National Police Air Service (NPAS)

NPAS Abbreviations

Forward Looking Infra-Red

National Police Air Service

NO Tail Rotor

Traffic Collision Avoidance System

Tactical Flight Officer

Coandă Effect   
The Coandă effect is the tendency of a fluid jet to be attracted to a nearby surface. The NOTAR system works to provide some directional control using the Coandă effect.  A variable pitch fan is enclosed in the rear of the aircraft immediately forward of the tail boom and driven by the main rotor transmission. This fan forces low pressure air through two slots on the right side of the tailboom, causing the downwash from the main rotor to hug the tailboom, producing lift, and thus a measure of directional control. This is augmented by a direct jet thruster and vertical stabilisers.