Those two new engines (and their customers) have been causing some uproar in until recently peaceful NB segment. The author is (very) convinced the PW1000G series is on the winning hand and he explains why;
revolutionairy technology instead of evolutionairy larger thrust range (up to 40k lbs) potential to further lower fuel burn
Myself I tend to give the LEAP-X the benefit of the doubt based on the CFM Safran+GE) track record, GE's GENX technology and a natural skepticism about a hot running gearboxes in compressor inlets.
Last week Airbus John Leahy said he is "comfortable" with Pratt & Whitney's P1000G maintenance projections of 20% lower maintenance costs compared with today's engines and that Airbus tests of a P1000G on an A340-600 testbed support Pratt's claims. http://www.flightglobal.com/articles...ave-7-8-million-price-premium.html
I think this applies to the Leap-X as well, so I'm not sure why they're giving that to the GTF.
It's an interesting fight, since the two companies are tacking the same problem (fuel burn) via two different paths. One is going after propulsive efficiency, one after thermodynamic efficiency. Both are viable paths and it's a question of which company can push farther down their respective roads.
One advantage I think Leap-X has is that that technology would scale to a new large engine a lot more easily than GTF would.
Stitch From United States of America, joined Jul 2005, 26723 posts, RR: 83 Reply 2, posted (2 years 8 months 3 weeks 5 days 20 hours ago) and read 15269 times:
Quoting tdscanuck (Reply 1): One advantage I think Leap-X has is that that technology would scale to a new large engine a lot more easily than GTF would.
Pratt believes that the GTF can scale to over 100,000 pounds for use on the 777 and they note the bigger the fan, the shorter the engine (relative to a conventional engine) because they reduce engines stages along with their attendant discs and airfoils. So the bigger the engine, the lighter it gets and the less maintenance it needs compared to a conventional engine.
sirtoby From Germany, joined Nov 2007, 282 posts, RR: 22 Reply 5, posted (2 years 8 months 3 weeks 5 days 12 hours ago) and read 15161 times:
Quoting tdscanuck (Reply 1): One advantage I think Leap-X has is that that technology would scale to a new large engine a lot more easily than GTF would.
The LEAP-X is more or less a downscaled version of the GEnx...
Quoting tdscanuck (Reply 1): Quoting keesje (Thread starter):
potential to further lower fuel burn
I think this applies to the Leap-X as well, so I'm not sure why they're giving that to the GTF.
If you are already running hot that is harder to achieve as you cannot get very much hotter as you then would hurt maintenance costs and your NOx emissions go up.
aerotech777 From United States of America, joined Aug 2009, 48 posts, RR: 0 Reply 6, posted (2 years 8 months 3 weeks 5 days 7 hours ago) and read 15091 times:
Hi,
It was mentioned in the first link that the core of the Leap X will use the concepts from lower cycle wide body engines and apply them higher cycle narrow body environment. It will be nice if some engine gurus can post some details about these concepts.
In the same link it was also mentioned that the Leap X will use 2 stages high pressure turbine instead of single stage. What%u2019s the benefit of the use 2 stages HP turbine versus single stage and is this related to lower cycle versus higher cycle?
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 7, posted (2 years 8 months 3 weeks 5 days 7 hours ago) and read 15076 times:
Quoting rheinwaldner (Reply 3): Quoting tdscanuck (Reply 1):
One is going after propulsive efficiency, one after thermodynamic efficiency
How good would be a combination of both?
The benefits should be cumulative...they're basically independent technologies.
Quoting keesje (Reply 4): it seems much of the technology used by CFM and PW , doesn't exclude each other.
Agreed.
Quoting aerotech777 (Reply 6): It was mentioned in the first link that the core of the Leap X will use the concepts from lower cycle wide body engines and apply them higher cycle narrow body environment. It will be nice if some engine gurus can post some details about these concepts.
The major drive on Leap-X is to carry all the latest aerodynamic improvements (most of which have come on large engines recently) back into the smaller engines, like 3D airfoils and improved combustors, plus a higher pressure core (greater thermodynamic efficiency).
Quoting aerotech777 (Reply 6): In the same link it was also mentioned that the Leap X will use 2 stages high pressure turbine instead of single stage. What%u2019s the benefit of the use 2 stages HP turbine versus single stage and is this related to lower cycle versus higher cycle?
I don't think it's a benefit so much as a necessity. Higher thermodynamic efficiency requires a higher pressure ratio, which requires a more powerful compressor, which requires more turbine to drive the more powerful compressor. If you can't get enough power extraction from a single stage, you go to two.
I don't think these particular design features are particularly cycle related.
Lumberton From United States of America, joined Jul 2005, 4708 posts, RR: 21 Reply 9, posted (2 years 8 months 3 weeks 5 days ago) and read 14986 times:
Quoting keesje (Thread starter): The GLGroup has become a bit less predictable recently, apparently some new experts joined the group.
Quote: There is nothing worse than misinformation, so let’s clear up a few issues. For those of us who bothered to go to the Farnborough Air Show, then like me, you’ll have known that the CFM International LEAP-X engine is not a derivative engine. It is a brand new engine from the ground up.
In contrast, the Pratt & Whitney GTF engine is a derivative engine – the geared engine concept is a 1960s based design, compromised, risky and airlines have witnessed issues with reliability with such designs before. The LEAP-X engine is a new product launched in 2008 – hardly the definition of derivative when even CFM doesn’t even have a related engine to it.
If any engine is going to reach limitations first, it’s the GTF. Don’t be duped by claims that the LEAP-X engine cannot be expanded. When speaking extensively the LEAP-X program director, at the show, he informed me that the demonstrator testing had exceeded expectations, was ahead of the planned development timeline and has scope to grow in both thrust and further fuel burn reduction.
"When all is said and done, more will be said than done".
NicoEDDF From Germany, joined Jan 2008, 1051 posts, RR: 1 Reply 10, posted (2 years 8 months 3 weeks 4 days 23 hours ago) and read 14975 times:
Quoting aerotech777 (Reply 6): In the same link it was also mentioned that the Leap X will use 2 stages high pressure turbine instead of single stage. What%u2019s the benefit of the use 2 stages HP turbine versus single stage and is this related to lower cycle versus higher cycle?
Not to mention that CFMI is at the absolute limit of material technology regarding their HPT Blades on the CFM56-5A/B.
The one stage has to drive the complete HPC with the result that there is apparently so much load on the one stage, that CFMI up to now is not capable of producing a reliable blade (not even the latest and greatest P/N).
That leads to a soft time limit on the blades (12.000 cyc?!) and a lot of HPT blade separations in the past beginning from cracks at the platform.
Not to nice and airlines are not happy...
Interestingly enough, the V2500 engine has two stages, as do all bigger engines apart from Rolls Royce with their triple spool design and their single stage HPT + single stage IPT, resulting effectively in load distribution of the compressor system to two stages also.
keesje From , joined Dec 1969, posts, RR: Reply 11, posted (2 years 8 months 3 weeks 4 days 11 hours ago) and read 14857 times:
Quoting Lumberton (Reply 9): Anyway, here's the other side of the GLG debate on which of these engines looks more promising.
Doesn't sound like a very proffesional editorial. He/she attack someone;
Quoting Lumberton (Reply 9): There is nothing worse than misinformation, so let’s clear up a few issues. For those of us who bothered to go to the Farnborough Air Show, then like me, you’ll have known that the CFM International LEAP-X engine is not a derivative engine. It is a brand new engine from the ground up.
Who claimed the Leap-X is a derivative ?! Haven't seen it anywhere! Talking about misinformation, what a Don Quixote.
Then to claim the PW1000G is a derivative because gearboxes were tested in the sixties, I won't even go into that..
+ I have spoken to a saleman at an airshow so I know, too funny.
aerotech777 From United States of America, joined Aug 2009, 48 posts, RR: 0 Reply 12, posted (2 years 8 months 3 weeks 1 day 5 hours ago) and read 14621 times:
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 13, posted (2 years 8 months 3 weeks 1 day 3 hours ago) and read 14601 times:
Quoting aerotech777 (Reply 12):
I am wondering why the aft part of PW 1000G engine cowl is moving according to this link:
I don't know for sure, but I can think of two possible reasons offhand:
1) They're trying to define the optimum fan duct profile and, by putting different "rings" on the aft end of the nacelle and then sweeping them fore/aft they can track TSFC and find the optimum.
2) They're actually implemented a very simple variable area nozzle for production, which would allow them to tweak the fan stream exit velocity in flight and squeak out a small propulsive efficiency gain.
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