The Ligeti Stratos is one of the most original aircraft ever to come out of the Australian ultralight movement: a tiny, fully enclosed, joined-wing pusher designed and built in Melbourne in the mid-1980s by Charles and Helena Ligeti. This page summarises the story of the aircraft and its designer. The full history, written by Arthur Marcel in 2014, is available as a PDF document at the bottom of the page.
Who built it
Charles and Helena Ligeti emigrated to Australia from Czechoslovakia in 1977. Charles, a chemical engineer by training, came from an aviation family: his father had flown in the Second World War and later with Czechoslovakian Airlines, and held a number of patents. Australia at the time was opening the door to home-built flight through Air Navigation Regulation (exemption) 95:10, and the Ligetis decided to design an aircraft of their own.
It was Helena who suggested looking at joined-wing concepts. The couple tested the idea first with radio-controlled fibreglass gliders, then with smaller models, working out how to keep a connected-wingtip aircraft stable in yaw and roll and how to give it benign stall behaviour. They even built a foot-launched glider for the Melbourne Birdman Rally before committing to a full-size machine.
The S1 prototype
Construction of the prototype, the S1 Stratos, began in late 1983. The layout was unlike anything else on the field: a rear-mounted engine driving a ducted fan in pusher configuration, a streamlined enclosed cockpit, and a lower wing that also acted as a forward control surface in the manner of a canard. Many other builders doubted the odd-looking aircraft would fly at all.
It did. On 25 April 1985, at Penfield Aerodrome near Sunbury, about 35 km from Melbourne, Charles flew the Stratos for the first time, completing several circuits and a safe landing, despite having only around ten hours of flying experience gathered in a Cessna and a glider at Helena’s insistence. The S1 turned out to be fast, manoeuvrable and efficient, with a lift-to-drag ratio no other 95:10 aircraft of the day could match, and it soon began collecting awards for performance and originality. In 1986 the Ligetis formed a company, took the aircraft to North America and won awards at Oshkosh.
The S2 and the 1987 accident
The production version, the S2, was a substantially different aircraft: a larger cabin, side-stick controls, a slightly bigger engine (28 hp instead of 24), elevator on the canard only and ailerons on the main wing only, plus aerodynamic refinements to the fuselage intended to squeeze more lift out of limited power. Those changes also altered the stall. Where the S1 had a gentle nose-bobbing stall, the S2 stalled more sharply and needed more height to recover.
On 22 September 1987, again at Penfield, Charles Ligeti took the S2 up for its first flight. Test flying in that era had to be carried out below 500 feet. The aircraft stalled, there was not enough height to recover, and Charles was killed in the crash. Work on the Stratos stopped, and Helena closed the business.
The project today
The couple’s son, Ron Ligeti, went on to study aerospace engineering at RMIT and to work on composite aircraft structures with Boeing in Melbourne. He has since set out to build a new Stratos, with his mother helping in the workshop. In 2014 he was presented with the Ligeti Labahn Memorial Shield at Natfly.
Download the full history
LGT-Stratos-History.pdf — The Ligeti Stratos by Arthur Marcel, 2014, 4 pages with photographs. This is the original document that was published on this site in 2014; it is kept here at the same address so that existing references to it continue to work.
See also: Scott Winton: 25 years since, another of Arthur Marcel’s histories hosted on this site.
