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Doubts About The Engine Of The MAX  
User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Posted (2 years 5 months 1 week 6 days 19 hours ago) and read 24838 times:

The following article with the title "Even more doubts about B737MAX" has some detailed and recent information about the upcoming NB engines:
http://aeroturbopower.blogspot.com/2...en-more-doubts-about-b737max.html:

Quote:
"The end result is that you've got a really big gap between a P&W Neo and a CFMi Neo." To clarify: the gap is in favor of the P&W GTF and Airline Economics is quoting an senior industry expert here, who expects the LEAP to have a 4% disadvantage.

Comment: 4% might be at the upper end for the engine alone. But bundled with the disadvantage of the tricky engine installation on the MAX this gap could even become larger in total.

Other (almost weird) info from the article:

- CFM in an attempt to get market share in 2011 fought extreme price battles. They went so low that one customer is reported to have picked the GTF just by applying the principle "what is good, can't be cheap" (because the LEAP was offered at a suspiciously low price).

- The GTF on the MAX might become an option.

- There also seems to be much talk that the lack of MAX commitments might have to do with real deficits of the MAX.

- Even the scenario where Boeing would have to rethink the MAX strategy is discussed (and considered as likely).

- The GTF seems to beat all promises.

148 replies: All unread, showing first 25:
 
User currently offlineMD-90 From United States of America, joined Jan 2000, 8507 posts, RR: 12
Reply 1, posted (2 years 5 months 1 week 6 days 18 hours ago) and read 24622 times:

Quoting rheinwaldner (Thread starter):

- The GTF seems to beat all promises.

I hope it's true--I was born in Connecticut and I'm a P&W fan.


User currently offlinechuchoteur From France, joined Sep 2006, 764 posts, RR: 0
Reply 2, posted (2 years 5 months 1 week 6 days 18 hours ago) and read 24529 times:

Quoting MD-90 (Reply 1):
Quoting rheinwaldner (Thread starter):

- The GTF seems to beat all promises.

I hope it's true--I was born in Connecticut and I'm a P&W fan.

P&W are willing to offer performance guarantees.
That's all that matters really - if it doesn't deliver, they pay.

They've run that engine a lot of hours now, more than almost any other new engine design going into service, so their performance guarantees have substance I would say...


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 3, posted (2 years 5 months 1 week 6 days 18 hours ago) and read 24487 times:

First off aeroturbopower is probably one of the most pro-Airbus aviation blogs there is, so I do take the information with a little bit of apprehension as there typically is an obvious slant compared to Leeham, Scott Hamilton, Jon Ostrower, and Flight Global. Many of its posts sound more like an Airbus sales campaign than anything else. I'm not saying it is a bad blog, just one that shows bias.

I find it interesting that there are claims of 4% difference between the LeapX and PW GTF on the A320NEO. That is a big difference for a side by side comparison. If there was such a discrepency, I'd expect airlines to be very bias towards the GTF. The article's claim that CFMI slashing prices and making its engines virtually free is complete nonsense in my opinion. CFMI is a for profit company and is not selling engines virtually free to maintain market share. Anyone who thinks that is not a very knowledgeable because the overhaul and spares business on engines is not enough to slash prices to virtually free. CFM has about 40% of the A320 NEO market. To me that indicates that the GTF may be better. 4% is an interesting number.

One thing I find interesting is that it states "there is increasing evidence that the PW GTF is exceeding expectations in all aspects of testing". I'd be curious to learn more about that. It would be great for it to be exceeding expectations, although the line all aspects of testing makes no sense. If it exceeds all aspects of testing, then the expectations were not established correctly in the first place. One thing I learned early in my design engineering career is that if you find no failures in your testing, you overdesigned the product and there is more opportunity left. I'd like to learn more about that.

I find it interesting that the article comes up with the conclusion that Boeing is wrong with the 737MAX and they should go back to the drawing board.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinePhxA340 From United States of America, joined Mar 2012, 891 posts, RR: 1
Reply 4, posted (2 years 5 months 1 week 6 days 18 hours ago) and read 24448 times:

Quoting rheinwaldner (Thread starter):
There also seems to be much talk that the lack of MAX commitments might have to do with real deficits of the MAX.

My first issue with this post is that this is a blog .... not really an article. I can write whatever I want on a blog too ... until I see a customer cancel a MAX order because of a 4% short fall, it is all speculation.

Stitch can probably give you a more accurate number but doesn't that MAX have over 800 + commitments ?? That is a pretty solid number.

As far as the price battle - that almost made me laugh "whats good can't be cheap". Ask Ryanair how they feel about their rediculously cheap 737 order. I think they would use the word great.


User currently offlinegarpd From UK - Scotland, joined Aug 2005, 2660 posts, RR: 4
Reply 5, posted (2 years 5 months 1 week 6 days 18 hours ago) and read 24319 times:

Quoting rheinwaldner (Thread starter):
The following article with the title "Even more doubts about B737MAX" has some detailed and recent information about the upcoming NB engines:
http://aeroturbopower.blogspot.com/2...html:

I saw that post before you linked it here. That blog is glaringly Pro-Airbus and at times seems as if it is written someone after gulping down some Airbus brand 100% sugar Cool Aid.

People were dead certain Boeing was making a mistake launching the 737 NG with the same single engine manufacturer. Look how that turned out!

This blog post can be filed under "Irrelevant Fan-Boy post" IMO.

Quoting Roseflyer (Reply 3):

I find it interesting that the article comes up with the conclusion that Boeing is wrong with the 737MAX and they should go back to the drawing board.

What do Boeing know about making airplanes? Airbus are the pros and this blogger knows a lot. Boeing should listen to the both of them!
[/Scarcasm]



arpdesign.wordpress.com
User currently offlinenomadd22 From United States of America, joined Feb 2008, 1866 posts, RR: 0
Reply 6, posted (2 years 5 months 1 week 6 days 17 hours ago) and read 24171 times:

From the gearbox on the GTF being more efficient than Pratt had officially anticipated I had the feeling they were being conservative with their claims. Even with a 2% drop because of a smaller fan, I wondered about their exclusion from the Max.
The blog is a joke, but the fact remains that if Pratt can keep up with the other guys core wise, theyre going to have an advantage.



Andy Goetsch
User currently offlineneutronstar73 From United States of America, joined Mar 2011, 506 posts, RR: 0
Reply 7, posted (2 years 5 months 1 week 6 days 17 hours ago) and read 24065 times:

Quoting Roseflyer (Reply 3):

Absolutely. They are unabashed in their pro-Airbus, anti-CFM tirades. Only reason to read that site is for comedy. Aeroturbopower should not be taken seriously. If you do take it seriously, take it with a kilogram of salt, because I don't think I've ever read a "post" on that site that was in any way complementary to CFM or Boeing...ever.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 8, posted (2 years 5 months 1 week 6 days 17 hours ago) and read 23892 times:

http://www.flightglobal.com/blogs/fl...reaking-boeing-reveals-new-73.html

I am not sure if these is just convenient timing, but flightglobal presented an article where Boeing reveals some real design parameters.

8'' nose extension
Fly by wire spoilers
Tail cone extension
Electronic Bleed Air control
Elevator strengthening

Flightglobal actually provides some facts unlike the blog which had a lot more speculation.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinePresRDC From United States of America, joined Jul 1999, 661 posts, RR: 1
Reply 9, posted (2 years 5 months 1 week 6 days 16 hours ago) and read 23758 times:

Quoting Roseflyer (Reply 3):
The article's claim that CFMI slashing prices and making its engines virtually free is complete nonsense in my opinion. CFMI is a for profit company and is not selling engines virtually free to maintain market share. Anyone who thinks that is not a very knowledgeable because the overhaul and spares business on engines is not enough to slash prices to virtually free.

Recall that, with the exception of spare engines, neither CFMI nor P&W sell engines directly to airlines. The engines are sold to the airframer at a price that is negotiated in a master contract for the specific engine model and does not change for different customers.

What engine manufacturers do, though, is offer credits for a percentage of the engine price that are issued directly to the airline and can, at the airline's option (an option that is usually taken), be converted to cash and wired directly to the airframer to help offset the cost of the aircraft. That percentage is highly negotiated and is typically well north of 65% of the price at which the engine is sold to the airframer.

Both P&W and CFMI offer performance guarantees. It is very much part of the business. Guarantees often include things like engine weight, fuel consumption, climb performance, maintenance cost, etc. The guarantees are typically expressed as rates on a fleet wide average (except for zero event guarantees, such as IFSD, remote site removal, uncontained failure, etc.) and are subject to the airline maintaining certain operating parameters (derate, stage length, etc.).


User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 10, posted (2 years 5 months 1 week 6 days 16 hours ago) and read 23677 times:
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Pratt is said to be holding back a number of percent in SFC on the PW1100G to protect themselves as they cannot afford another engine program that does not meet contractual guarantees. So it's not inconceivable that the PW1100G will be better than Pratt is currently stating.

As to LEAP-X and the MAX, airlines forced Boeing to launch it so they must have faith otherwise they'd have waited for the NSA with GTFs.

I believe Pratt's VP of GTF development was overly optimistic in his opinion that the PW1100G could fit on the 737NG with little to no modification to the airframe. I would not be overly surprised if Boeing's decision to sole-source the LEAP-X was due to the amount of production and design changes necessary to accommodate the PW1100G.


User currently offlinefpetrutiu From United States of America, joined Aug 2007, 884 posts, RR: 0
Reply 11, posted (2 years 5 months 1 week 6 days 16 hours ago) and read 23644 times:

Quoting PhxA340 (Reply 4):
Stitch can probably give you a more accurate number but doesn't that MAX have over 800 + commitments ?? That is a pretty solid number.

Over 1000 now per Boeing: http://boeing.mediaroom.com/index.php?s=43&item=2212


User currently offlineHamlet69 From United States of America, joined Mar 2000, 2744 posts, RR: 58
Reply 12, posted (2 years 5 months 1 week 6 days 16 hours ago) and read 23447 times:

Quoting rheinwaldner (Thread starter):
- The GTF on the MAX might become an option.

Weirdly, this is the only part of the blog that actually has some meat behind it.

At last month's ISTAT conference, there was a lot of talk that Boeing is still considering the GTF as a second option on the MAX. While Boeing has dismissed this publically, there seems to be a lot of respectable sources indicating that the GTF is indeed, at least being looked, with a final "yea or nay" decision expected to come sometime this summer.

Aspire Aviation adds a bit more to this in their recent article here:

http://www.aspireaviation.com/2012/0...ing-continues-to-optimise-737-max/

They mention the potential of a 71" fan for a 737 GTF. I do wonder at that, as from my sources, Boeing can fit up to a 70" before they 'run into issues'.

Guess we'll just have to wait and see. . .

Regards,

Hamlet69



Honor the warriors, not the war.
User currently offline737tdi From United States of America, joined Sep 2007, 843 posts, RR: 1
Reply 13, posted (2 years 5 months 1 week 6 days 15 hours ago) and read 23320 times:
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This has nothing to do with the engines but more with the last two posts.

Boeing best do something about the problems with the horizontal stabalizers on the NG v the Max, we are having a few problems with skin cracking on them. It's not a hard repair but takes the aircraft out of service for a couple of days. Maybe that is part of the "elevator strengthening"?


User currently offlinePlaneAdmirer From United States of America, joined Jul 2009, 564 posts, RR: 0
Reply 14, posted (2 years 5 months 1 week 6 days 15 hours ago) and read 23169 times:

Quoting Stitch (Reply 10):
Pratt is said to be holding back a number of percent in SFC on the PW1100G to protect themselves as they cannot afford another engine program that does not meet contractual guarantees. So it's not inconceivable that the PW1100G will be better than Pratt is currently stating.

While I know this is about the 737, the original post and yours made me think about the GTFon the 777NG. If the GTF is performing as well as rumored, then it may make the 777NG a very competitive offering for some time.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 15, posted (2 years 5 months 1 week 6 days 15 hours ago) and read 23099 times:

Quoting 737tdi (Reply 13):

Boeing best do something about the problems with the horizontal stabalizers on the NG v the Max, we are having a few problems with skin cracking on them. It's not a hard repair but takes the aircraft out of service for a couple of days. Maybe that is part of the "elevator strengthening"?

If you are talking about the cracking and damage caused by the elevator tab system, there is an Airworthiness Directive published that you can read on the FAA website: 2010-17-19. That will all be fixed long before the MAX. AD's usually have a design change and Service Bulletin mandated in about 2 years time to fix the problems.



If you have never designed an airplane part before, let the real designers do the work!
User currently offline737tdi From United States of America, joined Sep 2007, 843 posts, RR: 1
Reply 16, posted (2 years 5 months 1 week 6 days 14 hours ago) and read 22902 times:
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Quoting Roseflyer (Reply 15):
If you are talking about the cracking and damage caused by the elevator tab system, there is an Airworthiness Directive published that you can read on the FAA website: 2010-17-19. That will all be fixed long before the MAX. AD's usually have a design change and Service Bulletin mandated in about 2 years time to fix the problems.




Not that, I was involved in changing all of our elevators. We were doing them on RON every Friday night for what seemed like forever. We got quite good at it, ours have been completed for quite some time. This only addressed the vibration and flutter of the elevator.

What I'm referring to is the lower horiz. stab skin. We are finding small lateral cracks between the ribs. Like stated they are easy to repair with a simple doubler but still take awhile to perform and costly downtime. Don't know if you have ever taken a 737CL or NG to high power but there is a very noticeable difference between the two in relation to stab vibration. I suspect it is due to the hard mounted engines on the NG v the isolator mounted on the CL.


User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 17, posted (2 years 5 months 1 week 6 days 14 hours ago) and read 22891 times:

Quoting Roseflyer (Reply 3):
blogs
Quoting PhxA340 (Reply 4):
blog
Quoting garpd (Reply 5):
blog

This is nor fair. Because they talk about an article in a publication. In fact it is almost zero opinion from aeroturbopower in the blog post. And the opinion that is expressed favours Boeing.

Quoting PhxA340 (Reply 4):
I can write whatever I want on a blog too

But not quoting a publication.

Quoting garpd (Reply 5):
That blog is glaringly Pro-Airbus and at times seems as if it is written someone after gulping down some Airbus brand 100% sugar Cool Aid.

Show some examples. I cant remember.

Quoting neutronstar73 (Reply 7):
If you do take it seriously, take it with a kilogram of salt, because I don't think I've ever read a "post" on that site that was in any way complementary to CFM or Boeing...ever.

So you probably didnt read a post from them at all?

IMO the bias of the readers might have affected a balanced judgment as much as any other bias...


User currently offlinePhxA340 From United States of America, joined Mar 2012, 891 posts, RR: 1
Reply 18, posted (2 years 5 months 1 week 6 days 13 hours ago) and read 22788 times:

Quoting rheinwaldner (Thread starter):
This is nor fair. Because they talk about an article in a publication

It is very fair ... the 'article' comes from the "Blogspot"... This is neither a balanced reveiw nor based on facts , just guesses.

I am all for a healthy debate on the merits of the NEO and MAX but this is clearly biased to the point where it stopped being fun to read after the first few sentences.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 19, posted (2 years 5 months 1 week 6 days 13 hours ago) and read 22688 times:

Quoting rheinwaldner (Reply 17):

Quoting garpd (Reply 5):
That blog is glaringly Pro-Airbus and at times seems as if it is written someone after gulping down some Airbus brand 100% sugar Cool Aid.

Show some examples. I cant remember.

How about the analysis of Delta ordering the 739ER and only comparing it to the A320NEO and A321NEO? That was almost comical bias. When someone tried to point out that a realistic comparison would be versus the A320 or A321, the blogger ignored it and said that since the competition will eventually be operating A320NEOs and A321NEOs, then it is the only logical comparison and the blogger completely ignored the savings of replacing 30 year old 752s with brand new 739ERs and the fact that Virgin America and jetBlue have A320s on order that they will be taking delivery of side by side with A320NEOs.

How about the multiple posts, doubts on MAX, GTF exceeds expectations, Ryanair criticism of the MAX, American and Norweigian defecting from Boeing, etc? It's not that I am selecting a few anti-Boeing and pro Airbus articles, it is that every post on that blog is like this.

Then of course there was the technical analysis of block fuel burn comparison of the A320 vs 738. It was based on ACAPs and conveniently chose the highest MTOW of the A320 vs the lowest fuel capacity restricted 738 and conveniently chose a range and payload that was exactly where the A320 had it's peak performance. That's like saying that the A319 burns less fuel than the A320 when the A320 is artificially limited to the amount of payload that an A319 can. Of course when you ignore the 30 seat advantage and increased payload, the A319 burns less fuel than the A320. However airlines in actualy operating conditions prefer the A320 and its lower CASM.

That blogger searches for anything negative about a Boeing or CFM product and posts it. That blogger also finds everything positive about the GTF and posts it. There are some general posts, but unless they are pointing out straight facts like airline X ordered an airplane or a certain model was launched, most of them follow the pattern. Reading that blog is like watching Fox News and trying to get an understanding of the democratic party's political objectives. Sure there are some facts in there, but a lot more facts that are positive about one side are presented while facts promoting the other side are ignored.

[Edited 2012-04-11 14:20:44]

[Edited 2012-04-11 14:37:39]


If you have never designed an airplane part before, let the real designers do the work!
User currently offlinePresRDC From United States of America, joined Jul 1999, 661 posts, RR: 1
Reply 20, posted (2 years 5 months 1 week 6 days 13 hours ago) and read 22523 times:

Quoting Stitch (Reply 10):
I would not be overly surprised if Boeing's decision to sole-source the LEAP-X was due to the amount of production and design changes necessary to accommodate the PW1100G.

The CFMI 737 contract with Boeing gives CFMI exclusivity on a re-engined 737 platform. That is why CFMI is sole source on that aircraft.


User currently offlineracko From Germany, joined Nov 2001, 4857 posts, RR: 20
Reply 21, posted (2 years 5 months 1 week 6 days 12 hours ago) and read 22477 times:

Quoting Roseflyer (Reply 8):
8'' nose extension

Are we talking a wart like on the A330F or a more elegant solution, i.e. a lengthened gear?


User currently offlineMountainFlyer From United States of America, joined Jul 2005, 476 posts, RR: 0
Reply 22, posted (2 years 5 months 1 week 6 days 12 hours ago) and read 22333 times:

Quoting racko (Reply 21):
Are we talking a wart like on the A330F or a more elegant solution, i.e. a lengthened gear?
This blog says landing gear.

[Edited 2012-04-11 15:27:10]


SA-227; B1900; Q200; Q400; CRJ-2,7,9; 717; 727-2; 737-3,4,5,7,8,9; 747-2; 757-2,3; 767-3,4; MD-90; A319, 320; DC-9; DC-1
User currently offlineCM From , joined Dec 1969, posts, RR:
Reply 23, posted (2 years 5 months 1 week 6 days 12 hours ago) and read 22220 times:

Quoting 737tdi (Reply 13):
Boeing best do something about the problems with the horizontal stabalizers on the NG v the Max

The stab skin cracking issue is already solved and is either being delivered on new 737NGs today, or will begin delivery on new aircraft shortly. It is not something which will need to wait for the MAX.

Quoting racko (Reply 21):
Are we talking a wart like on the A330F

No. The nose gear doghouse is being enlarged (lengthened forward) so the longer gear does not have to extend below the current skin lines. There may be some small blisters incorporated into the NLG doors to accommodate the required space around the tires for a flailing tread, but there will be no A330F-style "box" hanging below the fuselage.


User currently offlineneutronstar73 From United States of America, joined Mar 2011, 506 posts, RR: 0
Reply 24, posted (2 years 5 months 1 week 6 days 7 hours ago) and read 19671 times:

Aeroturbopower is comical in its bias. I swear, I've never read a single article on that "website" that was NOT biased in favor of Airbus or didn't make jabs at GE or CFM. That blog has a ridiculously high Airbus and Rolls Royce bias.

At least from my perspective.


User currently offlinePlanesNTrains From United States of America, joined Feb 2005, 5582 posts, RR: 28
Reply 25, posted (2 years 5 months 1 week 6 days 6 hours ago) and read 19721 times:

Quoting rheinwaldner (Reply 17):
IMO the bias of the readers might have affected a balanced judgment as much as any other bias...

Well, that knife cuts both ways, now doesn't it?  

-Dave



Next Trip: SEA-ABQ-SEA on Alaska
User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 26, posted (2 years 5 months 1 week 6 days 3 hours ago) and read 18778 times:
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I find the blog's bias amusing. Pratt did hold 4% TSFC in reserve. However, they are not there yet. They shouldn't be expected to be there now either. But Pratt didn't change the fan for the fun of it.    That is expensive! It was to improve performance.

Now the interesting time will be this summer when Pratt optimized the PW1500G in the air. Until the compressors and variable area nozzle are co-optimized... There will be room to improve the engine. But while ground state optimization have been performed, the GTF is unusually dependent upon its nacelle for performance. This was partially true with the 787 and will be very true with the A350 in that the nacelle has more impact on TSFC than before. This is just the trend.

Quoting PresRDC (Reply 9):
Recall that, with the exception of spare engines, neither CFMI nor P&W sell engines directly to airlines. The engines are sold to the airframer at a price that is negotiated in a master contract for the specific engine model and does not change for different customers.

But as you know, there are rebates, guarantees, parts prices, and other aspects. Some are as good as a price cut.

Quoting Stitch (Reply 10):
Pratt is said to be holding back a number of percent in SFC on the PW1100G to protect themselves as they cannot afford another engine program that does not meet contractual guarantees. So it's not inconceivable that the PW1100G will be better than Pratt is currently stating.

It should be 4%. However, expect only 1% at EIS with the remainder 'brought in' within 3 or so years.

Quoting Hamlet69 (Reply 12):
While Boeing has dismissed this publically, there seems to be a lot of respectable sources indicating that the GTF is indeed, at least being looked, with a final "yea or nay" decision expected to come sometime this summer.

I have not heard this. If true, it will be interesting to know the contract provisions on how Pratt could put the GTF on the MAX. I suspect this is only rumor.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently onlinesirtoby From Germany, joined Nov 2007, 378 posts, RR: 22
Reply 27, posted (2 years 5 months 1 week 6 days 3 hours ago) and read 18611 times:

Quoting neutronstar73 (Reply 7):
Absolutely. They are unabashed in their pro-Airbus, anti-CFM tirades.
Quoting Roseflyer (Reply 19):
That blogger searches for anything negative about a Boeing or CFM product and posts it.

At least, I found that one, saying a lot of positive things abut the 787 vs. the A330.

http://aeroturbopower.blogspot.com/2...amliner-ready-to-fly-and-kill.html


User currently offlinefaro From Egypt, joined Aug 2007, 1548 posts, RR: 0
Reply 28, posted (2 years 5 months 1 week 6 days ago) and read 17070 times:

Quoting rheinwaldner (Reply 17):
Quoting Roseflyer (Reply 3):
blogs
Quoting PhxA340 (Reply 4):
blog
Quoting garpd (Reply 5):
blog

This is nor fair. Because they talk about an article in a publication. In fact it is almost zero opinion from aeroturbopower in the blog post. And the opinion that is expressed favours Boeing.

  

Read the article people. If they have displayed a certain bias in some of their prior articles, does that mean that every single article will be biased?

This one clearly is more objective and very very interesting. Read, don't bleat.

Faro



The chalice not my son
User currently offlinetravelavnut From Netherlands, joined May 2010, 1613 posts, RR: 7
Reply 29, posted (2 years 5 months 1 week 5 days 22 hours ago) and read 16293 times:

Quoting neutronstar73 (Reply 24):
Aeroturbopower is comical in its bias

Haha!! Pot, meet Kettle   

Quoting Hamlet69 (Reply 12):
Quoting rheinwaldner (Thread starter):
- The GTF on the MAX might become an option.

Weirdly, this is the only part of the blog that actually has some meat behind it.

I hope this actually comes to fruition. I really have a soft spot for P&W  



Live From Amsterdam!
User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 30, posted (2 years 5 months 1 week 5 days 22 hours ago) and read 15932 times:

Quoting Roseflyer (Reply 8):
I am not sure if these is just convenient timing, but flightglobal presented an article where Boeing reveals some real design parameters.

I have noticed the articles about this. But the published information seems not to be new. IIRC these things have been mentioned beforeby Boeing .

Quoting Stitch (Reply 10):
I would not be overly surprised if Boeing's decision to sole-source the LEAP-X was due to the amount of production and design changes necessary to accommodate the PW1100G.

This seems to be correct, IMO.
It seems like squaring the circle to mount a huge fan to the 737. And the huge fan is the essential feature of the GTF. In fact the GTF is primarily invented to raise the fansize without getting in troubles with too much speed at the fan tips.

Quoting PhxA340 (Reply 18):
It is very fair ... the 'article' comes from the "Blogspot"... This is neither a balanced reveiw nor based on facts , just guesses.

The article does not come from the blogspot. It quotes experts that have made statments at ISTAT.

Quoting Roseflyer (Reply 19):
How about the analysis of Delta ordering the 739ER and only comparing it to the A320NEO and A321NEO?

Strange, I admit.

Quoting Roseflyer (Reply 19):
How about the multiple posts, doubts on MAX, GTF exceeds expectations, Ryanair criticism of the MAX, American and Norweigian defecting from Boeing, etc?

Ok, about these things you can report without any bias by just stating the truth and yet for a Boeing fanboy it must sound like biased junk. I don't know how to write about these things in a balanced way and without questioning Boeing's position at the same time.

Quoting Roseflyer (Reply 19):
Then of course there was the technical analysis of block fuel burn comparison of the A320 vs 738.

Derailing Boeings claims about the NG is really not complicated and does neither require bias nor twisted numbers. Any analysis that shows these two aircraft to be more or less on par is probably closer to the truth than the challenged numbers from Boeing PR.

Quoting PlanesNTrains (Reply 25):
Well, that knife cuts both ways, now doesn't it?
-Dave

Fair remark.
I am the voice that has "told you so", in case the future will show that the MAX will not be the last response to the NEO from Boeing. If not, I will admit that I was wrong.

I have always said that:

- The 737 is penalized significantly by the design heritage from the 60. It is a lifecycle handicap. The 737 did extremely well and had an extremely long run. One day it will be inadequate to cope with the future's requirement. I just say this is now. The quoted 4t weight gain, as leaked by SUH at ISTAT, might underline this.

- In our area we judge technical solutions in these two areas: "fit for purpose" and " fit for future". The 737 would only qualify for the former and not for the latter IMO. The A320 does qualify for both.

- It will take some miracolous effort from Boeing's side to keep parity while taking the 737 for another round.

- The focus on the new GTF/high b/r engines for the next round exactly hits the 737 at its weakest point (ground clearance).

- Boeings is now going too far, in attempting to keep contact with two newer models by upgrading two older designs. I dare to say that they won't keep their today 737&777 customers that way (notice this is not the same like saying: I wish that they won't keep their customer, because this is clearly not what I wish. A fanboy would wish Boeing to suffer. This is not my position. Not at all. I try to be a balanced commentor).

Quoting lightsaber (Reply 26):
So it's not inconceivable that the PW1100G will be better than Pratt is currently stating.
It should be 4%. However, expect only 1% at EIS with the remainder 'brought in' within 3 or so years.

So our Pratt expert here basically backs up the main claim of the article.

Quoting PhxA340 (Reply 18):
I am all for a healthy debate on the merits of the NEO and MAX but this is clearly biased to the point where it stopped being fun to read after the first few sentences.

So debate with lightsaber about the 4%.

I would add that these 4% seem not to be the gap between the Leap and the GTF. IIRC it has been reported that even defensive estimations for the GTF would reveal a gap to the Leap. And these 4% seem to be just the gap between the safely estimated and the more and more realisticly to be expected capability of the GTF. Which would lead to an even larger gap between this emerging wonder-GTF and the Leap.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 31, posted (2 years 5 months 1 week 5 days 20 hours ago) and read 14946 times:

Quoting Roseflyer (Reply 3):
First off aeroturbopower is probably one of the most pro-Airbus aviation blogs there is,
Quoting garpd (Reply 5):
That blog is glaringly Pro-Airbus and at times

This being the first blog I’ve read from this author I’ve no idea to his bias, but it’s certainly not the first time I’ve read about Pratt holding back the true potential of the GTF.

Quoting lightsaber (Reply 26):
Quoting Stitch (Reply 10):Pratt is said to be holding back a number of percent in SFC on the PW1100G to protect themselves as they cannot afford another engine program that does not meet contractual guarantees. So it's not inconceivable that the PW1100G will be better than Pratt is currently stating.
It should be 4%. However, expect only 1% at EIS with the remainder 'brought in' within 3 or so years.

If this is indeed the case, then it’s going to put Boeing in a very difficult spot. We already know that that updating the engine on the 737 is much more involved than on the A320, with both the airframe and engine requiring significant modification costing both time and money.

A 4% difference has the potential to be a real game changer, but the question is; what can Boeing do about it? Pratt have no motivation to guarantee anything more than they have already so hypothetically Boeing could offer a GTF-Max tomorrow and then spend 2 years and vast amounts of cash developing it only for the 4% to never materialise.

The problem then is, what happens if the GTF does turn out to have a 4% advantage, by the time this will be confirmed the Max will likely be in testing if not in service – too late for Boeing to do anything about it, other than re-max the max.

A little OT, but as an added bonus for Airbus. Should this turn out to be correct, then the GTF powered A321NEO will be an absolutely perfect 757 replacement.


User currently offlineRickNRoll From Afghanistan, joined Jan 2012, 830 posts, RR: 0
Reply 32, posted (2 years 5 months 1 week 5 days 19 hours ago) and read 14270 times:

Quoting garpd (Reply 5):
People were dead certain Boeing was making a mistake launching the 737 NG with the same single engine manufacturer. Look how that turned out!

Look how the 787 turned out. The GENx was late and under performing, but the RR was doing better. Putting all your money on one square might pay off better, but it can make your losses bigger, too.


User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 33, posted (2 years 5 months 1 week 5 days 19 hours ago) and read 14241 times:
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Quoting rheinwaldner (Reply 30):
One day it will be inadequate to cope with the future's requirement. I just say this is now. The quoted 4t weight gain, as leaked by SUH at ISTAT, might underline this.

Daniel Tseng's sources at Boeing have stated that SUH is wrong and the real weight gain is much smaller.



Quoting Daysleeper (Reply 31):
The problem then is, what happens if the GTF does turn out to have a 4% advantage, by the time this will be confirmed the Max will likely be in testing if not in service – too late for Boeing to do anything about it, other than re-max the max.

If lightsaber is correct, that 4% likely won't become available until after 2020. CFM won't be standing still themselves during that time and that fuel burn advantage will have it's greatest impact on longer stage lengths. And the A320 already has the advantage on long stage lengths compared to the 737NG, and yet the 737NG is still in that fight thanks to a 2000 liter greater fuel load that allows it to at times outfly the A320-200 when winds are adverse.

So should the PW1100G gain all 4%, that will favor that engine on the A320-200 and (especially) A321-200 on longer missions. Might actually make the A321-200neo a true 757-200 replacement in terms of nominal range.

But Boeing will surely still sell plenty of 737MAXs for shorter missions and will probably still score some orders with long-distance carriers, as well, since the MAX will load even more fuel than the NG.


User currently offlineRickNRoll From Afghanistan, joined Jan 2012, 830 posts, RR: 0
Reply 34, posted (2 years 5 months 1 week 5 days 19 hours ago) and read 14026 times:

Quoting PhxA340 (Reply 18):

It is very fair ... the 'article' comes from the "Blogspot"... This is neither a balanced reveiw nor based on facts , just guesses.

I am all for a healthy debate on the merits of the NEO and MAX but this is clearly biased to the point where it stopped being fun to read after the first few sentences.

The article is in Aviation News, which is subscription only. We are relying on the blogger making fair quotes from the article, which he has read and we haven't. If the quotes are accurate, then Boeing has a problem.


User currently offlinePhxA340 From United States of America, joined Mar 2012, 891 posts, RR: 1
Reply 35, posted (2 years 5 months 1 week 5 days 19 hours ago) and read 14055 times:

Quoting Daysleeper (Reply 31):
The problem then is, what happens if the GTF does turn out to have a 4% advantage, by the time this will be confirmed the Max will likely be in testing if not in service – too late for Boeing to do anything about it, other than re-max the max.

The 737NGs being built today are ~ 10% more efficient that the ones built in the 90s. You can always make changes if there are shortfalls during production. I am still a big believer that the NEO is going to be the better plane for long distances and the MAX will have the advantages for short trips.


User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 36, posted (2 years 5 months 1 week 5 days 19 hours ago) and read 13811 times:
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Quoting RickNRoll (Reply 32):
Look how the 787 turned out. The GENx was late and under performing, but the RR was doing better.

Both engines were late and the Rolls-Royce Trent 1000's initial SFC miss was said to be almost double that of the GEnx-1B. GE did have significantly more work to do to recover that miss, however.


User currently offlineneutronstar73 From United States of America, joined Mar 2011, 506 posts, RR: 0
Reply 37, posted (2 years 5 months 1 week 5 days 18 hours ago) and read 13538 times:

Quoting travelavnut (Reply 29):
Haha!! Pot, meet Kettle

Please be gone. You add nothing to the thread, except a targeted name calling.

Meanwhile:

I think CFM knows the constraints they are up against. I'm sure Boeing does, too. I'm particularly interested to see how flight tests go with P&W and the MRJ GTF variant.


User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 38, posted (2 years 5 months 1 week 5 days 18 hours ago) and read 13480 times:

Quoting Stitch (Reply 33):
Quoting rheinwaldner (Reply 30):
One day it will be inadequate to cope with the future's requirement. I just say this is now. The quoted 4t weight gain, as leaked by SUH at ISTAT, might underline this.

Daniel Tseng's sources at Boeing have stated that SUH is wrong and the real weight gain is much smaller.

Sorry, Daniel Tseng does not nearly qualify to be in the same league as SUH. SUH knows what he knows because Boeing has told him so as potential customer. And SUH is not biased. His advice should be taken very seriously by Boeing.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 39, posted (2 years 5 months 1 week 5 days 18 hours ago) and read 13450 times:

Quoting rheinwaldner (Reply 30):
I would add that these 4% seem not to be the gap between the Leap and the GTF. IIRC it has been reported that even defensive estimations for the GTF would reveal a gap to the Leap. And these 4% seem to be just the gap between the safely estimated and the more and more realisticly to be expected capability of the GTF. Which would lead to an even larger gap between this emerging wonder-GTF and the Leap.

I am now really confused. The basis for the article was that the GTF is expected to have 4% advantage over the LeapX on the A320NEO according to an expert.

Now back to commenting on the actual article.

What I really call into question is that if this 4% is true, why are the orders for the GTF and LeapX split almost 50-50 on the NEO? It could be other factors such as reliability, maintenance, spares, support, etc. As an aside note, GTFs have been around for decades. They have only ever been used commercially in one application which was the BAE-146. That airplane suffered from engine reliability problems due to the complexity of the gearbox and all the cooling required with it. Such factors counteracted the efficiency benefits of a GTF. Technology has changed and PW hopes to have the winning combo to overcome some of the drawbacks of the GTF. When it comes to adding high speed moving parts to an engine, reliability is going to suffer, so that is just one possibility for why airlines may choose a LeapX even if there is an efficiency advantage there are other factors. This is all speculation on my part.

The article then talks about how the MAX is at such a disadvantage for not having the GTF. This is where I am seeing the bias in either Aeroturbopower or the quoted Airline Economics article. If all the Airbus customers were going for the GTF, then I would definitely understand the argument that Boeing made a poor decision by going LeapX only. However, Airbus appears to have parity between the two engines. The MAX does have some disadvantages with ground clearance, so I understand that they likely will not derive as much benefit from the new engines as Airbus will, however I am just stating that the claims of the LeapX being the wrong decision are not adequately justified. I am curious if a GTF is being considered for the MAX or not.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 40, posted (2 years 5 months 1 week 5 days 18 hours ago) and read 13333 times:

Quoting Stitch (Reply 33):
If lightsaber is correct, that 4% likely won't become available until after 2020. CFM won't be standing still themselves during that time and that fuel burn advantage will have it's greatest impact on longer stage lengths. And the A320 already has the advantage on long stage lengths compared to the 737NG, and yet the 737NG is still in that fight thanks to a 2000 liter greater fuel load that allows it to at times outfly the A320-200 when winds are adverse.

Why would it be 2020? Final versions of the GTF are expected to be flying next year so in a best case scenario it’s would be reaching its potential in 2016. In a worst case, 3 years from the NEO’s EIS would put it at 2018.

In regards to the CFM improvements, although I don’t doubt that there will be future PIPs I can’t see any reason as to why they would be motivated to rush them onto the Max. Instead I see them concentrating on producing PIP’s for the original 1C version as fitted to the NEO and C919 as this is where they face competition and due to the substantial changes required to make the engine work on the 737, I’d say its highly unlikely that these PIPs would be applicable to the 1B.

There is also the time aspect, the GTF is at least a year if not two ahead in development, therefore I wouldn’t expect them to introduce any PIPs until 2019/2020 for the 1C and even later for the 1B which would give the NEO and Pratt a couple of years to make a dent in the Max’s market share.

Quoting Stitch (Reply 33):
So should the PW1100G gain all 4%, that will favor that engine on the A320-200 and (especially) A321-200 on longer missions. Might actually make the A321-200neo a true 757-200 replacement in terms of nominal range.

I agree completely, infact if the recent range increase for the NEO is applicable to both engines, then the A321NEO-GTF might even have legs on the 752.

Quoting Stitch (Reply 33):
But Boeing will surely still sell plenty of 737MAXs for shorter missions and will probably still score some orders with long-distance carriers, as well, since the MAX will load even more fuel than the NG.
Quoting PhxA340 (Reply 35):
I am still a big believer that the NEO is going to be the better plane for long distances and the MAX will have the advantages for short trips.

I’m not so sure if the short range/long range difference is still the case for the Max and NEO, however I am sure that the Max is going to sell in significant numbers and be a financial success for Boeing.


User currently offlinemham001 From United States of America, joined Feb 2005, 3650 posts, RR: 5
Reply 41, posted (2 years 5 months 1 week 5 days 17 hours ago) and read 13272 times:

Quoting rheinwaldner (Reply 38):
Sorry, Daniel Tseng does not nearly qualify to be in the same league as SUH. SUH knows what he knows because Boeing has told him so as potential customer. And SUH is not biased. His advice should be taken very seriously by Boeing.

That's right, SUH would never hype some numbers (real or imagined) to gain some sort of a benefit for himself. Not his style. Nope. No way..


User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 42, posted (2 years 5 months 1 week 5 days 17 hours ago) and read 13249 times:

Quoting rheinwaldner (Reply 30):
And the huge fan is the essential feature of the GTF. In fact the GTF is primarily invented to raise the fansize without getting in troubles with too much speed at the fan tips.

I think you are about half right.

A lot of the reading I'm doing these days on the topic is more about how the fact that the fan spins at its slower optimum speed while the core spins at its faster optimum speed (which is three times faster, and some are suggesting 4x or 5x in the future) is at least as much of a game changer if not more.

It means you need fewer stages in the engine, which gets rid of a lot of heavy, expensive and high maintenance parts, mainly compressor and turbine blades, but also extra spools, bearings, case sections, etc. And as Rolls will tell you, a shorter spool doesn't need to be as rigid as a longer spool and thus it is even lighter, so there are knock-on benefits.

Some complain about the heavy, expensive and maintenance gearing of the GTF, but one important point is you are trading off parts that are lifetime limited such as blades for ones that Pratt says are not lifetime limited, namely the gears. I don't know if Pratt guarantees the gears for life or not, but it'd be interesting to know.

Quoting RickNRoll (Reply 34):
The article is in Aviation News, which is subscription only. We are relying on the blogger making fair quotes from the article, which he has read and we haven't. If the quotes are accurate, then Boeing has a problem.

I think you are making a good point about us relying on the blogger, but I really don't see any news here.

Those who have been following know that the GTF has the strengths pointed out above yet some concerns about the gearing itself and concerns that Pratt is playing it safe in more traditional areas such as materials and core design.

They also know that CFMi is taking a lot of risk in materials, in particular the use of CMCs (cermic matrix composites) in the turbine, and is having to tweak almost everything on the engine to keep up with Pratt.

We also know that it looks like the MAX may have advantages on longer stage lengths whereas NEO may have advantages on shorter stage lengths.

So, no news here.

None of us knows how this particular game will turn out, and we won't till after the MAX ships, which is planned to be a year and a half after NEO ships.



Inspiration, move me brightly!
User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 43, posted (2 years 5 months 1 week 5 days 17 hours ago) and read 13151 times:

Quoting Roseflyer (Reply 39):
What I really call into question is that if this 4% is true, why are the orders for the GTF and LeapX split almost 50-50 on the NEO?

The performance advantage isn’t guaranteed, I understand this to be “Pratt’s comeback” after over promising and under delivering on previous projects they really wanted to get this one right so this time round, they are planning on over delivering.

So with no guaranteed advantage, Pratts history of over-promising and as you mention yourself the possibly of maintenance issues then I wouldn’t expect them to have a lead in the order numbers. In fact, all things considered I believe they are doing well to maintain 50% at this stage.


User currently offlineastuteman From United Kingdom, joined Jan 2005, 10038 posts, RR: 96
Reply 44, posted (2 years 5 months 1 week 5 days 17 hours ago) and read 13143 times:
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Quoting Stitch (Reply 33):
If lightsaber is correct, that 4% likely won't become available until after 2020. CFM won't be standing still themselves during that time


Not sure I get this. The GTF will EIS in 2013. So IF (and I stress if) there is 4% up Pratt's sleeve, it should be pretty much manifest by the EIS of the A320NEO. Of course this is an "if".

Quoting Stitch (Reply 33):
But Boeing will surely still sell plenty of 737MAXs for shorter missions and will probably still score some orders with long-distance carriers, as well, since the MAX will load even more fuel than the NG.

Don't disagree, to be honest. I must admit to be eagerly anticipating the MAX's specs, which I believe should be around by the end of the year, to see what has, or is pledged to be, done.

Quoting travelavnut (Reply 29):
Haha!! Pot, meet Kettle

The most eyebrow raising bit of this whole thread to me is watching the same people get "holier than thou" about this allegedly biased blog who would be all over a blog biased in the other direction like a rash. Circuses couldn't provide better, to be honest.

Quoting neutronstar73 (Reply 37):
Please be gone. You add nothing to the thread, except a targeted name calling.

All references to "direct hits" studiously avoided....  
Rgds


User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 45, posted (2 years 5 months 1 week 5 days 17 hours ago) and read 13168 times:
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Quoting rheinwaldner (Reply 38):
Sorry, Daniel Tseng does not nearly qualify to be in the same league as SUH. SUH knows what he knows because Boeing has told him so as potential customer.

Why would Boeing only tell SUH, a potential customer, that the plane is 4 tons over weight and not tell the actual customers the same? None of them, to my knowledge, have released any statements noting such an overage.

Daniel Tseng claims he has spoken with Boeing engineers and those engineers tell him the plane is not that heavy. I give the opinion of Boeing's engineers a bit more weight than I do SUH. *shrug*



Quoting Daysleeper (Reply 40):
In regards to the CFM improvements, although I don’t doubt that there will be future PIPs I can’t see any reason as to why they would be motivated to rush them onto the Max. Instead I see them concentrating on producing PIP’s for the original 1C version as fitted to the NEO and C919 as this is where they face competition and due to the substantial changes required to make the engine work on the 737, I’d say its highly unlikely that these PIPs would be applicable to the 1B.

CFM is going to sell a hell of a lot more engines on the MAX then they will on the C919. I would not be surprised if they sell more engines on the MAX than the neo. CFM would be insane to NOT focus on the LEAP-X1B because that is where they're going to be making the bulk of their money.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 46, posted (2 years 5 months 1 week 5 days 16 hours ago) and read 12983 times:

Quoting Stitch (Reply 45):
CFM is going to sell a hell of a lot more engines on the MAX then they will on the C919. I would not be surprised if they sell more engines on the MAX than the neo. CFM would be insane to NOT focus on the LEAP-X1B because that is where they're going to be making the bulk of their money.

As I said, I don’t doubt that they will indeed develop PIPs I just believe that they won’t materialise until at least 2 or 3 years after the GTF has received its first round of updates. Let’s also not forget that Pratt aren’t going to be staying still either, it’s perfectly possible that they could counter any CFM PIP with one of their own which would maintain the advantage.


User currently offlinePlanesNTrains From United States of America, joined Feb 2005, 5582 posts, RR: 28
Reply 47, posted (2 years 5 months 1 week 5 days 15 hours ago) and read 12866 times:

Quoting astuteman (Reply 44):
Circuses couldn't provide better, to be honest.

Sure, but again, it seems to go both ways. Of course, that's true everywhere. When you listen to political commentary, they will throw someone under the bus every time - unless they say something they agree with. Then it's "Except they are right THIS TIME." lol

-Dave



Next Trip: SEA-ABQ-SEA on Alaska
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 48, posted (2 years 5 months 1 week 5 days 15 hours ago) and read 12776 times:

Quoting Daysleeper (Reply 40):
In regards to the CFM improvements, although I don’t doubt that there will be future PIPs I can’t see any reason as to why they would be motivated to rush them onto the Max. Instead I see them concentrating on producing PIP’s for the original 1C version as fitted to the NEO and C919 as this is where they face competition and due to the substantial changes required to make the engine work on the 737, I’d say its highly unlikely that these PIPs would be applicable to the 1B.

That is a logical statement, but another factor is that the 737 is a higher production rate airplane and has more money to fund research and development. Boeing pays for CFM to make Performance Improvements to the airplane. CFM also earns huge amounts of money selling those improvements via retrofit Service Bulletins. The purchases go beyond the initial sales campaign.

Although it may seem true, I don't believe that CFM puts more money into development on the A320 variant of the engine or creates PIPs faster for the A320 variant than the Boeing variant. I don't see them doing that when looking at the CFM56 vs V2500 competition.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 49, posted (2 years 5 months 1 week 5 days 14 hours ago) and read 12680 times:

Quoting Roseflyer (Reply 48):
Although it may seem true, I don't believe that CFM puts more money into development on the A320 variant of the engine or creates PIPs faster for the A320 variant than the Boeing variant. I don't see them doing that when looking at the CFM56 vs V2500 competition.

That’s not what I said, my point was that they have more to gain by improving the 1C as there is a competitor, where as they are going to sell the 1B regardless. And again, that’s not to say that they won’t develop PIPs for it, I just think given the added complexity and its later EIS they won’t be available until at least 2 years after the GTF has received its initial update thus giving Pratt and Airbus yet more time to eat into the Max’s market share.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 50, posted (2 years 5 months 1 week 5 days 14 hours ago) and read 12626 times:

Quoting astuteman (Reply 44):


Not sure I get this. The GTF will EIS in 2013. So IF (and I stress if) there is 4% up Pratt's sleeve, it should be pretty much manifest by the EIS of the A320NEO. Of course this is an "if".

I think PW is in a very good spot with the GTF in that it will begin operation and production at a much slower rate than the LeapX will. The GTF will first power the Cseries. While they ramp up their production rate and go through the rapid design revision process that comes with new designs, they will not be at maximum production rate. I think that gives them a lot more flexibility and so many of the early teething issues with the engine should be worked out by the EIS of the A320NEO.

LeapX is going to be powering the C919 and A320NEO in the same time frame. I personally believe CFMI has less of a challenge since it is heavily based on the CFM56, which is an engine they have already perfected. Either way, I don't see either engine falling flat at EIS of the A320NEO or 737NG.

Quoting astuteman (Reply 44):

The most eyebrow raising bit of this whole thread to me is watching the same people get "holier than thou" about this allegedly biased blog who would be all over a blog biased in the other direction like a rash. Circuses couldn't provide better, to be honest.

Some of the comments that were posted were rather off base in my opinion which warranted comments on the blog being biased.

"The 737max has an exclusive agreement with an engine that the majority of sources claim cannot compete with the P&W GTF, even before taking into account the implications of making the LEAP X smaller for the 737max."


I am not seeing a majority of sources claim that the LeapX can't compete with the PW GTF. I saw them talking about one source giving a 4% difference between the two engines, yet still the order book does not reflect even reflect that.

The blogger does report many facts, but there is an obvious slant about which facts are reported.
.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 51, posted (2 years 5 months 1 week 5 days 9 hours ago) and read 12315 times:
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Quoting Daysleeper (Reply 49):
That’s not what I said, my point was that they have more to gain by improving the 1C as there is a competitor, where as they are going to sell the 1B regardless.

Well CFM does have competition for the 1B in the form of the PW1100G.  

That being said, yes, Pratt could have all of the "reserve" SFC in production by the time the LEAP-X enters service, but them's the breaks and it will give CFM an incentive to push out PiPs.


User currently offlineHamlet69 From United States of America, joined Mar 2000, 2744 posts, RR: 58
Reply 52, posted (2 years 5 months 1 week 5 days 8 hours ago) and read 12066 times:

Quoting lightsaber (Reply 26):
I have not heard this. If true, it will be interesting to know the contract provisions on how Pratt could put the GTF on the MAX. I suspect this is only rumor.

Personally, I have not heard it either. And like you, I'd keep it at the 'rumor' stage until we hear something more substantial. However, as I said, it has been reported (at least, repeated) in a few sources that I usually find (mostly) credible. Which is why I think there might be at least a small kernal of truth behind the rumor.

One such article is here:

http://www.bizjournals.com/albuquerq...g-could-be-considering-geared.html

Although it comes from the New Mexico Business Weekly, the actual article was written by Steve Wilhelm from the Puget Sound Business Journal. He uses Scott Hamilton a lot (probably too much) for his sources. While I don't always see eye-to-eye with Mr. Hamilton's analysis', he does have far more contacts than I do  

(I read this article when it came out, but purposely did not post it here on A.net due to the LH reference, as I figured it'd get both camps up in arms. As we seem to have crossed that bridge on this thread already, it might as well get shared.)

Quoting Daysleeper (Reply 40):
In regards to the CFM improvements, although I don’t doubt that there will be future PIPs I can’t see any reason as to why they would be motivated to rush them onto the Max.

*shrug* History tells a different story. GE is sole-source on the current 737NG, as well as the 777LR's. They have produced PIP's for those engines over the years at the same rate they have done so for a platform where they have competition. I see no reason the MAX will be any different.


Regards,

Hamlet69



Honor the warriors, not the war.
User currently offlineJoeCanuck From Canada, joined Dec 2005, 5471 posts, RR: 30
Reply 53, posted (2 years 5 months 1 week 5 days 7 hours ago) and read 11959 times:

CFM is under a ton of pressure to make sure they at least meet specs right out of the box...and, like Pratt, I would be surprised if they aren't holding back on their specs...they'd be crazy not to.

While I'm a huge fan of the GTF, I find it a bit odd that it seems suddenly, CFM is the underdog in this race. The CFM 56 and GE34 engine lines are among the most successful in history...in sales, performance, economy and reliability. With their track record, if they say they can deliver...I'm inclined to believe them. Add to that list the GE90 and GEnX...and you have one heck of a lot of success to back up any claim they make.

As we all should know by now, fan size isn't the ultimate determining factor in efficiency. RR is spinning a smaller than optimum fan faster to maintain their XWB bypass ratio on the -1000 with a larger core...and they claim without any loss inefficiency.

One thing a bigger fan will always have is a lower noise signature...but since most current engines meet future noise standards, I don't think that will be a deal breaker.

As we've seen so often, bad news seems to be more entertaining than good news...this story seems to be much ado about nothing.



What the...?
User currently offlineastuteman From United Kingdom, joined Jan 2005, 10038 posts, RR: 96
Reply 54, posted (2 years 5 months 1 week 5 days 6 hours ago) and read 11848 times:
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Quoting Roseflyer (Reply 50):
Some of the comments that were posted were rather off base in my opinion which warranted comments on the blog being biased.

I have no issue with that.
Some of those dismissing this blog out of hand though would be all over it like a rash if the bias were in the other direction. For what it's worth, you're not one of them

Rgds


User currently offlineEPA001 From Netherlands, joined Sep 2006, 4739 posts, RR: 39
Reply 55, posted (2 years 5 months 1 week 5 days 5 hours ago) and read 11736 times:
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Quoting astuteman (Reply 54):
Some of those dismissing this blog out of hand though would be all over it like a rash if the bias were in the other direction

Well, that is the "normal pattern" we usually see here on A-net. The "usual suspects" have again not let us down. Which was to be expected and is also part of the fun reading topics out here.  .

On the subject itself I would say that the GTF could by concept always have an advantage, but that is just theoretical. If P&W can deliver upon this, they are in a very comfortable position. If they can't, the situation for CFM might not be that bad as the blog (which is based on another article) suggests. Only time will tell, and we will have to be patient in order to see the outcome being unfolded.  

How much that unfolding will really hurt the MAX vs. the NEO remains to be seen since the engine performance is only one of many reasons for an airline to select either the NEO or the MAX as the aircraft of choice in that segment of the market.


User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 56, posted (2 years 5 months 1 week 5 days 4 hours ago) and read 11677 times:

Quoting Stitch (Reply 33):
that fuel burn advantage will have it's greatest impact on longer stage lengths.

Why? A better SFC pays back from the first meter of the taxi run.

Quoting Roseflyer (Reply 39):
I am now really confused. The basis for the article was that the GTF is expected to have 4% advantage over the LeapX on the A320NEO according to an expert.

I think lightsaber mentioned 4% as the difference between the initial, conservative estimations for the GTF and the more and more realistic peformance some years later.

Quoting Roseflyer (Reply 39):
What I really call into question is that if this 4% is true, why are the orders for the GTF and LeapX split almost 50-50 on the NEO?

Because they could have been sld dirt cheap. We have indications for this.

Quoting Stitch (Reply 45):
Why would Boeing only tell SUH, a potential customer, that the plane is 4 tons over weight and not tell the actual customers the same?

SUH got the same customer documentation any other airline got too. The 4t must come from there. In this docu there obviously was other data that seemed credible enough for other airlines to order the MAX.

IMO this 4t/4% will create a A350MK1/787 situation in the medium term:
The MAX will never gain back the already lost ground (several lost customers, between 500 and 1000 less units just because of the later EIS) and after some years the gap (in orders) will accentuate more and more until Boeing stands before a pile of broken glass.


User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 57, posted (2 years 5 months 1 week 5 days 4 hours ago) and read 11656 times:

Quoting Daysleeper (Reply 43):
The performance advantage isn%u2019t guaranteed, I understand this to be %u201CPratt%u2019s comeback%u201D after over promising and under delivering on previous projects they really wanted to get this one right so this time round, they are planning on over delivering.

Right, but we can't have our cake and eat it too. If Pratt isn't willing to sign up to the margin, certain bloggers shouldn't act as if it's a certainty.

As Astuteman said, we should know soon enough, and long before either NEO or MAX are in the air.

Quoting EPA001 (Reply 55):
On the subject itself I would say that the GTF could by concept always have an advantage, but that is just theoretical.

Indeed. Roseflyer already mentioned how GTFs already exist but the best-known implementation suffered from poor reliablity up front so it wasn't persued any further, so that theoretical advantage needs to be proven out, as I feel Pratt will.



Inspiration, move me brightly!
User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 58, posted (2 years 5 months 1 week 5 days 3 hours ago) and read 11549 times:

Quoting Revelation (Reply 57):
Right, but we can't have our cake and eat it too. If Pratt isn't willing to sign up to the margin, certain bloggers shouldn't act as if it's a certainty.

Then ignore the blog and its conclusions and discuss the POTENTIAL 4% advantage the GTF may have .

Quoting Revelation (Reply 57):
As Astuteman said, we should know soon enough, and long before either NEO or MAX are in the air.

Why? As has been discussed the likely course of events would be for the GTF to launch on spec next year and then for a PIP to follow around 2016, meaning the NEO would be able to take full advantage of it at launch and the Max would be in late stages of development.

[Edited 2012-04-13 00:18:05]

User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 59, posted (2 years 5 months 1 week 5 days 1 hour ago) and read 11375 times:

Quoting Revelation (Reply 42):
Quoting rheinwaldner (Reply 30):And the huge fan is the essential feature of the GTF. In fact the GTF is primarily invented to raise the fansize without getting in troubles with too much speed at the fan tips.
I think you are about half right.

A lot of the reading I'm doing these days on the topic is more about how the fact that the fan spins at its slower optimum speed while the core spins at its faster optimum speed (which is three times faster, and some are suggesting 4x or 5x in the future) is at least as much of a game changer if not more.

If the fan would be as big as the turbine, the optimum speed of both would be the same. As the fan grows, a different speed becomes desireable. The GTF so to speak is a key-enabler to get large fan sizes. As it is the point to operate larger fans without the usual penalities and exacty larger fans are prevented on the 737 I would go as far and say, that the GTF on the 737 is pointless.

Ok, I know Pratt would mount their GTF on the 737 and Boeing might do it for the sake of customer wishes. But the benefits would not come to full effect..

Quoting Revelation (Reply 42):
They also know that CFMi is taking a lot of risk in materials, in particular the use of CMCs (cermic matrix composites) in the turbine, and is having to tweak almost everything on the engine to keep up with Pratt.

IMO the probem is that the parity CFM would achieve by extreme efforts would erode away anyway after some years, as nothing will stop Pratt to slowly PIP'ing in their GTF the initially unfeatured Leap features. In 2016 CFM might keep parity by sophisticated features in other areas. But as soon as Pratt will make use of them too, the gap will not be bridgeable anymore, except by a CFM GTF...


User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 60, posted (2 years 5 months 1 week 4 days 20 hours ago) and read 11119 times:
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Quoting rheinwaldner (Reply 56):
IMO this 4t/4% will create a A350MK1/787 situation in the medium term:
The MAX will never gain back the already lost ground (several lost customers, between 500 and 1000 less units just because of the later EIS) and after some years the gap (in orders) will accentuate more and more until Boeing stands before a pile of broken glass.


One of the "a.net truths" is that airlines base their purchasing decisions on an airframe's fuel burn. Of course, "a.net truths" are anything but, which is why there is more than one airframe model in service today.  

It's no secret Pratt is holding back SFC. So per "a.net truth", the only narrowbody planes that should be securing orders are the CSeries, the MRJ, the MS-21 and the A320neo with PW1100G power. And yet interest in the CSeries remains moribund, the MRJ is almost totally dependent on AX, and the only airlines buying the MS-21 are Russian. I also believe CFM has secured more A320neo propulsion system orders than Pratt.

The A350MkI went down because it lost RFPs to some major carriers (QF, SQ) and because it left Airbus with no offering in the 250-350 seat market (as the A340 was not going to continue production long-term). The 737MAX is winning RFPs from major carriers and it keeps Boeing in the 125-200 seat market.

So I strongly disagree with your opinion and we shall let history sort out who was right.  

[Edited 2012-04-13 07:18:08]

User currently offlinePlaneAdmirer From United States of America, joined Jul 2009, 564 posts, RR: 0
Reply 61, posted (2 years 5 months 1 week 4 days 20 hours ago) and read 11015 times:

Quoting Daysleeper (Reply 58):
Then ignore the blog and its conclusions and discuss the POTENTIAL 4% advantage the GTF may have

If it's going to be a hypothetical discussion, why not make it a POTENTIAL 10% advantage or even 15% or for that matter 1-2%?


User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 62, posted (2 years 5 months 1 week 4 days 19 hours ago) and read 10982 times:
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I believe I should discuss more on the 4% Pratt is holding in reserve. This amount is above an beyond the normal improvement in technologies that we see in PIPs on engines. Partially, this is due to Pratt *usually missing fuel burn by 4%.* Pratt cannot afford to miss fuel burn on the GTF.

I should point out that certain components on the GTF are far more conservatively engineered than the LEAP-X. Some, such as the scalloped low compressor, have to be done at design or most of the advantage couldn't be retrofitted in. Pratt also simplified the low turbine to save weight and reduce overhaul costs. There is no retrofitting back in a newer concept low turbine.

But Pratt will also have a tougher time tuning the engine for peak efficiency due to the nacelles variable nozzle. Why we often see 0.5% to 1% improvement in engine fuel burn after two (or so) years of service due to improved stator position mapping, I expect a further 0.5% due to the nozzle and how changes in that tuning affect both the low and high spools thus creating a more complex tuning game. It will get done, but I expect it to take time.

I also expect Pratt to have to redesign some part of the engine they do not yet know they have to redesign. For example, I didn't expect a fan technology upgrade. That tells me that Pratt needed to increase the RPM of the low spool (probably for low turbine efficiency). Note: Mach # would be more proper technical terminology than RPM, but I must simplify for discussion sake.

Quoting rheinwaldner (Reply 30):
- The focus on the new GTF/high b/r engines for the next round exactly hits the 737 at its weakest point (ground clearance).

   But everyone should remember that most narrowbody missions are relatively short. While the typical mission has grown (e.g., addition of 738 flights to Hawaii), that is not the case for all flights. Then again, the most profitable *new* flights are at the margin (long range).

Quoting Daysleeper (Reply 31):
A 4% difference has the potential to be a real game changer, but the question is; what can Boeing do about it?

Weight. In particular the hydraulics in the tail. I would also replace the aft pressure bulkhead with a new variation of the 739ER's CFRP (there were lessons learned). I suspect the floor beams are also a good candidate for weight reduction. IMHO, I believe half the reason to look into a new 737 tail cone aerodynamic improvement is that Boeing identified a weight reduction part that might as well be further optimized if one is going to do a material change for weight...

Quoting Stitch (Reply 33):
If lightsaber is correct, that 4% likely won't become available until after 2020. CFM won't be standing still themselves during that time and that fuel burn advantage will have it's greatest impact on longer stage lengths.

CFM won't stand still. That 4% is for advantages above and beyond normal PIPs. Pratt will do those too.

Quoting Stitch (Reply 33):
So should the PW1100G gain all 4%, that will favor that engine on the A320-200 and (especially) A321-200 on longer missions. Might actually make the A321-200neo a true 757-200 replacement in terms of nominal range.

   Let me be clear that Pratt is in discussion for TATL range A321s. Those will not be available at EIS, but there is high interest in a lower cost TATL solution. I suspect that range (3900nm+) would be of high interest to mid-east carriers too.

Quoting Daysleeper (Reply 40):
In a worst case, 3 years from the NEO’s EIS would put it at 2018.

While I agree with the math, I think 2020 is the timeframe Pratt/Airbus will need for all of the improvements for a TATL range A321. This would include engine PIPs and airframe weight reduction as well as a MTOW increase to better optimize the airframe for a longer range mission.

Quoting EPA001 (Reply 55):
On the subject itself I would say that the GTF could by concept always have an advantage, but that is just theoretical.

Increasing the mach # of the low turbine to improve efficiency is a proven concept. The only theoretical part of the GTF is the reliability of the gearbox. Oh, Pratt's proven that on the ground, but the thermal variation in the air is always different than accelerated ground testing. The goal is to accelerate ground testing to match or exceed flight loads; sometimes that works, sometimes it doesn't.

Quoting Stitch (Reply 60):
It's no secret Pratt is holding back SFC. So per "a.net truth", the only narrowbody planes that should be securing orders are the CSeries, the MRJ, the MS-21 and the A320neo with PW1100G power

  

However, you have a point in that we will have a split market. Just as LH selected different engines for the A320OEO and A321NEO, we could see those airlines that need the payload at range splitting their fleet. GE does an excellent job on per cycle costs. I do not expect that to stop.

I do expect the A320NEO to open up longer missions. While I do not expect these missions to be the bulk of narrowbody flights, I do expect their profit to be attractive enough to drive some fleet replacement decisions.

Of course Pratt must prove the GTF reliability and time on wing. The PW2000 dispatch reliability at EIS kept Pratt from exploiting a fuel burn advantage that RR closed in the nick of time.

Quoting Revelation (Reply 57):
If Pratt isn't willing to sign up to the margin, certain bloggers shouldn't act as if it's a certainty.

You have a point there. I believe that Pratt is doing everything it can to ensure a successful GTF EIS. This includes cycle life, maintenance costs, as well as fuel burn. Pratt is giving themselves margin to ensure a 'swing for the fences' EIS.

Quoting rheinwaldner (Reply 59):
Ok, I know Pratt would mount their GTF on the 737 and Boeing might do it for the sake of customer wishes. But the benefits would not come to full effect..

Pratt would *love* to mount the GTF on the 737MAX. While the TSFC would be lower, so would the weight. If the A320NEO core was kept (most likely) we would see the following advantages (analogous with the MRJ GTF having the same core as the C-series):
1. The lower thrust demands result in lower pressure as the only way to balance the engine is to take in less air into the core at the low compressor. This cools all the hot section components. Pratt could re-optimize the high turbine cooling (including the inlet guide vanes), or sell an engine with 25% (or more) longer intervals between overhauls. I believe Pratt would most likely keep part commonality and instead sell service time on wing.   
2. Enhanced hot/high performance. While thrust would be limited by airframe structural concerns, why not allow for full thrust at 600' altitude and 114F. (Typical requirement for DXB, DOH, AUH. No, they aren't at any altitude, but they do have hot days at low barometric pressure.)

Despite the 737MAX having a better wing for long haul (its newer than the A320 wing), I see a case where the 737MAX will naturally trend to optimizing for 500nm to 2300nm missions and the A320NEO being more optimized for 700nm to 3400nm missions. While both will be able to operate outside those windows, they will be at an economic disadvantage to the competitor.

I see the 737MAX selling. I also see Boeing having little choice but to announce a CFRP wing development for the MAX in ~2022. Then the cycle will repeat again.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineHmelawyer From United States of America, joined May 2011, 65 posts, RR: 0
Reply 63, posted (2 years 5 months 1 week 4 days 19 hours ago) and read 10837 times:

Quoting lightsaber (Reply 62):
I think 2020 is the timeframe Pratt/Airbus will need for all of the improvements for a TATL range A321. This would include engine PIPs and airframe weight reduction as well as a MTOW increase to better optimize the airframe for a longer range mission.

If the improvements come around a 2020 timeframe, then that just may be the impetus for Boeing to really kick the planning for NSA into high gear. They didn't think that a 2019 EIS was doable, and there is a need to give the MAX a decent production run to not tick customers off about residual values, but an EIS around 2025 likely works on both counts. This would allow Boeing to launch not long after 2020 and change the discussion from what the GTF will do to the NEO/MAX battle and how the NSA can be optimized to best incorporate the best advantages of the GTF and whatever GE/CFM and/or RR has come up with at that time.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 64, posted (2 years 5 months 1 week 4 days 19 hours ago) and read 10829 times:

Quoting PlaneAdmirer (Reply 61):
If it's going to be a hypothetical discussion, why not make it a POTENTIAL 10% advantage or even 15% or for that matter 1-2%?

Because I believe 4% to be accurate, further up the thread Lightsaber suggested that 1%-2% would perhaps be the figure upon EIS and a PIP a couple of years later would increase this to around 4%.

I don’t quite understand why some posters on here seem determined to discredit this blog when its basis of Pratt holding a few percent performance as a reserve on the GTF is perfectly credible.


User currently offlinePlaneAdmirer From United States of America, joined Jul 2009, 564 posts, RR: 0
Reply 65, posted (2 years 5 months 1 week 4 days 19 hours ago) and read 10784 times:

Quoting Daysleeper (Reply 64):
I don’t quite understand why some posters on here seem determined to discredit this blog when its basis of Pratt holding a few percent performance as a reserve on the GTF is perfectly credible.

Actually, I am very hopeful for the GTF. After reading Lightsabers post, I double checked to make sure that I show him as a RR and he is.


User currently offlineEPA001 From Netherlands, joined Sep 2006, 4739 posts, RR: 39
Reply 66, posted (2 years 5 months 1 week 4 days 19 hours ago) and read 10785 times:
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Quoting lightsaber (Reply 62):
I see the 737MAX selling. I also see Boeing having little choice but to announce a CFRP wing development for the MAX in ~2022. Then the cycle will repeat again.


Wow. What an interesting post from you again Lightsaber. Many thanks for that.  .

Regarding your last line I was thinking, wouldn't Boeing be better off to take as much as she can out of the MAX, but then move forward to the All New Narrow-body? Another re wing-operation would be very expensive, and would push-back the introduction of that Y1 airplane for many years. Then again, if Airbus and Boeing can keep their customers (very) happy with the NEO and the MAX, they might as well milk the cow till the end. Especially if no real game-changing technologies or offering by competitors will appear over that period of time (2022 and 10 years beyond).  .


User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 67, posted (2 years 5 months 1 week 4 days 18 hours ago) and read 10780 times:
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I don't see Boeing going with a CFRP wing on the MAX when they can go NSA unless by the mid-2020s the overall technological base for an NSA remains uncompetitive on an ROI basis as it does at this moment. Airbus would likely follow the same track so in such a scenario we'd see the 737 line perhaps pushing seven decades and the A320 crossing the half-century mark!   

User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 68, posted (2 years 5 months 1 week 4 days 18 hours ago) and read 10642 times:

Quoting rheinwaldner (Reply 56):

Quoting Roseflyer (Reply 39):
What I really call into question is that if this 4% is true, why are the orders for the GTF and LeapX split almost 50-50 on the NEO?

Because they could have been sld dirt cheap. We have indications for this.

Do we have indications of this or speculation by one article and blog? My personal opinion is that the statement of selling engines for virtually free indicates whoever wrote that really doesn't know what they are talking about. That discredited most of their statements in my mind. CFMI is profit driven and is not going to sell engines for virtually free. What they may do is reduce prices to get more market share to get benefits of higher production rates. However we are talking single digit percentages. The engine manufacturer margins are close to the airplane manufacturer margins of 10%.

Quoting rheinwaldner (Reply 59):

If the fan would be as big as the turbine, the optimum speed of both would be the same. As the fan grows, a different speed becomes desireable. The GTF so to speak is a key-enabler to get large fan sizes. As it is the point to operate larger fans without the usual penalities and exacty larger fans are prevented on the 737 I would go as far and say, that the GTF on the 737 is pointless.

A geared turbofan allows the turbine and compressor to spin faster than the fan. In any high bypass turbofan engine (leapX is 10:1, PW1000 is 12:1), a gearbox would improve efficiency. The fan on the GTF is not going to spin slower than the LeapX. The core is going to spin faster and need fewer stages which is where the efficiency gain comes from. If you think a GTF would be pointless on a 737, I don't think you understand jet engine technology. The 737 fan size is big enough to get much of the benefit out of a GTF. It is for other reasons that Boeing went LeapX.

Quoting Daysleeper (Reply 58):

Why? As has been discussed the likely course of events would be for the GTF to launch on spec next year and then for a PIP to follow around 2016, meaning the NEO would be able to take full advantage of it at launch and the Max would be in late stages of development.

I think there is a lot of speculation of the GTF being better than proposed. I'm not trying to be a detractor, but I don't understand why many on this thread are assuming it will be better than expected. The PW1000 is a monumental launch for Pratt & Whitney. They haven't produced an engine at the rates needed since the cold war. I don't deny that with all the recent history manufacturers are cautious about projections. However I trust the engineering decisions made by the manufacturers far more than speculation from aviation industry analysts.

PW has a lot of things going with this very large development program. GTFs are inherently less reliable, so that is why they have been in the testing phase so long. For example, the GTF would lose massive numbers of orders if its IFSD rate is too high to meet ETOPS requirements. If the UER rate is too high, airlines are quickly abandon the program. One diversion with an unscheduled removal costs an airline aobut $250,000. That destroys any fuel savings.

PW is going for something that is more complex and has the capability of improved performance over CFM. However I wouldn't put CFM as the underdog. They have optimized the CFM56 over generations and this is more evolution than revolution. In all factors other than Fuel Burn, I would expect CFM to have the advantage.

There is a lot more in engine development than launching on spec and then doing PIPs. I caution you over the belief that the engine will be better than expected. Reaching every parameter on time, and on budget is a massive undertaking and to this day with the ever growing FAA, EASA and TC regulations in the industry few manufacturers have been able to do it.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinenomadd22 From United States of America, joined Feb 2008, 1866 posts, RR: 0
Reply 69, posted (2 years 5 months 1 week 4 days 17 hours ago) and read 10562 times:

Quoting lightsaber (Reply 62):
The only theoretical part of the GTF is the reliability of the gearbox. Oh, Pratt's proven that on the ground, but the thermal variation in the air is always different than accelerated ground testing. The goal is to accelerate ground testing to match or exceed flight loads; sometimes that works, sometimes it doesn't.

Didn't Pratt plan the design around a 98% efficient gearbox and come in at 99%, meaning only half the planned heat dissipation?



Andy Goetsch
User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 70, posted (2 years 5 months 1 week 4 days 14 hours ago) and read 10323 times:

Quoting Roseflyer (Reply 68):
I'm not trying to be a detractor, but I don't understand why many on this thread are assuming it will be better than expected. The PW1000 is a monumental launch for Pratt & Whitney. They haven't produced an engine at the rates needed since the cold war.


You have essentially given the main reason as to why the GTF is expected to better its performance guarantees. As you point out this is a very significant launch for P&W and with a history of not meeting their performance figures they are very aware of how much missing the spec can cost them.

Therefore in order to prevent history repeating it’s self they have, or it is believed they have under-promised this time and will be able to deliver an engine that is able to meet its guaranteed figures without being fully optimised.

Quoting Roseflyer (Reply 68):
. GTFs are inherently less reliable, so that is why they have been in the testing phase so long

An extended period of testing does not prove that an engine is inherently less reliable, if anything it demonstrates just how diligently Pratt are working to deliver a reliable product.

Quoting Roseflyer (Reply 68):
PW is going for something that is more complex and has the capability of improved performance over CFM. However I wouldn't put CFM as the underdog.

You seem to be contradicting yourself here, you state that the GTF has the ability to out-perform the LeapX but then say it won’t….


User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 71, posted (2 years 5 months 1 week 4 days 14 hours ago) and read 10194 times:

Quoting Roseflyer (Reply 68):
Do we have indications of this or speculation by one article and blog? My personal opinion is that the statement of selling engines for virtually free indicates whoever wrote that really doesn't know what they are talking about. That discredited most of their statements in my mind. CFMI is profit driven and is not going to sell engines for virtually free. What they may do is reduce prices to get more market share to get benefits of higher production rates. However we are talking single digit percentages. The engine manufacturer margins are close to the airplane manufacturer margins of 10%.

I think it's worse than that, no? Meaning the 10% is including profits from sales, parts, services, etc. Thus your previous programs had better be producing that revenue stream that allows to research and develop your next programs, or you don't have any way to stay in the business once the current products run their course.

In the case of Pratt, the military side of the house has had many successes, and they've been used to make up for the various missteps the commercial side has had over the last decade or two.

I forget the number, but GE said it was still paying down the R&D on the GE90 until just very recently, meaning it took them something like two decades to hit a break even position, and that isn't unusual.

The main reason for bringing this up is to point out yet again that everyone in the business is taking huge risks, and no one is doing so lightly.



Inspiration, move me brightly!
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 72, posted (2 years 5 months 1 week 4 days 13 hours ago) and read 10088 times:

Quoting Daysleeper (Reply 70):
You have essentially given the main reason as to why the GTF is expected to better its performance guarantees. As you point out this is a very significant launch for P&W and with a history of not meeting their performance figures they are very aware of how much missing the spec can cost them.

Therefore in order to prevent history repeating it’s self they have, or it is believed they have under-promised this time and will be able to deliver an engine that is able to meet its guaranteed figures without being fully optimised.

I have very different logic than you do. Your logic makes good business sense, but I think about it from an engineering point of view. PW has taken on something very challenging with a GTF and high production rates. That makes it harder to produce a product, on performance, on budget, and on time. I think you underestimate how challenging it is. Just because executive leadership is motivated to prevent history from repeating itself as you say that doesn't mean that engineering will be able to do it. Some speculate they underpromised to account for some of the challenge. I may be wrong, but I don't really buy into the statement that they are underpromising to account for shortfalls. I used to work for a Pratt & Whitney sister company and I have never seen them create projections and budgets for a product and then just add a 4% just in case we fail factor. Any engineering study that does that should be sent back to the drawing board to be redone. If you are so skeptical in your performance of a project while planning it, then you really don't know what you are doing.

From my experience, you add additional flow time in a schedule to overcome challenges that you know are going to happen during development and testing. Good engineering judgement does not underpromise performance, just acknowledge additional flow time.

Quoting Daysleeper (Reply 70):

An extended period of testing does not prove that an engine is inherently less reliable, if anything it demonstrates just how diligently Pratt are working to deliver a reliable product.

You are absolutely right that an extended period of testing does not prove that the engine is less reliable. What does make the engine less reliable is putting a planetary gearbox between the fan and the compressor, which is a very challenging environment for a gearbox to be in and then trying to find to keep it cool and lubricated. No one has ever been able to do it on the scale of a PW1000 before.

The geared turbofans produced by Honeywell/Lycoming are great for their application on business jets which are low utilization and where reliability is not very important due to ample maintenance. No one has made it work well larger scales. The BAE-146 has been plagued by engine reliability problems and hardly compares to what the PW GTFs are being proposed to do.

Quoting Daysleeper (Reply 70):

You seem to be contradicting yourself here, you state that the GTF has the ability to out-perform the LeapX but then say it won’t….

I think you are confusing terms. The GTF design has the ability to optimize blade speed for the both the fan and turbine/compressor. That is where fuel efficiency comes in since there are fewer stages needed. A GTF design has the capability of burning less fuel. However as stated earlier, the main drawback is reliability. To this day, it's a tradeoff. Does the airline want better fuel burn or better reliability? PW is trying to make the GTF work and maintain reliability. If they do it will be a smash hit.

[Edited 2012-04-13 14:33:38]

[Edited 2012-04-13 14:35:13]


If you have never designed an airplane part before, let the real designers do the work!
User currently offlineSeJoWa From United States of America, joined May 2006, 352 posts, RR: 0
Reply 73, posted (2 years 5 months 1 week 4 days 13 hours ago) and read 10032 times:

Roseflyer, if I remember correctly, it is in this interview that Alan Epstein of P&W tells how they ran a test engine and took it apart after so-and-so-many cycles to find basically no wear on the gears.

http://www.airplanegeeks.com/2012/01...in-and-the-geared-turbofan-engine/

If that eventually proves correct in-service too (and it seems a lot of testing has gone into the gears), it really may be so that the higher temps GE needs will tilt the reliability scales towards the GTF.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 74, posted (2 years 5 months 1 week 4 days 12 hours ago) and read 9991 times:

Quoting SeJoWa (Reply 73):
Roseflyer, if I remember correctly, it is in this interview that Alan Epstein of P&W tells how they ran a test engine and took it apart after so-and-so-many cycles to find basically no wear on the gears.

http://www.airplanegeeks.com/2012/01...in-and-the-geared-turbofan-engine/

If that eventually proves correct in-service too (and it seems a lot of testing has gone into the gears), it really may be so that the higher temps GE needs will tilt the reliability scales towards the GTF.

Thanks for the article. One day it will be good to see GTFs in widespread use. It isn't that different from CVTs in cars. A few tried for decades until Nissan finally hit a combo that worked and mass produced them starting in 2006.

I think it is a bit early to tell the PW GTF vs LeapX. There are rumors of the GTF being better, but that hasn't shown up in the orders competition yet.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineJoeCanuck From Canada, joined Dec 2005, 5471 posts, RR: 30
Reply 75, posted (2 years 5 months 1 week 4 days 10 hours ago) and read 9860 times:

What I really don't get is why it's so easy to assume that Pratt is holding back 4% from published specs but CFM isn't. As of right now, GE/CFM is spanking the pants off of Pratt, and has been since the 737 Classics.

The GTF is a brilliant big of engineering. With the gearbox being the newest thing about the engine, they can go relatively low tech for the core and reap major benefits. CFM has a tougher job, squeezing more of their efficiencies from the core, (though they are no slouches in the fan department), and relying on more exotic materials.

What some seem to be missing is that the GTF fan won't be spinning more slowly, the LPT will be spinning much more quickly. That's where the efficiency gains come from, (perhaps I'm mistaken...correct me if I'm wrong). With the LPT spinning at a more optimum mach #, the LPT needs fewer stages to achieve the turbine efficiencies than the direct drive CFM LPT.

From what I understand, this doesn't mean that CFM can't get similar efficiencies from their engine...but more stages mean more weight and more potential for reliability issues.

Bottom line; I think it's way to early to write the LeapX off as a second best solution. Lots of MAX and NEO customers seem to agree.



What the...?
User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 76, posted (2 years 5 months 1 week 4 days 5 hours ago) and read 9731 times:
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Quoting EPA001 (Reply 66):
Regarding your last line I was thinking, wouldn't Boeing be better off to take as much as she can out of the MAX, but then move forward to the All New Narrow-body?

You are correct. As I think about what I would do with a re-wing... It keeps coming back to new taller landing gear and that breaks too much commonality with the 737.

Quoting nomadd22 (Reply 69):
Didn't Pratt plan the design around a 98% efficient gearbox and come in at 99%, meaning only half the planned heat dissipation?

Now make a thousand of them and all customers will remember is the worst ones. It is more of a maintenance worry than efficiency. You are correct that less heat dissipation is a good thing in terms of durability.

Quoting Roseflyer (Reply 68):
PW is going for something that is more complex

Actually, quite the opposite. Due to the low turbine running at a far more efficient Mach #, there is one less row of low turbine blades. With a faster and slightly more efficient low compressor, it simplifies the high compressor. GE is going for very high performance low and high compressors. There is, in my opinion, slightly more risk there than with the PW1000G concept.

Quoting Roseflyer (Reply 68):
GTFs are inherently less reliable, so that is why they have been in the testing phase so long.

   Prior to synthetic gear oil, gearboxes in radial engines were unreliable and had a number of issues. Prior to electronic temperature sensors with digital logic to predict gearbox failure, a gearbox failure was a spectacular event. Much of the testing was to *prove* to Boeing/Douglas senior management that Pratt could predict a gearbox failure more than 400 cycles prior to said failure. Why 400? The general rule in aviation is to take a cycle life and divide it by three and that is why you have to act. Boeing/Douglas worried the FAA would mandate a division by 4. (2 lives plus 2 lives for information is typical for fracture critical parts such as landing gear). Thus, 400 proven cycles allows a gearbox to stay on, after a defect is found, for 100 cycles before the engine is pulled for gearbox overhaul for fracture critical parts or 133 cycles if the part is safety critical or 200 cycles if the part is but durability critical.

Yes, why fracture critical is more important than safety critical? IIRC it was the Comet (Electra?) that helped create that category.

Quoting Revelation (Reply 71):
I forget the number, but GE said it was still paying down the R&D on the GE90 until just very recently, meaning it took them something like two decades to hit a break even position, and that isn't unusual.

If memory serves me right, the JT9D took 25 years for break even.    Note: That was all of the upgrades, including the JT9D-7R4.

Quoting Roseflyer (Reply 72):
Some speculate they underpromised to account for some of the challenge. I may be wrong, but I don't really buy into the statement that they are underpromising to account for shortfalls. I used to work for a Pratt & Whitney sister company and I have never seen them create projections and budgets for a product and then just add a 4% just in case we fail factor.

Because Pratt typically missed fuel burn at EIS by 4%, the GTFs were always saddled with the 4% burden. Partially as the GTF is that much of a game changer.

Let's look at it another way. How could the LEAP-X come close to the GTF's fuel burn? The basic physics of the gearbox drop fuel burn 8% to 11% plus produce a lighter engine! Now 8% lower fuel burn would be a low bypass engine, such as an engine under the 737MAX's wings. (Poorly optimized bypass ratio.) The 11% cut in fuel burn would be for a lager (above 60k lbf thrust) engine. Recall that the higher the bypass ratio the more the fan blade tip Mach number limit is reducing the Mach number in the low turbine (and to a lesser impact, the low compressor). Everyone becomes obsessed with how the gearbox improves fan efficiency, but there is actually more gain back at the low turbine until the higher bypass ratio is accounted (I know... chicken and egg).

Quoting JoeCanuck (Reply 75):
What I really don't get is why it's so easy to assume that Pratt is holding back 4% from published specs but CFM isn't.

GE did so with the GE-90-115. Hence why it could enter fuel burn at 2% lower fuel burn than promise and then be PIP'd up to the target fuel burn. So it is possible GE is holding back 4%. However, GE hasn't typically held that much back for narrowbody engines. OK, Pratt used to hold back none (other than what the IPTs held back). But after too many misses, Pratt had to hold back at the system level to account for mis-steps.

Quoting JoeCanuck (Reply 75):
the LPT needs fewer stages to achieve the turbine efficiencies than the direct drive CFM LPT.

Needs fewer stages for better efficiency.    A below optimum Mach # turbine will have greater losses as well as lower specific horsepower extraction per stage. This is why RR went to a triple spool.

By having the triple spool's low compressor powered by its own turbine stage, the triple spool not only gains efficiency, but cuts part count by about one turbine stage.

Quoting JoeCanuck (Reply 75):
I think it's way to early to write the LeapX off as a second best solution.

I do not write off the LEAP. However, unless Pratt really messed up, the GTF will have the advantage on longer range missions.    Again, most narrow body missions are about 90 minutes duration.

GE has an advantage of *far* greater resources for R&D funding than Pratt. However, Pratt has put in money over the last decade. IMHO, the GE low compressor is 1.5 generations ahead of the Pratt!    However, its not that critical if the compressor Mach # is more optimum.   GE is also going with more advanced

Now GE is claiming they will have a 5% more efficient compressor than the GTF:
http://www.cfm56.com/cfm-value/technology/leap

If true, that is huge. However, if its a 5% more efficient compressor than versus a GTF if the GTF has a low compressor at normal RPM, that I would believe. In general, GE has more efficient compressors than Pratt. The only exception I know of is Pratt could build a more efficient fan for the GP7200 and GE was shocked when Pratt beat promise!    However, that just taught GE what they missed so it wouldn't surprise me if GE was ahead again.  

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 77, posted (2 years 5 months 1 week 4 days 5 hours ago) and read 9769 times:

Quoting lightsaber (Reply 76):

I do not write off the LEAP. However, unless Pratt really messed up, the GTF will have the advantage on longer range missions. Again, most narrow body missions are about 90 minutes duration.

I believe average flight for the 737NG is between 800 and 900 miles and right at 2 hours.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinestrfyr51 From United States of America, joined Apr 2012, 1223 posts, RR: 1
Reply 78, posted (2 years 5 months 1 week 4 days 3 hours ago) and read 9664 times:
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Boeing will NOT abandon the CFM Leap engine on the 737 MAX. I worked with the CFM-56 -2,-3B abd 3C where more than a few were on wing 30,000+ Hours.You Don't abandon an engine that has that kind or reliability. As much as I revere Pratt Engines and I think the GTF Will be a winnwer . Until that engine proves itself in the field? which Ihave NO doubt it will do.It's just a good engine design. Now what I AM hoping for is that Pratt expands the concept to the 90K-120K thrust engines where I believe they can Make a VERY significent Rumble in the market beause Pratt's Cores are FAR more robust than the competitors. And if the GTF concept works THERE?? the A350 Will be a winner with htat engine on it! Boeing has tied their wagon to GE and that's a solid business decision but the Pratt F135 Coreemated to the GTF?? might raise a Whole Bunch of Hell in the marketplace !!

User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 79, posted (2 years 5 months 1 week 4 days ago) and read 9538 times:
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Quoting strfyr51 (Reply 78):
Boeing will NOT abandon the CFM Leap engine on the 737 MAX.

I do not think anyone implies that. There has been a rumor that Pratt might be allowed onto the 737MAX. However, I've heard nothing substantial to make me believe that rumor.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 80, posted (2 years 5 months 1 week 3 days 22 hours ago) and read 9383 times:

Quoting Roseflyer (Reply 68):
Because they could have been sold dirt cheap. We have indications for this.
Do we have indications of this or speculation by one article and blog? My personal opinion is that the statement of selling engines for virtually free indicates whoever wrote that really doesn't know what they are talking about.

Beside any personal opinion I remembered that this topic has been discussed earlier. Around the time of the last Paris air show (when CFM had a rush in orders for the LEAP on the NEO), a series of articles appeared that underlined exactly what you question: CFM has bought market share!

Here are first some links (carefully avoiding Aeroturbopower because of its damaged reputation in this thread   )
http://leehamnews.wordpress.com/2011...e-and-how-it-wins-deals/#more-4743
- or - http://airinsight.com/2011/06/27/the-war-of-words/#more-1802
- or - http://airinsight.com/2011/06/15/vir...ectes-cfm-leap-engine-for-a320neo/
- or - http://leehamnews.wordpress.com/2011...-great-incentives-for-engine-deal/
- or - http://airinsight.com/2011/08/25/pri...tial-leap-gtf-narrow-body-battles/

Some quotes:

Quote:
Kowalchuk said the competition was fierce, and added, “CFM’s offer was significantly stepped up with great incentives.”

- or -

Quote:
As for stand-alone engine/services packages that don’t involve restructuring or lease rates, “buying” market share is pretty common.

- or -

Quote:
Although CFM told our partner, Addison Schonland of AirInsight, last week that it doesn’t “buy” deals, there is solid evidence to the contrary.

- or -

Quote:
Cush, CEO of Virgin America, said GTF was ahead until CFM came in with an economic package that was superior.

- or -

Quote:
But a telling comment came from CFM’s Sandrine Lacorre, product marketing director, who said at a UBM Aviation conference, “What we can’t do technically, we will do commercially.”

Any question? IMO this rehabilitates the strong statements of Aeroturbopower.

Quoting JoeCanuck (Reply 75):
What I really don't get is why it's so easy to assume that Pratt is holding back 4% from published specs but CFM isn't.

As Lightsaber already explained the GTF potentially reaches significantly more than the same non-GTF engine (all other things the same).

So in other words, if the GTF and the LEAP would be on par in the end, this would only mean that Pratt has underdelivered in almost any other area than the gear itself. And CFM would have delivered exceptionally in these other areas. The GTF naturally has a splendid reserve over a conventional engine that allows "screwing up" in many other areas until the advantage has been canceled out. And unless we want to credit Pratt that they will screw up all the other parts except the gear, the conclusion must be, that the GTF will be ahead.

Basically the GTF gives Pratt a compelling headstart and after subtracting a considerable chunk of the full benefit for the rest (less optimum solutions), Pratt simply hopes to be in the positive at the end.

Quoting lightsaber (Reply 76):
Recall that the higher the bypass ratio the more the fan blade tip Mach number limit is reducing the Mach number in the low turbine (and to a lesser impact, the low compressor).

This is what I meant, when I mentioned that basically the GTF allows larger fans (everything else the same).


User currently offlineDaysleeper From UK - England, joined Dec 2009, 841 posts, RR: 1
Reply 81, posted (2 years 5 months 1 week 3 days 22 hours ago) and read 9304 times:

Quoting Roseflyer (Reply 72):
I have very different logic than you do. Your logic makes good business sense, but I think about it from an engineering point of view. PW has taken on something very challenging with a GTF and high production rates……………

Regardless of the exact reason, I haven’t seen anything posted which would cast doubt on Pratt having a 4% performance reserve. In fact, after reading Mr Sabers excellent posts I’m now almost certain that there is more to than a rumour.



Quoting JoeCanuck (Reply 75):
What I really don't get is why it's so easy to assume that Pratt is holding back 4% from published specs but CFM isn't. As of right now, GE/CFM is spanking the pants off of Pratt, and has been since the 737 Classics.

The reasons why were discussed earlier in the thread, but essentially it comes down to Pratt desperately needing to meet the specifications this time due to their rather poor performance on recent projects.

Quoting Roseflyer (Reply 74):
I think it is a bit early to tell the PW GTF vs LeapX. There are rumors of the GTF being better, but that hasn't shown up in the orders competition yet.

As I stated earlier;

Quoting Daysleeper (Reply 43):
The performance advantage isn’t guaranteed, I understand this to be “Pratt’s comeback” after over promising and under delivering on previous projects they really wanted to get this one right so this time round, they are planning on over delivering.

So with no guaranteed advantage, Pratts history of over-promising and as you mention yourself the possibly of maintenance issues then I wouldn’t expect them to have a lead in the order numbers. In fact, all things considered I believe they are doing well to maintain 50% at this stage


User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 82, posted (2 years 5 months 1 week 3 days 19 hours ago) and read 9162 times:

Emphasis is mine:

Quoting lightsaber (Reply 76):
Actually, quite the opposite. Due to the low turbine running at a far more efficient Mach #, there is one less row of low turbine blades.
Quoting lightsaber (Reply 76):
The basic physics of the gearbox drop fuel burn 8% to 11% plus produce a lighter engine!
Quoting lightsaber (Reply 76):
Everyone becomes obsessed with how the gearbox improves fan efficiency, but there is actually more gain back at the low turbine until the higher bypass ratio is accounted (I know... chicken and egg).

Thanks for pointing these things out.

I will add that according to

http://airinsight.com/2011/11/09/com...nes-gtf-vs-leap-maintenance-costs/

it's more than just one less LPT row:

http://d9itxagvk5mi8.cloudfront.net/wp-content/uploads/2011/11/Final-Engine-Stages-Table1.jpg

It's four less in the LPT and two less in the HPC for GTF vs LEAP (16 vs 22 stages!), which of course hugely reduces weight as well as cuts the number of blades in half according to Pratt.

Pratt is saying the gearbox will last the life of the engine, and we all know that engine blades do not, so it should be a big maintenance win for the GTF. As you say, though, the tradeoff is the nastiness that results if/when a gearbox fails.

Quoting rheinwaldner (Reply 80):
As Lightsaber already explained the GTF potentially reaches significantly more than the same non-GTF engine (all other things the same).

So in other words, if the GTF and the LEAP would be on par in the end, this would only mean that Pratt has underdelivered in almost any other area than the gear itself.

Yes, but he also said that GE is 1.5 generations ahead in compressor technology, so all things are not even close to equal. CFM has invested its money one way, Pratt has invested it another way, and we won't know the totality of the result till we have an actual result.



Inspiration, move me brightly!
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 83, posted (2 years 5 months 1 week 3 days 19 hours ago) and read 9107 times:

Quoting rheinwaldner (Reply 80):

Any question? IMO this rehabilitates the strong statements of Aeroturbopower.

You bring up many of the points on how CFM wins competitions. Commercially they have the strong support network, spares inventory, more overhaul shops, and genuinely lower maintenance costs than the V2500. I don't see that changing with the the LeapX. Additionally GECAS only finances GE/CFM airplanes, which helps in sales campaigns as well.

Fuel burn isn't the only thing that sells engines. I still don't think I have ever read a credible article that indicates that CFM is selling the engines for virtually free. I do agree that CFM does present a strong commercial argument. It was quite incredible that they were able to win the LeapX vs PW GTF competition for the Frontier A320 NEO since they already had ordered the Cseries.

[Edited 2012-04-14 08:50:31]


If you have never designed an airplane part before, let the real designers do the work!
User currently offlineFRNT787 From United States of America, joined Sep 2007, 1324 posts, RR: 15
Reply 84, posted (2 years 5 months 1 week 3 days 18 hours ago) and read 8996 times:

Quoting Roseflyer (Reply 83):
It was quite incredible that they were able to win the LeapX vs PW GTF competition for the Frontier A320 NEO since they already had ordered the Cseries.

Exactly. With the Frontier deal, they were negotiating with Republic, a major GE customer. (The E-Jets are all GE powered, and many GE financed). Additionally, the deal was a three way deal with Airbus involved as well:

For Frontier/Repulbic:
----Lower Lease Rates on the current A319 fleet, leading to immediate $35 million annual savings
----Renegotiated engine contracts (overhauls, spares etc) leading to further immediate savings
----A320neo
----A319neo for longer missions
----Very positive financing terms

For Airbus:
---An important launch order for the A319neo, for which they had NONE during the Paris Air Show order extravaganza.
---Sends a "strong" message to Bombardier
---Total Frontier deal now same scope (Up to 80 aircraft) as the C-Series deal was

For GE:
---Long term customer for both Capital and Engines
---Score a major customer already on the GTF program.
---Maintains current aircraft in service that may have been "unviable" at current fuel prices.

The Frontier deal, and I suspect others like it, is an example of good business, working the deal. That is how business works. I rather hate reading "gave .....away" on here. According to this site, the 767, A330, LeapX and others are all so undesirable they cannot be sold for anything.



"We have a right to fail, because failure makes us grow" --Glenn Beck
User currently offlineJoeCanuck From Canada, joined Dec 2005, 5471 posts, RR: 30
Reply 85, posted (2 years 5 months 1 week 3 days 17 hours ago) and read 8966 times:

Quoting rheinwaldner (Reply 80):

So in other words, if the GTF and the LEAP would be on par in the end, this would only mean that Pratt has underdelivered in almost any other area than the gear itself. And CFM would have delivered exceptionally in these other areas.

The CFM56 is an old tech engine by now. It doesn't take much imagination to realise that there have been significant developments in engine tech, (besides the GTF), since it was certified so significant improvements are definitely possible...without a GTF. Look at the LPT's. The GTF can use fewer stages by spinning theirs faster. CFM is increasing the number of stages to maximize the energy transfer to the fan. Two ways to skin a cat.

GE managed to get double digit improvements with the GenX over the previous generation without a gearbox.

Pratt has their research primarily into making a robust, reliable and efficient gearbox...not that they've neglected other areas. As has been pointed out, they have a lot of bleeding edge military tech they can draw from.

GE seems to be leaning more towards exotic materials but they could be screwed if their research doesn't pan out.

It seems to me that where Pratt really has the chance to get ahead is with reliability. They don't have to stress the engine as a whole as much as CFM to get their efficiencies so may end up with an engine which requires less maintainence. Still, the CFM 56 is just about the most reliable engine ever so they do have the background to know what works.

The GTF is the next new thing but it won't be all things to all customers and it won't be the best at all things.

Quoting Roseflyer (Reply 83):
Fuel burn isn't the only thing that sells engines

If it was, the CFM wouldn't have sold on very many 320's, From what I understand, the V2500 is the more economical engine.



What the...?
User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 86, posted (2 years 5 months 1 week 3 days 17 hours ago) and read 8939 times:
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Quoting Revelation (Reply 82):
it's more than just one less LPT row:

Two faults of mine:
1. One less LPT row for the same efficiency. So Pratt's is shy a pair of stages.
2. But the LPC will be far more efficient due to the more optimal Mach #.

We should also be talking pressure ratio.

LEAP-X: 40:1
GTF: 45:1 to 50:1.

Bypass ratio
LEAP-X: 11.1
GTF: 12.2

http://airinsight.com/2011/11/09/com...nes-gtf-vs-leap-maintenance-costs/

I believe that is where you found your stages chart. The article predicts the Pratt engine will have a 2% to 3% fuel burn advantage.   

Also note that despite the higher pressure ratio, Pratt is going into the high turbine cooler. Now GE is bringing forth newer turbine materials. Will it work? Or will it be like the PW2000 which never achieved cycles between overhauls as Pratt was still learning about the commercial implementation of single crystal turbine blades.  
Quoting Revelation (Reply 82):
It's four less in the LPT and two less in the HPC for GTF vs LEAP (16 vs 22 stages!), which of course hugely reduces weight as well as cuts the number of blades in half according to Pratt.

Pratt has intentionally sacrificed long haul fuel burn to better optimize the engine for short haul.

In many ways, the competitiveness of the two engines will come down to high turbine maintenance costs.

http://airinsight.com/2011/06/27/the-war-of-words/#more-1802
"Note also that midway through the Virgin America campaign CFM offered a new engine with an extra stage and larger fan"

Lightsaber


Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineJoeCanuck From Canada, joined Dec 2005, 5471 posts, RR: 30
Reply 87, posted (2 years 5 months 1 week 3 days 12 hours ago) and read 8727 times:

Quoting lightsaber (Reply 86):

LEAP-X: 40:1
GTF: 45:1 to 50:1.

Some are saying the LeapX will also have a 45:1 to 50:1 pressure ratio range;

http://www.flightglobal.com/news/art...core-2-initial-performance-358081/

Quote:
The Leap-X OPR is almost identical to competitor Pratt & Whitney's PurePower geared turbofan option on the A320neo, although the two companies differ substantially in the mechanisation of the engines.



What the...?
User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 88, posted (2 years 5 months 1 week 3 days 11 hours ago) and read 8588 times:
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Quoting JoeCanuck (Reply 87):
Some are saying the LeapX will also have a 45:1 to 50:1 pressure ratio range;

Then that will help match up the TSFC.   

Those extra stages will have weight though...

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineJoeCanuck From Canada, joined Dec 2005, 5471 posts, RR: 30
Reply 89, posted (2 years 5 months 1 week 3 days 9 hours ago) and read 8443 times:

Quoting lightsaber (Reply 88):
Those extra stages will have weight though...

It's a damned interesting time, isn't it? It's a geeks paradise.



What the...?
User currently offlinekanban From United States of America, joined Jan 2008, 3560 posts, RR: 26
Reply 90, posted (2 years 5 months 1 week 3 days 8 hours ago) and read 8391 times:
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Quoting lightsaber (Reply 76):
It keeps coming back to new taller landing gear and that breaks too much commonality with the 737.

How does a 6 inch longer nose gear break too much commonality other than the cost of spares?... seems to me the ass end redesign and the different engines breaks commonality long before the nose gear unless one is landing nose gear first.


User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 91, posted (2 years 5 months 1 week 3 days 7 hours ago) and read 8347 times:
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Quoting kanban (Reply 90):
How does a 6 inch longer nose gear break too much commonality other than the cost of spares?...

I was referring to a new 737 with a replaced CFRP wing. By the time that new re-winged 737 is considered, new engines will also have to be developed (post-LEAP-X). That will result in a larger diameter engine to be competitive. It won't be possible to do another re-engine on the 737 (after the LEAP-X). Hence why EPA001 noted Boeing would go with the NSA and not another 737 improvement.

In other words, even I type without thinking through every implication.  

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlinekanban From United States of America, joined Jan 2008, 3560 posts, RR: 26
Reply 92, posted (2 years 5 months 1 week 3 days 6 hours ago) and read 8305 times:
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now I'm with you.. thanks for the clarification.

User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 93, posted (2 years 5 months 1 week 3 days 6 hours ago) and read 8257 times:

Quoting JoeCanuck (Reply 89):
It's a geeks paradise.

Count me in!  



Inspiration, move me brightly!
User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 94, posted (2 years 5 months 1 week 2 days 23 hours ago) and read 8058 times:

Quoting JoeCanuck (Reply 85):
It doesn't take much imagination to realise that there have been significant developments in engine tech, (besides the GTF),

Correct. Otherwise CFM could not build an engine about as good as GTF V1. My point is that GE has to rely on the edge of technology in a lot of other areas to get there. But these technologies won't stay away from the GTF over a longer period. It is a matter of time, until the GTF V2 will have the ultimate lead.

Overall the GTF is not a competing technology that prohibits the rest of the high tech. In fact it is mostly a complementary technology that would catapult a fine engine as the Leap into complete new dimensions. If the LEAP and the GTF would sport the same gear the Leap would achieve a tremendous lead.

Quoting JoeCanuck (Reply 85):
The GTF is the next new thing but it won't be all things to all customers and it won't be the best at all things.

Correct, but it will be unbeatable if everything else is the same.

I wonder why the GTF, which is the single revolutionary technology, is not embraced more aggresively by GE and RR. I estimate that the last single technology, that allowed such leap gains (in fuel burn) was the high b/r turbofans that powered the initial 747 & DC10 40 years ago. Everything else since then brought improvements only in small increments.

But at that time all engine vendors quickly started to develop engines for the 747. Why is there a reluctance towards the GTF this time? IMO the prospects are clarified enough to understand that this will be the technology that will be in every engine over longer terms. Imagine a situation in 7 years, when Pratt could have perfected the gear to realize a 787 engine, that would beat everything else out there despite lacking the edge of technology in a lot of other areas. Simply by the giant effect (in terms of the size of improvements we are used to in aviation) the GTF yields to the overall efficiency.

IMO RR and GE should get that technology on board (and be it by cooperation, imagine a RR/Pratt Trent GTF) as soon as possible.


User currently offlinepar13del From Bahamas, joined Dec 2005, 7229 posts, RR: 8
Reply 95, posted (2 years 5 months 1 week 2 days 21 hours ago) and read 7876 times:

Quoting JoeCanuck (Reply 75):
Bottom line; I think it's way to early to write the LeapX off as a second best solution.
Quoting rheinwaldner (Reply 94):
IMO RR and GE should get that technology on board

The answer to your question, they did not invent the technology and will not demolish their billion dollar enterprizes to the benefit of Pratt. After all, they are competitors, neither GE, RR or PW are sitting at the Airbus and Boeing campfire assisting each other. Betamax was also superior technology, how did that work out?


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 96, posted (2 years 5 months 1 week 2 days 19 hours ago) and read 7823 times:

Quoting rheinwaldner (Reply 94):

I wonder why the GTF, which is the single revolutionary technology, is not embraced more aggresively by GE and RR.

It's *hard*. Developing a gearbox that can handle that amount of power with commercial turbofan reliability at an acceptable weight with not excessive maintenance is an engineering triumph that took P&W many many years. GE and RR decided (rightly or wrongly) that the risk/reward profile wasn't right for them and went for other technologies to achieve the same goal.

If GTF turns out to be the game changer that P&W hopes it will be then GE and RR may have to follow suit eventually but they're at a multi-year disadvantage to P&W.

Tom.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 97, posted (2 years 5 months 1 week 2 days 19 hours ago) and read 7770 times:

Quoting rheinwaldner (Reply 94):
I wonder why the GTF, which is the single revolutionary technology, is not embraced more aggresively by GE and RR.

Simply put gearboxes are notorious for being problematic, heavy and unreliable.

Here's an article about some of the details of engine technology which is quite good.

http://www.flightglobal.com/news/art...ear-up-for-2025-and-beyond-354207/

In general GTFs along with Open Rotor/Propfans have been investigated since the 1980s as the next revolution. No company has been able to make it work yet. If it was easy, it would have been done early.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 98, posted (2 years 5 months 1 week 2 days 19 hours ago) and read 7756 times:
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Quoting rheinwaldner (Reply 94):
Overall the GTF is not a competing technology that prohibits the rest of the high tech.

   However some technology doesn't provide as much benefit at the more optimum mach numbers of a GTF. For example, a fan blade change that might help the LEAP-X 1.5% might only help the GTF 0.5% as the fan is at a much more efficient Mach number on the GTF. There is some low pressure turbine technology where that is true to. It shifts the TSFC and weight trade towards 'save the weight!'

Quoting rheinwaldner (Reply 94):
It is a matter of time, until the GTF V2 will have the ultimate lead.

Eventually. But look at the pressure ratios. Pressure ratios are approaching a cap based on the easy to cast in large shape Nickels (Inconel 715). Now, if someone has figured out how to cast a large casing out of Inconel 625, the problem is solved. Of course, there are other candidate materials.

Quoting rheinwaldner (Reply 94):
I wonder why the GTF, which is the single revolutionary technology, is not embraced more aggresively by GE and RR.

RR has done research into it. They just haven't put in the billion Pratt did. Most of what Pratt has developed is laboratory testing, mapping of oil cooling of the gearbox, determining failure modes and prediction, etc. It has been more blacksmith engineering rather than than theoretical. More analogous to a chip factory. While the theory must be there, getting to 22nm is more a matter of making it work. Yes, Ph.Ds must be involved, but it is more sweat equity with equations than pure theory.   

GE and RR also invested in Open Rotors. That is a big leap that requires passengers to accept longer flight times.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 99, posted (2 years 5 months 1 week 2 days 19 hours ago) and read 7705 times:

Quoting rheinwaldner (Reply 94):
But these technologies won't stay away from the GTF over a longer period. It is a matter of time, until the GTF V2 will have the ultimate lead.

If these technolgies are so inevitable, what is preventing Pratt from having them right now? After all, CFM has them, right?

Quoting rheinwaldner (Reply 94):
If the LEAP and the GTF would sport the same gear the Leap would achieve a tremendous lead.

And if my uncle had boobies, he'd be my aunt.

Quoting rheinwaldner (Reply 94):
Correct, but it will be unbeatable if everything else is the same.

Everything is NOT the same!

Quoting rheinwaldner (Reply 94):
I wonder why the GTF, which is the single revolutionary technology, is not embraced more aggresively by GE and RR.

Who knows what is happeneing behind the scenes? We do know PW and RR have signed some sort of agreement, but we don't know what it will bring.

Quoting rheinwaldner (Reply 94):
But at that time all engine vendors quickly started to develop engines for the 747. Why is there a reluctance towards the GTF this time?

At the same time, Lockheed, Convair, Rockwell, Northrup, Grumman, Boeing, McDonnell and others I'm sure I'm forgetting were all in the military airframe business, and now we're pretty much down to LM, Boeing and NG, and Boeing is mostly cargo ships and tankers, LM is mostly fighters, and NG is hanging on via drones.

Simply put, the barrier to entry is much higher and the expectations are much more difficult to achieve due to strong competitors with highly developed products.

It's not the same as six guys making a photo sharing app and two years later being bought out for $1B.



Inspiration, move me brightly!
User currently offlineJoeCanuck From Canada, joined Dec 2005, 5471 posts, RR: 30
Reply 100, posted (2 years 5 months 1 week 2 days 18 hours ago) and read 7658 times:

Quoting rheinwaldner (Reply 94):

Overall the GTF is not a competing technology that prohibits the rest of the high tech. In fact it is mostly a complementary technology that would catapult a fine engine as the Leap into complete new dimensions. If the LEAP and the GTF would sport the same gear the Leap would achieve a tremendous lead.

That's not completely true...especially where the engine cores differ...mostly in LPT. Not all technology that works on one is a direct transfer to the other.

The name of the game is energy transfer from the combuster to the fan. The GTF can do this with fewer stages because it is more efficiently transfers the energy on a per stage basis. Leap X can do the same thing...but it takes more stages. Overall efficiency should be very similar for both.

More exotic materials won't help the GTF as much as the LeapX since their LPT will be running at closer to an optimal Mach number. That may mean that the GTF can be cheaper and more reliable but that changes again if CFM gets their new materials prices down and reliability up.

The differences, ultimately will be weight. The GTF has its weight added in the gearbox and LeapX adds the weight in the LPT.

The GTF is a great idea...but lots of great ideas don't stand the test of time. Look back on the last 100 years of internal combustion engine technology. The vast majority never made the cut.

In 10 years, every new engine may be a variation of the GTF theme...or maybe not. It's way too early in the game for anybody to be declared winner.



What the...?
User currently offlinesphealey From United States of America, joined May 2005, 377 posts, RR: 0
Reply 101, posted (2 years 5 months 1 week 2 days 17 hours ago) and read 7601 times:

Quoting tdscanuck (Reply 96):
It's *hard*. Developing a gearbox that can handle that amount of power with commercial turbofan reliability at an acceptable weight with not excessive maintenance is an engineering triumph that took P&W many many years. GE and RR decided (rightly or wrongly) that the risk/reward profile wasn't right for them and went for other technologies to achieve the same goal.

How does it compare to the gearbox in the Soviet NK-12 turboprop as found on the Tu-95?

sPh

[noting for the record that there are several different names for the NK-12 engine]


User currently offlinestrfyr51 From United States of America, joined Apr 2012, 1223 posts, RR: 1
Reply 102, posted (2 years 5 months 1 week 2 days 17 hours ago) and read 7678 times:
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Quoting lightsaber (Reply 79):

I'd doubt that unless the A320 NEO outsells the 737 MAX 5:1 with the GTF on it. and as of yet? That's not the case.


User currently offlineJoeCanuck From Canada, joined Dec 2005, 5471 posts, RR: 30
Reply 103, posted (2 years 5 months 1 week 2 days 16 hours ago) and read 7592 times:

Quoting sphealey (Reply 101):

That's something I've wondered as well. Those huge tu-95 tprops abuse the heck out of their gearboxes.



What the...?
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 104, posted (2 years 5 months 1 week 2 days 14 hours ago) and read 7438 times:

Quoting sphealey (Reply 101):

How does it compare to the gearbox in the Soviet NK-12 turboprop as found on the Tu-95?
Quoting JoeCanuck (Reply 103):
That's something I've wondered as well. Those huge tu-95 tprops abuse the heck out of their gearboxes.

Directly converting between shaft horsepower and thrust is fraught with physics and philosophy problems but, rule of thumb, one pound of thrust is about 1 shaft horsepower.

The biggest NK-12's were just a shade under 15,000 hp, about equivalent in gearbox power to the engines on a decent sized biz jet.

To even do a 737/A320-sized aircraft means a gearbox with about 2 times the capacity of the NK-12 and you have to stuff it into the space of a fan spinner and you're running that power through one shaft instead of two like the NK-12...power density is probably at least a factor of 10 higher. That's why cooling and durability are such a concern.

Tom.


User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 105, posted (2 years 5 months 1 week 2 days 6 hours ago) and read 7180 times:
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Quoting JoeCanuck (Reply 100):
Leap X can do the same thing...but it takes more stages. Overall efficiency should be very similar for both.

One nitpick: More stages=more surface area (of the blades as well as casing). Due to the high speed flow of the core, surface area=drag. Thus, one advantage of the GTF is less parasitic loss by extracting the horsepower in fewer stages. This is why the trend is to fewer blades and fewer stages. While the aerodynamics of the bulk flow might not improve, by reducing the surface area the turbine (or compressor) efficiency will be improved.

So if the GTF and the LEAP-X had the same level of blade technology, the GTF will be more efficient. However, this is not the case. GE's low turbine is going with a newer (riskier from a cost/schedule perspective) blade technology.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineAesma From France, joined Nov 2009, 6668 posts, RR: 11
Reply 106, posted (2 years 5 months 1 week 2 days 2 hours ago) and read 7054 times:

I don't know if it's any indication but SAFRAN was making a big campaign in the Paris subway and papers a few weeks ago, looking for engineers for the LEAP-X, in particular.


New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
User currently offlinemoo From Falkland Islands, joined May 2007, 3948 posts, RR: 4
Reply 107, posted (2 years 5 months 1 week 2 days 2 hours ago) and read 7029 times:

Quoting tdscanuck (Reply 96):

Is gearing and those "other technologies" mutually exclusive, or will we end up seeing RR et al having to put in the work anyway in the next generation or so?

What I'm essentially asking is whether Pratt did the difficult problems upfront or not? If the solutions aren't mutually exclusive then RR et al may find themselves in the position of already having the (relatively) easy wins under their belt but with the real work left to do...


User currently offlineparapente From United Kingdom, joined Mar 2006, 1583 posts, RR: 10
Reply 108, posted (2 years 5 months 1 week 2 days 1 hour ago) and read 6948 times:

Another way of looking at this is through the actions of Rolls Royce.

They were betting on "OR".That will not now come to fruition.One also notes that their last itieration of their test OR was "Geared" (It was Cfm that was researching an ungeared OR). Rolls has sold out it's interests in their "small engine" to P&W.A clear acceptance (IMHO) of the superiority of the GTF concept (if sales in themselves was not enough).Indeed part of the deal if I recall properly was future cooperation on GTF (Larger engines?).

Perhaps they too realise that the future lies in this direction and that the XWB is effectively "as far as one can go" in terms of efficient by pass ratio's without introducing gearing.They are fine for the next 15 years with what they have got - but perhaps not beyond that point?

Rolls must know more (as an outsider) than anybody else I would wager. By their actions alone it would appear that the rumours about the GTF are indeed true.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 109, posted (2 years 5 months 1 week 2 days 1 hour ago) and read 6920 times:

Quoting moo (Reply 107):
Is gearing and those "other technologies" mutually exclusive, or will we end up seeing RR et al having to put in the work anyway in the next generation or so?

None of them are mutually exclusive that I can think of (except maybe the supersonic compressor but I don't think anyone even considers that anymore). However, they're not generally additive...two 2% technologies do not usually get you 4% when combined.

Quoting moo (Reply 107):
What I'm essentially asking is whether Pratt did the difficult problems upfront or not? If the solutions aren't mutually exclusive then RR et al may find themselves in the position of already having the (relatively) easy wins under their belt but with the real work left to do...

Pratt did a different difficult problem up front. Increasing the pressure ratio as LEAP-X is doing is a different set of difficult problems. Pratt's approach was probably a more difficult problem, in my opinion, but it's not like they'll just be able to plug and play the RR or GE or CFM work into the GTF without doing a lot of work themselves. All that money and time that Pratt spent on the GTF was being spent just as hard at the other OEM's on different things.

Tom.


User currently offlineimiakhtar From , joined Dec 1969, posts, RR:
Reply 110, posted (2 years 5 months 1 week 2 days 1 hour ago) and read 6905 times:

Quoting Roseflyer (Reply 48):
another factor is that the 737 is a higher production rate airplane

Are you sure of this?

Airbus A320 family deliveries in 2011 - 421
Boeing B737 family deliveries in 2011 - 372

I don't work in the manufacturing industry so I guess I could have misunderstood what you meant by 'higher production rate'.


User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 111, posted (2 years 5 months 1 week 1 day 19 hours ago) and read 6652 times:
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Quoting imiakhtar (Reply 110):
I don't work in the manufacturing industry so I guess I could have misunderstood what you meant by 'higher production rate'.
Daysleeper was of the opinion that CFM would develop PiPs for the C919 before they would the 737 MAX because the C919 has more competition and therefore needs all the help it can get.

Roseflyer and myself are of the opinion that since Boeing will deliver significantly more 737 MAXs per month than COMAC will C919s, CFM is guaranteed a far better return on any investment they make in the 737 engine as opposed to the C919 engine and therefore will likely focus their efforts on the 737 engine and apply what they can to the C919 engine.


User currently offlinecmf From , joined Dec 1969, posts, RR:
Reply 112, posted (2 years 5 months 1 week 1 day 19 hours ago) and read 6611 times:

Quoting imiakhtar (Reply 110):
Are you sure of this?

Airbus A320 family deliveries in 2011 - 421
Boeing B737 family deliveries in 2011 - 372

A320 is split between two engines whereas 737 only has one.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 113, posted (2 years 5 months 1 week 1 day 19 hours ago) and read 6603 times:

Quoting imiakhtar (Reply 110):
Quoting Roseflyer (Reply 48):
another factor is that the 737 is a higher production rate airplane

Are you sure of this?

It depends on what you use for the denominator in "rate". Airbus makes A320's at three sites with multiple final assembly lines per site (there are three FAL's in Hamburg alone) while Boeing makes 737's at one site with two FAL's (not counting the P-8 FAL which can build commercial 737's but currently doesn't).

The speed at which each airplane moves through the FAL is much higher for a 737 than an A320; the rate is higher. Airbus has more FAL's going so their total output is higher.

Tom.


User currently offlinedfwrevolution From United States of America, joined Jan 2010, 977 posts, RR: 51
Reply 114, posted (2 years 5 months 1 week 1 day 18 hours ago) and read 6480 times:

Quoting lightsaber (Reply 105):
One nitpick: More stages=more surface area (of the blades as well as casing). Due to the high speed flow of the core, surface area=drag. Thus, one advantage of the GTF is less parasitic loss by extracting the horsepower in fewer stages.

How does that balance with leakage per stage? Typically fewer stages = greater pressure drop per stage = greater leakage flow. For industrial turbines where weight doesn't matter, you will see designers maximize the number of stages to the extent that is reasonable. It's usually casing/rotor length and bearing span that become the limiting factor before drag.

Obviously this is an aeroengine, so the desire to minimize weight is understandable.


User currently offlineJoeCanuck From Canada, joined Dec 2005, 5471 posts, RR: 30
Reply 115, posted (2 years 5 months 1 week 1 day 18 hours ago) and read 6421 times:

Quoting lightsaber (Reply 105):

One nitpick: More stages=more surface area (of the blades as well as casing).

I'm just using huge generalities...nothing is ever free...but definitely a good point to bring up...drag is as relevent as anything else when considering efficiency.



What the...?
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 116, posted (2 years 5 months 1 week 1 day 18 hours ago) and read 6424 times:

Quoting imiakhtar (Reply 110):
Quoting Roseflyer (Reply 48):
another factor is that the 737 is a higher production rate airplane

Are you sure of this?

Airbus A320 family deliveries in 2011 - 421
Boeing B737 family deliveries in 2011 - 372

I don't work in the manufacturing industry so I guess I could have misunderstood what you meant by 'higher production rate'.

Sorry for the confusion, but I was referring to the quantity of CFM56s built for the 737NG versus the quantity of CFM56s built for the A320. More CFM56s are built for the 737 annually than A320 because there are three different engine manufacturers involved with the A320 program.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 117, posted (2 years 5 months 1 week 1 day 16 hours ago) and read 6327 times:
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Quoting dfwrevolution (Reply 114):
How does that balance with leakage per stage? Typically fewer stages = greater pressure drop per stage = greater leakage flow.

Every stage has tip leakage as well as other inefficiencies (e.g., the rotor is drag too...). So there is a trade. The greater the *pressure drop* (usually expressed as a pressure ratio), the less efficient the turbine stage. However, it is a fairly benign trade, up to a point, due to the favorable pressure gradient. The greater the mach number in the turbine, the less the penalty. The 'usable Mach #' is a function of the turbine blade rotational speed (2*pi*radius*rotational speed) which can be called 'RPM.'   In other words, because the GTF's low turbine is spining faster, more work may be extracted per stage with little penalty.

Quoting JoeCanuck (Reply 115):
nothing is ever free

Exactly. The GTF is analogous to single crystal turbine blades. The concept was simple and known... Pratt's PW2000 showed it wasn't that straight forward (turbine never met durability promise and the high turbine is typically 60% of the overhaul cost!). Ugh oh...

The same was true of the GE-90s fan. Those problems cost GE a billion dollars. But... it was money well spent. Pratt is trying to pre-spend the money. (Its far cheaper to do the engineering and test a head of time than after EIS.)

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 118, posted (2 years 5 months 1 week 1 day 11 hours ago) and read 6144 times:

And now:

The Boeing 737 MAX and the GTF (Posted on April 16, 2012 by leehamnet)


* GTF on the MAX is the story that won't die
* Boeing's Mike Bair says Boeing has the right to use the GTF if "the engine and commercial terms are superior to any engine offered by CFM"
* Superior is being interpreted as meaning 3%-5% better fuel burn
* Airbus's Leahy says GTF is 1.5% better than LEAP on A320NEO

So, if Pratt does come out with a clearly superior GTF, Boeing is allowed to put it onto the MAX.



Inspiration, move me brightly!
User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 119, posted (2 years 5 months 1 week 1 day 10 hours ago) and read 6083 times:
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Quoting Revelation (Reply 118):
So, if Pratt does come out with a clearly superior GTF, Boeing is allowed to put it onto the MAX.

And order is restored to the world.

Oh who am I kidding.  


User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 120, posted (2 years 5 months 1 week 22 hours ago) and read 5766 times:

Quoting Revelation (Reply 118):
* GTF on the MAX is the story that won't die
* Boeing's Mike Bair says Boeing has the right to use the GTF if "the engine and commercial terms are superior to any engine offered by CFM"
* Superior is being interpreted as meaning 3%-5% better fuel burn
* Airbus's Leahy says GTF is 1.5% better than LEAP on A320NEO

So the scenario that the GTF could end up on the MAX requires a 3%-5% shortfall of the Leap vs the GTF.

Boeing's considerations and the relating noise show one thing: Boeing does indeed not rule out (if not flatly anticipate) a 3%-5% shortfall of the Leap vs. the GTF. At least they distrust enough to publish their viewpoint openly. So the day the GTF on the MAX would be announced, we know from the conditions for that to happen, would have to be a dark hour for CFM.

This adds significant weight to the topic of this thread (doubts about the LEAP on the MAX). In fact it is dramatic and it vindicates certainly the questions raised by the article Aeroturbopower quotes.

Because, if the Leap will really be up to 5% worse than the GTF, even free engines probably won't help anymore to buy market share for CFM...  


User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 121, posted (2 years 5 months 1 week 21 hours ago) and read 5669 times:

Quoting rheinwaldner (Reply 120):
Boeing does indeed not rule out (if not flatly anticipate) a 3%-5% shortfall of the Leap vs. the GTF.

That's not what I think a neutral party would get out of that statement.

A reporter asked if Boeing had the rights to use an engine other than CFM, and Bair answered the question.

He ventured no opinion at all about if LEAP would suffer a shortfall.

And you seemed to ignore Leahy's data saying the difference is not anywhere near 4% on the platform that allows the huge fan you mention all the time.

Quoting rheinwaldner (Reply 120):
At least they distrust enough to publish their viewpoint openly.

That's to be expected - it pays for Boeing to keep CFMi's feet to the fire.

Some other things being published are CFM's LEAP contract figures:

Lion Air: $4.8B
Norwegian: $2.9B
Southwest: $4.7B

Ref: http://www.cfm56.com/press

I'm sure you've heard the old saying, "money talks"...

Quoting rheinwaldner (Reply 120):
So the day the GTF on the MAX would be announced, we know from the conditions for that to happen, would have to be a dark hour for CFM.

Agree it would be a challenge CFM would rather avoid, but as others have pointed out, GTF is not killing LEAP on the NEO and there's no real data to suggest it will on the MAX.



Inspiration, move me brightly!
User currently onlinesirtoby From Germany, joined Nov 2007, 378 posts, RR: 22
Reply 122, posted (2 years 5 months 1 week 21 hours ago) and read 5575 times:

Quoting Revelation (Reply 121):
Lion Air: $4.8B
Norwegian: $2.9B
Southwest: $4.7B

...at list prices. But nobody pays list prices!


User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 123, posted (2 years 5 months 1 week 21 hours ago) and read 5560 times:

Quoting Revelation (Reply 121):
Quoting rheinwaldner (Reply 120):
Boeing does indeed not rule out (if not flatly anticipate) a 3%-5% shortfall of the Leap vs. the GTF.

That's not what I think a neutral party would get out of that statement.

There are other statements in the article, that support overall what I have written. E.g. this one:

"We continue to hear that Boeing is seriously evaluating adding the GTF as an offering on the MAX."

"Evaluating seriously the GTF" can only mean what I have said:
That Boeing doesn't rule out a 3%-5% shortfall of the Leap vs. the GTF. Otherwise they would not have to evaluate this eventuality.

Quoting Revelation (Reply 121):
And you seemed to ignore Leahy's data saying the difference is not anywhere near 4% on the platform that allows the huge fan you mention all the time.

I forgot to comment this one.

What Leahy has said either means one of the following:

- He plays the gap down (could be a deceiptive tactic to keep everybody in a false sense of security until it would pop up very late that Boeing has put on the wrong horse).

- What he says is true (for the NEO). Which would mean that there could be a gap between the LEAP for the NEO and the LEAP for the MAX. Not a convenient interpretation from Boeing's perspective.

- Leahy said this before the test results of the GTF gave very encouraging feedback.

At least Leahy indicated that the GTF was in the lead from early on. So the 4% to be gained over some years could indeed be in addition this initial gap. Yielding an overall advantage of more than 4%.


User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 124, posted (2 years 5 months 1 week 19 hours ago) and read 5472 times:
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Quoting Revelation (Reply 118):
* Boeing's Mike Bair says Boeing has the right to use the GTF if "the engine and commercial terms are superior to any engine offered by CFM"

That is a HUGE barrier for Pratt/UTC to overcome. The commercial terms would include GEAC's ability to finance the complete airframe. That is an advantage Pratt is just not positioned to be as competitive.  
Quoting Revelation (Reply 118):
* Airbus's Leahy says GTF is 1.5% better than LEAP on A320NEO

Which mission? Due to the variable nozzle, the GTF should be better on longer missions. 1.5% is about the advantage on short 400nm to 600nm (e.g., European) missions. If it is only 1.5% on short missions, it will make the LEAP-X attractive to more European airlines (e.g., Easyjet).

The GTF advantage will be in the 2% to 4% range for longer missions. I believe that is where this older article had its fuel burn difference:
http://airinsight.com/2011/04/19/ber...-looks-at-gtf-leap-x-side-by-side/

Quoting rheinwaldner (Reply 123):
"Evaluating seriously the GTF" can only mean what I have said:
That Boeing doesn't rule out a 3%-5% shortfall of the Leap vs. the GTF.

Is Boeing negotiating more with GE? I'm still not hearing anything that serious about a GTF on the MAX.

Would I like to see the GTF on the 737?    I'm just not seeing the business case. Unless the full 4% 'fuel burn in reserve' is met. In that case, Boeing would have to talk to Pratt and ignore 'commercial terms.' A 5% drop in fuel burn is more than 200nm additional range. How could Boeing ignore that?

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 125, posted (2 years 5 months 1 week 19 hours ago) and read 5459 times:

Quoting rheinwaldner (Reply 123):
What Leahy has said either means one of the following:

- He plays the gap down (could be a deceiptive tactic to keep everybody in a false sense of security until it would pop up very late that Boeing has put on the wrong horse).

So you believe that Leahy may be decieving his own customers to take an inferior product? He's selling just as many LeapX engines as PW GTFs. I think you invented that possibility to support a crusade against Boeing/CFM. Leahy would not decieve his customers into choosing an inferior product as a way to prevent Boeing from putting the PW GTF on the MAX. Airbus would create an exclusive marketing agreement with PW and use legitimate business practices to do so if their goal was to exclusively use the PW GTF. If the LeapX was so bad, they would never have chosen it at Airbus.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinePlanesNTrains From United States of America, joined Feb 2005, 5582 posts, RR: 28
Reply 126, posted (2 years 5 months 1 week 19 hours ago) and read 5438 times:

Quoting rheinwaldner (Reply 123):
- He plays the gap down (could be a deceiptive tactic to keep everybody in a false sense of security until it would pop up very late that Boeing has put on the wrong horse).

Wow - you must REALLY want the GTF on the MAX to become reality! I mean, he'd throw his own customers' best interests under the bus just to make Boeing look bad.

He_is_clever!

-Dave



Next Trip: SEA-ABQ-SEA on Alaska
User currently offlinePHXA340 From United States of America, joined Mar 2012, 891 posts, RR: 1
Reply 127, posted (2 years 5 months 1 week 18 hours ago) and read 5390 times:

Quoting rheinwaldner (Reply 120):
Boeing's considerations and the relating noise show one thing: Boeing does indeed not rule out (if not flatly anticipate) a 3%-5% shortfall of the Leap

I take that consideration as a consideration and nothing more. Boeing also considered a sonic cruiser, and full double decker 747 ... but alas none of it came to frutition, Boeing will always keep options and doors open. Does it mean Boeing thinks the LEAP is going to underperform ... could be , but it is way more likely that Boeing is being a good business and always looking at their options.


User currently offlineneutronstar73 From United States of America, joined Mar 2011, 506 posts, RR: 0
Reply 128, posted (2 years 5 months 1 week 18 hours ago) and read 5377 times:

Quoting rheinwaldner (Reply 123):
That Boeing doesn't rule out a 3%-5% shortfall of the Leap vs. the GTF. Otherwise they would not have to evaluate this eventuality.

This statement makes no sense. All that says is "Boeing has set a certain parameter by which, if GE/CFM fail to meet this benchmark, will trigger a consideration of the GTF." It does not mean Boeing is basically expecting the LEAP to fail so they are looking at the GTF.

Does that make any sense? Boeing is essentially, KNOWINGLY, squandering billions of dollars on a product they know will fail, just so they can spend another billion dollars on an engine they really want.

Your logic escapes me on this one.


User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 129, posted (2 years 5 months 1 week 18 hours ago) and read 5369 times:
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If Boeing really felt LEAP-X was going to flop, you'd think they could have made a stronger case to airlines to wait until NSA.

Heck, the airlines themselves evidently feel LEAP-X is not going to be a dog, otherwise they'd have waited for NSA with the GTF or forced Boeing to adopt GTF for the MAX from the onset. Not to mention they are ordering it on the A320neo, where they do have the option of GTF.


User currently offlineredrooster3 From United States of America, joined Oct 2010, 229 posts, RR: 2
Reply 130, posted (2 years 5 months 1 week 17 hours ago) and read 5316 times:

On Flightglobal, there's an article on the MAX having a chance of getting raked wingtips like the P-8 and the 77W. They're testing it in the wind tunnels.

737 Max wingtips kept under wraps

Say Boeing does add the GTF as an option, and the raked tips prove to be better for the 737. Could this be a possible turnover for the 737 in efficiency against the A320? I'm kind of excited.

Also, if they chose the GTF, would they have to extend the even up higher?



The only thing you should change about a woman is her last name.
User currently offlinePHXA340 From United States of America, joined Mar 2012, 891 posts, RR: 1
Reply 131, posted (2 years 5 months 1 week 17 hours ago) and read 5309 times:

Quoting redrooster3 (Reply 130):
On Flightglobal, there's an article on the MAX having a chance of getting raked wingtips like the P-8 and the 77W. They're testing it in the wind tunnels.

I thought this was debunked because the raked wingtips wouldn't fit in most of the gate spaces of current operators.


User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 132, posted (2 years 5 months 1 week 17 hours ago) and read 5260 times:

Quoting sirtoby (Reply 122):
Quoting Revelation (Reply 121):
Lion Air: $4.8B
Norwegian: $2.9B
Southwest: $4.7B

...at list prices. But nobody pays list prices!

Yes, it is understood that press releases cite list prices.

The point I was making is that LEAP already has $billions of commitments on 737-MAX which won't even fly for another four years.

Quoting rheinwaldner (Reply 123):

"Evaluating seriously the GTF" can only mean what I have said:
That Boeing doesn't rule out a 3%-5% shortfall of the Leap vs. the GTF. Otherwise they would not have to evaluate this eventuality.

Can only mean?

Are you saying there is no possibility that Boeing is evaluating the GTF on an ongoing basis for other reasons, such as competitive evaluation?

Quoting rheinwaldner (Reply 123):
What Leahy has said either means one of the following:

... or, the difference on the A320 will be 1.5%.

Quoting lightsaber (Reply 124):
Which mission? Due to the variable nozzle, the GTF should be better on longer missions. 1.5% is about the advantage on short 400nm to 600nm (e.g., European) missions. If it is only 1.5% on short missions, it will make the LEAP-X attractive to more European airlines (e.g., Easyjet).

The GTF advantage will be in the 2% to 4% range for longer missions.

Yes, there are many moving targets.

We should know more as the GTF rolls out in 2013 for the C Series, 2014 for MRJ and 2015 for NEO, and LEAP rolls out in 2016 on C919 and NEO.

Boeing has made statements that their LEAP is not going to be the same as the one on the NEO:

Quote:

Hamilton said of the design: "With development programmes, you start with one engine and you start to refine it. The initial engine that CFM proposed to us probably had a lot of commonality with the C919 and [A320neo], but that was kind of our starting point. But we're going to continue to work with CFM every day on this and continue to customise the engine so that it is unique for the 737."

"We haven't finalised all the details of the engine, but we've dialed it in enough now, we know that we can get much better performance than what" was known when the evaluations first began with the baseline engine configuration, said Hamilton.

Ref: http://www.flightglobal.com/news/art...w-of-737-max-configuration-364297/

Leeham has more details but he is not revealing sources:

Quote:

Details are still sketchy and hard to come by. But our source has direct knowledge of the program.

Our source compared the requirement to reduce the fan size of the 737 LEAP from 78 inches on the Airbus A320 neo to 68 1/2 inches on the MAX to the fan reduction on the GEnx from the 787 to the 747-8. The 747-8 engines are optimized for this aircraft despite the smaller fan size.

Reducing the fan enables CFM to eliminate some LPT stages, our source explains, which also cuts other parts.

This eliminations allow the LEAP to be shorter, which also allows the engine mounting to be shorter.

CFM is also using ceramics to the MAX LEAP.

Ref: http://leehamnews.wordpress.com/2012...02/08/optimizing-leap-for-737-max/

So, lots of moving targets to shoot at.



Inspiration, move me brightly!
User currently offlineredrooster3 From United States of America, joined Oct 2010, 229 posts, RR: 2
Reply 133, posted (2 years 5 months 1 week 17 hours ago) and read 5245 times:

Quoting PHXA340 (Reply 131):
I thought this was debunked because the raked wingtips wouldn't fit in most of the gate spaces of current operators.

I never heard that? I know the 737NG's wingspan is wider than the A320 by 6 feet.

After looking at previous posts from What About A 739ER With The Wings Of The P-8? (by EA772LR Apr 6 2010 in Civil Aviation)

and

"737" Raked Wingtips Better Than Blended Winglets? (by Ikramerica Jun 4 2005 in Tech Ops) .

It seems that gate space is the issue...  



The only thing you should change about a woman is her last name.
User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 134, posted (2 years 5 months 1 week 16 hours ago) and read 5178 times:
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Quoting redrooster3 (Reply 130):

On Flightglobal, there's an article on the MAX having a chance of getting raked wingtips like the P-8 and the 77W. They're testing it in the wind tunnels.

Boeing is being aggressive with several aerodynamic tweaks on the MAX. The new tail cone, I've heard discussion of other aerodynamic fairings too. Boeing will do what they have to; I have no doubt the MAX will sell.

I'm still a GTF fan.   

Quoting redrooster3 (Reply 130):
Say Boeing does add the GTF as an option, and the raked tips prove to be better for the 737. Could this be a possible turnover for the 737 in efficiency against the A320?

Which mission? I do not see it likely that either will be superior for all missions. With fewer low pressure turbine stages in the MAX LEAP-X, it will be an engine optimized for shorter missions than the A320 engine. That is simply the nature of the trade study.

Quoting Revelation (Reply 132):
We should know more as the GTF rolls out in 2013 for the C Series, 2014 for MRJ and 2015 for NEO, and LEAP rolls out in 2016 on C919 and NEO.

Boeing has made statements that their LEAP is not going to be the same as the one on the NEO:

An exciting time for narrow body engines.   

Quoting Revelation (Reply 132):
Are you saying there is no possibility that Boeing is evaluating the GTF on an ongoing basis for other reasons, such as competitive evaluation?

I would be shocked if Boeing wasn't evaluating the GTF for said competitive evaluation reasons.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 135, posted (2 years 5 months 1 week 15 hours ago) and read 5061 times:

Quoting lightsaber (Reply 134):
I'm still a GTF fan.

I'm a huge GTF fan too.

Quoting lightsaber (Reply 134):
I have no doubt the MAX will sell.

Indeed. That was my point about putting up some of the sales numbers: it is already selling, and I'm sure it will continue to sell.

Quoting lightsaber (Reply 134):
An exciting time for narrow body engines.

Yes, it is interesting because GTF is applying lots of pressure on LEAP.

I think there's a pretty good chance that GTF will outclass the LEAP in terms of performance.

At this point in time it's my guess that it's maybe a one in five chance that GTF will do enough to make Boeing seriously consider putting it onto the 737.

The reason the number is so high is the technical potential of the GTF and the fact that aircraft purchasers would like an engine choice

The main reasons why the number isn't higher:
- CFM's technical potential and engineering resources
- CFM's advantage in support network and training
- GE's and CFM's existing customer relationships
- GE's advantages in financing
- Cost to integrate and qualify a second engine
- Damage to resale value by having two different engines

Quoting lightsaber (Reply 134):
I would be shocked if Boeing wasn't evaluating the GTF for said competitive evaluation reasons.

Indeed.

We've already seen the infamous Airbus 787 dossier.

We can be sure similar ones exist within Boeing, CFM, Pratt, etc.



Inspiration, move me brightly!
User currently offlineEPA001 From Netherlands, joined Sep 2006, 4739 posts, RR: 39
Reply 136, posted (2 years 5 months 1 week 15 hours ago) and read 4968 times:
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Quoting Revelation (Reply 135):
Quoting lightsaber (Reply 134):
I'm still a GTF fan.

I'm a huge GTF fan too.

Big fans deserve big fans here.   I am also very enthusiastic about the GTF-concept. I hope Pratt can really make it work.  .


User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 137, posted (2 years 5 months 1 week 13 hours ago) and read 4836 times:
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Quoting Revelation (Reply 135):
- Cost to integrate and qualify a second engine
- Damage to resale value by having two different engines

I agree with your other points. These two I'd like to discuss.

The cost to integrate and qualify a second engine is hundreds of millions. That will be more than made up by having the two engine vendors discount for each sale. IMHO, at the high sales rates of the narrowbodies, it is an advantage having two engines bid against each other. The minimum production rate to have multiple engines is somewhere between 30 to 50 *of each engine* per year to justify the alternative. I doubt either engine will have that low of a share of either the Airbus/Boeing narrowbody market.

I agree the resale is helped by having one engine. However, once there are over 500 of any type and over 20 operators, which I'm sure both engines would achieve on the MAX, it isn't that harsh of a hit.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 138, posted (2 years 5 months 1 week 12 hours ago) and read 4783 times:

Quoting lightsaber (Reply 137):
IMHO, at the high sales rates of the narrowbodies, it is an advantage having two engines bid against each other. The minimum production rate to have multiple engines is somewhere between 30 to 50 *of each engine* per year to justify the alternative. I doubt either engine will have that low of a share of either the Airbus/Boeing narrowbody market.

While it makes sense with narrowbody production rates to have multiple engine choices, if you look at history, the A320 was the first narrowbody to be produced with engine options other than the larger 757. The DC-9/MD-80 was single source. The 737 has always been single source. The 727 was single source. With how integrated the airframe is with the engine on the narrowbodies, they have always been single source until Airbus changed it. Going forward, the A320 NEO is still the only narrowbody airplane that strays from the norm of single engine/airframe combination.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineredrooster3 From United States of America, joined Oct 2010, 229 posts, RR: 2
Reply 139, posted (2 years 5 months 1 week 12 hours ago) and read 4764 times:

Quoting lightsaber (Reply 134):
Which mission? I do not see it likely that either will be superior for all missions. With fewer low pressure turbine stages in the MAX LEAP-X, it will be an engine optimized for shorter missions than the A320 engine. That is simply the nature of the trade study.

I was leaning more towards overall. I think the NG/A320 are very similar in overall costs for airlines.

Quoting lightsaber (Reply 134):
I have no doubt the MAX will sell.

Its either 1000 MoU's/Firms, or 1000 MoU's + Firms for the 737 max, from this latest article

Boeing in Australia to promote the 737 MAX

Quote:
Boeing says it has “commitments” for more than 1000 aircraft and it hopes to be able to reveal details of customers and orders at the Farnborough Airshow this year.



The only thing you should change about a woman is her last name.
User currently offlineHamlet69 From United States of America, joined Mar 2000, 2744 posts, RR: 58
Reply 140, posted (2 years 5 months 1 week 6 hours ago) and read 4565 times:

Quoting redrooster3 (Reply 130):
On Flightglobal, there's an article on the MAX having a chance of getting raked wingtips like the P-8 and the 77W. They're testing it in the wind tunnels.

As Boeing "looks at their options" so-to-speak, I wonder how closely they'll look at APB's Next-Generation winglet:

http://www.flightglobal.com/blogs/fl...plit-scimitar-winglet-next-on.html


Raked tips are good, but do increase span more than blended winglets. That might prohibit their use on NB aircraft like the 737 MAX. OTOH - years ago, Boeing studied the possibility of "interchangeable wingtips" for the 767. The idea was that, by re-doing the structure of the wingtip, Boeing would offer customers the option of swapping in-and-out a blended winglet, depending of the immediate foreseeable mission. The idea obviously didn't get too far, but I never heard if that was due to operational/design constraints, or just a general lack of customer interest in the 767 all together. . .


Regards,

Hamlet69



Honor the warriors, not the war.
User currently offlinelightsaber From United States of America, joined Jan 2005, 13134 posts, RR: 100
Reply 141, posted (2 years 5 months 1 week 5 hours ago) and read 4501 times:
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Quoting Hamlet69 (Reply 140):
As Boeing "looks at their options" so-to-speak, I wonder how closely they'll look at APB's Next-Generation winglet:

Winglets. They have several options. However, IIRC, the spiroid are more optimal at slightly lower Mach numbers than the 737s cruise speed.

Since the MAX would be a great time to switch winglets (e.g., reinforce the wing, if required), it would be silly for Boeing not to text new winglets.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently onlinerheinwaldner From Switzerland, joined Jan 2008, 2226 posts, RR: 5
Reply 142, posted (2 years 5 months 1 week 2 hours ago) and read 4306 times:

Quoting lightsaber (Reply 124):
That is a HUGE barrier for Pratt/UTC to overcome. The commercial terms would include GEAC's ability to finance the complete airframe. That is an advantage Pratt is just not positioned to be as competitive.

I agree. Sadly the GTF on the MAX in reality seems not to have much chances (despite all the talk).

Quoting Roseflyer (Reply 125):
So you believe that Leahy may be decieving his own customers to take an inferior product? He's selling just as many LeapX engines as PW GTFs.

You know as well as I, that the terms under which CFM has bought probably their market share have not been defined by Leahy. Leahy sells NEO's. And then the customer picks the better engine with hardly any input from Leahy. It is the job of sales teams from Pratt and CFM to sell the engines.

Quoting PlanesNTrains (Reply 126):
Wow - you must REALLY want the GTF on the MAX to become reality! I mean, he'd throw his own customers' best interests under the bus just to make Boeing look bad.

There is not the smallest reference about my will in my statement.

And as Leahy is probably quite unemotional regarding the engine a customer selects, I really smell a side blow in his statement. As a much more blunt attack on the MAX he could adore the GTF and exaggerate its potential and just conclude, that the MAX won't have it. But this PR strategy would increase the pressure on Boeing to bring the GTF on the MAX. But by stating a very mild advantage, he could indeed achieve a lulling effect. Hey, everything is alright, the NEO, the GTF, the LEAP and the MAX...

Quoting PHXA340 (Reply 127):
Does it mean Boeing thinks the LEAP is going to underperform ... could be

True, I too would not go any further.

Quoting PHXA340 (Reply 127):
but it is way more likely that Boeing is being a good business and always looking at their options.

Also true.
On the other side, do you think that Boeing is also always looking at their options to power the 777? Or would they just stay with the GE90 without considering the rest? Can we assume that Boeing has also defined some conditions under which they would look at a GE90-competitor? If all this talk about the GTF on the MAX is true, the barrier defined by these conditions in case of the 737 at least must have been broken potentially by the GTF...

Quoting neutronstar73 (Reply 128):
All that says is "Boeing has set a certain parameter by which, if GE/CFM fail to meet this benchmark, will trigger a consideration of the GTF."

Exactly, so shall we agree that this trigger could have been pulled already (look how much rumours about the GTF on the MAX are floating around)?

Quoting Stitch (Reply 129):
If Boeing really felt LEAP-X was going to flop, you'd think they could have made a stronger case to airlines to wait until NSA.

Probably at the time Boeing had to decide, the real qualities of the GTF maybe not have emerged so credibly as today.

Quoting Revelation (Reply 132):
Are you saying there is no possibility that Boeing is evaluating the GTF on an ongoing basis for other reasons, such as competitive evaluation?

It is a possibility of course. Especially if Pratt's increasing confidence is backed up by more and more real test data (so breaking the 3-5% barrier can't be ruled out anymore, which is roughly what we dispute here).


User currently offlineRevelation From United States of America, joined Feb 2005, 12564 posts, RR: 25
Reply 143, posted (2 years 5 months 1 week ago) and read 4112 times:

Quoting rheinwaldner (Reply 142):
Can we assume that Boeing has also defined some conditions under which they would look at a GE90-competitor? If all this talk about the GTF on the MAX is true, the barrier defined by these conditions in case of the 737 at least must have been broken potentially by the GTF...

Sure, why not?

Wiki writes the following:

Quote:

Trent 8104

In 1998 Boeing proposed new longer range variants of the 777X. Taking advantage of the Trent 800's growth capability, Rolls-Royce designed and built an improved engine designated Trent 8104, which was later scaled upwards to the even larger 8115. This development was the first engine to break through 100,000 lbf (440 kN) thrust and subsequently the first to reach 110,000 lbf (490 kN). However, GE Aviation former president James McNerney (now Boeing CEO) successfully offered the aircraft manufacturer up to $500 million in money to develop the 777X in exchange for exclusivity in powering the family. Boeing agreed in July 1999 to such a deal with the GE90-110B and GE90-115B to be the sole engines on the long-range 777s.[14] This resulted in the 8104 becoming just a demonstrator programme, despite setting further industry firsts for thrust levels achieved and the first to demonstrate the use of a fully swept wide chord fan.

Ref: http://en.wikipedia.org/wiki/Rolls-Royce_Trent

So RR had developed the T8104 to try to get on the 777-300ER / 777-200LR, but then GE brought its substantial financial strength to bear and that tipped the scales. As above, money talks.

Quoting rheinwaldner (Reply 142):
Probably at the time Boeing had to decide, the real qualities of the GTF maybe not have emerged so credibly as today.
Quoting rheinwaldner (Reply 142):
It is a possibility of course. Especially if Pratt's increasing confidence is backed up by more and more real test data (so breaking the 3-5% barrier can't be ruled out anymore, which is roughly what we dispute here).

The problem I am having is that you are saying there is some smoke, so there must be a fire.

It has been known that PW has left itself some margin for many years now.

It is also well known that Boeing must keep its eyes on the GTF for many different reasons, up to and including potentially putting it onto the 737.

It is not known what the root source of the current rumours about GTF on the 737 are.

They could be that Boeing is seriously evaluating it, or it could be that someone who has an interest in seeing GTF on the 737 let a rumour drop at ISTAT.

All we have is rumours. No sightings of senior PW execs sitting down with Boeing, no GTF hanging off a Boeing testbed, etc.

We see smoke on the horizon. It could be a fire, or it could be a ruptured steam pipe. We have no way of knowing the difference.

As a PW and GTF fan, I'd love to see it on the 737, but I have a hard time seeing it happen. As above, at this point in time I see at best one in five odds. If we start getting some hard data about it exceeding plan on the C Series I may change the odds, but not until.



Inspiration, move me brightly!
User currently offlineStitch From United States of America, joined Jul 2005, 31003 posts, RR: 86
Reply 144, posted (2 years 5 months 6 days 20 hours ago) and read 3947 times:
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Quoting rheinwaldner (Reply 142):
Probably at the time Boeing had to decide, the real qualities of the GTF maybe not have emerged so credibly as today.

I've been hearing that Pratt has been holding back SFC for a good bit longer than mid-2011, when the 737 MAX was announced.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9643 posts, RR: 52
Reply 145, posted (2 years 5 months 6 days 17 hours ago) and read 3813 times:

Quoting rheinwaldner (Reply 142):
Quoting Roseflyer (Reply 125):
So you believe that Leahy may be decieving his own customers to take an inferior product? He's selling just as many LeapX engines as PW GTFs.

You know as well as I, that the terms under which CFM has bought probably their market share have not been defined by Leahy. Leahy sells NEO's. And then the customer picks the better engine with hardly any input from Leahy. It is the job of sales teams from Pratt and CFM to sell the engines.

So are you saying that because the customer picks the engines themselves, it is ok for Leahy t