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Science fiction inventor with another science fiction question

  1. Oct 29, 2012 #1
    I am trying to come up with an idea of something tougher than steel for a starship hull and thought there might be a possibility of using a form of rock over an exoskeletal steel frame. I really am ignorant of temperature tolerences of any form of rock but am slightly aware of ceramics heat tolerances but don't know what ceramic is chemically.
     
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  3. Oct 29, 2012 #2

    phinds

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    The military uses depleted uranium for anti-tank shells ... stuff cuts through thick steel armor with no problem.

    Not a great choice for a ship though, because it's HEAVY.

    Probably best to just make up your own version of unobtanium.
     
  4. Oct 29, 2012 #3

    Simon Bridge

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    You know you can look this stuff up right? i.e.
    A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous (e.g., a glass). Because most common ceramics are crystalline, the definition of ceramic is often restricted to inorganic crystalline materials, as opposed to the noncrystalline glasses.
    http://en.wikipedia.org/wiki/Ceramic
    i.e. "ceramic" is a class of substances. Members of the class will have differing properties.

    Do you just want something to plausibly withstand high temperatures?
    Your story requirements will be important - eg. will the specific composition of the hull be important to the story you are telling?

    BTW: Is it possible to have anything over an exosceleton.
     
  5. Oct 30, 2012 #4

    Evo

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    A stylish jacket?
     
  6. Oct 30, 2012 #5
    I was thinking about a steel frame with rebar and some form of high temperature concrete. Sure I could just make my own unobtanium but I want something realistic because it is hard sci-fi,meaning based on real science. Does anyone know if there is a form of high temperature concrete?
     
  7. Oct 30, 2012 #6

    Ryan_m_b

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    Why do you want such a strong hull out of interest? Remember that the more mass you have the slower the thrust this craft is going to have and the slower top speed so concrete really isn't ideal. How about something like aerogel (can be as strong as steel and nearly light as air) with some sort of modification to make it air tight?
     
  8. Oct 30, 2012 #7

    phinds

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    Evo, you crack me up. :smile:
     
  9. Oct 31, 2012 #8

    Simon Bridge

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    <withering look reserved for people who come up with something I should have thought of>
    Hmmm... A coat of paint? Form-fitting lycra?
     
  10. Nov 1, 2012 #9

    Borek

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    Pitch black, with some sequins. Would make a great camouflage.
     
  11. Nov 1, 2012 #10

    Simon Bridge

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    Or spell something out in twinkley LEDs and start a round of cover-ups by astronomers.
     
  12. Nov 2, 2012 #11
    actually the reason I want something with a strong hull is so I can Tank the Enterprise, or the imperial star destroyer, or the Halo ship "Pillar of Autumn", or the Battlestar galactica, or just any other powerful spaceship in science fiction.
     
  13. Nov 2, 2012 #12

    Ryan_m_b

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    But those all have the advantage of being soft science fiction creations. They're all capable of impossible feats via heavy dollops of unobtanium.
     
  14. Nov 2, 2012 #13

    Simon Bridge

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    ... and most of those have met their Waterloo's within their own Universes anyway.
    I believe the original question has been answered?
     
  15. Nov 2, 2012 #14

    Ryan_m_b

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    Aha I thought I remembered a thread like this before:
    https://www.physicsforums.com/showthread.php?t=620530

    As was stated in that thread if you make a massive ship it's just going to be interminably slow with incredibly low thrust and low cruising velocity. Whilst it might be fun ultimately you can't win against soft science fiction designs. None of the ships you mentioned are constrained by even basic Newtonian physics.
     
  16. Nov 2, 2012 #15
    I suggest you head to the nearest asteroid farm and pick up a few. Use them to completely surround the ship. It serves as camouflage and a huge chunk of mass that acts as armor
     
  17. Nov 2, 2012 #16

    Ryan_m_b

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    I don't think camouflage in space could ever really be that effective (read in full) and whilst a few hundred metres of rock would certainly be good protection there are a couple of practical downsides:
    • The mass of the vessel is so huge that even with speculative propulsion systems like fusion drives thrust is going to be tiny and cruising velocity pitiful (see also the ideal rocket equation)
    • Those hundreds of metres of rock are going to have to have openings allow access in and out, to deploy sensors/weapons/thrusters etc. Said opening points could easily be hit rendering the craft less of a Cool Space Battleship and more of a caved in underground bunker in space.
     
  18. Nov 2, 2012 #17

    Ryan_m_b

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    Just out of interest I just googled whether or not there is any established canon for these ships. Turns out that the Star Wars franchise has an insane amount of background detail in it along with an (unsurprisingly) dedicated fanbase. According to "wookeepedia" a star destroyer has a powerplant capable of putting out over 7 yottawatts, which is about 2% of the Sun's solar output. According to this fansite which uses a pedantic amount of detail from the films a single shot from such a ship puts out at least 250 terrajoules of energy, which is enough to power the entire world for about 15 seconds. Lastly according to another page on said fansite a star destroyer has shields that can withstand 100 exajoules of energy, which if we could store all the power produced by human civilisation and release it at once as a weapon would take us about two months to save up for.

    This is what I mean when I say that it's mostly pointless to try and come up with hard science fiction scenarios/encounters with soft science fictional creations. They have the advantage of being able to write as many zeros as they like onto their characteristics and justify it with willing suspension of disbelief.
     
  19. Dec 3, 2012 #18
    One thing i dont think has been mentioned Carbon properly made it is the hardest substance on earth. It is also a very weak substance if need be and very common.
    Another thing is even if it is heavy the ship is in space so weight matters little and the mass probably wont be a huge deal just kinda slow at turning and should avoid landing on planets, most space ships should since it would take a large amount of energy landing and taking off not to mention planets with atmospheres which get terribly hot
     
  20. Dec 3, 2012 #19

    Simon Bridge

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    "properly made carbon"? "if need be"?

    afaik the "proper" way to make carbon is with protons, neutrons, and electrons...

    You mean that some forms of pure carbon are very hard and some quite soft as in diamond or graphite? Maybe "hardest" in connection with "made properly" is a reference to carbon nanotubes? (Though the hardest natural substance on Earth may be wurtzite boron nitride...)

    A high mass will mean it needs more energy (=fuel) for the same delta-vee. It can, and usually does, mean a higher moment of inertia (re: "kinda slow at turning") - but the details depend on the mass distribution. You are certainly correct to distinguish between mass and weight.

    Since the proposed ship considered to be using a lot of mass for shielding against soft sci-fi warships ... landing, or crashing, on a planet is not likely to bother it much :D
     
  21. Jan 9, 2013 #20
    But would aerogel hold up against energy weapons. You know, I'm just asking you guys to design the ship for me rather than do my job, never mind. I'll look it up myself.
     
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