Bell's New Army Rotorcraft Programs Charging Ahead

 - March 23, 2021, 6:05 AM
Bell has begun assembly on the FARA prototype, the two-seat 360 Invictus, at its Amarillo, Texas, facility, while it has accrued 200 flight hours on its FLRAA semi-finalist candidate, the V-280 Valor tiltrotor. (Artist rendering: Bell)

Semi-finalist Bell is moving ahead with its entries into the U.S. Army’s FARA (future attack reconnaissance aircraft) and FLRAA (future long-range assault aircraft) rotorcraft competitions. 

At Bell’s plant in Amarillo, Texas, assembly has begun on the FARA prototype, the two-seat 360 Invictus, according to Chris Gehler, Bell vice president and FARA program director.  “It looks like an aircraft now,” he said, noting that the helicopter already has had the mission rails, weapons bay, wing stubs, and skins attached. Bell has already built the flight blades following development testing and flight verification. The drive system is being assembled at Bell’s main plant near Fort Worth. Bell is aiming to have the aircraft put together by the end of this summer, perform ground runs one year later, and then make first flight by fall 2022. 

Meanwhile, Gehler said a ground-based simulator known as “aircraft zero” in Bell’s systems integration lab (SIL) will come together over the course of this summer as work is well underway on the flight control, avionics, and electrical benches as well as the hydraulic actuation and power components in the rig room. “The ‘cockpit’ inside the SIL really ties everything together and that will really be our ‘first flight,’” Gehler said. 

The SIL is similar in concept to what Bell used to develop the 525 Relentless super-medium civil helicopter and the larger V-280 Valor tiltrotor the company is campaigning for the Army’s larger Future Long-Range Assault Aircraft (FLRAA) program. All three programs are developing aircraft with fly-by-wire flight controls and have a certain degree of technological overlap, Gehler said. “The integration between the V-280 and the 360 is nearly identical—they use the same boxes for the flight computers, but the software is obviously a little different. Before we fly a test flight in the actual aircraft, we fly it in the SIL. Everything in the SIL is in that aircraft.”

The 11,000-12,000 pound (mission empty weight) 360 is designed with the same open architecture of the V-280. The conventional helicopter design will be powered by one GE T901 ITEP (improved turbine engine program) 3,000-shp turboshaft with a 598-shp Pratt & Whitney PW207D1—the same engine used on the Bell 429 light twin—serving as a supplemental power unit (SPU). 

Gehler said the SPU functions much like “sport mode” in a high-performance automobile. As opposed to a conventional—and smaller—traditional auxiliary power unit (APU) that provides untethered aircraft ground power and is then shut off, the SPU not only fulfills that role but also supplements aircraft performance in cruise or hover modes. “If the mission calls for higher gross weight or higher speeds then it is available to you,” Gehler said. “It is clutched in and out on the ground, you can turn it on and off in flight. In the event of failure of main ITEP engine, the SPU can control the main rotor for a much better autorotation descent and things like that. But the 360 is not a twin-engine aircraft. We are using an SPU in a weight-neutral way that gives the warfighter the use of that power in various modes of flight and in emergency situations.”

The T901 is designed to be used in FARA aircraft as well as being retrofittable into the existing Black Hawk and Apache fleets. GE claims that it delivers 50 percent more power, 25 percent better fuel economy, and 20 percent greater engine life than the T700 engine it will replace. The design combines the single spool architecture of its current T700 with ceramic composites found on GE’s new generation commercial jet engine models including the CFM LEAP in a way that lowers weight and increases performance and efficiency. The engine is being provided to Bell directly by the Army. The service branch announced in September that the engine had completed critical design review and that the first engine would begin testing in Q4 this year as a precursor to delivering it to FARA competitive prototype (CP) aircraft—Bell’s 360 and Sikorsky’s Raider X, a compound, coaxial design. 

Gehler said Bell expects to receive the first T901 in early 2022 and is already receiving engine software drops for the SIL and e-simulator to facilitate tuning the flight controls with the engine. Right now the schedule’s target is for ground runs to begin in summer 2022 with the first flight of the 360 shortly thereafter. 

The 360 is designed to “live in the mud,” Gehler said, stressing its maintainability. “The Army chose us because we are the low-risk, low-complexity, and low-cost option. They want this platform to be able to live in the mud for long periods of time, maintenance-free. We want to be able to see the aircraft operate for 30 days without any significant scheduled service. So we stuck with tried and true technologies and added modern fly-by-wire controls. We kept complexity out of the airplane,” he said, stressing that the approach included “having low-cost (main) rotor blades and having only four of them.”

The 360 also will be equipped with a real-time health usage and monitoring system (HUMS). Gehler estimates that the 360 could cost as little per unit as half an AH-64 Apache gunship while still hitting the Army’s performance targets: a maximum forward speed of at least 185 knots, the ability to operate in high/hot conditions of 4,000 feet and 95 degrees Fahrenheit, and a combat radius of at least 135 nm. Gehler stressed that the 360 is not an Apache replacement, but that, "Our cost is much lower than the target the Army is looking for now. The actual cost to fly this airplane will be quite low compared to an Apache.” 

Gehler said the 360 could meet the range goals and stay on station for 90 minutes with a 1,000-1,200 pound payload. The helicopter could have a maximum range of 700-800 nm with auxiliary fuel tanks installed in the “huge” internal main weapons bay and potentially even more than that if more tanks were hung on the wings, a requirement the Army has not fielded as of yet. The 360 is designed to be operated by two, one, or none in the cockpit. “Everything we are doing is meant to assure optional pilot capability,” he said. 

Meanwhile, Bell continues to fly its FLRAA semi-finalist, the V-280 Valor tiltrotor. The Army plans to have the first FLRAA aircraft operational by 2030. Bell is competing against the coaxial compound Sikorsky-Boeing SB-1 Defiant X  for the final award. 

Ryan Ehinger, Bell vice president and program director for FLRAA, told AIN that the V-280  already has logged 200 flight hours over the course of 150 sorties since its first flight in late 2017. “In that time we have been able to get thousands of test points and been able to knock out all of the Bell key attributes that we set out to achieve such as 280 knots of speed, Level 1 attitude quickness, and long-range mission speed of 240 knots. We’ve been able to move into other things such as fast roping, integration of pilot distributed aperture systems (PDAS), and things of that nature. So we really have done quite a bit in the 200 hours we have flown thus far,” he said. That includes demonstrating a combat radius of 230 nm and a variety of advanced avionics and systems integration. That includes flying the aircraft with Lockheed-Martin’s PDAS—pilot-distributed aperture system—and a tactical datalink. 

This technology allowed a 2020 demonstration of slingload operations with the V-280. “We watched with cameras mounted on the aircraft and sent that signal to a ground station with the tactical datalink,” Ehinger said. Bell has also integrated an autonomous guidance computer into the aircraft and last year demonstrated a sortie that flew autonomously—albeit with safety pilots aboard—including takeoff, landing, and conversion. “It’s really pretty remarkable,” Ehinger said.  “Our (testing) models reflect very accurately how the aircraft performs and flies. A significant benefit of that was allowing us to achieve autonomy as quickly as we did.” He also credits the intelligent application of lessons learned from more than 500,000 hours of flight experience derived from operations of the Bell-Boeing V-22 tiltrotor for enabling Bell to maximize V-280 performance and “reducing risk for the government.” The Bell-Boeing team delivered its 400th V-22 last year. 

For the remainder of 2021, Bell plans to focus on model validation, control law tuning, and program risk reduction. Ehinger is particularly proud of the fact that the aircraft already has been flown by Army experimental test pilots. “When you turn over the aircraft to Army (pilots), there’s nothing you can hide. You’ve got to be able to deliver on a capability and be able to execute. And we are really proud to be able to have done that,” he said. 

Ehinger said Bell’s digital thread has benefitted the V-280, 360, and Bell’s super-medium 525 civil helicopter programs. All three aircraft employ fly-by-wire flight controls. “It has helped us design more quickly, more accurately, and with fewer issues, as we moved into manufacturing and flight test.  The V-280 went very quick from clean sheet to first flight and the 360 has captured a lot of lessons learned from that, with a timeline that is even shorter than the V-280’s,” he said.  

“The future is about range and speed. It will transform the Army and be a game-changer for the warfighter,” Ehinger said. “You really can’t afford not to invest in this new capability to be competitive and win on the future battlefield. The tiltrotor offers that on a vehicle level. And when you combine that with (Bell’s) open systems architecture, it allows you to overcome obsolescence issues and move and upgrade mission systems at the speed of technology.”