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A previous HN discussion brought up the possibility of a Launch Loop and several descriptions of that proposal seem to fit very well. A Launch Loop is an iron
by deftnerd 13y ago
A previous HN discussion brought up the possibility of a Launch Loop and several descriptions of that proposal seem to fit very well.
A Launch Loop is an iron cable just 2 inches thick that runs inside of a sheath at tens of thousands of miles an hour. The sheath has electromagnets inside of it to accelerates the cable. The motion of the cable would cause the loop to curve and raise into the sky.
To outside observers, it would look like a giant version of the St. Louis arch with the peak nearly in low earth orbit, but only a few inches thick. The magic comes with the fact that the iron cable can be used for travel by using electromagnetic attraction to the iron cable through the sheath.
What's interesting is that while there are several engineering challenges, unlike a space elevator, this wouldn't require any materials technologies that don't already exist today. The iron cable could be made by existing forges that make the cabling for bridges, and the electromagnetic sheath could borrow a lot of existing technologies from the hard drive manufacturing industry.
It would also fit with his previous work on Space X and Solar Cities to some extent.
A launch loop can be used to transport cargo or passengers high enough that the energy required to get them into orbit is very inexpensive, which ties into his Space X work.
The external sheath of the Launch Loop could have solar panels on it to power the electromagnets that help keep the loop in motion, and even when the sun goes down, millions of tons of iron spinning like a flywheel has enough kinetic energy to keep going until the sun rises again.
I wouldn't be surprised if he ran across the concept when he was researching ways to get into space before he founded Space X, and it's his "Step 2".
Lastly, if you had a giant cable stretched across the sky that worked kind of like a bicycle brake cable in its sheath, but the cable was running through the system at 30k mph in a giant loop, what better name than Hyperloop? It also explains why a trip that he describes as being twice as fast as an airplane would take 30 minutes. It takes more time to go to LEO and back down
Keep an eye out for Musk buying any patents on electromagnetics or him buying a oceanic cable-laying ship.
http://en.wikipedia.org/wiki/Launch_loop http://en.wikipedia.org/wiki/Launch_loop
- btilly 13y agoThat suggestion fits amazingly well. I have no idea how I missed that previous HN discussion, but I must have. Because I'd remember if I'd seen that suggestion.
- schiffern 13y agoI put forward my argument here: https://news.ycombinator.com/item?id=4806458 https://news.ycombinator.com/item?id=4806458 Of course, Elon Musk had to throw a wrench in it. From SXSW: >[The Hyperloop is] not exactly a train. It's a new mode of transportation that doesn't exist. It could be underground or above-ground. An underground Lofstrom loop seems unlikely. The most revealing hints are the speed and the cost. Musk says it'll be cheaper than the LA-SF high-speed rail, which is so expensive because the allowable turn radius is enormous. Their right-of-way acquisition is constrained by ruthless physics. Since the allowable radius scales as square of velocity, anything doing LA-SF in 30 minutes will move more or less in a straight line (except near the endpoints). So it has to be a straight line, but also avoid right-of-way issues. In my mind the Lofstrom loop is still the only option that fits.
- jholman 13y agoThe people who originated the concept of the launch loop wanted to solve problems of launching spacecraft, thus the name. Elon Musk wants to commute faster between LA and SF, because he does that 400 mile commute 4 times a week. (Obviously Elon also very much wants to launch spacecraft, but maybe has reasons to ignore the launch loop for that purpose.) With that in mind, is there any reason a launch loop needs to be vertically oriented? Why can't it go, you know, SF, LA, San Diego, Las Vegas, Reno? And if so, why can't parts of it be "underground or above-ground"?
- schiffern 13y ago>maybe has reasons to ignore the launch loop for that purpose True. I think you would probably agree that they're more technical than anti-competitive. Musk has called space elevators a long-term optimization, but points out that you still need rockets anyway. Engineering-wise, a small loop is a lot easier than an orbit-capable loop. >is there any reason a launch loop needs to be vertically oriented? In the canonical implementation, the loop is actually fired horizontally from the base stations. The curve ofhe Earth makes the angle for the vertical component. You're quite right, of course, that the optimized design for launching is different from the optimized design for transport. I picture in my head a >20° departure angle, but I haven't run the math so I really don't know. I don't quite understand your question. Could you clarify?
- hansy 13y agoMusk explicitly mentions, "If you put solar panels on it, you generate more power than you would consume in the system. There's a way to store the power so it would run 24/7 without using batteries." [1] [1] http://www.theverge.com/2013/5/29/4378468/elon-musk-teases-june-news-on-hyperloop-rapid-transit-system http://www.theverge.com/2013/5/29/4378468/elon-musk-teases-j...
- tripzilch 13y agoMaybe I'm reading over it, but the article you link doesn't actually seem to contain that quote?
- mkr-hn 13y agoIt's just before the tags and comments.
- uvdiv 13y agoI think that might be true of launch loops? The cable has incredible kinetic energy, but it is magnetically suspended in a vacuum tube, so its power loss could be low.
- deleted 13y ago[deleted]
- phreeza 13y agoWhat happens to the sonic boom in this scenario? I understand that is the main obstacle to conventional supersonic flights above or close to land, how would this be different?
- Someone 13y agoThe tubed is pumped vacuum. See http://launchloop.com/VelocityShear http://launchloop.com/VelocityShear. That also argumentatie that having a heavy fast-moving Core close to a heavy stationery ouder tube is less of a problem than having a hard disk platter close to a stationry 1 gram (possibly less) disk head. I do not quite get that. The damage, once something goes wrong, is way higher, so we should make a much larger effort to decrease the probability that something goes wrong.
- joshuahedlund 13y agoThat sounds interesting for, say, a sci-fi novel, but in the real world I wouldn't want to be responsible for dealing with infrastructure maintenance, earthquakes, tornadoes... Can you imagine if even part of something like that collapsed?
- lifeisstillgood 13y agoOver the ocean? Would be relatively minor impact even for a catastrophic failure. The thing is the speeds - anything that can do NYC-LA in minutes is going to have a catastrophic failure mode that kills everyone in a big radius. I am just trying to imagine the London Underground at 14,000 mph.
- tome 13y agoYou'd get around the Circle Line in four seconds.
- madaxe 13y agoIt could of course also just be a good old-fashioned mass driver, based on his descriptions: http://en.wikipedia.org/wiki/Mass_driver http://en.wikipedia.org/wiki/Mass_driver
- tocomment 13y agoIt's starting to sound like this is the right idea. For you I have questions 3... 1. How do you avoid friction between the cable and the sheath? 2. Isn't the process of using eddy currents to generate motion very ineffient? 3. Would it be possible to build a small scale low speed version as a proof of concept?
- tocomment 13y agoI guess the only problem with his is your have to put it 5+ miles out into the ocean and there's really no way you can sail out that far, take the trip and sail back in under 30 minutes.