Hoppi-Copter

The Hoppi-Copter was a functional backpack helicopter developed by the American company Hoppi-Copters Inc. founded by Horace T. Pentecost in the 1940s. The original Hoppi-Copter consisted of two contra-rotating rotors on a pole attached to a motorized backpack. Although it was capable of flight, it was extremely hard to control.

Later prototypes of the Hoppi-Copter included versions with the pilot in a sitting position, and were in effect miniature one-man helicopters of a more conventional design, though retaining the contra-rotating rotors and thus obviating a tail rotor. Despite interest from the British Ministry of Supply in the 102 and 104 models, none were adopted commercially.

Variants

 * Pentecost HX-1 Hoppi-Copter (Hoppi-Copter 100): original back-pack version.
 * Hoppi-Copter 101: equipped with a seat and landing gear, proved that more development was necessary.
 * Hoppi-Copter 102: framed, with seat for pilot.
 * Hoppi-Copter 103: as the 102, but lighter with a more powerful engine and slightly greater rotor diameter
 * Hoppi-Copter 104: as the 103, with even greater rotor diameter
 * Hoppi-Copter Firefly