From Tube And Wing To Just Wing: The Future Of Airliners

Airliners have become an unremarkable part of modern life, but unless you happen to be an aircraft enthusiast, you’d be forgiven for thinking the latest Airbus model looks more or less the same as the Boeing 707 that ushered in the Jet Age. But that might soon change, with blended wing airliners looking like the next step in air travel efficiency. In the video after the break, [Real Engineering] takes us on a fascinating tour of the past and possible future of jet airliners.

Contemporary airliners all still follow the same old “tube and wing” design, but have become vastly more efficient. The latest jetliners burn almost 50% less fuel per passenger-km than they did 50 years ago. This is thanks to better engines, improved aerodynamics, reduced weight, and a vast array of other, often invisible changes. However, it’s looking like a more drastic change is needed to keep the progress going, and NASA, Boeing, and Airbus are all betting on blended wing designs to do this.

Blended wing aircraft are basically flying wings, where the cargo-carrying section of aircraft is shorter, wider, and produces lift. This layout can be used to increase the aircraft’s internal volume, and improve aerodynamic losses, by eliminating the tail. Research shows that blended wing design could reduce fuel consumption by as much as 27%. Since load and produced lift are spread more evenly along the entire width of the aircraft, it also reduces the amount of structural reinforcement required for the wings, especially at the root. The large internal volumes also allow other power sources, like hydrogen fuel cells to be used.

Blended wing aircraft are not without challenges. They are inherently unstable and require complex control systems to fly. These control systems depend on sensors, actuators, and software to work properly, and require multiple levels of redundancy. The omission of these redundancies ultimately led to the 2008 crash of a B-2 bomber, and the more recent fatal crashes of Boeing’s 737 MAX airliners. Also, unlike tubular fuselages, blended wing designs are not ideal pressure vessels. However, this is not a major problem thanks to the availability of carbon composite materials to create strong, lightweight structures.

With aircraft technology moving as fast as ever, we look forward to seeing what the future will bring. Whether it’s personal rotorcraft or commercial space flight, it sure won’t be boring.

77 thoughts on “From Tube And Wing To Just Wing: The Future Of Airliners

      1. Shaun McGreavy: Unless you believe in the wrong fairy tales and then you would be too dead to fly. Thanks, but I don’t need some leather clad Nazi screaming for my papers at the check in counter or threatening to drag me off to prison because his uniform is chafing as he goose steps his way to work.

      2. Easy to say, very hard to prove. Yes Nazi Germany did have some very good military hardware, and some advanced technologies for the day in use, but they were not the only ones – in many areas there were behind the allies, and even their better techs were often too complex to be practical – maintenance hogs and far too slow to produce. To the extent that they are basically useless in the real world despite some impressive features. You want one Tiger/Maus/Panther with enough spares, fuel and supplies to go for a few weeks, or 20 odd Shermans/Churchills and all the ammo and support vehicles you might need for that same few weeks? Same thing in aircraft the prototype jet they had at the very end of the war was better than anything the allies had in service, but it takes more than one jet to win a war, and its not the only jet engine powered prototype in the world either…

        I also don’t think it really matters which side wins a war, technology around combat evolves much more rapidly when there is investment in it, and that happens when there are fights going on that need it. You don’t bother developing and building tanks or even just a cartridge based, auto-loading rifle for your troops when they have good muzzle loader rifles and muskets and the indigenous tribes you are fighting with have probably not even got metal foundry technologies mastered. But when fighting somebody with similar advantages to you, maybe even a better starting postion, the arms race kicks in and more rapid progress is made.

        So I highly doubt aircraft would be much different, almost certainly worse if the Nazi had won – as to win they have to beat Russia, the British and their many friends, and at least cripple the American war machine, which was never going to happen – Just the British Empire vs Nazi Europe without direct militatry aid for either side would just have been a long drawn our pyrrhic victory if either side could actually win – and I’d still be betting on the British there – a globe spanning empire that mostly is very willing, vs a patch of Europe with most of the workers unwilling or already dead, smoke out of some death camp the Nazi loved so much… And picking a fight with the Russians while Britain was still in the fight basically sealed their doom, even if the Americans never come into the war the vast hordes of the Russians, and the fact the British empire would start seriously tooling up to produce weapon of war in Aus – well out of the Nazi’s range they could never have held against the many partisan groups in all their acquired nations, and the eventually vastly better supplied British Empire troops. Please note I am not at all downplaying the American involvement, when they finally come into the war proper it is a major change in trajectory, and even before that with the supply convoy the contribution was most useful.

        So assuming magic happens and The Nazi did somehow win there would be no cold war, so no need for all that investment in ‘fighting’ that war, and with how battered and drawn out WW II would have been technical improvements at the end of it may be far in advance of 1950’s tech, but would never make it to production, and then be dropped because there is no need to spend so much when you effectively own the world.

        1. I saw my first image of a flying wing airliner in 1952 in a Nash car advertisement in a magazine. It us now 2021 and I am still waiting. Douglas Aircraft Company was doing a lot of advanced research work on a blended wing airliner when Boeing took over. What happened to all that work. Boeing could have taken over the lead in airliner sales in all aircraft markets if they had pursued they development of all that research work already done. My bet now us that Airbus will beat them to the punch.

    1. With how sedate an airliner is supposed to be while manoeuvring around motion sickness really shouldn’t be a thing – so little feeling of motion, and the vast horizontal internal space giving you a horizon of sorts. I’d be surprised if motion sickness really did cause much issue – there are always going to be some, but are they any better off in a current airliner anyway?

    2. Which is why people fly around in tubes, the closer to the centreline the less motion you feel when the plane turns, which means people in these blended wing planers will have to sit in the center and cargo and fuel will be in the wings. (And the cheap seat will be in between with no food service and extra barf bags.)

    1. I think they mention the 707 because the Comet and the 104 (and the Avro 102 FWIW) still had the engines in the wing, instead of being pilon mounted, thus looking quite different.

      The french caravelle had a more modern configuration (engines pilon mounted near the tail ) but the looks still were “not quite the standard one”.

    2. True, but both of those early airliners had terrible safety records.

      The 707 can be traced back to the Boeing 367-80 (flew in 1954).

      It lead first to the KC-135, then to the 707 (the C-135 series fuselage was a bit narrower, it was widened for the 707 to complete with the Douglas DC-8’s 3 x 3 seating arrangement)

      Of course, the Comet flew in 1949, so it still have a good head start. It’s final form was the Nimrod for the RAF when was retired in 2011. Ironically, the RAF replaced them with Boeing E-3’s , which was derived from the 707

  1. I don’t think fliying wings will be that popular in the future, because the inherent instability makes impossible to recover just by human intervention (ie: if sensors provide wrong info, humans are powerless to do anything). The current sensor rate of failure means we cannot afford to fly wings without making them much more expensive.

    1. I believe he goes over this. Computer systems are more a matter of unstupid design than of material expense. Processors and sensors are relatively cheap compared to jet engines and frames; you just need to make sure your system isn’t relying on one ONE sensor (a-la Boeng 737 MAX). Just plaster it with multiple redundant (and cheap) sensors and computers of different types. With modern fly-by-wire planes, you’re also screwed if the computer goes out – nonetheless they’ve generally done well and this isn’t much worse.

    2. The usage of a bwd will hinge on airports being able to service and turn then around in a timely manner. Right now loading and unloading would take prohibitively long.

        1. Well said. It looks to me as though they should settle on a delta wing design. Oh!… hang on!… wasn’t there a ‘plane like that?.. errr… Concord, or something?
          Alright then.. a more blended version of concord…or something…..

  2. When I look at it I see 4 tails.. (7 if you count the engines)

    It still feels more experimental then the Auora D8:

    According the the video the biggest challenge with the Auora D8 is stress on the blades..

    But it seem that another company, Jetoptera may already have solved that issue, by going “bladeless”:

    I wonder if it is possible to use “the angle of attack” of the fan to self-balance the plane, like with a tail.

  3. There is a reason that subways have windows even while travelling inside dark tunnels. And a plane with no external windows will have the exact same effect on passengers. Maybe the brain can be fooled by a TV screen showing images from outside.

    The London underground started without windows (why waste money and materials on windows that can only ever see walls), but quickly added them because they help a lot with motion sickness. Movement is detected by the inner ear, but your eyes tell you (without windows) that you are stationary. Conflicting information causes mental stress and nausea.

    1. I wonder if they could replicate the motion closely enough with a 2 dimensional array of leds on the inside of the walls that had a chaser pattern to mimic the direction and acceleration of the plane. I would think in theory you could disable them when at a constant velocity.

    2. Trains spend a great deal of time accelerating, decelerating and taking pretty sharp corners (especially the narrow underground), so lots of instances of what you see and feel does not match if there are no windows.
      An Aircraft need do none of those much at all, so in flight itself I don’t think windows would really matter, there isn’t enough acceleration to be picked up by the ear most of the time, you are just sat in a noisy room, and on the take-off or landing its a single moment of discomfort (assuming you suffer motion sickness) and you know it is coming.

  4. All the folks talking about motion sickness because there won’t be any windows need to consider that most passengers in airplanes can’t see out a window anyway.

    In current passenger planres, if you aren’t sitting right at the window then you can’t see out. In modern (large) planes, most passengers sit in seats with no window.

    I don’t hear about major puke problems in modern large planes. I don’t expect there will be large problems with puke in flying wing passenger planes.

    1. The counter point to that is if you aren’t sitting next to a window, you’re right in the center of the plane. Less relative motion whenever the plane banks. That would reduce motion sickness.

    2. It’s because every plane (commercial) have you open All windows on take offs and landings, check that out next time you fly. I never get motion sickness when flying, but when i got on a train in the cabin I got sick. Only when i got to the breakfast cab which was all windows did i feel better. Never would have figured that out. On a wing plane there would be no windows. Need a lot of barf bags.

    3. People who seat away from window at least know the window is there and at times look at it to see what is happening. It’s a mind game and all the plane companies follow that custom, they all can’t be wrong.

  5. “Blended wing aircraft are inherently unstable” er, no. You can deliberately design one to be unstable, or to have relaxed static stability sure, but there’s nothing inherent about it.similarly you can make your tube and wing unstable and save some trim drag if you want.

    “They require complex control systems” absolutely, relaxed static stability requires state of the art 1970s technology.

    The real problem with these designs is conceptual these are A380 capacity concepts for an industry that doesn’t want A380 sized aircraft.

    1. It’s true that flying wings can be made stable. It was done in WW2 and it’s well known how to make them stable. By incorporating reflex on the trailing edge you can introduce stability which is really incorporating the required negative lifting tail into the wing itself. But getting stability is not necessarily the trade off for efficient fuel saving designs.
      What this article neglects is the aerodynamic losses due to frontal area. Blended bodies are thicker in general and thus have to push more air out of the way across the width of the aircraft while current designs using a tube reduce this issue.
      Another way of improving efficiency is to fly slower. Do we need to go need to go 600 mph? Would 500 or 400 be ok? If you sacrificed some speed, designs change a lot. Long high aspect ratio wings (think U2 spy plane, global flyer-round the world unfueled record plane, and gliders in general) point to designs that travel very efficiently with glide ratios of up to 50 to 1 which means 50 feet forward for 1 foot of drop. They don’t travel quite as fast but are vastly more efficient than current commercial airliner designs. There are a a range of design choices that are demonstrably more efficient than today’s designs but require new trade offs to be made.

      1. Indeed, everything is trade-offs. Flying wings make alot of sense to me as a passenger aircraft – IF we assume air travel will continue as it has done through most of the last 20 years, ever more passengers and cargo – as in terms of internal volume and liftable mass to drag and footprint they do very very well. Should also be able to fly at relatively lower speeds, so increased mass etc doesn’t force longer runways.

        I don’t think a U2 style plane ever makes sense for mass transit – as you scale up the body to fit everything you want the wings end up beyond feasible in length and material strengths. So they probably wouldn’t be nearly as efficient as current commercial airliners, which are riding that compromise of maximum space to minimum fuel cost within the limitations of runways, material strengths etc – the whole point of the jumbo jet design is to take lots a long way, and the only thing following that same criteria that has any hope of being better is flying wing designs. A U2 style plane would be more like Concorde, rather impressive in its way but not fitting the needs of air travel as we know it today well at all. Might be a good private jet concept, but that is about it IMO.

        1. Speaking of fuel cost, (Consumption) pertaining to global warming, how much fuel does each trip use? Is there a hourly consumption rate for these planes? Seems like what the autos burn is a lot less than what the daily flights thru out the world burns. If you look at the tragic map of sky lanes, you can’t fit any more planes up there. I know we can’t stop the flights and a big contribution to green house gases. Is that a trade off of what is required to stop global warming?

          1. If Air travel is an evil that really need stomping for global warming is a very complex question, and comparing to ground vehicles fairly isn’t easy either – airliners carry huge numbers over vast distances – often over terrain a car couldn’t travel anyway. So comparison to ships is perhaps fairer, or perhaps trains – again both mass transit. Where cars are usually only moving one person and the total miles covered by all of them globally is an even vaster distance than aircraft cover – ground vehicles are used and often even owned (so used frequently) by the poorer folk globally – flights while vast in quantity are almost all taken by the wealthy, on the global scale at least.

            Excess air travel when there isn’t any real need is obvious lowhanging fruit, so flying less often, or even never if you can is a good thing. But the same is true for using your Car, if you don’t use it when you could walk or take mass transit…

            But there are plenty of things that work better through having Air transport. Obvious ones being perishable food transport – yes locally grown is always going to be better on a ‘green’ front, but you can’t always grow the right amount locally, everywhere, every time (and its better to ship it than waste it all), and some things that are essentials for some folks diets (mostly vegans) just plain won’t grow in large areas of the world.

            There is also that very human touch – in person meetings, being able to study something for yourself, seeing other cultures up close and personal. All things that can’t just be replaced by fancy communication technologies – augmented, with the need for travel reduced, but not replaced.

            Then there is boring old cargo that could take other methods – but the only other method for most would be by boat, those are slow, often have to take far less direct routes and are far from paragons of green – though carrying capacity to fuel used per mile should be better on a boat. But there will be on a purely carbon footprint standpoint a cross over where air freight is better, and being more convenient and fast enough to fill voids in the common “Just in Time” parts supply method and to respond to a changing world – no good sending firefighters to help your neighbour on fire if they won’t get there till the whole place is burnt or the weather has changed anyway (to take a current example with Greece getting UK firefighters coming to their aid).

  6. The argument that saving fuel will reduce total carbon emissions is patently bollocks.
    If you look at the graphs, as fuel savings have been made over the years, and the relative cost of air travel goes down, the public use air travel more, and the total emissions actually increase.

    What is needed are steep taxes on air travel, probably in the form of tax on fossil fuels, worldwide.
    This will keep demand relatively low. If a departing-from country won’t tax the fuel, then the arriving-at country can do so, by international agreement.

    The taxes can then subsidise carbon-free generation of H2 from renewable energy.

    1. I think just mandating a percentage of the price of a ticket be used for subsidies instead of adding a costly bureaucratic layer where taxes can be siphoned off to pay for other projects.

  7. Anyone ever consider that you can’t park this thing at a jetway in any major airport? The geometry won’t allow that. You would be resigned to hardstanding the aircraft, using air stairs and then bussing the passengers to the terminal. Either that, or spend billions of dollars on airport improvements for wide parking spaces for these aircraft, which would be extremely inefficient.
    Also, as a pilot, I would hate to try landing this thing in a 20 knot crosswind. Guaranteed wingtip strike. I’ll stick to my “tube and wing” aircraft, thank you.

    1. This is addressed in the linked video. These planes are inherently smaller for the same passenger count. So if the number of seats is kept constant, the planes will actually be smaller.

  8. People have been claiming the flying wing is the future of all aircraft for 50 years, why have the only examples so far been eclectic military aircraft that are near uncontrollable and must be flown with augmentation? Just another click bait pipe dream.

  9. The big issue here seems to be skipped over. The tube and wing design is due to the pressurized cabin. Pressuring a non cylindrical shell is quite difficult, flat panels create huge stress points. This was tried with odd shaped fuel tanks in the X-33 program. Inspection for cracks on a pressurized vessel would also be difficult in the wing shape. There would be many difficult technical hurdles, we have done it with the b2 bomber, the odd shape may not be cost effective yet.

    Its a little scary thinking that boeing cant get the 737 conventional design right, let alone something that will require full computer control to not let the human put it into a uncontrollable situation.. maybe airbus can have a go at this…

    1. What about use an oxygen concentrator so that it wouldn’t have to be pressurized or at least not as much? Is that just a cost issue or is it a issue of power usage or weight undoing the savings from a lower cabin pressure?

  10. I have 2 main issues with the “manta ray” shape aside from what’s already been mentioned (nausea, stability, etc.). 1) getting people and goods on/off at a reasonable pace either at the airport, or worse, after a crash. it’s be like rolling in a tank. you can only go up or down. 2) expansion of the airframe. 737-Max and A380 not withstanding, the Boeing and Airbus airframes have had such longevity because they were easy to expand (make the tube longer) without destroying the basic design. One of the reasons the 747 has done so well vs the A380 flaming out in mere decades is the versatility of its design. Doing the same for a flying wing seems like it wouldn’t be nearly as versatile.

    1. The emergency egress issue is quite significant in a blended wing aircraft. With limited locations for exits, due to the shape, it would be like trying to evacuate a theater through just the lobby in 90 seconds.
      And then there is the pressurization issue. This issue is not just structural it is a failure mode issue. An explosive decompression would disrupt the airflow and could likely make the aircraft totally uncontrollable.

      1. I doubt an explosive decompression would matter to control of the aircraft long enough to notice, assuming it doesn’t compromise the structure enough the whole thing starts to break up. A fast enough leak to meaningfully disrupt the airflow would be over quickly enough the aircraft’s inertia is likely sufficiently large you wouldn’t even notice. I might be wrong there, but when you are talking tossing a relatively tiny amount of air out (as there isn’t that big a pressure difference, nor huge volume at that pressure, there is just not that much air to loose) vs a stupendously heavy aircraft…

        I also can’t see how exits are at all a problem – hatch with ladder to let folks up onto the wing top when appropriate, hatch with those inflatable slides to let folks down through the wing bottom… Its a different problem logistically to the tube model, but need not be any more problematic – if anything I’d suggest its easier – so much external surface area in sensible places to put hatches within the passengers cabin, so probably more egress points.

        Now actually making such an aircraft affordably, and meeting all the practical considerations for civilian use is definitely a challenge, it is such a new design for the civilian world. But there is no reason I can see it can’t be done when flying wings have been in use for decades in various forms and scales so there is a great body of knowledge to draw on.

    2. Nothing to stop such a blended wing design from being stretched, scaled up, or even turning into a hybrid tube and delta wing if needed for reason – the core design doesn’t change, or at least change any more than the normal jet profile when being buggered with.

      But I think that is actually the wrong way to look at it – the standard jumbo jet shape requires lots of expansion and new bulges for the various new uses because the useable internal space is actually quite constricting – to fit out a big wing with its very large single volume for other tasks is probably just fitting a different interior option into that rather large space.

      The expansion of the airframe really shouldn’t come into the picture any more than it does on normal jumbo – it is not an SR71 trying to go faster than the sound barrier by several times and so getting cooked… Definitely a design factor that must be considered, but not one that should be a major barrier to its creation – the big one for that is definitely the pressure vessel element – every extra bit of mass needed to make the bottle strong enough in its potentially (nothing to stop the pressurised passenger section being a tube on the inside with the extra space in the wings being the cargo) odd shape counts.

      The logistics of loading and unloading people and goods at the airport I doubt changes enough to notice – how many doors off and on an aircraft are usually in use for the passengers with all the security and boarding pass type stuff? Surely that is much more about managing the lemmings, keeping the traffic flowing properly than the aircraft geometry – though obviously it will play some part in how you managed that traffic.

  11. So.. where are the windows?!? Or are we to gather that there will be no more window seats? Maybe… overhead windows on some future models? Or maybe… glass floors? Looks neat and all, but… seems a bit claustrophobic to me.

  12. ‘In order to be old and wise you must first be young and stupid’. The Comet ushered in the jet age, followed by the Caravelle. The Comet had engines in the wing, rather like the blended design, which has been on the drawing board for 50 years. The 707 came 11 years after the Comet. Stupid article.

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