Long flight durations are highly desirable to expand mission capabilities for unmanned air systems and autonomous applications in particular. Flapping wing aerial vehicles are unmanned air system platforms offering several performance advantages over fixed wing and rotorcraft platforms, but are unable to reach comparable flight times when powered by batteries. One solution to this problem has been to integrate energy harvesting technologies in components, such as wings. To this end, a framework for designing flapping wing aerial vehicle using multifunctional wings using solar cells is described. This framework consists of: (1) modeling solar energy harvesting while flying, (2) determining the number of solar cells that meet flight power requirements, and (3) determining appropriate locations to accommodate the desired number of solar cells. A system model for flapping flight was also developed to predict payload capacity for carrying batteries to provide energy only for power spikes and to enable time-to-land safely in an area where batteries can recharge when the sun sets. The design framework was applied to a case study using flexible high-efficiency (>24%) solar cells on a flapping wing aerial vehicle platform, known as Robo Raven IIIv5, with the caveat that a powertrain with 81% efficiency is used in place of the current servos. A key finding was the fraction of solar flux incident on the wings during flapping was 0.63 at the lowest solar altitude. Using a 1.25 safety factor, the lowest value for the purposes of design will be 0.51. Wind tunnel measurements and aerodynamic modeling of the platform determined integrating solar cells in the wings resulted in a loss of thrust and greater drag, but the resulting payload capacity was unaffected because of a higher lift coefficient. A time-to-land of 2500 s was predicted, and the flight capability of the platform was validated in a netted test facility.

Biological creatures demonstrate tremendous feats of maneuverability and dexterity. Some of these feats are achieved by intelligent usage of mass and inertia. For example, lizards use their tail mass and inertia to change body pose during jumping to self-right in mid-air. In a similar fashion, having shown passive mass position effects during flight tests of both flapping only and propeller-assisted flapping platforms, usage of an actuated reaction mass is proposed as a means of improving the maneuverability of a propeller-assisted flapping wing aerial vehicle. A simplified model for equations of motion, utilized successfully for autonomous diving, is presented and adapted to describe the aerodynamic forces on the wings and other surfaces. A model to approximate the change in the center of mass to be used with the equations of motion is also described. A design using a linear actuator in concert with the platform battery as a reaction mass system was prototyped and flight tested. Using the prototype design, flight characteristics for improved maneuverability were demonstrated via both video footage and data gathered by an inertial measurement unit during the same flight.