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Re: Hyperloop firm shows off the magnetic tech that will help it move at 760 mph
Author: mook
Date: 05-09-2016 - 13:28
This. And as for the first question, it won't produce any sonic booms because if it actually work it'll be inside a tube under a partial vacuum. Assuming of course that no boom is created inside the tube and transmitted to the outside through the tube walls (that's manageable if it happens).
That said, 'magnetic levitation' (better term would be 'magnetic suspension' because there's no magic involved; the ones who think that the laws of physics are what's suspended are probably keying on the 'levitation' term) was around much farther back than the 1960s on a small scale. Did anybody ever use "frictionless" tracks in HS or college physics labs? Some of those were mag suspension; others were air suspension. The mag suspension worked better and were quieter. And sci-fi stories way back into the 1930s had pneumatic or evacuated magnetic tunnels "through the core" for long-distance travel.
Hmmmm. Let's see. It's about 400 miles from SF to LA (downtown-downtown, by a reasonably direct but not perfectly straight route, such as down I-5). Maximum comfortable acceleration/deceleration in a device that doesn't require seat belts (e.g. a train) is about 4 mphps. So from a dead stop a tube car that runs 760 mph would take 760/4 or 140 sec or (allowing for fade in & fade out so we don't break necks) 3-4 minutes to get up to speed. Also, there be curves; it's not a straight line even if it's fairly direct, and unless those curves have a Really Huge radius (unlikely for a real-world route) it will have to slow down a bit to avoid punishing g-loads. If there's a station somewhere in the Valley to transfer local traffic, there's a stop/dwell/start involved unless there's a bypass of some kind for expresses (tube trains don't look like they would handle switches well - ???). Silicon Valley would demand its own station, of course, as would, probably the San Fernando Valley. So by the time you're finished, you've added 5-6 minutes of decel/dwell/accel time times 2-3 intermediate stations. Figure the curves (horizontal and vertical) into it, and I suspect the practical travel time SF-LA is likely to be around an hour rather than the near 1/2-hour the raw speed suggests. Of course, it's still the only thing proposed so far (including the pipe dreams talked about at election time) that can arguably meet the time requirements of The Proposition ...
That said, 'magnetic levitation' (better term would be 'magnetic suspension' because there's no magic involved; the ones who think that the laws of physics are what's suspended are probably keying on the 'levitation' term) was around much farther back than the 1960s on a small scale. Did anybody ever use "frictionless" tracks in HS or college physics labs? Some of those were mag suspension; others were air suspension. The mag suspension worked better and were quieter. And sci-fi stories way back into the 1930s had pneumatic or evacuated magnetic tunnels "through the core" for long-distance travel.
Hmmmm. Let's see. It's about 400 miles from SF to LA (downtown-downtown, by a reasonably direct but not perfectly straight route, such as down I-5). Maximum comfortable acceleration/deceleration in a device that doesn't require seat belts (e.g. a train) is about 4 mphps. So from a dead stop a tube car that runs 760 mph would take 760/4 or 140 sec or (allowing for fade in & fade out so we don't break necks) 3-4 minutes to get up to speed. Also, there be curves; it's not a straight line even if it's fairly direct, and unless those curves have a Really Huge radius (unlikely for a real-world route) it will have to slow down a bit to avoid punishing g-loads. If there's a station somewhere in the Valley to transfer local traffic, there's a stop/dwell/start involved unless there's a bypass of some kind for expresses (tube trains don't look like they would handle switches well - ???). Silicon Valley would demand its own station, of course, as would, probably the San Fernando Valley. So by the time you're finished, you've added 5-6 minutes of decel/dwell/accel time times 2-3 intermediate stations. Figure the curves (horizontal and vertical) into it, and I suspect the practical travel time SF-LA is likely to be around an hour rather than the near 1/2-hour the raw speed suggests. Of course, it's still the only thing proposed so far (including the pipe dreams talked about at election time) that can arguably meet the time requirements of The Proposition ...
