ELI5: How Contra-Rotating Propellers Work

A single propeller creates a swirling motion of air behind it (called 'torque' or 'swirl effect'), which wastes energy and can make the aircraft harder to control. Contra-rotating propellers consist of two propellers mounted on the same shaft, but spinning in opposite directions. The second propeller essentially 'recovers' the energy from the swirl created by the first, straightening out the airflow. This results in greater efficiency (more thrust for the same power), cancels out the torque effect for better control, and reduces noise, often seen in military planes needing high power and efficiency in a compact space.