Zephyr Net

Boeing Test Flies Strike UAV
Aviation Week & Space Technology
08/25/2003, page 50


David A. Fulghum
St. Louis


Boeing has test-flown a strike UAV that can be dropped from a supersonic F/A-22


Small, Lethal and Persistent

The U.S. Air Force wants to field a 100-lb. unmanned aircraft--launched from a stealth fighter flying at supersonic speed--that can cruise the battlefield for a half-day or more armed with a weapon powerful enough to disable a moving armored vehicle.

The project is called Air Dominator, and Boeing's Phantom Works has won the airframe technology demonstration phase of the project to build a low-speed, high-endurance candidate aircraft. The project is under the direction of the Air Force Research Laboratory at Eglin AFB, Fla.

As part of the project, Boeing also will look at an aerial refueling vehicle and a network "gateway" unmanned aircraft. Both, in company with the armed vehicles, would be part of a small interactive constellation of aircraft that would be launched in a cluster from a single F/A-22.

Although the five-year program has just started, Boeing has already flown the first prototype twice. It is a 4-ft.-long, 12-ft.-wingspan aircraft that uses advanced wing-warping techniques for flight control. That means the wing bends to turn the aircraft rather than using conventional flaps, ailerons and elevators. More flights will be made over the next year with an advance version of the miniature aircraft in a company-funded initiative.

The mature demonstrator aircraft is scheduled for first flight in 2005, said Carl Avila, Phantom Works' director of advanced tactical missile systems. The project is part of the persistent area dominance initiative being directed by the Air Force.

The concept of operations involves first defining a kill box or area of influence over which a number of flying munitions would scan the battlefield for a minimum of 12 hr.

"Those munitions would loiter there, and anything that enters that area, if it's a hostile target, would be attacked," Avila said. "The concept we proposed would loiter up to 48 hr."

An interesting twist to Boeing's concept is that a number of these small UAVs would be deployed in a cluster from a stealthy F/A-22 fighter during supersonic flight. Packages of three or four vehicles each would be launched at speeds of Mach 1.1-1.2 and altitudes of 30,000-40,000 ft.

"They would parachute [using a high-drag device to slow them], open up, deploy the folding wings and go down to very low altitudes--1,000-3,000 ft.--and fly fixed or random search patterns over the [designated] area," Avila said. "These would be network-enabled weapons. The onboard sensors would identify targets and that information would be sent back to ground stations, but they would also have some degree of autonomy in that the weapons would be capable of communicating with each other."

After one weapon identifies a target, all those flying in the area could swarm to the target if it's designated a priority. Or some weapons may be directed to continue the search while only a few attack. For such operations, the gateway UAV would be an important element. "It would be the tie to whatever network this system of vehicles becomes part of," Avila said. The Air Force is conducting studies on the optimum tactics for ganging up on targets such as a moving column of tanks.

The weapons-carrying versions of the air vehicle would launch up to two skeet-like explosive submunitions and would then strike a third target in a suicide attack. Each vehicle would also carry an onboard sensor such as a flash laser radar (ladar) and a network data link--probably Link 16.

The refueling and gateway aircraft would likely be about 50% larger than the other UAVs in the cluster. A package would mix one of the larger aircraft with two weapons-carrying vehicles, Avila said. Various packaging concepts are being studied, but likely a selection of aircraft will be launched in a "dense-pack" of three or four vehicles that would separate once its speed is sufficiently reduced by a retarding device. Each vehicle would then deploy its own parachute to stabilize its attitude while the wings deploy and the engine is started. In the initial concept, the wings are offset with one attached to the nose of the UAV and the other to the tail.

"When you first look at it, you wonder if it can really fly," Avila said. But tests have shown the vehicles to be very maneuverable, he said. Boeing is planning for the vehicles to be propeller-driven. Various engines are being considered including a heavy fuel option. To keep the noise signature stealthy, researchers are also looking at hybrid turbine-electric motors and turbine engines with a whine that is outside the range of human hearing. The aircraft has a targeted speed range of 100-150 kt.

The operational concept is for the refueling and gateway aircraft to operate at a higher altitude than the weapons-carrying versions. The gateway aircraft would be positioned to ensure that it has good line-of-sight communications to all the munitions. Satellite communications would complete the link to a command and control ground site.