On June 9th, 2020, the Sikorskyâ€“Boeing SB>1 Defiant continued its test regiment and expanded the flight envelope, achieving 205 knots, surpassing the top speed of the legendary Black Hawk. Sikorsky Chief Test Pilot, Bill Fell remarked that this milestone is just the beginning and that the #SB1Defiant has “got a lot more in it.” Reaching new speeds in low level flight will be key to providing the U.S. Army the capabilities they need to dominate the multidomain battlefields of the future. Sikorsky, and partner Boeing, are proving the scalability and tailorability of Sikorsky’s Collier award-winning X2 Technologyâ„¢ through SB>1 DEFIANTâ„¢
The Sikorskyâ€“Boeing SB-1 Defiant (stylized as “SB>1”; company designation S-100) is the Sikorsky Aircraft and Boeing entry for the United States Army’s Future Vertical Lift program, succeeding the Joint Multi-Role initiative. It is a compound helicopter with rigid coaxial rotors, powered by two Honeywell T55s, and made its first flight on 21 March 2019. The Boeing-Sikorsky team is seen to have an advantage with their large industrial base that may result in wider support from Congress. Their transport helicopter designs are the most-used in the Army now, and the US Army has had little interest in the tiltrotor technology in Bell’s submission.
The design will have a cruise speed of 250 kn (290 mph; 460 km/h), but less range due to using the “old” T55 engine. A new engine, the Future Affordable Turbine Engine (FATE), is to meet the range requirement of 229 nmi (264 mi; 424 km). Compared to conventional helicopters, the counter-rotating coaxial main rotors and pusher propeller offer a 100-knot (115 mph; 185 km/h) speed increase, a 60% combat radius extension, and 50% better performance in high-hot hover performance. Dynamic systems like turboshafts, transmission, and rotors were scheduled to be tested at West Palm Beach, Florida, by the end of October 2018, before ground runs in November, then first flight to reach 200 knots (230 mph; 370 km/h) within six months.
Sikorsky has said that the X2 design is not suitable for heavy-lift size, and instead suggests the CH-53K for heavy-lift and tiltrotor for the ultra-class. Sikorsky plans to build the 30,000-pound-class (14,000 kg) JMR-TD (with a cabin 50% larger than the Black Hawk) at full scale to remove doubts about the scalability of the X-2 technology. Sikorskyâ€“Boeing states the SB-1 will be quick and nimble, with fast acceleration and deceleration, fast side-to-side movement, and the capability to hover with the tail up and nose down. The Defiant demonstrator will be powered by the Honeywell T55, which powers the CH-47 Chinook. It will be slightly modified to better operate at slower propeller speeds, down to 85% rpm.