I did some more calcs - in a two class Cabin wetted area is about 9% better and internal volume about 2% less with equivalent capacity up front and in the back.

From the AVWeek article - the rumour or what Boeing said is that it is a 2 class aircraft.

The main barrel is about 20%(also about 20') less in length meaning fewer ribs but those ribs are about 10% more in circumference and then beams are wider/more complex. All in all with the 9% less skin the weight for the fuselage should be in the same ballpark.

About 30% fewer containers in the bottom (taking into account the Wingbox - but each would hold 45-50% more.

[quote="morrisond"]I just redid the wetted area calcs. The 2x3x2 has about 1% less wetted area than a potential A322 (A321 plus two rows) assuming all Y of similar capacity.

I posted this a year or two ago in a different thread, but I have Boeing data on the 737NG and there is no difference in fuel burn, to the single digit, between the 737-700 and 800,
despite the ~20 foot longer fuselage of the 800, when the two are the same weight. This is true at any weight and altitude. In other words, Boeing flight test data saw no increase
in fuel burn with the longer fuselage, so there apparently is no measurable increase in drag. Put yet a different way, a fatter but shorter 2-2-2 or 2-3-2 fuselage with the same wetted
area as a 3-3 stretch is going to have more drag due to it's greater form drag as you (apparently) can't use wetted area in drag calculations with fuselages. Always been curious
about this since I saw the raw numbers 17 years ago (and rerunning them every so often to make sure I wasn't seeing things) but I think once the nose pushes the air out of the way,
the air stays out of the way as it tumbles along the boundary layer, until it gets to it's next obstacle, be it antennas, the tail(s), the inward taper...

Happy to be proven it's just a 737 thing and other configurations don't follow that rule, but I very much doubt it is just a 737 thing.

AvgWhiteGuy wrote:

morrisond wrote:

I just redid the wetted area calcs. The 2x3x2 has about 1% less wetted area than a potential A322 (A321 plus two rows) assuming all Y of similar capacity.

I posted this a year or two ago in a different thread, but I have Boeing data on the 737NG and there is no difference in fuel burn, to the single digit, between the 737-700 and 800,
despite the ~20 foot longer fuselage of the 800, when the two are the same weight. This is true at any weight and altitude. In other words, Boeing flight test data saw no increase
in fuel burn with the longer fuselage, so there apparently is no measurable increase in drag. Put yet a different way, a fatter but shorter 2-2-2 or 2-3-2 fuselage with the same wetted
area as a 3-3 stretch is going to have more drag due to it's greater form drag as you (apparently) can't use wetted area in drag calculations with fuselages. Always been curious
about this since I saw the raw numbers 17 years ago (and rerunning them every so often to make sure I wasn't seeing things) but I think once the nose pushes the air out of the way,
the air stays out of the way as it tumbles along the boundary layer, until it gets to it's next obstacle, be it antennas, the tail(s), the inward taper...

Happy to be proven it's just a 737 thing and other configurations don't follow that rule, but I very much doubt it is just a 737 thing.

Interesting. It could be something do with Aero and the fact that the -700 fuselage is stubby or having the tail back further on 800 is benefit - Maybe out of the turbulent airflow coming off the wing. Or the longer Fuselage on the 800 hides the Vertical stabilizer due to the aircraft flying at a slight up angle in normal cruise. Or the longer fuselage on the 800 generating more lift which means less drag from the wing. Does the same relationship hold with the 900?

I found a number of references that the Fuselage provides about 10% of lift on a Modern Airliner. A -800 is about 10' longer in the front or about 20% - meaning maybe another 2% of lift - not insignificant and I am sure there are many tradeoffs.

Opus99 wrote:

seahawk wrote:

3-3 is not what Boeing is going for. 2-3-2 with 16.5" seats and 18" aisles is a more than competitive solution when using modern design and production technology. Boeing wants to attack a completely untaken section of the market and they will delivery a twin aisle with single aisle operating costs, which will be a revolution.

And that’s what I’m thinking! Twin aisle at single aisle operating costs. If they can do that? Then that would take the cake. Is it possible? Though? You would’ve have higher weight and more crew so more expensive by default? But at least comparable to single aisle should be the target.

And who should achieve this if not Boeing? In the end the wider fuselage also contributes additional lift and the shape allows for more lift generated by the fuselage will even improve the efficiency. Imho this will work, all it takes are some slightly smaller seats in cattle class, which will be more than compensated for by much nicer seating in Premium economy and business class.

seahawk wrote:

Opus99 wrote:

seahawk wrote:

3-3 is not what Boeing is going for. 2-3-2 with 16.5" seats and 18" aisles is a more than competitive solution when using modern design and production technology. Boeing wants to attack a completely untaken section of the market and they will delivery a twin aisle with single aisle operating costs, which will be a revolution.

And that’s what I’m thinking! Twin aisle at single aisle operating costs. If they can do that? Then that would take the cake. Is it possible? Though? You would’ve have higher weight and more crew so more expensive by default? But at least comparable to single aisle should be the target.

And who should achieve this if not Boeing? In the end the wider fuselage also contributes additional lift and the shape allows for more lift generated by the fuselage will even improve the efficiency. Imho this will work, all it takes are some slightly smaller seats in cattle class, which will be more than compensated for by much nicer seating in Premium economy and business class.

I'm sure Airbus is quite capable of something like this as well. You would have to guess they have teams working on advanced fuselage shapes - or should have been ever since 2011 when NSA was rumoured to be an ovalish 2x3x2.

I suspect with the right tools this is not that hard of an engineering challenge.

Look at Keesje's Post #492 in this thread - an A400M cross section is not that far off what is rumoured for NMA. viewtopic.php?t=1027711&start=450

morrisond wrote:

seahawk wrote:

Opus99 wrote:

And that’s what I’m thinking! Twin aisle at single aisle operating costs. If they can do that? Then that would take the cake. Is it possible? Though? You would’ve have higher weight and more crew so more expensive by default? But at least comparable to single aisle should be the target.

And who should achieve this if not Boeing? In the end the wider fuselage also contributes additional lift and the shape allows for more lift generated by the fuselage will even improve the efficiency. Imho this will work, all it takes are some slightly smaller seats in cattle class, which will be more than compensated for by much nicer seating in Premium economy and business class.

I'm sure Airbus is quite capable of something like this as well. You would have to guess they have teams working on advanced fuselage shapes - or should have been ever since 2011 when NSA was rumoured to be an ovalish 2x3x2.

I suspect with the right tools this is not that hard of an engineering challenge.

Look at Keesje's Post #492 in this thread - an A400M cross section is not that far off what is rumoured for NMA. viewtopic.php?t=1027711&start=450

You can not compare the A400, as the cargo floor needs to be very strong for the loads it has to carry, that is not the same challenge as making the cabin floor on an airliner.

seahawk wrote:

morrisond wrote:

seahawk wrote:

And who should achieve this if not Boeing? In the end the wider fuselage also contributes additional lift and the shape allows for more lift generated by the fuselage will even improve the efficiency. Imho this will work, all it takes are some slightly smaller seats in cattle class, which will be more than compensated for by much nicer seating in Premium economy and business class.

I'm sure Airbus is quite capable of something like this as well. You would have to guess they have teams working on advanced fuselage shapes - or should have been ever since 2011 when NSA was rumoured to be an ovalish 2x3x2.

I suspect with the right tools this is not that hard of an engineering challenge.

Look at Keesje's Post #492 in this thread - an A400M cross section is not that far off what is rumoured for NMA. viewtopic.php?t=1027711&start=450

You can not compare the A400, as the cargo floor needs to be very strong for the loads it has to carry, that is not the same challenge as making the cabin floor on an airliner.

No - but in an Airliner you get the bottom which has to support the Cargo plus the Beam midway through the cross section to support the passengers. Non- round shapes are possible and have been done for a long time.

flyinggoat wrote:

The double circle idea is nothing new, and it's the sort of design I assumed Boeing was thinking when all the talk of an "oval" fuselage was starting. Many military cargo aircraft use this design. C-5, C-17, An-124, An-225, C-295, A-400M, C-390 etc all have flattened bellies. That being said, the C5, AN-124, AN-225 have the upper decks, so I think the overall height of the pressure vessels is still greater than the width, so the floors would still be in tension. The C-17, C-295, and A-400M appear to be wider than they are tall, which, from what I gather in this thread, means the floor is in compression. Does the fact that these are military transports designed to carry heavy equipment mean the floors are capable of handling the compression forces more than a passenger aircraft with underfloor cargo space? Or, am I missing something here?

The proposed TU-304 (Later called the Frigate Freejet) was a triple aisle wide body with a oval fuselage as well.

I'm not sure if I'm on the right track here, but I don't know that I'd be so quick to rule out the double circle type fuselage that has been proposed.

AN 124, AN 225 are nearly unpressurized (250mBar diff pressure ) hold.
C17, A400m, C130, C160 have / had more or less circular pressure vessels. ( hold and the outside may appear differrent.
C97 had double circle with the middle floor carrying the tension to keep the shape.

url: http://2.bp.blogspot.com/_eqb8qL2GKZc/S ... 9rQRjHNYc/
like that image

morrisond wrote:

seahawk wrote:

morrisond wrote:

I'm sure Airbus is quite capable of something like this as well. You would have to guess they have teams working on advanced fuselage shapes - or should have been ever since 2011 when NSA was rumoured to be an ovalish 2x3x2.

I suspect with the right tools this is not that hard of an engineering challenge.

Look at Keesje's Post #492 in this thread - an A400M cross section is not that far off what is rumoured for NMA. viewtopic.php?t=1027711&start=450

You can not compare the A400, as the cargo floor needs to be very strong for the loads it has to carry, that is not the same challenge as making the cabin floor on an airliner.

No - but in an Airliner you get the bottom which has to support the Cargo plus the Beam midway through the cross section to support the passengers. Non- round shapes are possible and have been done for a long time.

Sure and I am sure Boeing will do this and they will make it work.

If you do it in CFRP you don't need to have a pure circular shape. Look at the A350 diameter, steep sidewalls. The NMA would be the same. I don't see this double bubble come back.
BTW DC-8, DC-9 and 707, 727 had it as well.

The A400M is way too wide for what is needed here. Not even close.

Taxi645 wrote:

WIederling wrote:

flipdewaf wrote:

He may say it a lot but it’s clear that the civil air transport market is a mature , almost completely fungible one. Would a company say there needed to be market differentiation if it weren’t needed? I’d wager they would.

Calhoun needs to find a solution for copying the "A321 solution space" without people noticing they buy an embelished copy.
( They actually worked that rather well with the 787. )

And doing so while not looking like they copied the MC-21 either...

Boeing needs to worry about capacity, range, operating costs, etc. Just about everything, probably even the galley sink, matter more than whether it "looks like a copy" of a roughly cylinder shaped fuselage with swept wings and two engines.

WIederling wrote:

I do wonder if they intend to work their magic via the same SonicCruiser conversion to Dreamliner gambit.
All that flashy MOM, NMA, ... "taste" projected onto a me too product.

That's a possibility. I assumed at the time the NMA was put on hold that the outcome of the review they were doing would result in whatever was relevant of the work done so far for the NMA transitioning to an NSA program. I'm skeptical they have made up their mind yet, though.

Opus99 wrote:

seahawk wrote:

3-3 is not what Boeing is going for. 2-3-2 with 16.5" seats and 18" aisles is a more than competitive solution when using modern design and production technology. Boeing wants to attack a completely untaken section of the market and they will delivery a twin aisle with single aisle operating costs, which will be a revolution.

And that’s what I’m thinking! Twin aisle at single aisle operating costs. If they can do that? Then that would take the cake. Is it possible? Though? You would’ve have higher weight and more crew so more expensive by default? But at least comparable to single aisle should be the target.

That would only work for a while until Airbus comes up with Large Narrowbody that would have operating costs way lower compared to NMA.

Boeing can't future proof their widebody to compete with next generation narrowbody.

AvgWhiteGuy wrote:

morrisond wrote:

I just redid the wetted area calcs. The 2x3x2 has about 1% less wetted area than a potential A322 (A321 plus two rows) assuming all Y of similar capacity.

I posted this a year or two ago in a different thread, but I have Boeing data on the 737NG and there is no difference in fuel burn, to the single digit, between the 737-700 and 800,
despite the ~20 foot longer fuselage of the 800, when the two are the same weight. This is true at any weight and altitude. In other words, Boeing flight test data saw no increase
in fuel burn with the longer fuselage, so there apparently is no measurable increase in drag. Put yet a different way, a fatter but shorter 2-2-2 or 2-3-2 fuselage with the same wetted
area as a 3-3 stretch is going to have more drag due to it's greater form drag as you (apparently) can't use wetted area in drag calculations with fuselages. Always been curious
about this since I saw the raw numbers 17 years ago (and rerunning them every so often to make sure I wasn't seeing things) but I think once the nose pushes the air out of the way,
the air stays out of the way as it tumbles along the boundary layer, until it gets to it's next obstacle, be it antennas, the tail(s), the inward taper...

Happy to be proven it's just a 737 thing and other configurations don't follow that rule, but I very much doubt it is just a 737 thing.

That would make the case that the most efficient twin aisle is a 2-2-2 versus a short 2-3-2 or 2-4-2, if the same capacity for all three.

morrisond wrote:

[ Does the same relationship hold with the 900?

I don't know, our airline didn't/doesn't have 900's so I couldn't put it into the computer.
I would strongly suspect it would, unless the drag from the extra doors cost it ~10 pph. Yet another reason stretches seem to prosper over their shorter siblings, no (measureable)
extra drag from the longer fuselage

DenverTed wrote:

That would make the case that the most efficient twin aisle is a 2-2-2 versus a short 2-3-2 or 2-4-2, if the same capacity for all three.

Yes, until the capacity gets to the point where the fuselage needs strengthening because it's getting too long and thin (A340-5/600). I'd hazard a guess that is around 235 seats
in a typical two class, ~4.1 meter inner-diameter aluminum tube layout, but it's purely a guess.

I've said this before, but my money is on a wide-isle, 18.5" seats, 3-3 configuration. The problem (now) is, that seems to be right where the MC-21 is. One more thing for Boeing
to make look like they didn't copy.

But it would give Boeing total control of a completely uncovered market segment. The technology will also apply to the NSA which will then take command of the single aisle market.

The thing is, you can not have single aisle operating cost with two aisle. That is physically not possible. Under the assumption you have all the tech available and can choose your product, the moment one gets bigger than the other you need more material, what makes the frame heavier, what leads to bigger wings and engines, what makes the frame heavier, what leads to stronger gears, what makes the frame heavier, etc.

So from the moment you add volume you also add weight. Now of course the additional volume allows for additional seats to spread the cost, but your operational costs will be higher.
So an empty 2-3-2 aircraft will be more expensive to fly than an empty 3-3 aircraft if both are at the same tech level.

If the 2-3-2 should fly further then it will be even more at a disadvantage on direct competing routes.

Now if one thinks you can overcome that with an aircraft designed towards pure pax operation and just design as much cargo hold away as possible, that will make up a bit but it also reduces the sales potential in certain regions.

There is a reason that no aircraft sits between the A321 and 787-8 in size and even there the 787-8 is suboptimal. Regulations on seating configurations just make dead space super expensive to build for no gain thats why 3-4-3>3-3-3>2-4-2>2-3-2. Also everything that can not take the containers avialable now is by design a failure. Cargo will not change, not for decades. We still use the same containers on ships as ever (thats how it seams, it is that long), and they fit on trucks as well. Same goes for Airfreight. The system is so interconnected, you can not move away from it anymore.

FluidFlow wrote:

The thing is, you can not have single aisle operating cost with two aisle. That is physically not possible. Under the assumption you have all the tech available and can choose your product, the moment one gets bigger than the other you need more material, what makes the frame heavier, what leads to bigger wings and engines, what makes the frame heavier, what leads to stronger gears, what makes the frame heavier, etc.

So from the moment you add volume you also add weight. Now of course the additional volume allows for additional seats to spread the cost, but your operational costs will be higher.
So an empty 2-3-2 aircraft will be more expensive to fly than an empty 3-3 aircraft if both are at the same tech level.

Yep.

But if Boeing goes with all the latest tech they can build a A321 killer (or at least somewhat better).

The risk is Airbus can come back with the same tech in an all new A322 6 across that kills the Boeing twin aisle thing - but that is unlikely and the bet Boeing would have to take.

A 6 abreast would never have the same capacity without being too long. It also has an inferior product with 100% more middle seats. Boeing needs to be daring and I think airlines are really wanting the MOM.

Some A322 sort of airplane is a sure bet to come. Very cheap and fast to do, just needs a new wing. Updates can be used for the rest of the A320-family.
Boeing's NMA needs to top this. By size, by volume, by upper end capacity. This will be the actual competition. However making it transpacific range would lead to too much weight. It must be cheap to built and sell.

seahawk wrote:

A 6 abreast would never have the same capacity without being too long. It also has an inferior product with 100% more middle seats. Boeing needs to be daring and I think airlines are really wanting the MOM.

So Boeing wants more capacity? Calhoun said he targets the A321XLR capacity. We are talking here about a 3-3 240 single class against a 2-3-2 240 single class variant. Everything else is Apples and Oranges.

If Boeing wants to build a 280 single class aircraft, that is something totally different. Of course it will also have drawbacks, as it will be 20-30t heavier than a 240, especially if it needs to be able fly 4500nm. That will make it very uncompetitive again on sub 3000nm missions what will reduce the potential sales a lot even compared to the MAX-10.

The A321 is a very mediocre solution for the targeted market. It does not have the range, the cabin comfort or the capacity to successfully open and grow new point-to-point connections. Airlines want an more versatile aircraft, that will give them the right tool to right size the capacity on medium to long routes. That is what the MOM family will successfully do and that is why airlines are eager for Boeing to launch.

seahawk wrote:

The A321 is a very mediocre solution for the targeted market. It does not have the range, the cabin comfort or the capacity to successfully open and grow new point-to-point connections. Airlines want an more versatile aircraft, that will give them the right tool to right size the capacity on medium to long routes. That is what the MOM family will successfully do and that is why airlines are eager for Boeing to launch.

So Boeing wants a versatile aircraft or a specialised aircraft? In my opinion, the A321 is versatile. You can use it on BOS-JFK and on BOS-LHR as it is on both routes very efficient. Now what does Boeing want? A321 capacity and more range (so a heavier aircraft) and give up the short routes? Or does Boeing want more capacity and more range? So no competitor for the A321 and an aircraft in a different size class?

We actually do not know and I do not think Boeing found the solution either.

Or they did and will follow Calhouns words, and he said to target the A321 market. So an aircraft that is good on very short routes as well as medium routes, with around 100t take off weight and around 240 seats single class.

Everything else is no competitor but rather an aircraft targeting a different market. Boeing is in the tricky situation to either launch a versatile aircraft that is good at everything (A321) but not outstanding, or a specialized aircraft that targets a specific market (777-8) and risks to fall short on sales but occupies a niche where there are no competitors.

What makes this worse is the extreme compromise Boeing seems to take by reducing cargo capability and choosing a weird shape that will limit future cargo conversions and a pure freighter version. The sole thing that kept the 767 alive. It was not the so comfortable 2-3-2, it was actually the perfect tube size for cargo operations combined with a relatively small wing. For pax operations the market moved on to the A330 and 2-4-2 as it is more efficient. Now if Boeing boxes itself into a hole by hampering cargo and launching a 2-3-2 that inherently has to much aisle per passenger they could end up in a hard place.

Launching a 3-3 180-240 NB familiy on the other hand guarantees sales far into the 2050s. Now if you are an investor and indirectly control of Boeing, or having other leverage due to the pure capitalist nature of business, what would you decide? A moonshot at an ominous MoM or a solid cash cow for 30 years?

seahawk wrote:

The A321 is a very mediocre solution for the targeted market. It does not have the range, the cabin comfort or the capacity to successfully open and grow new point-to-point connections. Airlines want an more versatile aircraft, that will give them the right tool to right size the capacity on medium to long routes. That is what the MOM family will successfully do and that is why airlines are eager for Boeing to launch.

I am not sure it is fair to describe a plane that got 500 orders in the first year mediocre. The market seems to tell that it is the right product at the right time...

"Mediocre" for the hottest seller on the market that Boeing has no answer to? If that's mediocre we need more of it.

FluidFlow wrote:

The thing is, you can not have single aisle operating cost with two aisle. That is physically not possible. Under the assumption you have all the tech available and can choose your product, the moment one gets bigger than the other you need more material, what makes the frame heavier, what leads to bigger wings and engines, what makes the frame heavier, what leads to stronger gears, what makes the frame heavier, etc.

So from the moment you add volume you also add weight. Now of course the additional volume allows for additional seats to spread the cost, but your operational costs will be higher.
So an empty 2-3-2 aircraft will be more expensive to fly than an empty 3-3 aircraft if both are at the same tech level.

If the 2-3-2 should fly further then it will be even more at a disadvantage on direct competing routes.

Now if one thinks you can overcome that with an aircraft designed towards pure pax operation and just design as much cargo hold away as possible, that will make up a bit but it also reduces the sales potential in certain regions.

There is a reason that no aircraft sits between the A321 and 787-8 in size and even there the 787-8 is suboptimal. Regulations on seating configurations just make dead space super expensive to build for no gain thats why 3-4-3>3-3-3>2-4-2>2-3-2. Also everything that can not take the containers avialable now is by design a failure. Cargo will not change, not for decades. We still use the same containers on ships as ever (thats how it seams, it is that long), and they fit on trucks as well. Same goes for Airfreight. The system is so interconnected, you can not move away from it anymore.

But a tight light 2 class 2x3x2 does not have more volume than a 3x3 when you adjust for similar capacity. The 2x3x2 actually has about 9% less skin and 2% less internal volume - that extra seat being basically in the bulge is a very efficient cost in volume - basically the decrease in length of the cabin more than offsets the increased width of a tight 2x3x2.. The penalty in aisle space is only about 1.4x for two 17" aisles vs one 19" aisle.

Boeing is calling it a 2 Class aircraft (according the AVWeek article). I think Boeing is seeing the writing on the wall and they know by the time this aircraft arrives COMAC could be a major player. They will have a very hard time competing with them for airlines that are all Y or Y-. An all Y NMA has about 1% less Skin and 6.5% more internal volume. They need to differentiate themselves as Calhoun has stated.

A 168x183" cross section gets you containers than can carry about 50% more than an LD3-45 offset by the reduced cabin length - so probably about 20-25% more cargo capacity than the 3x3.

AvgWhiteGuy wrote:

morrisond wrote:

[ Does the same relationship hold with the 900?

I don't know, our airline didn't/doesn't have 900's so I couldn't put it into the computer.
I would strongly suspect it would, unless the drag from the extra doors cost it ~10 pph. Yet another reason stretches seem to prosper over their shorter siblings, no (measureable)
extra drag from the longer fuselage

DenverTed wrote:

That would make the case that the most efficient twin aisle is a 2-2-2 versus a short 2-3-2 or 2-4-2, if the same capacity for all three.

Yes, until the capacity gets to the point where the fuselage needs strengthening because it's getting too long and thin (A340-5/600). I'd hazard a guess that is around 235 seats
in a typical two class, ~4.1 meter inner-diameter aluminum tube layout, but it's purely a guess.

I've said this before, but my money is on a wide-isle, 18.5" seats, 3-3 configuration. The problem (now) is, that seems to be right where the MC-21 is. One more thing for Boeing
to make look like they didn't copy.

An interesting data point would be an fuselage with a wider cross section but same wings/tail/engines at the same weight and whether or not the bigger the hole it punches in the air is more than the extra lift it produces - which theoretically could mean less drag from wings. It's probably not a huge difference one way or the other. I doubt the Fuselage is a large component of drag anyways compared to the engines/wings/tail.

FluidFlow wrote:

There is a reason that no aircraft sits between the A321 and 787-8 in size and even there the 787-8 is suboptimal.

I thought both the 767 and the A330-200 actually occupy that space and were fairly successful.

par13del wrote:

FluidFlow wrote:

There is a reason that no aircraft sits between the A321 and 787-8 in size and even there the 787-8 is suboptimal.

I thought both the 767 and the A330-200 actually occupy that space and were fairly successful.

The 788 and A332/A338 are the same size. But you are right that that the 767 is currently sitting there.

Polot wrote:

par13del wrote:

FluidFlow wrote:

There is a reason that no aircraft sits between the A321 and 787-8 in size and even there the 787-8 is suboptimal.

I thought both the 767 and the A330-200 actually occupy that space and were fairly successful.

The 788 and A332/A338 are the same size. But you are right that that the 767 is currently sitting there.

size wise :: approximate, smaller to larger:

762-200 | A310
767-300
767-400 |787-8
A330-200 | A330-800
787-9 | A330-300 | A330-900
787-10

( OK?)

AvgWhiteGuy wrote:

morrisond wrote:

I just redid the wetted area calcs. The 2x3x2 has about 1% less wetted area than a potential A322 (A321 plus two rows) assuming all Y of similar capacity.

I posted this a year or two ago in a different thread, but I have Boeing data on the 737NG and there is no difference in fuel burn, to the single digit, between the 737-700 and 800,
despite the ~20 foot longer fuselage of the 800, when the two are the same weight. This is true at any weight and altitude. In other words, Boeing flight test data saw no increase
in fuel burn with the longer fuselage, so there apparently is no measurable increase in drag. Put yet a different way, a fatter but shorter 2-2-2 or 2-3-2 fuselage with the same wetted
area as a 3-3 stretch is going to have more drag due to it's greater form drag as you (apparently) can't use wetted area in drag calculations with fuselages. Always been curious
about this since I saw the raw numbers 17 years ago (and rerunning them every so often to make sure I wasn't seeing things) but I think once the nose pushes the air out of the way,
the air stays out of the way as it tumbles along the boundary layer, until it gets to it's next obstacle, be it antennas, the tail(s), the inward taper...

Happy to be proven it's just a 737 thing and other configurations don't follow that rule, but I very much doubt it is just a 737 thing.

But, the 800 fuselage weighs more. If the 700 and 800 have he same payload, what is the extra cost for fuel for a 3 hour flight? I suppose this determines whether WN will take -7s, or just take the savings in commonality and go with all -8.
I figure the fuselage is about 550lb/ft or 11,000lb. The 777-300ER weighed 50,000lb more than the 777-200LR, or about 1,500lb/ft. I'm surprised the LR was not more popular, especially on 6,000 mile routes where that extra fuselage weight would cost fuel.
I think the conclusion is that longer proportioned aircraft are well worth the fuselage weight for the extra volume and floor space.
With the -700 having a length/width ratio of 9, I doubt we will see any aircraft under 10 in the future. Especially with larger fan engines with taller gear, longer fuselages make sense.

WIederling wrote:

Polot wrote:

par13del wrote:

I thought both the 767 and the A330-200 actually occupy that space and were fairly successful.

The 788 and A332/A338 are the same size. But you are right that that the 767 is currently sitting there.

size wise :: approximate, smaller to larger:

762-200 | A310
767-300
767-400 |787-8
A330-200 | A330-800
787-9 | A330-300 | A330-900
787-10

( OK?)

The issue was whether any plane sat in the space between the A321 and the 788, so perhaps placing the A321 on the list would be more helpful, but I defer this one and move on.

I think too many people focus too much on a certain capacity rather considering that you actually are targeting a market, not a capacity. If a slightly smaller plane has the range and the cost is low enough, the market will accept it anyway.

seahawk wrote:

The A321 is a very mediocre solution for the targeted market. It does not have the range, the cabin comfort or the capacity to successfully open and grow new point-to-point connections. Airlines want an more versatile aircraft, that will give them the right tool to right size the capacity on medium to long routes. That is what the MOM family will successfully do and that is why airlines are eager for Boeing to launch.

The A321 maybe, but a A322, with more capacity, a higher MOTW and new much more efficient wing with more fuel volume and A320 production line cost could very well be good enough for a large part of that market given it's low acquisition cost. A Boeing MC-21 look-a-like would do even better on the cabin comfort front, but then again, you considered 3 inches extra width at head level irrelevant, only extra aisles matter I guess...

Taxi645 wrote:

A Boeing MC-21 look-a-like would do even better on the cabin comfort front, but then again, you considered 3 inches extra width at head level irrelevant, only extra aisles matter I guess...

a worthless feature. we've been educated endlessly that more space ~higher comfort is irrelevant. 737 is perfect.

seahawk wrote:

The A321 is a very mediocre solution for the targeted market. It does not have the range, the cabin comfort or the capacity to successfully open and grow new point-to-point connections. Airlines want an more versatile aircraft, that will give them the right tool to right size the capacity on medium to long routes. That is what the MOM family will successfully do and that is why airlines are eager for Boeing to launch.

The reason the A321 is a mediocre solution for the target market is that its as cheap as chips and common with probably the biggest jet family out there, which makes it incredibly verdsatile.
Which is why its selling by the thousands, and why deliveries went UP in 2020 in contrast to EVERY other aircraft type.
Those are the currencies that airlines want.
It's us that want the bells and whistles I suspect......

Rgds

... if god wanted single aisle wider than 737 he would 737 wider...

FluidFlow wrote:

So Boeing wants a versatile aircraft or a specialized aircraft? In my opinion, the A321 is versatile. You can use it on BOS-JFK and on BOS-LHR as it is on both routes very efficient. Now what does Boeing want? A321 capacity and more range (so a heavier aircraft) and give up the short routes? Or does Boeing want more capacity and more range? So no competitor for the A321 and an aircraft in a different size class?

Assuming NMA-5X is real, Boeing would be using specialized frames to provide versatility: 737-10 for short-haul and NMA-5X for long-haul.

Yes, it's inelegant, but it does give Boeing differentiation from the A321-200XLR while providing versatility. Of course, the A321XLR can do both (though perhaps not as efficiently on short-haul nor as effectively on long-haul), but that versatility is why I don't see Boeing doing any significant damage to the model's success - it will just help Boeing start to claw back from it's ~25% market share in the 220-240 seat segment.


(NMA-6X and NMA-7X play in a different market from the A321)

Armadillo1 wrote:

... if god wanted 'a' single aisle wider than 737 he would 'have made the' 737 wider...

That made me laugh. Thank you for the moment of levity!

ewt340 wrote:

Boeing can't future proof their widebody to compete with next generation narrowbody.

That's the 200-250pax question isn't it?

morrisond wrote:

FluidFlow wrote:

The thing is, you can not have single aisle operating cost with two aisle. That is physically not possible. Under the assumption you have all the tech available and can choose your product, the moment one gets bigger than the other you need more material, what makes the frame heavier, what leads to bigger wings and engines, what makes the frame heavier, what leads to stronger gears, what makes the frame heavier, etc.

So from the moment you add volume you also add weight. Now of course the additional volume allows for additional seats to spread the cost, but your operational costs will be higher.
So an empty 2-3-2 aircraft will be more expensive to fly than an empty 3-3 aircraft if both are at the same tech level.

If the 2-3-2 should fly further then it will be even more at a disadvantage on direct competing routes.

Now if one thinks you can overcome that with an aircraft designed towards pure pax operation and just design as much cargo hold away as possible, that will make up a bit but it also reduces the sales potential in certain regions.

There is a reason that no aircraft sits between the A321 and 787-8 in size and even there the 787-8 is suboptimal. Regulations on seating configurations just make dead space super expensive to build for no gain thats why 3-4-3>3-3-3>2-4-2>2-3-2. Also everything that can not take the containers avialable now is by design a failure. Cargo will not change, not for decades. We still use the same containers on ships as ever (thats how it seams, it is that long), and they fit on trucks as well. Same goes for Airfreight. The system is so interconnected, you can not move away from it anymore.

But a tight light 2 class 2x3x2 does not have more volume than a 3x3 when you adjust for similar capacity. The 2x3x2 actually has about 9% less skin and 2% less internal volume - that extra seat being basically in the bulge is a very efficient cost in volume - basically the decrease in length of the cabin more than offsets the increased width of a tight 2x3x2.. The penalty in aisle space is only about 1.4x for two 17" aisles vs one 19" aisle.

Boeing is calling it a 2 Class aircraft (according the AVWeek article). I think Boeing is seeing the writing on the wall and they know by the time this aircraft arrives COMAC could be a major player. They will have a very hard time competing with them for airlines that are all Y or Y-. An all Y NMA has about 1% less Skin and 6.5% more internal volume. They need to differentiate themselves as Calhoun has stated.

A 168x183" cross section gets you containers than can carry about 50% more than an LD3-45 offset by the reduced cabin length - so probably about 20-25% more cargo capacity than the 3x3.

So you compromise the optimal shape (now a sphere is the perfect shape, but for an aircraft it is more or less a circle) to not gain any volume just to have an aisle? Why would you do that if you no not want more seats? So if you aim at the same capacity then you do not need any special shape. The point is, that if you compare a 240 seats circle with a 240 seats ovoid (or whatever weird shape you go for), you only add complexity without any additional capacity. This does not help the case. To make it worth while you need to increase capacity what also needs more MTOW, what makes the design heavier.

And for the containers:
If it does not take LD3-45s it is dead in the water. There are billions invested in automated cargo systems that take LD3-45 (or the wide body version of the LD3 and LD2 containers). So no one will accept different shapes and sizes just because Boeing builds a strange shaped pax aircraft.
That means the shorter cabin would lead to actually less cargo capacity because you can carry less containers.
The only other option would than be to bulk load to use the wider cargo bay but that would make turn around times horrible because bulk loading long haul operations where we have more checked luggage would be a nightmare (operational).

Stitch wrote:

FluidFlow wrote:

So Boeing wants a versatile aircraft or a specialized aircraft? In my opinion, the A321 is versatile. You can use it on BOS-JFK and on BOS-LHR as it is on both routes very efficient. Now what does Boeing want? A321 capacity and more range (so a heavier aircraft) and give up the short routes? Or does Boeing want more capacity and more range? So no competitor for the A321 and an aircraft in a different size class?

Assuming NMA-5X is real, Boeing would be using specialized frames to provide versatility: 737-10 for short-haul and NMA-5X for long-haul.

Yes, it's inelegant, but it does give Boeing differentiation from the A321-200XLR while providing versatility. Of course, the A321XLR can do both (though perhaps not as efficiently on short-haul nor as effectively on long-haul), but that versatility is why I don't see Boeing doing any significant damage to the model's success - it will just help Boeing start to claw back from it's ~25% market share in the 220-240 seat segment.


(NMA-6X and NMA-7X play in a different market from the A321)

Well, it can become really elegant if they introduce an single aisle NMA, which later can be downscaled to an NSA with a different wingbox, wing and tail. This way they have 1 cockpit, tube and production method for the 150-300 seat segment.

A bit more out of the box would be downscaling the twin aisle NMA to the 150 seat segment. You would wind up with an stuby plane, but it would definitely be different and elegant.

Sort of a "B310"?

FluidFlow wrote:

morrisond wrote:

FluidFlow wrote:

The thing is, you can not have single aisle operating cost with two aisle. That is physically not possible. Under the assumption you have all the tech available and can choose your product, the moment one gets bigger than the other you need more material, what makes the frame heavier, what leads to bigger wings and engines, what makes the frame heavier, what leads to stronger gears, what makes the frame heavier, etc.

So from the moment you add volume you also add weight. Now of course the additional volume allows for additional seats to spread the cost, but your operational costs will be higher.
So an empty 2-3-2 aircraft will be more expensive to fly than an empty 3-3 aircraft if both are at the same tech level.

If the 2-3-2 should fly further then it will be even more at a disadvantage on direct competing routes.

Now if one thinks you can overcome that with an aircraft designed towards pure pax operation and just design as much cargo hold away as possible, that will make up a bit but it also reduces the sales potential in certain regions.

There is a reason that no aircraft sits between the A321 and 787-8 in size and even there the 787-8 is suboptimal. Regulations on seating configurations just make dead space super expensive to build for no gain thats why 3-4-3>3-3-3>2-4-2>2-3-2. Also everything that can not take the containers avialable now is by design a failure. Cargo will not change, not for decades. We still use the same containers on ships as ever (thats how it seams, it is that long), and they fit on trucks as well. Same goes for Airfreight. The system is so interconnected, you can not move away from it anymore.

But a tight light 2 class 2x3x2 does not have more volume than a 3x3 when you adjust for similar capacity. The 2x3x2 actually has about 9% less skin and 2% less internal volume - that extra seat being basically in the bulge is a very efficient cost in volume - basically the decrease in length of the cabin more than offsets the increased width of a tight 2x3x2.. The penalty in aisle space is only about 1.4x for two 17" aisles vs one 19" aisle.

Boeing is calling it a 2 Class aircraft (according the AVWeek article). I think Boeing is seeing the writing on the wall and they know by the time this aircraft arrives COMAC could be a major player. They will have a very hard time competing with them for airlines that are all Y or Y-. An all Y NMA has about 1% less Skin and 6.5% more internal volume. They need to differentiate themselves as Calhoun has stated.

A 168x183" cross section gets you containers than can carry about 50% more than an LD3-45 offset by the reduced cabin length - so probably about 20-25% more cargo capacity than the 3x3.

So you compromise the optimal shape (now a sphere is the perfect shape, but for an aircraft it is more or less a circle) to not gain any volume just to have an aisle? Why would you do that if you no not want more seats? So if you aim at the same capacity then you do not need any special shape. The point is, that if you compare a 240 seats circle with a 240 seats ovoid (or whatever weird shape you go for), you only add complexity without any additional capacity. This does not help the case. To make it worth while you need to increase capacity what also needs more MTOW, what makes the design heavier.

And for the containers:
If it does not take LD3-45s it is dead in the water. There are billions invested in automated cargo systems that take LD3-45 (or the wide body version of the LD3 and LD2 containers). So no one will accept different shapes and sizes just because Boeing builds a strange shaped pax aircraft.
That means the shorter cabin would lead to actually less cargo capacity because you can carry less containers.
The only other option would than be to bulk load to use the wider cargo bay but that would make turn around times horrible because bulk loading long haul operations where we have more checked luggage would be a nightmare (operational).

You excellently put in writing why I can't really get a grip of this thread.

Seemingly design decisions are thrown around as if suddenly typical constraints of tube & wing, aluminum and / or CFRP have materially changed.
Suddenly stubby planes are shown to be a good solution, when they traditionally have been awful from a revenue potential vs. cost perspective.
Suddenly comfort is a thing again, when neither the industry, nor the most important average consumer has shown any appetite to pay real cash for any amount of comfort improvement. Nobody in the real world is paying a dime more to fly A320 vs. 737, or A350 vs. 787 to gain an inch of seat width.
Suddenly we are advocating complex forms, disregarding basic requirements of material load distribution patterns or talking them down as being mitigated by "new materials". And those same complex forms are now suddenly heavily 3D-printed on a large industrial scale to not only enable those very forms, but to also bring production cost down so significantly, that it shall be one of the most important competitive advantages of the new plane.
And at the same time, we advocate using new, non-compatible containers or go back to the future via bulk loading.

I have my doubts.

The problem is the size and what size is Boeing actually talking about. Obviously you want more than version of the plane

240seats - 2 class is probably bigger than a A321 and more like 270-280 seats single class in a A321 (240 seats configuration). So about 757-300 size. The problem is, this is close to the upper limit for a single aisle and the lower limit for a twin aisle.

I think aside from the fuselage diameter and shape the intended range is way more critical as it defines the wing size, weight and such and market segment. That is really tricky to decide. Too much wing means too much weight but the A321XLR and bigger concepts seem to be hell bound for more range.

seahawk wrote:

A 6 abreast would never have the same capacity without being too long. It also has an inferior product with 100% more middle seats. Boeing needs to be daring and I think airlines are really wanting the MOM.

Indeed.
I haven't seen it quoted for quite some years however BA themselves used to say that they had learned their lesson from the 757-300 - "it was just too long"
(This is for RPT of course - the 753 seemed to work extremely well for non-sked Ops).

I joined an airline circa 1990 which was a very satisfied 767 operator.

When I queried why they had never used the 757, the answer was:

"Uneconomic. Carries 30-40 fewer passengers than the 767 but takes as long - OR LONGER to turn around".

Which is exactly the space into which an A322 would launch, as far as I can see.

cheers

.

FluidFlow wrote:

And for the containers:
If it does not take LD3-45s it is dead in the water. There are billions invested in automated cargo systems that take LD3-45 (or the wide body version of the LD3 and LD2 containers). So no one will accept different shapes and sizes just because Boeing builds a strange shaped pax aircraft.

Difficult to say.
If Boeing manages to convert their 737 bulk loading customers to containerized they might be able to introduce a new form factor.
compare the 767: it introduced the LD2/LD8 box afair ( where the A300 fit an existing box:LD3), a new box style.

Airbus NB introduced the LD3-45 type an adaption of the basic LD3. essentially a new type too.

All taken a new type or not may be dependent on the market Oompf Boeing can excert.

A new container is not much of a problem, as long as it is smaller than a LD6, which it will be.

brindabella wrote:

seahawk wrote:

A 6 abreast would never have the same capacity without being too long. It also has an inferior product with 100% more middle seats. Boeing needs to be daring and I think airlines are really wanting the MOM.

Indeed.
I haven't seen it quoted for quite some years however BA themselves used to say that they had learned their lesson from the 757-300 - "it was just too long"
(This is for RPT of course - the 753 seemed to work extremely well for non-sked Ops).

I joined an airline circa 1990 which was a very satisfied 767 operator.

When I queried why they had never used the 757, the answer was:

"Uneconomic. Carries 30-40 fewer passengers than the 767 but takes as long - OR LONGER to turn around".

Which is exactly the space into which an A322 would launch, as far as I can see.

cheers

.

You make a good point in general, I am just not sure how applicable it is in the MOM context.

Turn around times are less and less important the longer your average stage length gets. Lets be clear here, MOM won't be flying JFK - MIA, LHR - FRA or MAD - WAW anymore than todays large widebodies do. MOM will be flying MAN - PHL, MUC - PHX and the likes. Turn times won't be deal breakers here, as intercont flying has an inherent disadvantage in A/C usage during 24h to hit preferential departure times for consumers. If the 753 had reliable 5000NM over ground range even in unfavorable winds, it would be far more a plane busting hubs than 787 ever was. Not that I believe in busting hubs...

All this turnaround debate was had 20 years ago:

viewtopic.php?t=80027

Condor and LH proofed that you can turn around a 753 as fast as an A310. And that was without containers in the hold. If you are really in a hurry with a 753, you use a bus gate and stairs and the front and back.