On Monday, SpaceX announced that it would be holding a Hyperloop pod competition, inviting universities and private companies to build passenger pods based on SpaceX CEO Elon Musk's open sourced Hyperloop design. The company said it would build a one-mile test track for the pods on a lot adjacent to its Hawthorne, California headquarters.
The Hyperloop has been described as high speed rail combined with an air hockey table: in the system, human-sized pods are propelled by linear induction, with magnets on the outside of the pod repelling the magnets lining the track, which is enclosed in a low-pressure tube (to reduce drag on the pods). The system is supposed to move humans and cargo at a rate of 760 miles per hour.
The impetus for the idea was Musk's disapproval of California's attempts to build a high-speed rail system between Los Angeles and San Francisco. Musk detailed this in a 58-page document in 2013 (PDF), claiming that his Hyperloop idea could be built over the same stretch of land as California High Speed rail but for just $6 billion. (California's train system was estimated to cost around $68 billion as of this January.) But Musk decided to step back from the Hyperloop idea as soon as he put it forward. He made his designs open source and publicly said that neither SpaceX nor Tesla Motors, his electric vehicle company, would be building a Hyperloop.
Is a 1 mile long track long enough to test a train that goes 760 miles per hour?
(Score: 2) by kaszz on Wednesday June 17 2015, @05:00PM
The Gizmag article writes about a 4000 meter long linear accelerator to reach 338 m/s using 65 MW at peak load. I think that's the maximum acceleration that will be used. And then given that the test track is 1600 meters long the rest is math. For passenger comfort the g-force has to be artificially limited to no more than 4.91 m/s².
I think the questions to ask is:
* Maximum possible speed at 800 meters?
* Time it takes to travel the test track at maximum acceleration and retardation?
* Limitations by side forces?
* How will linear motor failure be handled when the pods need to stop?
Designing it as a loop would solve some problems but introduce others too, like side forces.
(and who will put up 6 billion US$ to make this happen?)
(Score: 2) by hubie on Wednesday June 17 2015, @08:50PM
On a 4000 m track, getting to 338 m/s would take (ideally - no wind drag, constant acceleration) about 1.5 g's. At that acceleration, the fastest you can get in 800 meters is about 151 m/s. The time it would take to go the 800 meters is about 10.6 seconds (assume an equal amount to stop).
For what it's worth, if don't care about stopping, it would take you about 15 seconds to run the 1600 meters and you'd be going about 218 m/s.