Army developing tactics for armed robotic aircraft.

One of the Army's oldest unmanned aerial vehicles is being outfitted with precision-guided weapons for operations in Iraq, officials say. The armed aircraft, called the Hunter, is viewed as a potentially valuable weapon for urban warfare.

The Hunter will drop the Viper Strike, a laser-guided glide bomb that Originally was designed to be a tank killer. Officials predict combat deployment will provide an opportunity to develop new tactics for lethal weapons in robotic systems.

"A weaponized UAV able to loiter for hours and strike fleeting targets has intuitive appeal to the U.S. military," says Col. Jeff Kappenman, systems manager for unmanned aircraft at the Army's Aviation Center, in Fort Rucker, Ala. "It just gives the services more capability without putting as many forces on the ground."

Army officials have been working on the Hunter-Viper Strike system for more than two years. The program has moved more slowly than expected, officials say. The first weapon-equipped Hunter drones and Viper Strike munitions were delivered to the Array for live fire testing in March 2003. The program got senior-level endorsement throughout the Army.

Earlier this year, the Army had two weapon-loaded Hunters and 14 laser-homing Viper Strike munitions in Iraq.

However, as of January 2005, the Army had only one Hunter crew in Iraq qualified for Viper Strike delivery, and training was continuing in the war zone. "It's just taken a lot longer than we anticipated to bring Viper Strike to an operationally effective capability," acknowledges Col. John Burke, project manager for UAV systems at Redstone Arsenal, Ala. "It's more than simply dropping a weapon off the UAV."

Hunters went to Iraq in January 2003, and a single company remains deployed with the 15th Military Intelligence Battalion.

One of the issues that had to be worked out was the Hunter's flying rights in a crowded airspace, also used by Army, Air Force and other intelligence systems.

A draft of an armed UAV operator's field manual was released in December 2004. The operators, who are helicopter pilots, must learn ballistics, laser codes and designators, and laser backscatter in fog, dust and smoke. Officials say the training manual will continue to be refined while Viper Strike is in operation in Iraq.

Army concerns about armed UAVs in maneuver warfare are more complicated than those of other services. "It's one thing if you're putting fires on an isolated target away from collateral damage," notes Burke. "It's another when you're going to release a munition in an area with troops and civilians. Your precision and accuracy have to be much higher."

The Hunter, made by Northrop Grumman Integrated Systems, has been around for more than a decade. In 1996, the Army decided to let the contract expire after just seven systems. In 1997, Congress gave the Army $12 million to remove Hunter from storage and test its capabilities. The system saw action in the Balkans conflict in 1999.

The basic Hunter UAV is a division and corps-level intelligence asset with range greater than 200 kilometers and endurance up to 12 hours. It cruises at 90 knots and reaches an altitude of 15,000 feet. A C-Band datalink ties the vehicle to a ground station. The sensor package sends day television or night infrared imagery to the ground. Northrop Grumman engineers have so far integrated 35 different payloads on the Hunter air vehicle.

In 2003, the company equipped the Hunter with the Army's "brilliant anti-tank" submunition. The UAV required changes in the airframe and electronics. "It would not have been that difficult had we had a normal development timeframe," explains Jim Perry, Hunter chief engineer and deputy program manager at Northrop Grumman Integrated Systems.

The aircraft had hard-points on the wings for external stores, but the center wing was not wide enough for released munitions to dear the fixed landing gear. A 5.2-foot long center wing extension provided safe clearance and held another 110 liters of fuel. The nose landing gear of the Hunter was strengthened to take extra weight.

Rather than disturb flight-critical software, engineers gave the Hunter a mission computer able to interface with the UAV data link and almost any weapon. The UAV operator controls the weapons and determines their status. The graphic user interface in the ground station helps to control and deliver munitions.

Viper Strike evolved from the brilliant anti-tank (BAT) submunition, which the Army had developed in the 1990s for its tactical missile, but subsequently stopped funding. The glide bombs rely on acoustic and infrared sensors to guide them to enemy armored vehicles. They can penetrate light top armor with shaped-charged warheads.

The altitude at which BAT deployed from the Army tactical missile was about the same as the operating altitude of the Hunter. The Army awarded Northrop Grumman a contract in July 2002 to integrate the BAT into the Hunter system and demonstrate UAV capabilities. Two BAT rounds could be carried under the Hunter and launched from their tubular housings by piston action to unfold their wings and glide to their targets.

An instrumented BAT was launched from a Hunter in September 2002, and a live round followed in October. The successful demonstration led to a contract in mid-January 2003 to outfit 78 BATs with tube housings and to modify six Hunters to deliver the munitions.

Although no BAT systems were deployed in Iraq, the Army saw a need for armed-UAV technology. But to make the system more useful in urban combat, the Army replaced the acoustic-infrared BAT with the laser-guided Viper Strike.

"The big issue was low collateral damage," recalls John Miller, director of ground systems at Northrop Grumman, A laser seeker projected by a lightweight laser designator rangefinder made the Viper Strike a precision weapon, he says.

To demonstrate precision-attack capability in an urban environment, a stationary pickup truck was parked between construction trailers simulating buildings. The TV camera acquired the target, and the laser rangefinder designated the truck. The Viper Strike destroyed the truck with minimal damage to the trailers, says Miller. "We knew it would take out the armored targets. What we didn't realize was how good it was on soft targets."

The Army has ordered 78 Viper Strike rounds. The initial munitions will be converted from BAT munitions and 45 new weapons are being built without the acoustic sensor probes on their folding wings. Northrop Grumman is considering other changes to lighten the munitions by 10 to 15 pounds and will integrate a global positioning system satellite receiver to guide the gliding round through cloud cover and improve the survivability of the air vehicle. A Viper Strike data link also is under consideration, which would allow operators to redirect the weapon while in flight.

The Army plans to field the weapon-equipped UAV with dismounted infantry, armor, manned aviation, artillery and other maneuver units.

Training is vital in this program, say officials. "A lot of the training is not about can I steer the designator over the target, but about how that individual or group interplays with a whole combat team," explains Burke. "The actual mechanics of how to use it are very straightforward. What you have to practice is the tactics, techniques and procedures." As Hunter companies rotate in and out of Iraq, the incoming commander chooses how many operators will train for Hunter with Viper Strike.

Within the ground commander's plan of attack, the UAV operator must be aware of how fast the target is moving and what friendly forces are around. "Collateral effects are a part of the scheme of maneuver," says Burke. "It's not a sniper shot." The Army is working to define a "surface danger zone" for the Viper Strike comparable to that of the Hellfire missile. SDZ describes the precision of the round and its explosive effects to protect friendly forces.

With Viper Strike, Hunter operators must maintain close communication with the ground commanders. The commander of air operations in the area assigns altitudes and operating areas to manned and unmanned aircraft.

Hunter with Viper Strike will not be the only weapon-equipped UAV in the Army. The Hellfire missile will be fired from the Ignat endurance UAV later this year. The Army also plans to purchase a new "extended range multi-purpose" UAV for intelligence, surveillance, reconnaissance and communications applications. The General Atomics Warrior and Northrop Grumman Hunter II are among the expected competitors in the program. The winner is scheduled to be selected in April.

Even without weapons aboard, UAVs can be used as target indicators. The Army is expected to install a laser designator on the Shadow tactical UAV, now in operation in Iraq. Kappenman notes even the hand-launched Raven UAV will play a role in combat situations, not with a laser designator but as a source of imagery.

Meanwhile, the Army's aviation technology center at Fort Eustis, Va., plans to test the Boeing unmanned Little Bird helicopter to help refine armed-UAV tactics and procedures.

Under a $1.6 million program with the Army's Aviation Applied Technology Directorate, Boeing will test the use of weapons such as Hellfire, the advanced precision-kill weapon system missiles, and the GAU-19A gun aboard the unmanned Little Bird, a modified MD 530F helicopter.

The topic of armed UAVs, meanwhile, is gaining attention at the Defense Department, where policy officials are debating the implications of deploying these systems.

"Weapons introduction onto unmanned air vehicle systems must be carefully considered and conducted under a controlled and thoughtful process," said Dyke Weatherington, deputy of the UAV Planning Task Force at the office of the secretary of defense. "Appropriate study and test is necessary to assure the safety and reliability of the system," he wrote in response to questions from National Defense. "That said, it is likely that we will see the services continue to qualify an increasing variety of weapon-UAV combinations to meet mission requirements."

UAV programs, additionally, need to continue to address a variety of technical challenges, such as aerial refueling, Weatherington noted. "Another equally challenging technical area is the development of a robust see-and-avoid system for UAVs that will prevent mid air collisions or near misses with other UAVs or manned platforms."