Some helicopters incorporate a stability augmentation system (SAS) to help stabilize the helicopter in flight and in a hover. The original purpose and design allowed decreased pilot work load and lessened fatigue. It allowed pilots to place an aircraft at a set attitude to accomplish other tasks or simply stabilize the aircraft for long cross-country […]
Most helicopters, other than smaller piston-powered helicopters, incorporate the use of hydraulic actuators to overcome high control forces. A typical hydraulic system consists of actuators, also called servos, on each flight control, a pump which is usually driven by the main rotor transmission and a reservoir to store the hydraulic fluid. Some helicopters have accumulators
The electrical systems, in most helicopters, reflect the increased use of sophisticated avionics and other electrical accessories. [Figure] More and more operations in today’s flight environment are dependent on the aircraft’s electrical system; however, all helicopters can be safely flown without any electrical power in the event of an electrical malfunction or emergency. Helicopters have
The fuel system in a helicopter is made up of two groups of components: the fuel supply system and the engine fuel control system. Fuel Supply System The supply system consists of a fuel tank or tanks, fuel quantity gauges, a shut-off valve, fuel filter, a fuel line to the engine, and possibly a primer
The transmission system transfers power from the engine to the main rotor, tail rotor, and other accessories during normal flight conditions. The main components of the transmission system are the main rotor transmission, tail rotor drive system, clutch, and freewheeling unit. The freewheeling unit or autorotative clutch allows the main rotor transmission to drive the
Reciprocating Engines Reciprocating engines, also called piston engines, are generally used in smaller helicopters. Most training helicopters use reciprocating engines because they are relatively simple and inexpensive to operate. Turbine Engines Turbine engines are more powerful and are used in a wide variety of helicopters. They produce a tremendous amount of power for their size
Antitorque System Helicopters with a single, main rotor system require a separate antitorque system. This is most often accomplished through a variable pitch, antitorque rotor or tail rotor. [Figure 1] Pilots vary the thrust of the antitorque system to maintain directional control whenever the main rotor torque changes, or to make heading changes while hovering.
Swash Plate Assembly The purpose of the swash plate is to convert stationary control inputs from the pilot into rotating inputs which can be connected to the rotor blades or control surfaces. It consists of two main parts: stationary swash plate and rotating swash plate. [Figure 1] The stationary swash plate is mounted around the
Helicopter Swash Plate Assembly and Freewheeling Unit Read Post »
The rotor system is the rotating part of a helicopter which generates lift. The rotor consists of a mast, hub, and rotor blades. The mast is a hollow cylindrical metal shaft which extends upwards from and is driven and sometimes supported by the transmission. At the top of the mast is the attachment point for
Airframe The airframe, or fundamental structure, of a helicopter can be made of either metal, wood, or composite materials, or some combination of the two. Typically, a composite component consists of many layers of fiber-impregnated resins, bonded to form a smooth panel. Tubular and sheet metal substructures are usually made of aluminum, though stainless steel
