Quoting lightsaber (Reply 10): The C-series and MRJ share the same core. The MRJ takes the unusual step of a low loading the low spool. In other words, with lower pressure feeding the high spool there is less air and thus the same combustor, with just 'minor'* changes for the reduced fuel loading are required. Most of the cost will be borne by the C-series. I've heard rumors that the MRJ will only require ~150 engines to break even. Nothing like saving on a two stage low compressor.
The MS-21 and A320NEO also share a high spool. I suspect it will take a bit of explaining to differentiate the two engines (if there are any, my rumor mill won't talk A320NEO or MS-21 right now). However, I expect the two nacelles to be related, but different in key features.
You may want to post to that thread to follow up on this, but it seems our local expert lightsaber doesn't have the info at this point in time.
pylon101 From Russia, joined Feb 2008, 1392 posts, RR: 0
Reply 5, posted (2 years 7 months 3 weeks 3 days 16 hours ago) and read 7626 times:
The question of PW 1400G for MS-21 is being discussed due to the fact that PW and United Engine Corporation revealed plans to assemble this engine in Russia in Perm - and we have no idea on what terms.
As it used to be the discussion immediately switched to national interests.
If SNECMA is working with Saturn plant and PW is going to do the same in Perm - to what extend this cooperation is a positive factor considering high stakes made on PD-14 new generation engine?
I suspect this is going to be like CFM-56-x numbers. The difference is that the were at least in development order.
Quoting Revelation (Reply 4): You may want to post to that thread to follow up on this, but it seems our local expert lightsaber doesn't have the info at this point in time.
If you want insight into the A320NEO or MS-21 engines, the wikipedia link is pretty good.
Right now, the A320NEO should have the highest pressure ratio. ~10% higher than the C-series. That alone makes for a more efficient engine.
Its killing me waiting for the actual fuel burn numbers on the C-series. I'm expecting the engine to beat expectations. However, Pratt has a history of missing fuel burn by 4%. So perhaps all the margin my rumor mill is excited about will just be eaten up by the standard fuel burn miss. We won't see another PW6000... (Pratt couldn't afford that... hence MTU as a partner.)
The MRJ and C-series show much of the opportunity of the GTF: Easier variability of the low spool. The closest analogy we've had has been the Trent series where RR could 'mix and match' for new engines relatively easy (e.g., the T500 wouldn't have happened otherwise. Although a 2-stage low compressor.. Ok, that was case where Pratt could beat the other offered engines with what will be a mighty low pressure ratio. However, expect that engine to have *insane* cycle life (even versus its sister engine on the C-series). Considering the very short missions of the MRJ, that could be a winning compromise!
The A320 NEO engine is a higher OPR (Overall pressure ratio). I question what changes will be made. Risk reduction would throw those changes on the low spool. Sigh... Those that know aren't sharing.
Right now the profit will be the A320NEO. In fact, that one engine will pay for the development of the other three. Without the C-series, there wouldn't have been the MS-21 which is doing much of the engineering to have a timely entry into service for the A320NEO. The MRJ is a bonus side engine. With the redesign, I'm hearing far better scuttlebutt on that airframe. In other words, it might just sell enough to be a profit center on its own.
packsonflight From Iceland, joined Jan 2010, 365 posts, RR: 0
Reply 8, posted (2 years 7 months 3 weeks 2 days 23 hours ago) and read 6319 times:
I saw somewhere that the GTF is focusing on the gearbox right now and the turbine technology is relatively old compeared to the LeapX, so is if fair to assume that once PW has mastered the gearbox they can start to conscetrate on the turbine, and pick a lot of low hanging fruits there, resulting in a far superior engine to the LeapX
lightsaber From United States of America, joined Jan 2005, 12414 posts, RR: 100
Reply 9, posted (2 years 7 months 3 weeks 2 days 21 hours ago) and read 5856 times:
Quoting packsonflight (Reply 8): I saw somewhere that the GTF is focusing on the gearbox right now and the turbine technology is relatively old compeared to the LeapX
Correct. The CMC high turbine on the Leap-X is a 6% fuel burn advantage. I also see a *far* more aggressive low turbine on the Leap-X. Combined with the scalloped low compressor, (which is *far* more advanced than any other low compressor), and you can see why the Leap-X can sell against the GTF.
But a CMC tubine, at achieve optimal efficiency, must be designed in from the start. It is not an easy retrofit. Unless a significant thrust increase is planned, there will be significant wasted cooling air. However, it isn't a trivial thing to utilize that cooling air. For example, the diffuser, fuel injector, and other combustor parts must be designed for the air to be utilized as combustion (hot) air instead of cooling air.
Revelation From United States of America, joined Feb 2005, 11919 posts, RR: 25
Reply 11, posted (2 years 7 months 3 weeks 2 days ago) and read 5120 times:
Quoting lightsaber (Reply 9): The CMC high turbine on the Leap-X is a 6% fuel burn advantage.
Since this was going over my head, I did some research on this and came up with:
Ceramic matrix composites (CMCs) are a subgroup of composite materials as well as a subgroup of technical ceramics. They consist of ceramic fibers embedded in a ceramic matrix, thus forming a ceramic fiber reinforced ceramic (CFRC) material. The matrix and fibers can consist of any ceramic material, whereby carbon and carbon fibers can also be considered a ceramic material.
The motivation to develop CMCs was to overcome the problems associated with the conventional technical ceramics like alumina, silicon carbide, aluminium nitride, silicon nitride or zirconia – they fracture easily under mechanical or thermo-mechanical loads because of cracks initiated by small defects or scratches. The crack resistance is – like in glass – very low. To increase the crack resistance or fracture toughness, particles (so-called monocrystalline whiskers or platelets) were embedded into the matrix. However, the improvement was limited, and the products have found application only in some ceramic cutting tools. So far only the integration of long multi-strand fibers has drastically increased the crack resistance, elongation and thermal shock resistance, and resulted in several new applications.
Quote: The use of CMCs in gas turbines would permit higher turbine inlet temperatures, which would improve turbine efficiency. Because of the complex shape of stator vanes and turbine blades, the development was first focused on the combustion chamber. In the US, a combustor made of SiC/SiC with a special SiC fiber of enhanced high-temperature stability was successfully tested for 15,000 hours. SiC oxidation was substantially reduced by the use of an oxidation protection coating consisting of several layers of oxides. The engine collaboration between General Electric and Rolls-Royce is studying the use of CMC stator vanes in the hot section of the F136 turbofan engine presently used in the Joint Strike Fighter. The engine joint venture, CFM International is also considering the use of CMC parts to reduce weight in its Leap-X demonstrator engine program, which is aimed at providing next-generation turbine engines for narrow-body airliners. CMC parts are also being studied for stationary applications in both the cold and hot sections of the engines, since stresses imposed on rotating parts would require further development effort. Generally, a successful application in turbines still needs a lot of technical and cost reduction work for all high-temperature components to justify the efficiency gain. Furthermore, cost reduction for fibers, manufacturing processes and protective coatings is essential.
I also ran across the following from earlier this year:
CFM’s LEAP-X. The approach to performance improvement for CFM has been to raise the bypass ratio by moving to higher temperatures and pressures. This move is supported by a switch to new, more advanced materials. A key application of new materials will be the use of ceramic matrix composite (CMC) blades in turbines for the LEAP-X. It appears that these blades are now to be ready to go into service in 2020 (we understand that this slipped from 2018). This timing is four years after the engine should be service. Our concern is that greater cooling requirements will reduce fuel burn performance and higher temperatures will reduce blade life on the early engines. The LEAP-X is also at an earlier development stage than the GTF with design freeze planned at the end of 2011 and “core 3″ to be completed in mid-2012. The flying test bed is scheduled for Q3 2013.
sirtoby From Germany, joined Nov 2007, 351 posts, RR: 22
Reply 12, posted (2 years 7 months 3 weeks 2 days ago) and read 5053 times:
Quoting Revelation (Reply 4): Quoting lightsaber (Reply 10):
The C-series and MRJ share the same core.
Not true - the CSeries core is upscaled from the MRJ core.
And the core of the NEO engine is another upscale from the CSeries core.
PW1100G and PW1400G share the same core - in fact it is the same basic engine with different externals and mounts.
Quoting pylon101 (Thread starter): PW 1100G - for NEO
PW 1524G - is with largest fan (dia. 73")
PW 1200G - for CS and MRJ
PW 1400G - for MS-21
PW1000G - family of Geared Turbo Fans
second number: aircraft OEM: 0= Boeing, 1= Airbus etc.
last two numbers: takeoff thrust in klbf, highest version of the PW1100G will be the PW1133G, delivering 33klbf at SLS Takeoff
Quoting lightsaber (Reply 9): I also see a *far* more aggressive low turbine on the Leap-X.
The seven-stage LPT in the LEAP-X is not aggressive - but the fact the engine needs seven stages just shows that teh GTF might be the superior concept as it just needs 3 stages in the high-speed LPT.
Click on the Characteristics tab for:
"The numbering scheme for each PW1000G engine model follows the same historical Pratt & Whitney pattern: the first number represents the generation—in this case, 1 or 1,000. The second number denotes the customer: 1 for Airbus, 2 for Mitsubishi, 4 for Irkut, and 5 for Bombardier. The last two numbers indicate the thrust class: 24 for 24,000 pounds of thrust, and so forth. And finally, the “G” stands for a geared turbofan engine. Above, the full PW1000G engine product table is listed in order of thrust."
I see also that the A320NEO and MS-21 now both have the same fan diameter. Sensible.
Quoting Revelation (Reply 11): So there seems to be some question as to whether or not LEAP-X will have its CMC turbine.
First, great links. Thank you. How did the LEAP-X sell that well sans CMC high turbine?!?
Quoting sirtoby (Reply 12): The seven-stage LPT in the LEAP-X is not aggressive
Aggressive was my word as they're pushing the core exit pressure down toward the fan exit pressure. There are transient compromises doing that.
Quoting sirtoby (Reply 12): Not true - the CSeries core is upscaled from the MRJ core.
You're saying the C-series has a higher flow number core than the MRJ? Since 'core is the high compressor, combustor, and high turbine,' I see no reason Pratt would change. I'm not seeing room in the test program for even a scaled core. Nitpick, the MRJ is derived from the C-series. The two stage low compressor (down from 3 on the C-series) is enough to explain the power difference. If I'm wrong, I'd be happy to be corrected. But I'm only seeing the test plan for two sizes of cores in the GTF family.
Personally I'm floored with the 2 stage LPC on the MRJ.
pylon101 From Russia, joined Feb 2008, 1392 posts, RR: 0
Reply 14, posted (2 years 7 months 3 weeks 1 day 20 hours ago) and read 4844 times:
It explains a lot.
And believe that 1400 series will be eventually turn into 3 different indexes, for MS-21 -200, -300 and -400 .
Like for Airbus 1124-1128-1133.
PW is probably waiting for updated specs from Irkut.