Fenestron
From Wikipedia, the free encyclopedia
A Fenestron (or Fantail) is a totally enclosed tail rotor of a helicopter that has a tail rotor configuration. Its purpose is to counteract the torque of the main rotor and is molded into the tail.
The term Fenestron was trademarked by the French company Sud Aviation, now known as Eurocopter.
While conventional tail rotors typically possess a maximum of 5 rotor blades, Fenestrons have between 8 and 18 blades. These are arranged in varying distance, so that the noise is distributed over different frequencies and thus appears quieter. Since the Fenestron has a smaller diameter, it has a higher circulation speed than a normal tail rotor.
Advantages of the Fenestron:
- Increased safety for people on the ground, since spinning tail rotors rank among the largest sources of danger with helicopters.
- Higher ground clearance of the tail arm and a smaller susceptibility to foreign objects.
- Greatly reduced noise, since the blade tips are enclosed; this and the greater number of blades leads to reduced vibration.
Disadvantages include higher weight of the enclosure, higher construction cost, and a higher power requirement because of the smaller size.
The Fenestron tail rotor was used for the first time at the end of the 1960s on the second experimental model of the SA 340, and on the later model Aérospatiale SA 341 Gazelle. Other than Eurocopter and its predecessors, the Fenestron was also used on the US military helicopter project Boeing-Sikorsky RAH-66 Comanche, which was cancelled in 2004.
