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The Hyperloop: BUSTED

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brucehoult:
Yeah?

Hyperloop is hard.

Is it harder than making a luxury all-electric sedan with supercar-beating performance and 500 km range, and selling it at a profit for the price of an Audi or BMW? When everyone else was convinced you can only make golf carts.

Is it harder than taking a 30m high rocket 1st stage that is 75 km above the earth and travelling at 6000 km/h and propulsively landing it on a barge in the ocean? You've only got to go back about three years to find pretty much everyone saying it's somewhere between impossible and impractical. This year it has become so routine people are not bothering to get out of bed to watch the livecasts.

Hyperloop doesn't break any fundamental laws of physics. There are lots of challenges many of which could be showstoppers if they can't be solved. But that's just a matter of engineering. I'm sure it could be done. The question is more the economics.

I'm not a fan of high speed ground transportation. I can't see much point spending tens of billions on a single 300 or 400 km/h train route when a lowly Dash8 takes 40 - 60 passengers at over 500 km/h with infinitely flexible routes between any arbitrary pair of towns less than 1500 - 2000 km apart that each possess a 1000 - 1200 meter long airstrip (or less, with reduced range and/or passengers).

If you've got 1600m of runway available then you can step up to a CRJ (or A318 probably) with more seats, longer range, 800+ km/h speed, and lower operating costs. But even the Dash8 beats any non-hyperloop high speed ground transport.

But, again, I don't see any fundamental reason that Hyperloop is "BUSTED" in the sense of being impossible or breaking any fundamental laws.

Fungus:

--- Quote from: EEVblog on August 03, 2017, 01:33:24 am ---They didn't even mention the most important and hardest part, and the one that will ultimately doom this concept. The vacuum  :palm:



--- End quote ---

Jeez, how much money are those guys spending on this?

Or team has about 6m of tube and no vacuum pump. We can levitate our tiny pod, but that's it. The first time we'll know if the propulsion works is when it arrives at the proving round in September.

amspire:
Not sure it has been posted, but here is the Tesla proposal:

https://www.tesla.com/sites/default/files/blog_attachments/hyperloop_alpha3.pdf

It does include a fair bit of detail. It doesn't run in a full vacuum like space - it runs at an air pressure in the tubes of 100 pascals  - about 1/1000th of the atmosphere. In terms of safety concerns, it does seem to rely on the assumption that derailments, tube damage and collisions are extremely unlikely. If a carriage somehow becomes stranded, then supposedly all carriages behind it (the spacing can be under 800 meters) will stop and then drive back to the starting point on small battery powered electric wheels even of it is at atmospheric air pressure.

I do not think the possibility that every carriage in the tube could be stranded is considered. Say one carriage gets stranded and then one near the start of the tube fails while reversing on its wheels back to safety. The hundreds of carriages containing 28 people each in between would all be completely stranded.

brucehoult:

--- Quote from: amspire on August 03, 2017, 03:05:11 pm ---Not sure it has been posted, but here is the Tesla proposal:

https://www.tesla.com/sites/default/files/blog_attachments/hyperloop_alpha3.pdf

It does include a fair bit of detail. It doesn't run in a full vacuum like space - it runs at an air pressure in the tubes of 100 pascals  - about 1/1000th of the atmosphere.

--- End quote ---

That makes things a little bit easier for the vacuuum pumps and permits minor leaks (mind you there is no such thing as a perfect vacuum). Structurally, it's identical to a full vacuum, for both the tube and the vehicles (and people in them).

I can't immediately find a table going that far, but I know a rule of thumb that says atmospheric pressure halves every 16000 ft is pretty close to at least 64000 ft, so ten halvings or 1/1024 of normal pressure is about 160000 ft altitude (50 km) equivalent.

mtdoc:

--- Quote from: brucehoult on August 03, 2017, 01:13:25 pm ---Yeah?

Hyperloop is hard.

Is it harder than making a luxury all-electric sedan with supercar-beating performance and 500 km range, and selling it at a profit for the price of an Audi or BMW? When everyone else was convinced you can only make golf carts.

Is it harder than taking a 30m high rocket 1st stage that is 75 km above the earth and travelling at 6000 km/h and propulsively landing it on a barge in the ocean? You've only got to go back about three years to find pretty much everyone saying it's somewhere between impossible and impractical. This year it has become so routine people are not bothering to get out of bed to watch the livecasts.

Hyperloop doesn't break any fundamental laws of physics. There are lots of challenges many of which could be showstoppers if they can't be solved. But that's just a matter of engineering. I'm sure it could be done. The question is more the economics.
--- End quote ---

Yep. Exactly my sentiments. Both economics and the associated politics are what will make the ambitious long distance projects extremely difficult if not impossible - at least in the U.S.


--- Quote ---But, again, I don't see any fundamental reason that Hyperloop is "BUSTED" in the sense of being impossible or breaking any fundamental laws.

--- End quote ---

Yes, but just don't try taking that stand with the Thunderf00t fanboys!

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