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.
Jim, both my calculations (after correcting the
error that Bill pointed out) and Bill's calculations show that indicated air
speed is not a good indiction of mass flow. Identical indicated
airspeeds between sea level and 20,000 ft would have a 30% lower mass flow
at 20,000 ft than at sea level.
That does not mean you would necessairly have
any cooling problem provided you only needed to get rid of approx 70% of the
heat you did at sea level (i.e reduced power out put - but, if using a turbo
then if it were marginal cooling at sea level, I think you would have
problems at 20,000 even with the cooler air.
FWIW