Timeline for Perpetual motion machines and rocketry
Current License: CC BY-SA 4.0
21 events
| when toggle format | what | by | license | comment | |
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| May 25, 2021 at 21:11 | comment | added | user121330 | Lighter atoms aren't better for your ion drive, they're just lighter. | |
| May 25, 2021 at 4:35 | comment | added | Peter Cordes |
@BMF: Yes, exactly. To maximize a*b, you probably want to spend equal effort on both sides of the problem, whether that's weight of computers vs. gearboxes, or dollars of materials cost, or whatever. Especially with diminishing returns in how much gain you get for doubling the amount spent one side, not linear.
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| May 25, 2021 at 4:28 | comment | added | BMF | @PeterCordes I think it might be best for the sake of readability to leave out exactly what kinds of mathematical problems are handled. Relegate the explanation away to "it just gets more convoluted and difficult for computers", or something. You bring another good point though. If you can get into the dozens of rpms simply, you can reach into the thousands (needed for a typical prop) mechanically. There's a certain dynamic between those two, electrical and mechanical. Well-shielded, dumb circuitry can withstand EM warfare. | |
| May 25, 2021 at 4:28 | comment | added | nick012000 | @BMF I'll point out that with an infinite supply of energy, you could use superconducting dynamos to generate very large amounts of energy - the main limit of these spinners, when used to drive dynamos, would be wires melting from waste heat generated by electrical resistance, or the machines tearing themselves apart due to the magnetic fields generated. You could just rig your superconductor's cooling systems to the spinner as well, to drive its various pumps. Rockets aside, spinners have the potential to power very scary electrically-powered weapons systems. | |
| May 25, 2021 at 4:15 | comment | added | Peter Cordes | @BMF: (But the more complex you make it, the more the reader is likely to think about how / why the spinner itself was originally designed that way, and the less plausible that it's naturally occurring. And how it implements checking the problems. Some problems like factoring are asymmetric, much easier to verify than implement, as far as we know on non-quantum computers; e.g. real-world RSA crypto depends on that. All NP-complete problems are like that, too, such as travelling salesman: find a path that's at most length N. The less of a black-box the spinner is, the worse, right?) | |
| May 25, 2021 at 4:13 | comment | added | Peter Cordes | @BMF: A simple prop plane would presumably use a gearbox and a simple controller, instead of direct-drive with high-powered number crunching that pushes far into diminishing returns from that avenue of increasing power. Interesting idea to have it not directly speed-programmable, but based on some kind of challenge/response driving a stepper.) | |
| May 25, 2021 at 3:56 | comment | added | BMF | A simple prop plane might become a flying "server room". The reliance on electronics is something that may not work with my envisioned story (I guess the plot dictates my worldbuilding now, sigh). Electronics are all too easy to bring down in a time of war. The Lego set solution looks more favorable at the moment, or perhaps the spoke/cog/paddle solution, if it pans out. | |
| May 25, 2021 at 3:47 | comment | added | BMF | @PeterCordes I can see this becoming an area of study for an entire guild, perhaps a branch of the guild of mathematics. An ongoing research effort for discovering the ridiculous mathematical rules that coax spinners up to higher and higher rpms. The computational machinery needed could be quite imposing, requiring their own power and cooling systems, etc. | |
| May 25, 2021 at 3:45 | comment | added | BMF | @PeterCordes under that solution, yeah there would definitely be physical limits on speed to avoid ridiculousness. That's actually my main concern: over-poweredness. I rather needed the limits imposed by a gear train, its size and mass, to offset the gains. What I had in mind was a seriously convoluted instruction set, based on some hard mathematical problems. Low-rpm modes would require very little and could be maintained by simple dumb control circuitry. The higher you go, however, the more convoluted it gets. Greater computations, greater speeds, hell, maybe the protocols change. | |
| May 25, 2021 at 3:16 | comment | added | Peter Cordes | @BMF: Yeah, Programmable RPM would vastly simplify everything, and greatly reduce the weight of a geartrain to turn slow high torque into huge amounts of heat or whatever else. Or as you say, if you want to hit things with the rotating cube face directly, you can cut out all the gearing. But what's the upper limit on rotation rate? Relativistic linear velocity, flooding the area with gamma rays from smacking air molecules into each other? If there isn't some fixed speed, you'd have to set some arbitrary limits on the range if you want to avoid sillyness. | |
| May 25, 2021 at 3:11 | comment | added | Peter Cordes | @BMF: yes, "paddle" is a good description. Or basically a cog with really deep teeth. | |
| May 25, 2021 at 2:31 | comment | added | BMF | I'm looking to draw an insane amount of energy from spinners. I'll need to find what the torque limit of a spoke/paddle spinner is, with its greater effective surface area. We're talking about rocket engines and hypersonic aircraft propulsion here. I may need to ask a separate question soon, to settle this and move on with development. | |
| May 25, 2021 at 2:24 | comment | added | BMF | 2.) The "Lego set" solution. Supply humans with the alien, magical spinners as well as indestructible cogs, links, gears, etc. | |
| May 25, 2021 at 2:23 | comment | added | BMF | I was considering a couple other solutions too. (Unfortunately, I need these "spinners" for the plot to happen, so I'll have to solve my torque problem somehow.) 1.) One way to fix it is to allow some kind of input, perhaps coded instructions sent via EM communication, to adjust the rotation rate of a spinner. This solves the torque problem by removing the problem. Instead of worrying whether torque applied to a gear chain (whose purpose is to output high-rpm) will destroy said chain, the high-rpm output can be achieved directly. This solution is perhaps too over-powered for my taste though. | |
| May 25, 2021 at 2:17 | comment | added | BMF | @PeterCordes that's a potential solution I didn't consider. The spinners are to come in many sizes and varying rotation rates. I don't see why spokes or paddles can't be an edition. (However odd it may look, lol.) | |
| May 25, 2021 at 1:35 | comment | added | Peter Cordes | @BMF: perhaps you can extract more work from a cube spinner by using it like a camshaft / crankshaft, placed under a pillar to raise it. (Perhaps allowing for the material to abrade away at the slide point.) i.e. using the bouncing of a square wheel with it's non-constant "diameter". | |
| May 25, 2021 at 1:31 | comment | added | Peter Cordes | @BMF: Perhaps your spinners could be a different shape, like infinitely strong flat spokes a meter or two long sticking out of a counterrotating axle for the largest ones. (3 or more spokes per wheel, maybe 8, maybe with the number having some significance to their origins, or varying by spinner.) That distributes the load through a much larger volume of mundane material, and over a larger area (since the spokes are wide and flat like cube faces, but the whole face is moving in the direction of motion). | |
| May 24, 2021 at 22:39 | comment | added | BMF | @jdunlop So it seems. It's something I totally overlooked when building my world. I'm currently trying to figure out how much torque a socket connecting a gear train to a spinner could reasonably handle before deforming. But, it's not looking promising. | |
| May 24, 2021 at 22:23 | comment | added | jdunlop | Worth pointing out that you don't have infinite power, just infinite energy. The torque is infinite, but the materials being used to turn that into useful work are mundane, so the actual power being extracted is finite. This makes a lot of these ideas impractical. | |
| May 24, 2021 at 11:02 | comment | added | Clearer | If you have effectively infinite electrical power, water IS hydrogen. | |
| May 24, 2021 at 10:45 | history | answered | PcMan | CC BY-SA 4.0 |