I Built a Drone With Only One Motor

Summary

The video documents the design and flight testing of a drone controlled by one motor and a single articulated propeller. Unlike a quadcopter, it uses no separate motors for steering. The design is mechanically compact but requires custom motor-control and flight-control software.

How It Steers

A hinged propeller hub lets the blades change pitch as the motor accelerates and decelerates. By timing those changes to the desired direction, the drone creates uneven lift and tilts to steer. The first hub used two hinges set at 45 degrees; a later, more compact design used one hinge.

Motor Control and Timing

A conventional drone ESC lost synchronization during rapid torque changes because it estimates motor position from back-EMF. The creator replaced it with a moteus R4 servo controller, which reads motor position using a magnetic encoder. This enabled a six-inch propeller to spin at nearly 20,000 rpm while the motor changed speed about 300 times per second.

At that speed, a two-millisecond control delay amounted to roughly 20 degrees of rotation. The creator therefore rewrote the motor-control firmware to communicate directly with the flight controller and calculate commands onboard, reducing latency and eliminating an extra microcontroller.

Hub and Airframe Design

The redesigned hub was more than half the size of the earlier one. It used bearings to let the blade pivot under load and was printed from a strong, stiff PPACF filament. Additional masses on the hub helped keep the blades near neutral at high speed, reducing the risk of blade deformation and vibration.

The drone’s housing included ribs to resist motor torque. These reduce, but do not eliminate, gradual body rotation—avoiding the need for a tail rotor or servos.

Testing and Troubleshooting

Initial flight attempts crashed, and strong vibrations overloaded the accelerometers. To see what the fast-moving propeller was doing, the creator built a low-cost imaging setup: the motor controller triggered a flash at a specific propeller angle, synchronized with the camera shutter. The very short flash pulse effectively froze the blades in an image. The footage revealed that the blades were flexing under load; replacing them with stiffer blades eliminated the vibration.

After further crashes and component breakages, the creator mounted the drone on a weighted test stand and tuned its P-controller. Because the motor made a compass unreliable and the airframe continued to rotate, he added an infrared beacon and sensor. Custom flight-controller firmware used beacon detections to correct the drone’s heading estimate.

Result and Limitations

The drone eventually achieved stable, level flight and responded to control inputs. The creator describes it as a notably small, fast articulated-propeller drone, built around a single motor, a six-inch propeller, and electronics.

It still depends on an indoor infrared beacon, so outdoor operation is not yet supported. A future project mentioned in the video would use a linear camera sensor to help with heading and autonomous navigation.

The creator says the project’s code and 3D files are open source.

Reviews, Guides, or Tutorials

This is an engineering build-and-test demonstration rather than a product review or step-by-step tutorial. It explains the steering mechanism, motor-control changes, hub redesign, diagnostic camera setup, vibration fixes, and heading solution.

Main Speaker/Source

• Joshua Bird — creator and narrator; describes the design, tests, failures, and final flight results.