Hackaday

A maker known as rctestflight explores using variable-pitch propellers on a quadcopter to address the efficiency problem caused by high disk loading. By borrowing technology from fixed-wing aviation, the pitch-change mechanism allows faster thrust control than throttling large, high-inertia motors. The 3D-printed variable-pitch props were tested with a belt drive system and showed improved flight performance and efficiency over conventional RPM-based control. The experiment even demonstrated near-autorotation capability, though the drone lost control when throttle was cut. The conclusion is that while the concept works, the complexity involved makes building a helicopter a more practical alternative.

Variable-Pitch Propellers For More Efficient Quadcopter