CoulombFly: Miniature drone weighs just 4 grams, can fly forever with sunlight
Chinese researchers have developed a tiny, solar-powered micro flying robot with an electrostatic drive that can fly forever in sunlight.
(Image: Mingjing Qi et al.)
Chinese scientists from the Department of Energy and Power Engineering at Beihang University in Beijing have developed a solar-powered micro drone called "CoulombFly", which is designed to fly freely and continuously in sunlight. This is made possible by a highly efficient electrostatic drive and ultra-light solar cells, as the team reports in the journal Nature.
Flying robots, also known as micro aerial vehicles (MAVs), could be used in the future for environmental monitoring or rescue missions. Until now, however, their flight time has been limited to a few minutes, as factors such as friction greatly reduce the efficiency of conventional electromagnetic motors when they are small.
Although there are already approaches for alternative drives, these require ground systems for energy supply and cannot fly freely. Solar energy would be one solution, but no solar-powered MAV has yet succeeded in flying autonomously and continuously in natural sunlight.
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Electrostatic drive for efficiency
CoulombFly consists of a rotor and a stator with eight pairs of electrodes that are alternately positively and negatively charged. Brushes are attached to the electrodes, which transfer charge to the rotor blades.
When a high DC voltage is applied to the electrodes, they generate electrostatic fields that drive the rotor. When turning, the rotor blades alternately pass positive and negative electrodes, which maintains rotation. This in turn drives the propeller and lifts CoulombFly into the air.
According to the researchers, at 30.7 g W-1, this drive achieves a significantly better lift-to-power ratio than comparably sized MAVs. Unlike most electromagnetic motors, it also does not heat up, which could increase the service life of the components.
Ultra-light solar cells supply the drive with energy
The energy supply is provided by two ultra-light high-performance solar cells. With a total mass of just 4.21 grams, CoulombFly is lighter than many paper airplanes and weighs only 1/600th of the weight of the lightest solar-powered aircraft to date, according to the researchers.
According to the publication, CoulombFly was able to achieve sustained free flight under natural sunlight conditions with an irradiance of 920 watts per square meter in tests. However, CoulombFly does not yet have a mechanism for controlling the direction of flight and requires vertical rails for guidance. Sudden changes in brightness can also disrupt the solar supply. However, the researchers are confident that they will be able to solve these problems.
The ultimate goal is "to build a super-strong flying vehicle that is about the size and weight of a mosquito and has a wingspan of less than one centimeter," IEEE Spectrum https://spectrum.ieee.org/smallest-drone quotes Mingjing Qi, one of the researchers involved and a lecturer in energy and supply engineering at Beihang University in Beijing.
(vza)