Design and Performance of a Quad-Shrouded Rotor Micro Air Vehicle

This paper describes the experimental investigation of a quad-shrouded rotor micro air vehicle and focuses on the hover performance improvements over a conventional unshrouded micro quad rotor. The effects of number of rotor blades, blade root pitch angle, and shroud diffuser length on aerodynamic performance were studied. The rotor diameter was 6.6 cm, it had a tip Re of 20,000, and the gross weight of the vehicle was 90 g, with a shroud weight fraction of 13%. With the optimized design, the power loading of the quad-shrouded rotor was about 15% greater than the unshrouded configuration. To completely evaluate the configuration, the performance of the vehicle in edgewise flow was investigated. The drag and pitching moment for the shrouded rotor was about 2.5 times greater than the unshrouded vehicle. However, control-moment measurements suggested that the edgewise gust tolerance was at least 4  m/s. The vehicle prototype was also successfully flight tested in hover using onboard feedback regulation. Base...