This is all connected.

You need to define the plane to know how you can built it, which then allows you to identify possible risk sharing partners, which then allows you to define a workflow and a production line,

A PO means that the 797 has moved from a design and market study one step closer to being a real fully fledged development program.

PW100 wrote:

350helmi wrote:

This isn't difficult....He is saying that an A321 @220 seats is heavier than a 797 @270 seats on a per seat basis, which isn't that much of a stretch to imagine IMO.

Not that difficult . . .? ?

(yes, I realize I'm pulling this slightly out-of-context).

I think it will be very difficult, if not imposisble, for a 797 to be lighter per seat than an A321 @220 seats, when at the same time it would have a (significant) range advantage . . .

And apparently you didn't understand the point of that sentence. Was explaining what had been said before, not that it would be easy for the 797 to be lighter than the A321, although I do think on a per seat basis comparing the largest 797 (270pax) vs the A321 (220pax) that may well be the case, but then that really isn't apples to apples comparison. Comparing the (eventual) largest models of both families I think the A322 will be the lighter frame per pax since it will probably have less range and be the slightly smaller frame.

350helmi

Momo1435 wrote:

Boeing recently booked several new 788 orders and had some downward conversions to the -8 as well. It does look like they are actively selling this model again after some years of focusing their sales efforts on the 787-9.

We're talking about a handful 787-8 orders and/or conversions, I hardly call that "actively" selling.

I don't think the 788 will be very useful for shorter routes but there are lots thin routes between 7-10k miles that a 788 modified w 789 build features would be the ideal ac. It may not be a huge market but the 788 would own it

Would this plane be sized for LD2 / DPE containers like the 767? Narrower (bulk only)? Wider (LD3 / AKE)?

Investors Business Daily reported that Boeing will buy Aurora Flight Sciences. Aurora Flight Sciences did the design of the double bubble fuselage for NASA, which may be used in the 797. In addition to the double bubble, the design had engines mounted at the back of the fuselage and smaller wings for improved fuel efficiency. United Technologies was also part of the NASA project, which I assume means Pratt and Whitney has intellectual property in the design.

http://m.nasdaq.com/article/boeings-lat ... e-cm855713

In addition, Boeing may formally unveil plans for the 797 widebody at the Dubai Air Show in November, AeroDefenseNews reported Thursday.

CRHoward wrote:

Investors Business Daily reported that Boeing will buy Aurora Flight Sciences. Aurora Flight Sciences did the design of the double bubble fuselage for NASA, which may be used in the 797. In addition to the double bubble, the design had engines mounted at the back of the fuselage and smaller wings for improved fuel efficiency. United Technologies was also part of the NASA project, which I assume means Pratt and Whitney has intellectual property in the design.

http://m.nasdaq.com/article/boeings-lat ... e-cm855713

I asked a few pages ago, or in another thread maybe, about it the 797 would use fuselage lift to let it have smaller wings and less drag. Should be interesting to see if it’s something truly different. It’s a narrow market if it’s a traditional tube and wing aircraft. It’s a lot different and wider target if it isn’t.

I think the design will look conventional but will take advantage of the IP and experience producing the fuselage via the mandrel process to create a twin aisle craft with single costs. If BA can pull this off the their pioneering efforts on the 787 will be more than validated.

If this can not be accomplished I don't think we will see a MOM. If it can it will be hard to counter.

From these bits of news it does appear that the dreamers at Boeing are back. For that to happen the 787 program must be doing well. I can't see the financial people yielding to another cutting edge project without the 787 being considered a long term success. I do think the comment on a unified wing and fuselage was a red herring. Boeing will do its best to control the message so for now we can only speculate. I'm speculating that Pratt and Whitney will have a buy in with their intellectual property to become one of the two engines offered. I would also go out on the limb and say that CFM will be the second. And RR would again be Airbus's choice for the a322.

CRHoward wrote:

From these bits of news it does appear that the dreamers at Boeing are back. For that to happen the 787 program must be doing well. I can't see the financial people yielding to another cutting edge project without the 787 being considered a long term success. I do think the comment on a unified wing and fuselage was a red herring. Boeing will do its best to control the message so for now we can only speculate. I'm speculating that Pratt and Whitney will have a buy in with their intellectual property to become one of the two engines offered. I would also go out on the limb and say that CFM will be the second. And RR would again be Airbus's choice for the a322.

I don't think the dreamers are back. Boeing already mentioned the next new aircraft design will not be a moonshot project. Instead it will incorporate existing technologies from the 787 and 777X.

What I can't quite understand is what justifies a totally new airframe with 220-270 max seating vs the existing 787-8 which seats 240-360 max, and I'm not sure that the 797's max seating would indeed be 270, perhaps even higher: seabosdca in reply 3 indicated that an ideal one-class max density seating would be more like 300...

Isn't here a significant overlap here? Wouldn't B be better off doing a 787-Lite with less fuel capacity, lighter and less powerful engines (a new GTF development?) and perhaps a (somewhat) shortened fuselage?

I just don't get it...assuming so much development and financial risk for a frame that has a fair chunk of its market dominated by the A321LR at one end and the 787-8 at the other...and not addressing the 737MAX replacement issue at all...


Faro

In many ways it is easy to over complicate Boeing's thinking.This MOM only turned up after the A321NEO LR .This aircraft has has incredibly positive reviews.Only v recently from Air Asia CEO and a few weeks ago from Walsh(IAG) others CEO's have said similar things.It after all effectively a 757 less 30% sfc.
Yes it can go 4.2knm max range with 200-206 pax.But that is max range for tatl.No doubt there are other configs with more pax and a little less range.
Boeing right now does not have a response in this space.So they are looking to cover this - and more - whilst they are at it.
Not rocket science.So no it won't be a moon shot (price) but it will cover what they see as a growing segment covering the old original 757/767 space.

Faro wrote:

What I can't quite understand is what justifies a totally new airframe with 220-270 max seating vs the existing 787-8 which seats 240-360 max, and I'm not sure that the 797's max seating would indeed be 270, perhaps even higher.

Isn't here a significant overlap here? Wouldn't B be better off doing a 787-Lite with less fuel capacity, lighter and less powerful engines (a new GTF development?) and perhaps a (somewhat) shortened fuselage?

I just don't get it...


Faro

Could it be that there's more to it than the number of square feet/meters of cabin space? That something designed to carry enough fuel for 14-16 hour flights can't be very economical flying 6-8 hour flights? I guess we'll find out if the market wants enough of the new aircraft to justify launching it.

Revelation wrote:

Faro wrote:

What I can't quite understand is what justifies a totally new airframe with 220-270 max seating vs the existing 787-8 which seats 240-360 max, and I'm not sure that the 797's max seating would indeed be 270, perhaps even higher.

Isn't here a significant overlap here? Wouldn't B be better off doing a 787-Lite with less fuel capacity, lighter and less powerful engines (a new GTF development?) and perhaps a (somewhat) shortened fuselage?

I just don't get it...


Faro

Could it be that there's more to it than the number of square feet/meters of cabin space? That something designed to carry enough fuel for 14-16 hour flights can't be very economical flying 6-8 hour flights? I guess we'll find out if the market wants enough of the new aircraft to justify launching it.

I'm not disputing the potential market but the means to exploiting it...a totally new aircraft is a huge financial burden and a huge development risk...hence the 787-Lite idea...


Faro

parapente wrote:

In many ways it is easy to over complicate Boeing's thinking.This MOM only turned up after the A321NEO LR .This aircraft has has incredibly positive reviews.Only v recently from Air Asia CEO and a few weeks ago from Walsh(IAG) others CEO's have said similar things.It after all effectively a 757 less 30% sfc.
Yes it can go 4.2knm max range with 200-206 pax.But that is max range for tatl.No doubt there are other configs with more pax and a little less range.
Boeing right now does not have a response in this space.So they are looking to cover this - and more - whilst they are at it.
Not rocket science.So no it won't be a moon shot (price) but it will cover what they see as a growing segment covering the old original 757/767 space.

I agree with your - and more - statement. I don't think this is just about the A321LR. That plane has maybe 50 orders? It is a small market where the extra 7,000lbs of payload of the A321LR over the A321neo are useful. Probably only 100-200 757s were ever used over that range. I don't think there is anywhere near enough of a market for a new plane to target that.

What I see the 797 attacking is not just then A321LR but the replacement for the 767s and A330s flying short to medium haul routes in Asia. That is a much much bigger market and it is growing. Thinner Transatlantic routes, Hawaii and US transcons can also be flown with the same basic airframe as trunk routes in Asia. I think airlines may be waiting on the 797 and what it may offer instead of purchasing the A330neo.

Faro wrote:

Revelation wrote:

Faro wrote:

What I can't quite understand is what justifies a totally new airframe with 220-270 max seating vs the existing 787-8 which seats 240-360 max, and I'm not sure that the 797's max seating would indeed be 270, perhaps even higher.

Isn't here a significant overlap here? Wouldn't B be better off doing a 787-Lite with less fuel capacity, lighter and less powerful engines (a new GTF development?) and perhaps a (somewhat) shortened fuselage?

I just don't get it...


Faro

Could it be that there's more to it than the number of square feet/meters of cabin space? That something designed to carry enough fuel for 14-16 hour flights can't be very economical flying 6-8 hour flights? I guess we'll find out if the market wants enough of the new aircraft to justify launching it.

I'm not disputing the potential market but the means to exploiting it...a totally new aircraft is a huge financial burden and a huge development risk...hence the 787-Lite idea...


Faro

No doubt a totally new aircraft is a huge financial burden and a huge development risk, and yet we see Boeing is still showing signs of moving forward.

The head of the new program office is the former VP/GM of the 787 program.

Clearly if any simple lightweight derivative of the 787 would be viable, he'd know about it.

So far the clear indication is that it is not.

Revelation wrote:

I'm not disputing the potential market but the means to exploiting it...a totally new aircraft is a huge financial burden and a huge development risk...hence the 787-Lite idea...


Faro

No doubt a totally new aircraft is a huge financial burden and a huge development risk, and yet we see Boeing is still showing signs of moving forward.

The head of the new program office is the former VP/GM of the 787 program.

Clearly if any simple lightweight derivative of the 787 would be viable, he'd know about it.

So far the clear indication is that it is not.[/quote]


Yes, that sheds an interesting light on the project if it's being led by the former 787 program VP/GM...he should know better than anyone if a 787-Lite is desirable or not...says a lot about B's risk appetite too...


Faro

Boeing hoodwinked many with the Sonic Cruiser. Would LOVE to see what's on the drawing board. A rear engined twin aisle sounds nice...

Wouldn't be the first to come up with the idea. The BAC 3-11.

Faro wrote:

What I can't quite understand is what justifies a totally new airframe with 220-270 max seating vs the existing 787-8 which seats 240-360 max...

Scores of thousands of kilograms less weight is what justifies it.

The 787-8 has an OEM OEW of 118,000kg. I expect MoM to come in around the 85,000 kilogram mark (around a 767-300ER). That is over 50,000 kilograms lighter and that is going to be huge in terms of trip fuel savings. That will also allow engines designed around 50,000 pounds of thrust to be used, as opposed to the 787's, which are designed around 75,000 pounds.

Stitch wrote:

Scores of thousands of kilograms less weight is what justifies it.

I'd like to come back to this.
ref https://en.wikipedia.org/wiki/Airbus_A330#A330-500

WP:EN:A330 wrote:

A330-500
Also known as the A330-100, the A330-500 was a proposed "shrink" of the A330-200 version launched in July 2000 at the Farnborough Airshow,[157][158] with eight fuselage frames removed – four ahead and four behind the wing. This would allow for the seating of 222 passengers. The −500's maximum takeoff weight was to be 228 tonnes (503,000 lb), a 5-tonne (11,000 lb) decrease from the A330-200, allowing a range of 12,970 km (7,000 nmi; 8,060 mi). A lighter version, at 195 tonnes (430,000 lb), would have flown up to 8,060 km (4,350 nmi; 5,010 mi).[159] The aircraft would have had 5 per cent better specific fuel consumption than the A300-600, powered by either the CF6-80G2, PW4000, or the Trent 500.[157]

OEW increase from A300-600 to that A330-100 is about 31t ( 89t to ~120t ~ +35%)
even if we assume the engine tech unlinked fuel delta to be zero :
That "little bit more" in structure seems to come with zero penalty.
( explains why all the WB craft over time were turned into capable long rangers.)

enzo011 wrote:

Stitch wrote:

The "A322" could very well end up being a "stretch to far". She might also not be able to take the same class of engines as the MoM due to gear height issues, which would impact her TOW. The "A322" could become the 767-400ER to the MoM's A330-200: too little, too late. Sure, Airbus could put an all-new wing on her and an all-new landing gear on her, but then she starts to look like the 777X - a "heavy" frame to support all that new structure competing against a lighter, optimized design. And like the 777X, she will also loses a(n even more) significant amount of parts commonality with her earlier sisters.

Do you think that the twin aisle will weigh less than the single aisle, even with a new wing and landing gear? In that case Boeing and Airbus has been doing things incorrectly all these years. Also, if that is the case I see no reason why Airbus could not design their own MOM in the same vein as Boeing.

Stitch wrote:

enzo011 wrote:

That would leave the 270 seat market and that is where the A338 will sit. You can try and cut the price of the A330 in that case to put pressure on the MOM pricing from above and below. Many airlines seem to favour cheaper prices on frames so it will be interesting where Boeing is able to place a new design in terms of two mature programs.

The A330-800 is likely going to be significantly heavier, however. If MoM is dimensioned around a 767-300, she could be 35,000kg or more lighter than an A330-800. The A332 sold well against the 767 because both were used on 12+ hour missions where the extra passenger and cargo revenue of the A332 outweighed her high fuel burn. MoM is probably going to be used on 6+ hour missions or less and I can't see how an A338 will compete on CASM with such a higher fuel burn in those missions.

Sure it will be heavier, but a discounted A338 should put Boeing in check on price at least. I think you have argued before that the 748i may have not sold a lot, but it at least kept A380 pricing honest. Surely this would be the case here as well?

So would you propose Airbus build an A338 at a LOSS to compete with the B797??
I fail to see what Business sense that makes other than to Make Airbus Bankrupt..
If Boeing has the B797 then Airbus should examine a new design because they will anyway should the B797 proceed to "Eat their Lunch"
Maybe Airbus should try Innovating rather than Imitating because Boeing is in the midst of revamping it's lineup to bring all their offerings into "Fly By Wire" or some advanced flight control regime.
I would have thought by now this would be evident since we're 17 years into the 21st century and even the F-15 is nearly obsolete..
The B737 series will probably go through the same regime next , IF Boeing doesn't rebuild and revamp the B757 with new Technology.
A Lot of you guys already Know this but you're not Looking clearly at the signs. Cables and partially analog or hybrid flight control systems are not going too much further into this century. It's all the way digital or Bust !!

strfyr51 wrote:

So would you propose Airbus build an A338 at a LOSS to compete with the B797??
I fail to see what Business sense that makes other than to Make Airbus Bankrupt..
If Boeing has the B797 then Airbus should examine a new design because they will anyway should the B797 proceed to "Eat their Lunch"
Maybe Airbus should try Innovating rather than Imitating because Boeing is in the midst of revamping it's lineup to bring all their offerings into "Fly By Wire" or some advanced flight control regime.
I would have thought by now this would be evident since we're 17 years into the 21st century and even the F-15 is nearly obsolete..
The B737 series will probably go through the same regime next , IF Boeing doesn't rebuild and revamp the B757 with new Technology.
A Lot of you guys already Know this but you're not Looking clearly at the signs. Cables and partially analog or hybrid flight control systems are not going too much further into this century. It's all the way digital or Bust !!

I think it depends what the 797 can sell for. If it can sell the largest version for prices close to the A321 then obviously Airbus will be in trouble, but I don't see how a new design and all the cost related to that will be able to sell for close to a paid off program. I do agree with you that if Boeing ticks all the boxes with the 797 then Airbus will need to look at their own answer, I don't expect it to happen though.

I would like to know what your definition of innovation and imitating is. I find it funny that you mention Boeing is in the midst of revamping its lineup to the same standard of "Fly By Wire" when Airbus has done this already. What I find interesting is that Boeing has one all electric aircraft, one that is not close to FBW and one FBW aircraft.

strfyr51 wrote:

So would you propose Airbus build an A338 at a LOSS to compete with the B797??

if we take into account that 797 is still 8 years away, and the A330 may be out of production by then, I'd argue that both aircraft do not compete with each other.

WIederling wrote:

Stitch wrote:

Scores of thousands of kilograms less weight is what justifies it.

I'd like to come back to this.
ref https://en.wikipedia.org/wiki/Airbus_A330#A330-500

WP:EN:A330 wrote:

A330-500
Also known as the A330-100, the A330-500 was a proposed "shrink" of the A330-200 version launched in July 2000 at the Farnborough Airshow,[157][158] with eight fuselage frames removed – four ahead and four behind the wing. This would allow for the seating of 222 passengers. The −500's maximum takeoff weight was to be 228 tonnes (503,000 lb), a 5-tonne (11,000 lb) decrease from the A330-200, allowing a range of 12,970 km (7,000 nmi; 8,060 mi). A lighter version, at 195 tonnes (430,000 lb), would have flown up to 8,060 km (4,350 nmi; 5,010 mi).[159] The aircraft would have had 5 per cent better specific fuel consumption than the A300-600, powered by either the CF6-80G2, PW4000, or the Trent 500.[157]

OEW increase from A300-600 to that A330-100 is about 31t ( 89t to ~120t ~ +35%)
even if we assume the engine tech unlinked fuel delta to be zero :
That "little bit more" in structure seems to come with zero penalty.
( explains why all the WB craft over time were turned into capable long rangers.)

The A330-100 wasn't the same as the a330-500. The A330-100 was the more expensive lighter A310 like design with A330 systems / cockpit etc.

https://www.flightglobal.com/news/articles/airbus-rethinks-250-seater-to-keep-a330-commonality-65324/

keesje wrote:

The A330-100 wasn't the same as the a330-500. The A330-100 was the more expensive lighter A310 like design with A330 systems / cockpit etc.

https://www.flightglobal.com/news/articles/airbus-rethinks-250-seater-to-keep-a330-commonality-65324/

The fuel reference is afaics about the high commonality to A330-200 layout i.e. a shrink A330 retaining
that models "full size" wings and the OEW coming with that amount of structure.

Again: riddle me that!

WIederling wrote:

keesje wrote:

The A330-100 wasn't the same as the a330-500. The A330-100 was the more expensive lighter A310 like design with A330 systems / cockpit etc.

https://www.flightglobal.com/news/articles/airbus-rethinks-250-seater-to-keep-a330-commonality-65324/

The fuel reference is afaics about the high commonality to A330-200 layout i.e. a shrink A330 retaining
that models "full size" wings and the OEW coming with that amount of structure.

Again: riddle me that!

You are just comparing the fuel economy of a newer gen jet to an older gen jet. You need to compare how the fuel economy would improve from the older gen jet using a newer gen shrink vs an optimized aircraft of the same tech level as that shrink.

It’s cool that the A331 would have 5% better fuel burn than the A306. That becomes less impressive if a A360 of the same size and tech level as the A331 but optimized for the size burns 25% less fuel.

The question is whether the market is big enough to pay for the development of that A360, versus using a lower cost but les optimized solution.

Does this new office have discretion over the most important issue (maybe only here on A.net ! )? Will the new 797-MoM have a yoke or side-stick? Or maybe this decision is made by some engineering team or customers...or already has been made? Anyhow it may be the job of this new office to flesh-out this kind of issue with customers and suppliers.

My bet is on the first Boeing side-stick...Hardly see any new aircraft maintaining compatibility with the archaic 737 cockpit -- maybe with the 787-type to the extent possible, yoke aside. If B goes ahead with this aircraft...I imagine we will find out about this sooner rather than later.

Question for the finance guys...

I believe boeing would milk 787 tech to the last drop, yoke included.

If they go ahead and end up spending $10 bi to develop this 797, so now you have a 100 million list price airplane to sell...

How many frames would boeing have to sell and deliver before one would call it a sucessful program? Lets say in a 10 year period starting on EIS

Stitch wrote:

Scores of thousands of kilograms less weight is what justifies it.

The 787-8 has an OEM OEW of 118,000kg. I expect MoM to come in around the 85,000 kilogram mark (around a 767-300ER). That is over 50,000 kilograms lighter and that is going to be huge in terms of trip fuel savings. That will also allow engines designed around 50,000 pounds of thrust to be used, as opposed to the 787's, which are designed around 75,000 pounds.

Something along the lines of this?

That is an interesting cross section. The 800 model would be very short I would think. My contention is the big thing for Boeing given how they produce isntondecide on barrel width and establish infrastructure to efficiently produce lots of them.

If you build this 8 wide economy design you can always stretch or rewing and wingbox it later for different missions.

To me an 8 wide has more appeal than a 7.

That cross section provides perfect loading under pressure. Similar to an ATR72. It provides 90% of the advantages of an oval design in terms of surface area and none of the disadvantages. An oval design simply wont work and will always be trying to form a circle under pressure. So it would need to be either super thick and heavy or have a support column in the middle of the cabin.

8 wide is more efficient too than 7 abreast making it worth having the second Aisle.

The fuselage height is only 4.5metres high so the shortest design at 46metres long is actually more slender than a 767-200 and a 787-8. The cabin length would be the same as the A321. But with 8 vs 6 seats in the width that still has 33% more seats in full economy. So it has to be fairly short for an 8 abreast cabin.

I'd expect the 797-8 version to be fairly niche. As the shortest version of any family usually has the worst CASM. I calculate its CASM would actually be similar to a 787-8. So the only advantage would be total trip cost.

The 797-9 would carry more passengers with very little increase in trip cost. So it's CASM would now beat all of the widebody aircraft on medium haul routes across the atlantic.

The 797-10 carries even more passengers with only a further tiny increase in trip costs. Its CASM would now reach narrowbody territory. Its structual weight per seat would equal the A321 with 75% more seats for 75% more weight. So under 1000nm there would be no cost penalty to upsize congested routes.

[photoid][/photoid]

RJMAZ wrote:

Stitch wrote:

Scores of thousands of kilograms less weight is what justifies it.

The 787-8 has an OEM OEW of 118,000kg. I expect MoM to come in around the 85,000 kilogram mark (around a 767-300ER). That is over 50,000 kilograms lighter and that is going to be huge in terms of trip fuel savings. That will also allow engines designed around 50,000 pounds of thrust to be used, as opposed to the 787's, which are designed around 75,000 pounds.

Something along the lines of this?

An interesting graphic. The 787-8 would most likely be made redundant by the 797-10, sizewise.

I wonder, in this scenario, if the -8 or -10 would have different engines/wings over the other two models.

Planeflyer wrote:

I don't think the 788 will be very useful for shorter routes but there are lots thin routes between 7-10k miles that a 788 modified w 789 build features would be the ideal ac. It may not be a huge market but the 788 would own it

I'd be curious what a 788 with the same improvements and MTOW as the 789 has would do for range. It looks like the 10 is a similar ~18' stretch up from the 9 (vs the ~20' difference between the 8 to 9) and that ~18' costs around 1200nmi. You probably wouldn't get the same increase going all the way down to the 8, but I'd assume you'd get at least a 800-900nmi range increase, putting it somewhere around 8000-8200nmi, essentially a smaller, more efficient 777-8X for ULH.

Boeing778X wrote:

An interesting graphic. The 787-8 would most likely be made redundant by the 797-10, sizewise.

I wonder, in this scenario, if the -8 or -10 would have different engines/wings over the other two models.

The 787-8 has not had a large order for a very long time. It also doesnt share many parts with its larger siblings. Where as the 787-9 and 787-10 share a large amount of parts. Some say the 787-8 costs the most to produce.

Boeing would definitely stop production of the 787-8 if such a MOM came out. Any remaining orders would either be upgraded to the 787-9 and customers like Japan that originally ordered the 787-3 for short range use would then convert orders to the 797.

The majority of A330CEO and 767 users operate their aircraft below 4000nm. So the MOM would capture this entire market.

caverunner17 wrote:

I'd be curious what a 788 with the same improvements and MTOW as the 789 has would do for range.... putting it somewhere around 8000-8200nmi, essentially a smaller, more efficient 777-8X for ULH.

The 787-8ER would be a simple addition to the family. However I can't see a huge market for it. Maybe 100 aircraft at most and that wouldnt cover the development. Its a small market shared between the A350-900ulh, 777-8x and 787-8ER. The larger aircraft will usually have better CASM with everything being equal. So I don't think a 787-8ER would actually be superior even with its new technology.

If see a greater chance of a potential lightweight 787-8 being produced with 10% removed from the empty weight and max takeoff weight. So similar range but a lower RASM and CASM.

Polot wrote:

WIederling wrote:

Again: riddle me that!

You are just comparing the fuel economy of a newer gen jet to an older gen jet. You need to compare how the fuel economy would improve from the older gen jet using a newer gen shrink vs an optimized aircraft of the same tech level as that shrink.

Go back and read what I wrote further up.
The A300-600 revamp and the design base for that A330-100 aren't too far apart ( 10 years ).

Thus, even if you attribute the fuel advantage to just engine tech the
susceptibility to increased fuel from increasing wing structure is rather flat.
( There is a reason why airlines (mis)use the A330
for shorter ranges ignoring the much lighter 767 )

Now the same goes in reverse. shrinking the wing and removing associated structure
will also not show the advertised "leap" in performance.

The assumptions behind the MOM are based on a "duh, simply obvious... but wrong" mirage.
Just like all the individual super features ( easily adding up to 10% of the 787 are a mirage.
the only really substantial improvements is engine tech.

RJMAZ wrote:

Something along the lines of this?

RJMAZ wrote:

That cross section provides perfect loading under pressure.

... It isn't a sphere...
It isn't even circular

RJMAZ wrote:

An oval design simply wont work and will always be trying to form a circle under pressure.

Whereas this design will try and form a square? Same still applies here, it is trying to become a circle and you need to locally reinforce where the stresses become higher. To say it can be cost effective to optimise around this cross section is a different matter, it is often said that the limiting factor on skin thickness and weight is different for CFRP than it is for standard so it is conceivable that there is a scenario where there would be no additional weight because ramp rash drives the design and not bending or pressure stresses.

RJMAZ wrote:

The 797-10 carries even more passengers with only a further tiny increase in trip costs. Its CASM would now reach narrowbody territory.

This is the part I really don't understand, the business case for the airline, what would make an airline choose this OVER a narrowbody, there is no reduction in CASM and no increase in range. You want more capacity? send 2 narrowbodies. The reason the A380 doesn't work is the same reason that the MOM doesn't work. Its not that Boeing aren't fantastic manufactures of aircraft its that the physics and the economics don't stack up.

RJMAZ wrote:

Its structual weight per seat would equal the A321 with 75% more seats for 75% more weight. So under 1000nm there would be no cost penalty to upsize congested routes.

Penalties:
Increased types in the fleet
Less fleet flexibility
Additional engine type in the fleet
Benefits:
1 plane instead of two on congested routes

If I was running an airline I would abuse a larger aircraft occasionally rather then add the extra type to my fleet.

Fred

flipdewaf wrote:

It isn't a sphere...
It isn't even circular

The skin is evenly loaded. As there is a floor beam you can think of the upper and lower lobes as separate pressure vessels. The only stress point on the skin is where the floor joins on the side which is reinforced by the floor beam.

Quite a few aircraft are "double bubble" higher than they are wide. The point where the skin circles dissect are always where the floor beam is located.

For instance on the 747 the upper bump uses the upper floor to brace the two circles.

The structure will definitely not form a square.

flipdewaf wrote:

This is the part I really don't understand, the business case for the airline, what would make an airline choose this OVER a narrowbody, there is no reduction in CASM and no increase in range. You want more capacity? send 2 narrowbodies.

Compared to 10 years ago there is now twice as many destination pairs with more than 10 daily flights.

Compared to 10 years ago there are now 4 times as many widebody aircraft on short routes under 1000nm. Even though these aircraft have poor CASM the airlines simply can't add extra narrowbody flights.

This is a worldwide trend. The MOM will solve this problem.

This is not the same as the A380 example where there is a single flight per day between destination pairs.

We're not talking about a small market here. The thickest routes conveniently require the most number of narrowbody aircraft. Pareto's 80/20 principle for example 20% of the worlds busiest routes may use 80% of the worlds aircraft.

So even if only the thickest 10% routes get upgauged to the MOM that would represent over 30% of the narrowbody aircraft replaced.

My CASM analysis is slightly conservative too. The 797-10 best case scenario it will have superior CASM to all 737 and A320's on short routes. The 797-8 best case will have better CASM than the 787-8 and A330 on medium haul.

In all economy config with 30inch pitch the 797-10 would have 380 seats. The A321 has 220 seats.

The 797-10 weighs 65% more but has 75% more seats.

QuarkFly wrote:

Does this new office have discretion over the most important issue (maybe only here on A.net ! )? Will the new 797-MoM have a yoke or side-stick? Or maybe this decision is made by some engineering team or customers...or already has been made? Anyhow it may be the job of this new office to flesh-out this kind of issue with customers and suppliers.

My bet is on the first Boeing side-stick...Hardly see any new aircraft maintaining compatibility with the archaic 737 cockpit -- maybe with the 787-type to the extent possible, yoke aside. If B goes ahead with this aircraft...I imagine we will find out about this sooner rather than later.

As far as I can see, the most important and most discussed aspect of airplane design on airliners.net is how wide the economy seats are and how wide the cabin is.

I doubt Boeing will ever get rid of the yoke.

RJMAZ wrote:

Stitch wrote:

Scores of thousands of kilograms less weight is what justifies it.

The 787-8 has an OEM OEW of 118,000kg. I expect MoM to come in around the 85,000 kilogram mark (around a 767-300ER). That is over 50,000 kilograms lighter and that is going to be huge in terms of trip fuel savings. That will also allow engines designed around 50,000 pounds of thrust to be used, as opposed to the 787's, which are designed around 75,000 pounds.

Something along the lines of this?

This is probably the closest concept to a plausible design that I have seen posted. Where did it come from? A few comments, MTOW doesn't need to be identical for all three planes. I would expect some variability. Also I would not focus too heavily on LD3-45s. Boeing is probably not afraid to require a new container if it increases useable volume.

Newbiepilot wrote:

This is probably the closest concept to a plausible design that I have seen posted. Where did it come from? A few comments, MTOW doesn't need to be identical for all three planes. I would expect some variability. Also I would not focus too heavily on LD3-45s. Boeing is probably not afraid to require a new container if it increases useable volume.

Plenty of clues: The focus on the containers, the spelling of pressurisation -- no house fly, though.

I made it myself.

For the specs I based the smallest size off the A310-300, length and wingspan. The A310-300 has a 77T empty weight, 164T MTO with a range of 5150nm using 61,000L of fuel. With modern engines I estimated range would increase to 6300nm. Probably too much range, so it could be made lighter.

This forms the shrink model where I then reduced MTO to 150T bringing the range to the 5300nm you see listed. I reduced the fuselage width by 1 foot and the height by 3 feet which would bring the empty weight down slightly from 77T to 75T. Considering the aircraft would use composites that weight would be realistic.

I then found how much weight is added when you stretch a 767 and A330. I added 5T for the 797-9 and 10T for the 797-10 to get their empty weights. To calculate the range of the stretch models I worked out how much weight was left for fuel after adding a typical payload.

If it was a 2 aircraft family you could pick two aircraft at any point between the 797-8 and 797-10 that I listed.

For example
48m - 5000nm range
56m - 4000nm range

Revelation wrote:

Newbiepilot wrote:

This is probably the closest concept to a plausible design that I have seen posted. Where did it come from? A few comments, MTOW doesn't need to be identical for all three planes. I would expect some variability. Also I would not focus too heavily on LD3-45s. Boeing is probably not afraid to require a new container if it increases useable volume.

Plenty of clues: The focus on the containers, the spelling of pressurisation -- no house fly, though.

The artist with the house fly has been pushing goofy extra wide narrowbody designs and unconventional greenliner concepts. There has been some over emphasis on LD3-45 containers.

This design is new and much more intriguing.

Would the D8 concept form Aurora fit in to the MOM?

RJMAZ wrote:

Quite a few aircraft are "double bubble" higher than they are wide. The point where the skin circles dissect are always where the floor beam is located.

This arrangement has a negative distance between circle centers.
That turns the force needed to "hold it together" from pull to push.

Floor beams under compression is a far from optimal arrangement.

This is one of these "duh, obvious, must be good" thingies that are anything but. ..

WIederling wrote:

RJMAZ wrote:

Quite a few aircraft are "double bubble" higher than they are wide. The point where the skin circles dissect are always where the floor beam is located.

This arrangement has a negative distance between circle centers.
That turns the force needed to "hold it together" from pull to push.

Floor beams under compression is a far from optimal arrangement.

This is one of these "duh, obvious, must be good" thingies that are anything but. ..

This approach is not being considered for aesthetics like BER's approach to fire control, it's being considered because the shape is the one that delivers the desired capacity.

I'm pretty sure Boeing's engineers understand the implications.

It'll be interesting to see the final design.

Revelation wrote:

Plenty of clues: The focus on the containers, the spelling of pressurisation -- no house fly, though.

ExifTool Version Number : 9.01
File Name : 797.jpg

File Size : 119 kB
Software : Adobe Photoshop CS6 (Windows)
Modify Date : 2017:10:13 09:15:57
Artist : Tola Badekale
XP Author : Tola Badekale
Date/Time Original : 2017:02:18 08:59:14
Create Date : 2017:02:18 08:59:14

https://twitter.com/boeing/status/754008960261246976

RJMAZ wrote:

flipdewaf wrote:

It isn't a sphere...
It isn't even circular

The skin is evenly loaded. As there is a floor beam you can think of the upper and lower lobes as separate pressure vessels. The only stress point on the skin is where the floor joins on the side which is reinforced by the floor beam.

Quite a few aircraft are "double bubble" higher than they are wide. The point where the skin circles dissect are always where the floor beam is located.

For instance on the 747 the upper bump uses the upper floor to brace the two circles.

Higher than wide has a different load distribution than wider than high. For wider than high the biggest force is found exactly where the floor beam is located as the pressure wants to push this parts outside. In your design this point is in the upper point of the fuselage and the forces needs to be absorbed through the whole fuselage until transferred into the floor beams

Every now existing wide body uses containers, is really somebody believing that if the 797 will come it will be without containers? I do not know about the LD3-45, it could be a new size special to the 797.
Apart from that, I believe Airbus could counter with a new "A310" not that bird, but a new frame in that form factor.