Hyperloop, Bottom Line Up Front:

The presentation below is our documented work on a sub-scale model of the Hyperloop proposed by Mr. Elon Musk. We are a mechanical engineering senior design team from the University of Illinois Urbana-Champaign. Feedback is welcome on this document or relevant aspects to the project. Email feedback to bell15@illinois.edu. Sharing and adaptation of our work is welcome and encouraged.

Link to PDF: UIUC Hyperloop Status Report

The Background

Eleven of sixteen weeks down, the last semester of my BS mechanical engineering at UIUC is proving to be quite entertaining. Most of the entertainment has been derived from two things, triathlon and projects. After competing in the National Collegiate Triathlon Championships in Tempe, AZ last week, I have turned most of my attention to the projects.

Having the time to work on these projects has been a definite benefit of (1) taking 4.5 semesters to finish my degree and (2) taking off last semester to off to intern at Tesla. The first project of note is directly related to Tesla, more accurately Mr. Elon Musk. [Note: I say Mr. Musk because a critic of a senior design presentation reprimanded me for referring to Mr. Musk by his first name. The professor asked if I had ever met Mr. Musk, and the best I could honestly reply was that I walked past him a few times in the office. The audience chuckled.] Last year, Mr. Musk released a proposal for the Hyperloop, a new form of transportation in response to the proposed California high speed rail project, which was as he called it, one of the most expensive and slowest in the world.  The 58 page white paper presented a compelling proposal for the system, arguing its feasibility through first principles in typical Mr. Musk form. Not surprisingly with Mr. Musk’s Tesla, SpaceX, and Solar City commitments, he seemingly declined to save the world in a 4th industry, at least for the time being. Instead, the paper concluded with the following statement:

Hyperloop is considered an open source transportation concept. The authors encourage all members of the community to contribute to the Hyperloop design process. Iteration of the design by various individuals and groups can help bring Hyperloop from an idea to a reality. 

The authors recognize the need for additional work, including but not limited to: 
1. More expansion on the control mechanism for Hyperloop capsules, including attitude thruster or control moment gyros. 
2. Detailed station designs with loading and unloading of both passenger and passenger plus vehicle versions of the Hyperloop capsules. 
3. Trades comparing the costs and benefits of Hyperloop with more conventional magnetic levitation systems. 
4. Sub-scale testing based on a further optimized design to demonstrate the physics of Hyperloop. 

Hyperloop at Illinois

Back to Champaign, the proposal caught Professor Placid Ferreira‘s attention, so he dispatched three undergrads to pursue design of a sub-scale model of the Hyperloop system last fall. Upon my return to campus from California, I joined the team to continue pursuing the sub-scale model as a senior design project this semester. The core team includes students Elliot Giraud, Louis Zhao, Logan Wan, Tut Tangtragulcharoen, me, and advisor Professor Carlos Pantano-Rubino.

The goal of the project is to create a physical sub-scale model with three major components – (1) an evacuated test track, (2) a linear induction motor, and (3) a passenger capsule – with the objectives to explore the feasibility of the Hyperloop concept and optimize prototype performance. Due to project constraints – time, money, technical difficulty, etc. – several adaptations were made to these sub-systems from the original design in the white paper. These are documented in the presentation attached above. A few major adaptions of note:

1. Test track: the evacuated test tube will be an oval with approximate 13m of track, constructed of rigid steel conduit 90 degree elbows with 60 inch radii and clear PVC straights, both nominally 3 inches in diameter. The oval design means the capsule will experience proportionally much tighter turning radii than the proposed Hyperloop. This resulting forces limits the scale model’s speed and (sadly) prevents us from testing near sonic behavior. Attempting to do so would likely destroy capsule components, the track, and/or the surrounding building. Still, the tube and support systems are designed to handle a 2kg capsule traveling at a jaunty 30m/s.
2. Motor: a tubular linear induction motor will be constructed around the PVC piping, a decision driven by the difficulty of constructing the fin and slot motor of the original proposed design. The tight turning radii would have made aligning the capsule rotor fin with respect to tube-based stator slot very difficult difficult.
3. Capsule: due to the selection of the tubular linear induction motor, the capsule itself will be the rotor, constructed from an iron rod with copper jacket. Regretfully capsule will also forego the air skis because of the complexity of the system, difficulty packaging the components into the small size of the capsule, and short project timeline. Instead, the capsule will roll on low friction ball transfer bearings. For initial motor testing, we will not have a compressor on the front of the vehicle, but we plan to implement it if possible. The exhaust air will be routed to the rear of the vehicle in lieu of the air skis.

Although these modifications deviate from the original design more than I would prefer, designing and constructing even the simplified systems in the 16 week academic term is daunting. Right now, we have completed most of the design work, have received the last of our raw materials, and are entering the construction phase. As the lead for the tube construction, I am waiting for four of the 3 inch rigid conduit special radius 60 inch sweeps – not the easiest things to acquire – to be shipped from Ohio. Once these arrive, I’ll be consumed by cranking out a seamless track – as seamless as possible so the transfer bearings carry the capsule smoothly around the track – that also seals enough to be evacuated down to 100 Pa or 0.75 torr.

For a project in my mechatronics class project, I’m attempting to use a Freescale pressure sensor chip in conjunction with the TI Launchpad MSP430 we’ve been programming this semester to monitor the pressure and implement a control system to turn on and off the vacuum pump when the pressure inside the tube gets too high above our target vacuum. The simple solution for ON/OFF is a servo taped to the switch on a power strip linked to a small 110V vacuum pump; the complex one is a relay controlled by the 3.3V outputs of the MSP430 to switch on and off the three-phase 250V AC required for an industrial vacuum pump. To be continued.

And if all this wasn’t enough, I’m helping construct thermally- and human-representative heads for a research project in Professor John Rogers’ legendary research group. We’re going for the Mythbuster-esque ballistics gel with a heated brain core embedded. More on this when I can disclose the project.

Other than that, it’s just an ordinary semester at Illinois.