Feasibility of Laser Power Transmission to a High-Altitude Unmanned Aerial Vehicle

Solar-powered unmanned aerial vehicles (UAVs) have demonstrated interesting capabilities for high altitude and long endurance. However, current solar-powered UAVs are extremely light and fragile and have small payloads. This report examines whether a laser-beam-powered UAV could be scaled up to a sufficient size to be of practical interest, and identifies some of the concept's limiting factors. The report focuses on the physical parameters of flight — altitude, range, persistence, and power — that are possible for a laser-photovoltaic aircraft that uses current technology. Commercially available lasers and photovoltaic cells could provide a UAV with performance characteristics that are beyond the performance envelope of existing air vehicles, especially sustained extremely high altitude. If the laser is beamed from the ground or from a ship, the UAV is closely "tethered" to the beam source, although it could fly at extremely high altitudes over it, and clouds could interrupt the beam and force the UAV to descend below the cloud layer from time to time. If the laser were placed on a conventional aircraft, however, the UAV would be powered by an air-to-air transmission; the "tether" to the power source could be much longer (hundreds of kilometers), and clouds would no longer be a likely threat. The performance niche opened by this concept could be worth further consideration if an important mission were identified for an air vehicle with ultra-high operating altitude and moderate persistence and payload.