A Practical Approach to the Problem of Stall Flutter

A method is presented in this paper whereby the real part of the dynamic moment derivative may be obtained from a flutter test on a single blade oscillating in torsion alone in the stall region. These data may be used to predict the critical flutter velocity and frequency of a blade with the same geometrical properties oscillating with two degrees of freedom and having arbitrary elastic and inertial properties. It is possible that the present method can be used to predict the flutter speed and frequency of a cantilever blade by either a representative section or a Rayleigh-type analysis.