Legoguy From United Kingdom, joined Jun 2006, 3301 posts, RR: 44 Reply 4, posted (3 years 5 months 1 week 1 day 14 hours ago) and read 7737 times:
I thought I read somewhere that the engine cowlings are designed by Boeing and Airbus, and as Boeing holds the patient for the chevrons on certain engines, Airbus could not use them without penalty. Is this true or am I being daft?
By the way, the chevrons look fantastic on the 787 and 747-8, it's a shame no other large aircraft feature them. I believe they were tested on a GE-90 of an EVA air 777-300ER a while back.
Can you say 'Beer Can' without sounding like a Jamaican saying 'Bacon'?
Lightsaber From United States of America, joined Jan 2005, 10661 posts, RR: 100 Reply 5, posted (3 years 5 months 1 week 1 day 11 hours ago) and read 7586 times:
Quoting EA772LR (Reply 3): I wonder if Boeing will return to a more conventional designed nacelle down the road. If Boeing was shooting for optimal efficiency, why did they use the chevrons?
Boeing/GE/RR chose a small fuel efficiency penalty to make the plane far quieter. Part of the selling point of the 787 is less restricted night-operations. There are certain airports (e.g., night landings at LHR) where having a much quieter aircraft allows for more operations.
Quoting Legoguy (Reply 4): I thought I read somewhere that the engine cowlings are designed by Boeing and Airbus, and as Boeing holds the patient for the chevrons on certain engines, Airbus could not use them without penalty. Is this true or am I being daft?
There are many patents on Chevrons. GE, Pratt, and RR all hold their own.
Lightsaber From United States of America, joined Jan 2005, 10661 posts, RR: 100 Reply 7, posted (3 years 5 months 1 week 1 day 11 hours ago) and read 7548 times:
Quoting Astuteman (Reply 6): And yet it won't be any quieter than the A380. Airbus say they achieve the same result by other means...
Yes, engine weight!
Seriously, as you noted Astuteman, there is a trade-off for each decision. Airbus with the A380 went with larger fans that cut the noise. This induced a weight penalty which hurts the A380 economics on shorter flights, but should be a pretty neutral change on longer flights (perhaps even a plus on ULH flights).
The Chevrons allow for low noise without as much weight. Thus, an airframe a little better optimized for shorter missions. The now defunct 787-3 rears its head.
AeroPiggot From United States of America, joined May 2005, 280 posts, RR: 0 Reply 10, posted (3 years 4 months 3 weeks 2 days 11 hours ago) and read 5321 times:
At the first flight of the 787 from Everett, I was standing by the runway, and that was the lowest engine noise I have ever heard from wide body twin. In fact I could not hear the 787 engines over the chase airplanes.
A scientist discovers that which exists, an engineer creates that which never was.