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The Slingatron: Building a Railroad to Space
- daniel-cussen 13y agoI thought this would be totally hokey, but it wasn't. If Freeman Dyson says it's a brilliant idea, then maybe it is. I see it as being in the same category as the Hyperloop--at least worth a look at.
- valtron 13y agoReminds me of a Lofstrom Loop: http://en.wikipedia.org/wiki/Lofstrom_loop http://en.wikipedia.org/wiki/Lofstrom_loop
- msandford 13y agoThis idea to me seems a lot more feasible. Read about it years ago and it makes me sad to see that it's not happening.
- jessaustin 13y agoA structure 2000 km (actually, 4000 km) long is envisioned, with internal speeds of 14km/s. We're just not very good at building that sort of thing yet.
- mjn 13y agoAt those scales, it's considerably harder than building high-speed rail NYC<->LA, and the latter is usually ruled out as infeasible.
- kevinpet 13y agoThe key number is 40-60,000 Gs. Wikipedia helpfully informs me that this is 3-4 times the rating of the electronics used in artillery fuzes.
- tlb 13y agoOne possible use is launching solar reflectors to reduce global warming. https://en.wikipedia.org/wiki/Space_sunshade https://en.wikipedia.org/wiki/Space_sunshade
- yew 13y agoG forces are less problematic when launching bulk materials (fuel, air, water, foodstuffs, metals - as I see the project proposal suggests). If you're 'catching' the payload at the other end, you can make the launch vehicle very dumb. Even more so if you can leave your engine at home and still use it (see also "ablative laser propulsion"). Radial forces on the launch platform itself are more of a concern. You have to stop it from tearing itself apart while it overcomes friction/drag and reaches escape velocity.
- simonh 13y agoTheir proposal also suggests that the capsule will need it's own rocket motor (and hence guidance and telemetry system) to get to orbit.
- DanielBMarkham 13y agoA few years ago, I was interested in the physics of getting LEO costs down, so I did some computer modeling. This general idea was the best I could find. Put the mechanics and fuel for the vast majority of orbital insertion inside some ground-based system, instead of trying to carry it. Impossible to use with humans, but for lots of other stuff like supplies, more fuel, habitats, etc -- should work fine. At least as far as I could tell. It's much more feasible than a Space Elevator, and no new tech needs to be invented. Having said that, I'm not so sure this is going to work in KickStarter format. Sure, build a bigger laboratory model, but to make this really work it's going to need a lot of cash.
- Tloewald 13y agoIf we're not going to worry about living payloads, why not just use a circular rail gun? (A macro scale cyclotron if you will.) It has no moving parts (except perhaps the exit point), it doesn't need to be a spiral, it doesn't all need to be mounted on a moving platform.
- DanielBMarkham 13y agoI agree. I didn't use this specific configuration either. All I meant was the general idea of slinging cargo from the surface into LEO. Much, much cheaper than using explosives to dead-lift things out of the gravity well.
- czottmann 13y agoBacked. Super-interesting concept, and the people at HyperV Technologies Corp seem to know what they're talking about, so I am excited about this. For example, their other KS project—the Plasma Jet Electric Thrusters for Spacecraft[^1]—was successful both in funding and delivering what was promised. Also, you gotta love their pretty low-key / somewhat amateur'ish videos. ;) [^1]: http://www.kickstarter.com/projects/2027072188/plasma-jet-electric-thrusters-for-spacecraft http://www.kickstarter.com/projects/2027072188/plasma-jet-el...
- solistice 13y agoThe right hand rule thing reminded me of my physics teacher, or pretty much any physics teacher ever. Everyone grows up. Except physicists. Physicists are special. Or else, how do you explain a grown man sitting in front of a leynhurst generator for an entire noon just turning the wheel and marveling at the discharge?
- jamesdelaneyie 13y ago|Also, you gotta love their pretty low-key / somewhat amateur'ish videos. ;) The kickstarter aesthetic
- czottmann 13y ago> The kickstarter aesthetic I disagree. Most KS videos I watched were very upbeat/chippy/hipster'ish/enthusiastic pieces of semi-professional ad/film making. The HyperV videos, not so much. They look like transfers from a VHS camcorder. :)
- binarymax 13y agoPosted this a couple days ago, and it didn't take. Very glad to see that this finally made it on the front page. Hyper-V had an impressive plasma thruster campaign, so I know they can deliver. I hope this gets funded and they can pull of the proof of concept...it seems so much better than many other ideas for small payload launch.
- msandford 13y agoIt's an interesting idea to be sure. And it's definitely one that seems kinda crazy, which probably means it could work. But there's one crucial detail missing: calculations on the centripedal/centrifugal force necessary to continue acceleration and/or direct the payload from horizontal to partially/completely vertical. http://en.wikipedia.org/wiki/Centrifugal_force http://en.wikipedia.org/wiki/Centrifugal_force a = v^2/r so let's go with 1km/sec and a diameter of 5m. a = 1,000 x 1,000 / 2.5 = 400,000 m/s^2 or roughly 40,000 g Now let's assume that it's a 1/4lb weight as described or 0.1kg. F = m x a = 0.1 x 400,000 = 40,000 newtons. Next let's assume that the piece of metal is steel and roughly cubic. It's density is around 8g/cm^3 (http://hypertextbook.com/facts/2004/KarenSutherland.shtml http://hypertextbook.com/facts/2004/KarenSutherland.shtml). Mass = density x volume => volume = mass / density = 100g / 8g/cm^3 = 12cm^3 cube root(12) ~= 2.3 so we've got a cube with faces around 2.3cm on a side. They've said that they're going to encase it in plastic so let's neglect the strength of the plastic and call it 2x the size of the cube. That brings this to 5cm x 5cm. Now let's translate that into pressure. P = F / a = 40,000 / (.05 x .05) = 16 MPa The tensile yield strength for a regular, boring steel (A36) is 250MPa and the ultimate tensile strength (the max it can hold prior to breaking but after deforming) is 400MPa so this is fine for now. http://en.wikipedia.org/wiki/Ultimate_tensile_strength http://en.wikipedia.org/wiki/Ultimate_tensile_strength At 2km/sec you get 64MPa needed and at 7km/sec you need 784MPa all of which are within the realm of possible but rapidly heading towards the limits of material strength. The 784MPa number would go down if you made the diameter bigger, too. Ultimately they aren't building a thing which will disintegrate the slug (my initial thought) but it's going to have to be extremely well engineered and precisely made for balance in order to ensure that it doesn't tear itself apart. The technical combination of a steel rolling mill and a swiss watch. And due to balance issues definitely harder from a technical perspective than even the really tough portions of a rocket. EDIT: didn't realize that "*" did formatting so I fixed it. EDIT2: Screwed up on the calcs, assumed 10,000m/sec instead of 1,000/msec. Fixing those.
- jamesaguilar 13y agoAlso, if I'm reading Wikipedia right, delta v to LEO is 10km/sec, and that's not counting the insane atmospheric drag on something travelling that speed at sea level. Good luck.
- ChuckMcM 13y agoSigh, the challenge of magnetic rail launchers and this slingatron thing is the atmosphere. Sure if you could pull a vacuum around the launch facility you might get close, but consider that the typical rocket launch gets maximum dynamic pressure as it goes supersonic on its way out of the atmosphere. This thing is going to hit that and live in that space while its going around the loop. Now compute the effect of a supersonic shockwave that is curling in on itself. The standing wave you generate it going to generate some amount of overpressure, back of the envelope, looking at four to six wavefronts collapsing on themselves as you go around the final loop of maybe 6 atmospheres? There is a reason fish don't swim in a circle to build up speed to jump out of the water, because their own wake would stop them cold. I wonder if someone could do a quick CFD of a payload travelling in a 7.6km/s at sea level is in the 'high hypersonic' regime (> MACH 10 closer to MACH 25) The energy you are dumping into the air at that point is going to create a pretty impressive flame front by itself. This is perhaps the coolest things about the really high speed videos of the Navy railgun project.
- Daniel_Newby 13y agoRe. the flame front, they say that the payload will be supported from the rail by a plasma bearing. You mean an air bearing? No. A plasma bearing. You have to admire their chutzpah.
- zeteo 13y agoWhile 250k is peanuts compared to regular costs of rocket research, I feel 1 km/s is not that impressive of a demonstration. Rifles have achieved higher muzzle velocities as far back as 1935 [1], and ground-based systems capable of over 3 km/s have been demonstrated in the '60s and '90s only to meet with little interest [2] [3]. [1] http://en.wikipedia.org/wiki/.220_Swift http://en.wikipedia.org/wiki/.220_Swift [2] http://en.wikipedia.org/wiki/Project_HARP http://en.wikipedia.org/wiki/Project_HARP [3] http://en.wikipedia.org/wiki/Super_High_Altitude_Research_Project http://en.wikipedia.org/wiki/Super_High_Altitude_Research_Pr...
- 3327 13y agoyes but this is purely mechanical
- microDude 13y agoShouldn't DARPA being funding this sort of thing?
- jessaustin 13y agoFrom other comments, it seems there are a number of basic physics and materials challenges involved in reaching orbit. However, this sort of technology used with self-guided projectiles could produce the UP/Ex launcher described by Vinge in Rainbows End, used for very rapid local and interstate deliveries. It takes much less energy to hit the next town over than it does to reach LEO.
- jccooper 13y agoBallistic launch to orbit is... problematic. Getting something going fast enough is tough (G loads, aero loads, material in the launcher, etc) but doable. A really really big light gas gun should do, if the "Slingatron" won't. Thing is, you cannot shoot something from the planet's surface to orbit. Just can't. If energy is too low, you're normal ballistic, and the projectile falls somewhere downrange. If energy is too high, you escape from Earth's gravity well, and you never see the thing again. (This might be fine for sending materials to the Moon, though.) What if the energy is just right? Well, you go into orbit with closest approach at exactly your altitude. Which is you one orbit later... if aero effects haven't already caused enough energy loss to run the projectile into the surface, as they would on Earth. (Side bar: even on the Moon or Mars, it wouldn't work well. Orbit at the height of the highest lunar mountain would be very unstable, though it would work better than on Earth! Might get a few orbits out of it before crashing, if you can find a path without huge mascon changes, and if it doesn't hit your launch facility. The top of Mons Olympus still has enough atmosphere to be problematic.) So you have to have high-altitude propulsion to alter your trajectory once you get there, so you can orbit at a reasonable altitude. Which is why they note that they need an onboard rocket. And that's unfortunate, because it throws away the appealing simplicity of ground launch: passive payloads (and thus low marginal costs). Now, alongside your space-gun you've also got to design a mass-produced probably-expendable rocket system (with guidance) that can survive wicked G loads. And so here come a lot of extra marginal and development costs and a lower payload fraction. Does your gun-and-rocket system still beat a 2/3-stage rocket? With enough volume it might, but where do you get those customers? I kind of like the idea of shooting your massive space-gun at an active target that can do the orbital circularization for you; either a tug that refuels itself from the projectile, or more exotically a rotating momentum exchange tether. That on-orbit system adds additional development and capital expense, in exchange for very low marginal cost. Which would be nice if you had the volume--but nobody needs that sort of volume in space now (nor is likely to for quite some time.) But once some system with reasonable development costs and acceptable marginal costs has paved the way, it might be a lovely system for bulk material transport (probably mostly volatiles, like water, but maybe also metals for construction).
- DigitalSea 13y agoThis is an interesting idea, but one that heavily relies on factual mathematics to work correctly. Even slightly get your calculations on force required to launch the vehicle and continue acceleration wrong and you've got a potential disaster on your hands when whatever it is you are launching comes falling out of the sky in your direction. I really like the outside-of-the-box approach and idea, it will be interesting to see if $250,000 is enough to build something of this magnitude which will need to be tested and tested and then tested 100 more times before you could even attempt to try it in the real world.
- alinspired 13y agointeresting "mechanical" idea for sure, why can't you use magnetic loop to speed up the object more gradually and fire up afterwards. Also really interesting references to HARP in this thread: http://en.wikipedia.org/wiki/Super_High_Altitude_Research_Project http://en.wikipedia.org/wiki/Super_High_Altitude_Research_Pr...
- chrischen 13y agoThis is sooo going to be weaponized.
- cabalamat 13y agoThe fact that this has obvious military applications suggests to me that if it was practical, militaries would have already done it.
- rbanffy 13y agoIndeed. It looks like an obvious ship killer. What can you do to a one ton steel brick travelling in your direction at Mach 10?
- jtheory 13y agoIt's hard to imagine scaling this up to be able to throw a ton at a time. If you want to throw something that heavy, you'll have a much easier time using explosives to do it -- and we've been able to do that for quite a long time now (multi-ton shells were fired in WWI).
- Tloewald 13y agoGiven the spin-up time and the fact it's a giant gyro (and thus can't be aimed) the ability of a 15" gun to fire payloads at enemy ships seems far more useful.
- Selfcommit 13y agoBut.. Does it work in Kerbal space?
- electronous 13y ago+1 for the xkcd ref ;)
- Selfcommit 13y agoSomeone found the humor =) I'll suck on the -2 Karma for a while...
- danthewireman 13y agoThis looks fantastic if it'd work, but I wonder if it'd be more useful to build in space, and then use it to launch little probes. No atmospheric drag. I realize building it in space would be a good bit harder than on the ground. I'm just in wouldn't-it-be-cool land.
- DanBC 13y agoBuild it on the ground, and use that ground based version to sling up the moon based version, and use that to sling out the stuff for the Mars colony?
- Aqueous 13y agoI'd be all for it if it could get organic materials to space, including humans, and if it could do so without a rocket stage. The demo videos are really impressive (especially the blowing of the hole through that rug - be careful! Looks like you might have a modern weapons technology here as well) but it seems unstable and not versatile enough payload wise!
- PBxdId7wFr 13y agoSeems like overoptimistic, poorly thought through horseshit to me.
- lifeformed 13y agoI was hoping the $10K slot would get you a tiny payload of your choice flung into space.
- emhs 13y agoI'd hoped so too, at first, but since this is just to build a non-orbital mid-scale demonstration, I figure building this one doesn't ensure that the orbital one will get built, and thus they couldn't guarantee that a full-size slingatron would ever exist to deliver the promised launch. Would've been nice, though. They'll probably offer that if they kickstarter the first orbit-capable one.
- ytjohn 13y agoStill trying to get rid of all those old CRT monitors out in the storage shed?
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- riemannzeta 13y agoLife imitates art? http://en.wikipedia.org/wiki/The_Moon_Is_a_Harsh_Mistress http://en.wikipedia.org/wiki/The_Moon_Is_a_Harsh_Mistress Is Mike already lurking in some massive instance?!
- Blahah 13y agoMy thoughts exactly. I'm actually amazed it has taken so long for this idea to come to anything close to fruition. Heinlein really grokked the future.
- zw123456 13y agoIf it does not work they can always re-purpose it and totally clean up in the next punking-chunkin competition.
- realrocker 13y agoIf this takes off one of the common uses would be flinging the last remains of dear loved ones into space.A "human dust" would surround the lower orbit. Anaerobic bacteria will thrive in the dust fed upon by deadly viruses. Skeletal remains would form microscopic spherical super-strong bone pods encasing these deadly viruses. This dust will stick to spacecraft on re-entry. The deadly viruses infect the human population resisting any medical intervention(since cooked in space) leading to the inevitable apocalypse: Zombies. Totally worth the 5$ I say. Please down vote me. I am bored.