The first B-21 Raider test aircraft is about halfway through an extended period of loads calibration testing, during which Northrop Grumman is stressing a production-representative bomber to avoid risk during production. This intensive process has pushed the aircraft’s first flight back to 2023.

• Original schedule was for late 2021
• Northrop Grumman says most of its critical load condition testing is done
• U.S. Air Force and Northrop want first test aircraft to be representative of production bombers

Northrop Grumman says the initial flight test aircraft has completed the first and most critical of three major loads calibration conditions as part of the process in a fixture at its Plant 42 facility in Palmdale, California. The OEM says there are three “major” conditions—a combination of stress on the airframe from 0-100% to represent different flight and maneuver conditions—that the aircraft must meet before moving on to a rollout and then first flight. The company has not provided the exact specifications of these metrics.

“Northrop Grumman has put significant emphasis on production readiness as one of the many priorities and risk reduction efforts we’ve employed on the B-21 program,” says Doug Young, Northrop Grumman’s vice president and program manager for its strike division. “From Day 1, we’ve aggressively worked to seek out discovery early and to burn down as much production risk as early as possible.”

The intensive loads calibration testing process has changed the closely tracked planned first flight date for the B-21 to 2023 after a public rollout still expected for this year. The first flight was originally projected for last December, then for mid-2022 before this latest move, Aviation Week first reported. However, the new date is not firm and will likely shift as testing continues, the U.S. Air Force says.

Randall Walden, director of the Air Force’s Rapid Capabilities Office, which handles the B-21 program, tells Aviation Week that the loads calibration process was about halfway completed as of mid-May. The Air Force said in early March that testing was beginning, with the actual process starting only after the public announcement. The service also announced that the sixth B-21 had entered production.

“That’s the first time an airplane gets to go in, and [we] figure out how well it works from a structural point of view,” Walden says. “And you typically do that on a new aircraft build anyway. So we’re going through that type of testing. And notice what I said: Testing. It’s all about the data and events that drive us to things like a rollout and drive us to a first flight.”

The loads calibration process both tests the structural capability of the aircraft and then calibrates strain gauges in preparation for the flight test. Northrop Grumman says the loads calibration so far has yielded “very positive and consistent results” and is reaffirming its digital models of the aircraft.

“Those two things are going on simultaneously, Right now I believe they’re still in the middle of loads [calibration], making sure all of that’s making sense,” Walden says. “I won’t go into a lot of detail precisely of what the numbers look like. But in general terms, we’re on a good path, and everything’s looking very good based on what we’re seeing.”

The B-21 is unique compared to other new-build military aircraft because the program wanted to use the same production and manufacturing process for the initial aircraft as it will use for the entire production run.

“In normal programs, you don’t typically build the test aircraft the same way you build a production aircraft. We did that differently on the B-21,” Walden says, adding that the goal is to achieve an operational capability earlier.

Northrop Grumman and the Air Force are flying a representative testbed with all avionics and flight programs to reduce risk as ground tests continue, along with testing software and other subsystems, Walden says.

Once loads calibration is completed and the aircraft is publicly rolled out, that will allow for more ground testing ahead of the first flight.

“All of the indications today are that we’ll roll it out this year,” Walden says. “Now once you roll it out, that means it’s in a state where you’re ready to actually start getting some more test data. That test data includes engine starts, applying electrical, things of that nature, and then doing low-speed taxi and high-speed taxi. Those three major events are normally done prior to first flight.”

While this process is dictated by data and not dates, Walden says normal programs take about six months from rollout to first flight. This general schedule would mean a first flight in spring to early summer of 2023 if the rollout is complete by the end of 2022.

Northrop’s B-2 Spirit, for example, rolled out in a November 1988 public ceremony and first flew in July 1989.

“All of that data would suggest that you’re now ready for first flight,” Walden says. “So it’s not schedule-driven, it’s event-driven and data-driven. And all that data will tell us when we actually do first flight. Normal programs are usually within six months after rollout that you’re flying. Normal. Again, all the data and events that happen over that time frame will suggest whether we fly or not.”

Like the B-2 in 1989, the B-21 will make its first flight from Palmdale to Edwards AFB, California, for extensive testing in the air. Edwards has reactivated its 420th Flight Test Sqdn., as part of the Air Force Test Center’s 412th Test Wing, to oversee this process.

The service wants to buy at least 100 B-21s, but Air Force officials say there is a goal of 145 bombers to meet its minimum capacity. The B-21 is expected to first enter the fleet in the mid-2020s at Ellsworth AFB, South Dakota, and replace the current B-2 and B-1 fleet.

The Air Force, in its fiscal 2023 budget request, calls for $3.3 billion in research, development, test and evaluation funding for the bomber along with $1.8 billion for procurement. Over five years, the service expects to spend $19.6 billion for B-21 procurement, according to budget documents. The 2023 request includes funding for multiple bombers in the first annual lot of low-rate initial production. The service did not specify how many will be procured per year but said more than one will be bought in fiscal 2023. The projected nonrecurring average unit cost for each B-21 is $623 million when adjusted for inflation.

Lt. Gen. David Nahom, Air Force deputy chief of staff for plans and programs, told the Senate Armed Services Committee on May 17 that the service is focused on development with no real way to accelerate the bomber’s timeline yet.

“If there’s any acceleration, it’ll be after we develop and field,” Nahom said. “There may be some acceleration in the numbers we buy after we have fielded the aircraft, but right now . . . there’s no acceleration. We’re moving at a good pace, but we don’t see an acceleration in the near term.”

Ongoing, steady investment in the B-21 program has kept it well resourced and on track, though there likely will be issues that arise as development and testing continue, Lt. Gen. Duke Richardson, the military deputy in the office of the assistant secretary of the Air Force for acquisition, technology and logistics, said during the same hearing.

“It is a development program, and we’ve got a lot of work ahead of us. I don’t know what bumps might come, but there’ll be bumps along the road. And as we finish out the program, we have to work through them,” he told lawmakers when asked what the Air Force needs. “[We need] just the patience to continue working with us, as we work through whatever bumps are there. And to be clear, I don’t know of any. Through all my years of experience, most programs we’re doing have bumps along the road.”