Novel Control of a Propeller Driven Rotor as a Swashplateless System

A novel method of swashplateless rotor control is presented for a propeller driven rotor. A propeller driven rotor consists of small electric motors and propellers attached to the rotor blade to spin the main rotor. The control methodology involves varying the propeller RPM around one rotor revolution to generate rolling and pitching moments for the main rotor. A small test stand was fabricated using 2.7 ft diameter 3D printed rotor blades to investigate this concept with various tip propeller geometries. The test stand was utilized to characterize changes in motor commands to rotor rolling and pitching moments. Next, in an effort to reduce the required power for the propeller driven rotor, the propeller placement along the rotor blade span was varied. Placing the propeller at the mid span location on the main rotor blade resulted in a significant reduction of 50% in the electrical power loading coefficient CPe/σ compared to a tip propeller placement. Finally, the propeller driven rotor control strategy was experimentally compared with a 6 ft diameter, shaft driven rotor that used a conventional swashplate system. A comparison of the control authority derivatives for the different configurations showed that the propeller driven rotor control strategy resulted in a similar amount of control authority as a conventional swashplate system.