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Old 06-03-2004, 11:21 PM
psfred psfred is offline
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Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Brian:

At 80,000 ft, the air is pretty thin, so drag is minimal. The SR-71 will, as far as I know, fly up to the point there isn't enough air to allow adequate flight control, it's not relaly limited by engine breathing. That high, with that little drag, it doesn't burn much fuel once it's up to speed, at least compared with take off and climb.

It did burn considerably less fuel than the Concorde, but then it's only about 1/4 the size (or less). Concode burned at least half the fuel load getting up to altitude and speed. That's why there was never an engine out emergency -- would have resulted in a ditching, as there wasn't enough fuel on board to return to origination or destination at less than 60,000 ft. Engine maintenance was overwhelming (and I'm sure one of the reasons Concorde never made a dime for anyone). Just like the Great Eastern -- even nearly bankrupted the shipbreakers!

Peter
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