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Bell’s new attack helicopter concept looks like a bull shark with a 20mm rotary cannon in its mouth, with a sleek organic fuselage that should allow it to fly at more than 180 knots in forward flight.
Unveiled Oct. 1 at the company’s Advanced Vertical Lift Center outside Washington, D.C., the so-called “360 Invictus” is Bell’s pitch for the U.S. Army’s Future Attack Reconnaissance Aircraft (FARA). Bell is one of five companies competing for FARA. The others are AVX Aircraft, Boeing, Karem Aircraft, and Sikorsky.
Focusing on affordability, Bell has mustered its extensive experience and history building reliable, utilitarian military aircraft to pitch a less-exotic option for the U.S. Army’s new attack helicopter. The 360 Invictus tag is in line with the company’s naming scheme of a significant number followed by a glorious-sounding adjective. It also developed the V-280 Valor advanced tiltrotor (its target speed was 280 knots), the V-247 Vigilant unmanned tiltrotor, and the 525 Relentless.
Invictus’s somewhat conventional design is a single-main-rotor helicopter with a tandem cockpit. It borrows the rotor system from the 525, which the company notes has been flown at speeds above 200 kts in test flights. Both the shrouded hub and rotor blades have been “ported over” from the 525 program, but will be scaled to fit the Invictus, according to Keith Flail, vice president of advanced vertical lift systems at Bell. Where the 525 has five blades, Invictus will have four and will not exceed the Army’s 40-foot size limitation.
Invictus also will use a version of the 525’s fly-by-wire flight control system and features a modular, open-systems avionics system provided by Collins Aerospace.
The aircraft will be powered by a single GE improved turbine engine mounted aft and to the left of the main rotor hub. On the opposite side will sit a “supplemental power unit” that “engages with the drive system to provide additional horsepower when required to give us that extra power and speed we need,” Flail said. He declined to say if the SPU is required to reach the program target speed of 180 knots.
“It adds significant increase in horsepower,” Flail said. “Today, we’re not going to reveal more about how it engages with the drive system. We have a patent pending related to that.”
Another interesting and also unexplained design feature is the engine intake is on the left side of the fuselage and the exhaust ports out horizontally on the opposite side.
The aircraft should have a combat radius of 135 nautical miles with more than 90 minutes of time on station and achieve 4k/95F hover out of ground effect (HOGE).
At cruising speed, two “lift-sharing” wings, which are 24 feet tip-to-tip, will offload half the burden from the fully-articulated main rotors. Horizontal stabilizers controlled by the fly-by-wire system will keep the aircraft trimmed in the lowest drag position at high speed. The ducted tail rotor is canted to reduce drag and provide additional lift, Flail said.
Invictus will carry munitions internally and features retractable landing gear to further reduce drag at high speed.
The U.S. Army is developing FARA on a relatively swift timeline, with plans to field the aircraft by 2030. Two competitors should receive contracts in 2020 to build prototypes that will fly off against each other in 2023. The winning aircraft eventually will fill the armed scout role left vacant by the retired OH-58D Kiowa Warrior, now being performed by AH-64E Apaches teamed with RQ-7 Shadow drones.
Bell hasn’t built a prototype Invictus yet, but has tested a 17 percent scale model in a wind tunnel, Fail said. The company will showcase a full-scale mockup at the Association of the U.S. Army’s annual expo in Washington, D.C., later this month. Currently in preliminary design, Bell plans on flying a prototype aircraft in 2022.
“The team is progressing incredibly well as we’re heavily in to preliminary design,” Flail said. “We are fully staffed and executing this program with a lot of resources committed so that we get to 2022, looking for first flight for the aircraft.”
In designing Invictus, Bell was “laser focused” on affordability and meeting the Army’s tight development schedule, Flail said. Based on its experience with developing and flying the V-280 Valor tiltrotor under the Joint Multirole Technology Demonstration Program, Bell is confident it can meet the Army’s demand for prototype aircraft within three years and fire up a production line almost immediately afterward. The conventional Invictus configuration should help, Flail said.
“We certainly could have come up with other solutions,” he said. “But, to meet the requirements . . . we really wanted to focus on that simplicity and really drive complexity and risk out of it as much as possible. . . . You can have elegance without being exotic.”
That is a not-so-thinly veiled dig at Sikorsky and its S-97 Raider compound helicopter. Raider sports dual, coaxial rigid main rotors and a pusher prop, a configuration that has repeatedly reached speeds approaching 220 knots in flight test. Raider was developed specifically to replace the Kiowa Warrior, first flew in 2015 and is favored for FARA if only because it has been so extensively tested.
AVX is teamed with L3 and has revealed concept images of its design, also a coaxial main rotor helicopter. Karem is teamed with Northrup Grumman and Raytheon and likely will offer a tiltrotor design. Boeing has not revealed its FARA design.