A close up view of a US Air Force B-2 Spirit Bomber from 509th Bomb Wing, Whiteman AFB, MO being refueled by the boom and refueling arm of a KC-10 Extender aircraft. The image was taken from the Boom Operators

Aviation week & Space technology March 9th 1992 reported that the Northrop be to a TB stealth bomber utilizes a member of classified black Technologies designed to enhance its stealth capabilities

The B-2 Spirit is perhaps the most expensive bomber ever built, costing over $1 billion per aircraft (when all the R&D costs are factored in). For that money, though, there is a lot of capability this