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16 October 2020

Boeing-Sikorsky SB>1 DEFIANT

SB>1 DEFIANT is a modern, fully-integrated vertical lift aircraft being developed by Boeing and Sikorsky for the US Army’s joint multi-role (JMR) technology demonstration of the Future Vertical Lift (FVL) programme.
An artist’s impression of SB>1 DEFIANT in the battle field. Image courtesy of Boeing.
The SB>1 DEFIANT will have a cruise speed of 463km/h. Image courtesy of Boeing.
The aircraft will be equipped with X2 rigid co-axial rotor system. Image courtesy of Boeing.
The first flight of the SB>1 DEFIANT helicopter was made in March 2019. Credit: Sikorsky-Boeing.
The SB>1 DEFIANT helicopter is powered by two Honeywell T55 engines. Credit: Honeywell International Inc.

SB>1 DEFIANT is a modern, fully integrated vertical lift aircraft being developed by Boeing and Lockheed Martin company Sikorsky team for the US Army’s joint multi-role (JMR) technology demonstration of the Future Vertical Lift (FVL) programme.

The aircraft is intended to meet the attack and assault needs of the US Army, along with the long-range transportation, infiltration and resupply needs of the US Marine Corps.

SB>1 DEFIANT is capable of performing tight assault formations, close proximity landing, unique hovering, high-speed and low-speed flights due to its large angular rates and precision attitude control capabilities.

The project partners unveiled a SB>1 DEFIANT helicopter developed for Joint Multi-Role Technology Demonstration (JMR-TD) programme, a part of FVL programme, in December 2018. The helicopter made its first flight in March 2019, followed by public flight debut in February 2020.

The data from the helicopter will help the US Army develop new utility helicopters which are expected to be commissioned in the early 2030s.

SB>1 DEFIANT design and features

The next-generation aircraft will meet the future demands of the military, offering an optimal combination of speed, lift and range, with better agility and greater manoeuvrability. It is built with 85% commonality between attack and assault aircraft.

The fuselage of DEFIANT is made of composite materials for achieving superior strength and weight reductions. It integrates a retractable type landing gear for less drag during flight.

SB>1 DEFIANT is equipped with X2 rigid coaxial rotor system technology, which was tested aboard the X2 and S-97 Raider aircraft. Each rotor of the twin coaxial rotor system revolves in opposite direction and reduces the net torque of the other rotor in real-time.

Its rotor blades are made from composite material, which reduces vibrations and minimises wear of the components, while providing greater life and reduced maintenance costs. The aircraft is also equipped with the active vibrator control technology to dampen the vibrations from the rotors and deliver smooth lift and manoeuvrability.

The rear fuselage integrates a pusher propulsor with the clutch, enabling the aircraft to attain approximately twice the speed of a conventional rotorcraft. The pusher configuration also allows the aircraft to cover longer distances during the long-range missions, while advanced drive system ensures minimal transmission losses.

The manually foldable blades reduce the space requirements during parking, picketing, and transport. The aircraft fits in the footprint of a folded AH-1 when folded for shipboard stowage.

Avionics

SB>1 DEFIANT features a rotorcraft equipped with a fly-by-wire system, which can control the rotors, pusher propulsor, rudders, and elevators. Each rotor blade actuator is connected to the fly-by-wire technology to avoid any potential mechanical losses.

The active rudder and elevator controls can change the flight path of the aircraft with greater agility and ease. The aircraft also has options to employ weapons during all modes of flight.

Cabin details

The helicopter can accommodate 12 fully combat-equipped troops and four crew members. It also offers sufficient space for medical evacuation (MEDIVAC) operations.

SB>1 DEFIANT engine and performance

SB>1 DEFIANT is powered by a pair of Honeywell T55 engines, which offer fuel savings, reliability and maintainability.

The aircraft is capable of flying at a maximum speed of 250ktas (463km/h) and hover out of ground effect (HOGE) at an altitude of 6,000ft.

It has greater expeditionary range and endurance and is capable of carrying heavier payloads compared to the present generation rotorcraft.

The forward thrust offered by the pusher propulsor enables the aircraft to rapidly displace itself from the flight path in high-threat environments.

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