Flexible Mass-Balance Arms and Control-Surface Flutter

Abstract

This paper records a theoretical investigation into the effect on aileron flutter of flexibility in the aileron mass-balance arm. It is shown that this flexibility can affect both wing-aileron and aileron-tab flutter, but each is affected differently. In wing-aileron flutter, mass-balance arm flexibility gives rise to ternary flutter and has a powerful stabilizing effect when the mass-balance natural frequency approaches the flutter frequency. In aileron-tab flutter, the mass-balance flexibility serves to produce an aileron overtone mode equivalent in effect to a rigidly mass-balmlced aileron mode of the same frequency. When this frequency is sufficiently high aileron-tab flutter results. The fundamental aileron mode (the lower frequency normal mode of the aileron and its mass-balance weight) has no significant effect on the flutter.