Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: Black Wolf on February 09, 2006, 01:12:27 pm
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I've been designing ships for my universe, and I've been making them all tapered and aerodynamic. My justification for this is that if they're moving at fast STL speeds (Say, up to around .5 C - still too slow for relativity to affect them, but at a point where hops to relatively nearby systems aren't impossible), and they hit space dust or asteroid fragments or whatever, it'll hit them a glancing blow rather than directing all of the kinetic energy into the ship directly. What I want to know, from someone with better physics than me, is, assuming the front was still pretty solidly armoured, whether this would actually work? If it wouldn't, I'll scrap it and either invent some kind of deflector, or just massively armour the fronts of the ships and put a speed cap on them.
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I've been designing ships for my universe, and I've been making them all tapered and aerodynamic. My justification for this is that if they're moving at fast STL speeds (Say, up to around .5 C - still too slow for relativity to affect them, but at a point where hops to relatively nearby systems aren't impossible), and they hit space dust or asteroid fragments or whatever, it'll hit them a glancing blow rather than directing all of the kinetic energy into the ship directly. What I want to know, from someone with better physics than me, is, assuming the front was still pretty solidly armoured, whether this would actually work? If it wouldn't, I'll scrap it and either invent some kind of deflector, or just massively armour the fronts of the ships and put a speed cap on them.
Why not just cheat and say aerodynamic type designs improve FTL travel?
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The probability of hitting too much sapce dust is preety low anyways (well, for cruising through a solar system, if your visiting the rings of saturn it becomes quite high, but theres no reason to move at .5c in the rings of saturn). But in the event you did hit some dust it would work to reduce the KE released, but the key word is reduce. It all depends on how sharply angled your hull is and how big these micrometeors are. And ofcourse, where your ship is will determine the last one, as well as the probability of an encounter.
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Why cant the ships be athmospheric capable? That would explain the shape.
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Aldo: This is STL - Slower than Light. They're not moving under conventional drives as we know them today, but they are moving in normal space.
Prophet: Because they're massive - the specific design I want to use this for is a colony ship.
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Aldo: This is STL - Slower than Light. They're not moving under conventional drives as we know them today, but they are moving in normal space.
Prophet: Because they're massive - the specific design I want to use this for is a colony ship.
I was assuming you had some form of FTL.
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Ehm, doing a part of the basic maths in my head, I'd say the less oblique (that means right angled, doesn't it?) the impact, the less of the energy is actually transferred into the vessel, or at least transferred as a vector directly opposed to the movement, but I'm not too sure on the effects.
If I knew the amount of dust size/mass of a particle and the actual angle on which it would hit, I might be able to do some maths and see if it really mattered.
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My educated guess says, that if you hit anything bigger than a M&M at 0,5 c, you're ****ed, shield or no shield doesn't matter.
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I could also do some quick maths on what the force per square meter would be if I knew both size and mass. But indeed, anything above a certain mass would really, really blow a hole in the ship unless you did something creative.
(Like pushing out a gas over the hull, but the speed of the ship keeping it stuck to the hull or something like that. Crazy idea, just thought it up)
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doesn't areodynamics rely on a fluid like flow to do it's thing, I don't think lone particles especaly at the given speeds are going to care much about the shape.
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Bob, it would still glance off the hull if it hit it at an angle, and therefore not transfer all of it's energy.
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by the way, a one gram particle traveling at 0.5c impacting your hull would create a 2.7 kiloton explosion, or about 1/7th of the hiroshima bomb.
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So barely noticable to anything in the FS2 universe then? :D
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TYhings get hit by a sun exploding and are still relatively intact in the FS universe, take a guess...
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doesn't areodynamics rely on a fluid like flow to do it's thing, I don't think lone particles especaly at the given speeds are going to care much about the shape.
If you take a certain mass impacting at 0,5c, and you say that it'll bounce off, with at least half of the KE staying KE, and the rest of the energy becoming heat, if you do the vector math, the angle will matter. IIRC.
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Actually interstellar dust is quite a problem even at speeds like 0.3-c.
Reason is, one of my profs told me that's the speed the probe to Alfa Centaury will reach using a solar sail.
However the density of said dust is still a lot lower than in the Solar System....a stray proton at most. The actual problem is radiation shielding. Anyone calls up how the X-Ray machine works? Yeah it dupms high speed electrons into a slab of metal.
That's the reason why an anti-radiation screen will be a must have for STL interstellar travel.
So I wouldn't bother with angling/streamlining the ship, but worry about the massive radiation shielding the crew will require.
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Sorry, but no amount of aerodynamic shape will help you at 0.5c. The fallacy of the argument of an angled impact reducing the kinetic energy of a collision is that it requires an inelastic collision, ie, the particles hits the top layer and bounces right off. At relativistic speeds, a particle is going to go right through the top layers of steel like it was sweet cream. Any known solid at these speeds in an impact (dust, pebbles, a baseball) can be treated as just a collection of particles because the kinetic energy far exceeds the binding energy of the individual atoms in the particle. So a particle won't bounce off a plate like a poolball. It's going to hit like a drop of water splashing into a film of oil, i.e completely disrupting both structures and mixing them temporarily. The result is that whether the shielding is angled or flat on, each impact will vaporize approxomately the same volume of shielding.
An analogy of this effect is in the study of hypersonic impacts of solids done for explaining meteor craters. A roughly spherical meteor impacting a surface (and this holds true for micrometeors hitting the lunar surface at only 20km/s) will leave a round hole about 10 or so times its radius whether it impacts at an angle of 0 or 60 degrees. Craters will only elongate enough to give a clue of the angle of impact at very shallow angles.
Back to your ships, an aerodynamic shape is worse for high speed STL travel than a long thin cylinder. This shape will prevent a minimal cross section for impactors (and at 0.5c, they'll all basically be hitting head on). Armoring the front of the cylinder with a bunch of ablative ceramics or what have you would be the most ideal with present technology.
Also, the density of the solar system space is about 5 atoms per cubic centimeter. Interstellar space is less, but not negligable and since the journey to the nearest starsystem would take about 7 years or so at 0.5 c, you'd need a fair amount of plating to grind off.
Some type of repulsive energy shield you could beam in front of your ship would be ideal. Honestly, glueing an iceberg to the front of your ship would work pretty well too. But my main point is that aerodynamics work in classical fluids, they don't work in relativistic space flight.
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^that's what I was thinking^
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Well, i wouldnt say no amount, but no sane amount....
Anyways, flaser and bobfar seem to be preety much right.
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However, if the ships look cool, use them. :D