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Comment by challenger22 | Hacker News Reader

Wow. The criticisms I've seen about using flying-wing designs for passenger aircraft (planes that look like the B-2 bomber), are often focused on how bad the boarding process is for the movie theater seating they require. This design looks like it eliminates the seating problem pretty well. Flying wings have been known to be more efficient for a long time; logistics problems are the devil in the details.

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Yet the image provided is the most radical representation I have seen of the "flying wing". This is two fuselages in V by initial look. I would still think that you could simply provide a screen for the interior passengers to have a view out, from the opposite side of the aircraft. People have done just fine in the center rows of jumbos so I am not sure that the negative impact is high as imagined.

The thought experiment to play with is, swap out windows for computer displays, still with the air gap seen on some planes, but not for all windows and see what transpires.

Discount business class in the isle, economy next to window.

Problem solved.

Probably wouldn't happen -- it would require one class to rub elbows with another.

"Why have windows at all outside of First Class?"

-Airline execs once economy passengers get used to having no windows on one side.

Pretty sure windows are required so that passengers can see outside in case of an emergency.

You could have cameras and screens instead of windows. Much, much cheaper in the end.

Doesn't seem like the kind of thing you can rely on in an emergency.

Maybe, though such footage would be useful in a black-box for post-incident/post-flight analysis as a visual comparison to the recorded control/instruments - could only help.

Windows tend to work slightly better after running into the ground than cameras, electrical systems and screens do.

(A broken window still lets you see outside)

You don't need to have a window on every seat. You could have a few real windows on the side and complement the missing ones by screens.

Fair point - I was on a plane and on landing saw the wing flap act in an unusual way (didn't fully open compared to other flap and seemed like it was limited/stuck on one edge and one end raised more than the other and down end shaking and wasn't what I'd seen on that type of boing before). I pointed this out to the staff, who thanked me. Might of been nothing, and not something you follow up or indeed, how you would follow up. But equally, may of been sign of something amiss.

>However, aviation regulator the European Aviation Safety Agency said [in reference to windowless planes]: "We do not see any specific challenge that could not be overcome to ensure a level of safety equivalent to the one of an aircraft fitted with cabin windows."

https://www.bbc.com/news/business-44383220

Don't they just need windows at emergency exits? Passengers are already supposed to await cabin crew instructions before they evacuate, and passengers probably aren't really that great at evaluating danger aside from the obvious signs like fire or being under water, but the exit door window would also tell you that.

Or more importantly so that the rescue service can see in.

Not sure if there is "reason" for forward facing seats (perhaps crash safety? If so, why not put them all backwards since that is safest?)

I could imagine seats facing "outwards", with a corridor along the windows. Kinda like a cinema but the screen is replaced by a row of windows. This way no one gets to "hog" the window seat (apart from the front row, and even then others can still see the windows on their walk along the corridors to the toilets etc). Bonus points for raised stadium-style seating with storage lockers under the rows at the back.

I'd guess the G-forces of take off would be quite uncomfortable if seated backwards facing. You'd be pressed into the seat belt rather than into the seat.

Are takeoff G-forces actually higher than braking G-forces at landing? I think they're probably comparable given the speeds and runway lengths are similar, so you would just be swapping the seatbelt discomfort from the end of the flight to the beginning. You could also probably make the seats pivot slightly to counteract the plane's angle of attack causing discomfort.

I'm not an expert on this issue in any way, but my instinct is that there would be more acceleration during take-off. When landing, the plane has already decelerated to just above the minimum speed to maintain lift (nearly stalling), and doesn't have to come to a complete stop on the straight part of the runway before turning off to wherever it's going to de-board. Conversely, during take-off the plane goes from zero to hopefully well above the speed to generate lift.

Also, the plane tilts by up to 20 degrees.

My instinct was the opposite. I happened to be on an A321 this AM so measured it with my phone.

Acceleration was about 0.4 g with peak of 0.5 g. Second stage climb (5-10K) was 0.2g nose up. Rest of climb was 0.1g. Decel was 0.3-0.4 g also with a peak at 0.5 g.

On the big engine Lears, I’m quite sure the accel is higher than braking plus reversers. Airliners might also have higher accel rates on shorter runways as they often do power limited takeoffs on long runways in the interest of maintenance economy.

Related, we had a hold for weather at the destination, so I checked the pitch of the plane in the hold. It was 0.1 g nose up, which was quite noticeable when walking up the aisle to the restroom.

Braking is higher G but consider that the descent and landing aren't really nose-down situations and the braking part itself takes seconds. When taking off you have nose up for quite some time throughout the climb. Sitting backwards would make it pretty uncomfortable unless the seats are somehow redesigned (they'd have to be anyway to handle the different stresses).

We fly an aircraft with "club seating" (two rear facing seats facing two front facing seats). Experimentally, my son who is prone to airsickness has a harder time in the rear facing seats [which are closer to the center of mass and center of lift and so experience less excursions in turbulence than the forward facing seats, yet he is sicker in the rear-facing seats].

Those of us prone to motion sickness don't do well when facing the wrong direction. I have the same problem in trains /subways /limos /etc

I think it is safest if you will not factor people having book/laptop/hot coffee in front of their face. For other considerations see sibling posts.

The same issue is for back facing seats on autonomous cars. I don't see it happening.

It's not that easy to make a screen that looks anything like a real window, the main reason being that the perspective won't change when you move your head.

Where are you seeing information about the seating in this design?

I don't think there is a spec, but looking at an image of a b-2 versus the image in the article should give you an idea to start with.

See youtube https://youtu.be/MvekG31FbJM?t=9 for an artists conception of the seating layout.

Crash will send you flying between the seats, it looks like. The seats would need to be oriented differently.

Isn't that what seatbelts are for?

Only partially. Ever tried bending forward with the seatbelt on in the plane? You can easily reach with your upper body to the seat in front.

In case of a crash, the seats will move forward and then spring back, if you have your body in between of the two seats in front of you while they do this, you can easily get crushed.

On planes, belts are to prevent you getting thrown in to the ceiling during turbulence. That's why you're supposed to keep them on at all times.

>On planes, belts are to prevent you getting thrown in to the ceiling during turbulence.

e.g. Billy Mays

Heart disease, possibly incurred from cocaine use, was his cause of death. The luggage hitting his head after the tire blowout was ultimately not the cause, though was initially reported that way.

was that video 100% auto-generated? sounded like a robotic voice.

Youtube is fully of spammy auto-generated videos reading press releases and other nonsense.

Yes I pray for the day when google algorithms detect this crap and deindex those.

Looks like the plane loses a good chunk of its window seats, and another good chunk are just looking at the other half of the plane.

Not that these are deal breakers, but it's generally safe to assume that at least economy passenger experiences are going to get worse, not better.

I am inferring it from the shape of the aircraft.

I thought the problem was they are more difficult to fly, less stable.

My understanding is that the YB-35 flying wings had difficulties with stability along the Y axis, part of the reason they weren't suitable as bombers (for dumb bombs).

Eliminates the seating problem by... eliminating the problem seats. I mean you could have done that without changing the plane's shape.

20% less fuel is huge, that's the real plus.

Yep, Boeing has talked about a Blended-Wing-Body airliner but it turns out passengers don't want to ride in the middle of such a monster.

The flying-V solves that.

> Flying wings have been known to be more efficient for a long time

Source needed

In the UAV world, the longest endurance loiter time fixed wing craft are either relatively slow and with long, straight wings (the 30 hour version of the rq-9, or the global hawk), or are flying wings...

Sure, but those are not features you want in a cargo or passenger aircraft.

The Global Hawk has a wingspan over 50% as long as an A350, yet it weighs 1/10th as much. There is no comparison.

> The Global Hawk has a wingspan over 50% as long as an A350, yet it weighs 1/10th as much. There is no comparison.

I agree that there is no comparison - in the sense that the two cannot be compared that way. For example: A childhood toy of mine (a compressed-air plane) needs a wingspan 1% as long as an A350, yet it only weighs 1/1,000,000th as much - and can still only stay airborne for 30 seconds!

This discussion [1] on the different most-aerodynamic plane shapes is fairly interesting, and certainly doesn't confirm the person above who claimed that a flying wing is the most aerodynamic shape.

[1] https://aviation.stackexchange.com/questions/17119/what-is-t...

Well, given that mass would scale as square of wingspan that is only 2.5x as bad.

> Sure, but those are not features you want in a cargo or passenger aircraft

Depends on the use case: for a feeder aircraft (regional to international airport) load, range and speed isn't terribly important, but fuel economy still is, for economical reasons (and for ecological reasons, which translate into economical by making the tickets an easier sell to a climate-aware population). In well developed regions, the main draw of feeder planes over ground transportation is not travel speed, but the convenience and piece of mind of checking in at your home airport.

Since a lot of regional (or effectively regional) airports are wildly overbuilt in hopes of attracting bigger connections there could be a market for a plane that fills the available width with a modern high aspect ratio wing to max out efficiency for small loads. If new aircraft designs weren't prohibitively expensive or fuel would be much more expensive this kind of plane would exist. Basically, put the wing of a Global Hawk on an ERJ-145.

https://en.wikipedia.org/wiki/Boeing_X-48

Note 1: Boeing once toyed with a blended wing-body, a sort of flying wing, to produce dramatically better aerodynamics and fuel efficiency. Passengers would have sat in a wide cabin, rather like a small amphitheater. But tests with a mock-up produced such a negative reaction that the company dropped the technology, except for military refueling aircraft.

That link provides nothing to backup the previous claim.

Unfortunately the source of that note, an article in the Economist from 2006, doesn't indicate when they tested. Standards and expectations of airline passenger comfort have degraded significantly over the years, so it might be reasonable to retest.

Although, I found an article from 2018 [1], quoting a Boeing VP of Product Development and Future Airplane Development, which basically says a blended wing design for commercial passenger aviation is unlikely because the required minimum height for passenger loading implies a minimum width that is quite large, and may not be very compatible with existing airports.

[1] https://leehamnews.com/2018/04/03/dont-look-for-commercial-b...

Lift to drag ratio.

Aerodynamically the wetted area that generates drag without lift is undesirable. You need a wing generate lift, but everything else is there for something else like stability, handling, payload etc.

In conventional "tailplane" configuration the fuselage and tail are just providing drag and almost no lift (tail has little wings 'upside down' generating negative lift and trim drag). If you have canard or some more exotic wing configuration you can have all wings generating lift but there is still drag from the body. In clean flying wing, there is nothing else except the lift producing wing.

Not entirely true. In a flying wing there is constant flap adjustment needed to counter balance a CG (center gravity) offset. The amount of counter drag is higher than a narrow winged tailplane. Obtaining a correct CG is therefore also more crucial. With variations in passengers and other load this will be a challenge.

But thick, deep wings are not exactly known as the very definition of aerodynamic efficiency either. Are we sure that a sleek long tube added to a well-designed wing can be beaten by a wing that is full of compromise to accommodate seating?

It's the thickness-to-chord ratio that matters, not absolute thickness.

Swept wing in the Flying-V is clever way to get a optimal thickness-to-chord while keeping the total surface area in check.

Concerning the horizontal stabiliser providing negative lift: it's possible and frequently so, but not necessary for stable flight.

(If I understand correctly, what is required is that its angle of attack is lower than the one of the main wing, or equivalently (if the wings have the same shape) its wing loading.)

See section 6.1 here, for example:

http://www.av8n.com/how/htm/aoastab.html#sec-basic-stability

Yes. That's not theoretical requirement for tailplane.

But as the source you provides say: "indeed most aircraft operate with negative tail lift most of the time."

In practice all commercial aircraft have the center of mass so much forward that require negative lift for stability. If you look at the cross section of the horizontal stabilizer, it's like wing upside down.

My understanding is that airlines like to load their planes such that the CG is such that the tail contributes basically no lift, to minimise drag and fuel consumption.