Don’t look for commercial BWB airplane any time soon, says Boeing’s future airplanes head

April 3, 2018, © Leeham News: New airplanes for the foreseeable future are unlikely to look radically different than the tube-and-wing configuration that’s been around since the dawn of manned flight.

Yes, there are unmanned aerial vehicles (UAVs) that look very different. Yes, there are the B-2 and B-21 bombers that are flying wings.

Scaled Blended Wing Body airplane. Source: NASA.

And, yes, there is the Blended Wing Body concept that was created by McDonnell Douglas and tested, in scaled-size models, by Boeing, which acquired MDC in 1997.

But don’t expect to see a BWB either as a freighter or as a passenger airplane any time soon, says Boeing’s VP of Product Development and Future Airplane Development.

Nice idea, not very practical

Mike Sinnett says the configuration works. It’s economic. But its very configuration works against the airplane for commercial application, he says.

“The characteristics of a freighter, in general, are you want to be able to use the airplane at airports that aren’t typically as improved as airports are that we use passenger airplanes at,” he told an evening meeting March 28 at the University of Washington in Seattle. The event was organized by the American Institute of Aeronautics and Astronautics.

“Airport compatibility is a really important part of that,” he said.

Mike Sinnett.

“A BWB works great because it’s got [wing] span. It’s got more empty weight than a tube-and-wing configuration for a revenue ton of cargo. It’s going to carry more operational empty weight. It’s got span and it’s got a fair amount of wetted area.

Sinnett said designers will make the weight trade for span when there is a lot of range needed. For short missions, for example, four hours, the weight trade isn’t worth it.

“A four-hour mission isn’t going to work because you’ve got more weight and you’re not taking advantage of that span,” he said. Long cruise segments are required to make the aerodynamics work to their greatest benefit.

Large wing span may also conflict with airport compatibility, he said.

Cargo aircraft also need to be “loadable” quickly, he said. Existing freight containers and cargo loading systems need to work with the BWB.

Required economic improvement

“And, in general, unless it’s more than a 20% improvement over what you have today,” a new airplane isn’t justified. “For more than a 20% improvement, people will make the change,” he said.

Sinnett that that Boeing’s studies have only shown a few cases in which the economics are better than 20%.

Military cargo operations aren’t tied to commercial requirements.

“You can imagine someday where military cargo operations, long-range, where you’re going from hub-to-hub,” he said. But so far, there hasn’t been a customer requirement for which a BWB makes sense.

Passenger requirements

Sinnett said passenger use presents different challenges.

In a BWB, the center wing box is also where the passenger cabin is. The wing box needs to be tall enough to accommodate 95% of the world’s men to be able to stand upright.

Space is required for the carry-on bags. There has to be room above and below the floor for ventilation and systems.

“That means you have to have a certain height. Once you have a certain height, you’ve got to have a certain width for the box to work,” he said. “That translates into a certain span. You’ve got a really big airplane at that point.”

This results in the multiple hundreds of passengers, he said.

“It’s hard to do with a small airplane to get enough height in the center box.”

Another challenge

The design creates another challenge: developing a family of airplanes.

Boeing, as with all manufacturers, like several models of a basic design.

This enables the OEM to create, relatively inexpensively, several sub-types to cover the massive R&D costs and post high profit margins (at least in theory) the longer the program is in production.

With tube-and-wing design, it’s a relatively simple task to stretch or shrink the base design to create a three-member family.

The 737 MAX has four sizes, the MAX 7, 8, 9 and 10. Although there were special challenges to overcome for the MAX 10, the stretch was nevertheless accomplished for comparatively little money.

A BWB, with its unique shape, doesn’t lend itself to a stretch or a shrink, Sinnett said. “You take the most expensive part of the airplane, the non-constant section, and growing it in a non-constant way, or shrinking it in a non-constant way. It’s really hard.”

51 Comments on “Don’t look for commercial BWB airplane any time soon, says Boeing’s future airplanes head

  1. The Greens will not like this. In Sweden Aviation is now their enemy number one.

    • For a country with such a rich heritage in aviation that is a shame. I’ve always admired Saab. Great planes and great cars. Love their fighters but my favorite plane is the Saab 2000.

  2. I kind of discussed this recently as parts of the NMA discussions. The many innovative, game changing concepts are aimed at the bigger public as PR. They want to feel good, see progress, innovation and game changers for sustainability. They get what they want, graphically.

    It’s how our society and the now huge sustainability industry works these days. Creating perceptions / mental comfort is more important than reality.

    https://lh3.googleusercontent.com/-DowitrCzH-4/WcpsKSc4J1I/AAAAAAAACw4/tSGvOzpEhLIxwB4O0lXFLR7fEiUHuB5NACLcBGAs/s1600/Aerospace%2BInnovation%2BSustainable%2BFuture.jpg

    • If you don’t play with ideas you will never know what works.

      Reality does rear its ugly head when a new aircraft cost 10+ Billion US to get to market.

      Shoot, a couple of those and you can’t do share buy backs for crying out loud.

      In reality there is a balance and as they say in the US, you go off the reservation and things get interesting.

      You don’t want to be staid but you also don’t want to go under.

      And for someone who likes to design aircraft for Boeing and Airbus (regardless of the feasibility) maybe a bit of throwing stones in a glass house?

      I seem to remember an A380 twin?

    • They get what they want, graphically.

      Is that why you post graphics all the time on a.net and link to them here?

    • I do post a concept now and then, but no flying wings, solar cell powered dream machines, flat bodies, transparent fuselages or WB at NB cost flying green miracles saving the earth for our grand children. Aviation is increasingly poluting & 75% of passengers are tourists. Slightly cleaner aircraft technology is washed away by 4-5%/ yr growth. Hello reality, smell the coffee.

      • True. There are just too many of us. This is at the root of all environmental problems. Humans are the new locusts.

        • I rarely have flown for tourist. Its (5 trips maybe in 60+ years) most of it has been family and sometimes family friend related.

          I am kind of stuck with being here (short some drastic remedies)

          I drive as economical a car as I could get that also worked for my wife (taller than I am)

          Never had any kids of my own so I did my bit there.

          A twin A380 is about as pure fantasy as it gets though (said with and taken with humor hopefully) .

  3. For freight this is fine but as a passenger this would suck what joy is left out of flying if you are a plane buff.

    • If it would work? Be interesting to see what they could do with LCD windows and or panorama displays.

      Last ride I had the lady in the seat by the window promptly went to sleep (I like to ride that side of the aircraft as we fly by where I grew up)

      Now that kind of sucked.

      • I agree Trans, I might be old fashioned but screens just don’t do it for me. I could put that on at home!
        Nothing beats looking out a real window.
        I know there have been plenty of complaints that the 787 window doesn’t darken all the way to black but I love the fact you can dim the sun yet still see out the window.
        I think nothing is better on long night flight than to rest your head on the window and wasth the cities drift by below… 🙂

        • The will develop enhance reality windows and inner celings making you look at a perfect sunny day or a mega star night and you coould not see it was fake. You will just be disappointed when walking thru the gate and see the haze outside.

          • Too much enhanced will also appears as fake. Especially when they start adding in airships that play ads on them

  4. to paraphrase Darth Vader “I find his lack of ambition disturbing”

    the tube and wing has been maxed (hah) out and all improvements at this point are low ROI refinements (when a 50 year old airframe (737) with 25 year old wings can get within a few % of the latest greatest (C-Series) you know you’ve reached a technological dead end)

    whether it be side by side double bubble (much of the aero benefit of BWB with all of the simple structure and derivative benefits of tube and wing) or BWB or Lockheed’s HWB, a step change in aircraft design is needed.

    a double bubble based on A320 fuselage dimensions and modern materials would provide a 10 across twin aisle capable the MOM mission @ 250 seats in a 25M long passenger floor and C gate compatibility and the airbus fanboy’s favorite – containerized cargo in the form of 2 aisles of LD3-45 containers.

    throw in Honda style overwing engine mounts and you get short, light landing gear with no restrictions on fan dimension. make it a canard planform with center fuselage main doors and you get even shorter main landing gear (due to further aft center of rotation) and a virtual quad aisle with no one more than 13 rows from the exit for ultra-fast turn times.

    split ailerons and large articulated winglets, along with the overmount/rearset engine pylons eliminate the need for a dedicated vertical stabilizer.

    combine all these design aspects with modern materials and engineering techniques and you would see on the order of 15% less structural weight per passenger in an easy to build, easy to extend, structurally and aerodynamically efficient design

    but McBoeing won’t even bother redesigning section 41 for MoM so the hell with it.

    • High thrust engines will not work (economically) on an over the wing install.

      They keep looking at concepts but it also keeps coming back to the reality that there are limits.

      If you came up with 40% more efficient but tripled your production costs?

      I would say that its says how hard the whole flying thing is that a 737 design that is 50 years old is still viable (or was made so)

      • The 737 tube is old but wings, engines, avionics is new x 3. It gives you a hint of what matters the most in aircraft design, (wings+engines). If it was not so profitable for Boeing they would have replaced it years ago, but Money talks..

        If Bombardier had designed the C-series with 3+3 seating of 180 pax much lower empty weight they could have seen more orders for airlines mainly flying short hops.

        • Claes:

          Sad truth and even engines only get you so much.

          There are no miracles on the horizon.

          ICE and the variations we are pretty well stuck with.

          • We all wait for the solution to gravity, but until then we need lift and it cost Engine Power to push the wing forward forcing air down making lift.
            If we get a passanger Aircraft with a glide ratio of over 100:1 the raising airstreams due to weather and sun heating the ground might be sufficient to keep it aloft together with thin solar panels covering the fuselage as on Solar Impulse 2.
            Using wire launch up to 3000ft will help. The solar panels on SI2 only had 45kW of Power, getting up to 500-750kW makes a difference and it can find use on certian routes in good weather condistions.
            Even with a 100:1 Cl/Cd and 750kW solar panels + wire launch at M=0.5 at 3000ft it cannot handle icing conditions and strong headwinds limiting its use.

        • Its called Airbus for reason ( a bad name none the less)
          Local buses havent changed much in shape either over last 60 years. Underneath, maybe most have moved engine to the rear now.
          Customers want low floors, easy grab handles, wifi- the things that matter , not flights of fancy from the CAD screen

          • You are correct Duke.
            Despite the technology, the airplane fuselage is just an iteration of a Victorian railway carriage.
            I still think there could be a better layout.
            I suggested a long time ago that a seat re-design could be beneficial. A theatre type set where the squab lifts could offer an alternative replacement for the overhead bin. Sorting out somewhere for the IFE and lifejackets should be solveable, but the big advantage could be in boarding and disembarking time reduction possibilities.

      • you have made that assertion previously (overwing won’t work with big engines) before, I didn’t buy it then and I don’t buy it now.

        yes, the engine pylons would be loaded in compression vs tension, but there is no reason to believe they would be engineered as reverse underwing pylons (single narrow spar projecting from the wing). more likely the engine intakes and mounting structures would be more closely integrated into the wing structurally and aerodynamically.

        • Cant cantilever an large fan over-wing engine forward of the leading edge to help with the thin wing design.Sure they are many other disadvantages and likely few advantages

          These sort of out there designs for small executive jets and feeder liners are great, but the market and other concerns says otherwise.
          HFB320 Hansajet with forward swept wings which puts the spar through the cabin but behind the passengers.
          VFW614 and Hondajet – overwing engines
          Piaggio Avanti – 3 lifting surfaces, rear wing mounted t/ps
          This shows the concepts do work well , but..

          • bilbo: I am not an aeronautical engineer but I am a mechanic , technical .

            I do know things don’t scale up well and I believe that is fully true of engine mounts.

            Vast majority of the business jets (all?) are tail mounted.

            Small jets only with the engine above it.

            Bjorn could give us a good detailed explanation

            The weight bearing as well as the dynamics on over the top of the wing have got to be wild and unworkable on large aircraft.

        • TransWorld, I too am an engineer, Civil and Software.

          most BJs are tail mounted/T-Tails because they want very short landing gear so they don’t need ground services to board and load baggage.

          at the same time the 727 was a rear-mount T-Tail so there is nothing inherently unscalable about that architecture, just wing mount engines and low tails are more structurally efficient, but you trade heavier landing gear.

          Honda saw an opportunity to maintain the short landing gear with the structural weight advantages of wing mounted engines. they also saw aerodynamic gains from this approach.

          there is no reason to believe that Boeing (or Airbus) with their cutting edge composites knowledge couldn’t engineer a sufficiently strong overwing pylon that, when combined with the weight savings from shorter and lighter landing gear resulted in an overall lighter aircraft.

          • The Hondajet engines are effectively rear engines anyway as they are exactly the same place they would be if they were on the rear fuselage. Plus they are canted inward off their support strut towards the fuselage. A complicated way to have rear mounted engines !!. Seems just a gimmick

            To me the real innovation comes from the integral molded composite fuselage
            http://world.honda.com/HondaJet/innovation/03/

          • You might see over the wing UDF Engines right after the wing trailing edges. Having Engines in front of the wing did help wing flutter margin, having them attached to the aft wing beam and up and aft might worsen it. Still todays sensors, computers and fast actuators should be able to surpress wing flutter aerodynamically allowing for Heavy UDF Engines at this location.
            Mounting heavy engines aft gives c.g. problems.
            One possibility are regular Ultra high bypass Engines under the wings and a smaller UDF type of combined Engine/APU in the tail re-energizing the body bounday layer and give enough thrust for taxiing.

          • Wire and/or thin strut stabilization would cut the pylon weight and increase it’s strength .

    • I’m not feeling his lack of enthusiasm. Boeing have a lock on this configuration and they should exploit it. A replacement for the 777? I can see it.

      More like, I want to see it. The tube and wings business is getting tedious. At least they should at least get into a competition with Lockheed (with their splendid HWB) for military airlifters or a long endurance, manned surveillance and C2 platform. Or even a tanker..jeez, so many possibilities……

      • Lockheed HWB ? Thats right a 4% scale wind tunnel model. LOL.

    • Yes, “McBoeing” is such an apt name for Boeing nowadays!

      Couldn’t agree more, as noted a few months ago in other reader comments/threads posted in previous LNC discussions re McBoeing…er post-Seattle HQ era of Boeing, which since leaving Seattle “thinks” and acts more like the flailing/failing company it took over as the last century was drawing to a close, McDonnell Douglas…

      …than the gutsy and innovative company whose 707s, 727s, 747s and 787s REVOLUTIONIZED air travel, each in their own way, and each spectacular successes in terms of technology AND $ales!!!

      And Seattle HQ Boeing’s 737s, 757s, 767s & 777s are nothing to sneeze at, too!

      For while the aforementioned models (707s, 727s, 747s, 787s) were transformational in ways that revolutionized air travel that allowed those models to enter the cultural zeitgeist far beyond the aerospace and avgeek universes in ways the 2nd group (737s, 757s, 767s, 777s) never have (hit songs, movies, countless advertising campaigns…which btw let’s not forget even just weeks ago it was a 747-8 that Lufthansa used to show off its newest branding/colors…NOT you-know-who’s…just sayin’ 😉)…

      …the fact still remains that 737s have soldiered on for 50 years already, and will probably be among the very few aircraft to ever sell as well or fly as long…maybe even 100 years (as much incredible as it might seem horrifying for anyone stuck in a teeny tiny, no legroom seat, IFE-less cabin for more than 2, much less 7-8 hours! 😱)…

      …767s were the twin-engine models that were deployed over the trans-Atlantic that ultimately allowed for ETOPS/big twins that are commonplace even today for that model, and BOTH OEMs have since standardized on models on such as Boeing’s ubiquitous 777s that slayed Airbus’s quad jet A340, but alas, also killing its own masterpiece, the 747…

      …and speaking of those 777s, horrible though they may be for economy pax stuffed into teeny tiny seats, in no legroom rows, aboard planes with nearly half the lavs as a 747 for as many (or even more) pax than the majestic Queen, with aisles in economy so narrow one has to walk at an angle pivoted sideways for 5-15 hours, they’re still engineering miracles – especially the pair of huge GE 100k+ lbs thrust engines…

      Whereas McDonnell Douglas’ last big successful commercial airplanes were…the DC-8…DC-9…DC-3…and all decades before how many Boeing models that Boeing launched AFTER those three MCD planes?

      Yeah, that’s among the glories of pre-Chicago era, visionary Boeing…

      …versus the post-Seattle era of…McBoeing!

      How or why the culture of a FAILED COMPANY subverted and subsumed the far more successful company, and indeed the one whose impressive a track record for success after success (with perhaps the 787 launch debacle being an exception in terms of program management and cost overruns, but certainly NOT the full on embrace of revolutionary materials and technologies) like Boeing’s was before it absorbed/saved McDonnell Douglas, remains a mystery to me?

      Perhaps someday the brilliant minds at Harvard Business School will answer this question in a case study…but just seems so strange as to how the mighty company, Boeing, surrendered its mojo to the meek one it long ago vanquished, McDonnell Douglas, to become aptly described with well earned derision, as “McBoeing”…

      • PS: forgot to also note the extraordinary feat by OG, “Moonshots ‘R Us…and NOBODY Does ‘Em Better Than Us”, Boeing, and its nearly simultaneous ‘dual launch’ of both the single aisle 757 (that many an airline dreamt “if only there was a forthcoming ‘neo’ option…”)…

        …AND the innovative OG MoM twin aisle/twin engine star itself, the 767…which as noted above, helped usher in the era of twin engine intercontinental (ETOPS) flights that now pretty much has relegated quad jets to the past, except, perhaps for a few isolated QANTAS sectors that ultimately, too, will become the domain of the big twin ultra long haul aircaft it is now seeking from A & B…plus, of course, the niche A380s outside of Emirates!!!

        …at two separate FALs, miles…no, make that entirely different cities apart on opposite sides of Seattle itself…

        How could I possibly overlook that as among the many stellar accomplishments that McDonnell Douglas hasn’t come close to achieving itself for commercial aircraft since perhaps the DC-3…

        …that Boeing did so well, that it practically was taken for granted!

        Or worse, now seems to be viewed with disdain in the post-Seattle “McBoeing” era…

        • Boeings not failing, nor did it ‘leave Seattle’. The Commercial airplane division is still there. What is in Chicago is the HQ, with around 700 staff, of many divisions including commercial.

          gee the alternative facts/fake news people seem thick on the ground today

          • We might expect Boeing HQ to move inside the Washington Beltway to be closer to the Goverment Power and Money and get a better unstanding when Projects for the armed forces cost a bit more and take a tad longer time than promised. Just look at LM that managed to survive the F-35’s thanks to its well staffed and funded HQ within the Beltway and next to the Congressional Country Club.

  5. I think the line about McDonnell Douglas should be revised.

    The Original Design was by McDonnell Douglas and has been refined by Boeing which was take over by MD in 1997.

  6. He seems to be self setting the situation up to preclude.

    He talks about small aircraft, but its possible this is a larger aircraft idea.

    I would like to see the seating arrangement, wing width, engines for a A350/777 sized aircraft.

    There has been some discussions that the rotation out into the wing if you put passengers there would not be well taken.

    I would be happy to fly out there! Call it your low cost seating, premium costs for those at the center.

    It may very well not work (I don’t buy the shrink, those don’t work, 787 stared with the -8 did not shrink to it)

    I can see the lengthening issue. Given enough advantage that might be able to be overcome.

    Again more details.

    • It pretty much ruled out ‘lengthening’ all together, no ‘details’ required its self explanatory.
      Let it go, it cant be done.

      • I know what he said.

        Engineers come up with concepts all the time that work around and mitigate or eliminate the issues.

        I don’t say it can be done, just thinking it should not be ruled out either. Most times no but sometimes a different take changes things dramatically.

        Hopefully its not taken ad tooting my horn, but we had some air boxes that failed the actuating mechanism frequently. 25 years we have been fixing them.

        I came up with a replacement concept that cut the cost by 80%. The fabricaros felt it needed a bit of modification to the idea. We implemented their contribution and still kept the basic idea and its worked gang busters.

  7. Of course he’s fully right and of course people won’t listen, because in the end we’re all a bunch of BWB Fan boys ;-).

  8. The head of the US Air Force Air Mobility command seems to be more impressed with the blended wing body concept than many of the people who have posted in this thread, or Boeing’s Mr. Stinnett as quoted by Mr. Hamilton in his post. See the excerpt below from the September 2016 Flight Global article at the link below. Will Boeing be declining to bid for USAF KC-Z contracts. or do they just have some other design in mind for the KC-Z? Perhaps Mr. Stinnett was not including stealth tankers in his “freighter and transport” category, or understandably, not considering “by 2035” as being “anytime soon”? I seem to remember that the Boeing 707/727/737 family had its origins in Boeing seeing a need for a tanker whose speed and altitude capabilities would be compatible with those of jet B47 and B52 bombers, which were having to descend from their normal cruising altitudes to be refueled near stall speed by propeller tankers that were much like contemporary airlines, with no jet engines or thin swept wings. The practical and sensible people at Douglas and Lockheed knew that transports with jet engines and wings swept as sharply as those of a jet bomber were impractical ideas, and kept on with refining DC-6’s into DC-7’s and Constellations into Super Constellations. Some even dreamed of installing turboprop engines on future upgrades of practical and proven propeller airliners with thick non-swept wings.

    “The air force will begin a study this year examining what the KC-Z tanker would look like and will start seeking investment opportunities a year after the study is completed. The USAF is considering whether the new tanker should include standoff, stealth or penetrating capabilities for an anti-access area denial environment. As the F-35 moves into denied environments, a low observable tanker should follow the fighter, Everhart says.

    “We’re going to need a platform that we’ve never seen before,” he says. “The blended or hybrid wing, it’s a lifting body and it has a capability of being low observable.”

    https://www.flightglobal.com/news/articles/usaf-commander-wants-technological-leap-to-kc-z-ta-429534/

  9. For carry on bag…. I would have imagined that some design like lockers for bag in ferries could also work? So that passengers put their carry on bag in a rack to the side of the cabin instead of occupying the height. Given Boeing have also designed ferries like Boeing 929 I think they can redeploy some of those experiences here.

    • You probably stole Scotts thunder of that one , as hes quoted in the article. Could be a new post in a few days ?
      Its possible Boeing has a yearly budget of around $100 mill to make changes to the whole 787 program to improve production efficency, aerodynamic changes, even costs to push the monthly rate up. Ive heard Airbus does much the same for A330 series

  10. Lightweight , ducted , contra. propfans mounted T-tail could give acceptable weight and noise parameters .
    P.M.

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