Stalled flying is a subject which at the present time is occupying the thought and time of aerodynamic experts all over the world. It is still more or less in the experimental stages, but its value to flying, and more especially commercial aeronautics, is now almost universally recognised.

It has hitherto been possible to fly an aeroplane at all angles of incidence from the no-lift angle up to the burble point of the aerofoil section employed for the wings. The burble point on the lift curve marks the change-over from streamline to turbulent critical airflow, and at this angle the aeroplane will stall. The machine sinks, and what is more dangerous, becomes unstable laterally so that the pilot loses power over its orientation. A spin then usually ensues.

It may be as well to state here that the only way of defining the change-over point from normal to stalled conditions is by means of the stalling angle.