In 1972, with funding from NASA and the US Army, Bell Helicopter Textron started development of the XV-15, a twin-engine tiltrotor research aircraft. Two aircraft were built to prove the tiltrotor design and explore the operational flight envelope for military and civil applications.

After three decades, they continue to be used as experimental testbeds.

The US Navy plans to acquire 48 HV-22Bs for combat search and rescue, special warfare and logistics support.

Type: Research Tiltrotor
Project begin : July 1973
First Flight : May 3, 1977
First conversion from vertical
to horizontal flight: July 24, 1979
Units built: 2
Crew: 2
Engines: 2 * 1550 hp Lycoming LTC1K-4K
Speed: Max: 550 km/h
Service Ceiling: 8800 m
Range: 800 km
Weight: Empty: 4340 kg -- Max: 6000
Rotor Span: 7.62 m
Length: 12.8 m
Height: VTOL 4.67 m
Disc Area: 91.23 m2