flipdewaf wrote:

seabosdca wrote:

For this aircraft, an oval fuselage isn't an "exotic" feature to leave out when price negotiations get down to brass tacks. It's the core of the business case. Take it away and you have a 767 MAX with pretty wings, which Boeing knows perfectly well has no hope of competing on operating economics with the A321neo.
.

So the question is...
Does the reduced lift independent drag outweigh both the increase in induced drag due to increased fuselage weight and the reduced versatility of a smaller cargo compartment?

Fred

Revelation wrote:

TTailedTiger wrote:

B777LRF wrote:

Reading the quote you posted, it states rather clearly that Boeing is presenting the airlines with a blank sheet of paper, asking them what they'd like. That's pretty much as far removed from payload/range charts, performance numbers, timelines and what have you, as it gets. And the bit about 'scheduled to enter service in 2025' is yet more marketing fluff; and as anyone who's been following aviation for the last decade will testify, you don't go from a blank piece of paper to 'enter service' in 7 years. That's before we even get to the crux of the matter, which is lack of a suitable engine. RR are knee-deep in doo-doo with the Trent which is bound to the delay the 'superfan'; PW are in the same situation with the GTF and are not in a position to up-gauge that engine any time soon, and GE doesn't even remotely have something in the pipeline. Which means, at present the only propulsion on offer is, indeed, marketing hot air.

PS
I too have been on a team buying aircraft from Boeing.

So then you don't believe Boeing will receive any engine proposals that are due soon?

Especially since they've already gotten a first set of proposals from all three engine vendors?

It's not hard to see CFM propose a scaled up LEAP with the CMC hot section components from GE9x that Lightsaber tells us are as much of a game changer as GTF is.

RR actually is on schedule with SuperFan, see our discussion earlier in this thread.

Agree...


If anyone is a non-starter, I'd have to say its PW. Their track record was bad before GTF and now it's atrocious.

PS: Blank piece of paper? B777LRF has gone from off target to ridiculous.

B777LRF wrote:

musman9853 wrote:

marcelh wrote:

Do we have a reliable engine?

P&W,RR,and GE/CFM have all submitted engine proposals. IMO GE/CFM is a lock, but i'm not sure rr or p&w gets the other option. my moneys on rr tho

'Proposals', well, according to several sources GE are not sure there's a business making it worth their while. RR's SuperFan is still an R&D project, and PW need to get their shyte together before anyone will take them seriously.

What Boeing asked for is an engine weighing x amount of kilograms, producing x amount of thrust with a TSFC in this or that ballpark. And the engine OEMs submitted a paper saying 'sure, we can do that'. That's about as fluffy as Boeing's non-solid 797 'proposals'.

TTailedTiger wrote:

I am excited with the prospect of traditionally narrowbody only airlines ordering the 797 for upguaging current capacity as well as going into new city pairs. I could definitely see airlines like Alaska and Copa ordering the 797 to expand their operations now that a smaller and highly efficient widebody is available. Perhaps Southwest would be interested in it for Hawaii and South America. But I doubt we would ever see them start service to Europe or Asia. Ryanair could also be a good candidate. I also think it might make sense for GOL. It would be a nice fit for JetBlue but they are attached at the hip to Airbus.

mffoda wrote:

Another article to add to the discussion...

https://thewest.com.au/news/aviation/bo ... b88994564z

RJMAZ wrote:

flipdewaf wrote:

seabosdca wrote:

For this aircraft, an oval fuselage isn't an "exotic" feature to leave out when price negotiations get down to brass tacks. It's the core of the business case. Take it away and you have a 767 MAX with pretty wings, which Boeing knows perfectly well has no hope of competing on operating economics with the A321neo.
.

So the question is...
Does the reduced lift independent drag outweigh both the increase in induced drag due to increased fuselage weight and the reduced versatility of a smaller cargo compartment?

Fred

It would definitely be worth the going oval.

Medium to long thin routes usually have very little demand for cargo other than passenger bags. It is highly likely the 797 will not be built for cargo.

A 787-8 taking off with maximum payload weight can only fill its fuel tanks to approximately 65% capacity before hitting MTOW. The 787-8 would struggle to fly between two airports 5000nm apart which is well inside the MOM range window. The 797 could fly that same route but with passengers and bags only in a 3 class cabin.

On a 4000-5000nm MOM range route you can use the 787-8 if you need cargo or the 797 if you dont need cargo. They would compliment each other nicely, it would be silly for Boeing to build the 797 as a big cargo mover when you have the 787. You would lose efficiency by adding cargo volume to the 797.

Also regarding structural efficiency and weight of an oval: The fineness ratio usually takes the width to length of an aircraft. The 797 of reduced height cross section might have a normal finesness ratio when viewed from the side but a short and stubby A310 fineness ratio when viewed from the top. As the oval would not be as strong when it comes to bending Boeing can simply make it stubby. That is why i think it will definitely be a tight 8ab cross section with a reduced height lower lobe.

It would definitely be worth the going oval.

Boeing has pushed back an announcement over pursuing the New Midsize Airplane (NMA) until sometime in 2019, but increasingly, financial analysts are seeing the new aircraft as a fait accompli.

mffoda wrote:

Another article to add to the discussion...

https://thewest.com.au/news/aviation/bo ... b88994564z

RJMAZ wrote:

flipdewaf wrote:

seabosdca wrote:

For this aircraft, an oval fuselage isn't an "exotic" feature to leave out when price negotiations get down to brass tacks. It's the core of the business case. Take it away and you have a 767 MAX with pretty wings, which Boeing knows perfectly well has no hope of competing on operating economics with the A321neo.
.

So the question is...
Does the reduced lift independent drag outweigh both the increase in induced drag due to increased fuselage weight and the reduced versatility of a smaller cargo compartment?

Fred

It would definitely be worth the going oval.

Medium to long thin routes usually have very little demand for cargo other than passenger bags. It is highly likely the 797 will not be built for cargo.

A 787-8 taking off with maximum payload weight can only fill its fuel tanks to approximately 65% capacity before hitting MTOW. The 787-8 would struggle to fly between two airports 5000nm apart which is well inside the MOM range window. The 797 could fly that same route but with passengers and bags only in a 3 class cabin.

On a 4000-5000nm MOM range route you can use the 787-8 if you need cargo or the 797 if you dont need cargo. They would compliment eachother nicely, it would be silly for Boeing to build the 797 as a big cargo mover when you have the 787. You would lose efficiency by adding cargo volume to the 797.

Also regarding structural efficiency and weight of an oval: The fineness ratio usually takes the width to length of an aircraft. The 797 of reduced height cross section might have a normal finesness ratio when viewed from the side but a short and stubby A310 fineness ratio when viewed from the top. As the oval would not be as strong when it comes to bending Boeing can simply make it stubby. That is why i think it will definitely be a tight 8ab cross section with a reduced height lower lobe.

morrisond wrote:

RJMAZ wrote:

flipdewaf wrote:

So the question is...
Does the reduced lift independent drag outweigh both the increase in induced drag due to increased fuselage weight and the reduced versatility of a smaller cargo compartment?

Fred

It would definitely be worth the going oval.

Medium to long thin routes usually have very little demand for cargo other than passenger bags. It is highly likely the 797 will not be built for cargo.

A 787-8 taking off with maximum payload weight can only fill its fuel tanks to approximately 65% capacity before hitting MTOW. The 787-8 would struggle to fly between two airports 5000nm apart which is well inside the MOM range window. The 797 could fly that same route but with passengers and bags only in a 3 class cabin.

On a 4000-5000nm MOM range route you can use the 787-8 if you need cargo or the 797 if you dont need cargo. They would compliment eachother nicely, it would be silly for Boeing to build the 797 as a big cargo mover when you have the 787. You would lose efficiency by adding cargo volume to the 797.

Also regarding structural efficiency and weight of an oval: The fineness ratio usually takes the width to length of an aircraft. The 797 of reduced height cross section might have a normal finesness ratio when viewed from the side but a short and stubby A310 fineness ratio when viewed from the top. As the oval would not be as strong when it comes to bending Boeing can simply make it stubby. That is why i think it will definitely be a tight 8ab cross section with a reduced height lower lobe.

I still say it will be a tight 7W with small lower lobe so they can reuse the cross section and nose on NSA (albeit with different wing, tail and wingbox most likely). It just makes too much financial sense to not do this and then have a lot of commonality between NMA and NSA.

Revelation wrote:

AvWeek: Boeing's New Midsize Airplane Will Happen, Say Analysts is registering a shift in sentiments:

Boeing has pushed back an announcement over pursuing the New Midsize Airplane (NMA) until sometime in 2019, but increasingly, financial analysts are seeing the new aircraft as a fait accompli.

It goes on to say:

“Airline views on this Boeing concept appeared increasingly positive to us, with the design parameters firming”
"Airlines appear to now be more interested in the NMA relative to current Airbus or Boeing products"
"This could lead to a more aggressive response by Airbus"
Expanding Boeing Global Services is seen as smoothing out development cycles even if it raises interim risk levels
NMA provides a proper response to A321
NMA provides a lower risk for the eventual 737 replacement
50% of suppliers surveyed see a 2019 NMA release whereas 10% do not
Only 20% of suppliers say they are not in discussions with Boeing on NMA

2019 should be an interesting year.

seahawk wrote:

16,5 will work for economy minus.

skystar767 wrote:

I don’t think this plane should be a wide body. A narrow body would be much better for Boeing. It would replace the 757 which most airlines around the world liked. The 737 max too low the 787 too big. I thing the 797 narrow body would give the A321lr a run for its money.

seahawk wrote:

I can easily see Boeing trading seat width for the comfort of an extra aisle. And if the pre-launch focus links passenger comfort to the volume of overhead bins, I am always sceptical. So yes, I would not be surprised to see them go below 17".

Revelation wrote:

skystar767 wrote:

I don’t think this plane should be a wide body. A narrow body would be much better for Boeing. It would replace the 757 which most airlines around the world liked. The 737 max too low the 787 too big. I thing the 797 narrow body would give the A321lr a run for its money.

Sounds like you've never been in the last row of an A321 or 757-300 waiting for 200+ pax in front of you to deplane...

seahawk wrote:

16,5 will work for economy minus.

flipdewaf wrote:

So the question remains wholly unanswered: Does the reduced lift independent drag outweigh both the increase in induced drag due to increased fuselage weight and the reduced versatility of a smaller cargo compartment?

You have characterised the market well and I accept that there is little need for cargo on the particular market the 797 is aimed at. The issue isnt with bending it is with pressurisation and the increased weight which is not being taken account of.

Stitch wrote:

seahawk wrote:

I can easily see Boeing trading seat width for the comfort of an extra aisle. And if the pre-launch focus links passenger comfort to the volume of overhead bins, I am always sceptical. So yes, I would not be surprised to see them go below 17".

Boeing would only trade it if airlines demanded it and I don't seem them doing so because otherwise we would have 8-abreast 767s, 9-abreast A330s and 10-abreast A350s as the "normal" configuration.

Stitch wrote:

A "tight 8" means a 767 cross section at minimum and while this plane does seem to be designed around being a true 767 successor, the world's majors all appear to have set a minimum width of 17 inches / 43 centimeters so I expect that even if Boeing does with a 767 cross-section in the main cabin, you will see 2+3+2 by almost all operators.

RJMAZ wrote:

The 767 is 26% less area than the A330 and 13% less area than the 767.

Cross section area per passenger would be a good metric for efficiency. Assuming 8ab and 7ab for the A330 and 767.

A330 - 31,250 cm2 per seat
767 - 30,570 cm2 per seat
797 - 23,125cm2 per seat
A321 - 21,500cm2 per seat

So a tight 8ab double bubble reduced height fuselage with LD3-45's height containers that are maybe a foot or two wider.

RJMAZ wrote:

Stitch wrote:

A "tight 8" means a 767 cross section at minimum and while this plane does seem to be designed around being a true 767 successor, the world's majors all appear to have set a minimum width of 17 inches / 43 centimeters so I expect that even if Boeing does with a 767 cross-section in the main cabin, you will see 2+3+2 by almost all operators.

That is not true. The 797 would have a much smaller cross section than the 767.

The 767 in 8 abreast uses 16.4" seats.

I predict the 797 will have a cabin 6" wider to allow standard 17" seats in 8ab.

The 767 fuselage is 5.03m wide but 5.41m tall.
The A330 fuselage is 5.64m circular.
The 797 I estimate to be 5.18m wide but only 4.5m tall. That is only 36cm taller than the A321.

Cross section area
A330 - 250,000 cm2
767 - 214,000 cm2
797 - 185,000 cm2
A321 - 129,000 cm2

The 767 wastes a lot of area to fit the LD2's with increased height.

The 767 is 26% less area than the A330 and 13% less area than the 767.

Cross section area per passenger would be a good metric for efficiency. Assuming 8ab and 7ab for the A330 and 767.

A330 - 31,250 cm2 per seat
767 - 30,570 cm2 per seat
797 - 23,125cm2 per seat
A321 - 21,500cm2 per seat

So a tight 8ab double bubble reduced height fuselage with LD3-45's height containers that are maybe a foot or two wider.

keesje wrote:

Average cabin width (without 20 inch aisle(s)) at shoulderheight per passenger would have my preference. Sidewall shape, armrest number/ width, aislewidth give too much opportunity for creativity / perception management with seat(bottom, cushion)width.

RJMAZ wrote:

keesje wrote:

Average cabin width (without 20 inch aisle(s)) at shoulderheight per passenger would have my preference. Sidewall shape, armrest number/ width, aislewidth give too much opportunity for creativity / perception management with seat(bottom, cushion)width.

I disgree. Aisle width can and should vary.

A 2-3-2 economy cabin can use narrower aisles than say 3-5-3 economy cabin. To use the same width aisle on both is unfair against narrower aircraft.

Also a shorter aircraft can use narrower aisles. The long 757-300 desperately needed a wider aisle but that same aisle width works fine on the shorter 737-8.

A tight 8ab cabin on the 797 would have a fairly short fuselge length based on the published capacity numbers. Cabin length would probably be similar to a 737-10. As each aisle is effectively serving a 2-2 seating cabin it can be much narrower.

It would not surprise me if the 797 in 8ab had two 16" aisles. That is still more aisle area per passenger than the A320 family. You might have to walk slower down the aisle but having two aisles completely offsets this.

lightsaber wrote:

First excellent post. However, I'm recalling a 18" minimum width for evacuation paths. But I'm going from memory.

Lightsaber

HermansCVR580 wrote:

Wonder if Boeing will us any of the design from the Aurora D8? I Boeing has a partnership with them and that plane kind of fits the bill. Google Aurora Flight Science D8 there is a video of a mock-up interior also.

Revelation wrote:

skystar767 wrote:

I don’t think this plane should be a wide body. A narrow body would be much better for Boeing. It would replace the 757 which most airlines around the world liked. The 737 max too low the 787 too big. I thing the 797 narrow body would give the A321lr a run for its money.

Sounds like you've never been in the last row of an A321 or 757-300 waiting for 200+ pax in front of you to deplane...

Strato2 wrote:

Revelation wrote:

skystar767 wrote:

I don’t think this plane should be a wide body. A narrow body would be much better for Boeing. It would replace the 757 which most airlines around the world liked. The 737 max too low the 787 too big. I thing the 797 narrow body would give the A321lr a run for its money.

Sounds like you've never been in the last row of an A321 or 757-300 waiting for 200+ pax in front of you to deplane...

I'd certainly rather have a couple of minutes extra de-boarding time than a Boeing economy class seating standard for several hours.

keesje wrote:

Put in "18 inch" seats, 16 inch aisle(s), three seaters, incoming sidewalls, 28-29 inch pitch ultra slim seats and big IFE seat boxes and you will have the most miserable 18 inch seat experience of your life. You'll hang over into the aisle(s) and there the trolley and fellow passengers are unsuccessfully trying to not hit you all flight. And the airline will say the have industry standard width seats, 18 inch. Taking the public & media for a ride.



Nobody is advertising their seatwidth boosting, half width armrest.

keesje wrote:

Put in "18 inch" seats, 16 inch aisle(s), three seaters, incoming sidewalls, 28-29 inch pitch ultra slim seats and big IFE seat boxes and you will have the most miserable 18 inch seat experience of your life. You'll hang over into the aisle(s) and there the trolley and fellow passengers are unsuccessfully trying to not hit you all flight. And the airline will say the have industry standard width seats, 18 inch. Taking the public & media for a ride.

Marketing departments will try to make anything sound good.

I think you're taking the reality of an Air Asia X A330/A330neo and trying to project it on to NMA, before we even know NMA's actual dimensions.

keesje wrote:

I think you're taking the reality of an Air Asia X A330/A330neo and trying to project it on to NMA, before we even know NMA's actual dimensions.

Asia XA330neo? To be honest I have no idea what you are referencing Revelation.

seahawk wrote:

Who cares about comfort for economy class? It can be miserable.

skystar767 wrote:

I don’t think this plane should be a wide body. A narrow body would be much better for Boeing. It would replace the 757 which most airlines around the world liked. The 737 max too low the 787 too big. I thing the 797 narrow body would give the A321lr a run for its money.