Bell XV-15 TRRA (Tilt Rotor Research Aircraft), Ship 2
The XV-15 Tilt Rotor technology demonstrator was the culmination of efforts begun in the early 1950s to produce an aircraft that could takeoff, land, and hover like a helicopter, but with the speed of an airplane. The rotor pylons tilt from vertical to horizontal to eliminate the speed barriers imposed on conventional helicopters by retreating-blade stall and allowed the XV-15 to operate at speeds of 550 kph (345 mph TAS).
This is the second of the two XV-15s built by Bell under a joint NASA/US Army program. It served from 1979 through 2003, demonstrating operations under a wide range of conditions and logged 700 hours in testing. Its success encouraged Bell and the US Marine Corps to develop a scaled-up Tilt Rotor, the MV-22, as a replacement for Marine transport helicopters. In association with Agusta Aerospace, Bell also developed the Model 609 civil Tilt Rotor with experience gained from the XV-15 program.
More information: Bell XV-15 TRRA (Tilt Rotor Research Aircraft), Ship 2