1941/42: fighter with single stage R-2800, a missed opportunity?

[P-39 Expert]

The Hellcat and P-39 were both mentioned in the thread, and the thread was old.

Why do you say it was stripped?

 

[fubar57]

 

[Vincenzo]

"Airplane does not meet Air Corps cooling requirements at any of these powers"

 

[tomo pauk]

The Hellcat and P-39 were both mentioned in the thread, and the thread was old.
Why do you say it was stripped?

Because it was with 87 gals of fuel, as it can be seen via the takeoff weight.
P-39N is too late for the time frame, since it was in production last 2 of 24 months of interest here. Same applies fot the Hellcat.

 

[Shortround6]

It may be even worse if you open the whole report.

"At 9700ft and at manifold pressures above 55" hg, mixture temperatures were within the detonation range."

Actual coolant and outside air temperatures are listed in the full report

"High Prestone temperature observed in climb was 136^ C at 11,000ft at 1235hp with a free air temperature of +4^C."

This is 11^C above the max temp listed in the engine chart for a P-39Q.

I will note (trying to be fair) that this air temperature was bit warm for Buffalo in October. Standard air temp charts call for 19.77^F (-6.8^C)at 11,000f on a standard 59^F (15^C)day. However a standard "Hot" chart with 100^F (37.8^C) at sea level calls for temp of just under 80^F (25^C)at 11,000ft. Other charts may vary. Hot charts did vary, the one I used is supposed to be "typical".

 

[P-39 Expert]

"Airplane does not meet Air Corps cooling requirements at any of these powers"

Neither did the P-47B, P-51A, or SpitfireV for that matter.

 

[P-39 Expert]

Because it was with 87 gals of fuel, as it can be seen via the takeoff weight.
P-39N is too late for the time frame, since it was in production last 2 of 24 months of interest here. Same applies fot the Hellcat.

Again, I disagree on the weight.
Saving 33gal (120-87) would only account for 198#. The N grossed 7650 with 120gal fuel, an additional 198# would have increased weight of the test plane to only 7472# (7274+198), still below published gross weight.
Joe Baugher's site shows the first 100 N models to be within serial numbers 4944 to 5043 and this plane was #4400 (probably a K or L with the new -85 9.6 geared engine). The reduced fuel models started with the 167th example indicating the test model had the full 120 gallons. No K or L models had reduced fuel capacity.
ALL the AAF planes were tested (official performance test) at a weight below their published weights. If you discount this test then you should discount every other test. This indicated they were using average or mean fuel during the flight. Taking off at full gross weight for the test and "correcting" the test weight to reflect average or mean fuel for that flight.
The British "corrected" (their term) the gross weight in their tests to 95% of takeoff weight to reflect the average weight of that flight with average fuel.
Also, in the performance tests the amount of fuel was almost never mentioned, even when they state the number and caliber of guns and the corresponding amount of ammunition.
When reduced fuel is mentioned, specifically one test each with the P-51A and P-38G, both those planes were lighter than published weights AFTER the reduced fuel is deducted.
Again, if you discount this test than you should discount every other AAF test, they were all light.

 

[Vincenzo]

Neither did the P-47B, P-51A, or SpitfireV for that matter.

give me the sources

 

[Vincenzo]

So the test is a P-39K-1-BE modified for became a N-1...

 

[P-39 Expert]

give me the sources

wwiiaircraftperformance.org, same as for the P-39.

 

[P-39 Expert]

So the test is a P-39K-1-BE modified for became a N-1...

My guess since I couldn't find 42-4400 in the list of serial numbers.