Helicopter

Overview

A helicopter is a rotary-wing aircraft that generates both lift and thrust from a powered main rotor, giving it the ability to take off vertically, hover, and fly in any direction. The single-main-rotor configuration with an anti-torque tail rotor is the most common arrangement: one large rotor does the flying while a small tail rotor counters the torque reaction that would otherwise spin the fuselage. A turboshaft engine supplies shaft power through a reduction gearbox to both rotors.

The machine is organised around its drive train. The turboshaft Turboshaft Engine delivers power to the Main Transmission / Gearbox, which reduces engine speed and splits torque between the Main Rotor System and, via a driveshaft, the Tail Rotor System. The Fuselage carries the cabin, tail boom and landing structure, supported on its Landing Skid Gear. The pilot commands the aircraft through the Flight Control System, monitors it through the Avionics & Cockpit Suite suite, and is supplied by the Fuel System and Electrical System systems.

How it works

Each main rotor blade is a rotating wing; as it spins it produces lift proportional to its pitch angle. Raising the collective lever increases pitch on all four blades together to climb, while the cyclic stick tilts the swashplate to change pitch around the disc, tipping the rotor and driving the helicopter in that direction. The articulated rotor head uses flap, lead-lag and feathering hinges so each blade can move independently and shed the asymmetric loads of forward flight.

The tail rotor, driven through a 90-degree gearbox, produces sideways thrust that the pilot trims with the anti-torque pedals. A freewheeling unit in the transmission lets the rotor keep turning if the engine fails, allowing the pilot to autorotate to a controlled landing using the energy stored in the spinning blades.