Elon Musk details Hyperloop
 

Elon Musk is into transportation, whether it's an electric car or a spaceship. Today, he detailed a plan to revolutionize a portion of public transit. It's called the Hyperloop, and it's meant to get folks from SF to LA (or any two cities less than 900 miles apart) in 30 minutes seated in aluminum pods that are hurtled to and fro at 800 miles an hour in a pair of steel tubes. To keep things safe, pods will be spaced five miles apart so that they can stop without running into each other, which means a total of 70 pods could operate simultaneously.

Of course, the real question is how to get the pods moving at those speeds? One main issue with such transport is wind resistance (and associated friction) that increases as the speed of the pods inside the tube escalate. Naturally, one could operate the tubes in a complete vacuum, but keeping such a system free of air would be difficult to maintain over such long distances. Instead, the Hyperloop system will work as a low air pressure environment that is easily maintained with standard compressors. Additionally, "an electric compressor fan on the nose of the pod that actively transfers high pressure air from the front to the rear of the vessel" is there to relieve what air does build up at the front. This compressor fan would also provide an air bearing around the pod to keep it suspended in the middle of the tube, much as an air hockey table suspends a plastic puck. As for power? Well, that would come from external linear electric motors positioned every 70 miles to keep the pods humming along at subsonic speeds.

http://www.engadget.com/2013/08/12/e... ign=Engadget