By Michael Sirak

The Air Force and its industry partners have begun flights with a test version of the new radar arrays under development for the B-2A stealth bomber aircraft, Northrop Grumman [NOC], the prime contractor for the platform’s upgrades, said on Monday.

The company said it, together with Raytheon [RTN], supplier of the modern radar antennas, has completed the installation, integration and initial flight testing of the first developmental test units (DTU) on the B-2A test aircraft, which is designated AV-3, at Edwards AFB, Calif. The B-2 carries two radar arrays, one on each side of the aircraft.

“The delivery and installation of the DTUs is a major milestone for the RMP program,” Dave Mazur, Northrop Grumman’s B-2 program manager, said in the company’s Nov. 26 statement.

Northrop Grumman and Raytheon are working under the Air Force’s B-2 Radar Modernization Program (RMP) to upgrade the existing AN/APQ-181 multimode radar on the 21-aircraft B-2A fleet through the addition of modern active electronically scanned arrays (AESA). These new antennas will allow the radars to operate on a different frequency within the Ku-band so that they do not interfere with the functioning of commercial satellites to which the Department of Commerce assigned the primary right to the radar’s current classified frequencies (Defense Daily, Jan. 27, 2006 and June 19, 2006).

The new AESA antennas will also lay the foundation for potential capability enhancements to the radar, such as the ability to generate high-resolution synthetic aperture radar images for targeting of ground objects. However, the Air Force officials say there is currently no funding available to earmark for such options.

The Office of the Secretary of Defense announced in August that challenges encountered last year associated with integrating the test arrays on AV-3 had caused a slip of at least six months to the current RMP schedule (Defense Daily, Aug. 27). The Air Force and two companies have said they have been working to minimize the impact to the overall RMP so that they can still complete the program in 2011, as originally planned (Defense Daily, Sept. 10).

Mazur said Nov. 26 progressing into flight testing with the DTUs, which began on Oct. 30, “demonstrates not only the technical maturity of the highly complex radar itself, but also the ability of the B-2 industry team to identify and resolve technical issues in a positive, collaborative manner.”

The Oct. 30 flight demonstrated “substantially improved antenna performance,” according to Northrop Grumman.

The installation of the two DTUs on AV-3 establishes a configuration that is electrically equivalent to the production version of the radar units planned for the program, Mazur said.

Flight testing with the two DTUs will continue through early 2008. Thereafter, Northrop Grumman said it will install two production-representative radar arrays, known as development units (DUs), in AV-3. These units, also supplied by Raytheon, will incorporate minor hardware changes unrelated to radar performance, Northrop Grumman said. They will support the final radar development, integration and testing activities that will lead to the production phase of the RMP that is expected to begin in 2008, the company said.

The Air Force places the total estimated cost of the B-2 RMP at $1.386 billion, including $819 million for development and $567 million production activities.

It anticipates that the B-2A, currently the only stealthy, penetrating long-range strike aircraft with a large bomb-and missile-carrying capacity in the U.S. arsenal, will remain in service for about three more decades, if not longer.