It is called “Defiant X”, a proposed refined version of the current Sikorsky and Boeing SB>1 coaxial compound helicopter. The design is the team’s ultimate pitch to replace the US Army’s UH-60 Black Hawk helicopters with a speedy Future Long Range Assault Aircraft (FLRAA).
Images of Defiant X reveal a noticeably pointier nose cone, relocation of the engine exhaust outlet from aft of the main rotor assembly, lateral reshaping of the airframe and tail boom and chevron-style tail fins. All are enhancements are meant to reduce Defiant’s thermal signature and improve aerodynamic handling. Improved stability during landing and taxiing is obtained by a conventional tricycle-style nose wheel landing gear replacing the tail dragger landing gear of the SB>1.
The signature coaxial, counter-rotating main rotor system and eight-bladed aft pusher propeller configuration remain essentially unchanged. The prototype of the SB>1, N100FV made its first flight on 21 March 2019.
The Defiant X main competitor in the race for an FLRAA contract is the Bell V-280 Valor advanced tiltrotor. The prototype of this design, registered N280BH made its first flight already on 18 December 2017. Both designs resulted from the Joint Multirole Technology Demonstration (JMR-TD) program the US Army launched in 2013. The current demonstration aircraft and using the data collected to refine their FLRAA pitches under competitive demonstration and risk reduction (CD&RR) contracts awarded by the Army.
Artist impressions: Sikorsky-Boeing