Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Bjorn’s Corner: New engine development. Part 4. Propulsive efficiency April 19, 2024
- Boeing unlikely to meet FAA’s 90-day deadline for new safety program April 18, 2024
- Focus on quality not slowing innovation, says GKN April 18, 2024
- Boeing defends 787, 777 against whistleblower charges April 17, 2024
- Dissecting Boeing CEO’s statement next new airplane will cost $50bn April 15, 2024
NMA must stand on its own business case
Dec. 6, 2018, © Leeham News: The prospective Boeing 797 (NMA) must stand on its own business case and not rely on aftermarket contracts for a profitable
program, reports investment bank JP Morgan.
JPM’s aerospace analyst Seth Seifman met with Boeing CEO Dennis Muilenburg, CFO Greg Smith and Boeing Commercial Airplanes VP-marketing Randy Tinseth Dec. 4. In a research note issued yesterday, Seifman reported that the business case for the New Midmarket Aircraft still hasn’t closed—but “if Boeing launches the NMA, it will be with the intention of earning a return on the aircraft itself that is comparable to existing programs; it will not be a plan to accept lower margins on the aircraft and make it up in the aftermarket.” (Emphasis in original.)
Must stand on its own
The “NMA must stand on its own as a traditional aircraft program,” Seifman wrote. “While the NMA decision is not yet made, Boeing believes the moves it has taken to de-risk development would still allow a 2019 launch to result in a 2025 entry-into-service.”
However, he added that the NMA will “jump start” activities in the new businesses and vertical integration of actuators, APUs, avionics and seed the growth of Boeing Global Services.
Seifman wrote that he was “relieved to hear” NMA must stand alone in its business case.
“Boeing holds the NMA cards close to its vest,” he wrote. “We see arguments on both sides” of a go ahead or a decision to shelve the project. But Seifman “tends” to believe a program launch, probably at the Paris Air Show, next year.
“NMA appears to be as much about transforming Boeing as it is about the aircraft and we found [the] discussion consistent with this view,” Seifman wrote.
“The intention here is to deliver both the cost that Boeing believes the market needs to buy the NMA AND a path to the production system for an eventual 737 replacement.”
Other take-aways
- Seifman writes that Boeing sees more orders for the 777X coming in 2020, “when legacy 777 operators look to replace aircraft.”
- The 737 and 787 drive cash flow in 2019, partially offset by the 777X costs.
- CFM is meeting its LEAP engine delivery commitments but it will be a crunch to deliver enough 737s this month to meet the full year guidance of 810-815 aircraft of all types.
“reported that the business case for the New Midmarket Aircraft still hasn’t closed—but…”
IMHO the constant references to ‘closing the business case’ are pure deception. The decision has already been made to move forward and the confidential pre-sales process is underway. If that results in the finding that no airline is going to buy the proposed configuration then it might be killed outright, but the idea that hordes of accountants and engineering economists are hunched over ledger books analyzing whether a change of 0.01% in the forecast prime rate in 2037 will cause the ‘business case to fail’, 1980s asset-allocation style, is a smokescreen.
“reported that the business case for the New Midmarket Aircraft still hasn’t closed—but…”
.. is OverSpeak for “not enough customers are willing to commit at the pricing that Boeing would like ?needs? to press for.
Why do I not get “replied” eMails though requested anymore?
@Uwe:
“…is OverSpeak for “not enough customers are willing to commit at the pricing.”
Logically, would that be equally applicable to the 321XLR, 321Neo+, 321Neo++ concepts in the context of cannibalizing existing 321LR sales potential and more broadly, available production slots for the whole 320Neo family given that the program is now already sold out for yrs to come?
Just wondering if the same principles apply….
I don’t see the comparability you seem to assume.
Boeing is endlessly talking about a super new airplane, next best thing to sliced bread sittin in formerly vacant space : the MoM. They can’t say what it is to look like and also seem to be unable to bind customers.
Airbus has talked about working on enhanced versions of the A320 family. ( and stopping or moving on the backburner some of those )
All else appears to be grapevine russlings in the media.
MoM at the moment looks very much like the abortive NSA super ding just around the corner. ( resolved in NEO and MAX )
@Uwe:
“I don’t see the comparability you seem to assume”
Sometimes, bias towards X and against Y can cloud vision.
As for the alleged lack of comparability, I can’t help but noticed the similarity in substance between the 2 descriptions as below:
“Boeing is endlessly talking about a super new airplane” vs
“Airbus has talked about working on enhanced versions of the A320 family.”
They are both “talking” about new products except U ‘spiced up’ the wordings for 1 but not the other.
” next best thing to sliced bread ”
An example of the type of spice used.
“They can’t say what it is to look like”
1. They did a little bit for general public consumption(e.g. U and me) particularly @ the Paris airshow in case U’ve forgotten:
https://money.cnn.com/2017/06/20/news/companies/boeing-797-paris-first-peek/index.html
2. Pretty sure potential 797 customers @ this stage hv already seen+knew a lot more and in much greater details(but agreed not to disclose) than available to the general public:
https://www.seattletimes.com/business/boeing-aerospace/boeings-talking-with-airlines-about-a-797-and-they-like-what-they-hear/
Same story for the 321XLR(and likely even 321Neo+). In fact, we see the same inf0-sharing pattern whenever any new concept has progressed to a stage right before seeking ATO by the board prior to official program launch.
“and also seem to be unable to bind customers.”
If “bind” means actual contract, of course not because 797 sales team is procedural-wise not allowed to do so @ this stage, not even a LoI/MoU with customers. If for no other reasons, 797 team @ least need to know @ which price range the board would allow when they start negotiating with customers. Again, same deal re 321XLR until it clears ATO.
“MoM at the moment looks very much like the abortive NSA”
It did @ the beginning until Paris airshow 2017 when more details of NMA were revealed to the general public including an obscure artist rendering of the NMA concept itself. Since then, Boeing created the NMA program office, started hiring talents specifically for NMA, secured the 797 trademark for NMA, etc.:
https://www.bizjournals.com/seattle/news/2018/07/10/boeing-797-nma-new-mid-market-airplane-trademark.html
https://www.bizjournals.com/seattle/news/2018/05/17/boeing-nma-797-program-managers-engineers-details.html
None of the above happened for the NSA before if U can recall….e.g. Boeing has never published even just an artist rendering of the NSA concept prior to Max launch.
Imho Boeing spent a lot of time making the right choice and getting a “super aircraft”. If they do not disclose anything it’s not to make the same mistake as the 787 because Airbus with the A350 have followed the launch despite the fact that the 787 Dreamliner won on the market makes the A350 … They protect their investments
I can see a large percentage (50+% ?) of potential A321XLR/Plus orders in the short-medium term to be conversions from current A321/LR orders and/or options.
@sPh
how could you possibly close a business case when major parameters are still under evaluation? So, no, it’s not a smoke screen.
The open parameters are:
1) the production system for the fuselage. While we can assume that the tech for the 787 and 777X wings can be used for the 797, the barrel system of the 787 fuselage appears to be both too heavy and too expensive. My best guess is there are still at least 2 alternative technologies developed and evaluated.
2) there is no suitable engine available. PW, RR and CfM are offering engines, but as we all know, they have all hands full with the existing programs. For 2025 service only derivatives of the GTF and the Leap would be possible. But, given delays in the production system, the RR Advance could be back in the race if it offers superior performance.
3) Pricing might in the end be the key question: Will it be possible to reduce production cost of the 797 below the A330neo? If not, will the 797 be so much more efficient that airlines would still buy it in sufficient numbers?
I have no doubt that is is as the Signori stated: The business case is still open and mayor decisions still pending.
Of course there is not an engine.
Engines are based on proposals. 787 did not have a in service engine either (nor did most of the aircraft launched)
Engine is not an issue, who supplies it, what it looks like, all the fiddly stuff yes but if they want engines, they will have e engine(s).
I’m not convinced this is generally true. In the case of the Airbus 220, Mitsubishi RJ, Embraer E2 and Airbus 320neo the engine came first.
And the CFM56 came before the 737-300 and the RR Trent 700 that powers the A330 was in fact developed for an aborted DC10/MD11 makeover.
Regardless of CFM, most advances tend to new engines not older ones.
Yes you can sometimes utilize one that was intended for something else.
Its not the norm.
My analysis would be that if the fuselage technology is not defined it is still an R&D project, not a commercialization effort. Yet the reports published here and at other aviation news sites indicate Boeing is working the supply chain (and possibly some select airlines) to fully define a commercial product. They would not be doing that if the basic decisions were still in the lab. Similarly for the engine: one of the reasons for the “business case” smokescreen is to keep the pressure on the engine makers to improve their performance guarantees and price.
Yep
I tend to agree, Boeing might have a preliminary design ready but it needs to fit robotic manufacturing and those robots are not available just yet, so the Board of directors need to know how fast, how accurate and to what price the fuselages can be built, probably building dummy composite fuselage sections somewhere in Washington state as the robots get good enough for the trails. Just look at the Airbus A321neo robotic problems in HAM that should be much easier of a well known design.
Similar for engines, what performance to what price and the risks that PWA and RR sky high promises are broken and GE’s lower risk design will not be so low risk. All need to be assured before the board gives ATO. I assume all major suppliers +Boeing wants the US government to help with early money to reduce the risks. Maybe Trump will pay up for the Air Force 2’s based on the 797.
Hello Claes,
Regarding: “probably building dummy composite fuselage sections somewhere in Washington state as the robots get good enough for the trails”.
And perhaps Boeing management and/or the board also want to see static test results. preliminary flight test results, and bug/problem reports for the first few shipsets of wings made for the 777-X in Boeing’s new Everett composite wing plant using new technology that is also slated for the 797?
https://www.flightglobal.com/news/articles/picture-boeing-powers-up-777x-test-aircrafts-syste-454190/
It comes down to how good are those robot built parts and how quickly can they be made in I assume cheaper soft tools.
So the directors must decide if the progress is positive or if problems pop up more quickly than they are solved as they invest in better robots, analytical models and tools for the more complex trails.
They can ask for more and more testing of the manfacturing system up to Paris Air Show 2019 when price, performance and deliveries must be firmed up for the first model ( 797-8) and they will have a few years to improve the design for the next ( 797-9) to make parallels to the 787 program development.
No matter what is said for the consumption by the analysts this programme will only make financial sense as part of a wider learning of skills and process improvements for a future NSA.
Totally agree, and on this principle they will launch it.
By the time Boeing decides if it will make a 797 the customer s will have bought something else. And this is a “new” plane so Boeing will deliver two years late just like the 787
The 787 was much latter than two years
From rollout to in service was 4 years
“Later, not latter.@
Ahh, the spelling police!
We have been freed by LOL, now I feel freed.
My access is oddly changed and I have not tried to correct it.
So I don’t have the review period to correct. I am ok with it.
For the NMA design, I believe the best reference point is the recent Airbus A321lr flight from Seychelles to Toulouse, carrying the equivalent of 180 passengers 4,100nm. The NMA, specifically the 797-7x, should do exactly that, with 30% more seats and twin aisles. The wing and engine optimal size should be based on that.
A 30% step change in guage over the A321 provides differentiation. The cabin would be about a 4m stretch of the A321 cabin at 2-3-2, or a 9m stretch of the cabin at 2-2-2. Then the 797 can then be shrunk 5m to trade fuselage weight for fuel. Or follow the A321xlr playbook, and build the 797-7xlr, add 5t of mtow and more fuel tanks.
Seems like low hanging fruit to me.
A321 @180 seats is using 8 rows at 2-2 and ~25 at 3-3 with reaaaaly large seat pitches (i.e. a lot of wasted space from an airline perspective)
a 2-3-2 MOM could do 234 (130% of 180) in the same or less fuselage length than an A321 10 rows of 2-1-2 and 26 rows of 2-3-2 with a still reasonable but denser seat pitch.
Ted:
Those are some great ideas!
Granted Boeing has no idea what they are doing so they need all the help they can get.
I guess they’re welcome to their opinion.
I’m leaning towards a twin aisle 757-300 as the aircraft to replace. 175′ long, 2-2-2 metal fuselage, KISS principle, keep it sircular stupid, 14′-4″ outside diameter, 44K engines, 44m wing, or thereabouts.
Ted:
I hate to enlighten you, but Boeing is the mfg, not you.
You have an opinion, they have the hardware.
So opine all you want but they don’t even know you (or I) exist.
Point taken. My personal opinion for Boeing through the Leeham comment section is tilting at windmills (persistently engaging in a futile activity).
Hello Ted,
Your proposed 14 ft 4 inch diameter 6 abreast airliner would have 12.5 percent greater perimeter per passenger abreast than a 737, and 8 percent greater perimeter per passenger than an A321 or Boeing’s proposed NMA. It would thus have significantly greater fuselage weight and skin friction drag per passenger, and inferior per seat costs, than an aircraft with a 737, A321, or NMA fuselage cross section built with the same engine and fuselage construction technology. It will consequently never be built, since the airlines who would be the customers for such aircraft have the services of competent aerospace engineers who would take about 30 seconds to ascertain these facts. See calculations below.
Results are listed from lowest value (highest efficiency) to highest value (worst efficiency). Efficiency will also be subject to the fuselage not becoming to stubby or too slender for near optimal streamlining, structural stiffness, and control surface effectiveness. MOM7-200 is an NMA like fuselage cross section.
Boeing 737: 148 W x 158 H inches near circular, 6 abreast.
Average Diameter = 153 inches
Perimeter Pi x AVG Diameter = 480.7 inches.
Perimeter per Passenger = 80.1 inches.
MOM7-200/NMA: 194 W x 176 H inch ellipse, 7 abreast.
Perimeter = 581.5 inches.
Perimeter per Passenger = 83.1 inches.
A321LR: 155.5 W x 163 H inches near circular, 6 abreast.
Average Diameter = 159.25 inches
Perimeter Pi x AVG Diameter = 500.3 inches.
Perimeter per Passenger = 83.4 inches.
14 foot 4 inch circular fuselage, 6 abreast.
Diameter = 172 inches
Perimeter Pi x Diameter = 540.4 inches.
Perimeter per Passenger = 90.1 inches.
I calculated the perimeter of circles and near circles according to Pi x average diameter, for the elliptical MOM7-200/NMA I assumed that the cross section was close enough to a true ellipse for the ellipse perimeter calculation tool at the link below to give an acceptable answer.
https://www.mathsisfun.com/geometry/ellipse-perimeter.html
Before I get flamed by A320 fans, I will note that the lower perimeter per passenger of 737’s vs A320’s is what allows them to end up with similar per seat costs to an A320, in spite of some of the less efficient features of the 737’s older design, such as smaller engine fan diameter due to lower landing gear height, and larger tail surface area due to pre FBW design.
For those about to post that an NMA would have greater cross section area than an A321, please read the following excerpts from part 20 of Bjorn Fehrm’s free series on aircraft drag reduction before posting. Also note that aircraft fuselages are mostly hollow structures, in which most of the weight is in the surface skins and their supporting frames and stringers.
“We are assuming our aircraft is the A320neo type with a cabin with 180 seats, all filled with passengers.”
“The Parasitic drag has Air friction drag as the dominant part but also contains drags we’ve discussed like Form drag, Transonic or Compressibility drag and Interference drag.”
“There are other drag factors, but these are the main ones and the ones we have discussed. The important ones are Air friction drag and Induced drag. These represent 85% of total drag of an aircraft.
This is why aircraft designers try to minimize the total surface of the aircraft at the same time as they try to make the wingspan as wide as possible.”
https://leehamnews.com/2018/03/09/bjorns-corner-aircraft-drag-reduction-part-20/
Hello TransWorld and Ted,
Regarding: “Granted Boeing has no idea what they are doing so they need all the help they can get.”
According to the excerpts below from a 8-6-18 Airways Mag interview with Delta CEO Ed Bastian, and a 2-22-18 Australian Business Traveller interview with QANTAS CEO Alan Joyce, these two airlines CEO’s do not share your opinion that with regards to the NMA, Boeing has “no idea what they are doing”.
“Q: With that behind you, you’ve gone on record saying that Delta would consider Boeing’s NMA as a launch customer. In your opinion, what would that plane’s perfect specifications be to Delta?”
“A: We think about that plane it would replace, the 767s and 757s.
We have 80 767s, about a hundred 757s. We want something in the 225 to 275-seat category.
We want to take advantage of the fuel efficiency and the lighter structure, the modern day amenities for that aircraft and I think the range is going to be an important determinant, as well as making certain Boeing isn’t overbuilding the aircraft.
And that’s why we want to be in there if given the opportunity to be an early, early customer.”
https://airwaysmag.com/interview/edbastian/
“Qantas CEO Alan Joyce remains upbeat about the prospects of Boeing’s forthcoming mid-sized jet, informally dubbed the Boeing 797 and expected to take wing in 2026.
Joyce sees the Boeing 797 as an ideal candidate for transcontinental flights as well as some nearby Asian routes, making it a potential replacement for the Airbus A330s.
Speaking at today’s briefing for the airline’s half-yearly financial results, which saw Qantas turn in a bumper six months with a pre-tax profit of $976 million – a 15% boost over the same period last year – Joyce talked up the Boeing 797 as “a lighter aircraft than some of the widebody, twin-aisles that we have today.”
“It has a range that’s designed to fly transcontinental and maybe into South-East Asia so it’s not over-spec’d for the domestic operation.”
Qantas previously planned for the Boeing 787-9 to take on east-west routes, but now sees the Boeing 797 as a better fit.
“Our thinking has evolved,” Joyce told Australian Business Traveller on the sidelines of the airline’s first Dreamliner delivery in Seattle. “While the 787 as with the A330 are pretty powerful, they are over-spec’d” for domestic flights, “so the economics do not work.”
However, with a larger passenger capacity than the airline’s current Boeing 737 workhorses, there’s also scope for it to take on the popular ‘triangle routes’ from Sydney to Melbourne and Brisbane.
“We’re now at the cap of 80 movements an hour for four or five hours every day already” Joyce explains.
“By 2026, when this aircraft is proposed to be produced, the airport will probably completely full by then. So the way to grow will be bigger and bigger gauge aircraft,” with the added appeal of the Boeing 797 being able to do its ‘turn-around’ from inbound to outbound flights as fast as the Boeing 737.”
https://www.ausbt.com.au/qantas-ceo-increasingly-bullish-on-the-boeing-797
Keeping in mind Boeing already has the 797 layout designed.
And that is the $64 question. Is there a market for it as noted the A321 x 180 pax wastes a lot of aircraft because it can’t do the distance with the fuel needed.
Singapore is doing a flight to New York with 172 and an A350-900ER. If they can make money it works.
But it only works because they have a lot of routes the A350 can carry a mixed load on making money to allow a single A350 route to NY (support of A350 in larger numbers)
That NY bird(s) will have no use on any other route (economically) – complete lack of flexibility if things change. So you have 3 to 5 aircraft for a single route (not sure how many days a week it runs) – any other route and its a wasted bird.
180 kegs of ballast is Airbus’ baseline for their flight, not mine. 30% is 30%. A321 at 180, 200, or 240 seats, 797-7x will be at 234, 260, or 300 seats, relatively.
The main question still stays – the cost (both production and use) of narrow-widebody x long-narrowbody !
@S543:
By my gut feeling and per historical precedence, @ equivalent/similar seat count+cabin density, long narrowbody format always win against short widebody format in terms of production cost & op cost per seat.
The only way a widebody can still win is belly cargo Rev$ potential(e.g. LD3) unaccounted for in the op cost per seat equation. This is tricky for Boeing to define the 797 design config because from what I hv read, potential 797 customers are almost evenly split(by potential order size, not simply quantity of airlines) between:
Group A:
Want belly cargo container i.e. a heavier, taller fuselage height – mainly fm FSC customers based outside N.America.
Group B:
Don’t want belly cargo container i.e. a lighter, shorter fuselage height – mainly fm customers within N.America and LCCs.
I strongly believe 752 did not cannibalized 762 sales in the late 70s/early 80s because of that diff in cargo capability despite both were:
1. Developed based on similar tech/gate size limit in parallel.
2. Marketed in parallel by Boeing.
3. Similar in seat count(228 vs 245, 1-class)
4. Almost identical range for the initial 752 vs initial 762.
Large carriers such as BA, UA, CO, AA, TW, DL even betted on both. Fast forward to today and given the existence of 321LR and likely 321XLR, 797 may still hv a biz case only if the format preferred by customer Group A will be chosen.
Belly cargo is prominent in long range flights, its not in shorter domestic range flights in US and Europe.
Asia may want more, but is that a killer? Who knows.
The single aisles have room for some critical high cost fast freight. They don’t for regular. Asia works fine with the SA.
How much that is a factor in Asia sale then is a big question.
It may be more a want than a have to.
HelloFLX,
Regarding: “long narrowbody format always win against short widebody format in terms of production cost & op cost per seat.”
In his 11-14-18 paywall post “How useful is an NMA, Part 6” on this website, Bjorn Fehrm came to a different conclusion than you regarding op cost per seat of the NMA vs. long narrow body competitors. The excerpt below is from the free summary of this post. The “compared types” referred to in the excerpt are the A321LR, A321XLR, A330-800, and 787-8. By using historical precedent you ignore any consideration of differences due to the main proposed innovation of the 797, i.e. using the elliptical fuselage made practical by composite construction to combine the cargo capacity of a single aisle aircraft with the passenger cabin width of a 767, which reduces perimeter per seat abreast from that of a 767 to that of an A321, resulting in fuselage wetted areas, skin friction drag, and fuselage weights similar to those of a single aisle aircraft of equivalent passenger capacity.
“Now we finish the series by comparing the NMA to its main alternatives for range and operational economics.
Summary:
When comparing the NMA with its competitors, the same cabin type and ruleset must be used for all aircraft.
Using a common ruleset and measuring over typical long range operation, the NMA will be the most economical aircraft of the compared types.”
Composite construction for fuselage insnt likely to be worthwhile for a small widebody that is purposely limited range. For very good reasons the most efficient fuselage shape has been circular followed by double bubble. Elliptical may be good for aerodynamics but looses out in structure weight. But perhaps the long delay on business case is because test sections of composite fuselage made from panels have failed in structural test?
Hello Duleofurl,
Regarding: “perhaps the long delay on business case is because test sections of composite fuselage made from panels have failed in structural test?”
On what source or sources do you base this statement? Maybe instead the test panels have been projected into black holes in another dimension by aliens from the Andromeda galaxy who do not like and won’t allow elliptical fuselage shapes?
Source? I dont have one as its speculation on my part- thats why I said ‘perhaps’
Boeing isnt saying anything, as all information about 797 is held tightly.
But History is a guide to things they may want to avoid “this time around”
“But Boeing is learning how hard composites can be to analyze effectively and build economically for commercial jet structures. The company has had to delay the 787’s introduction because elements of the composite-made wing box–the major structure inside each wing–buckled in stress tests.”
https://www.technologyreview.com/s/409929/boeings-composite-problem/
The key phrase is ‘ analyse effectively and build economically’, a new fuselage shape would raise challenges based on that criteria.
Thats was of course back in 2008, once we knew the extent of the 787s problems- something Boeing has vowed not to repeat. I was speculating that these sorts of things are now being checked more rigorously by physical testing before production begins.
Plus this part describing Boeings testing process
“Boeing’s mechanical stress tests start with representative pieces (known as coupons), then move on to progressively larger parts of the structure, and finally to the full structure. Boeing puts the structural parts into huge hydraulic machines that bend and twist them to mimic stresses that go far beyond worst-expected conditions in real flights….”
Its a reasonable assumption to assume Boeing is now doing testing of possible fuselage sections on a new 797.
Duke: Boeing had a good idea of what the CFRP would do. Perfect? no.
In the body join, it actually was designed right in the first place then got thinned too much in a weight saving move.
I would think you of all people would get that design these days is all about modeling, testing, finding out where your model was wrong (both too much or too little) refining it, testing it again.
At this point they have 10 years of working with the material specifically in pre tests to finish structural test.
Please note, the wing did not break and at 155% they gave up trying to .
The 787-8 is still overweight per design though performing to spec.
They then refined the -9 to be below weight deign.
787 rear fuselage is not the same though the rest apparently continues (it keeps selling so they may do the whole thing one of these days)
Boeing was a huge part of the B2 work (they contracted to help Northrup Grumman out when that went bad execution wise).
My take is just a dislike of Boeing and the NMA is driving the view, clearly Boeing has plenty of experience with CFRP to know what they can and ca’t do, what it cost for a fuselage (if they do it that way) and the wing for sure will be.
It may not be a commercial success, that rests on a lot of factors, but that Boeing can’t do what they say they can is nonsense.
The ellipse that your defining is very eccentric – about 0.5 to 0.6 where 0 is a circle and 1 is a straight line. Also, there’s no way it could be lighter than a circular cross section, even on a per pax abreast bases. It would also have a greater cross sectional area.
You’re talking about a fuselage cross section that has a narrowbody height and a widebody width.
Making the cross sectional mildly eccentric mitigates the issue but does not come close to solving it.
Hello Chris Lee,
Regarding: “The ellipse that your defining is very eccentric – about 0.5 to 0.6 where 0 is a circle and 1 is a straight line.”
That is incorrect, the fuselage dimensions that Boeing would logically be contemplating to give 767 cabin width, with single aisle below floor cargo capacity, would be approximately 194 inches wide by 176 inches tall, which is a width to length ratio of 1.10, and which gives a perimeter per seat abreast very slightly less than that of the A321. See an outline of my calculations below, which agree with the results stated by Bjorn Fehrm in his several series of articles on the NMA on this website over the last several years. Since you are claiming that my calculations and Mr Ferhrm’s are in error, please promptly share with us the details of your calculations.
Perhaps, in addition to your calculations, you could share with us your education and experience in aviation that has provided you with the knowledge to calculate aircraft design parameters more accurately than Mr. Fehrm, an ex fighter pilot and Saab aerospace engineer who worked on the design of the Saab Gripen fighter, and the teams of aerospace engineers that Boeing employs. Which aircraft designs have you worked on?Myself, I admit to being an aviation amateur, albeit one with a masters degree in physics who has been working for 25 year as a medical physicist, which is a field of employment which requires one to be able to obtain correct answers to math/science problems, at least the vast majority of the time.
Regarding : “Also, there’s no way it could be lighter than a circular cross section, even on a per pax abreast bases. It would also have a greater cross sectional area.”
This statement is also erroneous. An aircraft fuselage is a mostly hollow shell structure, with weight concentrated in the surface skins and supporting stringers and frames. The empty weight is thus largely a function of the its SURFACE area, not cross section. The weight of the air inside the fuselage, composite floor boards, floor supports, and seats and furnishings is small compared to that of the surface skins, stringers and frames which support structural, pressurization, and aerodynamic loads. Additionally. the weight of seats and furnishings for a particular number of passengers is not a strong function of how many seats are placed in each row of seats. One hundred seats lined up in a single row weigh the same as 20 rows of 5 seats , or 10 rows of 10 seats
Following are some examples of the correct parameter for comparing, at an approximate level, the weight and drag efficiency of different fuselage designs, i.e. perimeter per passenger, calculated for each of the four fuselage designs that Bjorn included in an illustration in the free summary of his 3-18-15 paywall article: “Redefining the 757 replacement: Requirement for the 225/5000 Sector, Part 6”, and also for a Boeing 767.
The results are listed from lowest value (highest efficiency) to highest value (worst efficiency). Efficiency will also be subject to the fuselage not becoming to stubby or too slender for near optimal streamlining, structural stiffness, and control surface effectiveness. MOM7-200 is an NMA like fuselage cross section.
MOM7-200: 194 x 176 inch ellipse, 7 abreast.
Perimeter = 581.5 inches.
Perimeter per Passenger = 83.1 inches.
A321LR: 163 x 155.5 inches near circular, 6 abreast.
Perimeter = 500.3 inches.
Perimeter per Passenger = 83.4 inches.
NSA6-200: 163.4 inch circle, 6 abreast.
Perimeter = 513.3 inches.
Perimeter per Passenger = 85.5 inches.
NLT7-200: 194 inch circle, 7 abreast.
Perimeter = 609.5 inches
Perimeter per Passenger = 87.1 inches
Boeing 767: 198 x 213 inch near-circle, 7 abreast.
Perimeter = 645.6 inches.
Perimeter per Passenger = 92.2 inches.
Significant points:
I) The perimeter per passenger of the MOM7-200 and A321LR are within o.4%.
II) The perimeter per passenger of the 767 is 11.1 % greater than that of the MOM7-200 and A321LR.
I calculated the perimeter of circles and near circles according to Pi x average diameter, for the elliptical MOM7-200 I assumed that the cross section was close enough to a true ellipse for the ellipse perimeter calculation tool at the link below to give an acceptable answer.
https://www.mathsisfun.com/geometry/ellipse-perimeter.html
Here is a link to the March 2015 Bjorn Fehrm paywall post from which I took the fuselage dimensions that I used in my calculations above, except for those for the 767. Do the fuselage diagrams in the free introduction of this article not clearly show the assertion that an NMA would have a fuselage eccentricity of 0.5 to 0.6, to be wildly incorrect?
https://leehamnews.com/2015/03/18/redefining-the-757-replacement-requirement-for-the-2255000-sector-part-6/
Anyone who is struggling with why designers of 500 mph jet airliners place far more priority on minimizing fuselage surface area than they do on minimizing fuselage cross section area, will probably find part 20 of Bjorn’s Fehrm’s free series on aircraft drag reduction, from which the following excerpts are taken, to be informative. Form drag which is largely dependent on cross section area is important for non-streamlined objects like bowling bowls and rectangular boxes; however, for a carefully streamlined object like an airliner fuselage, skin friction drag, which is largely dependent on skin SURFACE area becomes dominant.
“We are assuming our aircraft is the A320neo type with a cabin with 180 seats, all filled with passengers.”
“In level flight at FL370, our cruise drag, at our cruise speed of M0.78 and average mission weight, is 7,900lbf. This means our engines need to produce 3,950lbf each to keep a constant Mach of 0.78.
The 7,900lbf of drag is composed of 4,700lbf of Parasitic drag or drag independent of lift and 3,200lbf of Induced drag or drag caused by lift.
The Parasitic drag has Air friction drag as the dominant part but also contains drags we’ve discussed like Form drag, Transonic or Compressibility drag and Interference drag.”
“There are other drag factors, but these are the main ones and the ones we have discussed. The important ones are Air friction drag and Induced drag. These represent 85% of total drag of an aircraft.
This is why aircraft designers try to minimize the total surface of the aircraft at the same time as they try to make the wingspan as wide as possible.”
https://leehamnews.com/2018/03/09/bjorns-corner-aircraft-drag-reduction-part-20/
Here is some more reading material on the importance of skin friction drag for streamlined bodies.
“When the drag is dominated by viscous drag, we say the body is streamlined, and when it is dominated by pressure drag, we say the body is bluff. Whether the flow is viscous-drag dominated or pressure-drag dominated depends entirely on the shape of the body. A streamlined body looks like a fish, or an airfoil at small angles of attack, whereas a bluff body looks like a brick, a cylinder, or an airfoil at large angles of attack. For streamlined bodies, frictional drag is the dominant source of air resistance. For a bluff body, the dominant source of drag is pressure drag. For a given frontal area and velocity, a streamlined body will always have a lower resistance than a bluff body. For example, the drag of a cylinder of diameter $D$ can be ten times larger than a streamlined shape with the same thickness (see figure 1).”
https://www.princeton.edu/~asmits/Bicycle_web/blunt.html
AP_Robert, that got me thinking what is the optimal proportion for an airliner. Comparing two 270 seat airliners, one 3-3 with a cabin of 135′, one 3-3-3 with a cabin of 90′. I went with a 1 to 1 cone on the front and a 6 to 1 cone on the back. I got 6,400 square feet for the 3-3, and 7,700 sf for the 3-3-3, so 20% more skin drag. But the 3-3-3 has 55% more volume, so that is theoretically a more efficient shape. Passenger decks on the lower front hold of the 787-8 or A330-800? I’m sure there are other factors, but from a volume per skin drag perspective, that is one perspective.
AP Robert
I make it an ellipse 193″ wide by 172″ tall. Eccentricity isn’t the same as height to width ratio.
If you ‘design’ a cabin cross section making similar assumptions about seat width, aisle width and structure thickness you get something similar to the above result.
The assumption that just because you increase a linear dimension by a factor then the weight increases by that same factor is incorrect, the weight will increase by the cube of that linear factor. You’d expect a linear increase of dimension of 10% to result in a weight increase of 40%, all else being equal
I could not see Bjorn’s working as its paywall protected. If the two aircraft are both moving 225 people with the same amount of fuel, then the two aircraft will be competitive, assuming they also cost the same to buy & maintain. The indications are that the NMA will fail on all three counts. It won’t use the same quantity of fuel because it will be heavier, it won’t have engines of sufficiently greater s.f.c. than a narrowbody and it will cost more to buy and maintain. Also it will come later to market.
I don’t want to get into an argument about qualifications, arguments should stand by themselves, but I refer you to the Breguet Range Equation on Wikipedia. If the aircraft fly at similar speed, altitude and use the same kind of fuel (I think you’ll agree on that), then range only depends on L/D ratio, s.f.c. and Log to Base e of the MTWO/final weight (e.g. the fuel used). If we assume that L/D is the same, then a heavier a/c must have significantly better sfc to compensate for the difference Log to base e of the ratio of weights. No engine technology that I know of is on the horizon to provide that, and even if there was it would be just as applicable to a narrowbody as a widebody.
Sorry I couldn’t answer direct – the site wouldn’t let me.
Seasons greetings and goodwill
@Richard Brown:
“By the time Boeing decides if it will make a 797 the customer s will have bought something else”
Partially agree. E.g., that’s essentially the argument behind why IAG has not shown much interest in the 797 and increasingly leaning towards the 321LR(1st @ EI).
On the other hand, if ATO/launch will happen mid-2019 as this JPM analyst is predicting, that’s just half yr away for potential customers to wait which is inconsequential for investment on a new fleet type @ this kind of magnitude+long term fleet impact. Historically for this industry, if early potential customers are really interested in the 797 concept after Boeing board clears 797 for ATO, they can already commit via MoU/LoI on the condition that Boeing will actually launch that program within a fixed period(typically 12mths) and freely walk away fm the MoU/LoI if Boeing decide not to or defer decision till much later.
“..this is a “new” plane so Boeing will deliver two years late just like the 787..”
Actually, 787 was over 3.5yrs late relative to original EIS schedule so your prediction of 2yrs late for 797 would theoretically be an improvement.
On the other hand, 330Neo wasn’t exactly a “new” plane with largely existing engine(T1000->T7000 conversion) and airframe(90%+ is a 330Ceo) yet Airbus delivery was still late by 1yr.
FLX, yes the A330 neo was late by a year, but the rollout was much earlier, the delay I think was mostly getting the Etops from Rolls on the engine ( who ere consumed by their other problems). Will a NMA even need Etops at EIS, especially if they give US carriers first slots ?
The problem was the engines and the engines was not ETOPs issue.
The Engine is a derivative of the Trent 10 that had to be finished first. What was going on internally we likely will never know.
Publicly they had failures on the 1000, they were tying to figure out what was going on (and failed to until recently) with more issues in cracked blades vs corroded ones.
They took the worst of a flawed engine and then came out with two subsequent engines. All those engines will have to get blades replaced in the future.
Firing several thousand people of course helped things out immediately.
Have to look it up but 180 ETOPs with need to prove it at 3000 hours.
Happy Airbus.
On the other end of the scale is the XWB’s, had apparently only 2 In Flight Shutdowns in 3 million hours, so they are starting to get something right.
The T1000 was a debacle contributed by pressure to get it on the 787’s wing, if they had another 2 years it could have been a different situation?
Don’t hope the same happens with the 797.
Not a etops issue for TAP?
Flight global says different
https://www.flightglobal.com/news/articles/a330-900-secures-etops-with-engine-life-restrictions-453844/
Having a restriction means full etops is not complete
@Dukeofurl:
“the A330 neo was late by a year, but the rollout was much earlier”
I don’t think so…..unless U define a difference of only 1mth as “much earlier”:
787 vs 330Neo
Program launch= Apr 2004 vs Jul 2014
Official roll out= Jul 2007 vs Sep 2017
Duration= 3yrs 4mths vs 3yrs 3mths
“..the delay I think was mostly getting the Etops from Rolls..”
In which I’m totally aware of among other issues due to RR. However, when I couldn’t submit my homework on-time, whether it was because my dog hate my homework or I was just too lazy to do it made no difference to my teacher….
“Will a NMA even need Etops at EIS, especially if they give US carriers first slots?”
I bet U every cent/penny in my pocket, NMA/797 will hv @ least ETOPS180 upon EIS because:
1. No customer will accept it without ETOPS when types smaller/cheaper than NMA/797 such as Max/320Neo families already offer ETOPS180 today…let alone its nemesis 321LR.
2. U.S. customers may want to deploy NMA/797 on DOMESTIC ETOPS routes such as to/fm Hawaii shortly after EIS e.g. that’s exactly what UA did with their 1st batch of 777 23yrs ago.
3. Even if 1st slot may be for a U.S. customer, the 2nd, 3rd, 4th, etc. may not be. That won’t buy Boeing much longer time to secure ETOPS after initial EIS.
There are photos of the first production A330 -900 rolled out of the factory paintshop- without engines- dated end of the year 2016. So it was 2 years later for EIS.!
https://www.ainonline.com/aviation-news/air-transport/2017-06-09/first-flight-airbus-a330neo-expected-end-summer
And yes formal delivery to TAP was only a few weeks back
This site confirms my view of a ‘year delay’
“Airbus finally delivered the first A330neo to TAP Air Portugal with one year delay. The Portuguese flag carrier was supposed to receive the [plane] in the ‘fourth quarter of 2017.’
https://airlinerwatch.com/airbus-finally-delivers-the-first-airbus-a330-900-of-tap-air-portugal/
Im sure they will be very happy with the plane, along with many airlines who have ordered it.
It would far more complicated than ‘just late paperwork from RR’ for a years delay. The RR engines are fine, just the rigourous testing for etops along with RR busy schedule of new engines- and other problems no doubt- impacted the completion.
Of course, nothing to look at here folks, just move on,
As the 797 opens up markets and there is nothing in those markets, its a new frontier.
767 is too heavy, A330-800 is too heavy.
The A321 as good as it is, is range constricted with the desire numbers of passengers.
There simply is nothing in that space that can do the range and pax with SA economics.
Boeing may not be able to pull it off, but other than a Singapore like NY route, you need pax numbers or it simply does not work. Yes the longer range 737 and A320s have taken some of the bottom of that area (at a cost)
They have not take the middle of the 757 though how much that was really used is not a whole lot either (but it also is an older less economic air-frame ) more useful as its been paid for and operated in a better fuel price climate.
It can relieve congested routes as well, but like the A380, you have to over come the flexibility of more aircraft vs a single one.
There clearly are a large number of different airlines that have to calculate how this would fit into their network.
The success of it depends on it fitting in with enough to sell 2000 or more.
Stay tuned.
Something doesn’t add up here in the bigger picture. Boeing had one fuselage in the 130-200 seat class in 50 years now two wide bodies in 20 years in the 220-320 seat class?
Airbus in more need of a new Twin-Aisle with 250-275 seats and range somewhere between 5-6K Nm, 50-60Klb GTF/Ultrafan engines maybe what they waiting for, EIS 3 years or so after the 797. In the mean time A321XLR’s and A322’s skimming some cream from the bottom of this market.
Couple of points to ponder …
The need for cargo – what is the revenue delta between a 100KG of cargo and an economy passenger?
My simple Big Auto view on this is that cargo pays 30-40% what the passenger would pay. Therefore cargo is very much secondary in most situations.
The more light duty the plane is the less influence cargo has in its normal operation. Which is a good thing if you are wanting to develop the world’s wimpiest TA for your next project.
135T MTOW TA if it ever gets off the ground would be passenger only unless it is doing local flights with half tanks.
Replacing Classic 7double7’s with the NG model?
Interesting given they went out as 250T and 300T models and they are going to be replaced by a 350T model.
“The more light duty the plane is the less influence cargo has in its normal operation.” Which I think describes the success of the A321. Cabin space is king, range and freight capability are an albatross in many cases.
Scott, did these guys get an answer from Muilenburg and/or Smith on whether the 797 will hit the 15% overall profit target set for BA corporate?
@Montana: Nothing in the research note on this and I doubt Boeing would have been that specific. They don’t talk about specific program profits, let alone paper airplane profits.
Thanks, Scott. Just thought I’d ask since Muilenburg has made a big deal of this metric in the last couple of years.
@uwe
Imho Boeing spent a lot of time making the right choice and getting a “super aircraft”.
If they do not disclose anything it’s not to make the same mistake as the 787 because Airbus with the A350 have followed the launch despite the fact that the 787 Dreamliner won on the market makes the A350 … They protect their investments
As an investor, I always hate it when i see overly paid executives go into spin mode.
Seifman writes that Boeing sees more orders for the 777X coming in 2020,
“when legacy 777 operators look to replace aircraft.”
In other words . . . let us kick the can down the road and don’t expect too much from us in 2019.
Muileburg and Smith have made a ton of dough in the last few years. Wall Street expects them to deliver results not excuses.
I don’t see United Or Delta buying the 777x it’s to big, and Unit d would have to get our of it’s contract for 350s. Same with AA, and clearly Delta has already told Boeing to piss off. Boeing better hope EK still wants it’s planes
More land for parking airplanes, or more land for something else? Below is an excerpt from the 12-18-18 Seattle Times story at the link after the excerpt.
“Boeing has taken an exclusive lease option for 58 acres of undeveloped land west of the main runway on Paine Field “to develop additional aerospace manufacturing facilities to supplement its existing operations” in Everett, according to documents approved Monday evening by the Snohomish County Council.”
https://www.seattletimes.com/business/boeing-aerospace/boeing-explores-potential-expansion-at-paine-field-could-it-be-for-the-797/