A pilotless X-47B is slated to be subjected to a burst of electromagnetic energy that will be 10 times that endured by other aircraft being tested to survive the electronic pollution found on an aircraft carrier.

Aerospace officials are pointing to that closely held plan as an important clue about a key mission that the U.S. Navy's next-generation, unmanned combat air system is being designed to perform. The mission is electronic attack—using bursts of high-power microwave (HPM) energy—against enemy electronics such as surface-to-air missiles and the radars that control them. Targets also could include computers, command-and-control centers or anything else that involves the heavy use of electronics.

Unlike other seagoing aircraft, the X-47B, a surrogate for the unmanned carrier-launched airborne surveillance and strike (Uclass) aircraft, will not be tested to an electromagnetic interference (EMI) level of 200 volts per meter. Instead, the design will have to survive and operate in a stunning environment of 2,000 volts per meter.

That means the Navy wants a design for its Uclass program that would be able to fire a permanently installed, rechargeable, anti-electronics weapon and withstand the sidelobes and errant electronic spikes that may occur when it is fired. Such an HPM device could be used at close range against enemy electronics without damaging the Uclass system's own electronics and flight controls.

As part of the testing, a trip to the anechoic chamber at NAS Patuxent River, Md., is next on the X-47B's test agenda.

“We will spend the better part of this spring doing electromagnetic compatibility testing,” says Capt. Jaime Engdahl, who represents the unmanned combat air system demonstration (UCAS-D) program.

“Does [the future Uclass aircraft] have to be the [X-47B size]?” he asks. “It was developed under the J-UCAS [Joint Unmanned Combat Air System] program and was sized for an internal weapons bay to carry 4,500 pounds of weapons and some electronic warfare weapons.”

Congress is already weighing in on the Navy's future unmanned strike options. A draft authorization bill keeps four major contractors—General Atomics, Lockheed Martin, Northrop Grumman and Boeing—alive in the hunt for a Uclass until 2016, stipulating that the program remain in the critical design review phase until that time.

Right now, the Navy's unmanned strike aircraft program is proceeding with two Northrop Grumman X-47B test aircraft. One (AV-1) is at NAS Patuxent River for the autonomous aircraft carrier landing program. It is slated to demonstrate the first carrier-based catapults and arrested landings in 2014.

The other aircraft (AV-2) is undergoing flight testing at Edwards AFB, Calif., and will be used eventually to autonomously find and rendezvous with two tankers, says Capt. Jaime Engdahl. That evaluation will be followed by an approach, a plug-in and the receipt of 3,000 lb. of fuel. One tanker will have a Navy probe-and-drogue refueling system; the other will have an Air Force-type boom refueling system. The transfer of fuel will be followed by a disconnect, detachment and flight away from the tanker using all the onboard sensors and software.

“All of that will have to be done in a closed loop,” says Engdahl. “There are phases that drive the program. For the carrier [demonstration], it's the final approach, the last half-mile before landing. You need to do that autonomously.

“You also need to hit the basket on a Navy-style [probe-and-drogue] tanker autonomously instead of it being remotely piloted,” he adds. “The air vehicles can't be commanded by operators on the ground, the carrier or another aircraft.

“We're taking the exact same software and processors and putting them on the the tankers and using GPS algorithms for both carrier landings and autonomous aerial refueling.”