Bell Helicopter assembly leader Jeff Josselyn begins a tour for two journalists seated inside a nearly complete tiltrotor parked within a former OH-58D modification centre at Bell’s manufacturing complex in Amarillo.
“The beauty is, this aircraft is based on all the lessons learned from the V-22,” Josselyn begins, as the seated journalists grab a little too eagerly at the unfamiliar controls.
Josselyn’s 10 April tour is the first time Bell has allowed journalists inside the V-280 Valor, a $500 million gamble that will compete with the Sikorsky-Boeing SB-1 Defiant and other concepts for a military rotorcraft replacement market worth billions over several decades. It is scheduled to begin a year-long flight demonstration with the compound-pusher SB-1 later this year. The data will inform the requirements and – perhaps – the acquisition strategy for the US military’s Future Vertical Lift (FVL) programme.
With the SB-1 still in the final assembly stage, Bell is waging a full-on marketing blitz with its nearly completed aircraft. For Bell, the V-280 is as much about redemption as technological progress. The V-280’s managers want to show the world that the company has learned from the lessons of the V-22, the first operational tiltrotor that survived a tumultuous and tragic development phase. Josselyn notes tht the V-280 is designed using lessons gleaned from more than 300,000h of test and operational flight hours on the V-22.
To prove how the V-280 will be different, Bell starts with a cockpit tour.
Valor demonstrator is "95% complete", ahead of flight testing from September
Bell Helicopter
With heated transparencies scheduled to arrive from PPG by mid-April, the V-280’s initial windshields have been removed, allowing visitors to enter the cockpit through the front window rather than the side door. Once seated, it takes a few moments to absorb the differences between the V-280 and a conventional helicopter – or even the V-22.
“We don’t have the traditional cyclic and collective as you’d see in a traditional rotor aircraft,” Josselyn explains. “The reason is because of the range this aircraft is capable of. You’re going to be sitting in this seat for quite some time.”
Instead, Bell has installed sidesticks, a technology borrowed from the similarly fly-by-wire 525 Relentless, a super-medium helicopter still in development and aimed primarily at the commercial market. The bulkhead and keel of the V-280 are also modelled on the 525.
As an aside, the 525 fleet remains grounded as the National Transportation Safety Board completes an investigation of a fatal crash last July of the first test aircraft. Bell expects the board to release the conclusions “very shortly”, allowing the company to resume flight tests.
Meanwhile the first and only V-280, billed as 95% complete, is waiting for a few key components. One of them is the forearm support that mounts behind the sidestick, allowing the crew to manoeuvre the new tiltrotor with small wrist movements comfortably over long periods. Ergonomics is a surprising theme for a military helicopter, but Bell’s layout for the V-280 is focused on providing 525-level comfort for the crew. The aisle stand features a cursor control device angled at about 45° rather than perpendicular to the glare shield, allowing the crew to toggle between four multi-function displays using a natural hand position. The multi-function displays themselves use traditional push-button controls, but Josselyn notes that Bell could move to touch-screen devices in an operational V-280.
Despite Bell’s substantial investment, the path to an operational V-280 could be long and far less forgiving than the two-decade development project the US military lavished on the V-22. The V-280 may be a “fourth-generation tiltrotor”, as Bell describes it, but it is not designed to replace the V-22, which anyway the US Marine Corps and Air Force Special Operations Command are not looking to replace for the foreseeable future.
Like the SB-1, the V-280 is instead designed to fill the role once performed by Bell’s original UH-1 Huey. Sikorsky’s UH-60 Black Hawk won the 1970s competition to replace the Vietnam-era UH-1; Bell’s unsuccessful bids for that Utility Tactical Transport Aircraft System contract were based on two- and four-bladed versions of the Model 240.
The army has yet to settle on a firm plan for replacing the Black Hawk fleet. Instead, it is following a two-path strategy. First, the army is funding the Improved Turbine Engine Programme (ITEP), which will replace the 2,000shp-class GE Aviation T700 engine with a 3,000shp powerplant. A competition between the GE3000 and the Honeywell/Pratt & Whitney joint venture ATEC HPW3000 is scheduled for a downselect by the end of the decade, with the winner cleared to develop a product to re-engine hundreds of UH-60s and Boeing AH-64 Apaches.
At the same time, the army also is funding GE to develop the future affordable turbine engine (FATE). This 6,000shp-class turboshaft will provide enough thrust to power a rotorcraft up to around 100kt faster than a conventional helicopter, and be able to take-off and land vertically. Assuming the army can continue to afford modernising UH-60s while simultaneously developing a high-speed replacement, the FATE engine will be relied upon to power whatever comes next.
TECHNOLOGY DEMONSTRATOR
The joint multi-role technology demonstration (JMR-TD) is the army’s flying laboratory for assessing the merits and challenges of combining relatively high speed and vertical lift. For Sikorsky-Boeing, JMR-TD is a chance to introduce the coaxial-compound-pusher configuration into operational service. Early experiments with Sikorsky ABC concepts in the 1970s shelved the concept for four decades, as flight control technology was not yet able to cope with the vibration levels associated with high-speed flight. In the past decade, Sikorsky revived the concept with the X2 high-speed demonstrator, which won the prestigious Collier Trophy after demonstrating that fly-by-wire technology can offset the vibration effect. Sikorsky continues to develop the S-97 Raider to fill niche military roles, and works with Boeing to develop the SB-1 for JMR-TD.
Technically, JMR-TD is not a competition. The army will not award a winner at the end of the demonstration. Both teams are preparing to compete for a follow-on development contract for FVL, along with alternative high-speed concepts proposed by Karem Aircraft and AVX Corp.
On 26 October, the army released a request for information for a subset of the planned FVL family of aircraft called capability set 3 (CS3), which calls for replacing UH-60s and the Marines’ UH-1s by 2032. The information the army gathers will inform an analysis of alternatives (AoA), the first step in the US military’s process to launch a new acquisition programme.
If the Department of Defense follows the normal path, the AoA will clear the army to launch a three-year risk reduction phase in 2020 focused on raising the maturity of key technologies with multiple contractors. The next step is to downselect to one contractor in 2023 to enter a seven- to nine-year engineering and manufacturing development phase, leading to an initial operational capability in 2030 or 2032.
The V-280 is a new aircraft, but an operational tiltrotor is not a new technology. For this reason, Bell advocates accelerating the schedule by deleting the risk-reduction phase and proceeding straight to the engineering, manufacturing and development phase in 2018.
“We think that based on what we've done that we could accelerate that [schedule],” says Vince Tobin, Bell’s vice-president of advanced tiltrotor systems.
Accelerated development programmes are not a hallmark of the US military’s acquisition system. In reality, many aircraft development programmes arrive years late – like the V-22. Army aviation, in particular, has a poor reputation for delivering new aircraft into service. With the exception of the non-combat Airbus Helicopters UH-72 Lakota, the army has not successfully fielded a new aircraft with vertical lift capability since the Black Hawk and Apache in the late 1970s.
Tobin acknowledges that Bell’s proposal to accelerate the schedule by skipping the technology maturation phase has met some reluctance within the Pentagon. “There is some receptiveness,” he says. “But there's a lot of concern. Not unexpectedly we're going to have fly to prove some things out. We might have more receptivity [after the flight demonstration phase of JMR-TD].”
For its part, Bell remains on track to enter flight testing in September. The V-280 has recently completed ground vibration testing, which revealed the need for several undisclosed design tweaks but nothing that will delay the programme’s airborne debut. Bell scheduled the ground vibration testing with non-flight-rated gearboxes installed in the Valor. By mid-May, the company expects to replace that equipment with flight-rated hardware.
The design and layout of the gearboxes are at the heart of Bell’s claimed cost and reliability improvements for the V-280 compared with the V-22. The Osprey fleet features a complex, composite wing with forward sweep and anhedral. Assembling the composite skin panels onto the metal spars is complicated. Workers in a tooling station called Item 30 attach the skins to the spars, note any places where they don’t align and then pull them back apart to apply a liquid shim. The liquid shim must be applied within 30min across the entire surface of the wing or it must be removed.
Bell believes its V280 design is mature enough for the army to skip a risk-reduction activity
Bell
The forward sweep and anhedral design of the V-22 wing creates another complication. A driveshaft runs through the wing to connect both engines, allowing one of the engines to power both propellers if the other engine fails. To achieve this, Bell installed a mid-wing gearbox to connect the driveshaft in the middle.
In the years since the V-22 entered service, Bell’s engineers determined that the forward sweep and anhedral features were unnecessary, but it was too late to remove them in the Osprey configuration. The V-280, by contrast, features a straight, flat wing that requires no connecting gearbox above the fuselage.
Another major advance in simplicity for the V-280 is in the engines themselves. The V-22 tilts both the wings and the engines. For the army, this configuration prevents troops from exiting from the side of the aircraft, as they’ve grown used to in Black Hawks and Hueys. It also increases the complexity of the both the engines and the tilting mechanism.
The V-280’s engine – a T64-GE-419 – is mounted horizontally in the wing-mounted nacelle and does not tilt. The direct drive that translates the engine power to the prop-rotor gearbox is also left stationary inside the engine nacelle, removing another source of complexity from the Valor configuration. The only mechanisms that tilt in the V-280 are the prop-rotor gearbox and the propellers.
Source: FlightGlobal.com
