13. Propellers - Wings With A Twist

The Wright brothers realized that a propeller was a rotating wing – giving it a twist made it practical. By the mid 1930s, variable pitch and NACA research revolutionized propeller design. With the coming of the jet age, propellers fell out of favor for large aircraft. But designers soon realized that a fast turboprop with an advanced propeller could be more efficient than the best jetliners.