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Helicopter terms, definitions and expressions
| Expression | Definition |
|---|---|
| Auto-rotate | The action where by a pilot puts a helicopter into a controlled decent without the aid of an engine. Usually the helicopter would have to be within a predefined (by manufacturer) height/velocity atittude to be successful. Though the complete explanation is quite lengthy, basically the pilot lowers the collective control and puts the main rotor blade pitch into a negative angle to maintain rotor RPM during decent before feathering out (pulling the collective back up) to complete a touch down/landing. |
| Centrifugal Clutch | A clutch that enguages as a result of an outward force caused by turning motion. This system is usually automated without any pilot input. Such systems can reduced start-up and shut-down workload requirements for pilots. |
| Center of Gravity | The point where the (usually) forward and aft balance is calculated depending on weight and balance calculations of both the helicopter/aircraft and it's load including fuel and passengers. |
| Chord | The width of the rotor blade measured from the lead edge to the trailing edge. Chords can taper from root to tip in some designs. |
| Clutch | A system whether automatic or manual, of engaging the engine drive to the main flight transmission. eg. Centrifugal Clutch or clutchable V - belts to main rotor gearbox to drive the rotors. |
| Collective | The collective pitch control, or collective lever, is normally located on the left side of the pilot's seat with an adjustable friction control to prevent inadvertent movement changes the pitch (angle of attack) of the main rotor blades collectively to achieve ascent, decent and hover. |
| Cyclic | The cyclic control usually located between the pilot's legs and is commonly called the cyclic stick is similar to an aeroplanes ailerons but not only controls rolling left and right to achieve turns, it also moves forward and back to obtain it's directional control. |
| FPM | Feet per minute describing speed of ascent or descent. |
| Governor | An electrical or mechanical device that automatically maintains engine RPM with varying flight loads. |
| HIGE (Hover In Ground Effect) |
Hover in ground effect relates to the helicopters ability to hover at a certain altitude while |
| HOGE (Hover Out of Ground Effect) |
Hover in ground effect relates to the helicopters ability to hover at a certain altitude while |
| kmp/h | Speed, Kilometers (1000 meters) per hour - the amount of kilometers travelled within an hour |
| Knots | Speed, Nautical miles |
| MPH | Speed, Miles per hour - the amount of imperial miles travelled within an hour |
| Pedals | In a helicopter they are more correctly referred to as "anti-torque pedals". The anti-torque pedals are located in the same position as the rudder pedals in an airplane, and serve a similar purpose, namely to control the direction in which the nose of the aircraft is pointed. Application of the pedal in a given direction changes the pitch of the tail rotor blades, increasing or reducing the thrust produced by the tail rotor and causing the nose to yaw in the direction of the applied pedal. The pedals mechanically change the pitch of the tail rotor altering the amount of thrust produced. |
| ROC | Rate of Climb |
| Rotor Blade | The rotating "wing" of the helicopter. (Also applies to the tail rotor) |
| RPM | Revolutions Per Minute |
| Sprag Clutch | Also known as the over-run clutch, is basically a one way clutching device that allows the rotor blades to continue to turn, automatically disengaging the engine in the event of an engine failure. |
| Skids | |
| Swash Plate | |
| Throttle | Helicopter rotors are designed to operate at a specific rotational speed. The throttle controls the power produced by the engine, which is connected to the rotor by a transmission. The purpose of the throttle is to maintain enough engine power to keep the rotor speed within allowable limits in order to keep the rotor producing enough lift for flight. In many helicopters, the throttle control is a single or dual motorcycle-style twist grip mounted on the collective control (rotation is opposite of a motorcycle throttle), while some multi-engine helicopters have power levers. In many piston engine-powered helicopters, the pilot manipulates the throttle to maintain rotor speed. Turbine engine helicopters, and some piston helicopters, use governors or other electro-mechanical control systems to maintain rotor speed and relieve the pilot of routine responsibility for that task. (There is normally also a manual reversion available in the event of a governor failure.) |
| VHF | Very High Frequency relating to the AM band aircraft transceiver use for communication. |
| Vortex State |
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