Improve the P-47

[AquaShrimp]

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.

[Bodhi]

In doing so you also would have neutered the best jabo the US had in it's inventory...

[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.

[HoHun]

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)

[Squire]

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.

[CptA]

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

[HoHun]

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)

[HoHun]

Hi Cpta,

Very good points! :-) Thanks for your post!

Regards,

Henning (HoHun)

[AquaShrimp]

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.

[Overlag]

you described a P51 there......

[Debonair]

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

[Squire]

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.

[AquaShrimp]

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.

[Bodhi]

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.

[bkbandit]

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.