Smallest Manned Helicopter

A human-powered helicopter is a helicopter powered solely by one or more humans carried on board. As in other human-powered aircraft, the power is usually generated by pedalling. It remains a considerable engineering challenge to obtain both the power-to-weight ratio and rotor efficiency required to sustain a helicopter in flight.
A helicopter, or chopper, is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of Vertical Take Off and Landing aircraft cannot perform.
Helicopters were developed and built during the first half-century of flight, with the first operational helicopter in 1936. Some helicopters reached limited production, but it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production, with 131 aircraft built. Though most earlier designs used more than one main rotor, it is the single main rotor with anti-torque tail rotor configuration that has become the most common helicopter configuration. Tandem rotor helicopters are also in widespread use due to their greater payload capacity. Coaxial helicopters, tiltrotor aircraft, and compound helicopters are all flying today. Quadcopter helicopters pioneered as early and other types of multicopter have been developed for specialized applications such as unmanned drones.
A major problem with the autogyro was driving the rotor before takeoff. Several methods were attempted in addition to the coiled rope system, which could take the rotor speed to 50% of that required, at which point movement along the ground to reach flying speed was necessary, while tilting the rotor to establish autorotation. Another approach was to tilt the tail stabiliser to deflect engine slipstream up through the rotor.
Due to the operating characteristics of the helicopter—its ability to take off and land vertically, and to hover for extended periods of time, as well as the aircraft's handling properties under low airspeed conditions—it has been chosen to conduct tasks that were previously not possible with other aircraft, or were time- or work-intensive to accomplish on the ground.
A helicopter used to carry loads connected to long cables or slings is called an aerial crane. Aerial cranes are used to place heavy equipment, like radio transmission towers and large air conditioning units, on the tops of tall buildings, or when an item must be raised up in a remote area, such as a radio tower raised on the top of a hill or mountain. Helicopters are used as aerial cranes in the logging industry to lift trees out of terrain where vehicles cannot travel and where environmental concerns prohibit the building of roads.