TS: Are you referring to equal speeds? I guess 320/737 would also burn less on one-engine, but green dot.
But ETOPS distances would normally be calculated on rather high speeds, correct? For instance the 320 would normally use cca 0.78/290 descent profile, but for ETOPS calculation FCOM suggests strategies of 0.78/320 or 0.80/350 which is V
MO! I do not think a twin would consume less on one than on two at 330+ kt IAS. Am I wrong?
FCOM A320:
FL100 LR speed integrated cruise tables:
73-70 tonnes, time to consume 1hr exactly, flown ANM 357. With some simplification this reads
71,5 t, FL 100, IAS 310kt, FF 1500 kg/h/eng.
SE OPS - fixed speed strategies MCT/320kt:
71,5 t, FL100, IAS 317 kt, FF 3153 kg/h
SE OPS - holding at green dot speed:
71,5 t, FL100, IAS 225 kt, FF 2330 kg/h
If you say the 757 behaves differently, I take your word for it but I wanted to make sure we are evaluating the same options.
On the other hand, on a quad, with inboard engine out, I would not be so sure. And if somebody told me that a trimotor with windmilling #2 used less fuel at low level than on three I would have to believe that. Where's a Lockeed expert when you need one?
