Theory of Aerofoils on which occur bubbles of stationary air

Abstract

Spoilers, split flaps and sometimes (with thin aerofoils) incidence alone cause the flow to separate from the aerofoil surface. This flow often reattaches to form a closed bubble of virtually stationary air at a fairly constant pressure. The paper sets out a mathematical theory of the subsonic inviscid flow external to the bubble whose position is assumed. The influence of the bubble on the lift and moment coefficients is calculated and some comments are made about the stalling of thin aerofoils.