Chinese team’s solar-powered drone is lighter than paper plane, offers sustained flight

[Nan Yang]

The ultralight micro aerial vehicle, dubbed the CoulombFly, is the product of six years of research. Photo: Handout

Chinese team’s solar-powered drone is lighter than paper plane, offers sustained flight​

• Article in Nature cites breakthrough by Beihang University team as capable of forging ‘a path to new kinds of tiny aerial vehicles’

Dannie Peng in Beijing
Published: 6:41pm, 19 Jul 2024

Chinese researchers say they have created the world’s smallest and lightest solar-powered drone – 600 times lighter than any in existence.

The Beijing-based team overcame long-standing motor efficiency and power issues to create the palm-sized device, which they said could greatly expand the potential of such micro aerial vehicles, or MAVs.

Weighing just over 4 grams (0.14oz) and with a wingspan of 20cm (about 8 inches), the drone is lighter than a paper plane and 1/600th the weight of the lightest solar-powered MAV, according to its developers from the school of energy and power engineering at Beihang University.

Peer-reviewed journal Nature welcomed the breakthrough, saying in an independent article on Wednesday that it “could forge a path to new kinds of tiny aerial vehicles”.

The same issue also carried a paper from the developers explaining their findings.

According to the paper, the small size, lightness and high mobility of MAVs allows them to be used in a wide range of applications – from environmental rescue and monitoring to information collection in confined spaces.

However, a major hurdle is the limited flight duration.
The problem gets worse for even smaller, ultralight MAVs – those weighing less than 10 grams typically have a flight time of under 10 minutes.

For example, an ultralight drone launched by the Dutch company TRNDlabs in 2015 – then the world’s smallest – weighed only 7 grams but had a flight time of just 7 minutes.

Qi Mingjing, a professor at Beihang University and a corresponding author of the paper, explained that existing MAVs generally use electromagnetic motors as actuators – the component that helps a machine achieve physical motion by converting energy.

However, the efficiency of actuators decreases significantly as the vehicle becomes smaller.

They still require bulky ground power systems to take off, preventing the rotorcraft from flying freely.

Other types of propulsion are being tested, with researchers pinning their hopes on sunlight as an ideal external energy source to achieve sustained flight.

But the question is: how to ensure that the solar panels on the MAV are able to provide enough power?

The issue is similar to why electric vehicles are not powered by solar panels, because the power they provide would not be enough to move the car, Qi said.

Its creators say the CoulombFly was able to maintain sustained flight in an hour-long endurance test without any drop in performance. Photo: Handout

His team worked to overcome the challenge for six years before finally developing their tiny lightweight drone, which is propelled by a new, more efficient electrostatic motor and powered by very light solar panels.

The team named the drone “CoulombFly” – as it is operated by “coulomb force”, or the attraction or repulsion of particles or objects because of their electric charge.

“We have come up with a new actuator principle that allows the machine to fly with substantially lower power consumption under the same conditions, so that the same piece of solar cell can now provide enough power,” he said.

In an hour-long endurance test, the CoulombFly maintained sustained flight throughout the process without showing any degradation in performance.

But this ultralight drone, as a prototype, is still two to three years away from use in real-life situations, Qi said.

“We have proposed a new type of flying vehicle through the breakthrough in the underlying principle, but a lot of technical difficulties will still need to be overcome before the achievement is turned into practical application.”