The prototype SB>1 Defiant. (Sikorsky-Boeing)

The prototype Sikorsky-Boeing SB>1 Defiant compound helicopter has been rolled out at West Palm Beach in Florida.

The rollout comes less than a month after the planned first flight of the SB>1 was pushed back from 2018 into early 2019 which Sikorsky-Boeing attributed to faults found during ground testing, and subsequent repairs.

The SB>1’s rigid coaxial main rotor and pusher prop allow faster speeds and longer range than conventional helicopters. (Sikorsky-Boeing)

The SB>1 is Sikorsky-Boeing’s bid for the US Army’s joint multi-role-medium (JMR) technology demonstrator trial for its future vertical lift (FVL) program. The aircraft features a counter-rotating coaxial rigid main rotor system and an eight-bladed pusher propeller at rear, the same configuration successfully tested on the smaller X-2 and S-97 Raider testbeds. The S-97 has achieved more than 230 knots airspeed in level flight.

The JMR will pit the SB>1 against Bell’s V-280 Valor tilt-rotor which has been flying since 2017 and seeks to improve the range and speed of the venerable Sikorsky UH-60 Blackhawk substantially from 2030.

An artist’s impression of the SB>1 in flight. The engine exhausts and lower fuselage shaping shown in the concept differ from those of the prototype. (Sikorsky-Boeing)