|Sikorsky X2 Demonstrator|
|Role||Experimental compound helicopter|
|Manufacturer||Sikorsky Aircraft / Schweizer Aircraft|
|First flight||27 August 2008|
|Retired||14 July 2011|
|Developed into||Sikorsky S-97 Raider|
Design and development 
Sikorsky has incorporated decades of company research and development into the X2 helicopter on a $50 million budget. The S-69/XH-59A Advancing Blade Concept Demonstrator showed high speed was possible with a coaxial helicopter and auxiliary propulsion but it vibrated too much; the Cypher UAV expanded company knowledge of the unique aspects of flight control laws in a fly by wire aircraft with coaxial rotors; and the RAH-66 Comanche, which developed expertise in composite rotors and advanced transmission design. Other features include slowed rigid rotors 2 feet apart, active force counter-vibration inspired by the Black Hawk, and using most of the power for the pusher propeller rather than the rotor. The fly-by-wire system is provided by Honeywell, the rotor by Eagle Aviation Technologies, anti-vibration by Moog Inc, and propeller by Aero Composites.
On 4 May 2009, Sikorsky unveiled a mock-up of a Light Tactical Helicopter derivative of the X2.
Operational history 
The X2 first flew on 27 August 2008 from Schweizer Aircraft's (a division of Sikorsky Aircraft Corporation) facility at Horseheads, New York. The flight lasted 30 minutes. This began a 4-phase flight test program, to culminate with reaching a planned 250-knot top speed. The X2 completed flights with its propeller fully engaged in July 2009. Sikorsky completed phase 3 of the testing with the X2 hitting 181 knots in test flight in late May 2010.
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) set by a modified Westland Lynx in 1986. The X2 flight was purposefully made 37 years to the date of the S-69's first flight.
On 15 September 2010, test pilot Kevin Bredenbeck achieved Sikorsky's design goal for the X2 when he flew it at a speed of 250 knots (290 mph; 460 km/h) in level flight, an unofficial speed record for a helicopter. The demonstrator also reached a speed of 260 knots (300 mph; 480 km/h) in a shallow 2˚ to 3˚ dive, slightly less than the 303 mph of the XH-59A.
On 14 July 2011, the X2 completed its final flight and was officially retired after accumulating 22 hours over 23 test flights. With the end of development, the X2 will be followed by its first application, the S-97 Raider high-speed scout and attack helicopter.
Data from Flug-Revue NOTE: No other specifications have been released by Sikorsky.
- Crew: 2
- Length: not available ()
- Rotor diameter: 26.4 ft (8.05 m)
- Height: not available ()
- Disc area: 548 ft² (50.9 m²)
- Empty weight: lb (kg)
- Max. takeoff weight: 7,937 lb (3,600 kg)
- Powerplant: 1 × LHTEC T800-LHT-801 turboshaft, 1300–1800 shp (1000–1340 kW)
- Propellers: 1 six-bladed pusher-type propeller
- Rotor configuration: 2 four-bladed co-axial
- Maximum speed: 260 knots (299 mph, 481 km/h)
- Cruise speed: 250 knots (287.5 mph, 460 km/h)
- Range: 702 nmi (808 mi, 1300 km)
- Service ceiling: ft (m)
- Rate of climb: ft/min (m/s)
See also 
- Related development
- Aircraft of comparable role, configuration and era
- Eurocopter X3
- Kamov Ka-50
- Kamov Ka-92
- Lockheed AH-56 Cheyenne
- Mil Mi-X1
- Piasecki X-49
- Carter Personal Air Vehicle
- Related lists
- Trimble, Stephen. "Sikorsky's X2 speedster completes first flight". Flightglobal.com, 27 August 2008.
- Goodier, Rob (September 20, 2010). "Inside Sikorsky's Speed-Record-Breaking Helicopter Technology". Popular Mechanics. Retrieved 22 September 2010.
- Sikorsky to Build and Test X2 Technology Demonstrator Helicopter. Sikorsky
- Trimble, Stephen (26 July 2010). "Sikorsky X2 sets unofficial helicopter speed record". FlightGlobal. Reed Business Information. Retrieved 29 July 2010.
- First Flight Of Sikorsky X2 Demonstrator, Aviation Week & Space Technology, 27 August 2008. Accessed: 9 March 2012.
- X2 marks the spot for radical rotor designs, Flightglobal.com, 12 June 2007.
- "Sikorsky X2". Flug-Revue. Archived from the original on June 12, 2008. Retrieved 2007-06-25.
- Trimble, Stephen. Sikorsky unveils mock-up X2 armed scout. Flightglobal.com, 4 May 2009.
- Sikorsky and Boeing to pitch ‘X-2’-based design for US Army JMR TD effort - Flightglobal.com, February 28, 2013
- Trimble, Stephen. "Sikorsky high-speed X2 prototype starts flight-test phase". Flight International, 2 September 2008.
- Lynch, Kerry. "Sikorsky X2 Files With Engaged Propeller". Aviation Week, 13 July 2009.
- Croft, John. "Sikorsky completes third-phase X2 tests with 181kt flight". Flight International, 27 May 2010.
- Rotorcraft World Records. Fédération Aéronautique Internationale (FAI)
- "X2 Technology Demonstrator Achieves 225 Knots, Sets New Top Speed for Helicopter - Target Milestone of 250 Knots Looms in Q3 2010". Sikorsky.com, 26 July 2010.
- Croft, John (September 15, 2010). "Sikorsky X2 hits 250kt goal". Flight International. Retrieved 2010-09-16.
- Sikorsky's X2 Chases World Speed Record
- "Sikorsky X2 Technology Demonstrator Achieves 250-Knot Speed Milestone". sikorsky.com. 15 September 2010. Retrieved 23 September 2010. "The speed, reached during a 1.1-hour flight, is an unofficial speed record for a helicopter."
- Finnegan, Joy editor-in-chief (1 October 2010). "Sikorsky Breaks 250 KTAS Record". Rotor & Wing. Retrieved 6 October 2010.
- Robb, Raymond L. Hybrid Helicopters: Compounding the Quest for Speed p49, Vertiflite, Summer 2006. Quote: "Ultimately, the XH-59A achieved an incredible 303 mph"
- Paur, Jason (15 July 2010). "Sikorsky’s Record-Setting Helicopter Retires". WIRED. Retrieved 15 July 2011.
- "Award-Winning X2 Technology Demonstrator Takes its Final Flight - Program paved the way for upcoming S-97 Raider helicopter", Sikorsky Aircraft Corp., 14 July 2011.
- "Sikorsky X2 TD". unicopter.com. September 18, 2010. Retrieved November 21, 2010.
- Note: this is the disc area of one rotor set, not the effective area of the whole coaxial rotors set.
- Green, Ronald D. Flight Plan 2011 - Analysis of the U.S. Aerospace Industry, Rotorcraft Developments p18, U.S. Department of Commerce / International Trade Administration, March 2011. Accessed: 2 March 2012. Quote: "Several companies--including Sikorsky, Eurocopter, and Carter Aerospace Technologies--are developing compound helicopters to combine vertical/short take-off-and-landing capabilities with one or more propellers for increasing forward speed over conventional helicopter design."
- Sikorsky X2
- Sikorsky X2 (proposed) on unicopter.com
- "Sikorsky Calls X2 Shape of the Future", Aviation Week, 25 February 2008
- "Sikorsky X2 In Blades-On Ground Tests", Aviation Week, 21 May 2008
- "Hyper Helos: Prototypes coming off the drawing board and into the race", Flight International, 3 July 2008