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The Hyperloop: BUSTED

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edavid:

--- Quote from: lem_ix on July 31, 2016, 06:56:56 pm ---People don't seem to understand the most important side of engineering, COST. Sure it sounds cool and I'd like to ride one but that doesn't mean it's a good idea.

--- End quote ---

I guess you didn't read the Hyperloop proposal.  The whole point of it was to present a design with higher performance than CHSR, at lower cost.

You can certainly argue whether the cost estimates were reasonable, but you seem to have completely missed that Musk's proposal was all about cost.

Mark_Of_Sanity:
Here is an interesting response to the thermal expansion problem TF mentions.
Titled: Re: The Hyperloop Busted (Thunderf00t) - Thermal Expansion Mechanism

TheAmmoniacal:

--- Quote from: Mark_Of_Sanity on August 03, 2016, 06:03:16 pm ---Here is an interesting response to the thermal expansion problem TF mentions.
Titled: Re: The Hyperloop Busted (Thunderf00t) - Thermal Expansion Mechanism


--- End quote ---

Yep, that is the only viable solution to the thermal expansion problem in the Hyperloop. It's still extremely challenging though.

helius:
Thermal expansion would not be a problem in a buried tube, and it would solve the vandalism problem as well.

Maxlor:
I'm dubious that's a viable solution. Let's do some back of the envelope calculation:

Let's say there's a 100K temperature differential we need to consider, and our pin points are 1000m apart. The elongation of steel is 12ppm, so our previously 1000m of tube are now 1001.2m long. The sideways motion to accomodate those additional 1.2m is about 21.2m at the middle at the 500m point, which is not unreasonable, it's in about the same range as a multilane highway's width. However, the hypertube cars are now also travelling through an arc with a radius of about 5.9km, which at a speed of 300m/s results in a sideways acceleration of 15.2m/s^2, and what's more, the acceleration will switch from left to right every 3 seconds. That'd be a very uncomfortable journey.

What if the pinpoints were 10km apart instead of 1km? That'd increase the radius 10-fold, which would mean 1/10th of the acceleration, i.e. about 1.52m/s^2. That's about the acceleration you experience in a subway, and I think it'd still be uncomfortable to experience that constantly, with direction switching every 30 seconds. Then again, people put up with riding the subway with its constant starting and stopping, so maybe it'd be ok. However, the sideways motion of the tube would increase by a factor of 10 too, to a whopping 212m. That's quite a bit of land use there. So it'd be both slightly uncomfortable and use an unreasonable amount of land.

So I don't think just allowing thermal expansion is the answer.

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