David Unaipon (born David Ngunaitponi; 28 September 1872 – 7 February 1967) was an indigenous Australian preacher, inventor, writer and activist. He was a member of the Ngarrindjeri nation. He was born at Point McLeay, a Lutheran mission located on the mouth of the Murray River southeast of Adelaide. As an inventor, he invented the modern sheep-shearer, centrifugal motor, a multi-radial wheel, helicopter blades, and a mechanical propulsion device, deriving many of his designs from Aboriginal-Australian tools and weaponry. As a preacher and activist, he preached widely throughout South Australia, often travelling on foot, preaching that Aboriginal-Australian beliefs and Christiann religion are similar (if not the same) in nature, and advocating for Aboriginal-Australian rights and welfare. He also became the first Aboriginal Australian to publish extensive written works in the English language. Unaipon's portrait is featured on the Australian $50 bank note in commemoration.
