The U.S. Air Force expects its next-generation bomber to cost about $550 million per aircraft, excluding development costs, the service's No. 2 civilian said.
"We're still using that as a pretty firm chalk line for those companies that are bidding on it," Undersecretary Eric Fanning said during a breakfast with reporters on Tuesday in Washington, D.C.
"There are a number of people who think it's too low of a number and we're not going to get the requirements out of the bomber that we need," he added. "But what I'm seeing ... is this is keeping both the Air Force and the contractors pretty disciplined about what they propose putting into the bomber."
The figure refers to the estimated unit production cost of the Long-Range Strike Bomber, or LRS-B, and doesn't include research and development expenses, which are likely to be significant. Fanning declined to specify what the latter might be, only that they wouldn't "double" the overall cost of the plane.
The new bomber is one of the Air Force's top three acquisition programs, along with the F-35 Joint Strike Fighter and the KC-46 refueling tanker. The service requested $700 million for "strategic bombers" in fiscal 2015, which begins Oct. 1, a $100 million increase from this year, according to Pentagon budget documents.
The Air Force may buy between 80 and 100 of the aircraft, which are designed to succeed the B-2 Spirit made by Northrop Grumman Corp. Lockheed Martin Corp., the world's largest defense contractor, has teamed up with Boeing Co., the world's largest aerospace company, to challenge Northrop for the work.
The undersecretary said the Air Force is "still hewing pretty close" to the target production cost in part because former Deputy Defense Secretary Ashton Carter "was passionate about" using it as a requirements-shaping constraint on the development process, Fanning said.
The service has said the bomber will have the option to be unmanned and able to penetrate increasingly sophisticated enemy defenses -- so-called anti-access, area-denial, or A2-AD, environments.