The Mini-copter was originally conceived as a man-carrying platform for use by the military. Its use was intended to be for Army Special Forces and to retrieve downed combat pilots from behind enemy lines.
In 1954 an American inventor named Gilbert W. Magill of Glendale California designed and built the HR-1, a "mini" portable helicopter, at the tip of the rotor blades a hydrogen peroxide rocket engine impulse the rotor, this helicopter was better known as the "Pinwheel".
Magill made his helicopter portable in a carrying box which was a success that flew incredibly well and had a fantastic performance for its size, with a maximum speed of 161 km / h (100 mph), a ceiling of 4570 meters (14.993 feet) and a range of 32 km (20 miles) with two tanks with a total of 20 liters of hydrogen peroxide 90% ea This small helicopter still holds the world´s record speed of vertical climb rate.
The project was originally funded by the U.S Navy and a working model was developed, but due to the end of the Vietnam conflict the requirements for retrieving downed Navy pilots came to an end.