As Sikorsky looks forward to the pending merger with Lockheed Martin, two advanced rotorcraft programs are progressing at pace. The high-speed S-97 Raider has flown a second time, while the systems integration laboratory (SIL) for the SB-1 Defiant rigid coaxial-rotor compound helicopter – for the US Army Joint Multi Role (JMR) program for which Sikorsky has teamed with Boeing - will fire up this year.
The first Raider prototype completed a 1.2-hr. second flight on Sept. 29 at Sikorsky’s development test center in West Palm Beach, Florida. The aircraft, which had undergone several upgrades since its maiden flight May 22, completed several takeoffs and landings, low-speed flight and the first run-on landings, says Chris Van Buiten, vice president for Sikorsky Innovations. Final assembly of the Defiant demonstrator will begin in 2016 with the aircraft on track to fly in 2017, according to Doug Shidler, Sikorsky's JMR program director.
The first Raider prototype is not expected to fly again until the ground-based transmission system testbed (TSTB), also at West Palm Beach, has completed 200 hr. of endurance testing on the aircraft's General Electric YT706 engine, transmission, rigid coaxial rotors and tail-mounted variable-pitch propulsor. The TSTB has logged 32 hr. and plans call for 15-20 hr. of testing a week, says Dave Banquer, Raider chief engineer.
The second of the two industry-funded Raider prototypes, meanwhile, is essentially complete and will be displayed at the Association of the U.S. Army’s convention in Washington on Oct. 12-14. While aircraft 1 will be used for envelope expansion and demonstration of the Raider’s key performance parameters, aircraft 2 will be used for customer demonstrations.
The S-97 is a follow-on to Sikorsky’s X2 technology demonstrator, which exceeded 250 kt. in 2010. The Raider is designed to cruise at 220 kt. carrying weapons on external pylons, and is capable of exceeding 250 kt. when clean—100 kt. faster than any conventional helicopter, the company says.
The JMR program is demonstrating high-speed rotorcraft configurations that are candidates for the Army’s planned Future Vertical Lift (FVL) Medium program to replace the Sikorsky UH-60 Black Hawk utility and Boeing AH-64 Apache attack helicopters beginning in the mid-2030s. The 230-kt. SB-1 is also based on Sikorsky’s X2 configuration. The main task for Defiant “is to demonstrate the handing qualities of the X2 in this size class,” says Pat Donnelly, Boeing's program director.
The Defiant is now in detail design, with many parts in fabrication, Shidler says. The SIL at Sikorsky’s Stratford, Connecticut, plant will tie the aircraft’s vehicle management system hardware and software together with simulated sensors and a cockpit simulator. “It will test the digital flight control system and all it controls,” Donnelly says.
The Defiant propulsion systems testbed at West Palm Beach – similar to the TSTB for Raider - will begin running in 2016 and endurance-test a full set of dynamic components to qualify them for flight. The Defiant will be assembled in the hangar where the two Raider prototypes were built.
FVL began as a Pentagon initiative to replace all of its helicopter fleets with a family of advanced rotorcraft sharing technologies. In January, the Army introduced the concept of “Capability Sets” describing missions to be performed by the different classes of FVL. Sikorsky and Boeing are teamed to pursue FVL Medium, which encompasses Capability Sets 2, 3 and 4.
“Capability 2 is attack, a smaller platform to support the Army, Navy and Marine Corps. Capability 3 is a bigger aircraft, an assault platform carrying a squad of 12-14 troops," Donnelly says. "Capability 4 is larger still, more of a V-22 growth assault platform."
The final size of FVL Medium will depend on the customer, but “with Raider and Defiant we will bookend Capabilities 2 and 3, and collect data based on actual flight vehicles to support validation of our design tools,” says Shidler.
Interaction with potential Raider customers has increased since the aircraft began flying, according to Van Buiten. “Flying makes all the difference and we are having some exciting discussions,” he says. “The level of interest is global, but the bulk of discussions are domestic because of export authorization. We have engaged the U.S. government for permission to have more in-depth discussions with specific international customers.”
The dialog is not just with military customers, but also commercial. Raider, which is designed to carry six troops, is about the right size for a six-passenger offshore-utility and “really good,” according to Van Buiten, as a four-passenger VIP helicopter. “In VIP configuration we can do New York-Washington and New York-Boston in an hour, and Cupertino, [California] to Los Angeles in 1.5 hr. Raider is a reinvention of the helicopter. That’s the kind of thing you expect to see in Silicon Valley,” he says.
This article has been compiled and condensed from two separate pieces, which are available to subscribers. The first, "Sikorsky Raider Flies Again As Lockheed Merger Nears" goes into greater detail about the September Raider flight and plans for the program. The second, "Sikorsky-Boeing JMR Demo On Track For 2016 Assembly" looks at the JMR concept and examines rival development programs as well as the Sikorsky-Boeing bid.
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