How to make a micro-drone

Micro-drones: Twice better thanks to intentionally bad wings

A team of scientists has designed wings with which any normal passenger aircraft would stay like a stone on the ground. Instead of guiding the air flow over the surface as gently and without interruption as possible, they let it tear off at the pointed leading edge of the wing. Amazingly, the team writes in the journal Ā»Science RoboticsĀ«, this ultimately leads to a more energy-efficient and more stable flight.

However, this only works with wings that are well under one meter in size, i.e. with so-called micro-UAVs or micro-drones. According to Matteo Di Luca's team from Brown University in Providence, Rhode Island, the latest batteries keep the aircraft, which weighs just a few grams, in the air for about half an hour. Thanks to its new wings, such an aircraft could fly for up to three hours, at least ideally. Based on their wind tunnel tests, the group estimates that under realistic conditions the flight time would still drop to an impressive one and a half hours or more.

They copied the structure of the wings from nature. Insects and other small fliers would have inspired them to disregard the aerodynamic laws that apply on a large scale. Because in the world of the small, completely different influences would have an effect on an airplane. For example, you would be constantly tossed about by gusts of air that a normal-sized airplane does not mind.

The trick with the controlled stall prevents the susceptibility to failure, the scientists found. Specifically, the pointed leading edge ensures that turbulence occurs in the front half of the wing. These seem to make the aircraft less sensitive to the random gusts. At the rear end of the wing, the scientists attached a rounded rail similar to a landing flap. It catches the swirled air flow again and thus provides buoyancy.

The trick, however, reduces the efficiency of the wing, write the researchers. Which is why the wings would have to be longer than conventional mini drones. Dispensing with the classic wing profile also makes this easier: the wings could be thicker and correspondingly more stable without any problems, and you gain more space for batteries - and thus an even longer flight time.