Image Credit: Sikorsky/Boeing

When it comes to military aircraft, vehicles and other emerging technologies, the Sikorsky-Boeing SB>1 Defiant is the future. This next-generation military helicopter shows just what today’s technologies and advanced systems are capable of. After years of research and development, Sikorsky and Boeing have revealed their master plan for the latest in military aircraft.

Tried and Tested Military Aircraft

While the SB>1 Defiant is a future concept, the idea stemmed from Sikorsky’s X2 Technology Demonstrator as far back as 2008. The X2 performed 23 test flights at Sikorsky’s Innovations Center in Florida between 2008 and 2011 totalling 22 hours. All the practice paid off as the X2 reached a maximum cruising speed of 253 knots in level flight. It was an unofficial record for conventional helicopters.

Even though the X2 project ended in 2011, it had achieved more than what anyone could have anticipated a decade later. The valuable lessons learned enabled them to develop the required technologies for future military aircraft. Before the SB>1 Defiant, Sikorsky launched a high-speed scout and attack S-97 Raider helicopter in 2015 based on their Advancing Blade Concept.

In 2017, Lockheed Martin gave us a taste of what to expect from future military aircraft based on the X2. Along with their subsidiary, Sikorsky Helicopters, Lockheed Martin started development of their Future Vertical Lift concept. They planned to develop Assault and Attack variants offering unmatched manoeuvrability, speed and longer range.

SB>1 Defiant Military Aircraft

The SB>1 Defiant helicopter is a joint multi-role medium-class Future Vertical Lift technology demonstrator based on Sikorsky’s X2 platform. It uses two counter-rotating rigid blades at the top which eliminates the retreating blade stall issue. This is a problem that single top rotor helicopters have to contend with hence their speed limit of +-150 mph (+-240 km/h).

In laymen’s terms, when a helicopter is in a stable hover with no ambient wind, the top blade generates an equal amount of lift during its rotation around the central axis. However, when they start moving forward, the blade develops extra lift on the side where it rotates forward into the wind. The other side works the opposite as the blades rotate backwards with the wind producing less lift. This often results in an unbalanced flight that could threaten to tip the helicopter if it exceeds the predetermined maximum airspeed.

The success of Sikorsky’s technology is no longer a secret as it is very simple in theory. Using two main rotors on top of one other that rotate in opposite directions increase lift balance and also allows the helicopter to fly faster. In fact, this futuristic military aircraft can fly up to twice the airspeed of regular helicopters without compromising on handling or agility.

Furthermore, it eliminates the need to for a regular tail rotor because the top rotors can now manage the yaw on their own. Instead, the SB>1 Defiant uses a pusher prop as well as active rudders and elevators. The aircraft can now take off and move away quickly without having to tilt forward first. When travelling at higher speeds, the rear push prop provides extra power while the rudders and elevators are responsible for high-speed manoeuvring.

Next-Generation Design And Development

Adding even further value, the Defiant will have retractable landing gear to help reduce drag for reaching higher speeds. This results in more efficient flying and leads to a much longer range than convention helicopters. The twin-rotor system minimises downwash when getting on and off while also dramatically reducing the acoustic signature. To top it all off, the top rotors can also be folded back when on the ground allowing for easy storage and transporting.

A summary of the latest features on the SB>1 Defiant include the following:

  • Fly-by-wire flight controls
  • Advanced rigid rotor system
  • Lift offset co-axial rotor
  • Advanced drive system
  • Active vibration control
  • Foldable rotor system
  • Pusher prop with clutch, active rudders and elevators
  • All-composite fuselage
  • Weapons employment in all modes of flight

In addition to all the technology, the Assault variant will have cabin space for 4 crew members and 12 fully-equipped combat troops. An Attack variant will use a similar drivetrain, vehicle management systems among others but it will have a different fuselage with heavier armour. It could even double as a medevac unit with enough space to transport and provide lifesaving support for up to eight people.

Enhanced Performance

According to Lockheed Martin, the concept could cruise at over 250 knots or 288 mph (464 km/h). What makes it even more fascinating is the advanced hovering capability even at altitudes of 6,000 ft (1,800 m) and in temperatures of 92° F (33° C).

In addition to improved speed and range, this future military aircraft also offers greater payload capacity compared to conventional helicopters. As yet, there is no confirmation on maximum payload or when it will enter service although some suggest around 2030.

Here’s a closer look at the concept video courtesy of Sikorsky and Lockheed Martin.

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