Convair XFY-1 Pogo
The Convair XFY-1 Pogo was an experimental turboprop tailsitter built for a U.S. Navy programme that sought a vertical takeoff and landing (VTOL) fighter able to operate from the decks of ordinary ships and protect convoys. Convair and Lockheed received contracts in May 1951; Convair completed one flying XFY-1, driven by an Allison YT40 turboprop turning two 16-foot counter-rotating propellers. Test pilot James F. "Skeets" Coleman began tethered flights inside a Moffett Field airship hangar in April 1954, made the first free flight on 1 August 1954, and on 2 November 1954 flew the transition from a vertical takeoff to horizontal flight and a vertical landing. The concept worked, but flying the aircraft demanded exceptional skill, and the Navy closed the programme in 1956; the Pogo is now held by the National Air and Space Museum.
Why It Mattered
In the years after the Second World War, the U.S. Navy wanted a fighter that could rise vertically from the decks of ordinary ships — destroyers, oilers and transports — so that convoys and task forces would not depend on aircraft carriers for air defence. The Navy launched a formal VTOL fighter study in 1948, and in May 1951 it awarded contracts to Convair and Lockheed to design, build and fly experimental aircraft to prove the idea. Convair's entry, the XFY-1 Pogo, was a tailsitter, resting upright on its tail before rising vertically and levelling into forward flight. Where its Lockheed rival never took off or landed vertically at all, the Pogo did both; Defense Media Network describes its 2 November 1954 flight, from vertical takeoff through horizontal flight to a vertical landing, as the first such flight by an aircraft other than a helicopter or autogyro. The Smithsonian's judgement is that the Pogo proved the VTOL fighter concept theoretically possible, while showing how much work remained before it could be made practical.
Design Notes
The Pogo stood upright on the ground, supported at the trailing edges of its two delta wings and its dorsal and ventral fins. At each of the four tips, a small castering wheel on a long strut formed the landing gear; at touchdown the struts compressed several feet, in the manner of a child's pogo stick, the comparison that gave the aircraft its name, but there were no brakes and the wheels rolled freely. Its single Allison YT40 turboprop joined two T38 power sections side by side into one massive gearbox, and delivered 5,850 shaft horsepower to two counter-rotating propellers 16 feet across. Because the pilot sat upright for vertical flight and reclined for cruising, his seat rotated between the two attitudes. Convair even tied about 25 feet of rope inside the cockpit, so that after an emergency landing away from base the pilot could climb down safely. Weapons were never tested; the proposed armament was up to four 20 mm cannon in the wingtips, or 48 folding-fin rockets.
Operational History
Convair tested the engine on a vertical stand at Lindbergh Field, San Diego, by February 1954, and joined it to the airframe a month later. In April the project moved to Moffett Field, where flight testing began inside the vast Hangar One, built in the early 1930s for the dirigible USS Macon. On 29 April 1954, Convair test pilot James F. 'Skeets' Coleman made the first tethered flight, the aircraft steadied by lines from a motorised reel that flight-test engineer Bob McGreary could snatch tight if it teetered. Coleman accumulated more than sixty hours of tethered flying before the first free flights on 1 August 1954, when he rose 20 feet at the first attempt and 150 feet at the second. Testing then moved to Naval Auxiliary Air Station Brown Field, where he flew more than seventy further flights of takeoff, hover and landing. On 2 November 1954 Coleman took off vertically, transitioned into horizontal flight for 21 minutes, and came back to a vertical landing; the aircraft made its public debut two days later, and Coleman was later awarded the Harmon Trophy for the transition flight. Landing stayed the hardest part: unstable in the hover, the Pogo descended through its own turbulent propwash, and Coleman judged his descent with a Ryan radar altimeter whose three lights showed whether the rate was safe. A second pilot, John Knebel, flew the aircraft on 19 May 1955 without tethered-rig experience and nearly came to grief; Coleman made his own last flight on 16 June 1955. By then the great gearbox was wearing, with metal particles appearing in its oil, while the Navy's enthusiasm and funding were shifting to jets flown from aircraft carriers; on 1 August 1956 the Navy closed the books on the XFY-1.
Afterlife
After the programme ended, the Pogo remained near San Diego for several more years. The Navy shipped it to Naval Air Station Norfolk, Virginia, and the aircraft sat 'gate guard' there for a number of years. In 1973, the Navy transferred it to the National Air and Space Museum. It is now in the museum's collection at Suitland, Maryland — the only XFY-1 ever to fly. The Smithsonian presents it as one of the many attempts made after the Second World War to devise a practical VTOL combat aircraft.