Abstract:
Free-flight models suspended by cable from a helicopter have been observed to experience unstable lateral pendular oscillations when towed above a certain speed. A simplified mathematical model of this configuration, considering only roll angle and lateral displacement of the model, has produced a result in agreement with flight observation. A criterion is given for the prediction of the critical speed, and design parameters are discussed which will help to increase the speed range at which tow is possible free from instability in this mode.
