3 ms·

Each pod weighs 7,700 lb and is traveling at 760 mph. Are you sure a few-centimeter speedbump isn't a big deal? I don't know how to calculate whether or not i

Each pod weighs 7,700 lb and is traveling at 760 mph. Are you sure a few-centimeter speedbump isn't a big deal? I don't know how to calculate whether or not it would be, but I'm interested in knowing why you feel it won't cause problems. Remember, the pod comes into direct contact with the wall while banking, so it's going to take the full force of any few-centimeter bump.

jacquesm 12y ago
> Are you sure a few-centimeter speedbump isn't a big deal? Depends on lots of things, such as the angle of incidence of the pod relative to the direction of the wall of the tube. > I don't know how to calculate whether or not it would be, but I'm interested in knowing why you feel it won't cause problems. I don't know how to calculate rockets landing on barges either, but SpaceX seems to be able to pull it off. There is nothing in the realm of engineering that says you can't make a bunch of tubes sliding over each other relative to the direction of travel for some vehicle to travel within that tube as long as you respect a couple of basics. One simply solution would be something like this: seg2----- --seg1 ----- ---------- 0000000 Where the '0' are the elements of the pod in contact with the wall (I would assume they're using rollers there, anything solid would wear out the wall in no time at all). That way there is no speedbump at all... It's not as if you're going to do right angle turns at the joint of two segments. Anyway, I really think you're chasing a ghost here, the problems with hyperloop are not basic engineering.
- sillysaurus3 12y ago
  That solution is interesting, but does it account for the fact that the tube curves all throughout its route? Some parts need to be curvy, some need to be straight. Are you sure that expansion can be coaxed into a curve shape rather than linear? How? Also, curves still result in a speedbump with that solution. The pod will be traveling directly toward the gap just below "seg2" if it's banking against the wall. You could make the edge a sharp edge, like a sword's edge, but that doesn't help because due to expansion that edge will still protrude out into the path of the pod. I know it seems like it shouldn't be a hard problem, but it's looking like one. Remember, 300 meters of expansion over 350 miles is 0.85m of expansion per mile. Hold out your arms to the length of a meter and picture how much steel that is. That's what your proposed joints need to deal with: 0.05cm of expansion per meter. So if you have your joints every 20 meters, that's still a 1cm gap, which means a speedbump around curves. Wouldn't that make curves very unpleasant for the passenger and the pod? And you can't have them every meter without increasing the engineering complexity and weakening the structural integrity, right? Yet whatever solution they come up with would need to be placed less than every 20 meters, otherwise they'll get a 1cm gap.
  - jacquesm 12y ago
    I have a feeling that no matter how many times I'm going to answer your 'but this is impossible' with showing you how in fact it is possible you're not going to concede that in fact it probably is possible nor are you going to stop so in the interest of conserving bandwidth I'll bow out of the conversation here with this final bit. The solution for the above is that you need to take into account the radius of curvature and you're clearly not doing that. The inside of that tube needs to be relatively smooth in the direction of travel, not perpendicular to it. You could also interleave to two segments if you wanted it to be even smoother. So no, this is not a hard problem in spite of your continued insistence that it is because you can't solve it. http://jacquesmattheij.com/you+can+not+do+that http://jacquesmattheij.com/you+can+not+do+that
    - sillysaurus3 12y ago
      If you don't have time, fine. If you don't want to talk, fine. But I have some strong words which, out of respect for HN's guidelines, I won't say. Being dismissive of a newbie's concerns while killing their interest in the field isn't great, especially after they've put hard work into giving you a clear-cut example of the technical reasons why something looks hard to them. And I still don't understand how your solution wouldn't leak air into the hyperloop unless the steel sleeves were pressing very firmly into each other. Like the inner sleeve forcefully pressing into the outer sleeve. I have no idea why you refuse to admit this is at the very least a nuanced problem.
      - jacquesm 12y ago
        > If you don't have time, fine. If you don't want to talk, fine. I'm not on your payroll and you're stuck in a groove. > But I have some strong words which, out of respect for HN's guidelines, I won't say. Feel free, I'm not made of sugar. But you're arguing from a position that makes no sense to me, you're apparently entirely ignorant of the basics of mechanical engineering and you're going to tell the likes of Elon Musk and his band of merry engineers what they can or can not do. They just came within a hair of planting a friggin' rocket on a barge from space. Do you really believe they couldn't get a bunch of tubes to slide inside each other without overshooting their air intake budget? That's mostly a factor of 'how big are the pumps' and 'how many such sliding spots do we need' (a few hundred would do just fine) and how much room there is for additional seals (plenty). > And I still don't understand how your solution wouldn't leak air into the hyperloop unless the steel sleeves were pressing very firmly into each other. Like the inner sleeve forcefully pressing into the outer sleeve. No, you don't need that you can use regular seals for that, just like we do on high pressure air connections, fun fact, they work better when the difference is higher, go figure. > I have no idea why you refuse to admit this is at the very least a nuanced problem. Because it is a nuanced problem for you, but not for anybody that has the wherewithal to be hired on the engineering parts of a project like this. Just like my little brother would find assembly language a 'nuanced problem' and I find it relatively easy. It all depends on whether or not you're doing this (mechanical engineering) on a daily basis or whether you want to be back-seat driving nay sayer. Once you've decided on the latter any solution will be inadequate.

jacquesm 12y ago

> Are you sure a few-centimeter speedbump isn't a big deal? Depends on lots of things, such as the angle of incidence of the pod relative to the direction of the wall of the tube. > I don't know how to calculate whether or not it would be, but I'm interested in knowing why you feel it won't cause problems. I don't know how to calculate rockets landing on barges either, but SpaceX seems to be able to pull it off. There is nothing in the realm of engineering that says you can't make a bunch of tubes sliding over each other relative to the direction of travel for some vehicle to travel within that tube as long as you respect a couple of basics. One simply solution would be something like this: seg2----- --seg1 ----- ---------- 0000000 Where the '0' are the elements of the pod in contact with the wall (I would assume they're using rollers there, anything solid would wear out the wall in no time at all). That way there is no speedbump at all... It's not as if you're going to do right angle turns at the joint of two segments. Anyway, I really think you're chasing a ghost here, the problems with hyperloop are not basic engineering.

sillysaurus3 12y ago
That solution is interesting, but does it account for the fact that the tube curves all throughout its route? Some parts need to be curvy, some need to be straight. Are you sure that expansion can be coaxed into a curve shape rather than linear? How? Also, curves still result in a speedbump with that solution. The pod will be traveling directly toward the gap just below "seg2" if it's banking against the wall. You could make the edge a sharp edge, like a sword's edge, but that doesn't help because due to expansion that edge will still protrude out into the path of the pod. I know it seems like it shouldn't be a hard problem, but it's looking like one. Remember, 300 meters of expansion over 350 miles is 0.85m of expansion per mile. Hold out your arms to the length of a meter and picture how much steel that is. That's what your proposed joints need to deal with: 0.05cm of expansion per meter. So if you have your joints every 20 meters, that's still a 1cm gap, which means a speedbump around curves. Wouldn't that make curves very unpleasant for the passenger and the pod? And you can't have them every meter without increasing the engineering complexity and weakening the structural integrity, right? Yet whatever solution they come up with would need to be placed less than every 20 meters, otherwise they'll get a 1cm gap.
- jacquesm 12y ago
  I have a feeling that no matter how many times I'm going to answer your 'but this is impossible' with showing you how in fact it is possible you're not going to concede that in fact it probably is possible nor are you going to stop so in the interest of conserving bandwidth I'll bow out of the conversation here with this final bit. The solution for the above is that you need to take into account the radius of curvature and you're clearly not doing that. The inside of that tube needs to be relatively smooth in the direction of travel, not perpendicular to it. You could also interleave to two segments if you wanted it to be even smoother. So no, this is not a hard problem in spite of your continued insistence that it is because you can't solve it. http://jacquesmattheij.com/you+can+not+do+that http://jacquesmattheij.com/you+can+not+do+that
  - sillysaurus3 12y ago
    If you don't have time, fine. If you don't want to talk, fine. But I have some strong words which, out of respect for HN's guidelines, I won't say. Being dismissive of a newbie's concerns while killing their interest in the field isn't great, especially after they've put hard work into giving you a clear-cut example of the technical reasons why something looks hard to them. And I still don't understand how your solution wouldn't leak air into the hyperloop unless the steel sleeves were pressing very firmly into each other. Like the inner sleeve forcefully pressing into the outer sleeve. I have no idea why you refuse to admit this is at the very least a nuanced problem.
    - jacquesm 12y ago
      > If you don't have time, fine. If you don't want to talk, fine. I'm not on your payroll and you're stuck in a groove. > But I have some strong words which, out of respect for HN's guidelines, I won't say. Feel free, I'm not made of sugar. But you're arguing from a position that makes no sense to me, you're apparently entirely ignorant of the basics of mechanical engineering and you're going to tell the likes of Elon Musk and his band of merry engineers what they can or can not do. They just came within a hair of planting a friggin' rocket on a barge from space. Do you really believe they couldn't get a bunch of tubes to slide inside each other without overshooting their air intake budget? That's mostly a factor of 'how big are the pumps' and 'how many such sliding spots do we need' (a few hundred would do just fine) and how much room there is for additional seals (plenty). > And I still don't understand how your solution wouldn't leak air into the hyperloop unless the steel sleeves were pressing very firmly into each other. Like the inner sleeve forcefully pressing into the outer sleeve. No, you don't need that you can use regular seals for that, just like we do on high pressure air connections, fun fact, they work better when the difference is higher, go figure. > I have no idea why you refuse to admit this is at the very least a nuanced problem. Because it is a nuanced problem for you, but not for anybody that has the wherewithal to be hired on the engineering parts of a project like this. Just like my little brother would find assembly language a 'nuanced problem' and I find it relatively easy. It all depends on whether or not you're doing this (mechanical engineering) on a daily basis or whether you want to be back-seat driving nay sayer. Once you've decided on the latter any solution will be inadequate.