Hyperloop Gets Test Track in California • Hacker News Board

Re: Hyperloop Gets Test Track in California

#11

Post by stcredzero » Tue, May 26, 2015, 5:55 PM UTC

Retric wrote: post #3

rmxt wrote: post #2

A 5-mile test track won't be big enough to examine the biggest concerns: thermal and seismic. The alpha brochure linked to in the OP barely touches on the two. Here [1] is a better analysis/take-down of what thermal issues such a long structure will encounter. (TL;DR: A 400-mile long continuous structure will need to accommodate 1000 feet of thermal movement over it's length and lifetime.) Seismic is another beast: i…

Thermal expansion is not really an issue that gets worse with distance, as the track can simply be made from independent segments connected with expansion joints. The issue is being able to cross from segment A to segment B not the number of such segments. In other words if it works on a test track it scales just fine, but getting that first connector to work is the hard part. Earthquakes require active dampening whi…

But don't we have a window of minutes to shut down the system in case of an earthquake? I thought we could get advance warning from P waves. (This doesn't work if you're in the epicenter, unfortunately.)

If the car gets badly damaged, but the passenger stays alive, and the system can be fixed in a reasonable amount of time, then this is fine performance for a major earthquake event. High speed trains have similar performance in the same situation.

Re: Hyperloop Gets Test Track in California

#12

Post by gargarplex » Tue, May 26, 2015, 5:55 PM UTC

ChuckMcM wrote: post #9

Sigh "The 5-mile test track is estimated to cost about $100 million, which Hyperloop Transportation Technologies hopes to pay for with its initial public offering (IPO) later this year, according to Navigant's blog." Run away, run far far away. They might as well do a kickstarter. Seriously, what sort of "business" is a 5 mile test track? Lets say you charged $25 for a "5 minute ride on the hyperloop!" and you got 8…

$/mi will reduce with scale.

Re: Hyperloop Gets Test Track in California

#13

Post by rmxt » Tue, May 26, 2015, 5:59 PM UTC

Retric wrote: post #3

rmxt wrote: post #2

A 5-mile test track won't be big enough to examine the biggest concerns: thermal and seismic. The alpha brochure linked to in the OP barely touches on the two. Here [1] is a better analysis/take-down of what thermal issues such a long structure will encounter. (TL;DR: A 400-mile long continuous structure will need to accommodate 1000 feet of thermal movement over it's length and lifetime.) Seismic is another beast: i…

Thermal expansion is not really an issue that gets worse with distance, as the track can simply be made from independent segments connected with expansion joints. The issue is being able to cross from segment A to segment B not the number of such segments. In other words if it works on a test track it scales just fine, but getting that first connector to work is the hard part. Earthquakes require active dampening whi…

Thermal is an issue that gets worse with distance. Did you look at the article that I posted above? If you are proposing expansion/slip joints at every pier, that runs directly counter to the proposal which states that expansion joints will only be needed near the stations. [1, pg. 27] If we go according to the proposal, the slip joint at the stations on the test track will only need to accommodate ~9 feet of movement (5280x5x6.5x10^-6x100)/2 compared to something an order of magnitude higher for a full-scale track.

Successfully designing for earthquakes does not necessarily mean active damping. (That is, it is not "required" as you state.) Yes, many large structures use specially designed mass or viscous dampers for dynamic loading (Citigroup Building, NYC; Taipei 101; Millennium Bridge, London), but others are designed to fail safely such that life and structure are preserved to the greatest extent possible. Specifically for bridge structures, there is the notion of plastic hinging in visible locations. [2] This way, the failures can be identified and repaired before normal use resumes. Here are some relevant state DOT guidelines. [3]

[1] http://www.spacex.com/sites/spacex/files/hyperloop_alpha-201...

[2] https://en.wikipedia.org/wiki/Plastic_hinge

[3] http://www.dot.ca.gov/hq/esc/techpubs/manual/bridgemanuals/b...

Re: Hyperloop Gets Test Track in California

#14

Post by pavlov » Tue, May 26, 2015, 5:59 PM UTC

ChuckMcM wrote: post #9

Sigh "The 5-mile test track is estimated to cost about $100 million, which Hyperloop Transportation Technologies hopes to pay for with its initial public offering (IPO) later this year, according to Navigant's blog." Run away, run far far away. They might as well do a kickstarter. Seriously, what sort of "business" is a 5 mile test track? Lets say you charged $25 for a "5 minute ride on the hyperloop!" and you got 8…

As an IPO this sounds similar to most biotech/pharma startups. These companies routinely IPO in the $50-100 million range when all they have is a patent, some promising data but no approved clinical trials and no business.

Of course it's different because there's a clear post-IPO acquisition market for biotechs. Not quite as clear who would buy Hyperloop if it's proven to work...

Re: Hyperloop Gets Test Track in California

#15

Post by pbreit » Tue, May 26, 2015, 6:02 PM UTC

ChuckMcM wrote: post #9

Sigh "The 5-mile test track is estimated to cost about $100 million, which Hyperloop Transportation Technologies hopes to pay for with its initial public offering (IPO) later this year, according to Navigant's blog." Run away, run far far away. They might as well do a kickstarter. Seriously, what sort of "business" is a 5 mile test track? Lets say you charged $25 for a "5 minute ride on the hyperloop!" and you got 8…

You should not. But a lot of (more positively thinking) people might like the risk/reward. After all, Elon is 4 for 4 in making people fabulously wealthy off very-hard-to-do projects (I know he's not officially involved but some of his people are like Sacks and Pishevar are).

Re: Hyperloop Gets Test Track in California

#16

Post by WalterSear » Tue, May 26, 2015, 6:04 PM UTC

geon wrote: post #8

> The problem with traveling in an evacuated tube is, if you lose the vacuum in the tube, everybody in the tube will crash Wouldn't that be a "crash" into a gradually rising air preassure? Something like a smooth deacceleration.

Turbulence is probably going to be an issue.

Re: Hyperloop Gets Test Track in California

#17

Post by pbreit » Tue, May 26, 2015, 6:04 PM UTC

hyperbovine wrote: post #6

"If the position of the wall deviates from straightness by a few thousandths of an inch, you could crash ... if you lose the vacuum in the tube, everybody in the tube will crash ... the vehicle's compressor ... can't fail, or the pods will crash ... The 5-mile test track is estimated to cost about $100 million, which Hyperloop Transportation Technologies hopes to pay for with its initial public offering (IPO) later t…

Are you referring to the over-the-top negativity of an uninvolved spectator?

Re: Hyperloop Gets Test Track in California

#18

Post by huuu » Tue, May 26, 2015, 6:06 PM UTC

  * Invent something totaly new
  * Test it on a small scale
  * Get a lot of negative comments on HN

Com'on people. This might be the transportation of the future!

Re: Hyperloop Gets Test Track in California

#19

Post by stephengillie » Tue, May 26, 2015, 6:06 PM UTC

ChuckMcM wrote: post #9

Sigh "The 5-mile test track is estimated to cost about $100 million, which Hyperloop Transportation Technologies hopes to pay for with its initial public offering (IPO) later this year, according to Navigant's blog." Run away, run far far away. They might as well do a kickstarter. Seriously, what sort of "business" is a 5 mile test track? Lets say you charged $25 for a "5 minute ride on the hyperloop!" and you got 8…

This reminds me of the Seattle Monorail, which continues to operate today. For a few dollars, you can ride swiftly and smoothly from one part of Downtown Seattle to another part of Downtown Seattle.

Some day, scientists hope, the value of the monorail will be seen. That day, we expect to extend the rail line to other communities. Meanwhile, we just pulled a tunneling machine out of its boring hole, continue to expand the Link Light Rail system, and are developing various trolley-based solutions such as the ones in South Lake Union and First Hill.

Re: Hyperloop Gets Test Track in California

#20

Post by digikata » Tue, May 26, 2015, 6:07 PM UTC

ChuckMcM wrote: post #9

Sigh "The 5-mile test track is estimated to cost about $100 million, which Hyperloop Transportation Technologies hopes to pay for with its initial public offering (IPO) later this year, according to Navigant's blog." Run away, run far far away. They might as well do a kickstarter. Seriously, what sort of "business" is a 5 mile test track? Lets say you charged $25 for a "5 minute ride on the hyperloop!" and you got 8…

The purpose would be to learn more about the inevitable practical problems that come up between a system concept that pencils out to be more efficient and a real operating system. I think we stand on the shoulders of giants giving an incredible science and tech foundation to work upon. However, all that knowledge can give us a false sense of how difficult it is to cross into unknown territory (e.g. when assembling a new system from well understood elements, like hyperloop).