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I was told in this other question this aircraft was not real, and that it could not fly in this design.

Shame it can't fly but why?

I'm now interested in knowing what would prevent it to fly, from an engineering point of view. It looks great... why is it so obvious this cannot work?

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  • $\begingroup$ What makes you say that it would not work? $\endgroup$ – egid Jul 30 '17 at 17:30
  • $\begingroup$ @egid as I commented on the other post, main gear too forward, for example? $\endgroup$ – Federico Jul 30 '17 at 17:55
  • $\begingroup$ My take is that the CG is far forward, and the center of lift is behind the main gear. $\endgroup$ – mongo Jul 30 '17 at 18:58
  • $\begingroup$ Because (as I look at the picture closely) it appears that the outboard section of the left wing is in the process of breaking off? $\endgroup$ – jamesqf Aug 1 '17 at 19:16
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That picture appears to be a photoshop assembly of real aircraft bits from common landing/take-off shots, made to fit the shape of a NASA X48, an unmanned flying test aircraft about the size of an ultralight. Whoever did the photoshop job even slavishly copied the undercarriage position (but not the relative undercart length/height) of an extremely lightly built, largely empty, model aircraft.

It certainly can fly.

https://www.nasa.gov/topics/aeronautics/features/bwb_main.html

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  1. As the comments point out, the main landing gear is too forward. Delta wings (and blended) typically land (and takeoff) with a high nose-up, should be an easy fix.
  2. Left wing is longer, again easy fix.
  3. Outboard control surfaces (normally would be elevons) are both pointing down on approach (or is it climbing?), tail heavy?
  4. For a blended wing body, the airline still chose a tail-fin logo (backwards mind you)!
  5. Natural pitch stability is required for certification, but the way it looks this design is unstable in pitch. Note that all trailing flaps are deflected down, something which will generate strong pitch instability. There is no obvious means by which a counteracting pitch response could be generated.
  6. It looks as if payload is held mostly in the forward part. While it could be balanced when empty, with any sensible amount of payload it will be hopelessly nose-heavy.

Related: Why is there really only one basic design for passenger airplanes?

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  • $\begingroup$ Re #1, just about everything takes off with a nose-up attitude. Try that in this, and you'd be trailing sparks down the runway. $\endgroup$ – jamesqf Jul 30 '17 at 19:03
  • $\begingroup$ Of course, the general layout can fly. After all, it is not that different from B-2. However, the details clearly show that this is not an image of anything real. $\endgroup$ – Jan Hudec Aug 1 '17 at 18:37
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Passenger evacuation for one. Right now, you can open some doors on the side of the tube and add more doors if needs be. That's a lot more of a challenge here.

Also, distributing passengers to a wider area inside the body can lead to greater instances of motion sickness.

Passengers will generally prefer having windows, which is also a challenge for this type of aircraft.

Main gear should be far enough forward that most of the weight is on it, but far enough aft that the nose isn't unloaded in aft CG conditions. It might be right where it needs to be. You'd have to know the CG location. You also need to account for an empty airplane with minimal fuel or it could tip up onto the tail. Tip up.

A large lifting area should at least mean slower landings, but gear should be long enough or far enough aft to flare a bit. You want the mains to touch first so you don't bounce or damage the nose gear.

It's not so much that it can't be done, but there are challenges.

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    $\begingroup$ Re "Passengers will generally prefer having windows...", I'm not sure about that. The few times I've flown commercial, it seemed that most of the other passengers were far more interested in watching the in-flight TV. $\endgroup$ – jamesqf Jul 31 '17 at 17:35
  • $\begingroup$ Well, you do know the CG location. Or more precisely: the CG must be just before the quarter (average) chord and it must be a just little more before the main gear. Therefore the main gear must be just after the quarter-chord. But it's well before it! $\endgroup$ – Jan Hudec Aug 1 '17 at 18:14
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I believe the challenges to using BWB as a people mover are the motion sickness and evacuation issues. Soluble, but challenges nonetheless. Of course, airport and runway suitability are possible issues as well. Military airlift is a probable first application for BWB.

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  • $\begingroup$ What's BWB? Inline more information will help aircraft enthusiasts that might not know much :) $\endgroup$ – tgkprog Jul 31 '17 at 13:51
  • $\begingroup$ Blended Wing Body. $\endgroup$ – Skip Miller Aug 1 '17 at 0:13

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