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Polot
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 12:28 pm

RJMAZ wrote:
heavymetal wrote:
Polot is exactly correct here. The 757-300's lack of sales was a function of it's poor timing to market, not it's poor economics. Ask any of the carriers operating it - for the carriers that operate it, its one of, if not the, most profitable narrowbodies thanks to its great economics. I believe it would have outsold the 757-200 over the long run if given the opportunity, much like all of the other upgauge models. Unfortunately 9/11 sealed the 757 family's fate.

No, that is the biggest load of crap I've ever heard. The 757-300 was a desperate last gasp attempt by Boeing to keep the 757 line going. Sales for the 757 came to a dead stop in 1994 with 12 orders and another 13 orders in 1995. The introduction of the A321 in 1994 is what caused that dead stop. The 737-900 didn't help either.

The 757-300 was a last attempt in 1996 to improve CASM as the A321 could easily match the CASM of the 757-200.

That is 5 years before September 11. The coffin lid was already on and that simply added the last nail.

I doubt a 757-300 style modern version would sell very well today. Unless it could sell 1000+ frames its a bad idea.

Correlation does not equal causation.

Those 12 orders in '94 and 13 in '95 were immediately followed by 59 in '96, 44 in '97, and 50 in '98. Certainly not because of the 753, since only 55 total of those were sold, 39 of which were in 2000 and 2001. So maybe its time to rethink the whole A321 caused an immediate dead stop in 757 sales forcing Boeing to respond with a stretched 753? I'm not sure looking at two years in the mid 90s tells the whole story. It is not like the A321 was a hugely popular aircraft at first. You could probably just as equally argue that the 757's poor sales in 94/95 was a final side effect of the early 90s recession that resulted in precarious financial positions for many US airlines (the 757's biggest customers), and the collapse of a couple including EA, a 757 customer that provided the market with a source of used 757s.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 1:07 pm

Outside the vastly complex process of building these phenomenal machines ,the hardest job must be peering into the distant future and correctly guessing where and how the market will move.
The annual projections often look (to me) to be a marketing pissing exercise depending what A&B have to sell.When planning a new aircraft with the $10bn cheque attached they have to guess technically 10 years into the future just to build it but also a further 20 years so that the whole project makes a good return.That is difficult to put it mildly.
The market under discussion here has been largely ignored for many years (757/767/300/310).The gap has been getting smaller at one end with 230-240 seater aircraft such as the A321NEO NEO and now the B737-10 coming into the marketplace.But larger at the other end with smaller wide bodies getting ever heavier with longer ranges (A332 NEO and B787-8).

I suppose one way of looking at it would be if Boeing decided 'not' to launch a 250ish seat 4-5knm 797 for an EIS in 2027.
What would the market think of that?Indifference or horror?
 
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keesje
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 1:28 pm

I read somewhere the 757 costed almost as much to build as a 767. It was build like a WB.

I think that if Boeing doesn't launch a 250ish NMA, Airbus will sell even more A321s and will launch a bigger NB based on it anyway.
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heavymetal
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 5:03 pm

RJMAZ wrote:
heavymetal wrote:
Polot is exactly correct here. The 757-300's lack of sales was a function of it's poor timing to market, not it's poor economics. Ask any of the carriers operating it - for the carriers that operate it, its one of, if not the, most profitable narrowbodies thanks to its great economics. I believe it would have outsold the 757-200 over the long run if given the opportunity, much like all of the other upgauge models. Unfortunately 9/11 sealed the 757 family's fate.

No, that is the biggest load of crap I've ever heard. The 757-300 was a desperate last gasp attempt by Boeing to keep the 757 line going. Sales for the 757 came to a dead stop in 1994 with 12 orders and another 13 orders in 1995. The introduction of the A321 in 1994 is what caused that dead stop. The 737-900 didn't help either.

The 757-300 was a last attempt in 1996 to improve CASM as the A321 could easily match the CASM of the 757-200.

That is 5 years before September 11. The coffin lid was already on and that simply added the last nail.

I doubt a 757-300 style modern version would sell very well today. Unless it could sell 1000+ frames its a bad idea.


I'm not sure why you're arguing the 757-200? It's a universal truth that it's much less efficient than the A321s and 737-900ERs that replaced it. There is no debate on this.

That doesn't change the fact that the 757-300, with its stretch, has better economics than the CEOs/NGs and the smallest widebodies above it - even with the drag (pun-intended) of the 757's suboptimal wing. It would have sold better if its EIS was not right around 9/11.

That becomes the fundamental debate in this thread: should the MOM/NMA be an optimized long-narrowbody, like the 757-300 with a new wing/engine, or is it a 7-abreast small widebody. We may get to watch this unfold, if Boeing pursues the small widebody and if Airbus further stretches/re-wings/re-engines the A321neo.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 6:44 pm

heavymetal wrote:
That becomes the fundamental debate in this thread: should the MOM/NMA be an optimized long-narrowbody, like the 757-300 with a new wing/engine, or is it a 7-abreast small widebody. We may get to watch this unfold, if Boeing pursues the small widebody and if Airbus further stretches/re-wings/re-engines the A321neo.


It looks like Boeing had figured it out decades ago when they launched both the 757 and the 767. The very reason they launched both plane types indicates they were very aware of the two separate market segments that needed their own aircraft type.

Boeing seems hesitant to launch a short high capacity widebody and the fact that the pax 767 is being reconsidered seem to indicate that maybe there is not a sufficiently large market for such a widebody aircraft.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 7:19 pm

I think the backers of a twin aisle NMA solution are slowly loosing ground.

The economics look unconvincing, Probably somewhere halfway in between 737 and 787.

Technical breakthroughs that can not be applied to a longer, lighter same capacity NB are invisible.

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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 8:40 pm

VS11 wrote:
heavymetal wrote:
That becomes the fundamental debate in this thread: should the MOM/NMA be an optimized long-narrowbody, like the 757-300 with a new wing/engine, or is it a 7-abreast small widebody. We may get to watch this unfold, if Boeing pursues the small widebody and if Airbus further stretches/re-wings/re-engines the A321neo.


It looks like Boeing had figured it out decades ago when they launched both the 757 and the 767. The very reason they launched both plane types indicates they were very aware of the two separate market segments that needed their own aircraft type.

Boeing seems hesitant to launch a short high capacity widebody and the fact that the pax 767 is being reconsidered seem to indicate that maybe there is not a sufficiently large market for such a widebody aircraft.


This is why I continue to believe in a NMA with the size of the 757-300 and the range of the A321LR, its composite fuselage cross-section shared by a future NSA. A PIP on the 787-8 would complete the lineup for Boeing.
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767333ER
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 8:56 pm

keesje wrote:
I read somewhere the 757 costed almost as much to build as a 767. It was build like a WB.

I think that if Boeing doesn't launch a 250ish NMA, Airbus will sell even more A321s and will launch a bigger NB based on it anyway.

I’m not sure what built like a widebody means. The fundamental difference between a narrowbody and widebody is the body and considering the 757 uses the 707 cords section, it’s built like a narrowbody. The systems give the illusion of being the same as the 767 as they are controlled by basically the same cockpit and and share a few of the same key components such as the fuel pumps, APU, hydraulic pumps, and a few other things. The only major system that I believe is almost the same is the fuel system, but then again not because the 767 can have jettison. The pneumatic systems are very different, so are the hydraulic systems, and electrical systems to an extent too. Perhaps the 757 cost almost as much as a 767 to make because it’s almost as large.
jagraham wrote:
SCAT15F wrote:
Where is this "767-400 has taller landing gear to fit the PW4000 94-inch fan" stuff coming from? The taller gear has absolutely NOTHING to do with the engines.

The 767-300 uses exactly the same size engines (93 and 94-inch fans) as the 767-400. The only difference is the thrust rating, and the higher rating is available for the -300 as well.

This is basic information people.

I did NOT say that the 764 has taller landing gear to fit the PW4000. For the record, the taller gear allows for adequate rotation with the longer fuselage. So the 764 does not have the 739 problem.

What I did say is that since the 763 can accommodate the PW4000 AND the 764 has 18 inch higher landing gear AND the GEnx-2 has an 11 inch bigger fan than the PW4000, the 764 should be able to accommodate the GEnx-2 without significant changes. While the 763 cannot.

The 763 has comparable ground clearance to the 787 which honestly is embarrassing for the 787, but with the GEnx-2B being smaller than the 787’s I don’t see why it wouldn’t fit. It would be close, but maybe a flat bottom like the 737 would be an option if ever they did feel the need to put that engine on a 763.
keesje wrote:
I think the backers of a twin aisle NMA solution are slowly loosing ground.

The economics look unconvincing, Probably somewhere halfway in between 737 and 787.

Technical breakthroughs that can not be applied to a longer, lighter same capacity NB are invisible.

Image

May I ask how you are so sure of this being the case?
Been on: 732 733 734 73G 738 752 763 A319 A320 A321 CRJ CR7 CRA/CR9 E145 E175 E190 F28 MD-82 MD-83 C172R C172S P2006T
 
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keesje
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 9:24 pm

767333ER wrote:
keesje wrote:
I read somewhere the 757 costed almost as much to build as a 767. It was build like a WB.

I think that if Boeing doesn't launch a 250ish NMA, Airbus will sell even more A321s and will launch a bigger NB based on it anyway.

I’m not sure what built like a widebody means. The fundamental difference between a narrowbody and widebody is the body and considering the 757 uses the 707 cords section, it’s built like a narrowbody. The systems give the illusion of being the same as the 767 as they are controlled by basically the same cockpit and and share a few of the same key components such as the fuel pumps, APU, hydraulic pumps, and a few other things. The only major system that I believe is almost the same is the fuel system, but then again not because the 767 can have jettison. The pneumatic systems are very different, so are the hydraulic systems, and electrical systems to an extent too. Perhaps the 757 cost almost as much as a 767 to make because it’s almost as large.
jagraham wrote:
SCAT15F wrote:
Where is this "767-400 has taller landing gear to fit the PW4000 94-inch fan" stuff coming from? The taller gear has absolutely NOTHING to do with the engines.

The 767-300 uses exactly the same size engines (93 and 94-inch fans) as the 767-400. The only difference is the thrust rating, and the higher rating is available for the -300 as well.

This is basic information people.

I did NOT say that the 764 has taller landing gear to fit the PW4000. For the record, the taller gear allows for adequate rotation with the longer fuselage. So the 764 does not have the 739 problem.

What I did say is that since the 763 can accommodate the PW4000 AND the 764 has 18 inch higher landing gear AND the GEnx-2 has an 11 inch bigger fan than the PW4000, the 764 should be able to accommodate the GEnx-2 without significant changes. While the 763 cannot.

The 763 has comparable ground clearance to the 787 which honestly is embarrassing for the 787, but with the GEnx-2B being smaller than the 787’s I don’t see why it wouldn’t fit. It would be close, but maybe a flat bottom like the 737 would be an option if ever they did feel the need to put that engine on a 763.
keesje wrote:
I think the backers of a twin aisle NMA solution are slowly loosing ground.

The economics look unconvincing, Probably somewhere halfway in between 737 and 787.

Technical breakthroughs that can not be applied to a longer, lighter same capacity NB are invisible.

Image

May I ask how you are so sure of this being the case?


Sure ? But I think the backers of a twin aisle NMA solution are slowly loosing ground. The economics look unconvincing, Probably somewhere halfway in between 737 and 787. Technical breakthroughs that can not be applied to a longer, lighter same capacity NB are invisible. And now Boeing seems to delay the project. Not convincing IMO.
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 10:37 pm

Polot wrote:
Correlation does not equal causation.

On September 11 2001 the 757 only had 49 outstanding orders or one years production left. That is a dead program or as people call the 747-8 "on life support"

So it was dead before September 11.

The A321 and the A320 in general got increased orders after September 11. You can see the big production rate increase in 2005 and 2006. So September 11 is a convenient excuse but a false one.

Boeing had delivered more 757's than what was ordered for every year since 1991. So the backlog was continually decreasing.

Between 1978 and 1990 nearly every year Boeing had more orders than what they were producing. The backlog was increasing. With a peak of 166 orders in 1989.

So it wasn't one or two years dip in orders. If you plot the data the program peaked in 1991 and had a significant downturn in 1994 and 1995. The A320 program quadrupled deliveries from 1994 to 1999. That is a huge ramp up. So the 757 decline lines up with the A320 and then 737NG which has good CASM and much better RASM. The A310 also got killed by the A320 with its orders going straight to zero.

The 757 is much loved on here. But it is viewed through rose coloured glasses.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 10:53 pm

heavymetal wrote:
That doesn't change the fact that the 757-300, with its stretch, has better economics than the CEOs/NGs and the smallest widebodies above it - even with the drag (pun-intended) of the 757's suboptimal wing. It would have sold better if its EIS was not right around 9/11.

You've got your dates wrong.

There is a massive amount of years between placing orders and having it entering service. Boeing launched the 757-300 program on September 1996. That is a full 5 years before September 11 2001. So the 757-300 averaged only 10 aircraft per year in a booming economy. That is a piss poor performance.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sat Dec 09, 2017 11:13 pm

keesje wrote:
Sure ? But I think the backers of a twin aisle NMA solution are slowly loosing ground. The economics look unconvincing, Probably somewhere halfway in between 737 and 787. Technical breakthroughs that can not be applied to a longer, lighter same capacity NB are invisible. And now Boeing seems to delay the project. Not convincing IMO.

Pure speculation.

I've shown that weights of a 30 year old widebody design can match the modern A320 on weight per passenger and area per passenger.

I've shown extending a long narrowbody tube can weigh more than extending a shorter widebody tube the same length.

I've shown the 757 sales tanked since the A320 came out. A new engined version would still be overweight due to the structurally inefficient long and skinny tube.

Maybe ask Singapore airlines who operated both the 757 and A310. They sold their 757's after only 5 years and bought additional A310's.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 1:00 am

If we take the lightest variants of twin aisles, and the most (unusual) positive seating numbers (767 at 8 abreast, A310 at 9 abreast, A321 just max 220 seats)
it becomes clear the NB 757 and A321 are much lighter per seat.

A310 - Operating empty 80,142kg (176,683lb), Max passenger capacity at nine abreast 280, 286 kg per seat.
B762 - Operating empty with JT9Ds 80,920kg (178,400lb), Max seating for 290 at eight abreast, 279 kg per seat
A300B4 - Operating empty 88,500kg (195,109lb), 336 single class passengers in main cabin, 263 kg per seat
767-300 - Empty with PW-4050s 79,560kg (175,400lb), max seating for 328 at eight abreast, 243 kg per seat.
B752 - Operating empty with P&W engines 57,840kg (127,520lb), up to 239 in all economy class.242 kg per seat.
B753 - Operating empty with RB-211s 64,590kg (142,400lb) Max seating for 289 passengers, 223 kg per seat
A321 - Operating empty 47,776kg (105,330lb), Maximum in a high density layout of 220 passengers, 217 kg per seat
source: http://www.airliners.net/aircraft-data https://www.seatguru.com/airlines/Thomson_Airways/Thomson_Airways_Boeing_767-300ER_V4.php,

The numbers show that the optimized twin aisles for the same mission has an operating empty weight 20% higher. That's probably why they get parked.
And that is taking very conservative numbers (most 767s are 7 abreast, A310s 8 abreast & today A321s can take more than 220 seats).

You have to get to really big aircraft (>300 seats) to get close.

That raises the question: is above 300 seats the NMA spec airlines are looking for? Apparently not. More up to 250 seats.

Image
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 2:19 am

B777LRF wrote:
seahawk wrote:
B777LRF wrote:
Engines are important to get the desired efficiency, but you must assume the same efficiency of the engines when looking at the fuselage and wing design.


Eyad89 wrote:


I agree with both of you, but the basic premise of this thread has the issues backwards: It's engines first, then fuselage and wings. If, just for arguments sake, the next big thing in the engine department turns out to be ducted fans which lends itself to mounting on the aft fuselage, then all previous discussions about fuselage dimensions and wing geometry goes out the window.

Engines first; the rest will follow.

CFM, RR, and Pratt are all going to offer very competitive designs.

Ducted fans are too far away. Unducted fans have too slow of cruise for the range.

Pratt is offering a next generation GTF. CFM and RR will offer very competitive designs to keep Pratt off the platform.

There is not going to be an issue with competitive engines. Since the engines will be optimized for longer missions than the NEO (which are optimized for longer missions than the MAX or C-series).

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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 4:13 am

keesje wrote:
If we take the lightest variants of twin aisles, and the most (unusual) positive seating numbers

I feel that I'm repeating myself.

You've just compared widebody aircraft with greater range.

762 - 6500nm
763 - 5900nm
A310 - 5100nm
A300 - 4000nm

753 - 3400nm
752 - 3900nm
A321CEO - 3200nm
A321NEOLR - 4000nm

You can clearly see the connection between weight per passenger and the aircrafts range. The numbers line up perfectly.

The 757-200 has the closest range and is similar vintage to the widebody designs. The 767-300 can equal the weight per passenger even though its carrying the wing and structure to support 50% greater range. That in itself should be all the proof you need.

If a plane had to fly 50% further it needs much more fuel, it needs much more structure to carry that fuel. A larger wing, stronger gear and engines. The opposite happens if you reduce the required range the plane would be lighter if fully optimised. The the 767 non ER models had a wing and structure sized correctly they would both be lighter and would clearly beat both 757 versions and match the A321.

I think I'll plot a graph tomorrow with weight per passenger on one axis and range on the other.

You'll see that it will be a straight line.

We should do the following.

Empty weight / max passenger / range. Lowest number wins.

763ER - 90011 / 326 / 6025 = 0.0458
A321CEO - 47776 / 220 / 3200 = 0.0678
A321NEOLR 50800 / 240 / 4000 = 0.0529

The 767 wins by a big margin.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 6:34 am

keesje wrote:
That raises the question: is above 300 seats the NMA spec airlines are looking for? Apparently not. More up to 250 seats.

Image

You do realise that the 767 and A310 size actually covers 81% of that pie chart. The percentages nearly perfectly match cabin capacities fitted to both the A310 and 767 fleets in service.

With the 767 a tiny number of charters used them with over 300 seats. The pie chart says 3% that sounds right.

Economy airlines operated them with 200-250 seats. The pie chart says 27% which again sounds about right.

Most larger airlines used them on medium haul routes with under 200 seats with a luxurious business class. Most 767's and A310's sold had cabins under 200 seats so 46% on the pie chart is spot on.

So the pie chart perfectly represents the A310/767 size.

No where does the pie chart say that is the maximum seating capacity. It would be the seating capacity the airline wants with their standard of seating density. Some high end airlines have very low density with plenty of room per passenger.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 10:29 am

lightsaber wrote:
B777LRF wrote:
seahawk wrote:



I agree with both of you, but the basic premise of this thread has the issues backwards: It's engines first, then fuselage and wings. If, just for arguments sake, the next big thing in the engine department turns out to be ducted fans which lends itself to mounting on the aft fuselage, then all previous discussions about fuselage dimensions and wing geometry goes out the window.

Engines first; the rest will follow.

CFM, RR, and Pratt are all going to offer very competitive designs.

Ducted fans are too far away. Unducted fans have too slow of cruise for the range.

Pratt is offering a next generation GTF. CFM and RR will offer very competitive designs to keep Pratt off the platform.

There is not going to be an issue with competitive engines. Since the engines will be optimized for longer missions than the NEO (which are optimized for longer missions than the MAX or C-series).

Lightsaber


I fully agree with you, when looking at the pure plane design, but when you look at the market position of a product the outlook must be different. If your product is only competitive when having more advanced engines, it is always vulnerable to the competition modernising the engines on their product.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 12:32 pm

Yes the engines don't count as they are available for both manufacturers. The edges must be found somewhere else
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 1:58 pm

keesje wrote:
If we take the lightest variants of twin aisles, and the most (unusual) positive seating numbers (767 at 8 abreast, A310 at 9 abreast, A321 just max 220 seats)
it becomes clear the NB 757 and A321 are much lighter per seat.

A310 - Operating empty 80,142kg (176,683lb), Max passenger capacity at nine abreast 280, 286 kg per seat.
B762 - Operating empty with JT9Ds 80,920kg (178,400lb), Max seating for 290 at eight abreast, 279 kg per seat
A300B4 - Operating empty 88,500kg (195,109lb), 336 single class passengers in main cabin, 263 kg per seat
767-300 - Empty with PW-4050s 79,560kg (175,400lb), max seating for 328 at eight abreast, 243 kg per seat.
B752 - Operating empty with P&W engines 57,840kg (127,520lb), up to 239 in all economy class.242 kg per seat.
B753 - Operating empty with RB-211s 64,590kg (142,400lb) Max seating for 289 passengers, 223 kg per seat
A321 - Operating empty 47,776kg (105,330lb), Maximum in a high density layout of 220 passengers, 217 kg per seat
source: http://www.airliners.net/aircraft-data https://www.seatguru.com/airlines/Thomson_Airways/Thomson_Airways_Boeing_767-300ER_V4.php,

The numbers show that the optimized twin aisles for the same mission has an operating empty weight 20% higher. That's probably why they get parked.
And that is taking very conservative numbers (most 767s are 7 abreast, A310s 8 abreast & today A321s can take more than 220 seats).

You have to get to really big aircraft (>300 seats) to get close.

That raises the question: is above 300 seats the NMA spec airlines are looking for? Apparently not. More up to 250 seats.]


You are looking at this in a really really weird way. I think this is because of your bias towards Airbus narrowbodies is causing you to twist logic.

If Boeing comes up with target ranges and capacities, the MTOW and OEW of the airplane are mostly set. The wing, landing gear and engines are sized mostly based on payload . Let’s say the magic number is all economy 300seats at 4000nm range based in market research and that is what Boeing wants to build. That would be 150K in payload. From that point Boeing would decide how long a 6, 7, 8 or 9 abreast plane would be to fit in those 300 seats (50 rows at 6 abreast, 43 at 7 abreast, 38 at 8 abreast) and determine the OEW of each fuselage dimension. Longer and narrower, or shorter and wider. They will decide what is best since they have all the numbers and analysis.

Comparing OEWs of the 757, 767, A310 and A321 to support your claim that a narrowbody is lighter per seat makes no sense since the payload and MTOW of the 767 and A310 are much higher since the wings, engines, and gear are heavier so that the plane can lift more fuel to fly much farther.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 2:06 pm

keesje wrote:

The numbers show that the optimized twin aisles for the same mission has an operating empty weight 20% higher. That's probably why they get parked.
And that is taking very conservative numbers (most 767s are 7 abreast, A310s 8 abreast & today A321s can take more than 220 seats).

They are? Incredible what Boeing was able to do with the 762 optimized for ~220 pax over ~4,000nm to turn it into a 763ER with minimal effort. Its almost like the 762 wasn't optimized for its missions at all.
 
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 2:18 pm

RJMAZ wrote:
I feel that I'm repeating myself.

You've just compared widebody aircraft with greater range.

762 - 6500nm
763 - 5900nm
A310 - 5100nm
A300 - 4000nm

753 - 3400nm
752 - 3900nm
A321CEO - 3200nm
A321NEOLR - 4000nm

You can clearly see the connection between weight per passenger and the aircrafts range. The numbers line up perfectly.

The 757-200 has the closest range and is similar vintage to the widebody designs. The 767-300 can equal the weight per passenger even though its carrying the wing and structure to support 50% greater range. That in itself should be all the proof you need.

If a plane had to fly 50% further it needs much more fuel, it needs much more structure to carry that fuel. A larger wing, stronger gear and engines. The opposite happens if you reduce the required range the plane would be lighter if fully optimised. The the 767 non ER models had a wing and structure sized correctly they would both be lighter and would clearly beat both 757 versions and match the A321.

I think I'll plot a graph tomorrow with weight per passenger on one axis and range on the other.

Yes, please do. And please make sure there are no house flies on the glass when you make a copy! :biggrin:
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PHBVF
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 3:17 pm

Well if you take range into account for those aircraft models, please do take into account that there is no way a 767-200 could reach 6500nm, that would be a 767-200ER.
Same goes for a 767-300/-300ER and A310-200/-300. Not even getting started on the A300 (as certain models could barely make 2000nm!)
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Polot
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 3:56 pm

PHBVF wrote:
Well if you take range into account for those aircraft models, please do take into account that there is no way a 767-200 could reach 6500nm, that would be a 767-200ER.
Same goes for a 767-300/-300ER and A310-200/-300. Not even getting started on the A300 (as certain models could barely make 2000nm!)


Yes, but it shows how un-optimized the 762A/763A are. Boeing did not go and significantly alter the wings, landing gear, etc to go from A->ER. The ER's OEW is only 2-4 t heavier than their A versions but have ~2000 nm more range and ~35-45t higher MTOW.
 
Newbiepilot
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 5:14 pm

Polot wrote:
PHBVF wrote:
Well if you take range into account for those aircraft models, please do take into account that there is no way a 767-200 could reach 6500nm, that would be a 767-200ER.
Same goes for a 767-300/-300ER and A310-200/-300. Not even getting started on the A300 (as certain models could barely make 2000nm!)


Yes, but it shows how un-optimized the 762A/763A are. Boeing did not go and significantly alter the wings, landing gear, etc to go from A->ER. The ER's OEW is only 2-4 t heavier than their A versions but have ~2000 nm more range and ~35-45t higher MTOW.


The 767-200A is far far away from optimized since the most powerful engine at the time of introduction had about 48,000lbs of thrust. Once more powerful engines in the 50-60K lbs range were available, the plane was able to be optimized to fully take advantage of its 3,000 sq ft wing which is more than double the size of the A321 wing and a whole lot heavier.

Boeing won’t have problems with undersized engines on a new plane so it will be much more optimized. The 767-200A is not a good example to compare OEW, MTOW, or range with because it had a big wing to make up for underpowered engines. Once more powerful engines were available, the plane had almost too much range to be useful.
 
Eyad89
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 6:00 pm

RJMAZ wrote:
keesje wrote:
If we take the lightest variants of twin aisles, and the most (unusual) positive seating numbers

I feel that I'm repeating myself.

You've just compared widebody aircraft with greater range.

762 - 6500nm
763 - 5900nm
A310 - 5100nm
A300 - 4000nm

753 - 3400nm
752 - 3900nm
A321CEO - 3200nm
A321NEOLR - 4000nm

You can clearly see the connection between weight per passenger and the aircrafts range. The numbers line up perfectly.

The 757-200 has the closest range and is similar vintage to the widebody designs. The 767-300 can equal the weight per passenger even though its carrying the wing and structure to support 50% greater range. That in itself should be all the proof you need.

If a plane had to fly 50% further it needs much more fuel, it needs much more structure to carry that fuel. A larger wing, stronger gear and engines. The opposite happens if you reduce the required range the plane would be lighter if fully optimised. The the 767 non ER models had a wing and structure sized correctly they would both be lighter and would clearly beat both 757 versions and match the A321.

I think I'll plot a graph tomorrow with weight per passenger on one axis and range on the other.

You'll see that it will be a straight line.

We should do the following.

Empty weight / max passenger / range. Lowest number wins.

763ER - 90011 / 326 / 6025 = 0.0458
A321CEO - 47776 / 220 / 3200 = 0.0678
A321NEOLR 50800 / 240 / 4000 = 0.0529

The 767 wins by a big margin.



Why are we even considering range in the equation, isn't range an irrelevant variable when it comes to the MOM market? (otherwise A338 would still be a good candidate).

A widebody airplane will almost always have more range than a narrowbody aircraft, their bigger size will always allow them to carry more fuel that makes them fly further. Their longer range is a part of being a widebody aircraft, they can carry more fuel and payload. This fact can't just be ignored or changed. No widebody with short range has ever been a great success,actually it's quite the opposite. The success of widebody airplanes increases proportionally as their range increases (compare sales of 773 against 77W, or 767-300 against 767-300ER)

The longer range of 767 isn't an excuse for having a heavier weight per passenger than 757. Boeing can't change that, that's the disadvantage of being a widebody frame.

A300 is a widebody that is optimized for short range , and we have shown how it competes against 752 that has exactly the same range (4,000 nm vs 3,900 nm), 752 is the one with better weight/passenger. Range isn't to be blamed here, it is the efficacy of narrowbody aircraft.

RJMAZ wrote:
The the 767 non ER models had a wing and structure sized correctly they would both be lighter and would clearly beat both 757
.


Please explain this, and how come neither Boeing nor Airbus were successful at making this aircraft for all those years.

A modern 757 with composite materials can have a range of 4,500-5,000 with great efficiency. I still have this hope that this is what 797 would like eventually.
 
Eyad89
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 6:41 pm

Newbiepilot wrote:
Polot wrote:
PHBVF wrote:
Well if you take range into account for those aircraft models, please do take into account that there is no way a 767-200 could reach 6500nm, that would be a 767-200ER.
Same goes for a 767-300/-300ER and A310-200/-300. Not even getting started on the A300 (as certain models could barely make 2000nm!)


Yes, but it shows how un-optimized the 762A/763A are. Boeing did not go and significantly alter the wings, landing gear, etc to go from A->ER. The ER's OEW is only 2-4 t heavier than their A versions but have ~2000 nm more range and ~35-45t higher MTOW.


The 767-200A is far far away from optimized since the most powerful engine at the time of introduction had about 48,000lbs of thrust. Once more powerful engines in the 50-60K lbs range were available, the plane was able to be optimized to fully take advantage of its 3,000 sq ft wing which is more than double the size of the A321 wing and a whole lot heavier.

Boeing won’t have problems with undersized engines on a new plane so it will be much more optimized. The 767-200A is not a good example to compare OEW, MTOW, or range with because it had a big wing to make up for underpowered engines. Once more powerful engines were available, the plane had almost too much range to be useful.



To put things into perspective, in order for 767-300A to have the same weight/passenger as 752, its OEW has to drop down from 86,000 KG to 72,000 KG. How can Boeing achieve that? In order for 767-300A to have the same weight/passenger as 753, its OEW has to drop down to 68,000 KG. What can be done to achieve that?
 
Kikko19
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 6:41 pm

757has the fuse of 737? Then it's dead in the water. But should come out with a slightly bigger fuse than a320 and then we can discuss about mom.
 
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Stitch
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 6:45 pm

RJMAZ wrote:
The the 767 non ER models had a wing and structure sized correctly they would both be lighter and would clearly beat both 757.

Eyad89 wrote:
Please explain this, and how come neither Boeing nor Airbus were successful at making this aircraft for all those years.


Because it wasn't the goal. The 767 and 777 were both designed as long-range airframes so their structures reflected that role. They were held back in early service due to the lack of sufficient engine power (and in the case of the 767, conservative ETOPS rules) so they had operating weights well below what they were designed around. Once the engines became available to support the significantly higher TOWs needed to tank the necessary fuel for long-range flight, they became the frames they were designed to be and became much more successful.

The 757 was meant to be the "short-haul" airframe whereas the 767 was meant to be the "long-haul airplane". The 767 tanked almost twice the fuel of the 757 thanks to the greater center tank volume the wider and taller fuselage offered and the greater wing tank volume due to the larger and thicker wing. To be able to lift that extra fuel weight required a stronger, heavier frame and more powerful (and heavier) engines and stronger (and heavier) landing gear.


Eyad89 wrote:
To put things into perspective, in order for 767-300A to have the same weight/passenger as 752, its OEW has to drop down from 86,000 KG to 72,000 KG. How can Boeing achieve that?


They would make the 767-300A shorter and maybe shrink the wingspan a bit, as well. Airbus shrank the A300 by 7 meters and took a meter off the wings to create the A310 and lower the OEW by almost 10,000kg. You'd also not need to strengthen the airframe and wings as much to support higher operating weights, you'd use lighter landing gear and maybe smaller tires. Maybe save some weight in the engines (lower thrust could mean lighter materials could be used).
 
DfwRevolution
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 7:02 pm

Kikko19 wrote:
757has the fuse of 737? Then it's dead in the water. But should come out with a slightly bigger fuse than a320 and then we can discuss about mom.


The 757 shares the same upper lobe diameter as the 707, 727, and 737. The 757 lower lobe and structural design are unique. Not that it matters. It isn't re-entering production.
I have a three post per topic limit. You're welcome to have the last word.
 
RJMAZ
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 8:38 pm

Eyad89 wrote:
A300 is a widebody that is optimized for short range , and we have shown how it competes against 752 that has exactly the same range (4,000 nm vs 3,900 nm), 752 is the one with better weight/passenger. Range isn't to be blamed here, it is the efficacy of narrowbody aircraft.

A300 88,500kg / 361 seats = 245kg
752 57,840kg / 239 seats = 242kg

2.5% difference in range 0.8% difference in weight.
You can see they are the same. No difference in weight per passenger. Both all economy 17" seats equal aisle space per passenger, same pitch.

Stitch further explains why the range must be taken into account.
 
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seahawk
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 8:48 pm

Exit Limit for the A300 is 345.
 
Eyad89
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 8:49 pm

RJMAZ wrote:
Eyad89 wrote:
A300 is a widebody that is optimized for short range , and we have shown how it competes against 752 that has exactly the same range (4,000 nm vs 3,900 nm), 752 is the one with better weight/passenger. Range isn't to be blamed here, it is the efficacy of narrowbody aircraft.

A300 88,500kg / 361 seats = 245kg
752 57,840kg / 239 seats = 242kg

2.5% difference in range 0.8% difference in weight.
You can see they are the same. No difference in weight per passenger. Both all economy 17" seats equal aisle space per passenger, same pitch.

Stitch further explains why the range must be taken into account.



Again, you went for a 9-abreast A300. Do the numbers again with 321 seats ( as the Thomas Cook A322)
 
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sassiciai
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 9:23 pm

This thread title is the following:

Boeing officially forms program office to flesh out 797 plans

A Program Office does not define what is produced, that is the responsibility of the "797 Project Team" or whatever title Boeing uses for such a team

The Program Office (PO) is tasked with the "how" of producing the new bird, the "what" is not its remit. This PO is looking into how to build the thing, how to organise the assembly line, how to arrange the supply chain, and all such things. This thread should be debating all the mistakes made in the 787 project, how to rectify those errors, what to do about composites, all-electric, and all that technical stuff

But here on A.net, it seems everyone is only interested in "what", and not the "how". If that is reflected in Seattle (or Chicago), then I can only wish Boeing good luck in this next (moon-) shot! If they cant get round to thinking "how", then maybe they'll need my good luck!

At the extent of this thread, my input (second attempt) might be all too late! The "how" thread didn't get started, and is still overwhelmed by the "what". IMHO, that should be in a different thread!
 
RJMAZ
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 9:30 pm

Eyad89 wrote:
Again, you went for a 9-abreast A300. Do the numbers again with 321 seats ( as the Thomas Cook A322)


https://www.seatmaestro.com/wp-content/ ... 0-603r.pdf

361 seats in the A300

A300 - 17" seats with two 15" aisles.

757 - 17.2" seats with one 20" aisle.

So I went with near perfect comparison. The 757 number is using 28" pitch where as the A300 appears to be 29" pitch. So the A300 actually has equal space per passenger.

Of course you can change the aisle size to make the seats wider or smaller to give the answer you want. So I could see you putting 18" seats in the 757 with a 16" aisle and putting 16" inch seats in the A300 with two 18" aisles as a counter argument.

The aisles width I chose both have equal 3.33" of aisle per seat.

In case of the 767. 2-4-2 actual has 75% of the seats with a window or aisle. So its not too bad with 16.5" seats an two 15" aisles.
 
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keesje
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 9:41 pm

sassiciai wrote:
This thread title is the following:

Boeing officially forms program office to flesh out 797 plans

A Program Office does not define what is produced, that is the responsibility of the "797 Project Team" or whatever title Boeing uses for such a team

The Program Office (PO) is tasked with the "how" of producing the new bird, the "what" is not its remit. This PO is looking into how to build the thing, how to organise the assembly line, how to arrange the supply chain, and all such things. This thread should be debating all the mistakes made in the 787 project, how to rectify those errors, what to do about composites, all-electric, and all that technical stuff

But here on A.net, it seems everyone is only interested in "what", and not the "how". If that is reflected in Seattle (or Chicago), then I can only wish Boeing good luck in this next (moon-) shot! If they cant get round to thinking "how", then maybe they'll need my good luck!

At the extent of this thread, my input (second attempt) might be all too late! The "how" thread didn't get started, and is still overwhelmed by the "what". IMHO, that should be in a different thread!



The what & how seem hard to separate.

A 737 stretch or a flat 787 has a huge impact on "how".

Image

Not that I believe in a further 737 development, but you never know..

I think the discussion is very much in the what area as we speak. Maybe they even need more time..
"Never mistake motion for action." Ernest Hemingway
 
Newbiepilot
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 11:06 pm

Eyad89 wrote:
Newbiepilot wrote:
Polot wrote:

Yes, but it shows how un-optimized the 762A/763A are. Boeing did not go and significantly alter the wings, landing gear, etc to go from A->ER. The ER's OEW is only 2-4 t heavier than their A versions but have ~2000 nm more range and ~35-45t higher MTOW.


The 767-200A is far far away from optimized since the most powerful engine at the time of introduction had about 48,000lbs of thrust. Once more powerful engines in the 50-60K lbs range were available, the plane was able to be optimized to fully take advantage of its 3,000 sq ft wing which is more than double the size of the A321 wing and a whole lot heavier.

Boeing won’t have problems with undersized engines on a new plane so it will be much more optimized. The 767-200A is not a good example to compare OEW, MTOW, or range with because it had a big wing to make up for underpowered engines. Once more powerful engines were available, the plane had almost too much range to be useful.



To put things into perspective, in order for 767-300A to have the same weight/passenger as 752, its OEW has to drop down from 86,000 KG to 72,000 KG. How can Boeing achieve that? In order for 767-300A to have the same weight/passenger as 753, its OEW has to drop down to 68,000 KG. What can be done to achieve that?


First off the engines on the 757 are 1 ton lighter so that is 2000KGs. The 767 wing is 50% larger than the 757(3000sq.ft vs 2000sq.ft). The wingbox structure also shrinks with lower loading. That gets you much of the rest of the difference to get them close.
 
Newbiepilot
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Re: Boeing officially forms program office to flesh out 797 plans

Sun Dec 10, 2017 11:09 pm

sassiciai wrote:
This thread title is the following:

Boeing officially forms program office to flesh out 797 plans

A Program Office does not define what is produced, that is the responsibility of the "797 Project Team" or whatever title Boeing uses for such a team

The Program Office (PO) is tasked with the "how" of producing the new bird, the "what" is not its remit. This PO is looking into how to build the thing, how to organise the assembly line, how to arrange the supply chain, and all such things. This thread should be debating all the mistakes made in the 787 project, how to rectify those errors, what to do about composites, all-electric, and all that technical stuff

But here on A.net, it seems everyone is only interested in "what", and not the "how". If that is reflected in Seattle (or Chicago), then I can only wish Boeing good luck in this next (moon-) shot! If they cant get round to thinking "how", then maybe they'll need my good luck!

At the extent of this thread, my input (second attempt) might be all too late! The "how" thread didn't get started, and is still overwhelmed by the "what". IMHO, that should be in a different thread!


I don’t think people care as much about how the airplane is built as they do about cabin width ;)

The how is incredibly important. It drives the production costs. How is also incredibly important when it comes to leasing customers. Airbus has had a big advantage selling to leasing customers with the A330 being more popular than 777. A plane built for lessors (minimal variability, low engine overhaul costs, simplified option structure, standardized interiors, etc) may sell very well.
 
RJMAZ
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Re: Boeing officially forms program office to flesh out 797 plans

Mon Dec 11, 2017 9:56 am

So I plotted the aircraft numbers. As we can see there is a consistent link between the range of the aircraft and the empty weight per passenger.

Image

The ranges quoted are with a light passenger payload. With the maximum passenger amount usually the range is significantly less. This is obvious with big range difference between the 737Max8 and the 737Max200. It shows just how light the passenger loads must be.

Also the 787-10 hits its exit limit with a full econony cabin. With 9ab 30" pitch it would have 460-470 passengers which would bring it back to the right.

Also I created another table where I divided the empty weight per passenger by its range. I then placed them in order of range and the graph perfectly shows the relationship.

Image

The design range of the aircraft is the biggest factor in CASM.

In terms of the Boeing 797 widebody. If the stretch has a max range of 3500nm then it is highly likely to have better CASM than a 4000nm max range narrowbody.
 
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seahawk
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Re: Boeing officially forms program office to flesh out 797 plans

Mon Dec 11, 2017 10:43 am

But now you forgot one important factor, landing cycles.
 
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keesje
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Re: Boeing officially forms program office to flesh out 797 plans

Mon Dec 11, 2017 10:57 am

RJMAZ wrote:
So I plotted the aircraft numbers. As we can see there is a consistent link between the range of the aircraft and the empty weight per passenger.

Image

The ranges quoted are with a light passenger payload. With the maximum passenger amount usually the range is significantly less. This is obvious with big range difference between the 737Max8 and the 737Max200. It shows just how light the passenger loads must be.

Also the 787-10 hits its exit limit with a full econony cabin. With 9ab 30" pitch it would have 460-470 passengers which would bring it back to the right.

Also I created another table where I divided the empty weight per passenger by its range. I then placed them in order of range and the graph perfectly shows the relationship.

Image

The design range of the aircraft is the biggest factor in CASM.

In terms of the Boeing 797 widebody. If the stretch has a max range of 3500nm then it is highly likely to have better CASM than a 4000nm max range narrowbody.


Great Job RJMAZ! I will have a closer look in my free time :wink2:

What we shouldn't forget / ignore the bulk of flights for NMA's would be ~ 250 seats ~1500NM. see Page 49 : http://www.oliverwyman.com/content/dam/oliver-wyman/global/en/2016/jan/oliver-wyman-airline-economic-analysis-2015-2016.pdf

It a beefed up big NMA is good for >3000NM > 250 seats only, it will be wiped away by much cheaper NB's in the (huge) <1500NM segment. And also wiped away >3500NM by much more capable, bulk produced twin aisles. That can fly to/from Asia the next day, or alternatively TATL with an extra 20t of revenue cargo. And the airlines already have them.
"Never mistake motion for action." Ernest Hemingway
 
RJMAZ
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Re: Boeing officially forms program office to flesh out 797 plans

Mon Dec 11, 2017 1:31 pm

keesje wrote:
It a beefed up big NMA is good for >3000NM > 250 seats only, it will be wiped away by much cheaper NB's in the (huge) <1500NM segment. And also wiped away >3500NM by much more capable, bulk produced twin aisles. That can fly to/from Asia the next day, or alternatively TATL with an extra 20t of revenue cargo. And the airlines already have them.

The most efficient aircraft to fly 1500nm will be the one that's maximum range is 1500nm. It doesnt matter if its twin aisle or single aisle. As the graphs show the range with max payload determines the weight of the aircraft much more than the payloads weight itself. So short range CASM is directly rated to range.

For instance a 767-300 fuselage sitting on top of 757 sized wing and engines. It wouldn't fly very far but it would be extremely efficient at any distance it could fly.

The opposite a 757-300 fuselage sitting on 767 sized wings and engines could fly 8000+nm however it would not be efficient on a 1000nm trip.

Boeing can simply size the wing so the stretch model has a very low range with max payload. That means Boeing can hit any CASM target they want by simply optimising around a lower fuel load and lower maximum takeoff weight.

If Boeing finds 50% of the NMA flights will be under 1500nm then we may see a 767-300 sized fuselage on top of 757 sized wings and engines. As the fuselage makes up less than half of the aircrafts weight then this 797-10 would be closer to the 753's empty weight than the 763's. Half way is 75T so probably closer to 70T. This would be the super efficient tight 8ab people mover for those 1500nm trips. The A321 with its higher 3500nm design range would be at a disadvantage. A larger winged longer ranged A322 even more so.

Then you would have the shorter 762 sized cabin version the 797-9. You'd save 3-4T in fuselage weight straight off the bat. With 50 less passengers saves another 5T in payload. This frees up 8T for extra fuel that the stretch couldn't carry. Range would go up around that of the A321.

The 797-8 would then be the shrink. More fuselage weight saved and less passenger weight would allow the 757 sized wings to be finally be filled to full capacity. Depending on its length it could be similar capacity to the A321LR but with 5000+nm range. Or it could be A322 sized with 4500+nm range. Either way it would be a step above.

In summary 120T maximum takeoff 70-75T OEW
797-8 250 seat economy, 200 seat 2 class, 5000nm,
797-9 300 seat economy, 240 seat 2 class, 3500nm,
797-10 350 seat economy, 280 seat 2 class, 2000nm,
 
Newbiepilot
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Re: Boeing officially forms program office to flesh out 797 plans

Mon Dec 11, 2017 2:09 pm

RJMAZ wrote:
keesje wrote:
It a beefed up big NMA is good for >3000NM > 250 seats only, it will be wiped away by much cheaper NB's in the (huge) <1500NM segment. And also wiped away >3500NM by much more capable, bulk produced twin aisles. That can fly to/from Asia the next day, or alternatively TATL with an extra 20t of revenue cargo. And the airlines already have them.

The most efficient aircraft to fly 1500nm will be the one that's maximum range is 1500nm. It doesnt matter if its twin aisle or single aisle. As the graphs show the range with max payload determines the weight of the aircraft much more than the payloads weight itself. So short range CASM is directly rated to range.

For instance a 767-300 fuselage sitting on top of 757 sized wing and engines. It wouldn't fly very far but it would be extremely efficient at any distance it could fly.

The opposite a 757-300 fuselage sitting on 767 sized wings and engines could fly 8000+nm however it would not be efficient on a 1000nm trip.

Boeing can simply size the wing so the stretch model has a very low range with max payload. That means Boeing can hit any CASM target they want by simply optimising around a lower fuel load and lower maximum takeoff weight.

If Boeing finds 50% of the NMA flights will be under 1500nm then we may see a 767-300 sized fuselage on top of 757 sized wings and engines. As the fuselage makes up less than half of the aircrafts weight then this 797-10 would be closer to the 753's empty weight than the 763's. Half way is 75T so probably closer to 70T. This would be the super efficient tight 8ab people mover for those 1500nm trips. The A321 with its higher 3500nm design range would be at a disadvantage. A larger winged longer ranged A322 even more so.

Then you would have the shorter 762 sized cabin version the 797-9. You'd save 3-4T in fuselage weight straight off the bat. With 50 less passengers saves another 5T in payload. This frees up 8T for extra fuel that the stretch couldn't carry. Range would go up around that of the A321.

The 797-8 would then be the shrink. More fuselage weight saved and less passenger weight would allow the 757 sized wings to be finally be filled to full capacity. Depending on its length it could be similar capacity to the A321LR but with 5000+nm range. Or it could be A322 sized with 4500+nm range. Either way it would be a step above.

In summary 120T maximum takeoff 70-75T OEW
797-8 250 seat economy, 200 seat 2 class, 5000nm,
797-9 300 seat economy, 240 seat 2 class, 3500nm,
797-10 350 seat economy, 280 seat 2 class, 2000nm,


I really appreciate your comments on this thread. I have never seen a chart like the one you created. I also appreciate your responses to someone who is playing devils advocate against the rumored configuration from Boeing.

I am excited to see what Boeing comes up with for range, capacity, and payload. I am also intrigued to find out what parts will be composite and how it will be fabricated. I am also wondering how they will find a way to keep production costs low. I imagine many more robots inside the Boeing factories versus the outsourcing strategy used on the 787. It is an exciting time!
 
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william
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Re: Boeing officially forms program office to flesh out 797 plans

Mon Dec 11, 2017 2:38 pm

Newbiepilot wrote:
RJMAZ wrote:
keesje wrote:
It a beefed up big NMA is good for >3000NM > 250 seats only, it will be wiped away by much cheaper NB's in the (huge) <1500NM segment. And also wiped away >3500NM by much more capable, bulk produced twin aisles. That can fly to/from Asia the next day, or alternatively TATL with an extra 20t of revenue cargo. And the airlines already have them.

The most efficient aircraft to fly 1500nm will be the one that's maximum range is 1500nm. It doesnt matter if its twin aisle or single aisle. As the graphs show the range with max payload determines the weight of the aircraft much more than the payloads weight itself. So short range CASM is directly rated to range.

For instance a 767-300 fuselage sitting on top of 757 sized wing and engines. It wouldn't fly very far but it would be extremely efficient at any distance it could fly.

The opposite a 757-300 fuselage sitting on 767 sized wings and engines could fly 8000+nm however it would not be efficient on a 1000nm trip.

Boeing can simply size the wing so the stretch model has a very low range with max payload. That means Boeing can hit any CASM target they want by simply optimising around a lower fuel load and lower maximum takeoff weight.

If Boeing finds 50% of the NMA flights will be under 1500nm then we may see a 767-300 sized fuselage on top of 757 sized wings and engines. As the fuselage makes up less than half of the aircrafts weight then this 797-10 would be closer to the 753's empty weight than the 763's. Half way is 75T so probably closer to 70T. This would be the super efficient tight 8ab people mover for those 1500nm trips. The A321 with its higher 3500nm design range would be at a disadvantage. A larger winged longer ranged A322 even more so.

Then you would have the shorter 762 sized cabin version the 797-9. You'd save 3-4T in fuselage weight straight off the bat. With 50 less passengers saves another 5T in payload. This frees up 8T for extra fuel that the stretch couldn't carry. Range would go up around that of the A321.

The 797-8 would then be the shrink. More fuselage weight saved and less passenger weight would allow the 757 sized wings to be finally be filled to full capacity. Depending on its length it could be similar capacity to the A321LR but with 5000+nm range. Or it could be A322 sized with 4500+nm range. Either way it would be a step above.

In summary 120T maximum takeoff 70-75T OEW
797-8 250 seat economy, 200 seat 2 class, 5000nm,
797-9 300 seat economy, 240 seat 2 class, 3500nm,
797-10 350 seat economy, 280 seat 2 class, 2000nm,


I really appreciate your comments on this thread. I have never seen a chart like the one you created. I also appreciate your responses to someone who is playing devils advocate against the rumored configuration from Boeing.

I am excited to see what Boeing comes up with for range, capacity, and payload. I am also intrigued to find out what parts will be composite and how it will be fabricated. I am also wondering how they will find a way to keep production costs low. I imagine many more robots inside the Boeing factories versus the outsourcing strategy used on the 787. It is an exciting time!


Automation is the key, Its where Boeing is going next, how to assemble a plane quicker and with less personnel. One of the reasons why I think the 797 has come first before the 737 replacement, to get this process done right. Pretty sure Airbus is working on the same thing.

It's funny watching Keejse argue for a Boeing NB when he brought us the well thought out, and plausible Boeing WB Ecoliner Concept :lol: :lol: :lol: :lol:

viewtopic.php?t=775819

You are right Newbie, exciting times ahead.
 
RJMAZ
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Joined: Sat Jul 09, 2016 2:54 am

Re: Boeing officially forms program office to flesh out 797 plans

Mon Dec 11, 2017 10:37 pm

william wrote:
It's funny watching Keejse argue for a Boeing NB when he brought us the well thought out, and plausible Boeing WB Ecoliner Concept.

Yes the big winged narrowbody concept with its 5000nm range could never have great CASM on a short 1000nm flight.

These short flights would make up the majority of flights that the MOM aircraft would fly. That big wing and large fuel capacity is a disadvantage.

The obvious solution for Airbus to create an efficient aircraft for routes under 1500nm is to just simple stretch the A321NEO keeping the current 97T MTO limit.


A321's empty weight: 50,800kg
240 passengers: 24,000kg
Fuel in wing and wingbox tanks is 18,600kg
Total: 93400kg

As you can see there is 4600kg free headroom before you hit the maximum takeoff weight. Some airlines fit one or two aux fuel tanks in the cargo hold. In the case of the A321LR they fit 3 aux tanks and have a lower density cabin. The original A321 had a 93.5T maximum takeoff weight so it couldn't carry more than one tank.

Stretching the A321 up to a full 5 metres would be relatively easy with that much headroom. The 737-9 was maxed out and Boeing still managed a 737-10.

If we're talking under 1500nm flights Airbus wouldn't need 18,600kg of fuel either. So there is plenty of room to stretch it up to 280 seats max density or 250seat medium density cabin. Tail strike issues could be easily solved in software. The only big issue would be the landing weight.
 
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seahawk
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Re: Boeing officially forms program office to flesh out 797 plans

Tue Dec 12, 2017 7:04 am

The problem is we do not know what the majority of MoM missions will be. below 1000nm, 2000nm or more around 3000nm or maybe even more? One should not forget that the whole MoM idea started when airlines asked for something 757-200 sized with comfortable TATL range.
 
RJMAZ
Posts: 691
Joined: Sat Jul 09, 2016 2:54 am

Re: Boeing officially forms program office to flesh out 797 plans

Tue Dec 12, 2017 7:38 am

That is why I predict there will be 3 fuselage lengths with very large length differences between each one. As a result we will see a massive difference in range between the shortest and longest models. So Boeing can cover everything from 1000nm short hops to transatlantic at a full load into the wind.

Airlines can then choose depending on their network which models to buy. With high commonality of 90+% they would probably buy all three.

Qantas for example would most likely operate
mostly the short range stretch model as it could cover all the very thick domestic work and to New Zealand. They probably wouldn't order the longest range shrink model because it would lack the legs to do international routes to say Singapore, Vietnam, Japan.

Where as US3 would operate the long range shrink model to go transatlantic.
 
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seahawk
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Re: Boeing officially forms program office to flesh out 797 plans

Tue Dec 12, 2017 7:45 am

The problem with this is that according to the known market research less than 15% of all interested airlines want more than 250 seats, while over 50% asked for less than 200 seats.
 
flipdewaf
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Re: Boeing officially forms program office to flesh out 797 plans

Tue Dec 12, 2017 10:04 am

The problem I see with trying to justify an aircraft with twice as many aisles, 60-70% extra seats that can simply match the CASM of the smaller aircraft to enable a reduction of frequencies and not a lot else, is that it isn't enticing for the airlines to actually want to take that risk.

The real challenge is determine whether I'm talking about the
A321NEO vs RJMAZ _797-10
or
77W vs A380.

If the smaller plane either matches or has slightly higher CASM then that is the "winner"

Fred
Image
 
Eyad89
Posts: 353
Joined: Fri Sep 02, 2016 10:47 pm

Re: Boeing officially forms program office to flesh out 797 plans

Tue Dec 12, 2017 11:08 am

RJMAZ,

I do appreciate all the calculations and efforts you have put into this topic thus far, as they are detailed and well written, but I still disagree with some of your points.

RJMAZ wrote:
So I plotted the aircraft numbers. As we can see there is a consistent link between the range of the aircraft and the empty weight per passenger.


I think we are confusing correlation with causation here. Range is mainly determined by fuel capacity and the rate of fuel consumption. If an airplane can tank in more fuel, then it is more likely to be bigger in size and heavier than those planes that have less range, otherwise it wouldn't be physically possible to tank in more fuel.
So range is a product of size and weight, and number of passengers is also a product of size and weight, but linking range to the number of passengers does not make sense. Sure, there is a correlation, but none of them is caused by the other.

RJMAZ wrote:

Also I created another table where I divided the empty weight per passenger by its range. I then placed them in order of range and the graph perfectly shows the relationship.


I honestly don't see why you are dividing by range if we are talking about the market of 5,000 nm maximum. All what you saying here is that dividing by a bigger value of range results in a smaller ratio of weight/passenger/ range. Of course it will, as you are dividing by a gigantic value (the denominator). What is the significance of this ratio anyway? What does it tell us here? and what does this have to do with choosing the right size for a short-ranged NMA?


RJMAZ wrote:
The design range of the aircraft is the biggest factor in CASM.


Allow me to completely disagree with this. Again, please refer to the correlation vs causation argument above . If range is the biggest factor in CASM, then how could 779 have a much better CASM than 77W even though they share the exact same range. And How come 789 has a better CASM than A333/9 even though it has a longer range?

The main cause-and-effect link between range and weight is that heavier planes are more likely to have larger fuel capacity due to their bigger size. range is simply a product of weight, and CASM is also a product of weight, but range and CASM are not directly related.

RJMAZ wrote:
In terms of the Boeing 797 widebody. If the stretch has a max range of 3500nm then it is highly likely to have better CASM than a 4000nm max range narrowbody.



We have gone through this multiple times. It seems we will agree to disagree here. I still think this statement is impossible based on numbers, and you could have your different opinion regarding the matter of course.

This isn't about Boeing or Airbus. It's about a 757-sized aircraft vs a 767-sized aircraft that can carry 200+ passengers up to 4,500 - 5,000 nm maximum. If Boeing is to start a clean-sheet design using the best technology they can get their hands on in terms of CFRP, aerodynamics, engine choices, etc, which aircraft would more likely sell more? To me personally, I still see it as a 757 successor. Let's keep A vs B out of this question.
 
RJMAZ
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Joined: Sat Jul 09, 2016 2:54 am

Re: Boeing officially forms program office to flesh out 797 plans

Tue Dec 12, 2017 11:50 am

seahawk wrote:
The problem with this is that according to the known market research less than 15% of all interested airlines want more than 250 seats, while over 50% asked for less than 200 seats.

At what density though?

JAL has only 186 seats in their 787-8. https://www.seatguru.com/airlines/Japan ... 7-800.php#

AA's has only 102 seats in their transcon A321 fleet.
https://www.seatguru.com/airlines/Ameri ... 1_new.php#

The numbers we throw around for consistency is 28-30" pitch full economy cabin. This is simply for comparison purposes only. 2 class and 3 class cabins will have a significantly lower seat count.

Usually the longer the flight, the more spacious the cabin will be with a larger percentage of the cabin dedicated to business class seats. Let's say the
797-8/9/10 has 250/300/350 seats all economy. In real life that will probably end up being 150/220/290 seats. The 787-8 being longer range will have a huge portion of the cabin dedicated to premium seats. Where as the 787-10 for short flights would probably only have a couple rows of slightly wider recliner seats.

Passengers on average are less likely to upgrade to a business class seat on a short domestic flight.

flipdewaf wrote:
The problem I see with trying to justify an aircraft with twice as many aisles, 60-70% extra seats that can simply match the CASM of the smaller aircraft to enable a reduction of frequencies and not a lot else, is that it isn't enticing for the airlines to actually want to take that risk.

The real challenge is determine whether I'm talking about the
A321NEO vs RJMAZ _797-10
or
77W vs A380.

If the smaller plane either matches or has slightly higher CASM then that is the "winner"

Fred

Two 15" aisles means 30" of aisle versus one 22" aisle in the A320. That's not twice the aisle. 2-4-2 acts like a pair of 2-2 cabins so each aisle can be narrower. Than the aisle in a 3-3.

The A380 reduction in frequency is a bad example. We are talking 20+ daily 737 flights where they have flights 15 minute apart in the peak. Upgauging to say 12 797-10 flights with equal CASM is a huge improvement. Less fees and pilots etc

Upgauging from say 7 weekly 777 flights to 4 A380 flights. Some days there would be no flights. Even if the A380 had better CASM it probably wouldn't be a good idea.

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