ferpe From France, joined Nov 2010, 1915 posts, RR: 56 Posted (1 year 10 months 1 day 3 hours ago) and read 13997 times:
Seems GE is tuning down how much they will gain with their PIPs for the 787, IIRC the PIP2 should be on spec or better with the RR T1000 within 1% spec. Seems both are now aiming for "within 1% of original spec":
Stitch From United States of America, joined Jul 2005, 26934 posts, RR: 83 Reply 1, posted (1 year 10 months 1 day 3 hours ago) and read 13879 times:
The 787-9 was launched with the expectation that the engines would be rated to 75,000 pounds, but if PiP2 is good for 3,000 pounds more than that, could the 787-9 be made available with 78,000 pound engines to improve field performance, or do they need 78,000 pounds now that MTOW is around 250t?
BoeingVista From Australia, joined Jan 2009, 1089 posts, RR: 2 Reply 2, posted (1 year 10 months 1 day 1 hour ago) and read 13272 times:
Quoting ferpe (Thread starter): Seems GE is tuning down how much they will gain with their PIPs for the 787, IIRC the PIP2 should be on spec or better with the RR T1000 within 1% spec. Seems both are now aiming for "within 1% of original spec":
Pretty sure that RR are now aiming for spec rather than 1% below.
The GEnx-1b PIP had a failure during FAA block certification that required a redesign and resulted in certification at a lower thrust level? Hadn't heard this, GE have better message control than RR.
Baroque From Australia, joined Apr 2006, 15380 posts, RR: 60 Reply 3, posted (1 year 10 months 20 hours ago) and read 12750 times:
Quoting BoeingVista (Reply 2): Pretty sure that RR are now aiming for spec rather than 1% below.
In the article there is some pretty fancy footwork with the wording in that area - looks like GE wording being shuffled a bit. And the comparisons are being made with specifications that are not stated. Two moving attempts at two targets that are unknown and possibly different! Great.
Where is the engine man with his beam of illumination?
Stitch From United States of America, joined Jul 2005, 26934 posts, RR: 83 Reply 4, posted (1 year 10 months 19 hours ago) and read 12679 times:
Rolls put the Package B LPT on a production engine (#10025) and it put SFC to within 2% of original spec.
They put all of the Package B upgrades on a demonstrator engine and it was 0.5% better than original spec - the expected result was to be within 1% of original spec.
The 787-9 engine (Trent 1000-J) would have additional (unnamed) tweaks to reduce SFC by another 2%.
GE expected PiP 1 to bring the engine to original spec, but I don't believe it did.
Baroque From Australia, joined Apr 2006, 15380 posts, RR: 60 Reply 5, posted (1 year 10 months 18 hours ago) and read 12523 times:
Quoting Stitch (Reply 4): The 787-9 engine (Trent 1000-J) would have additional (unnamed) tweaks to reduce SFC by another 2%.
GE expected PiP 1 to bring the engine to original spec, but I don't believe it did.
Engine performance seems even more a mystery than OEW is!! Do you know Stitch if that -J ver was with XWB type mods or are they yet to come? Presumably, that would be a -K??
BoeingVista From Australia, joined Jan 2009, 1089 posts, RR: 2 Reply 6, posted (1 year 10 months 17 hours ago) and read 12328 times:
Quoting Stitch (Reply 4): They put all of the Package B upgrades on a demonstrator engine and it was 0.5% better than original spec - the expected result was to be within 1% of original spec.
LOL love it, "within 1% of original spec" but actually 0.5% better than original spec... but what about this high power stall on the GEnx, any more information?
I do remember reading in one of Mr Lightsabers long explanations of engine design something about a reverse pressure gradient margin (to prevent stalls) that can be eroded to get more engine efficiency but is very hard to design in if you don't have it maybe this is what happened to the GEnx?
328JET From , joined Dec 1969, posts, RR: Reply 7, posted (1 year 10 months 16 hours ago) and read 12197 times:
Both engines are a disappointment.
Imagine that we have three years after original planned EIS of the B787 and both still have not reached the original target. Not to mention an improvement above the requested figures, as some would have expected after additional three years development time.
These two engines programs did not perform as good as, for instance, the GE90-110/115, which showed better than expected results.
Baroque From Australia, joined Apr 2006, 15380 posts, RR: 60 Reply 8, posted (1 year 10 months 16 hours ago) and read 12132 times:
Quoting BoeingVista (Reply 6): I do remember reading in one of Mr Lightsabers long explanations of engine design something about a reverse pressure gradient margin (to prevent stalls) that can be eroded to get more engine efficiency but is very hard to design in if you don't have it maybe this is what happened to the GEnx?
I don't remember that one, but in a recent thread on the TXWB he did comment on the RR report that they had found a better surge margin on the TXWB than was expected and he commented on the implications flowing (yep a pun) from that!
That thead also had bits about pulling XWB features back into the T1000. And I think the GEnx also got discussed.
But do not ask me how to find thread that are as recent as that one. About 2 or 3 months ago?????
PM From India, joined Feb 2005, 6747 posts, RR: 65 Reply 10, posted (1 year 10 months 16 hours ago) and read 11892 times:
Quoting 328JET (Reply 7): Both engines are a disappointment.
Imagine that we have three years after original planned EIS of the B787 and both still have not reached the original target. Not to mention an improvement above the requested figures, as some would have expected after additional three years development time.
These two engines programs did not perform as good as, for instance, the GE90-110/115, which showed better than expected results.
I'm not sure I agree with the conclusions you seem to have reached.
Since neither GE nor RR have quite made it (even after being gifted three more years to try), my assumption is that the target was perhaps just too ambitious.
If, on the other hand, the GE90 was set a less challenging target, then showing "better than expected results" may not mean much.
In other words, what GE and RR have achieved on the GEnx and Trent 1000 may actually be more deserving of praise than what GE did with the GE90. What you achieve does rather depend on how ambitious you were in the first place.
328JET From , joined Dec 1969, posts, RR: Reply 11, posted (1 year 10 months 16 hours ago) and read 11886 times:
Quoting thegeek (Reply 9): I think that could have something to do with the high levels of expectation put upon them. GE90B wasn't expected to be such a game changer.
For sure the expectations were high, but we are talking about additional three years time for both producers, which is 50 percent of a regular development time for a complete new engine and not some small improvements only.
NCFC99 From United Kingdom, joined May 2005, 652 posts, RR: 0 Reply 12, posted (1 year 10 months 16 hours ago) and read 11783 times:
Quoting 328JET (Reply 7): Both engines are a disappointment.
Imagine that we have three years after original planned EIS of the B787 and both still have not reached the original target. Not to mention an improvement above the requested figures, as some would have expected after additional three years development time.
Does anyone think that both companies have slowed development of the engine programs due to 3 years of lost sales. Surely both companies woulkd have had a fair bit of income from the engine sales to fund the ongoing development and improvement of the engines. Alot is said of Airbus & boeings 'lost opportunities due to delays', surely this applies to RR & GE aswell.
Does anyone know if RR & GE get anyform of compensation from Boeing and Airbus as they could have supplied working engines ontime on both the 787 & 380(albeit with a higher SFC)?
BoeingVista From Australia, joined Jan 2009, 1089 posts, RR: 2 Reply 13, posted (1 year 10 months 15 hours ago) and read 11341 times:
Quoting Baroque (Reply 8): I don't remember that one, but in a recent thread on the TXWB he did comment on the RR report that they had found a better surge margin on the TXWB than was expected and he commented on the implications flowing (yep a pun) from that!
Yep, it was in that thread (probably that post) that he made the point that it was difficult to get the surge margin back if the original design did not have it but if you had a better margin than anticipated then you could trade it for better SFC down the line.
parapente From United Kingdom, joined Mar 2006, 1320 posts, RR: 10 Reply 14, posted (1 year 10 months 14 hours ago) and read 11267 times:
What I do believe this article / thread shows is that 2 of the Worlds most advanced enginering companies are bumping their head on the ceiling of what is humanly technically possible (within the constraints of a "standard" direct drive fanned engine).
It is a phenominal achievement by both of them. They have clearly both worked their proverbials off to make it to "spec".I am sure RR is finding the same on the XWB but at least they have all the learnings of the Trent 1000 to fall back on.
Hence in many ways GTF and OR technologies. A major departure is now required to find further meaningful efficiencies I feel.
ferpe From France, joined Nov 2010, 1915 posts, RR: 56 Reply 15, posted (1 year 10 months 13 hours ago) and read 10842 times:
The article to me explains why it had gone a bit quiet around the GEnx, before the flight trials GE was very vocal about having better SFC then RR. Then since about 1 year it has been rather benign talking from both sides .
Nothing as pleasant as when others join the trouble (R perspective) .
The RR civil engine head said at Paris that both manufacturers extrapolated recent LPT gains to far for the 787 engines and made to simple and to light LPT designs. Both had to back out with redesigns.
RR have the advantage they have made one similar design since (TXWB) where they seems to have learned a lot. GE has been working on their LeapX, not quite the same class of engine but the hot section works seems interesting. They should now put all this to work on the GE90X but as Lightsaber said it needs a big redesign as it lack among other things contra-rotation.
par13del From Bahamas, joined Dec 2005, 5918 posts, RR: 8 Reply 16, posted (1 year 10 months 13 hours ago) and read 10822 times:
Quoting PM (Reply 10): Since neither GE nor RR have quite made it (even after being gifted three more years to try), my assumption is that the target was perhaps just too ambitious.
Ambitious to/by whom, the OEM and their customers or the engine companies agreeing to such targets?
Easy for us to say or even give praise for what they have achieved, but this is a economic business and not hitting targets puts them and the OEM at risk of penalities.
Baroque From Australia, joined Apr 2006, 15380 posts, RR: 60 Reply 17, posted (1 year 10 months 13 hours ago) and read 10575 times:
Quoting BoeingVista (Reply 13): Yep, it was in that thread (probably that post) that he made the point that it was difficult to get the surge margin back if the original design did not have it but if you had a better margin than anticipated then you could trade it for better SFC down the line
Yes that is close to what I remember. He was really interested in what could be done with the extra margin.
Quoting parapente (Reply 14): What I do believe this article / thread shows is that 2 of the Worlds most advanced engineering companies are bumping their head on the ceiling of what is humanly technically possible (within the constraints of a "standard" direct drive fanned engine).
You might want to wait until the authority speaks on that. I think the XWB shows there is still a way to go. Between CFD and blisks, the innards are in for a shake up, ceramics, and there seem to be more fancy things you can do with fans other than go to GTF or OR (must stop repeating myself myself!).
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 18, posted (1 year 10 months 10 hours ago) and read 9095 times:
Quoting 328JET (Reply 7): Both engines are a disappointment.
In PR terms, sure, but compared to how far they came from their predecessors they're huge achievements. The mistake was in setting the goals too far ahead, not in creating a disappointing engine. Both the Trent1000 and GEnX are huge jumps beyond their predecessors.
Quoting 328JET (Reply 7): These two engines programs did not perform as good as, for instance, the GE90-110/115, which showed better than expected results.
The GE90-110/115 was a derivative engine with a much less aggressive target...it's a lot easier to make the goal when the posts are closer.
lightsaber From United States of America, joined Jan 2005, 10874 posts, RR: 100 Reply 19, posted (1 year 10 months 10 hours ago) and read 8950 times:
I'm disapointed to see the aggresive promises of the 787 engines not being delivered. Oh well, this just implies more PIPs.
From the OP link: "The event led to the decision to certify the baseline PIP1 at 70,000 lb thrust and to redesign the high pressure turbine nozzle."
Redesign the turbine inlet nozzle blades? Talk about making tough work sound trivial...
[
Quoting Stitch (Reply 4): They put all of the Package B upgrades on a demonstrator engine and it was 0.5% better than original spec - the expected result was to be within 1% of original spec.
Sounds like RR is keeping a little margin. By only promising within 1% of original spec, RR keeps from paying penalty (usually the first 1% miss of fuel burn is at the airline's risk).
Quoting parapente (Reply 14): What I do believe this article / thread shows is that 2 of the Worlds most advanced enginering companies are bumping their head on the ceiling of what is humanly technically possible (within the constraints of a "standard" direct drive fanned engine).
Both learned the hard way how to make a better LPT. While disapointing, one learns more from mistakes...
Also, as others noted, the new CMC high turbines from GE will be a big improvement. I wonder if GE can retrofit them?
Quoting ferpe (Reply 15): The RR civil engine head said at Paris that both manufacturers extrapolated recent LPT gains to far for the 787 engines and made to simple and to light LPT designs. Both had to back out with redesigns.
A costly lesson, but both GE and RR learned valuable information on low turbines.
Quoting ferpe (Reply 15): They should now put all this to work on the GE90X but as Lightsaber said it needs a big redesign as it lack among other things contra-rotation.
I'm amused I'm already in the conversation. (Please quote me, I'm just amused.)
Quoting tdscanuck (Reply 18): In PR terms, sure, but compared to how far they came from their predecessors they're huge achievements.
But for the 787 (and 748I) to be 'game changers,' they needed to eventually beat initial promise.
Quoting Baroque (Reply 17): Between CFD and blisks, the innards are in for a shake up, ceramics, and there seem to be more fancy things you can do with fans other than go to GTF or OR (must stop repeating myself myself!).
I'm shocked more hasn't been done with BLISKs (Integrated blade rotor compressor blades) on the two 787 engines. I suspect the compressors are due for one un-announced PIP (or two...).
New thermal coatings are coming out too. Some of their capability will be required just for the 789 thrust levels. But there should be further fuel burn reduction.
Quoting tdscanuck (Reply 18): The GE90-110/115 was a derivative engine with a much less aggressive target...
Much less agressive external target. The fact that GE nailed the internal target is impressive. The low EIS fuel burn of the GE-90-115 helped make the 77W.
Stitch From United States of America, joined Jul 2005, 26934 posts, RR: 83 Reply 20, posted (1 year 10 months 10 hours ago) and read 8826 times:
Quoting ferpe (Reply 15): The RR civil engine head said at Paris that both manufacturers extrapolated recent LPT gains too far for the 787 engines and made to simple and to light LPT designs. Both had to back out with redesigns.
GE was really bit by this. They reduced the LPT blade count by 30% compared to the GE90, but this proved to be far too aggressive so PiP1 reduces the count by only 10%.
Quoting ferpe (Reply 15): RR have the advantage they have made one similar design since (TXWB) where they seems to have learned a lot.
Finally adding a second IPT stage must have made some very big improvements alone. An extra 6 inches of fan diameter helps as well.
Yet even this engine is said to be having problems at the upper-end and will require her own sub-variant to properly operate in the highest-thrust regimes.
Babybus From United Kingdom, joined Dec 2003, 3537 posts, RR: 6 Reply 21, posted (1 year 10 months 6 hours ago) and read 6850 times:
It seemed from the start that it was the engine that was the main feature of the 787 aircraft. Is it not possible for Boeing to look at weight savings, or something like that, to enhance the efficiency of the engines?
and with that..cabin crew, seats for landing please.
Stitch From United States of America, joined Jul 2005, 26934 posts, RR: 83 Reply 22, posted (1 year 10 months 5 hours ago) and read 6578 times:
Quoting Babybus (Reply 21): It seemed from the start that it was the engine that was the main feature of the 787 aircraft. Is it not possible for Boeing to look at weight savings, or something like that, to enhance the efficiency of the engines?
Engines were always going to be the largest efficiency driver on the 787, but other items like the CFRP construction and bleedless architecture all contribute their part to improve overall efficiency.
faro From Egypt, joined Aug 2007, 1456 posts, RR: 0 Reply 23, posted (1 year 10 months 5 hours ago) and read 6298 times:
Quoting Stitch (Reply 20): GE was really bit by this. They reduced the LPT blade count by 30% compared to the GE90, but this proved to be far too aggressive so PiP1 reduces the count by only 10%.
Quoting lightsaber (Reply 19): Both learned the hard way how to make a better LPT. While disapointing, one learns more from mistakes...
Funny that. Didn't PW also make the same mistake on the ill-fated PW6000? Why so much concentration on the compressor?
ferpe From France, joined Nov 2010, 1915 posts, RR: 56 Reply 24, posted (1 year 10 months 4 hours ago) and read 5924 times:
Quoting faro (Reply 23): Quoting lightsaber (Reply 19):
Both learned the hard way how to make a better LPT. While disapointing, one learns more from mistakes...
LPT = Low Pressure Turbine.
On the PW6000 Pratt simplified the Compressor to much then on the 787 engines it was the (Low) Turbines turn....
Non French in France
25 lightsaber: as noted: Pratt tried to go with a 5 stage HPC (high pressure compressor). Oops. Pratt engineers pointed out it wouldn't work and were told to go bac
26 tdscanuck: The engine was about half of the overall efficiency gain on the 787. It is possible, and they did it...that's where the other half came from. Tom.
27 thegeek: If that is the way Pratt management treats its professional employees it is unsurprising that they have seen a big decline in market share. I'd guess
28 ferpe: Reading about the failures in the 4000 and the 6000 programs it has been my reaction that there must have been something wrong in the culture inside
29 Baroque: Just a general comment, in review magazines you very seldom see comparisons of engines. You can find the entrails of the 737 v the 32x or the T7W v th
30 Stitch: There is The Engine Yearbook that gives you general specs. Not sure who publishes it, but I have found it on the Internet via a search.
31 Baroque: Thanks for the tip. http://www.ubmaviationnews.com/Publications/The-Engine-Yearbook or http://edition.pagesuite-professiona...-e2b4-4ca5-8e28-251d63a
32 lightsaber: I like who I see on the organization chart now. (Good managers who have risen up.) But there is a reason for the PW4098, PW4173 PW4170A, PW6000, PW40
33 simpilot459: They did and still are actively looking for ways to shed pounds; although they did take a weight increase for some of the features (larger windows, l
34 Baroque: Yessir, homework already done. Comprehension will take a bit longer. Bugger of a format to manage on my screen I might add. Quite clever, but tedious
36 parapente: As a geberal rule (he said!) it seems to be more and more about the engines wherever you look. In truth from the 380 through the 748/777/350/787/320&a
37 lightsaber: I recommend Google Chrome's web browser. The link seems to have HTML 5 code and most web browsers have trouble with that. Safari might work too as wi
38 Baroque: It was mostly that the as loaded size text was a bit small for my aging eyes and one dab of the enlarge was too big for the screen. Also you cannot d
39 ferpe: The document works fine in Firefox 5 (the latest), you can also download the document, go to Menu > Download a PDF wait till all pages are on scree
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Talk about making tough work sound trivial...
A costly lesson, but both GE and RR learned valuable information on low turbines.
(Please quote me, I'm just amused.) 
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