The XH-51A was a high speed demonstrator helicopter. The first flight was a hover with the aircraft piloted  by Lockheed test pilot  Ray J. Goudey. The aircraft made it's first transition to forward flight on  Nov. 2, 1962 with Lockheed engineering test pilot Donald R. Segner at the controls.

The initial configuration had a 3 blade main rotor, which was later changed to 4 blades.

Source: "Rigid Rotor Rewind: Lockheed Helicopters Come Full Circle", Raymond L. Robb, VERTIFLITE March/April 2017, Page 51