Secret Plan for 'Invisible Bombers'

The U.S. has invested more than GBP1bn in a "black" programme to design a next-generation bomber with a radar stealth signature less than one-tenth that of a mosquito, according to military sources.

The Northrop Grumman corporation is understood to be building the demonstration prototype for a classified U.S. Air Force plan to field the first squadron of almost undetectable strike aircraft within a decade.

The unclassified version of the USAF budget shows no funding for the new bomber, but company documents show unexplained funds for "technology work" between 2008-10.

Northrop Grumman chief executive Ron Sugar said last year that the company's integrated systems aircraft division had made strides in black projects and had identified them as the top new-business opportunity.

Rivals Boeing and Lockheed Martin - designer of the original F117 stealth jets first used in combat against Serbia and Iraq - announced in January they were teaming up on a new stealth project.

Lockheed Martin "Skunk Works" leader Frank Cappuccio said at the time that his company had decided not to partner Northrop Grumman because of unexplained "openness issues". Boeing and Lockheed Martin say they have not received any government funding.

Sources say the advanced aircraft will be made of revolutionary materials created to absorb or deflect radar pulses and will incorporate advanced aerodynamics.