by Christopher Chatterton

Created on: May 14, 2008   Last Updated: September 15, 2008

While rotary wing craft can be used to describe any vehicle that uses a means of upward lift to get airborne and fly, it generally refers to machines that generate lift around a central mast containing two or more rotor blades. By far the most common and widely used form of this type of machine is the helicopter.

Origins of the concept of Rotary Wing Aircraft

Leonardo Da Vinci and his intricate sketches of his airscrew' drawn in 1493, lay forgotten until in 1861, the French engineer Gustave de Ponton d'Amecourt coined the phrase Helicopter'. Originating from the French word helicoptere', it is derived from the Greek words helix' meaning spiral or turning and pteron' meaning wing; giving us spiral-turning wing (Anon, 2008). His vision for a vehicle that was lighter than air, and could achieve vertical take of and landing (VTOL), would not be fully implemented until the end of the 1940's.

How Helicopters Work

Helicopters and rotary wing aircraft achieve lift by turning rotor blades around a central mast, to generate upward lift.

These blades rotate and cut through the air, which in turn defeats the effects of gravity by increasing torque to the point where the vehicle spins upwards, much as a spinning top would.
To balance the effects of torque, which would otherwise continuously spin the craft around in the opposite direction, a tail rotor is fitted to allow forward propulsion, directed by the engine.

Hovering is the unique attribute that results from yaw control (movement from side-to-side) by means of foot pedals and a throttle stick to control the tail rotor and speed of the engine. The ability to hover has led to many applications for rotary wing aircraft, which distinguishes them from their fixed wing counterparts.

History of Rotary Wing Aircraft

It took some 450 years until the vision of Leonardo Da Vinci's sketch for a fully serviceable helicopter could be realised. The advent of the Korean War saw the introduction of medical evacuation from the battlefield to proper surgeons situated in the rear, usually some miles away and certainly inaccessible by ground transport.

Immortalised in M.A.S.H., the bumblebee' otherwise known as the Bell 47, deployed in 1950 by the United States Army allowed thousands of men to survive wounds that were untreatable by medics on the battlefield. The unique bubble' canopy allowed excellent all round vision but the single piston engine meant that the Bell 47 lacked power, which meant it had limited range and lift capability. This left

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