Sikorsky-Boeing-Defiant-03212019-First-Flight-1 The Sikorsky-Boeing SB>1 DEFIANT; helicopter achieved first flight March 21, 2019. With its two coaxial main rotors and rear-mounted pusher propulsor, DEFIANT is unlike production rotorcraft available today. Photo courtesy Sikorsky and Boeing. 2019.03.222019.10.17