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GENx Beats Trent1000 On SFC  
User currently offlineLumberton From United States of America, joined Jul 2005, 4708 posts, RR: 20
Posted (6 years 7 months 2 days 21 hours ago) and read 13588 times:

First there was Scott Hamilton's allusion to problems that RR was having on achieving it's fuel burn targets.
http://www.leeham.net/filelib/ScottsColumn_2_121107.pdf

Quote:
(We understand fuel burn on the Trent 1000 is over target.)

Now there is a thread on another forum that features an article from Flight in which RR acknowledges the problem and GE says that "airlines are telling it the engine's sfc (i.e., GENx) is 2-3% better than the Trent 1000's". I will post a link when one becomes available.

How significant is the "2-3%"?


"When all is said and done, more will be said than done".
127 replies: All unread, showing first 25:
 
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12128 posts, RR: 52
Reply 1, posted (6 years 7 months 2 days 21 hours ago) and read 13581 times:



Quoting Lumberton (Thread starter):
How significant is the "2-3%"?

Over the 20+ year life of an airplane (40,000+ flying hours), times the number of engines (2X on the B-787), that is very significant.


User currently offlineStitch From United States of America, joined Jul 2005, 30537 posts, RR: 84
Reply 2, posted (6 years 7 months 2 days 21 hours ago) and read 13581 times:
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The article is supposedly on the Flight's website, but might be limited to subscribers at this point.

Here is an article from the 20th noting RR was working on improvements and GE claiming they were 2-3% better then the Trent - http://www.flightglobal.com/articles...ove-trent-1000-for-boeing-787.html

I know the Trent is supposed to be better on short-to-medium missions thanks to it's better climb performance, but if GE can extend their cruise advantage even more because of RR's issues, that might sway more deals to GE.

Rheinbote noted in 787 Dec 11th Update: Good Or Bad? (by A380900 Dec 3 2007 in Civil Aviation) that the 787 could be upwards of 5% off it's block fuel burn goals between the extra weight and engines - though apparently this would affect RR-powered birds more.

I wonder how this will affect the Trent XWB program? They have some time to address it, but their baseline projections may now be inaccurate.

[Edited 2007-12-24 11:34:23]

User currently offlineZvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 64
Reply 3, posted (6 years 7 months 2 days 21 hours ago) and read 13545 times:



Quoting Lumberton (Thread starter):
How significant is the "2-3%"?

For one 787 or A350, that's more than 60 gallons of fuel per hour of flight time or about 1000 gallons per day at normal utilization rates. So, per aircraft, we're talking about over 300,000 gallons of fuel per year. That's over half a million dollars per year. I'd say that transcends significant.


User currently offlineN1120A From United States of America, joined Dec 2003, 26357 posts, RR: 76
Reply 4, posted (6 years 7 months 2 days 21 hours ago) and read 13504 times:



Quoting Stitch (Reply 2):

I know the Trent is supposed to be better on short-to-medium missions thanks to it's better climb performance, but if GE can extend their cruise advantage even more because of RR's issues, that might sway more deals to GE.

As it is, the GE is the physically smaller engine. This means that it may well be better suited for smaller applications, but the Trent will scale up better.



Mangeons les French fries, mais surtout pratiquons avec fierte le French kiss
User currently offlineLumberton From United States of America, joined Jul 2005, 4708 posts, RR: 20
Reply 5, posted (6 years 7 months 2 days 21 hours ago) and read 13502 times:



Quoting Zvezda (Reply 3):
So, per aircraft, we're talking about over 300,000 gallons of fuel per year. That's over half a million dollars per year. I'd say that transcends significant.

So, is it safe to say, that this threatens the business case for the Trent 1000 if not fixed?



"When all is said and done, more will be said than done".
User currently offlineAtmx2000 From United States of America, joined Oct 2004, 4576 posts, RR: 38
Reply 6, posted (6 years 7 months 2 days 20 hours ago) and read 13479 times:



Quoting Lumberton (Reply 5):
So, is it safe to say, that this threatens the business case for the Trent 1000 if not fixed?

It means they will have to be more aggressive with pricing on engines, parts, and maintenance contracts



ConcordeBoy is a twin supremacist!! He supports quadicide!!
User currently offlineZvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 64
Reply 7, posted (6 years 7 months 2 days 20 hours ago) and read 13433 times:



Quoting Atmx2000 (Reply 6):
It means they will have to be more aggressive with pricing on engines, parts, and maintenance contracts

 checkmark  It also means that GE will not need to be so aggressive with pricing and will be able to demand a premium.


User currently offlineLumberton From United States of America, joined Jul 2005, 4708 posts, RR: 20
Reply 8, posted (6 years 7 months 2 days 20 hours ago) and read 13416 times:



Quoting Zvezda (Reply 7):
t also means that GE will not need to be so aggressive with pricing and will be able to demand a premium.

But what about the early customer, like ANA, that choose the Trent 1000? It's not like they can call GE and order up 60 engines to swap out? This can't be good for the 787 program. And surely, its potentially devastating for RR if not fixed.



"When all is said and done, more will be said than done".
User currently offlineZvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 64
Reply 9, posted (6 years 7 months 2 days 20 hours ago) and read 13367 times:



Quoting Lumberton (Reply 8):
But what about the early customer, like ANA, that choose the Trent 1000? It's not like they can call GE and order up 60 engines to swap out?

That's why they get launch customer discounts.

Quoting Lumberton (Reply 8):
This can't be good for the 787 program. And surely, its potentially devastating for RR if not fixed.

RR will survive this whether they fix it or not.


User currently offlineAtmx2000 From United States of America, joined Oct 2004, 4576 posts, RR: 38
Reply 10, posted (6 years 7 months 2 days 20 hours ago) and read 13366 times:



Quoting Lumberton (Reply 8):
But what about the early customer, like ANA, that choose the Trent 1000? It's not like they can call GE and order up 60 engines to swap out? This can't be good for the 787 program. And surely, its potentially devastating for RR if not fixed.

It would depend on what type of guarantees they got in their contract. Also ANA would have gotten a good price being a sought after launch customer with a large order.

And don't forget that ANA is buying a lot of 787-3's on which the RR engine has been expected to be the better performer.



ConcordeBoy is a twin supremacist!! He supports quadicide!!
User currently offlineKhobar From United States of America, joined Mar 2006, 2379 posts, RR: 4
Reply 11, posted (6 years 7 months 2 days 19 hours ago) and read 13190 times:



Quoting Lumberton (Reply 8):
But what about the early customer, like ANA, that choose the Trent 1000? It's not like they can call GE and order up 60 engines to swap out? This can't be good for the 787 program. And surely, its potentially devastating for RR if not fixed.

This was one of the "unique" features of the 787 - the engines can be swapped. It might take longer than the original 24 hours, but they have a common engine interface. Thus it is even possible to run RR on one side and GE on the other.


User currently offlineAlessandro From , joined Dec 1969, posts, RR:
Reply 12, posted (6 years 7 months 2 days 19 hours ago) and read 13158 times:

Any difference in weight and expected lifetime and need of maintenance?

User currently offlineLumberton From United States of America, joined Jul 2005, 4708 posts, RR: 20
Reply 13, posted (6 years 7 months 2 days 18 hours ago) and read 13097 times:



Quoting Khobar (Reply 11):
This was one of the "unique" features of the 787 - the engines can be swapped.

But what of the availability of engine production slots? Hopefully, RR will fix this in short order, but if not and an early customer wants to swap out, they'll have to get in line until GE ramps up.



"When all is said and done, more will be said than done".
User currently offlineTrex8 From United States of America, joined Nov 2002, 4681 posts, RR: 14
Reply 14, posted (6 years 7 months 2 days 18 hours ago) and read 13078 times:
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wasn't one of the advantages of the RR 3 shaft design that especially with a non bleed system which needs to "tap" power off a shaft, its more efficient for the RR design as one shaft is rotating at a more optimal speed. while the SFC may be greater, this may help make up some of the difference in real life operations..

User currently offlineClipper136 From United States of America, joined Mar 2006, 316 posts, RR: 1
Reply 15, posted (6 years 7 months 2 days 16 hours ago) and read 12859 times:

Slow down fellas,

Why not wait until there is an actual problem, and not

Quoting Lumberton (Thread starter):
allusion to problems

before you start banging the drum.

There is no indication that this is true. There has been no confirmation by RR or Boeing that I can find.
I would not take GE's figures as the Gospel. They are trying to sell engines.


User currently offlineLumberton From United States of America, joined Jul 2005, 4708 posts, RR: 20
Reply 16, posted (6 years 7 months 2 days 16 hours ago) and read 12829 times:



Quoting Clipper136 (Reply 15):
before you start banging the drum.

Read the first few posts again. Its an article in the subscriber version of Flight; will post a link when available.



"When all is said and done, more will be said than done".
User currently offlineKhobar From United States of America, joined Mar 2006, 2379 posts, RR: 4
Reply 17, posted (6 years 7 months 2 days 16 hours ago) and read 12796 times:



Quoting Lumberton (Reply 13):
But what of the availability of engine production slots? Hopefully, RR will fix this in short order, but if not and an early customer wants to swap out, they'll have to get in line until GE ramps up.

Ah, that might be a problem, but I imagine some kind of deal could be worked out. We know or can guess what aircraft slots are like, but what are engine slots like to get? Is GE currently working at capacity? I don't have any idea.


User currently offlineClipper136 From United States of America, joined Mar 2006, 316 posts, RR: 1
Reply 18, posted (6 years 7 months 2 days 16 hours ago) and read 12750 times:



Quoting Lumberton (Reply 16):
Its an article in the subscriber version of Flight

According to the article RR confirmed that they are working on continuous improvements according to their development plan. The article points to "reports" that the engine is not meeting targets. It does not say where these reports are from. The specific figures quoted are from GE.

As new development engines, both manufactures will be working on development enhancements through EIS and beyond.


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 19, posted (6 years 7 months 2 days 15 hours ago) and read 12695 times:



Quoting Lumberton (Thread starter):
Now there is a thread on another forum that features an article from Flight in which RR acknowledges the problem and GE says that "airlines are telling it the engine's sfc (i.e., GENx) is 2-3% better than the Trent 1000's".

That really shouldn't surprise anybody...RR usually has better durability and less weight at the expense of some SFC. That comes partly from design philosophy and partly from using a 3-spool architecture.

Quoting Lumberton (Reply 8):

But what about the early customer, like ANA, that choose the Trent 1000? It's not like they can call GE and order up 60 engines to swap out?

They could swap if they wanted to, as noted in prior posts. However, unless RR dropped below their performance guarantees (very unlikely, given that the RR has been certified for months) ANA would have no basis to get out of the contract without penalties.

Quoting Lumberton (Reply 8):
This can't be good for the 787 program.

Why? It doesn't say anything about the absolute performance of either engine, just that one is a little better at SFC than the other, which is completely normal in a program with multiple engine types.

Quoting Khobar (Reply 11):
the engines can be swapped. It might take longer than the original 24 hours, but they have a common engine interface. Thus it is even possible to run RR on one side and GE on the other.

Although it may be technically possible, I doubt the FMC would be very happy about it and the airplane is certainly not certified for it.

Quoting Alessandro (Reply 12):
Any difference in weight and expected lifetime and need of maintenance?

RR tends to be lighter (shorter/stiffer frame and less complex stator structure thanks to 3 spools) and more durable than GE. In return, GE tends to have better SFC.

Tom.


User currently offlineMolykote From United States of America, joined Aug 2005, 1340 posts, RR: 29
Reply 20, posted (6 years 7 months 2 days 13 hours ago) and read 12198 times:



Quoting Lumberton (Thread starter):
How significant is the "2-3%"?

The PW4098 missed its fuel burn target by 3-4% (I believe).

On the longer range 777 missions that this engine was designed for this problem was amplified by the inherent need to "carry fuel to carry fuel" and the PW4098 basically vanished from the market. The only upside was that this disaster did facilitate the arrival of a PW4098 display engine at the Dulles Air and Space Museum ahead of "schedule". I like many aspects of Pratt designs but in this case I must call a spade a spade.

I am not directly implying that the Trent 1000 will suffer a similar fate as I simply don't know. Some other RR applications (i.e. 757-200) offer extended life and durability in exchange for a fuel burn penalty compared to the competition. However, I would imagine that the longer haul, lower cycle 788/789 applications (which are easier on engines on a per hour basis) would somewhat diminish any life/durability benefit that (may) be in RR's favor - especially in the context of a fleet hour agreement.

I know very little about the GEnx and Trent 1000 so consider the preceeding paragraph speculation.



Speedtape - The asprin of aviation!
User currently offlineKhobar From United States of America, joined Mar 2006, 2379 posts, RR: 4
Reply 21, posted (6 years 7 months 2 days 12 hours ago) and read 11867 times:



Quoting Tdscanuck (Reply 19):
Although it may be technically possible, I doubt the FMC would be very happy about it and the airplane is certainly not certified for it.

Well, I can't see a situation where a plane would have a GE on one wing and a RR on the other, except maybe to fly out of a war zone or something drastic like that (or perhaps another take on "The Flight of the Phoenix"), and because of that I can see why the money wouldn't be paid for certification, but the engines do use a common interface, and the FMC issue would be purely software in nature. As a crude analogy, I can run two different brands of HD on my computer each with their own timing and other characteristics, and the computer is perfectly happy, automagically identifying the hardware on a piece by piece basis. However, I have no idea how "smart" an FMC might be - does it only know "engine", "GE", "GE90", "GE90-115", etc?

I'm not claiming the interchangeability is the same as the F135/F136, but it's not like the old days either.


User currently offlineMax Q From United States of America, joined May 2001, 4359 posts, RR: 19
Reply 22, posted (6 years 7 months 2 days 11 hours ago) and read 11625 times:

Interesting, is there an implication the RR engine on the 757 has a worse SFC than the PW ?


The best contribution to safety is a competent Pilot.
User currently offlineLightsaber From United States of America, joined Jan 2005, 12860 posts, RR: 100
Reply 23, posted (6 years 7 months 2 days 10 hours ago) and read 11516 times:
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Quoting Lumberton (Thread starter):

Now there is a thread on another forum that features an article from Flight in which RR acknowledges the problem and GE says that "airlines are telling it the engine's sfc (i.e., GENx) is 2-3% better than the Trent 1000's". I will post a link when one becomes available.

How significant is the "2-3%"?

My industry sources collaborate the 2% number. (Note, they're going to de-emphasize the difference due to their nature.)

However, we must be clear that we're talking cruise fuel burn
The RR has a slight climb fuel burn advantage. However, due to the GEnX advantage, GE burns less fuel from 2000nm on.

Quoting N1120A (Reply 4):
As it is, the GE is the physically smaller engine.

The core is pushed a little harder. But GE can grow to the 789 requirements. Beyond that? GE is working on new turbine materials that *might* be ready in time for a larger 787-10.

Quoting Lumberton (Reply 8):
It's not like they can call GE and order up 60 engines to swap out?

Unlikely for $500,000/year. An engine and nacelle swap will cost more than most customers will bear.

Quoting Molykote (Reply 20):

The PW4098 missed its fuel burn target by 3-4% (I believe).

Yes a 4% miss. It made the PW4090/PW4098 payload at longer rangers identical. So why buy the added fuel?

RR must fix the difference if it is to regain sales momentum. Can they do it? I believe so. I've seen some RR compressor proposals that will help cut fuel burn another 1%. Another 1% could probably be gained in HPT tuning. The last 1%? That's the challenge. So hire more R&D engineers.  Wink

Quoting Tdscanuck (Reply 19):
That really shouldn't surprise anybody...RR usually has better durability and less weight at the expense of some SFC. That comes partly from design philosophy and partly from using a 3-spool architecture.

Partially. RR did a better job optimizing for climb. The rest is not being as aggressive as GE. The harder you push a core, the lower the fuel burn. With oil stuck above $90/bbl, the market preference is drifting toward minimal fuel burn.

I have confidence in RR, but its never good to give the competition a leg up. It will cost RR hundreds of millions to develop everything to cut the fuel burn. This won't be a minor effort. Worth it? I believe so.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineIwok From Sweden, joined Jan 2005, 1108 posts, RR: 0
Reply 24, posted (6 years 7 months 2 days 9 hours ago) and read 11277 times:



Quoting Lumberton (Thread starter):
Now there is a thread on another forum that features an article from Flight in which RR acknowledges the problem and GE says that "airlines are telling it the engine's sfc (i.e., GENx) is 2-3% better than the Trent 1000's". I will post a link when one becomes available.

So what are the implications for the Trent XWB: it seems as though the advantage over the GE-90 powered 77L/W may not be as high as claimed unless GE is swayed to join on with the XWB??  stirthepot 

iwok


25 Cobra27 : Not really if you ask me.
26 Zvezda : I predict GE will be persuaded when the A350-1000 starts outselling the 777-300ER.
27 Baroque : "GE says the GEnx's fuel consumption is on target and that airlines are telling it the engine's sfc is 2-3% better than the Trent 1000's. Engine cert
28 BlueShamu330s : RR's response in the article is: "Performance targets are worked throughout all developmental programmes. We laid out a continuos improvement programm
29 Flipdewaf : I have a feeling that RR will sort this to some extent but the fuel burn in cruise will never be as good as the GE. I think if airlines arent seen to
30 Baroque : QF has taken the GEs but even allowing for some long flights to the US, the average for them 787 stage for them looks likely to be less than 5000 km
31 Terry : I am sure there's a lot of speculation, but am worried as a RR fan. PM, where are you?!
32 Lumberton : I don't know the answer, but all this discussion highlights the benefits of competition and having two engine choices for the 787. One engine offerin
33 Norcal773 : This is the first I've heard of this. I bought a 787 book in SIN the other day and it doesn't mention this. You can swap engines in 24 hours but not
34 Flipdewaf : Knowing that the 3spoolers of RR can be easily optimised for different operations and I have heard from people in the know at RR that it was a clear c
35 KC135TopBoom : It will not effect the B-787 at all. The airlines still have a choice as to engines.
36 Revelation : LOL - how many times in my career have I heard such things... "It's just a simple matter of software" has become a standing joke in the industry. "Th
37 Post contains images A350 : Since the Trents enter service earlier than the GeNX engines the only intersting question is their performance when the GeNX comes in service. It's ir
38 Lumberton : Not sure about this; salespersons will capitalize on a sfc advantage.
39 Iwok : LOL aint't that the truth. If you are an engineering manager and you hear "its only a minor software tweak" put on your thigh high boots and wade in
40 Zvezda : Could a test pilot get a 787 with mismatched engines to fly? Most likely. Would it ever be certified for commercial ops? Absolutely not.
41 Lemurs : I'm sure they're getting feedback from their customers who are currently engaged in negotiations with both companies. Customers get access to quite a
42 Post contains images SailorOrion : Let's hope it's really the engine that was detected and not some passenger's notebook with Bluetooth on SailorOrion
43 Lumberton : With the exception of the 787-3 flights operated by Japanese carriers, aren't most flight profiles for this class of aircraft a lot longer than 2000n
44 Mir : Very significant, but I wouldn't put too much stock in these sort of numbers before the plane has even flown. I'm not even sure how the airlines woul
45 Lumberton : Other than the comparing what the manufacturers are telling them, I don't know either.
46 Khobar : And yet, in this case, it is just a software issue. Microsoft...
47 Fruitbat : The Trent XWB is a number of years behind the Trent 1000 and projections for that engine will incorporate learning from Trent 500/900/1000 in service
48 Post contains images Atmx2000 : These engines have been powered on, had ground tests and have been flying about on test bed aircraft, correct? You should be able to determine a grea
49 Post contains images Lightsaber : Originally, RR had targeted a break even point of 5000nm. Why? Costs were equivalent for the fleet (except for a few operators, most will use 788's o
50 Bohlman : Most definitely. Let's say 2% 10,000lbs an hour plus an average of 30 frames over a 20 year period at an average of $2.50 a gallon over those years e
51 Khobar : Wow, went from a software issue to a minor software tweak and the possibility of bluetooth thrown in for good measure. One might get the impression s
52 Atmx2000 : But they are pursuing other issues as well, like the durability improvements, which presumably extend lifetime of the engine parts and reduce mainten
53 Fruitbat : No, I'm not. But neither am I expecting either two engines of the same generation powering the same airframe to have significantly different overall
54 Tdscanuck : The FMC knows exactly what engine it installed, down to the serial number. However, it is not just a software issue and it's not like running to diff
55 Zvezda : Tdscanuck, would you agree that it's something that, if ever tried, would be flown by test pilots, not line pilots, and that it would absolutely neve
56 XT6Wagon : The quotes that I have seen is that as far as the aircraft is concerned the engine on the wing is an engine. Doesn't matter what it is since each eng
57 Tdscanuck : Absolutely. If there were some business case for it I think it could probably be certified (with appropriate analysis, simulation, and flight testing
58 Zvezda : Right, it's not that it couldn't be certified. It's that it never would be certified because there is no business case that could justify the certifi
59 Gigneil : I concur with Baroque's earlier post. No airline anywhere can tell GE or RR anything about either engine at this time. NS
60 Tdscanuck : That's not exactly right. The problem is that when the airplane asks for "X", "X" depends on what engine is out there. The airplane typically shoots
61 Mir : The airlines aren't going to be using these engines in a test cell or on a test aircraft. When the 787 actually starts flying and can get some real d
62 Thegeek : Isn't this something that the B787 program with it's common electrical interface was supposed to resolve? Assuming that there isn't some software pro
63 Post contains images Lightsaber : You are, of course correct. But as a fluids guy... I focus on my biases. Lightsaber
64 Atmx2000 : It happened on the 777, with RR having the upper hand on the original models.
65 Tdscanuck : Although it's true that they don't have any on-787 data, that really doesn't factor into SFC much at all. The engine can't tell what it's connected t
66 Bongodog1964 : Quoting Baroque (Reply 27): That is amazing. I guess it must be done by modelling, or intuition, but certainly it is remarkable that airlines are able
67 Post contains links Baroque : And no doubt these numbers are changing over time. There is no way of knowing that the numbers quoted are for the same time, or even on exactly compa
69 Lumberton : Perhaps we'll have an outright denial by RR soon, or at least a link to the Flight article? Presumably, Flight Global's standards for accuracy are a
70 Post contains images Astuteman : I think the key issues here are:- a) Is the Trent SFC (reputedly) 2% worse than the GEnx, but making spec numbers? Or not? b) What will be the perfor
71 Post contains images Revelation : Hey, it's just the developers saying it's sooooo hard. Wait till the testers start talking about their "test matrix". Time to take out the check book
72 Post contains images Lightsaber : Or by directly comparing the flight test numbers. Both engines have flown. Both engines have extensive ground test data including ground test data at
73 Revelation : And I've read (and think you've written) how the GE90 wasn't a great engine till the enhancements for the GE90-115B were introduced and retrofitted t
74 Atmx2000 : Were they retrofitted? Were there a lot of GE90 enginessold afterwards?
75 RayChuang : If I remember correctly, the GENx engine is very close to a "clean sheet" engine in much of its engine core design, while the Trent 1000 is essentiall
76 Justloveplanes : This doesn't sound difficult as was pointed out earlier, a simple calculation in the engine controller or flight control system should be able to add
77 Post contains images Lightsaber : Yep. However here its only purely pursuing fuel burn. (Ok, probably some reduction in maintenance costs too, but RR is really only playing catch up o
78 Bongodog1964 : Whats the difference between the "spec sheets" and the "flight test numbers" ? Surely they with both engines having flown they are one and the same.
79 Tdscanuck : The part that I guess I'm failing to get across is that it's very easy to underestimate how tightly integrated modern avionics are. It's is not as si
80 Lightsaber : Spec sheets are a very truncated list of engine performance. During the flight testing, the engines perform under a huge variety of operating conditi
81 Trex8 : during these flight tests are the engines also providing bleedless power to some system on the test aircraft?
82 Justloveplanes : Your point is well taken, so the question to ask is did Boeing put enough into its engine commonality spec that the engines are as integration swapab
83 Lightsaber : Usually there is a simulated bleed test. Or in the case of the Trent 1000/GEnX electrical power take off. Lightsaber
84 Post contains links Revelation : Some interesting quotes: http://www.geae.com/aboutgeae/presscenter/genx/genx_20070222.html http://www.geaviation.com/aboutgeae/...resscenter/genx/gen
85 F14D4ever : The interchangeability spec was never intended to allow mixed installation. Its intent was to allow two GE engines to be swapped for two RR engines.
86 SailorOrion : Responding to the secondary topic on this thread, I think it all comes down to economy. Would the economical benefits outweigh the certification cost
87 Justloveplanes : From your description, this two different engines does not even sound feasible for, say, an emergency ferry somewhere. Correct?
88 Stitch : In the time it would take to pull a bum Trent and secure, install and configure a good GEnx - or vice-versa - you would likely be able to just air-sh
89 F14D4ever : Correct, not only because of the pragmatic consideration explained by Stitch, and because of aero and lapse considerations, but because the flight ma
90 OldAeroGuy : A fuel burn tolerance of 1% is pretty tight. Both OEM's find that the fuel burn of the same airframe/engine combination coming down the assembly line
91 Zvezda : The only scenario where I can imagine someone trying it would be when the USAF is on the way to bomb the airport to Gotterdammerung and that's the la
92 RJ111 : The RB211-535 burnt quite a bit more than the PW2000 and we know how that turned out. Lets see how they perform in service. The interesting thing is t
93 Lightsaber : Yes. But customers now expect that. Some airframes still have that variation. Others, like the 777, have less variation. e.g, its a known weakness of
94 Thegeek : But that was in days when fuel wasn't such a major cost to airlines. These days it's very important, but that's only been true in the last few years,
95 Art : So SQ's A380 figures should move up/down a little when they start measuring fuel burn on 3 frames rather than just the 1?
96 Post contains images Astuteman : In fairness, Airbus have probably had a larger than typical sample to select from on the A380, given the large number of miles flown, and number of a
97 Scbriml : I just can't see airlines doing this, even leasing companies seems a bit of a stretch to me.
98 Art : If oil doubles in price in real terms by 2025 and significantly better engines are available, why not update your 10-15 year old frame? I guess Boein
99 Post contains images Baroque : Sounds a bit more like the reality that I thought was out there. With the A380, due to circumstances that presumably Airbus are not entirely happy ab
100 Zvezda : It was the demands of the leasing companies that drove the decision for a common engine interface. If you've already got a CFRP airframe, then engine
101 Post contains links Scbriml : Allegedly. Though I've not seen any documented evidence of it. I still don't see it happening very often and certainly not for an entire fleet (which
102 Stitch : The banks might have driven it, since Boeing worked with them to ensure the 787 was "financier friendly". If a bank re-possesses a 787 with GEnx engin
103 OldAeroGuy : Agree for the RR powered A380's. Engine Alliance A380's still probably need some data base expansion. With regard to SQ's single RR A380, it could be
104 Post contains images Rheinbote : More so once they have met their own guarantees Thank you, Lightsaber. According to 787 specs, the book difference between GEnx and Trent1000 should
105 Post contains images Fruitbat : RR and GE know their current numbers; Boeing know the current numbers. What do the airlines know? Whatever Boeing tell them. I don't know what happen
106 Tdscanuck : As noted, intermix was never a requirement of the interchangeability spec. As a result, there is no provision or expectation for it in any of the oth
107 Post contains images Baroque : If RR is 2% off and GE is off too, how does GE get to be 2 to 3% "better"? I know percentages are odd things, but not that odd surely??
108 Rheinbote : What's so difficult? If GE was off by, say, 1% and Rolls is 2-3% worse than that, then RR would be off by 3-4%, no?
109 Post contains images Baroque : Except that La's figure is 2% for RR. But I begin to wonder if the La 2% was for the difference between the RR and GE engines, or was a number for ho
110 Rheinbote : Did you read the first post? "...an article from Flight in which RR acknowledges the problem and GE says that "airlines are telling it the engine's sf
111 Post contains images PM : I've been out of the loop for a while (flying around on GE engines ) and, in any case, I'm in no position to comment on sfc or anything technical. How
112 Baroque : I did. If GE is 2-3% better than RR, and GE is 1% off itself then as you say in 108 RR is off 3-4%, but that does not agree with the La figure of 2%
113 Post contains images PM : Too soon to panic!
114 Post contains images Fruitbat : By spec numbers I meant all engine metrics, not just SFC. RR acknowledge a Trent 1000 SFC issue vs GEnX at EIS but expect to rectify it asap. ** Adop
115 A342 : This doesn't make sense. If anything, the airlines would tell GE that the RR engine is better.
116 Jetlife2 : I'm not going to comment on the specifics here but you may be interested in some general background. I guess you are implying that in a campaign the a
117 Post contains images PM : @ Jetlife2 Good post. Very balanced. Thanks!
118 Post contains images Baroque : Ahhh, or Ah so as PM might have to say. Wonder when ASAP will be given the rubber time that seems to be swathing new projects these days. Again, RR m
119 A342 : Thanks for the post. You make some very interesting and valid points. But in this case, I still think that no airline has told GE "your product is so
120 Post contains images Stitch : Why not? "Dear GE, your engine is so much better then RR...that RR is offering me a 5% lower price. Will you match it?"
121 Post contains links Lumberton : Here's the link to the story on Flight Global: http://www.flightglobal.com/articles...ove-trent-1000-for-boeing-787.html
122 Abba : Wouldn't that also depend on a mission profile? No doubt GE would not do their comparison on a profile that wasn't in their favour...
123 Art : From Flight: "GE says the GEnx's fuel consumption is on target and that airlines are telling it the engine's sfc is 2-3% better than the Trent 1000's.
124 Abba : Indeed so - but that doesn't change my point as there might be a good deal of different situations to choose from. Including situations where custome
125 RJ111 : SFC has nothing really to do with the aircraft or the route. It's the amount of fuel needed to sustain a certain thrust. The amount of thrust an airc
126 Thegeek : Technically, but what SFC? Cruise SFC? Static SFC? Climb SFC? It is possible that the Trents have an advantage at sea level or climb and the GEnx's h
127 Baroque : Indeed, which of those? Or is it overall consumption over a given mission, and if that, which mission? GE are not going to emphasise either a figure
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