The Hyperloop would send multi-person passenger pods through an above-ground tube at 760 miles per hour—nine-tenths the speed of sound. The tube would sit on 20-foot-high pylons that would mostly follow the route of California Interstate 5. Musk estimates the cost of the project to be around $6 billion, or less than a tenth of the estimated cost of the proposed California high-speed rail project, which Musk calls too slow and too expensive. The LA to San Francisco trip would take about 30 minutes of a turbulent-free and quiet ride.
The full details of the plan are available here.
"It would be cool to see a new form of transport happen," Musk said in a conference call with reporters today. He said that he first envisioned a pneumatic tube like the type used to shuttle mail in post offices a year and a half to two years ago. But, he said, his analysis showed that the energy requirements would be too great.
Instead, the updated plan, developed with the help of about a dozen Telsa and SpaceX engineers working part time on the project, calls for a partially evacuated tube—with an air density inside of about 1/6 that of the atmosphere of Mars, or the equivalent of 150,000 feet in altitude here on Earth—with pods inside riding on air skis, some 28 of them per pod. The reduced pressure inside the tube would reduce drag from friction, as would doing away with wheels. Magnetic levitation was considered and then rejected as too expensive.
Musk conceives of the Hyperloop passenger pods as similar to airplanes—lightweight and fast enough not to require the interior space of a passenger train.
Each ski would ride on its own cushion of air, which would be generated through a combination of aerodynamic pressure created by the high-speed passage of the pod through the tube, and compressed air injected beneath the ski. A compressor at the front of each pod would scoop up air for this purpose.
The air compression system provides some propulsive power in the Hyperloop concept, but most of the propulsion comes from linear induction motors. The system includes an aluminum blade on each pod that rides between magnetic elements in the tube to accelerate the pods at the beginning of their journey, and decelerate them at as they near their destination. Energy is captured during deceleration to recharge the system's batteries.
The system could use motors and batteries developed for the Tesla model S electric car. Solar panels on the roof of the tube could supply the needed power.
Musk said in the call that he's considering funding the construction of a demo Hyperloop, perhaps at the SpaceX rocket testing facility in West Texas. Although the tube would have a shortened length, the pods in the prototype Hyperloop would be full-scale, allowing people to ride in them.
Twenty-foot pylons supporting the Hyperloop tube would extend from Los Angeles to San Francisco. Solar panels on the roof would supply all the necessary power.
"If somebody else goes and does demos, that would be really awesome, and I hope somebody does," said Elon on the call, "But if it doesn't look that's happening or if it's not happening in quite the right way, then that's when I'd allocate some time for this."
Giving the project a high priority, said Musk, he could complete a working demo in one to two years. More likely it will take three to four years to get it done. From there, he said, the entire LA to San Francisco Hyperloop could be completed in another four to five years, putting the entire start-to-completion time at seven to ten years from now. "I think that's comparable timing," said Musk, "to the high-speed rail project."
Correction: A previous version of this story incorrectly stated the estimated speed for Hyperloop passenger pods. It is 760 miles per hour, not 800; and the pods would travel at nine-tenths the speed of sound, not faster than.