Story ID: 
Sikorsky S-97 Raider Enters Flight-test Phase
By: Thierry Dubois
Caption: Prototype is representative of a multimission, high-speed helicopter for the U.S. Army, manufacturer says.
Word Count: 472
Sikorsky’s S-97 Raider semi-compound helicopter made its first flight on May 22. A follow-on to the X2 demonstrator, the S-97 combines two rigid coaxial, counter-rotating rotors and a pusher propeller to achieve speeds unattainable with a conventional rotorcraft.

The maiden sortie took place at the manufacturer's development flight center in West Palm Beach, Florida. It lasted approximately one hour, during which pilot Bill Fell and co-pilot Kevin Bredenbeck took the aircraft through a series of maneuvers designed to test hover and low speeds. With first flight achieved, the Raider is now moving onto,  “demonstrating key performance parameters critical to future combat operations including armed reconnaissance, light assault, light attack and special operations,” Sikorsky said, referring to the needs of the U.S. Army. The S-97 can be developed to carry six troops and external weapons. It has two aircrew. Cruise speeds are predicted to reach 240 knots.

“With the Raider aircraft’s unmatched combination of speed, maneuverability and acoustic signature, Sikorsky Aircraft is ideally positioned to provide the military with essential mission-specific capabilities. With this flight, we have started the demonstration of solutions to not only near-term capability gaps but also solutions for future vertical lift needs,” Samir Mehta, President of Sikorsky Defense Systems & Services, said.

In addition to military missions, Sikorsky is exploring commercial applications for the S-97. “In a commercial role, applications could include VIP transport, offshore oil support, search and rescue and medevac. The speed of the S-97 Raider makes it an interesting option,” Chris Van Buiten, vice president of Sikorsky Innovations, told AIN. Another feature for both civil and military operations is that the S-97 is relatively quiet. The rotor has a lower blade tip speed, there is no tail rotor and the pusher propeller can be shut off during hover and operations at normal helicopter flight speeds.

The program is 100 percent funded by Sikorsky and its 53 industry partners. GE Aviation provided a YT706-GE-700R turboshaft, part of the T700/CT7 family, for the single-engine rotorcraft. This 2,500-3,000 shp, FADEC-controlled engine is currently used in the Sikorsky MH-60M for the U.S. Army Special Forces. United Technologies Aerospace Systems provided the flight control computers, air data system and prop drive. Triumph provided the gearbox.

“The S-97 is much more production-representative than the X2, which was a single-seater,” Van Buiten said. The X2 was designed to prove the physics of the X2 configuration, whereas the Raider is rather designed to demonstrate the operational value to customers. According to Van Buiten, significant improvements have been made in several areas of the design including the fuselage, flight controls, drive train and rotor system.

The final assembly of a second prototype is to be completed this year. A demonstration tour of the Raider is planned for 2016.