Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: AquaShrimp on September 21, 2006, 05:54:43 PM
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Lets say its January 1943. Using existing technology, how could the P-47 have been transformed into a better plane?
Heres my take. I think the P-47 was far too heavy, and had too low of a critical mach to achieve the potential that it had. Heres what I would have done-
Stressed Aluminum skin- Would have saved weight.
Remove machine gun armament and replace with two 20mm cannons- Would have saved weight, and could have carried alot of 20mm ammo.
Thin, laminar flow wings- High altitude escort fighters needed to be able to fly and dive fast. This would have helped increase the critical mach.
Squared off wingtips- Improves roll rate.
Basically anything to save weight would have been my goal. Increasing internal fuel supply, and having stations for drop-tanks would be a necessity too.
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In doing so you also would have neutered the best jabo the US had in it's inventory...
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The P-47 was relegated to ground attack work because of its short-commings.
But would it have really be neutered? Cannons were far superior to machine guns in ground atttack work. In one Korean War test, twenty 50 caliber rounds and twenty 20mm rounds were each fired into a seperate truck. The 50 caliber rounds merely broke the drivers seat, while the 20mm rounds exploded the vehicle.
Stressed skin has been mentioned a few times to be more fragile than non-stressed, but I've never seen any confirmation of this.
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Hi Aquashrimp,
>Lets say its January 1943. Using existing technology, how could the P-47 have been transformed into a better plane?
Re-design it around a Merlin engine ;-)
>But would it have really be neutered?
Not at all - your suggestions make sense, except for the "stressed skin" bit because the P-47 actually was of stressed-skin construction historically.
>Stressed skin has been mentioned a few times to be more fragile than non-stressed, but I've never seen any confirmation of this.
German gunnery tests in WW2 confirmed this quite clearly. If the skin is not a load-bearing part, you can afford to lose the skin without any ill effect on the structural integrity of the aircraft. However, that means you're technologically back to the fabric-over-steel-tubes days of WW1, and end up with a much heavier plane for the same job, so it's not a realistic option.
The Hurricane started off with that technology, but got stressed-skin wings as soon as possbile. Its old-fashioned fuselage reportedly stood up well against cannon shells, but compare the Hurricane's weight to the Spitfire's, and you'll see the price paid for that.
>Cannons were far superior to machine guns in ground atttack work.
It's the same in air combat, especially if you use high-explosive shells against stressed-skin aircraft. The problem with the cannon was that the USA had a lot of reliabiilty problems with their version of the Hispano cannon.
One idea on how to boost P-47 performance: Replace the turbo-supercharger by a mechanically-driven one :-) Heresy, I know, but if you accept you're going to use it as ground attack aircraft anyway, the mechanically driven one is going to be a lot lighter, yield close to the same power and add a lot of exhaust thrust to the propeller thrust if you're going really fast.
(If you want to use it as an esort fighter, better stay with the turbo, though.)
Regards,
Henning (HoHun)
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It already had a very good roll rate, and was aluminum skinned, so I dont see either of those being a real issue.
For armament, 20mm weight savings would have been negligable, and its firepower was of course, very good. You have to get into the whole history of USA fighter armament in WW2, it was decided to stay with the 50s for a number of reasons, I wont get into all that right here. It certainly would not have been some light weight fighter being rearmed with 20mm.
Critical mach?, I have read nothing that indicated it was not able to dive very fast, and in fact, I doubt any fighter in the ETO could escape a P-47 by diving away.
Its top speed was over 425mph at alt, so again, im not sure what the wing design and mach issue is your talking about.
The reason it was superseded by the P-51 in the 8th AF was range, past that it was highly regarded as an escort fighter.
I am in no way saying it didnt have its drawbacks...or going on some P-47 super-rant-a-thon, all designs were compromises, but a lot of the issues you posted were never really problems for it.
Increase its internal fuel load, and its powerplant, would have been obvious improvements for it, but like the P-38, the Mustang came along at a time that it was decided to use it instead.
Btw, the 56th FG served untill wars end in the escort role with P-47s.
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Well,
Considering that the P-47 was an evolutionary developement of the earlier Seversky P-35, P-41, and Republic P-43 fighters, the sweeping changes that you are proposing would have been just about impossible from a manufacturing point of view.
Seversky (later Republic) designed and built their aircraft using technology and techniques that while outdated from a hindsighted point of view, used quite familiar and proven solutions to them.
Also consider that most cutting-edge military technologies and manufacturing techniques were, and still are proprietary and highly secret, and most military aircraft manufacturers of the time were competing with one another for contracts, and were very reluctant to share ideas.
The changes you are proposing would have required almost a complete re-design of the entire airframe, not just the wing structure, and even if the designers had chosen to use the same basic external shapes, the inside structures would not have been those of a P-47. This would have meant delays due to sub-contracting for new components and assemblies.
In addition, the changes would have meant shutting down the existing plants to re-tool, or even the construction of new plant space. More delays.
The changeover would also have required the production of expensive new manufacturing jigs and tooling under wartime conditions of shortages...not an easy thing to do, and probably would have meant even more delays.
After the plants were built, you would have to either transfer existing plant workers or train new workers to man them. Slowing current production and adding more delays.
Finally, after all that expenditure of capital, time, and effort, what do you have...an unproven design using new, unproven technologies, and probably costing much more than further evolutionary developement of the existing P-47 airframe design would have provided (P-47N).
As far as armament goes, those decisions were made and specified by the military, not the manufacturers. Also the weapons themselves were supplied by the military, often after the delivery of the aircraft, and not by the manufacturer.
I'm sure many firms would have been more than happy to provide the Armed Forces with aircraft designed to mount multiple 20mm canon, but the U.S. Military in 1943 was quite happy with an armament of four, six, or eight .50 cal machineguns, of which they had plenty, and which cost much less to build than licensed Hispano-Suizas or Oerlikons.
Wishful thinking I'm afraid.
CptA
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Hi Squire,
Good comments on the history, and I'd add Republic's own line of tried high-speed airfoil designs that they were probably not going to ditch for a yet unproven laminar airfoil. (North American had no tradition of high-speed aircraft, which meant lack of experience but also lack of "cultural inertia".)
There are two points I have to disagree with, though:
>For armament, 20mm weight savings would have been negligable, and its firepower was of course, very good.
Weight savings would have been considerable, and the firepower could have been far better:
4x Hispano II - 154 rpg - 352 kg - 187% firepower
8x ,50 Browning M2 - 375 rpg - 562 kg - 100% firepower
(Using total energy calculation.)
You could have saved 210 kg (463 lbs), which is a lot even for a heavy fighter like the P-47, and almost doubled firepower while doing so.
>Critical mach?, I have read nothing that indicated it was not able to dive very fast, and in fact, I doubt any fighter in the ETO could escape a P-47 by diving away.
According to Eric Brown (who did the testing), it did indeed have a rather low critical Mach number and was retrofitted with dive recovery flaps. It accelerated extremely quickly in a steep dive, but got out of control at moderately high speeds. Spitfire, Mustang, Fw 190 and Me 109 all could reach higher Mach numbers.
Regards,
Henning (HoHun)
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Hi Cpta,
Very good points! :-) Thanks for your post!
Regards,
Henning (HoHun)
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Edit: Found the answer.
The weight savings of the P-51H over the P-51D were due to thinner skin made out of an alloy. Empty weight savings were 600lbs.
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you described a P51 there...... :p
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give the wings about 2-3 degrees of washout, vortex generators, winglets, outboard LE slats; set the 'pit back a couple feet more to increase critical Mach number; Q-tip prop & add a spinner over the prop hub
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A description of the P-47 wing and fuselage design:
http://rwebs.net/avhistory/history/p-47.htm
As far as dive speed, @600mph TAS seems to be most oft quoted, but in any event, it could accelerate fast in a dive, enabling it to catch and shoot down enemy fighters attempting to flee in that fashion (important in an escort fighter), as far as absolute critical mach, I would charaterize it as "fast enough" even if it wasnt the absolute fastest.
50 cal vs 20mm weight savings is about 3 percent of its loaded weight of @14000 lbs, as for the whole 20mm vs 50 cal thing, its been debated to death, and im not going to redo it in this thread. Overall I think Hispano Vs would have been a better choice (ala the Tempest), but its not what the USAAF was issued in WW2.
Looking at the P-47C and the P-47N, I think they did what they could with the design, for the most part, save the upgunning it to cannon.
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Hey, I found something interesting. They *did* make a lightweight P-47!
The fastest version of the Thunderbolt was the XP-47J, which was proposed in November 1942 as a lighter-weight version of the Thunderbolt designed to explore the outer limits of the design's basic performance envelope. The XP-47J was fitted with a 2800 hp Pratt and Whitney R-2800-57(C) housed inside a close-fitting cowling and cooled by a fan. The ventral intake for the CH-5 turbosupercharger was separated from the engine cowling and moved aft. The four-bladed propeller was fitted with a large conical-shaped spinner. The wing structure was lightened and the armament was reduced from eight to six 0.50-inch machine guns. The contract was approved on June 18, 1943.
Maximum speed of the XP-47J was 507 mph at 34,300 feet, range was 765 miles at 400 mph, 1070 miles at economical cruising speed. An altitude of 15,000 feet could be reached in 4.5 minutes. Service ceiling was 45,000 feet. Weights were 9663 pounds empty, 12,400 pounds normal loaded, 16,780 pounds maximum. Wingspan was 40 feet 11 inches, length was 33 feet 3 inches, height was 14 feet 2 inches, and wing area was 300 square feet.
So it appears this P-47J is something close to what I envisioned.
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Originally posted by AquaShrimp
The P-47 was relegated to ground attack work because of its short-commings.
Wrong.
The P-47 was relegated to ground attack due to it's survivability over the inline engined aircraft. As the war progressed, the Mustang came on line as the D and took over escort role, giving even more freedom to the 47 to ground attack, but it never gave up the escort role entirely. The 51 also suffered high casualty rates when on the deck due to the exposed coolant system as opposed to the 47's record.
Originally posted by AquaShrimp
But would it have really be neutered? Cannons were far superior to machine guns in ground atttack work. In one Korean War test, twenty 50 caliber rounds and twenty 20mm rounds were each fired into a seperate truck. The 50 caliber rounds merely broke the drivers seat, while the 20mm rounds exploded the vehicle.
I completely disagree. The cannon may have heavier hitting power, but it has less range, and less "lead on target".
As for your statement regarding a truck, provide data. Have you ever seen the effects of a .50 round impact????
Originally posted by AquaShrimp
Stressed skin has been mentioned a few times to be more fragile than non-stressed, but I've never seen any confirmation of this.
LOL, the stressed skin is way better over the tube structure you advocate. It cuts weight massively by removing the steel tube frame, and provides a "hull" that can literally take damage all over and survive.
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as far as the guns go there isnt nothin wrong with the 8 50s and i prefer them over the 4 cannons. more ammo faster fire rate. Have u ever hita wing with all 8 50s , like butter. Hispanos are also knocked out by weak weapons easly were as i have been in a jug and token alot of hits in the wing with all my guns working. But this is all from aces high and not real life. If it aint broke dont fix it, those 50 calibre guns were on everythin and they got the job done.
Just my 2 cents.
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First off, Bodhi, Nice to see that quote is still in SOMEONE's signature, ;)
And I like the idea of cannons. With a good gunner, Id say it would be much more lethal. 'specially if they were '30s!
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Historically cannon were considered to have 50% to 200% the range of MGs. They got in close for MGs, but with cannon had the same hitting power much further out.
That is, at least on non-evading bombers. Nimble fighters present other problems.
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I'm afraid that AquaShrimp needs to bone up on his history...
When it came to performance, the P-47 ruled the roost at high altitude. Moreover, that's exactly where it was designed to fight. While the Merlin powered P-51Ds were on the back side of the power curve at 25,000 feet, the P-47 was just beginning to hit its stride. Nothing in the ETO was as fast as the P-47s above 30,000 feet. Up there, its excess power made it feel positively agile, and its acceleration and climb rate up that high was without peer. Seriously, the R2800-59 engine was making 2,300 hp at 31,000 feet! Compare that to any other in-service fighter and you'll see that this is about 1,000 hp better than any of them, and that's for a B series R2800. The C series engines generated 2,800 hp at 32,600 feet!! The fastest fighter in squadron service as of April 1945 was the P-47M, able to reach up to between 475 and 480 mph at 32,000 feet and 370 mph at sea level. Even the heavier, long-range P-47N could flirt with 470 mph.
As to a "low critical Mach", that is simply baloney. Max permitted dive speed was exactly the same as that for the P-51D, with its laminar flow wing; 500 mph IAS @ 1g. Jugs were able to exceed 600 mph TAS without damage. Indeed, one P-47D was dive tested post war over 200 times, with all dives exceeding Mach .77, and some reaching Mach .83 without problems or issues. I've posted some of the original flight test data on my website. IIRC, the P-47's critical Mach was actually higher than that of the P-51.
As others have noted, the P-47 was a stressed-skin design. The P-47N did get squared-off wing tips, which did improve its already excellent rate of roll, but only above 300 mph. I have seen data that attributes roll rates between 82 and 90 degrees/second for the various P-47s.
By 1944, all P-47s could carry three external drop tanks. In the Pacific, P-47s were frequently flown with 160 gallon P-38 drops tanks, and sometimes carried another 75 gallon tank under the belly. With the arrival of the P-47D-25-RE, the Jug had the range to reach Berlin. When the P-47N came into service, it was THE longest ranging single-seat fighter on the planet... Even better than the P-51D. Just on internal fuel, the P-47N had a range of 1,700 miles. Add another 395 gallons externally and it had the ability to fly nearly 2,600 miles. In 1944, Republic demonstrated the ability of the P-47N by flying one from Long Island to Eglin Field in Florida, where it then flew mock dogfights with another Army fighter. After this was concluded, it then flew back to New York, all without landing. How's that for range? That was a 1,930 mile flight, with 20 minutes at MIL power and 5 minutes in WEP included. When it finally landed, it had enough fuel remaining to fly up to Boston and still have a 30 minute reserve....
No one thought that eight .50 caliber Brownings were inadequate, because they were more than enough for its mission. Those 8 guns could put out 6,000 rounds per minute, a rate of fire on par with the M61 rotary cannon in service today.
Your statement that the P-47 was relegated to ground attack because of its "short-comings" is... well, simply uninformed.
P-47s were used for ground attack and close support because they were far more durable than the liquid-cooled P-51s. They could absorb much more damage and fly home. Of all USAAF single-engine fighters, the P-47 had the lowest loss to sortie ratio, and by a significant margin too.
Some rather well credentialed aviation historians have stated that while the P-38 was first to take the air war deep into Germany, and the P-51 finished off the already mauled and depleted Luftwaffe, it was the P-47 that broke its back. Jugs had already killed off a significant portion of the Luftwaffe's west-front experten before the P-51s arrived in any significant numbers.
P-47s continued to fly escort missions until the surrender. Flying with the 8th AF, the 56th FG simply refused the Mustang and produced the highest scoring aces in the ETO. 9th AF P-47s flew escort for B-26s right up through April of 1945, when most B-26s stood down for lack of targets.
The whole premise of your argument is that the P-47 was somehow inferior and needed to be redesigned. Clearly, that is false. Neither the USAF, RAF, Lufwaffe or the Japanese thought that the P-47 was inferior. They all recogized that it was the best high altitude fighter of the war, and it got better with each new update. Indeed, the ultimate derivative of the P-47 was the XP-72, powered by a 3,300 hp, 28 cylinder R-4360 engine. This Super-Jug, was able to attain 490 mph, running at reduced manifold pressure (and 415 mph at sea level). A production order was cancelled as being unneeded, and Republic received a contract for design and development of the XP-84 Thunderjet instead. Nonetheless, the P-72 was expected to be a true 500 mph fighter.
Now, to futher your education, I suggest that you read this 8 part article (http://home.att.net/~historyzone/Seversky-Republic.html) on the design, development and operations of the P-47.
My regards,
Widewing
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Great post Widewing!!
Only that the P47 was the best high alt fighter in WWII may not be true, cause speed isnt all in high alt!! There was other high alt fighters with a much better turn performence and a still very good speed and climb(Ta152H, SpitIXc Merlin67 extended wing for example), but for sure the P47 was very good and not that rare! The only disadvantage was its high fuel burn rate, probably the only real advantage of the P51 over the P47.
Greetings,
Knegel
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"I completely disagree. The cannon may have heavier hitting power, but it has less range, and less "lead on target". "
Less range? Actually more effective range, especially if you had Minengeshoss ammo which hitting power was not dependent of range.
I think 8 .50 cals was perfect for ground work the Jug did. Lot of scattered damage and thus more hits because the firing times are short. Also the penetration is practically almost similar to 20mm AP.
-C+
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Hi Squire,
>As far as dive speed, @600mph TAS seems to be most oft quoted
Hm, I don't believe that's anywhere near realistic as that Mach 0.79 at sea level (and more higher up) - far in excess of the critical Mach number of the P-47. It might be that it's a "straight" conversion from an actual airspeed indicator reading, but these are not too accurate at very high speeds.
Mach 0.79 was the limit for the Me 109, and close to the limit for the P-51 and the Fw 190, but the P-47 couldn't even get near it.
>50 cal vs 20mm weight savings is about 3 percent of its loaded weight of @14000 lbs
It should be appreciated that in aircraft design, 3% of the loaded weight is a biggie.
I've got a weight and balance chart for the P-47 here that indicates 1830 lbs maximum internal fuel. You can increase fuel load and thus endurance by 25% by going to four cannon, and the impact on practical range is actually even greater than that.
Besides, four cannon were the "luxury" version of weight saving because they virtually doubled firepower. If you're going for a lean P-47, you might go for a 2-cannon-setup with the following characteristics:
2x Hispano II - 308 rpg - 252 kg - 94% firepower
For a neglegible drop in firepower, you'll save 310 kg weight, or 684 lbs.
>Overall I think Hispano Vs would have been a better choice (ala the Tempest), but its not what the USAAF was issued in WW2.
Certainly, 2 x Hispano V would actually yield more firepower than 8 x 0.50", but as the Hispano V was only used late in WW2, I thought the Hispano II was a more realistic comparison.
Regards,
Henning (HoHun)
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A few remarks:
The biggest problem of the P47 was range. It was constantly increased with more and bigger DT and the addition of an AUX tank, bigger tanks and eventually wet wings in the P47N.
The way to improve the P47 and over come the weight problem was more power. The paddle blade prop contributed to the efficiency of transforming engine power to thrust adding about 500 FPM to climb rate. The hotrod P47-M was not such a great improvement over the 56th FG Jugs as they already had their engines over boosted reaching close to the M,N engine's output. And that was in lighter better stream lined razorback models way before the M was developed. Johnson repeatedly claimed that his P47 was boosted to 72".
If it would have been designed as a ground attack plane it would have used a gear charger and save a lot of weight and complications. However, what made it a superior high alt fighter (its real purpose) was its distinctive feature - the supercharger. The plane was literaly designed around it.
The crittical mach numer is not what matters, it's how you reach that number. The P-51 was a very fast diver but it's handeling was problematic. At certain speed the stick forces would reverse and if the pilot was not ready for it, it would slam the stick into his belly and risk breaking the plane. Other planes would buffet or suffer early degregation of control. The P47 handeled very well right up to the critical mach where the stick would freeze. Not to mention the superior dive acceleration meaning you cover more distance before reacing max speed.
Bozon
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Hi,
Hohun always forget that hitpower while a aircombat and specialy while escort missions often is less important than hitprobability.
The .50 cal was good enough vs Fighters, 8 x 13rps will have a better probability to hit than 2 x 11rps or 4 x 11rps, specialy with so far outside placed guns and so a smal range of convergence. One time 104 rps fly toward the target, the other time 22rps or 44rps. Also cannon shels are not always HE, the 20mm AP dont cause much more damages on a Fighter than the .50cal and the smaler armament need relative more tracer rounds.
While groundattacks it simply depends to the targets, vs groups of soldiers and unamned vehicles the 8 x .50 cal was probably the better weapons, similar to cluster bombs, while vs light armored vehicles (halftracks etc) and groundobjects (AAA and Flak) the 20mm was better, vs Tanks both guns was rather uneffective.
Imho vs smal and or nimble targets the armament with smaler guns is good, while vs big or slow moving targets the bigger guns armament is better, despite the much smaler rate of fire.
More guns also provide a better reliability(smaler probability to jam all guns) and was the P47 wing able to handle 4 x 20mm without to make it more tough(more weight)??
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The P-47 easily "could have" had 2 x 20mm in each wing, just look at the Tempest, and, for that matter the Spitfire XIV, which had bays for 2 x 20s in each wing, although the second 20 wasnt mounted. It wasnt a case of couldnt.
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M model. hmmmmmmm, say here that there were 130 built, i wonder if AH would do it, it say here that it was a moded d so it should be hard to do.
I dont know whats the big deal about the cannons. 8 50s, thats a strong gun package. i have snap shoted cons to death with the 4 of the p51b, now double it.
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Originally posted by HoHun
Hi Squire,
>As far as dive speed, @600mph TAS seems to be most oft quoted
Hm, I don't believe that's anywhere near realistic as that Mach 0.79 at sea level (and more higher up) - far in excess of the critical Mach number of the P-47. It might be that it's a "straight" conversion from an actual airspeed indicator reading, but these are not too accurate at very high speeds.
Mach 0.79 was the limit for the Me 109, and close to the limit for the P-51 and the Fw 190, but the P-47 couldn't even get near it.
This is incorrect. See below.
(http://home.att.net/~Historyzone/DiveChart.JPG)
This was a fully instrumented aircraft (Mach meter and data probe, including calibrated strip chart recorder). It attained Mach .83 on several dives and it was not fitted with dive recovery flaps.
Typically, a P-47 diving at the allowed limit of 500 mph IAS at 12,000 feet is doing 601 mph TAS, or Mach .82, and this was the placarded limit. It was often exceeded in combat. Mach .82 is well into compressibility, but there's no doubt that the P-47 was capable of these speeds.
Bf 109s and Fw 190s were unable to escape from P-47s, even in prolonged dives.
My regards,
Widewing
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Hi Widewing,
>It attained Mach .83 on several dives and it was not fitted with dive recovery flaps.
Quite impressive! Especially if no dive recovery flaps were used. Makes me wonder why they were considered necessary at all, though.
Was the aircraft configuration in fact representative for a WW2 aircraft? I'm just asking because the chart seems to indicate a 1949 test date, and there would have been ample of time for the airframe to receive modifcations. On the other hand, there might not have been that much reason to modify the type once the war was won. What were the objectives of the tests, by the way?
>It was often exceeded in combat. Mach .82 is well into compressibility, but there's no doubt that the P-47 was capable of these speeds.
Hm, it would be interesting to have a look at the development history since I've seen a couple of texts that seem to suggest quite clearly that at least the early Jugs were troublesome. Here's what Eric Brown wrote:
"About the beginning of 1944 reports begang reaching the RAE of Thunderbolts diving out of control from high-altitude combat, and eventually in March of that year a P-47D was seconded to RAE Farnsborough from the US Eight Air Force for investigation, since it was suspected that the cause was compressibility induced, and the RAE was at that time heavily involved in researach in the transonic flight range.
[...]
Before the next flight, a Machmeter was fitted to the aircraft, and as instructed I climbed to 35,000 ft, carried out a 2 min level run at full power and trimmed the aircraft before pushing over into a 30 degree dive. At Mach=0.72, the aircraft begang to buffet slightly and pitch nose down, requiring a strong pull force to maintain the dive angle. At Mach=0,73 the buffetting increased severely and the nose-down pitch was so strong that it needed a full-blooded both-handed pull to keep the dive angle constant. I had to hang on grimly in this situation, unable to throttle back until Mach number decreased as altitude was lost. The pull-out was not effected until 8,000 ft. Analysis showed that a dive to M=0.74 would almost certainly be a 'graveyard dive'.
I have only subsequently experienced such severe compressiblity nose-down pitch effects in two other aircraft, the Messerschmitt 163B and the Gurmman F-8F [sic!] Bearcat."
(From "Testing for Combat".)
From Brown's tests, a recommendation to fit dive recovery flaps to provide a nose-up pitch moment resulted. Apparently, they were fitted to most P-47D aircraft as recommended.
>Bf 109s and Fw 190s were unable to escape from P-47s, even in prolonged dives.
If the P-47 could be dived to Mach 0.82, it certainly was faster than the Bf 109. I don't know about the exact absolute maximum speed of the Fw 190, but it's my impression that it was tested to Mach 0.80 at least.
Regards,
Henning (HoHun)
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Hi Squire,
>The P-47 easily "could have" had 2 x 20mm in each wing, just look at the Tempest, and, for that matter the Spitfire XIV
Absolutely! Just look the P-51 which was designed for four machine guns in each wing, and fitted with four Hispano cannon without much ado.
The Hispano II was a long-recoil weapon anyway that generated relatively low recoil forces, and as the 4 x Hispano II installation was in fact considerably light than the 8 x 0.50" installation, the P-47 could have been converted easily.
Regards,
Henning (HoHun)
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Hi Bozon,
>The biggest problem of the P47 was range. [...] The way to improve the P47 and over come the weight problem was more power.
Hm, the problem is that with the "1943" approach, we can't use the power that only became available gradually due to progress in engine and supercharger technology from the beginning.
Weight did indeed directly counteract range. The "Breguet" range equation does in fact feature the ratio of loaded weight to empty weight in an important role, and if you accept that any weight saving could be used to carry extra fuel, Aquashrimp's concern about weight is indeed a very valid one.
>If it would have been designed as a ground attack plane it would have used a gear charger and save a lot of weight and complications. However, what made it a superior high alt fighter (its real purpose) was its distinctive feature - the supercharger. The plane was literaly designed around it.
Hm, I'm not so sure that this would withstand a technical analysis. The important thing about the turbo-supercharger was the intercooler, and two-stage mechanically-driven superchargers were quite effective at high altitudes, too, if adequate intercooling was provided.
The turbo-supercharger in fact improved engine efficiency, but not necessarily peak output - while it had more shaft power, the extra exhaust thrust at high power settings might have more than compensated for that. (At least, DVL research reached this conclusion, of course in a generalized fasion.)
While the mechanically-driven two-stage supercharged P-47 would have been less efficient, it might have been able to use the rear fuselage location of the turbo-supercharger for an extra fuel tank to compensate for the poorer efficiency or maybe even surpass the turbo-supercharged version.
(I'm not saying it would - but I think one would have to run a very close analysis before one could tell for certain which version was longer-ranged. I suspect this was not actually done in WW2 since until the second Schweinfurth raid, fighter range was considered to be of secondary importance by the USAAF.)
>The P-51 was a very fast diver but it's handeling was problematic. At certain speed the stick forces would reverse and if the pilot was not ready for it, it would slam the stick into his belly and risk breaking the plane.
Hm, I believe you must be thinking of the turn behaviour with a full fuselage tank. The symptom in dives was increasingly violent buffeting and a loss of control effectiveness.
If you look at Brown's description above, the P-47 suffered from that at lower speeds than the Mustang, and added a dangerous nose-down change of trim on top of that.
Regards,
Henning (HoHun)
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Hi Bodhi,
>The P-47 was relegated to ground attack due to it's survivability over the inline engined aircraft.
Hm, according to what I have read about the USAAF's decision making progress, the thing that concerned the top brass was range, and the P-47 was in fact considered inferior to the P-51 in that respect, which seems to have been the primary motivation for the change-over of the 8th Air Force to Mustangs.
However, I have not seen a good account of that in the history books, with a timeline of reports and orders to document that decision, so I don't consider that a "verified opinion".
My impression is that the good points of the P-47 with regard to ground-attack capabilities were emphasized when the 9th Air Force received the Jugs in an act of good leadership.
I'm not sure that we can actually tell for certain that the P-47 was in fact superior to the P-51 as I'm not aware of any truly useful loss statistics. Not to say the P-51 was actually as good as the P-47, but you might have read the threads on the B-17 vs. B-24 and the Navy aircraft toughness discussion (in which the SBD emerged as the true champion) - my conclusion was that we should try to check the reliability of reputations whenever possible :-)
>I completely disagree. The cannon may have heavier hitting power, but it has less range, and less "lead on target".
Hm, you don't want to hit the target, you want to knock it down. The actual killing power is determined by the product of the number of hits and the destructiveness of each round.
As the destructiveness of each round can be considered to be roughly equivalent to its total energy (kinetic and chemical), you can actually calculate the hitting power, and for a battery of a given weight, cannon generally come out superior because their larger shells can carry a greater amount of chemical energy.
>As for your statement regarding a truck, provide data. Have you ever seen the effects of a .50 round impact????
Here is an interesting statement regarding the opinions at the time, quoted from "Flight Journal Special, Winter 2000" and referring to the Joint Fighter Conference:
"In Monroe's discussions, it became apparent that the British and the U.S. Navy were in the process of making a switch from .50-caliber guns to 20mm cannon. The principal reason was that although the 20mm cannon had a slower rate of fire, it put out more weight of metal than the .50-caliber gun in a given time, and it did not jam during a 20-second, full-load burst."
(The Army opposed this switch vehemently. It was a flame war even back then ;-)
The Army at that time favoured the .60" machine gun, an adaptation of the German MG151. Just for fun, here the comparison between two such batteries for the P-47:
6x MG 151 - 298 rpg - 578 kg - 116% firepower - firepower per weight: 113%
8x ,50 Browning M2 - 375 rpg - 562 kg - 100% firepower - firepower per weight: 100%
As you can see, the difference is rather small, so it's not suprising the .60" MG never replaced the proven .50" Browning.
Regards,
Henning (HoHun)
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I wouldnt have wanted to take any of them to those speeds, it must have been a dizzying ride, plummeting earthwards at that rate in those things, I guess survival in war makes one do what one has to.
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Originally posted by HoHun
Hi Widewing,
>It attained Mach .83 on several dives and it was not fitted with dive recovery flaps.
Quite impressive! Especially if no dive recovery flaps were used. Makes me wonder why they were considered necessary at all, though.
Was the aircraft configuration in fact representative for a WW2 aircraft? I'm just asking because the chart seems to indicate a 1949 test date, and there would have been ample of time for the airframe to receive modifcations. On the other hand, there might not have been that much reason to modify the type once the war was won. What were the objectives of the tests, by the way?
>It was often exceeded in combat. Mach .82 is well into compressibility, but there's no doubt that the P-47 was capable of these speeds.
Hm, it would be interesting to have a look at the development history since I've seen a couple of texts that seem to suggest quite clearly that at least the early Jugs were troublesome. Here's what Eric Brown wrote:
"About the beginning of 1944 reports begang reaching the RAE of Thunderbolts diving out of control from high-altitude combat, and eventually in March of that year a P-47D was seconded to RAE Farnsborough from the US Eight Air Force for investigation, since it was suspected that the cause was compressibility induced, and the RAE was at that time heavily involved in researach in the transonic flight range.
[...]
Before the next flight, a Machmeter was fitted to the aircraft, and as instructed I climbed to 35,000 ft, carried out a 2 min level run at full power and trimmed the aircraft before pushing over into a 30 degree dive. At Mach=0.72, the aircraft begang to buffet slightly and pitch nose down, requiring a strong pull force to maintain the dive angle. At Mach=0,73 the buffetting increased severely and the nose-down pitch was so strong that it needed a full-blooded both-handed pull to keep the dive angle constant. I had to hang on grimly in this situation, unable to throttle back until Mach number decreased as altitude was lost. The pull-out was not effected until 8,000 ft. Analysis showed that a dive to M=0.74 would almost certainly be a 'graveyard dive'.
I have only subsequently experienced such severe compressiblity nose-down pitch effects in two other aircraft, the Messerschmitt 163B and the Gurmman F-8F [sic!] Bearcat."
From Brown's tests, a recommendation to fit dive recovery flaps to provide a nose-up pitch moment resulted. Apparently, they were fitted to most P-47D aircraft as recommended.
This P-47 was being used by Curtiss-Wright Propeller Division to test various blade designs in an effort to determine if they suffered structural failures under very high drag loads. Some blades were actually deformed during the testing. Curtiss was trying to design a prop that would have greater efficiency as an increasing portion of the blade went supersonic. In short, they were unable to gain any substantial improvement. They tried many blade designs, some extremely thin and others were scimitar shaped.
Aside from being heavily instrumented, this Jug was standard P-47D-30-RE loaned to Curtiss by the NY Air Guard. It was never upgraded to include dive recovery flaps. Fisher simply set trim for a pullout at 20,000 feet. According to Herb, he typically pulled 5g on pullout.
There were many incidences of P-47s diving straight into the ground. Often it was a result of not following procedure or ignoring the danger. Such accidents were certainly not limited to the P-47s. Aside from the P-38, the P-51 suffered the same problem. Naval fighters did also, but were seldom flown at the altitudes commonly seen in the ETO, so they suffered less. A big problem was that when the P-47 entered service, there was virtually no training concerning compressibility and how to coax a speeding fighter out of a dive. Pilots often used trim, but frequently rolled in too much trim, leading to sudden and fatal structural failures.
I'm rather amused that Brown takes credit for dive recovery flaps on the P-47. Especially when Republic had been working with NACA and Lockheed since early 1943 on this issue. I suspect he attributes too much credit to himself at times. Republic and the AAF was well aware of the problem with compressibility long before "the beginning 1944", as was every other manufacturer of modern fighters (Allied and Axis).
By the way, every F8F that left the factory was fitted with dive recovery flaps. After Grumman's Bob Hall and Corwin Meyer tested a dive recovery flap equipped P-38L and P-47D at the fighter conference, Hall went back to Grumman and ordered an engineering team to incorporate them into the Bearcat.
Herb Fisher was the only civilian to be awarded the USAAF Air Medal. He also flew a borrowed F8F-2 extensively, testing a reversable prop. He would dive from altitude and reverse the prop to reduce dive speeds. It worked, but the vibration was so severe he would nearly pass out.... Eventually Curtiss sorted out the propeller design and the vibration was greatly reduced. He would dive straight down from 30,000 feet and never exceed Mach .71, and still maintaining good control. Like many Curtiss projects, this one was moot because prop fighters were rapidly being replaced by the first generation jets.
My regards,
Widewing
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Whats with all this revisionist history here?
Where were the P-47s in 1942 and 1943 when U.S. bombers were getting mauled over Germany? They were returning to base due to insufficient range, thats where they were. P-47s would escort B-17s part of the way, the -17s would have to proceed on alone, and hopefully pick up some escort on the way back. Unacceptable, its one of the main reasons why the SBC had to halted.
All the high-altitude performance in the world won't save you if you're out of fuel. Drop-tanks are nice, but they do have to be dropped for combat. Any fuel left in them is thusly wasted.
Bodhi, I never advocated tubular steel framing for the fuse.
Widewing, I never said that the P-47 was a poor performer, I said that it didn't reach its full potential. Which is true, it was too heavy. By the time the P-47N came into service, the air war in the ETO was over. Alot of good that did!
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as soon as widewing breaks out the charts thats when the post has just become offical.:aok
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Originally posted by AquaShrimp
Widewing, I never said that the P-47 was a poor performer, I said that it didn't reach its full potential. Which is true, it was too heavy. By the time the P-47N came into service, the air war in the ETO was over. Alot of good that did!
Inasmuch as the P-47 was the fastest prop driven fighter to see combat in significant numbers, had the lowest loss ratio and the P-47N was the longest ranging single-engine fighter.... I'd say it reached it's full potential, hotrod prototypes excluded (XP-47J and XP-72).
As to the P-47N; it was developed specifically for service in the Pacific. There was never any intention to deploy it to the ETO. With that in mind, the P-47N saw extensive combat during the last 6 months of the war. Japan had nothing for it.
You need to understand that the P-47 was designed to an Army specification. It exceeded that specification. As the air war evolved, so did the Thunderbolt. Range issues in the ETO were generally overcome with the introduction of the P-47D-25-RE, which had greater internal fuel capacity. Nonetheless, from the P-47D-15 on, the Jugs had the range to fly beyond the Rhine. The 8th AF Thunderbolts so battered the Luftwaffe that they withdrew their fighters into Germany to avoid the massive horde of Thunderbolts. Very few P-47s were encountering the enemy before they had already pickled off their external tanks. The last thing the Luftwaffe wanted to do was go head-to-head with the P-47s, especially when the Jug escorts were numbering in the six to seven hundreds.
I'm sorry, but your analysis is flawed.
My regards,
Widewing
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I've got a question. If cannon were so "superior" to the Ma Deuce, why did the F-86 have them? And that is a question, not a flame.
We need more posts like this, instead of the usual...
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I've got a question. If cannon were so "superior" to the Ma Deuce, why did the F-86 have them? And that is a question, not a flame.
Because stupidty tends to linger around for quite some time even in face of overhwhelming counter-evidence.
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later versions did, the aussie F-86, considered by some the best of them, carried 30mm guns & a RR avon engine, iirc the US F-86h had 20mm guns, b ut then MiGs were begging for 'small' lol calibre pwnege so thats what teh they gotted
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Hi Stoney,
>I've got a question. If cannon were so "superior" to the Ma Deuce, why did the F-86 have them? And that is a question, not a flame.
As pointed out above, the Navy understood the advantage of cannon before the USAAF did, and it seems that as a result, there were considerable inter-service tensions because it was the Army that was in charge of developing aircraft armament. (At least, that's what the article on the Joint Fighter Conference in the abovementioned Flight Journal Special suggests.)
So it was sort of a "service tradition" that the USAF equipped the F-86 with machine guns only. Combat experience in Korea, while showing the general superiority of the USAF pilots over their adversaries and the capability of the F-86 to deal with the better-performing MiG-15, showed that the effectiveness of machine guns left a lot to be desired, especially as jets were tougher targets than propeller aircraft, as firing opportunities often were short due to the high speeds of the jets, and as the combat took place at very high altitude where it rarely happened that the jet fuel, less volatile than high-octane petrol to begin with, burst into flames from a lucky hit.
The USAF reacted by converting a handful of F-86 airframes to carry 20 mm cannon and sending them into combat in "Project GUNVAL", as the name suggests meant to validate the effectiveness of cannon. After GUNVAL, the 20 mm cannon become the standard armament of USAF fighters (and as far as guns are concerned, it still is today).
Regards,
Henning (HoHun)
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Hi Widewing,
Thanks for the additional information! :-)
>I'm rather amused that Brown takes credit for dive recovery flaps on the P-47. Especially when Republic had been working with NACA and Lockheed since early 1943 on this issue. I suspect he attributes too much credit to himself at times. Republic and the AAF was well aware of the problem with compressibility long before "the beginning 1944", as was every other manufacturer of modern fighters (Allied and Axis).
This is indeed a strange perspective! I guess it shows that even very specific accounts but well-known "historical figures" have to be read with great care :-/
However, to defend Brown's perspective, I have read that in the case of the P-38, the Air Force insisted that the diving problems were a flutter problem and not (as Kelly Johnson fully aware) compressibility-induced. Maybe there was a similar disagreement on the P-47, and the RAE's opinion was sought in order to tip the scales one way or the other.
>Aside from being heavily instrumented, this Jug was standard P-47D-30-RE loaned to Curtiss by the NY Air Guard. It was never upgraded to include dive recovery flaps. Fisher simply set trim for a pullout at 20,000 feet. According to Herb, he typically pulled 5g on pullout.
Hm, I guess "trim" is the key here. Brown mentioned that he trimmed the aircraft into the trim (something that is strongly discouraged or prohibited by many aircraft's manuals), so he probably was making a "bad case" dive to see if service pilots could get themselves killed if they made a mistake on initiating the dive.
Now that you have told me about the high mach limit, I noticed that Brown's article does not describe any of the Mach figures he gives as a "limit". I had noticed that in his books, he uses the terms "limiting", "critical", or "maximum tactically useful" Mach number, but there is no such qualifier for the Mach numbers he achieved in the P-47.
I guess that Eric Brown is not to blame, but that I misunderstood his article when I reached the conclusion that the P-47 was limited to Mach 0.73 without the dive recovery flaps!
Do you perhaps have the exact placard limits (and ideally, an airspeed calibration chart)? It would be interesting to compare it to the P-51's.
(I don't have an airspeed calibration chart for the P-51 either, but the placard limits, expressed in IAS, do not match the stated maximum of Mach 0.75 exactly, so the difference can be understood as result of the various instrument errors.)
Regards,
Henning (HoHun)
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It is interesting to note that the P-47 is thought to have the lowest loss rate of any WWII RAF service aircraft.
Used primarily as a ground attack aircraft, only 7 are known to have been lost to enemy action out of 825 delivered.
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I say stream-line it, give it low wings, two 20mm in the cowlings, 2 7.9s, one in each wing, give it a Daimler-Benz engine, a bright yelloy nose, and Iron cross on the side... in the end make it look kind of like the ones with one engine...:
(http://www.jg53.com/images/aircraft/bf109/bf109e-he11.jpg)
Naw, just joking. I think the Thunderbolt was good the way it was.
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Widewing, my analysis of the P-47 is wrong? I'm proved right by later prototype and production models of the P-47! If anything, you are confused.
I said the P-47 had too little range to be an escort plane. So did Republic, thusly the P-47N was developed.
I said the P-47 was too heavy and needed a lightweight version. So did Republic, thusly the P-47J was developed.
I said the P-47 had too low of a critical mach. So did Republic, thusly diveflaps were added, AND a laminar flow wing P-47 was tested (P-47K).
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Aquashrimp,
I really don't think you want to go there...
Prepare for the delluge of charts, specs, and more information that is going to teach us all something we didn't know, yet again...
:aok
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Originally posted by AquaShrimp
Widewing, my analysis of the P-47 is wrong? I'm proved right by later prototype and production models of the P-47! If anything, you are confused.
I said the P-47 had too little range to be an escort plane. So did Republic, thusly the P-47N was developed.
I said the P-47 was too heavy and needed a lightweight version. So did Republic, thusly the P-47J was developed.
I said the P-47 had too low of a critical mach. So did Republic, thusly diveflaps were added, AND a laminar flow wing P-47 was tested (P-47K).
Ok, it's obvious that you are unwilling consider that you were in error. So I'll merely point out where you have been wrong so far and present facts that disprove your conclusions.
You stated:
"I think the P-47 was far too heavy"
Fact: While heavy, the P-47 was not "far too heavy". It out-performed the fighters of the enemy. It's power loading at altitude was better than the P-51D. Its weight was mitigated by its enormous horsepower. At around 14,000 lbs, it was only marginally heavier than the Typhoon and Tempest, neither of which could match its performance above 20,000 feet (where the ETO air war was fought). It was 3,000 lb lighter than the P-38L.
You stated:
"had too low of a critical mach to achieve the potential that it had."
Fact: P-47s were the fastest, best climbing fighters at the altitude they were engineered to fight at. Late models were the fastest prop fighters to see combat in WWII, up to 40 mph faster than the P-51s. The P-47 had the exact same speed restriction as the P-51D; 500 mph IAS. We have data that shows the P-47 being capable of 600 mph TAS in a dive. Dive recovery flaps were installed because they made recovery easier. The P-51 was not fitted as it would have required a major redesign of the wing structure. Instead, North American changed the angle of incidence of the horizontal stabilizer on later models to reduce high Mach tuck. The F4U and F6F didn't have them because they seldom flew high enough to get into high Mach issues, meaning that they were not needed. As it was, neither the F4U or the F6F demonstrated severe tuck under at high Mach anyway.
Dive limitations for US fighters:
P-47D: 500 mph IAS
P-51D: 500 mph IAS
P-63A: 500 mph IAS
P-40E: 480 mph IAS
P-39Q: 475 mph IAS
F6F-5: 449 mph IAS
F4U-1D: 443 mph IAS
P-38L: 440 mph IAS
P-61A: 430 mph IAS
FM-2: 425 mph IAS
Recent testing by the Society of Experimental Test Pilots established that the military's ratings were accurate. They dive tested the P-47D-40, P-51D, F6F-5 and FG-1D. Their conclusion was that they ranked in the order I have listed them.
You stated:
"Stressed Aluminum skin- Would have saved weight."
Fact:
The P-47 was a stressed-skin, flush riveted monoplane, as advanced in structure as any aircraft of its time.
You stated:
"Remove machine gun armament and replace with two 20mm cannons."
Fact:
The USAAF did not want 20mm cannons on their fighters. Moreover, the eight-gun installation on the P-47 was more than adequate for the job it was designed to do. It simplified logistics and the Browning MGs were utterly reliable.
You stated:
"Thin, laminar flow wings- High altitude escort fighters needed to be able to fly and dive fast."
Fact:
There is much disinformation about the advantages of the laminar flow airfoils. Even North American admitted that there was no significant decrease in overall drag over 90% of the speed range. This was due to the air flow not remaining laminar as was originally thought. If you examine the wings of both the P-47 and P-51, you would notice that the chord to thickness ratio of the Thunderbolt's wing was less than that of the P-51D. That means that relative to the width of the wing, the P-47's wing was thinner than that of the P-51. Max dive speeds are limited as much by drag rise of the propeller as by the drag rise of the wing itself. At Wright Field in July of 1944, a shiny new P-51D was dive tested at gradually increasing speeds. Initial buffeting began at Mach .75 and gradually increased as speed went up. Eventually, they dived it to Mach .83, but did such damage to the plane that it was written off. In contrast, the immensely strong P-47 could survive repeated dives to Mach .83 without injury to the airframe.
You stated:
"Squared off wingtips- Improves roll rate"
Fact: Neither of the two fastest rolling fighters in the US inventory, the P-63 and F4U, had squared wingtips. Aileron design is the greatest factor, not whether the wingtip is squared or radiused. Read this NACA test report:
(http://naca.larc.nasa.gov/reports/1947/naca-report-868/03.gif)
You stated:
"The P-47 was relegated to ground attack work because of its short-commings."
Fact:
Already mentioned that this statement is uninformed. General Elwood "Pete" Quesada commanded the 9th AF in the ETO. Originally, the 9th AF was to be assigned P-51B fighters (based upon the out-moded idea that the A-36 was very effective...It wasn't). However, the 8th AF wanted the Mustangs. That suited Quesada just fine. He asked for every P-47 he could get. Why? Because Quesada saw that the A-36 loss rates were 4 times that of P-47s in MTO operations. After the war, Quesada was asked why he preferred the Thunderbolt over the P-51. He replied, "because we knew that without a shadow of a doubt that our losses would have been far greater had we been flying the P-51. P-47s brought my men home."
P-47s were assigned to this role because it was the best aircraft for the job.
Now, you just made these statements:
"I said the P-47 had too little range to be an escort plane. So did Republic, thusly the P-47N was developed"
You were wrong... Now you sound like your opinion somehow enlightened Republic and they built the P-47N just to prove you right. Had you bothered to educate yourself prior to making your initial post, you would have recognized that the P-47 had adequate range by 1944 and was the longest ranging single-engine fighter of the war by late 1944. You can't backtrack like that and expect to get away with it.
"I said the P-47 was too heavy and needed a lightweight version. So did Republic, thusly the P-47J was developed."
Again, you are backtracking.... LOL.. The XP-47J was a prototype, basically a technology demonstrator. It was rejected by the USAAF as not meeting their needs. In addition, it was actually
heavier than the P-47C-5 and had a greater fuel burn rate. With the same fuel capacity as the C models thru the D-23, it offered no improvement in range. As an interceptor, the XP-47J would have excelled, but it was no improvement as an escort fighter.
"I said the P-47 had too low of a critical mach. So did Republic, thusly diveflaps were added, AND a laminar flow wing P-47 was tested (P-47K).
"
Dive flaps were added, but not because the P-47 had a low critical Mach. They were added because the P-47 flew extremely high, where compressibility was a major issue for ALL fighters. Due to the P-47's extreme dive acceleration, pilots could get into compressibility trouble very quickly. These flaps were installed on the F8F, and not because it had a low critical Mach, but because they reduced the risks associated with high speed dives. Not all designs could readily accommodate the flaps. The P-51 couldn't and a different approach was taken by North American as stated previously.
Finally, the XP-47K did not fly with a laminar flow wing. This fighter was modified to test the new "bubble" canopy. Later, it was used as the second test bed for the enlarged wing eventually used on the P-47N (with internal fuel tanks). This wing used the same Republic airfoil section as previous P-47s.
Now, you can keep insisting you are correct, but we have established that you are lacking in the facts. Arguing in circles won't reverse this. Had you gone back to 1941 and XP-47B, some of your points would have been viable. However, by late 1943, the P-47 had established itself as the premier high alt fighter on the planet.
My regards,
Widewing
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Originally posted by Widewing
At around 14,000 lbs, it was only marginally heavier than the Typhoon and Tempest, neither of which could match its performance above 20,000 feet (where the ETO air war was fought).
not a very good comparison as both the Typhoon and Tempest excelled at low altitude work.
similarly the P-47 could not match their performance below 20,000.
besides, marginally heavier? its a good 4,000lb or so heavier than both.
TA-152 would have been a better comparison as it is heavier than the Hawkers and also designed as a high altitude fighter.
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Originally posted by Furball
not a very good comparison as both the Typhoon and Tempest excelled at low altitude work.
similarly the P-47 could not match their performance below 20,000.
besides, marginally heavier? its a good 4,000lb or so heavier than both.
TA-152 would have been a better comparison as it is heavier than the Hawkers and also designed as a high altitude fighter.
We all know that these aircraft were developed for different missions, although the Typhoon was designed initially as an interceptor, at which it failed miserably. Fortunately, the airframe was engineered well enough to be adapted to the low level and attack mission, at which it excelled.
My point was that while the P-47 was a heavyweight, it was not a great deal heavier than some of its comtemporaries (Tiffie, Tempest, F6F, etc). A loaded Ta 152 was more than a ton lighter (around 11,500 lbs) than loaded Typhoon. But, of more importance was the fact that the Ta 152H was a non-factor, with perhaps a dozen seeing combat in the last weeks of the war.
Typically, a P-47D-22 weighed about 15,000 lbs loaded, while the Typhoon Mk.IIb weighed in just below 14,000 lbs when fully loaded. Empty weights were roughly 9,900 lbs vs 8,800 lbs.
My regards,
Widewing
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Hi Widewing,
>Dive limitations for US fighters:
>P-47D: 500 mph IAS
>P-51D: 500 mph IAS
>P-63A: 500 mph IAS
>P-40E: 480 mph IAS
>P-39Q: 475 mph IAS
>F6F-5: 449 mph IAS
>F4U-1D: 443 mph IAS
>P-38L: 440 mph IAS
>P-61A: 430 mph IAS
>FM-2: 425 mph IAS
>Recent testing by the Society of Experimental Test Pilots established that the military's ratings were accurate.
Hm, do you mean to suggest that the Society of Experimental Test Pilots validated the red line speeds you quoted? I'd be very surprised!
>The USAAF did not want 20mm cannons on their fighters. Moreover, the eight-gun installation on the P-47 was more than adequate for the job it was designed to do. It simplified logistics and the Browning MGs were utterly reliable.
The USAAF did not want 20 mm cannon on their fighters, but that doesn't prove anything except that the USAAF made mistakes, too.
"Adequate for the job" - funny, as the P-47 was lost its job as long-range escort fighter and was replaced by the P-51.
The armament suggested by Aquashrimp does provide virtually the same firepower as the historical battery, but saves 680 lbs of weight.
These 680 lbs of weight, if carried as fuel, would have extended the range of the P-47 by more than 200 miles. Even if that would not have meant P-47 cover all the way to Schweinfurt and back, I'm sure the additional coverage would have been greatly appreciated by 8th Air Force bomber crews.
Regards,
Henning (HoHun)
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Originally posted by HoHun
funny, as the P-47 was lost its job as long-range escort fighter and was replaced by the P-51.
That doesn't mean P-47 was inadequate for the escort job or that it was a bad plane. It has more to do with availability ie complexity of production, price, favoritism, etc, rather than performance numbers.
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Hi 2bighorn,
>favoritism
To pick just one, what's the story of favoritism behind the selection of the P-51 as premier escort fighter? First time I ever hear of that.
Regards,
Henning (HoHun)
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Originally posted by HoHun
To pick just one, what's the story of favoritism behind the selection of the P-51 as premier escort fighter? First time I ever hear of that.
I was thinking about time before the selection was made, specifically brits and their lobbying for merlin mustang. Without it we'd probaly see push for p-38 improvements and/or p-47 would roll out of factories with wet wings sooner. Probably "favoritism" wasn't right word to chose.
It does not really matters tho, when 8th AF finally realized that escorts are must, mustang was a logical choice, it was the only single engine fighter with satisfactory range from the get go.
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Originally posted by HoHun
>Recent testing by the Society of Experimental Test Pilots established that the military's ratings were accurate.
Hm, do you mean to suggest that the Society of Experimental Test Pilots validated the red line speeds you quoted? I'd be very surprised!
>The USAAF did not want 20mm cannons on their fighters. Moreover, the eight-gun installation on the P-47 was more than adequate for the job it was designed to do. It simplified logistics and the Browning MGs were utterly reliable.
The USAAF did not want 20 mm cannon on their fighters, but that doesn't prove anything except that the USAAF made mistakes, too.
"Adequate for the job" - funny, as the P-47 was lost its job as long-range escort fighter and was replaced by the P-51.
I'm not suggesting anything, I'm telling you that the SoETP found the P-47 to be the superior fighter in a dive. Beyond that, ask any pilot who flew the P-47 and the P-51 and they will echo this.
Also, I meant that the "eight-gun installation" on the P-47 was adequate for its mission, which was to destroy enemy fighters.
Historians generally recognize that there was a predisposition towards liquid cooled fighters within the USAAF. Likewise, the Navy was overtly biased towards air-cooled radials. Referred to as the Fighter Mafia, many high ranking AAF generals made no effort to hide the fact that the P-51 was more "their kind of fighter". Add to this that the P-51 was a stellar performer and offered greater range than the P-47 (in late 1943) and one can see why the P-51 was selected. Another reason was logistics. Doolittle was determined to simplify his logistics and did so by selecting one type of fighter. Inasmuch as the P-51 had the desired range and at the time of the decision, the Thunderbolt did not, Doolittle decided to re-equip the 8th with P-51s as they became available. You might note that the 56th FG refused Mustangs in no uncertain terms. They insisted on and were permitted to retain the P-47. Doolittle was not going to fool around with a unit that had their level of success.
The arrival of the P-47D-25-RE moved the P-47 much closer to the P-51 in terms of range. With external three tanks installed, it had a comparable combat radius to the P-51. Using two 160 gallon tanks accomplished the same thing.
You stated that "the P-47 was lost its job as long-range escort fighter and was replaced by the P-51."
This was true only in the ETO, and then not entirely either. In the Pacific, the P-47N constituted 50% of the fighter force of the 7th AF. In the western Pacific, the P-47N offered longer range than the P-51s, greater mechanical reliability and their legendary ruggedness.
As to the AAF's reluctance to switch over to 20mm cannons... They were certainly stubborn. 20mm cannons did not arrive on Air Force day fighters until the F-86H of 1953. it seems they were ok for night fighters (P-61), but the fighter mafia managed to retain the Brownings long after the Navy had switched to cannons. During the war years, this could be justified as a measure of simplicity and logistics. The fact that the primary USAF jet fighters went to war in Korea with .50 cal MGs is clearly a matter of politics and rivalry.
Switching the P-47 to 20mm cannon would not have allowed for additional fuel with the existing wing design. That was addressed by the P-47N, but the AAF still required the fifties....
My regards,
Widewing
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Hi 2bighorn,
>I was thinking about time before the selection was made, specifically brits and their lobbying for merlin mustang.
Hm, I think there is nothing wront with lobbying for the fighter with the best performance. It's not like they were pushing for a Spitfire ;-)
>It does not really matters tho, when 8th AF finally realized that escorts are must, mustang was a logical choice, it was the only single engine fighter with satisfactory range from the get go.
Roger - the only reason we are having a discussion at all is the assumption, implicit in Aquashrimp's question, that the USAAF might have realized this earlier and tried to bring up the P-47 to that standard (not knowing the British would come up with a better solution).
Regards,
Henning (HoHun)
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very good info in this thread.
Thanks widewing & HoHun :aok
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Hi Widewing,
>I'm not suggesting anything, I'm telling you that the SoETP found the P-47 to be the superior fighter in a dive.
Widewing, you posted a list of dive speeds and right beneath it the statement:
"Recent testing by the Society of Experimental Test Pilots established that the military's ratings were accurate."
Simple question: Did the SETP establish that the dive speeds you posted are accurate or not?
>Also, I meant that the "eight-gun installation" on the P-47 was adequate for its mission, which was to destroy enemy fighters.
The Brownings might have been able to fulfill their mission, but the P-47 outfitted with Brownings is another thing.
You won't get any "lead on target" if you're low on fuel and returning home when the "targets" get at your bombers. Against the Schweinfurt raids, many Luftwaffe fighters could perform three interception sorties because the bomber flew over most of the Reich un-escorted. The width of the gap between fighter range and distance to target was directly responsible for the catastrophic losses the 8th Air Force took.
>Referred to as the Fighter Mafia
Was this term actually in used WW2? It's usually associated with the group around Boyd, who had great impact on fighter tactics and procurement in the 1960s and 1970s.
>Switching the P-47 to 20mm cannon would not have allowed for additional fuel with the existing wing design.
The earlier the Brownings were replaced, the better a constructive solution could have been found. A new engine mount like with the Fw 190 or a re-located cockpit like with the F4U might have provided the centre-of-gravity shift or the extra space needed to carry more fuel even in the fuselage.
The new engine mount for the Fw 190 was a minor engineering change, so I presume it would not have been a problem for republic either. The resulting forward move of the centre of gravity might have made an additional rear fuelage tank possible. (Wing tanks like the F4U-1's might not even have required an engine shift.)
Besides, a lighter aircraft has a longer range on the same amount of fuel as a heavier aircraft, so 20 mm cannon would have been beneficial even without any extra tanks on the P-47.
Regards,
Henning (HoHun)
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Best thread ever!
I read somewere that the 20mm cannons could not fit because of the landing gear arrangement on the jug, ie not enough room between the front of the wing and the gear. Is this true or false?
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Originally posted by HoHun
Hi Widewing,
>I'm not suggesting anything, I'm telling you that the SoETP found the P-47 to be the superior fighter in a dive.
Widewing, you posted a list of dive speeds and right beneath it the statement:
"Recent testing by the Society of Experimental Test Pilots established that the military's ratings were accurate."
Simple question: Did the SETP establish that the dive speeds you posted are accurate or not?
>Also, I meant that the "eight-gun installation" on the P-47 was adequate for its mission, which was to destroy enemy fighters.
The Brownings might have been able to fulfill their mission, but the P-47 outfitted with Brownings is another thing.
You won't get any "lead on target" if you're low on fuel and returning home when the "targets" get at your bombers. Against the Schweinfurt raids, many Luftwaffe fighters could perform three interception sorties because the bomber flew over most of the Reich un-escorted. The width of the gap between fighter range and distance to target was directly responsible for the catastrophic losses the 8th Air Force took.
>Referred to as the Fighter Mafia
Was this term actually in used WW2? It's usually associated with the group around Boyd, who had great impact on fighter tactics and procurement in the 1960s and 1970s.
>Switching the P-47 to 20mm cannon would not have allowed for additional fuel with the existing wing design.
The earlier the Brownings were replaced, the better a constructive solution could have been found. A new engine mount like with the Fw 190 or a re-located cockpit like with the F4U might have provided the centre-of-gravity shift or the extra space needed to carry more fuel even in the fuselage.
The new engine mount for the Fw 190 was a minor engineering change, so I presume it would not have been a problem for republic either. The resulting forward move of the centre of gravity might have made an additional rear fuelage tank possible. (Wing tanks like the F4U-1's might not even have required an engine shift.)
Besides, a lighter aircraft has a longer range on the same amount of fuel as a heavier aircraft, so 20 mm cannon would have been beneficial even without any extra tanks on the P-47.
Regards,
Henning (HoHun)
I no longer have the SoETP book, some years ago I loaned it to a friend who misplaced it. However, I recall the general results of their testing and Francis Dean mentions the results in his book, America's Hundred Thousand. They found the P-47 to be the fastest accelerating and the most stable of the bunch in a dive. It out-distanced the others rapidly.
The numbers I provided are right out of the various pilot manuals for each type. Specific limits for the P-47 were 500 mph IAS below 25,000 feet and 400 mph IAS above 25,000 feet. For the Mustang, the limits were 505 mph IAS below 9,000 feet, 500 mph IAS above this, with a 300 mph IAS limit above 35,000 feet. Limits for the FG-1D were: 299 mph IAS at 30,000 feet, 368 mph IAS at 20,000 feet and 443 mph IAS at 10,000 feet. Typical of the Navy and Grumman, the F6F's limits were poorly defined. Largely to the severity of the airspeed indicator error. As it was, 370 knots (426 mph) IAS above 15,000 feet and 390 knots (449 mph) IAS below 15,000 feet. If you calculate 390 knots @ 15,000 feet, it equates to 566 mph TAS, or Mach .78, which is certainly well into compressibility.
As to adding 20mm cannon... The M2 cannon was nearly 40 inches longer than the BMG .50, which would have resulted in the guns protruding nearly four feet beyond the leading edge. Moving them rearward was not an option as the main spar was in the way. The difference in weight between 8 Brownings and 4 Hispanos amounts to just over 100 lbs. Normally, the P-47 carried 498 pounds of ammo (weight includes links). A typical weight of ammo for the M2 (as used on the P-38) was 92 pounds. Times 4, that equates to 368 pounds, or 130 lb less than the .50 cal load. Therefore, the total weight reduction is about 235 pounds. If every pound reduced was transformed into additional fuel, it would add 39 gallons. At 42" MAP, 2550 RPM, the P-47 burned 175 gallons/hour. So, this would add about 13 minutes of endurance, or less than 7 minutes to its combat radius. Now, the question begs, would the major level of modification required be worth the time, money and production delays associated with retooling? I think that the USAAF and War Production Board would say "hell no!" Moreover, a 1.4% reduction in loaded weight will not impact range in any measurable way.
Beginning with the P-47D-4, an 8 inch extention was added to the engine mount to allow for a QEC (Quick Engine Change) set-up, which greatly reduced the time required to change an engine. This pushed the P-47s MAC as far forward as Republic thought prudent.
To meet the need for additional range, the P-47D-25 introduced an enlarged internal aux tank, adding 65 gallons. With this, there was no more volume within the fuselage for additional fuel. Thus, Republic's extended, wet wing design that appeared on the P-47N.
My regards,
Widewing
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Originally posted by Nilsen
Best thread ever!
I read somewere that the 20mm cannons could not fit because of the landing gear arrangement on the jug, ie not enough room between the front of the wing and the gear. Is this true or false?
There was room. The receivers would have fit, but the entirety of the barrels would have protruded from the leading edge, not unlike the Typhoon. However, the USAAF believed that the machine gun installation was more than adequate, especially when compared to the four-gun installation on the P-51B. Oddly enough, the two prototypes for the P-51B were built from Allison powered Mustangs with 4 Hispanos installed....
(http://aeroweb.brooklyn.cuny.edu/images/scaled/aec01846.jpg)
My regards,
Widewing
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(1) Its unrealistic to compare the P-47 to other aircraft at the P-47s prime operating altitude. Very little fighting took place at 35,000 feet. In one account I read, from the 356th I believe, the pilots stated that they had alot of trouble getting the Germans to engage them at that altitude in 1943. So in reality, while the P-47s may have had a slight advantage at that altitude, they had to come down to a lower altitude for engagements.
(2) On simple charts, the P-47 appears to do well in dives, but other factors come in to play also The Thunderbolt’s ailerons would flutter as it exceeded its critical Mach limits, causing the stick to move violently from side to side; pummeling the inside of the pilot’s thighs black and blue.
http://www.warbirdsresourcegroup.org/URG/p47.html
Initial engagements with the Luftwaffe showed severe shortcoming at low and medium altitudes and a insufficient fuel load for the escort mission.
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Originally posted by AquaShrimp
(1) Its unrealistic to compare the P-47 to other aircraft at the P-47s prime operating altitude. Very little fighting took place at 35,000 feet. In one account I read, from the 356th I believe, the pilots stated that they had alot of trouble getting the Germans to engage them at that altitude in 1943. So in reality, while the P-47s may have had a slight advantage at that altitude, they had to come down to a lower altitude for engagements.
(2) On simple charts, the P-47 appears to do well in dives, but other factors come in to play also
http://www.warbirdsresourcegroup.org/URG/p47.html
It was common for the escorts to fly at 30k or higher... That's why it was called "top cover". There are many instances where German fighters were encountered at extreme altitudes because the Luftwaffe wanted, where possible, to get above the escorts.
Early P-47C models were not rigged or equipped for drop tanks. So, range was limited to internal fuel. However, in early 1943, P-47s were not expected to fly escort deep into Germany. At that time, the 8th AF was still convinced that the bombers could defend themselves.
As to that website you provided a link to... The books it uses for sources are, at best, garbage. I suggest Bodie's book on the P-47 and any number of high quality, well researched volumes. You can also access squadron reports. A basic book everyone interested in the ETO should possess is The Mighty Eighth War Manual by Roger Freeman.
My regards,
Widewing
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Originally posted by AquaShrimp
So in reality, while the P-47s may have had a slight advantage at that altitude, they had to come down to a lower altitude for engagements.
And that meant that the attacking LW could not dive through the defenders to get to the bombers and always were at a disadvantage from the top cover diving at THEM. P-38s were more than capable of fighting the LW planes on even terms but were unable to be an effective top cover due to the diving limitations. That resulted in 190s doing fast attack runs and getting away with it.
I forget which pilot was it, but when inteviewed he said he never had an engagement where the LW was higher them him, they always got to attack from above. (not very reliable without a source I know, sorry).
Also, in early 43 when just deployed to Britain, fighting tactics were still lacking leading to believe that the P47 would have serious trouble vs. the LW. The tips they got from the RAF included going into a luftberry circle when attacked and such stuff that totaly was not suited for the Jug (a spitfire maybe). Someone has posted that document in this forum before. In practive P-47s were successful even at lower altitudes vs. the LW (in the MTO and 9AF).
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Originally posted by Widewing
Fact:
There is much disinformation about the advantages of the laminar flow airfoils. Even North American admitted that there was no significant decrease in overall drag over 90% of the speed range. This was due to the air flow not remaining laminar as was originally thought. If you examine the wings of both the P-47 and P-51, you would notice that the chord to thickness ratio of the Thunderbolt's wing was less than that of the P-51D. That means that relative to the width of the wing, the P-47's wing was thinner than that of the P-51. Max dive speeds are limited as much by drag rise of the propeller as by the drag rise of the wing itself. At Wright Field in July of 1944, a shiny new P-51D was dive tested at gradually increasing speeds. Initial buffeting began at Mach .75 and gradually increased as speed went up. Eventually, they dived it to Mach .83, but did such damage to the plane that it was written off. In contrast, the immensely strong P-47 could survive repeated dives to Mach .83 without injury to the airframe.
Widewing,
I'm suprised this hasn't been posted yet...
http://www.spitfireperformance.com/mustang/mustangIV-divetest.html
http://www.spitfireperformance.com/mustang/p-51d-dive-27-feb-45.pdf
You'll see that Francis Dean's quote regarding the Wright Field tests are somewhat inaccurate. The airframe was far from 'written off', in fact it was to be re-fitted with metal elevators before conducting further tests.
7. Maximum Limit of Combat.- The airplane has been dived to a maximum Mach number of 0.85 and on several occasions to 0.84. In each case the pilots reported that the vibration became extremely heavy beyond 0.80. In each dive to 0.84 or above the vibration became so severe that the airplane was damaged. The leading edge skin of the wing flap was buckled between rivets, a coolant radiator cracked and hydraulic line broken due to vibration on various dives to 0.84 and above. In extreme war emergency the airplane can be dived to a Mach number of 0.83 (400 m.p.h. Indicated Airspeed at 25,000 ft.), if a very gradual pull-out is made.
Cheers,
Brent Erickson
http://www.wwiiaircraftperformance.org/mustang/mustangtest.html
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Hi Widewing,
>As to adding 20mm cannon... The M2 cannon was nearly 40 inches longer than the BMG .50, which would have resulted in the guns protruding nearly four feet beyond the leading edge.
This seems to have been typical for successful Hispano installations ;-)
>The difference in weight between 8 Brownings and 4 Hispanos amounts to just over 100 lbs.
The difference is more pronounced if you look at the weights of the complete batteries as posted above:
4x Hispano II - 154 rpg - 352 kg - 187% firepower
8x ,50 Browning M2 - 375 rpg - 562 kg - 100% firepower
2x Hispano II - 308 rpg - 252 kg - 94% firepower
(Including ammunition and belt links, ammunition supply of equal energy in each setup.)
The advantage of the 4x Hispano battery is 110 kg (243 lbs - your figure is 235 lbs, so we're in good agreement here), and the advantage of the 2x Hispano battery is 310 kg (684 lbs).
A 310 kg advantage is equal to 413 L additional fuel - 110 gallons, or 38 min of endurance at 42" Hg/2550 RPM. My guess (we could tell more accurate with the manual data) is that this would result in a cruise speed of about 300 mph, so we have a gain of about 190 miles range or 95 miles combat radius.
According to Williamson Murray, "War in the Air", the P-47 had a combat radius of about 375 miles in August 1943, meaning that it could reach about as far as Wiesbaden. From Wiesbaden to Schweinfurt, we've got a distance of 88 miles, or slightly less than the gain from the different armament.
That should, at the very least, be food for serious thought :-)
(Of course, we wouldn't able to assign the full 310 kg to fuel, as tanks and fuel lines have their own weight as well. On the other hand, my P-47D-25 to D-35 Power Plan Chart indicates that Maximum Cruise Power is a bit lower than the setting I used above (which is about equivalent to Maximum Continuous in that chart), so we might get a bit more range out of it anyway. The 310 kg are about 4.9% of the loaded weight, so on the return leg, the P-47 will be markedly lighter than usual which helps combat radius, too. So there are some conservative factors along with the initial optimistic assumption that make the 95 mile combat radius extension a reasonable approximation. Conservative factors includes my map reading as Wiesbaden is not at the extreme limit of Murray's range circle, and somewhat south of the direct route to Schweinfurt, too :-)
>Now, the question begs, would the major level of modification required be worth the time, money and production delays associated with retooling? I think that the USAAF and War Production Board would say "hell no!"
With the benefit of hindsight, I'd say the answer in early 1943 should certainly have been an unambiguous "Yes"! Without this benefit, I'd expect that this suggestion would have been turned down since neither the USAAF nor the War Production Board had a clear idea at that time of how hard the fight was going to be for the 8th Air Force.
>To meet the need for additional range, the P-47D-25 introduced an enlarged internal aux tank, adding 65 gallons. With this, there was no more volume within the fuselage for additional fuel.
As pointed out above, the F4U-1 had tanks in the outer wings, which might have been an option for the P-47 as well, especially as we'd gain some volume from switching to 2x Hispano cannon.
To gain room in the fuselage, it would have been an option to remove the turbo-supercharger :-) The P-47 already had the intercooler that was required for high altitude performance, and replacing the turbo-supercharger with a mechanically driven one would have freed up the rear fuselage and the lower fuselage as well, creating plenty of room for enlarged fuel tanks.
Sounds like heresy, but actually two-stage mechanically-driven superchargers were doing quite well at high altitude, too, and while the P-47 would have lost a bit of power at the propeller, it would have gained some through exhaust thrust while being lighter overall (at an equivalent fuel load).
Regards,
Henning (HoHun)
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Originally posted by HoHun
As pointed out above, the F4U-1 had tanks in the outer wings, which might have been an option for the P-47 as well, especially as we'd gain some volume from switching to 2x Hispano cannon.
I thought the reason they got rid of the wing tanks in the later Corsairs was because almost all mission profiles up to the time used drop tanks and with the addition of the second hardpoint on the -1C, -1D, and -4, it was thought the wing tanks were unnecessary. If that's the case, couldn't the same argument be made for the P-47? In "Long Reach", some of the Jug pilots describe maintaining their centerline tank during combat...Plus, looking at the construction of the wings on a website I found (I'm at work and didn't look it up again, but is showed a schematic of the structure) it doesn't look as if placing fuel in the wing was ever originally envisioned, based on the configuration of the ribs, spar, etc. And, although completely annecdotal, is there any reference that descibes U.S. pilots as having "cannon envy" to the point that they'd trade their 8X.50 cal for 2X or 4X hispano? Again going back to "Long Reach", many of the pilots describe their confidence in going head-on with German planes due to the fact that the Jug possessed "superior firepower" compared to the German fighters. This may have been a misperception, especially when compared to the heavy cannon planes like the A-8 or 152, but it was a perception that existed none-the-less.
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Originally posted by LRRP22
7. Maximum Limit of Combat.- The airplane has been dived to a maximum Mach number of 0.85 and on several occasions to 0.84. In each case the pilots reported that the vibration became extremely heavy beyond 0.80. In each dive to 0.84 or above the vibration became so severe that the airplane was damaged. The leading edge skin of the wing flap was buckled between rivets, a coolant radiator cracked and hydraulic line broken due to vibration on various dives to 0.84 and above. In extreme war emergency the airplane can be dived to a Mach number of 0.83 (400 m.p.h. Indicated Airspeed at 25,000 ft.), if a very gradual pull-out is made.
Cheers,
Brent Erickson
http://www.wwiiaircraftperformance.org/mustang/mustangtest.html
Excellent material Brent, thanks for posting it.
My regards,
Widewing
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Originally posted by HoHun
Hi Widewing,
To gain room in the fuselage, it would have been an option to remove the turbo-supercharger :-) The P-47 already had the intercooler that was required for high altitude performance, and replacing the turbo-supercharger with a mechanically driven one would have freed up the rear fuselage and the lower fuselage as well, creating plenty of room for enlarged fuel tanks.
Sounds like heresy, but actually two-stage mechanically-driven superchargers were doing quite well at high altitude, too, and while the P-47 would have lost a bit of power at the propeller, it would have gained some through exhaust thrust while being lighter overall (at an equivalent fuel load).
Regards,
Henning (HoHun)
Well apparently, Republic thought that they also needed better mid-level performance. With the XP-72, they changed to a huge centrifugal supercharger spun by a long extention shaft. This monster consumed as much internal volume as the turbo and its ducting, but it did provide for 3,300 hp at a much lower critical altitude of 25,000 feet. Had the XP-72 entered production as scheduled, it was to be fitted with the wing of the P-47N. Thus, they would have had a 500 mph fighter with range comparable to the P-51D. Bodie quotes Republic as expecting 540 mph on the projected eventual 4,000 hp promised by Pratt & Whitney.
My regards,
Widewing
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Sounds like a custom build drag racer, not a combat service a/c...
-C+
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Originally posted by Charge
Sounds like a custom build drag racer, not a combat service a/c...
-C+
But 1 I would happily donate a testicle to have built for my personal enjoyment and raising hell down the Hudson River VFR corridor.
Wolf
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Originally posted by Wolfala
But 1 I would happily donate a testicle to have built for my personal enjoyment and raising hell down the Hudson River VFR corridor.
Wolf
You might even give those F-16's that intercept you a run for their money...for a minute or so anyway...
If you look at the pictures of the XP-72, it looks like a warplane, no custom built testbed. Its a huge, monstrosity of a plane. I'm making a total SWAG here, but I'm guessing the overall dimensions get close to some of the present day (smaller) jet fighters. If the war had continued, I guess we would know whether or not it would have been the dominant fighter it looked like on paper.
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The XP-72...
(http://home.att.net/~historyzone/XP-72.jpg)
(http://home.att.net/~ww2aviation/XP-72Profile2.JPG)
Herb Fisher's P-47D-30-RE dive test Jug.
(http://home.att.net/~ww2aviation/Fisher-F-47D.JPG)
Why the P-47 was thought to be the better jabo... This one flew home this way.
(http://home.att.net/~ww2aviation/hv-h2.jpg)
Jugs did just about everything, including operating from carriers. In this case, a P-47D is catapulted off of a CVE at Saipan. Thunderbolts were operating off of captured airfields within rifle range of Japanese defenders.
(http://home.att.net/~ww2aviation/Saipan-Jugs.jpg)
My regards,
Widewing
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Thats it, I'm flying the P-47 tonight. All models. Are you happy now? What a cool plane. I used to think it was an ugly monstrosity, but now I find it's lines and shape to be magnificent. The wing shape, the elongated cowl, the wide stance on the gear is just fabulous.
BTW, anyone that has flown the P-47 in the Special Events arena knows how important it is to control the high ground in any engagement. I would much rather be diving to 30K than struggling to reach it. The P47 is nearly untouchable above 30K (Ta-152 excluded).
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Hi Widewing,
>With the XP-72, they changed to a huge centrifugal supercharger spun by a long extention shaft. This monster consumed as much internal volume as the turbo and its ducting, but it did provide for 3,300 hp at a much lower critical altitude of 25,000 feet.
Quite interesting, I wasn't aware of that before. I think it shows quite nicely that Republic weren't religious about their turbo-supercharger.
In 1943, a mechanically supercharged Jug would, of course, have looked somewhat different than the XP-72. I'm confident it would have been possible to use a conventional engine installation as in the F4U-1 or the F6F-3 with the supercharger close to the firewall. That way, the volume beneath of and aft of the cockpit would have become available for fuel. (And much more than 110 gallons, if required.)
That would have given the P-47 the range to get to Schweinfurt and back on a single drop tank (or, installing more than 110 gallons internally, even without a drop tank).
Had the course of the air war been anticipated correctly by the USAAF, such an improved P-47 might have been a valuable asset to the 8th Air Force in its battles over the Reich.
Regards,
Henning (HoHun)
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we need cats for our carriers, i should be able to load the hellcat, rockets 2 1000blers 100% fuel. With wind u could prob do it with out the cats but we dont have it, i have seen pics wit f6fs right before launch hooked up to cats, yea there nothin but big rubber bands but it will help.
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"With the XP-72, they changed to a huge centrifugal supercharger spun by a long extention shaft."
Is that really a sensible way of doing that?
What about torsional forces or bearings of the shaft?
What if something hits the shaft?
AFAIK, the Merlin has the connection shaft made out of metal that is rather soft to tolerate the conditions that would make a harder shaft to shatter. And it is quite short. If a small transmission gearbox would be used to keep the revolutions in sensible limits that would require even more of the shaft to bear the torsional forces without bending, and thus without shattering.
Got any picture of how they did it?
-C+
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Originally posted by Widewing
Well apparently, Republic thought that they also needed better mid-level performance. With the XP-72, they changed to a huge centrifugal supercharger spun by a long extention shaft. This monster consumed as much internal volume as the turbo and its ducting, but it did provide for 3,300 hp at a much lower critical altitude of 25,000 feet.
What's the source for this? The sources seem to be quite contradictory because something like this is claimed in the AHT while White's book claim turbo in the XP-72.
Regarding the dive recovery of the P-47, it appears that the elevator tended to lock up at high mach numbers and the pilot was basicly a passenger until the mach number decreased at lower altitudes (around 12k) and elevator became operational again (sources RAE and an article written by C.E. Pappas, chief of the aerodynamics department of Republic). Therefore the dive recovery flaps were added to late production P-47s.
In the case of the P-51 dive recovery was basicly possible at any time but the recovery would cause increased buffeting and danger of structural damage. Actually the XP-51 in the NACA was the first plane where the dive recovery flaps were tested experimentally.
gripen
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Below is a graph from article by Pappas (Flight, March 15th 1945) showing the elevator characters. Note that there might be some error in the measurements and the elevator might have been modified in the later models).
gripen
(http://www.onpoi.net/ah/pics/users/852_1159539157_p-47dive.jpg)
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Originally posted by gripen
What's the source for this? The sources seem to be quite contradictory because something like this is claimed in the AHT while White's book claim turbo in the XP-72.
White is simply incorrect. In Bodie's monster reference work on the P-47, he details the engine and supercharger installation on the XP-72. Below is a scan of the supercharger and Bodie's description from page 244 of his book.
(http://home.att.net/~ww2aviation/XP-72superchgr2.jpg)
My regards,
Widewing
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Originally posted by HoHun
"Adequate for the job" - funny, as the P-47 was lost its job as long-range escort fighter and was replaced by the P-51.
At the time the 51 came out, it had lots more range than the current jug. I wish they had the early jug in AH, that it might be in EW--- I simply can't fly any of the planes in there against a spit V
(p.s.--never get in an arguement with Widewing about airplanes:aok )
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Thanks Widewing, there is not much written about the planes using the R-4360.
I've been trying to compare Republic dive data and Herb Fisher's but it seems that I should re-arrange the spreadsheet to time line based to compare the results. Anyway, the republic data seem to be near vertical dive started with half roll while Fisher just pushed the plane to the dive. Also the plane tested by Republic appear to be somewhat cleaner early series P-47 (given the weight).
gripen
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Originally posted by bkbandit
we need cats for our carriers, i should be able to load the hellcat, rockets 2 1000blers 100% fuel. With wind u could prob do it with out the cats but we dont have it, i have seen pics wit f6fs right before launch hooked up to cats, yea there nothin but big rubber bands but it will help.
I missed this before... You don't need a catapult, all you need is full flaps and WEP power on takeoff. Some guys will tell that they add flaps on the takeoff run, others will say they use only half flaps and wrestle into the air...
My recommendation is full flaps and WEP. No muss, no fuss, airborne without drama. 100% gas, rockets and two 1k bombs... No problem.
My regards,
Widewing
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Originally posted by gripen
Thanks Widewing, there is not much written about the planes using the R-4360.
I've been trying to compare Republic dive data and Herb Fisher's but it seems that I should re-arrange the spreadsheet to time line based to compare the results. Anyway, the republic data seem to be near vertical dive started with half roll while Fisher just pushed the plane to the dive. Also the plane tested by Republic appear to be somewhat cleaner early series P-47 (given the weight).
gripen
I did some additional digging into the two XP-72 prototypes. Not only did they not fly with a turbosupercharger, they never flew with that huge centrifugal blower either. That was slated for the ten YP-72s that were cancelled along with the production contract.
According to Republic's Lowery Brabham, they flew with a specially modified R4360-13 engine, fitted with a variable speed, two stage mechanical supercharger. The engine produced 3,350 hp at sea level, 2,820 hp at 25,000 feet compared to 3,000 hp and 2,400 hp respectively for the "standard" R-4360-13.
My regards,
Widewing
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Read somewhere on the internet and I paraphrase...
50 caliber heavy machine guns were the standard to alleviate supply chain issues with multiple types of ammo. I believe this was a deliberate decision made in the interest of simplicity, made easy by the fact that it was a good weapon.
Apparently all other issues took a back seat to this decision. What else would make sense?
I suppose that rather than giving the Jug cannon to boost it's hitting power it was just outfitted with more of the standard 50s.
Of course you could bring up the P38 :) but it DID have 4 50s in addition to the 20mm.
There's the added plus (and I'm guessing here) of familiarity with the weapon from plane to plane so as the squadrons were re-equipping with better planes the pilots were already familiar with the guns and knew what to expect (trajectory, velocity, distance..)
My question is - was the ammo indeed interchangeable across all 50 cal Heavy mgs in all the service branches?
Comments?
Magoo
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Hi Magoo,
>My question is - was the ammo indeed interchangeable across all 50 cal Heavy mgs in all the service branches?
Good question, but the rest of your posts makes me believe you have missed most of what was written above.
In short:
- The 8x 12.7 mm MGs did have about the firepower of 2 x 20 mm cannon.
- The 8x 12.7 mm MGs were about 684 lbs heavier than 2 x 20 mm cannon, with ammo and belting considered for both batteries.
- 684 lbs is about the weight of the extra fuel the P-47 would have needed in late 1943 to escort the 8th Air Force bombers all the way to Schweinfurt and back.
So the "50 cal" machine gun cost the USAAF dearly, both in terms of men and machines.
Weight in an aircraft will affect its combat effectiveness negatively, and the "50 cal" was a rather heavy weapon for the firepower it delivered.
Regards,
Henning (HoHun)
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Again, I'll ask this question, although the answer is annecdotal. Does anyone have any quotation of U.S. pilots in ETO that display "cannon envy". Almost everything I've read from U.S. pilots shows utter confidence in the firepower of the Ma Deuce. Almost all pilots talk about "superior firepower" when they compare their planes to their German counterparts. As I stated in my earlier post, this may have been a perceived advantage, but it was a uniform one. I don't doubt your math/scientific approach to comparing armament, but what did the actual pilots think? There are many examples of the U.S. using equipment that was technically "inferior" but battle tested, reliable, easily manufactured, logistically sustainable (arguably most important), and inspired complete confidence in their crew/operators.
Obviously I can't make an opinion as an actual WWII fighter pilot, but in AH, I'll take my 8X.50cal over 2X20mm any day. 4X20mm, maybe, but not just 2...
And Magoo, the answer to your question is "yes".
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Originally posted by HoHun
684 lbs is about the weight of the extra fuel the P-47 would have needed in late 1943 to escort the 8th Air Force bombers all the way to Schweinfurt and back.
Also, where you gonna stash that extra 114 gals of avgas?
http://rwebs.net/avhistory/history/p-47.htm
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Originally posted by Stoney74
Also, where you gonna stash that extra 114 gals of avgas?
http://rwebs.net/avhistory/history/p-47.htm
Was about to ask the same question.
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Hi Stoney,
>Almost everything I've read from U.S. pilots shows utter confidence in the firepower of the Ma Deuce.
It's not like you'd have to sell the 20 mm cannon to the pilots - you'd have to sell them to the US Army.
So for the judgement of the 12.7 mm HMG's historical performance, both the question and the answer are completely irrelevant.
>There are many examples of the U.S. using equipment that was technically "inferior" but battle tested, reliable, easily manufactured, logistically sustainable (arguably most important), and inspired complete confidence in their crew/operators.
No amount of "diverse advantages" will change the basic fact that the 12.7 mm HMG was way overweight and inflicted a weight penalty of 684 lbs of extra weight over an equivalent cannon battery.
Regards,
Henning (HoHun)
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Originally posted by Stoney74
Also, where you gonna stash that extra 114 gals of avgas?
http://rwebs.net/avhistory/history/p-47.htm
Originally posted by Wolfala
Was about to ask the same question.
I'd suggest you two just go back a couple of messages and read the in-depth discussion of your question there.
When I'm in the right mood, I'm quite ready to provide an "executive's summary" like the one I posted for Magoo's benefit - once in a while, but not twice or thrice in succession.
Regards,
Henning (HoHun)
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See Rules #2, #4, #5
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I believe the .50 debate is 2 fold: Supply chain, as pointed out earlier. The other reason is the lack of need for buff busting. The allies weren't faced with heavy armada's of bombers which required cannon to crack. And since the AXIS never developed anything along the lines of the B-17 or B-29, or fielded them in any threatening numbers - maybe it was a moot point.
Maybe Tony Williams, our resident gun author can chime in on this?
Wolf
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See Rules #2, #6
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See Rule #2
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Originally posted by Stoney74
Anyone ELSE have an opinion?
Well, while I tend to think that US planes might have done better with cannons, it should be noted that firepower as defined by HoHun completely ignores some good qualities of the battery of the 12,7mm MGs; good ballistic characters combined with large concentration of projectiles in the target area. In addition the 12,7mm bullet could penetrate quite well even at long range.
There is a long history of shooting theories by HoHun in this board and a common feature of all these is somewhat strange way to handle probability of the hit and practically allways the way he handles issue favors certain type of weapons or weapon installations. The first time I was involved with him in this kind of discussion was about four years ago (see here (http://www.hitechcreations.com/forums/showthread.php?s=&threadid=43507)). In that time he strangely assumed increasing accuracy of the shooting when the range increased. I teached him (with simple examples) some basic probability calculations. So after learning these he came up with new theory assuming that in the case of uncertainty, the hits some how concentrate evenly around the right point (?), so I had to point out that in the case of the uncertainty, the error is practically allways systemetical (ie not evenly distributed around right point). After this he has been arguing that in most cases pilots tend to shoot directly behind the target so there is very little systemetical error and accuracy is around 1mil in the best case, so I posted German data on shooting accuracy to steady target showing far worse accuracy even in the case of a good shooter. After that it has been quite quiet in that front.
gripen
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Hi Skuzzy,
Thanks for re-acting so quickly to my request.
Regards,
Henning (HoHun)
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Hi Wolfala,
>I believe the .50 debate is 2 fold: Supply chain, as pointed out earlier. The other reason is the lack of need for buff busting. The allies weren't faced with heavy armada's of bombers which required cannon to crack. And since the AXIS never developed anything along the lines of the B-17 or B-29, or fielded them in any threatening numbers - maybe it was a moot point.
Let me point out what I consider the two vital flaws in those points:
1) Supply chain.
Switching the fighter squadrons over to cannon entirely would not even have increased the number of spare parts as you could drop the 12.7 mm MGs from the supply chain. If the bombers would have kept it, fine, but they had thousands (or ten-thousands ...) of type-specific spare parts in their supply chain anyway.
Besides, in logistics, the high-turnover, low-value articles that are continuously directed to a high number of recipients - like cannon and ammunition - are not a problem at all. What you are worried about are high-value, low-turnover parts, especially when they are mission-critical, such as radar sets for lead bombers or jamming equipment for electronic warfare.
(The Luftwaffe routinely used up to three different types of guns with non-interchangable ammunition on a single aircraft type, and I never read anything about supply difficulties until the breakdown of the transportation system in the last weeks of the war made fulfilling even the simplest demands highly difficult.)
If the US Army had been free of bias and illusions, they would have asked themselves: "Do we want to accept a weight penalty of 684 lbs in the P-47 to make the life of our bean counters a tiny little bit easier, or do we switch to cannon armament?"
2) Cannon were only necessary to combat bombers.
The German military had cannon developed as universal air combat weapons, recognizing early that MG armament would be insufficient, with their combat experience (which included a lot of MG use due to the delay in employing technology) confirming the inadequacy of machine guns. They also conducted ballistic research to find the best way to destroy stressed-skin all-metal aircraft, and arrived at the high-explosive mine shell.
What's more, the Luftwaffe fielded a 15 mm cannon that the USAAF later attempted to introduce as a replacement for the 12.7 mm HMG, and quickly and universally upgraded it to 20 mm because the weapon was much more effective firing medium-velocity cannon shells than it had been firing high-velocity projectiles of with only a light explosive or incendiary warhead.
In the development of cannon as air-to-air weapons, there was no connection to the bombing offensive against Germany at all - even the MK108 had been introduced into service before the Schweinfurt raid for the first time convinced the German leadership that bombers were indeed going to be a serious threat.
Two cannon simply were a better way of delivering the same firepower as eight heavy machine guns, regardless of the type of the aircraft they were used against.
Again, there is hardly an simpler way of improving the P-47 performance than removing 684 lbs of excess weight by changing it to a more modern armament battery. If the USAAF had realized this (they didn't even come close), better supervision of the build-up of Hispano production in the US would have made the replacement of the Browning MGs with cannon a realistic possiblity.
With regard to the impact of weight, if you look at his article on the F8F, you will see that Grumman went to incredible lengths to save just 230 lbs. (They deliberately weakened the wing to an ultimate load of just 7.5 G and allowed the wing tips to separate in a safe and controlled manner if these 7.5 Gs were exceeded.)
http://www.findarticles.com/p/articles/mi_qa3897/is_199808/ai_n8826530
Regards,
Henning (HoHun)
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Originally posted by HoHun
Again, there is hardly an simpler way of improving the P-47 performance than removing 684 lbs of excess weight by changing it to a more modern armament battery. If the USAAF had realized this (they didn't even come close), better supervision of the build-up of Hispano production in the US would have made the replacement of the Browning MGs with cannon a realistic possiblity.
Well, after all - despite all the advantages of the cannons - the statistical reality what was seen by the USAF in the ETO, was that a plane with only 4 x 12,7mm MGs (weakest armament of the three primary USAF fighters) was the most succesfull and the most effective against the German fighters (P-51B). So in practice reducing the armament of the P-47 to the 4 x 12,7mm would have resulted about same weight saving much easier without any structural or logistical changes and apparently no practical reduction in combat performance.
In practice similar reality was seen by NAVY in the Pacific where the F6F and the FM-2 were the most succesfull planes (quantatively and relationally).
In fact vast majority of the American air to air kills of WWII were reached with armament of 4 x or 6 x 12,7mm MG. Naturally that does not tell if the P-51 or the F6F (which accounted vast majority of US kills) would have done better with cannons but it certainly tells that firepower was definately not the limiting factor of the success.
gripen
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Only the B model P-51 had four 12.7mm machine guns. The D had six.
A postwar study showed the way that 50 cals were effective. A 50 cal round only downed an enemy plane when it struck flammable objects (fuel, ammunition), or critical parts (pilot, vulnerable engine components).
Source: Dirty Little Secrets of World War II.
Cannon rounds make their own explosions.
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Jimmy Thatch was actually angry when the F4F-4 was introduced with 6X.50cal instead of the F4F-3's 4X.50cal. He thought it was unnecessary firepower and reduced performance too much.
The P-47 could have lugged the extra weight around. When the P-47D15 was introduced with pylons, it would carry an extra 1800lbs of fuel in 2 150 gallon drops. The extra weight was not the issue. It was an issue of space within the airframe. Changing the armament in the wings would not have made enough space to carry an extra 114 gallons internally. The P-47N had redesigned, larger wings to include more fuel.
The P-47 was designed around that big turbosupercharger. Replace that to make more room for fuel, and you've got a different airplane. As Widewing said, when they did try that, they called it the XP-72.
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Originally posted by AquaShrimp
Only the B model P-51 had four 12.7mm machine guns. The D had six.
It was very good air to air results of the P-51B which caused 8th AF to switch almost entirely to the P-51 (except the 56th FG). And many pilots rated P-51B better than the P-51D despite heavier and more reliable armament of the later (change was decided before spring 1944).
In addition there is couple examples of reducing armament of production aircraft from 6 to 4 x 12,7mm MGs like the P-40N and FM-2. Also the Russians tended to remove wing armament of the P-39 as well as Australians often reduced armament of the P-40 to 4 MGs.
I'm not ignoring the advantages of the cannons, IMHO cannon is superior, but historically in many cases 4 x 12,7mm MGs proved to be good enough armament. This is also supported by the very good combat record of the P-51B and FM-2.
gripen
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Originally posted by Stoney74
Jimmy Thatch was actually angry when the F4F-4 was introduced with 6X.50cal instead of the F4F-3's 4X.50cal. He thought it was unnecessary firepower and reduced performance too much.
The P-47 could have lugged the extra weight around. When the P-47D15 was introduced with pylons, it would carry an extra 1800lbs of fuel in 2 150 gallon drops. The extra weight was not the issue. It was an issue of space within the airframe. Changing the armament in the wings would not have made enough space to carry an extra 114 gallons internally. The P-47N had redesigned, larger wings to include more fuel.
The P-47 was designed around that big turbosupercharger. Replace that to make more room for fuel, and you've got a different airplane. As Widewing said, when they did try that, they called it the XP-72.
I remember reading somewhere that no matter HOW much external gas the Jug could carry, the bigger thing was the range which it could fly/fight on internal fuel--- gotta drop the tanks in a fight, which often happened otw TO the target
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Hi Bj,
>I remember reading somewhere that no matter HOW much external gas the Jug could carry, the bigger thing was the range which it could fly/fight on internal fuel--- gotta drop the tanks in a fight, which often happened otw TO the target
Good point! This tactical consideration would have made the increased internal tankage I suggested even more valuable.
684 lbs are equivalant to about 110 gallons of fuel - the F4U-1 for example had wing tanks holding 124 gallons, so that is not an unusual amount of fuel at all.
(Republic - as "Seversky" - had pioneered the devleopment of "wet" wing tanks, by the way, with their P-35 fighter.)
Applying the Breguet range equation to the P-47, an increase of internal fuel by 684 lbs leads to an increase of the range on internal fuel by 41% (from a fuel increase of just 27%).
Adding 1200 lbs of fuel in a drop tank to the above example, the Brequet range equation indicates a range incrase of 26% from a fuel incrase of 18%. (That assumes that the drop tank is kept - if you drop it when it's empty, range would increase even further as the aircraft becomes cleaner aerodynamically).
Regards,
Henning (HoHun)
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Originally posted by HoHun
Good point! This tactical consideration would have made the increased internal tankage I suggested even more valuable.
Well, changing the weapons and increasing the internal tankage are quite separated issues. The capacity of the internal tankage of the P-47 was increased twice without any change in the weapons and the weight increase due to this was not seen as a big problem.
If the weight saving had been a real issue, the squadrons would have removed the outer MGs just like many P-40 units did in Pacific and that would have been possible without any structural changes and apparently no real effect on combat performance of the armament just like the record of the P-51B and the FM-2 shows.
AquaShrimp,
I forget to note earlier that even with the 6 x 12,7mm MGs the P-51D was still the weakest armed of the three primary USAF fighters.
gripen
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Originally posted by bj229r
I remember reading somewhere that no matter HOW much external gas the Jug could carry, the bigger thing was the range which it could fly/fight on internal fuel--- gotta drop the tanks in a fight, which often happened otw TO the target
P-38s were capable of carrying 600 gallons under the wings.. These large tanks were used rarely as they limited cruise speeds and had to be dropped at low speed to avoid striking the tail. In theory, a P-38 fitted with these tanks could fly further in one direction than it had internal fuel to return. Most use of the 310 (300 usable) tanks were for ferrying fighters over great distances. With these tanks, the P-38 could fly trans-Atlantic with adequate reserve.
My regards,
Widewing
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IF my math is correct, 231 cubic inches equals 1 gallon. 684 lbs. at 6 lbs. per gallon = 114 gallons times 231 cubic inches equals 26,334 cubic inches. That gives us 15.24 cubic feet needed to contain that 114 gallons of fuel. So again, I'll pose the question, is there 15 cubic feet of free area within the airframe to contain the extra fuel. Does anyone know?
Let's not forget that in the Pacific, lighter armament was a luxury resulting from the construction of Japanese aircraft. The reason the F4F-4 was delivered with 6X.50cal was a result of British experience with the Martlet with 4X.50cal against German aircraft.
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Originally posted by Stoney74
Let's not forget that in the Pacific, lighter armament was a luxury resulting from the construction of Japanese aircraft. The reason the F4F-4 was delivered with 6X.50cal was a result of British experience with the Martlet with 4X.50cal against German aircraft.
At least Eric Brown appear to have been quite happy with firepower of the Martlet I and II, he was in the No: 802 Squadron which flew convoy patrol duties from the HMS Audacity late 1941 (quoted from "Air International" magazine):
"No 802 Martlets achieved a very high success rate against the marauding Focke-Wulf Fw 200s that prowled the Atlantic seeking out convoys and either attacking them or reporting their presence to U-boat wolf pack. The Condor was heavily armed and had few blind spots, so we received quite number of hits on our fighters as we went in to the attack, but they proved well able to absorb punishment; indeed one Martlet survived a collision with an Fw 200, although the German aircraft was mortally damaged.
The weight of firepower in the Martlet was, I believe, a decisive factor in our success, and one of my lasting impressions is seeing the cockpit of a Condor virtually disintegrate under the devastating hail of lead coming from my Brownings as I made head-on attack. Perhaps this experience was what made me feel the Royal navy should have retained the American name Wildcat from the outset for this ferocious little fighter, and it seems that their Lordships at the Admiralty belatedly shared my opinion, for when the first Wildcat V was delivered to this country early in 1944, it was decided that henceforth the name Martlet would be dropped for all marks of the aircraft."
I'm not sure if the plane was Martlet I or II but apparently 4 or 6 x 12,7mm MGs proved to be quite effective against four engined bomber given that several Condors were claimed by No. 802 Squadron.
The Brits seem to have been going towards four cannon armament and in the case of the P-51 the cannon installation appear to originate from the British requirement; had the P-47 been built for the British spec, it would almost certainly had been with 4 x 20mm cannons. Anyway, despite apparently successfull installation of the 4 x 20mm cannon in the Mustang Ia/P-51, the production P-51B and later models used 12,7mm MGs and reached great success.
In the Finnish service 4 x 12,7mm proved to be effective against the russian types which were generally quite well protected, the exception being the Il-2 which was difficult to shoot down even with the 3 x 20mm of the G-6 with wing cannons.
The point here is that choosed weapons of the P-47 appear to have been very effective in combat so why fix something which was not broken? After all the Allies were clearly winning air war over Germany with a plane with just half or 3/4 firepower of the P-47.
The cannons would have probably been some what more effective but would it have been worth of all structural, logistical etc. changes?
gripen
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I have one comparison of armament from a RAF pilot who went from Spit V and IX (4x.303 + 2x 20mm) to a P51C. (4x.50).
His feeling was tha it was a great stepdown in firepower.
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Angus,
That was certainly a stepdown in firepower, but that does not mean that 4 x 12,7mm was somehow ineffective against the German fighters; 2 x 20mm would have been better but the combat record of the P-51B shows that 12,7mm MGs did pretty well after all. If they have been facing really well protected planes like the Il-2, the situation might had been different.
Pilot's comments on weapons seem to depend quite much on what kind of enemies they were facing and also what other planes pilots have flown. As an example Eric Brown started his combat career with the Sea Gladiator and other early war FAA fighters were the Fulmar and the Sea Hurricane so weapons of the Martlet were seen as a great improvement. In addition the good results against German planes seem to support Brown's opinion.
Notable thing is that I have not been able find any negative pilot comment on the weapons of the P-47; generally all comments seem to be more or less praising. And the combat record of the P-47 is pretty good so there is not much reason to believe that cannons would have caused a large improvement.
gripen
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Originally posted by gripen
Notable thing is that I have not been able find any negative pilot comment on the weapons of the P-47; generally all comments seem to be more or less praising. And the combat record of the P-47 is pretty good so there is not much reason to believe that cannons would have caused a large improvement.
gripen
Agreed. Statistics aside, US pilots seem to have been uniformly satisfied with their armament, and I have encountered reports from at least a couple of Germans who feared the P-47 because of its guns.
- oldman
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Originally posted by Oldman731
Agreed. Statistics aside, US pilots seem to have been uniformly satisfied with their armament, and I have encountered reports from at least a couple of Germans who feared the P-47 because of its guns.
- oldman
the problem is, people have the AH mindset. In AH, you have to blow the plane out of the sky to "win". hence why canons are seen as the only way by some.
in WWII, deep over Germany, just getting those 109/190s to disengage the bombers was enough to "win"...... a few pings from 8x50s would sure do that......
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Hi Oldman,
>Statistics aside, US pilots seem to have been uniformly satisfied with their armament, and I have encountered reports from at least a couple of Germans who feared the P-47 because of its guns.
Talking about the US pilots who apparently were satisfied, I'm sure that's because they were never given the choice between eight heavy (indeed) machine guns, or two cannon and the weight of their mount 684 lbs down.
You can have your crew chief tuning the machine for a year, and he will still fail to match the performance gain from the weapon change. The weight advantage takes the run-of-the-mill P-47D-25 half the way down to the P-47M "racer's" light weight configuration.
(It's also telling that 9th Air Force P-47 pilots refused the installation of rear warning radars, since they felt that 50 lbs of extra weight were too much. Now extrapolate that reaction to 684 lbs ... :-)
You're probably aware of the WW2 saying: "The Mustang does everything the Spitfire does, too, but the Mustang does it over Berlin."
Well, re-configure the P-47 with 2x Hispano cannon and some internal tankage, and the Thunderbolt "does it over Schweinfurt".
I think it's quite difficult to look at the greatest defeat the 8th Air Force ever suffered (and they suffered it twice) without reaching the conclusion that their escort fighters were somehow lacking. Very likely, this was 8th Air Force thought, for they replaced the the P-47 with the P-51.
The title of this thread is "Improve the P-47", and I have not seen any suggestion that would have yielded a greater improvement than simply exchanging the US gun for a model the British were already using with great success.
Regards,
Henning (HoHun)
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Hi Overlag,
>in WWII, deep over Germany, just getting those 109/190s to disengage the bombers was enough to "win"...... a few pings from 8x50s would sure do that......
Actually, the air war agaist the Luftwaffe was not won until the USAAF fighters were "unleashed" from close escort duties and actively hunted down and destroyed the Luftwaffe interceptors.
Not that there is much to choose between 8x 12.7 mm and 2x 20 mm firepower-wise - but the lighter cannon battery will leave you with more fuel for the hunt.
Regards,
Henning (HoHun)
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i didnt mean the overall winning of the war. The russians did that.....;)
i ment that the p47 was, mostly a bomber escort. Its job was to escort bombers, and protect them from fighters. Just getting them to break off was enough to forfill that plan.
sure, the ground attack/vulching the americans did of german bases would be better suited to a cannon version P47, but the escort one id rather have 6-8 50s.
also with 6-8 guns, if one jams, its not so much of a problem, but if that was a plane with only 4 cannons...... :(
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Hi Overlag,
>i ment that the p47 was, mostly a bomber escort. Its job was to escort bombers, and protect them from fighters. Just getting them to break off was enough to forfill that plan.
That was what everyone thought before they tried it out. Just as the Germans in the Battle of Britain, the USAAF realized that it wouldn't work when they started the air battle for Germany.
Interceptors that operate under radar control over friendly territory have a big advantage when it comes to setting up intercepts. You can't defeat them by trying to get between them and the bombers - you can only defeat them by shooting them down in so large numbers that their losses can't be made good anymore.
To achieve air superiority, you have to destroy the enemy air force. Just pinging their planes is not enough, at least not in the long term.
Regards,
Henning (HoHun)
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Originally posted by HoHun
but the lighter cannon battery will leave you with more fuel for the hunt.
Only if you can find the 15 cubic feet required to put the fuel inside the airframe. There's no problem adding 684 pounds to the takeoff weight of the P-47. Its the space required. Changing the armament would not free up 15 cubic feet of wing area.
HoHun, where's the space inside the airframe to take advantage of your proposed weight savings?
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Hi,
with only 2 x 20mm the P47´s would have had the same problems like the Bf109F/G. It need much better shooting pilots to hit something.
Huhun always only count the firepower, while time to shoot and bullets per sec are also a very important factor, at least as long as the bullets are able to penetrate the target. This result in a higher hitprobability per armament and the lot of guns are also more reliable.
With the few percent of hits a normal WWII pilots was able to archive(i did read it was around 3 - 7%) a longer time to shoot to adjust the aim was a real advantage. Not many pilots was skilled like Graf, Hartmann, Moelders and Marsaille. The majority did shoot from much to long distance and wasnt able to calculate a good lead.
At the end of the war, with the new Gunsights, this problem got minimized much, but in 1943 and 44 many still effective guns imho was better vs Fighters than a few cannons.
The Brits did carry their .30cals not just for fun!! Same like the Germans they did use them to chase a enemy and to find a good lead to use the more effective but slow firing and low on ammo 20mm´s.
So if we assume a very good pilot, who got a hitquote per ammoload of maybe 30-50%, Huhun is right, while for the normal pilot the lot of guns, the more rounds persec per armament and the longer time to shoot probably was a advantage, at least vs smal nimble fighters.
Vs bombers iam all for cannons!
"Hohun wrote this
- The 8x 12.7 mm MGs did have about the firepower of 2 x 20 mm cannon.
- The 8x 12.7 mm MGs were about 684 lbs heavier than 2 x 20 mm cannon, with ammo and belting considered for both batteries."
But without ammo there is only a different of around 290lb.
And he also claim that 8 x .50cal have around the firepower of 2 x 20mm, thats true if we assume that always ALL bullets hit and that always ALL .50cal impacts are needed to down the fighter and if we dont care about the higher rate of fire of the .50cals.
If we see it per sec the 8 x .50cal shoot 104 rounds, while the HispanoII shoot only 20 rounds. Using Mr. Williams & Mr. Gustin´s guncalculation factors the 8 x .50cal have a more big firepower. The 2 x 20mm are closer to 6 x .50cal.
Accordinbg to Mr. Williams & Mr. Gustin´s the P47D had around 389kg(857lb) ammoload and a complete armament load(only guns and ammo, no belt etc) of 613kg(1350lb), so Huhun did assume a complete load for the 20mm´s of around 302kg(666lb inclusive 800 rounds).
According to Mr. Williams & Mr. Gustin´s thats a firepower of around 16000(this value is a calculation factor determinded by Mr. Williams & Mr. Gustin´s to compare the guns and their effectiveness) per amoload, while the P47D did carry a ammoload of 15640 destructive power.
Since 6 x .50cal was similar powerfull like the 2 x 20mm, they could have reduced the weight by deleting 2 x .50cal. So the weight already would have been down by 58kg(128lb).
And i never saw a cannon belt of 400rounds anyway. Was it possible to carry that many rounds in the P47 wing in ONE belt??
Edit: Made a typo and resulting a calculation misatke!
Greetings,
Knegel
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Originally posted by HoHun
Talking about the US pilots who apparently were satisfied, I'm sure that's because they were never given the choice between eight heavy (indeed) machine guns, or two cannon and the weight of their mount 684 lbs down.
Hm... if the the P-47 had been designed for the cannons, it would have been 4 x 20mm not 2 x 20mm. Four cannons would have been a clear improvement.
Originally posted by HoHun
(It's also telling that 9th Air Force P-47 pilots refused the installation of rear warning radars, since they felt that 50 lbs of extra weight were too much. Now extrapolate that reaction to 684 lbs ... :-)
This has probably much more to do with air war situation when the tail warning radar was introduced; fighter units of the 9th AF rarely met German planes in air, so very little need for such device.
Besides, the tail warning was a standard equipment from the P-47D-40 onwards, including the P-47N which had longer range that the P-51D and weighed full loaded over 20000 lbs, some 2500 lbs more than full loaded the P-47D-25. So the weight of the weapons seem to have been quite minor factor.
Originally posted by HoHun
Well, re-configure the P-47 with 2x Hispano cannon and some internal tankage, and the Thunderbolt "does it over Schweinfurt".
Well, the P-47N did much more without change of the weapons.
Originally posted by HoHun
The title of this thread is "Improve the P-47", and I have not seen any suggestion that would have yielded a greater improvement than simply exchanging the US gun for a model the British were already using with great success.
Regarding the title of this thread, 4 x 20mm would had been an improvement while 2 x 20mm would had been downgrade according to US Navy rating ie one 20mm cannon equals three 12,7mm MGs.
Originally posted by HoHun
To achieve air superiority, you have to destroy the enemy air force. Just pinging their planes is not enough, at least not in the long term.
The P-51 did actually destroy the Luftwaffe with half or 3/4 firepower of the P-47. The P-51 units claimed more air to air kills in Europe than P-47 and P-38 units combined.
Notable thing is that statistically the only cannon armed fighter of the three primary USAF fighters did this destroying work worst and the weakest armed did it best.
gripen
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giving the wings about 2-3 degrees of washout, vortex generators, winglets, outboard LE slats; setting the 'pit back a couple feet more to increase critical Mach number; Q-tip prop & adding a spinner over the prop hub would do a lot more for Thunderbolt performance than the few percent weight reduction thats been discussed for the last 100 posts
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Hi Debonair,
>giving the wings about 2-3 degrees of washout, vortex generators, winglets, outboard LE slats; setting the 'pit back a couple feet more to increase critical Mach number; Q-tip prop & adding a spinner over the prop hub would do a lot more for Thunderbolt performance than the few percent weight reduction thats been discussed for the last 100 posts
Good list, but are you sure all of them would actually have helped, or were 1943 technology at least? Washout for example would tend to reduce the wing's efficiency, and if you mount outboard leading edge slats anyway, you might not actually need it.
With regard to the "few percent weight reduction" though, you don't seem to appreciate the impact it would have had on performance. Just look at this weight comparison:
P-47D-25RE: ca. 14500 - 14700 lbs
Cannon Jug: ca. 13816 - 14016 lbs
P-47M: 13275 lbs
OK, the Cannon Jug would not have been equivalent to a stripped-down racer, but it would have benefitted both in performance and manoeuvrability. (Just one example: At high altitude, the climb rate improvement would have been around 25%.)
If you still have the impression, that weight savings in the region of 5% are insignificant - we're talking about aviation here where 5% weight more or less is a big issue.
What do you think would happen in Aces High if the Cannon Jug loadout would be added to the list? 684 lbs saved, two Hispanos instead of eight Brownings ... which loadout would the players choose?
Regards,
Henning (HoHun)
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Originally posted by Knegel
Hi,
with only 2 x 20mm the P47´s would have had the same problems like the Bf109F/G. It need much better shooting pilots to hit something.
Greetings,
Knegel
Knegel make a very good point in that the odds of getting a hit on the enemy drop substantially if you have but two cannon.
Using Aces High as an example. HTC has stated that they researched the ballistic behavior of all guns modeled in the game. They believe it to be as accurate as the platform can allow. So, let's compare the relative bullet patterns by pitting a pair of Hispanos to the eight-gun brace of the P-47. The Hispanos are from a Spitfire Mk.XVI. Only the cannons were fired.
Both images were generated using the .target command, range set at 1,000 yards. The Spitfire is on top, the P-47 below it. Both fighters have convergence set at 350 yards. Guns were fired for 3 seconds for both types.
(http://home.att.net/~ww2aviation/Twin-Hispano-1000.jpg)
(http://home.att.net/~ww2aviation/Eight-Fifties-1000.jpg)
I don't think it takes more than a glance to determine which gun set-up is most likely to score hits. Likewise, the concentration of the Fifties is impressive. Note also that the Hispanos show a pronounced "drop" when compared to the Brownings. For the P-47, this simplifies obtaining hits by a considerable margin.
Personally, I believe the effectiveness of the Brownings is much greater than just two Hispanos.
My regards,
Widewing
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Widewing,
Could you create similar presentation for the F4U-1C or the Typhoon because 4 x 20mm would have been practically only realistic alternative to the 8 x 12,7mm.
Thanks in advance.
gripen
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"Personally, I believe the effectiveness of the Brownings is much greater than just two Hispanos. "
Certainly in Aces High the Brownings are very accurate. But are they correctly modelled? Four guns stacked per wing (a large wing) and fired at the same time for three seconds are not likely to produce such concentrated pattern. The .50s in P38 could do that but the nose of the a/c is not subject to flexing in flight.
Of course for three seconds firing time the .50 start to produce a concentrated statisitical pattern but I find it hard to believe that wing mounted guns could produce that kind of pattern to 1000 yds -especially in flight.
Just my opinion.
Well, this is not the first time this matter has been discussed...
-C+
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Hi Widewing,
>I don't think it takes more than a glance to determine which gun set-up is most likely to score hits.
The question is, which setup is going to score more kills? A 20 mm Hispano projectile has 4.9 times the energy of a 12.7 mm API round. That's at the muzzle, at least - and due to the higher chemical energy of the 20 mm round that is not affected by drag, the balance shifts further in favour of the Hispano the farther you go downrange.
You'd have to draw at least five or six dots on the Hispano chart for each dot that is actually there to give a true impression of the comparative firepower (or hold the trigger down for at least five times as long) to give a true impression of relative firepower.
It's often overlooked that the probability for destruction of the target is Pd = Sum (Ph * Nh * Pk). When the probability of a hit is the same, the number of hits Nh has the same influence as the probability of kill for each hit Pk.
States at this, it becomes obvious that there is no inherent advantage in batteries with a high rate of fire unless "everything else is equal" - which in the case of machine guns and cannon does not apply.
Regards,
Henning (HoHun)
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Originally posted by HoHun
The question is, which setup is going to score more kills? A 20 mm Hispano projectile has 4.9 times the energy of a 12.7 mm API round.
Hm... the right question is, does supposed 4,9 times more energy mean same kind of ratio in the effectiveness of the round.
Not according to US Navy because they rated 1 Hispano equal to 3 M2s.
Originally posted by HoHun
You'd have to draw at least five or six dots on the Hispano chart for each dot that is actually there to give a true impression of the comparative firepower (or hold the trigger down for at least five times as long) to give a true impression of relative firepower.
Well, this part is (again) misunderstanding of probability; generally the M2 had roughly 20% higher ROF than the Hispano so per time unit the probability of the hit is better than assumed per projectile (assuming everything else equal). In addition the differences in ballistics might cause notable differences.
As an interesting sidenote there was a 1000-1100 rpm version of the M2 in production as early as 1939.
gripen
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"Not according to US Navy because they rated 1 Hispano equal to 3 M2s."
How did they figure that out?
I don't think HoHun is talking about the hit probability but firepower, which means hits yes, but also the effect of those hits.
The distance and HE performace makes it difficult to compare. At close range the 6x.50Cal may be as effective as two Hissos, but from a distance the better kinetic energy and HE content of 20mm requires the addition of one .50Cal to achieve the same effect with ROF effect added than the 2xHisso. If I had any math skills I'd calculate it...
Also remember that from extreme ranges the German Mine ammo is still almost as lethal than from point blank due to HE performance. :)
From shooter point of view the speed and flatness of bullet path is an asset of course.
-C+
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Hi Charge,
>"Not according to US Navy because they rated 1 Hispano equal to 3 M2s."
Note that I am talking about projectiles when I'm quoting a factor of 5.9 in favour of the Hispano. Using muzzle power, 1 Hispano equals 3.74 Brownings. (I'm not sure the US Navy used anything better than a rule of fist - arriving at an integer number is such a comparison doesn't look overly accurate.)
>I don't think HoHun is talking about the hit probability but firepower, which means hits yes, but also the effect of those hits.
Since people seem to get confused by different "probabilities", I'll just call it lethality so that we know what we are talking about:
L = Nf * Ph * Pk
Firepower would be:
FP = ROF * Pk
Note that this does not include hit probability, which depends on the situation and is not directly determined by the weapon.
Regards,
Henning (HoHun)
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Hit probability IS determined by the weapon. The last time we fooled with them the Ma Duece 50 BMG was more accurate and ballistically superior to the 20mm cannon. The 50 BMG shoots a much flatter trajectory, and, loaded with ammo NOT designed to create dispersion, shot a tighter group. When shooting over a RANGE of distances, especially where the distance is not a given, but instead must be judged by the shooter by an educated guess, the round with the flatter trajectory will score the greater number of hits PER ROUND FIRED. Further, when you factor in the variables in rate of closure, convergence factors over the distances involved, and the various factors introduced by deflection shooting, flatter trajectory makes a HUGE difference.
Yes, it is true that the 20mm in a number of forms has become the round of choice on U.S. fighters. However, they are now fired from the various GE electric "Galting Gun" type cannons with a rate of fire far beyond what was possible in World War II. Further, the average modern fighter pilot has more hours in training than the average fighter pilot in World War II had in total flying time. Also, the modern fighter pilot has all sorts of true computer aided sights. Comparing even Vietnam era fighters to World War II fighters is far more useless than comparing apples and oranges.
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Hi Hilts,
>Hit probability IS determined by the weapon.
It's determined by multiple factors, including the weapon. That's the reason it's not part of the firepower definition as above.
Think of a sniper rifle - it does not have much raw firepower, but it can be highly effective anyway.
(It only makes a difference for the point where you enter the Ph factor "per round fired", as you correctly noted, into the equation.)
>The 50 BMG shoots a much flatter trajectory, and, loaded with ammo NOT designed to create dispersion, shot a tighter group.
As a P-38 fan, I'm sure you're familiar with the Bore Sighting Chart for the type, which shows only a small difference between 20 mm and 12.7 mm trajectories? (If not, I'd offer to post it.)
Of course, the P-38 with its nose mounted armament was one of the best planes regarding long range fire, so at extreme range you'd actually notice the longer drop. The "effective boresight range" against a fighter-sized target is about 800 m for the 12.7 mm on the P-38, I haven't entered the Hispano II data yet but it should be slightly less than that.
The pattern size of course depends (among other factors) on the rigidity of the mounting, and for aircraft guns, the 12.7 mm gave a relatively wide pattern in a wing mount. Again, the P-38 is pretty ideal since nose mounts tend to be quite rigid.
>Comparing even Vietnam era fighters to World War II fighters is far more useless than comparing apples and oranges.
Did I do that? I thought I deleted that paragraph before posting :-)
But seriously, the USAF went to cannon in the Korean war, and the Gatling guns came only later.
Regards,
Henning (HoHun)
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the P47 is the bestest plane in World War 2 period.
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Nonono. It's teh Fairey Swordfish:D
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Originally posted by Charge
I don't think HoHun is talking about the hit probability but firepower, which means hits yes, but also the effect of those hits.
The correct way to present this is just claim that each hit is more effective - at arguable multiplier. Presenting this as longer shooting time gives wrong impression of hitting probability, which is in the case of Hispano roughly 20% lower for each gun due to ROF at given time frame assuming everything else equal.
The effect of the round naturally depends on target - historically the M2 did well against German fighters.
Originally posted by HoHun
Note that I am talking about projectiles when I'm quoting a factor of 5.9 in favour of the Hispano. Using muzzle power, 1 Hispano equals 3.74 Brownings. (I'm not sure the US Navy used anything better than a rule of fist - arriving at an integer number is such a comparison doesn't look overly accurate.)
Well, notable thing is that there is no reason to believe that US Navy rating - despite what ever way it's created - is some how biased. They choosed Hispano after war; 4 x 20mm, not 2 x 20mm.
gripen
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Originally posted by gripen
... wrong impression of hitting probability, which is in the case of Hispano roughly 20% lower for each gun due to ROF at given time frame.
My mistake, wrong wording. Should be: ... wrong impression of number of hits which is in the case of Hispano roughly 20% lower for each gun due to ROF at given time frame.
gripen
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"The effect of the round naturally depends on target - historically the M2 did well against German fighters."
I'd say that particular statistical effectiveness depended from other reasons. However, I'm not saying the Jug had bad weaponry. IIRC in Meimberg's memoirs he was shot down by a Jug a couple of times, and when the Jug did hit his 109 the plane was pretty much in pieces and it was time to bail out. I think that if the Jug had had 20mms he would have been dead.
But still the 109 was armed with only one MG151/20 for some time and I think for typical use of that aircraft it was enough. E.g. Marseille's success was indication of this. But the shooter had to be accurate to be successful with single 20mm. The 4x20mm of FW190 favored the average shooters better.
-C+
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Charge,
As you are Finnish speaking, you probably know how extreme can be pilot's expriences on effect of the weapons on various targets. One well known extreme is Sarvanto's case; six DB-3 Bombers in 5 minutes with a Fokker D.XXI and 4 x 7,7mm MG. Another extreme can be Karhila's case after bombing of the Lappeenranta base 2.7.1944, Karhila (known as a good shooter and one of the few Finnish aces who preferred wing cannons in Bf 109) was flying the MT-461 with wing cannons and met six Il-2s, used all his ammunition from close range but could not get any of them (story can be found from SILH 2/2001).
gripen
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Individually, if a 20mm round hits, it can be 3-5 times stronger than any single US 50cal impact.
However, consider that 2x Hispanos firing at 600rpm does 20 rps (rounds per second). A battery of 8 50cals firing at 500rpm does 66 rps.
Going by the example of a 3 second burst (already shown) that means the Hispanos fired 60 rounds total, only a few of which would have hit. The Brownings would have fired 198 rounds total, well over half of which would have hit the target.
In my perspective, a couple scattered 20mm hits is nothing compared to over a hundred 50cal impacts (conservatively estimating half weren't scattered in the screenshot dispersion), all in the same area.
Mind you, just an opinion based on all the info already presented (rates of fire looked up on the Internet)
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Hi Krusty,
>Individually, if a 20mm round hits, it can be 3-5 times stronger than any single US 50cal impact.
>However, consider that 2x Hispanos firing at 600rpm does 20 rps (rounds per second). A battery of 8 50cals firing at 500rpm does 66 rps.
Good approach.
It's the same as this one: L = Nf * Ph * Pk
As you see, the difference in number of rounds fired and probabilty of kill multiply, so L (Hispano) = 60 * 4.9 * PK * Ph while L (Brownings) = 198 * 1.0 * PK * Ph. (Introducing PK of unknown size as lethality of 1 Browning projectile.)
That yields:
L (Hispano) = 294 * PK * Ph (Hispano)
L (Browning) = 198 * PK * Ph (Browning)
Note that just as Hilts already pointed out, the Ph figures for both weapons are different. Ph does of course depend on the situation.
>Going by the example of a 3 second burst (already shown) that means the Hispanos fired 60 rounds total, only a few of which would have hit. The Brownings would have fired 198 rounds total, well over half of which would have hit the target.
Hm, I don't understand how you assign hit probabilities here. If the Browning has Ph > 0.5, I can't imagine the Hispano having Ph = 0.1 or something. They both share a very flat trajectory out to 700 yards at least, with just a couple of inches deviation from the common sight line.
>In my perspective, a couple scattered 20mm hits is nothing compared to over a hundred 50cal impacts (conservatively estimating half weren't scattered in the screenshot dispersion), all in the same area.
Hm, it would be helpful to have an aircraft silhoutte in that diagram. At 1000 yards, it would probably be surprisingly small ...
Regards,
Henning (HoHun)
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Hm... Generally the ROF of the M2 is listed around 650-750 rpm (13 rps in Tony's site) so:
8 x M2: 8 x 13rps x 3s = 312 rounds/3s
2 x Hispano: 2 x 10rps x 3s = 60 rounds/3s
4 x Hispano: 4 x 10rps x 3s = 120 rounds/3s
Assuming as an example 10% hit probability for each projectile for both guns:
8 x M2: 31,2 hits/3s
2 x Hispano: 6 hits/3s
4 x Hispano: 12 hits/3s
Assuming that one firepower of a Hispano equals 3 x M2 (according to US Navy) ie as an example one second burst of 10 rounds from Hispano equals 39 rounds from three M2s. This gives ratio 3,9 for a Hispano round ie one hit from Hispano equals 3,9 hits from M2 so relative hit sum would be:
8 x M2: 31,2 hits/3s
2 x Hispano: 23,4 hits/3s
4 x Hispano: 46,8 hits/3s
So using US Navy rating, the 2 x 20mm would had been a downgrade while 4 x 20mm would had been an improvement. And if the ROF of the M2 had been increased to 1100 rpm, it would have resulted 44 hits/3s at same conditions ie very close the relative firepower of the 4 x 20mm, almost twice firepower of the 2 x 20mm and all this without large modifications to the airframe.
BTW US Navy rating might be well based on test shots on real airplanes and analysis of gun camera films. At least the Brits made such analysis so probably that was possible for the US Navy too.
gripen
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I'd pretty much agree that given sufficient magazine capacity for each gun, having FOUR 20mm cannons on the P-47 would have been at least somewhat of an upgrade in armament. However, there's no way I'd think that TWO 20mm cannons would even be equal to the eight M2 50BMG gun set, nevermind any sort of an improvement.
As a side note, I would say that four 20mm cannons with around 250-300 rounds per gun would have been a serious step up compared to the standard gun set on a P-38, since Hohun brought it up. However, I do not think that the standard gun set on a P-38 is better than the standard gun set on a P-47, other than where the guns are located. So I still do not think that ONE 20mm cannon is an adequate replacement for FOUR M2 50BMG's.
Back on the actual subject of this thread, the gun set is the last thing I'd be looking at were I going to improve the P-47. And I would certainly NOT consider removing the turbocharger either. If anything, I'd likely increase the size of the turbocharger enough to eliminate the problem of over rev at higher altitudes. If you're trying to make a piston engine perform at maximum potential over a wide range of altitudes, it is near impossible to beat a turbocharger. Otherwise, the current generation of piston engine GA aircraft wouldn't have so many turbocharged versions at the top end of the scale performance wise. There wouldn't be so many high end turbocharger kits available as upgrades, either.
The truth is, the U.S. aircraft were just a little behind the curve in evolution for the early part of the war, mostly because of the USAAF/USAAC and their myopic lack of foward vision. They didn't really do a great deal to inspire innovation, and did a lot to stifle progress. Examples are scattered throughout the development history of many aircraft.
Merely accelerating the development curve for most of the aircraft in the inventory, the P-47 included, and removing the roadblocks brought on by ignorance and arrogance would have brought better planes into battle earlier. And don't forget that some really big improvements never saw production, but were shelved in the interest of cost and expedience. One need only look at the Sherman tank to see the Russians weren't the only ones to believe quantity has a quality all its own.
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Originally posted by gripen
Widewing,
Could you create similar presentation for the F4U-1C or the Typhoon because 4 x 20mm would have been practically only realistic alternative to the 8 x 12,7mm.
Thanks in advance.
gripen
As requested...
Typhoon, followed by the F4U-1C and the P-38L for good measure. I have included a rear view of a Fw 190D-9 in the P-38L image. Range was 991 yards. I transferred the same image, in red, to the target of the P-38.
(http://home.att.net/~ww2aviation/Typhoon-1000.jpg)
(http://home.att.net/~ww2aviation/F4U-1C-1000.jpg)
(http://home.att.net/~ww2aviation/P-38L-1000.jpg)
My regards,
Widewing
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Originally posted by HoHun
Hi Debonair,
>giving the wings about 2-3 degrees of washout, vortex generators, winglets, outboard LE slats; setting the 'pit back a couple feet more to increase critical Mach number; Q-tip prop & adding a spinner over the prop hub would do a lot more for Thunderbolt performance than the few percent weight reduction thats been discussed for the last 100 posts
Good list, but are you sure all of them would actually have helped, or were 1943 technology at least? Washout for example would tend to reduce the wing's efficiency, and if you mount outboard leading edge slats anyway, you might not actually need it.
With regard to the "few percent weight reduction" though, you don't seem to appreciate the impact it would have had on performance. Just look at this weight comparison:
P-47D-25RE: ca. 14500 - 14700 lbs
Cannon Jug: ca. 13816 - 14016 lbs
P-47M: 13275 lbs
OK, the Cannon Jug would not have been equivalent to a stripped-down racer, but it would have benefitted both in performance and manoeuvrability. (Just one example: At high altitude, the climb rate improvement would have been around 25%.)
If you still have the impression, that weight savings in the region of 5% are insignificant - we're talking about aviation here where 5% weight more or less is a big issue.
What do you think would happen in Aces High if the Cannon Jug loadout would be added to the list? 684 lbs saved, two Hispanos instead of eight Brownings ... which loadout would the players choose?
Regards,
Henning (HoHun)
washout done properly reduces induced drag, increasing wing efficiency.
important at high altutudes where indicated airspeeds are low.
even more so if you're interested in high altitude aerobatics.
i'd bet widening the low airspeed end of the flight envelope is a big deal for dogfighting up there.
shrinking the back side of power curve helps too
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I've read over this thread in detail and wanted to bring in a POV from someone who uses the P-47 as his main ride. I'm not sure how many in responding to this thread fly in AH, besides Widewing and myself, but these are my thoughts based on the simulation fidelity HTC has allowed us to participate in.
1. The notion of 8x50 being replaced with 2x20: I violently disagree with this and it would be a step backward.
2. 8x50 being replaced with 4x20: If you fly a F4U-C or Tempest on a regular basis, then there is some merrit in a mod like this. However - for me personally, I wouldn't be comfortable with the gravity drop of the 20mm over the distances I usually fire at.
I treat the P-47 like a paper shreader - my guns stagger from 400 up through 475 and overlap from banks 4 on inward to 1. I must be doing something right because according to the website my hit % hovers between 10 and 12 % fairly consistantly - but that should be considered and abbiration as i'm not a normal pilot by any means of the word. SLA Marshall and a few others post WW2 conducted a study and later wrote a book titled Men Under Fire: The Problem of Battlefield Command in which he wrote 25 % of soldiers engaged in direct action fired their weapons.
Now the correlation is this - when you consider the stresses of combat and the lack of experience you were dealing with in handling complex machinery - 10 % is a number which, in most estimations which is way up there in god territory. More realistic for your typical pilot is 1.5-3 % hit percentage, with the average creeping up to 5 %.
When I examine members of my squad, some of whom have been around a few years and others who are fairly recent - the average tends to be in the 7% range. With Shawk's group who has more pilots, on the higher range of 7% boardering 8 %.
The point which I am failing to make is this - the P-47 series is deadly enough without even considering 4x20's in the wings. I have very little issue with runs averaging 6-10 kills, and sometimes higher if fuel permits. For me, the sheer amount of lead going out - 103 rounds per second is staggering even in a virtual enviroment. Being in the Marines showed me first hand what a single BMG gun could do - you just don't want to be on the recieving end of 1, let alone 8 paired together.
S!
Wolf
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Hi,
regarding the armament hit probability so kill probability many dont seems to see that not only the armament is a factor!!
As long as a target fly strait or is very big and get attacked right from 6oc, a slow firing gun have exact the same hitprobability per ammoload like a fast firing gun, therfor i would tend to use cannons vs big targets(bombers), specialy cause the better penetration of the structure.
Interesting it get when the target roll/turn/dive/climb and if the attacker is forced to estimate a deflection.
MG´s in general tend to have a much longer time to shoot, therefor its good possible to adjust the aim while shooting, without to waste to much of the ammoload. Additionally many MG´s dont let a "open window" between each bullet, also this is very important, specialy while shooting with a high deflection.
Imho the Tempest, HurriIIc and F4U-1c only are extremely danagerus in the H2H area with extended ammo load. In the other areas, with normal ammo load, the pilot need to be much more carefully not to run out of ammo.
Time to shoot is a big aspect of the armament hitprobability and MG´s in general could carry much more ammo!
P47D could shoot 32sec.
F4U-1c 23sec.
Tempest only 11,5sec.
HurriIIc only 9sec.
SpitIXc 12sec.
Of course the F4U-1c, HurriIIc, Typhoon and Temp had a extremely good firepower and vs not or slow moving groundobjects and bombers this is very good. But what is the firepower worth, if the pilot dont have enough ammo to adjust a bad calculated lead(the F4U-1c is almost a exception here, but still have 30% less time to shoot that the P47)??
While shooting to a smal fighter from a perfect attacking position(short range, 6 oc, enemy fly strait) or if the pilot was able to calculate a perfect lead, even 2 x MG17 + MG151/15 was good enough, like Mr. Marsaille and Mr. Graf did proof in a very impressive way.
Therefor i think with increasing distance and attackingangle, but decreasing pilot skill, the need of more guns or faster shooting guns with big ammoload, NOT more powerfull guns, was needed! (vs Bombers of course more powerfull guns was better, while the .50cal still was effective vs fighters on common shooting ranges)
At the end of the war and after the war, the computed gunsights did improve the hitprobability much, cause the pilot as influence got almost deleted. Therefor the need of a very long time to shoot wasnt needed anymore, so a smal number of cannons probably would have been a big improvement, cause they was effective vs fighters, bombers and groundobjects, on a longer range(with the computed gunsights long range hits got much more likely) and they was more light.
Greetings,
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Hi Hilts,
>However, there's no way I'd think that TWO 20mm cannons would even be equal to the eight M2 50BMG gun set, nevermind any sort of an improvement.
Well, the firepower would be equivalent - improvement really would be the weight saving (or fuel increase).
>However, I do not think that the standard gun set on a P-38 is better than the standard gun set on a P-47, other than where the guns are located. So I still do not think that ONE 20mm cannon is an adequate replacement for FOUR M2 50BMG's.
Hm, do you consider the gun set of the P-38 inferior (firepower-wise) then? In my opinion, it's about equal to the P-47's.
>If anything, I'd likely increase the size of the turbocharger enough to eliminate the problem of over rev at higher altitudes.
I think this was actually done throughout the life-span of the P-47, but it would be hard to rush this kind of progress to get a better Jug in 1943.
>Otherwise, the current generation of piston engine GA aircraft wouldn't have so many turbocharged versions at the top end of the scale performance wise. There wouldn't be so many high end turbocharger kits available as upgrades, either.
Well, but the general aviation aircraft are so slow that they can't reap the benefit of exhaust thrust anyway, and the turbo-supercharger is more economic which is important if you're paying for your own fuel. (And for range, too - my suggestion to delete the turbocharger is based on the idea that a lighter, smaller mechanical supercharger setup will allow more extra fuel to be carried than the more thirsty engine will drink :-)
>The truth is, the U.S. aircraft were just a little behind the curve in evolution for the early part of the war, mostly because of the USAAF/USAAC and their myopic lack of foward vision. They didn't really do a great deal to inspire innovation, and did a lot to stifle progress.
Hm, do you think so? In my opinion, there were many innovative aircraft helped on the way by the USAAC/USAAF, their weakness was just that they were not designed as accurately for their combat environment as the European types. (Might be a good spin-off thread :-) I see only one recurrent weakness of the US designs, and that's a habitual disregard of the impact of airframe weight.
Regards,
Henning (HoHun)
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Hi Debonair,
>washout done properly reduces induced drag, increasing wing efficiency.
important at high altutudes where indicated airspeeds are low.
Ah, I see what you mean. Did you mean this just as a general suggestion, or was the P-47 found lacking with regard to high-altitude wing efficiency? I'm asking because the NACA reports often provide this kind of insight, so if there's a good one on the P-47, well, I'd be interested :-)
Regards,
Henning (HoHun)
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Hi Widewing,
>I have included a rear view of a Fw 190D-9 in the P-38L image.
Thanks, that's a good benchmark! :-)
Regards,
Henning (HoHun)
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Hi Wolfala,
>1. The notion of 8x50 being replaced with 2x20: I violently disagree with this and it would be a step backward.
Judging by Widewing's graphs, it seems that the Hispano has a bit more dispersion than the 12.7 mm in Aces High, while I believe the situation was the reverse in real life.
>I treat the P-47 like a paper shreader - my guns stagger from 400 up through 475 and overlap from banks 4 on inward to 1.
Interesting idea! In some other game that didn't allow such fine control, I used up to 600 yards with the P-47 (for all guns) and got good results, too, so I think I see your point.
>More realistic for your typical pilot is 1.5-3 % hit percentage, with the average creeping up to 5 %.
Certainly. It's the same with the errors in "precision bombing" - the average error in actual combat was far greater than what the man-machine combination would actually have allowed.
>The point which I am failing to make is this - the P-47 series is deadly enough without even considering 4x20's in the wings.
How would you feel about 2x 20 mm and 684 lbs weight reduction? (Or a fairer question might be, how about 4x 12.7 mm and 684 lbs weight reduction?)
From experience in Air Warrior, the Dora they had was quite effective despite being a bad lead sled, but in real combat I'd have considered it seriously handicapped. Just to point out that I don't mean to confuse online flying and reality - but your opinion on online flying would be interesting for me anyway! :-)
Regards,
Henning (HoHun)
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Originally posted by Widewing
As requested...
Typhoon, followed by the F4U-1C and the P-38L for good measure.
Thanks, seems that at least in AH, the P-47 has very good concentration of projectiles around the target at long range.
Originally posted by Wolfala
Now the correlation is this - when you consider the stresses of combat and the lack of experience you were dealing with in handling complex machinery - 10 % is a number which, in most estimations which is way up there in god territory. More realistic for your typical pilot is 1.5-3 % hit percentage, with the average creeping up to 5 %.
I used 10% just as an example, the German data gives following values assuming steady about four engined bomber size target (30m2) right behind at variable range 1000->300m:
Good shooter 15,9%
Average shooter 7,05%
Poor shooter 3,98% or less
In practice results are claimed to be more like half of these in real combat and other factors like deflection etc. might cause large difference.
gripen
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Originally posted by Wolfala
The point which I am failing to make is this - the P-47 series is deadly enough without even considering 4x20's in the wings.
The point HoHun is making and a few missed is that replacing mg with cannons is not a way to increase firepower but to save weight (while keeping about equivalent firepower).
I tend to agree with this, assuming the reliability of 20mm was sufficient. 684 lbs weight reduction? I'd take that anytime.
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Originally posted by bozon
The point HoHun is making and a few missed is that replacing mg with cannons is not a way to increase firepower but to save weight (while keeping about equivalent firepower).
Well, keeping the about equivalent firepower would have been 2 x 20mm and 2 x 12,7mm according to US Navy rating (which is claimed to be based on somekind of real testing). There would have been still some weight savings and also some modifications would have been needed to airframe.
gripen
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In an plane as heavy as the P47, saving 600lbs wouldn't help. Somebody kept pointing out how the P47M weight was only about 800-1000lbs lighter and was such a great performer -- well the M had a different engine or rating than the D which is the real reason it was such a performer.
Take out 2 of the 50 cals. And their ammo. How much weight does that save? Take out half the ammo on the remaining guns. Now how much have you saved. You now have the same firepower as 2x20mm (6x50cal) at nearly the same weight savings. Nearly. Not the same, mind you. Cannon planes had their own problems, it wasn't a "magic bullet" solution, IMO. Putting 2x20mm in a plane and nothing else was just begging for complaints.
Besides, the P47 was/is so damn heavy that you couldn't really make it a turn fighter by removing the guns. You couldn't really add more fuel. You couldn't really do much without a major redesign (like the 47N's wing). Taking that weight out wouldn't have made it perform *that* much better, and wouldn't have allowed wing tanks (not much, at least) for extra gas.
Just my opinion.
P.S. I go into combat with my centerline tank sometimes in AH to keep the gas that much longer. If I'm in a D25 or later I'll drop the wing tanks first and keep the centerline. If I get in trouble I'll drop that one too.
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According to Tony's site, there was plenty of problems in the developement of the American version of the Hispano so reliability might had been an issue too.
gripen
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Originally posted by bozon
The point HoHun is making and a few missed is that replacing mg with cannons is not a way to increase firepower but to save weight (while keeping about equivalent firepower).
I tend to agree with this, assuming the reliability of 20mm was sufficient. 684 lbs weight reduction? I'd take that anytime.
His original argument was that the change in armament would create the reduction in weight, which would allow for enough extra internal fuel to escort U.S. bombers all the way to their target and back. Therefore, you keep the weight, you just trade armament for range. The only problem is that, aside from his turbo to super exchange, he still hasn't explained how the change in armament frees up enough room for the extra gas. Only the turbo/supercharger change would create space, so really, the armament question is moot without room in the airframe for the required volume of fuel. So really, his argument should be an analysis of how much worse the high altitude performance would be and how the 2X20mm armament would compensate for it.
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Hi Krusty,
>In an plane as heavy as the P47, saving 600lbs wouldn't help.
It would, especially at high altitude where induced drag, which is increases with weight, plays an important role. At high altitude, you'd get a 25% climb rate increase from saving 684 lbs.
>well the M had a different engine or rating than the D which is the real reason it was such a performer.
They cut the weight to improve performance, no way around that :-) If all the goodies do no harm, why give up some of the goodies?
>Take out 2 of the 50 cals. And their ammo. How much weight does that save? Take out half the ammo on the remaining guns. Now how much have you saved.
Before: 8x ,50 Browning M2 - 375 rpg - 562 kg - 100% firepower
After: 6x ,50 Browning M2 - 187.5 rpg - 298 kg - 75% firepower
-> 582 lbs weight savings.
>You now have the same firepower as 2x20mm (6x50cal) at nearly the same weight savings.
Well, but you have only half the ammunition, too :-) You could make this change instead:
Before: 8x ,50 Browning M2 - 375 rpg - 562 kg - 100% firepower
After: 2x Hispano II - 115 rpg - 157 kg - 94% firepower
-> 893 lbs weight savings.
(Note that I doubt the accuracy of the Navy's factor of "3" between the two gun types. The Luftwaffe used a factor of 3.34 between the MG151/15 and the MG151/20, and the MG151/15 was much more potent than the 12.7 mm Browning.)
>Putting 2x20mm in a plane and nothing else was just begging for complaints.
Well, the Navy planned to replace the 12.7 mm gun with the Hispano cannon because the 12.7 mm jammed in long bursts, and the Hispano didn't. The Hispano was quite reliable in British service, and if the USAAF would have placed more management attention on the gun, it could have been available in reliable form for them, too.
>You couldn't really add more fuel. You couldn't really do much without a major redesign (like the 47N's wing).
Oh, we're talking about just 110 gallons here. As described way up in this thread, you can simply extend the engine mount a bit more to shift the centre of gravity forward and mount a small tank in the rear fuselage. The rest can be stored in the space saved in the gun bays and perhaps in small wing tanks outboards. I'm not quite sure how much fuel the P-47N could take, but I'd bet the increase was by much larger than 110 gallons.
Regards,
Henning (HoHun)
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Originally posted by AquaShrimp
The P-47 was relegated to ground attack work because of its short-commings.
But would it have really be neutered? Cannons were far superior to machine guns in ground atttack work. In one Korean War test, twenty 50 caliber rounds and twenty 20mm rounds were each fired into a seperate truck. The 50 caliber rounds merely broke the drivers seat, while the 20mm rounds exploded the vehicle.
Stressed skin has been mentioned a few times to be more fragile than non-stressed, but I've never seen any confirmation of this.
This thread is long so i'm sure this has been covered but your somewhat clueless. The P-47 was an outstanding interceptor and very capable in that role. In fact it was every bit the equal of the P-51. What it didnt have was the P-51's range so as the pony was deployed the P-47 (and P-38) were redelpoyed in support of the tactical airwar.
There is a famous quote regarding the P-51 that goes something like this.
It's not the P-51's capabilities that make it special, its that it has those capabilities over Berlin....
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Originally posted by HoHun
(Note that I doubt the accuracy of the Navy's factor of "3" between the two gun types. The Luftwaffe used a factor of 3.34 between the MG151/15 and the MG151/20, and the MG151/15 was much more potent than the 12.7 mm Browning.)
The German rating for the destruction factor in the case of the "minen" typen projectiles was based on assumption that about 400g of HE content was required to down one four engined bomber. The kinetic energy was not accounted at all because the type of the large target. Because there apparently was no "minen" type projectile for the MG151/15, this rating favors heavily MG151/20. Based on total energy (including kinetic) the difference is much smaller.
Generally the rating of German air weapons were driven by the need to destroy extremely large targets like four engined bombers. The US Navy rating was probably based on targets they usually assumed to meet in combat.
Originally posted by HoHun
Well, the Navy planned to replace the 12.7 mm gun with the Hispano cannon because the 12.7 mm jammed in long bursts, and the Hispano didn't. The Hispano was quite reliable in British service, and if the USAAF would have placed more management attention on the gun, it could have been available in reliable form for them, too.
Hm... at least according to Tony's site, the reliability problems seem to have been mostly in American version of the Hispano side delaying the Navy's move to the cannon armament, the British version being more reliable.
gripen
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AFAIK the barrel length does not itself provide more accuracy, only better muzzle velocity and thus flatter trajectory. Thus I wouldn't be surprised if MK108 was more accurate than either Browning or Hispano if scatter was concerned. But MK108's shortcoming is bad trajectory. Imagine trying to hit a bomber at long range by "dropping" a 30mm round on it...
I'm not sure if I read somewhere that Hispano II was prone of jamming because of drum feed. Was the H II never made as belt fed?
Hisso V was belt fed with shorter barrel and better RPM, anybody knows if it was more accurate than H II?
-C+
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The the belt fed mechanism for the Hispano 404 was originally designed in France (by Chattellerault ??) and IIRC the first plane to utilize it was the MB.155. The Brits made their own version of this system and it replaced the drum fed mechanism around late 1941/early 1942.
Regarding the accuracy, the high velocity and flat trajectory are advantages as well as some amount of dispersion because vast majority of the error comes from the shooter (error being practically allways systematical). I've posted some German data here (http://www.hitechcreations.com/forums/showthread.php?s=&postid=1995488#post1995488).
gripen
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"The Brits made their own version of this system and it replaced the drum fed mechanism around late 1941/early 1942."
So the Hisso II was already modified for belt feed.
I have to disgree with you to some extent Gripen. If you look at the dispersion patterns presented previously and consider the size of the a/c then I'd say that the smaller dispersion will give you higher probability of hits at extreme ranges.
But when you are maneuvering and shooting at the same time the pilot's accuracy plays a huge role, of course. At some ranges the disperison can have good effects, too, but getting scattered hits with weapon which has ammo that does not have much effect will not do you much good.
Anybody have the disperison pattern for P38's Hispano?
-C+
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Well, the problem of the Hispano patterns posted by Widewing is that the concentration of the bullets is not in the target area (notable drop at 1000 yards if compared to to patterns of the P-47). Disperion itself is not particularly different based on just looking the patterns; density of the pattern of the P-47 is greater due to more guns and higher ROF.
According the data I posted (linked above), even a good shooter itself cause dispersion which is far greater than dispersion caused by the guns (steady target). Note also that usually 400 yards is considered as the limit of practical shooting range (more in the case of the large bombers).
gripen
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"Well, the problem of the Hispano patterns posted by Widewing is that the concentration of the bullets is not in the target area"
That is what troubles me. IIRC the patterns should look pretty much the same for Hisso and 50Cal. It would be intersting to see the actual patterns.
I have too the "Lentoampumaoppi" but the actual firing test did not have the luxury of steady target at set distance and autopilot to keep the plane still while shooting as we have in AH.
IRL the effect of pilot ability was certainly a major factor when accuracy was measured at reasonable firing distances, not to 1000yds.
-C+
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Originally posted by HoHun
Hi Krusty,
Before: 8x ,50 Browning M2 - 375 rpg - 562 kg - 100% firepower
After: 6x ,50 Browning M2 - 187.5 rpg - 298 kg - 75% firepower
-> 582 lbs weight savings.
>You now have the same firepower as 2x20mm (6x50cal) at nearly the same weight savings.
Well, but you have only half the ammunition, too :-) You could make this change instead:
Before: 8x ,50 Browning M2 - 375 rpg - 562 kg - 100% firepower
After: 2x Hispano II - 115 rpg - 157 kg - 94% firepower
-> 893 lbs weight savings.
Regards,
Henning (HoHun)
Hi,
again he dont see the pretty important factor of time to shoot!!
8x .50 Browning M2 - 375 rpg = 29sec time to shoot.
6x .50 Browning M2 - 187 rpg = 14,4 sec time to shoot.
2 x Hispanno II - 115rpg = 11,5sec time to shoot.
Afaik the P47 already was one of the best high alt performer in WWII, probably the best build in high numbers, so a weight advantage wasnt realy needed.
Imho the damage power of 20mm´s in relation to .50cals while fightercombat get overvalued anyway.
A fighter hand much more vital areas than a Bomber and a good hitprobability the pilots only could gain on distances where even the .50cal was likely to cause damages. Therefor every .50calround had a not to bad probability to cause vital damages, while also the tracerrounds of the 20mm´s dont was as effective and also the 20mm´s 1st had to get through the surface to cause real bad damages and i guess this also wasnt always the case.
Specialy while escort missions its better to damage a enemy than to miss him at all and the probability to at least damage a enemy increase with fireratio and time to shoot and reliability of the guns.
The .50cal may have tend to jam at long bursts, the 20mms simply dont had enough ammo to make long bursts. Let jam 2 out of 8 .50cal, the pilot still had the same time to shoot still with the firepower of 2 x 20mm.
I personally dont would like to be some hundret miles behind the frontline, trying to keep enemy fightes away from my bombers with only 115rounds per gun in 2 guns. I would better choose 4 x .50cal with 475 rounds per gun for this task to safe weight.
Greetings,
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From another board by Butch2k:
H means Height (or max dispersion diameter) as i previously used vertical and lateral dispersion values.
D means distance.
Units are metric.
German Weapons
-----------------------
MG-17 Cowling mounted (Bf 109F-2 / Bf 109F-1 actual tests)
H = 0.60 / 0.8 m
D = 100 m
H/D = 60/10000 80/10000
= 6 mils / 8 mils
MG-131 Cowling mounted (Fw 190A - theorical max)
H = 1m
D = 100m
H/D = 100/10000
= 10 mils
MG-151/15 Engine mounted (Bf 109F-2 actual test)
H = 0,35 m
D = 100 m
H/D = 35/10000
= 3.5 mils
MG-FF Engine mounted (Bf 109F-1 actual test)
H = 0,2 m
D = 100m
H/D = 20/10000
= 2 mils (very tight patern)
MG-FF Wing mounted (Bf 109E-3 actual test)
H = 0,35 m
D = 100m
H/D = 35/10000
= 3.5 mils
MG 151/20 Engine mounted (Bf 109G-6 - theorical max)
H = 0.3m
D = 100m
H/D = 30/10000
= 3 mils
MG 151/20 Wing mounted - inner (Fw 190A - theorical max)
H = 0.7m
D = 100m
H/D = 70/10000
= 7 mils
MG 151/20 Wing mounted - outer (Fw 190A - theorical max)
H = 0.8m
D = 100m
H/D = 80/10000
= 8 mils
MK 108 Engine mounted (Ta 152 - therorical max)
H = 0.35
D = 100m
H/D = 35/10000
= 3.5 mils
Allied Weapons
------------------
M2 Nose mounted P-38 (USAAF 1944 Gunnery manual)
H = 1.88 m
D = 229 m
H/D = 188/22900
= 8.2 mils (75% = 4.1 mils)
Hispano 20mm Nose mounted P-38 (USAAF 1944 Gunnery manual)
3 mils 75%
6 mils 100% assumed
Notice that the 151/20 dispersion is much bigger in wing installation even in FW190 which has a rigid wing. So if the same percentage for added dispersion would be added to wing mounted Browning it would have dispersion of what? Roughly 13 mils?
-C+
PS. Knegel, your attitude troubles me. If you have an issue with somebody throw him a PM and sort it out.
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Originally posted by Charge
I have too the "Lentoampumaoppi" but the actual firing test did not have the luxury of steady target at set distance and autopilot to keep the plane still while shooting as we have in AH.
While some what simplified, it's a good book, giving good view to the complexity of the aerial shooting.
Non steady target and other factors would generally cause increasing error which is mostly systematical, therefore also some amount of dispersion will help.
gripen
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I made an interesting find on the Inter-web-a-majiggy today, when looking for something else.
(http://www.airwar.ru/image/i/fww2/p47d-i.jpg)
So if you took the SC and put it behind the engine, like the hellcat (for example) you wouldn't need all that ducting and piping and you'd have room for almost another full "main" tank. -- probably could double the internal tankage. However, the SC takes up nearly all of it (certainly not enough room left for even a small tank.
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Charge:
I don't buy those theoretical max numbers. Those "theoretical max" numbers seem VERY high, especially considering the same gun in the same central position (tested in nose vs theoretical in wing root) has more than double the dispersion. Doesn't add up. At least to me.
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Going back to the cutaway view:
(http://rwebs.net/avhistory/images/P47cutaw.jpg)
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Hi Krusty,
>So if you took the SC and put it behind the engine, like the hellcat (for example) you wouldn't need all that ducting and piping and you'd have room for almost another full "main" tank.
Roger that, clear case.
>However, the SC takes up nearly all of it (certainly not enough room left for even a small tank.
Ah, thanks for the side view! I see plenty of room there:
http://hometown.aol.de/HoHunKhan/p47d_extra_tank.jpg
The brownish area is 1 m x 0.5 m. If you make this a tank 0.9 m wide, you get 450 L (ca. 119 gallons) of volume for an extra tank.
Note that I'd move the radio and oxygen bottles further back into the rear fuselage. As they are fixed weight, it's easy to balance them with the engine mount extension I mentioned above.
(The fuel as variable weight couldn't be balanced as easily because you have two different situations, full and empty tank! :-)
So it would be possible to store the requried fuel internally without even needing to use the wings, which have a storage potential, too. (The F4U-1 had 124 gallons of fuel in the wings, just to calibrate the sense for realistically possible volumes.)
Regards,
Henning (HoHun)
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Originally posted by Krusty
I made an interesting find on the Inter-web-a-majiggy today, when looking for something else.
(http://www.airwar.ru/image/i/fww2/p47d-i.jpg)
So if you took the SC and put it behind the engine, like the hellcat (for example) you wouldn't need all that ducting and piping and you'd have room for almost another full "main" tank. -- probably could double the internal tankage. However, the SC takes up nearly all of it (certainly not enough room left for even a small tank.
thing is the ducting at the bottom of the plane protected the pilot rather well.... doing away with that wouldnt make much sence?
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Originally posted by Krusty
ISo if you took the SC and put it behind the engine, like the hellcat (for example) you wouldn't need all that ducting and piping and you'd have room for almost another full "main" tank.
You are absolutely correct Krusty, as is HoHun. Replacing the turbo with a supercharger would free up space. However, what would the performance difference be? The Hellcat couldn't make near the power at 30K feet that the P-47 did. I'm guessing that escorting bombers flying at 28K that the high altitude performance was as important as range? Maybe more important? There was no other fighter in the world at the time that could match the performance at that operational altitude. At those altitudes, it also boasted the best rate of climb of any fighter of the time.
Think about this, early on in 1943, in both the Atlantic and Pacific theaters, the commanders complained about the Jugs short legs. If I was an engineer at Republic, that would become my biggest priority. First improvement in the P-47 was adding the fat belly to the C's and it was incorporated in the D's rolling off the assembly line. The kit when fitted, added the plumbing necessary to use pressurized drop tanks. That's "Extend the range improvement" #1 in early '43. Then, the D-15 was fitted with pylons to allow even more fuel in drops--improvement #2. When the D-40 was introduced, it carried more internal fuel than the earlier models--improvement #3. Then, the mother of all improvements with the N model that could fly 9 hour missions, carrying almost 2/3rd's more fuel than the D models internal--improvement #4. The P-47N began flight testing in summer of 1944, so you could assume that the new wing design began some months (at least) before then.
So, I contend that Republic was fairly tenacious about improving the overall capability of the aircraft as soon as feedback from the various theaters identified the weakness of its range. Remember, this aircraft was designed based on pre-WWII design criteria, and I personally feel that they made just about every improvement they could without totally changing the design or character of the aircraft. I guess I should have made this argument earlier...
EDIT: Is there any way to simulate the difference in performance at altitude using a supercharger application a la the Hellcat or Corsair? Same engine, except for the N model Jug.
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Hi Overlag,
>thing is the ducting at the bottom of the plane protected the pilot rather well.... doing away with that wouldnt make much sence?
Hm, that was a welcome side effect of the turbocharger installation and probably not something that was considered indispensable. I believe most other WW2 fighters had no comparible structures anyway, so the Jug might have survived without it, too.
From a strategic point of view, having escort fighters over Schweinfurt would have been a great advantage, and losing the extra protection and the crumple zone provided by the ducting would have been only a small tactical disadvantage.
So if in 1942, someone would have told the USAAF top brass stuff like "according to our evaluation of gunnery training results, we can't count on the bombers to defend themselves, and according to intelligence on Luftwaffe bases and capabilities, we're going to be in deep trouble if we start our strategic bombing campaign", they might have had the chance to order a longer-ranged variant of the P-47 into production if they acted quickly and decisively.
Thinking about it, January 1943 as orignally suggested by Aquashrimp might not be early enough to have the fighter available in strength ...
Regards,
Henning (HoHun)
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Originally posted by HoHun
So if in 1942, someone would have told the USAAF top brass stuff like "according to our evaluation of gunnery training results, we can't count on the bombers to defend themselves, and according to intelligence on Luftwaffe bases and capabilities, we're going to be in deep trouble if we start our strategic bombing campaign", they might have had the chance to order a longer-ranged variant of the P-47 into production if they acted quickly and decisively.
Thinking about it, January 1943 as orignally suggested by Aquashrimp might not be early enough to have the fighter available in strength ...
Well, if USAAF had wanted escort fighters capable to reach Schweinfurt 1943, the most realistic options would had been the P-51B, P-38 and Spitfire VIII. All these were in production, were used by USAAF and had required range with only minor modifications (wing tanks etc.).
But in reality USAAF believed that escort fighters were not needed; the P-51B was allocated to 9th AF, most P-38s went to MTO as well as Spitfire VIIIs.
The P-38 missed Schweinfurt by days, the P-51B by couple months while the P-47N missed it by 1,5 year.
gripen
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Originally posted by Krusty
So if you took the SC and put it behind the engine, like the hellcat (for example) you wouldn't need all that ducting and piping and you'd have room for almost another full "main" tank.
I'm not sure you can do away with the ducting as they are needed for more than just transporting the gases and I believe they need some minimum volume. In the P-38 they run along the wing in order to make them long enough. Anyone knows?
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Originally posted by bozon
I'm not sure you can do away with the ducting as they are needed for more than just transporting the gases and I believe they need some minimum volume. In the P-38 they run along the wing in order to make them long enough. Anyone knows?
Only the early P-38 had intercooler ducts in the outer wings, and they weren't just ducts, they were the actual intercoolers, just long empty boxes that ran along the leading edge of the wing where they'd be exposed to cold air. But those ductwork type intercoolers were very inefficient, and prevented the engines from running full boost. They'd have had to have been longer still to have cooled the air enough to work well.
The late P-38 had chin mount intercoolers, and the reason the ductwork was long (it ran from the turbocharger behind the engine forward to the intercoolers and then back to the engine, but did not run through the wings) is that they had the turbocharger behind the engine, and the new core type intercooler had to be in the chin of the cowl in front of the engine in order to work. It made the system more efficient, but it made for a much tighter fit inside the fuselage, making service work even more difficult.
The truth is, the longer the duct work for the intercooler, the more turbo lag you have, because you have a longer distance for the pressure change to travel. You mount the intercooler where it is the most efficient at removing heat, because that is the most important factor.
My T Type Regal has the turbocharger mounted directly on the top of the engine, and has no intercooler at all. I use methanol injection to cool the charge. The only "piping" is a very short tube with two o-rings that adapts the turbocharger compressor outlet to the intake, and the throttle is bolted directly to the compressor.
The later version of my Regal had the turbocharger mounted on the front of the engine and two short hoses that ran from the compressor to the intercooler (right in front of the engine, there is a fan on the harmonic balancer to draw air through it) and from the intercooler to the throttle, now mounted AFTER the compressor and the intercooler. However, that intercooler is small and inefficient, when you modify the car, one big step is to mount a large intercooler out in front of the radiator and condenser and run longer hoses. The larger intercooler flows more air, but is also exposed to colder air by not being behind the radiator.
In the case of the P-47, it might have been possible to adapt a small version of the P-51 radiator cooling system for use as an intercooler system allowing greater intercooler efficiency and use of the heated air for added thrust. It would depend mostly on the increase in drag as compared to the increase in efficency and the added thrust.
In the case of the P-38 it might have been possible to enlarge the radiators and their bulges and mount the core type intercoolers in front of the radiators, and also use the P-51 style cooling. The boudary layer scoop used to take in air for the radiator on the P-51 didn't increase drag much and did help to increase air pressure on the radiator, raising cooling capacity, it was that scoop that allowed the pressurized and heated air from the radiator to create thrust. It might have been possible to do the same on the later P-38, and the slicker early cowls could have been left alone to decrease drag there. It would also have shortened the ductwork and created a cleaner installation.
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Originally posted by gripen
Well, if USAAF had wanted escort fighters capable to reach Schweinfurt 1943, the most realistic options would had been the P-51B, P-38 and Spitfire VIII. All these were in production, were used by USAAF and had required range with only minor modifications (wing tanks etc.).
But in reality USAAF believed that escort fighters were not needed; the P-51B was allocated to 9th AF, most P-38s went to MTO as well as Spitfire VIIIs.
The P-38 missed Schweinfurt by days, the P-51B by couple months while the P-47N missed it by 1,5 year.
gripen
gripen is exacly correct here. It was again a problem with short sighted and careless leadership that brought on unescorted bombers, and not a lack of suitable planes (there was a lack of numbers, but not types). Even if they believed that the bomber could get through without escorts, it would have been wise to escort them anyway, to allow them the greatest chance to do the job. The reason MORE fighters with BETTER range and BETTER performance weren't already there is not because they couldn't be built or couldn't be built YET, but because the people running the show didn't WANT them because they didn't think they NEEDED them. It was then easy to say the nightmare of unescorted daylight bombing came about because of a lack of suitable planes, AFTER the fact. It hid the fact that the planes could have been there and been ready had it not been for poor decisions. Blaming Lockheed and Republic for not having enough planes and having them ready made things easy to hide, or swallow, depending on your view point.
Remember that the 20th and 55th fighter groups went operational in less than 60 days (less than 30 in reality for some) with the P-38H, while the P-38J was not only in production, but being delivered to training units, and the P-38K, with greater range and speed even than the P-38L, had been declined by the WPB because of a required two week production delay. The P-38 capacity at Lockheed Burbank could have been DOUBLED by moving the Lockheed Burbank B-17 lines to any number of companies capable of producing heavy bombers, like Consolidated Vultee Nashville, where, of all things, they were trying to build P-38's.
At the time, for increased range, the P-47 need only a fuel system modification and some drop tank work, and this was known LONG before Schweinfurt, and there were PLENTY of P-47's.
The P-51 was close to being ready, but even after deployed, it suffered some serious engine problems. This too could have been solved earlier had it not been for the myopic and stubborn insistance on unescorted bombing.
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Hi Hilts,
>In the case of the P-47, it might have been possible to adapt a small version of the P-51 radiator cooling system for use as an intercooler system allowing greater intercooler efficiency and use of the heated air for added thrust.
The intercooler was of course necessary even without the turbo-supercharger to get good high-altitude performance. In a non-turbocharged P-47, it would be possible to set the intercooler very close to the front firewall, reducing ducting losses. Probably a minor thing, the main point really would be to free the fuselage space.
>In the case of the P-38 it might have been possible to enlarge the radiators and their bulges and mount the core type intercoolers in front of the radiators, and also use the P-51 style cooling.
Interesting idea - I guess that would really have been a speed booster for the P-38. Was the P-38 ever used in racing, and if it was, did they try anything like this? (I recently read an article on a modified P-38 which, judging from the photograph, didn't appear to have any turbo-superchargers mounted, though the article attributed a recent emergency landing to turbo failure. Somewhat confusing.)
>it was that scoop that allowed the pressurized and heated air from the radiator to create thrust.
Hm, I'm a bit sceptical about net thrust, but it appears that the jet cooler reduced the power lost to cooling to a term increasing linearly with speed, while all other drag increases to the cube of speed. That means that at high speed, cooling drag becomes almost neglectible compared to parasite drag.
Regards,
Henning (HoHun)
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Much of the ductwork on the P-47 had more to do with where the turbocharger was located than anything else. You can get away with less or no intercooling with a mechanical crank driven supercharger, depending on how efficient it is. But without an intercooler on a turbocharger you have to reduce boost by about 50%, unless you use chemical cooling (like the methanol injection I use, or the propane injection some use).
If you were to mount the intercooler by the firewall, you'd KILL efficiency. an intercooler really has to have a great deal of air flow to be effective, AT LEAST as much as a radiator. Mounting it behind the engine and between the engine and the firewall would reduce efficiency a great deal.
I don't know how much the cooling system/intercooler change would help the P-38, but it likely wouldn't hurt.
I agree, it wasn't really that the cooling system on the P-51 made it faster, it's just that it created the least amount of net loss.
The last P-38 raced at Reno that I remember is Lefty Gardner's "White Lightning" (since sold to "Red Bull" drink corporation), and it is VERY stock. In fact, it uses, or used, stock surplus engines right out of the crate. The last time I saw it the turbochargers were not mounted, just the shields and covers were there. It also is set up as an early type recon plane with the low drag cowls. From what I understand, the "modification to "White Lightning" is only that it was converted from a late model P-38 recon plane to an early model. That's what I was told and saw evidence of, it may have changed.
IF that is indeed the case, then it cannot have the turbochargers on it, because a late model would not have the ductwork intercoolers in the wings, and the plane cannot have the core type intercoolers in the chins, because it has the early chin which has no room for intercoolers. It also did not have the sound that the turbochargers give, it did not sound anything like "Porky II" or "Glacier Girl". It is my understanding that "Glacier Girl" is the ONLY early model to have flown in several decades that DOES have operational turbochargers.
Best I remember, no one has raced a P-38 seriously with any sort of budget in at least 30 years. They are far too rare and too expensive, and racing one would be very expensive, you need twice the amount of parts. I think Lefty hit 399MPH a few years ago, with a stock, unmodified P-38. It could be done, and made to be very fast, but you need to spend enough you could buy "Dago Red" (was the fastest P-51 at Reno the last few years) and all the spares, plus a complete back up plane that would be fast enough to get to the "Silver" Unlimited race.
Lad Gardner, Lefty's son, put "White Lightning" down in a cotton field in Greenwood Mississippi about 4 years or so ago, maybe more, because of a carburetor fire. It was towed to a hangar and set back on its gear, but they couldn't raise the funds to repair it, so it was sold. That's the only P-38 I've heard of making an emergency landing here in years. The others were all actual crashes. About 15 years ago, both engines on the CAF P-38 quit on takeoff, and it crash landed, both people on board were badly hurt, and the CAF has made no progress in repairing it that I'm aware of.
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i'm not sure a P-38 could safely handle enough of a Mach number to be competetive at reno (would be about 0.67 ), especially so close to the ground. I'd love to see what an F-82 could do. Someone should buy Strega & Dago Red and biuld them into a Twin Mustang
:O :O :O :O
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Hi Hilts,
>You can get away with less or no intercooling with a mechanical crank driven supercharger, depending on how efficient it is. But without an intercooler on a turbocharger you have to reduce boost by about 50%, unless you use chemical cooling (like the methanol injection I use, or the propane injection some use).
For very high altitude performance, an intercooler is very important as the high compression ratios will heat the charge considerably. One reason the Dora was not a good high-altitude aircraft was the lack of an intercooler, and if I remember correctly, even the Dora versions with a Jumo 213E/F had to resort to methanol-water cooling to compensate for the lack of an intercooler, just like the turbochargers you mention.
>If you were to mount the intercooler by the firewall, you'd KILL efficiency. an intercooler really has to have a great deal of air flow to be effective, AT LEAST as much as a radiator. Mounting it behind the engine and between the engine and the firewall would reduce efficiency a great deal.
Hm, maybe I didn't explain it clearly enough: I was thinking of keeping the existing intake on the P-47, but moving the intercooler to a point just aft of the firewall. Shortening the ducts should be beneficial, the only thing to watch out for is to keep it away from the hot engine, which would heat up everything and reduce efficiency, which is probably what you are warning against.
>The last P-38 raced at Reno that I remember is Lefty Gardner's "White Lightning" (since sold to "Red Bull" drink corporation), and it is VERY stock. In fact, it uses, or used, stock surplus engines right out of the crate. The last time I saw it the turbochargers were not mounted, just the shields and covers were there.
>Lad Gardner, Lefty's son, put "White Lightning" down in a cotton field in Greenwood Mississippi about 4 years or so ago, maybe more, because of a carburetor fire.
Ah, thanks, that must have been my mystery plane! Beautiful non-military blue-white-red paintjob? The turbocharger failure story didn't make much sense, but a carburettor fire would probably demand an immediate emergency landing. I hope the new owner will succeed in bringing White Lightning back up into the air!
Regards,
Henning (HoHun)
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Originally posted by Debonair
i'm not sure a P-38 could safely handle enough of a Mach number to be competetive at reno (would be about 0.67 ), especially so close to the ground. I'd love to see what an F-82 could do. Someone should buy Strega & Dago Red and biuld them into a Twin Mustang
:O :O :O :O
Most pilots, especially test pilots like Levier, Burcham, Mattern, and Kelsey said that critical Mach and compression were not a factor below 20K feet. Besides, these days they modify the planes enough that they could alter the wing profile. The two main reasons for the wing profile that causes the problem on the P-38 are fuel capacity and high altitude/high rate of climb, and neither of those is necessary at Reno.
I think the big draw back to a P-38 or an F-82 would be the extreme expense of reducing drag on a larger plane, plus the extreme expense of having two engines (most teams don't have a really good spare, imagine having two on the plane PLUS a spare) since they have over $100K in the engine, and in the case of the Merlin it is a grenade with the pin pulled. They KNOW the Merlin IS going to come apart, the only question is when and how bad. The other thing about a twin is that if the inside engine blows quickly while you're in a turn at near 500MPH, the outside engine would probably fly you right into the ground. Even the big radials blow up, though not as bad or as often as the Merlins.
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I'd bet that Mach number wasn't a factor below 20k for those gentlemen because they just didn't reach the speeds needed to hit high enough Mach numbers below 20k, but at Reno, with density altitudes probably about 7500' i'd bet a stock airframe P-38 would be in the range of Vuh-uh if it was running at a competetive speed (about Mach 0.65 - 0.7?). Of course i'm no expert & those guys who handle the racing planes are. It surprised the crap out of me when they broke 500, especialy at low altitudes & with the all the turns, you'd have to guess they can do even a bit more traveling just straight ahead...i think i'd like them to let one of the stormbird.com 262s race, just to see it finish way back lolol
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Hohun,
In the case of the two speed two stage crank driven superchargers on most U.S. planes, they still didn't make near as much power above 25K. I'd have to look at the charts, but the P-51 for example was down to around 900-1100 HP at 27K, so they weren't making enough boost to make heat or power up high. The thing about a crank driven supercharger, be it Roots style or centrifugal, is that heat and inefficiency increase exponentially with RPM. So does the HP drag. You can only turn them so fast before they absorb a lot more power than they make by compressing air. The only choice is to make them bigger. Then they become heavy and take up way too much space. Also, they begin to make so much heat that you cannot cool the charge enough because you cannot put enough intercooler on it, since an intercooler requires space, and requires a substantial amount of air flow to exchange heat. Granted, at high altitude the air is much cooler, but it is also much thinner, requiring more air volume to absorb the same amount of heat (a cubic foot of air at 30K contains less air than a cubic foot of air at sea level).
Now that I understand exactly where you wanted to mount the intercooler, it has a better chance of working that way, but I doubt you can get enough air through it to make it efficient, and when you factor in the paragraph above regarding the efficiency of crank driven centrifugal superchargers, I still don't think you could make the P-47 perform as well as it did without the turbocharger. I just don't think you could put a big enough supercharger on it or spin a smaller one fast enough.
Yes, "White Lightning" has had a red, white, and blue paint job for years. The carb fire got so bad that it burned a substantial section of the fuselage and parts of the wing, and it was in danger of spreading to the fuel system. The smoke got so bad in the cockpit that Lad said he could barely see or breathe. The damage from landing was not terrible, but it needed about $100K worth of repairs, and Lefty is well into his seventies, they simply ran out of time and money, either the plane had to fly and make some money or they had to sell it.
My only fear is that a corporation will not take good care of the plane and spend what needs to be spent to make sure it is in perfect condition. If the accountants get control of the project, corners will be cut, and when you are dealing with planes like that, whether it is a P-38 or an Me109, you simply cannot allow money to be an issue, you have to spend whatever it takes, because a failure will destroy the plane and possible kill people. Besides that, ther probably aren't 20 pilots in the entire world qualified to actually FLY a P-38. Sure, there are pilots who can ferry one around, but if you're going to fly one for a show, you need someone with the talent and skill that a couple of guys at Planes of Fame have, and few others. LLoyds of London does not require that Steve Hinton be the only pilot in command of "Glacer Girl" just for fun.
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Originally posted by Debonair
I'd bet that Mach number wasn't a factor below 20k for those gentlemen because they just didn't reach the speeds needed to hit high enough Mach numbers below 20k, but at Reno, with density altitudes probably about 7500' i'd bet a stock airframe P-38 would be in the range of Vuh-uh if it was running at a competetive speed (about Mach 0.65 - 0.7?). Of course i'm no expert & those guys who handle the racing planes are. It surprised the crap out of me when they broke 500, especialy at low altitudes & with the all the turns, you'd have to guess they can do even a bit more traveling just straight ahead...i think i'd like them to let one of the stormbird.com 262s race, just to see it finish way back lolol
I'll have to look it up, or maybe Widewing will have it handy, but I'm thinking Levier was exceeding critical Mach substantially in compression tests and exceeding 500MPH below 20K during the pullout. And remember that the critical Mach figure was for 1G. The Lockheed dive tests were VERY severe, and extensive. I know that Warren Bodie had copies of or access to the log books, and maybe Widewing can post what was in them, as he knows Warren Bodie a lot better than I do.
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Hi Hilts,
>I'd have to look at the charts, but the P-51 for example was down to around 900-1100 HP at 27K, so they weren't making enough boost to make heat or power up high.
Hm, I haven't looked it up yet either, but the P-51B first used a higher-geared supercharger and got quite impressive very high altitude performance from it. The Spitfire IX had a similarly high full throttle height at first, and both types were using intercoolers (or aftercoolers).
>Now that I understand exactly where you wanted to mount the intercooler, it has a better chance of working that way, but I doubt you can get enough air through it to make it efficient
Hm, I should be able to get the same amount of air through it as for the turbo-supercharger as all cross sections of the system remain unchanged, and the engine will not require any more air than before.
>I still don't think you could make the P-47 perform as well as it did without the turbocharger.
It's probably going to be a close thing, and I'm certainly going to lose some performance in the region between low gear and high gear full throttle height. A certain amount of performance loss would be acceptable to get the desired increase.
However, after Krusty posted the side-view that shows that the P-47D still had room for a good amount fuel without removing the turbo-supercharger, the mechanically-supercharger P-47 has lost some of its attractiveness since room for fuel was the main point of pulling the turbine.
>I just don't think you could put a big enough supercharger on it or spin a smaller one fast enough.
I believe size would not be a problem since the R-2800 has a much larger frontal area than the Merlin, and the Merlin manages to "hide" the supercharger almost completely. The R-2800 needs more air, but it's much larger, too.
However, something I hadn't thought of before: It might be that we don't have any suitable mechanical supercharger "off the shelf" in 1943. The R-2800 as used in the F6F and F4U is not sufficiently supercharged to compete with the turbine, and I don't know if there were larger superchargers available. As it takes some time to design and manufacture one, that might kill the project (unless we allow a longer lead time).
(With turbo-superchargers, it was not uncommon to mount two per engine, but that was greatly aided by the uncomplicated way of driving two turbines by simply piping half of the cylinders' exhaust to each. One could use two mechanically driven, smaller superchargers, but only at a cost of a complex drive train. I'm not aware of any actual application like that.)
>The carb fire got so bad that it burned a substantial section of the fuselage and parts of the wing, and it was in danger of spreading to the fuel system. The smoke got so bad in the cockpit that Lad said he could barely see or breathe.
That sounds worse than I imagined. Good thing he put it down before anything happened to the structure!
>LLoyds of London does not require that Steve Hinton be the only pilot in command of "Glacer Girl" just for fun.
Hm, reminds me of something John Deakin mentioned (or maybe I should say "preached"): With the passing away of the "old" generation who still have the professional skills to make Warbirds work (and fly them), it's getting harder and harder for the operators to keep the aircraft flying. It seems that despite all encouragement by the CAF and other organisations, they can't get enough enthusiasts to learn some of the required skills :-(
Regards,
Henning (HoHun)
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Originally posted by Debonair
I'd bet that Mach number wasn't a factor below 20k for those gentlemen because they just didn't reach the speeds needed to hit high enough Mach numbers below 20k, but at Reno, with density altitudes probably about 7500' i'd bet a stock airframe P-38 would be in the range of Vuh-uh if it was running at a competetive speed (about Mach 0.65 - 0.7?). Of course i'm no expert & those guys who handle the racing planes are. It surprised the crap out of me when they broke 500, especialy at low altitudes & with the all the turns, you'd have to guess they can do even a bit more traveling just straight ahead...i think i'd like them to let one of the stormbird.com 262s race, just to see it finish way back lolol
Hi,
the mach numbers wasnt a problem below 20k simply cause the Mach 1 in lower alt (less cool air) is not the same speed like Mach 1 in high alt(cool air).
Mach 1 at 20°C is around 1235km/h (768ph), so Mach 0,7 = 537mph.
At -50 degree(supposed to be in 10km alt) Mach1 is only around 1079km/h and so Mach0,7 decrease to 470mph.
Since the Reno Airrace is rather in low level and at a temperature rather above 20° the mach problems shouldnt be a real problem.
Greetings,
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Agreed, there are too few around to pass along the skills. Sadly, it is also a question of money. It takes a lot of hours to get proficient, and that takes time, and more importantly fuel plus wear and tear on planes. The CAF apparently is having trouble even keeping what they have flying now maintain, judging by the number of recent mechanical failures that have resulted in crashes, some fatal and also destroying planes as well. And even great pilots in well maintained planes make tragic errors, as recently demonstrated close to home here when Art Vance was killed and the F6F-5 from Planes of Fame was destroyed. A great man and a great plane were lost just miles from my home. I go by there about 5 or 6 times a year, and it bothers me every time.
I have always said that if I hit the lottery big, I'd buy a warbird (a P-38, no doubt), but I'd also buy a trainer, and pay Steve Hinton whatever he wanted to teach me to fly as well as he does before I ever even taxied my prized warbird. I told him that a year or so ago, when we were standing next to "Glacier Girl". I've talked to my uncle, who has thousands of hours, about learing to fly, but I don't have the time or money right now. If I did, I'd get him to teach me, and I'd get my IFR and my twin rating before I ever flew any real distance, so that I'd be prepared for weather or other problems.
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"The truth is, the longer the duct work for the intercooler, the more turbo lag you have, because you have a longer distance for the pressure change to travel. You mount the intercooler where it is the most efficient at removing heat, because that is the most important factor."
As I side note: IMO the lag is not a problem in aircraft as you do not really throttle it much, and if you do, you do not need immediate respose as you do in a car.
-C+
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Originally posted by Captain Virgil Hilts
I'd get my IFR and my twin rating before I ever flew any real distance, so that I'd be prepared for weather or other problems.
ME with instrument rating doesn't guarantee you'll be prepared for problems. It just means you'll have the potential for twice the problems in IFR conditions.
I just wish there was some way to simulate the difference in performance for a P-47D with supercharger vs. turbo. Is there a way to plug Hellcat engine performance numbers into a P-47D airframe and see what the difference would be?
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Originally posted by Stoney74
ME with instrument rating doesn't guarantee you'll be prepared for problems. It just means you'll have the potential for twice the problems in IFR conditions.
No, but getting IFR rated means if I hit weather and IFR conditions I'll have at least SOME idea what I'm supposed to be doing.
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Hi Hilts,
>Sadly, it is also a question of money. It takes a lot of hours to get proficient, and that takes time, and more importantly fuel plus wear and tear on planes.
Roger that!
I recently read a quite interesting book, "On Men and Mustangs", about two brothers who built a 2/3 scale Mustang replica. Tom Short had originally decided to buy a real Warbird in 1970, when the prices were steeply rising but still affordable, but his brother Thayne suggested building a replica instead. With a view on the irreplacable nature of the "real thing" and the increasing operation cost, Tom considered that the better option, and together they built an absolutely neat replica (which took years).
They had started off with plans for a steel-tube fuselage with glass fiber skin, and teamed up with Harold Dale, an aircraft designer who had worked at North American on the original P-51, to design a complete plane according to their requirements.
Their declared goal was to produce "a plane that will look, sound, feel and fly exactly like a P-51 Mustang". They probably got very near to perfection in that regard (and could probably have gotten even closer if they had found a suitable V-12 engine instead of the V-8 they had to rely on). Another goal was to make the design a standard kit in order to make it easier for other builders to get results quickly and at a reasonable price, but I guess that never worked out as planned.
However, I think they took a very interesting route, and it's telling that even in 1970, Warbirds were slipping out of the financial reach of rather well-off people. Tom Short had actually decided on a Mustang as real Warbird first because it was one of the more economic WW2 aircraft around. Now we've got 2006, and the development he observed has continued for more than three decades ...
Replicas have not been the breakthrough the Shorts have hoped for, but they have not vanished from the scene either ... maybe they're going to play a bigger role in the future.
Regards,
Henning (HoHun)
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Hi Debonair,
>at Reno, with density altitudes probably about 7500' i'd bet a stock airframe P-38 would be in the range of Vuh-uh if it was running at a competetive speed (about Mach 0.65 - 0.7?).
Reno is at about 5000 ft, and 500 mph TAS at that altitude work out to about Mach 0.67 (on a standard day).
As Hilts pointed out, the severity of the Mach problems depend on the G load, and as the Reno races include rather steep turns (I don't know the actual G figures, but from the bank angles evident in the photographs, they're not neglegible :-), a non-modified P-38 woud probably be at a disadvantage.
The diving case is a bit different from the racing case because in a dive, you welcome the Mach-induced drag increase and don't mind a certain loss of elevator authority as long as it doesn't result in dangerous pitching tendencies.
For a racer, the Mach-induced drag increase would of course be somewhat counter-productive, and I imagine you'd be more sensitive against control issues as well when going around the pylons at top speed, too.
So it's not just a question of the plain Mach number, but also of what the symptoms are if you "push against the envelope".
Regards,
Henning (HoHun)
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Hi Charge,
>As I side note: IMO the lag is not a problem in aircraft as you do not really throttle it much, and if you do, you do not need immediate respose as you do in a car.
The British Aircraft Purchasing Commission tested the P-38 with turbo-superchargers and found that the turbines need 10 s to spool up from idle to full power. That meant that on take-off, you'd have to hold the P-38 on brakes until the engines were running at full power, or you'd suffer from a rather long take-off run (because you'd make most of it at less than full power).
With the P-38, the tricycle landing gear made this procedure easy, but I wonder how the P-47 handled it since as a taildragger, it would tend to nose over if you'd run it up to full power ...
Regards,
Henning (HoHun)
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Seen as how the Model used here for Performance ratings doesn't match the actual Historical ones of the P-47, especially @ Low Alt., as w/ most A/C models used in the game, it's no wonder you wish this.
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Originally posted by HoHun
Hi Charge,
>As I side note: IMO the lag is not a problem in aircraft as you do not really throttle it much, and if you do, you do not need immediate respose as you do in a car.
The British Aircraft Purchasing Commission tested the P-38 with turbo-superchargers and found that the turbines need 10 s to spool up from idle to full power. That meant that on take-off, you'd have to hold the P-38 on brakes until the engines were running at full power, or you'd suffer from a rather long take-off run (because you'd make most of it at less than full power).
With the P-38, the tricycle landing gear made this procedure easy, but I wonder how the P-47 handled it since as a taildragger, it would tend to nose over if you'd run it up to full power ...
Regards,
Henning (HoHun)
I don't recall ever reading about a nose-over of a Tail-dragger going full power while standing on the brakes to get max performance for T/O.
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Originally posted by Col. Flashman
Seen as how the Model used here for Performance ratings doesn't match the actual Historical ones of the P-47, especially @ Low Alt., as w/ most A/C models used in the game, it's no wonder you wish this.
What, specifically, is incorrect with the P-47 performance models?
My regards,
Widewing
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Mostly they inability to achieve Max Acelleration & Top Speed @ Sea Level up to 15,000', as w/ the majority of the A/C in AH that I've been experimenting w/ in the Off-line portion of the game.
Unless there is a difference in Performance models between the Off-line & actual combat situations when flying against other players.
I've had the pleasure of getting unofficial stick time, to be able to actually add this to my Log-book would be a pip, in most of the American A/C used in the game from privately owned A/C, Piggyback versions, @ the A/P I flew out of, these were not stripped down either & the researching of actual Combat Pilot reports & interviews there of.
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Originally posted by Col. Flashman
Mostly they inability to achieve Max Acelleration & Top Speed @ Sea Level up to 15,000', as w/ the majority of the A/C in AH that I've been experimenting w/ in the Off-line portion of the game.
Performance is modeled from actual test data. Pilot reports are largely useless for modeling aircraft. What data are you using?
My regards,
Widewing
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Originally posted by Captain Virgil Hilts
The last P-38 raced at Reno that I remember is Lefty Gardner's "White Lightning" (since sold to "Red Bull" drink corporation), and it is VERY stock. In fact, it uses, or used, stock surplus engines right out of the crate. The last time I saw it the turbochargers were not mounted, just the shields and covers were there. It also is set up as an early type recon plane with the low drag cowls. From what I understand, the "modification to "White Lightning" is only that it was converted from a late model P-38 recon plane to an early model. That's what I was told and saw evidence of, it may have changed.
Looking the pictures from Reno in the Gardner's web site (http://p38whitelightnin.com/gallery/general/); the engines are handed and there is no turbos installed. If the engines were stock with original 8,1:1 SC gear ratio, it's unlikely it could do much more than 60" even if running at 3200rpm or bit more at 5k. So the speeds reached in the race were probably much less than 500mph true.
gripen
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"The British Aircraft Purchasing Commission tested the P-38 with turbo-superchargers and found that the turbines need 10 s to spool up from idle to full power. That meant that on take-off, you'd have to hold the P-38 on brakes until the engines were running at full power, or you'd suffer from a rather long take-off run (because you'd make most of it at less than full power)."
Interesting. I'd say that the spooling time is because of the supercharger size, not because of the piping or intercoolers. The turbo probably needs to be quite big to be able to feed the engine sufficiently up high, so the exhaust thrust in ground level only slowly accelerates the turbine. That means that if you cut the power from full throttle the waste gate opens wide open and the boost is readily available for some time since the turbine does not slow down rapidly.
At least thats how I understand it....
-C+
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Originally posted by Widewing
Performance is modeled from actual test data. Pilot reports are largely useless for modeling aircraft. What data are you using?
My regards,
Widewing
Thank'ee for responding.
I travelled to Air Shows quite a lot between the ages of 8 & 35, where I met & spoke w/ Test, Pursuit Ship & Fighter Pilots about the A/C they tested & actually flew in Combat during WW II. I’ve also an informative collection of Aviation material covering this era of flight & have had access to Original Spec Sheets/Books/Lit on the A/C I was rather interested in. :aok
I managed to get a ride by paying for 1/2 the fuel & got a tick of unofficial stick time in the Piggyback version of the P-40, as well as several other different Piggeyback Fighters in Private Owner/Operator hands. We were able to achieve well over 340mph IAS in the P-40 between Sea Level & 15,000’ w/ full fuel on board, there were exact weight fake 50s mounted in the wings & according to the Owner/Pilot, we were @ least 3/4 Combat Loaded during this flight & he really wrung the Olde Girl out for me, I had a slight green tinge when I climbed out afterwords. :aok
So what you are stating here is that what the Combat Pilots actual experiences under Varying Weather & Combat Conditions in regards to the Performance & Handling characteristics of the A/C they are flying w/ full, 3/4,1/2,1/4, Combat Loads, finding that the Indicated Air Speed, Climb Rate, Power Dive Ability, Turn Rate, etc., was better or worse or the same when measured against the Test Data stated in the Spec Sheets & from the Test Pilots sent by the Company that were on hand for the training flights, is of no consequence & useless to you. :confused:
I’ve read here that the P-40 cannot Power Dive to save itself, so it can speed away @ tree-top-level from an opponent, to enable the Pilot can Climb back to Alt. to start all over again. :confused:
Which happens to be the one of the Main Combat Tactics taught to P-40 Pilots to keep from being shot down so that they can re-engage or arrive back to their Aerodrome safely. P-40 Pilots have reported 600mph IAS during Power Dives, which scared the Devil out of them not believing they'd be able to pull out of it & were able to maintain speeds over 400mph IAS @ tree-top-level before the climb back for Alt. FEAF, RAAF, RNZAF, USAAC & the AVG Pilots made these reports, have written books, given interviews & they are out there for public consumption. :aok
I’ve read here that the Max IAS in level flight from Sea Level to 10,000’ is somewhere in the 290mph range, :confused: which is well below the 325mph to 350mph, all in IAS mind you, reported by Combat Pilots & they were able to achieve that between those Alt’s. It is my understanding that Aspirated, Fuel Injected, Turbo, Super & Turbo-Supercharged Recip A/C Perform better @ Sea Level to 10,000’ because Air/Fuel Ratio is @ its best because the air hasn’t thinned out enough yet to effect Performance.
Your flight models, for me, on 3/4's of the A/C I've flown, won’t go over 200mph IAS in the Practice Area of the game @ any Alt. I’ve lots of sim & real flight time, so this is rather puzzling to me. My “Wingman Force 3D” is set up properly also.:confused:
One of the main complaints from the FEAF B Pilots that had to quickly transition to the E model under Combat Conditions, was the difference in CG & Weight, making handling different, making for longer T/O’s runs & not being as responsive in the air "to them" compared to the B model & just the opposite for the E Pilots to the B model, in their P-o-V's. I only point this out as I read in the Forum that you use the same flight model for both B & E ‘s.
Cheers
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Hi,
noone say the P40 cant reach 350mph, but it didnt reach such speeds just in level flight and it for sure couldnt maintain 400mph, at least not for long!!
In a smooth dive the planes fast overcome their Vmax(level flight). From 13000ft and a initial speed of 200mph IAS i just reached 550mph in a dive and the P40 still was good manouverable.
In AH, vs the Zero, the P40 can disengage very well by diving away.
btw 600mph are already mach 0,78 at 20°C, i guess from 18000ft downward thats good possible in AH, but i was to lazy to climb that high.
The testdatas are mostly made with combatworthy planes, actually they was made to give datas to the pilots, would be bad to use special planes and to feed the own pilots with wrong datas, eh??
If you cant get above 200mph, you should stop to climb! ;)
Greetings,
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Originally posted by Col. Flashman
Thank'ee for responding.
I travelled to Air Shows quite a lot between the ages of 8 & 35, where I met & spoke w/ Test, Pursuit Ship & Fighter Pilots about the A/C they tested & actually flew in Combat during WW II. I’ve also an informative collection of Aviation material covering this era of flight & have had access to Original Spec Sheets/Books/Lit on the A/C I was rather interested in. :aok
I count several test pilots from Curtiss, Grumman, Republic and North American as friends. Some are now dead. I am also friends with some well known WWII fighter pilots (living and recently deceased) and keep a correspondence running with several others less well known. I also have a decent collection of AAF, USN and factory test data on hand, as well as an extensive personal library and over 15,000 photos digitally preserved from original prints or prints from original negatives.
I managed to get a ride by paying for 1/2 the fuel & got a tick of unofficial stick time in the Piggyback version of the P-40, as well as several other different Piggeyback Fighters in Private Owner/Operator hands. We were able to achieve well over 340mph IAS in the P-40 between Sea Level & 15,000’ w/ full fuel on board, there were exact weight fake 50s mounted in the wings & according to the Owner/Pilot, we were @ least 3/4 Combat Loaded during this flight & he really wrung the Olde Girl out for me, I had a slight green tinge when I climbed out afterwords. :aok
Many of us playing Aces High have flying experience, both military and civilian.
So what you are stating here is that what the Combat Pilots actual experiences under Varying Weather & Combat Conditions in regards to the Performance & Handling characteristics of the A/C they are flying w/ full, 3/4,1/2,1/4, Combat Loads, finding that the Indicated Air Speed, Climb Rate, Power Dive Ability, Turn Rate, etc., was better or worse or the same when measured against the Test Data stated in the Spec Sheets & from the Test Pilots sent by the Company that were on hand for the training flights, is of no consequence & useless to you. :confused:
What I am stating is that HTC will only use actual test data to model aircraft. They cannot and will not use anecdotal evidence, IE: combat pilot reports. These are unreliable for many reasons. There's plenty of test data taken at Eglin, Anacostia and Langley, etc, plus factory test data to establish what aircraft performance was when the aircraft were in service.
I’ve read here that the P-40 cannot Power Dive to save itself, so it can speed away @ tree-top-level from an opponent, to enable the Pilot can Climb back to Alt. to start all over again. :confused:
The P-40s as modeled in AH2 dive very well. Your perception is incorrect.
Which happens to be the one of the Main Combat Tactics taught to P-40 Pilots to keep from being shot down so that they can re-engage or arrive back to their Aerodrome safely. P-40 Pilots have reported 600mph IAS during Power Dives, which scared the Devil out of them not believing they'd be able to pull out of it & were able to maintain speeds over 400mph IAS @ tree-top-level before the climb back for Alt. FEAF, RAAF, RNZAF, USAAC & the AVG Pilots made these reports, have written books, given interviews & they are out there for public consumption. :aok
I believe that you mean 600 mph TAS, not IAS. 600 mph IAS at 8,000 feet translates into 696 mph true airspeed (nearly Mach 0.93)... Much faster than any WWII fighter could attain.
I have dive tested the AH2 P-40B and you can reach at least 605 mph TAS in a terminal velocity dive. Dive acceleration is what I expected, better than the A6M2, but inferior to the F6F or F4U.
I’ve read here that the Max IAS in level flight from Sea Level to 10,000’ is somewhere in the 290mph range, :confused: which is well below the 325mph to 350mph, all in IAS mind you, reported by Combat Pilots & they were able to achieve that between those Alt’s. It is my understanding that Aspirated, Fuel Injected, Turbo, Super & Turbo-Supercharged Recip A/C Perform better @ Sea Level to 10,000’ because Air/Fuel Ratio is @ its best because the air hasn’t thinned out enough yet to effect Performance.
Here's how the P-40E performs in AH2....
(http://www.hitechcreations.com/ahhelp/models/charts/p40espd.gif)
Your flight models, for me, on 3/4's of the A/C I've flown, won’t go over 200mph IAS in the Practice Area of the game @ any Alt. I’ve lots of sim & real flight time, so this is rather puzzling to me. My “Wingman Force 3D” is set up properly also.:confused:
Obviously you have issue with your throttle... I have no problem getting rated speed out of any fighter in the game. I've tested every fighter in the game at sea level, 10k, 20k, 25k and 30k. All perform to the posted charts, but low fuel fighters are always a bit faster (2-5 mph) as one would expect.
One of the main complaints from the FEAF B Pilots that had to quickly transition to the E model under Combat Conditions, was the difference in CG & Weight, making handling different, making for longer T/O’s runs & not being as responsive in the air "to them" compared to the B model & just the opposite for the E Pilots to the B model, in their P-o-V's. I only point this out as I read in the Forum that you use the same flight model for both B & E ‘s.
There are some issues with the P-40s, IMHO. First, our P-40B offers performance identical to the P-40C, with its added weight and drag (measured in-game at 338 mph TAS @ 16,000 feet, 25% fuel, zero fuel burn). That should be addressed, or at least the designation should be changed to P-40C and the drop tank option be added. Second, our P-40E has a War Emergency Power rating. No P-40E was so equipped (V-1710-39 did not have a WEP rating). So, it performs more like the P-40K-1, with the V-1710-73 engine. Also, both P-40s are able to lower full flaps at 171 mph IAS, when the pilot's manual states that 140 mph IAS was the max permitted for full flaps. Aside from these minor issues, I can find no significant fault in the flight behavior of either P-40.
Here's the chart for the AH2 P-40B... It is exactly the same for that which I have for the P-40C, but the P-40C is 400 lb heavier and has the added drag of the fuel tank shackles.
(http://www.hitechcreations.com/ahhelp/models/charts/p40bspd.gif)
In general, your perceptions of aircraft performance in Aces High is way off the mark. Swing by the Training Arena and we'll help you get your throttle properly calibrated. You'll see a huge improvement in aircraft performance.
My regards,
Widewing
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Flashman: (Harry flashman ?) :D
Of diving:
"Which happens to be the one of the Main Combat Tactics taught to P-40 Pilots to keep from being shot down so that they can re-engage or arrive back to their Aerodrome safely."
This worked against opponents from Japan mostly, - but not when you'd meet a 109 or a 190 for instance.....P40's were used quite a bit in the med where the opponents were mostly much faster than in the pacific.
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i think i remember reading that early on in North Africa, P-40s could dive away from the 109s.
not the 109F, though...
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Neville Duke commented on flying the P40 against the 109's where the 109's often gave them a bad day, - he got shot down a couple of times I belive.
Now I'm curious enough to start reading ;)
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The wartime P-40E could attain @360 mph TAS tops with a good engine at optimum alt, flying at full power "flat out" in level flight. I give it the extra 5-10mph to give it the benefit of a very well tuned engine, perhaps exceeding its rated manifold settings, and using 100/130 fuel. You would not have likely got that out of an operational bird in the Pacific, Africa, or Burma.
There isnt an ex P-40E pilot, living or dead, of any nation, that ever claimed it could attain anything faster than that, unless it was diving.
The fastest wartime P-40 (in squadron service) was the P-40N of 1944, which could do @380 mph TAS tops.
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Nice hijack. This WAS a P-47 thread. Or at least MOST of the 1st 4 pages were.
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The thread is from September 21st, and is over 200 replies, I hardly think its a "hijack". They all go OT at some point, and I think the conversations have been related in a generalized way, which is keeping with the spirit of the forum.
When we start yelling at each other over the War of 1812, and what the French did or didnt do at Waterloo, then thats a hijack.
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Originally posted by Squire
When we start yelling at each other over the War of 1812, and what the French did or didnt do at Waterloo, then thats a hijack.
Oooooh, so tempting...
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Originally posted by Angus
Neville Duke commented on flying the P40 against the 109's where the 109's often gave them a bad day, - he got shot down a couple of times I belive.
Now I'm curious enough to start reading ;)
squawking 7500 & i have Neville Duke's book, read it a couple years ago. Great read.
part of it was a P-38 thread too, but you can't really talk about improving a plane without comparing it to other planes & iirc was a part about getting your PP/AMEL/IA
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Originally posted by Angus
Flashman: (Harry flashman ?) :D
Of diving:
"Which happens to be the one of the Main Combat Tactics taught to P-40 Pilots to keep from being shot down so that they can re-engage or arrive back to their Aerodrome safely."
This worked against opponents from Japan mostly, - but not when you'd meet a 109 or a 190 for instance.....P40's were used quite a bit in the med where the opponents were mostly much faster than in the pacific.
Yes, one in the same. :aok
In the Med & N.A., the R.A.F. were still using the Lufbery Circle as their main Defensive Tactic against Bf-109's, so it's no wonder that they weren't having much success w/ the P-40, as they weren't taking advantages of her strengths & letting the 109's exploit her weaknesses.:( :furious :confused:
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Hi,
what was the strengths of rhe P40E over the 109F4??
Greetings,
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Originally posted by Knegel
Hi,
what was the strengths of rhe P40E over the 109F4??
Greetings,
I didn't state that the P-40E had strengths over the 109-F4. :confused:
I stated that the R.A.F. didn't use Tactics that Exploited the P-40E's strengths in combat, which allowed the 109-F4's to exploit the P-40E's weaknesses. :t
The Power Dive, the ability of the P-40E to take Punishment & her six 50's were three of her greatest strengths. The R.A.F. did not use Tactics that exploited them & they suffered for it @ the hands of the 109-F4's. :p
And as I recollect, 109's were not very good in a full on Power Dive untill late war models arrived w/o the stabilizer supports, as they'd start shedding parts off their Empennage or hit Compressibility & six 50's would completely shred a 109 in short order, even the 109-F4, though the 109 cannon's would shred an P-40E as well, but not as quickly, as the P-40E's had superior Armour compared to 109's.
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Originally posted by Knegel
Hi,
what was the strengths of rhe P40E over the 109F4??
Greetings,
better shark mouth paint job potential for the Curtis
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Originally posted by Col. Flashman
Yes, one in the same. :aok
In the Med & N.A., the R.A.F. were still using the Lufbery Circle as their main Defensive Tactic against Bf-109's, so it's no wonder that they weren't having much success w/ the P-40, as they weren't taking advantages of her strengths & letting the 109's exploit her weaknesses.:( :furious :confused:
nanananana. N-Africa didn't all happen in a month you know, and the Med was a conflict of some 5 years generally.
They ended up trying with almost anything in the book, and by the time things got intense down there, they had already learned from the Battle of Britain.
As for the 109F, it outperforms the P40's used at the time in almost any aspect. And was that a 6 x .50 cal P40?
I read somewhere that early on P40's had to be escorted by Hurricanes, and RAF pilots getting Spitfires after the P40's were absolutely delighted. Will try to dig some on this.
By the way, 109F does not have the stabilizer struts.
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"as the P-40E's had superior Armour compared to 109's"
I didn't know this. What armour was better in P-40 than in 109?
-C+
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Originally posted by Angus
nanananana. N-Africa didn't all happen in a month you know, and the Med was a conflict of some 5 years generally.
They ended up trying with almost anything in the book, and by the time things got intense down there, they had already learned from the Battle of Britain.
As for the 109F, it outperforms the P40's used at the time in almost any aspect. And was that a 6 x .50 cal P40?
I read somewhere that early on P40's had to be escorted by Hurricanes, and RAF pilots getting Spitfires after the P40's were absolutely delighted. Will try to dig some on this.
By the way, 109F does not have the stabilizer struts.
Commonwealth P-40s (Tomahawks and later Kittyhawks) were generally used as fighter-bombers and spent the bulk of their time well below 12,000 feet. In February of 1943, 239 Wing and 7 SAAF Wing were equipped exclusively with Kittyhawks. These two Wings attacked several Luftwaffe airfields at Gabes, which were defended by JG77, who where flying both 109Fs and the latest 109G-2s. 14 Kittyhawks were shot down for ten 109s lost in aerial combat. It should be noted that the Kittyhawks were up against some of the best German fighter pilots in North Africa, including Heinz Bar and Ernst Reinert, who claimed 9 between them. On this particular day, the Kittyhawks didn't have high cover.
It was generally standard practice to provide Kittyhawks with high cover by Spitfires. Any fighter would be at a major disadvantage when restricted to low altitude by tactical requirements, as were the Commonwealth Kittyhawks. Adding to this was the issue of the Kittyhawks being inferior to to 109s in virtually every respect other than minimum turn radius and roll rate. P-40s required superb teamwork to effectively deal with the Luftwaffe. I say effectively, which means barely holding their own.
P-40s served in the MTO well into 1944 with the USAAF. Overall, they did better than one would expect. Several pilots became aces flying the P-40 in 1944, despite it being completely outclassed. This reflects more on the quality of the opposition pilots and the excellent team tactics used by the AAF, than on their generally obsolete P-40s. P-40s provided the bulk of the air cover over Anzio for months. They proved effective at engaging German fighters and fighter-bombers (190s) and claimed kills exceeded losses by about 4 to 1. Anyone can check on USAAF P-40 combat ops by reviewing Carter and Mueller's AAF combat chronology available in .pdf form here. (http://www.airforcehistory.hq.af.mil/Publications/fulltext/wwii_combat_chronology.pdf)
My regards,
Widewing
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The AVG "Flying Tiger" tactics you speak of were only effective against the Japanese, flying slower a/c that could not dive as fast, like the Ki-43 and the Ki-27.
The leading P-40 aces in North Africa were the following (just P-40 kills):
CR Caldwell, RAAF, 20 kills on P-40s. Australian.
B Drake, RAF, 13 kills on P-40s. British.
JF Edwards, RCAF, 12 kills on P-40s. Canadian.
AW Barr, RAAF, 11 kills on P-40s. Australian.
RH Gibbes, RAF, 10 kills on P-40s. British.
The RAF went into action in N. Africa in April 1941, a year and a half before the USAAF landed a/c in November 1942.
Leading USAAF P-40 aces in the MED (just P-40 kills):
Levi Chase, 10 kills, 60th FS
William Moymer, 8 kills, 33rd FG HQ
Roy Whittaker, 7 kills, 65th FS
Ralph Taylor, 6 kills, 317th FS
Robert Baseler, 5 kills, 325 fg HQ
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Interesting doc. A-26's of the 7th AF in the pacific went against Japan in July 45.
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Hi Squire,
>The leading P-40 aces in North Africa were the following (just P-40 kills):
Interesting list :-) Considering the odds these pilots were fighting against, their kill numbers represent quite an achievement!
For comparison, here are the leading P-40 killers (ETO/MTO/North Africa, just P-40 kills):
Hans-Joachim Marseille: 101
Werner Schroer: 40
Heinz Bär: 36
Gustav-Siegfried Rödel: 28
Ernst-Wilhelm Reinert: 28
Hans-Arnold Stahlschmidt: 27
Otto Schulz: 26
Friedrich Körner: 24
Karl-Heinz Bendert: 22
Gerhard Homuth: 22
Günter Steinhausen: 19
Joachim Müncheberg: 18
Karl von Lieres u. Wilkau: 14
Jürgen Harder: 13
Willy Kientsch: 13
Heinz-Edgar Berres: 13
Anton Hackl: 12
Ludwig Franzisket: 12
Horst Reuter: 11
Rudolf Sinner: 11
Siegfried Freytag: 10
(I compiled this list from Tony Wood's Luftwaffe Claims List, West Front.)
Of course, one should be careful not to put too much significance into such lists.
Technically, the Me 109 certainly was superior in most respects, but they operated under quite different tactical circumstances than the P-40s, so kill numbers are an asymmetric affair in any case, even when you're just looking at the most successful pilots in both aircraft.
There were two interesting statements by P-40 pilots that highlighted their difficult situation: One pilot said (not verbatim) "our only chance lay in keeping a sharp lookout and relying on mutual support to keep the Messerschmitts off our backs". Another, asked whether the Me 109F was superior to the P-40, answered (again, not verbatim): "Hell, even the Me 109E would have been superior!" He qualified this statement with a description of the climb rate superiority of the Me 109, which meant that in most engagement the P-40 found itself in a defensive role and unable to move aggressively.
Given the chance, there is no doubt that the P-40 could be quite effective even with its dedicated low-altitude engine and its weight handicap. (The P-40F with a Merlin engine was a bit better at altitude, but its Packard-Merlin was not as powerful an engine as the contemporary Spitfire IX's. Compared to the Spitfire V, though, the P-40F had the advantage of a two-speed supercharger.)
Regards,
Henning (HoHun)
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It's been documented that Luftwaffa Pilot claims have puzzled their Crew Chief's @ times, because during the Rearming after missions no Ammo expediture has been found & Kills have been claimed.
Now either there's something a-miss there or they Flew the kills into the ground or some other object in order to be able to make these claims.
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Hi Flashman,
>It's been documented that Luftwaffa Pilot claims have puzzled their Crew Chief's @ times, because during the Rearming after missions no Ammo expediture has been found & Kills have been claimed.
Let me guess: You've been reading Martin Caidin's book on the Me 109 :-)
Combat claims of course have to be read with care, but that's true for all air forces involved in the war. At least, we're comparing oranges and oranges - though we're actually talking about apples.
Regards,
Henning (HoHun)
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Oh, there is no doubt the Bf109F was by far the more dangerous fighter, I doubt any of the P-40 pilots would have disputed that. Of course you must judge all the aces on their accomplishments based on the circumstances in which they found themselves. There were great talents from all the combatants in the North African fighting, both allied and axis.
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Hi Squire,
>Oh, there is no doubt the Bf109F was by far the more dangerous fighter, I doubt any of the P-40 pilots would have disputed that. Of course you must judge all the aces on their accomplishments based on the circumstances in which they found themselves. There were great talents from all the combatants in the North African fighting, both allied and axis.
I absolutely agree! One might even argue that it was the greater accomplishment to devise tactics of mutual support in order to be able to complete one's missions in the face of the enemy's technical superiority than just lone-wolfing it in a better aircraft.
Tactical thinkers like Mölders, Pokrishkin or Broadhurst might have been more influential than aces like Marseille. I'm currently not aware of who was the most important Allied fighter leader in North Africa, but I'm sure they had some good leadership, too :-)
Regards,
Henning (HoHun)
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I'm currently reading a book (http://www.amazon.co.uk/exec/obidos/ASIN/0811731243/203-6626400-0703923) called "Flying American Combat Aircraft of WWII" edited by Robin Higham. It's a large collection of pilot's stories on those aircraft. The interesting part regarding this thread is a chapter written by Mark E. Bradley, who was involved with the developement of the P-47 right from the XP-47B (he was in the developement of the P-43 before that). He became Chief of Flight test after Kelsey and even flew combat missions with the P-47 in ETO and flew also the P-47N in the PTO while he was in the 5th AF.
Bradley was also deeply involved on range extension programs of the US fighters and actually the fuselage tank of the P-51 is sometimes called "Colonel Bradley's Tank" due to his input to this program. So here is what he says about the P-47:
"It is enough to say here that though the P-51 was allready equipped with wing tanks, we were able to bring about a further increase in it's droppable fuel capacity and resultant range by placing an additional ninety-gallon tank behind the pilot's seat. We had no such luck with the P-47.
There was no place to put more fuel in the P-47 except in droppable wing tanks. Earlier, Republic had developed what was called a "slipper tank", usable for ferrying only. Because it made the airplane unstable, it was not suitable for combat. In the end we used same pylon and tank arrangement utilized on the P-38. The first such installation was made, not at the factory and not at Wright Field, but in Africaby Col. Claire Bunch, an enterprising officer working for Jimmy Doolittle."
The book itself is very interesting read, there are practically all main types and several lesser known, but important types like the P-26, O-47, Vultee BT-13, C-54, CG-4A...
gripen
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Originally posted by AquaShrimp
Basically anything to save weight would have been my goal. Increasing internal fuel supply, and having stations for drop-tanks would be a necessity too.
From the If you could talk to a WWII Fighter Pilot (http://www.flyaceshigh.com/forums/showthread.php?s=&threadid=191240&perpage=40&pagenumber=1) Thread:
Excerpt From Widewing's Interview With Robert Johnson
RSJ: Well, the enemy would stall first because the Jug's mass allowed to retain its, er...
CCJ: Energy?
RSJ: Yes, energy. The P-47's mass allowed it to retain its energy better and it stalled a few seconds after the enemy plane. The German would snap over and head down. Except, now I was right behind him and there was no getting away.
CCJ: Wouldn't he still be directly behind you?
RSJ: No. Pulling up so suddenly always caught them by surprise. The second or two that it took for them to react took care of that.
CCJ: Why did you roll?
RSJ: Because that killed my speed faster than the enemy if he didn't, which gained me the advantage of being to his rear as he zoomed up. If he rolled too, that also worked to my advantage because it killed his speed faster than mine.
As you can see the JUG's Weight was one of its strength's
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Originally posted by mussie
As you can see the JUG's Weight was one of its strength's
It always depends to the situation and pilotskill if weight is a advantage or a disadvantage.
Disadvantages of more weight:
Smaler range.
Smaler horizontal acceleration.
Smaler steady climb.
More bad sustained horizontal turn.
Slower deceleration.
Higher stallspeed.
More sideslip.
Higher structural forces(specialy while turning).
Advantages of more weight:
Better downward acceleration at medium to highspeed.
Smaler E-bleed at highspeed.
Less weight include many more advantages, but a good pilot of course can use the very important advantages of more weight(more inertia and more downward thrust) to his advantage.
btw, in the case of your example, RSJ seems to mix up some things. He claim that the P47 retain its energy better and stall some sec later. Thats maybe ok, cause the big inertia and relative high liftload and span load, but this implement that it also slow down less fast, and this slower deceleration is the reason for the later stall.
But then he goes on that he did roll to kill the speed faster than the enemy to get onto his tail. Thats also ok, but not in the same contex, cause if he slow faster down, he also will stall faster, specialy in a roll with its related problems.
And then its of course a advantage to be behind the enemy, but would he have been able to follow a upzoom, if he was more slow??
This extreme downslowing bring the P47 into bad trouble, cause it lose its inertia and since the climb of the P47 isnt that good at all, he would be in trouble(of course above 6500m alt the P47 own the sky anyway).
And then he say that if the enemy also slow down to stay behind the Jug, its also a advantage for him, but wouldnt this be the same situation like if he slow down to get behind the enemy??
If the Jug was able to follow the upzoom(or looping) of the faster oponent in front and to use the situation of a same fast enemy on his tail as advantage, the thrust, not the weight was the cause.
The only moment when i would wish to have a more heavy plane is when i need to disengage in a dive(actually in real life it was the most wanted advantage to be able to disengage). In all other situations weight isnt a real help, though it also isnt always a disadvantage(specialy not while combat at highspeed).
Greetings,
Knegel
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you forgot to add on the pro side for high weight: higher Va
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Hi,
Afaik there are different definations of the Va(manouvering speed).
1. maximum speed [at a particular weight] at which full deflection of the controls can be made without exceeding the design limit load factor and damaging the airplane’s primary structure” and Va is the maximum recommended speed for turbulent air penetration.
2. Va is the speed below which our aircraft will stall rather than bend or break.
Regarding 1. the weight is not direct related, rather the construction. Weight can be a indicator for a rough construction, but weight also stress the construction.
Regarding 2. a faster Va of course is a advantage, same like a higher stallspeed in general, but also this dont have to do with weight, rather with liftload and spanload etc.
What i forgot is the Vmax(dive), if the construction allow high mach numbers(in case of the P38 this dont seems to be always the case, so the high weight dont help here).
Greetings,
Knegel
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A 500 mph IAS Vne has to be reassuring.
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Originally posted by Knegel
Hi,
Afaik there are different definations of the Va(manouvering speed).
1. maximum speed [at a particular weight] at which full deflection of the controls can be made without exceeding the design limit load factor and damaging the airplane’s primary structure” and Va is the maximum recommended speed for turbulent air penetration.
2. Va is the speed below which our aircraft will stall rather than bend or break.
Regarding 1. the weight is not direct related, rather the construction. Weight can be a indicator for a rough construction, but weight also stress the construction.
Regarding 2. a faster Va of course is a advantage, same like a higher stallspeed in general, but also this dont have to do with weight, rather with liftload and spanload etc.
What i forgot is the Vmax(dive), if the construction allow high mach numbers(in case of the P38 this dont seems to be always the case, so the high weight dont help here).
Greetings,
Knegel
Just saw that i wrote advantage, where i was up to write disadvantage!
"Regarding 2. a faster Va of course is a disadvantage.............."
Stoney,
Vne of 500mph at what altitude??
Greetings,
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I've never seen a plane where the V speeds were given for specified altitudes, just always in IAS.
there is a pretty good reason for this...
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Hi,
planes that operate above 12000ft and above 250knots normaly get a list of IAS speeds, related to the altitude, simply cause the mach related problems, not the normal airflow turn to be the main problem regarding the Vne limit.
Though this problem get minimized a bit, cause the IAS measurement start to overrate, also cause mach related problems with the pitot tube. Therefor the planes might not fly as fast as the IAS indicate, but still the Vne IAS depents to the altitude.
I already saw some of this charts for WWII planes posted here on the board.
Normal modern Spotplanes and gliders only show 1 Vne IAS.
Greetings,
Knegel
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the good reason i mentioned, i've never flown anything faster than a bonanza or been over 11,500';) ;) :eek: