Lift and Measurements in an Aerofoil in Unsteady Flow

A wind tunnel is described which is capable of producing both “transverse” and “streamwise” gusts. An account is given of the lift and pressure fluctuations measured on an isolated aerofoil tested in the tunnel. The response to a transverse gust compares well with Kemp’s (1) theory although the pressure distribution is not as predicted. The results suggest that the wake behavior and in particular the existence of a separation region can in practice seriously affect the validity of applying the now classical unsteady vortex theory.