Keeping Hyperloop Grounded

By: Ruth Zachariah

14 Dec 2020

The thrill of speed aboard Hyperloop might be as unnoticeable as flying. Forces such as drag and friction, however, may alter the performance of Hyperloop at such high speeds [1]. In this blog, we will explore what it will take for Hyperloop to stay on track and travel smoothly.

But first, knowing how Hyperloop is set into motion is as important as how it remains in motion. Hyperloop is fundamentally powered by magnetic levitation and propulsion. Magnetic levitation was first used to operate the high-speed Maglev train in Shanghai, China in 2004, and has since been implemented in countries like Japan and South Korea [2]. The phenomenon consists of using superconducting magnets that are cooled to extreme temperatures to increase the power of its magnetic field.

Having a strong enough magnetic field impacts the ability for the train to move. In high school physics terms, levitation causes like poles to repel and as a result, pushes the pod upward. Propulsion depends on both magnetic repulsion and attraction; like poles, between the back of the pod and the track, repel and push it forward. Along with this, opposite poles between the front of the pod and the track will pull it forward. It is important to note that there is no contact between the pod and the track throughout the ride, eliminating the possibility of friction [3]. Given maglev's potential, it can be argued that Hyperloop will revolutionize transport technology.

Assuming all external factors considered, how will Hyperloop remain on the track? There are two much-discussed types of levitation systems that could be used in Hyperloop. The first levitation system, electrodynamic suspension, relies on repulsive electromagnetic forces between the bottom of the pod and a conducting guideway. Halback arrays, simplified as magnets at the bottom of the pod, help create a magnetic field as the pod moves in the direction of the track. This causes electrical (eddy) currents to form in the track, and these currents will always oppose the magnetic field generated by the pod [4]. As a result, the magnetic resistance will push the pod back on track!

The second levitation system is known as electromagnetic suspension, and is based on attractive magnetic forces. The electromagnets are placed at the bottom of the pod in this type of system. By varying the strength of electromagnets, the gap distance between the pod and the track can be altered. For example, when the current is increased, the pod gets attracted to the track, and the gap distance reduces. This causes a Hyperloop pod to speed up. With a sufficiently high speed, the Hyperloop pod will be lifted, and pushed forward [4]. This is when levitation has been achieved.

Magnetic levitation systems for hyperloop systems have proven to work, at least on a small scale. On November 8, 2020, Virgin Hyperloop successfully completed the first-ever human passenger test in a nearly airless tube in Las Vegas, Nevada! The pod accommodated merely two passengers: Josh Giegel, and Sara Luchian, Virgin Hyperloop's Chief Technology Officer, and Head of Passenger Experience.  The pod blew past at 100 mph on the 500 m DevLoop track until it safely came to a complete stop [5].

Preparing Pegasus, Virgin Hyperloop’s pod, for the first human passenger test in Nevada

This test truly demonstrated the performance of maglev systems in futuristic transportation. Moreover, this milestone inspires us to tackle hyperloop engineering challenges head-on!

References:

[1] A. Davies, "The WIRED Guide to Hyperloop", Wired, 2018. [Online]. Available: https://www.wired.com/story/guide-hyperloop/. [Accessed: 08- Nov- 2020].

[2] M. Contreras, "HSGT Systems: HSR, Maglev and Hyperloop", The Journal; Permanent Way Institution, vol. 136, no. 4, 2018. Available: https://www.thepwi.org/technical_hub_journal_technical_articles/pwi_journal_1018_vol136_pt4/pwi_journal_1018_vol136_pt4_hsgt_systems. [Accessed 15 November 2020].

[3] C. Wellenreiter, "Hyperloop One: Transportation of the Future", Medium, 2017. [Online]. Available: https://medium.com/the-marc-project/hyperloop-science-piece-draft-265618b0d0e7. [Accessed: 08- Nov- 2020].

[4] "Levitation Systems for the Hyperloop | Hyperloop Connected", Hyperloop Connected, 2019. [Online]. Available: https://hyperloopconnected.org/2019/05/levitation-systems-for-the-hyperloop/. [Accessed: 08- Nov- 2020].

[5] A. Hawkins, "Virgin Hyperloop hits an important milestone: the first human passenger test", The Verge, 2020. [Online]. Available: https://www.theverge.com/2020/11/8/21553014/virgin-hyperloop-first-human-test-speed-pod-tube. [Accessed: 12- Nov- 2020].

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