But the new bomber's future is not assured. While Libyan and Afghan gunners may be no match, the new planes seem likely to encounter major turbulence at home, as a climate of financial austerity begins to afflict the Pentagon for the first time in a decade and other weapons compete to serve its military role.

Critics have expressed concerns that the Air Force will not fit the bombers into its budget, that their preliminary design is too technically ambitious, and that a key potential mission -- conducting bombing raids over China -- is implausible. They also have asked why new planes are needed when old ones are undergoing multi-billion-dollar upgrades.

By all accounts, the Air Force's track record of making bombers the country can afford is dismal. The B-1 program was cancelled mid-stream by the Carter administration after its cost doubled, then revived under President Reagan. The B-2 grew so costly in the early 1990s that the Pentagon ended up buying just a fifth of the aircraft originally planned.

The B-2s are actually not used much now, partly because few targets justify risking aircraft that cost $3 billion apiece in today's dollars, and partly because their flights by some estimates cost $135,000 per hour -- almost double that of any other military airplane.

The Air Force says the new bomber is slated to cost roughly $55 billion, or about $550 million a plane -- less than a quarter of the price of the B-2. If costs rise, "we don't get a program," Air Force chief of staff Gen. Norton Schwartz recently told reporters, citing a 2009 warning by then-Secretary of Defense Robert Gates, an airpower skeptic, as Gates cancelled an earlier attempt to build a new bomber.

One of the skeptics is Tom Christie, the Pentagon's chief weapons tester from 2001 until his retirement in 2005. He says that if $550 million per copy is the target, "you're talking $2 billion by the time they build the damn thing .... How many times [have] we been through this with bombers? And look where we end up."

"Besides, what do we need it for?" adds Christie, a sardonic scientist who in his three decades working for the military contributed to the design of many of today's most successful warplanes. A jowly man with snow-white hair, Christie has devoted his retirement to highlighting and criticizing what he sees as wasteful Pentagon practices.

Center for Public Integrity

The new bomber program has been accelerated at a particularly risky moment, when its design -- by the accounts of several top officials -- remains up for grabs. The Air Force has said, for example, that it may or may not be given a nuclear mission at some point in the future, a feature that would add to its price tag. The Air Force has also said it is to be "optionally manned," meaning it conceivably could be flown from a ground station, without a pilot in the cockpit. Nothing similar, involving unmanned, armed aircraft that must survive in a hostile environment, has ever been attempted.