3 of the Greatest Obstacles to Hyperloop
By: John Hu
Tags: Hyperloop, Physics, Transportation

And how we might solve them

Introduction

In early 2013, Elon Musk introduced the Hyperloop. It promised to be a revolutionary form of transportation. With a proposed speed of 760 mph or 1220 km/h, Hyperloop will be the fastest land-based system to exist.

Inside a vacuum tube, pods are accelerated at high speeds since there is little air resistance. Instead of moving on rails like bullet trains, Hyperloop uses magnetic levitation(maglev) to avoid any friction that would slow it down.

Besides offering lightning quick speed⚡️- it could also reduce deadly car crashes, connect people living far away, and create a sustainable future.

However, there are some obstacles that engineers are still working on.

g-forces Vacuum compression Economics

1. g -forces

Photo by Gabriel Valdez on Unsplash

Have you ever wondered why Roller-coasters are so exhilarating?

Well, it comes down to Newton’s third law.

As the rider and cart accelerates, there is a force exerted on you. When you suddenly dive down, you can feel the force pushing you back into the seat.

Let’s discuss why this can be problematic. Once a>0.5 g, where g is the acceleration due to Earth’s gravity or 9.81 m/s², it can cause headaches, problems with blood circulation, and even loss of consciousness. 🔴

But there’s also another force called the centripetal force when the Hyperloop curves. While you might not have heard of this force, it keeps the moon in orbit and makes cars skid when they turn.

Based on basic math, as r decreases, the centripetal force will increase. The tighter the turn, the greater the “outwards” force.

This makes the ride difficult to handle. The solution? Banked curves.

If you’ve wondered why race car tracks are tilted, they are there to counteract this outwards force that would otherwise fling the cars out of the track. Here is a great example of a banked curve.

Daredevil bus straight out of Mario Kart

Such a bank creates further vertical acceleration, which makes the ride even more unpleasant.

Since Hyperloop targets many demographics — business travelers, the elderly, children, handicapped people, it will need to be comfortable in order to be widely accessible.

Solution: Lowering acceleration

If passengers feel sick aboard the Hyperloop, it’s going to be

when it starts when it turns when it stops.

Reaching the Hyperloop’s maximum speed of 760 mph at a manageable 0.3 g would only take around 15 km. So far, so good.

But then the Hyperloop makes a curve. It will either need to decelerate or curve over a large distance. One research paper puts the curve radius at around 2000 m at 300 km/h. So, at Hyperloops max speed of 1220 mph, the radius would need to be 8051 m or 8 km!

Now you might wonder. Can’t it travel in a straight path from point A to point B? Well, barriers like rivers or hills can’t be directly crossed, they have to be bypassed. Most of the testing for Hyperloop is in Nevada, but future projects in India, Mexico, and Canada could be on rugged terrain.

But there’s more than acceleration from the pod. A greater problem is acceleration from air..

2. Vacuum compression

The Hyperloop is like a large balloon with no air inside

Imagine a deflated party balloon. When you blow air into it, it expands. This is because the particles inside jostle each other and push outwards.

It turns out they are pushing against the atmosphere. Or 10,000 kg or air every square meter. Normally, this is fine. Here is when it becomes a problem.

Pull all the air out of the balloon and you get a vacuum. The pressure inside the balloon is low because there are no more particles. Suddenly, all the atmospheric pressure is crushing the balloon. POP!

A solution is strengthening the walls of the balloon. Now the balloon won’t pop. Except for the fact that it can still be popped with a pin. This also applies to the Hyperloop.

If the Hyperloop punctures, all the outside air would rush in, shooting the pods back at fatal speeds. One source puts the acceleration of the pods at 7.5 m/s². In less than 4 seconds, they would accelerate to 100 km/h! From the numbers alone, it’s clear that it has to be safe or nobody will ride it.

Solution: Innovative materials and smart sensors

Currently, Hyperloop designs feature steel tubes with reinforced concrete. The walls of the tube will need to be thicker than the proposed 25 mm to account for weather, wind, and other factors.

New super alloys could also be used such as Aluminum Matrix Composites(AMC). Because these materials are expensive right now, they will be suitable for important parts of the tunnel such as these airlocks.