Bf-109 vs P-40

P-40 vs Bf 109

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You know, I was trying and trying to find the book where the designer of the P-40D stated that the chin was a big problem for level flight speed directional stability, but I cant find it. Go figure. Anyways, just wanted to point out that even he thought that was the problem. So they came up with the XP-40K-CU-15, the forerunner to the P-40Q. I also read somewhere that North American 'borrowed' Curtiss's data on that ship (before it was built), and hence the P-51 was born.
 
Us Procurement was also done in stages, at least at times. The USAAC would issue a "requirement" to which a number of manufactures would respond with paper proposals. The USAAC would evaluate these proposals and pick one or more (or none) to be developed further. After a bit of negotiations a contract would be written covering the construction of one or more prototypes and it is here that performance guarantees start to show up. If the plane does not reach it's performance guarantees the Army does not have to pay full price for the plane. You could think of the first part as a "wish list" and after the manufacturers come up with their proposals of how close they can come the Army starts to get real settles for what is achievable in the next few years.
The USAAC was to put it mildly, very frugal in the 1930s. Like with engine development. If they contracted for a test engine to develop XXX horse power an under test it did not make it, the Army could refuse to pay for the engine. If the engine broke on the test stand before the completion of the test it was up to the manufacturer to repair it and test it again in order to complete the contract.

If the Allison was "pet" of the USAAC they had a funny way of showing it. In the Spring of 1939 the USAAC was over $900,000 behind in payments to Allison for work already done. They got out of paying it by swapping the debt for permission to export the V-1710 to France and England. I don't want to think of what they did to companies that were not "pets"

Other countries had a number of requirements, sometimes general requirements were put out in a booklet or paper that covered ALL aircraft. Things like "G" loading's for various types of aircraft, perhaps ground pressure of tires, materials or fittings standards. This way when issuing a fighter (or pursuit) or bomber "requirement" it would focus on the performance desired and all the little details (or not so little) would be covered by saying "refer to requirements booklet XXX for all other specifications".

One book on the Bf 109 gives a German tactical requirement for fighters dated 6/7/1933.

Armament is listed as is a maximum speed (400kph at 6000meters), Range/endurance, Climb to altitude, ceiling, and airfield size (400 meters X 400 meters) along with some other considerations.

It seems that it is some of these "details" that decisions were made that seriously affected some aircraft's performance as time went on.
 

It still doesn't stand up. The XP-40K with the cooling modifications doesn't show up until about 2 years after the the Prototype P-51 is rolled out the door. Granted you did say before the the XP-40K was built, but that is an awful long time to be sitting on that kind of information. It has also been said that the XP-46 used the same type of radiator that the P-51 did but Curtiss sure didn't seem to get the performance out of it. And as I keep pointing out, Curtiss didn't use that style of radiator on any of the liquid cooled P-60 aircraft.
Curtiss had been the #1 supplier of fighters to the US Army for a good part of the time between the wars, It seems hard to believe they wouldn't use every trick they knew to try to regain that position. Instead they churned out a succession of duds while giving away speed secrets to their competitors?
 
So it would seem. Curtiss also was working on a turbo/supercharged version called the XP-40J. IIRC with simular lines to the XP-40K-CU-15. I think that the USAAF had a bromance with the P-38, which effectively killed the P-40. But the USAAF had contractual obligations to Curtiss so kept the P-40 w/o major improvements. I mean after all, dosn't all relevant data go to the USAAF for evaluation? This is just a theory of mine.

found it:

source (about speed stability) pg.23 of Curtiss_P-40_in_action. Don Berlin was the guys name.
 
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Only if there is a contract to do so. There is a lot of proprietary information held by manufacturer and even if the government wants the information in interest of national security, it is sold to the government.
 

There already was a P-40 with a turbocharger. It was called the P-37. There was an XP-37 and 13 YP-37s. The First YP-37 flew in Jan of 1939 and was delivered to the army in March.

The USAAF had NO long term contractual obligations to Curtiss. For example the last batch of 1000 (P-40N-40) was ordered on June 30 1944. It was later cut back to 220 aircraft. The Previous order for 1000 planes (500 P-40N-30s and 500 P-40N-35s) was placed on Feb 14 1944. If Curtiss could demonstrate (or even show detailed proposals) for improved P-40s existing contracts could be amended or new contracts placed.

The P-40 was initially ordered and kept in production, not because it was the best but because it was available and once in large scale production ( at it's best, Curtiss could build over 400 fighters per month) the numbers of fighters lost to retooling for a major change would run to many hundreds of aircraft.
 
RAF did have minimum speed requriements with some of their specifications.
Air Ministry specification F.7/30 specified a fighter with a minimum speed of 250mph, which was the start of the Spitfire.
Specification F.35/35 was for a 'very' high speed fighter, to be made by Airspeed, but never built.
Specification F.18/37 was for a 12 gun fighter capable of at least 400mph, from which the Hawker Typhoon emerged.
 
Oh yeah I forgot about that early Spit requirement, I think it's in one of my Price books and a sea level requirement if I'm not mistaken, they were big on that in the late-thirties but not so much top speed at altitude, at least in the speed races of the day which trialled a lot of european fighters. I never got the impression the RLM or British were quite like the USAAF/USN about the speed requirement, then when I thought about it neither the Russians nor the Japanese either. Would you agree or do you think I might be off on this (I mean I could be, sure)?

Hey and the way I read it (Price again, but he's been wrong before) the Typhoon started as a private venture and the specification was written around it. Is this not correct?
 
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Some authors say that the Japanese navy had a requirement for a fighter that could do 310mph ( or the metric equivalent) plus a few other performance specs that led to the Zero.

British air ministry may have put out feelers or a wish list to which manufacturers responded before official specifications were written up.

Specification F.18/37 , just as Claidemore stated, called for a minimum speed of 400mph and while Hawker got a contract for the Typhoon out of it, Hawker was by no means the only company to submit proposals. It was policy in those days to start the procedure for an aircraft's replacement even as it was coming into service. Hawker had gone to the Air Ministry with a proposal but were told to hold onto it as the F.18/37 specification would be coming out soon and they might want to revise their proposal to fully meet the specification. Bristol, Gloster, Supermarine all submitted proposal in addition to Hawker.
 
 
A few points I recall from various readings over the years. The Army Air Corps was infatuated with the inline liquid cooled engine, thus the P-38, P-39, and 1/2 our topic, the P-40. Don't forget the P-40 was really a P-36 with the radial removed. All of those aircraft were powered by the Allison because the customer, the USAAC, wanted it that way. Alot of misguided desires by the USAAC , were produced in all of these aircraft. From what I recall, Lockheed basically HAD to design a twin engine aircraft to meet the performace desired by the USAAC, because they wanted the Allison used.

The best two U.S.A. fighters in Europe, were not designed as the Army specifically asked. Republic used a radial in thier design despite the preference of an inline. The performance of the design forced it's acceptance. And we all know how the P-51 came into existence, with the USAAC not even involved and even delayed "looking" at the aircraft.
 
you seem to having a lot of trouble with the difference between "as designed"" and as used 2-4 years after the initial design was done.

Why add the weight?
British opinion at the time (summer/fall of 1940) was that a fighter without armor and self-sealing tanks was good for little more than being a trainer. Two synchronized .50 cal MGs were hardly an effective armament. With even the free firing .50 cal guns at the beginning of 1940 cycling at 600rpm the Sychro guns were down well under 500rpm. Even later installations (P-39 and British Mustangs) with nominal 800rpm guns often couldn't top 500rpm when synchronized.

A high flying plane that was an unprotected torch and was lacking in fire power doesn't really do much good.

Extra gun ports/cartridge chutes, protruding gun barrels and such also hurt. Original design requirement was for two .50 cal guns with just 200rpg. Just think about that and see how well it lines up with the oft told tale about the P-40 being "designed" to be a ground straffer. A US .50 weighed about as much (or more) than a German 20mm MG/FF.



WW II turbos were not an add on accessory like a car turbo. Because of their weight and bulk (for fighters) you either designed them in from the start or you did without.



A second gear on the Allison would have done next to nothing. It was already using a altitude gear. Please go over existing threads and learn why and how supercharger gears work and the effect they have. Also learn why the German engines performed at the altitudes they did or didn't perform. the Db 601Aa in the 109E made slightly less power at 12,000ft than the engine in a P-40C and despite the hydraulic drive it didn't get better at higher altitude. The DB 601N engine made about 20hp more than an Allison with 9.60 supercharger gears about 1200ft higher. The DB Hydralic supercharger charge drive did ZIP for high altitude performance.

Could the P-40 have worked better? Yes just look at the P-40F but it was still a bit late and too heavy. Part of that goes back to the very beginning. You can take a fuel tank out of a plane to lighten it up very easily, but taking out the extra wing area and structural weight that allowed the plane to carry the fuel tank and/or take off in a given distance with that tank are a lot harder to take out later vs designing them out to begin with. The XP-40 was designed to hold 158 US gallons in unprotected tanks and this went to 180 US gallons in the P-40-CU. that is just about 150 imp gallons. Think about adding a 55 gallon fuel drum to the INSIDE of either a Spitfire or 109 in addition to what is already there. Range (fuel capacity) vs take-off distance (field length) is a trade-off every plane designer/manufacturer and air force had to make. The more fuel the bigger the wing needed to be, the bigger the wing the heavier the wing and so on.

The US seems to have had a tendency to over gun their aircraft, especially in the 1940-42 time frame.
 

Lockheed had to use the Allison because there was no Single 1500hp engine available. The Wright R-2600 was on the way but in 1937 it wasn't really flyable hardware and needed more time. The R-2800 was two years away from being put in a test mule. Nobody was sure that an aircooled radial would stand up to being turbo charged, they hadn't tried it yet. The Allison wins by default.


The design of the P-47 was a bit tortured. It started out as a very small Allison powered fighter but it was soon realized that initial estimates were way off the mark and weight growth ( which required ever larger wings) would soon leave the plane no better than what was already being made lead to a re-think. The Army was also starting to worry about being able to supply enough Allisons for all the different programs. I don't know who came up with the eight .50 cal gun requirement but that sealed the deal. Eight .50s could not be carried by a 1150-1350hp engine.
 
Seriously some of you blokes here have an incredible array of specific and detailed knowledge. I have trouble remembering half the stuff I read.
 

Again, I agree. Severesky / Republic had gained thier turbo-supercharged radial knowledge with the P-43 Lancer. When the orginal design (little of anything I can find to read about) of the inline P-47 was obvious to achieve nothing in performance gains, Republic basically enlarged the P-43 design to use the new R-2800, along with Rebuplic's method of turbo-charging the engine.
 

First time I read that I thought "planes made out of LEAD" no wonder the P40 struggled at altitude
 
davparlr said:
Could you expound on this a bit. Not that I doubt it, I am just interested in your rationale.
Click to expand...

The US was coming off a decade long one .50 and one .30 cal gun standard. Usually 200 rounds for the .50 and 500 rounds of the .30 although two .30s could be and were fitted at times. in the 1939-40 period Navy planes went to one .30 and three .50s and then four .50s while doubling the ammo load per gun (or more), unfortunately without a compensating increase in engine power. Throw in the fitting of armor and self-sealing tanks and weight was certainly going up faster than power. Good as the .50 was it was a heavy gun and used heavy ammunition.
The Army over did things as well. Adding a pair of .30 cal guns to the P-39 (in the nose) was bad enough but when they went to four .30s in the wings with 1000rpg things were getting just a bit silly. That is approximately 240lbs of .30 cal ammo and the .30 cal ammo was going to last over 30 seconds longer than the 37mm and .50 cal ammo. Fitting the early P-40s with 380 rpg of .50 cal ammo for the fuselage guns went the other way. the .50s might have 20 seconds of firing time after the wing .30s ran dry.
The P-46 prototype with TWO .50s and EIGHT .30s?
The P-40E with SIX .50s? impressive firepower but one .50 gun weighs almost 3 times as much as a .30 and the ammo is 5 times heavier. Upping the engine power by 50-100hp doesn't quite cut it.
P-47? well it had 2000hp but at 425rpg of .50 cal ammo the P-47 was carrying over 1000lbs of ammo. They often flew with much less ammo.
The prototype P-55 originally had two 20mm and two .50s for a 1250hp engine.
The P-54 had more power but had TWO 37mm guns in a tilt-able nose mount to match the trajectories of the two .50s.
The P-53 (or P-60) was supposed to have EIGHT .50s but didn't get the 2000hp engine until much later in development.
And so on.

As an Idea of the weights involved a P-40C carried around 590lbs of guns and ammo compared to a Spitfire with eight .303s 440lbs or so. A P-40E carried just over 900lbs and a P-39 was around 860lbs. Spitfire with two 20mm and four .303s was about 650lbs.

The entire reason for being for a fighter/pursuit/interceptor is to get a battery of guns into firing position against an enemy aircraft. Too light an armament and even the best performing aircraft will find success difficult. Too heavy an armament and the aircraft will face extreme difficulty in getting into firing position.
 
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Famous P-40 pilots

Nicky Barr: RAAF ace (11 victories); also a member of the Australian national rugby team.
Gregory Boyington: AVG/US Marine Corps; later commanded USMC VMF-214, the "Black Sheep Squadron".)
Clive Caldwell: RAAF, highest-scoring P-40 pilot from any air force (22 victories); highest-scoring Allied pilot in North Africa;[85] Australia's highest-scoring ace in World War II (28.5 victories).
Daniel H. David: USAAF; later famous as the comedian and actor Dan Rowan; scored two victories and was wounded, while flying P-40s in the Southwest Pacific.
Billy Drake: RAF, the leading British P-40 ace, with 13 victories.
James Francis Edwards: RCAF, 15.75 victories (12 on the P-40); also wrote two books about British Commonwealth Kittyhawk pilots.[86]
Geoff Fisken: RNZAF, the highest scoring British Commonwealth ace in the Pacific theater (11 victories), including five victories in Kittyhawks.
Jack Frost: SAAF, the highest scoring air ace in a South African unit, with 15 victories (seven on the P-40); missing in action since 16 June 1942.[86]
John Gorton: RAAF; Prime Minister of Australia, 1968–1971; flew Kittyhawks with No. 77 Squadron in New Guinea and was an instructor on the type.
John F. Hampshire Jr.: USAAF, 23rd FG, China; equal top-scoring US P-40 pilot (13 victories).
David Lee "Tex" Hill: AVG/USAAF, 2nd Squadron AVG and 23rd FG USAAF, 12.25 P-40 victories (18.25 total).
Bruce K. Holloway: AVG/USAAF, equal top-scoring US P-40 pilot (13 victories); later a USAF general (four-star) and commander of Strategic Air Command.[87]
James H. Howard: AVG/USAAF, six victories in P-40s with the AVG; later awarded the Medal of Honor following a single action in a P-51 over Europe.
Nikolai Fyodorovich Kuznetsov: VVS, twice Hero of the Soviet Union; most of his 22 victories were scored in P-40s.
Stepan Novichkov: VVS, highest scoring Soviet P-40 ace, with 19 victories; a further 10 victories on other types.
Petr Pokryshev: VVS, 14 victories in P-40s; twice Hero of the Soviet Union; eight victories on other types.
William N. (Bill) Reed: AVG/USAAF, commanded 3rd FG, Chinese-American Composite Wing (Provisional), 14th Air Force; nine victories in P-40s.
Robert Lee Scott, Jr.: USAAF, commander of the 23rd FG, China; more than 10 victories in P-40s.
Kenneth M. Taylor: USAAF; one of only two US pilots to get airborne (in a P-40) during the attack on Pearl Harbor (7 December 1941), during which he shot down two aircraft and was wounded in the arm.
Keith Truscott: RAAF; pre-war star of Australian football; became an ace in the UK during 1941, while flying Spitfires; commanded a Kittyhawk squadron at the Battle of Milne Bay (New Guinea, 1942); killed in an accident in 1943, while flying a P-40.
Boyd Wagner: USAAF; while flying P-40s, Wagner became the first USAAF ace of World War II (on 17 December 1941), during the Philippines Campaign.
Len Waters: RAAF, the only Australian Aboriginal fighter pilot of World War II.
George Welch: USAAF; one of only two US pilots to get airborne (in a P-40) during the attack on Pearl Harbor. Welch destroyed three Japanese aircraft that day.

Source:
http://en.wikipedia.org/wiki/Curtiss_P-40_Warhawk#Famous_P-40_pilots

Quite a few aces there, the Soviet pilots are particualrly impressive, as they fought the 109 head to head same as the brits, and their P-40s came out on top.
 
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