Sikorsky-Boeing SB>1 Defiant exceeds 100 kt in recent flight

The Sikorsky-Boeing SB>1 Defiant coaxial helicopter exceeded 100 kt during a 13 January flight, the tandem announced on 17 January.

The aircraft, being developed for the US Army under its Joint Multi-Role Technology Demonstrator (JMR-TD) effort, also performed manoeuvres at a 30° angle of bank at the Sikorsky Development Flight Test Center in West Palm Beach, Florida. Sikorsky spokesperson Melissa Chadwick on 17 January declined to provide further details about the 13 January flight test.

Sikorsky-Boeing recently topped 100 kt speed with its SB>1 Defiant coaxial rotorcraft. The team may be struggling with rotor blade stiffness as stiff blades are required when coaxial rotors are close together. (Lockheed Martin)

Exceeding 100 kt is progress for the Defiant. It lags behind the Bell V-280 tiltrotor, which has exceeded 300+ kt. The V-280 also participated in JMR-TD, which Bell ended in September 2019.

Bell believes that speed is an inherent benefit of tiltrotor aircraft. Company spokesperson Mike Reilly said on 17 January that there is a great correlation between Bell’s analytical modeling and aircraft performance and the fidelity of its pre-flight systems integration laboratory and component testing. Bell, he said, was able to move quickly and achieve the 300+ kt speed owing to its experienced test flight programme leadership along with Bell and US Army test pilot confidence in the aircraft.

Although the SB>1 Defiant just recently exceeded 100 kt, the Sikorsky-Boeing team is focused on programme performance and continues to advance the aircraft’s rigorous flight test programme. Sikorsky and Boeing, Chadwick said, are very encouraged by the data they are collecting from their SB>1 flights and from the feedback they are receiving from their pilots. She declined further comment.