AEROSPACE PRODUCTS
Civilian helicopters

Helicopters are perhaps the most versatile aircraft devised by man and are used in multifarious roles, both civil and military. Their manoeuvrability allows them the facility of landing and operating from areas from which fixed wing aircraft find it difficult, or impossible, to operate.

Helicopters are 'rotorcraft' as distinguished from 'fixed-wing' aeroplanes, such as the aeroplanes that airlines fly or the fighters and bombers in the world's air forces. Helicopters get their 'lift' from rotor blades rotating around a mast.

In fixed-wing aeroplanes, the wing profile (called aerofoil) deflects air efficiently downward, causing an opposite lifting force on the wing, with lower pressure on the upper surface and higher pressure on the lower surface, providing 'net lift'. However, the more the lift of the aerofoil, the greater is the 'drag'. A helicopter uses the same principle, only, its rotors work like rotating wings.

Although, because of their shape and propulsion, helicopters do not compare favourably with jets, they offer two main advantages:

• Because of their rotors providing lift in a vertical direction, helicopters can take off and land vertically, and can hover in the air over a single point on the ground. So they can land on, and take off, from small areas such as pinnacles of hills and rugged terrain in remote areas and confined areas like building tops in crowded cities.
• Because of their ability to hover and to move at very slow speeds (at which most aeroplanes, other than those adapted to vertical take-off and landing, would just fall to the ground), helicopters are able to fly at very low, almost ground-hugging, levels. This gives them an advantage in battlefront operations.

Due to these advantages, helicopters are ideally suited for search and rescue operations, medical evacuation and observation, besides commuting and private transport. Helicopters are also used for tasks such as fire fighting, tours, personnel transport and law enforcement.