RichardPrice From , joined Dec 1969, posts, RR: Reply 1, posted (6 years 11 months 2 weeks 13 hours ago) and read 13388 times:
It depends - as I found out in a Tech/Ops thread (which completely and utterly proved a belief of mine wrong!), the chevrons are for noise reduction purposes so I guess it all depends on how loud the engines are. Since RR are producing a new engine just for the A350 (currently, it remains to be seen if it will appear on other aircraft), noise reduction may be something the new engines can do on their own. The chevrons actaully increase drag somewhat, so if the actual engine can be made quieter to the point where they arent needed then its a positive for performance as well.
The massive A380 engines are LHR QC2 compliant so it all depends on exactly how quiet the A350 engines have to be!
Stitch From United States of America, joined Jul 2005, 28461 posts, RR: 84 Reply 5, posted (6 years 11 months 2 weeks 12 hours ago) and read 13240 times:
Quoting NorCal (Reply 4): I thought it was a derivative engine not a whole new engine...
I imagine it's based on the original Trent 1000 A350 powerplant with improvements in the core and larger fan diameters and such to provide the extra thrust needed (especially for the A350x-1000/A350-900R/A350-900F).
RichardPrice From , joined Dec 1969, posts, RR: Reply 7, posted (6 years 11 months 2 weeks 12 hours ago) and read 13204 times:
Quoting NorCal (Reply 4):
I thought it was a derivative engine not a whole new engine
All engines are derivative engines, there hasnt been a 'whole new engine' in 20 odd years (I think I had this discussion with someone in another thread a week or so ago).
The Trent 1000 is an RB211 lineage, the GeNX is derived from the GE90 etc etc. Sure, the newer models arent anything like the original models, but neither manufacturer went back to the drawing board with a blank sheet of paper for either engine - they took what they had and improved it.
Pratt was going to offer a cleansheet design for the 787, but was dropped.
Rolls Royce are offering a new Trent iteration for the XWB, not the Trent 1000 adaption that they were offering for the original A350 design.
DfwRevolution From United States of America, joined Jan 2010, 846 posts, RR: 51 Reply 11, posted (6 years 11 months 2 weeks 12 hours ago) and read 13096 times:
Quoting Rheinbote (Reply 10):
Otherwise chevron nozzles will be subject to WTO ruling on 'unfair' subsidies creating a competitive advantage (which is plain stupid, because that's exactly what research money should be spent for)
NASA funded research enters the public domain once the results are published. It's not for "American Eyes Only."
Rheinbote From Germany, joined May 2006, 1966 posts, RR: 52 Reply 14, posted (6 years 11 months 2 weeks 11 hours ago) and read 12991 times:
Quoting DfwRevolution (Reply 11): NASA funded research enters the public domain once the results are published.
in many cases that seems to happen, yes. But what about, for example, the NASA/Boeing "21st Century Wing" research program which seems to be quite elusive whenever one tries to dig up respective report papers?
http://www.alphastarcorp.com/right/research.html NASA/LaRC, and Boeing Jet Cruiser - 21st Century Wing
Key Accomplishments: Predicted reliability increase by a factor of 100. Reduced the weight by changing internal structure (i.e spar, height, width, skin thickness).
Any hint on further information on "21st Century Wing" research would be greatly appreciated
But back to topic: Fitting chevrons to fan and maybe core nozzles as well is one thing, but having the knowledge to design them is another. QTD yielded the know-how to tailor chevron setup and geometry to measured interior noise in three dimensions, leading to non-uniform dispersal and shaping of chevrons. This reportedly also reduces cruise drag to an extent that a need for more complex variable geometry chevrons may be obviated.
Gaut From Belgium, joined Dec 2001, 344 posts, RR: 2 Reply 15, posted (6 years 11 months 2 weeks 11 hours ago) and read 12900 times:
The chevrons are not that new, it is used on the GE's CF34 nozzles (see pictures). However in the B787 case, the chevrons are on the cowls so it's maybe patented by the nacelle manufacturer (Goodrich)...
DfwRevolution From United States of America, joined Jan 2010, 846 posts, RR: 51 Reply 18, posted (6 years 11 months 2 weeks 10 hours ago) and read 12606 times:
Quoting Trex8 (Reply 17): IIRC I read somewhere that Airbus considered it on the original A350 but chevrons actually increase fuel comsumption so they dropped the idea but it seemed it was available to them.
Yes, cheverons typically result in a minor increase in fuel consumption.
Quoting Rheinbote (Reply 14): Any hint on further information on "21st Century Wing" research would be greatly appreciated
ASAIK, those were both conceptual studies that went no where. NASA and a co-operative effort between Boeing and LM did some work on a potential SST in the late-90s, but the only means to reduce noise and air pollution were wildly impractical. I suspect there is very little information available because the project didn't go very far.
In terms of real world projects, keep in mind that the super critical airfoil (which Airbus used extensively) was pioneered at NASA's Langley Research Center. Fly-by-wire and other digital instrumentation that both Airbus and Boeing utilize were also NASA innovations.
Quoting from Flight Global:
R-R remains the only manufacturer to have signed up to be on the A350. Airbus is adamant that it is close to finalising a deal with General Electric to put the GEnx on board the A350, but whatever happens, R-R will be the lead engine supplier for service entry
Beech19 From United States of America, joined Jul 2006, 936 posts, RR: 4 Reply 24, posted (6 years 11 months 2 weeks 8 hours ago) and read 12350 times:
Quoting Trex8 (Reply 23): the A4 version of their CF680E1 has a different fan diameter to all the others. There are probably other errors too!
Well i don't know about the specific A4 version but the CF680E1 does have a 8" larger diameter fan than the other CF6-80C2 and others.
Similar to the way that the GEnX used on the 787 has a 111" diameter fan and the GEnX used on the 747-8 has a 105" diameter fan. Same motor basically though.
KPAE via KBVY
25 Zvezda: Correct. They work by causing sound pressure waves to cancel each other. I thought the latter had a 104" fan diameter. No?
26 Beech19: The GE CF6-50 (Airbus A300B, DC-10-15/-30 Boeing 747-200/300, KC-10, E-4) and the CF6-80A (Airbus A310-200, Boeing 767-200) had 105" diameter. The CF
27 Glideslope: GE will never offer a GE90 derivative on the 350. Period.
28 Beech19: Um... hate to disspoint ya. The GEnX was already on board for the previous A350. Granted the GE90 will never show up on the A350, the 3.5ft smaller d