https://preview.theaircurrent.com/

This is Jon Ostrower's new gig.

So it’s ultrafan vs LEAP/9x. I’m shocked rolls has the resources available short term to do this.

There is another thread which reports that GE and Safran were negotiating to increase the max thrust for CFM engines to 50000 lbs. So I vote for LEAP as opposed to 9x.

OTOH, what is Pratt going to do?

texl1649 wrote:

So it’s ultrafan vs LEAP/9x. I’m shocked rolls has the resources available short term to do this.

I suspect that B is concerned about this very thing.

"OTOH, what is Pratt going to do?"

After the recent SNAFUs by Pratt will an OEM trust them to provide launch engines in the near future?

This is an interesting note in Jon's article...

"Historically, picking a power plant has closely preceded the formal launch of the aircraft. Boeing made its pick of General Electric and Rolls-Royce engines for the 787 (then-7E7) just 20 days before All Nippon Airways placed the jet’s 2004 kickoff order."

Yes, picking an engine means the offer order to cert to delivery contractual dates are basically...done.

It also means the loser(s) among the three engine makers becomes incentivized, from a market perspective, to “discuss” with Airbus, their in house technically quite advanced stage design/plans/options. After the Boeing board meeting last week, I think the ball is rolling pretty quickly, finally.

jagraham wrote:

There is another thread which reports that GE and Safran were negotiating to increase the max thrust for CFM engines to 50000 lbs. So I vote for LEAP as opposed to 9x.

OTOH, what is Pratt going to do?

The basic LEAP core can’t do that though. His article references tech from both families, and while GE (and Boeing) would have an interest to brand them as one family, I’m guessing actual parts commonality would approach zero. Mechanic training for GE 797 engine and LEAP might be quite similar tho.

mffoda wrote:

This is an interesting note in Jon's article...

"Historically, picking a power plant has closely preceded the formal launch of the aircraft. Boeing made its pick of General Electric and Rolls-Royce engines for the 787 (then-7E7) just 20 days before All Nippon Airways placed the jet’s 2004 kickoff order."

The question then becomes, when will they pick the powerplant?

Looks like the 797 is coming soon. Very soon. Maybe even within a month, if it follows the 787 timeline. Exciting!

Sadly, I think Boeing will decide which is less worse: RR or Pratt.

CFM has issues with the LEAP turbine, but that is interval on wing, not fuel burn nor dispatch reliability. It is easily monitored and the factories have already geared up to provide replacement parts.

CFM is pretty much certain (or at least GE) to be selected.

It is a question of who is the 2nd option and what hurdles they must leap to be selected.

PlanesNTrains wrote:

mffoda wrote:

This is an interesting note in Jon's article...

"Historically, picking a power plant has closely preceded the formal launch of the aircraft. Boeing made its pick of General Electric and Rolls-Royce engines for the 787 (then-7E7) just 20 days before All Nippon Airways placed the jet’s 2004 kickoff order."

The question then becomes, when will they pick the powerplant?

This is the most exciting time to engineer an engine. Many changes and improvements. Management decides if they want to risk new technology or not. It take a few months to optimize the concept for launch (including planned thrust growth margin).

By iterating aircraft/engine optimization, the overall airframe cuts fuel burn a few percent. The pylon will be optimized.

Now, far more goes on after engine selection, but first the opportunity has to be seen.

Lightsaber

Imagine a carrier having 787 and 797 in their fleet, based on what is taking place now, the risk is high.
Th engine OEM's have a couple years to restore confidence, the issues with engines on the 787 today are reliability not new tech, the engines have been around for a few years.

JayinKitsap wrote:

texl1649 wrote:

So it’s ultrafan vs LEAP/9x. I’m shocked rolls has the resources available short term to do this.

I suspect that B is concerned about this very thing.

In theory, they have Advance technology integrated in a testbed engine (see thread in TechOps) and by the time the big spend needs to happen for UltraFan RR should be taking in lots of cash from A350 TXWB sales. Unfortunately they have taken a big hit financially and reputationally with the T1000 issues.

texl1649 wrote:

The basic LEAP core can’t do that though. His article references tech from both families, and while GE (and Boeing) would have an interest to brand them as one family, I’m guessing actual parts commonality would approach zero. Mechanic training for GE 797 engine and LEAP might be quite similar tho.

We have some pretty clear guidance from just three months ago:

(CEO of GE Aviation David) Joyce said CFM will probably be the engine provider rather than GE, if Boeing selects the family.

“I see no reason at all why we wouldn’t make LEAP the baseline,” he said. “It will be bigger, but it will be something advancing not a full generation, but a half generation in technology from what LEAP is today.”

It will be “kind of” a clean-sheet engine, Joyce said. “We’ll be able to put as much technology as we feel is mature enough, advanced technology, brand new stuff.”

Ref: https://leehamnews.com/2018/03/22/ge-cf ... ng-on-nma/

“It will be bigger,” Joyce told a JP Morgan investment conference on 14 March. “It’s advancing [on the Leap technology] not a full generation but a half-generation.”
...
“The probability is very, very high this will be a CFM engine,” Joyce says.

So in essence it's going to be a bigger CFM LEAP with a "half generation" leap (tm) in technology.

lightsaber wrote:

Sadly, I think Boeing will decide which is less worse: RR or Pratt.

CFM has issues with the LEAP turbine, but that is interval on wing, not fuel burn nor dispatch reliability. It is easily monitored and the factories have already geared up to provide replacement parts.

CFM is pretty much certain (or at least GE) to be selected.

It is a question of who is the 2nd option and what hurdles they must leap to be selected.

PlanesNTrains wrote:

mffoda wrote:

This is an interesting note in Jon's article...

"Historically, picking a power plant has closely preceded the formal launch of the aircraft. Boeing made its pick of General Electric and Rolls-Royce engines for the 787 (then-7E7) just 20 days before All Nippon Airways placed the jet’s 2004 kickoff order."

The question then becomes, when will they pick the powerplant?

This is the most exciting time to engineer an engine. Many changes and improvements. Management decides if they want to risk new technology or not. It take a few months to optimize the concept for launch (including planned thrust growth margin).

By iterating aircraft/engine optimization, the overall airframe cuts fuel burn a few percent. The pylon will be optimized.

Now, far more goes on after engine selection, but first the opportunity has to be seen.

Lightsaber

I think this makes the most sense. CFM goes on first and I would guess is the launch engine. If you want a Pratt or RR you wait some additional time. It fits with the aggressive launch schedule for the airplane as well. CFM may be comfortable with a 2025 EIS and the others may need longer.

Didn't GE say that they were calling it quits if they didn't get exclusivity?

Continental767 wrote:

Looks like the 797 is coming soon. Very soon. Maybe even within a month, if it follows the 787 timeline. Exciting!

You don't pick winner(s) of an RFP the day they are due..

Oh, I realize, Revelation, that GE/SNECMA are expanding their contractual relationship with this new family, To 50or 55k, I should clarify my suspicion is it is, in fact, a new family. Sure, lots of LEAP stuff, but in reality a new core engine, with GE9x tech, and, curiously, not a GTF. so, same stage numbers and architecture as LEAP basically.

GE basically said they weren’t doing another three engine sources all new design/family, and I’m sure they offered to spend/contribute more if sole sourced.

What rational major carrier would want an all new ultrafan design in about 2026 at this point? I don’t think even BA or DL, let alone Korean or others would throw a big commitment that way.

scouseflyer wrote:

"OTOH, what is Pratt going to do?"

After the recent SNAFUs by Pratt will an OEM trust them to provide launch engines in the near future?

RR and Pratt are about on par in the SNAFU department.

GoSharks wrote:

Continental767 wrote:

Looks like the 797 is coming soon. Very soon. Maybe even within a month, if it follows the 787 timeline. Exciting!

You don't pick winner(s) of an RFP the day they are due..

Yeah but Boeing has a ton of familiarity with the basic offerings they are going to see. The manufacturers will make their guarantees on performance, finances and specs which will be easily comparable in a matter of a few hours.

The only hard part is evaluating the technical risk with each proposal. But the basic architecture of each proposal is fairly well known. GE/CFM will offer a high temp exotic material but fairly conventional engine. Pratt will offer some GTF. RR is the only wildcard. Do they offer the full ultra fan or just the advanced?

You have likely already talked to airlines about their preferences. My take is that more airlines are loyal to RR than Pratt. I expect the RR to have more technical risk with their first geared fan and a new core but to win out on political merits over Pratt. I think CFM/GE is a sure thing.

bigjku wrote:

GoSharks wrote:

Continental767 wrote:

Looks like the 797 is coming soon. Very soon. Maybe even within a month, if it follows the 787 timeline. Exciting!

You don't pick winner(s) of an RFP the day they are due..

Yeah but Boeing has a ton of familiarity with the basic offerings they are going to see. The manufacturers will make their guarantees on performance, finances and specs which will be easily comparable in a matter of a few hours.

The only hard part is evaluating the technical risk with each proposal. But the basic architecture of each proposal is fairly well known. GE/CFM will offer a high temp exotic material but fairly conventional engine. Pratt will offer some GTF. RR is the only wildcard. Do they offer the full ultra fan or just the advanced?

You have likely already talked to airlines about their preferences. My take is that more airlines are loyal to RR than Pratt. I expect the RR to have more technical risk with their first geared fan and a new core but to win out on political merits over Pratt. I think CFM/GE is a sure thing.

I'd agree but I think Pratt has to go "all in" as this would probably be their last opportunity to move up the size ladder. That they know they can't screw it up anything beyond something very minor is a given. Also, Pratt would probably be more aggressive on price, something they can do with their corporate backing that Rolls might not be able to match with all the money they are spending fixing current issues. As with most, I concur that something involving CFM/GE is almost a given.
I've got nothing against any manufacturer but as a Pratt fan I'd love to see a strong comeback.

texl1649 wrote:

jagraham wrote:

There is another thread which reports that GE and Safran were negotiating to increase the max thrust for CFM engines to 50000 lbs. So I vote for LEAP as opposed to 9x.

OTOH, what is Pratt going to do?

The basic LEAP core can’t do that though. His article references tech from both families, and while GE (and Boeing) would have an interest to brand them as one family, I’m guessing actual parts commonality would approach zero. Mechanic training for GE 797 engine and LEAP might be quite similar tho.

The last few GE engines have pretty much been done by taking their best current core design and scaling it to the appropriate size and then adding a bit of new technology. This scaling of cores is now done in the virtual world speeding up development. The more new technology that is added the greater the risk. GE can easily strike a balance between risk and fuel burn targets to create an engine by the required operational date.

GE has this in the bag.

The GE9X fan is newer tech and a bit lighter at any given size. So you could effectively have a larger diameter fan providing more thrust with the same shaft horsepower. The LEAP core might only need to provide 10% more shaft power to create an engine with 30% more thrust. Bypass ratio could be as high as 13:1 setting a new record.

Supercharging a core with an additional front stage is pretty common practice. It increases overall frontal area giving higher flow and pressure ratio through the core. Increased heat is the obvious side effect but the LEAP core is reaching maturity. They might add some GE9x techology in the turbine section to handle the heat. This could easily add 25% more shaft power from the core creating an engine with 50% more thrust than the current LEAP.

The end result is an engine that probably shares few parts with the LEAP or GE9x but shares the mature technology of both.

Scaling the Pratt GTF is high risk. It needs a new larger core, Pratt has little experience scaling cores. It needs a new higher ratio gearbox.

Rolls royce advance is based off the 3 shaft trent design and is simply too large for the 797. Scaling it down would be inefficient. Derating the trentTen core and adding a smaller fan can not beat GE. Rolls would need a brand new core. The Rolls royce ultrafan is a cleansheet and very high risk option to meet the in service date. Boeing knows they arw struggling at the moment, even amateur enthusiasts can see Rolls is in trouble.

I think a derivative of the LEAP engine is the most-likely at launch, with a possible P&W GTF or RR UF option down the road. GTF and UF would probably be desirable on NSA so whomever wins the second engine option on NMA would help de-risk the NSA program.

texl1649 wrote:

What rational major carrier would want an all new ultrafan design in about 2026 at this point? I don’t think even BA or DL, let alone Korean or others would throw a big commitment that way.

Agreed. While DL has already said that they want to be a (the?) launch customer for the NMA, an ultrafan engine concept which has not been proven and debugged in commercial service might be too much risk to take on.

Kind of interesting that DL wants to be the launch customer considering they've operated every Boeing model EXCEPT the 787.....

Launch customers may have some preferences...look at 757/767/787/Neo current and past operators...NH is 767 carrier and a potential launch customer -- went for Rolls on 787, maybe NH kicking themselves? AA chose LEAP for A320Neo and 787 GEnx, also is 767-CF6 so CFM is what they would prefer. Delta went for Pratt-GTF on NEO, and Isn't UAL a 767 Pratt aircraft? --but GE on UA 787. Qantas may be interested in 797, what would they prefer?

So agreed that CFM is almost a shoe-in. I don't know if there is really room for another 797/NMA engine maker. It's very expensive to certify two engines and the engine OEM's may not want a competition, instead may demand an exclusive. Didn't hurt the A350 and I don't know if the 797 will have a big initial customer base that would support two engines. Maybe another engine could be a 797 NEO ten years layer in 2035. My bet is CFM only for now.

texl1649 wrote:

Oh, I realize, Revelation, that GE/SNECMA are expanding their contractual relationship with this new family, To 50or 55k, I should clarify my suspicion is it is, in fact, a new family. Sure, lots of LEAP stuff, but in reality a new core engine, with GE9x tech, and, curiously, not a GTF. so, same stage numbers and architecture as LEAP basically.

Jon's blog post indicated the RFP is for a 45k engine, less than the 50k of the GE/SNECMA.

Currently Boeing has single engine supplier on the 737, 748, the 772LR, 777F, & 773W
The 767 has 3 suppliers and the 787 has 2 with GE having the pole position for both.

My best guess is GE/SNECMA in an exclusive on the first model, possibly 2 for the 2nd model. That would allow for a larger thrust and more mature technology. There is probably a couple of years between the two models.

RJMAZ wrote:

texl1649 wrote:

jagraham wrote:

There is another thread which reports that GE and Safran were negotiating to increase the max thrust for CFM engines to 50000 lbs. So I vote for LEAP as opposed to 9x.

OTOH, what is Pratt going to do?

The basic LEAP core can’t do that though. His article references tech from both families, and while GE (and Boeing) would have an interest to brand them as one family, I’m guessing actual parts commonality would approach zero. Mechanic training for GE 797 engine and LEAP might be quite similar tho.

The last few GE engines have pretty much been done by taking their best current core design and scaling it to the appropriate size and then adding a bit of new technology. This scaling of cores is now done in the virtual world speeding up development. The more new technology that is added the greater the risk. GE can easily strike a balance between risk and fuel burn targets to create an engine by the required operational date.

GE has this in the bag.

The GE9X fan is newer tech and a bit lighter at any given size. So you could effectively have a larger diameter fan providing more thrust with the same shaft horsepower. The LEAP core might only need to provide 10% more shaft power to create an engine with 30% more thrust. Bypass ratio could be as high as 13:1 setting a new record.

Supercharging a core with an additional front stage is pretty common practice. It increases overall frontal area giving higher flow and pressure ratio through the core. Increased heat is the obvious side effect but the LEAP core is reaching maturity. They might add some GE9x techology in the turbine section to handle the heat. This could easily add 25% more shaft power from the core creating an engine with 50% more thrust than the current LEAP.

The end result is an engine that probably shares few parts with the LEAP or GE9x but shares the mature technology of both.

Scaling the Pratt GTF is high risk. It needs a new larger core, Pratt has little experience scaling cores. It needs a new higher ratio gearbox.

Rolls royce advance is based off the 3 shaft trent design and is simply too large for the 797. Scaling it down would be inefficient. Derating the trentTen core and adding a smaller fan can not beat GE. Rolls would need a brand new core. The Rolls royce ultrafan is a cleansheet and very high risk option to meet the in service date. Boeing knows they arw struggling at the moment, even amateur enthusiasts can see Rolls is in trouble.

Ultrafan is a GTF https://www.rolls-royce.com/media/our-s ... arbox.aspx. It also has a variable pitch fan. The new core is already being done in the Advance3 demonstrator. So the pieces are there, and should generate class leading efficiency; but will Boeing wait??? Or trust for that matter????? Ultrafan has a LOT of new toys in one toybox.

acjbbj wrote:

Didn't GE say that they were calling it quits if they didn't get exclusivity?

Is that calling it quits with manufacturing engines or calling it quits completely because the vultures seem to circling GE at the moment. Anyway, it looks like the 797 will make its debut soon and we won’t have to guess/argue over the specifications. We’ll just have to guess/argue if it was the right decision for Boeing to make. As always, time and a DL/UA order for 100+ each will tell.

Fingers crossed for 797 By the way, I think it is the perfect time to launch the program. Airbus is not at a position to counter this program due to the recent changes at the management level. Do they need to respond to 797 is another topic. Time will tell.

imthedreamliner wrote:

Fingers crossed for 797 By the way, I think it is the perfect time to launch the program. Airbus is not at a position to counter this program due to the recent changes at the management level. Do they need to respond to 797 is another topic. Time will tell.

Airbus is in a very good position to counter & even pre emp this program. They have lots of resources, available technology and 2 existing maturing engines. If they want they do a small, light, cheap NMA, 3 years before Boeing NMA they will. And forget game changing, technological magic from either side. Airbus never has been shy, waiting for Boeing.

But wouldn't a scaled down and lighter (and reliable) Trent, or a new smaller core (compared to Trent) be technological magic, Ultrafan or not?

One can ask oneselve how long aviation will be able to avoid the consequences of the Paris agreement. Considering EIS will be somewhere between 2025-2027, playing it save with half-generation improvements might avoid technological risk but could very likely make itself very vulnerable to market/fuel use/regulatory risk.

So with a 45K engine, what sort of fuselage does that indicate? Is the thrust required a clue for that or is it mostly inconsequential?

What do we know about the 797/NMA aircraft? From the link in the OP’s post:

- A pair of new small twin-aisle aircraft
- NMA-6X, is a 228-passenger medium-ranger with a 5,000 nautical mile endurance
- NMA-7X, seating in two classes for 267, touting a range 800 nautical miles shorter

How will it be different from the 788?
What will be the abreast seating configuration?

What is an ovoid hybrid fuselage?
What are 767-200 small twin boarding doors?

keesje wrote:

imthedreamliner wrote:

Fingers crossed for 797 By the way, I think it is the perfect time to launch the program. Airbus is not at a position to counter this program due to the recent changes at the management level. Do they need to respond to 797 is another topic. Time will tell.

Airbus is in a very good position to counter & even pre emp this program. They have lots of resources, available technology and 2 existing maturing engines. If they want they do a small, light, cheap NMA, 3 years before Boeing NMA they will. And forget game changing, technological magic from either side. Airbus never has been shy, waiting for Boeing.

The sales performance of game changing, technological magic dreamliner against old technology A330neo is proving you wrong. The cheap counter of Airbus against 797 may prove to be wrong as well.

Taxi645 wrote:

One can ask oneselve how long aviation will be able to avoid the consequences of the Paris agreement. Considering EIS will be somewhere between 2025-2027, playing it save with half-generation improvements might avoid technological risk but could very likely make itself very vulnerable to market/fuel use/regulatory risk.

I'm glad someone else notices this on the site. A320 CEO is a good example of the current mindset - tweak engines, add LCD's and winglets and a 1988 variant magically becomes "state of the art" 25-30 years later. I guess I should upgrade the memory in my damn Apple IIe while I'm at it - and then tell my friends I have fast computer

1989worstyear wrote:

Taxi645 wrote:

One can ask oneselve how long aviation will be able to avoid the consequences of the Paris agreement. Considering EIS will be somewhere between 2025-2027, playing it save with half-generation improvements might avoid technological risk but could very likely make itself very vulnerable to market/fuel use/regulatory risk.

I'm glad someone else notices this on the site. A320 CEO is a good example of the current mindset - tweak engines, add LCD's and winglets and a 1988 variant magically becomes "state of the art" 25-30 years later. I guess I should upgrade the memory in my damn Apple IIe while I'm at it - and then tell my friends I have fast computer

While selling by the thousand.

scbriml wrote:

1989worstyear wrote:

Taxi645 wrote:

One can ask oneselve how long aviation will be able to avoid the consequences of the Paris agreement. Considering EIS will be somewhere between 2025-2027, playing it save with half-generation improvements might avoid technological risk but could very likely make itself very vulnerable to market/fuel use/regulatory risk.

I'm glad someone else notices this on the site. A320 CEO is a good example of the current mindset - tweak engines, add LCD's and winglets and a 1988 variant magically becomes "state of the art" 25-30 years later. I guess I should upgrade the memory in my damn Apple IIe while I'm at it - and then tell my friends I have fast computer

While selling by the thousand.

It's sad how little has changed, really

The 90s and Noughties really were the malaise period for airliners.

scouseflyer wrote:

"OTOH, what is Pratt going to do?"

After the recent SNAFUs by Pratt will an OEM trust them to provide launch engines in the near future?

Of Course!! Not Every GE engine built was ALL THAT either. I remember the CF6-6 was pretty much a "DOG" in the summer. on the DC-10-10.

QXAS wrote:

So with a 45K engine, what sort of fuselage does that indicate? Is the thrust required a clue for that or is it mostly inconsequential?

As engine technology improves aircraft can get lighter while doing the same mission. Less fuel burn means less weight and a smaller wing. The A321LR is the perfect example it can carry roughly the same payload the same distance as the 757-200 with three quarters of the thrust.

Based on this 45,000lb of thrust definitely means a 767 cabin sized aircraft. That means 7ab minimum but that is enough thrust for a short 8ab aircraft as well.

So the 797 will be a light weight, smaller winged version of the 767. Just like the A321LR is a light weight smaller version of the 757.

Cross section is still open for debate but I think it will be very similar to the 767. Most likely a foot wider to allow tight 8ab while keeping the 767's LD2 containers. Potentially a slightly reduced height cross section to use a brand new full width container.

It definitely wont use LD3 containers so that rules out the A310, A300 cross section.

Considering the incredibly tight lead times put forward for this project it really can't be anything else than Cfm can it?
Boeing would be mad to select anybody else (and they are not mad).
And if I were Cfm I would demand exclusivity too.Cant see that Boeing has any option but to agree.
The 7x (I assume it would be built second) is actually quite a large aircaft that's going to need plenty of ooomph imho.

Revelation wrote:

[

(CEO of GE Aviation David) Joyce said CFM will probably be the engine provider rather than GE, if Boeing selects the family.

“I see no reason at all why we wouldn’t make LEAP the baseline,” he said. “It will be bigger, but it will be something advancing not a full generation, but a half generation in technology from what LEAP is today.”

It will be “kind of” a clean-sheet engine, Joyce said. “We’ll be able to put as much technology as we feel is mature enough, advanced technology, brand new stuff.”

Ref: https://leehamnews.com/2018/03/22/ge-cf ... ng-on-nma/

“It will be bigger,” Joyce told a JP Morgan investment conference on 14 March. “It’s advancing [on the Leap technology] not a full generation but a half-generation.”
...
“The probability is very, very high this will be a CFM engine,” Joyce says.

So in essence it's going to be a bigger CFM LEAP with a "half generation" leap (tm) in technology.

Seems to me this is exactly what Boeing wants.

jagraham wrote:

Ultrafan is a GTF https://www.rolls-royce.com/media/our-s ... arbox.aspx. It also has a variable pitch fan. The new core is already being done in the Advance3 demonstrator. So the pieces are there, and should generate class leading efficiency; but will Boeing wait??? Or trust for that matter????? Ultrafan has a LOT of new toys in one toybox.

I hope Boeing will take this risk and select the RR Ultrafan as their second engine. I'm a big fan of something really new. I was hoping the GTF would have had a smoother EIS, still it wasn't the gearbox which caused the problems many had feared.

I would think P&W will have sorted out the GTF by the time the 797 has its EIS. But I don't think Boeing should opt for just an upscaled version of the GTF which will power the A321(X)LR. Like the Trent-XWB doesn't give the A350 a decisive advantage over the 787, the GTF won't give the 797 a decisive advantage over an updated A321 IMO. Playing safe with the GE engine option in combination with going bold with the RR Ultrafan will make the 797 a winner I think.

questions wrote:

What do we know about the 797/NMA aircraft? From the link in the OP’s post:

- A pair of new small twin-aisle aircraft
- NMA-6X, is a 228-passenger medium-ranger with a 5,000 nautical mile endurance
- NMA-7X, seating in two classes for 267, touting a range 800 nautical miles shorter

How will it be different from the 788?
What will be the abreast seating configuration?

What is an ovoid hybrid fuselage?
What are 767-200 small twin boarding doors?

Shorter ranged aircraft usually have a smaller wing compared to fuselage size. Big wings are to carry the fuel to fly long distances. The 797 might have a high number of seats on paper but it will be significantly lighter and have less wing area than the 788.

If a cleansheet design is used the seat numbers being two class points to a 8ab design not a 7ab cabin.

Hybrid ovoid means a double bubble style cross section. It still uses circles to have even pressure distribution. Most aircraft are double bubble but usually they are taller than they are wide. The 797 will probably be the first aircraft that has less height than width. Structurally it might weigh slightly more but the reduced surface area means less drag and less fuel burn.

We'll probably see something like my design from a couple years ago. I expect there will eventually be a third stretch model which will pretty much equal the 787-8 in capacity but be much lighter with half the range.


Bases on the graphic above
NMA-6X equals my 797-8
NMA-7X equals my 797-9
Future NMA-8X would be my 797-10

RJMAZ wrote:

Cross section is still open for debate but I think it will be very similar to the 767. Most likely a foot wider to allow tight 8ab while keeping the 767's LD2 containers. Potentially a slightly reduced height cross section to use a brand new full width container.

Actually I think the 797 will have somewhat narrower cross section than the 767. 7 abreast Y with 17,5" only. The 787 is too wide for 8 abreast Y (according to the airlines) and too narrow for 9 abreast (according to the passengers). Same with the 777, too wide for 9 abreast and too narrow for 10 abreast. I don't think Boeing will make this mistake another time and make the fuselage wider (and heavier) than necessary, to compete with large narrowbodies like the A321LR.

parapente wrote:

Considering the incredibly tight lead times put forward for this project it really can't be anything else than Cfm can it?
Boeing would be mad to select anybody else (and they are not mad).
And if I were Cfm I would demand exclusivity too.Cant see that Boeing has any option but to agree.
The 7x (I assume it would be built second) is actually quite a large aircaft that's going to need plenty of ooomph imho.

Of course Boeing doesn't have to agree with exclusivity. It's their RFP, they set the conditions. Demanding exclusivity is the only reason I can see GE/CFM missing out on the 797. GE has a good relationship with Boeing, but nothing is guaranteed. See the A320neo, despite RR's excellent relationship with Airbus, they are not powering the neo.

Didn't RR recently announce a major restructure with upto 4500 people being made redundant. 3000 in the UK and those mostly Managerial and admin. It could be they know the outcome already and it would give more money for investment/development of a new engine or they know they have missed out. Guess you can make what you want from the restructure news.

frigatebird wrote:

Actually I think the 797 will have somewhat narrower cross section than the 767. 7 abreast Y with 17,5" only. The 787 is too wide for 8 abreast Y (according to the airlines) and too narrow for 9 abreast (according to the passengers). Same with the 777, too wide for 9 abreast and too narrow for 10 abreast. I don't think Boeing will make this mistake another time and make the fuselage wider (and heavier) than necessary, to compete with large narrowbodies like the A321LR.

Doubtful. 7ab at those seating values if two class would be nearing 767-400 length. That is getting structurally inefficient.

With a reduced height ovoid cross section the fuselage tube will be more suseptable to bending so optimal finenesd ratio will be less than normal. This points further to an 8ab cabin. It will look slightly stubby when viewed top down but it will look slender from the side due to the reduced height.

The big one is that 8ab is more efficient than 7ab in terms of aisle area. With 17.5" seats and aisles when going to 8ab you gain 14.5% extra seats in the width for only a 11.1% increase in width. That difference of 3.4% is pure efficiency. Its the main reason why the A330 beat the 767.

Financiers and leasors will push against engine exclusivity on future mass models, given current issues with maturity and volume production.

Perhaps a new alliance / JV (or two) will surprise.

RJMAZ wrote:

Doubtful. 7ab at those seating values if two class would be nearing 767-400 length. That is getting structurally inefficient.

With a reduced height ovoid cross section the fuselage tube will be more suseptable to bending so optimal finenesd ratio will be less than normal. This points further to an 8ab cabin. It will look slightly stubby when viewed top down but it will look slender from the side due to the reduced height.

The big one is that 8ab is more efficient than 7ab in terms of aisle area. With 17.5" seats and aisles when going to 8ab you gain 14.5% extra seats in the width for only a 11.1% increase in width. That difference of 3.4% is pure efficiency. Its the main reason why the A330 beat the 767.

DL have roughly these seating capacities (228/267) on their two-class 763s and 764s respectively. I am not sure shorter and fatter would be more efficient from a fitness ratio perspective. The wing wouldn't have to be as large but then again it would be cfrp thinner and have a higher aspect ratio limiting fuel volume.

tortugamon

So Boeing gave them 24 hours. Nice one. But anyway I'm so looking forward to the 797. Mayyyyyyyyyyyyyyyyyyybe they'll launch it at Farnborough but I doubt it.