Propulsion Systems
The propulsion system converts electrical energy into thrust. Understanding motors and propellers is critical for optimizing drone performance and efficiency.
Motor-Propeller System Overview
Brushless Motor Theory
Brushless DC motors work via electromagnetic induction â alternating magnetic fields in the stator cause permanent magnets in the rotor to spin.
Motor Naming Convention
Architecture Diagram
Motor Size: WWMM
WW = Stator width in mm
MM = Stator height in mm
Examples:
2207 = 22mm wide, 7mm tall (5-inch racing)
2306 = 23mm wide, 6mm tall (5-inch freestyle)
1404 = 14mm wide, 4mm tall (3-inch micro)
2812 = 28mm wide, 12mm tall (7-inch long range)
KV Rating Explained
KV stands for "RPM per Volt" â the number of revolutions the motor makes per volt of input with no load.
Propeller Theory
Propellers are airfoils that generate thrust by accelerating air downward. Key parameters:
Motor Sizing Guide
Thrust-to-Weight Ratio
Hands-On Project: Propulsion Efficiency Calculator
Summary
- KV rating = RPM per volt; lower KV = more torque, higher KV = more speed
- Propeller size (Diameter x Pitch) determines thrust and efficiency tradeoffs
- Larger props are more efficient but less responsive
- Motor stator size determines torque capability and physical fit
- Thrust-to-weight ratio should be 4:1+ for good performance
- Always match motor, prop, and battery for optimal efficiency
Next, we'll cover battery and power management.