Quick Fire Science: Hyperloop Trains

Could trains be built to travel as fast as jet liners?
22 August 2013


Steam train


US-based entrepreneur Elon Musk is not a man who's lacking ambition in life. His company Space-X has already built rockets which compete with those used by NASA and the European Space Agency, and last year one of them became the first commercial spacecraft to visit the International Space Station. This week, however, it's another of his projects which has been in the news - a new kind of train which he thinks could transport people over the 350-miles between Los Angeles and San Francisco in only 35 minutes.

- The Hyperloop trains work by seating passengers in capsules, which are then fired down tubes at close to the speed of sound.

- To reduce air resistance, vacuum pumps will suck most of the air out of the pipe.

- The pumps will be powered by solar panels on the top of the tube, but one tiny crack anywhere along its 350-mile route could bring the trains to a halt.

- No one has ever made such a large vacuum tube before. The closest they've come is the Large Hadron Collider, but even that is tiny in comparison to what Elon Musk is proposing.

- To reduce friction even further, magnets are used to levitate the capsules in the middle of the tube, without any contact with tube's walls, just like a mag-lev train.

- But magnets are also used to propel the capsules forward, using an arrangement called a linear motor.

- In such a motor, a magnet on the front of each train interacts with magnets on the side of the tunnel. These attract the train as it approaches, and are flipped to repel the train as soon as it passes, so that they always push the train forwards.

- Assuming that capsules are fired once every two minutes, and each could carry 28 passengers, Elon Musk thinks that the system could carry over 800 passengers an hour.

- One of the biggest difficulties of travelling so fast is that even the slightest bend in the track will produce enormous g-forces in the capsule, so the track has to be almost completely straight.

- But these trains might take a while to get off the ground. Elon Musk says he's too busy with other projects to build it himself, but hopes someone else might step in.


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