Two X-5s were built and flown. One crashed and was destroyed on October 13, 1953, when it failed to recover from a spin at 60 degrees sweepback. The other was delivered to the National Museum of the United States Air Force in March 1958.
Bell X-5
The X-5 was the first aircraft to vary the sweepback of its wings in flight. It was built to prove the theory that by increasing the sweepback of an airplane's wings after takeoff, a higher maximum speed could be obtained while still retaining low takeoff and landing speed and higher rate of climb with the wings swept forward.