keesje From , joined Dec 1969, posts, RR: Posted (6 years 1 month 3 weeks 5 days 16 hours ago) and read 6271 times:
Remarkable open interview of John Croft with Leap programme director Ron Klapproth. Lots of details on technology, time table, C919 vs A320/737, and interesting trade-offs between BPR & weight etc. Enjoy
keesje From , joined Dec 1969, posts, RR:
Reply 2, posted (6 years 1 month 3 weeks 5 days 7 hours ago) and read 5933 times:
Quoting Burkhard (Reply 1): They still have a lot to do if they really want it in service in 2016 already, not much time left.
They say they've working on it for 12 yrs already.
A related article on the GTF, PW, IAE, RR
P&W's commercial engines senior vice-president of sales, Bob Keady, declined to comment on any GTF development that IAE could undertake. However, he says that from P&W's perspective an advanced version of the engine could feature improvements to the core, such as newer-generation materials, and increased bypass and pressure ratios.
lightsaber From United States of America, joined Jan 2005, 15560 posts, RR: 100
Reply 4, posted (6 years 1 month 3 weeks 5 days 5 hours ago) and read 5769 times:
AIRLINERS.NET CREW FORUM MODERATOR
Overall a slightly different engine than I was expecting. This isn't a bad thing, it is just my 'guess' on the state of GE technology. I will 'tune my understanding' as more information becomes available.
The bypass ratio is higher than I expected in a non-GTF. (around 11:1 per the link)
Quote: Klapproth says the X1C fan will have a 190.5cm (75in) "plus or minus an inch" diameter with 18 blades, compared with 36 titanium blades for a CFM56-5C and 24 blades for a CFM56-7B.
I want to see that fan. I have to admit I haven't seen concepts dropping to 18 blades (I'm not in fan development... )
Combined with a new lighter fan containment structure, total weight savings will be 455kg (1,000lb) per aircraft, says CFM. Bypass ratios for re-engining programmes might be 9-10:1, says Klapproth.
1,000 lbm per aircraft?!? That is *far less* weight reduction than what I was expecting. Hmmm... so there is room for the GTF. Seriously, IAE (if that is the GTF path forward) will have to do a bit in weight reduction to stay competitive.
Quote: The X1C will have a 10-stage HPC (1-4 are blisks, 5-10 are blades)
Bummer... I expected 8 BLISKS and 2 blades. So if anyone tells me GE has a plan to cut fuel burn ~1%, I'm going to be guessing the LEAP-X HPC is going more BLISK!
Quote: CFM International says open rotor by itself can deliver as much as a 26% reduction in fuel burn over today's models.
Which is 10% below the LEAP-X. Interesting... but I think there is far more work ahead on shrouded fans that will make it so that the GTF and Open rotor have similar economics.
I expect the engine front to be nothing but noise before Farnborough. But at that airshow expect to hear about the A320 and 737 re-engine.
Quoting Fly2HMO (Reply 3): Interesting. I wonder what the stators look like, I'm assuming they have a 3D airfoil as well.
That is interesting. I wonder if they will make the final design.
"They did not know it was impossible, so they did it!" - Mark Twain
To my eye they go a long way to explaining the thinking of the various players in this market.The Leap-x consortium's thinking is very openly explained (3 stages of development) with the different technologies involved.Also the timelines required.It is very interesting to note that they (like RR) see the ultimate development as a contra rotating open rotor.
The IAE position is somewhat less clear but of course until (not if) P&W and RR resolve workshare these two players will be unavailable for detailed comment.
However one cannot help but notice 2 points.
1.That GE see the way forward as scaling new technology of large engine design down to the smaller engine (which is RR's position)
2.That to get to the ultimate target (2025) 25% reduction in fuel burn it has to be contra rotating open rotors. (Rolls' position).
Yet when you look at Rolls' 15 -50 document thay clearly state that to achieve this (OR) one requires a planitary gearbox to keep the open rotors operating efficiently.
Thus perhaps the positions/technologies of P&W and RR are not that far apart when considering the "end game"ie when the all new aircraft are built. I can see why someone recently suggested that the 2015 engines were "stopgaps".
the cores won't be but perhaps the fans/cowlings will.