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And the P-40F/L didn't have better performance than the ASllison P-40. The difference between them was within the airspeed indicator error.
A later test of the F showed performance at differing rpm and 18,100ft. Why 18,100ft, I do not know.
Always wondered about that 362mph on December 1, 1941. All the other tests before and since have shown the P-40E to be a 340mph airplane.In terms of outright speed, perhaps not.
But where the performance was achieved was different.
Here are tests of the P-40E and the P-40F
http://www.wwiiaircraftperformance.org/P-40/P-40F_41-13601_PHQ-M-19-1440-A.pdf
http://www.wwiiaircraftperformance.org/P-40/P-40E_40-384_PHQ-M-19-1300-A.pdf
Note that this test shows a maximum speed of 342mph @ 11,400ft and 340mph @ 15,300ft.
A source like Joe Baugher (Curtiss P-40E (Kittyhawk IA)) quotes 362mph @ 15,000ft (Curtiss P-40E (Kittyhawk IA)). This must have been for ones with later engines - the E in the test had the V-1710-39 with 8.8:1 supercharger drive ratio, rather than the later 9.60:1 gears.
Baugher quotes speeds of:
335mph @ 5000ft
345mph @ 10,000ft
362mph @ 15,000ft
Time to climb to 20,000ft of 11.5 minutes.
Service ceiling was 29,000ft.
For the F, Baugher (Curtiss P-40F Warhawk) quotes speeds of:
320mph @ 5000ft
340mph @ 10,000ft
352mph @ 15,000ft
364mph @ 20,000ft
Time to climb to 20,000ft of 11.6 minutes.
Service ceiling was 34,400ft.
The test report from WWII Aircraft Performance only has two all out level speeds listed where the engine was flat out (3,000rpm), and two more with reduced rpm:
320mph @ 9,800ft (2,650rpm)
350.5mph @ 12,800ft (3000rpm)
336.5mph @ 16,700ft (2,650rpm)
364.5mph @ 19,270ft (3000rpm)
Time to climb to 20,000ft of 10.2 minutes.
Service ceiling as listed by Joe Baugher.
The test report for the E shows a time to climb to 20,000ft of 11.82 minutes. The earlier (and lighter) D has a time to 20,000ft of 10.0 minutes in a separate test.
The E has a higher peak climb rate (2,400fpm @ 10,000ft vs 2,210fpm @ 9,600ft). By 15,000ft the E's RoC has dropped to 1,370fpm (F: 1,860fpm), 20,000ft it is 880fpm (F: 1,480fpm) and 25,000ft it is 480fpm (F: 1,000fpm).
The P-40E and P-40F were in different condition in the tests so far listed.
The F had the gun ports taped over, while the E did not. The F had wing racks with shackles and stays, the E was set up for use with a belly tank (though the tank was removed for all-out level speed tests).
A later test of the F (http://www.wwiiaircraftperformance.org/P-40/P-40F_41-13635_FS-M-19-1578-A.pdf) showed performance at differing rpm and 18,100ft. Why 18,100ft, I do not know.
The speed was 374 without belly tank and sway bars removed (369.5mph with sway bars in place).
RoC was 2,185fpm @ 18,100ft and 1,380fpm @ 25,000. Quite an improvement over the earlier F.
The later N used the V-1710-81 with the 9.6:1 gears.
http://www.wwiiaircraftperformance.org/P-40/P-40N-5_42-105241_Eng-47-1685-A.pdf
Max speed is shown as 350mph @ 16,400ft. The increased altitude rating of the engine comes at the cost of low altitude climb rates. The RoC at 10,000ft is 1,935fpm compared to the E's 2,400fpm, the RoC at higher altitudes is improved: 1,365fpm vs 880fpm @ 20,000ft and 760fpm vs 480fpm @ 25,000ft. The service ceiling is also improved to 31,000ft.
So, you can see that the F definitely moves the performance up about 4-5,000ft. Without losing too much down low.
The N loses performance down low, compared to the E, in order to improve altitude performance. That is the trade-off in using a single speed engine.
Low down performance could be recovered by using higher MAPs/boost with the appropriate fuels.
A multi-speed supercharger drive should enable the P-40 to retain the low down performance E while accessing the better high altitude performance of the N. There is a small weight penalty - the 2 speed Merlin gained ~75lb over its single speed brother.
But most of the reports I have seen (I admit I haven't looked through all of them) show 'Military power' ratings in the 40's or at the most 50's for the P-40E, if they indicate it at all.
The later N used the V-1710-81 with the 9.6:1 gears.
http://www.wwiiaircraftperformance.org/P-40/P-40N-5_42-105241_Eng-47-1685-A.pdf
Max speed is shown as 350mph @ 16,400ft. The increased altitude rating of the engine comes at the cost of low altitude climb rates. The RoC at 10,000ft is 1,935fpm compared to the E's 2,400fpm, the RoC at higher altitudes is improved: 1,365fpm vs 880fpm @ 20,000ft and 760fpm vs 480fpm @ 25,000ft. The service ceiling is also improved to 31,000ft.
The N loses performance down low, compared to the E, in order to improve altitude performance. That is the trade-off in using a single speed engine.
Low down performance could be recovered by using higher MAPs/boost with the appropriate fuels.
A multi-speed supercharger drive should enable the P-40 to retain the low down performance E while accessing the better high altitude performance of the N. There is a small weight penalty - the 2 speed Merlin gained ~75lb over its single speed brother.
The use of over boosting by the P-40 is a complicated and messy story. We have a lot of threads that discuss this or at least touch on it.
Interesting how this puzzle seems to be coming together. I wonder if the Russians did any overboosting of the P-39s? I know they had slightly different versions of V-1710 so I'm not sure if it worked the same way. It might explain a lot.
Russian pilot comments have to be taken in context, their own planes, engines and guns were built to be disposable at rate much higher than the US or British aircraft, engines and guns.
Engine life was always a balance between power used and life expected with materials and heat treatment thrown in and changing.