What Testing Has Taught Us | Hyperloop One
XP-1 in the DevLoop Tube

What Testing Has Taught Us

By the end of this summer, Hyperloop One will have spent more time testing a full-scale Hyperloop system than any other group in the world. In July, we shared the results of our first, full systems test flight  Hyperloop One's Kitty Hawk Moment. This was the first time in the world a full system Hyperloop was tested as a single integrated unit in the vacuum environment of our DevLoop tube. Last week, we shared the results of our second phase of trials, which deployed the complete XP-1 vehicle in the tube. XP-1 is comprised of a carbon fiber aeroshell atop our levitating chassis, which includes the components for propulsion, levitation and guidance. During phase two testing we also reached the fastest recorded speed of any Hyperloop test pod, reaching a top speed of 310 kilometers per hour, or 192 mph.

Since our ‘first flight’ was announced we’ve had a lot of interest globally in what we are building. We’ve culled our intelligence to address some of the top questions we’re getting about how Hyperloop works and share what we are learning during our tests.

How does the motor and propulsion system work?

Hyperloop One vehicles are propelled using a linear electric motor, which is a straightened-out version of a conventional rotary motor. A conventional electric motor has two primary parts: a stator (the part that stays still) and a rotor (the part that moves or rotates). When voltage is applied to the stator it makes the rotor spin and do the work of, say, spinning a power drill. A linear electric motor has the same two main parts, however, the rotor doesn’t rotate but instead moves in a straight line along the length of the stator. In the Hyperloop One system, the stators are mounted to the tube, the rotor is mounted to the pod, and the pod straddles the stators as it accelerates down the tube.

Our explainer video does a great job of bringing this to life.

Do Hyperloop systems need a complete vacuum to operate?

Hyperloop One systems are designed to work in a low-pressure vacuum, not a perfect vacuum. You don’t need a perfect vacuum to get substantial benefits from reduced aerodynamic friction. We’re aiming to function at or below 100 Pascals. A Pascal (Pa) is a measure of atmospheric pressure. The air at sea level is 101,325 Pa, so 100 Pa is roughly equivalent to the pressure exerted by a quarter laying flat on a table. During our recent testing we pulled a much lower vacuum than 100 Pa.

What would happen if there was a vacuum breach in the tube?  

Our tubes are constructed out of thick, strong steel and are very difficult to puncture. However, it is reasonable to expect leaks and even the occasional breach in routes that stretch 100 miles or more. We’re designing and constructing the tube and pods explicitly to handle extremely low pressures and  sudden changes in air pressure. They’ll be able to tolerate small leaks, holes, and even breaches without suffering from a vacuum collapse.

If there was a leak or breach in an operational Hyperloop system, the incoming air pressure would slow vehicles down, and we might need a power boost to get them to the next station. We will also have the ability to section off parts of the route and re-pressurize sections in the case of a significant emergency. Every pod will have emergency exits if needed, but mostly pods will glide safely to the next portal (station) or egress point in the event of an emergency. Additionally, we are building sensors throughout the pods, tubes, and system to notify of any leaks or breaches and we would be able to identify and perform maintenance to resolve any leaks quickly. 

How many people will be able to travel in the pod that you shared photos of?

We recently shared images and video of our prototype levitating chassis and aeroshell that sits on top of the chassis. This upper section of the vehicle was built for aerodynamic testing and does not hold people or cargo, although it is large enough and strong enough for people to stand inside. The capacity of our production system pods will depend on the specific needs of future customers. 

Why is your pod aerodynamically designed? That type of design won’t be needed in a vacuum, right?

We still have some air to deal with in the tube. The aerodynamic design will help us to understand airflow principles inside the tube, and reduce energy consumption in the low-pressure vacuum environment.

What controls the test vehicle inside of the tube?

The test vehicle departure is scheduled by our control software systems and we have sensors throughout the system, on the pod, and in the tube that provides real-time positioning and location information at all times. A set of conductive guidance rails provide electromagnetic stability during flight.

How are you going to make the technical leap from a shorter test track and slower speeds to a longer track capable of speeds upwards of 600 miles per hour? 

Our current Hyperloop tests are slower than the maximum speed of a Hyperloop as the test tubes are not long (only 500 meters). Speed is a function of track length. With another 2,000 meters added, we could easily reach speeds of up to 700 mph. We are actively engaged with customers who want to build the first proof of operation facilities at lengths of 10 to 20 miles and hope to have three operational systems by 2021. We will also work in parallel to certify the control systems required to operate safely at these high speeds.

How fast will Hyperloop accelerate and decelerate? Could I get sick?

Hyperloop One pods will be designed to accelerate and decelerate gradually, no different than you’d feel on a commercial airline. During our recent phase two testing, the pod accelerated much faster, about the equivalent of going 0 to 60 mph in 1.85 seconds. However, this was a short test track and thus we needed to accelerate more quickly for testing purposes. Passenger systems would be designed with passenger comfort in mind and will achieve the kinds of speeds we’re aiming for with lower acceleration rates over longer propulsion segments.   

What lessons did you learn from your testing this summer and how will those insights be applied to future tests of the system? 

With every test we learn how we can become faster, more efficient, and how to make changes to improve upon systems that we will eventually build for customers in proof of operations sites. These tests helped us better integrate subsystems, improve our control systems, power electronics, and braking. Designing a system teaches you a lot, building one even more and testing it teaches you volumes – the quicker you can do this the more you learn and the faster you can take Hyperloop to the world.

 - The Hyperloop One team