page_title: Backpack helicopter
section_title: Examples
hierarchical_section_title: Backpack helicopter / Examples
caption_attribution_description: English: (A possible design for a helibackpack with counter-rotating twin rotors. I made this image with CGI.
context_page_description: A backpack helicopter is a helicopter motor and rotor and controls assembly that can be strapped to a person's back, so he can walk about on the ground wearing it, and can use it to fly. It uses a harness like a parachute harness and should have a strap between the legs. Some designs may use a ducted fan design to increase upward thrust. Several inventors have tried to make backpack helicopters, with mixed results.
  Typically, a backpack helicopter differs from a conventional helicopter in two main ways:
  First, there is no tail rotor, and the main rotors are contra-rotating. Yaw is controlled by fine adjustment of a differential gear in the rotor drive transmission. When one rotor is adjusted to spin slightly faster than the other, it induces yaw.
  Second, the rotors are fixed pitch, which assists with simplicity; this means, however, that in the event of engine failure autorotation is impossible. Usually, a ballistic parachute would be incorporated for safety.
  An edition of Popular Science magazine in 1969 featured a backpack helicopter that used small jet engines in a tip jet configuration instead of contra-rotating rotors. This design could function in autorotation.
caption: A possible design for a helibackpack with contra-rotating twin rotors
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