On the second day of Christmas, Sikorsky and Boeing gave to the world two photographs of the SB-1 Defiant compound helicopter prototype, which has been completed and rolled out of the West Palm Beach, Fla., hangar where it was built.
The aircraft is one of two advanced vertical-lift prototypes participating in the U.S. Army’s Joint Multirole tech demonstration (JMR-TD) Program.
Two new photos show the coaxial, rigid-rotor design of the aircraft in detail. It has eight rotor blades, four each on two counter-rotating main rotors. An eight-bladed pusher propulsor — basically a backwards propeller — is affixed to the aft fuselage to provide forward thrust. The blades' pitch is variable to maximize thrust and perform quietly at high speed.
Defiant is designed to fly at twice the speed and range of today’s conventional helicopters and offers advanced agility and maneuverability. It will help inform the next generation of military helicopters as part of the U.S. Army’s Future Vertical Lift program.
The aircraft is expected to break contact with the ground for the first time in early 2019. Plans to fly in 2018 were delayed and then officially pushed into the New Year in a Dec. 12 call with aviation reporters.
It was only in the first two weeks of December that relatively minor engineering issues surfaced during ground runs of a mirror image of the aircraft bolted to the earth that the team was forced to inform the Army the aircraft would not fly by year end, Rich Koucheravy, Sikorsky’s director of business development and Randy Rotte, Boeing’s director of global sales and marketing for cargo helicopters and FVL, said during the call.
“As we develop this aircraft, we have a very deliberate process for getting to first flight,” he said. “We do have a couple of artifacts we continue to work on along with the Defiant build.”