Sikorsky-Boeing X2 Defiant
The Sikorsky-Boeing X2 coaxial rigid rotor technology Defiant helicopter demonstrator is being flown for the U.S. Army’s Joint Multi-Role Helicopter requirement. Sikorsky proved the efficiency of the rigid rotor co-axial design in 2010 when its 6,000-lb. gross weight X2 demonstrator helicopter achieved 250 knot flight speed, or twice the speed of conventional helicopters. It also demonstrated low pilot workload and low acoustic signature. The RAIDER prototype aircraft will improve on the X2 demonstrator by showcasing precision maneuvers in low flight speed, high G turning maneuvers at over 200 knots, hot day hover performance at altitudes up to 10,000 feet, and significant improvements in payload and flight endurance compared with conventional light tactical helicopters.
On 01 June 2005 Sikorsky Aircraft announced plans to build and test a demonstrator for a new class of coaxial X2 Technology helicopters that maintain or improve on all the vertical flight capabilities of rotorcraft and whose high speed configuration will cruise at 250 knots. The announcement came at the American Helicopter Society International's annual technical forum in Grapevine, Texas, where Sikorsky unveiled new scale models of X2 Technology helicopter concepts in various weight classes and configurations.
Preliminary design work for the demonstrator is finished and parts fabrication for the aircraft had alread commenced. Sikorsky initially planned to build and fly its X2 Technology demonstrator helicopter at its Schweizer Aircraft subsidiary by the end of 2006.
"We initiated X2 Technology convinced that the most productive and flexible helicopter is a helicopter which is capable of a significant increase in speed," said Sikorsky President Stephen Finger. "Customers are demanding greater speed but without sacrificing any of the unique capabilities that make helicopters the ideal platform for countless civil and military missions."
X2 Technology aircraft will hover, land vertically, maneuver at low speeds, and transition seamlessly from hover to forward flight like a helicopter. In a high speed configuration, one or more 'pusher props' are part of an integrated auxiliary propulsion system to enable high speed with no need to physically reconfigure the aircraft in flight.
The top cruise speed of helicopters in service today, roughly 150 to 170 knots, are only incrementally better than what they were decades ago due to the fundamental limits of conventional rotor systems. Previous attempts to develop faster helicopters have resulted in degraded hover performance. Likewise, attempts at fixed wing or hybrid vertical lift aircraft have resulted in aircraft with less hover capability than helicopters.
X2 Technology refers to a suite of technologies Sikorsky will apply to achieve new levels of performance in coaxial helicopters. The X2 Technology Demonstrator was funded by Sikorsky Aircraft with development taking place in collaboration with its Schweizer Aircraft subsidiary. X2 Technology aircraft will hover, land vertically, maneuver at low speeds, and transition seamlessly from hover to forward flight like a helicopter. In a high-speed configuration, one or more 'pusher props' are part of an integrated auxiliary propulsion system to enable high speed with no need to physically reconfigure the aircraft in flight.
Sikorsky selected the term X2 Technology in order to: describe a class of helicopters with a coaxial design and to describe the multiplying effects (2X, or times 2) of applying a suite of modern technologies to coaxial helicopters. These technologies include new rotor blade designs, advanced flight control laws, transmissions with greater horsepower to weight performance and the ability to seamlessly transfer power from the main rotor to the aft propulser, and active vibration control.
Sikorsky will also incorporate decades of company research and development into X2 Technology helicopters, including: the XH-59A Advancing Blade Concept Demonstrator which showed high speed was possible with a coaxial helicopter and auxiliary propulsion, the Cypher UAV which expanded company knowledge of the unique aspects of flight control laws in a fly by wire aircraft that employed coaxial rotors and the RAH-66 COMANCHE, which developed expertise in composite rotors and advanced transmission design.
On 20 September 2005 Sikorsky Aircraft was awarded two US government contracts to perform conceptual, preliminary design for two X2 Technology(TM) heavy-lift coaxial rotorcraft. The Concept Design and Analysis (CDA) awards from the US Army's Applied Aviation Technology Directorate (AATD) are in direct support of evaluating joint requirements and Joint Heavy Lift (JHL) rotorcraft for the armed forces.
Sikorsky's efforts focused on applying coaxial rotor X2 Technology to a super heavy-lift coaxial rotor crane that can cruise at 165 knots and a high- speed super heavy lift configuration capable of cruising at 245 knots.
AATD describes the CDA activity as defining the "art of the possible, the science of the probable and the design of the affordable" JHL vertical take- off and landing rotorcraft that enables future joint concepts of operations. The CDA will set the technical foundation for joint requirement analysis leading to design concept and performance projections that can reach Technology Readiness Level 6 by 2012.
The AATD contracts call for the conceptual and preliminary design of a baseline aircraft with a 250 nm radius along with eight variations to identify the impact of changes in payload, range, environmental conditions, and shipboard compatibility on aircraft size, performance, operational suitability, cost, schedule, and development risk.
On 13 February 2013 Sikorsky Aircraft Corp., a subsidiary of United Technologies Corp. and Boeing announced they would submit a joint proposal to build a demonstrator aircraft based on Sikorsky’s X2™ Technology rotorcraft design for the Army’s Joint Multi-Role (JMR) Technology Demonstrator (TD) Phase 1 program.
The Sikorsky-Boeing proposal will demonstrate how X2 Technology with counter-rotating coaxial main rotors and a pusher propeller, and advanced fly-by-wire system, will deliver efficient 230-knot cruise airspeed, improved hover efficiency, and weight optimized design in an affordable package. By leveraging our proven design, they believe they can offer the Army reduced risk, a 100-knot improvement in speed, a 60 percent improvement in combat radius and 50 percent better high-hot hover performance.
"The Sikorsky-Boeing team for JMR TD is truly a team of equals,” said Leanne Caret, vice president and general manager of Boeing's Vertical Lift division. “Sikorsky will take the lead role in this JMR TD Phase 1 proposal, and Boeing will take a lead role for Phase 2, for the mission systems demonstrator program.... Our companies are fully committed to the long term nature of the Future Vertical Lift initiative and we will contribute equally in terms of capital, technological capability and risk on our path to the FVL with the Army”.
Proposals for JMR TD Phase 1 were due to the U.S. Army Aviation Applied Technology Directorate by March 6, 2013. The Army was initially expected to announce its selection of one or more winning bids in late 2013. Demonstrator aircraft were expected to fly in 2017.
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