I’ve learned a lot of painful lessons from over a decade of designing, building, and cursing at dozens of RC aircraft. I didn’t know much when I began but since then I’ve studied aircraft design, got my HAM radio license, paragliding certified, and begun private pilot lessons … It’s important to understand when I began creating these things, there weren’t any consumer level drones with these features:
Design objectives:
Compact: Foldability such as nesting arms
Control: such as Tilted rotors to increase yaw authority, rigid frame, sufficient distance and shielding for GPS-mag in autonomous flight.
Robustness: compliance during crashes and Field serviceability such as identical arms, common hardware.
These are the fraction of the airframes that didn’t get cannibalized into newer iterations. I’ve built several dozen different versions of these things.
Some exceptionally ugly foamy planes. At least they hold up in crashes when learning to fly
I studied controls engineering. I’ve started programming my own flight controllers to get my hands dirty beyond the theory. In this particular project, it was a challenge to define the transfer function of the propeller&motor system. I used high speed video to determine the lag of the propeller when a PWM step function was applied.
(Reflections: Nowadays I think I would use a load cell to determine thrust from PWM and matched transfer function to that. Additionally I was using an Accelerometer to sense the tilt angle- since there were no translational accelerations for this setup, it wasn’t an issue, but best practice would be to use something like a gyro or encoder for more direct angle measurement.
I’ve learned from a LOT OF MISTAKES. It’s been good to have a sense of humor to keep at it in such failures.