The first aircraft to fly using a variable-geometry wing, which allows for relatively low landing and takeoff speeds, but allows for higher in-flight speeds. The design was based on the Messerschmitt P.1101 captured at the end of World War II. Brig. Gen. Albert Boyd, then commander of the Air Force Flight Test Center at Edwards AFB, Calif., was the first pilot to complete full conversion from 20• sweepback to 60• sweepback in flight on August 23, 1951. The aircraft was difficult to fly and had a tendency to spin. Capt. Raymond Popson was killed on October 14, 1953, and the second X-5 was destroyed when he wasn't able to recover from a spin. Despite its flaws, the X-5 achieved all of its design objectives and provided a wealth of data on variable-geometry design. A total of 11 USAF, NACA, and contractor pilots made a total of 149 flights in the X-5s through 1955. The surviving aircraft is now on display at the US Air Force Museum at Wright- Patterson AFB, Ohio.
| Contractors: | Bell Aircraft Corp. |
| Locations Built: | Buffalo, N. Y. |
| Number Built: (USAF) | Two (two) |
| First Flight: | June 20, 1951 |
| First Flight Model: | X-5 |
| First Flight Location: | Edwards AFB, Calif. |
| First Flight Pilot: | Jean "Skip" Ziegler |
| Models/Variants: | X-5 |
| Powerplant: | One Allison J35-A-17 nonafterburning turbojet rated at 4,900 lb static thrust |
| Wingspan: | 32 ft 9 in (wings extended); 22 ft 8 in (wings swept) |
| Length: | 33 ft 4 in. |
| Height: | 12 ft 0 in. |
| Weight: | 9,875 lb gross |
| Armament: | None |
| Accommodation: | Pilot only |
| Cost: | Unconfirmed |
| Max. Speed: | 705 mph |
| Range: | 750 mi |
| Ceiling: | 42,000 ft. |
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