During the past sixty years since theirfirst successful flights, helicopters havematured from unstable, vibratingcontraptions that could barely lift thepilot off the ground, into sophisticatedmachines of extraordinary flyingcapability. They are able to hover, flyforward, backward and sideward, andperform other desirable maneuvers. Igor Sikorsky lived long enough to have thesatisfaction of seeing his vision of a flying machine "that could lift itself vertically fromthe ground and hover motionless in the air" come true in many more ways than hecould have initially imagined. At the beginning of the new Millennium, there were inexcess of 40,000 helicopters flying worldwide. Its civilian roles encompass airambulance, sea and mountain rescue, crop dusting, fire fighting, police surveillance,corporate services, and oil-rig servicing. Military roles of the helicopter are extensive,including troop transport, mine-sweeping, battlefield surveillance, assault and anti-tank missions. In various air-ground and air-sea rescue operations, the helicopter hassaved the lives of over a million people. Over the last forty years, sustained scientificresearch and development in many different aeronautical disciplines has allowed forlarge increases in helicopter performance, lifting capability of the main rotor, highspeed cruise efficiencies, and mechanical reliability. Continuous aerodynamicimprovements to the efficiency of the rotor have allowed the helicopter to lift morethan its empty weight and to fly in level flight at speeds in excess of 200 kts (370km/h; 229 mi/h). Since the 1980s, there has been an accelerating scientific effort tounderstand and overcome some of the most difficult technical problems associatedwith helicopter flight, particularly in regard to aerodynamic limitations imposed by themain rotor. The improved design of the helicopter and the increasing viability of othervertical lift aircraft such as the tilt-rotor continue to advance as a result of therevolution in computer-aided design and manufacturing and the advent of newlightweight composite materials. The helicopter today is a safe, versatile, and reliableaircraft, that plays a unique role in modern aviation provided by no other aircraft.Back to ContentsThe Dream of True FlightCompared to airplanes, the development of which can be clearly traced to OttoLilienthal, Samuel Langley, and the first fully controlled flight of a piloted poweredaircraft by Orville and Wilbur Wright in 1903, the origins of successful helicopter flightare considerably less clear. A pure helicopter can be defined as any flying machineusing rotating wings (i.e., a rotor with blades that spin about a shaft) to provide lift,propulsion, and control forces that enable the aircraft to hover relative to the groundwithout forward flight speed to generate these forces. In addition, to be practical, the