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Comment by dmitrygr | Hacker News Reader

The main problem with flying wings, and probably this design too, is that they are inherently unstable, and without very precise computer control they are uncontrollable. Compare to modern planes that a good pilot can fly and land with zero computers, given some effort. (They are stable, and with no control inputs at all just keep flying in same attitude as they are currently in)

In a flying wing, computer failure is a certain airframe and passenger loss. I don't know any engineers who write flawless code. Do you?

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This is patently false. In fact you should delete this post in its entirety because it's just wrong. Don't make these things up and post them as fact. Flying wings easily fly without any computers whatsoever. They are inherently aerodynamically stable. Only manual elevon inputs by humans are actually required and it is quite easy to control unless your center of gravity is too far back. The CG is usually around 70% of the way to the front from the back.

Instead of spending half your comment saying how wrong GP is, why not provide some compelling evidence? I was under the impression that flying wings are indeed more unstable than traditional airframes.

For example:

https://en.wikipedia.org/wiki/2008_Andersen_Air_Force_Base_B...

> After the wheels lifted from the runway, which caused the flight control system to switch to different control laws, the erroneously sensed negative angle of attack caused the computers to inject a sudden, 1.6‑g, uncommanded 30-degree pitch-up maneuver. The combination of slow lift-off speed and the extreme angle of attack (and attendant drag) resulted in an unrecoverable stall, yaw, and descent.

This seems to support GP's assertion that "without very precise computer control they are uncontrollable" and "computer failure is a certain airframe and passenger loss"

This says they can be designed to be passively stable, and indeed have existed since the 1930s: https://aviation.stackexchange.com/questions/2252/how-does-a...

I think it requires a little more careful design then traditional plane bodies, so there is some sense in which flying wings are less stable naturally. But the claim that flying wings are necessarily unstable without computer control seems to be false.

Absolutely no one denies that the B-2 in particular is unstable, but it is one particular model designed to a particular set of requirements that are vastly different from those for a commercial airliner. It seems that the general public have internalize "the B-2 and F-117 are inherently unstable" as "flying wings are inherently unstable", which is incorrect.

To be even clearer, these two planes were designed with the goal of having the smallest radar cross-section possible. The lack of aerodynamic stability was worth the trade off (esp. since it could be compensated for by flight computers).

A hang glider is a flying wing, has no computers on board does not crash by itself :) Hopefully that does the job as an existence proof.

Uh, not really? Seems more like a failure of the computer. Don't know much about flying but sounds like a pretty extreme maneuver was attempted by the computer.

Take a piece of printer paper and lay it down landscape, fold the top inch down a couple times, then crease in half. A classic.

I build and fly flying wings that don't have computers

Flying wings that are controlled entirely manually exist. A favourite example (I know people that have flown these) is the Marske Pioneer[1]. An actual glider with highish aspect ratio wings that was and is quite flyable by hand

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

The design in question is more of a flying dart than a flying wing anyway. There is no reason to think it would be particularly unstable in pitch.

>flying wings ... are inherently unstable

Not if you use an airfoil with an appropriate pitching moment, that's designed for flying wings. Look at all of the hobbyist models that fly just fine using very crude control inputs.

>In a flying wing, computer failure is a certain airframe and passenger loss.

No.

The control sticks in an Airbus A320/330/350 are entirely decoupled from the mechanical control surfaces. All control inputs are going through "computers" in even the most manual of flight modes.

And that is why af447 went down. Pilot didn't feel copilot pulling up, and computer averaged the inputs... Yeah, that works really well

P2 was actually trying to get the nose down. The pilot flying was quite determined to keep the aircraft pitched up. They knew they were fighting on the controls, there was a voice announcement whenever it happened. The root problem was that they were not communicating with each other in an effective way. If P2 actually felt that strongly, he should of assertively stated that he wanted control (which he eventually got BTW) rather than trying to steal control. If he really felt strongly enough to mutiny against the authority structure, he should of whacked the pilot flying with the fire axe.

In a working cockpit, there should never be a question as to who is actually flying the plane...

AF447 went down primarily because of bad training, bad communication, and bad reactions by the pilots. Active sidesticks may have saved them as a last line of defense, but it isn't the primary reason the plane went down.

This is a false argument IMO. It is possible to do a reliable fly-by-wire system. Difficult and expensive, but possible.

You have never flied a kite have you? What do they most of them look like? Flying wing!

Are there wing designs that encompass strong dihedral characteristics?

and manufacturing blended wing bodies is very difficult to do

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