The Bell 360 Invictus is a proposed helicopter design intended to meet the US Army requirement for a Future Attack Reconnaissance Aircraft (FARA). It is based on the Bell 525 Relentless.

Design

Scott C. Donnelly, CEO of Textron, has said in April 2019 that the 360 will be based on the 525.

The design was unveiled on 1 October 2019, showing a two seat tandem cockpit, with sighting optics and/or laser designator above a 20mm cannon gun turret at the chin position below the cockpit, mid-mounted stub wings below the shrouded rotor hub and four 40 foot (12 m) diameter rotor blades, an active horizontal stabiliser and a tilted and shrouded tail rotor. Missiles are mounted on pylons off the fuselage, below the stub wings. It will be powered by two of the Improved Turbine Engine Program (ITEP) engines by General Electric.

The US Army requirement calls for a speed in excess of 180 knots (330 km/h), and the 525 and 360 are intended to meet this. The stub wings are intended to take about 50% of the weight of the aircraft at moderate to high speed. Combat radius will be 135 nanometres (1.35×10⁻¹⁰ km) with at least 90 minutes time on station. It will use fly by wire control.

Bell intends to unveil a full-scale mockup of the 360 at the Association of the United States Army annual show beginning 14 October 2019.

Presentation

Bell has unveiled its proposed single-rotor design for the U.S. Army’s Future Attack Reconnaissance Aircraft (FARA), a cutting-edge helicopter that may be optionally manned.

The ‘360 Invictus’ helicopter will be loaded with a 20 mm cannon and integrated munitions launcher able to carry Hellfire missiles or rockets. It will be able to adapt for future weapons integration in order to fight in urban environments, according to Bell.

Bell showcased its design to reporters at its facilities in Arlington, Virginia on Tuesday.

“The Army realized that they absolutely do need a smaller aircraft that’s … able to operate in urban canyons as well as out in mixed terrain,” said Jeffrey Schloesser, executive vice president for strategic pursuits at Bell.

Schloesser said the 360 Invictus has high-cruise speeds, long-range capabilities and advanced maneuverability, all intended to help it dominate a future battle-space.

“We have a solution that can accomplish those missions, but it’s also the lowest-risk, and therefore probably the lowest-cost aircraft, to be able to accomplish [that],” Schloesser said.

Keith Flail, vice president of advanced vertical lift systems, said the agile helicopter’s first flight is expected in the fall of 2022. It should be able to fly at speeds greater than 180 knots true airspeed, or more than 200 miles per hour; the aircraft will also have a supplemental power unit that can boost the aircraft’s speed in flight.

Loosely based on Bell’s 525 Relentless rotor system, the fly-by-wire computer flight control helicopter will be made in partnership with Collins Aerospace which will deliver a new avionics hardware and software suite. “[Collins] also has the ability to integrate capabilities with the MOSA, or modular open system architecture, onto the aircraft,” Flail said.

Some observers at Tuesday’s event remarked how the streamlined, lightweight fuselage design of the 360 Invictus resembled the body of a shark, particularly the vertical canted ducted tail rotor, designed for optimized lift and propulsion.

“As we’re in the wind tunnel, as we’re looking at performance, as we’re looking at drag, everything on the aircraft, we’re very confident that we have a good story on … that design target,” Flail said.

In April, the Army awarded Bell, a subsidiary of Textron, the contract to begin prototype and design work; but the company must compete against four other firms before the service down-selects its options to move forward with its future helicopter.

They are: AVX Aircraft Co. partnered with L3Harris Technologies; Boeing Co.; Lockheed Martin’s Sikorsky; and Karem Aircraft.

Currently, the Army is developing FARA and the Future Long Range Assault Aircraft (FLRAA) along with other airframes as part of its larger Future Vertical Lift initiative, or FVL.

FVL, the Army’s third modernization priority, is intended to field a new generation of helicopters before 2030.

Flail said that Bell will have a full-scale model of its FARA design, which fits inside a C-17 Globemaster III for transport as well as a 40-foot CONEX box, at the annual Association of the U.S. Army show later this month.

History

The US Army is working to a rapid timeline, with a plan to develop, flight test and field its next-generation reconnaissance aircraft by 2028. It anticipates awarding two teams contracts in 2020 to build prototypes, with a fly-off competition in 2023. FARA would be a replacement for the service’s retired fleet of Bell OH-58D Kiowa Warriors.

Bell’s 360 Invictus borrows the rotor system of the 525 Relentless, a super-medium-lift commercial helicopter designed to transport up to 19 passengers and aimed at serving the oil and gas industry. The twin-engined 525, which has a fully articulated rotor with five composite blades, is still undergoing Federal Aviation Administration (FAA) certification testing.

The 360 Invictus rotor system and airframe would be significantly smaller than the 525, however. With seating for only a pilot and gunner sitting in tandem, the single-engined aircraft would have only four blades, although Bell declines to say what they will be be made from.

Its smaller size is in part meant to meet the US Army’s requirement for an aircraft with a maximum diameter of 12.2m (40ft) – a specification meant to allow the FARA to manouevre between buildings in urban battlefields.

Bell notes that the 525’s rotor system has been tested at speeds above 200kt (371km/h), though it advertises the Invitus’s speed as more than 185kt. The US Army wants FARA to have a cruise speed of at least 180kt.

“Certainly with our configuration there’s opportunities to continue to mature or block upgrade the aircraft [speed], if they want more capability,” says Frank Lazzara, director of advanced vertical lift systems sales and strategy at Bell. “But, we’re trying to ensure that the focus stays on the affordability and sustainability.”

The helicopter’s wing would provide up to 50% of lift when the aircraft flies at 180kt, allowing the articulating rotor to translate more power into forward movement, he adds.

“The high flapping capability is a very efficient propulsor that it is not bearing the lift load,” says Lazzara.

Designed with a combat radius of 135nm (250km) with more than 90min of time on station, the aircraft should be able to hover out of ground effect at 4,000ft at 35°C (95°F), says Bell.

To reach high speeds, Bell has streamlined the 360 Invictus’s profile with internal weapons carriage, main rotor shroud, retractable landing gear and a ducted tail rotor, which is also canted.

“The canted tail rotor allows for additional capability in a hover,” says Lazzara. He adds that the ducted tail rotor is also more efficient, thus saving power for the main rotor, and is safer for ground operation.

The helicopter also has a patent pending “supplemental power unit,” which the company declines to discuss in detail.

“Advanced aircraft need auxiliary power capability,” Lazzara says. “So, the team found a way to get auxiliary power on the aircraft that literally bought its way onto the aircraft by being able to contribute to the main horsepower solution in forward flight.”

The helicopter would also have a horizontal stabilizer that is controlled by a fly-by-wire flight-control system.

“In forward flight, the flight-control computers would be constantly adjusting the horizontal stabilizer, keeping the aircraft in an attitude that provides the best drag configuration,” says Lazzara.

The company says the fly-by-wire flight control system ought to reduce pilot workload and provide a path to adding autonomous flight capabilities later. Bell says the helicopter would have modular and open systems, with Collins Aerospace supplying avionics hardware and software.

Bell describes the 360 Invictus’s reliance on the 525’s rotor system as a low-risk route for the US Army, claiming that it has high technology and manufacturing readiness levels. However, the commercial 525, which was due to enter service several years ago, has been delayed a number of times and is still finishing the final stages of the FAA certification process.

Bell is also critical of more complex designs, which it says come with inherent cost. This is a veiled swipe at leading competitor Sikorsky, whose S-97 Raider co-axial compound helicopter is widely viewed as the favorite in the FARA competition. The Raider first flew in 2015 and has achieved speeds above 200kt in test flights.

“The cost of operation for VTOL aircraft typically comes down to gearboxes and blades,” says Keith Flail, vice-president of advanced vertical lift systems at Bell. “Typically, the dynamic components are the primary cost drivers on aircraft.”

Of course, Bell is also pitching the V-280 Valor tiltrotor for the US Army’s other Future Vertical Lift competition: the Future Long-Range Assault Aircraft (FLRAA) programme, which is intended to replace the UH-60 Black Hawk. The V-280 relies upon a drive shaft that rotates with its two rotor blades to transition from vertical to horizontal flight.

Moreover, the V-280 has been flying since 2017 and Bell has often noted its flight time is an indication of the programme’s maturity, accumulated testing experience which inherently reduces risk to the US Army should the service contract the company to manufacturer the tiltrotor en masse at the conclusion of the FLRAA competition.

However, because the 360 Invictus is still in the preliminary design phase and not scheduled to fly before the latter part of 2022 it would start out at least six years behind the flight testing programme of the Sikrosky S-97 Raider. Despite being behind Sikorsky’s effort, Bell believes it can rapidly catch up should it start flying three years from now.

“We have a very good process to get the first flight, and then get to second flight faster, and third flight and fourth flight,” says Flail, noting that he believes streamlined digital design and manufacturing processes within Bell can help the company achieve a rapid testing tempo. He cites the Bell V-280 as an example of that tightly integrated design and manufacturing system working well.

The Bell 360 Invictus is designed as an attack helicopter with a 20mm cannon and munitions launcher that can be integrated with air-launched effects and other future weapons.

Because the US Army does not explicitly require a utility variant for FARA, Bell is not presenting its helicopter in that configuration. However, the company says the way the helicopter is laid out means it could be reconfigured to a utility version, allowing for the two variants to share parts, similar to the UH-1Y and AH-1Z, which have 85% commonality.

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