Aerodin čije se održavanje u letu uglavnom postiže reakcijama vazduha na dve površine ili više površina koje se obrću pomoću motora; odlika mu je sposobnost da se uspravno, vertikalno diže, da stoji u mestu, da leti vodorovno, horizontalno, i da se lagano spušta na željenu tačku.
1. One that chops
2. Machine gun
4. A high-bouncing batted baseball
5. A customized motorcycle
An aircraft without wings that obtains its lift from the rotation of overhead blades; SYN. chopper, whirlybird, eggbeater.
Powered aircraft that achieves both lift and propulsion by means of a rotary wing, or rotor, on top of the fuselage. It can take off and land vertically, move in any direction, or remain stationary in the air. It can be powered by piston or jet engine. The autogiro was a precursor.
The rotor of a helicopter has two or more blades of airfoil cross-section like an airplane's wings. Lift and propulsion are achieved by angling the blades as they rotate. Experiments using the concept of helicopter flight date from the early 1900s, with the first successful lift-off and short flight 1907. Ukrainian–US engineer Igor Sikorsky built the first practical single-rotor craft in the US 1939.
A single-rotor helicopter must also have a small tail rotor to counter the torque, or tendency of the body to spin in the opposite direction to the main rotor. Twin-rotor helicopters, like the Boeing Chinook, have their rotors turning in opposite directions to prevent the body from spinning. Helicopters are now widely used in passenger service, rescue missions on land and sea, police pursuits and traffic control, firefighting, and agriculture. In war they carry troops and equipment into difficult terrain, make aerial reconnaissance and attacks, and carry the wounded to aid stations.