Sikorsky-Boeing’s FVL Contender Takes Flight

March 25, 2019

William Kucinski

(Image courtesy: Lockheed Martin Corporation)

The Sikorsky -Boeing SB-1 Defiant (stylized as “SB>1 DEFIANT”) compound helicopter flew for the first time at Sikorsky’s West Palm Beach, Florida facility. Unlike current rotorcraft, the SB-1 Defiant’s propulsion system includes a rear-mounted pusher propulsor in addition to two coaxial main rotors. This unique setup allows the Defiant to reach speeds and a service range far beyond that of modern helicopters.

The aircraft, developed by Sikorsky Aircraft Corporation – a subsidiary of Lockheed Martin Corporation –and the Boeing Company, provides valuable insight into rotorcraft design and help inform the next generation of military helicopters as part of the U.S. Army ’s Future Vertical Lift (FVL) program. The FVL program aims to maximize control in strategic standoffs and exploit gaps created in complex “anti-access area denial systems” against near-peer adversaries.

“Defiant is designed to fly at nearly twice the speed and has twice the range of conventional helicopters while retaining the very best, if not better low-speed and hover performance of conventional helicopters,” says Dan Spoor, vice president of Sikorsky Future Vertical Lift. “This design provides for exceptional performance in the objective area, where potential enemy activity places a premium on maneuverability, survivability, and flexibility. We are thrilled with the results of today’s flight and look forward to an exciting flight test program.”

Read more: Sikorsky, Boeing debut future vertical lift dual-rotor design with SB>1 DEFIANT helicopter

Beyond achieving increases in speed and range of modern helicopters, Defiant’s design also improves maneuverability and survivability in a cost-effective way. The SB-1 incorporates technological advances from Sikorsky’s X2 Technology Demonstrator , which was developed from the Sikorsky S-69/XH-59 experimental coaxial compound rotorcraft. The unique rotor mast and hub shape reduces drag on the aircraft, which active vibration control and fly-by-wire controls contribute to ideal handling characteristics.

“The design and development of Defiant has revealed the capability advancement that is truly possible for Future Vertical Lift,” says David Koopersmith, vice president and general manager, Boeing Vertical Lift. “Clearly, the performance, speed, and agility of Defiant will be a game changer on the battlefield and we look forward to demonstrating for the U.S. Army the tremendous capabilities of this aircraft.”

The helicopter is participating in the U.S. Army's Joint Multi-Role-Medium Technology Demonstrator program. Data from Defiant will help the U.S. Army develop requirements for new utility helicopters expected to enter service in the early 2030s. This flight marks a key milestone for the Sikorsky-Boeing team, and is the culmination of significant design, simulation, and test activity to further demonstrate the capability of X2 Technology.

William Kucinski is content editor at SAE International, Aerospace Products Group in Warrendale, Pa. Previously, he worked as a writer at the NASA Safety Center in Cleveland, Ohio and was responsible for writing the agency’s System Failure Case Studies. His interests include literally anything that has to do with space, past and present military aircraft, and propulsion technology.

Contact him regarding any article or collaboration ideas by e-mail at This email address is being protected from spambots. You need JavaScript enabled to view it..