A recently acquired piece of Nevada desert could very well be the next Kitty Hawk.

The Hyperloop is anticipated to be the first new mode of transportation in over a century, adding to the classic quartet of planes, trains and automobiles (and boats). The idea is simple—propel pressurized pods through a depressurized tube at tremendous speeds—but the engineering challenges are staggering.

ENGINEERING.com has been following the Hyperloop’s progress since its inception, as well as the associated tools and competitions. In a recent webinar, Josh Giegel, VP of design and analysis engineering at Hyperloop Technologies shared the company’s vision from a design and engineering perspective.

The Hyperloop: 4 Core Elements

To make the Hyperloop a reality, Geigel and his colleagues are developing four key technologies:

• The Big Tube: a 12’ diameter tube which can support an ultra-low pressure (ULP) environment
• The Compressor: an axial compressor capable of functioning in an ULP environment
• Levitation: a method for lifting the pods that will work in an ULP environment
• Electric Propulsion: a linear motor to accelerate the pods within the tube

The Big Tube

“One of the interesting things about this is that it’s very different from conventional pipelines,” said Giegel. “Most of the time inside a pipeline you have a high-pressure liquid that you’re pushing through it, so you want to keep as much stuff from coming out as possible. We’re trying to keep stuff from getting in, and that’s a very different problem.”

Their aim is to reduce the pressure inside the tube to one thousandth of an atmosphere (equivalent to approximately 160,000-foot elevation). This would substantially reduce drag; a pod moving through the tube at 700 mph would experience drag equivalent to a transport trailer travelling on a highway at 60 mph.

Since the high pressure in pipelines is partly responsible for stabilizing their structure, the tube requires novel solutions to improve its strength and resistance to buckling. Hyperloop Technologies is currently conducting welding and vacuum tests using a 70-foot-long off-the-shelf tube with an 11-foot diameter.

“In the civil world, there hasn’t been anything like this before, so we’re coming up with different vibration isolators and dampers and thermal expansion joints because we have a very different problem than everyone else,” said Giegel.

The Compressor

In Giegel’s words: “We’re designing essentially an axial compressor that would work at 160,000’ of elevation; no one’s ever done that before and it’s a very different problem. You’re getting to the edge of rarefied flow and doing interesting things to the shapes of the blades, because you have a very low Reynolds number and a very high Mach number.”

Although Hyperloop Technologies has been working extensively on these challenges with modelling and simulation, everything will need to be adjusted in light of actual test data. Enter the Blade Runner: a unique wind tunnel that was designed, analyzed and built in ten weeks. It’s capable of running continuously and testing at supersonic speeds.

Giegel and his colleagues are still investigating what to do with the air once it has been compressed, which requires yet another engineering skillset. “From thermodynamics and heat transfer, to fluid dynamics, to aerodynamics, there are some really awesome problems here,” said Giegel.

Levitation

“We’ve got an air bearing system and we’ve characterized that; we know the shortcomings and the requirements, not just from a performance standpoint but as a system,” said Giegel. “We’re also looking into mag lev which people tend to think of as really expensive. But trust me: this isn’t your grandad’s mag lev system.”

Specific systems aside, the levitation testing itself is noteworthy for its speed. “No one’s tested levitation at these speeds before,” said Giegel. The testing device uses a read head and a wheel spinning at a tip speed of 700 mph, which is no mean feat.

Electric Propulsion

Currently, electric motors are the most attractive propulsion option for the Hyperloop. There are two basic kinds of linear electric motors: induction and synchronous. The former are more common in the industry, but Giegel hinted that the company may be opting for the latter.

“There have been machines that have this amount of power (roughly 30 MW) but they go very slow,” said Giegel. “Then there are machines that have a lot of speed, but not a lot of power. We need a combination of both, so that’s where we’re really pushing the state of the art for power electronics equipment as well as motor design.”

The vacuum tube, wind tunnel and levitation testing rigs were all built to validate Hyperloop Technologies’ models, but the company is doing a much larger test to validate the design of the propulsion system.

The Propulsion Open Air Test (POAT) in Nevada will see a test vehicle on an open air track being accelerated from zero to 350 mph in two seconds. This is primarily to test the force density of the machine. Once the POAT has verified the electric motor’s design, the next step will be running the same test inside a tube.

The Hyperloop Needs You!

At this point, it should be clear that designing the Hyperloop involves almost every kind of engineering. Giegel commented on this:

“We really have a need for all types of engineers on a diversity of problems. We’ve got civil, structural, aero, fluids, electro-magnetics, high-power electronics, high-power propulsion and controls; the only thing we don’t capture right now is bioengineering, but as soon as we start doing acceleration testing with crash dummies we’re going to be getting into that very quickly.”

If this sounds like the sort of place you’d like to work, keep an eye on our jobs board or visit Hyperloop Technologies’ website.

For more information, check out our Hyperloop webinar.