  Motivated by a winged seed, which takes advantage of a wing with high angles
of attack and its associated leading-edge vortex to boost lift, we propose a
powered 13.8-gram aerial robot with the maximum take-off weight of 310 mN (31.6
gram) or thrust-to-weight ratio of 2.3. The robot, consisting of two airfoils
and two horizontally directed motor-driven propellers, revolves around its
vertical axis to hover. To amplify the thrust production while retaining a
minimal weight, we develop an optimization framework for the robot and airfoil
geometries. The analysis integrates quasi-steady aerodynamic models for the
airfoils and the propellers with the motor model. We fabricated the robots
according to the optimized design. The prototypes are experimentally tested.
The revolving-wing robot produces approximately 50% higher lift compared to
conventional multirotor designs. Finally, an uncontrolled hovering flight is
presented.
