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Okay, just something I thought of while fiddling with my LEGO: An aerodynamic desigh is only handy in atmosphere and not necessary in space, right? I remember it from physics lessons and some posts in this newsgroup. But space is not a true vaccuum, (...) (21 years ago, 23-Jun-03, to lugnet.space)
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(...) Sylvi, Aerodynamics is complex. One usually divides aerodymanic behavior into different categories, depending on the speed of the vehicle in comparison to the speed of the particle. If your vehicle is traveling under particle speed (the speed (...) (21 years ago, 23-Jun-03, to lugnet.space)
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(...) One of the cool things about space is that you can always rationalize it with some kind of nifty technology, like navigational shields. :D I don't think those micro-particles would care if your ship is aerodynamic, since there's no air in (...) (21 years ago, 23-Jun-03, to lugnet.space)
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(...) I think the biggest problem for a ship accelerating towards light speed is not particles, but energy consuption. remember, the faster you go, the more energy you need to propell yourself, and this increases exponentially. essentially, (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) Wow, that's quite a bit more complicated than I assumed... (...) Yup, I had those in mind for vehicles which actually travel through atmosphere. (...) No thank YOU, George, for clearing some things up. What about this, taken from the SF novel (...) (21 years ago, 23-Jun-03, to lugnet.space)
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(...) True, of course. However, I was wondering about the most efficient design to make that large ammount of energy used effeciently! (...) In mine the situation is similar.. (...) Thanx! Love, Sylvi (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) Pretty right on your first point. Aerodynamics works where there is an atmosphere. A ship that is capable of nearlight speed would be have to have some type of deflector for those few in-vacuum molecules, because as you point out, they would (...) (21 years ago, 23-Jun-03, to lugnet.space)
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(...) Yeah, I thought that when they would develop near lightspeed capabilities, they would develop shields, too! What if you just put water all over the hull? It would instantly turn to very hard ice and that would shield the ship against (...) (21 years ago, 23-Jun-03, to lugnet.space)
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In lugnet.space, Mark Sandlin wrote: shnipage (...) I've always wondered about this. Although particles would have no atmosphere to be whisked around the shape with, wouldn't a particle hitting a 45 degree angle transfer only part if it's energy to (...) (21 years ago, 23-Jun-03, to lugnet.space)
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(...) Well, it's only theoretical at the moment, but scientists believe that there's such a thing as "Dark Matter". It is invisible to all modern sensing systems (including the naked eye), but it is the only explanation for certain celestial events (...) (21 years ago, 23-Jun-03, to lugnet.space)
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(...) -snip- (...) Sylvi, This is an interesting reference. I can only guess at Reynolds' inspiration, though it does sound like an extrapolation of designs based on hypersonic flow theory (on that front, see (URL) -- note how the optimal shape (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) Yeah, but also in aerodynamics and hydrodynamics, the sleeker it is, the less resistance it encounters on it's forward edge. If you minimize the amount of forward contact on the front, less particles would hit it, causing less overall damage. (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) don't forget the old phylosophy that the faster you go, the greater the chance that small particles will hit you. So at 1/2 the speed of light, you would definately need some form of shielding. An old, and possible, idea is to use a barrier of (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) i think because of all the major scifi shows out there, Star Trek paid the most attention to actual physics and in making their technologies plausible. maybe not probable, but who knows what the future will hold? -Jr.Mar.Hoffman (URL) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) I think this point is dead on! Even though these ships are aerodynamic, they aren't SO aerodynamic that they deflect photons! and while photons are much smaller than your average particle out there, the particles that are present in a vacuum (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) If I understand physics correctly, it doesn't make a difference whether it is the ship traveling at .9 c or the hydrogen atom. The energy released is the same. Thus, that atom is effectively dealing far, far more energy than 1.5E-10 watts. Not (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) Well, in the space-ish situation, the number of particles you're hitting will only come down to size; regardless of its shape, a ship shaped like a perfect lozenge will hit the same number of particles as a ship shaped like a cube, if their (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) Along those lines, you might as well just simply make your ship with the dimensions of a pencil, to minimize cross-section. The degree of electromagnetic radiation reflected back to a transmitter (radar) by an aircraft is primarily based upon (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) ERg. <choke> Blatch. You're kidding, right? The only one offhand that I can think of which is worse is Star Wars. (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) Ack! Heresy! Stone him with light grey BURPS! ;^D Trev (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) That's essentially correct. Two cars hitting each other head-on at 30MPH is effectively the same as one car hitting a stationary vehicle at 60MPH. Obviously the two accidents would not be perfect mirror images of each other, but the level of (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) Not really. When you're dealing with individual particles hitting other individual particles, there really isn't any such thing as a 45 degree angled surface. It's more like billiard balls, where the relative angle of impact is determined by (...) (21 years ago, 23-Jun-03, to lugnet.space)
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(...) It does behave more like a fluid at extremely high speeds. However, have you seen what happens to an airplane when it hits water at mach speeds? It's not pretty, and that's essentially what you'd have to be dealing with in a near vacuum. By (...) (21 years ago, 23-Jun-03, to lugnet.space, FTX)
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(...) I wouldn't say that. Star Wars was intentionally written with cinematic effect in mind. And which is worse, the show that intentionally ignores physics, or the show that tries to obey physics and fails? (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) Eesh. Star Trek script writers tend to accept hypothetical physics as gospel truth (with the result that much of Star Trek physics has since been disproven), and a lot of hard-core Trekkies do the same thing with any physics presented on Star (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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In lugnet.space, Sylvia Tresto wrote: > Okay, just something I thought of while fiddling with my LEGO: An aerodynamic > desigh is only handy in atmosphere and not necessary in space, right? I remember > it from physics lessons and some posts in this (...) (21 years ago, 24-Jun-03, to lugnet.space)
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(...) Ah, now your not talking about dynamics as such, but surface area too. the aerodynamic comes into play with the angle of reflection. Trav (-|-) (21 years ago, 24-Jun-03, to lugnet.space)
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(...) Interesting discussion and all. Aerodynamics in near lightspeed space travel? Whatever, but like someone said, if your suspending disbelief enough to conceive FTL or NLS travel, you can suspend it enough to solve such minor details as space (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) I'm not sure on the physics, but we can assume either to be interchangeable; the ship impacting a motionless particle at .9c, or a particle at .9c impacting the ship. Kinetic energy is derived from mass and velocity. So it is, in effect, a (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) You're right, though I read Jonathan's point as being that I didn't account for relativistic effects in the energy calculation, which is true. If I have the math right, the crossover point where the relativistic energy exceeds the rest mass (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) Bah. If you're going to stone me, at least do me the courtesy of stoning with bricks. :) James (who likes both Star Trek and Star Wars, but has to leave his credulity at the door before watching either. B5 merely makes my credulity give me (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) Yeah, one would hope that if we ever achieve the capability of moving that fast, we'd also have the capability of dealing with associated problems. And if it's comparable to a sports car's engine, I'd think heat buildup would be a bit of a (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) You're thinking of Babylon 5 right? Phasers, shields, warp drive. HA. real physics there. :P Babylon 5 had interial momentum, the centrifugal concept of gravity, real-space phycis and everything Rick Hallman (URL) Das-Brick.Org> ... (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) ohhh, PhotoDynamic, I like that idea. I may have to use that somehow. Good thinking there Alister. (...) Handled like a spastic whale if I remember. (...) Trav (-|-) (21 years ago, 24-Jun-03, to lugnet.space)
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(...) But you're going at .95c, which means you're hitting lots of particles per second. If your ship has a frontal area of 9 sq meters, and 90000 square centimeters, that's 90,000 molecules you're running into for every centimeter forward in space (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) Jonathan, The craft would indeed contact a lot of particles (about 2.85x10^14 per second per square meter of frontal area at 0.95c) but the energy per particle is very small. So the total energy of those particles seems manageable in (...) (21 years ago, 24-Jun-03, to lugnet.space, FTX)
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(...) I have a way you could avoid the whole problem all together using real physics. I think I read this somewhere before in doing my own research on space travel. It involved firing an ionizing beam like microwaves or something in front of the (...) (21 years ago, 24-Jun-03, to lugnet.space)
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(...) If you spin anything around without curving or coming to a complete stop, you'll be sorry. Inertia still applies in space, and at the speeds probably used, a 180-degree spin will turn the entire crew into little puddles on the back of their (...) (21 years ago, 25-Jun-03, to lugnet.space, FTX)
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(...) You're forgetting four things. First, there's no atmosphere, and the main reason for making long banking curves like that is because you can't make abrupt vector changes in an atmosphere. That's not a concern in a near vacuum. Second, no, you (...) (21 years ago, 25-Jun-03, to lugnet.space, FTX)
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In lugnet.space, Leonard Hoffman wrote: -snip- (...) -snip- (...) Now I'm going to start this off with the fact I'm no physicist. I'm not an expert. And everything I'm about to say is relayed from endless conversations I've had with my father about (...) (21 years ago, 25-Jun-03, to lugnet.space, FTX)
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(...) Nope. You're misapplying inertia. The whole ship, including contents, has inertia. If it is moving, say, 1.25 Km/s (pretty darn quick) in arbitrary direction A, it (and all it's contents will continue to move in direction A, and which (...) (21 years ago, 25-Jun-03, to lugnet.space, FTX)
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(...) He does have a point as far as capital ships are concerned. A Starfury is a one-man ship, and everything I've seen suggests that when a Starfury rotates in flight, the cockpit is pretty darn near the center of rotation, so the pilot can (...) (21 years ago, 25-Jun-03, to lugnet.space, FTX)
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(...) Ask your dad about that again. My comment was based on readings from Stephen Hawking's "Brief History of Time" and "Universe in a Nutshell", as well as various online physics FAQ. Granted, in space you don't have to worry about air friction or (...) (21 years ago, 25-Jun-03, to lugnet.space, FTX)
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(...) Yup. But even a ship like the Hyperion could probably spin in place relatively quickly - certainly not at starfury-like speeds - but I imagine it could still do a 180 within a couple minutes. I strongly suspect, given the shape of Earthforce (...) (21 years ago, 25-Jun-03, to lugnet.space, FTX)
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(...) I hadn't really thought about this problem before, but I can see how it would be a problem. If your propellent has an exit velocity of 2mph, it shouldn't ever be able to make you go faster than 2mph. Once you've hit that point, the propellent (...) (21 years ago, 25-Jun-03, to lugnet.space, FTX)
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(...) I was under the assumption you would accelerate after the direction change. Actually, the way this all started, spinning the ship to shoot behind you, is a bit foolish. Unless in a little fighter, there should be guns all around, like a modern (...) (21 years ago, 26-Jun-03, to lugnet.space, FTX)
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(...) The Hyperion (URL) lists> at about 1200 meters. Assuming the center of rotation is the exact center of the vessel, you're swinging 600 meters of steel around the point of rotation, and that's the critical point (after all, you want to make (...) (21 years ago, 26-Jun-03, to lugnet.space, FTX)
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(...) Not at all. In atmospheric fighter combat, if I drop in on your six, you've got to shake me long enough to swing around and point your forward-facing guns at me before you can shoot back because you can't fly backwards. Thus, whoever gets (...) (21 years ago, 26-Jun-03, to lugnet.space, FTX)
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(...) While everyone already pointed out that Babylon 5 is the best mainstream sci-fi at actually obeying physics in space, I would like to point out a few additions to the above statement. The Star Trek "science advisor" has an Art degree. Half of (...) (21 years ago, 26-Jun-03, to lugnet.space, FTX)
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(...) -off subject- Not to burst anything, but I think the Hyperion is far less then 1200 meters, due to comparison with the Nova and Omega Destroyers. The Destroyers are 1717 meters long. B5tech.com lists the Hyperion at 1,025, which is slightly (...) (21 years ago, 26-Jun-03, to lugnet.space, FTX)
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(...) Rick, I would have to agree with what happens on B5. Those crazy physics consultants .....always taking real physics into account! :] We're not talking about a Cooper Mini or anything. Something that big simply cannot turn on a dime (slow (...) (21 years ago, 26-Jun-03, to lugnet.space)
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(...) No, if you use simple conservation of momentum, at subrelatavistic speeds, you can still get a modest boost with a propellant speed of 2 mph. Your speed increase is propellant weight x 2 mph / remaining vehicle weight. since total momentem has (...) (21 years ago, 26-Jun-03, to lugnet.space, FTX)
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(...) Yup, but also note that a propellant exhaust speed of 2 mph is the rough equivalant of having the crew throw things out the back hatch. :) James (21 years ago, 26-Jun-03, to lugnet.space, FTX)
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(...) I think you may need to look into relativistic reference frames... the exit velocity is w.r.t. the vehicle, not where it is traveling or what its current velocity is... the upper limit on vehicle velocity achievable with a fuel of a given (...) (21 years ago, 26-Jun-03, to lugnet.space)
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(...) Correct. (...) Yes, *something* does. It's not light though, since if it was light, they would spin in the black direction (with the black side leading the rotation).... (the momentum imparted to something perfectly reflecting is twice that of (...) (21 years ago, 26-Jun-03, to lugnet.space, FTX)
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(...) That webpage was the only source I could think of that listed the Hyperion's length, but I was a bit doubtful of the total accuracy of everything. I kinda remember a TNG ep where it was mentioned that the Romulan Warbird (D'deridex) was about (...) (21 years ago, 27-Jun-03, to lugnet.space, FTX)
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(...) Actually the ship in SW2:AOTC could not have used light for propulsion. As the ship must have used hyperspace speeds to reach Palpatine so quickly we must conclude that whatever was used was far beyond any real science explanation. Just to put (...) (21 years ago, 27-Jun-03, to lugnet.space, FTX)
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