The 11 most terrible military vehicles ever! (With Pictures)

9. Caspian Sea Monster

Another way to remain fuel efficient is to take advantage of certain aerodynamics. For planes, sticking close to the earth helps create “ground effect” where drag forces decrease and lift forces increase. That’s the concept behind the Caspian Sea Monster, a plane built in Russia in the 1960s. It was supposed to fly extremely close to the ground, between 15 and 30 feet above, to create a cushion of air to lift it. The giant could still reach top speeds of over 300 mph.

The Caspian Sea Monster crashed in the ’80s due to pilot error and was never recovered from its watery grave due to its sheer weight – over 150 tons – and size. Despite being a top project during the Cold War, Russia seems to have given up on ground effect flight.