These ungainly plane-helicopter hybrids were once used to transport mail

April 28, 1936

An autogyro takes off in front of the United States Capitol.

Image: Library of Congress

In 1919, Spanish aviation engineer Juan de la Cierva witnessed one of his airplanes crash after stalling out due to low speed. The pilot was uninjured, but Cierva was determined to improve the safety of low-speed flight.

The solution: a set of unpowered rotors attached to the top of the plane, a design Cierva dubbed autogiro.

As an autogyro accelerated forward with its conventional propellor, aerodynamic forces caused the rotors to autorotate, creating lift. This allowed the aircraft to take off with a much shorter runway. Read more...