Sikorsky for decades has been developing and testing X2 technologies that have proven a coaxial main-rotor helicopter can fly as fast or faster than a turboprop airplane. That investment has resulted in the S-97 Raider and SB>1 Defiant that are competing against equally robust prototypes to be the future of military rotorcraft. The chief engineer on all of those programs and the test pilot who flew them speak to Vertical.