So the flow over the top of the wing breaks free and forms a huge vortex and the drag increases tremendously? Sounds like an aerodynamic stall to me. A bit pedantic, but that is pretty much what a stall is. The nose might not drop and the aircraft might be controllable, but the wing is still stalled.
No, that's not quite right. A stall means that the air has separated from the wing and the wing is no longer flying. The huge vortex created when a delta wing is at high AoA actually causes the air to stick to the top of the wing, and this maintains control.
I used to fly a 48" delta winged glider that had a catapult launch. The catapult would launch it at about 120mph. I could fly to about 300 feet in a nice vertical arc, but as soon as I yanked back on the elevons, the rather light plane would turn sharply and slow down significantly, due to the very effect discussed. A non delta wing would have been unable to maintain airflow over the wing because the high AoA (20-25 degrees) would have been far more than the 12-15 degrees that straight or swept wing can take.
> A stall means that the air has separated from the wing and the wing is no longer flying.
That's not quite right either. A wing doesn't stop flying when it stalls, i.e. when the angle of attack exceeds the critical angle of attack. What does happen is that the coefficient of lift starts to decrease instead of increase what increasing angle of attack, and with sufficient angle of attack the coefficient of lift can become too low indeed.
A wing in stall can be flown, but it's tricky. Controls are inverted, natural stability of the plane doesn't really work anymore. It's not a situation you normally want to be in, but the plane does not suddenly fall from the sky.
It's true. A stalled wing still has aerodynamic properties that can be used to keep it from falling out of the sky immediately, but in the sense of the OP's comment about a delta being stalled, my definition as used to explain the difference between the two holds up.
The article referenced also talks about control inversion, interestingly. So yes, a stalled wing can be "flown" but not in the same way that the original question was referencing.
Where does the article mention control inversion? I don't see any mention of it. We're not talking about adverse yaw thing, we're talking about the coefficient-of-lift-decreases-with-increasing-angle-of-attack thing.
That's not the case for a delta wing in the regime that the article talks about. Increasing the angle of attack still increases the coefficient of lift.
It forms a single vortex over each wing, coefficient of lift still increases with angle of attack. It's more like moving the wingtip vortex near to the nose of the plane. There is a much higher 'true stall' angle of attack where flow separates and lift reduces.
