High-Speed Hover-Capable Morphing Micro Air Vehicle

The design, fabrication, and testing of a hybrid micro air vehicle capable of morphing between a high-hover-endurance rotary-wing mode and a high-cruise-speed fixed-wing mode is described. The micro air vehicle can efficiently perform a mission comprising outdoor flight to a target, followed by indoor surveillance and a return to the launch point. In addition, the micro air vehicle can function as a multirole platform, capable of flying exclusively as a fixed-wing or a rotary-wing vehicle. The key design drivers were 1) minimizing power required to hover, 2) ensuring static longitudinal stability in fixed-wing mode, and 3) minimizing the change in geometry between flight modes. Configuration trade studies were performed using blade element momentum theory for the rotary-wing mode and modified lifting-line theory for the fixed-wing mode. Design drivers for the rotary-wing mode and fixed-wing mode were often conflicting, and the selection of the final vehicle planform was primarily based on longitudinal static stability in fixed-wing mode. Two proof-of-concept prototypes with identical geometries, one for each flight mode, were constructed using off-the-shelf components and tested. Analytical predictions were validated by experimental measurements on the prototype vehicles. The final vehicle design is a flying wing with aft-swept, negatively twisted wings, having a wingspan of 394 mm and a mass of 85 g. The cruise velocity is 13.2 m/s, and the power required to hover is 11.6 W.