RESPONSE AND STABILITY OF THE REMOTELY-PILOTED, CONSTRAINED X-HALE AIRCRAFT IN WIND TUNNEL

摘要

Formulations for the flight dynamics of flexible aircraft have been commonly applied to aircraft free to fly in the three-dimensional space, having all six rigid-body degrees of freedom. For risk reduction in the future flight operations of the X-HALE testbed at ITA, however, wind-tunnel tests of the remotely-piloted, four-meter-span configuration of the aircraft were performed. In the wind tunnel, the rigid-body translations were completely constrained, but the same was not valid for the rigid-body rotations, which could be conveniently left free or not with a proper selection of the connection between the aircraft and the wind-tunnel mount. In the present paper, in order to computationally assess the response and stability characteristics of the aircraft in the wind tunnel, we derive equations of motion for a constrained flexible aircraft with up to three rigid-body rotational degrees of freedom, mounted on an also flexible wind-tunnel strut. The numerical model has its value confirmed by the wind-tunnel tests in the predicted and observed roll-control reversal for anti-symmetrical deflections of the all-moving tails, and absence of reversal for aileron deflections.