A fresh wave of structures, systems and weapons upgrades is being rolled into the Northrop Grumman B-2 as part of efforts to keep the stealth bomber in the front line to 2050 and beyond.

The drive to sustain the 20-strong fleet enjoys “good support across the board” says Brig. Gen. Robert Wheeler, commander of the 509th Bomb Wing at the B-2’s home at Whiteman AFB, Mo. The case for injecting new life into the B-2 was unquestionably bolstered by U.S. Defense Secretary Robert Gates’s April decision to ax the next-generation bomber project, ambitiously aimed at fielding a new aircraft in 2018. But Wheeler adds the stealth bomber was always part of the equation.

“Even if the next-generation bomber came along, we were always going to be part of the fight.” The upgrade plan evolved for the B-2 is “designed to look to the threats of the future and that’s the plan we have right now. We are exactly on that plan,” he adds. The effort builds on key avionics and systems enhancements, plus new weapons capabilities and initiatives to sustain the low-observable structure and skin.

“We are building a new aircraft from the inside out,” says Col. Kevin Harms, commander of the 702nd Aeronautical Systems Group at Wright-Patterson AFB, Ohio. “We didn’t have the means to remake the aircraft itself but we’ve put together a very strategic plan. The original aircraft design is quite flexible and, although it was originally designed as a nuclear bomber, it has migrated and become a multirole aircraft and we see that continuing as we go forward.”

A key upgrade recovering from a slow start is the delayed B-2 radar modernization program (RMP). Under the RMP, the mechanically scanned antenna of the Raytheon APQ-181 Ku-band multimode navigation and attack radar is being replaced with an active electronically scanned array (AESA). The effort is now well underway, with five aircraft expected to be flying by year-end. Northrop Grumman, which manages the RMP, was awarded a $382-million system development and demonstration (SDD) contract by the Air Force in 2004.

Integration and other issues stalled the RMP and forced Northrop Grumman and El Segundo, Calif.,-based Raytheon Space and Airborne Systems to set up a “tiger team” to get the effort back on track, says Northrop Grumman vice president and B-2 program manager Dave Mazur. “A lot of decisions were being made and technical risks being pushed down the road to meet a ‘need date,’ so we basically said ‘let’s stop and re-group,’” he adds.

The upgrade, which also included a new power supply and modified receiver/exciter as well as the AESA antennae (two per shipset), was instigated because of an upcoming frequency spectrum conflict with emerging digital TV satellite signals. However, the hold-ups have had a knock-on effect because the RMP was designed in conjunction with other systems upgrades as part of efforts to provide the bomber with an “open architecture” for later modifications. “It’s basically two years late, and all the upgrades are backed up,” says Wheeler. “Now my biggest drawback is getting enough aircraft because they’re going through the upgrades.”

“We’ve got two inducted now and three are out there flying,” says Wheeler. A sixth, the final SDD phase aircraft, is in programmed depot maintenance at Northrop Grumman’s Palmdale, Calif., facility. Test results to-date are positive in terms of performance and maintenance. “The picture is very clear, and the crews are quite happy with it. There is also a lot less maintenance. It’s a reliable day-to-day working radar without moving parts,” he adds. The AESA modification will also add “hooks” for future modes, including high-resolution synthetic aperture radar and enhanced land/sea moving-target indication.

Production RMPs for the remaining 14 B-2s are coming under a $468-million contract awarded to Northrop Grumman in December 2008. In mid-June the company passed the second of two Air Force program audits. The first, in February, saw completion of a Verification Compliance Review (VCR)-1, which audited testing of the radar’s hardware and basic operational modes. VCR-2 confirmed results for the testing of the radar’s strategic mission modes. Despite the hold-ups, upgrades are expected to be completed by October 2010.

As well as RMP, most other avionics upgrades are aimed at sustainability as well as performance improvements. “Low observable (LO) is no longer the major maintenance driver,” says Mazur, referring to the support headaches associated with keeping the B-2 stealthy. “That’s now No. 3 and avionics has started to raise its head.” Issues are chiefly concerned with supporting the aging technology which, in most cases, dates from the 1970s and 1980s. Special test equipment is becoming obsolete, with maintainers and suppliers sometimes being forced into scouring eBay for equipment as outdated as floppy discs.