Newbiepilot wrote:

I think the A330-200/300 order mix is more based on evolving weights than any specific pivot point where range is more important than CASM.

But surely CASM roughly stayed the same between the two variants?

The only real change I can see was payload-range and I suppose, absolute range.

(Aircraft weights in themselves aren't important to an airline. The effects of weight, i.e. payload, payload-range, range and fuel burn, are.)

Newbiepilot wrote:

keesje wrote:

Newbiepilot wrote:

What is the hard evidence? How many A321LRs have been sold with its rapidly growing fan base? Do you have the numbers? There is a market for that plane, but only 100-200or so 757s were regularly operating routes over 3000nm. The A321LR is only a 7,000lbs MTOW upgrade over the A321neo. I am very curious how big of a chunk out of the NMA market will be the A321LR. It will be part of it, but how much is the big question?

It sounds like you backed off your original claim that I originally quoted



There has been no narrowbody that can move 200 people over 4000NM since the DC8 so you can’t claim an observation that a narrowbody costs less fuel and has significantly lower costs. The A321LR is being marketed as capable of doing that. That market in the last 40 years has been flown by widebodies.

If you looked at the hard data I linked you could see where this is coming from. If the differences in weight / costs between similar sized NB and WB's would be close, we could have a discussion.

https://www.airliners.net/forum/viewtopic.php?t=1362827

They aren't. Unless you move towards 300 passenger, than conventional 3-3 fuselages become long / relatively heavy.

Probably one of the reason Boeing has been dragging it's feet on MoM, NMA, 757 replacement for more than 5 years now.
https://flyawaysimulation.com/news/4596/

Hard data would be fuel burn and operating costs. Comparing OEWs isn't hard data to support your claim that "moving 200 people /25t over 4000NM using a NB costs less fuel and has significantly lower costs". Do you have actual hard data? No one is using A321s on 4000nm flights, but an airline like United knows the cost of the 757, 767, and 787 over that type of distance. The longest A320 family flights are only 3000 miles. Copa would have numbers for the 737NG since they have the longest flights on the older generation narrowbodies and Norwegian has numbers for the 737MAX and WOW Air for the A321NEO on transatlantic flights.

You have not shared any hard data supporting the capacity where narrowbodies or widebodies are more efficient. It appears you pulled 300 passengers out of thin air. The maximum number of seats ever certified on a narrowbody is 259, so clearly the transition point where widebodies are more efficient than narrowbodies is less than 300.

Newbie, airlines don't need proven, hard data to have a pretty good idea on costs, economics, . It's called calculations, modelling, simulation. They even order aircraft before they are build / tested, based on that. Thousands .

Do you believe a twin aisle could have the same economics as a single aisle around 200 seats/4000NM? Why?

The maximum number of seats ever certified on a narrowbody is 259

Nope 295. You could say this is not 300, but it's close enough for me to confirm my observations (OEW 757-300: ~65t, 767-200: ~ 80t).

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/76f1b4b597ac25cf86257d430062f219/$FILE/A2NM_Rev_31.pdf

It's in operation with 280 seats. https://www.seatguru.com/airlines/Thomas_Cook_Airlines/Thomas_Cook_Airlines_Boeing_757-300.php

keesje wrote:

Do you believe a twin aisle could have the same economics as a single aisle around 200 seats/4000NM? Why?

I believe a twin certainly could have better economics because they are the only airplanes flying now that actually can fly 4000NM with 200 seats or 25tons of payload. I also believe that the width of the cabin isn't a huge factor in determining efficiency. You and a few others talk frequently about narrowbody vs widebody, but as I said before, a few percent penalty for a wider cabin can be partially offset with shorter landing gear, and shorter wiring runs, hydraulic tubes, etc so this widebody vs narrowbody argument is over exaggerated. The Airbus marketing folks and fans want to convince everyone that narrowbodies are better since they want to focus on the A321. The Boeing marketing folks and fans want to focus on widebody at narrowbody cost. I personally don't care how wide an airplane is. To me, engines, wings, landing gear and weights are more important to optimize an airplane for its mission.

keesje wrote:

The maximum number of seats ever certified on a narrowbody is 259

Nope 295. You could say this is not 300, but it's close enough for me to confirm my observations (OEW 757-300: ~65t, 767-200: ~ 80t).

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/76f1b4b597ac25cf86257d430062f219/$FILE/A2NM_Rev_31.pdf

It's in operation with 280 seats. https://www.seatguru.com/airlines/Thomas_Cook_Airlines/Thomas_Cook_Airlines_Boeing_757-300.php

Sorry I got my numbers wrong on the 757-300 since I thought we were still talking about 4000nm range and that meant DC8. Given the number of 757-300s sold, it is pretty apparent that it is not the ideal pivot point between narrowbodies and widebodies.

Amiga500 wrote:

Newbiepilot wrote:

I think the A330-200/300 order mix is more based on evolving weights than any specific pivot point where range is more important than CASM.

But surely CASM roughly stayed the same between the two variants?

The only real change I can see was payload-range and I suppose, absolute range.

(Aircraft weights in themselves aren't important to an airline. The effects of weight, i.e. payload, payload-range, range and fuel burn, are.)

The relative importance of CASM has gone up in the past decade. In the past RASM more heavily influenced purchasing decisions. Smaller planes kept revenue per seat up since airlines didn't have to deeply discount as many tickets. What I mean when saying that is before we had more sophisticated revenue management systems, airlines would buy smaller planes to keep RASM higher while maintaining frequency. Optimized revenue management reservation systems have helped fill extra seats, especially with connecting traffic while protecting yields. Airlines are able to fill empty seats much more efficiently now than they were two decades ago and therefore emphasis on CASM is higher and thus larger airplanes are desirable. We are seeing this with both narrowbodies and widebodies. Interests in smaller derivatives like the A319, 737-7, A332, A338, 788, 772, 778 etc has all faded.

Newbiepilot wrote:

Airlines are able to fill empty seats much more efficiently now than they were two decades ago and therefore emphasis on CASM is higher and thus larger airplanes are desirable. We are seeing this with both narrowbodies and widebodies.

We certainly aren't seeing it with 777X and A380. Indeed, the A35k sales are not stellar.

Newbiepilot wrote:

Interests in smaller derivatives like the A319, 737-7,

The trip cost advantage these two offer over the larger siblings is notoriously small.

Indeed, looking back, its very surprising they sold as well as they did.

Newbiepilot wrote:

A332, A338, 788, 772, 778 etc has all faded.

The A338 and 778 did not launch 2 decades ago. The 772 was ultimately replaced by the 77W, not really dropping range. The discussion about the A332 vs 333 is related to our topic.

It would also be remiss to point out none of the 772, 778 or 338 had a larger sibling which had an initial max range of ~<4000nm.

From KarelXWB a couple of years ago:

Amiga500 wrote:

So from that:
1. Are there any other examples that back up my conclusion? If so...
2. What is this threshold?
3. Is the MoM going to be above it in any guise?
4. Will the variants that don't meet it sell in significant numbers.
5. Will the variants that do meet it really be cannibalising 787 sales?

I don't think that threshold exists anymore.

The market is now much different. This was when the 747 was still flying most long haul routes. The A330 and 767 could provide increased frequency on the routes flown by old 747-200's. So only once the range on paper reached 6000nm did their sales increase.

Back then the 737 struggled to fly 2500nm.

Today we have narrowbody of aircraft pushing 4000nm and the efficient 787 flying 5000-7000nm. Routes under 1000nm are getting thicker and thicker.

CASM has become the primary market driver. Optimising the plane to a certain range and payload can give a 5-10% CASM improvement using similar technology and engines.

If you want to fly transatlantic and need a 5000nm paper range. Take two identical capacity and technology aircraft. One is designed with a 5000nm range the other 7000nm range. The longer range aircraft has 50+% more fuel, a bigger wing, weighs more empty. When flying transatlantic the shorter range plane will have significantly better CASM.

The world market is now so big, building a niche aircraft can still sell thousands of frames.

With one design you can hit two of these large niche markets. Using the same wing with a shrink short fuselage you can get a tranatlantix plane with better RASM and CASM than the 788. Using a stretch fuselage you can get a short thick route aircraft. One that can replace two narrowbody flights burnung less total fuel and less overall crew costs.

RJMAZ wrote:

Amiga500 wrote:

So from that:
1. Are there any other examples that back up my conclusion? If so...
2. What is this threshold?
3. Is the MoM going to be above it in any guise?
4. Will the variants that don't meet it sell in significant numbers.
5. Will the variants that do meet it really be cannibalising 787 sales?

I don't think that threshold exists anymore.

The market is now much different. This was when the 747 was still flying most long haul routes. The A330 and 767 could provide increased frequency on the routes flown by old 747-200's. So only once the range on paper reached 6000nm did their sales increase.

Back then the 737 struggled to fly 2500nm.

Today we have narrowbody of aircraft pushing 4000nm and the efficient 787 flying 5000-7000nm. Routes under 1000nm are getting thicker and thicker.

CASM has become the primary market driver. Optimising the plane to a certain range and payload can give a 5-10% CASM improvement using similar technology and engines.

If you want to fly transatlantic and need a 5000nm paper range. Take two identical capacity and technology aircraft. One is designed with a 5000nm range the other 7000nm range. The longer range aircraft has 50+% more fuel, a bigger wing, weighs more empty. When flying transatlantic the shorter range plane will have significantly better CASM.

The world market is now so big, building a niche aircraft can still sell thousands of frames.

With one design you can hit two of these large niche markets. Using the same wing with a shrink short fuselage you can get a tranatlantix plane with better RASM and CASM than the 788. Using a stretch fuselage you can get a short thick route aircraft. One that can replace two narrowbody flights burnung less total fuel and less overall crew costs.

In addition to all of this if you can do this program and make your typical profit margins it gives you the chance to work on certain technologies you want to push forward for a new narrowbody. I would put the following on that list as spin off benefits you can get.

1. Increasing automation of the manufacturing process for a CFRP airliner. This is of huge importance to any new narrowbody.

2. I expect this plane to explore the potential of going down to one pilot instead of two.

3. I expect Boeing to build this aircraft somewhere other than Washington and I expect the same to be true of a new narrowbody when that time comes.

One of the keys to wanting to do this program is that the technology and business case for a new narrowbody simply isn’t there yet. IMHO it won’t be until there is a change in basic propulsion/airframe setup. Finding a profitable way to move things forward is important overall. The 797 is key to the 737 replacement in that it can do a fair amount of de-risking while also defining the upper boundaries on just what a 737 replacement will actually be.

bigjku wrote:

1. Increasing automation of the manufacturing process for a CFRP airliner. This is of huge importance to any new narrowbody.

I expect this is the biggest risk of the MOM program.

The 787 program worked out how to build a carbon plane.
The 797 will work out how to build one cheaply.

To reduce production costs requires an exponential increase in automation and reduction of parts count. This will not be easy or cheap to develop.

If Boeing skimps on the development and simply builds it like scaled down 787 its production cost per plane will be too high. Every plane may have to be sold at cost price and the development cost would never get paid off.

If Boeing gets production costs down low the profit per frame can eventually pay off the development cost. Even if the development costs to pay for this automation will be much higher it will be better in the long run. As you point out this experience is required for a future 737 replacement.

Could it not be possible that Boeing are considering long-term the 737 replacement and therefore, will pitch a single aisle that covers the 757-200/300 initially (220-270 pax) with an all new fuselage, wing and engine. Then, using this fuselage ultimately an integral part of the 737 replacement?

If there is talk of making a twin aisle with single aisle economics surely airlines would consider a single aisle with even better economics?

Btblue wrote:

Could it not be possible that Boeing are considering long-term the 737 replacement and therefore, will pitch a single aisle that covers the 757-200/300 initially (220-270 pax) with an all new fuselage, wing and engine. Then, using this fuselage ultimately an integral part of the 737 replacement?

If there is talk of making a twin aisle with single aisle economics surely airlines would consider a single aisle with even better economics?

First I am not 100% sure that a large narrow will do better on the market so I think that assumption isn’t a sure thing.

Second I don’t think that anyone is 100% sure exactly what a new narrowbody will look like so you can design a fuselage that works for it just yet. IMHO no one will touch a new narrowbody until they can make a large leap in efficiency. That means either a new shape or a new propulsion setup (hybrid electric or something) so you can’t really design a fuselage that works for it yet.

From what I can gather from people at Boeing I have chatted with they believe that the range of most aircraft airlines want will be best covered by 4 aircraft. They know they eventually have to move to build a new narrowbody but the capital investment on such a product will be huge. You can’t do it until you are certain you won’t be preempted and that you can deliver the product at a price the market will bear. I think those economics change when the propulsion technology changes. But do it before then you run the risk of having happen what happened to the c series when the 737 and A320 just took new engines without all the investment for a new airplane.

Too long to read version...building a new narrowbody likely has an awful business case right now.

Btblue wrote:

Could it not be possible that Boeing are considering long-term the 737 replacement and therefore, will pitch a single aisle that covers the 757-200/300 initially (220-270 pax) with an all new fuselage, wing and engine. Then, using this fuselage ultimately an integral part of the 737 replacement?

If there is talk of making a twin aisle with single aisle economics surely airlines would consider a single aisle with even better economics?

As engine efficiency improves and materials become lighter/stronger it has a flow on effect on the size if the plane.

The 737 replacement that seats the same number of passengers as a 737-8 will then be much lighter. It will require a smaller wing, less fuel capacity and engines with less thrust to perform the same mission.

It would be impossible to make one wing and engine combination that could scale from the 737-8 market up to the 757-300 MOM market. This would end up with the 737-8 size being overweight and the 757-300 being underwinged with poor lift to drag. So both models would get beaten by an optimised design.

The A321LR is already shows signs of this. It is clearly underwinged and the A320 is overweight compared to the 737 on short sectors.

The MOM 797 needs to be a carbon shortish 8AB to get that 757-300/767-200 capacity/range target. It will mature carbon fibre production to get costs down.

The 737 replacement will need to be a carbon 6ab, 200 seats and fully optimised for maximum efficiency under 3000nm. The CS500 would provide the minimum benchmark. The CS500 would be around 10T lighter than a similar capacity and range 737MAX. No oval 7ab fuselage here.

A tight, 6AB, fully optimised, carbon, short ranged aircraft from Boeing could easily trump the CS500 which is too wide for only 5abreast.

RJMAZ wrote:

Btblue wrote:

Could it not be possible that Boeing are considering long-term the 737 replacement and therefore, will pitch a single aisle that covers the 757-200/300 initially (220-270 pax) with an all new fuselage, wing and engine. Then, using this fuselage ultimately an integral part of the 737 replacement?

If there is talk of making a twin aisle with single aisle economics surely airlines would consider a single aisle with even better economics?

As engine efficiency improves and materials become lighter/stronger it has a flow on effect on the size if the plane.

The 737 replacement that seats the same number of passengers as a 737-8 will then be much lighter. It will require a smaller wing, less fuel capacity and engines with less thrust to perform the same mission.

It would be impossible to make one wing and engine combination that could scale from the 737-8 market up to the 757-300 MOM market. This would end up with the 737-8 size being overweight and the 757-300 being underwinged with poor lift to drag. So both models would get beaten by an optimised design.

The A321LR is already shows signs of this. It is clearly underwinged and the A320 is overweight compared to the 737 on short sectors.

The MOM 797 needs to be a carbon shortish 8AB to get that 757-300/767-200 capacity/range target. It will mature carbon fibre production to get costs down.

The 737 replacement will need to be a carbon 6ab, 200 seats and fully optimised for maximum efficiency under 3000nm. The CS500 would provide the minimum benchmark. The CS500 would be around 10T lighter than a similar capacity and range 737MAX. No oval 7ab fuselage here.

A tight, 6AB, fully optimised, carbon, short ranged aircraft from Boeing could easily trump the CS500 which is too wide for only 5abreast.

Hey RJMAZ.

I meant a common developed fuselage for the 757-200/300 which would then lend itself to the 737 replacement in the long term, but with a different wing (for both models (plus 220 and sub 220)). High ground clearance ensuring future propulsion possibilities.

Btblue wrote:

Hey RJMAZ.

I meant a common developed fuselage for the 757-200/300 which would then lend itself to the 737 replacement in the long term, but with a different wing (for both models (plus 220 and sub 220)). High ground clearance ensuring future propulsion possibilities.

The tube of the fuselage is the cheapest and easiest part.

The wing, wingbox, engines, landing gear and tail would be totally difference and they are more complex.

At a certain point it actually becomes lighter to go with a wider cross section. Sharing cockpits and systems is good enough. So using the correct cross section for the job

Even if you went with 6AB totally optimising the designs would require a different cross section anyway.

The 35-40m short range model would be best designed with smaller 17" seats for 1 hour long flights and a narrow 20" aisle.

The 50-55m long range model would be best designed with more comfortable 18" seats for 8+ hour flights and a 22" aisle due to the cabin length being nearly twice as long. Everyone wished the 757 had a wider aisle.

If you used the wider cross section from the long range model on the short range model that would put it at a 3-5% weight disadvantage.

Its a pretty big deal. If the C series was built with a cross section 6inchs narrower it would weigh 5% less have 5% better CASM and in my opinion it would have sold twice as many aircraft due to that advantage.

RJMAZ wrote:

Btblue wrote:

Hey RJMAZ.

I meant a common developed fuselage for the 757-200/300 which would then lend itself to the 737 replacement in the long term, but with a different wing (for both models (plus 220 and sub 220)). High ground clearance ensuring future propulsion possibilities.

The tube of the fuselage is the cheapest and easiest part.

The wing, wingbox, engines, landing gear and tail would be totally difference and they are more complex.

At a certain point it actually becomes lighter to go with a wider cross section. Sharing cockpits and systems is good enough. So using the correct cross section for the job

Even if you went with 6AB totally optimising the designs would require a different cross section anyway.

The 35-40m short range model would be best designed with smaller 17" seats for 1 hour long flights and a narrow 20" aisle.

The 50-55m long range model would be best designed with more comfortable 18" seats for 8+ hour flights and a 22" aisle due to the cabin length being nearly twice as long. Everyone wished the 757 had a wider aisle.

If you used the wider cross section from the long range model on the short range model that would put it at a 3-5% weight disadvantage.

Its a pretty big deal. If the C series was built with a cross section 6inchs narrower it would weigh 5% less have 5% better CASM and in my opinion it would have sold twice as many aircraft due to that advantage.

I disagree that the CSeries problem is in the fuselage sizing, rather it's in the size of the wings/stabilizers driven by the design range. The CS100 and CS300 are built to fly over 3,000nmi, which is far greater than 99% of it's missions will ever be. If they had sized the major components to reflect an actual design range of 1,500nmi - 2,000nmi, you would have an aircraft that is not only lighter in OEW, but also generates significantly less parasite drag due to the lower wetted areas. This would have sold much better than the current design as you would have an even larger efficiency gap between the CSeries and 737/A320, making it more difficult for the big guys to neutralize this via price.

If you want evidence of this, Leeham recently claimed that Delta was able to obtain a lower purchase price by capping the aircraft's range at 1,000nmi, and paying per-use for routes above that. No need to carry around the extra structure for range you don't use.

heavymetal wrote:

I disagree that the CSeries problem is in the fuselage sizing, rather it's in the size of the wings/stabilizers driven by the design range. The CS100 and CS300 are built to fly over 3,000nmi, which is far greater than 99% of it's missions will ever be. If they had sized the major components to reflect an actual design range of 1,500nmi - 2,000nmi, you would have an aircraft that is not only lighter in OEW, but also generates significantly less parasite drag due to the lower wetted areas. This would have sold much better than the current design as you would have an even larger efficiency gap between the CSeries and 737/A320, making it more difficult for the big guys to neutralize this via price.

If you want evidence of this, Leeham recently claimed that Delta was able to obtain a lower purchase price by capping the aircraft's range at 1,000nmi, and paying per-use for routes above that. No need to carry around the extra structure for range you don't use.

I've posted this exact thing many times in various threads.

This is true if the CS100 and CS300 were to be the only models. They have too much range, wing and weight. However the current C series wing and structure would be perfect for the stretched CS500. It would have a much lower range and be much lighter per seat. Its CASM would probably be the best jet on the market.

So the only thing that could have improved the CS500 even further would be a 6inch narrower fuselage. Lucky for Boeing it gives them a lower benchmark to surpass with the 737 replacement.

RJMAZ wrote:

You need a big CASM advantage to break into an existing market. Airlines won't risk adding a new aircraft type unless there is a big financial gain.

The C series was built with too much capability. The CS100 and CS300 have similar CASM to the Max 7 and 8. When an airline is operating multiple flights a day on any given route there is no disadvantage of operating a larger aircraft. So the Max 8 will win.

Considering most the the 737 flights are below 1000nm sector lengths the C series could have been built lighter with less range while carrying the same number of passengers. This would have given the C series the CASM advantage to break into the market.

Bit of a shame really. A CS500 simple stretch with no thrust bump or MTO increase would provide the CASM advantage needed. But ideally the CS300 fuselage length should have been the stretch model.

RJMAZ wrote:

I don't think that threshold exists anymore.

Not sure I agree with that. This change from -200 to -300 occurred less than 10 years ago.

RJMAZ wrote:

The world market is now so big, building a niche aircraft can still sell thousands of frames.

I agree with the premise, but not the figures. If the A380 is niche, its not selling thousands. If the 777-8 is niche, its also not selling thousands.

I think you can build a niche aircraft economically, but I would think it needs to be a variant of a family that has its design point centred around a substantial market - i.e, the A319 and 737-7 are anchored by the A320 & 373-8. The 777-8 will be anchored by the 777-9. The A380 is standing on its own two feet and we don't need to comment further on it.

I'm not sure the 787 program is a good example given the teething issues, but right now, it'd seem that the -9 and -10 will bail out the -8 which is in a bit of a niche - and perilously close to MoM in capacity. But, as I said, I'm not sure I should use that example - although is it unreasonable to expect a new program (aka new airframe) to have issues? Since 777, we've had A380, A350, B787, B747-8, CSeries. All of them were delayed to varying degrees and the only one that didn't descend into Charlie Foxtrot status was the A350. Not exactly a glowing resume of delivery by any of the OEMs.

I thought this thread is about Airbus response to a potential MOM and not about Boeing´s potential MOM

RJMAZ wrote:

So the only thing that could have improved the CS500 even further would be a 6inch narrower fuselage. Lucky for Boeing it gives them a lower benchmark to surpass with the 737 replacement.

Just for info, I've seen many people use incorrect data thats on the interwebz for the fuselage before.

You may already know, but the CSeries fuselage is not circular, its not even elliptical or ovoid. There are at least three separate radii that describe the outer mould line. Its a complex curvature that does enhance floor space and shoulder width while minimising the underfloor region and void in the crown.

Its a balls from a stress/fatigue perspective, but should be fairly good in terms of wetted area.

Of course, I suppose there is nothing to stop Boeing applying the same philosophy, but doing so with 6x 17" seats and a narrow aisle. How well that would be received is questionable though.

RalXWB wrote:

I thought this thread is about Airbus response to a potential MOM and not about Boeing´s potential MOM

It is. Its just widening discussion to consider whether (i) the MoM is substantial, (ii) whether Boeing will actually commit to a dedicated MoM program, (iii) whether Airbus would be justified in following them and (iv) whether Airbus would be better served by nibbling at it from both ends with variants of existing products.

Threads drift. Accept it and you'll be happier (and more informed) for it.

Amiga500 wrote:

RJMAZ wrote:

So the only thing that could have improved the CS500 even further would be a 6inch narrower fuselage. Lucky for Boeing it gives them a lower benchmark to surpass with the 737 replacement.

Just for info, I've seen many people use incorrect data thats on the interwebz for the fuselage before.

You may already know, but the CSeries fuselage is not circular, its not even elliptical or ovoid. There are at least three separate radii that describe the outer mould line. Its a complex curvature that does enhance floor space and shoulder width while minimising the underfloor region and void in the crown.

Its a balls from a stress/fatigue perspective, but should be fairly good in terms of wetted area.

Of course, I suppose there is nothing to stop Boeing applying the same philosophy, but doing so with 6x 17" seats and a narrow aisle. How well that would be received is questionable though.

Technically the C-series can be outfitted 6-abreast with 16.5" seats, which would solve the "too capable" and CASM issues, I'd be very surprised if BBD didn't offer that to prospective airlines...

As for Boeing's MOM, they're at the awkward capacity spot where single-aisle starts to impede on operations (turn-around times) and twin-aisle is still meh for Economics. I am guessing that a clean-sheet MOM will either be a 787-esque 8ab (tight) or a single-aisle 6ab. That should apply with AB either rewinging/optimize the A330 or scaling up the A321.

Lets assume you can pass a fellow passenger when the aisle is 30 inch wide, instead of the regular 18-20 inch width. During (de)boarding, if 5 people are standing in the aisles doing something, you can pass all of them.

If those same 5 people are standing in the aisles doing something on a bigger 2 narrow (18") aisles aircraft, you can not pass them. So what is better for speed, 1 wide aisle or 2 regular narrow ones?

If we make a narrow body 10 inches wider & keep the cargo belly as flat as on an A320, it creates space for a twin aisle premium cabin (everybody aisle access). A 10 inch wider fuselage also does wonders for structural efficiency / weight when going beyond 35 seat rows.

JustSomeDood wrote:

Technically the C-series can be outfitted 6-abreast with 16.5" seats, which would solve the "too capable" and CASM issues, I'd be very surprised if BBD didn't offer that to prospective airlines...

Yeah, that was doing the rounds a few years back too, but how realistic are 16.5" seats?

For reference, the BAe 146 has - Floor width: 3.24m, shoulder width: 3.42m
The CSeries has - Floor width: 3.10m, shoulder width: 3.28m


How many operated the 146/RJ with 6 a-breast?

keesje wrote:

Lets assume you can pass a fellow passenger when the aisle is 30 inch wide, instead of the regular 18-20 inch width. During (de)boarding, if 5 people are standing in the aisles doing something, you can pass all of them.

If those same 5 people are standing in the aisles doing something on a bigger 2 narrow (18") aisles aircraft, you can not pass them. So what is better for speed, 1 wide aisle or 2 regular narrow ones?

If we make a narrow body 10 inches wider & keep the cargo belly as flat as on an A320, it creates space for a twin aisle premium cabin (everybody aisle access). A 10 inch wider fuselage also does wonders for structural efficiency / weight when going beyond 35 seat rows.

You mean like the MC-21?



The MC-21 looks to be a cracking technical product. Right sized, with very advanced manufacturing techniques that don't cost the earth.

Politics will screw it though.

In terms of a potential Airbus response.If Airbus think it's ok to take 206 pax (2 class) 4,000nm board and de board with the existing (great) fuse would they really go to the enormous expense to build a new aircraft 10" wider? (However good It maybe).

I guess it would be worth it if they felt they could (over time) replace the whole 320 family with this new design (obviously there would be the need for an additional smaller wing/engine combo.
But their present design is winning anyway and they are first out of the blocks with a MOM - the 321LR.
Price is another very big factor as the airlines have reminded Boeing.

If Airbus can use their present fuse and all the internal systems (and tail?).Re work their old double bogey MLG ,insert their new (but existing) monolithic carbon box section the 'all' they have to do is a new wing (engine is not their concern).One writer above suggested a total cost of €2billion if I am not mistaken.They would absolutely murder Boeing on price - and if the new engine could be readied earlier they could certainly be ready earlier ,thus beating Boeing to market as well (airlines have also mentioned timing as a critical factor).

Weighting up all these factors I am not sure they would want to go for a clean sheet when the size of the market is abit 'iffy' anyway.

I can see that a wider central aisle would help de boarding,but I was always given to understand that this mattered less on longer distance flights ( which these would be) as opposed to the usual 2-3 hour LCC type flights.

Amiga500 wrote:

You mean like the MC-21?

The MC-21 looks to be a cracking technical product. Right sized, with very advanced manufacturing techniques that don't cost the earth.

Politics will screw it though.

If only they had sold their program to Airbus for a ruble they'd be in a much better position.

Revelation wrote:

If only they had sold their program to Airbus for a ruble they'd be in a much better position.

Too much overlap with A321LR.

But if Boeing came in with an offer... it'd really solve a lot of their short-term problems (although I suppose, you'd be aiding a large organisation who would eventually go their own way and become a direct competitor).

keesje wrote:

A 10 inch wider fuselage also does wonders for structural efficiency / weight when going beyond 35 seat rows.

Can you please provide an explanation for the definition of "wonders for structural efficiency"? Are you implying that a wider fuselage and larger diameter oval will actually be lighter than a smaller diameter oval? Airplane fuselages aren't simple cylinders.





What happens beyond 35 rows that causes the stringers to shrink and become lighter if the diameter of the airplane and therefore length of frames becomes bigger? The width of the fuselage isn't necessarily significantly reducing the loads on the longerons and stringers. The wider fuselage is going to be heavier and therefore increase loading on stringers and therefore increase their size, unless the bending is changing the loading so much at a specific length. How do you come to the conclusion that this is at 35 rows? The benefit of a wider fuselage is that more seats can be installed per row which results in a shorter airplane. A wider fuselage that doesn't make the airplane any shorter increases weight.



I find it very very strange that you propose that a wider single aisle adding 10 inches will reduce the weight of an airplane, but adding an additional 18 inches and making the airplane a widebody at 7 abreast is inefficient. I don't see the logic or engineering behind your idea of a structurally efficient extra wide narrowbody. It doesn't make sense to me.

Airbus has very talented engineering teams who know more about the design of fuselage structure than anyone on this forum, so I am confident they would come up with the most optimized design and I don't see the logic behind your proposal, but I'm not as smart as the Airbus engineers so I'll leave it up to them.

Hi Newbie if a fuselage has a 10 inch wider fuselage, the same loads have a longer arms which leads to lower stains. It improves area moment of inertia of an aircraft fuselage cross section. Alternative you can lower the dimensions of fuselage structure and skin (weight saving) or e.g. make the fuselage longer and stay within the allowed load envelope. A bigger (average) radius helps to the fourth power improving Polar moment of inertia of a tube leaving room for weight reduction if the load stays ~ the same. Which is the case if e.g. a cabin stays 3-3 abreast + AKH container.
https://www.engineersedge.com/imagefiles/polar-moment-of-inertia.png



Of course there are other loads the fuselage has to take, but those are often more limiting factors for widebodies, that can theoretical have thin skins from a bending standpoint but still need to withstand e.g. hail & scrapnel loads
.

not sure i'm in right topic...

what airbus need to do is admit they are now wrong in choosing fuselage size for widebodies.

A350 is a perfect big wing with 787 fuselage
330NEO is a 787 size plane (for now, not about 1990) with less capacity.

what they have to do is a change a cross-section.
Can they change 350 to 77X size? hardly to imagine, mostly by human nature.
can they switch 330 to some 767 style? no (and NO MoM from 330)

but they can refresh 330 like 777x style.
expanding inner width with same outer and try to fight B on they own field.
something like 528=>543sm inner width with same 564 outer, leaving 21sm for structure (comparing to 23sm for 777x)


new wing can be a next step (after new wing for 321)

keesje wrote:

Hi Newbie if a fuselage has a 10 inch wider fuselage, the same loads have a longer arms which leads to lower stains. It improves area moment of inertia of an aircraft fuselage cross section. Alternative you can lower the dimensions of fuselage structure and skin (weight saving) or e.g. make the fuselage longer and stay within the allowed load envelope. A bigger (average) radius helps to the fourth power improving Polar moment of inertia of a tube leaving room for weight reduction if the load stays ~ the same. Which is the case if e.g. a cabin stays 3-3 abreast + AKH container.
https://www.engineersedge.com/imagefiles/polar-moment-of-inertia.png



Of course there are other loads the fuselage has to take, but those are often more limiting factors for widebodies, that can theoretical have thin skins from a bending standpoint but still need to withstand e.g. hail & scrapnel loads
.

How is anything that you posted relevant to your comment "A 10 inch wider fuselage also does wonders for structural efficiency / weight when going beyond 35 seat rows." What is special about 35 rows to make a wider fuselage more structurally efficient?

In one post you say widebodies can't compete with narrowbodies in efficiency. Then in another you say that current narrowbodies are too narrow and need to be wider to be more efficient. You seem to have decided that 178 inches is some magic number, yet provide no analysis why.

I understand how a beam works, but not how you are coming up with numbers showing that 178 inches is the ideal diameter for a plane that is 55 meters long. Why is 178 inches better than 196 inches or 164 inches? Nothing that you posted backs up the claim that 178 inch diameter fuselage will be lighter than a 164 inch fuselage since it is all theory. Going on the wider is better motif, why not make the airplane a 7 abreast widebody that is 196 inches wide?

What keesje is trying to say is that the longerons could be lighter if the tube diameter is increased. The greater diameter tube will be able to resist bending easier.

What he doesnt realise is the extra material in each frame and the skin itself adds more weight/load to the longerons.

So they both cancel each other out and the longerons will probably end up being similar in size and weight.

But at the end of the day the frames and skin will be heavier. So the overall tube will be heavier. You will also get a drag penalty. So that extra 10inch of aisle will only ever have a negative effect on fuel burn and range. My weight modelling spreadsheet clearly shows this.

The vast majority of the time the reason you would go with a wider fuselage is if you can fit more seats in the width. That means a shorter fuselage and in some cases that can completely offset any weight gain. You can't make it shorter if you only made the aisle wider.

There will be points where a fuselage becomes too long and skinny. So you will go from 4AB to 5AB to 6AB and from 8AB to 9AB to 10AB.

However with the rules of max 3 seats from and aisle and minimum aisle widths 7AB is fairly unique adding an extra aisle for only one seat.

My modelling shows you would be better off staying with 6AB and making it longer (757-300) or going straight to 8AB and making it shorter (A310). 7AB should be completely skipped if you want to extract every bit of performance out of a design.

What he is saying that with any tube like structure you get to a point (length) where the diameter starts to work against you in carrying the stresses.

This is where a wider diameter becomes beneficial.

This is often known as the fineness ratio (or similar) and it is what the A340-600 was bumping up against. It was at the very limits of the length that could be used for that diameter of tub - without making the tube itself so much stronger that the weight of doing so becomes counter productive.

Talk is cheap, Airbus doesn't have an airplane to compete with the B797! If they did? They would announce it just like Boeing has said they'll be building a new airplane. All of this airbus is going to do this and that is A BUNCH OF BULL !! Everybody already knows who's going to DO what and who's going to Buy what! The airlines that are A321 customers may or may NOT buy the B797. and those that aren't might sure buy the B797. But even when they get together the architecture for the B797?? They might just go Hi Tech with the B757 because BOTH were superior airplanes. in heir own right. And airlines that have them? Are keeping them for as long as they can..

https://www.flightglobal.com/news/artic ... th-443696/

Joyce is saying BA does not have a AC to compete against the 321LR and ,being a customer he is excited to work with them so they will. No customer wants to be in single source situation.

I realize all the fcf posts got deleted and before this one does let me just say why fcf relates to this thread. high fcf allows you to invest in RD and new AC development. Boeing with much higher fcf has the capability to look at a new AC. AB on the other hand needs the 350 and 321new and especially LR versions to build fcf. Nothing builds fcf like pricing power. Boeing has enjoyed pricing power with the 777 and the fcf #'s over the past 5 years are a testament to this.

in the 321LR AB has a FCF monster!

Amiga500 wrote:

Yeah, that was doing the rounds a few years back too, but how realistic are 16.5" seats?

For reference, the BAe 146 has - Floor width: 3.24m, shoulder width: 3.42m
The CSeries has - Floor width: 3.10m, shoulder width: 3.28m


How many operated the 146/RJ with 6 a-breast?

It would be totally unrealistic for a flight over one hour. Going from 8ab to 9ab or 9ab to 10ab is a much smaller increase percentage wise than going from 5ab to 6ab. Even by Air Asia's standards it would be tight with skinny arm rests. Though they might be the first to do it for short regional flights.

I looked at the idea with my CS100 turboprop proposal for an ultra short haul, high CASM 150 seater. There are thousands of jets flying trips under 500nm every day.

Well, if Qantas are looking for something to compete against the 321LR, Boeing's 260+ seat twin aisle NMA isn't going to be much help.

The biggest problem for Airbus will be having suitable engines.

If Boeing goes with a full carbon 8AB MOM it will probably be fairly light with a 150T MTO. Engine thrust would be around 45,000lb.

A shortened smaller wing A330 would struggle to get down to 150T MTO. The Airbus model would ideally need more thrust. So to use the same engines the A330 version would either need to have approx 20% less range at the same capacity or be shrunk to have 20% less capacity with the same range.

The A310-400NEO, A330-700NEO or whatever you want to call it would be cheaper to develop and produce. It would keep Boeing honest and mainly compete on price.



Picture from keesje

Based on 767-200 non-ER max TO weight and engine thrust, I'd think a 150 ton MOM would need at least 50,000 lb engines unless the wing area is substantially larger than the 767's 3050 sq ft (which of course would add more weight)

RJMAZ wrote:

If Boeing goes with a full carbon 8AB MOMe

Considering a short/medium haul aircraft spend most of its time on the ground I'm not sure if a high tech highly expensive aircraft is a good solution.

Newbiepilot wrote:

How is anything that you posted relevant to your comment "A 10 inch wider fuselage also does wonders for structural efficiency / weight when going beyond 35 seat rows."

SCAT15F wrote:

Based on 767-200 non-ER max TO weight and engine thrust, I'd think a 150 ton MOM would need at least 50,000 lb engines unless the wing area is substantially larger than the 767's 3050 sq ft (which of course would add more weight)

762 is 142T with 48,000lb of thrust allowing a very short 1900m takeoff run. Derated takeoff for 2500m takeoff run needs only 42,000lb of thrust.

A310-200 is 144T with 45,800lb using JT9D's

A300-200 Is 165T with 51,800lb of thrust.

So 45,000lb would be about right for 150T and a 2500m takeoff run. You probably don't want to over wing or over engine the aircraft just to get a shorter takeoff run. That just creates more weight to carry on short sectors.

The 737-900ER and 767-400ER have the lowest thrust to weight ratio and if scaled to 150T its only 43,000lb of thrust.

RJMAZ wrote:

The 737-900ER and 767-400ER have the lowest thrust to weight ratio and if scaled to 150T its only 43,000lb of thrust.

The -900 has a pretty bad rep for take-off field length though doesn't it?

So with weight growth allowances, you'd likely be looking for 45k lbf to be the lower bound of your engines.

Amiga500 wrote:

RJMAZ wrote:

The 737-900ER and 767-400ER have the lowest thrust to weight ratio and if scaled to 150T its only 43,000lb of thrust.

The -900 has a pretty bad rep for take-off field length though doesn't it?

So with weight growth allowances, you'd likely be looking for 45k lbf to be the lower bound of your engines.

Mostly that is lack of rotation angle due to stubby legs and long body.

StTim wrote:

Amiga500 wrote:

RJMAZ wrote:

The 737-900ER and 767-400ER have the lowest thrust to weight ratio and if scaled to 150T its only 43,000lb of thrust.

The -900 has a pretty bad rep for take-off field length though doesn't it?

So with weight growth allowances, you'd likely be looking for 45k lbf to be the lower bound of your engines.

Mostly that is lack of rotation angle due to stubby legs and long body.

Ah, OK.

RJMAZ wrote:

My modelling shows you would be better off staying with 6AB and making it longer (757-300) or going straight to 8AB and making it shorter (A310). 7AB should be completely skipped if you want to extract every bit of performance out of a design.

Good post! And that last sentence is exactly why so many are sceptical about the whole thing.

(Oh no, I forgot, magic CFRP will make it work... Heh heh!)

Maybe 10-abreast is the answer.... I dare ye Boeing

http://www.icas.org/ICAS_ARCHIVE/ICAS20 ... RS/152.PDF

[I'd f___ing love to see this!]

SomebodyInTLS wrote:

RJMAZ wrote:

My modelling shows you would be better off staying with 6AB and making it longer (757-300) or going straight to 8AB and making it shorter (A310). 7AB should be completely skipped if you want to extract every bit of performance out of a design.

Good post! And that last sentence is exactly why so many are sceptical about the whole thing.

(Oh no, I forgot, magic CFRP will make it work... Heh heh!)

I don’t think anyone believes it will be 7 across. If they build it it almost has to be 8 which is a good size and makes a lot of sense.

@keesje, your idea is good, but the range should be about 4,900 - 5,000nm pax + bags. This way, the aircraft won't be subject to any limitations due to unfavourable winds when flying westbound Western/Central Europe to East Coast North America during wintertime.

...and will easily beat what boeing will offer, economy-wise.

BlueSky1976 wrote:

@keesje, your idea is good, but the range should be about 4,900 - 5,000nm pax + bags. This way, the aircraft won't be subject to any limitations due to unfavourable winds when flying westbound Western/Central Europe to East Coast North America during wintertime.

@BlueSky1976, maybe. It would be an entirely new design, probably succeeding the A330s, 767s, 788 in many medium haul roles. It would be a new family with diffferent payload- range options in the mid market segment. A shorter, more range version could evolve. It's more about the concept than zooming in on details. Overspecifications should be avoided though, it risks making aircraft heavy and expensive to fill niches not worth the effort.

RJMAZ wrote:

The biggest problem for Airbus will be having suitable engines.

If Boeing goes with a full carbon 8AB MOM it will probably be fairly light with a 150T MTO. Engine thrust would be around 45,000lb.

A shortened smaller wing A330 would struggle to get down to 150T MTO. The Airbus model would ideally need more thrust. So to use the same engines the A330 version would either need to have approx 20% less range at the same capacity or be shrunk to have 20% less capacity with the same range.

The A310-400NEO, A330-700NEO or whatever you want to call it would be cheaper to develop and produce. It would keep Boeing honest and mainly compete on price.

Chances of Airbus responding with a completely new widebody aircraft are pretty small, and would be the wrong move IMO.

Instead, Airbus should stretch the A321 (as the Reuters article suggests) and put a new wing and powerplant on the entire A320/A321/A322 family. Not only the investment costs will be much lower, the new family will cover both narrowbody and MOM markets. As long as Boeing focuses heavily on the development of its new MOM aircraft, it won't be able to address the 737 successor.