Background information on the X2 can be found in the following reference,

High Airspeed Testing of the Sikorsky X2 Technology (TM) Demonstrator, Paper presented at 67th Annual National Forum of the American Helicopter Society, Virginia Beach VA, May 4, 2011.

The aircraft was inducted into the Smithsonian National Air and Space Museum (Steven F. Udvar Hazy Center in Chantilly, Virginia, USA) on 27 October 2016.