The S-69/XH-59A Advancing Blade Concept Demonstrator had shown that high speed was possible with a coaxial helicopter with auxiliary propulsion supplied using two jet engines, but that vibration and fuel consumption was excessive;[2][3][4] the Cypher UAV expanded the company's knowledge of the unique aspects of coaxial flight control laws with a fly-by-wire aircraft; and the RAH-66 Comanche developed expertise in composite rotors and advanced transmission design.

[16] Sikorsky has since patented a "Standpipe" (fixed tube between rotating rotor axes) suitable for a central hub fairing.

[19][20][21] In June 2014, Sikorsky/Boeing submitted the SB-1 Defiant helicopter design for the Future Vertical Lift program based on the X2 principle,[22][23] which was approved by the Army in October.

[27] On 26 July 2010, Sikorsky announced that the X2 exceeded 225 knots (259 mph; 417 km/h) during flight testing in West Palm Beach Florida, unofficially surpassing the current FAI rotorcraft world speed record of 216 knots (249 mph; 400 km/h) set by a modified Westland Lynx in 1986.

[40] It was donated to the National Air and Space Museum in October 2016 and is on display in the Steven F. Udvar-Hazy Center in Chantilly, Virginia.

[41][42] The Sikorsky Aircraft Corporation and the X2 Technology Demonstrator Team was awarded the 2010 Robert J. Collier Trophy by the National Aeronautic Association[43][44] "...For demonstrating a revolutionary 250 knot helicopter, which marks a proven departure point for the future development of helicopters by greatly increasing their speed, maneuverability and utility."