Sikorsky S-97 Raider. Photo courtesy of Sikorsky
The Sikorsky S-97 Raider's flight test program has lifted off after being grounded for nearly a year. The demonstrator met its flight objectives Tuesday.
Sikorsky VP for Future Vertical Lift Dan Spoor said test pilots Bill Fell and John Groth flew the complete flight test card, flying the aircraft for 90 minutes at Sikorsky's facility in West Palm Beach, Florida.
It is the first public announcement of Raider's return to flight since one of the two operational prototypes suffered a hard landing in August 2017. Raider itself is based off the experimental X2 Sikorsky built and used to demonstrate 200-kt forward flight with an airframe capable of vertical takeoff and landing.
Raider is the precursor of the yet-to-fly SB-1 Defiant on offer for the Joint Multi-Role Technology Demonstrator (JMR-TD) program that will feed into and inform the requirements for the U.S. Army-led Future Vertical Lift (FVL) initiative to develop a next-generation helicopter.
"This is a significant milestone, which allows us to proceed with our full flight test program to demonstrate how Sikorsky’s X2 Technology is revolutionizing the future of vertical lift," said Spoor. "We look forward to demonstrating to the U.S. military that high flight speed, and extraordinary maneuverability in the hover and low speed regimes, will dramatically change the way that military aviators fly and fight with helicopters."
What makes the S-97 stand out is its coaxial rotor design, which is being scaled up into the Defiant. A tail propeller — it does not need a tail rotor because of the coaxial main rotor system — provides forward thrust as much as a boat prop.
Bell's V-280 demonstrator, which recently demonstrated several capabilities such as cruising at 160 kt, is the other aircraft in the JMR-TD program. It is an evolutionary tiltrotor based on the V-22 Osprey in use by the U.S. Marine Corps, U.S. Air Force Special Operations Command, Japan and soon to be the U.S. Navy.
When entering forward flight, the V-22's engines and rotors — being fixed in the same nacelle — rotate forward on each end of its wings. The V-280's rotors move while the engines are fixed forward, allowing for tactical improvements like sliding side doors and the integration of a fly-by-wire controls system.