Sir George Cayley, often called the Father of Aeronautics, designed a helicopter powered by a bow-string mechanism with feather blades (similar to the reproduction shown here). Later, he experimented by flying a model with multiple adjustable surfaces, allowing him to understand how every change affected the model’s flight. This model is a ½ scale replica of his original 1804 model. Cayley used the data from these experiments to publish his On Aerial Navigation in 1809.
