The Sikorsky-Boeing team has begun ground tests on a prototype of the SB>1 Defiant high-speed,co-axial compound helicopter that is being built for the U.S. Army.

Developing team begun ground tests on a prototype of the high-speed SB>1 Defiant helicopter, the production of which has been completed by Sikorsky, a Lockheed Martin company, and Boeing months ago.

The SB>1 Defiant is designed to fly at twice the speed and range of today’s conventional helicopters and offers advanced agility and maneuverability. It will help inform the next generation of military helicopters as part of the U.S. Army’s Future Vertical Lift program.

The SB>1 Defiant’s successfully restrained ground run test operations, marks a major milestone ahead of the first flight, which is expected in early 2019.

Developed with 85 percent commonality between attack and assault aircraft, the SB>1 Defiant will reduce development and life-cycle costs and ensure minimal disruption or loss of existing rotorcraft expertise. Its open mission systems architecture allows rapid technology and capability insertion to meet evolving FVL requirements and provide the U.S. Military with evolutionary sustainability, affordability and readiness for years to come.

The aircraft’s capabilities are largely derived from the X2 rigid co-axial rotor system which has already proven its airworthiness through flights of the X2 and S-97 Raider.

With two coaxial rotors on top that rotate in opposite directions, the extra lift from each rotor’s advancing blade balances out the diminished lift from the opposite side’s retreating blade to eliminate retreating blade stall.