SB>1 Defiant Breaks Cover

 - December 28, 2018, 5:29 AM
The SB>1 Defiant employs a rigid coaxial main rotor with an eight-bladed pusher propeller. (photo: Sikorsky)

Sikorsky and Boeing have released the first images of the jointly developed SB>1 Defiant as the compound helicopter nears its first flight. Registered N100FV, the SB>1 (also given the Sikorsky in-house model number S-100) has been assembled at Sikorsky’s facility at West Palm Beach, Florida.

The two companies joined forces in January 2013 to offer a bid for the U.S. Army’s Joint Multi-Role Technology Demonstrator (JMR-TD) program, which is intended to provide data that will inform the development and specifications for the U.S. Army Future Vertical Lift requirement that will, in turn, create a new generation of medium utility helicopters for service from the 2030s with double the speed of today’s rotorcraft and a significant range increase.

The Defiant employs the advancing blade concept and is configured with coaxial main rotors and a pusher propeller. Power is initially provided by two Honeywell T55 turbines, although a new FATE (Future Affordable Turbine Engine) powerplant is under development by GE Aviation for future application. The Defiant design is based on Sikorsky’s Schweizer-built X2 demonstrator, which has also spawned the smaller Sikorsky S-97 Raider demonstrator for the FARA (Future Attack and Reconnaissance Aircraft) requirement.

First flight for the SB>1 was originally scheduled for 2017 but was delayed at the request of the U.S. Army to incorporate automated fiber placement production technology in the construction of the main rotor blades. Sikorsky/Boeing hoped to fly the Defiant before the end of 2018, but that date has been pushed back into 2019 to enable the completion of comprehensive ground runs.

The Defiant is pitted in the JMR-TD program against the Bell V-280 Valor tiltrotor, which made its first flight in December 2017.

The SB>1 has a design speed of 250 knots with a range increase of around 60 percent compared with the UH-60 Black Hawk, although the extra range will only be achieved with the forthcoming FATE powerplant. (photo: Sikorsky)


My imagination goes wow, looks like good tech.... My conscious thought process goes OMFG what a maintenance nightmare. I can only imagine the check-flight profile requirements and vibration analysis criteria. Of course perhaps tech has helped with that.... is the TR/prop a viscous drive or an over-run clutch setup? What does the PCR and mixing system look like?............ does the counter-rotating MRH act as bifilar weight replacement/compensation?