The Stratos was an Australian single seat ultralight aircraft, developed by Charles Ligeti in the 1980s.
The most notable feature is its closed wing configuration, with the sweptback foreplane and the high-mounted mainplane being connected at their wingtips by vertical fins.
The prototype, piloted by Ligeti, first flew on 25 April, 1985, with him later reporting that the aircraft fulfilled or exceeded all expectations.
During testing at Penfield, near Sunbury, Victoria on 22 September 1987, Ligeti lost control of the aircraft, with the craft falling vertically to the ground.
[5] An investigation by the Australian Transport Safety Bureau focused on a change made to the forward wings, so that they had full span elevators, affecting stalling and pitching behaviour.