helicopters

A helicopter is an aircraft with long blades on top that go round very fast. It is able to stay still in the air and to move straight upwards or downwards. Aircraft with one or more power-driven horizontal rotors that enable it to take off and land vertically, move in any direction, or remain stationary in the air. Since a rotor is essentially a rotating airfoil, a helicopter is often described as a rotary-wing aircraft, in contrast to a conventional fixed-wing airplane. One of the earliest ideas for flying, it appeared in China and Renaissance Europe as a toy and in Leonardo da Vinci's designs. The Frenchman Paul Cornu made the first manned flight in 1907. Igor Sikorsky produced the first successful prototype in 1939, which was followed by rapid development in the U.S. and Europe. It is widely used for civilian transport, rescue work, and various commercial purposes. It has been used by military forces since the Korean War (1950-53) for transporting material, moving assault troops, and directly attacking other forces

helicopter

a powered trowelling machine with spinning blades used to spread concrete

helicopter

{i} highly maneuverable aircraft which flies by means of horizontally rotating blades

helicopter

An aircraft that can rise or descend vertically, by means of large overhead power-driven rotor or rotors

helicopter

an aircraft without wings that obtains its lift from the rotation of overhead blades

helicopter

An aircraft that is borne along by one or more sets of long rotating blades which allow it to hover, move in any direction including reverse, or land; and having a smaller set of blades on its tail that stabilize the aircraft

helicopter

A mid-air maneuver in which the skier rotates the body 360 degrees

helicopter

An overhead lift The partners skate facing each other, with the lifting partner skating backwards They clasp hands and the lifted partner is raised over the lifting partner's head as in a forward lasso lift In the air, the lifted partner maintains a position parallel to the ice with an arched back with the legs extended back and split in a "V" position, as though the arms and legs are the blades of a helicopter as the lift is turned by the lifting partner

helicopter