P-47D-11 Power Settings

[Stoney]

Running a test last night, I noticed that as I approached 25-30K in a climb, that my manifold pressure kept slipping off.  I was conducting a climb using the "normal" setting using 2550 RPM and 42" of MP.  Above 25K, I kept having to nudge the throttle to maintain 42".  Further, once at 30K, I noticed that WEP was not available at that altitude.  Neither the MP nor fuel burn changed, only the sound of the engine.

I was under the impression that the critical altitude, for all of the Jugs, was in excess of 30K?

[Mike Williams]

Hi Stoney:

FTH in a climb will be less than in level flight.  I'm not sure what the FTH using 42" would be off hand.  Check P-47 Performance Trials.  FTH in climb using 52"  is around 24,000 ft.  56" is pushing 28,000 ft.   I think the turbo regulator used and its rpm limitations can effect this to some degree.

[Stoney]

Awesome information Mike, as always.  I'm assuming the lack of exhaust backpressure at lower than WOT settings limits the turbo speed, and therefore, the potential MP available? 

[bozon]

Sure demonstrates the effect of the paddle blade prop on the D-10 curves. Quite amazing.
I could only wish we had it on our razorback.