Ultra-light electrostatic VTOL drone flies indefinitely in sunlight
Researchers at China’s Beihang University have developed CouloumbFly, a palm-sized miniature rotorcraft that weighs just 4.21 g, or about as much as four paperclips. The drone can fly all day if the sun is shining, lifting its own mass without any power besides sunlight.
The key to its remarkable VTOL endurance is an insanely lightweight electric motor driving a top rotor. Effectively, flappy-looking foil-covered tabs hanging around the outside of the airframe are positive and negative stator plates of an electrostatic motor, while the rotor is a fence-like series of 64 thinner vertical tabs.
When a rotor blade contacts a brush on an electrode plate, it forms a capacitor, determining how much charge it can transfer. The charged rotor blade moves towards the next electrode plate, ensuring consistent driving torque for continuous rotation.
The drone has two whisper-thin solar panels generating about 4.5 volts, which is fed through a voltage multiplier and transformer to step up the power for the electrostatic motor.
In testing, the drone flew for an hour without power diminishing before a mechanical failure brought it back down. The researchers hope to increase its payload and upgrade it with flight control systems, enabling sustained surveillance, communications, and search-and-rescue operations.+
+Source: https://newatlas.com/drones/solar-electrostatic-drone/