The hover analysis considers pilot attitude and position control tasks in the presence of horizontal gusts. The effects of each of the stability derivatives on the difficulty of the control tasks and on the closed-loop gust responses are determined. It is clearly shown that the handling qualities studies of control sensitivity and angular damping must consider the influences of M sub u (or L sub v) and should include gust inputs. These conclusions are substantiated by previous variable-stability-helicopter experiments. The effects of vehicle size and geometry are investigated by several approaches. The key result of increasing size is found to be a reduction in M sub u and L sub v which can, in turn, lower the requirements for control power and damping. The handling qualities during transition of two vehicles, a tilt duct and a tilt wing, which were previously tested on a simulator are analyzed. It is shown that both trim control and perturbations about the trim conditions must be considered. In fact, part of the increased difficulty in landing transitions, in comparison with takeoff transitions, is due to more difficult trim control; the much more stringent position control requirements in landing are also a contributing factor.

"This report presents a series of discussions on selected topics related to the development of VTOL flying qualities criteria. The topics were chosen on the basis of their importance to flying qualities and the potential significance to the Air Force VTOL Integrated Flight Control System (VIFCS) program. The treatment given to the selected topics was aimed at identifying those areas that require further study and research within the scope of the VIFCS program. -- page iii.