3 ms·
I'm not an aeronautical engineer but my understand is that a lot of the increase in efficiency is due to introduction of turbofan engines with higher bypass rat
by hodgesrm 9y ago
I'm not an aeronautical engineer but my understand is that a lot of the increase in efficiency is due to introduction of turbofan engines with higher bypass ratios. These economize on fuel since the fuel increasingly runs the turbofan to compress air that enters the bypass duct rather than generating thrust directly. Thrust instead comes from decompression of the air as it flows out behind the engine.
B787, B777, AB380, and AB350 all have GE or RR turbofans with 8:1 or greater bypass according to numbers in Wikipedia. [0]
This is not the only design improvement but it's a big one.
[0] https://en.wikipedia.org/wiki/Bypass_ratio https://en.wikipedia.org/wiki/Bypass_ratio
- ocdtrekkie 9y agoWouldn't these design improvements equally apply to a new hypothetical four engine plane?
- hodgesrm 9y agoThat's a good question. Other big factors in operating expense are load factor (i.e., percent of seats filled) and weight. The A380 is in trouble because it measures poorly on the preceding and in addition can only fly out of hubs with specially modified gates. The 747-8 seems to be largely a freighter with production down to about 1 a month. At this point it seems unlikely we'll see another big aircraft design program any time soon unless a country like China decides to do one for status reasons.