Assessing the Longitudinal Handling Qualities of the Flying-V by Pilot Evaluation

Abstract

The handling qualities of an aircraft are an important aspect in aircraft design, especially for novel configurations. The Flying V is a flying wing passenger aircraft designed to transport about 300 passengers. The handling qualities of such a new configuration aircraft are to be investigated before the aircraft can continue in its design process. The first step is to investigate the longitudinal handling qualities of the Flying V in cruise conditions. The handling qualities are heavily affected by the geometry of the aircraft, which has no tail and has a shorter arm to the elevons for the pitch control. These two main differences do not affect the pitch angle control negatively, which is the focus of conventional handling qualities evaluations, but have a strong effect on the flight path angle. This effect is a non-minimum phase response due to the large change in lift needed to generate the pitching moment. To test this flight path angle behaviour, a new evaluation of the handling qualities is implemented which uses flight path angle tracking.
Two control allocations were created: one where both inboard and outboard elevons deflect in the same direction, and one where the change in lift the elevons generate is countered by deploying the inboard and outboard elevons in opposite directions. The longitudinal handling qualities in cruise conditions were investigated by pilot opinion in a moving base simulator. Three experiments were conducted: a traditional pitch experiment, the novel flight path angle experiment, and the latter experiment using the second control allocation.
The pilots indicated the pitch attitude control to be Level 1 handling qualities, while the normal control allocation flight path experiment was Level 2. The new control allocation improved the performance of the pilots during the experiment, but the lowered control authority was too much for most pilots to rate it at Level 1.