The Science of a Hyperloop Pod
Imagine, in the not so distant future, taking a transit system that moves people and things cleaner than automobiles, yet faster, cheaper, and more reliable than airplanes. It’s a challenge that SpaceX founder Elon Musk has given to the world, and one that an ambitious group of engineers at the University of Cincinnati feel that they can rise to.
Hyperloop is a revolutionary transit concept through which a pod carrying passengers and cargo travels through a tube at over 700 mph using only renewable energy, and is still cost effective, with the average one way ticket price around $27. It may sound like something from a science fiction film, but if completed, the system could take passengers from Los Angeles to San Francisco in about 30 minutes. While a daunting task to many, it’s just the kind of challenge that Dhaval Shiyani was itching for. Shiyani is the founder and team leader of Hyperloop UC, a group of over 40 engineers and scientists building a prototype pod for the Hyperloop system. I sat down with Shiyani to talk about some of the science and engineering that goes into building a system like this from scratch.
How it works
As you might imagine, a transit system of this level of sophistication comes with it’s share of engineering obstacles. Hyperloop has no wheels and the pod levitates as it moves through its tube from which most of the air has been removed in order to reduce friction, with the thrust provided by induction motors on the track.
“One of the challenges was to design light-weight systems that operate in low-pressure environments.” says Shiyani. “The lighter the system, the faster it will go, so we tried to shave off as much weight as we could from our design.” The team considered using composite materials such as carbon fiber, but found that material too expensive. Instead, they used aluminum to make the frame, and though hard to weld, has a better strength to weight ratio than steel.
However, even in this low-pressure environment, the tube is not a perfect vacuum, and there are still issues with the air providing friction. Engineers run into something called the Kantrowitz limit, which limits how big a pod can be in a tube. The bigger the pod relative to the tube, the more the air molecules get compressed as it moves forward. Instead of air moving around the pod, at high speeds the pod will act like syringe, pushing the entire column of air. In order to keep the tube to a manageable size for building, that air needs to be removed. The solution to this was to put an air compressor on the front of the pod, removing the air in the front and pushing it out the back, alleviating the air pressure in the tube.
Levitation is another obstacle. At first the group tried air bearings, using pressurized air being pushed through the bottom of the pod. The trouble with this is that it’s very heavy and bulky, adding to the amount of energy required to move the pod. The pressurized air is also extremely unsafe, and could explode.
The team decided to go with an electrodynamic suspension (EDS), which uses spinning magnets to push the pod up. When magnets spin, they generate an electric field. When the magnets spin fast enough, the electric field generated would be strong enough to push the pod up from the aluminum track. While safer and lighter than using compressed air, getting the powerful magnets to function correctly was something the team had to study extensively, as no one had prior experience using dynamic magnets.
Perhaps the biggest challenge has been coordinating all the different sensors and instruments needed for Hyperloop to function safely and effectively. Programming the software that oversees all the independent systems has been a difficult undertaking. Shiyani says “You need to know the pod’s location, speed, and levitation information all the time in real time.” Since there’s no conductor, everything needs to be autonomous and remote, including emergency systems, which complicates things even further. 100% accuracy at these speeds is a must.
The University of Cincinnati Team
The Hyperloop UC project began back in 2014. After graduating from the University of Mumbai, Shiyani came to Cincinnati to work on his master’s degree in engineering. Always a big fan of Musk, Shiyani was interested in the possibility of working on the revolutionary transit system. He then found a 58-page white paper written by Musk himself, describing the details of how such a system work would. “I remember sitting working my graveyard shift in the dorm and reading this paper, and I thought that would be cool to work on.”
Eight Months later, SpaceX announced an open competition to design the pod that would carry passengers through the Hyperloop tube. Shiyani began assembling his team and submitted an application. For months, the small group worked on plans for their pod design, adding team members on the way. Out of more than 1200 designs submitted, the UC team was one of 124 to be invited to a design review in Texas in January 2016.
After convincing the Dean of Engineering to provide a small amount of funding, Shiyani and the rest of the team drove 16 hours through the night to College Station, Texas. After an intense weekend, the UC Team had moved on to the finals, one of 25 teams to do so. Upon returning to UC, the team met with the Dean and the then university president,, Santa Ono, and they secured enough funds to start building a prototype. Over the last 12 months, the team has grown to nearly 40 people and several community partners that have generously donated advice or workspaces. The dean of engineering has even loaned space in his personal lab for the Hyperloop team to work.
They are now on to the finals with schools such as MIT, Cal Berkley, and Purdue. Their hard work and creativity will be tested at the design competition January 27-29, 2017 at SpaceX’s facility in Los Angeles to determine if their design will be used to make future Hyperloop tracks. The pod will be graded on final construction, safety and reliability, performance in tests, and performance in flight. Shiyani and the rest of the UC Hyperloop team is are looking forward to the competition, as few expected their group to go very far. They’ve risen to the challenge and exceeded many expectations, including their own. Win or lose, their hard work has contributed to making a fast, clean, and reliable transportation system a future reality.
Check back soon for updates on UC Hyperloop Team’s performance at the design competition finals!