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Thursday, December 1, 2011

Sikorsky Targets S-97 Raider Flight in 2014

Military X2 variant wraps up preliminary design review stage.

By Douglas Nelms

Sikorsky X2 demonstrator’s “backbone” and coaxial rotors on display at AUSA in October. Photo by Andrew Parker

Stratford, Conn.-based Sikorsky Aircraft has completed the preliminary design review (PDR) for its S-97 Raider, going through all the sub-systems and overall system design, and has started the detail design and long lead time parts fabrication, which keeps the aircraft on target to fly in 2014, according to Chris Van Buiten, vice president of Sikorsky Innovations, the technology development arm of Sikorsky Aircraft Corp. Van Buiten added that some 20-plus “suppliers and partners” are involved in the program.

The S-97 is based on technology developed through Sikorsky’s X2 experimental helicopter prototype, and the manufacturer intends to enter the helicopter in the U.S. Army’s upcoming Armed Aerial Scout (AAS) program. Two prototypes will be built, configured to carry up to six troops.

Of the five major competitors considering the AAS program, Sikorsky is the only one that does not already have a prototype flying. The others are the Bell OH-58 Block II, Boeing AH-6im, EADS North America AAS-72X and AgustaWestland, with either the AW109 or AW119. The disadvantage of not already having a flying prototype is trumped by the advantage of having a future aircraft capable of flying at twice the speed, with double the maneuverability and the capability to hover out of ground effect at 10,000 feet at 95 degrees F, compared to the “6K/95” requirement (6,000 feet/95 degrees F) for the other aircraft, Van Buiten pointed out. He also noted that the S-97 features totally new technology, whereas the other competing helicopters are all new generations of older aircraft, two of which date back to the Vietnam era.

Sikorsky has not revealed the cruise speed for the S-97, but has quoted it as well in excess of 200 knots with a range of 570 km (307 nm). The X2 demonstrator has already exceeded 250 knots using a pusher propeller that generates 1,500 lbs of thrust. The pusher propeller will allow the pilot to fly with it engaged or disengaged. When the prop is disengaged, the Raider operates at very low decibel noise levels.

The S-97 is also being designed to take a variant of the GE CT7-8 engine, an extension of the T700-GE-701D used in the Black Hawk. “The aircraft is being designed from the beginning to leverage the upcoming ITEP (Improved Turbine Engine Program) with power in the 3,000 SHP range,” Van Buiten said. The ITEP program is current Army sponsored plan to produce an engine for its UH-60 Black Hawks and AH-64D Apaches that will produce greater shaft horse power while consuming less fuel.

“Sikorsky sees great value in a Raider design that uses a single engine that is common with Black Hawk and Apache,” Van Buiten said.

The 701D engines is rated in the 2,000 SHP range while the CT7-8 is in the 2,500-3,000 SHP range.

Van Buiten noted that the S-97 is being designed from the start to be manned by either one or two pilots, or flown totally autonomous as a UAV, depending on the mission requirement. “We call it the optionally piloted aircraft, so the mission commander makes the decision which version to use. No pilot on board, or one pilot plus one observer—or, for a very demanding mission, with two trained aviators up there.”

He explained that Sikorsky is already looking at the next size up from the S-97, which would be replacements for the Black Hawk and the Apache after 2020. These would also use technology developed from the X2 program. “There is no formal program yet, but we are getting ready. Those (aircraft) would have the same game changing attributes as the S-97—double the speed and maneuverability and the same 10K/95 HOGE … but with twin engines.”

CONTRACTS: Bell-Boeing Joint Project Office, Amarillo, Texas, was awarded a $12.3-million agreement to demonstrate, integrate and qualify the Interim Defense Weapon System mission kit on the MV-22 tiltrotor aircraft including associated logistics support. Work will be performed in Ridley Park, Pa. (99 percent) and Fort Worth, Texas (1 percent), and is expected to be completed in July 2010. General Electric Aviation, Lynn, Mass., was awarded a $33.2-million contract for repair of components in the T64 engine used on the H-53 aircraft. Work will be performed at Lynn, Mass., (86 percent) and Cherry Point, N.C., (14 percent) and is expected to be completed by September 2009.

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