New pilotless aircraft to push the bounds of data links, electric technology

Dec. 1, 1997
FORT WORTH, Texas - In a time when military budgets are declining, military aircraft pilots are resigning their commissions, and costs are soaring for high-technology aircraft, defense planners worldwide are struggling to find safe and inexpensive ways to handle a wide range of aircraft missions from ground attack to air superiority.

By J.R. Wilson

FORT WORTH, Texas - In a time when military budgets are declining, military aircraft pilots are resigning their commissions, and costs are soaring for high-technology aircraft, defense planners worldwide are struggling to find safe and inexpensive ways to handle a wide range of aircraft missions from ground attack to air superiority.

Gaining greater credibility every day is the concept of the unmanned - or uninhabited - combat air vehicle (UCAV). This is not to be confuse UCAVs with unmanned aerial vehicles (UAVs), which are becoming widely used in reconnaissance roles, or with their older cousins, RPVs (remotely piloted vehicles), which generally are target drones.

Aeronautical and avionics experts say UCAVs will require the latest technology in wireless data links, secure real-time data communications, data encryption, advances in electric aircraft - particularly in electric actuators - and broad use of commercial-off-the-shelf (COTS) electronic equipment because of the expected tight cost constraints of the future aircraft.

The autonomy of UCAVs lie somewhere between RPVs and UAVs. Like UAVs, they can operate without human assistance and loiter for long periods over enemy territory, yet they also take commands remotely from datalinked operators. These operators may be thousands of miles away at a ground base, aboard a ship, or even in an aircraft.

Somewhere around 2015, UCAVs may take over nearly all of the missions of manned aircraft, from air-to-air combat, to close air support, to strategic bombing. That is likely to involve an entire family of UCAVs, each designed for a particular role.

But in the beginning there will be only one airframe and one mission to demonstrate the entire UCAV concept. That airframe is to weigh no more than 10,000 pounds empty, carry large numbers of 100-to-200-pound munitions, and cost no more than $7 million each. Its mission: suppression of enemy air defenses.

Leaders of the U.S. Defense Advanced Research Projects Agency (DARPA) and the U.S. Air Force have told contractors of plans for an advanced technology demonstration (ATD) program that would invest some $100 million through 2002, with the goal of having a prototype flying by that date. The first phase will award several contracts for a year-long study into operational concepts and technology needs, followed by a downselect to one contractor to build and demonstrate a prototype.

Air Force officials, meanwhile, want to place the first UCAVs in service by 2009, given funding approval and successful technology development.

"We have focused a lot on affordability; we would like to keep the aircraft as simple as possible," says David Whelan, director of DARPA`s tactical technology office. "Smaller, lighter munitions, carrying many per sortie, is where the high-leverage payoff would come. We want to think of it as a very low-maintenance, low-operating-cost system that we would not need to fly as frequently as manned aircraft for training purposes.

Electronic technology

"New technology might come into play, such as electric actuators to avoid the use of hydraulics," Whelan says. "We are willing to look at minimizing on-board sensors; there are a lot of programs looking at very capable off-board sensors, such as the Tier II Plus (GlobalHawk) high-altitude, long-endurance UAV, that we can use for off-board cueing and even off-board targeting."

The subsonic UCAV, which is to operate at low, medium, and high altitudes for hours or days at a time, will require multi-spectral distributed sensors, robust wide-bandwidth, redundant jam-resistant agile datalinks, multi-platform data fusion, situational awareness, on-board artificial intelligence, and on-board electronic warfare and missile detection capabilities. The need for long periods of storage, minimal maintenance, and reduced weight also are leading designers toward an hydraulics-free approach, such as incorporating electric actuators.

But due to the overriding requirement for low-cost solutions, each of these will need to be applications of existing systems or systems that may be developed or advanced during the life of the program itself, which forces a highly modular "plug-in" package design.

"Being 10 years out into the future, we have the ability to explore how to do the whole mission differently and more cost effectively," Whelan says, adding that the UCAV cannot itself be a technology driver. "I`m trying to take this one step at a time and keep the R&D focused on a reasonable first step," he says. "There is a large community that wants to keep manned systems in play and we don`t want to get into a lot of arguments over the eventual state of unmanned systems."

The entire range of off-board sensors - from space-based surveillance to unattended ground sensors - are being considered for what Whelan says will be a "tightly coupled system of sensors".

"In terms of the ability of the aircraft or overall system to perform its mission, the critical technologies are the communications links," Whelan says. "The level of technology required in the air vehicle, weapons and guidance system are basically here today. The control elements are primarily monitors with software. So the critical long pole in the tent is communication," Bledsoe says. "There is always the drive for more bandwidth. When you consider what it takes to transmit images back and commands up and multiply that by large numbers of systems doing this, the communications limitations become an issue. It`s not a matter of designing one aircraft to do one mission, the problem is having several of these operating simultaneously."

Other issues include stealth. The radar signature of the vehicle increases in importance if part of the mission involves long dwell times over enemy territory, so DARPA experts are anticipating proposals for low-observable designs.

How and from where operators will control UCAVs is also an important consideration, as well as determining the appropriate mix of automated flight systems with remote controls.

Although some have suggested using a modified manned aircraft such as the F-16 as a proof-of-concept vehicle, that is not the course to an actual production vehicle.

"You could modify a lot of existing aircraft to have a degree of unmanned suitability, but the problem is the low lifecycle cost requirement," Whelan says. "To have that, you need a vehicle suited to long periods of non-use, all of which really speaks to new and advanced technology." And if UCAVs are to meet their potential to handle a full range of air combat missions within the next 20 years, it will require an all-new vehicle that takes advantage of new technologies.

While some say the technology and systems exist today to create a UCAV, Whelan says he is not so certain industry is ready for a production aircraft. While there has been strong progress toward jam-resistant, long-range datalinks - vital to the success of any UCAV - Whelan says he believes other areas are not yet so advanced.

"If I was to ask for a tailless, continuous-surface aircraft, could the contractors do that today?" Whelan asks. "Are they ready to work with any special materials we may need? Can they do this at a cost that won`t break the bank? Electric actuators, for example, certainly leave a lot of room for improvement. We`re just not yet ready to create an all-electric aircraft, although that certainly would seem to be the direction we might want to go. We have an ongoing program called VITAL that uses a lot of fiber optics, but that is an R&D program and I`m not sure all of the technology is ready to go there, either."

Armand Chaput, who leads the Lockheed Martin UCAV design team in Fort Worth, Texas, sees UCAV technological issues in terms of bringing the cost of that technology within the limits of the DARPA/USAF target.

"If this system does not come in at a very attractive cost, it probably won`t happen," Chaput says. "Adaptation of off-the-shelf computers and software is at the top of the list. The second key area is how to command and control these things - the technology associated with datalinks, multiple vehicle control by a single operator, robust bulletproof datalinks, the man/machine interface. A lot of technology has been developed in terms of automated systems for manned aircraft that are directly applicable to the UCAV, but the real challenge is how to take the existing pieces and integrate them into a low-cost system."

Enabling the aircraft to reason on its own is another issue, Chaput points out. The aircraft will require enough artificial intelligence "so when you aren`t in contact with it, it can do some reasonably intelligent things on its own, such as knowing not to fly into a hill or sand spike," he says.

Jim Bledsoe, manager for advanced strike systems at the Boeing Phantom Works in St. Louis says he believes technology may not be the most significant problem facing UCAVs.

"Taking the man out of the cockpit, I would put in the category of revolution. This is a substantially different weapons system from any we`ve ever had and getting an understanding on the part of the customer on what that system is, how it will integrate in the force structure, and work safely and reliably in a mix of manned and unmanned systems is one issue. The second is how to pay for it. Those are much more significant issues in determining how and when and if these programs go forward than the technology issues."

Click here to enlarge image

This Lockheed Martin artist`s concept shows two 20-foot low-observable UCAVs as they strike an airfield with penetrating weapons. UCAVs, which are intended to get close to targets without putting human aircraft pilots at risk, will push technologies related to electric actuators, high-speed data links, and machine automation.

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