Adding VTOL Capabilities to a Fixed Wing UAV

As part of my junior project for aerospace engineering, my team explored adding vertical take-off/landing capabilites (VTOL) to a fixed-wing unmanned aerial system (UAS). In order to launch the UAS, the vehicle would either have to be hand launched or launched from a rail. Launching by hand poses significant risk due to the fact that the propellor for the aircraft is in the back. Launching by rail necessitates transporting large amounts of equipment that consumes valuable space for a flight test. A third option would be to add VTOL capabilities to the aircraft via adding a quadrotor system to the existing blended wing-body design. Once the vehicle is airborne, the flight controls system would switch modes and transition to conventional horizontal flight. In certain circumstances, flight modes could be blended to use the VTOL quadrotor propellers as well as the horizontal flight propeller on the back of the aircraft. Significant care was put into the design to properly size the battery, electronic speed controllers, motors, and propellers. The center of vertical thrust also needed to match the vehicle center of gravity to avoid adverse pitching moment that would require excess power to one side of the motors. The propellers needed to be far away enough from the body such that they did not significantly impact the freestream flow field over the wings and such that there was no body interference on the vertical thrust.