RJMAZ
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Re: Boeing CEO: NMA will

Thu Feb 13, 2020 10:41 am

morrisond wrote:
You are basically saying the 7W burns 15% more fuel as the tail is bigger/heavier - that just doesn't seem right.

You clearly don't get it.

I will try and explain it.

Lets say you have a wing and engine combo that can have a MTOW of 100t. The 7ab fuselage might add only 1000kg at the same seating capacity. But it is shorter so the tail might be only 500kg heavier. But this is where the loop begins.

That 1500kg of extra empty weight is now taken out of the fuel carried, remember the MTOW is fixed at 100t. If the OEW, payload and fuel is split 50/25/25 then that means that extra empty weight reduces fuel capacity by 6%. The extra drag for the shorter and wider fuselage combined with this reduced fuel would easily see range drop by 10%.

Now to make the comparison fair the 7ab needs to gain back that 10% range. The extra fuel requires a slightly higher MTOW. That requires a slightly bigger wing and slightly more powerful engines. The empty weight has now increased a second time. The extra thrust requires the tail to be enlarged again. The fuel capacity needs to be increased even further but this time by smaller and smaller amounts as the loop continues.

The loop eventually ends up with the 7ab design burning 15% more fuel and a tail that is 4500lb heavier.

The same loop can be used to optimise a cleansheet design for a shorter range.

For instance a 787-8 sized fuselage that was FULLY optimised for 5000nm range would see the empty weight reduced by 20% and the fuel burn per seat would be improved by over 10%. It would take another 20 years for engine technology to get that same 10% gain. So optimisation of a design is huge.

Derating an existing design by reducing MTOW does not reduce fuel burn it simply reduces engine maintenance and landing fees. See the 787-3 as a bad example of of a derated design not an optimised design.
 
JonesNL
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Re: Boeing CEO: NMA will

Thu Feb 13, 2020 11:10 am

RJMAZ wrote:
morrisond wrote:
You are basically saying the 7W burns 15% more fuel as the tail is bigger/heavier - that just doesn't seem right.

You clearly don't get it.

I will try and explain it.

Lets say you have a wing and engine combo that can have a MTOW of 100t. The 7ab fuselage might add only 1000kg at the same seating capacity. But it is shorter so the tail might be only 500kg heavier. But this is where the loop begins.

That 1500kg of extra empty weight is now taken out of the fuel carried, remember the MTOW is fixed at 100t. If the OEW, payload and fuel is split 50/25/25 then that means that extra empty weight reduces fuel capacity by 6%. The extra drag for the shorter and wider fuselage combined with this reduced fuel would easily see range drop by 10%.

Now to make the comparison fair the 7ab needs to gain back that 10% range. The extra fuel requires a slightly higher MTOW. That requires a slightly bigger wing and slightly more powerful engines. The empty weight has now increased a second time. The extra thrust requires the tail to be enlarged again. The fuel capacity needs to be increased even further but this time by smaller and smaller amounts as the loop continues.

The loop eventually ends up with the 7ab design burning 15% more fuel and a tail that is 4500lb heavier.

The same loop can be used to optimise a cleansheet design for a shorter range.

For instance a 787-8 sized fuselage that was FULLY optimised for 5000nm range would see the empty weight reduced by 20% and the fuel burn per seat would be improved by over 10%. It would take another 20 years for engine technology to get that same 10% gain. So optimisation of a design is huge.

Derating an existing design by reducing MTOW does not reduce fuel burn it simply reduces engine maintenance and landing fees. See the 787-3 as a bad example of of a derated design not an optimised design.


This is like basic engineering 101, same applies on cars, boats, etc. More seats-> heavier design -> bigger engines -> bigger brakes -> bigger suspension -> bigger tires... You cant increase weight on 1 part without impacting other parts. Especially not on something that is so weight sensitive as planes...
 
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seahawk
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Re: Boeing CEO: NMA will

Thu Feb 13, 2020 11:20 am

moa999 wrote:
But what is that 30" aisle doing for your efficiency and casm?. Remember this aircraft won't compete with today's 320neo,321LR/XLR but tomorrow's.

What if Airbus also takes the new engine, stretches to 322 using lighter panels and rewings with a folding tip - all at a lot less cost to them.


The wide aisle won´t happen.

If you really want to fly routes over 3000nm with it, the turnaround is not a huge topic either way and if your board from door 2 the pax in the premium seats in the front will be happy enough. This door also helps with your evacuation time. If you want to use it in a high density configuration on short routes, you simply use a bus gate and board from the front and the back. Even the Devil´s pencil aka 753 can be turned around in 35 minutes doing so.
 
planecane
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 11:21 am

I think production methods and cost are the key to the NMA competing successfully with the A321XLR/future A322. IF they are able to "design for production" and reduce the manufacturing costs to significantly less than Airbus can do (both from their operating philosophy and the fact that they are still building essentially the same structure that they have since the A320 was first built), they can compete with lower sales prices even if the performance was only slightly better or the same as the competition.

If, hypothetically, Boeing could sell the NMA 10% cheaper than the A321XLR, that would be around $6 million per unit. An airline ordering 100 would save $600 million plus interest. That would be very significant.

In general, I'd say keesje has been correct for all of these years about the wide narrowbody concept.
 
morrisond
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Re: Boeing CEO: NMA will

Thu Feb 13, 2020 1:36 pm

JonesNL wrote:
RJMAZ wrote:
morrisond wrote:
You are basically saying the 7W burns 15% more fuel as the tail is bigger/heavier - that just doesn't seem right.

You clearly don't get it.

I will try and explain it.

Lets say you have a wing and engine combo that can have a MTOW of 100t. The 7ab fuselage might add only 1000kg at the same seating capacity. But it is shorter so the tail might be only 500kg heavier. But this is where the loop begins.

That 1500kg of extra empty weight is now taken out of the fuel carried, remember the MTOW is fixed at 100t. If the OEW, payload and fuel is split 50/25/25 then that means that extra empty weight reduces fuel capacity by 6%. The extra drag for the shorter and wider fuselage combined with this reduced fuel would easily see range drop by 10%.

Now to make the comparison fair the 7ab needs to gain back that 10% range. The extra fuel requires a slightly higher MTOW. That requires a slightly bigger wing and slightly more powerful engines. The empty weight has now increased a second time. The extra thrust requires the tail to be enlarged again. The fuel capacity needs to be increased even further but this time by smaller and smaller amounts as the loop continues.

The loop eventually ends up with the 7ab design burning 15% more fuel and a tail that is 4500lb heavier.

The same loop can be used to optimise a cleansheet design for a shorter range.

For instance a 787-8 sized fuselage that was FULLY optimised for 5000nm range would see the empty weight reduced by 20% and the fuel burn per seat would be improved by over 10%. It would take another 20 years for engine technology to get that same 10% gain. So optimisation of a design is huge.

Derating an existing design by reducing MTOW does not reduce fuel burn it simply reduces engine maintenance and landing fees. See the 787-3 as a bad example of of a derated design not an optimised design.


This is like basic engineering 101, same applies on cars, boats, etc. More seats-> heavier design -> bigger engines -> bigger brakes -> bigger suspension -> bigger tires... You cant increase weight on 1 part without impacting other parts. Especially not on something that is so weight sensitive as planes...


I fully understand this principle. I understand the calculations are circular.

However, if you keep your thumb on the scale and ignore certain things yes that is what the result will be. Let me try one more time.

The analysis is coming up with a fuselage that is 1,000KG I agree with that. However the analysis is not giving any credit for shorter cable runs or shorter gear.

So let us take two separate frames and forget the tail for a second. Same wing same engines.

One WB with 300 seat Capacity and 20' shorter than an 300 Seat NB.

The WB has 3% less wetted area and about 19% more frontal area, however the Wetted area calculation I did in tech ops takes the frontal area into account. Same drag off the main engines/ main wing.

Two good articles from NASA here https://www.grc.nasa.gov/www/k-12/airplane/sized.html https://www.grc.nasa.gov/www/k-12/airplane/drageq.html Basically no one knows what is most important - you have to put them in a windtunnel.


Sitting on the runway the WB could have 1,000KG more fuselage weight. It could be less it could be more. But I will accept 1,000KG

Cable/electrical/servicing runs would be 20' shorter going from the Cockpit to the Tail and 10' shorter from the Wing section to the cockpit or to the tail.

I have no idea how much weight that is - but it would be less - 100-200KG? BTW this article says a typical WB has about 7,400KG in wiring. https://aerospaceamerica.aiaa.org/featu ... on-wiring/

The WB is about 10% less in length. So a savings of 300-400 KG is not unrealistic as they could be talking about a really big WB.

To achieve the same rotation angles as the tail is shorter the WB could have have significantly shorter gear. This could save a bunch of weight.

Let us assume it makes up the difference to the 1,000KG.

So you have two aircraft (sans tails) with identical weights and the WB has less wetted area than the NB, and could be more efficient as more of a teardrop.

Yes the Tail has to be bigger to account for the shorter airplane. But it won't be 50% bigger and weigh 3,500 lbs more. It may just make up for the WB having 3% less wetted area.

There is no way it would burn 15% more fuel.
 
2175301
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Re: Boeing CEO: NMA will

Thu Feb 13, 2020 2:28 pm

morrisond, JonesNL,RJMAZ

Concerning the above discussion on theoretical performance of different scenarios.

One of the things that colleges and universities fail to teach is that in almost all cases the equations being used are "best fit" equations to known data; and have an accuracy of how well they fit the data. Somewhere filed in the scientific libraries are the papers that derived those equations, and they almost always include an accuracy to all data number.

I'd be stunned if the accuracy of any of those equations was 5% or less. Often equations are accurate to 10-20% (and some are only accurate to 30%); which works for most practical things in life without much difficulties.

If better accuracy is required (in fields such as aerospace) then models and even full scale equipment is tested with highly accurate test equipment. In aerospace - its wind tunnel testing, which I suspect can get within 2.5% accuracy (and perhaps less depending on the accuracy of the test equipment and methods).

One of my expertise is highly accurate heat exchanger testing. Most plants have a hundred dollars of temperature instruments, and perhaps a few thousand dollars of flow instruments. I can show up with $50,000+ of extremely accurate temperature instruments and much better flow instruments (which can cost between $10,000 - $200,000 depending on the application) and show that the heat exchanger is performing often 10-20% better/worse than designed; and all of that can be traced to the inaccuracies of the equations being used. The largest uncertainties are in the fluid flow equations; which are the same equations used for airflow (and most design and plant engineers are stunned when I show them the papers where the equations were developed from and the uncertainty range to know accurate test results.

I would suggest that while it's great to talk about the theoretical trad-offs of doing this or that; that in reality in my opinion much of what you are describing is likely within the error margins of the equations and it takes wind tunnel testing to figure out the actual answers on which configuration/model is best.

There are very few equations in science and physics that are developed solely based on theoretical basis that are considered highly accurate. When you hear that some result matches the equation... the real question is "how close" and with what accuracy was the test instruments (what is the total accuracy of the test).

In the case of heat exchanges. Calculating the heat rate capacity of a heat exchanger is a few apparently straight forward equations. Calculating the total test uncertainty is about 50 times more complex; and there are to the best of my knowledge only 3 people in the USA who understand all the complexities and what needs to be done to calculate a highly accurate total test uncertainty (yes there are industry documents on what to do and factors to consider; but, the average engineer gets overwhelmed: It took me years to learn).

Have a great day,
 
FluidFlow
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 2:29 pm

Shorter gear will not work the problem will not be the rotation angle but the ground clearance for the nacelles. This limits or actually dictates the gear length.

Check out the tail of the A310. It is massive compared to the aircraft lenght. Thats the dimensions you look at. Thats a lot of tail for such a small aircraft. If you need to stay under 100t to avoid 8 main landing wheels, which adds a lot of weight you box yourself in a lot with a stumpy ovoid and if you go above you might as well go up until 130-150t MTOW and then the design becomes too big for NB gates and also too potent to be competitive at short hops <1500nm
 
morrisond
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Re: Boeing CEO: NMA will

Thu Feb 13, 2020 2:36 pm

2175301 wrote:
morrisond, JonesNL,RJMAZ

Concerning the above discussion on theoretical performance of different scenarios.

One of the things that colleges and universities fail to teach is that in almost all cases the equations being used are "best fit" equations to known data; and have an accuracy of how well they fit the data. Somewhere filed in the scientific libraries are the papers that derived those equations, and they almost always include an accuracy to all data number.

I'd be stunned if the accuracy of any of those equations was 5% or less. Often equations are accurate to 10-20% (and some are only accurate to 30%); which works for most practical things in life without much difficulties.

If better accuracy is required (in fields such as aerospace) then models and even full scale equipment is tested with highly accurate test equipment. In aerospace - its wind tunnel testing, which I suspect can get within 2.5% accuracy (and perhaps less depending on the accuracy of the test equipment and methods).

One of my expertise is highly accurate heat exchanger testing. Most plants have a hundred dollars of temperature instruments, and perhaps a few thousand dollars of flow instruments. I can show up with $50,000+ of extremely accurate temperature instruments and much better flow instruments (which can cost between $10,000 - $200,000 depending on the application) and show that the heat exchanger is performing often 10-20% better/worse than designed; and all of that can be traced to the inaccuracies of the equations being used. The largest uncertainties are in the fluid flow equations; which are the same equations used for airflow (and most design and plant engineers are stunned when I show them the papers where the equations were developed from and the uncertainty range to know accurate test results.

I would suggest that while it's great to talk about the theoretical trad-offs of doing this or that; that in reality in my opinion much of what you are describing is likely within the error margins of the equations and it takes wind tunnel testing to figure out the actual answers on which configuration/model is best.

There are very few equations in science and physics that are developed solely based on theoretical basis that are considered highly accurate. When you hear that some result matches the equation... the real question is "how close" and with what accuracy was the test instruments (what is the total accuracy of the test).

In the case of heat exchanges. Calculating the heat rate capacity of a heat exchanger is a few apparently straight forward equations. Calculating the total test uncertainty is about 50 times more complex; and there are to the best of my knowledge only 3 people in the USA who understand all the complexities and what needs to be done to calculate a highly accurate total test uncertainty (yes there are industry documents on what to do and factors to consider; but, the average engineer gets overwhelmed: It took me years to learn).

Have a great day,


Thanks and a great post.

That is exactly what NASA was getting at in the articles I posted above on Aero

BTW - I found a source of estimates of landing gear weight "The landing gear represents 2.5 to 5% of the MTOW " https://en.wikipedia.org/wiki/Landing_gear

So if we really only need to make up 600-700KG in weight (1,000kg -300-400 lost in wiring weight) - that would only be about .5% of MTOW.

If a short gear is 2.5% of MTOW then a long gear NB could only be less than a .5% increase in MTOW to come in under weight of the WB. You also have to take into account the wingbox/landing gear/nosegear bays could be lighter as shorter/lighter gear would put less stress on them accounting for a heavier tail.

Basically there is enough margin of error that there may be no penalty to doing a WB.
 
morrisond
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 2:43 pm

FluidFlow wrote:
Shorter gear will not work the problem will not be the rotation angle but the ground clearance for the nacelles. This limits or actually dictates the gear length.

Check out the tail of the A310. It is massive compared to the aircraft lenght. Thats the dimensions you look at. Thats a lot of tail for such a small aircraft. If you need to stay under 100t to avoid 8 main landing wheels, which adds a lot of weight you box yourself in a lot with a stumpy ovoid and if you go above you might as well go up until 130-150t MTOW and then the design becomes too big for NB gates and also too potent to be competitive at short hops <1500nm


The NB 300 Seat will be well above 100T.

The A310 has a tail height of 51'10", A300 54.9' and almost 7M longer.
 
morrisond
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 4:22 pm

morrisond wrote:
FluidFlow wrote:
Shorter gear will not work the problem will not be the rotation angle but the ground clearance for the nacelles. This limits or actually dictates the gear length.

Check out the tail of the A310. It is massive compared to the aircraft lenght. Thats the dimensions you look at. Thats a lot of tail for such a small aircraft. If you need to stay under 100t to avoid 8 main landing wheels, which adds a lot of weight you box yourself in a lot with a stumpy ovoid and if you go above you might as well go up until 130-150t MTOW and then the design becomes too big for NB gates and also too potent to be competitive at short hops <1500nm


The NB 300 Seat will be well above 100T.

The A310 has a tail height of 51'10", A300 54.9' and almost 7M longer.


If you look at the 787 ACAP https://www.boeing.com/resources/boeing ... ps/787.pdf it appears the gear got longer to accommodate the 20' longer 781 issues with rotation angle and it became semi-levered which I assume adds weight.

Quote "Due to the increased length of the -10, there is an increased risk of striking the tail on the runway, particular during takeoff. To reduce the chances of this happening, the main gear on the -10 is semilevered. This means that the aircraft can rotate over the aft wheels, not just the centre of the of the landing gear assembly." https://thepointsguy.co.uk/news/differe ... nd-787-10/

Pages 2-9 and Pages 2-10 it appears as though the 787-10 has longer(and probably stronger due to the higher max landing weight of 445,000 lbs vs 425,000 lbs) gear. It has nothing to to do with the nacelle's.

Dimension A is 24'4"-25'8" on 789 vs 26'-26'9" on 781

Dimension D is 5'9"-6'1" vs 6'6"-7'3"

Dimension M is 22'7"-23'5" vs 23'3"-23'8"
 
frmrCapCadet
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 4:25 pm

Had Boeing not messed up the 748, MAX, buybacks of half as much stock it would have had upwards of $100 billion to develop new planes. Almost but not quite the percent of waste of resources could be said of Airbus. Is it just the duopoly that allows such incompetence to stay in business?
Buffet: the airline business...has eaten up capital...like..no other (business)
 
morrisond
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 4:42 pm

frmrCapCadet wrote:
Had Boeing not messed up the 748, MAX, buybacks of half as much stock it would have had upwards of $100 billion to develop new planes. Almost but not quite the percent of waste of resources could be said of Airbus. Is it just the duopoly that allows such incompetence to stay in business?


Bascially yes - you are not wrong and unless they get developing quickly with new more advanced shaped frames the Chinese will catch up quickly. You have to assume from an Aero standpoint they would have stolen enough that the C919 will be pretty good as it uses the same engines.

Plus as we have discussed I'm sure they won't care what price they sell it at - it will just be a question of how many they can make and every one they can make will take away from B & A. By the end of this decade I believe they will have things sorted and unless Boeing and Airbus move on to new designs soon - they will have a problem.

A rewing A320 series may not be enough and B & A may need to move onto the more radical fuel saving shapes like Truss Braced or BWB or semi BWB.

But that would require them to innovate and spend some of that money. If Boeing chickens out on even going to something that isn't Circular on NMA - there is not a lot of hope.
 
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Revelation
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 4:49 pm

https://www.reuters.com/article/us-sing ... SKBN2071MR tells us that Boeing VP of marketing Randy Tinseth is retiring after 38 years of working for Boeing.

The timing could be reflective of a new CEO wanting his own person in the job, or it could be a coincidence.

Relevant to this thread, the article says:

Tinseth declined to be drawn into a discussion on the mid-sized airliner situation. “The dynamic has changed. I’ll leave it at that,” he said.

My inference is that the new Boeing CEO Calhoun and/or the new BCA President Deal are not fans of the NMA concept.

This is something Scott Hamilton has written on leehamnews.com.

In turn this supports the idea that they want someone who shares their thinking as head of marketing.

I don't think the XLR sales are what has turned things around.

It's been clear from 2011 that A321NEO would have better payload/range than MAX could achieve and once the XLR concept became viable it was clear that XLR would capture the 757 replacement market.

I think what has changed is that DM and McAllister are gone and Calhoun and Deal are in.
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Wake now, discover that you are the song that the morning brings
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DenverTed
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 5:00 pm

What's the optimally proportioned plane for an AL fuselage and large fan geared engines? I could see a fuselage with a ratio of 1:12, but once beyond that, gear height is not needed for for the engines so it is a penalty for rotation for going thinner. How about fuselage structure? The difference between the 777-200 and 777-300 required 50,000lb more in empty weight. There must be a point of diminishing returns where to add extra length the weight of structure required for bending is not worth it.
A 185' long 2-3-2 should be better than a 200' 3-3, or a 175' 3-3-3, for equal size cabin
 
morrisond
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 5:02 pm

Revelation wrote:
https://www.reuters.com/article/us-singapore-airshow-boeing-tinseth/jet-market-oracle-tinseth-bows-out-with-boeing-at-crossroads-idUSKBN2071MR tells us that Boeing VP of marketing Randy Tinseth is retiring after 38 years of working for Boeing.

The timing could be reflective of a new CEO wanting his own person in the job, or it could be a coincidence.

Relevant to this thread, the article says:

Tinseth declined to be drawn into a discussion on the mid-sized airliner situation. “The dynamic has changed. I’ll leave it at that,” he said.

My inference is that the new Boeing CEO Calhoun and/or the new BCA President Deal are not fans of the NMA concept.

This is something Scott Hamilton has written on leehamnews.com.

In turn this supports the idea that they want someone who shares their thinking as head of marketing.

I don't think the XLR sales are what has turned things around.

It's been clear from 2011 that A321NEO would have better payload/range than MAX could achieve and once the XLR concept became viable it was clear that XLR would capture the 757 replacement market.

I think what has changed is that DM and McAllister are gone and Calhoun and Deal are in.


And also this part of the quote "But he sees the trend towards lighter, nimble jets started by the 787 continuing. Such aircraft allow airlines to start new routes unavailable to thirstier, larger planes.

And it is a trend that has paid off for Boeing, which sold 1,485 Dreamliners. But lately it has been on the losing side of the same battle, as airlines rushed to buy the smaller Airbus A321XLR."

I agree it seems like NMA will smaller - basically become 737-11 (call it A321.5 Size) and 737-12 (A322.5 ) in size, NMA -S and NMA-L.

At least then they won't step on the existing product line and that part will probably just be replaced by a smaller winged version of NMA-S and NMA-L sometime after 2030.
 
flipdewaf
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Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 6:39 pm

2175301 wrote:
morrisond, JonesNL,RJMAZ

Concerning the above discussion on theoretical performance of different scenarios.

One of the things that colleges and universities fail to teach is that in almost all cases the equations being used are "best fit" equations to known data; and have an accuracy of how well they fit the data. Somewhere filed in the scientific libraries are the papers that derived those equations, and they almost always include an accuracy to all data number.

I'd be stunned if the accuracy of any of those equations was 5% or less. Often equations are accurate to 10-20% (and some are only accurate to 30%); which works for most practical things in life without much difficulties.

If better accuracy is required (in fields such as aerospace) then models and even full scale equipment is tested with highly accurate test equipment. In aerospace - its wind tunnel testing, which I suspect can get within 2.5% accuracy (and perhaps less depending on the accuracy of the test equipment and methods).

One of my expertise is highly accurate heat exchanger testing. Most plants have a hundred dollars of temperature instruments, and perhaps a few thousand dollars of flow instruments. I can show up with $50,000+ of extremely accurate temperature instruments and much better flow instruments (which can cost between $10,000 - $200,000 depending on the application) and show that the heat exchanger is performing often 10-20% better/worse than designed; and all of that can be traced to the inaccuracies of the equations being used. The largest uncertainties are in the fluid flow equations; which are the same equations used for airflow (and most design and plant engineers are stunned when I show them the papers where the equations were developed from and the uncertainty range to know accurate test results.

I would suggest that while it's great to talk about the theoretical trad-offs of doing this or that; that in reality in my opinion much of what you are describing is likely within the error margins of the equations and it takes wind tunnel testing to figure out the actual answers on which configuration/model is best.

There are very few equations in science and physics that are developed solely based on theoretical basis that are considered highly accurate. When you hear that some result matches the equation... the real question is "how close" and with what accuracy was the test instruments (what is the total accuracy of the test).

In the case of heat exchanges. Calculating the heat rate capacity of a heat exchanger is a few apparently straight forward equations. Calculating the total test uncertainty is about 50 times more complex; and there are to the best of my knowledge only 3 people in the USA who understand all the complexities and what needs to be done to calculate a highly accurate total test uncertainty (yes there are industry documents on what to do and factors to consider; but, the average engineer gets overwhelmed: It took me years to learn).

Have a great day,


I disagree, not fully but kinda. The variation of the data on that scale of structures and geometries that we are discussing is well understood and the variation in the testing data particularly in the high Reynolds’s regimes we are discussing is low. I do agree that there are areas where the data is more difficult but this tends to be in areas that can and have been dealt with so whilst it may not be that we can describe the actual solution or mechanism for a solution we can maintain confidence that it is achievable.

What I mean by that is things like the specific behaviour of the flows around the join between the flap canoe at high Mach might have some variability in the testing whereas the drag from an engine nacelle (basically a cylinder) or a lift curve slope of a standard profile are well understood.

Fred


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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 9:14 pm

Revelation wrote:
The timing could be reflective of a new CEO wanting his own person in the job, or it could be a coincidence.

Considering that he does not have many years before he hit's retirement age I hope the board pay's close attention to how deep his purges go, it will just have to start all over again when the next CEO is appointed and he wants his people in place.
Unfortunately or fortunately, a technical business is starting to mimic the political industry.
 
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 9:22 pm

par13del wrote:
Revelation wrote:
The timing could be reflective of a new CEO wanting his own person in the job, or it could be a coincidence.

Considering that he does not have many years before he hit's retirement age I hope the board pay's close attention to how deep his purges go, it will just have to start all over again when the next CEO is appointed and he wants his people in place.
Unfortunately or fortunately, a technical business is starting to mimic the political industry.

I'm not sure how this mirrors political institutions.

Airbus just had a pretty much total regime change over the last year or so including the CEO and all the leading figures.

It's pretty typical to see new executives putting their favored lieutenants into the next rung of chairs when they get a new job.

I've seen it countless times in my many decades of corporate life.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
WIederling
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 10:17 pm

Revelation wrote:
It's pretty typical to see new executives putting their favored lieutenants into the next rung of chairs when they get a new job.

I've seen it countless times in my many decades of corporate life.


Yes.
And pretty much perfect to unlink management inclusive the new lieutenants from reality.
Murphy is an optimist
 
flipdewaf
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 11:02 pm

Revelation wrote:

It's pretty typical to see new executives putting their favored lieutenants into the next rung of chairs when they get a new job.

I've seen it countless times in my many decades of corporate life.


And often there are new roles created to provide the ceo with their favourite ‘pets’ from previous roles, sometimes you wonder how they got their jobs and other times you don’t need much of an imagination at all...

Fred



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par13del
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Thu Feb 13, 2020 11:21 pm

Revelation wrote:
par13del wrote:
Revelation wrote:
The timing could be reflective of a new CEO wanting his own person in the job, or it could be a coincidence.

Considering that he does not have many years before he hit's retirement age I hope the board pay's close attention to how deep his purges go, it will just have to start all over again when the next CEO is appointed and he wants his people in place.
Unfortunately or fortunately, a technical business is starting to mimic the political industry.

I'm not sure how this mirrors political institutions.

Airbus just had a pretty much total regime change over the last year or so including the CEO and all the leading figures.

It's pretty typical to see new executives putting their favored lieutenants into the next rung of chairs when they get a new job.

I've seen it countless times in my many decades of corporate life.

When a political head changes, all the appointees usually automatically resign, for the new CEO of Boeing I am ok with him putting in place heads of major units who align with his strategy. The reason why I said how deep his purges go is because the entire structure in a technical business cannot be political or appointed based on strategy alignment, eventually you get to the job where knowledge, skill and qualifications outweigh "political" correctness.

The culture at Boeing related to cost cutting and maximizing profit is deeply entrenched, but as we have seen in all the documents released, a high number of non-political employee's still exist in the organization and this CEO was on the board.
 
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Revelation
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 3:56 am

WIederling wrote:
And pretty much perfect to unlink management inclusive the new lieutenants from reality.

I've seen that be the case, and I've also seen the case where it was the old management that was unlinked from reality and the new management team showed up as a cohesive unit and executed a very effective change in direction that the old team would have never countenanced.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
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seahawk
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 6:06 am

Revelation wrote:
https://www.reuters.com/article/us-singapore-airshow-boeing-tinseth/jet-market-oracle-tinseth-bows-out-with-boeing-at-crossroads-idUSKBN2071MR tells us that Boeing VP of marketing Randy Tinseth is retiring after 38 years of working for Boeing.

The timing could be reflective of a new CEO wanting his own person in the job, or it could be a coincidence.

Relevant to this thread, the article says:

Tinseth declined to be drawn into a discussion on the mid-sized airliner situation. “The dynamic has changed. I’ll leave it at that,” he said.

My inference is that the new Boeing CEO Calhoun and/or the new BCA President Deal are not fans of the NMA concept.

This is something Scott Hamilton has written on leehamnews.com.

In turn this supports the idea that they want someone who shares their thinking as head of marketing.

I don't think the XLR sales are what has turned things around.

It's been clear from 2011 that A321NEO would have better payload/range than MAX could achieve and once the XLR concept became viable it was clear that XLR would capture the 757 replacement market.

I think what has changed is that DM and McAllister are gone and Calhoun and Deal are in.


No, what changed that the MAX grounding did cost billions. If you want to keep the finacial performance at a high level, there is no money for new project at the moment. And I believe Calhoun is stock value driven in his decisions.
 
JayinKitsap
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Re: Boeing CEO: NMA will

Fri Feb 14, 2020 6:25 am

flipdewaf wrote:
planecane wrote:
This is sort of related to the NMA and cross section discussions. How did the 767 end up designed as 7 abreast? It was designed in the late 70's with the oil crisis issues. Fuel efficiency was a key goal of the design. How did they end up with 7 abreast, which, in the context of the NMA discussion, is less efficient than 6 abreast or 8 abreast even with 40 years of technology improvement?

I believe they effectively wanted to get the biggest twin plane they could given the max thrust available per engine at the time and needed to get a certain range. To go 8 abreast would have given them too little range.

It was probably also positioning in the market, the 727 was below the 757, the 767, then MD-10 and L-1011, and the queen above. Going 8ab would have put it right among the DC-10 and L-1011 instead of between other choices.
 
JayinKitsap
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Re: Boeing CEO: NMA will

Fri Feb 14, 2020 7:26 am

2175301 wrote:
morrisond, JonesNL,RJMAZ

Concerning the above discussion on theoretical performance of different scenarios.

One of the things that colleges and universities fail to teach is that in almost all cases the equations being used are "best fit" equations to known data; and have an accuracy of how well they fit the data. Somewhere filed in the scientific libraries are the papers that derived those equations, and they almost always include an accuracy to all data number.

I'd be stunned if the accuracy of any of those equations was 5% or less. Often equations are accurate to 10-20% (and some are only accurate to 30%); which works for most practical things in life without much difficulties.

If better accuracy is required (in fields such as aerospace) then models and even full scale equipment is tested with highly accurate test equipment. In aerospace - its wind tunnel testing, which I suspect can get within 2.5% accuracy (and perhaps less depending on the accuracy of the test equipment and methods).

One of my expertise is highly accurate heat exchanger testing. Most plants have a hundred dollars of temperature instruments, and perhaps a few thousand dollars of flow instruments. I can show up with $50,000+ of extremely accurate temperature instruments and much better flow instruments (which can cost between $10,000 - $200,000 depending on the application) and show that the heat exchanger is performing often 10-20% better/worse than designed; and all of that can be traced to the inaccuracies of the equations being used. The largest uncertainties are in the fluid flow equations; which are the same equations used for airflow (and most design and plant engineers are stunned when I show them the papers where the equations were developed from and the uncertainty range to know accurate test results.

I would suggest that while it's great to talk about the theoretical trad-offs of doing this or that; that in reality in my opinion much of what you are describing is likely within the error margins of the equations and it takes wind tunnel testing to figure out the actual answers on which configuration/model is best.

There are very few equations in science and physics that are developed solely based on theoretical basis that are considered highly accurate. When you hear that some result matches the equation... the real question is "how close" and with what accuracy was the test instruments (what is the total accuracy of the test).

In the case of heat exchanges. Calculating the heat rate capacity of a heat exchanger is a few apparently straight forward equations. Calculating the total test uncertainty is about 50 times more complex; and there are to the best of my knowledge only 3 people in the USA who understand all the complexities and what needs to be done to calculate a highly accurate total test uncertainty (yes there are industry documents on what to do and factors to consider; but, the average engineer gets overwhelmed: It took me years to learn).

Have a great day,


So true about fluid flow, almost all the formulae are classical equations to fit test data, as the bazillion of molecules bouncing around each with 6 modes of freedom is too complex to compute. Well, when simple such as straight pipe flow under pressure is pretty accurate, but with open channel flow it is highly variable. Often the formula are in quadratic equations where there are two mathematical answers and one has to pick the one that makes sense. Then there is what is called the critical slope, where the equations divide by zero.

As I finished college I did a research semester at the US Geological Survey modelling stream flows and dam breaks. The typical river in the midwest was easy to model, but I was handed the modelling of the Teton River where a dam had failed. The first step of the river modelling is to get the normal steady state model debugged, well the Teton river valley had sections near the critical slope. Each morning I would review all my computer batches, usually to find the river running uphill at 30 MPH with a negative depth. Clearly wrong.

Test equipment needs calibration, that is needed to even hope to have the desired accuracy. Cheap pressure gauges are probably 5% accurate at mid scale, 15% as it gets to its limits. To get the good test stand stuff things get really pricey. Just getting a 30 point test calibration with 20W lube oil (3 10 point curves at different temperatures) and the correction curves loaded into its memory for a 4" flow meter runs nearly $3,000 plus shipping, only good for a year.

I started college when slide rules were still used, calculators showed up my Junior year. They were 2 significant digit devices, matching the accuracy of the formulas. One of my profs would penalize if we had answers with excess digits.
 
FluidFlow
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 8:14 am

morrisond wrote:
morrisond wrote:
FluidFlow wrote:
Shorter gear will not work the problem will not be the rotation angle but the ground clearance for the nacelles. This limits or actually dictates the gear length.

Check out the tail of the A310. It is massive compared to the aircraft lenght. Thats the dimensions you look at. Thats a lot of tail for such a small aircraft. If you need to stay under 100t to avoid 8 main landing wheels, which adds a lot of weight you box yourself in a lot with a stumpy ovoid and if you go above you might as well go up until 130-150t MTOW and then the design becomes too big for NB gates and also too potent to be competitive at short hops <1500nm


The NB 300 Seat will be well above 100T.

The A310 has a tail height of 51'10", A300 54.9' and almost 7M longer.


If you look at the 787 ACAP https://www.boeing.com/resources/boeing ... ps/787.pdf it appears the gear got longer to accommodate the 20' longer 781 issues with rotation angle and it became semi-levered which I assume adds weight.

Quote "Due to the increased length of the -10, there is an increased risk of striking the tail on the runway, particular during takeoff. To reduce the chances of this happening, the main gear on the -10 is semilevered. This means that the aircraft can rotate over the aft wheels, not just the centre of the of the landing gear assembly." https://thepointsguy.co.uk/news/differe ... nd-787-10/

Pages 2-9 and Pages 2-10 it appears as though the 787-10 has longer(and probably stronger due to the higher max landing weight of 445,000 lbs vs 425,000 lbs) gear. It has nothing to to do with the nacelle's.

Dimension A is 24'4"-25'8" on 789 vs 26'-26'9" on 781

Dimension D is 5'9"-6'1" vs 6'6"-7'3"

Dimension M is 22'7"-23'5" vs 23'3"-23'8"



Please do not twist stuff.

First you claimed you can have a shorter landing gear on the NMA because it has a shorter fuselage. Well yes but the shortest you can get is limited minimum ground clearance between the nacelle and the ground. Nothing shorter is possible except you mount the engines above the wing or on the tail. Otherwise you can not shorten anything. You claimed you can have a short gear, I said the length is limited by the nacelle. Shorter is not possible. The 787 stuff you bring up is nice and yes it is because of a tail strike risk but that occurred after they stretched the fuselage.

If the NMA has to be optimized to a certain length then the length of the height of the gear is limited by the nacelle ground clearance. And if Boeing learned anything from the MAX, they will include on every new design some margin to be able to accommodate new bigger engines in the future.

Second, the height of the tail has nothing to do with it being relatively heavy for the fuselage length. The A300 has a lot more thrust so even tho it is longer it needed an almost similar size tail compared to the A310. But now you see the problem, even tho the A310 is a lot smaller and has way lower thrust engines, it needs a massive tail to be stable. You better compare the A321 (44.5m length) to the A310 (46.6m length) and compare the tail structures of the two.

Now why does the A310 need such a big tail compared to the A321? The A310 has more thrust, so with the same moment arm it needs bigger control surfaces to balance out the nose up moment created by the engines applying thrust. The A310 has a bigger wing so the lift is greater creating another rotational moment when lift attack point and CoG are not exactly at the same point. So to balance this out the tail has to be bigger.

So for a short oval with the same capacity as the A321, the tail will be heavier and bigger if the NMA needs/has bigger wings, and more powerful engines. This leads to more weight in the tail this all leads to more compromises. So if the NMA has the same MTOW as the A321 it automatically has a heavier structure leading to less payload. If it has more MTOW it will need to grow a lot to accommodate enough pax to make up for the additional weight. My opinion is that in the 100-140 MTOW range it is almost impossible to create a good aircraft that has optimal performance. Regulations automatically increase weight (bigger gear needed due to more wheels needed) and this triggers a lot of additional weight for no benefit. If you then have a "stumpy" design that adds weight for no reason you end up with a sub-par design.
 
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Chipmunk1973
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 8:55 am

I’m sorry if this has already been suggested but I am finding this one of the more difficult threads to follow logically.

Assuming (yes I know, a dangerous start already), that the concept will be a single aisle design, why could they not allow for it to use dual aerobridges at the front like a wide body? In addition you could even allow boarding and disembarking via a rear door as per many LCC’s, weather permitting. Wouldn’t this partly resolve the issue of turnaround times of very large single aisles like the 757-300?

Does adding that second main doors add too much weight and complexity, especially if you make it an option?

Happy to be educated about aero engineering.

Cheers,
C1973
 
WIederling
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 9:08 am

Revelation wrote:
WIederling wrote:
And pretty much perfect to unlink management inclusive the new lieutenants from reality.

I've seen that be the case, and I've also seen the case where it was the old management that was unlinked from reality and the new management team showed up as a cohesive unit and executed a very effective change in direction that the old team would have never countenanced.


Yes, both is possible. though I've seen less of the latter than my earlier observation.
I've seen a couple of customers and companies with acquaintances in the workforce
being "overlayed" for lack of a better word by US managers/owners.
They have a strong win/lose mentality ( self winning requires losers on the other side ) ,
have difficulty working with a euro style workforce and the existing legal framework for interaction with the workforce.

Often appear to be just set up to gut the company they are superficially "tasked to manage".
i.e. they show all the aspects of predatory looters.

lack of the skill set "synergistic cooperation".
Murphy is an optimist
 
Amiga500
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 10:24 am

Chipmunk1973 wrote:
I’m sorry if this has already been suggested but I am finding this one of the more difficult threads to follow logically.

Assuming (yes I know, a dangerous start already), that the concept will be a single aisle design, why could they not allow for it to use dual aerobridges at the front like a wide body? In addition you could even allow boarding and disembarking via a rear door as per many LCC’s, weather permitting. Wouldn’t this partly resolve the issue of turnaround times of very large single aisles like the 757-300?

Does adding that second main doors add too much weight and complexity, especially if you make it an option?

Happy to be educated about aero engineering.

Cheers,
C1973



If boarding time was the be-all and end-all, then the A321 cabin-flex would have been optimised around boarding at a revised L2 door (they could have moved it a bit further ahead of the wing LE).

Instead they got rid of the L2 door. Which should show exactly where priorities lie.
 
WIederling
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 11:10 am

Amiga500 wrote:
If boarding time was the be-all and end-all, then the A321 cabin-flex would have been optimised around boarding at a revised L2 door (they could have moved it a bit further ahead of the wing LE).

Instead they got rid of the L2 door. Which should show exactly where priorities lie.

Isn't that overlayed by evacuation requirement?
you can't remove the L1 door(s) no cul de sac seating like in the 747 nose anymore.

( Hmm. could one do an evacuation only ( smaller, lighter ) L1 door set ?)
Murphy is an optimist
 
Amiga500
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 12:00 pm

WIederling wrote:
Amiga500 wrote:
If boarding time was the be-all and end-all, then the A321 cabin-flex would have been optimised around boarding at a revised L2 door (they could have moved it a bit further ahead of the wing LE).

Instead they got rid of the L2 door. Which should show exactly where priorities lie.

Isn't that overlayed by evacuation requirement?
you can't remove the L1 door(s) no cul de sac seating like in the 747 nose anymore.

( Hmm. could one do an evacuation only ( smaller, lighter ) L1 door set ?)


Yeah, you cannot do cul-de-sac; but I don't believe there is a requirement for L1 or R1 to be full sized.
 
morrisond
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 2:08 pm

FluidFlow wrote:
morrisond wrote:
morrisond wrote:

The NB 300 Seat will be well above 100T.

The A310 has a tail height of 51'10", A300 54.9' and almost 7M longer.


If you look at the 787 ACAP https://www.boeing.com/resources/boeing ... ps/787.pdf it appears the gear got longer to accommodate the 20' longer 781 issues with rotation angle and it became semi-levered which I assume adds weight.

Quote "Due to the increased length of the -10, there is an increased risk of striking the tail on the runway, particular during takeoff. To reduce the chances of this happening, the main gear on the -10 is semilevered. This means that the aircraft can rotate over the aft wheels, not just the centre of the of the landing gear assembly." https://thepointsguy.co.uk/news/differe ... nd-787-10/

Pages 2-9 and Pages 2-10 it appears as though the 787-10 has longer(and probably stronger due to the higher max landing weight of 445,000 lbs vs 425,000 lbs) gear. It has nothing to to do with the nacelle's.

Dimension A is 24'4"-25'8" on 789 vs 26'-26'9" on 781

Dimension D is 5'9"-6'1" vs 6'6"-7'3"

Dimension M is 22'7"-23'5" vs 23'3"-23'8"



Please do not twist stuff.

First you claimed you can have a shorter landing gear on the NMA because it has a shorter fuselage. Well yes but the shortest you can get is limited minimum ground clearance between the nacelle and the ground. Nothing shorter is possible except you mount the engines above the wing or on the tail. Otherwise you can not shorten anything. You claimed you can have a short gear, I said the length is limited by the nacelle. Shorter is not possible. The 787 stuff you bring up is nice and yes it is because of a tail strike risk but that occurred after they stretched the fuselage.

If the NMA has to be optimized to a certain length then the length of the height of the gear is limited by the nacelle ground clearance. And if Boeing learned anything from the MAX, they will include on every new design some margin to be able to accommodate new bigger engines in the future.

Second, the height of the tail has nothing to do with it being relatively heavy for the fuselage length. The A300 has a lot more thrust so even tho it is longer it needed an almost similar size tail compared to the A310. But now you see the problem, even tho the A310 is a lot smaller and has way lower thrust engines, it needs a massive tail to be stable. You better compare the A321 (44.5m length) to the A310 (46.6m length) and compare the tail structures of the two.

Now why does the A310 need such a big tail compared to the A321? The A310 has more thrust, so with the same moment arm it needs bigger control surfaces to balance out the nose up moment created by the engines applying thrust. The A310 has a bigger wing so the lift is greater creating another rotational moment when lift attack point and CoG are not exactly at the same point. So to balance this out the tail has to be bigger.

So for a short oval with the same capacity as the A321, the tail will be heavier and bigger if the NMA needs/has bigger wings, and more powerful engines. This leads to more weight in the tail this all leads to more compromises. So if the NMA has the same MTOW as the A321 it automatically has a heavier structure leading to less payload. If it has more MTOW it will need to grow a lot to accommodate enough pax to make up for the additional weight. My opinion is that in the 100-140 MTOW range it is almost impossible to create a good aircraft that has optimal performance. Regulations automatically increase weight (bigger gear needed due to more wheels needed) and this triggers a lot of additional weight for no benefit. If you then have a "stumpy" design that adds weight for no reason you end up with a sub-par design.


You seem to be trying to compare an 101T A321 to an 130T NMA, or 101T A321 to 144-164T A310 - of course it's tail will be larger.

We are comparing a same weight (sans tail) same capacity 7W to 6W. Same Wing, same engines. 7W is 20' shorter so of course the tail will be larger - but it won't lead to 15% higher fuel burn.

Yes it would make more sense for Boeing to put longer gear on the widebody to allow for future growth but we are not comparing that in this case - we are looking at optimal design. They could always design it with bigger wheel wells to allow longer gear at some point to allow for stretches.

You have no idea where they would mount the Engines on the wings. You can't say for sure that the nacelle height is the limiting factor. Boeing seems to like to mount them pretty high.

For optimal design you would make the gear as short as possible to get the Rotation angle you need. The Rotation angle is dependent on the location of the rear gear and the angle of the aft fuselage.

You can be pretty certain that a 6W 300 Seat aircraft would be limited by gear height due to rotation angle. It would need longer gear or a semi levered design to achieve the same rotation angle as the shorter 7W. Both of which would add weight.
 
FluidFlow
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 2:58 pm

morrisond wrote:

We are comparing a same weight (sans tail) same capacity 7W to 6W. Same Wing, same engines. 7W is 20' shorter so of course the tail will be larger - but it won't lead to 15% higher fuel burn.



Let's take this as a start. How will this work, if you can explain this I will be happy:

So the tail will be larger because the fuselage is shorter. Agreed. So the tail is heavier.

Then the exact same wing has to lift more. To lift more we need more thrust as the aircraft has to fly a higher AoA to generate more lift with the same wing because this leads to more drag.

So at the end we have at the same capacity a heavier aircraft that needs to fly less efficient to generate more lift to carry the additional weight from the bigger tail.

We do not include the additional weight from the sub optimal shape as you assumed the same weight. EDIT: So you need more fuel but you still have the same capacity. You have a 7W design that is losing vs a 6W on cost per seat

I never said it is 15% more (that came from a different poster) but it is definitely more than a 6W under your assumptions.
 
WIederling
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 3:18 pm

morrisond wrote:
For optimal design you would make the gear as short as possible to get the Rotation angle you need.


One aspect of "optimal" is to not "peak" optimality and thus deny any further potential for optimalization.
Murphy is an optimist
 
morrisond
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 3:19 pm

FluidFlow wrote:
morrisond wrote:

We are comparing a same weight (sans tail) same capacity 7W to 6W. Same Wing, same engines. 7W is 20' shorter so of course the tail will be larger - but it won't lead to 15% higher fuel burn.



Let's take this as a start. How will this work, if you can explain this I will be happy:

So the tail will be larger because the fuselage is shorter. Agreed. So the tail is heavier.

Then the exact same wing has to lift more. To lift more we need more thrust as the aircraft has to fly a higher AoA to generate more lift with the same wing because this leads to more drag.

So at the end we have at the same capacity a heavier aircraft that needs to fly less efficient to generate more lift to carry the additional weight from the bigger tail.

We do not include the additional weight from the sub optimal shape as you assumed the same weight. EDIT: So you need more fuel but you still have the same capacity. You have a 7W design that is losing vs a 6W on cost per seat

I never said it is 15% more (that came from a different poster) but it is definitely more than a 6W under your assumptions.


You can't say the shape is suboptimal - it may be more Aero - no way until you get it into a tunnel.

The extra 1,000kg in Fuselage Weight should be offset by shorter cable runs and shorter gear (and possibly more than offset). One of the other posters was suggesting a tail 50% bigger. That seems rather extreme. There should be a difference but on an aircraft that is 130Tish MTOW a tail that is 10-20% bigger (totally guessing) shouldn't be more than a few hundred pounds more - not 3,500.

Then you have a wider body that might generate more lift/ meaning less wing.

We are getting into tiny margins and would the WB be as efficient - probably not - but it could be within very low single digits. Fuel is about 30% of costs - assume 3% less efficient - that is a .3% cost.

The WB as it could fit a Wider container - even accounting for shorter length (i've done the calcs before in previous threads and don't feel like looking them up or finding them again) could carry 15-20% more Cargo by Volume providing additional revenue.

We are also ignoring the fact that the WB design will allow more room for Services (Lav's, Galleys) in the front and back meaning those could take less length of the fuselage shaving the WB disadvantage as well. Taking a meter off a 48M fuselage takes a few hundred KG's off. The WB could even with a bigger tail could weigh exactly the same.

Basically the margins are so close I don't think one could say one is better than the other by any significant amount.

However if you were an airline and both cost the same to buy and operate what would you rather have in your fleet? What do you think passengers would prefer?
 
ILNFlyer
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 3:26 pm

Nice opinion piece at flight global

https://www.flightglobal.com/flight-int ... 47.article

"Pee or get off the pot time at Boeing".

I do not understand why they just dont do a CFRP and re-engined 757-200 & 300.
 
KlimaBXsst
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 3:26 pm

To me

since it looks like the “beaners,” short for bean counters, will be closing up ANY “mid cabin entry doors” to add more seats at both BOEING and AIRBUS.

Boeing might as well use “Jetescape” type emergency exits through any cabin with a longer design. Jetescape type exits are similar to what Boeing designed for the 3 left and right exits on the 8 exit configured 757’s. Maybe Boeing can make lavatories smaller and also incorporate galleys and interior fixtures to intrude upon exit space to create room for more seats.

Can we agree upon this design aspect. (;
Aesthetically the A 340 got it right!
 
FluidFlow
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 3:32 pm

morrisond wrote:
FluidFlow wrote:
morrisond wrote:

We are comparing a same weight (sans tail) same capacity 7W to 6W. Same Wing, same engines. 7W is 20' shorter so of course the tail will be larger - but it won't lead to 15% higher fuel burn.



Let's take this as a start. How will this work, if you can explain this I will be happy:

So the tail will be larger because the fuselage is shorter. Agreed. So the tail is heavier.

Then the exact same wing has to lift more. To lift more we need more thrust as the aircraft has to fly a higher AoA to generate more lift with the same wing because this leads to more drag.

So at the end we have at the same capacity a heavier aircraft that needs to fly less efficient to generate more lift to carry the additional weight from the bigger tail.

We do not include the additional weight from the sub optimal shape as you assumed the same weight. EDIT: So you need more fuel but you still have the same capacity. You have a 7W design that is losing vs a 6W on cost per seat

I never said it is 15% more (that came from a different poster) but it is definitely more than a 6W under your assumptions.


You can't say the shape is suboptimal - it may be more Aero - no way until you get it into a tunnel.


True

The extra 1,000kg in Fuselage Weight should be offset by shorter cable runs and shorter gear (and possibly more than offset). One of the other posters was suggesting a tail 50% bigger. That seems rather extreme. There should be a difference but on an aircraft that is 130Tish MTOW a tail that is 10-20% bigger (totally guessing) shouldn't be more than a few hundred pounds more - not 3,500.


You wrote in you assumptions that are Quoted above that we have the same weight NB vs the WB. No one will build a 130tMTOW NB, so the NMA will be heavier? The 757-200 had around 115t. Airbus will build the XLR with the same capacity (almost) with 101t MTOW. Your NMA is 30% heavier than the A321 so it will need 30% more capacity (320) to have the same weight/pax ratio.

Then you have a wider body that might generate more lift/ meaning less wing.


Might but you assumed the same wing. Otherwise see your own quote:
You can't say the shape is suboptimal - it may be more Aero - no way until you get it into a tunnel.



We are getting into tiny margins and would the WB be as efficient - probably not - but it could be within very low single digits. Fuel is about 30% of costs - assume 3% less efficient - that is a .3% cost.


This will be entirely dependent on which MTOW you make your assumptions on, same as the NB as you assumed first or the 130MTOW you bring up later, that has to compete against a fictional 130MTOW NB...

The WB as it could fit a Wider container - even accounting for shorter length (i've done the calcs before in previous threads and don't feel like looking them up or finding them again) could carry 15-20% more Cargo by Volume providing additional revenue.


A different container that needs new handling facilities to every airport the NMA flies, vs the standard NB container every airport can already handle. I do not see this as an advantage at all. Just more complexity for everyone.

We are also ignoring the fact that the WB design will allow more room for Services (Lav's, Galleys) in the front and back meaning those could take less length of the fuselage shaving the WB disadvantage as well. Taking a meter off a 48M fuselage takes a few hundred KG's off. The WB could even with a bigger tail could weigh exactly the same.


So you are making the NMA even shorter if it competes on the same capacity vs the NB that you assume in the quote as being the same capacity.

Basically the margins are so close I don't think one could say one is better than the other by any significant amount.

However if you were an airline and both cost the same to buy and operate what would you rather have in your fleet? What do you think passengers would prefer?


The one that offers the cheaper fares so the lower cost per seat, as well as the one I can easier integrate into the fleet (commonality with crew, maintenance and container handling capability).
 
Elementalism
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 4:10 pm

ILNFlyer wrote:
Nice opinion piece at flight global

https://www.flightglobal.com/flight-int ... 47.article

"Pee or get off the pot time at Boeing".

I do not understand why they just dont do a CFRP and re-engined 757-200 & 300.


757 is a 40+ year old design. The cost to get it upto speed with FBW, new wing, ect would probably cost as much as a new design. Also I think this pivot is to replace the 737-7 through 757-200\300 in a single line. It is hard to shrink a plane vs a stretch. The 757 starts bigger than the A321NEO XLR. So it is hard to get it to something that would replace a 737-7.

I'd love to see a 757 MAX. New engines, wing ect. But that ship sailed 15 years ago. And it is biting Boeing in the arse imo. The A321 orders really picked up 3 years after the 757 was shuttered. IMO the 757 orders would had also picked up. The market changed by the end of the 2010s. A321\757 aircraft were more desired.
 
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Stitch
Posts: 26700
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 4:18 pm

ILNFlyer wrote:
I do not understand why they just dont do a CFRP and re-engined 757-200 & 300.


At the most basic level, this is likely what we will see.
 
flipdewaf
Posts: 3302
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 4:32 pm

morrisond wrote:
You can't say the shape is suboptimal - it may be more Aero - no way until you get it into a tunnel.
You cannot simply apply the doubt card and claim that no body knows. You may as well go down the route of philosophy and ask what is truth

morrisond wrote:
The extra 1,000kg in Fuselage Weight should be offset by shorter cable runs
Shorter? Don't they have to go across the cabin and between the engines too?

morrisond wrote:
and shorter gear
The gear length would be driven by engine sizing, the 753 would be the same size as the NBNMA so would only get easier from there with regards to having larger engines.

morrisond wrote:
One of the other posters was suggesting a tail 50% bigger.
That was myself, you will see in the tech ops thread how the sizing formula has been modified to allow it to scale with regard to the narrowbody option. The update also included some errors I had made in the TOW

morrisond wrote:
shouldn't be more than a few hundred pounds more - not 3,500.
What do you base the "few hundred pounds" on? Please forgive if I am wrong but it seems to be from a place of what you would like it to be rather than what it is.

morrisond wrote:
Then you have a wider body that might generate more lift/ meaning less wing.
Fuselages are not a good place to get lift.

morrisond wrote:
We are getting into tiny margins
, we certainly are not.

morrisond wrote:
Fuel is about 30% of costs - assume 3% less efficient - that is a .3% cost.
.... you sure?

morrisond wrote:
The WB as it could fit a Wider container
600mm wider, wasn't the premise oft his aircraft to use the current standard narrow body container?

morrisond wrote:
Basically the margins are so close
? Not if you look at it objectively and don't hamstring an over optimised design.

morrisond wrote:
I don't think one could say one is better than the other by any significant amount.
You can, read the tech ops thread.

morrisond wrote:
However if you were an airline and both cost the same to buy and operate what would you rather have in your fleet?

And if my aunt had a penis she'd be my uncle.

morrisond wrote:
What do you think passengers would prefer?
The one that has the smaller number next to the destination on the internet.

Fred
Image
 
planecane
Posts: 1424
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 4:33 pm

Elementalism wrote:
ILNFlyer wrote:
Nice opinion piece at flight global

https://www.flightglobal.com/flight-int ... 47.article

"Pee or get off the pot time at Boeing".

I do not understand why they just dont do a CFRP and re-engined 757-200 & 300.


757 is a 40+ year old design. The cost to get it upto speed with FBW, new wing, ect would probably cost as much as a new design. Also I think this pivot is to replace the 737-7 through 757-200\300 in a single line. It is hard to shrink a plane vs a stretch. The 757 starts bigger than the A321NEO XLR. So it is hard to get it to something that would replace a 737-7.


Unless there are some major variations between models (like different wings and other structural changes), there is no way to replace the 737-7 through 757-300 with one design. Either the smallest will be ridiculously inefficient or the largest will have severely lacking performance.
 
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Stitch
Posts: 26700
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 5:33 pm

planecane wrote:
Unless there are some major variations between models (like different wings and other structural changes), there is no way to replace the 737-7 through 757-300 with one design. Either the smallest will be ridiculously inefficient or the largest will have severely lacking performance.


The forum seems to be coalescing around the idea of two families employing a common fuselage cross section (3+3) with varying lengths and two wingspans.

I do have one question - the 757 has a span of 38m, which means it is wider than a Code C gate, but not by much. Do they park 757s only at Code D gates, or is there usually enough "padding" at a Code C gate that if a 737 or A320 was parked on either side it would be okay?

I ask because if they do and we are looking at a different wing for the larger variants (say the 45m/50m/55m lengths), could we look at something like a 44m wing with the fold at the 40m mark and it would still fit in the Code C gate?

If 757s only operate out of Code D gates, then Boeing would not need to worry about a fold as they could go out to 52m, though I expect we'd see just a straight 44m or 46m span with no folding tips.
 
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Revelation
Topic Author
Posts: 22660
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 6:08 pm

seahawk wrote:
No, what changed that the MAX grounding did cost billions. If you want to keep the finacial performance at a high level, there is no money for new project at the moment. And I believe Calhoun is stock value driven in his decisions.

I don't see it that way.

Boeing had already two rounds of multi billion dollar write downs due to MAX while DM was still CEO and NMA was still moving forward, so it wasn't about the money it was about the leader. Within a week of Calhoun taking over the NMA team canceled meetings it was going to have with outside vendors and the start over orders were given.

Besides, as we all know all new Boeing projects are funded by taxpayer givebacks and any red ink accrued is spread out for decades to come so no actual money is needed, and starting another new airplane program is key to keeping the ponzi scheme going.

ILNFlyer wrote:
Nice opinion piece at flight global

https://www.flightglobal.com/flight-int ... 47.article

"Pee or get off the pot time at Boeing".

Unfortunately FG's editorial staff has no actual sway over events.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
WIederling
Posts: 9309
Joined: Sun Sep 13, 2015 2:15 pm

Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 6:35 pm

Revelation wrote:
Unfortunately FG's editorial staff has no actual sway over events.


Isn't it fully sufficient to observe the constraints?

( my mother: you want to make me abandon my 3rd storey flat!
answ: constraints force you to ....
you have shoved decissions into the future for decades.
now you have no leeway left. Only one path open.)
Murphy is an optimist
 
morrisond
Posts: 2343
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 6:45 pm

FluidFlow wrote:
morrisond wrote:
FluidFlow wrote:

Let's take this as a start. How will this work, if you can explain this I will be happy:

So the tail will be larger because the fuselage is shorter. Agreed. So the tail is heavier.

Then the exact same wing has to lift more. To lift more we need more thrust as the aircraft has to fly a higher AoA to generate more lift with the same wing because this leads to more drag.

So at the end we have at the same capacity a heavier aircraft that needs to fly less efficient to generate more lift to carry the additional weight from the bigger tail.

We do not include the additional weight from the sub optimal shape as you assumed the same weight. EDIT: So you need more fuel but you still have the same capacity. You have a 7W design that is losing vs a 6W on cost per seat

I never said it is 15% more (that came from a different poster) but it is definitely more than a 6W under your assumptions.


You can't say the shape is suboptimal - it may be more Aero - no way until you get it into a tunnel.


True

The extra 1,000kg in Fuselage Weight should be offset by shorter cable runs and shorter gear (and possibly more than offset). One of the other posters was suggesting a tail 50% bigger. That seems rather extreme. There should be a difference but on an aircraft that is 130Tish MTOW a tail that is 10-20% bigger (totally guessing) shouldn't be more than a few hundred pounds more - not 3,500.


You wrote in you assumptions that are Quoted above that we have the same weight NB vs the WB. No one will build a 130tMTOW NB, so the NMA will be heavier? The 757-200 had around 115t. Airbus will build the XLR with the same capacity (almost) with 101t MTOW. Your NMA is 30% heavier than the A321 so it will need 30% more capacity (320) to have the same weight/pax ratio.

Then you have a wider body that might generate more lift/ meaning less wing.


Might but you assumed the same wing. Otherwise see your own quote:
You can't say the shape is suboptimal - it may be more Aero - no way until you get it into a tunnel.



We are getting into tiny margins and would the WB be as efficient - probably not - but it could be within very low single digits. Fuel is about 30% of costs - assume 3% less efficient - that is a .3% cost.


This will be entirely dependent on which MTOW you make your assumptions on, same as the NB as you assumed first or the 130MTOW you bring up later, that has to compete against a fictional 130MTOW NB...

The WB as it could fit a Wider container - even accounting for shorter length (i've done the calcs before in previous threads and don't feel like looking them up or finding them again) could carry 15-20% more Cargo by Volume providing additional revenue.


A different container that needs new handling facilities to every airport the NMA flies, vs the standard NB container every airport can already handle. I do not see this as an advantage at all. Just more complexity for everyone.

We are also ignoring the fact that the WB design will allow more room for Services (Lav's, Galleys) in the front and back meaning those could take less length of the fuselage shaving the WB disadvantage as well. Taking a meter off a 48M fuselage takes a few hundred KG's off. The WB could even with a bigger tail could weigh exactly the same.


So you are making the NMA even shorter if it competes on the same capacity vs the NB that you assume in the quote as being the same capacity.

Basically the margins are so close I don't think one could say one is better than the other by any significant amount.

However if you were an airline and both cost the same to buy and operate what would you rather have in your fleet? What do you think passengers would prefer?


The one that offers the cheaper fares so the lower cost per seat, as well as the one I can easier integrate into the fleet (commonality with crew, maintenance and container handling capability).


I was just throwing 130T out there - it might be less it might be more. If a NB seats 300 in Y that means it's bigger than an 753 with a lot more range (753 is 3,400Nm) . The 753 is 124T MTOW.

I 'm assuming same MTOW for both.

WB could be shorter in the front and back service areas as it's wider so you get the same square footage for the same length. You are serving the same number of passengers so storage/lav needs are the same.

I've always assumed that NMA and NSA are based on the same cross section so introducing a new container is no big deal. An LD3-45 will fit in there just fine for cross shipping. 737 Customers don't own any Containers or handling equipment right now anyways - so no big deal to adapt a new size.
 
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Revelation
Topic Author
Posts: 22660
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Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 6:45 pm

WIederling wrote:
Revelation wrote:
Unfortunately FG's editorial staff has no actual sway over events.

Isn't it fully sufficient to observe the constraints?

I don't see constraints.

Boeing just went to Wall Street looking for a $10B line of credit and walked away with a $12B line of credit and nary any damage to its bond rating.

If they wanted more I don't see why they couldn't have gotten more, borrowing is cheap these days.

The real issue IMO is the new CEO wasn't comfortable with the product being developed.

Now they will kick around various ideas for a good year or two while MAX and 777X are the focus.

Thus they will stay on the pot and pee slowly, much to FG's discomfort.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
morrisond
Posts: 2343
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 7:00 pm

flipdewaf wrote:
morrisond wrote:
You can't say the shape is suboptimal - it may be more Aero - no way until you get it into a tunnel.
You cannot simply apply the doubt card and claim that no body knows. You may as well go down the route of philosophy and ask what is truth

morrisond wrote:
The extra 1,000kg in Fuselage Weight should be offset by shorter cable runs
Shorter? Don't they have to go across the cabin and between the engines too?

morrisond wrote:
and shorter gear
The gear length would be driven by engine sizing, the 753 would be the same size as the NBNMA so would only get easier from there with regards to having larger engines.

morrisond wrote:
One of the other posters was suggesting a tail 50% bigger.
That was myself, you will see in the tech ops thread how the sizing formula has been modified to allow it to scale with regard to the narrowbody option. The update also included some errors I had made in the TOW

morrisond wrote:
shouldn't be more than a few hundred pounds more - not 3,500.
What do you base the "few hundred pounds" on? Please forgive if I am wrong but it seems to be from a place of what you would like it to be rather than what it is.

morrisond wrote:
Then you have a wider body that might generate more lift/ meaning less wing.
Fuselages are not a good place to get lift.

morrisond wrote:
We are getting into tiny margins
, we certainly are not.

morrisond wrote:
Fuel is about 30% of costs - assume 3% less efficient - that is a .3% cost.
.... you sure?

morrisond wrote:
The WB as it could fit a Wider container
600mm wider, wasn't the premise oft his aircraft to use the current standard narrow body container?

morrisond wrote:
Basically the margins are so close
? Not if you look at it objectively and don't hamstring an over optimised design.

morrisond wrote:
I don't think one could say one is better than the other by any significant amount.
You can, read the tech ops thread.

morrisond wrote:
However if you were an airline and both cost the same to buy and operate what would you rather have in your fleet?

And if my aunt had a penis she'd be my uncle.

morrisond wrote:
What do you think passengers would prefer?
The one that has the smaller number next to the destination on the internet.

Fred


Fred - The only way to settle this is to set the weights the same, same engines, same wing and see how much of a penalty the bigger tail is.

I'm assuming you have done it and it doesn't look good for the NB as it's not that big of a penalty. If otherwise I'm sure you would have let us know by now instead of continuing to cripple the WB. But at this point I'm not sure I would trust your numbers as you goal seek to get the result you want.

For cable runs - Cockpit to tail is 20' longer. Cockpit to wing 10' longer. Wing to tail 10' longer. Yes they might be a little more to the seats right to left - but other than power a lot of that is now wireless.

So why did the 787-10 have to use taller semi-levered gear (gear) to get more rotation angle? It's uses the same size Nacelle's as the 789.

All things being equal the NB would have heavier gear - maybe the same height but more complicated (semi-levered) to get the same rotation angle.

No one has said they would use the same Container other than some here on Anet.

You know the anatomy of your Aunt? Interesting.
 
morrisond
Posts: 2343
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 7:07 pm

Stitch wrote:

The forum seems to be coalescing around the idea of two families employing a common fuselage cross section (3+3) with varying lengths and two wingspans.



Well I would agree with the two wingspan idea as I have (and others) have been saying that for years. From an industrial standpoint it just makes too much sense. And it still may be 6W but at least 8W has now died as that never made sense as a standalone project.

But as Boeing itself said they are now looking at two concepts. What would they be other than 7W or 6W?
 
flipdewaf
Posts: 3302
Joined: Thu Jul 20, 2006 6:28 am

Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

Fri Feb 14, 2020 7:17 pm

morrisond wrote:
flipdewaf wrote:
morrisond wrote:
You can't say the shape is suboptimal - it may be more Aero - no way until you get it into a tunnel.
You cannot simply apply the doubt card and claim that no body knows. You may as well go down the route of philosophy and ask what is truth

morrisond wrote:
The extra 1,000kg in Fuselage Weight should be offset by shorter cable runs
Shorter? Don't they have to go across the cabin and between the engines too?

morrisond wrote:
and shorter gear
The gear length would be driven by engine sizing, the 753 would be the same size as the NBNMA so would only get easier from there with regards to having larger engines.

morrisond wrote:
One of the other posters was suggesting a tail 50% bigger.
That was myself, you will see in the tech ops thread how the sizing formula has been modified to allow it to scale with regard to the narrowbody option. The update also included some errors I had made in the TOW

morrisond wrote:
shouldn't be more than a few hundred pounds more - not 3,500.
What do you base the "few hundred pounds" on? Please forgive if I am wrong but it seems to be from a place of what you would like it to be rather than what it is.

morrisond wrote:
Then you have a wider body that might generate more lift/ meaning less wing.
Fuselages are not a good place to get lift.

morrisond wrote:
We are getting into tiny margins
, we certainly are not.

morrisond wrote:
Fuel is about 30% of costs - assume 3% less efficient - that is a .3% cost.
.... you sure?

morrisond wrote:
The WB as it could fit a Wider container
600mm wider, wasn't the premise oft his aircraft to use the current standard narrow body container?

morrisond wrote:
Basically the margins are so close
? Not if you look at it objectively and don't hamstring an over optimised design.

morrisond wrote:
I don't think one could say one is better than the other by any significant amount.
You can, read the tech ops thread.

morrisond wrote:
However if you were an airline and both cost the same to buy and operate what would you rather have in your fleet?

And if my aunt had a penis she'd be my uncle.

morrisond wrote:
What do you think passengers would prefer?
The one that has the smaller number next to the destination on the internet.

Fred


Fred - The only way to settle this is to set the weights the same, same engines, same wing and see how much of a penalty the bigger tail is.

Would the only meaningful comparison between the 779x and A350 have to assume the same weight?
morrisond wrote:
I'm assuming you have done it and it doesn't look good for the NB

I haven’t done it. If I were to do it would you like it with the comparable NB in terms of cabin layout or the one with the 28” aisle?

morrisond wrote:
as it's not that big of a penalty.
If otherwise I'm sure you would have let us know by now instead of continuing to cripple the WB.

I’m not crippling the wide body, it’s doing that itself.
morrisond wrote:
But at this point I'm not sure I would trust your numbers as you goal seek to get the result you want.

Uh huh.

morrisond wrote:
For cable runs - Cockpit to tail is 20' longer. Cockpit to wing 10' longer. Wing to tail 10' longer. Yes they might be a little more to the seats right to left - but other than power a lot of that is now wireless.

One day these new things you trot out will will run out..the cabin services are taken care of in the fittings and furnishings.
morrisond wrote:

So why did the 787-10 have to use taller semi-levered gear (gear) to get more rotation angle? It's uses the same size Nacelle's as the 789.

How much extra did it weigh?
morrisond wrote:

All things being equal the NB would have heavier gear -

Except that the WB gear has to hold up the fundamentally heavier aircraft soooooo....
morrisond wrote:
maybe the same height but more complicated (semi-levered) to get the same rotation angle.



If you’d like to have a discussion of a technical nature, please feel free to post to the thread in tech ops.

Fred



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