What is the primary advantage of a NOTAR system over a traditional tail rotor?

The primary advantage of a NOTAR (No Tail Rotor) system over a traditional tail rotor is enhanced safety, particularly for ground personnel and in confined landing areas. A traditional tail rotor uses a small, vertically mounted rotor at the tail of the helicopter to counteract the torque produced by the main rotor. This tail rotor presents a significant hazard to anyone working near the helicopter, especially in low-light conditions or when space is limited. The NOTAR system replaces the tail rotor with a ducted fan located inside the tail boom. This fan forces air through slots along the tail boom, creating a boundary layer control effect that counteracts the main rotor torque. Additionally, a direct jet thruster at the end of the tail boom provides directional control. Because the rotating blades are enclosed within the tail boom, the NOTAR system significantly reduces the risk of accidents involving ground personnel. It also reduces noise and vibration compared to a traditional tail rotor.