X-13 Vertijet

In 1947, the US Navy awarded the Ryan Company a contract to see whether or not a fighter plane could be made to take-off vertically. The result, after the Air Force took over the project in 1943, was the X-13. The aim at the beginning was to evaluate whether or not submarine-based aircraft would be feasible, and it's easy to imagine this beauty leaping from the seas. Once the Air Force became involved, the aim was to develop a jet-powered VTOL (Vertical Take-Off and Landing) aircraft.

The X-13, powered by a single Rolls-Royce Avon turbojet engine, was something of a success. During a test in 1957, it launched vertically, then transitioned to horizontal flight and back again. It was then demonstrated in Washington, D.C., where it crossed the Potomac River and landed at the Pentagon.  Unfortunately, the Air Force chose not to develop the project any further, citing a lack of operational requirements. That said, today's Harrier and F-35 jets can trace their ancestry directly back to the X-13.