Turbos will indeed complicate some shit.

Eric Ruttan wrote:

Ah yes.  But I was thinking of a turbo engine making full power up to 25K.  Which of course destroys the symmetry of the math. So I restate. If at X mpg IAS at 2000' you can get rid of Y BTU heat Then can you get rid of Y BTU heat at X mph IAS at 25K' If IAS is a direct measurement of Air Mass then yes, as the Air Mass is the same. If not then IAS is not a direct measurement of Air Mass. Or my logic is faulty. Thanks for your tolerant indulgence.