. Helicopter

helicopter is an aircraft with whirling rotor blades instead of fixed wings. It gets its lift from a set of spinning blades, called a rotor, which are turned by an engine.

The helicopter is one of the most use­ful aircraft. It does not need airfields to take off and land, and its flying abilities include vertical landings and takeoffs in addition to hovering. The name helicop­ter means “spiral wing”-a helicopter seems to spiral, or twist, its way through the air as it flies.

The First Ideas

Toy helicopters are quite easy to make from a spiral twist of paper, so it is not surprising that early inventors toyed with the idea of a flying machine using this principle. As far back as the 1400s,
the brilliant Italian artist and inventor Leonardo da Vinci sketched a flying machine with a large airscrew, resem­bling a helicopter. Sadly for him, there was no engine capable of powering such a machine, and it was never built.

Inventors experimenting with model helicopters with a single spinning screw, or rotor, came up against a serious flaw. As the rotor blades turned in one direc­tion, the body of the machine turned in the opposite direction. This problem was overcome by having twin rotors turning in opposite directions. In 1843, English aviation pioneer Sir George Cayley designed a helicopter along these lines,
with two sets of rotors. Steam engines, however, were the only power unit around, and they were far too heavy for a helicopter. There was no way to turn a toy into a machine that could lift people.