NOTAR® Technology

The NOTAR^® anti-torque system eliminates all of the mechanical disadvantages of a tail rotor, including long drive shafts, hanger bearings, intermediate gearboxes and ninety-degree gearboxes. Using the natural characteristics of helicopter aerodynamics, the NOTAR system provides safe, quiet, responsive, FOD-resistant directional control.

How does it work?

The enclosed variable-pitch composite blade fan produces a low pressure, high volume of ambient air to pressurize the composite tailboom. 

The air is expelled through two slots which run the length of the tailboom on the starboard (right) side, causing a boundary-layer control called the Coanda Effect. The result is that the tailboom becomes a "wing", flying in the downwash of the rotor system, producing up to 60 percent of the anti-torque required in a hover. The balance of the directional control is accomplished by a rotating direct jet thruster. 

In forward flight, the vertical stabilizers provide the majority of the anti-torque, however directional control remains a function of the direct jet thruster. 

NOTAR^® Technology Delivers:

• Greater Safety
  Studies have shown that 21 percent of all crashes are due to tailrotor strikes or loss of tail rotor effectiveness; NOTAR® systems eliminate these problems.
• Reduced Noise
  Designed and tested to be 50 percent quieter than any other helicopter. NOTAR-equipped helicopters are among the quietest certified helicopters available.
• Reduced Pilot Workload
  Using the Coanda Effect to provide tail boom lift and anti-torque, the system is more stable and easier to control. This effect reduces the sensitivity to wind direction on helicopter control.
• Reduced Aircraft Vibration
  The inherent stability of the standard MD 500 is further improved by the elimination of the exposed tail rotor assembly, which reduces overall helicopter vibrations and increases passenger comfort while reducing pilot fatigue.

In Production

There are just two production helicopters that utilize the NOTAR system, both produced by MD Helicopters.