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Old 4th March 2016 | 23:43
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tdracer
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From: Everett, WA
FD, I wasn't able to find anything meaningful on a quick search (to be fair, I'm on vacation and don't have access to my normal sources), but here is the basic theory:

Nearly all jet turbine engines have what we refer to a "TSFC Bucket" - SFC is high at low thrust, and high at high thrust, but low in the middle - sort of elongated "U" shape (the exact level and shape being a function of altitude and airspeed/Mach). For obvious reasons, the engine cycle is designed so that typical cruise thrust is at or near to the bottom of that TSCF bucket (that's why, even on a quad where this is little drop in cruise altitude/speed with an engine out, engine out range drops so dramatically - you end up operating well up that high side of the 'bucket').

So, pretty much any time you're operating at or near max rated thrust, you're operating well up on the 'high' TSFC side of that U shaped TSFC curve.

Clear???
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