Select the desired text size (persisted using cookies):


The Hyperloop Might Actually Work—and It's Less Radical Than You Think

Hyperloop Revealed

John Gardi is a tinkerer and jack-of-all-trades currently living in Canada. He garnered himself a slice of internet fame when he made a mock-up for Elon Musk's mysterious Hyperloop transportation system, and Musk himself dubbed it the "best guess" he'd seen yet. Here, Gardi explains his reaction to the project's reveal, why the project isn't actually so radical—and how it can work.

Finally, after much anticipation, Elon Musk released the preliminary design for his Hyperloop transportation system. The document lays out the how and why of the Hyperloop concept in generally understandable terms. I’ll try to distil it down to the high points here, but the full document won’t tax most folks. I applaud Elon Musk and the Space X team for that!

We now know for sure that there really isn’t a loop anywhere in the Hyperloop transportation system. Each of the opposing direction tubes is a separate machine which would only share components, like the pylons holding them up or the power system, for convenience, not necessity. The two tubes are not connected in any way other than structurally. The only 'loop' in Hyperloop is in the perception of the passenger on a return trip. Hyperway would have been a better descriptive, I think.

Hyperloop Pod

How Hyperloop Will Work

So, lets get right down to the nitty gritty of what Elon Musk has come up with this time!

Here’s a breakdown of what Hyperloop really turned out to be:

  • It is a closed twin tube transportation system providing uninterrupted traffic in both directions.
  • It will be elevated, as I speculated in my first article. No surprise there, it really is the only economical choice. (Don’t give me too many points for that one!)
  • The tubes will be partially evacuated of air, about 1/6 the air pressure on Mars or equal to an altitude of 150,000 feet in Earths atmosphere, or a partial vacuum.
  • The cabins of the pods would therefore be pressurized with a backup air supply and oxygen masks for emergencies.
  • The pods will be propelled by a rail gun powered by Hyperloop’s power system. We can assume solar panels and battery packs here.
  • The pods will ride on a cushion of compressed air powered by batteries in the pod and mostly coast between the rail gun at each end.
  • The pods will travel very fast and must do so to be efficient. The maximum velocity would be just below the speed of sound, about 700 miles per hour.

Two different distinct systems with two different pod approaches are being proposed, not just one:

  • The first is an all passenger version carrying 28 seats.
  • The second, I’m assuming larger, system would carry three automobiles and their passengers.
  • The Hyperloop system would split the power load between the pods batteries and the Hyperloop's own power systems to maximize efficiency.

The rail gun is actually a motor split from the outside through to the axle and then rolled out flat. Well, not really, but I hope it gets the idea across. The motor is made up of two parts, the rotor, a solid hunk of metal, usually copper, that the electromagnetic coils, or stators, can grab onto.

In the case of Hyperloop, the solid metal rotor will be on the pods—dead weight until the stators magnetically grab them. The rail gun coils are built into the tube walls and would be hooked into Hyperloop’s electrical system. The coils are energized to grab the pods at just the right moment, and accelerate them down the tube at high speed. The pod essentially gets a free ride using no more power from its battery than if it was standing still.

Once the pod is up to its maximum cruising speed, it coasts on an almost frictionless cushion of air. This is where the pod needs it’s own power and where Elon Musk’s design solution becomes really interesting!

This is where Elon Musk left the rest of us in the dust:

Firstly, there’s that cushion of air, literally like invisible ball bearings. Elon Musk even calls them ‘air bearings’ in his proposal. The principle is simple, take the rails off an air hockey table and flip it upside down so the playing surface is touching a smooth floor.

Turn it on and it’ll float slightly above the floor and would probably still float if you stood on it too. Heavy cargo movers in warehouses work the same way. In Hyperloops case, the air bearings are only at the bottom too, not all the way around the pods body as many of us thought it would be, including me!

So, now you know the basic principle behind the Hyperloop concept:

  • The Hyperloop Tube will be in a partial vacuum.
  • The rail gun will speed the pod up to maximum velocity.
  • The air bearings will allow the pod to glide almost frictionlessly.

Hyperloop Elevated

We have everything we need for a 400 mile coast up the coast in half an hour, right?

Not so fast. Even air pressure equal to 150,000 feet is thick enough to cause a lot of drag at high speed. It might be 1,000 times less air pressure than at sea level but it’s still dense enough to slow you down too much to make it 400 miles by coasting alone.

So, here’s part two of Elon Musk’s solution. The pods don’t fill a majority of the tube! So, instead being like a battery going into a cylindrical flashlight, these Hyperloop pods are more like a subway or train in a tunnel with lots of clearance to the tube wall, except at the bottom where the air bearings are. This way the thin air has a way around the pod instead of pushing it in front, building up pressure and slowing the pod down. This helps some but the pod still takes up to much room in the tube to be prevent a lot of drag.

If we can’t move the pod out of the way, how about we move the air instead!

The solution then is to have a large inlet on the nose of the pod, like a post-World War II Saber jets. Behind the inlet, a set of large turbine blades, just like you’d see in a dismantled jet engine. take up the whole front end of the pod. The turbine is spun by a powerful electric motor and it easily compresses the air and uses it two ways:

  • Some of the air is highly compressed for use in the air bearings. Bottled air can be used as a backup for the air bearings in case of power failure in the pod.
  • Most of the air sucked into the pod is channeled through the its body around the passenger compartment and funneled right out the back, just like those old Saber jets!

We have one system doing two jobs and it’s nice when you can get that! The electric turbine maintains the compression level for the air bearings and also eliminating most of the drag by becoming ‘invisible’ to the air, passing it back as fast as it’s coming—almost!

Now, the last part is pure elegance itself because it has no moving parts and is the key to Hyperloop’s uncrashability!

Hyperloop Pod

Even though the pod has reduced drag significantly with the use of the electric turbine, there is still a stream of thin air moving at very high speed across the top and sides of the pod. It can’t be helped, if the pod fills the tube more, it would slow down too fast. So, instead of considering it a issue, why not use the air outside the pod but inside the tube to our advantage? By shaping the pod so that the left-over air pushes the pod down, just like a modern day race car, it will be held to the tube floor all the more tightly.

Push hard on those air bearing and they’ll push hard right back. This gives what is often called authority, a more solid ride and more control. For Hyperloop, more control is just staying solidly gliding over the tube floor. The very shape of the pod holds it down during the entire high speed journey. With no move parts, it provides a primary function and eliminating a game stopper, un-crashable control for free. Pure Elon!

So, the secret sauce of Hyperloop really was a complex recipe from a master chef! By combining those three ingredients, each well known principles, an elegant overall solution was found. The thin air is used three ways, the air bearings, the air pass-through to the rear and the air passing over the pod holding it down.

There’s one more element left to take care of that last little bit of friction and drag. Insurance if you will, to make up for any shortfalls. It was the one part of Hyperloop’s inner tech that I guessed right about and it turns out to be almost an afterthought,

Let me explain. When I was researching Hyperloop months ago, I could see that coasting all the way wasn’t going to cut it, in fact my energy use was embarrassingly high compared to what we know now. I knew there had to be something to keep the speed up or boost it periodically. My assumption was to just put a rail gun along the whole length of the tube, just a lot less dense in the middle. I could get this to work, but only, as Musk says, in "non-optimal" circumstances. I was so sure the sustainer rail gun was there that I actually left it off my original flow chart for fear of stepping on a billionaire’s toes.

Tinker's Hyperloop Flow ChartThe author's original Hyperloop prediction

I needn’t have worried. the sustainer rail gun sections are there all right, every 70 miles or so for a few seconds of boost! Elon Musk’s dynamic solution take up the lions share of the load! And there you have it in a nutshell, the secret revealed—everything else about Hyperloop is mundane in comparison!

The mundane stuff

It’s because of Elon Musk’s brilliant solution that the rest of Hyperloop’s operations fall into much more familiar territory. Beyond the tight confines and the blinding speed, Hyperloop is just a modern day rendition of a mass transit vehicle. It will operate no differently then an elevator or subway. You get in, go for a ride, get out.

Like a road or railway, Hyperloop tubes can be used by one pod or many, as much as Tube Traffic Control can handle. The pods can climb and descend hills like other mass transit vehicles. Using the air bearing, pods can be as easily switched as a train, Pod switch yards would look very familiar indeed. A lot of mass transit knowledge garnered over the decades can be directly applied to the Hyperloop transportation system.

What have we ended up with?

In the end, not only did Elon Musk devise a brilliant technology that was better than any of us dreamed for, it was such a good design that it brings Hyperloop right into the realm of familiarity.

Beyond being a unique mode of travel, Hyperloop is simply just another way to get around.

And that’s just what we want!

By John Gardi