Sunlight-powered sustained flight of an ultralight micro aerial vehicle

Abstract The limited flight duration presents a significant obstacle to the widespread application of micro aerial vehicles (MAVs)1-3, especially for ultra-lightweight ones weighing less than 10 grams, generally having a flight endurance of no more than 10 minutes1,4. Sunlight power5-7 is a potential alternative to improve the endurance of ultra-light micro aerial vehicles, but owing to the restricted payload capacity of the vehicle and low lift-to-power efficiency of traditional propulsion systems, previous studies can not achieve untethered flight or sustaining hovering of MAVs powered by natural sunlight 8,9. To address the challenges, here we present a novel electrostatic-driven propulsion system with ultra-low power consumption (137 mW) and high lift-to-power efficiency (30.7 g·W-1) to realize the first sunlight-powered hovering of a micro aerial vehicle (with a total lift-to-power efficiency of 7.4 g·W-1) under natural sunlight conditions (920 W·m-2). The vehicle mainly consists of an electrostatic-driven propulsion system and an ultra-light kilovolt power system, with a total mass of 4.21 g, which is 1/600 of the existing lightest sunlight-powered aerial vehicle capable of hovering6. The sunlight-powered aerial vehicle we present is the first micro aerial vehicle to achieve untethered flight and sustained hovering under natural sunlight conditions (as opposed to artificial light sources 8,10 and wireless radiofrequency11).