A software engineer who’s also into drones and 3D printing has shared a single-motor drone that they built inside their home and tested on their bed. Joshua Bird shared a video of how they created it on YouTube, highlighting the unique technique they used to maintain controllability and stability. The design used a combination of a hinged propeller, rapid changes to the motor’s rotation speed, and a custom flight controller and motor controller firmware that allowed the motor to react to necessary changes in under 0.2 milliseconds.
Most rotary wing aircraft require a mechanism to counteract the torque generated by the motor or engine and to change its flight direction, typically with the use of a swash plate to change rotor disk attitude and a secondary propeller. While this method has been effective for decades, it has made rotary-wing aircraft heavier and more complex. This single-motor drone cut the need for a secondary mechanism by constantly adjusting the speed of the motor — speeding it up produces more reaction torque while slowing it down applies opposite reaction torque. This essentially turns into a balancing act between these two forces to reduce the torque on the drone body to a more manageable level.
The hinged rotor also relies on the same mechanism for directional control instead of relying on a swashplate. Each rotor blade sits on a 45-degree hinge that makes it pivot when the motor accelerates. As this happens, one blade pitches up to produce more lift, while the other blade pitches down, reducing lift. By accelerating and decelerating the motor as needed, Bird would be able to change the drone’s roll and pitch movement. It also combines this with the main rotor torque, motor adjustments, and the 3D-printed stabilizing fins to produce effective yaw control as well.
Latest Videos FromTom’s Hardware
This was the theoretical part — the majority of the build video focused on fixing issues, including the part where Bird built a high-speed camera using a Sony camera and a flash unit controlled by a microcontroller that gets its signals from the prototype drone’s motor controller and camera shutter. This home-made high-speed camera revealed that the drone’s propellers were too soft and had to be replaced with a 3D-printed version that used sturdier filament.
The creator had to launch several test flights from their bed, many of which resulted in a crashed drone and some wall damage as they fine-tuned the drone’s programming. Bird was eventually able to make the 3D-printed drone fly, although it was limited to the bedroom because of its fixed-base IR beacon navigation method. They said that they eventually want to add a linear camera to the build so that it could take off in other environments in the future.
While other researchers and engineers have built smaller, quieter drones, with China even revealing a mosquito-sized unit, Joshua Bird’s single-motor project is still a unique take on drones. But what made the YouTube video much more interesting is the problem-solving process and the solutions that came afterward. You can check out the complete video below and even start your own similar project by looking at the Single Propeller Drone GitHub repository.
