The B-21s are both test units, but the U.S. Air Force aims to produce more of these aircraft, to eventually replace the B-1 and B-2 bombers. So far, the service wants 50% more B-21s than it initially thought, which bodes well for Northrop Grumman. Once completed, the new bombers will carry both conventional and nuclear weapons, but first flights aren't slated to happen until 2022.

On the idea of accelerating the development of the B-21 Raiders, the Air Force's Acting Acquisition Executive Darlene Costello said the aircraft are not far enough along for acceleration. To her, the priority is "to get through the design, get completed, and not introduce concurrency" in the project, according to the Aerospace Manufacturing report. "Once we get through design and get the first ones delivered, we can adjust production rates and maybe affect them that way, but we have to get through the engineering with solid discipline."

Costello went on to say the agency has the design completed. "There are two test aircraft built and it will take a while to get through all the testing. And therefore, there could be some changes as a result of the testing." As of writing, the B-21 project hasn't fallen behind schedule or gone over budget, according to a U.S. lawmaker following the briefing, reports Aerospace Manufacturing. A key concern precluding the design phase from accelerating is the need for the U.S. Air Force to pin down plans for the larger fleet.