A stall is a physical phenomenon in fluid dynamics where the airfoil stops generating lift when moving through the air at angles above the critical angle of attack. As airfoils generate lift by the resultant force arising from the airflow around its upper and lower surfaces, the airflow needs to be smooth and continuous for a continuous lift. When the angle of attack increases, the airflow separates from the upper surface and abruptly reduces the lift generated.
Frequently Asked Questions
How does an aircraft recover from the stall?
A stalled aircraft can be recovered to normal flight be reducing the angle of attack below the critical angle of attack, i.e. by pitching down the aircraft.
What is a deep stall?
A deep stall is a type of stall where an aircraft's recovery from the stall is highly unlikely due to the loss of controls to pitch down the aircraft. This happens in configurations where a T-tail is involved. When such aircraft enters a stall, the wing at a high angle of attack and the wake from the separated turbulent flow blocks any flow to the tailplane and the elevators. This leaves the elevator ineffective to the pilot's inputs.