8 Major components in helicopter - Learn it


The primary function of the fuselage (also called the air frame or hull) is to hold all of a helicopter’s components in place. It also: transfers the forces of the rotors, undercarriage, and payload; protects the occupants from the elements; and contributes to the aerodynamic behavior of the helicopter, although this is often compromised by other requirements


The skid gives the helicopter the ability to land on a surface, and bears the helicopter’s weight on the ground. Skids are mainly used on light helicopters; heavier models use wheels because skids are impractical when it comes to maneuvering the helicopter during ground operations. An important aspect of the skid is its ability to absorb kinetic energy; firstly, to provide for a smooth touch-down when landing, and secondly to absorb energy in the case of ground resonance. For these reasons, oleo-pneumatic struts (oleo for short) are often used in skid design.

Main Rotors

The main rotors give the helicopter its lifting and control force. The lifting force is orthogonal to the rotor disc (upwards). By tilting the rotor disc, the direction of the lifting force is controlled. Each rotor individually adds to this force. When considering the rotors, a second important force comes into play immediately: rotor drag. This operates parallel to the orientation of the rotor disc, and in the opposite direction of rotor movement. This force must be overcome by the engine.

Rotor head

The rotor head is the result of a very complex engineering effort. Its purposes are to control the amount of lift generated by the rotors, and to provide direction control by tilting the rotor disc. Both of these tasks are accomplished by changing the rotor blade’s pitch. The amount of lift is controlled by changing the blade pitch of all of the blades simultaneously by the same amount. The control that the pilot uses for this purpose is called the collective. 


A helicopter is powered by its engine(s). There are two types of engines in use: combustion and turbine. The combustion engine can be separated into the piston and the wankle sub-types. Piston engines are almost exclusively used in (very) light helicopters, although some which are turbine powered have recently come onto the market. Turbine engines are more expensive than their combustion counterparts. The main advantage of turbines is their high power to weight ratio. They are also more reliable than the combustion engine.


The first and primary function of the transmission is reduction gearing, since engines turn much faster than the main rotor shaft. The transmission must be able to cope with the high torque values produced when driving a rotor system. The second key function is the transmission of the main rotor thrust to the hull.


The main purpose of the tail rotor (or anti-torque rotor) is to prevent the helicopter from spinning, due to the engine's generated torque (in order to drive the main rotor system), and the reaction torque (Newton's Third Law) working on the fuselage. The tail rotor rotates much faster than the main rotor, and is powered by the same engine that powers the main rotors.

Tail boom

The tail boom has several functions. First of all, it provides the arm to the tail rotor generated anti-torque force. The tail rotor itself is housed at the end of the tail boom for this reason. Furthermore, the tail boom contributes to the aerodynamics of the helicopter, and the horizontal and vertical stabilizers are, consequently, attached to it. With increased airspeed, they provide stability due to their weather vaning effect. In some designs, the tail boom also plays a role by providing (some) anti-torque lift, which is produced by the main rotor down wash passing the tail boom. The tail boom is thus deliberately shaped in order to generate this anti-torque force.

2. Wikipedia

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