Wednesday, 2 October 2019

The Army’s Next Attack Helicopter Could Look Like This

Bell

The Army’s Next Attack Helicopter Could Look Like This - Defense One:

Bell’s new 360 Invictus is the latest entrant hoping to fill the Army’s vertical-lift gap — and it’s remote-controlled.

After spending much of the past decade almost exclusively building and developing tiltrotor aircraft for the U.S. military, Bell is returning to its roots, pitching the U.S. Army a traditional helicopter for attack and reconnaissance missions.

The Textron company on Tuesday unveiled the Bell 360 Invictus, with a sporty-looking, new design that executives say is based on existing commercial technology, keeping it cheap to fly and maintain.

“If you need … and can afford a Corvette, do you go buy a Ferrari,” Jeffrey Schloesser, executive Bell’s vice president of strategic pursuits, said during a briefing in Arlington, Virginia. “This is not a truck. This is a high-speed, agile aircraft at an affordable price that meets all the requirements from the U.S. Army.”

Bell is one of five teams building prototypes for the Army, which wants to replace the OH-58D Kiowa Warrior helicopter it retired in 2014. The Army is calling its next-gen helicopter the Future Attack Reconnaissance Aircraft, or FARA.

As with most new weapons, Army officials want better performance: a new aircraft that is faster, can fly farther and carry more weapons than Kiowa, and that can be used to fight terrorist threats. It also is meant to fill “gaps in Army aviation attack and reconnaissance,” the Army said in April when it awarded the five teams contracts to build prototypes.

The helicopter is being built for battles in dense environments, like cities. While there are seats for two pilots, as the Kiowa had, Bell’s helicopter is being built to be flown remotely with no one in the cockpit.

Bell officials expect the new helicopter will fly by the fall of 2022, light-speed for the military and for an industry that tends to measure aircraft development programs in decades. Executives believe it’s the fastest the company has designed and built a new military helicopter from scratch.

“This is extremely fast paced,” Keith Flail, Bell’s vice president of advanced vertical lift systems, said Tuesday. “Focusing on simplicity and keeping the complexity and the risk out of it as much as possible is really important.”

The company chose a standard helicopter design over a tiltrotor — like the V-22 Osprey or V-280 Valor that the company is developing for a separate Army effort — for several reasons. Most importantly, a helicopter is cheaper to build and fly.

At first glance, the Invictus bears a striking resemblance to the Comanche, a stealth helicopter the Army tried to field some 20 years ago. Compared to today’s military helicopters, the Invictus has a sportier look. One reporter in the room said the helicopter’s sleek design resembled a shark.

Similar to the Apache attack helicopter, the Invictus has a 20-millimeter gun mounted under the nose. Like stealthy fighter jets, it will carry some of its missiles and rockets internally. A computer-generated animation showed the aircraft with motorized doors opening to reveal weapons inside, which then fold out.

In an attempt to lower the cost, the Invictus uses parts from other Bell aircraft.

“We are leveraging a lot of key technologies from the 525 program.” The Bell 525 Relentless is a medium-lift helicopter that Bell is developing for commercial customers.

For example, the rotors on the Invictus are a version of the rotors used on the Bell 525.

“You can have elegance without being exotic,” Flail said. “It’s up to us to bring [the Army] the most affordable, most sustainable solution that meets their requirements — and this absolutely will.”

Bell already is conducting wind tunnel tests on a 17-percent scale model.

The helicopter’s name — 360 Invictus — is a play on special electronics that will allow the two pilots to see threats all around the aircraft.

“This has to be out there in the fight gaining and maintaining contact with the enemy — the calvary mission that the United States Army has been doing since horseback,” Flail said. “It’s the out-front scout that can’t be defeated.”

The company plans to show off a full-scale model of the aircraft at the Association of the United States Army conference and trade show in Washington, D.C., later this month.

In addition to Bell, the Army has contracted Boeing, Lockheed Martin (Sikorsky), Karem Aircraft and a team of L3Harris Technologies and AVX Aircraft to build prototypes.

L3Harris’ unveiled its design in April. Lockheed’s design will be based on its X2 technology and informed by the S-97 Raider, which is in flight-testing today.

Bell 360 Invictus

Bell

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. Source: flightglobal.com