Engineers at China’s Beihang University, in collaboration with the Center of Advanced Aero-Engine, have developed a micro-aerial vehicle (MAV) capable of flying using direct sunlight.

With the potential for conducting high-altitude surveillance missions, the team is working to develop sun-powered drones that will eventually be launched much like satellites, but at significantly lower altitudes.

Source: Nature (2024). DOI: 10.1038/s41586-024-07609-4

According to the developers, such drones would be small in scale, thereby making it nearly impossible to track or shoot down during war, for instance.

The researchers explained that current iterations of MAVs are limited in flight time to about 30 minutes, with the smallest, dubbed ultralight MAVs, capable of flying for just 10 minutes. This is largely due to the electromagnetic motors used to power them that rely on electricity from a solar panel. However, smaller electromagnetic motors tend to be less efficient and the smaller the drone, the smaller the surface area of the solar panel.

To overcome these obstacles, the team employed an electrostatic motor that powers a rotor via electrostatic fields. As such, they were able to construct a motor weighing merely 1.52 grams.

To construct the motor, the team nested a circle of electrode plates around a spinning cylinder that hosts 64 rotor slats. As they spin, the team explained, the edges of the plates brush against the rotor slats. Meanwhile, the remaining components of the drone were created by placing two solar cells underneath the motor connected by a spanner and a helicopter-like rotor above the motor connected by a thin axis.

When exposed to sunlight, the solar cells on the drone produce power, thereby spinning the motor, which subsequently pushes the upper rotor, pulling the drone up into the air and holding it there. During trials, the drone sustained flight for at least an hour.

An article detailing the solar-powered drones, “Sunlight-powered sustained flight of an ultralight micro aerial vehicle,” appears in the journal Nature.

For more on this technology, watch the accompanying video that appears courtesy of Nature.