The hardest problem in this build is steering a flying machine that has only one motor, and Joshua Bird attacks it with a hinged propeller hub: accelerating blades lag and pitch in opposite directions, giving control over pitch and roll from the same motor that makes thrust. Torque pulses timed to the rotor angle, fired 300 times per second, do the actual steering. At nearly 20,000 RPM the rotor sweeps 20 degrees in the span of a 0.2 ms loop, so the cyclic pitch math runs directly on the motor controller in custom firmware. That timing budget looks like the crux of the whole design.
The hardware around the hub is well chosen. It is printed from PPA-CF on an enclosed Bambu Lab machine and carries miniature ball and thrust bearings, with rigid blades and a red flexible TPU shroud fitted with static anti-torque fins around the rotor. A brushless drone motor is driven by a moteus r4.11 servo drive with an integrated magnetic encoder, and a flight controller plus a handheld radio transmitter handle the flying side. A test stand was built along the way.
The strobe imaging setup stands out. A DSLR camera with synchronized flash photographs the propeller at precise angles, and those images exposed severe instability and blade flapping, which led to stiffer blades. Diagnosing a spinning rotor with a flash rig instead of guesswork seems like a genuinely clever method.
What remains open: several indoor flights ended in crashes against walls and furniture before a sustained indoor hover was finally achieved, and the drone body slowly spins as it flies. Heading comes from an external infrared lighthouse beacon seen once per revolution, correcting yaw drift.
Project by Joshua Bird. Watch it on their YouTube channel: