Frozen in concept study purgatory for several years, the US Army's long-standing wish to develop a heavylift vertical transport is rapidly moving towards becoming reality
Top aides to US Secretary of Defense Donald Rumsfeld have joined ranks with the US Army brass to support a potentially long and difficult development effort for an advanced vertical airlifter. New interest from the USNavy is coalescing into a joint specification, lending a critical element of cross-service support to the project. A joint requirements document that clears the way to launch a development programme is now being drafted. It should be finalised by the end of the year.
But the proposal still faces a tough battle for funding in a department growing weary of expensive and risky development programmes. There are also doubts that a US industry that has not successfully delivered an all-new military helicopter since the early 1980s is up to the task.
Conceptualised more than 30 years ago as a replacement for the Boeing CH-47 Chinook, the army began to revisit the vertical heavylift concept in the late 1990s. Initially, army leaders talked openly about launching a joint tactical rotorcraft programme with the US Marine Corps, which was then studying a follow-on to the Sikorsky CH-53E Super Stallion. But the "joint" designation had to be dropped after the marines refused to participate. The army renamed the requirement the future transport rotorcraft.
By 2002, however, the name of the project had changed again. This time, the word "rotorcraft" was the problem. Army officials preferred a designation that did not limit their choices to only helicopter designs.
A variety of ideas already were being proposed by potential bidders, including tiltwings, tiltrotors, fan-in-wing, super-short take-off and landing aircraft (SSTOL), plus coaxial and compound helicopters.
A Lockheed Martin C-130-sized gyrodyne also has been proposed. The programme was renamed the Air Manoeuvre Transport (AMT).
Funding for the AMT failed to materialise in any of the army's budget planning cycles through 2004, but support was steadily growing in other ways. The most significant step came when Michael Wynne, undersecretary of defence for acquisition, technology and logistics, formed the Joint Vertical Airlift Task Force (JVATF). Chaired by Wynne aide Michael Walsh, JVATF was chartered in August 2003 to examine the US military's fleet of roughly 5,500 helicopters, and make broad recommendations for modernisation investments and ways to address capability shortfalls.
Walsh's group reported back to Wynne in December with three observations:
n about 5,000 helicopters will exceed their useful life by 2025, but future spending plans anticipated funds to replace less than 1,000, mainly through remanufacturing rather than new-build;
n many helicopter flaws identified in the early 1980s had never been corrected, such as having to make hazardous landings in desert "brown-out" conditions;
n while the army, navy and the marines each had defined a requirement for a vertical heavylift platform, neither a spending plan or a development approach were in place to overcome the technological challenges of such an airframe.
After meeting Wynne, the JVATF decided to focus energy first on the heavy-lift dilemma, regarding it as the most urgent of the three priorities. Designing an all-new heavylift transport would pose the greatest technical challenges. Breakthroughs would be required in propulsion and airframe materials, but no budget-line item existed to begin the basic steps in research and science. For example, Walsh says, there is no vertical take-off and landing-capable engine with a 15,000shp (11,175kW) rating, the minimum power requirement for the heavylifter.
Meanwhile, there seemed to be little time to lose. The task force found that it would take a huge development effort for an operational aircraft to arrive between 2020 and 2025. Even if the military relied on technology that was mature today, the earliest operational aircraft would not be delivered until 2015.
The JVATF's recommendations included launching a $2.5 billion research effort spread over four or five years, starting in fiscal year 2006. The science and technology phase would then be followed by a roughly 10-year system development and demonstration effort worth at least $10 billion.
It was judged that no single service could afford the fiscal and technical challenge of leading such an effort alone. The JVATF recommended that the requirements of all three services with an existing need - the army, navy and USMC - be combined into a single development programme, based on the Lockheed Martin F-35 Joint Strike Fighter model. The scale of the undertaking also suggested to the JVATF that an international partnership should be considered. NATO, France and Germany each have a requirement for a similar heavylift requirement, and EADS subsidiary Eurocopter is working on its own vertical transport requirement (Flight International, 18-24 May).
So far, US manufacturers are resisting any acquisition approach that calls for a transatlantic development programme, but several industry officials say they are open to the idea of a JSF-like partnership strategy. In this scenario, European companies would be allowed to invest in the development phase and compete for work as bids become available. The JVATF's work has not tackled the international partnership issue, says Walsh, who adds that no European industry officials have contacted the task force to express interest in the project.
Ill-fated development
All three services have identified a need for a vertical transport that can carry more than 20t. The army first defined its requirement in the early 1970s and launched an ill-fated development programme. The Boeing XCH-62 prototype, which could haul about 22t about 185km (100nm), made several test flights, but the programme was halted in the late 1970s and cancelled several years later due to lack of funds.
Meanwhile, the army's existing heavy-lift fleet has aged. Due to remanufacturing programmes, an average CH-47 Chinook is 16 years old. But the actual airframe averages about 36 years across the fleet. Walsh says the JVATF learned that one of the original Chinook prototypes built by Boeing in 1960 is still flying and is due to be remanufactured in 2012 before being phased out in 2032. As the Chinook has aged, the army's need for a heavylifter has evolved.
The Chinook was designed to haul large amounts of supplies and small vehicles to locations inside friendly territory. With the rise of the Future Combat System (FCS), a family of 19 heavily networked combat vehicles each weighing about 20t, the army has defined a need for a "vertical manoeuvre" force. That is, a fleet of vertical take-off and landing (VTOL) aircraft capable of hauling a battalion of FCS vehicles to a combat objective, not just flying generic resupply missions.
While still low on the army's priority list, the AMT concept became the focus of intense conceptual development within the army's warfighting think-tanks. The idea of a new heavylift vertical transport was inserted into futuristic wargames. Very quickly, a new warfighting doctrine began to take shape called mounted vertical manoeuvre (MVM).
The doctrine calls for harnessing the capability of an aircraft that could haul a payload of vehicles and equipment weighing at least 20t hundreds of kilometres behind enemy lines, says Maj Al Huber, of the Army Aviation Centre's Directorate of Combat Development. "MVM allows the theatre commander to place significant mobile combat power suddenly at almost any location on the battlespace," says Huber.
Combat simulations show the dramatic advantages of a VTOL heavy transport. Most importantly, the insertion force would be allowed to bypass an age-old need for air manoeuvre units to capture suitable runways behind enemy lines, then expend a large fraction of their troops to secure, repair and defend the airstrips, says Huber.
Instead, the AMT-equipped manoeuvre force could choose where to mass forces and which areas to avoid. The concept is an improvement upon the US military's evolving preference for non-linear attack tactics, allowing forces to bypass the enemy's strongholds and strike smaller, perhaps more vital centres of gravity on the battlefield, such as headquarters units or critical infrastructure.
"Only with MVM can the future force rapidly exploit positions of advantage over enormous distances, bypassing restrictive terrain, and dominating the battlespace with surprise and overwhelming force," says Huber.
Four concept designs with similar load capacity were evaluated in Huber's study: conventional C-130s, SSTOLs, a tiltrotor VTOL platform and a helicopter. The goal was to transport an FCS-equipped brigade to an objective deep in enemy-held territory. The results, say Huber, show the high-speed VTOL aircraft "is the most efficient means of force delivery". High speed reduces demand for fuel, the vulnerability of the aircraft and the risk of crew fatigue, he says. As a result, the C-130 and SSTOL were deemed to be the least suitable for the MVM mission.
The heavylift helicopter offered the flexibility that was desired, but its 170kt (315km/h) speed was considered too slow to be survivable behind enemy lines. The tiltrotor, however, provided the perfect mix of speed, flexibility and lift capability for the MVM mission, says Huber. "The tiltrotor outperformed all other aircraft in this study," he adds. Other key findings of the warfighting experiments included a minimum operational radius of 450km would be required of the VTOL aircraft to accomplish the MVM mission. But the conceptual work by Huber and the JVATF's recommendations in January 2004 were still not enough to drive a heavylift programme from abstract theory into budget line-item reality.
Through February 2004, the army's publicly listed priorities focused on more urgent needs, such as fielding the Boeing/Sikorsky RAH-66 Comanche, and modernising the rest of its fleet of attack, scout and utility aircraft. Army aviation was in the midst of a deep crisis. The troubled Comanche programme was absorbing 40% of its acquisition budget, and basic survivability upgrades for the existing fleet could not be afforded. Army aviation leaders were concerned the Boeing AH-64 Apache and Sikorsky UH-60 Black Hawk would be outpaced by the FCS in combat.
JVATF's findings gained sudden traction within the army in mid-February, just as the service announced the cancellation of the Comanche programme. The service instead would redirect the Comanche's five-year $14.6 billion budget to fund other modernisation priorities. Top priorities included replacements of the Bell OH-58D Kiowa Warrior and Bell UH-1 Huey fleets, but the JVATF heavylift concept was included in the long-range funding plans.
By this time, the navy also was on board to help draft a joint requirement for a heavylift aircraft. The navy operates CH-53 Sea Stallions in anti-mine operations, but has a broader vision for a heavylift resupply fleet. One of the core elements of the navy's Sea Power 21 operational strategy is a concept called sea basing, which envisions massive floating staging bases for army and marine manoeuvre forces. The navy envisages a need for a heavylift force both for resupply and for launching troops into equipment into combat, possibly to landing zones hundreds of miles inland.
But the USMC, unable to wait for the heavylift programme to get started, is to pursue its own plan for a heavylift replacement for its CH-53E fleet. While this fleet is the focus of a service life extension programme, the large numbers of aircraft that will have to be retired after 2012 is forcing the USMC to launch a speedy replacement programme. An operational requirements document for a new-build CH-53X is expected to be completed in October, allowing the service to launch a system development and demonstration phase later in 2005. The USMC plans to buy 154 CH-53Xs, which will have a threshold requirement to lift 12,260kg (27,000lb) more than 200km.
STEPHEN TRIMBLE / WASHINGTON DC
Source: Flight International
