An anonymous reader writes There have been many US military machines of war that seemed to be revolutionary, but never make it out of the prototype stage. As Robert Farley explains: "Sometimes they die because they were a bad idea in the first place. For the same reasons, bad defense systems can often survive the most inept management if they fill a particular niche well enough." A weapon can seem like an amazing invention, but it still has to adapt to all sorts of conditions--budgetary, politics, and people's plain bias. Here's a look at a few of the best weapons of war that couldn't win under these "battlefield" conditions.