The time is ripe for a major technology push in US army aviation. But are the helicopter manufacturers in a position to provide it?

The rotorcraft basic research community in the USA has had a hard 15 months. One major research sponsor has announced plans to walk away from all vertical-lift aviation projects. Another critical funding source has cancelled two breakthrough – but troubled – helicopter technology projects and reordered priorities to focus on near-term, "applied" research. Meanwhile, US helicopter manufacturers have bristled at criticism from the Department of Defense that they are not being innovative enough.

Having failed to deliver a successful new rotorcaft in 20 years, US Army aviation leaders have adopted a sweeping modernisation strategy that largely downplays the role of the science and technology community. More than 800 new or refurbished aircraft are expected to be purchased for army aviation over the next several years, but the army has limited the acquisitions to strictly off-the-shelf types.

The contribution of science and technology is limited to the inclusion of key subsystems, such as advanced fly-by-wire and glass cockpits, which had been developed under now-cancelled programmes.

Some aftershocks of this profound period of change are already visible. Significantly, the search for the next ground-breaking technology has been greatly expanded, with US army aviation researchers in particular probing for sources of new ideas beyond the three largest domestic helicopter manufacturers.

The US Army did much to pace the progress of rotorcraft science. Yet, three fundamental performance boundaries that the army's experiments once helped to define – lifting capability, forward speed and endurance – have stayed stubbornly intact for decades.

Both the army and commercial industry have long-term interests in overcoming each of these barriers. In 20 years, the army wants to have an aircraft that can vertically lift a 20-25t vehicle, and to develop another rotorcraft with far greater speed and range than allowed by today's state of the-art in helicopter technology.

Conventional designs

Bell's tiltrotor designs are considered one way to address both challenges. But other companies are approaching the lift, speed and range barriers using adaptations to more conventional helicopter designs. Key areas to be studied are affordable structures capable of carrying C-130-sized loads in vertical-lift conditions, as well as the flight-control dynamics of increasing rotor speeds beyond Mach 1.

In the long term, such research, if funded today, could contribute vital design knowledge to the two aircraft expected to dominate the US military's rotorcraft inventory after 2030.

These two future concepts – Joint Heavylift Helicopter and the Joint Multi-role Helicopter – are not yet requirements or approved programmes. The army has been directed to lead a study to investigate the science and technology investments needed for the heavylift helicopter. But, essentially, both aircraft are visions for the next wave of rotorcraft modernisation after the army's core fleet of Boeing CH-47 Chinooks, Sikorsky UH-60 Black Hawks and Boeing AH-64 Apaches are retired beyond 2025.

Meeting challenge

Industry has estimated a $4-6 billion bill to meet the basic science and technology requirements of the heavylift aircraft alone. Rhett Flater, executive director of the pro-industry group American Helicopter Society (AHS), acknowledges that estimate has not been well received in the Pentagon. However, the idea of building what is essentially a C-130-sized, vertical-lift aircraft is more than just a propulsion challenge. Structural materials produced affordably on the market today are inadequate for such an aircraft.

The breakthroughs being considered suggest that now is the time to start a major science and technology push, which would allow for the army to begin acquiring advanced production models in the 2025-30 timeframe.

There are questions about whether the traditional helicopter manufacturers are in position to support such an effort.

The US Army Applied Aviation Technology Directorate (AATD) at Fort Eustis, Virginia has commissioned studies into potentially breakthrough rotorcraft concepts from start-up companies CarterCopter, which is proposing a heavylift gyrocopter, and Baldwin Technologies, which seeks to develop a mono-tiltrotor, also for the heavylift mission.

Meanwhile, Piasecki Aircraft has been granted funding to build a compound variant of the Sikorsky UH-60 Black Hawk, with a wing to offload the rotor and a tail-mounted propulsor to boost speeds. Sources at Sikorsky maintain the concept is fruitless, perhaps generating about 20kt (37km/h) more speed, but at the cost of significantly greater drag. But AATD's interest is one measure of the army's willingness to experiment.

However, Raymond Wall, AATD's director for systems integration, says that these studies must prove more than technical feasibility. Each company has to be able to prove convincingly that their aircraft design not only works, but is worth the substantial cost of continued investment.

"We have worked with a lot of these places through the years," says Wall. "Anybody can come up with an innovative new idea."

The army aviation branch's more traditional industry partners – Bell, Boeing and Sikorsky – have taken notice. American Helicopter Society's Flater, says: "AATD is simply trying to help out. The army leadership is willing to take a look at outlandish ideas."

The run of hardship for rotorcraft research has also changed the dynamics within the industry. Each of the biggest three army aviation contractors has been working on ground-breaking technology for decades – hence, Bell is investing in tiltrotor research, Boeing's work on the canard rotor wing (CRW) aircraft and Sikorsky's studies of a reverse velocity rotor (RVR) design. However, all three companies have been on the march in recent months to bolster their research and development infrastructure.

Innovation sought

In the past year, each of the three major US helicopter manufacturers has moved to seek new sources of innovation in rotorcraft. Boeing acquired Frontier Systems, in part to gain ownership of the DARPA-funded A-160 Hummingbird, a long-endurance, unmanned helicopter with a chequered flight-test history. Sikorsky acquired Schweizer Aircraft, principally with the aim of standing up a capability for the rapid prototyping of new design ideas. Finally, Bell has activated a new internal organisation called XWORX, which has also been chartered to conduct rapid prototyping and develop new concepts.

Each of these steps serves to answer criticism last year by Suzanne Patrick, deputy undersecretary of defence for industrial policy. Patrick issued a report on the capabilities of the US vertical-lift industrial base, which included an assertion that the major manufacturers could not be relied on to drive innovation.

Most industry executives have disputed Patrick's rationale, arguing that the manufacturers are simply responding to their customer's requirements. "To get some additional resources to push the boundaries a little bit would be useful," says Mike Tkach, newly appointed Boeing vice-president for army systems.

How much these responses were motivated from the critical report by the Pentagon is uncertain, and it is also unclear whether their main customer – army aviation – is prepared to reward them for a more aggressive posture on research and development. The mood in the army has been recalibrated by the short-term needs of the Iraqi war effort. The emphasis at AATD has been refocused on finding survivability upgrades for helicopters.

Industry's role in army rotorcraft research is likely to be relied on even more with the probable departure of the army aviation science community's largest single partner next year.

NASA has submitted a budget request for 2006 that would terminate funding for rotorcraft research. The withdrawal of NASA's roughly $60 million yearly budget would also void its side of a 36-year-old co-operative arrangement with the army, in which resources for dual-use projects were shared evenly. NASA has already closed two windtunnels used by rotorcraft researchers, claiming the facilities were under-used.

"This is a pretty devastating reduction," says Flater. Besides the immediate effect of the budget cut proposal on ongoing research, NASA has "eliminated funding for the university students who will be replacing the legacy researchers. That is a bad kind of double whammy to hit us within the industry," he says.

Mature industry

The administration, however, is arguing that the rotorcraft industry has reached a mature phase, in which revolutionary advances in technology are either not practical or not needed. But, at the same time, European governments are increasing investment across all areas of aeronautics research, including vertical-lift aviation.

The rotorcraft industry has approached both Congress and NASA with roadmaps for science and technology spending, seeking what Flater calls "revolutionary" improvements in rotor and transmission efficiency, safety and vibration reduction. One benchmark is to reduce empty weight of helicopter airframes 30% by introducing new composite materials. Another goal is to transition to bearingless main rotors, in an effort to ease the stress on dynamic components in rotor systems. Improving the efficiency of helicopter components is key to reducing operating costs, which are generally six times higher for helicopters than fixed-wing transports, says Flater.

"Our safety record right now is one of the worst around," says Flater, noting the helicopter industry averages about five accidents per 100,000 flight hours.

With roughly half the annual funding for US basic rotorcraft research set to disappear next year, there is growing fear of not only losing ground on competitive technologies, but also of a massive loss of youthful engineering talent.

New talent needed

"Eventually you're going to need young aeronautical engineers that didn't help design the Huey helicopter or the Black Hawk helicopter. And you have to have programmes that invest in that type of education and you have to have a job for them to go for one," said Brig Gen Jeffrey Schloesser, chairman of the army aviation task force, during a House of Representatives hearing on military helicopter programmes on 15 April.

In 2004 alone, the army cancelled the Boeing/Sikorsky RAH-66 Comanche and a joint effort with the Defense Advanced Research Projects Agency (DARPA) to develop the Unmanned Combat Armed Rotorcraft (UCAR).

The UCAR concept of deploying highly autonomous robotic helicopters to kill targets by the end of the decade was deemed overly ambitious by army leaders. One industry source close to the programme says army decision-makers did not think their battalion commanders would be ready to use such a technology within such a short timeframe. But DARPA strongly supported the concept and was poised to advance the programme into a prototype design stage in January when the army withdrew. The army has since dispersed most of its share of the UCAR programme funding to pay for developing aircraft survivability upgrades.

Making helicopters safer in combat situations will probably be the single-largest driver for science and technology spending, and the army has set ambitious goals, even as technical development delays continue to plague deliveries of defensive systems on the market today.

AATD is now seeking technologies that take a "holistic approach" to survivability, says Wall. Most defensive systems are engineered to defeat a particular threat – for example, laser jammers to counter heat-seeking missiles or ballistic blankets to guard against small arms fire. The army is searching for a capability to integrate a complete defensive system that can identify and defeat the full range of battlefield threats, from missiles through rocket-propelled grenades to bullets.

Status unclear

The status of UCAR's key innovative technologies is unclear. AATD is working on linking a Boeing AH-64D Longbow Apache to a Northrop Grumman RQ-5 Hunter fixed-wing unmanned air vehicle in a hunter-killer team. AATD does not intend to invest in UCAR-derived technology for that programme, as the Apache-Hunter link has nearly finished development.

Bell's work on the propulsive anti-torque system (PATS) for UCAR, a breakthrough concept to replace a tail rotor with a forward-thrust-producing exhaust nozzle, has also lost its key sponsor. Bell had been seeking a new source of funding to continue PATS development with NASA, DARPA or the army.


Source: Flight International