3 ms·

I believe fixed and rigidly fixed have very different meanings in this context. Your suggesting that the tube floats on the pylon(e.g on rollers). The hyperloop

I believe fixed and rigidly fixed have very different meanings in this context. Your suggesting that the tube floats on the pylon(e.g on rollers). The hyperloop paper suggests that it's attached with dampers that are, for lack of a better term, elastic.

ash 13y ago
I disagree. I think "fixed" means the tube attached to the pillar to prevent it from jumping out of it. See rings in figure 3 (page 11): http://www.spacex.com/sites/spacex/files/hyperloop_alpha-20130812.pdf http://www.spacex.com/sites/spacex/files/hyperloop_alpha-201...
- anologwintermut 13y ago
  Given that the proposal describes dampers used to absorb change, I think this is wrong. By building a system on pylons, where the tube is not rigidly fixed at any point, you can dramatically mitigateEarthquake risk and avoid the need for expansion joints. Tucked away inside each pylon, you could place two adjustable lateral (XY) dampers and one vertical (Z) damper. These would absorb the small length changes between pylons due to thermal changes, as well as long form subtle height changes (see page 11)
  - ash 13y ago
    It says dampers absorb change. But it doesn't mean only dampers do that. Of course they couldn't handle hundred meters expansion (near ends). I don't believe Musk would make such an easy mistake and force dampers handle all of thermal expansion. That said, the quoted text is somewhat confusing. I had to read it a few times before I got the idea.
  - rossjudson 13y ago
    See section 4.2.3. The tube will be supported by pillars which constrain the tube in the vertical direction but allow longitudinal slip for thermal expansion as well as dampened lateral slip to reduce the risk posed by earthquake.
function_seven 13y ago
I took it to mean that the tube was rigidly (or near rigidly) fixed in the vertical direction, more generously dampened in the transverse direction, and completely free to slide over the pylons in the longitudinal direction.
vidarh 13y ago
Given that the proposal mention slip joints at the stations that needs to be long enough to handle the aggregate expansion, it is pretty clear that the tube "floats" at least to a certain degree.

ash 13y ago

I disagree. I think "fixed" means the tube attached to the pillar to prevent it from jumping out of it. See rings in figure 3 (page 11): http://www.spacex.com/sites/spacex/files/hyperloop_alpha-20130812.pdf http://www.spacex.com/sites/spacex/files/hyperloop_alpha-201...

anologwintermut 13y ago
Given that the proposal describes dampers used to absorb change, I think this is wrong. By building a system on pylons, where the tube is not rigidly fixed at any point, you can dramatically mitigateEarthquake risk and avoid the need for expansion joints. Tucked away inside each pylon, you could place two adjustable lateral (XY) dampers and one vertical (Z) damper. These would absorb the small length changes between pylons due to thermal changes, as well as long form subtle height changes (see page 11)
- ash 13y ago
  It says dampers absorb change. But it doesn't mean only dampers do that. Of course they couldn't handle hundred meters expansion (near ends). I don't believe Musk would make such an easy mistake and force dampers handle all of thermal expansion. That said, the quoted text is somewhat confusing. I had to read it a few times before I got the idea.
- rossjudson 13y ago
  See section 4.2.3. The tube will be supported by pillars which constrain the tube in the vertical direction but allow longitudinal slip for thermal expansion as well as dampened lateral slip to reduce the risk posed by earthquake.

function_seven 13y ago

I took it to mean that the tube was rigidly (or near rigidly) fixed in the vertical direction, more generously dampened in the transverse direction, and completely free to slide over the pylons in the longitudinal direction.

vidarh 13y ago

Given that the proposal mention slip joints at the stations that needs to be long enough to handle the aggregate expansion, it is pretty clear that the tube "floats" at least to a certain degree.