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Sadly I've never found original performance test data for a P-40K
Yeah I've seen those, except the second page on the addendum, which is interesting (and better than nothing) but still doesn't tell us very much and apparently done at military power. All they were looking at there was what difference smoothing the paint made.
There must be a proper evaluation of the K model both by the USAAC, RAF, and probably the Soviets too. I know there is a document on WWIIaircraftperformance.org where they used a P-40K in some tests against a Zero and another where they used it against some Allied aircraft but I couldn't find them, they aren't in the P-40 section.
A P-40K and a P-43 were test flown against an A6M2 captured by China after it crashed landed on a beach in 1941. In 1942 it was rebuilt by Chinese and American technicians and tested in early 1943.
No they weren't, though it helped to boost the power by 15-20% which was just a matter of pushing the throttle forward, and / or drop the weight a bit.
A P-40K and a P-43 were test flown against an A6M2 captured by China after it crashed landed on a beach in 1941. In 1942 it was rebuilt by Chinese and American technicians and tested in early 1943.
Three comments on that -
My source for that is Shamburger, Page & Christy, Joe. The Curtiss Hawks. Wolverine Press, 1972. Library of Congress No. 79-173429 , page 231
- That would 14 mph faster than the P-40E in the Australian test we've been looking at.
- I would agree with you that what you mentioned there probbaly represents takeoff power of 1,325 Hp, which is achieved at 51" Hg
- However the normal WEP rating (not overboost) for the P-40K-15 was 60" Hg for 1,550 hp. So that would be 15% more power.
I recall reading that years ago along with critiques of the report. Given the statement that the engine could produce 900 HP, it's obvious that the engine/aircraft was not in service condition. A favorable comparison of the P-36A to the Zero confirms that. Pilots that flew the P-36A against the Zero on Dec. 7th would have disagreed with that report.Oh yea, good one, here you go: General Technical Data and Flight Characteristics of the Japanese Zero Fighter Plane
That's a significant power increase. That 60" must be mentioned in a P-40K Pilot's Notes or Operating Instructions sheet somewhere? Was the radiator or oil cooler improved from the P-40E to the P-40K or N to accommodate the increase in power?
I recall reading that years ago along with critiques of the report. Given the statement that the engine could produce 900 HP, it's obvious that the engine/aircraft was not in service condition. A favorable comparison of the P-36A to the Zero confirms that. Pilots that flew the P-36A against the Zero on Dec. 7th would have disagreed with that report.
That's a significant power increase. That 60" must be mentioned in a P-40K Pilot's Notes or Operating Instructions sheet somewhere? Was the radiator or oil cooler improved from the P-40E to the P-40K or N to accommodate the increase in power?
I would note that the HP ratings on the chart for WEP are in error. A simple typo I suppose.The manual for the P-40F and L (merlin engines) says the WEP rating which is apparently some kind of automatic setting, is 61" Hg (page 7 of the PDF) and it says that WEP is available in both low and high gear, use low gear below 8,000 ft and high gear above 8,000 ft. Later on page 42 the Critical altitude for WEP is listed as 4,600' for low gear and 12,000 ft for high gear.
See attached
Problems with the P-40 are the large amount of weight they were trying to lift (when climbing) with 1150hp or less.
Standard US procedure was to use military power for the first 5 minutes of the climb (42-44in in the case of the P-40s and the full 3000rpm)
British and Australian testing may do the P-40 a disservice if they use the 2600rpm and lower boost for the entire climb.
Both countries used a 5 minute full power rating (or sometimes 3 for the British) but the British then dropped to a 30 minute rating (and used that for all climbing tests) while the Americans didn't use that time period at all, the Americans dropped to either a one hour rating or (same rating different name) max continuous which was good for as long as the fuel lasted or a temperature gauge went into the red. The British/Australian climb tests are using the max continuous rating which for the Allison In the P-40 was about 1000hp.
The P-40 would have climbed very well indeed had the supercharger been able to supply 60in (or even 56in) for more than a minute or two when climbing.
The 60 in limit on the P-40 K was all done at 2500ft no RAM or a bit over 3000ft when at climb speed. High speed level flight was good for a bit higher.
The 56in limit was good for for 4300ft NO RAM. there is little or no difference between the superchargers on an E or a K. When Climbing the the K could have had 60in at sea level (on a standard day) and held it to around 3000ft but then the pressure would decline until at something over 4300ft the pressure was down to 56in as the plane continued to climb (far into the 2nd minute or start of the 3rd?) the pressure in the manifold would continue to drop as the supercharger just cannot supply anymore air at an engine speed of 3000rpm, Until you hit the high 11s or low 12s ft at which point the supercharger, with wide open throttle is supplying 42in in the case of the K. again, sources are all over the place depending on exact manifold and backfire screens.
There was no real change in the radiator or oil cooler but the engine in the K used mixed water/glycol cooling instead of pure glycol like the engine in the E. This gave a better heat transfer and coped with the increase heat load.
I would note that the HP ratings on the chart for WEP are in error. A simple typo I suppose.
Where is all the drag coming from?