By Dan Parsons | January 25, 2021 Estimated reading time 10 minutes, 45 seconds. Sikorsky and Boeing have unveiled a refined vision of the Defiant compound coaxial helicopter, the team’s ultimate pitch to replace the U.S. Army’s Black Hawk helicopters with a speedy Future Long Range Assault Aircraft (FLRAA). The companies have released splashy renderings of the “Defiant X” and a video showing it performing demanding battlefield duty — cruising through forested ravines with an underslung artillery cannon, landing troops in combat formation — but were cagey with reporters about how the new design improves on the SB>1 Defiant prototype currently flying. The Defiant X, a version of the SB>1 coaxial compound helicopter optimized for aerodynamic efficiency and reduced thermal and acoustic signature. Defiant Team Image