Aviation Week & Space Technology
July 1, 2002
Pg. 26

USAF Tags X-45 UCAV As Penetrating Jammer

Humans slow electronic attacks, so planners pick unmanned aircraft as EA-6B Prowler replacement

By David A. Fulghum and Robert Wall, Washington

The U.S. Air Force has changed the requirements for Boeing's high-performance unmanned combat aircraft to include electronic attack as part of its initial operational capability.

That change would make the Block 10 UCAV--which is to evolve from Boeing's X-45--the Air Force's replacement for the Navy and Marine Corps EA-6B Prowler. The Navy has already selected the two-man EA-18 as its follow-on.

This latest shift is only one of a series of twists and turns in the Pentagon's attempt to define the road map for fielding a modern electronic attack capability against increasingly sophisticated air defenses available on the world market. Among them are the Russian-built SA-10, SA-12 and SA-20, but they also include digitally upgraded versions of older missiles. Another reason for the delay in deciding how to proceed has been the concern among top Defense Dept. officials that all the Pentagon's electronic warfare (EW) systems must be networked efficiently.

The Air Force's UCAV would be able both to drop bombs, as originally planned, or block radar, communications and other electronic signals with a high-power RF signal produced by an EW payload that fits in the weapons bay. The strategy calls for the first 12 UCAVs to be focused on air defense suppression.

The push for UCAVs is an outgrowth of a meeting between Boeing officials and Defense acquisition chief E.C. Aldridge, Jr., last month. The UCAV had already been accelerated to an operational date of 2008. That schedule may be moved up again.

Aerospace industry officials say that Air Combat Command's requirements staff sent a letter in early June to the Air Force's operational requirements office altering the UCAV's primary mission for the first block of operational aircraft to include electronic attack. The decision comes at a time when senior Air Force leaders have been expressing increasing doubt about using UCAVs in an attack role because they believe those highly dynamic missions are still better performed by manned aircraft. Aldridge also told the service to improve the quality of the receivers they would use on the UCAV and to more adequately fund the project.

The need for an EW-focused UCAV is escalating because the Prowler has aged dramatically in the last year, according to Stephen Cambone, a top policy official for Defense Secretary Donald H. Rumsfeld.

HOWEVER, ENGINEERS are still scratching their heads to determine how the mission change will affect the UCAV's design. While the shape isn't expected to change radically, its size and demand for power may have suddenly increased, one industry official speculated. It could also alter the demonstrations the Air Force and the Defense Advanced Research Projects Agency had planned for the X-45. So far, design work on the X-45B hasn't been affected.

Industry officials admit they are working on the daunting problem of battle management of a jamming system distributed among several manned and unmanned aircraft. "Those boxes and those platforms tied together is certainly an area where we are going to work," said Mark Ronald, president of BAE Systems, North America. "At the speed at which things are done and the complexity of the signals that you're trying to work on, increasingly there is less value added by a man. A man just slows things down. Distributed systems are a lot more complex, but inherently you're much better off with unmanned."

The U.S. Air Force UCAV's emitter will not be omnidirectional. Instead power will be concentrated in a limited arc to cover aircraft in the target area or jam air defense radars at a particular site. Being able to direct the jamming beam would provide a measure of self-protection from air defense missiles that home on jamming signals.

EW PLANNERS envision a distributed architecture with a small number of UCAVs carrying receivers and a larger number with jamming payloads. In both cases, the payload would fit into the weapons bay. Baseline equipment is slated to be the ICAP-3 receiver upgrade currently in development for the EA-6B.

The distributed architecture concept and plans by the services to pursue different approaches to electronic attack has created interest at senior Pentagon levels in naming a contractor team to oversee the process. The goal is to make sure all receivers measure a foe's radar signal in exactly the same way so information can be shared and acted on instantaneously. If there are differences, it could lead to delays that give a modern air defense system the time to track and kill an airborne target, an industry official said.

In the Block 30 version of the Air Force's UCAV, developers expect to take the next step in electronic attack by inserting a high-power microwave weapon (HPM)in the weapons bay to attack targets with vulnerable electronics. In particular, radar installations are vulnerable to sharp spikes of energy that can damage components and scramble computer memories.

THE AIRCRAFT would have a fixed aperture, not a turret, but the jamming signal could be directed within a limited field of view, probably 90 deg. or less, by electronic scanning--roughly the same steering system used in the emerging generation of active electronically scanned aperture radars that will equip the F-22, JSF and F/A-18E/F. It's a new technology, and so far, controlling the energy has proven difficult. However, the kill mechanism is much faster than a laser that can take several seconds to kill a target. Those with insight into Boeing's efforts say that generating the power is not an issue. The problem is developing an aperture that can focus and direct the pulse of energy predictably. However, when the target shifts to computers, planners believe an omnidirectional burst of energy would likely be the best mode of attack.

Some UCAV proponents fear the Air Force's maneuver to change the mission could undermine the program, particularly in Congress where it has been sold to lawmakers as fighter/attack aircraft.