] ] While powered microlights (ultralights) developed from hang gliding in the late 1970s, they were also a return to the type of low-speed aircraft that were common in the earlier years of aviation, but which were superseded as both civil and military aircraft pursued more speed [REF].
Surprisingly, what really launched the powered ultralight aviation movement in the United States was not the Rogallo flexible wing but a whole series of rigid-wing motorized hang gliders [REF].