NOTAR-NO TAil Rotor (coanda effect)

the NOTAR system is simple in theory and works to provide some directional control using the Coandă effect.A variable pitch fan is enclosed in the aft fuselage section 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.

Benefits of the NOTAR system include increased safety (the tail rotor being vulnerable), and greatly reduced external noise. NOTAR-equipped helicopters are among the quietest certified helicopters.


 1 Air intake
2 Variable pitch fan
3 Tail boom with Coanda Slots
4 Vertical stabilizers
5 Direct jet thruster
6 Downwash
7 Circulation control tailboom cross-section
8 Anti-torque lift


There are three production helicopters that utilize the NOTAR system, all produced by MD Helicopters:

• MD 520N: a NOTAR variant of the Hughes/MD500 series helicopter.
• MD 600N: a larger version of the MD 520N.
• MD Explorer: a twin-engine, eight-seat light helicopter.