Sikorsky-Boeing SB>1 Defiant completes initial ground run

The Sikorsky-Boeing SB>1 Defiant has completed its initial ground run and is now advancing through the ground testing activity in the build up to first flight, the program team has announced.


A first look at the initial prototype of the Sikorsky-Boeing SB>1 Defiant
The initial prototype of the Sikorsky-Boeing SB>1 Defiant, which weighs in at over 30,000 pounds. Sikorsky-Boeing Photo

“The joint Sikorsky-Boeing team is working rigorously toward a productive, informative flight test program that will inform the next generation of military helicopters as part of the U.S. Army’s Joint Multi-Role-Medium Technology Demonstrator [JMR-TD] program,” the manufacturers said in a joint statement.

The Defiant, a high-speed rigid rotor coaxial rotorcraft, is one of two medium demonstration helicopters for JMR-TD, a program that is anticipated to lead into the U.S. Army’s Future Vertical Lift program in the mid 2030s to replace the Sikorsky UH-60 Black Hawk and Boeing AH-64 Apache. The other is Bell’s V-280 Valor third-generation tiltrotor.


Based on Sikorsky’s cutting-edge compound technology, previously flown in the X2 and S-97 Raider, the Defiant has a clutched rear pusher prop in addition to its coaxial rigid rotors. Weighing over 30,000 pounds, it is designed to achieve high speed and long range, while improving maneuverability and survivability in a cost-effective package.

2 thoughts on “Sikorsky-Boeing SB>1 Defiant completes initial ground run

  1. My big question is on how this design and Square / cube law implications and overall hub sizes impacts flat plate drag of hubs and connecting shaft? Even with fairings and flying saucer or spinner covers that appear to need to be over 6′ in diameter – this design doesn’t appear to scale well for hub drag from X2 to Defiant to – this super medium – Defiant size? Appears like to get high cruise speed, there’s going to have to be some brute force power requirements, which will drive increased fuel consumption, loads, MTOW and a spiral to bigger GB, Shafts, Hubs, blades etc…

  2. A few years back at the Annual AHS Forum, Marat Tischenko Chief
    Engineer of the Mil Design Bureau said in the competitions between Mil and Kamov design bureaus, Mil Always won the Cargo Helicopter
    competitions because of payload and cruise efficiency. Kamov did a number special purpose helicopter models but no coaxial rotor transport helicopters.

    Go figure

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