Maybe a gyroscope + glass of water ?

XMPPwocky · on Feb 9, 2020

No. Angle of attack behaves in some very non-obvious ways-

For example, if you maintain the same attitude, but decrease thrust so that your forward airspeed drops, and you begin descending... your angle of attack increases, despite the aircraft not actually rotating.

Why? When you start descending, the air below now seems to be "coming up at you"- you go from

  ---> (===

to

    7  (===
   /
  /

if that ASCII art helps at all (equals signs being the wing)

Now consider how roll, yaw, and crosswinds affect this- as the AoA becomes variable across the wing...

t0mas88 · on Feb 9, 2020

Doesn't work. The stall is about the angle at which the airflow meets the wing. The gyroscope (with or without glass of water) will tell you the attitude of the plane, but nothing about the direction from which the air meets the wing.

You can stall in a nose down attitude if you're descending fast, the air comes from "below" and you try to pull out ift the dive thereby increasing the angle at which the air meets the wing. All the while your nose is still pointing below the horizon.