Moving troops by land, sea and air has required a wide variety of military vehicles during the era of modern warfare. Trains, trucks, ships, aircraft and helicopters have all done their part to transport divisions across oceans and continents, move units up to the frontline or carry soldiers directly into combat. But the U.S. military and other forces have also experimented with an astounding lineup of troop transport vehicles that never saw action.

The lineup includes strange mobility concepts such as a hover vehicle that resembled a flying saucer, an amphibious vehicle based on rotating screws and a walking machine that echoes of four-legged robots being tested for today's military. Such vehicles also range in size from a single-person, flying scout vehicle to a huge flying boat designed to airlift hundreds of troops across the Atlantic Ocean during World War II.

Some proved too wild in their design, others came too late in a war and a few were just too ahead of their times. Who knows? Maybe some designs will show up again on future battlefields. For now, the U.S. military can look forward to trying out some flying car prototypes.