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Combat-Survivable Unmanned Aircraft Take Flight

March 2003
By Maryann Lawlor
E-mail About the Author

Future weapons platform designed to quell tomorrow’s threats.

Hellfire missile-toting Predators are an interim measure to increase combatant power in the area of operations. But the U.S. military is moving forward quickly on the path to a force-enabling tactical air power weapon system for both pre-emptive and reactive strikes.

Working with industry and the U.S. Air Force, the Defense Advanced Research Projects Agency (DARPA), Arlington, Virginia, is developing an unmanned combat aerial vehicle (UCAV) that operates alone, with other unmanned aerial vehicles or with manned aircraft to attack air defense systems and time-critical targets. Munitions being examined for the platform include both joint directed attack munitions and the small-diameter bomb, a weapon scheduled for delivery by the end of this decade.

The genesis of UCAV work occurred in 1998 when DARPA and the Air Force selected four contractor teams to produce a preliminary design. Nearly a year later, a team led by The Boeing Company Phantom Works, Seattle and St. Louis, was chosen to design, fabricate and flight-test its UCAV demonstrator system in a 42-month, $131 million cost-shared effort.

Late last summer, the contract was extended, and work began on advanced versions of the X-45 UCAV demonstrator aircraft. The $460 million contract will support the fourth block of X-45A software development and flight-testing; two new demonstrator aircraft, designated X-45B; two shipping and storage containers; and an updated mission-control station. Flight-testing of the first X-45B is scheduled for 2004, and delivery of the second vehicle is scheduled for fiscal year 2005.

According to Col. Earl Wyatt, USAF, UCAV program manager, DARPA, the team is taking a revolutionary approach in that the goal is for one operator to control multiple air vehicles. UCAVs would be adaptive and autonomous, and the operator would act as the battle manager of multiple systems that will relay information about vehicle status, targets and flight-tracking to the designated route. In unmanned vehicle parlance, autonomous can mean preprogrammed.

Developers base their work on predictions about the threats in the 2010 timeframe. They have been identifying technologies, processes and system attributes required to reach this goal and have developed a demonstration program that will give them confidence that they have mitigated the risks sufficiently to warrant advancing with UCAV as a weapon system, the colonel says.

The program consists of three areas of emphasis. Unlike the Predator, where Hellfire missiles were an add-on capability, the UCAV platform is being designed from the beginning to carry weapons that can have an impact on the outcome of the conflict, Col. Wyatt explains.

The mission-control segment is the second component of the program. It allows the operator to monitor vehicle health and situational awareness as well as to intervene when additional information alters a mission. One goal is to be able to transfer control of the vehicles from an operator located in friendly areas to one situated in the area of operations. This requires both line-of-sight and beyond line-of-sight communications capabilities, the colonel explains.

Finally, because unmanned aerial vehicle support and repair carry some high price tags, demonstrations have been devised to determine if costs can be reduced in these areas, the colonel says. Robust survivability is critical, he adds. Wyatt says, as is the ability to return UCAVs to service quickly when damaged. The support segment also is examining manpower requirements.

UCAVs are being developed using a spiral approach, and DARPA’s primary work is in Spirals 0 and 1, Col. Wyatt points out. For Spiral 0, the UCAV team is using two X-45A aircraft at NASA’s Dryden Flight Research Center, Edwards Air Force Base, California, to examine core functionality.

Spiral 0 comprises several blocks. Block I work involves demonstrating the aerodynamic performance of the vehicle. Block II examines multiship performance for coordinated operations. For Block III, some of the intelligence will be moved from the mission-control segment to the UCAV platform, which is followed by demonstrations of cooperation between vehicles in Block IV. Finally, in Block V, the proven intelligence capabilities from this work will be moved to the Spiral 1 vehicle, Col. Wyatt explains.

Michael Heinz, vice president and general manager, unmanned systems, Boeing, relates that all of the flight tests to date for Spiral 0 have been successful. Although the vehicle itself is important, he says that even more critical is Boeing’s work in the mission management area. “Under Spiral 0, we’ll be developing five releases of software that allow us to gradually progress from autonomous operations to adaptive-autonomous operations,” Heinz relates.

In autonomous operations, the vehicle is preprogrammed to carry out a specific mission. The first software release allows the X-45A to reconfigure itself under adverse conditions. At a minimum, it would return to base, or it could adjust to carry on the mission. The second software release enables two air vehicles to fly cooperatively and exchange information.

Software release three will gradually move the cognitive decision making, which is generally made by the operator on the ground, to the vehicle. Using the information from its own sensors or from other sources, it will dynamically respond and address threats or obstacles, then carry on or change its mission. This software is scheduled for testing late this year, Heinz says.

The fourth software release will provide cooperative-adaptive autonomous capabilities, and the fifth will build on this work and move the UCAV to operating in an environment with both manned and unmanned vehicles.

Spiral 1 will involve both the survivability and supportability of UCAV, and work will continue on demonstrating that UCAV can operate safely with both manned and unmanned aircraft.

During this spiral, the team will design, develop, build and flight-test two X-45B vehicles, which are designed to resemble other warfighting aircraft. They will be 30 percent larger than the X-45A and will include treatments that will reduce the signature of the craft to decrease the risk of detection. While Heinz does not refer to it as stealth, he allows that it is low-observable technology.

In Spiral 2, work will be turned over to the operators so they can determine future missions for UCAV.

“The demonstrations at the Dryden facility are where we pride ourselves on looking ahead. Air Force operators are involved along with industry and NASA–Dryden personnel to ensure that the things we are doing are going to be things that the operators can use,” Col. Wyatt explains.

A total of 124 demonstrations are scheduled through 2005. By the end of 2002, 47 demonstrations had taken place. Lt. Col. Roger Thrasher, USAF, deputy program manager, UCAV, DARPA, says the demonstrations span the waterfront in terms of testing and proving the system. The vehicle, manufacturing technologies, affordability, weapons and weapons integration, robust communications and supportability on the ground all are being examined, he says.

“We have a very disciplined approach. First, we analyze and then conduct demonstrations in simulations to reduce the risk. Then we move to demonstrations on the ground before graduating to flight demonstrations. Even among the flight demonstrations, there are certain key demonstrations that we refer to as graduation demonstrations where we integrate a lot of the pieces and show a [common] thread through the system functionality,” Col. Thrasher discloses.

The demonstrations help determine whether the UCAV work is on track, Col. Wyatt explains. If the demonstration is successful, it is a plus. If the goal was not achieved, the team examines what needs to be done and makes adjustments. It is an opportunity to stretch the idea of an autonomous air vehicle, he says. Col. Thrasher adds that the team will roll lessons learned into future spirals.

As concepts of operations are refined, the warfighter identifies the weapons that will be most effective on a platform the size of a UCAV. “We’re comfortable at this stage of the game with the weapons the warfighter has identified, and we’re accommodating them,” Col. Thrasher says.

The small-diameter bomb is one of the munitions the team has determined can be carried on a UCAV. The miniaturized bomb currently is under development by the Air Force at the Air Armaments Center, Elgin Air Force Base, Fort Walton Beach, Florida. It is scheduled for initial delivery by the end of this decade, and if it is as accurate as planned, the smaller weapon will produce the same effect as larger, less accurate weapons, Col. Wyatt explains.

Heinz shares that the team may explore other lethal and nonlethal payloads. “For example, some future spiral could incorporate directed energy or electronic attack types of systems,” he says. The actual operational requirements are determined by the military, he states.

Col. Thrasher points out that a human is always in command of the vehicle. “We use a building-block approach with different levels of autonomy. As we grow more comfortable with UCAVs and what they can do and what they cannot do, then we’ll be able to move toward more autonomous operations, where it operates within a set of rules of engagement. Certainly at the outset, the operator will be able to know what he’s aiming at just like with munitions today,” he says.

Col. Wyatt relates that integration is among the challenges that the team faces, and it must be done on several levels, including stealth and software, while keeping supportability in mind. “We need to make sure that we develop something that takes us to the next level of unmanned capability, but also we don’t want to forget the fundamentals and ensuring that it’s available when the warfighter needs it,” he emphasizes.

Interoperability is another key concern with DARPA’s UCAV work, Col. Wyatt says. UCAVs must be interoperable with manned assets in the air and on the ground. As part of its effort, the UCAV team is working with other program offices so that as UCAVs mature, they will be able to interoperate with other platforms. Simulations that allow UCAVs to operate with manned platforms are supporting this work, he states.

“By working with those other program offices, they are on our road maps, and we are on their road maps. So when the warfighter gets a UCAV system, we will have touched base on all of the things that make us an effective weapons system,” Col. Wyatt explains.

In addition to UCAV work, DARPA is investing in research on the U.S. Army’s unmanned combat-armed rotorcraft (UCAR). Four industry teams are conducting concept development studies. The UCAR program would involve developing and demonstrating the ability to conduct sustained armed reconnaissance and attack missions as an integral element of the Army’s Objective Force.

After the concept development studies are complete, DARPA will choose two contractors for a nine-month preliminary design phase, which will be followed by the system development phase that will result in two prototype vehicles. By the end of 2009, the Army will adopt the winning design and begin final system design and development. Fielding of the system is scheduled for the 2010 to 2012 timeframe.

The U.S. Navy also is examining UCAVs; however, work on this program is still in the early stages. Along with DARPA and the Navy, Boeing is developing a UCAV system with long-endurance surveillance, suppression of enemy air defenses and deep strike capabilities. It is being designed to operate from an aircraft carrier and require half the space of manned aircraft.

Col. Wyatt explains that a UCAV designed for the Navy would have to be able to land on aircraft carriers, a feat that is more challenging than landing on an airfield. However, the Navy will take advantage of DARPA’s current UCAV work during research and demonstrations, he adds.

Other companies continue to pursue work on UCAV systems. According to Douglas Fronius, director, target programs, Northrop Grumman Integrated Systems, El Segundo, California, his company has been actively working the Navy’s UCAV program with its company-funded effort on Pegasus, a UCAV that is designed to land on an aircraft carrier.

“The ability to land on an aircraft carrier was considered a difficult or high-risk area for an unmanned aircraft. So, as a confidence builder, we funded a program called Pegasus to put a very unusual configuration into that environment,” Fronius explains.

The kite-shaped UCAV, capable of autonomous flight, has begun testing at China Lake Naval Weapons Center, Ridgecrest, California. “Demonstrating that we can control that configuration autonomously at the speeds and approach rates suitable for carrier qualification is the goal of the program,” Fronius says.