Aircraft

First look at ultra-fast Sikorsky/Boeing SB>1 Defiant dual-rotor helicopter

The Sikorsky/Boeing SB>1 Defiant is our first look at the Future Vertical Lift project that will enter US Army service in the 2030s
The Sikorsky/Boeing SB>1 Defiant is our first look at the Future Vertical Lift project that will enter US Army service in the 2030s
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With counter-rotating blades at the top, the SB>1 Defiant blasts through the helicopter speed limit imposed by retreating blade stall on single-rotor helicopters
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With counter-rotating blades at the top, the SB>1 Defiant blasts through the helicopter speed limit imposed by retreating blade stall on single-rotor helicopters
The Sikorsky/Boeing SB>1 Defiant is our first look at the Future Vertical Lift project that will enter US Army service in the 2030s
2/2
The Sikorsky/Boeing SB>1 Defiant is our first look at the Future Vertical Lift project that will enter US Army service in the 2030s

Sikorsky and Boeing have been working on this high-speed, long-range, ultra-maneuverable military helicopter design for some time, and now they've released the first photos of what is expected to become a highly effective US Army utility helicopter sometime in the 2030s.

The SB>1 Defiant is a joint multi-role medium-class Future Vertical Lift technology demonstrator built around Sikorsky's X2 platform, which uses two counter-rotating rigid blades on the top of the aircraft to eliminate the retreating blade stall problem that puts a ~150 mph (~240 kmh) speed limit on helicopters with a single top rotor.

Putting it simply, at a stable hover with no ambient wind, a helicopter's top blade generates an equal amount of lift throughout its whole rotation around the central axis. But when you start moving forward through the air, the blade starts developing extra lift on the side where the blades are rushing forward into the wind, and less lift on the opposite side where the blades are going backwards with the wind. This can get so unbalanced that it threatens to tip the helicopter over altogether if you don't stay beneath a defined maximum airspeed.

Sikorsky's technology puts two main rotors on top of each other, rotating in opposite directions, which balances out the lift profile on either side and allows the craft to fly much faster – up to twice the airspeed of a regular helicopter – while maintaining excellent handling and agility.

With counter-rotating blades at the top, the SB>1 Defiant blasts through the helicopter speed limit imposed by retreating blade stall on single-rotor helicopters
With counter-rotating blades at the top, the SB>1 Defiant blasts through the helicopter speed limit imposed by retreating blade stall on single-rotor helicopters

It also negates the need for a regular tail rotor, as yaw can be managed using just the top rotors. The SB>1 Defiant uses a pusher prop at the rear, along with active rudders and elevators. At takeoff, this means the aircraft can lift off and move away quickly without needing to tilt forward. At higher speeds, the rear prop provides extra drive and the rudders and elevators help with high speed maneuvering.

The Defiant will have retractable landing gear, reducing drag to allow higher speeds at greater efficiencies, leading to longer range. Its twin rotor system will minimize downwash as you get on and off, and Sikorsky also claims a "dramatically reduced acoustic signature." On the ground, the top rotors can be folded back, allowing it to be stored and transported easily.

When it enters service, the Defiant will carry a crew of four and a cabin equipped for up to 12 combat-ready troops or eight medevac litters. That's in an assault configuration; there will also be an attack variant that shares a common fly-by-wire drivetrain and many other systems, but has a different composite fuselage and is much more heavily armed.

Take a look at the concept video below, or click through for a larger look at the photos released today.

Source: Sikorsky/Boeing

Sikorsky - Boeing Future Vertical Lift: The Way Forward

21 comments
fb36
Why not a similar size quadcopter design (similar to drones)? (Each propeller may have an electric motor & electricity could be provided by a central gas turbine engine (that also provides extra forward thrust)!)
noteugene
They will be coming soon I'd imagine fb. About the develemental phase when you already have a proven concept, insane. Move it up to 2023. This would be great for turbulant rescues, say at sea.
physics314
Rediscovering the wheel, here? Kamov has been making dual contrarotating rotor helicopters since the 1940-s.
Nelson Hyde Chick
If only we devoted as much time, money and resources to fixing the planet as we do to making systems to kill one another we might save the planet.
Captain Danger
Up to twice as fast as a regular helicopter. Airwolf would still eat it for breakfast.
Derek Howe
Nelson Hyde Chick - this will likely be used for more then just war. They will likely sell it in the commercial market as well.
ljaques
Pretty cool copter. My teeth went on edge when I heard that commentator's voice. Egad. Buy a clue, Sikorsky. The arrogant sales hype can't be good for sales.
toyhouse
Been watching the x2 program progress for the last few years. When they showed footage of it in a high speed run and posted the numbers, you knew it was the future. For fb36 wondering why not a quad? - four smaller disks have a smaller effective lifting area than a single large disk, all things being equal. And lifting payload is a biggie for the mission profile. This design delivers that, plus incredible speed. Counter rotating props certainly aren't new. But in this configuration and design - they are. And civilian uses are already being considered. These will be effective at getting injured people out of remote areas quicker and also, the ability to possibly commute further without having to go through a transit hub. Nothing political here. Just innovation.
Towerman
Bring back the COMANCHE ! That is a helicopter, not this bulky overly complexed strange concept idea worked into a "commercial" vehicle
Towerman
+1 fb36