Theoretical and Experimental Investigation of Aeroelastic Rotorcraft-Pilot Coupling

This paper presents and discusses the results of a study focused on the biomechanical behavior of human subjects holding the collective control inceptor in a flight simulator. The reported experimental campaign was conducted at the HELIFLIGHT simulation facility of the University of Liverpool as part of the EC sponsored project ARISTOTEL. The flight simulation model's motion was restricted to only the heave axis but was augmented to include an elastic mode of vibration in addition to the rigid heave mode. It is this augmentation that represents an element of novelty in the investigation. Four different pilots flew a number of alternative model configurations whose structural parameters had been varied. The placement of structural modes with a frequency of approximately 3.5 Hz resulted in observable unstable pilot-vehicle interactions. It was found that the presence of collective friction alleviates but does not completely eliminate this phenomenon. The models used for the study were very simple representations of reality. As such, the scalability of the results to numerical models representative of the structural dynamics of flexible helicopter airframes is also discussed.