While US military has had its fair share of bungled development programs — just look at the V-22 Osprey or the littoral combat ship — the ill-fated A-12 Avenger II is a strong candidate for the worst. It was so poorly managed that, if completed, the program could have sunk nearly all of the US Navy's budget.
The A-12 Avenger II concept was a two-seater, all-weather, carrier-based stealth bomber; the result of the US Navy's Advanced Tactical Aircraft (ATA) program, which aimed to replace the ageing fleet of A-6 Intruders by 1994.
Built by McDonnell Douglas/General Dynamics, the A-12 featured a Flying Wing design that drastically reduced the plane's radar and infrared signature compared to the A-6. Its dual nonafterburning turbofans would have given the A-12 the ability to carry 2340kg of armament up to 800 nmi at speeds topping 930km/h.
Full-scale mock-up displayed at an open house in 1996 at Caswell AFB
Unfortunately, the A-12 program never got off the ground, plagued by severe cost overruns and embarrassing delays. The prototype plane weighed 30 per cent more than the design spec, preventing it from operating on the carriers it was designed for. The entire project, by some estimates, could have ended up accounting for 70 per cent of the Navy's aircraft budget within three years.
These setbacks, combined with shrinking defence budgets in the Post-Cold War era, were enough to convince then-Secretary of Defense Dick Cheney to pull the plug on the whole fiasco in 1991. The US Navy instead focused on multi-role fighters like the F-18 Super Hornet and F-14 Tomcat, as opposed to the less-versatile stealth bomber model.
And while the A-12 itself is no more, much of the plane's advanced avionics systems made their way into the later F-117 bomber. And some parts of the plane actually made it onto eBay. [Aviation Intel - Wiki - FAS]