With a current global market value of $25.3 billion, which is expected to increase to $133.6 billion by 2033, the drone industry is one of the fastest-growing industries worldwide. Data released by the Federal Aviation Administration reveals that as of August 2024, there are 785,827 drones registered in the United States. Of those registered, 390,027 are under commercial licenses, while 388,838 are for recreational use.

These drones are being used in countless fields, covering everything from search and rescue to education, data collection, agriculture, photography, deliveries, and more. Though the ways drones are used differ greatly, they all share one major limitation: flight time. Unless powered by a tether, a drone requires an onboard battery to operate. The three typical types of batteries used in drones are lithium-ion, lithium polymer, and nickel-cadmium. The battery is usually the heaviest part of a drone. The larger the drone, the larger the battery needed. The larger the battery, the heavier the drone, which impacts flight time.

Other factors that impact flight time include wind resistance and moisture in the air, which add more resistance and weight for the battery to work against. Typically, a drone can fly between 20 to 30 minutes on a fully charged battery. A good battery generally needs to be completely replaced after approximately 200 hours of use. Most drone operators keep spare batteries on hand to extend the drone’s usage beyond the limit of a single battery charge. However, a group of researchers from Beihang University in China have been working on a prototype drone with unlimited flight time.

Called the CoulombFly, this drone is a micro-drone that weighs only 4.21 grams, has a 20-centimeter wingspan, and is about the size of a hummingbird. What makes this drone truly unique is that it harnesses solar energy, potentially allowing it to fly indefinitely during daylight hours. The drone is named after Coulomb’s Law, which relates to the amount of force created by the interaction of similar or opposite particles. Utilizing this principle, the team, led by Professor of Energy and Power Mingjing Qi, designed a dual-ringed electrostatic motor.

“Electrostatic motors are shaped like lanterns with a ring of electrode blades around them,” explained Peng Jinzhe, one of the researchers on the project. “These blades follow the principle that like charges repel each other, and opposite charges attract each other. The adjacent blades have opposite charges, so the moving electrode blade is repelled by the blade on its right side and attracted by the blade on its left side. This generates lift, enabling the entire device, including the battery, circuitry, motor, and propellers, to fly.” The blades gather solar power, converting it into 6,000 to 9,000 volts. The blades are made from lightweight carbon fiber covered in aluminum foil, which reduces excess heat output.

This allows the drone to operate with a tiny solar panel rather than a heavy battery source. “The high efficiency and low power consumption of the motor allow us to power the vehicle with a very small solar panel,” Professor Qi said. “We have managed to get a micro-aerial vehicle to fly using natural sunlight for the first time. Before this, only very large, ultralight aircraft could achieve this.” While the drone does work, Professor Qi clarified that they are still in the beginning stages of development. “My ultimate goal is to make a super-tiny flying vehicle, about the size and weight of a mosquito, with a wingspan under 1 centimeter,” Professor Qi continued. “But it can’t fly on its own power yet. I believe that with the ongoing development of microcircuit technology, we can make this happen.”

Once this happens, Professor Qi envisions these micro-drones being beneficial in a number of fields. One area he is particularly excited about is search and rescue. Drones that can fly for more than 20 to 30 minutes could prove critical in such missions. By harnessing solar energy and leveraging innovative electrostatic motors, researchers like Professor Qi and his team are pushing the boundaries of what’s possible in drone technology. As these advancements continue, the potential applications for such drones are vast, further cementing the lasting impact of the drone industry.

Previous Drone News: