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- 6
- Apr 9, 2023
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Several notes from the start:Keeping this in mind, the most obvious causal factor in the superior performance of European fighters is that the European engines available for use in the 1935-40 timeframe were of higher performance in terms of P/W ratio (particularly at altitude) than similar engines then available in the U.S. The German DB-601 and British Rolls Royce Merlin engines were both superior to the American Allison engine, the only serious V12 the U.S. produced in the late 1930s. It would take until 1940 for the U.S. radial engine makers to launch high-output versions of their radial engines (e.g. supercharged R-2800s) and of course the U.S. capitalized on the high-performance, liquid-cooled Merlin for use in the P-51.
So the question is, was the entire scope of the performance difference due to powerplants alone or whether there were other salient developments in aircraft aerodynamics and/or structures that help account for the superior performance of British and German fighters to start the war.
I think the best way to do this comparison is to compare three specific aircraft c. 1940: 1) The BF-109E 2) The Spitfire Mk1 (or Mk2) 3) The Curtiss P-40 (alternatively, substitute the P-39).
Note 2 - there is a difference between a design choice & a technical advance. German and British fighters also may have had higher performance on the metrics I mentioned above not because German's had specific ideas that were more advanced than the U.S.'s designers, but also because they were designed to do with different goals in mind. I have tried to equalize by not comparing aircraft designed for obviously different goals (eg, a twin-engined interceptor vs. a single-engined fighter). But there still might be some differences. For example, U.S. fighters might have been heavier (thus reducing climb rates) because the USAAC put more emphasis on armor protection than the RAF did. If that is the answer, happy to hear that too. Just want to know!
You sure? The only European nation with operational carriers in 1940 was Britain. The French Bearn was little more than a transport by that point.My uneducated opinion is that with the U.S. comfortably behind its ocean defenses, fighters weren't a priority. Small enemy fighters just weren't going to make it here. The only way they could get here would be by aircraft carriers. I'd bet a large sum of your money that in 1940, the U.S. carrier planes were better than any of the European nations carrier planes. A long range patrol bomber would be more useful.
even 1935 to 1940 covers a huge chunk of time in propeller aircraft design. The P-35 entered in service in 1938 and was running late. It might have compared rather well to European fighters of 1938. First Squadron Spitfires only went operational with them in Dec of 1938, Hurricanes had fixed pitch props, very few (if any service) 109s had DB 601 engines. P-35A's were commandeered export Swedish planes. The P-40s were sort of in no man's land in 1940, they could perform just about as well as any European fighter except the Spitfire but they weren't actually combat ready. They were not fitted with protective equipment until the end of the year and the .50 cal guns which made up 1/2 of their fire power were not suitable for combat in 1940 (or even part of 1941). However the P-40 was faster than the Hurricane and it was just about as fast as the 109E-3/4 while being a larger/heavier aircraft.The single-engined fighters which were being developed in the U.S. at the same time included the Seversky P-35, Bell P-39, and Curtiss P-40 (derived from the P-36). There was wide belief - confirmable by various performance metrics - that the U.S. fighters were inferior.
This rather ignores the two stage supercharged Twin Wasps in the Wildcats (made in small numbers in 1940) and the 1200hp Wright Cyclones (admittedly an oil problem or two) and the Wright R-2600. not used in fighters but was being loaded into A-20s (over 1900 R-2600s built in 1940, nobody else came close).. It would take until 1940 for the U.S. radial engine makers to launch high-output versions of their radial engines (e.g. supercharged R-2800s)
We can take a look on the P-30, that was powered by a turbocharged engine already in early 1930s. The P-43 was also a high-altitude fighter. The stillborn XP-37 was trying to offer the same (= competitive high-altitude performance), so was the XP-39.Just my $0.02, the inferior performance of the U.S Pursuit fighter had also something related to the USAAC fighter doctrine that seemed satisfied with single engines, small range, low altitude fighters.
Lockheed tried to circumvent this by offering the XP-38 as an interceptor.
The Allison did not really start out as an airship engine. It started as a general purpose engine and while the army was interested they had no money.
The Navy did and the army suggested that Allison look to the navy. The Navy was not really interested in a supercharged engine for airships but ordered 2 (?) the superchargers came later.
Army spent a lot of money (for the times) on the X-1430 project
See. Continental Hyper Cylinder and the O-1430 Aircraft Engine
and let's remember that the Army in the beginning of 1939 owed Allison 900,000 dollars for research and development already done and for which they never were paid.
Allison had to 'forgive' debt in order get permission to export the engine to France and England.
Continental didn't do anything until the Army paid and the Army didn't pay unless certain conditions were met. If an test engine broke during test the Army didn't pay until it was fixed and completed the contacted for test.
Now squeeze Lycoming into the mix
Lycoming O-1230 Flat-12 Aircraft Engine
In 1932, Lycoming began developing a high-performance engine to meet the Army Air Corps’ needs. The engine became the O-1230, but it was outclassed by the time it was ready for production.oldmachinepress.com
Lycoming spent about 500,000 of their own money and got some from the Army late in the project.
and as has been said, P&W and Wright were more interested in the commercial market as they could not stay in business with government contracts. P&W built a bunch of R-1535 radials, almost all for the Navy, and P&W finally discontinued development due to the lack of commercial sales and the fact that the older R-1830 had been upgraded and was more suited to larger, more modern aircraft.
I don't really agree with the premise of this at all, I think considering the late entry to the war, the remoteness from Europe geographically, the numerous political reasons to avoid war (or in some cases support THE OTHER GUYS WITH THE EXPENSIVE BLACK OUTFITS), the lack of funding in the early 30`s, the USA did almost unbelievably well to catch up. In fact in certain areas the USA were miles ahead of Britain, specifically pressure carburettor use.There was a wide consensus in U.S. military circles ~1939-1940 that U.S. pursuit fighters were substantially less capable in terms of performance than their equivalent European counterparts. Specifically, in Germany, the BF109-E (the first version to use the Daimler-Benz DB-601 engine) began production in 1938, while the original airframe was designed in 1934. In Britain, the Spitfire airframe was designed in 1935 and the airplane went into production in 1938. The single-engined fighters which were being developed in the U.S. at the same time included the Seversky P-35, Bell P-39, and Curtiss P-40 (derived from the P-36). There was wide belief - confirmable by various performance metrics - that the U.S. fighters were inferior.
What accounted for this difference in performance?
Of note: I am looking mostly for an engineering answer, and references would be greatly appreciated!
Advances in in aircraft performance are generally governed by developments in 1) aerodynamics 2) propulsion and/or 3) structures.
Keeping this in mind, the most obvious causal factor in the superior performance of European fighters is that the European engines available for use in the 1935-40 timeframe were of higher performance in terms of P/W ratio (particularly at altitude) than similar engines then available in the U.S. The German DB-601 and British Rolls Royce Merlin engines were both superior to the American Allison engine, the only serious V12 the U.S. produced in the late 1930s. It would take until 1940 for the U.S. radial engine makers to launch high-output versions of their radial engines (e.g. supercharged R-2800s) and of course the U.S. capitalized on the high-performance, liquid-cooled Merlin for use in the P-51.
So the question is, was the entire scope of the performance difference due to powerplants alone or whether there were other salient developments in aircraft aerodynamics and/or structures that help account for the superior performance of British and German fighters to start the war.
I think the best way to do this comparison is to compare three specific aircraft c. 1940: 1) The BF-109E 2) The Spitfire Mk1 (or Mk2) 3) The Curtiss P-40 (alternatively, substitute the P-39).
Note - I am being very specific to the timeframe of 1935 - 1940 because later U.S. developments, such as the P-51 Mustang, F6F, etc., largely corrected much of the performance deficit. While one could still argue on the margins about the superiority of one design over the other, there was no longer a consensus amongst the U.S. military officials that their pursuit fighters were inferior.
Note 2 - there is a difference between a design choice & a technical advance. German and British fighters also may have had higher performance on the metrics I mentioned above not because German's had specific ideas that were more advanced than the U.S.'s designers, but also because they were designed to do with different goals in mind. I have tried to equalize by not comparing aircraft designed for obviously different goals (eg, a twin-engined interceptor vs. a single-engined fighter). But there still might be some differences. For example, U.S. fighters might have been heavier (thus reducing climb rates) because the USAAC put more emphasis on armor protection than the RAF did. If that is the answer, happy to hear that too. Just want to know!
The P-39, after the prototype, and the P-40, were designed around the highest critical altitude engine/s Allison could provide at the time, using a single speed-single stage engine.Just my $0.02, the inferior performance of the U.S Pursuit fighter had also something related to the USAAC fighter doctrine that seemed satisfied with single engines, small range, low altitude fighters.
Lockheed tried to circumvent this by offering the XP-38 as an interceptor.
IN 1940 the US barely had a bomber anywhere near the performance of the B-17In 1940 no European country had a bomber anything near to the performance of the B-17.
And yet, P-39s and P-40s were pressed into flying escort both in the South Pacific, and North Africa, both for medium bombers and lights. The P-38s got the job for the heavies.IN 1940 the US barely had a bomber anywhere near the performance of the B-17
Only somewhat joking, It took Boeing from July 29, 1939 to March 30, 1940 to deliver39 B-17Bs. It took until Nov 29th 1940 to complete the next 38 aircraft. 20 were sent to Britain, the rest were sent back to the factory to be upgraded to B-17D specs.
The US was looking ahead, way ahead, They had asked for the B-24, B-25 and B-26 to be developed in the Spring of 1939.
But the state of the art in 1939 even looking ahead with crystal ball did not look good for long range escort fighters.
The US starting taking delivery of the B-23 in July 1939. It had crap for defensive guns (few people had any better although the British were working on it) but it could max out at over 280mph, cruise at 210mph and carry a 4000lb load for 1400 miles which, IMO, put the escort fighter in prespective in 1939. Give the bomber a 200 mile reserve or 300miles.
You need to fly 550 miles, fight for a few minutes, and return 550 miles and have a reserve and forget the B-17, do it at the Altitude the B-23 can fly at.
Now you have to do it using the engines that available in 1939 or you expect to be available in 1940 or early 1941.
Again for perspective, the first 24/25 B-25s did not have power turrets (indeed did not more than one .50 cal gun and two .30s) and did not have self sealing tanks but did have a range of 2000 miles with a 3000lb bomb load. The next 40 or so had self sealing tanks, a bit of armor and the smaller fuel tanks cut the range to about 1300 miles.
Design you escort fighters to escort these B-25s.
Can you do it?
The P-40 can't
The Spitfire can't
The 109 can't.
So why are we criticizing the P-40 or P-39 for not being escort fighters?
I don't really agree with the premise of this at all, I think considering the late entry to the war, the remoteness from Europe geographically, the numerous political reasons to avoid war (or in some cases support THE OTHER GUYS WITH THE EXPENSIVE BLACK OUTFITS), the lack of funding in the early 30`s, the USA did almost unbelievably well to catch up. In fact in certain areas the USA were miles ahead of Britain, specifically pressure carburettor use.
The USA was just let down by a deficit in compressor research. In my view nobody in Europe fielded a better all round single seat piston aircraft than the P-51D right up to the end of the war.