The tail rotor is a small propeller blade at the back of a helicopter's tail assembly that spins at a very high rate of speed. This propeller is used to maintain straight flight and the proper body positioning of the helicopter. By manipulating the speed of the tail rotor, the pilot is able to manipulate the position of the helicopter while in flight. If not for the tail rotor, the body of a helicopter would simply spin in a circle when the engine was started. It was once thought that a helicopter would never be able to effectively fly, and the entire concept was nearly abandoned prior to the invention and development of the tail rotor.
In the cockpit of a helicopter, the pilot has two separate hand controls as well as two foot pedal controls. The hand controls include one center joy stick that controls the altitude of the center or top main rotor. The second hand control mounted low and to the side of the pilot's seat controls the tail rotor. By adjusting the tail rotor to spin faster or slower, the tail of the helicopter is either allowed to rotate around or to be pushed back against the force of the main rotor. In some helicopters, this control of the tail rotor is accomplished by the manipulation of louvers that are placed in front of the rotor blades.
The tail rotor is a primary target in military aircraft. By damaging or knocking out the tail, the helicopter will not be able to continue flight and will usually violently crash. This is the reason that many military helicopters incorporate an armored area of protection surrounding the rotor and the tail. In an effort to increase the battle strength of the helicopter, some countries are experimenting with designs utilizing small jet thrusters in place of rotor blades on the helicopters in their military arsenals.
Some helicopter designs intended to be used as military weapon ships use two tail rotors. In theory, should one rotor happen to become damaged, the second rotor will be able to maintain proper flight characteristics. The best defense, however, is to avoid damage to the rotor in the first place. Defensive weaponry such as anti-radar cloaking devices, anti-missile rockets and chaffing devices intended to fool a missile into striking it instead of the helicopter have been designed and utilized to great success by many military outfits around the world.