Motor drives and motors

For drones — KV and size

KV — RPM per volt. Lower KV = more torque, larger propeller. Motor size (2212, 2806) — stator diameter and height.

For servos — torque

Measured in kg·cm. 10 kg·cm = 10 kg at 1 cm arm. Choose 30-50% margin over calculated load.

Operating voltage

Motors 2S-6S (7.4-22.2V), servos 4.8-8.4V. High-voltage (HV) servos are more efficient but cost more.

ESC for motor

ESC current must exceed motor peak current. Protocols: PWM, OneShot, DShot. BLHeli_32 for modern drones.

Cooling

Motors heat under heavy load. Check duty cycle and operating temp. Metal servos dissipate heat better.

Gearbox

Plastic gears — cheaper, quieter. Metal — stronger, for high-load applications.