The world’s most expensive bomber traces its roots to World War II

The B-2 Spirit is the most expensive bomber ever built, with a $500 million fly-away cost that climbs much higher when the RD costs are taken into account. The B-2's story, though, really starts in World War II – because the B-2 was the culmination of an idea.

Aviation historian Joe Baugher notes that Jack Northrop, the founder of Northrop Aviation, had been pursuing the flying wing since 1923. By 1940, he got a technology demonstrator up.

The next year, the U.S. Army Air Force was looking for a long-range bomber that could hit Europe from bases in the U.S. in the event England were to be knocked out of the war.

Northrop submitted a four-engine propeller-driven design that the Army Air Force designated the B-35. It was to have a range of 8,150 miles, a top speed of 391 miles per hour, and a maximum bomb load of 51,070 pounds. Production versions were to have up to 20 .50-caliber machine guns for defense.

The plane had a difficult development, and fell behind schedule. The Army Air Force, though, saw potential and kept it as a research project. Northrop was asked to develop a jet-powered version known as the YB-49, replacing the propeller-driven engines with eight jet engines. While this increased the top speed to 493 miles per hour, it cut the range down to about 4,000 miles.

The plane had its share of problems. Keeping the plane steady was very difficult in the best of times, and it was missing targets when it dropped bombs. Then, one of the YB-49s crashed on June 5, 1948, killing all four crew, including United States Air Force Capt. Glenn Edwards.

There were also hot disputes over the plane's manufacturing. Northrop insisted on having his company build the B-49 and its variants, while the Air Force wanted Northrop to work with Convair, which had designed and built the B-36 Peacemaker and B-32 Dominator bombers. Jack Northrop would later claim that the Secretary of the Air Force had demanded that Northrop agree to a merger of his company and Convair.

Northrop would abruptly retire and sell off his interest in the company he founded. However, shortly before his death in 1981, he was returned to Northrop, where Air Force officials took the extraordinary step of showing him a scale model of what would become the B-2 Spirit. The B-2 would be able to reach operational status in 1997, largely because by this time, the technology to address the stability issues had been developed.

Today, 20 B-2s are in service with the Air Force, and the service plans to buy another flying wing, the B-21 Raider.