Air Force, Navy to join forces on unmanned aircraft project.

Anascent Air Force-Navy program to develop a family of unmanned combat aircraft will seek to show military planners how this technology can help commanders gather intelligence, spot the enemy and ultimately destroy designated targets.

This ambitious effort, called J-UCAS (joint unmanned combat air systems) initially is focusing on developing common software that can be shared by both Air Force and Navy aircraft.

According to current plans, both the Air Force and Navy versions of J-UCAS will be equipped for strike missions. However, the Air Force is interested in optimizing its unmanned combat aircraft for electronic attack, while the Navy is focusing on reconnaissance and surveillance capabilities for carrier-based operations.

J-UCAS was formed last October by merging the Air Force X-45 and the Navy X-47 unmanned combat air vehicle programs.

Overseeing the J-UCAS program is the Defense Advanced Research Projects Agency. The Pentagon decided to turn over the $4 billion effort to DARPA to ensure the program does not fall prey to inter-service rivalries.

"We're going to demonstrate a set of capabilities so the services can understand this thing, what it can do and what it can't do," said Michael Francis, director of J-UCAS.

"The operating system is the part that's hardest to deal with," he told National Defense. Unlike traditional aircraft programs, J-UCAS emphasizes the software and the network, rather than the vehicles. "The platforms are just nodes in a network," Francis said.

In June, DARPA will select an "integrator-broker" to help develop the common operating system. The integrator, which could come from the government, academia or the private sector, will work with Boeing and Northrop Grumman, developers of the X-45 and X-47 respectively.

Fighting their way through layers of enemy air defenses, a UCAV must be capable of autonomous decision-making for everything short of the order to fire weapons. It must operate within a formation of multiple vehicles, which requires communications with other UAVs and with ground controllers. Even seemingly mundane matters such as flying in civilian airspace requires capable and reliable software.

"The level of autonomy, the level of collaboration, we're raising the bar for all UAVs," Francis said.

That is one reason why the operating system is being developed independently of the platforms. Should one or the other falter, at least part of the J-UCAS project can continue.

Boeing's X-45 and Northrop Grumman's X-47 will be assessed in their capabilities to meet both Air Force and Navy requirements. Both vehicles will use the same ground control equipment. "A Boeing ground station will control a Northrop Grumman aircraft," Francis added. "If the two aircraft are flying autonomously, unless you have a scorecard, you won't be able to tell which is which.

"We don't know if we'll have two designs that do everything or four designs that are specialized for service requirements," said Francis. "The common operating system is designed to work with whatever aircraft shows up for the mission that day."

The evaluations are scheduled between 2007-2009. Objectives include a combat radius of 1,300 nautical miles with a 4,500-pound payload (two Joint Direct Attack Munitions), 3.5 hours loitering time at a range of 1,000 miles and a capability of mid-air refueling, as well as operating in civilian airspace. The aircraft will have to demonstrate electronic attack and persistent surveillance capabilities.

The program recently passed two milestones. In March, an X-45 performed an unguided weapons release. In April, it launched a satellite-guided bomb at a speed of nearly Math 0.7 from 35,000 feet.