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Author Topic: P51-D vs F4U-4 & P38-L  (Read 4535 times)
alskahawk
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« Reply #30 on: March 05, 2009, 04:22:20 PM »

Wrong. The P-51 did not outclimb the P-38, ask the guys who flew both, Stan Richardson and Art Heiden will both tell you that the P-51 could not out climb a P-38, and they flew the real thing, in the skies over Europe, fighting for their lives. Nor did it out accelerate the P-38. Only at certain speeds and certain altitudes, and not many of them, either, did the P-51 out accelerate the P-38. You can talk mass all you want, but you're ignoring an important factor, HORSEPOWER.


 P 38L climb rate 20k in 7 min American Warplanes of WW2
 P 51 climb rate 3475f/m (American Warplanes of WW2)
 Checked various sites on the web specs varied widely depending on the site.

 P38L wt; 17,500Lbs
 P 51D 9200Lbs
 Horsepower
P38L 2 x 1425Hp (production engine)
P51 1590HP

 Probably the best example is in Osprey book P38 Lightning Aces of the Pacific and CBI. By John Stanaway. Page 45 tells of a mock combat between Capt. Joe Forster(P38) and a P51 pilot. "When the two fighters eventually flew combat against each other from an equal start at altitude, the superb Mustang easily prevailed,..."

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Captain Virgil Hilts
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« Reply #31 on: March 05, 2009, 06:21:30 PM »


 P 38L climb rate 20k in 7 min American Warplanes of WW2
 P 51 climb rate 3475f/m (American Warplanes of WW2)
 Checked various sites on the web specs varied widely depending on the site.

 P38L wt; 17,500Lbs
 P 51D 9200Lbs
 Horsepower
P38L 2 x 1425Hp (production engine)
P51 1590HP

 Probably the best example is in Osprey book P38 Lightning Aces of the Pacific and CBI. By John Stanaway. Page 45 tells of a mock combat between Capt. Joe Forster(P38) and a P51 pilot. "When the two fighters eventually flew combat against each other from an equal start at altitude, the superb Mustang easily prevailed,..."



Wrong again. Like I said, Captain Stan Richardson Jr. and Captain Art Heiden flew both planes, in combat. I know both of them, and corresponded with them directly, so did Widewing. Both said that the P-38 consistently climbed better than the P-51.  We're talking about TWO pilots who flew BOTH planes, in the same time period, in combat.

The P-38L does not weigh 17,500 pounds, it is closer to 16,000. And the -30 Allison in the P-38L makes 1725HP, not 1450HP.

No, the best books on the subject of the P-38, especially for technical data, are "The Lockheed P-38 Lightning" by Warren Bodie, and "America's Hundred Thousand". For the P-38J, with less powerful engines than the P-38L, the rate of climb at sea level was 4000 FPM, the rate of climb at 23,400 feet was 2900FPM, and the time from take off to 23,400 feet was 6 minutes and 12 seconds. The P-38J engines at 1612HP had 112HP less than the P-38L engines. Take off weight was 16,597 pounds, over 900 pounds lighter than your incorrect numbers, but actually heavier than actual operating numbers.


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Widewing
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« Reply #32 on: March 05, 2009, 06:56:30 PM »


 P 38L climb rate 20k in 7 min American Warplanes of WW2
 P 51 climb rate 3475f/m (American Warplanes of WW2)
 Checked various sites on the web specs varied widely depending on the site.

 P38L wt; 17,500Lbs
 P 51D 9200Lbs
 Horsepower
P38L 2 x 1425Hp (production engine)
P51 1590HP

 Probably the best example is in Osprey book P38 Lightning Aces of the Pacific and CBI. By John Stanaway. Page 45 tells of a mock combat between Capt. Joe Forster(P38) and a P51 pilot. "When the two fighters eventually flew combat against each other from an equal start at altitude, the superb Mustang easily prevailed,..."

You're not getting it...

When 8th AF fighter squadrons transitioned from P-38s to P-51s, the first thing they discovered during a combat mission was the P-51 was still climbing as they crossed the enemy coast. When flying the P-38s, as they crossed the enemy coast, they were already at altitude and settled into cruise.

Many pilots in P-38 groups did not view the P-51 as a step up. Those who had mastered the complex P-38 generally preferred the Lightning. Those who were uncomfortable in the P-38 were happy to get the more simple P-51. It was easier for low-time fighter pilots to fly. However, in the Pacific, P-38 groups nearly mutinied when told that they may have to switch to P-51s. General Kenney preferred the P-38 and refused to transition veteran P-38 Groups into the Mustang. P-51s in the 5th AF came with new units.

A P-38J outclimbs a P-51D by just over 15%.

Acceleration is a function of several factors.

Initial acceleration is calculated as Thrust-drag/mass. Run this for the P-38L and P-51D and the P-38L wins. With twice the available thrust, the P-38L was a powerful fighter.


My regards,

Widewing
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My regards,

Widewing
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Widewing
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« Reply #33 on: March 05, 2009, 07:20:39 PM »


 Probably the best example is in Osprey book P38 Lightning Aces of the Pacific and CBI. By John Stanaway. Page 45 tells of a mock combat between Capt. Joe Forster(P38) and a P51 pilot. "When the two fighters eventually flew combat against each other from an equal start at altitude, the superb Mustang easily prevailed,..."


Nice editing... How about quoting the entire story, rather than your hacked up version? I know why, because it shows that your assertions have been incorrect. Selective quoting, eh?

Here's a scan of that portion of the page in Stanaway's book.





My regards,

Widewing

« Last Edit: March 05, 2009, 07:22:39 PM by Widewing » Logged

My regards,

Widewing
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Yeager
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« Reply #34 on: March 05, 2009, 07:57:16 PM »

I know the record of the 38 in the Pacific theater.  Bong and McGuire obviously having such outstanding success in it against Japanese machines......but what was the reason the P38 units did not enjoy equivalent success as the the P47 and P51 units did in Med/Europe theater?  Is this even a true statement?  Was the P38 the ultimate US combat aircraft of WW2?
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Ack-Ack
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« Reply #35 on: March 05, 2009, 08:12:46 PM »

I know the record of the 38 in the Pacific theater.  Bong and McGuire obviously having such outstanding success in it against Japanese machines......but what was the reason the P38 units did not enjoy equivalent success as the the P47 and P51 units did in Med/Europe theater?  Is this even a true statement?  Was the P38 the ultimate US combat aircraft of WW2?

A lot of people point fingers at some of the mechanical 'teething' problems the Lightning face (heating problems, insufficient crew training on 2 engine aircraft, oil pump problems) as the main reason but in my opinion it had more to do with the political bickering, attitude and bias of the 8th High Command.  Other AF units that flew the Lightning up until wars end in the ETO/MTO area thought very highly of their plane and were successful in the same mission types the Lightings flew in the 8th before being withdrawn.

Was the P-38 a failure in the ETO?  Only with the 8th AAF and again, it was due (in my opinion) to the High Command than the plane.


ack-ack
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Bronk
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« Reply #36 on: March 05, 2009, 08:38:04 PM »


Pffft If the turbo had been retained in the 39. We wouldn't even have this discussion of whats better. Wink Big Grin
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alskahawk
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« Reply #37 on: March 05, 2009, 09:24:08 PM »

Nice editing... How about quoting the entire story, rather than your hacked up version? I know why, because it shows that your assertions have been incorrect. Selective quoting, eh?

Here's a scan of that portion of the page in Stanaway's book.

<Quoted Image Removed>



My regards,

Widewing

 
And what was the end line? Just what I quoted; which is also my initial comment. Co-alt equal E.  No creative editing. No skulduggery. No hacking.

How many duels start on the taxi way?

 What was my original comment? "Actually in real life the p51 had a much better climb rate, and accelleration rate than the P-38. As did most single engine fighters verse the P-38. A function of mass.  In AH the difference is barely noticible or non-existant. Co-alt, equal energy states the P38 will outturn the P51. The P51s advantages are to out dive and return with a higher energy state.

 ('Much better rate of climb." Much better"  overstatement. I should have typed better rate of climb)

You think you can win in a P51 coalt-equal E against a P38. and turnfight? In AH?  Co-Alt the 51s advantages are to extend and return with a higher energy state. (also it has a better roll rate) I want to be in the 38. I think Steve got my point; the P51 finishes third.

 As per other assertions of pilots prefering to stay with thier P38s rather than changing to a new aircraft. There were also pilots in the Pacific that prefered the P38J vs P38L. Pilot preference is not always about perfomance.

 
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Captain Virgil Hilts
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« Reply #38 on: March 05, 2009, 09:44:57 PM »

Keep repeating yourself. It helps. Well, it helps show how completely misled you are, anyway. You bring nothing to prove the P-51 out climbs the P-38. The P-38 has better power loading as well as a wing designed for more lift. The P-51 doesn't have a better rate of climb, never mind a much better rate of climb. The P-38 is superior in climb, and superior in acceleration at most speeds and most altitudes.

In case you have a difficulty with math, the figures I posted for the P-38J show an average climb rate from sea level to 23,400 feet of about 3700 FPM, which covers your post of the P-51D being good for about 3400 FPM by about 300 FPM.
« Last Edit: March 05, 2009, 10:21:56 PM by Captain Virgil Hilts » Logged

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SaVaGe

Captain Virgil Hilts
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« Reply #39 on: March 05, 2009, 09:54:25 PM »

Oh, and while we're at it, Widewing's years as a published author on the subject of World War II aircraft trumps what little you have brought to the discussion. He's got more valid and accepted sources in one shirt pocket than you have in your entire house.
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juice
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« Reply #40 on: March 05, 2009, 11:21:49 PM »

i am a F4U-1A lover. what about a match up between it & the 38L? i know the 38L can out climb & accelerate the -1A but doesn't the -1A own the 38L in every other category? i believe the -1A can consistently kick the 38L's but if the pilots are equal. i would like to hear from any & all but especially from ack ack & widewing.
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Saxman
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« Reply #41 on: March 05, 2009, 11:42:23 PM »

i believe the -1A can consistently kick the 38L's but if the pilots are equal. i would like to hear from any & all but especially from ack ack & widewing.

I like this guy. Big Grin

Seriously tho:

F4U-1A is faster up until 25k. It's close, with WEP being more pronounced.

P-38L will out-climb and out-accelerate. Rate of roll at high speeds is also better. Otherwise the F4U has the edge in rudder and elevator authority at high speeds. E retention could go either way. I've lost and caught P-38s in the Zoom with the 1A, depending on E-state.

F4U generally has the advantage once the flaps come out if the fight is level or nose-down, especially due to the Hog's superior elevator response at higher speeds.

If the 38L can keep the fight SUSTAINED nose-high he should be able to take control. However underestimate the 1A's zoom potential and you got a dead Lightning.
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Bodhi
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« Reply #42 on: March 06, 2009, 12:15:48 AM »

You may find it interesting that I have been conversing with author Robert Dorr about the F4U-4. He is also a Technical Editor for Air Power History magazine. This is the official publication of the Air Force Historical Foundation. The magazine recently published at article titled "The P-51 Mustang: The Most Important Aircraft in History?" Bob wrote, "The current Air Power History (where I am technical editor) has an article asserting that the P-51 Mustang is not merely the best fighter of the war but the greatest airplane of all time. A popular text making the rounds on the Internet claims that the F4U-4 Corsair was really the best fighter of the war; we would like to publish this in APH but cannot identify the originator."

Guess who wrote that F4U-4 piece 11 years ago? Uh huh, yours truly. Can someone say justice prevails?

I wrote to Bob and explained in detail why the F4U-4 was simply the finest fighter to see combat in WWII. I quoted a story I got from a retired USAF Brig.General. In 1941, he joined the RCAF and was trained on Hurricanes. He flew Spitfires in Britain and eventually transferred to the USAAF. He flew P-51s in the ETO. Post war, he stayed in the Air Force Reserve. Sometime prior to the Korean war, he encountered a Navy F4U-4B while flying a P-51D. The two pilots engaged in some determined mock combat. His description of the fight was simple and directly to the point. "My Mustang had nothing for that Corsair. I could not prevent it from getting on my tail and then could do nothing to shake it off."

I offered to polish up that old piece and include actual Navy test data. I also mentioned that one of our Aces High guys had recently finished the restoration of an F4U-4... I directed him to a copy of the F4U-4's detail specification. I doubt that he had any idea that these resources were out there.

It looks like I may be writing the P-51 rebuttal piece... Should be fun, and will generate some heat. It will also generate lots of light too. In August of 1945 the top three performing fighters in the US inventory were all painted blue. F8F-1, F7F-3, and the F4U-4.

My regards,

Widewing

Widewing,

if I can be of service, I'll gladly help.  Especially since our neighbors finished the most accurate Mustang to ever grace the skies since WW2.

Please advise as to what you need.  <S>
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Bodhi
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« Reply #43 on: March 06, 2009, 12:21:21 AM »

If you consider the power the P-38 had available, you'd have to figure that the props it had just weren't getting the job done. The chin mounted intercoolers just do not add enough drag to absorb all of the HP they allowed the Allisons to produce, after all, the H model and earlier didn't have them, and they were considerably slower that the later models, especially the L model running at full Lockheed/Allison rated boost and RPM (a difference of between 15 and 30 MPH, depending on models compared, and as much as 300HP per engine). Another thing to consider is that a turbocharger loves a load, and the more efficient the prop, the more it loads the engine, since it loses less to slippage.

The performance difference between the K model mule, with ill fitting cowl panels and all, and the J and L models is considerable, not just top speed, but especially climb rate and range (top speed increase wasn't worth a lot at altitude to the P-38, since above 25K you could get it to compress at or before 465MPH), as well as acceleration. The K model didn't have a lot more power (as compared to the J and L models), but evidently those Hamilton Standard Paddle props are a lot more efficient than the Curtiss Electric props are (as well as a lot more reliable according to the pilots). According to Bodie, the K model mule was actually a well worn and abused G model that had the chin intercoolers grafted on and the gear box cowls crudely fitted as well. The gear boxes were bigger and taller, and raised the centerline of the props several inches, so the cowls that covered them had to be quickly cobbled up by hand, they supposedly didn't really fit the prop hubs and spinners or the rest of the plane either, and the same could be said of the intercooler installation. Since there were only one or two (only one K mule was ever photographed, and there are only a couple of pictures of it) were ever built and it/they were built by hand, there's no way to tell how much the poor fit hurt the aerodynamics, but they felt it was enough to make a measurable difference.

I'm pretty sure the Merlin itself weighs a good bit more, the Allison was fairly light for it's size and displacement, Allison was originally a pure racing engine company from what I've read, and the V-1710 was first designed for the Navy to be used in lighter than air craft. I think the weight gain was fairly considerable. I'd have to drag out the book, (I don't know where it is right now, we're remodeling) but I seem to remember the total weight gain for the plane was around 1000 pounds (about 500 pounds per side I guess), despite losing most of the extensive exhaust system, the turbocharger, the intercooler, and the plumbing, which I agree is strange. Best I can remember, they anticipated little gain in speed, and an actual reduction in rate of climb, and possibly range. The desire was actually to reduce cost and complexity.

I don't know that the Merlin can be reassembled to run counter-clockwise the way the Allison can (the Allison was actually designed originally so that it could be shut down and re started running in the opposite direction), that would also cause problems, as one side would have to have a gear box with an extra gear or idler gear to make the props run in opposite directions (or the engine reversed in some other manner). Those helical cut gears in gear boxes don't like running the other way, and they usually don't like having gears added in to reverse them. That's why we use straight spur cut gears in high HP applications, but they bring in their own problems, and I can see where props might not like straight cut gears (harmonics and backlash).

The Merlin, unless tuned so that it gives up power below 22-25K feet, would give up power compared to the turbocharged Allison above 26K feet, further reducing speed and climb above that altitude. The only thing holding the Allison back from performing at altitude without the turbocharger was the crank driven supercharger. Given an equal amount of boost in stock form, the Allison actually makes more power (we tested that fooling with pulling tractors). If you put a crank driven supercharger on an Allison that made the same boost as a Merlin had, the Allison would make more power. Of course, the advantage of the supercharger on the Merlin series is it could be tuned for particular altitudes, the way it was in the Spitfires (there were high and low altitude specific versions of the Spitfire). So you can move the critical altitude to suit your purpose or mission.

But it is really hard to beat a turbocharger for great performance at a wide range of altitudes. In those days, turbocharging still had a ways to go, but even then it held some pretty significant advantages.

A late P-38 with the Hamilton Standard paddle props would have been far easier to produce and offered a lot more than a Merlin conversion. Removing the Curtiss Electric props would have removed a great deal of electrical load (the electrical system was almost overloaded if everything worked properly, and if the props acted up the generators were toast) and solved reliability issues. It would have also increased performance significantly by all measures, top speed, rate of climb, acceleration, and range. It would have required far less work with regards to changes. The gear boxes would fit the plane, props, and engines, all that was really required was a new set of dies to properly form the spinners, shrouds, and cowls. I'd be willing to bet it would have been a lot easier to get more Hamilton Standard paddle props than it would have been to get that many more Merlins. It would likely have been cheaper as well, since Packard was paying a license fee to Rolls Royce to build Merlins.

Holy wall of text Virgil! 

I'll have to look into this for an educated reply, but I am going to guess and say that the decrease in weight and streamlining for a Merlin vs. an Allison is gonna be huge let alone add the extra horsepower...
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Bodhi
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« Reply #44 on: March 06, 2009, 12:28:44 AM »

The propeller in that picture is the Hamilton Standard High Activity paddle prop, so the change in hub diameter would be different, since the Hamilton Standard is hydrostatic and not electric like the Curtiss Electric prop. There isn't a lot of room there for the hub and spinner to get bigger without the cowl covering the gear box and joining to the fuselage getting almost as big as the fuselage, but there is room. A four blade Curtiss would have been close to useless as far as gains go, because the three blade was so terribly inefficient. The spinner covering a Curtiss prop hub is full, I noticed that when I was talking to Steve and Bob one day up at Middlesboro. But I don't think the spinner covering a Hamilton Standard prop hub is quite as full. The easy thing to do is to compare the spinner covering a Hamilton Standard 4 blade P-51 prop to the one covering the Curtiss on a P-38. I don't have a reference photo handy. I know Widewing did some scale comparisons for the article you got that photo from. Maybe he has done others that he has not published, or maybe he has photos he can use to do a quick and rough comparison. Or maybe Bodhi has access to the parts, photos, or drawings.

I stand corrected, by the way, I remembered the P-38K mule as being a heavily reworked G model, and it was actually an E model that had seen even more use, abuse, and modification.

Virgil,

The spinner size does not dictate the size of the hub.  It only dictates conformity to airflow.  Both the '38 and ' 51 are perfect examples of it.  Decrease of hub size would only dictate a smaller hub and NOT smaller spinner.  A larger hub would dictate a larger spinner as size required.

Note the shaft of the Curtiss Electric Blades and the addition of the paddle on the Mustang and Thundebolt Curtiss cuffed blades.
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