Sikorsky-Boeing's SB>1 Defiant loses out on army contract

Designed for speed with a cruise capability of up to 250 knots (288 mph), the SB>1 used a coaxial rotor system and rear-mounted pusher propeller to exceed traditional helicopter speeds. However, this was not enough to secure the FLRAA contract as the Bell V-280 Valor offered superior range and speed aligned with future operational needs.

Constructed from composite materials lighter than traditional metals, the SB>1 aimed for increased durability and reduced weight to improve fuel efficiency and mission range. According to All Sciences Proceedings: "Weight Reduction: Lower overall weight means better fuel efficiency and longer mission range." Despite these advantages, the V-280’s tiltrotor configuration provided greater efficiency for long-range missions.

The unique coaxial rotor and pusher propeller design eliminated the need for a tail rotor while improving lift efficiency and forward speeds. Lockheed Martin stated: "Increased Lift Efficiency: Coaxial rotors generate more lift in hover and forward flight."

Although designed for future warfare with features like advanced drive systems and fly-by-wire controls, Lockheed Martin noted that despite its strengths: "the US Army ultimately chose the Bell V-280 Valor for its greater range." The SB>1 now resides at Fort Novosel's Army Aviation Museum in Alabama.

While not entering service with the US Army, insights gained from developing this ambitious helicopter will likely influence future military aviation advancements.