I built a drone with only one motor [video]
A YouTube maker showcases a single-motor, single-rotor drone that uses a clever hinge, encoder, and rapid torque modulation to vary blade pitch electronically, eliminating the need for a traditional helicopter swashplate. Commenters highlight how this fits into the broader field of underactuated robotics, compare it to existing RC and academic prototypes, and debate its practicality for payloads, efficiency, and military use. Many see it less as a near-term replacement for quadcopters and more as an inspiring, technically sophisticated experiment that pushes control algorithms to replace mechanical complexity.
Core engineering concept
- Single-motor, single-rotor drone uses a flexible hinge, magnetic encoder, and rapid torque modulation to vary blade pitch as it spins.
- This replaces a traditional helicopter swashplate and pushes complexity into software and control algorithms instead of mechanics.
- Commenters are impressed that pitch can be controlled via tiny speed changes at very high RPM.
Relation to prior work & similar designs
- Similar virtual-swashplate ideas have appeared in RC helicopters and academic monocopter research.
- Coaxial-rotor helicopters with a single main motor are cited as simpler, more practical cousins.
- Related “one-motor” or underactuated designs mentioned: meltybrain combat robots, monocopters with thrust-vectoring fins, very small single-motor helicopters, and fixed‑wing planes with variable pitch propellers.
Practicality, scalability, and performance
- Many see it as an ingenious proof-of-concept but doubt current practicality, especially for larger scales or payloads.
- Major issues discussed:
- Airframe spins; yaw control is weak and partly sacrificed to maintain pitch/roll/altitude control.
- Payload attachment and center-of-gravity balance are very sensitive; offset masses quickly destabilize the system.
- Likely poor wind resistance and limited controllability compared to quadcopters or conventional helicopters.
- Small, high‑RPM props are less energy-efficient than large, slow ones; long endurance designs still favor big rotors or fixed wings.
- Some think a two‑motor or tail‑rotor variant could be more useful while preserving some simplicity.
Control, sensing, and vibration
- Discussion of using gyroscopes, magnetometers, and sensor fusion (e.g., Kalman filters) to stabilize flight, but yaw trade‑offs remain fundamental.
- High‑speed imaging of flutter and test stands are praised as good debugging tools; vibration sometimes traced to basic component choices (e.g., wrong props).
Underactuated robotics & theory
- Thread frequently links this to underactuated robotics, where clever dynamics and control substitute for extra actuators.
- Examples span combat robots, aircraft with fewer control surfaces, and hydraulically actuated machinery.
Ethics, warfare, and dual use
- Some speculate about military relevance (e.g., Russia–Ukraine drones) but most doubt this design’s suitability for payload-carrying or kamikaze roles.
- Broader concern over drones killing civilians and the drift from benign to military applications, alongside recognition that most technology is dual use.
Learning and inspiration
- Many find the project highly inspiring and ask how to acquire similar skills.
- Suggested paths: formal engineering study, obsessive tinkering, step‑by‑step hobby projects (e.g., standard drones), simulators, online courses on underactuated robotics, and using LLMs as tutors.
- Drone hobby tips include starting with small “tinywhoop” drones and simulators to build piloting skills safely.