sentences:  Sikorsky intended to test hub fairings to reduce drag by 40%, and test flew fairings on the hubs themselves but not the central hub fairing ("aero sail") in between the hubs.Sikorsky has since patented a "Standpipe" (fixed tube between rotating rotor axes) suitable for a central hub fairing.On 4 May 2009, Sikorsky unveiled a mockup of a Light Tactical Helicopter derivative of the X2, and unveiled a prototype in October 2014.