Asymmetric Distributed Electric Propulsion VTOL Flying Wing: Conceptualization, Design and Flight Test

This paper presents aircraft concepts and designs which demonstrate that distributed electric propulsion can enable another paradigm in aircraft design: asymmetry. This attribute is leveraged upon to address operational issues relating to single motor failure. It is shown that the unique combination of minimum number of motors and a corresponding placement for which any one of the motors could fail, and full flight control in roll/pitch/yaw throughout VTOL and airplane modes can still be maintained, requires an asymmetric arrangement of six motors and their proprotors. This all-round redundancy is particularly important in applications where the aircraft, in the event of single motor failure during airplane mode cruise, needs to continue to be recoverable by VTOL mode landing in geometrically constrained environments (e.g. forested areas, small ships, urban locations etc.). In addition, the mechanical simplicity of the asymmetric arrangement enables the motors to be installed with a cant angle, thereby leveraging moment arm effects to enhance yaw control power. This is a much-needed enhancement for certain challenging operating conditions such as hovering or vertical landing in a crosswind. A small-scale prototype is designed, built and flight tested. Also presented is an example aircraft sizing of a larger scale variant to FAA Part 107 requirements, and it is shown that one area that can yield substantial improvement in loiter endurance is variable pitch proprotors.