Quote:
The main factor actually was the requirement that you have three or more engines for extended over-water ops. When ETOPS relaxed that requirement to two engines, the trijet was done.
Two engines are more efficient...
- Less rotating-machinery drag (saves energy).
- Fewer support systems (saves weight).
- Less flow energy-loss (no long s-duct).
- Larger fans are actually more efficient anyway. The core is going to be a little bit heavier, but it can optimized for max fuel efficiency at cruise speeds vice T/O.
If the weight and fuel savings were not enough, the reduced Mx cost (by 33%) seals the deal.
ETOPS- "Engines Turn Or People Swim". I'll take as many engines as you'll give meOriginally Posted by rickair7777
Yes.The main factor actually was the requirement that you have three or more engines for extended over-water ops. When ETOPS relaxed that requirement to two engines, the trijet was done.
Two engines are more efficient...
- Less rotating-machinery drag (saves energy).
- Fewer support systems (saves weight).
- Less flow energy-loss (no long s-duct).
- Larger fans are actually more efficient anyway. The core is going to be a little bit heavier, but it can optimized for max fuel efficiency at cruise speeds vice T/O.
If the weight and fuel savings were not enough, the reduced Mx cost (by 33%) seals the deal.
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