Integrating Solar Cells Into Flapping Wing Air Vehicles for Enhanced Flight Endurance

Abstract

Flapping wing aerial vehicles (FWAVs) may require charging in the field where electrical power supply is not available. Flexible solar cells can be integrated into wings, tail, and body of FWAVs to harvest solar energy. The harvested solar energy can be used to recharge batteries and eliminate the need for external electrical power. It can also be used to increase the flight time of the vehicle by supplementing the battery power. The integration of solar cells in wings has been found to alter flight performance because solar cells have significantly different mechanical and density characteristics compared to other materials used for the FWAV construction. Previously, solar cells had been successfully integrated into the wings of Robo Raven, a FWAV developed at the University of Maryland. Despite changes in the aerodynamic forces, the vehicle was able to maintain flight and an overall increase in flight time was achieved. This paper investigates ways to redesign Robo Raven to significantly increase the wing area and incorporate solar cells into the wings, tail, and body. Increasing wing area allows for additional solar cells to be integrated, but there are tradeoffs due to the torque limitations of the servomotors used to actuate the wings as well changes in the lift and thrust forces that affect payload capacity. These effects were modeled and systematically characterized as a function of the wing area to determine the impact on enhancing flight endurance. In addition, solar cells were integrated into the body and the tail. The new design of Robo Raven generated a total of 64% more power using onboard solar cells, and increased flight time by 46% over the previous design. They were also able to recharge batteries at a similar rate to commercial chargers.