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Comment by alexpotato | Hacker News Reader

Interesting historical note on the blended wing design:

One of the main arguments against it was that designers weren't sure if people would be ok with sitting towards the center of the plane. The thought was that passengers wouldn't be comfortable without being able to at least see outside (even a little, looking at you 3/4/3 widebody planes).

I mention this b/c there is a quote in Mary Roach's Flying to Mars. She mentions concerns around how astronauts will be able to psychologically handle the remoteness of space. As a similar example. they talk about how in Victorian England people were concerned that trains would be traveling so quickly that it would induce a state of shock in the passengers. This turned out to not be the case at all.

In fact, she quotes a cosmonaut who says "Only people think this is problem is psychologists".

View on HN

A bigger problem with blended wing designs is actually for the people on the peripheral. When the plane banks, passengers further from the axis of rotation will feel a more significant change in their altitude. You literally feel like you're "falling", as the plane banks to your side.

This also applies to existing aircraft, but the amount you drop/rise is limited by the your distance from the axis of rotation, which is normally not very far. In blended wing designs, the distance could be considerably greater, making this sensation much more intense.

The workaround for this would be to simply use shallower bank angles, but I suspect that would require some pretty major changes to navigation rules, as it would drastically increase the turn radius.

The issue isn't the bank angle exactly, it is the acceleration of the roll. Pilots will need to be careful not to throw people or drinks around, but I think it would be doable.

depends on the flight paths for different airports. some require tighter turns.

Pilots can control the bank acceleration, sure. They have much less control over acceleration due to uneven turbulence.

I'm not sure this tracks, I think turbulence powerful enough to cause passenger discomfort is usually so big that it affects the whole plane pretty uniformly. I think it's exceedingly unlikely that you'll spend enough time on a shear line to induce a large roll.

At least it's never happened to me, but I am only a passenger.

In a typical plane in turbulence, you can see the wings bending up and down. Perhaps a blended wing would be stiffer, though.

Yes a blended wing would be stiffer, but wing stiffness isn't really relevant here. The wing bending isn't evidence of differential pressure between the two wings, it's only showing that the wings are the part of the plane that's most affected by turbulence while not accounting for the majority of the inertia.

The point is that air currents powerful enough to appreciably affect a large plane are large scale and therefore you're unlikely to have enough differential pressure from one wing to the other to impart much torque.

I'm not certain about this and I'd love to be corrected if I'm wrong.

Ah, so in other words the whole plane bumps up and down but doesn't rotate. Therefore the location of passengers doesn't matter much, as all locations experience the same acceleration. (Provided the cabin is stiff)

When I was younger, watching the wings flex up and down in turbulence was one of my favorite things about flying, like an amusement park ride. Over the years my perspective has changed.

I've been in turbulence with high roll rates and even as a pilot unbothered by moderate chop, it will cause me to sweat. I've been in the last rows of a 777 and watched the fuselage flex in chop. A blended body would be pretty rigid and have a very low wing loading because it's basically all a wing. So it would be pretty uniform.

It would work if all turns were managed via controls to be a 1/4g, otherwise riding the outside would be like a roller coaster.

I'd prefer to go back to the MD-80. Very high wing loading, fast and never broke down. Skated through turbulence.

The DC-9 and MD-[89]X were great airplanes. One of the great tragedies of unchecked American corporate consolidation/acquisition is that Boeing was allowed to borg McDonnell-Douglas. (Although some climed the opposite was closer to the truth...)

Anyway, the resulting company is too large to fail, and thus, too large to exist. We're at a point where we could really use the competition we had in aerospace companies back in the 80s, when there were enough competitors in both military and commercial aviation for competitive pressures to keep the players working to provide innovation and value. (Rather than milking the market with intentionally poor designs a la Boeing's 737MAX.) Modern airlines have only two vendors to choose from now that Boeing and Airbus have gobbled up even their second-tier competitors.

Personally, I'd love to see what the old Convair, LTV, pre-Martin Lockheed, or pre-McDonnell Douglas might come up with in this competition...

The problem is that, what airlines want, and what regulators want, is now too expensive to independently develop and start a new competitor for, even if you are well resourced like China, Japan or Russia (which all have attempted and failed to break into international aviation sales).

A new aircraft development is a $15B+ R&D investment, for the price and fuel efficiency and safety required. McDonnell-Douglass and more recently Bombardier messed up their bets and it cost them their independent existence.

can't speak to aeronautics of it, but from a pax perspective, the md80 was a fantastic jet. probably the last vestige of what flying "used to be like" since they were too old to retrofit for "efficiency". also its planform looked AMAZING; retro-futuristic even

closest modern aircraft to it is the 717/MD90, which Delta is still flying, but not for much longer iirc

md88 was shit as pax if you didn’t like cold and loud.

Good to know, I'm aware that high roll-rate turbulence is possible but presumably quite rare?

rareish but once was enough. After 5 minutes, people start puking and then it just gets worse.

Not a pilot, but I've flown in the MD-80 once, and I've found it much more unpleasant than most planes due to the engine noise in the cabin.

But on the other hand, I've never experienced turbulence that's made me more than barely uncomfortable in any plane.

Secret was to not sit in the back

True, but absolute bank angle would also matter (say endpoint of roll when roll acceleration is zero) because now there's a component of gravity pulling you sideways.

Not if the pilot did it right. The net force on you should always be directly toward the floor.

Even when the plane is tipped over at 15* (or whatever their max bank angle happens to be)? The floor is no longer directly underneath you.

The plane turns while banking which results in a force vector mostly straight down towards the floor. If the plane did not turn while banking what you wrote is true.

The ground is whatever you accelerate towards.

Balanced out by the centripetal force of the plane turning!

Underneath is a relative term.

It is called a coordinated turn and it is what one normally aspires to fly.

https://www.boldmethod.com/learn-to-fly/aerodynamics/the-aer...

A coordinated turn with 60 degrees bank should be achievable by any airworthy airplane (it requires pulling 2g), and the maximum bank angle for a steady-state coordinated turn depends on how many g you can pull before you run out of control authority, cause an accelerated stall, or reach the airframe's structural limit.

Next time you fly, get a beverage of your choice and observe how it behaves. Here's an example, courtesy of the great test pilot Bob Hoover:

https://www.youtube.com/watch?v=V9pvG_ZSnCc

If the turn is coordinated you can't tell the difference. I've been in small GA planes turning at 35-40 degrees and it doesn't feel like you're sliding at all, you're pulled back into your seat and "down" (relative to you) into the flooring.

When roll acceleration is zero, the remaining acceleration (i.e., due to gravity) felt by a passenger on the wing edge will be the same as a passenger in the middle of the plane.

I wonder if this could be solved by a rotating inner cabin that always maintain perpendicular to force of gravity when the plane banks?

I think that would be tough. Out in relatively empty airspace, sure, the pilot can make pretty slow turns. But major airports with multiple runways, other airports in the vicinity, military bases, etc, all put hard requirements on the flight corridor. Sometimes the pilot has no choice but to make pretty sharp turns, and that means a pretty fast roll acceleration.

How about... more rudder? Of course, more control surface area means more drag and less fuel efficiency. Wonder if a flying wing style craft that has enough rudder to match traditional cylinder fuselages bank-and-yank capabilities is still more efficient.

Lateral acceleration is less pleasant for passengers. You don’t want peoples drinks to fall off their tray tables for example.

That said there is a fair about of wiggle room so I doubt it’s a significant issue in practice.

Maybe they could try inventing a way of keeping drinks from spilling when the container is tipped over...

I even have a cool name word to describe it: "lid"!

μg coffee cup https://science.nasa.gov/science-news/science-at-nasa/2013/1...

Lid or no lid, it’s still a problem if your drink falls off the tray table. Which is one of the reasons they say to put your tray tables in upright an locked position.

But even beyond that feeling like you’re falling out of your seat is unpleasant.

Automakers solved this problem many years ago, by making cupholders that are deeply recessed instead of thinking that cups wills somehow magically stay in place with a very minimal indentation (see the "cup holders" on the backsides of glove compartments in 1970s American cars).

Airlines would rather have more people in economy than to include cup holders.

You do sometimes see cup holders on private airplanes, but in commercial aviation the efficient solution is to avoid needing them.

Adding decent cupholders to cars didn't make cars bigger.

Similarly, adding decent cupholders to airplanes is not going to reduce passenger space.

Commercial aviation could stick as many as 850 passengers on an A380-800 in it’s maximum configuration, but the most an airline actually gets is 538 because of business and first class passengers having more room. Increasing passenger space by even 1 inch or just a pound of weight per seat makes a real difference.

Better cupholders do not decrease space at all. Some (better) airlines even have them: they flip down from the seatback. They literally take no space at all. This is ridiculous.

Cut a hole for cups to sit in on the back edge of the tray tables?

People falling over is more of a concern, it would take significant lateral acceleration before drinks fell it’s just easy to visualize.

As to why no cup holders, people aren’t going to use them most of the time and they don’t even help that much in turbulence.

The issue isn’t the bank angle but pitch acceleration felt by the passengers when they pilot wants to bank for a turn. Which opens up several methods to compensate.

You could for example more slowly enter a higher bank angle to have an equally fast turn though passengers would feel more pressed into their seats etc.

Turbulence causing roll upsets seems like it could be a larger issue.

you could also put the passengers more towards the middle and the fuel / cargo on the tips. Doesn't solve the problem and balance would be tough I imagine.

they don't have to be shallower, just bank angle increase should be slower than usual.

this issue is why the startup in socal is focusing on air freight for their flying wing design.

I'd image the biggest reason is that risk tolerance is lower for cargo companies than for passenger airlines, and that cargo companies are more inclined to run a subset of their fleet as an "experimental" model vs the consistency that passengers expect. They probably also have the biggest potential gains given there's only so tight you can pack people.

Banking isn't a problem in practice or your coffee wouldn't stay in your cup while standing on the table.

That's called a "coordinated turn", and it's what airline pilots should be aiming at whenever possible. In a coordinated turn, "down" remains aimed at the floor, regardless of actual bank angle. There's even an instrument (the turn-and-bank indicator) designed expressly to help pilots execute coordinated turns, which are generally considered a mark of a capable pilot in any plane...

I mean, the rise of low-cost carriers has shown pretty clearly that passengers are willing to put up with a lot for cheaper tickets…

This "falling" feeling is my favorite part about flying

It might be good to have a disincentive for the peripheral window seats. Some also find that feeling of falling / turbulence enjoyable.

people in the center, cargo in the peripherals

makes evacuaion harder that it has to be

>This also applies to existing aircraft, but the amount you drop/rise is limited by the your distance from the axis of rotation, which is normally not very far.

When a plane is crabbing, as in coming in sideways towards the runway, when it touches down, and suddenly pivots to normal runway directions, even passengers in the rear of a normal plane, might be accelerated hard around the yaw axis.

I wouldn’t want that on a red-eye, but it would add some entertainment to a one-hour flight.

Would legit pay extra for the fun ha

> A bigger problem with blended wing designs is actually for the people on the peripheral. When the plane banks, passengers further from the axis of rotation will feel a more significant change in their altitude. You literally feel like you're "falling", as the plane banks to your side.

This is a problem that a market can easily solve: make the more central seats more expensive than the outer ones. If the pricing is right, the demand for the various kinds/positions of seats will be balanced.

P.S. I can actually imagine that there do exist people who prefer the outer seats because they like the acceleration that makes the flight feel more like a carnival ride. :-)

Totally on board with flying in the outboard cheap seats, at least for any flight where I don't have to sleep. Flights are incredibly boring aside from takeoff and landing, and I love roller coasters. :)

I have a feeling there are enough of us to make it work in the market and still fill planes, just instead of first-business-coach going front-to-back it'll go center-out, like a theater.

Man you must like some adventure.

> This is a problem that a market can easily solve: make the more central seats more expensive than the outer ones.

There are risks to create a "vomit comet". Think about cleaning bills.

Does this mean if a blended wing plane banks hard and you stand up on one side of the plane you could potentially jump your way across to the other side a bit?

My understanding is that having to manufacture a different rib for each station along the structure is a significant challenge. It's possibly less of an issue with composites?

The differences in ribs across the span of a wing are much less of an issue than compound curvature in the wing skins—this is where composite manufacturing really shines, because you can mold them into arbitrary shapes.

The ribs are already all different across existing commercial airplane wings.

Across the wings yes but not across the majority of the fuselage.

How is that a meaningful distinction from either a design or manufacturing standpoint?

Because the fuselage is pressurized. And it is convenient to have pressure vessels as cylinders for even distribution of of the pressure forces across it. Ideally you want to have it capped off with two hemispheres (think propane tank shaped) but obviously you can't do that for other reasons. So there is likely more design and manufacturing for the front and rear of the plane than the main section.

Ah, gotcha. Yeah, there’s zero chance that you can make a pressurized pancake using rib-and-stringer architecture, probably even out of unobtanium. The best candidate I can think of is making it like a submarine, although that would definitely mess with the open concept floor plan and probably impose a huge weight penalty (although it might be helpful from a fatigue life standpoint). The only other remotely viable solution I can think of is drop stitching, but that has some fairly obvious drawbacks that would probably make it impracticable.

Another problem is how planes are designed for different sizes. Say you design your plane with the base / most ordered as the dash 9. Now someone wants a smaller longer range one.

just take some fuselage barrel sections out. Boom dash 8. Want an even smaller one. Take more sections out. Dash 7. Need a huge massive super long range one with loads of seats. Add sections and you get the dash 10 or 11.

Current planes use a uniform fuselage structure for this reason. You're going to make different models within the same model family with a flying wing.

In the fuselage they're called frames, not ribs for info

If the all the manufacturing techniques have to change, maybe 3d printing some parts or the whole plane would make sense and be viable.

The expensive part of composite aerostructures isn't making them, per se, it's the molds and tooling you have to build first, and you need a lot more of those when contours are constantly changing. (This isn't new though - continously changing contours have been the norm since the first high supersonic wasp-waisted "area rule" fighters and bombers appeared in the 50s and 60s.)

That said, I was working on B-2 aerostructures in the late 80s, and I can tell you that most all the parts on that plane have no symmetry in any direction other than centerline bilateral. My group figured we could save over $10 million each on a single B2 duct, if we could change the bizarre geometry to simplify the scary complex tooling it required. That was enough potential savings to provoke a design review, but the answer came back, "Nope. It has to be that way (we presumed for stealth). Go figure out how to build it..."

Anecdotally, I hate flying if I can't see out the window. Like, really really hate it.

My experience as a frequent flyer is that First Class is the most likely cabin to have all windows closed for 100% of the flight. It's baffling to me, people will even keep closed the window facing New York on the approach to LaGuardia which should be a crime. Also Boston, Salt Lake, Hawaii, and really pretty much all places except like Dallas and Cleveland types totally perplex me when the window is closed and I'm not directly next to it. I want to witness this glorious rock from above!

I see this more and more everywhere across the plane these days.

I remember flying as a kid/teen and nearly every window was open during takeoff and touchdown. Last 3 to 5 years and almost every flight has had less than 10% of the windows open. I don't get it - I also want to see it. We're fucking flying, for god's sake.

They didn't have the magical rectangle when you were a kid. Might miss some celebrity vacation pics if you take your eyes off it.

I thought I was the only one who experienced this.

I race cars as a hobby but I suffer from motion sickness whenever I’m not driving or whenever I can’t see out. People will choose the window seat and keep it closed the whole time. WHY?! At least open it when we’re on the ground being shaken back and forth while backing out and taxiing so my mind doesn’t lose point of reference.

They used to ask you to open the window shades for takeoff and landing, idea was to actually be aware of what is going on outside incase an evac is necessary.

Now they ask everyone only to close the window shades after landing to better control the temp, the APU a/c is often no match for direct sunlight. Then most people just leave them closed.

I've heard the opposite. Keeping the shades open is so that the rescue crews can look into the plane in case of a crash/accident.

At least in Europe having the blinds open (and the lights dimmed at night) is an airline requirement.

https://news.schiphol.com/why-do-the-window-blinds-have-to-b...

And once upon a now long time ago, when I was a boy, the food was actually hot, quite tasty, prepared by actual chefs, and served on real china dishes with metal silverware. (Even in Coach - it was many years before I travelled enough to get a few upgrades to First Class!)

Modernity and MBAs have stolen the elegance and service that flying (or the train, to an earlier generation) used to have when America was great. I remember marveling that as expensive as such flying was, it was really not a bad deal to get a great meal served by pretty young women looking over such amazing vistas, with fast, smooth transportation thrown into the bargain!

This always baffles me flying out west. I mean Nebraska, Kansas, Iowa - i get it - close those windows we can sleep. But the Rockies, Mt St Helens, Mt Hood, Mt Rainier...and then you hit the mfin GRAND CANYON and you still wont open up your window?!?! people that don't open their window over the grand canyon need to be put on a list for middle seat only.

I am regularly on flights which go over the Grand Canyon. On that flight specifically, I keep my window shade open for the sake of the folks in the middle and aisle seats.

Of course, they are probably thinking "wish that view didn't have that sleeping dude in the foreground".

You're still a hero. Thank you for sleeping so I don't have to feel awkward making you think I am looking at you while looking out the window.

yup it's insanely annoying

i flew business to hong kong a few years ago and i couldn't put the shades up AT ALL because of people sleeping most of the flight, which sucks because from the crack I was able to see through, we passed through some incredible shit

Back before the in-seat video days, I was flying back from Europe to the US. We were just approaching the coast of Greenland. I could see icebergs in the water, and glaciers coming down to the ocean. Then they asked us to close all the windows so people could see the in-flight movie. And I'm like, when am I going to see Greenland again? I can rent the movie.

When I've flown first class frequently it was during times of my life when I was flying a lot and so had miles to burn on upgrades and such.

After the first few times - especially if you're flying the same routes over and over - I got used to it, for better or worse.

I flew relentlessly for work for years and the view out the window of the plane was the one thing that never got boring or I took for granted. Actually, add lie flat seats. Everything else definitely became part of the wallpaper.

It... might have something to do with a psychedelic experience I had on a plane once...

I get this, but also peering out a narrow plane window at a view which is often at least substantially blocked by wing is not always fun.

I would like airlines to put a 360 degree camera system mounted to the exterior, and pipe through the feed either to a channel in an in-seat screen, or make it available to passengers wearing a VR headset. Imagine one of these much wider planes where many more seats are middle seats -- but where you can sit down, put on a VR headset, and get a clear image of the view in every direction. If fewer people will have a window in these future planes, and most awake people are looking at an entertainment system anyways, I would like the airline to pipe through a feed from a 360 degree camera mounted on the outside. Imagine sitting in a middle seat, comforted by the fact that you can put on a VR headset and

I'm claustrophobic. Having the window there and next to me is essential for me. Mentally, i need to feel like there's an exit i can jump through if things go awry. Of course, thats not realistic. But some artificial screen doesnt give me the same comfort. Looking out and see the outside for myself is the only thing that does it

People seem to prefer either the window or the aisle. You go and select seats, and it's always the middle seats that are left over. So it might be an issue if these new plane designs have lots of middle seats. They might have to give more space to the folks in those seats to get them filled.

This "problem" goes away if you just have one of the feeds in the seat-back entertainment system be a wing mounted camera view no?

Maybe if you had it in stereo 3D and gave the passengers a VR display.

If that were true, why would the person be on the plane in the first place? Couldn't they just watch a movie of their destination or zoom call the person they were visiting from home?

> If that were true, why would the person be on the plane in the first place? Couldn't they just watch a movie of their destination or zoom call the person they were visiting from home?

It can be the case that both:

* watching a video of the plane moving through the air is an effective way to mitigate some of the discomfort of flying

* meeting face to face with someone is valuable enough that it's worth taking the flight

? people go on planes to get to places not to experience flight itself per se. i don't mind sitting in an enclosed room for x amount of hours while it gets me half-way across the world for cheap

Personally, the only things I care about in a plane are safety (by a wide margin), comfort, and price. I spend all my time listening to music with my eyes closed or watching movies anyway, and the window doesn’t give me much.

Maybe just put a bunch of cameras all over the exterior so the passengers can see what’s going on wherever they are sitting.

I hear you. But the first time I did a polar/Hudson Bay flight between Europe and west coast USA, I was transfixed by the view out of the window. I’m very happy to have seen that extraordinarily beautiful view.

Cameras would be some compensation, but the direct view is amazing.

Arguably not as spectacular, but I relish every city approach. The serpentine Thames as you stack over Heathrow, the mountains of Vancouver, the insane scale of Tokyo: I value fuel and cost savings, but I hope there will always be opportunities to experience these wonderful views.

Planes have a huge impact on both the climate and economy, and I don’t think the joy of occasional sightseeing is a strong enough argument against pursuing efficiency gains.

The main argument against it is that it increases fuel consumption. Plowing your cargo area through the air sideways is just idiotic. There is some crazy public belief that it is more fuel efficient because the public doesn’t understand physics. These things keep getting getting publicity because even Hacker News folks don’t get it.

Long high aspect ratio wings and streamlined body are how you get fuel efficiency.

The fuel burn of a B2 is far higher pound for pound than a 737.

This idea gets even more ridiculous when you consider the cargo area is a pressure vessel. There is a reason the body is isomorphic with a welding tank.

Edit: I suppose I wouldn’t care about this, but the Biden Administration plowed climate money into a blended wing military concept, which 1 day with any CFD software shows is stupid.

You seem knowledgeable about this. Do you mind expanding on why these aren’t more efficient?

I'm no aerospace engineer, but the flux through the air, driving resistance, seems obviously higher the more you move away from the shape of a missile.

The problem is frontal area is higher, so more drag. Wetted area[1] is also much higher, so there's a lot of skin friction.

The advantages are (theoretically) lower structure mass per passenger. But airplane cabins are pressurized, and lightweight pressure vessels 'want' to be cylinders or spheres, not big flat boxes.

There's a aerospace engineering student who gave a thesis talk on the disadvantages of blended wing-body, and offers some possible solutions.[2]

[1] https://en.wikipedia.org/wiki/Wetted_area

[2] https://www.youtube.com/watch?v=IWBaddGG6z8

It’s not that simple. Aerodynamic drag is made up of surface drag and induced drag. Given the same coefficient of drag, drag goes up as S-wet goes up (which is what you’re referencing). Induced drag is a consequence of how much structure is required to create a flying vehicle. IF (and it’s a big if) the BWB turns out to be more structurally efficient, then the total drag for the plane might be less than for a conventional design.

(Source: I have an aerospace engineering degree from Embry-Riddle)

> There is some crazy public belief that it is more fuel efficient

There are a number of engineers at NASA and Boeing working on the X-48 who would disagree with you on this one.

The main advantage of the blended wing body is to reduce the skin friction drag [0] of the aircraft relative to the typical fuselage and wings. You have less surface area in contact with the air relative to the amount of internal volume. There may be some increase in the profile drag (i.e. the cross section of the aircraft) but is made up for by the reduction in the skin friction drag.

> The fuel burn of a B2 is far higher pound for pound than a 737.

This isn't really a fair comparison. They are two aircraft optimized for entirely different things.

[0] https://en.wikipedia.org/wiki/Skin_friction_drag

Skin friction drag is a drop in the bucket compared to parasitic and lift induced.

I’m willing to accept that a gold bullion transporter can look closer to a flying wing, but with any reasonable cargo density you are back to the standard design.

Trying to intuitively explain CFD results is apparently just as hard as dispelling the Bernoulli nonsense about airfoils.

I’m right and high aspect ratio wings are a harder materials science and design challenge than blended wings. There is a reason 10000x as much engineering effort is going into folding carbon fiber wings for passengers/cargo. The folding is to increase fuel economy through aspect ratio and fit in terminal box.

Everything I have said is trivial to prove with CFD and experimentally. I get that popular science articles need to entertain the masses.

Let me ask you this, why is the tail of passenger aircraft upward sloping?

One, I'll admit I'm not an expert in this, I have an aerospace degree and took some aircraft classes but it was 90% on the space side of things. But I'm trying to be devils advocate here since its not just pop-sci articles.

> Skin friction drag is a drop in the bucket compared to parasitic and lift induced

I'm trying to rectify it with papers that say "In civil aviation, skin-friction drag accounts for around 50% of the total drag in cruise conditions" [0]

> I’m right and high aspect ratio wings are a harder materials science and design challenge than blended wings

I understand that higher aspect ratio reduces drag too and that the planes should all look like scaled up gliders with their long skinny wings. But as you said, it is harder. So is it a clear cut answer that exploring blended wing designs is a waste of time?

> Let me ask you this, why is the tail of passenger aircraft upward sloping?

To prevent tail strike during take-off and landing when you are at a high angle of attack.

[0] https://www.sciencedirect.com/science/article/pii/S037604212...

Do you have any sources for this? My understanding is that hybrid wings reduce weight needed for structural components. Since fixed wings basically trade drag for lift, reducing weight can more than offset increases in profile/shape that increase drag.

https://www.technologyreview.com/2013/01/24/180345/hybrid-wi...

I mean, aerodynamic drag scales linearly with both Cd and A. It isn’t too far-fetched to think that you might be able to trade them off in a blended wing design and come out ahead by reducing interference drag and wetted surface area.

The pressure vessel problem is much more concerning to me—I can’t think of a way to solve it that wouldn’t massively increase weight and/or reduce usable space.

To be fair, the B2/737 comparison isn’t particularly fair—they were optimized for wildly different things, and only one design was significantly constrained by acquisition and operational costs.

I see. So this is why a flock of geese flies in a single file, rather then, say, a V shape.

Goose wash is the problem with single file. Goose V takes advantage of the up current you get from the neighbors lift. Geese and evolution clearly understand areo better than current HN.

Aerospace engineer here, this is incorrect.

Long thin fuselages dramatically increase drag due to skin friction. Blended wings have better lift to drag ratios, meaning for a given amount of fuel consumption (to overcome drag) you get higher payload/better range.

The B2 has twice the range of a 737 and cruises 20% faster.

I'm curious if your thinking on this matter has changed based on the replies you have received ?

No. The points made seem to be like asking if it is a good idea buy something that costs 25% more when you have a 5% coupon.

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