Passive-tilting rotors shown to boost drone speed and efficiency

Ordinarily, quadcopter drones have to tilt their front end downward when flying forward, increasing their frontal area and thus increasing drag. An experimental new drone gets around this problem, by only tilting its rotors.

Developed by a team at the University of California – Berkely, the aircraft is known as QUaRTM, which stands for “QUadcopter with an unactuated Rotor Tilting Mechanism.” It features a rectangular body with four arms, each arm incorporating a rotor/motor module at the end. Instead of being rigidly joined to the main body, the arms are all connected to it via spring-loaded hinges.

In this setup, when modest amounts of thrust are produced, the springs hold the rotors horizontally in line with the body. Once a high enough level of thrust is produced, however, the rotor arms overcome the force of the springs, temporarily tilting into the forward flight direction by up to 20 degrees relative to the rest of the drone.

This allows the copter to move forward while keeping…