Sikorsky, Boeing Debut Future Vertical Lift Dual-Rotor Design with SB>1 DEFIANT Helicopter

Being developed for the U.S. Army's Joint Multi-Role Technology Demonstrator (JMR TD) program, the medium-class technology demonstrator will help inform the next generation of military helicopters.

Sikorsky, a Lockheed Martin company (NYSE:LMT), in Stratford, Connecticut, and Boeing Defense, Space & Security (NYSE:BA) in Berkeley, Missouri, are introducing the SB>1 DEFIANT helicopter designed to fly with advanced agility and maneuverability at twice the speed and range of current conventional helicopters. Jointly developed for the U.S. Army’s Joint Multi-Role technology demonstrator program, the new rotorcraft design is intended to help inform the next generation of military helicopters as part of the U.S. Army's Future Vertical Lift (FVL) program.

Data from SB>1 DEFIANT will help the Army develop requirements for new utility helicopters expected to enter service in the early 2030s, officials say.

Sikorsky and Boeing are providing a first look at the new SB>1 DEFIANT helicopter, one of two designs participating in the U.S. Army’s Joint Multi-Role-Medium Technology Demonstrator Program. (Image courtesy Sikorsky and Boeing.)

The SB>1 DEFIANT Joint Multi-Role Technology Demonstrator (JMR TD) helicopter is Sikorsky’s third X2 aircraft in less than 10 years. It is being designed and built by Sikorsky and Boeing and will prove the scalability of the X2 design to a 30,000-pound class weight.

Sikorsky and Boeing engineers are proving the scalability and customizability of Sikorsky's Collier X2 Technology  through SB>1 DEFIANT, officials say. X2 Technology is designed to deliver speed, maneuverability, and scalability with improvements in vibration reduction, weight reduction, and blade technology that enables the aircraft to be flown by a single pilot, with a single engine. X2 Technology combines: dual, rigid, counter-rotating blades; integrated auxiliary propulsion; active vibration control; fly-by-wire flight controls; and hub drag reduction technologies.

A fully integrated aircraft that represents an evolution of the military’s most capable platforms, SB>1 DEFIANT is designed for the Army’s attack and assault missions as well as the Marine Corps long-range transportation, infiltration, and resupply missions.

Sikorsky and Boeing have designed the SB>1 DEFIANT to provide the right combination of speed, lift, and range that are paramount to both the assault and attack missions while increasing overall maneuverability and agility, officials explain. It was developed with 85 percent commonality between attack and assault aircraft to reduce development and life-cycle costs and ensure minimal disruption or loss of existing rotorcraftexpertise. Its open mission systems architecture allows rapid technology and capability insertion to meet evolving FVL requirements and provide the U.S. military with evolutionary sustainability, affordability, and readiness for years to come, they say.

The aircraft’s capabilities are largely derived from the X2 rigid co-axial rotor system, the airworthiness of which has been proven through flights of the X2 and S-97 Raider. With two coaxial rotors on top that rotate in opposite directions, the extra lift from each rotor’s advancing blade balances out the diminished lift from the opposite side’s retreating blade to eliminate retreating blade stall.

To provide the raw forward thrust for fast flight, the back of the SB>1 DEFIANT mounts a pusher propulsor, enabling the aircraft to fly twice as fast and twice as far as today’s conventional helicopter while increasing the overall maneuverability and agility required for specific mission objectives. This additional flight component also provides unique and unmatched maneuverability in all flight regimes including hover, low-speed flight, and high-speed flight.

The Sikorsky-Boeing SB>1 DEFIANT helicopter’s rotor system will enable it to fly about twice as fast and twice as far as today’s conventional helicopters. (Image courtesy Sikorsky and Boeing.)

The SB>1 DEFIANT is designed for upgradability and survivability in an open architecture environment, officials say, and features:

  • X2 Rotor System: A rigid, co-axial rotor system with pusher propulsor that provides improved mission objective capability, reduced wear on parts and systems, increased reliability and lower total lifecycle costs
  • Maneuverability and Agility: Improved agility and flight control augmentation allow tight assault formations with close proximity landings to deliver embarked troops as a cohesive unit and minimize exposure to hostile threats
  • Speed and Range: Twice the speed and distance of today’s conventional helicopters while increasing the overall maneuverability and agility needed for the military’s various missions
  • Survivability: Propulsor thrust coupled with large angular rates and precision attitude control enable the SB>1 DEFIANT to rapidly and precisely displace the aircraft position or flight path in response to threats or evolving tactical environments
  • Lethality: Rapid and precise acquisition of targets and prolonged engagement windows
  • Deployability: When folded for shipboard stowage, the SB>1 DEFIANT fits the footprint of a folded AH-1

The Future Vertical Lift (FVL) program will shape the U.S. military’s helicopter fleet of the future. Led by the U.S. Army, FVL will replace helicopters across the military through five different categories.

Sikorsky and Boeing are also partnered on the medium-lift aircraft for the U.S. Government's Future Vertical Lift program of record. The U.S. Government is expected to release the Request for Proposal for the medium-lift aircraft in 2019.

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Courtney E. Howard  is editorial director and content strategist at SAE International, Aerospace Products Group. Contact her by e-mail at This email address is being protected from spambots. You need JavaScript enabled to view it..