KL911 From Hungary, joined Jul 2003, 4439 posts, RR: 17 Reply 1, posted (2 years 4 months 2 weeks 2 days 22 hours ago) and read 14540 times:
Well, that's a nice start for the year 2010! It's just a small step, but I can see them go ahead with the program. What will Boeings answer be? A 737NG-NG?
OyKIE From Norway, joined Jan 2006, 2494 posts, RR: 3 Reply 3, posted (2 years 4 months 2 weeks 2 days 14 hours ago) and read 13977 times:
Quoting KL911 (Reply 1): Well, that's a nice start for the year 2010! It's just a small step, but I can see them go ahead with the program.
i believe this is the way to go. Airbus is too tied up to the A400 and A350 now, but to make the the plane competitive against the Cseries and C919 this might be the best option for now. I wonder how much they can improve the efficiency of the airframe in terms upgrading more systems inside the plane?
Quoting BlueSky1976 (Reply 2): More than likely a 737 with Leap-X instead of CFMs.
Although personally, I'd much rather like to see an all-new airframe, the 787 "Mini-Me"
I believe Boeing will honor their agreement with the CFM partners and go ahead with the Leap-X. I would also like for Boeing to go for a 787 "mini-me" project. But how much resources do Boeing have at the moment? They have the 787 and 747-8, and have to make a desicion about what they will do with the 777. I believe we will see either:
A brand new 737 replacement with an updated 777NG or super stretched 787 with a new wing.
OR
A modified 737NNG with a plastic 777.
Third option
A modified 737 as well as a an updated 777NG.
Dream no small dream; it lacks magic. Dream large, then go make that dream real - Donald Douglas
OyKIE From Norway, joined Jan 2006, 2494 posts, RR: 3 Reply 5, posted (2 years 4 months 2 weeks 2 days 13 hours ago) and read 13715 times:
Quoting Burkhard (Reply 4): And I expect they go the third option. Lowest risk, lowest cost, safe profit.
If the economics can be competitive against the Cseries and A350 I believe you are right. But it will not be able to offe the same pressure and humidity as the A350 and 787. I wonder how that will affect Boeings decision?
Dream no small dream; it lacks magic. Dream large, then go make that dream real - Donald Douglas
Scbriml From United Kingdom, joined Jul 2003, 10517 posts, RR: 51 Reply 6, posted (2 years 4 months 2 weeks 2 days 13 hours ago) and read 13610 times:
I'd be very surprised if Airbus dealt only with PW. Leahy said that they would only look at a GTF if it came from IAE (presumably for contractual reasons).
You're only supposed to blow the bloody doors off!
Parapente From United Kingdom, joined Mar 2006, 1209 posts, RR: 10 Reply 8, posted (2 years 4 months 2 weeks 2 days 12 hours ago) and read 13466 times:
Just a thought.
We all accept that Boeings response will be to use the LEAP-X engine.They (Cfm) have stated that it will be ready to go on the 919 wing for aircraft certification work in 2014.As such it could be on the wing of an already certified aircraft (737) to the same timetable - Say EIS 2015.
I note that Ryanair's publicised tactic the last time they "raped" Boeing was to spot a production gap 3/4 years into the future and offer to fill it in one go.(It also helped that Airbus pitched as well though).This time it was (publicised) as a 2014/16 timeframe.But this time Boeing would not play ball.
Is this the reason? They know they will be able to very happily fill these slots as they will be offering a "new" aircraft with 16% (Cfm) low fuel consumption?
Keesje From , joined Dec 1969, posts, RR: Reply 9, posted (2 years 4 months 2 weeks 2 days 12 hours ago) and read 13389 times:
Quoting Parapente (Reply 8): We all accept that Boeings response will be to use the LEAP-X engine
I wonder if it would be a compromised LEAPX / GTF fitted to the 737. The CFM56 has Bypass ratio of about 5.3, versus e.g. CSeries will have a BPR twice as high.
The A320 also seems to have room for higher BPR's. Airbus will have to redesign the wing pylon. But not as dramatic as Boeing did for the 737 in the eighties.
Maybe Boeing will end up joining up with Embraer that seems to have bigger ambitions. Sharing risk's / investments, engineering resources, same time zones, cheaper but skilled labor..
Tom355uk From United Kingdom, joined Nov 2007, 246 posts, RR: 3 Reply 10, posted (2 years 4 months 2 weeks 2 days 11 hours ago) and read 13094 times:
True, the A320 does have greater ground clearance than the 737, but the NG models have longer gear legs than the Classic 734 pictured so the Nacelles are less 'hamsterized'. I believe the Classics' ground clearance is ~45cm - feel free to correct me if i'm wrong!
Manfredj From United States of America, joined Mar 2007, 1132 posts, RR: 0 Reply 11, posted (2 years 4 months 2 weeks 2 days 9 hours ago) and read 12347 times:
I've always wondered why they haven't just given the 737 a new undercarriage to cope with the engine issues. I know the NG's sat a bit higher but why not raise it even more. Won't this open up more possibilites engine wise?
Tom355uk From United Kingdom, joined Nov 2007, 246 posts, RR: 3 Reply 12, posted (2 years 4 months 2 weeks 2 days 9 hours ago) and read 12249 times:
[quote=Manfredj,reply=11]
Again, feel free to correct me if i'm wrong, but if they extended the gear legs on the 737NG anymore, I don't think they would be able to fold into their existing stowed position (they would clash) and so an expensive and costly redesign involving either rearward retracting gear or some form of staggered retract (one in front of the other).
Stitch From United States of America, joined Jul 2005, 23614 posts, RR: 79 Reply 13, posted (2 years 4 months 2 weeks 2 days 9 hours ago) and read 12084 times:
LEAP-X has to have been designed with the 737NG in mind, so I can't see it being significantly "compromised". Boeing and CFM have been flight-testing a new nacelle style on a 737-900ER which will be used with the LEAP-X engine, after all. And Pratt swears they can get a GTF with an 80" fan on the 737NG.
Both Pratt and CFM want their engine to work with new-builds as well as future refits of in-service aircraft so it is in their financial interests to have Boeing stay with the 737NG and Airbus stay with the A320 so they can get a decade of new sales to create a market for decades of re-engine deals.
Aerdingus From Ireland, joined Dec 2006, 2245 posts, RR: 20 Reply 14, posted (2 years 4 months 2 weeks 2 days 8 hours ago) and read 11230 times:
I think it's crazy that the 737 has gone so long with the same engine. But whatever works. Will be interesting to see the new engines for the A320. With more options available on the Airbus, are 737s, even NGS, in danger? Hate to sound so dramatic, but just wondering. Then again, the 737 has suffered much adversity to be king of the narrow bodies.
BA EI FH FR TS ZB 3K 5G A306 A313 A320 A321 A333 B738 B744 B772 BCN CRL DUB FRA FUE GRO HEL HER HKG JFK LHR LIN MAD MXP
0NEWAIR0 From United States of America, joined May 2007, 762 posts, RR: 0 Reply 15, posted (2 years 4 months 2 weeks 2 days 7 hours ago) and read 11143 times:
Quoting Tom355uk (Reply 10): True, the A320 does have greater ground clearance than the 737, but the NG models have longer gear legs than the Classic 734 pictured so the Nacelles are less 'hamsterized'.
Cba From United States of America, joined Jul 2000, 4530 posts, RR: 4 Reply 16, posted (2 years 4 months 2 weeks 2 days 7 hours ago) and read 10769 times:
Makes sense... the A320 family is still a relatively young design in terms of narrow bodies.
From Boeing's stand point, it makes more sense to come out with a totally new product, rather than producing a fourth generation of the 737. Boeing's product will likely be more of a cross between the 737NG and the 757... covering the 150-200 seat market.
Aircraft such as the A319 and 73G are great for long and thin routes (CO's EWR-SNA comes to mind), however they are too heavy for shorter flights. Their trip costs almost equals that of a 738/A320. Notice how Boeing's best 737s of late have been the 738 and 739ER models.
Stitch From United States of America, joined Jul 2005, 23614 posts, RR: 79 Reply 17, posted (2 years 4 months 2 weeks 2 days 7 hours ago) and read 10771 times:
Quoting Aerdingus (Reply 14): I think it's crazy that the 737 has gone so long with the same engine. But whatever works.
And that is the key, isn't it?
As "superior" as the A320 is said to be by the Airbus Aficionados, it has not been able to break away from the 737NG in terms of orders. Boeing, whether by plan or sheer blind luck, successfully developed the third generation 737 into a serious competitor to the A320. And part of that success has to be extended to CFM and their CFM56-7 series of engines, so as they improve that family with LEAP-X, it should only help the 737NG...
Tdscanuck From Canada, joined Jan 2006, 11034 posts, RR: 72 Reply 19, posted (2 years 4 months 2 weeks 2 days ago) and read 8534 times:
Quoting Keesje (Reply 9): wonder if it would be a compromised LEAPX / GTF fitted to the 737. The CFM56 has Bypass ratio of about 5.3, versus e.g. CSeries will have a BPR twice as high.
The BPR on a GTF gets bigger primarily by having a smaller core, not a bigger fan. The fan is somewhat bigger, but the big gain is that you can spin that fan with a smaller core.
Quoting Manfredj (Reply 11): I've always wondered why they haven't just given the 737 a new undercarriage to cope with the engine issues.
Any longer, and they'd hit in the middle. The only way to go longer now is, as Tom355uk said, retractable oleos, stagger, or moving the mounting point outboard (major structural change).
Quoting Aerdingus (Reply 14): I think it's crazy that the 737 has gone so long with the same engine.
The 737 has had its engine for less time than the A320 has had it's engine...why is it crazy?
Aeolus From Mexico, joined Aug 2007, 370 posts, RR: 0 Reply 20, posted (2 years 4 months 2 weeks 1 day 23 hours ago) and read 8431 times:
What improvements to the fuel consumption (efficiency) and range would the re-engining process make?
I'm hoping it to improve considerably, but that's just my wish. I'd like to see the new wingtips being put into use soon if they are approved by the corresponding authorities. That'd be so sexy and nice !!!
Golli From Iceland, joined May 2007, 149 posts, RR: 0 Reply 22, posted (2 years 4 months 2 weeks 1 day 21 hours ago) and read 8287 times:
Quoting Tdscanuck (Reply 21): A whole new engine can, based on precedent, get about 5-10% fuel burn improvement. For equal fuel load, that should give you about 6-11% more range
Astuteman From United Kingdom, joined Jan 2005, 8610 posts, RR: 96 Reply 23, posted (2 years 4 months 2 weeks 1 day 16 hours ago) and read 8072 times:
Quoting Tdscanuck (Reply 19): The BPR on a GTF gets bigger primarily by having a smaller core, not a bigger fan. The fan is somewhat bigger, but the big gain is that you can spin that fan with a smaller core.
This begs the question as to why CFM can get up to 27 000lb thrust out of the CFM56-7B at only 61" fan diameter, whereas the PW1000G with its 73" fan only makes 23 000lb?
I agree that the gearbox helps reduce the core size and improve the bypass ratio, but as far as I can see, most of the improvement will come from a bigger fan, certainly when comparing a 5:1 ratio existing engine to a 10:1 ratio GTF. I'd defer to the engine specialists of course..
I would guess that applying GTF technology to a 9:1/10:1 ratio engine like the GEnx migt indeed yield an incremental improvement in BPR without a commensurate increase in fan diameter, but I'm only guessing
Aeolus From Mexico, joined Aug 2007, 370 posts, RR: 0 Reply 24, posted (2 years 4 months 2 weeks 1 day 7 hours ago) and read 7768 times:
Quoting Golli (Reply 22): Quoting Tdscanuck (Reply 21):
A whole new engine can, based on precedent, get about 5-10% fuel burn improvement. For equal fuel load, that should give you about 6-11% more range
Tdscanuck From Canada, joined Jan 2006, 11034 posts, RR: 72 Reply 25, posted (2 years 4 months 2 weeks 1 day 7 hours ago) and read 7749 times:
Quoting Astuteman (Reply 23): This begs the question as to why CFM can get up to 27 000lb thrust out of the CFM56-7B at only 61" fan diameter, whereas the PW1000G with its 73" fan only makes 23 000lb?
Lower disk loading (and probably lower RPM). A 73" fan is capable of producing quite a lot more thrust than a 61" (at equal technology), but it'll be louder. I suspect P&W's fan sizing is partly about noise reduction, and noise is *very* sensitive to RPM.
Lightsaber From United States of America, joined Jan 2005, 8534 posts, RR: 100 Reply 26, posted (2 years 4 months 2 weeks 19 hours ago) and read 8003 times:
I'm confused by one thing, Airbus told Pratt (per link) that they wanted to see the GTF through IAE. But Pratt isn't that interested in sharing their technology...
Quoting Astuteman (Reply 23): This begs the question as to why CFM can get up to 27 000lb thrust out of the CFM56-7B at only 61" fan diameter, whereas the PW1000G with its 73" fan only makes 23 000lb?
Nice data.
Quoting Tdscanuck (Reply 19): The BPR on a GTF gets bigger primarily by having a smaller core, not a bigger fan. The fan is somewhat bigger, but the big gain is that you can spin that fan with a smaller core.
That is a possible design compromise. But I think the fan diameters will grow.
Quoting Golli (Reply 22): If we give them the benefit of 10%, from the new engine.
A GTF should be able to do better. It all depends on the technology level. For the A320, I think Pratt would be willing to throw in everything that was low risk (even with high development costs). For example, contra-rotation, GTF, Integrated blade-rotor compressors (also called BLISKS), and some other more minor improvements).
If the A320 does go forward with an engine upgrade, this will force Boeing to follow. The only question with Boeing, is will they keep the GE/CFM exclusive or will they allow Pratt to bid an engine? I'm biased, but after admitting that, I think Boeing would be silly not to let Pratt offer a GTF on the 737. This, per my rumor mill, would cut the cost per 737RS by $1.6M to $2M just due to discounting of the engines on bids.
Lightsaber From United States of America, joined Jan 2005, 8534 posts, RR: 100 Reply 28, posted (2 years 4 months 1 week 6 days 23 hours ago) and read 7477 times:
Quoting Golli (Reply 27): We'll see A321's breezing trough trans con's in 2013??
Possibly. The reason I state that is Pratt *might* be able to do a GTF by then, but I do not see much interest in an IAE partnership for the A321.
I also think the development time will be longer as the next 'great leap' would be A320's TATL. That is non-trivial engineering. In part, the engine makers will want Airbus (or Boeing) to further improve their airframes to ensure a long sales life after investing in the engine development. The 'sharklet' A320 with a GTF is not a TATL airframe. More would need to be done. A little weight out of the A320, perhaps a wing reprofile (it is time) or a small wingspan growth.
With those airframe improvements (some, not all), I would see Pratt further refining the GTF for the A320.
It would be a nice jump in sales if the range could best the 752. Then the A321 (possibly a small further stretch) could be sold as a 752 domestic replacement and the A320 for TATL work? But perhaps I dream too much...
BoeingVista From Australia, joined Jan 2009, 658 posts, RR: 1 Reply 29, posted (2 years 4 months 1 week 6 days 23 hours ago) and read 7423 times:
I think that this is an interesting quote from the Fight blogger article
Quote: During the 2009 Paris air show the head of IAE partner MTU Aero Engines Egon Behle told Air Transport Intelligence that as IAE crafts its strategy for an engine to power A320 and Boeing Next Generation 737 replacements, "There are certainly some obstacles to remove." Behle noted Rolls-Royce and Pratt "do have different proposals" to narrowbody development.
We know that Pratt have the GTF, what are RR proposing? A while back RR were talking about a triple spool 30kLbs class engine and open rotor with the same noise levels of a turbo jet, do these proposals still exist?
Lightsaber From United States of America, joined Jan 2005, 8534 posts, RR: 100 Reply 30, posted (2 years 4 months 1 week 6 days 20 hours ago) and read 7302 times:
RR has had a breakthrough in packaging a 'small' triple spool. The economics on short missions (climb) will be excellent. Now, the GTF would beat it on cruise TSFC, but for European missions, the triple spool would be a lower cost engine. For US TCON, a GTF is a much lower cost engine. The question is, at what range do they have the same cost? That I do not know, but it is a very key number.
RR has had a breakthrough in packaging a 'small' triple spool.
OK, but are they actually proposing it for an A320 re-engining project? If so they are keeping pretty quiet about it, I cant find any public references to it even being bench tested which contrasts sharply with all the GTF hooha.
Keesje From , joined Dec 1969, posts, RR: Reply 32, posted (2 years 4 months 1 week 6 days 16 hours ago) and read 7086 times:
Quoting BoeingVista (Reply 31): OK, but are they actually proposing it for an A320 re-engining project? If so they are keeping pretty quiet about it, I cant find any public references to it even being bench tested which contrasts sharply with all the GTF hooha.
RR proposed the RB285 for the COMAC C919, that went with the LeapX.
I guess the LeapX is the lower risk option from market leader CFM (GE/Safran 50/50). It basicly build on GENX like technology. It has no gears or triplle spools. Still they claim 16% better fuel burn then CFM56.
I wonder what the CFM technology in combination with a GTF or third spool could do.
Baroque From Australia, joined Apr 2006, 15380 posts, RR: 60 Reply 33, posted (2 years 4 months 1 week 6 days 13 hours ago) and read 6729 times:
Quoting Lightsaber (Reply 30): RR has had a breakthrough in packaging a 'small' triple spool. The economics on short missions (climb) will be excellent.
Quoting Keesje (Reply 32): RR proposed the RB285 for the COMAC C919, that went with the LeapX.
Help!! Lightsaber!!
http://www.flightglobal.com/articles...285-study-for-150-seat-market.html R-R believes that as an advanced turbofan the three-shaft RB285 would deliver the same efficiency benefits as P&W's GTF, without the need for a reduction gearbox to decouple the fan. It could also be idled at a lower thrust setting by adopting the Trent 1000's intermediate pressure-spool offtake for the accessory gearbox.
Most of the rest I can follow, but what does the bit about idling at lower thrust by adopting the T1000 I pressure-spool offtake mean when it is at home. For starters, there was me thinking being non bleeding, the T000 did not have offtakes and even if it does how does that help you to idle, and idle what?????
I presume by cost you (La) are meaning fuel costs, but presumably there is a change that in terms of engine costs it would be 2 spool < 3 spool < GTF???
This link is the most up to date I have seen and then (08) they were clearly still on the fence.
I really do not understand their position.The short haul market is THE market.They have spent all this time investing in the IAE relationship.Clearly P&W wish to go "geared".Equally open rotor also requires "geared" (I believe from what I have read).
Both P&W and RR routes require a new core.Can they not even agree on this? If not the IAE is over,finito,kaput.
RR's presentation on "stage length" for narrow bodies is highly persuasive (but then it would be) equally the importance of fuel saving relative to cost of mantainance.However if both are true then the 3 stage engine route is the obvious way to go I would have thought.Whether is has a geared fan or not.
It seems to me that GENE-X are pushing full steam ahead on a state of the art high pressure/temperature core and just doing "the best that they can" with the fan. If you look at their presentations they too recognise that to make a further "leap" it will need to involve an exotic solution - whether it be open rotor (GE's preferred?) or contrarotating fans (Snemca's preffered?).
Either way they are "getting on with it" -Rolls apear to be navel gazing.
Stitch From United States of America, joined Jul 2005, 23614 posts, RR: 79 Reply 35, posted (2 years 4 months 1 week 6 days 8 hours ago) and read 6352 times:
Quoting Baroque (Reply 33): I presume by cost you (La) are meaning fuel costs, but presumably there is a change that in terms of engine costs it would be 2 spool < 3 spool < GTF???
A triple spool should have lower maintenance costs than a twin spool since the triple spool is much easier on the LPC and turbine during climb and you only have one high turbine stage versus two (though the latter really is more an RR design philosophy).
Lightsaber From United States of America, joined Jan 2005, 8534 posts, RR: 100 Reply 36, posted (2 years 4 months 1 week 6 days 5 hours ago) and read 6119 times:
Quoting BoeingVista (Reply 31): but are they actually proposing it for an A320 re-engining project? If so they are keeping pretty quiet about it, I cant find any public references to it even being bench tested which contrasts sharply with all the GTF hooha.
RR doesn't tend to make as much noise in the popular press. Instead, they design and sell engines. Pratt has no choice but to run an all out PR campaign as that is the only way they will garner enough mind share to re-enter the commercial engine market. For effectively, GE/CFM and RR have kicked Pratt out of most of the commercial market. The only commercial engines selling are the PW4170A, the PW1000 GTF's, and Pratt Canada business jet engines. And, of course, the V2500.
Compare this to GE with the GEnX (two versions), GE-90, CFM-56, CF-34, helicopter engines (dominates the market), and a huge stable of land based power units. None of the Pratt engines have volume (right now), all of GE's are selling in volume.
RR has the T700, T900, and T1000 selling well. The T800 was well received (back in theday) vs. the PW4098 debacle. Of course they also have the V2500 as well as their Allison stable of business jet engines.
Note: I intentionally do not mention military engines on this civil forum.
Pratt must earn their way back into the market. Part of that is PR.
Quoting Keesje (Reply 32): I wonder what the CFM technology in combination with a GTF or third spool could do.
All of the engine makers have that "CFM technology."
1. Integrated blade rotor compressors (also called BLISKS)
2. New blade profiles (in particular, the fan). Recall Pratt surprised GE with the GP7200's fan efficiency! CFM makes great engines, but they do not have an exclusive..
3. Contra rotation
4. Better Mach number profiles for the turbine and compressor
5. Better cooling designs (saves fuel as air going through the engine can do work instead of cooling).
Now, part of Pratt's strategy (as well as RR) is to take advantage of the inherent efficiency gains to make a lower cost design (fewer stages). There is an engineering compromise to everything.
Quoting Baroque (Reply 33): but what does the bit about idling at lower thrust by adopting the T1000 I pressure-spool offtake mean when it is at home. For starters, there was me thinking being non bleeding, the T000 did not have offtakes and even if it does how does that help you to idle, and idle what?????
The triple spool should consume less fuel at idle even with bleed. The triple also has a tremendous climb fuel burn advantage. So on short hop missions it should have the best economics.
But there is an advantage to lower fuel burn on longer missions as long as the short haul costs match or beat the LEAPX.
The quetion is where is the break even? If Pratt can make it on the 1 hour mission... they'll dominate as the lower fuel burn will open up new markets. If it is not until a 90 minute or 2 hour mission... few will buy the Pratt's who do not do quite a few TCON's.
Quoting Parapente (Reply 34): Both P&W and RR routes require a new core.Can they not even agree on this? If not the IAE is over,finito,kaput.
This issue is ownership. Both P&W and RR wish to 'own' more of the future engine. Also, their two concepts require very different cores. The company that 'wins' will earn licensing fees from the other.
DocLightning From United States of America, joined Nov 2005, 14043 posts, RR: 55 Reply 37, posted (2 years 4 months 1 week 6 days 5 hours ago) and read 6066 times:
Quoting Tom355uk (Reply 10): True, the A320 does have greater ground clearance than the 737, but the NG models have longer gear legs than the Classic 734 pictured so the Nacelles are less 'hamsterized'. I believe the Classics' ground clearance is ~45cm - feel free to correct me if i'm wrong!
The 733-5 have the same gear as the 73G. It had to be extended from the Jurassics to the Classics to fit the new engines, but the 73G has the same nacelles as the Classic. AND, unlike the A320, which has plenty of room both above and below the nacelle for expansion, the 737 is out of room.
A342 From Germany, joined Jul 2005, 4627 posts, RR: 4 Reply 38, posted (2 years 4 months 1 week 6 days 3 hours ago) and read 5881 times:
Quoting Lightsaber (Reply 36): The only commercial engines selling are the PW4170A, the PW1000 GTF's, and Pratt Canada business jet engines. And, of course, the V2500.
Don't want to split hairs, but I don't think the PW4000 (all series combined) is nowadays selling in higher numbers than the GP7200. And the PW6000 is a sad story.
On top of that PWC has a very big helicopter business which seems to be growing.
Quoting Lightsaber (Reply 36): Compare this to GE (...) helicopter engines (dominates the market),
But now that's a slight exaggeration. Apart from medium to large helicopters, their market share is basically zero. I'm not sure, but I'd say in terms of numbers delivered, RR, Turbomeca and PWC are each bigger than GE.
R2rho From Germany, joined Feb 2007, 1811 posts, RR: 1 Reply 39, posted (2 years 4 months 1 week 5 days 11 hours ago) and read 5583 times:
CFM has an easier job as improving the CFM56 with the latest GenX technology should be a more straightforward task than introducing a new architecture as PW and RR are doing.
But I wonder what will happen to IAE.... Leahy had already said that he wanted an engine offering only through the IAE consortium (understandable, from a customer support point of view), but PW and RR seem to be on different development paths that are not compatible with each other. It's either GTF or triple spool, but not both, because the design philosophies behind each are different.
So, will they each go their own way? Is there room for 3 engine types (5, if you count for the old CFM56 and IAE's that would continue to be supported)? Given the number of a/c involved, I think yes. But is it desireable for A&B to offer 3 engine choices? Or maybe they could offer 2 and 2 : LEAPX on both, and then say GTF on the A320 and RB285 on the 737, or viceversa...
Baroque From Australia, joined Apr 2006, 15380 posts, RR: 60 Reply 40, posted (2 years 4 months 1 week 5 days 8 hours ago) and read 5409 times:
Quoting Lightsaber (Reply 36): Quoting Baroque (Reply 33):
but what does the bit about idling at lower thrust by adopting the T1000 I pressure-spool offtake mean when it is at home. For starters, there was me thinking being non bleeding, the T000 did not have offtakes and even if it does how does that help you to idle, and idle what?????
The triple spool should consume less fuel at idle even with bleed. The triple also has a tremendous climb fuel burn advantage. So on short hop missions it should have the best economics.
I see, had not realised that idling config would be so important.
Quoting Lightsaber (Reply 36): This issue is ownership. Both P&W and RR wish to 'own' more of the future engine. Also, their two concepts require very different cores. The company that 'wins' will earn licensing fees from the other.
After a couple of decades of joint venture you would think they would have got past that stage!! Back to Rover and the B-26 in 1942??
Lightsaber From United States of America, joined Jan 2005, 8534 posts, RR: 100 Reply 41, posted (2 years 4 months 1 week 5 days 8 hours ago) and read 5383 times:
Quoting A342 (Reply 38): Apart from medium to large helicopters, their market share is basically zero.
Sadly, the medium and large helicopter market generates far more revenue, in particular support revenue, than the light helicopter market. That might change with UAV's... but for now, the oil companies prefer very large helicopters and they are the easiest profit in that market.
But you are correct that I was a bit harsh. But in large commercial airframes, Pratt must work their way back into the market. What a change from dominating the market!
Quoting Baroque (Reply 40): After a couple of decades of joint venture you would think they would have got past that stage!! Back to Rover and the B-26 in 1942??
If anything, the decades have made Pratt and RR 'harden their positions.' They both feel they 'gave too much away' with the current V2500 IAE contract.
The same was true of GE/SNECMA with CFM. But somehow they patched things up... So there is no absolute here. I'm trying to just show why they haven't jumped back together. I personally believe/speculate that Airbus will only allow two engines on the next A320NG (or whatever it is called). GE/SNECMA is pretty much a given (if for no other reason than to not drive away GEAS). Airbus made statements that they would prefer the next A320 engine to be IAE. But both Pratt and RR would like it to be there engine.
Parapente From United Kingdom, joined Mar 2006, 1209 posts, RR: 10 Reply 42, posted (2 years 4 months 1 week 5 days 8 hours ago) and read 5325 times:
I noticed that recently Dassault withdrew their agteement to use RR's new 2 spool engine (suggesting that - after 2 years work,they needed somethng with more thrust than the 10K lbs RR were offering - I guess their mid sized business plane is going to be supersonic!).That leaves zero takers for this design route.
One can see the logic for a triple spool - it's RR's area of expertise.One range of Trents from top to bottom - very attractive if they could make it work. But it is said (above) that 3 spool is incompatable with GTF technology. My question is why?
Lightsaber From United States of America, joined Jan 2005, 8534 posts, RR: 100 Reply 43, posted (2 years 4 months 1 week 5 days 6 hours ago) and read 5194 times:
Quoting Parapente (Reply 42): One can see the logic for a triple spool - it's RR's area of expertise.One range of Trents from top to bottom - very attractive if they could make it work. But it is said (above) that 3 spool is incompatable with GTF technology. My question is why?
First a note: RR can build triple spools down to ~27k of thrust. So any smaller engine should be a twin spool. Pratt has GTF concepts down to 16K and there is no reason they couldn't go smaller.
As to the incompatibility of triple and GTF, it could be done, but there is little advantage.
The advantages of a triple spool:
1. "Booster compressor" and (more importantly) the turbine that powers it are at a much more ideal mach number across the blades (or you can think of it as more ideal spool RPM).
2. The booster compressor (and turbine) can adjust to better match the current flight conditions.
The #1 disadvantage of the triple spool is:
1. Poor match of blade mach numbers between the fan and the turbine powering the fan. There is a turbine efficiency hit in all current engines due to the low mach number across the low turbine blades.
With a GTF, advantage #1 of the triple is taken away. Also, the GTF has the low turbine at about 250% to 300% of the RPM of the low turbine in the triple spool. So what is a disadvantage on a triple spool is an advantage on a GTF.
The only thing left for the triple spool is advantage #2. It will always have a better climb fuel burn.
To be fair to the triple spool fans out there, it is time (in my opinion) for one further improvement in the *long haul* triple spools. Move the first compressor stage onto the fan. Why? This would allow the rest of the 'intermediate compressor' to operate at even more optimal RPM (Mach number across blades). There is also a limit to the horsepower possible with one turbine stage for the high compressor and one turbine stage for the intermediate compressor. So don't worry about it. Put one compressor stage on the fan spool. This would allow the high compressor and intermediate compressors (and their turbines) to be even *better* optimized. (The first compressor stage would heat the air going into the intermediate compressor allowing for a faster spool RPM.) There is also an advantage to the higher 'overall pressure ratio.'
I had hopes to see this layout on the T1000 (I think it would cut fuel burn another 2%, possibly even more thanks to the higher RPM/Mach numbers on the high and mid turbines. The added weight would be about 300 to 500 lbm. So this optimization only 'pays off' for long haul. It also would add very little climb penalty to the trent (only one low compressor stage).
Oh, why the switch in terminology? The first comrpessor stages can be called the low compressor, initial compressor, or the booster compressor. The 2nd (of 3) compressors can be called the intermediate (or mid) compressor or the booster compressor. So to be clear, I changed terminology.
Parapente From United Kingdom, joined Mar 2006, 1209 posts, RR: 10 Reply 44, posted (2 years 4 months 1 week 5 days 6 hours ago) and read 5073 times:
Thanks for the above Lightsaber.Perhaps this is their "breakthrough" for their new triple design.However from what you have said it has got to be 2 or nothing if GTF is the only IAE route. Perhaps this makes sense as the open rotor/ new plane is moving further and further to the right. In 20 years who knows what will be happening!
Clearly a blow to Rolls.But if the damage is limited to this market segment only perhaps it's worth it.
My only concern is whether P&W have really cracked it. Who am I to say such a thing - clearly nobody.But reading about the past it is littered with (Planetary) failures - not because it could be built but that it could not be built for 15 years of hard work.I hope they have.
Jambrain From United Kingdom, joined Sep 2008, 220 posts, RR: 14 Reply 45, posted (2 years 4 months 1 week 5 days 4 hours ago) and read 4963 times:
Quoting Lightsaber (Reply 43): There is also a limit to the horsepower possible with one turbine stage for the high compressor and one turbine stage for the intermediate compressor
Which is presumably why RR now have 2 IP turbine stages on Trent XWB
Quoting Lightsaber (Reply 43): This would allow the rest of the 'intermediate compressor' to operate at even more optimal RPM (Mach number across blades).
But the booster stage would be running a very low mach no and the lp turbine would need to produce more hp, and being as GE on GENX have to design their 10 stage hp compressor to cover a wider range of blade mach no, I'm sure matching a 8 stage is more optimal for RR.
I'm guessing RR would have modelled both!
Of course they may think that the swan neck booster duct is aethetically unapealing and rejected it despite it being 2% better fuel-burn
jam
AirbusA6 From United Kingdom, joined Apr 2005, 1717 posts, RR: 0 Reply 46, posted (2 years 4 months 1 week 5 days 4 hours ago) and read 4971 times:
Quoting R2rho (Reply 39): But I wonder what will happen to IAE.... Leahy had already said that he wanted an engine offering only through the IAE consortium (understandable, from a customer support point of view), but PW and RR seem to be on different development paths that are not compatible with each other. It's either GTF or triple spool, but not both, because the design philosophies behind each are different.
After the PW6000 debacle, would Airbus (and the market) trust Pratt to do an engine on their own, as a number of A318 customers got their fingers burnt as a result of the PW6000 problems?
it's the bus to stansted (now renamed national express a4 to ruin my username)
A342 From Germany, joined Jul 2005, 4627 posts, RR: 4 Reply 47, posted (2 years 4 months 1 week 5 days 3 hours ago) and read 4889 times:
Quoting Lightsaber (Reply 41): Sadly, the medium and large helicopter market generates far more revenue, in particular support revenue, than the light helicopter market. That might change with UAV's... but for now, the oil companies prefer very large helicopters and they are the easiest profit in that market.
True, and I guess the utilization rate of oil helos is much higher than other commercial segments, so more mx must be performed and aircraft might be replaced earlier.
Quoting Lightsaber (Reply 41): But you are correct that I was a bit harsh.
Nah, just a point of view issue.
Quoting Lightsaber (Reply 43): First a note: RR can build triple spools down to ~27k of thrust.
So an A319(HGW) or A320-sized aircraft would be the lower limit for an (economical) narrowbody three-spool application?
Stitch From United States of America, joined Jul 2005, 23614 posts, RR: 79 Reply 48, posted (2 years 4 months 1 week 5 days 3 hours ago) and read 4910 times:
Quoting AirbusA6 (Reply 46): After the PW6000 debacle, would Airbus (and the market) trust Pratt to do an engine on their own, as a number of A318 customers got their fingers burnt as a result of the PW6000 problems?
The PW1000G is going to literally make or break Pratt in the commercial airliner market. To use a US baseball analogy, after the PW6000 and PW4000 misses, a miss with the PW1000G would be the "third strike" and they'd be "out".
Lightsaber From United States of America, joined Jan 2005, 8534 posts, RR: 100 Reply 49, posted (2 years 4 months 1 week 5 days 2 hours ago) and read 4844 times:
Quoting Jambrain (Reply 45): I'm guessing RR would have modelled both!
Naaa... Obviously my back of the envelope calculations are more accurate.
Seriously, I missed the XWB had a twin stage turbine on the intermediate. Although when I read the factsheets, it sounds like an engine where details are far from decided.
Quoting Jambrain (Reply 45): Of course they may think that the swan neck booster duct is aethetically unapealing and rejected it despite it being 2% better fuel-burn
or weight. The engine I describe would be less optimal for short missions (< 3,000nm). Customers like EK might not have appreciated that 'over-optimization.'
However, while a single stage low compressor would be at a poor mach number, the heating of the air into the mid-compressor has many advantages for a triple spool. Pratt is even looking into the concept for high thrust GTF's.
But remember, I'm in R&D/test. Whatever has been done... there is a better way!
Quoting Stitch (Reply 48): The PW1000G is going to literally make or break Pratt in the commercial airliner market. To use a US baseball analogy, after the PW6000 and PW4000 misses, a miss with the PW1000G would be the "third strike" and they'd be "out".
Low thrust is lower risk for a GTF, so the C-series and MRJ were logical launch candidates. If Pratt botches teh PW1000G... they are done. The PW4098, PW4173, and in particular PW6000 might be why airbus wants Pratt to be in IAE.
Now if the proposed Russian airliner goes forward, it locks Pratt into GTF development that is appropriate in thrust class for the A320 family. (But I have trouble taking the MS-21 concept seriously, but that is my own personal bias.) Proposed Russian MS-21 To Use Pratt Engine (by LAXintl Dec 10 2009 in Civil Aviation)
Right now I see the engine selection on the A320 like a good game of poker. Everyone is bluffing. No one holds such a strong hand that they're certain to win. The C919 and (possibly) the MS-21 throw two wild cards into the mix. Except these are like wildcards that have an uncertain value... So how does one bet? Also, in this poker game every engine vendor can merge cards with another player (e.g., IAE).
The only thing clear to me is Airbus will almost certainly go with the LEAP-X too (with a custom fan diameter).
PW100 From Netherlands, joined Jan 2002, 1760 posts, RR: 12 Reply 50, posted (2 years 4 months 1 week 4 days 14 hours ago) and read 4624 times:
Quoting Lightsaber (Reply 43): The #1 disadvantage of the triple spool is:
1. Poor match of blade mach numbers between the fan and the turbine powering the fan. There is a turbine efficiency hit in all current engines due to the low mach number across the low turbine blades
Why not solve that with a GTF?
I would also expect that an added advantage of a tripple spool is that both take-off performance and cruise performance deterioration would be less than a double spool. Not sure to what extent this works out on large engines, but generally a tripple spool should handle wear and tear better than a double spool.
Since the intermediate spool has no mechanical linkage to the other two spools, allowing all spools to operate closer to their design point [even when one or more compressor or turbine stages starts to deteriorate]. The engine will settle itself better and closer to design points.
Again, not sure how this works out on very large turbofans, but at my scale [reference my username ] this works out very nicely. Although a turboprop, in essence it is a tripple spool. And once you get the spool speed matching right, the engine can withstand an incredable amount of compressor and or turbine wear, and still make rated performance. Even fuel burn penalty is pretty limited - usually less than 2% after regular scheduled MTBR.
Then again, my engine is optimized for one hour stretches, not 8000 nm cross-continental hikes!
Regards,
PW100
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
Sirtoby From Germany, joined Nov 2007, 228 posts, RR: 23 Reply 51, posted (2 years 4 months 1 week 4 days 13 hours ago) and read 4529 times:
Quoting Astuteman (Reply 23): This begs the question as to why CFM can get up to 27 000lb thrust out of the CFM56-7B at only 61" fan diameter, whereas the PW1000G with its 73" fan only makes 23 000lb?
Because of a low fan pressure ratio, which on the other hand provides extremely good propulsive efficiency - and low noise.
Baroque From Australia, joined Apr 2006, 15380 posts, RR: 60 Reply 52, posted (2 years 4 months 1 week 4 days 11 hours ago) and read 4423 times:
Quoting Lightsaber (Reply 41): They both feel they 'gave too much away' with the current V2500 IAE contract. spin
Sounds as if not only is school still in, but they are still firing ink bombs at each other - or whatever the equivalent is in the era of the ballpoint and keyboard.
Quoting Stitch (Reply 48): To use a US baseball analogy,
So you mean PW are on steroids?
This thread started off pretty good, but it just seems to have got better and better. Great information on the niceties (and nasties) of the engines.
Stitch From United States of America, joined Jul 2005, 23614 posts, RR: 79 Reply 53, posted (2 years 4 months 1 week 4 days 10 hours ago) and read 4380 times:
Quote: Leahy stresses that Airbus is not interested in a sole-source deal with P&W for the GTF, and urges the US engine maker to get together with its IAE partners - which include Rolls-Royce - to "work out a way for IAE to offer the GTF".
Pressure on PW to stay in IAE, and pressure on RR to not go off by themselves on their triple spool route! Apart from anything else, could RR have a brand new engine available in the desired timescale?
it's the bus to stansted (now renamed national express a4 to ruin my username)
Lightsaber From United States of America, joined Jan 2005, 8534 posts, RR: 100 Reply 56, posted (2 years 4 months 1 week 3 days 6 hours ago) and read 3917 times:
Quoting PW100 (Reply 50): Why not solve that with a GTF?
1. Requires developing a high thrust GTF. The risk above 62k of thrust grows exponentially. My opinion is the limit is 75k today. (But with far more risk to buy down than a smaller engine.)
There is little risk with less than 40k (the size of triple spool we are discussing). But at that level of thrust, it would be impossible to package in the added set of bearings and the gearbox without lengthening the engine. That added weight kills off the benefit of going with a triple spool on short missions. In other words, it is not worth the effort as too few turbine rows benefit (vs. a double spool which has turbine rows to power the compressor).
In my opinion (only an opinion), a triple spool GTF does not makes sense below 85k of thrust (perhaps 74k (A388) would be good enough for long mission lengths). Half of the GTF benefit is already taken care of by having the intermediate spool powered by a dedicated turbine.
Where would a GTF triple spool make sense? 77W baby! But we're 15 years away from that gearbox being developed.
Quoting Aircellist (Reply 54): Back to topic, it seems it is Airbus pushing on IAE to incorporate PW's geared fan!
Thank you for the link. However, it is not a 100% consistent statement:
Quote: The Leap-X advanced turbofan and the PW1000G are being evaluated, and Enders repeated Airbus's previous statement that it wants an offer from its existing A320 supplier IAE.
If the PW1000G is being evaluated, that is a Pratt engine. Why would Pratt give up the revenue the IAE partnership requires? Now, the alternative is a customized A32X engine from IAE with RR doing the fan and compressors. Five years ago, I would be certain that would be a better engine than Pratt could deliver. Today... Pratt has caught up tremendously on fan (witness GP7200) and is putting in the integrated blade rotor compressor technology.
So I think it is more Airbus trying to convince Pratt to go with IAE. Airbus would make a *serious* mistake allowing 3 engines on the 32X. The questions in resale value would have airlines holding off orders to see which 2 engines 'won.' Since that takes years... They must, a la 787, push for two engine vendors. (CFM/IAE seems to be the prefered choice. In other words, sticking with the status quo.)
If that happens, I will be *very* interested to see which airline defects from one engine to the other!
CFM will have the lower risk design.
The GTF will be the better engine for long range missions (for example, B6).
The PW1000G has 'compromises' to make it more optimal on shorter missions... so it might hold value there too. My rumor mill is telling me good things about the C-series variant. The MRJ is behind schedule (no surprise, Mitsubishi hasn't taken on such an effort in too long) and while Pratt is serious about developing the engine for the Russians... how to say this, they are being "only as serious as the Russians" in development effort.
So the Pratt GTF's are moving forward. Now to just sell more! but also
Quoting Baroque (Reply 52): This thread started off pretty good, but it just seems to have got better and better. Great information on the niceties (and nasties) of the engines.
BoeingVista From Australia, joined Jan 2009, 658 posts, RR: 1 Reply 57, posted (2 years 4 months 1 week 3 days ago) and read 3740 times:
Quoting AirbusA6 (Reply 55): could RR have a brand new engine available in the desired timescale?
I guess thats the question, but if Airbus went that way or with the PW1000G it would probably be the end of IAE and that is not in Airbusses interests. They need to hope that good sense prevails, but as Lightsaber points out ownership is the key and if RR knuckle under and accept the GTF as the basis of the next IAE NB engine they would probably be accepting that they will never produce a 3 spool 30K lb class engine, future revenues and licence fees could add up to billions.
Revelation From United States of America, joined Feb 2005, 8073 posts, RR: 13 Reply 58, posted (2 years 4 months 1 week 2 days 10 hours ago) and read 3557 times:
Quoting AirbusA6 (Reply 55): Pressure on PW to stay in IAE, and pressure on RR to not go off by themselves on their triple spool route! Apart from anything else, could RR have a brand new engine available in the desired timescale?
I can see why Airbus would not want/allow 3 different engines (CFM, RR, PW) on the A320, but I can't see why they insist on an IAE offering.
It seems to me that Airbus hasn't been too successful telling engine companies what to do (witness GE on A350XWB), and they won't be in this case either.
Quoting Lightsaber (Reply 56): If the PW1000G is being evaluated, that is a Pratt engine. Why would Pratt give up the revenue the IAE partnership requires? Now, the alternative is a customized A32X engine from IAE with RR doing the fan and compressors. Five years ago, I would be certain that would be a better engine than Pratt could deliver. Today... Pratt has caught up tremendously on fan (witness GP7200) and is putting in the integrated blade rotor compressor technology.
Agreed, it's a cut-throat business and Pratt is playing catch-up, so if they think they have a winner on their hands I can't see how they can be convinced to compromise.
Quoting BoeingVista (Reply 57): I guess thats the question, but if Airbus went that way or with the PW1000G it would probably be the end of IAE and that is not in Airbusses interests.
Why? Aren't PW or RR substantial enough entities on their own?
Keesje From , joined Dec 1969, posts, RR: Reply 59, posted (2 years 4 months 1 week 2 days 9 hours ago) and read 3526 times:
Quoting Revelation (Reply 58): I can see why Airbus would not want/allow 3 different engines (CFM, RR, PW) on the A320, but I can't see why they insist on an IAE offering.
Quoting Revelation (Reply 58): Why? Aren't PW or RR substantial enough entities on their own?
After being market leader for decades I think PW lost it clinging to the JT9's and not performing as good as GE//RR with the PW4000. PW and Airbus have a history on GTF/A320 and I guess Airbus wants the "weight"of RR behind the GTF. Airbus were close to launch the GTF on the A320 series 10 years ago..
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And the PW6000 is a sad story.
If anything, the decades have made Pratt and RR 'harden their positions.' They both feel they 'gave too much away' with the current V2500 IAE contract. 
But we're 15 years away from that gearbox being developed.
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