The quest for a vertical takeoff aircraft that has the performance of a conventional plane has been a dream of designers – and military personnel – since the development of high thrust jet-type engines.
***image1***There have been several proposed solutions, including, in the 1950s, “tail sitters” like the U.S. Navy’s Convair XFY-1 Pogo. The basic idea was that a tail sitter would not have to rely on heavy thrust direction devices like the AV-8 Harrier or heavy engine rotation mechanisms like the OV-22 Osprey, equipment that is extra weight when flying “like an airplane.” Navies especially liked the idea because vertical takeoff aircraft could be launched from small spaces, eliminating the need for large carrier decks.
The XFY-1 was initially considered viable. The tail sitter would not require any extra weight, only a design that allowed it to sit on its tail and an engine that was strong enough to provide the 1:1 thrust-to-weight ratio needed to take off.
On the Pogo, two turbo prop engines were linked together to provide more than 5000 horsepower to drive a pair of contra-rotating, 16-foot propellers, and the four delta wings had small wheels on the tips for landing. The wheels had long springs attached to absorb the shock of landing, bouncing the aircraft when it touched down like it was landing on pogo sticks – thus the perhaps unfortunate name.
The Pogo made numerous test flights tethered in a hangar, and then began a program of real flights. Its performance was sprightly – not surprising considering its high thrust-to-weight ratio – but it proved very tricky to land, since it had to be “backed” down by the pilot looking over his shoulder. Its relatively small size also raised questions about its range and other issues such as loading underwing weapons.
In any event, the Navy became enamored with the higher performance of pure jets, which offered performance that a turboprop could not match. The XFY-1 was ultimately dropped.