1966 to 1994 $20 Twenty Dollars King Ford Smith / Hargrave Old Australian Paper Money Banknote (ET Series)

Australian invention in the age of aviation

At the time, early aviators were experimenting with mono-winged gliders, which were proving unstable and unsafe, and trying to develop an engine powerful enough to achieve lift.

Hargrave conducted many experiments and made countless models of his ideas. He studied aerofoils and developed a wave-propelled boat, a screw-driven engine, a working model aircraft with flapping wings, and a rotary engine so ahead of its time it was re-created by another inventor in 1908 and used in aviation for many years.