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zkojq
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Tue Jun 11, 2019 10:23 pm

marcelh wrote:
Reading a lot of comments, I get the impression that the 779 won’t sell. If an airline needs the capacity and is able to fill it, they will buy the plane. And how “superior” it will be to the A35K remains to be seen. Time will tell.


Agreed. For nearly all missions, the 787-10 is a far superior platform. Boeing has optimised the 777-9 for ULH ops, so on shorter routes the 787-10 has much better economics. Even more so if there is substance to the 6t extra MTOW bump.
First to fly the 787-9
 
planecane
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Tue Jun 11, 2019 10:44 pm

zkojq wrote:
marcelh wrote:
Reading a lot of comments, I get the impression that the 779 won’t sell. If an airline needs the capacity and is able to fill it, they will buy the plane. And how “superior” it will be to the A35K remains to be seen. Time will tell.


Agreed. For nearly all missions, the 787-10 is a far superior platform. Boeing has optimised the 777-9 for ULH ops, so on shorter routes the 787-10 has much better economics. Even more so if there is substance to the 6t extra MTOW bump.


Huh? The 787-10 has a 2 class seating spec of 330 while the 777-9 has a 2 class seating spec of 414. The 787-10 has a brochure range of over 1000 nmi less. These two aren't in the same class at all. Unless you mistyped and meant the 777-8 which might not ever be built.
 
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Stitch
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Tue Jun 11, 2019 10:58 pm

smartplane wrote:
Perhaps another reason for a delay, is review of FAA compliance maturity accorded to Boeing, which underpins the level of self-approval for the MAX and X?


That should impact final certification, not First Flight?
 
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LAX772LR
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 4:45 am

BlueSky1976 wrote:
LAX772LR wrote:
Sincerely doubt Boeing ever expected the aircraft to be much of a seller, if at all, with US airlines..... *maybe* replacing AA/UA's 77Ws some 20yrs down the road, but that's about the foreseeable extent of it.

If Boeing didn't expect the aircraft to be "much of a seller", it wouldn't start the program.

You should probably pay a bit closer attention before replying.
Missing those three words completely changes the context of your response.
I myself, suspect a more prosaic motive... ~Thranduil
 
Max Q
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 5:21 am

Carmitage wrote:
Max Q wrote:
Chaostheory wrote:

Airlines don't play Top Trumps.

The RB211 on the 757 burns anywhere from 4-8% more than the Pratt (depending on mods) yet it still had more customers. The GTF on the neo has an appreciable fuel burn advantage over the leap which will widen when the PIPs become available in the next 12-18 months, yet the leap to my knowledge is the better seller.



I find that really hard to believe, 4-8 %
more burn for the RB211 on the 757 is
a massive difference


The Rolls-Royce version of events is that the -535 did burn more fuel as a new engine (not sure it was as much as 4-8%), but the degradation was much less (the triple spool engine was shorter, so had less whip, reducing the wear on the abradable seals) so the fuel burn through the life of the engine was less - ie if you selected on the basis of initial fuel burn, you went for P&W; through-life, go to RR.

They also were very reliable and sat on the wing for a very long time (vs peers at the time).



I’ve only operated the RR535-E4B, the most powerful engine available on the 757
and it is very efficient and smooth, I’ve heard the P&W engine burns a bit less but it’s sure not 4-8%


That’s massive, if there was that much of a difference no one would have bought the RR powerplant
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CHRISBA35X
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 7:38 am

I do find it funny to note on other threads where the A35K and 779X are mentioned - the same posters who have spent years telling us the A380 is a dinosaur and the VLA market is deader than Daenaerys, are now trying to espouse the notion that the 779X is going to sell in mega numbers as the VLA market isnt nearly as dead as they thought it was when the A380 was dominating it.. What is good for the goose is good for the gander, or so they say.

In this case, whilst the 380 was flawed in execution and had a few things going against it that stopped it from really pushing the VLA market on rather than being pushed off by the VLA market, i do think the 779X will end up more successful than the 380 (sadly from my point of view). More cargo, equivalent CASM, more flexibility, slightly lower purchase price, better second hand market theoretically, and its a twin.

Lets just hope the Boeing guys and girls get it right first time. Any MAX nightmares here would be the death of the programme and a seismic blow from which Boeing would take years to recover from. Fingers crossed.
 
Armadillo1
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 7:43 am

equivalent CASM compared to A380?
 
CHRISBA35X
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 8:04 am

Armadillo1 wrote:
equivalent CASM compared to A380?



Its ballpark close. Many posters on here would assert the 779X has lower CASM than an A380 at a typical 450 seat config but my view is the A380 is slightly better on CASM.

We wont know for definite until the 779X flies and is in service so its a point of debate but what we can say is that it is a CASM monster and that thats what the VLA game is all about. We know the 779X will have excellent CASM, but will it be 748i good or A388 good? Time will tell but it I guess it is broadly equivalent.
 
blackscorpion
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 8:17 am

It looks like GE are taking the GE9X is to the Paris Air Show

https://www.instagram.com/p/BylWR5xAo3b/
 
uta999
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 8:33 am

How can the CASM be on par with an A380, which has four relatively old (15 years) engines, vs two relatively modern dryers on the 777-9X. If it turns out to be similar then that is quite bad surely.
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crimsonchin
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 8:34 am

Isn't motelyfool basically a Boeing fanboy blog?
 
waly777
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 8:59 am

CHRISBA35X wrote:
Armadillo1 wrote:
equivalent CASM compared to A380?



Its ballpark close. Many posters on here would assert the 779X has lower CASM than an A380 at a typical 450 seat config but my view is the A380 is slightly better on CASM.

We wont know for definite until the 779X flies and is in service so its a point of debate but what we can say is that it is a CASM monster and that thats what the VLA game is all about. We know the 779X will have excellent CASM, but will it be 748i good or A388 good? Time will tell but it I guess it is broadly equivalent.


Using real world configs of airlines with A380's and 77W, the latter has better CASK than the 380. Moreso in a 10AB 77W Y cabin. The 779 in similar configs will further improve that CASK. I know Anet likes to use hypothetical configs of similar seating density per m2 of cabin (leeham did this in 2017 or 2018 and the 779 came well ahead of the 35K and 380), but the reality remains they are configured for different purposes and we have more than enough realistic comparison points.

CASK is not the 380's strong point, RASK is. Thus the heavy F+J configs on most airlines. It can cash in on ludicrous amounts of revenue that no other AC can when matched properly to demand.
The test of first-rate intelligence is the ability to hold 2 opposed ideas in the mind concurrently, and still function
 
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 9:02 am

crimsonchin wrote:
Isn't motelyfool basically a Boeing fanboy blog?


Motley is the platform. It's the writers who provide the articles. And even then, the articles are biased in many ways.

Much like the trash on seekingalpha too.

Back to 77x: the max capacity is 440 with eighth doors? Does this increase with the other type-A additional doors?
 
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 9:03 am

uta999 wrote:
How can the CASM be on par with an A380, which has four relatively old (15 years) engines, vs two relatively modern dryers on the 777-9X. If it turns out to be similar then that is quite bad surely.


You know the A380 is a considerably larger and higher capacity airframe than the 779X right? And that the A380 in typical layout is the single lowest CASM airframe in airline service today, and has been for some years?
 
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 9:10 am

Carmitage wrote:
Don't forget the GE90 was an absolute dog (so reliable BA used it on London to Paris, which is somewhat embarrassing for a long haul aircraft)

The early GE90s certainly had their teething issues, but it's a bit disingenuous to insinuate that the LON-PAR ops had to do with "reliability".... seeing as BA did (and still) uses that run for crew training and familiarization on essentially any new large aircraft they take.
I myself, suspect a more prosaic motive... ~Thranduil
 
waly777
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 9:20 am

FrenchPotatoEye wrote:
crimsonchin wrote:
Isn't motelyfool basically a Boeing fanboy blog?


Motley is the platform. It's the writers who provide the articles. And even then, the articles are biased in many ways.

Much like the trash on seekingalpha too.

Back to 77x: the max capacity is 440 with eighth doors? Does this increase with the other type-A additional doors?


It should increase to 475 with the additional type A doors.
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 9:59 am

Waterbomber2 wrote:
lightsaber wrote:
FrenchPotatoEye wrote:

Could you expand on that?

I echo Zekes remarks to be honest. I see nothing substantially new or ground breaking???

1. CMCs, first engine with the tech in commercial service.
2. High Mach # compressor.
3. Enhanced variable cycle tech. For certain the variable turbine cooling of the LEAP. I see actuators being bought for more, but I do not know the specifics.
4. Far more cooling systems than I've ever seen. The turbine clearance control is two generations ahead of anything I've ever seen. In fact, it is was Lefebvre (one of the great chief engineers of engine design) presented in 1995 to graduate students (me), GE, Pratt, and RR. Apparently another grad student listened and made sure this happened. The problem for me is which of my three grad school friends who attended that lecture made it happen. And which of Lefebvre's variable cycle ideas..
5. Low turbine tech. See LEAP-1B and take it a generation forward. Traditionally, I have been a fan of Pratt being the leader here, but GE stole the right Pratt people. See the incredible efficiency bump of the PW1100G with the low turbine enhancement.
6. Fan blade tip Mach number, without a GTF a required tech for installing the low turbine tech. You get one guess why Pratt is so far behind in this tech.
7. Enhanced materials in combustor (less cooling air)
8. Finally imitating Pratt in modeling airflow through the whole engine. Engines are a system and tweaking how air flows from:
a. Low compressor to high, the GE-90 and TrentXWB botched this to the tune of 1 to 1.5% system fuel burn. Hint, the director if Pratt engine development warned of this botch with the PW6000 early in his carrier. I'm quite certain Steve will never allow this to happen again.
b. High compressor to pre-diffuser. GE was always good at this, modern modeling has allowed a nice fuel efficiency increase.
c. High turbine to low turbine. Seriously, compared to Pratt the LEAP and Txwb are amateur hour here. Seriously? Pratt has only been mocking GE and RR on this since Pratt won the F119 vs. F120 clearly on this tech. I only mention military for the clear' this tech is awesome!' timeframe.

But the people who focus on component efficiency do not get how to maximize system efficiency. 'How can the engine burn 2% less fuel by making the low compressor 1/4% less efficient?'. Because that makes the high compressor and pre-diffuser that much more efficient... Sigh...

Then there are a bunch of little technologies GE is just good at such as pre-diffuserss and shorter combustors. Not to mention fans. GE invests more in fan design because they are the least ready for GTFs. Oops.

The Mach numbers in the high compressor still are not at what that one lecture discussed. That is because bearings and seals are not there (see PW1100G issues).

I like how people who don't understand the internals of an engine mock me. Everything I listed is a generation ahead. Everything presents risk being a generation ahead. That means the first flight delay when risk is realized.

I haven't yet begun to discuss what wing efficiency is enabled by folding wing tips. I could do a wing with 4% better L/D than the A350 wing, but only with the aspect ratio. At least I wouldn't do it without that extension to mitigate the risks. Nor have I discussed Boeing's latest take on electrical subsystems. I'm still scratching my head

I work aerospace R&D. I've been exposed to a lot. If you need an example of when adding weight improves a product, see A330NEO (extended wingspan that is heavy and much heavier engines)

Lightsaber


I would like to reply to this.
1. CMC is like pushing the envelope of what has already been done for decades.
Materials science and more materials science. Works well in labo's, in real life operations RR, GE and PW are struggling with this, call it the bleeding edge.
On the Leap, a CMC shroud coating was compromised way ahead of expected.

2. What is a high Mach compressor? You mean like high tip speed on the blades or high compressor face speed?

3. and 4. seems to be about HPT cooling. Not much to see that is worthy of a generation bump.

5. LPT shows nothing worthy of a generation bump compared to the the GEnx generation.

6. Fan blade tip Mach number, what is so special on the GE9X compared to the GE90? The PW GTF fan blades show a lot of aerodynamic improvements that are slightly ahead of the GE90, the GE9X is merely catching up. Nothing worthy of a generation bump versus the Trent XWB.

7. All recent aircraft engines have increased combustor efficiency, through materials and lean combustion processes, etc...

8. Many points that are not verifyable.


I've read through hundreds of GE/PW/RR patents and I think that the technology is still at the dinosaur stage.
In recent times PW is obsessed with reverse combustion GTF's, I call this the reverse combustion WTF's.

I think that the engine manufacturers still can improve the engines a looooooot and I'm making work personally to this end as well.
The GE9X claims a 10% gain over the GE90 and 5% over other widebody engines in operation, but it's very questionnable and not verifyable. What stage of flight are we talking about?

Hardly a generation ahead, hardly ahead at all.
Hardly worthy of the big and expensive redesign that Boeing is doing for the B777 and will be superseeded within 5 years by whatever goes on the A350neo.

I think that a generation bump will happen in the 2020's resulting in 30% lower fuel burn compared to the GE9X/TXWB and then we can talk about a generational advance.
It will involve a major rethink of the turbofan architecture as a whole and not only menial advances in materials, cooling and blade design.

As I said, when I look at turbofans today, I see dinosaurs. I see waste, waste and more waste.
Too many baby steps and the state of the art is laughable, you should see some of these recent patents. People are getting paid to come up with that?

About the delay. I don't see the B777X EISing before 2022.
First flight in 2020 and EIS in 2022 is most plausible.
If QF choose it for project Sunrise, they won't get deliveries until it's almost time for the A350neo.


Um. I'm with lightsaber on who knows what they are talking about here. Btw https://en.m.wikipedia.org/wiki/Mach_number
 
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keesje
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 10:01 am

uta999 wrote:
How can the CASM be on par with an A380, which has four relatively old (15 years) engines, vs two relatively modern dryers on the 777-9X. If it turns out to be similar then that is quite bad surely.


CASM is a playing tool for marketing. You can use the published seatcount that helps your end coclusion.

777x has similar seatcount than A380, maindeck. Both 10 abreast, A380significant wider though. 11 abreast is coming.
Then there is the additional upperdeck.Typical seatcount for most A380 is 500-550, including bars etc.
If you remove the bard and go 11 abreast main deck, 600-650 seats. is easily reached. CASM king, but again that oversimplification..
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Waterbomber2
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 10:12 am

Jouhou wrote:
Waterbomber2 wrote:
lightsaber wrote:
1. CMCs, first engine with the tech in commercial service.
2. High Mach # compressor.
3. Enhanced variable cycle tech. For certain the variable turbine cooling of the LEAP. I see actuators being bought for more, but I do not know the specifics.
4. Far more cooling systems than I've ever seen. The turbine clearance control is two generations ahead of anything I've ever seen. In fact, it is was Lefebvre (one of the great chief engineers of engine design) presented in 1995 to graduate students (me), GE, Pratt, and RR. Apparently another grad student listened and made sure this happened. The problem for me is which of my three grad school friends who attended that lecture made it happen. And which of Lefebvre's variable cycle ideas..
5. Low turbine tech. See LEAP-1B and take it a generation forward. Traditionally, I have been a fan of Pratt being the leader here, but GE stole the right Pratt people. See the incredible efficiency bump of the PW1100G with the low turbine enhancement.
6. Fan blade tip Mach number, without a GTF a required tech for installing the low turbine tech. You get one guess why Pratt is so far behind in this tech.
7. Enhanced materials in combustor (less cooling air)
8. Finally imitating Pratt in modeling airflow through the whole engine. Engines are a system and tweaking how air flows from:
a. Low compressor to high, the GE-90 and TrentXWB botched this to the tune of 1 to 1.5% system fuel burn. Hint, the director if Pratt engine development warned of this botch with the PW6000 early in his carrier. I'm quite certain Steve will never allow this to happen again.
b. High compressor to pre-diffuser. GE was always good at this, modern modeling has allowed a nice fuel efficiency increase.
c. High turbine to low turbine. Seriously, compared to Pratt the LEAP and Txwb are amateur hour here. Seriously? Pratt has only been mocking GE and RR on this since Pratt won the F119 vs. F120 clearly on this tech. I only mention military for the clear' this tech is awesome!' timeframe.

But the people who focus on component efficiency do not get how to maximize system efficiency. 'How can the engine burn 2% less fuel by making the low compressor 1/4% less efficient?'. Because that makes the high compressor and pre-diffuser that much more efficient... Sigh...

Then there are a bunch of little technologies GE is just good at such as pre-diffuserss and shorter combustors. Not to mention fans. GE invests more in fan design because they are the least ready for GTFs. Oops.

The Mach numbers in the high compressor still are not at what that one lecture discussed. That is because bearings and seals are not there (see PW1100G issues).

I like how people who don't understand the internals of an engine mock me. Everything I listed is a generation ahead. Everything presents risk being a generation ahead. That means the first flight delay when risk is realized.

I haven't yet begun to discuss what wing efficiency is enabled by folding wing tips. I could do a wing with 4% better L/D than the A350 wing, but only with the aspect ratio. At least I wouldn't do it without that extension to mitigate the risks. Nor have I discussed Boeing's latest take on electrical subsystems. I'm still scratching my head

I work aerospace R&D. I've been exposed to a lot. If you need an example of when adding weight improves a product, see A330NEO (extended wingspan that is heavy and much heavier engines)

Lightsaber


I would like to reply to this.
1. CMC is like pushing the envelope of what has already been done for decades.
Materials science and more materials science. Works well in labo's, in real life operations RR, GE and PW are struggling with this, call it the bleeding edge.
On the Leap, a CMC shroud coating was compromised way ahead of expected.

2. What is a high Mach compressor? You mean like high tip speed on the blades or high compressor face speed?

3. and 4. seems to be about HPT cooling. Not much to see that is worthy of a generation bump.

5. LPT shows nothing worthy of a generation bump compared to the the GEnx generation.

6. Fan blade tip Mach number, what is so special on the GE9X compared to the GE90? The PW GTF fan blades show a lot of aerodynamic improvements that are slightly ahead of the GE90, the GE9X is merely catching up. Nothing worthy of a generation bump versus the Trent XWB.

7. All recent aircraft engines have increased combustor efficiency, through materials and lean combustion processes, etc...

8. Many points that are not verifyable.


I've read through hundreds of GE/PW/RR patents and I think that the technology is still at the dinosaur stage.
In recent times PW is obsessed with reverse combustion GTF's, I call this the reverse combustion WTF's.

I think that the engine manufacturers still can improve the engines a looooooot and I'm making work personally to this end as well.
The GE9X claims a 10% gain over the GE90 and 5% over other widebody engines in operation, but it's very questionnable and not verifyable. What stage of flight are we talking about?

Hardly a generation ahead, hardly ahead at all.
Hardly worthy of the big and expensive redesign that Boeing is doing for the B777 and will be superseeded within 5 years by whatever goes on the A350neo.

I think that a generation bump will happen in the 2020's resulting in 30% lower fuel burn compared to the GE9X/TXWB and then we can talk about a generational advance.
It will involve a major rethink of the turbofan architecture as a whole and not only menial advances in materials, cooling and blade design.

As I said, when I look at turbofans today, I see dinosaurs. I see waste, waste and more waste.
Too many baby steps and the state of the art is laughable, you should see some of these recent patents. People are getting paid to come up with that?

About the delay. I don't see the B777X EISing before 2022.
First flight in 2020 and EIS in 2022 is most plausible.
If QF choose it for project Sunrise, they won't get deliveries until it's almost time for the A350neo.


Um. I'm with lightsaber on who knows what they are talking about here. Btw https://en.m.wikipedia.org/wiki/Mach_number


Well tell me what a high Mach number compressor is.
There are no Mach numbers inside a compressor, only pressures.
So where is this high Mach measured? Before the intake? At the face of the compressor? On the rotating blades of the compressor?

A compressor is meant to compress air to higher pressures. The correlation with the high Mach number is difficult to make, especially considering that there are compressors even on aircraft engines designed for M3.0

So I would like to know more and make my mind up on whether this is BS, as I suspect that it is, or something that is new and offers benefits.
 
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 10:37 am

blackscorpion wrote:
It looks like GE are taking the GE9X is to the Paris Air Show

https://www.instagram.com/p/BylWR5xAo3b/


That's a long drive! They'd get there a lot quicker if they fired that bad boy up...
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CHRISBA35X
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 11:22 am

scbriml wrote:
blackscorpion wrote:
It looks like GE are taking the GE9X is to the Paris Air Show

https://www.instagram.com/p/BylWR5xAo3b/


That's a long drive! They'd get there a lot quicker if they fired that bad boy up...


I've seen bigger and bulkier in the overhead lockers ex-LOS and KHI ;) It'll fit just fine.
 
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 11:57 am

CHRISBA35X wrote:
I do find it funny to note on other threads where the A35K and 779X are mentioned - the same posters who have spent years telling us the A380 is a dinosaur and the VLA market is deader than Daenaerys, are now trying to espouse the notion that the 779X is going to sell in mega numbers as the VLA market isnt nearly as dead as they thought it was when the A380 was dominating it.. What is good for the goose is good for the gander, or so they say.

In this case, whilst the 380 was flawed in execution and had a few things going against it that stopped it from really pushing the VLA market on rather than being pushed off by the VLA market, i do think the 779X will end up more successful than the 380 (sadly from my point of view). More cargo, equivalent CASM, more flexibility, slightly lower purchase price, better second hand market theoretically, and its a twin.

Lets just hope the Boeing guys and girls get it right first time. Any MAX nightmares here would be the death of the programme and a seismic blow from which Boeing would take years to recover from. Fingers crossed.

I don't think anyone is seriously saying "the 779X is going to sell in mega numbers" regardless of their opinion of the A380.

The 777 started in the sweet spot of the market (772) and as more tech was added was so good as to create a new sweet spot (77W).

I don't think anyone can expect a repeat because (a) the 772 sweet spot is occupied by A359 and (b) 77X is not a clean sheet, presumably to lower risk and improve profitability at the cost of being able to target the exact market segment you want to target

In my case, I reacted to a poster saying the GE9X would not provide a return on investment, which to me is an absurd thing to say at this point in time.

From what we see 777X already has established itself with strong orders from blue chip customers and the portfolio will widen as the product matures.

And there are plenty of reasons 779 is not A380:
    o 20% fewer passengers than A380 so easier to fill without trashing yields
    o Two less engines than A380
    o Doesn't require its own new class of airport gate nor impose new absolute weight requirements
    o Has next gen engines instead of repackaged current gen engines like T900 and GP7200 were

To expand the last point, if you read John Leahy's post retirement interviews (where's the book, John?) you'll find he complained that the A380 got sandbagged by the engine vendors who told them they had no new tech ready to go in the near future, but of course it was only a few years later that the GE90-115B came out and changed the game. I think it was just bad timing. At the time A380 was being mooted GE had its hands full with the first pass GE90 and presumably hadn't made the decision to do the kind of investment needed to do the second pass.
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 12:01 pm

Revelation wrote:
And there are plenty of reasons 779 is not A380:
    o 20% fewer passengers than A380 so easier to fill without trashing yields

787-9 has fewer passengers than 779 so easier to fill without trashing yields
A321 787-9 has fewer passengers than 787-9 so easier to fill without trashing yields
....
.....
B1900 has fewer passengers than CRJ200 so easier to fill without trashing yields - and thus becomes the ultimate yield plane.
 
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 12:33 pm

kalvado wrote:
Revelation wrote:
And there are plenty of reasons 779 is not A380:
    o 20% fewer passengers than A380 so easier to fill without trashing yields

787-9 has fewer passengers than 779 so easier to fill without trashing yields
A321 787-9 has fewer passengers than 787-9 so easier to fill without trashing yields
....
.....
B1900 has fewer passengers than CRJ200 so easier to fill without trashing yields - and thus becomes the ultimate yield plane.

Thank you for a great example of a false reduction to absurdity argument.

As per H. L. Mencken via OldAeroGuy on our MAX grounding thread: For every complex problem there is an answer that is clear, simple, and wrong.

Please study https://en.wikipedia.org/wiki/Yield_management and report back.
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kalvado
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 12:46 pm

Revelation wrote:
kalvado wrote:
Revelation wrote:
And there are plenty of reasons 779 is not A380:
    o 20% fewer passengers than A380 so easier to fill without trashing yields

787-9 has fewer passengers than 779 so easier to fill without trashing yields
A321 787-9 has fewer passengers than 787-9 so easier to fill without trashing yields
....
.....
B1900 has fewer passengers than CRJ200 so easier to fill without trashing yields - and thus becomes the ultimate yield plane.

Thank you for a great example of a false reduction to absurdity argument.

As per H. L. Mencken via OldAeroGuy on our MAX grounding thread: For every complex problem there is an answer that is clear, simple, and wrong.

Please study https://en.wikipedia.org/wiki/Yield_management and report back.

Problem with the initial statement is that you gave that as a plain fact, without complex context. WHich is generally a bad idea
 
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 12:53 pm

kalvado wrote:
Problem with the initial statement is that you gave that as a plain fact, without complex context. WHich is generally a bad idea

Yes, I did assume readers knew of yield management. In the old days one could make such an assumption while posting on a.net. Perhaps not so much now.
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 1:03 pm

[quote="Revelation"][/quote]
I'm inclined to agree with you there, (I think I'm agreeing with you, I might be just agreeing with JL) that the A380 was somewhat sandbagged with poor engines (although that's partly Airbus's fault for chasing noise over optimum performance in my book). If you look at the history of two of the most impressive widebodies (A330 and 777) they both arrived pushing the boundaries as to what was possible with regards to engine sizes and as such were slightly hampered out of the box with what they could achieve payload range wise, they then both had engines grow in to their size categories and flourished as long range machines. The A380 was envisaged with its monstrous range (8200nm?) from the get go and with that left no head room for the inevitable improvements that would come its way from engines. Had it been envisaged as a 6-7000nm machine would it have grown more gracefully to fill its markets with less wasted capability and cost.

The 777X appears to have not tried to push the 8000nm magic number and maintain the payload range characteristics of the 77W. I know this is not an Airbus thread but my concern for their strategy with the A350 is that it might be too capable out of the box...

As a slightly back on topic musing, what would the 77W/L have been capable of had they just fitted the GE9x to it. My basic numbers say 105k thrust would be good for 335t takeoff weight.

Fred
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 1:33 pm

CHRISBA35X wrote:
I do find it funny to note on other threads where the A35K and 779X are mentioned - the same posters who have spent years telling us the A380 is a dinosaur and the VLA market is deader than Daenaerys, are now trying to espouse the notion that the 779X is going to sell in mega numbers...


I haven't seen these threads. Can you provide some links?
 
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 1:45 pm

keesje wrote:
tomcat wrote:
BoeingVista wrote:

OK, well this is a great OT argument Lightsaber, but back to the actual problem with the GE9X, what is it and how long do you think it will take to resolve?..


This thread is a non-sense. What the article posted in the opening post says is that
While Boeing and GE expect to have a fix ready soon, the first flight is likely to slip into July, if not later.


The GE9X problem is about to be solved, it will only take a few more weeks than expected, not 6 months.


I think there are signs (Muilenburg, Zeke, Avweek) from multiple angles. If you need wait for Boeing to state officially (kicking, screaming, deflecting, generalizing), you are always at least 2 months behind the deed.


I just fail to see how a few weeks or even a 2 months delay can be reported in the thread title as "delayed to year end". The tread opener simply misread the article and people are jumping to try to explain something that hasn't even been mentioned in the article. The thread title should at least be updated to "777X first flight likely to slip to July" or something along these lines.

What is being delayed to year end -2020 year end - is obviously the first delivery but there is no speculation here. It's just the result that the flight test campaign hasn't started yet.
Last edited by tomcat on Wed Jun 12, 2019 1:59 pm, edited 1 time in total.
 
mjoelnir
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 1:51 pm

I thought this thread was about the 777-9 test frame first flight was being delayed? I would the A380 and sales possibilities of the 777-9 belong somewhere els, as far as things are not influenced by the delay of the 777-9.
 
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 2:15 pm

tomcat wrote:
keesje wrote:
tomcat wrote:

This thread is a non-sense. What the article posted in the opening post says is that

The GE9X problem is about to be solved, it will only take a few more weeks than expected, not 6 months.


I think there are signs (Muilenburg, Zeke, Avweek) from multiple angles. If you need wait for Boeing to state officially (kicking, screaming, deflecting, generalizing), you are always at least 2 months behind the deed.


I just fail to see how a few weeks or even a 2 months delay can be reported in the thread title as "delayed to year end". The tread opener simply misread the article and people are jumping to try to explain something that hasn't even been mentioned in the article. The thread title should at least be updated to "777X first flight likely to slip to July" or something along these lines.

What is being delayed to year end -2020 year end - is obviously the first delivery but there is no speculation here. It's just the result that the flight test campaign hasn't started yet.


I would look at a delay to the end of the year as still optimistic. If something mechanical in the area of the high pressure compressor has to be changed, the engines disassembled and with new parts again assembled, I assume followed by test runs. A 6 month delay should be called short.
 
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 2:23 pm

mjoelnir wrote:
tomcat wrote:
keesje wrote:

I think there are signs (Muilenburg, Zeke, Avweek) from multiple angles. If you need wait for Boeing to state officially (kicking, screaming, deflecting, generalizing), you are always at least 2 months behind the deed.


I just fail to see how a few weeks or even a 2 months delay can be reported in the thread title as "delayed to year end". The tread opener simply misread the article and people are jumping to try to explain something that hasn't even been mentioned in the article. The thread title should at least be updated to "777X first flight likely to slip to July" or something along these lines.

What is being delayed to year end -2020 year end - is obviously the first delivery but there is no speculation here. It's just the result that the flight test campaign hasn't started yet.


I would look at a delay to the end of the year as still optimistic. If something mechanical in the area of the high pressure compressor has to be changed, the engines disassembled and with new parts again assembled, I assume followed by test runs. A 6 month delay should be called short.


I may have missed something, but nobody is talking or even speculating about a first flight delay to the end of this year. The most recent article on this subject suggests a slip of the first flight from end of June to July or maybe later (I understand that it's still a matter of weeks though). What are the facts that make you think that such a delay to end of year is even remotely possible?
 
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 2:41 pm

scbriml wrote:
blackscorpion wrote:
It looks like GE are taking the GE9X is to the Paris Air Show

https://www.instagram.com/p/BylWR5xAo3b/


That's a long drive! They'd get there a lot quicker if they fired that bad boy up...

I'm Just imagining a flying engine with nothing attached to it just soaring above paris
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Re: Rumour: 777X First Flight Likely Delayed Due GE9X Issues

Wed Jun 12, 2019 2:43 pm

If I'm Boeing, I'd under-promise and over-deliver at this point, pushing an end-of-year expectation while getting into the air a whole lot sooner. And also, GE can't be happy at Boeing 'pointing the finger' at them. Stock valuations plummet on less...
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 2:45 pm

musman9853 wrote:
scbriml wrote:
blackscorpion wrote:
It looks like GE are taking the GE9X is to the Paris Air Show

https://www.instagram.com/p/BylWR5xAo3b/


That's a long drive! They'd get there a lot quicker if they fired that bad boy up...

I'm Just imagining a flying engine with nothing attached to it just soaring above paris


Even a piano can fly if its sufficiantly powered :mrgreen: !
This is your pilot speaking. Welcome to flight one from here to there. We'll be flying at a height of ten feet, going up to twelve and a half feet if we see anything big. My copilot today is a flask of coffee.

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Re: Rumour: 777X First Flight Likely Delayed Due GE9X Issues

Wed Jun 12, 2019 2:49 pm

Faro wrote:
https://www.fool.com/investing/2019/06/08/the-revolutionary-boeing-777x-jet-is-running-behin.aspx


Apparently issues with the GE9X stator actuation mechanism which was the object of a re-design recently. First flight slated before the year end instead of end of June, with EIS for late 2020 or possibly 2021.

Anyone have any details?


Faro

Boeing went thru massive delays with its initial build of 787. Would have thought that a manufacture of its standing would have sorted itself and its vendors out by now.
 
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 2:51 pm

tomcat wrote:
mjoelnir wrote:
tomcat wrote:

I just fail to see how a few weeks or even a 2 months delay can be reported in the thread title as "delayed to year end". The tread opener simply misread the article and people are jumping to try to explain something that hasn't even been mentioned in the article. The thread title should at least be updated to "777X first flight likely to slip to July" or something along these lines.

What is being delayed to year end -2020 year end - is obviously the first delivery but there is no speculation here. It's just the result that the flight test campaign hasn't started yet.


I would look at a delay to the end of the year as still optimistic. If something mechanical in the area of the high pressure compressor has to be changed, the engines disassembled and with new parts again assembled, I assume followed by test runs. A 6 month delay should be called short.


I may have missed something, but nobody is talking or even speculating about a first flight delay to the end of this year. The most recent article on this subject suggests a slip of the first flight from end of June to July or maybe later (I understand that it's still a matter of weeks though). What are the facts that make you think that such a delay to end of year is even remotely possible?


Anything is possible. As a result, people will fill in the blanks with their hopes and dreams.
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MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
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Re: Rumour: 777X First Flight Likely Delayed Due GE9X Issues

Wed Jun 12, 2019 2:51 pm

AEROFAN wrote:
Faro wrote:
https://www.fool.com/investing/2019/06/08/the-revolutionary-boeing-777x-jet-is-running-behin.aspx


Apparently issues with the GE9X stator actuation mechanism which was the object of a re-design recently. First flight slated before the year end instead of end of June, with EIS for late 2020 or possibly 2021.

Anyone have any details?


Faro

Boeing went thru massive delays with its initial build of 787. Would have thought that a manufacture of its standing would have sorted itself and its vendors out by now.


Wait, what?
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
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Re: Rumour: 777X First Flight Likely Delayed Due GE9X Issues

Wed Jun 12, 2019 3:25 pm

Wonder if it would be possible to do some flight testing with GE90s installed ?
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Re: Rumour: 777X First Flight Likely Delayed Due GE9X Issues

Wed Jun 12, 2019 3:44 pm

AEROFAN wrote:
Faro wrote:
https://www.fool.com/investing/2019/06/08/the-revolutionary-boeing-777x-jet-is-running-behin.aspx


Apparently issues with the GE9X stator actuation mechanism which was the object of a re-design recently. First flight slated before the year end instead of end of June, with EIS for late 2020 or possibly 2021.

Anyone have any details?

Faro

Boeing went thru massive delays with its initial build of 787. Would have thought that a manufacture of its standing would have sorted itself and its vendors out by now.

If you want to make an omelette, you're going to have to break some eggs...

If they wanted "safe" they could have just kept selling cheap 77Ws.
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VV
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 6:34 pm

uta999 wrote:
How can the CASM be on par with an A380, which has four relatively old (15 years) engines, vs two relatively modern dryers on the 777-9X. If it turns out to be similar then that is quite bad surely.


Does it matter? A380 production will stop in 2021.
 
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 6:58 pm

Waterbomber2 wrote:
Jouhou wrote:
Waterbomber2 wrote:

I would like to reply to this.
1. CMC is like pushing the envelope of what has already been done for decades.
Materials science and more materials science. Works well in labo's, in real life operations RR, GE and PW are struggling with this, call it the bleeding edge.
On the Leap, a CMC shroud coating was compromised way ahead of expected.

2. What is a high Mach compressor? You mean like high tip speed on the blades or high compressor face speed?

3. and 4. seems to be about HPT cooling. Not much to see that is worthy of a generation bump.

5. LPT shows nothing worthy of a generation bump compared to the the GEnx generation.

6. Fan blade tip Mach number, what is so special on the GE9X compared to the GE90? The PW GTF fan blades show a lot of aerodynamic improvements that are slightly ahead of the GE90, the GE9X is merely catching up. Nothing worthy of a generation bump versus the Trent XWB.

7. All recent aircraft engines have increased combustor efficiency, through materials and lean combustion processes, etc...

8. Many points that are not verifyable.


I've read through hundreds of GE/PW/RR patents and I think that the technology is still at the dinosaur stage.
In recent times PW is obsessed with reverse combustion GTF's, I call this the reverse combustion WTF's.

I think that the engine manufacturers still can improve the engines a looooooot and I'm making work personally to this end as well.
The GE9X claims a 10% gain over the GE90 and 5% over other widebody engines in operation, but it's very questionnable and not verifyable. What stage of flight are we talking about?

Hardly a generation ahead, hardly ahead at all.
Hardly worthy of the big and expensive redesign that Boeing is doing for the B777 and will be superseeded within 5 years by whatever goes on the A350neo.

I think that a generation bump will happen in the 2020's resulting in 30% lower fuel burn compared to the GE9X/TXWB and then we can talk about a generational advance.
It will involve a major rethink of the turbofan architecture as a whole and not only menial advances in materials, cooling and blade design.

As I said, when I look at turbofans today, I see dinosaurs. I see waste, waste and more waste.
Too many baby steps and the state of the art is laughable, you should see some of these recent patents. People are getting paid to come up with that?

About the delay. I don't see the B777X EISing before 2022.
First flight in 2020 and EIS in 2022 is most plausible.
If QF choose it for project Sunrise, they won't get deliveries until it's almost time for the A350neo.


Um. I'm with lightsaber on who knows what they are talking about here. Btw https://en.m.wikipedia.org/wiki/Mach_number


Well tell me what a high Mach number compressor is.
There are no Mach numbers inside a compressor, only pressures.
So where is this high Mach measured? Before the intake? At the face of the compressor? On the rotating blades of the compressor?

A compressor is meant to compress air to higher pressures. The correlation with the high Mach number is difficult to make, especially considering that there are compressors even on aircraft engines designed for M3.0

So I would like to know more and make my mind up on whether this is BS, as I suspect that it is, or something that is new and offers benefits.


https://en.m.wikipedia.org/wiki/Axial_c ... escription
Then scroll down to
https://en.m.wikipedia.org/wiki/Axial_c ... _and_fluid

The relative motion of the blades to the fluid adds velocity or pressure or both to the fluid as it passes through the rotor. The fluid velocity is increased through the rotor, and the stator converts kinetic energy to pressure energy.


AKA
Fluid Velocity [mach] ---> Pressure
 
Lebroncin
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 8:19 pm

WholaLottaLove wrote:
lightsaber wrote:
5. Low turbine tech. See LEAP-1B and take it a generation forward. Traditionally, I have been a fan of Pratt being the leader here, but GE stole the right Pratt people. See the incredible efficiency bump of the PW1100G with the low turbine enhancement.


First of all, thank you for your post Lightsaber, enlightening as always! Quick question on the highlighted part: Isn't MTU Aero Engines building the LPT and not P&W? Did GE hire MTU's engineers?


I was wondering the same! Its my understanding as well. Lightsaber, could you confirm this, please?
Wasnt aware MTU had such good turbine tech.
 
Checklist787
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Re: Rumour: 777X First Flight Likely Delayed to Year End Due GE9X Issues

Wed Jun 12, 2019 9:32 pm

scbriml wrote:
blackscorpion wrote:
It looks like GE are taking the GE9X is to the Paris Air Show

https://www.instagram.com/p/BylWR5xAo3b/


That's a long drive! They'd get there a lot quicker if they fired that bad boy up...


.. Like the old Trent 1000 :roll:
 
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Stitch
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Re: Rumour: 777X First Flight Likely Delayed Due GE9X Issues

Wed Jun 12, 2019 11:51 pm

Flight Global is reporting that GE still anticipates completing GE9X certification testing this year and has completed some 80% of required testing.

https://www.flightglobal.com/news/artic ... gh-458847/
 
snasteve
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Thu Jun 13, 2019 1:08 am

planecane wrote:
There is an awful lot of speculation in that article by the author. Things like:

Boeing CEO Dennis Muilenburg recently stated that he still expects the 777X to enter service in 2020. However, even if that does happen, it will probably be much closer to year-end than initially planned


The second sentence is just unsubstantiated speculation by the author. If this turns out to be true and there is a significant delay, there will be many more sources than a single Motley Fool article written by an author who does not specialize in aviation.

As of now, I'd take it with a grain of salt.


I can do better, I predict there will be a delay of some sort, now I have absolutely no idea what I’m talking about and I’m not an industry insider.

I do know that there are a lot of delays with the new technology, and I would expect this to more or less continue. I don’t think airlines should be too surprised when it happens. What Motley fool is doing amounts to predicting that rain will be wet. IMO of course.
 
DfwRevolution
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Thu Jun 13, 2019 1:20 am

Waterbomber2 wrote:
Well tell me what a high Mach number compressor is.
There are no Mach numbers inside a compressor, only pressures.
So where is this high Mach measured? Before the intake? At the face of the compressor? On the rotating blades of the compressor?

A compressor is meant to compress air to higher pressures. The correlation with the high Mach number is difficult to make, especially considering that there are compressors even on aircraft engines designed for M3.0

So I would like to know more and make my mind up on whether this is BS, as I suspect that it is, or something that is new and offers benefits.


1.) A high-mach compressor is exactly what it sounds like. The tip speed of the compressor blades are traveling at or near the sonic velocity of the airflow. Mach number is an important parameter to the design engineer because it dictates the flow behavior of a gas. From my industrial experience, I would consider tip speeds of Mach 0.9 to 1.5 as a "high Mach" compressor. Maybe the thresholds are different for aviation, but I doubt it. So there are absolutely "Mach numbers inside a compressor."

2.) The benefit of a high-mach compressor is due to the high blade tip speeds. The volume flow and head through a dynamic compressor - including axial compressors - are proportional to the speed of the compressor blade. A faster compressor means a smaller, lighter compressor for the same work. That has obvious benefits for aircraft engines.

3.) There are no turbine aircraft engines that operate with velocities of Mach 3.0. Supersonic aircraft - including the SR-71 - use diffusers to slow incoming air to subsonic velocity before the engine inlet.
I have a three post per topic limit. You're welcome to have the last word.
 
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Re: 777X First Flight Delayed to Year End Due GE9X Issues

Thu Jun 13, 2019 2:06 am

DfwRevolution wrote:
Waterbomber2 wrote:
Well tell me what a high Mach number compressor is.
There are no Mach numbers inside a compressor, only pressures.
So where is this high Mach measured? Before the intake? At the face of the compressor? On the rotating blades of the compressor?

A compressor is meant to compress air to higher pressures. The correlation with the high Mach number is difficult to make, especially considering that there are compressors even on aircraft engines designed for M3.0

So I would like to know more and make my mind up on whether this is BS, as I suspect that it is, or something that is new and offers benefits.


1.) A high-mach compressor is exactly what it sounds like. The tip speed of the compressor blades are traveling at or near the sonic velocity of the airflow. Mach number is an important parameter to the design engineer because it dictates the flow behavior of a gas. From my industrial experience, I would consider tip speeds of Mach 0.9 to 1.5 as a "high Mach" compressor. Maybe the thresholds are different for aviation, but I doubt it. So there are absolutely "Mach numbers inside a compressor."

2.) The benefit of a high-mach compressor is due to the high blade tip speeds. The volume flow and head through a dynamic compressor - including axial compressors - are proportional to the speed of the compressor blade. A faster compressor means a smaller, lighter compressor for the same work. That has obvious benefits for aircraft engines.

3.) There are no turbine aircraft engines that operate with velocities of Mach 3.0. Supersonic aircraft - including the SR-71 - use diffusers to slow incoming air to subsonic velocity before the engine inlet.


Thank you but I'm not satisfied with your explanation.
All compressor blades on all engines have High Mach numbers at the rotor blade tips by design, and this is on the first stage of the compressor, as compressor rotor stage diameters decrease going aft, by design.
If we're talking low pressure compressor including the fan, there are even cases where the tip speed is supersonic.
So there is nothing novel about a compressor rotor with transonic blade tip speeds.

I certainly wouldn't call a compressor having one or two rotor stages with high blade tip speed, with a general term like "high Mach compressor", especially considering that there are hundreds of other parameters in a compressor that could affect its efficiency. This relates to one little part of a compressor.

A compressor with a faster rotor blade tip speed may not be more efficient considering drag effects.
Volume flow and pressure ratio can be affected by so many parameters, from number of stages to tip clearance, that talking about tip speed on one of the rotor stages alone is quite irrelevant.

About your point 3.
The diffusers are part of the inlet, and they slow down the air flow before the compressor face, not "before the inlet" as you describe.
Also, there are plenty of aircraft that operate at M3.0, which is what I said, even though there are no rotating compressors that operate with supersonic flows.
By the way, there are and have been non-rotating compressors designs where the flow is supersonic, they are called ramjets.
Be specific if you want to explain something.

I'm sick of this pseudo-science to explain supposed efficiency advantages.
At the end of the day, the generational advance seems to be in the level of the B.S. that we are being shoved in the face.

Jouhou wrote:
Waterbomber2 wrote:
Jouhou wrote:

Um. I'm with lightsaber on who knows what they are talking about here. Btw https://en.m.wikipedia.org/wiki/Mach_number


Well tell me what a high Mach number compressor is.
There are no Mach numbers inside a compressor, only pressures.
So where is this high Mach measured? Before the intake? At the face of the compressor? On the rotating blades of the compressor?

A compressor is meant to compress air to higher pressures. The correlation with the high Mach number is difficult to make, especially considering that there are compressors even on aircraft engines designed for M3.0

So I would like to know more and make my mind up on whether this is BS, as I suspect that it is, or something that is new and offers benefits.


https://en.m.wikipedia.org/wiki/Axial_c ... escription
Then scroll down to
https://en.m.wikipedia.org/wiki/Axial_c ... _and_fluid

The relative motion of the blades to the fluid adds velocity or pressure or both to the fluid as it passes through the rotor. The fluid velocity is increased through the rotor, and the stator converts kinetic energy to pressure energy.


AKA
Fluid Velocity [mach] ---> Pressure


Sorry but in a compressor, fluid velocity as accelerated by the rotor stages is nowhere near transonic Mach speeds. At the base of the rotor, your blades are cutting the air at a much lower relative speed than at the tips.
A longer blade will have a lower average fluid velocity because the tip speed will be the limiting factor.
Also, even though the blades may be travelling at high transonic Mach speeds at the tips, the fluid is unlikely to be accelerated to that speed due to relative angle between the blades travelling in the direction of circumference of the engines and the fluid acceleration being intended to accelerate air backwards.
So you don't know what you're talking about.
If you're going to explain something, get your facts right.


Since there has been no satisfactory explanation, only pseudo-sience, I'm inclined to call B.S. on this one.
Last edited by Waterbomber2 on Thu Jun 13, 2019 2:25 am, edited 1 time in total.
 
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BoeingVista
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Re: Rumour: 777X First Flight Likely Delayed Due GE9X Issues

Thu Jun 13, 2019 2:18 am

Stitch wrote:
Flight Global is reporting that GE still anticipates completing GE9X certification testing this year and has completed some 80% of required testing.

https://www.flightglobal.com/news/artic ... gh-458847/


When I read that article I get PW GTF denial flashbacks (saw problem, fixed problem, retested, saw same problem, re-engineered part to incorporate in flight test engine, we anticipate that this will fix the problem) all is clearly not well within this engine program.

Some highlights

GE Aviation completed a second round of certification flight testing for the 777X's engine in May, during which it completed 53 test flights and logged more than 300 flight hours.

The engine maker had told FlightGlobal late last year that it anticipated "making about 18 flights or so" during the second round of testing.


GE felt the need to endurance test the engine on wing, maybe issue does not show up in ground tests which would be concerning.

The company says additional flight tests in the second phase reflect changes to the massive, 105,000lb-thrust (467kN) GE9X's "variable stator vane lever arm".

The arms set the pitch of stator vanes, which are inside the compressor and slow airflow, increasing its pressure. GE Aviation redesigned the arm prior to the second phase of test flights after determining the initial design wore out faster than expected


Sounds like a 'mechanical' issue, also critical to correct operation of the engine.

"Since the engine for phase two had the new variable stator vane lever arm in the high-pressure compressor, we wanted to get the engine performance data on this configuration at altitude," GE Aviation says.


Confirms that issue needed extensive high altitude retesting.

The company is making other changes to improve the GE9X's durability.

"During a recent test, GE detected an anomaly in the engine data from the high-pressure compressor," GE Aviation says. "After data analysis and additional testing, our engineers saw an opportunity for a durability improvement in the front of the compressor."

"GE anticipates completing its certification testing this year," it adds.

The company does not provide specifics, but says the anomaly is "mechanical in nature — and is not related to the design or performance of the high-pressure compressor".


Annnnd shes back again, 'mechanical' issue returns; re-engineer and retest required.

What is a variable stator vane lever arm? From GE's patent below its no. 80. Seem to be lots of them (obviously) so any reliability issue would be magnified.

Image

There is no way with who knew what when questions still swirling around the MAX that Boeing can afford to have a test 777x grounded by an IFSD from an issue previously identified on the ground (safety is our number one priority and all that), she won't fly until GE has nailed this down. I'd say 6 months and another round of flying testbed flying.
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smartplane
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Re: Rumour: 777X First Flight Likely Delayed Due GE9X Issues

Thu Jun 13, 2019 3:13 am

BoeingVista wrote:
Stitch wrote:
Flight Global is reporting that GE still anticipates completing GE9X certification testing this year and has completed some 80% of required testing.

https://www.flightglobal.com/news/artic ... gh-458847/


When I read that article I get PW GTF denial flashbacks (saw problem, fixed problem, retested, saw same problem, re-engineered part to incorporate in flight test engine, we anticipate that this will fix the problem) all is clearly not well within this engine program.

The advised engine issue/s will trigger a partial / full reset of testing, so may have completed 80% of testing, pre-announcement, but post may now be 60% or less.

All OEM's are being super careful to keep certifying authorities in the loop, so no surprises.

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