How does hyperloop work? Everything you need to know about magnetic levitation

Elon musk’s transport pods could revolutionise the way we travel, but how do they work?

Libby Plummer
1 Sep 2017

First honed as a concept by Tesla and SpaceX founder Elon Musk in 2012, hyperloop is touted as the future of passenger transport.

For the uninitiated, hyperloop is a high-speed passenger transport system that involves a sealed tube through which high-speed pods move, slashing travel times. For example, the journey from London to Edinburgh - which takes more than four hours on a train -  would theoretically take just 30 minutes.

Musk has since encouraged startup firms and student-led projects to create their own versions of hyperloop. The high-speed system uses a version of magnetic levitation, but what is it and how does it work?

What is magnetic levitation?

Magnetic levitation, or maglev, is when an object is suspended in the air using only magnetic fields and no other support.

Along with super-fast maglev trains, magnetic levitation has various engineering uses including magnetic bearings. It can also be used for display and novelty purposes, such as floating speakers.

How does magnetic levitation work?

 Magnetic levitation’s best-known use is in maglev trains. Currently only in operation in a handful of countries, including China and Japan, Maglev trains are the fastest in the world, with a record speed of 375 mph (603 km/h). However, the train systems are incredibly expensive to construct and often end up languishing as little-used vanity projects.

There are two main types of maglev train technology - electromagnetic suspension (EMS) and electrodynamic suspension (EDS).

EMS uses electronically controlled electromagnets in the train to attract it to a magnetic steel track, while EDS uses superconducting electromagnets on both the train and the rail to produce a mutually repellent force that makes the carriages levitate.

A variant of EDS technology - as used in the Inductrack system - uses an array of permanent magnets on the underside of the train, instead of powered electromagnets or cooled superconducting magnets. This is also known as passive magnetic levitation technology.

How does Hyperloop use magnetic levitation?

In Musk’s original concept, the pods floated on a layer of pressurised air, in a similar way to pucks floating on an air hockey table. However, a more recent version of the technology from Hyperloop Transportation Technologies (HTT) - one of two companies leading the hyperloop race - uses passive magnetic levitation to achieve the same effect.

The technology has been licensed to HTT from Lawrence Livermore National Labs (LLNL), which developed it as part of the Inductrack system. This method is thought to be cheaper and safer than traditional maglev systems.

With this method, magnets are placed on the underside of the capsules in a Halbach array. This focuses the magnetic force of the magnets on one side of the array while almost entirely cancelling out the field on the other side. These magnetic fields cause the pods to float as they pass over electromagnetic coils embedded in the track. Thrust from linear motors propels the pods forward.

HTT’s main rival, Hyperloop One is also using a passive magnetic levitation system where pod-side permanent magnets repel a passive track, with the only input energy coming from the speed of the pod.

For both systems, air pressure in the tunnels is lowered using air pumps in order to aid the pods’ movement. The low air pressure dramatically reduces drag so that only a relatively small amount of electricity is needed to achieve top speeds.

When will hyperloop launch?

The hyperloop system does appear to be progressing with Hyperloop One recently managing to shoot a passenger pod through a test tube at 192mph (309km/h). But while impressive, it still falls well short of its 250mph (402km/h) goal.

A student team from the Technical University of Munich recently managed to reach an impressive top speed of 201mph (324km/h) on SpaceX’s custom-built 1.5km test track in Hawthorne, California. The extraordinary achievement was part of Elon Musk’s Hyperloop Pod Competition.

The first commercial hyperloop track could be built by Hyperloop One in the UAE, after the company agreed a feasibility study with the  Dubai Roads and Transport Authority (RTA). The proposed system would connect Dubai and Abu Dhabi with a mere 12-minute journey. However, despite various proposed projects around the globe, critics claim that hyperloop infrastructure is far too costly to ever develop into a comprehensive transport system.

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