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  1. Mallory
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    Mallory Mallegory. Contributor

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    Steam Powered Cannons or Equally-Simple Equivalent

    Discussion in 'Plot Development' started by Mallory, Jul 31, 2011.

    I've been doing a bit of research for my book because I want to use steam-powered cannons--or something equally simple for the same type of purpose-- for a battle. The small, scattered communities who live far away from the urban area have really limited resources when it comes to means for sophisticated military defense, so wouldn't have anything too complex, and steam cannons seem pretty simple (by contrast, the urban region has all sorts of high tech futuristic modern stuff, especially for Orwellian purposes). I did a bit of research and found that they were tried at one point in history, but didn't work well. Can anyone who knows about science explain why they wouldn't have worked, and how they might have been altered to work better?

    It doesn't HAVE to be steam-cannons per sae, but like I said, the people using them have limited military technology, although are savvy at things like digging wells and making other types of weapons...so I doubt they'd have the means to make a bomb or anything...(plus I'm too paranoid to type "how to make a bomb" in Google, I don't want the feds storming my house :p )

    Any tips? Haha I don't know much about weaponry of this kind, but would like to.
     
  2. Steerpike
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    Steerpike Felis amatus Supporter Contributor

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    Check this out:

    http://web.mit.edu/2.009/www/experiments/steamCannon/ArchimedesSteamCannon.html

    Problem with old steam cannons, at least in part as I understand it, is you simply can't get water into the system fast enough to create enough steam to launch the projectile. I've read suggestions that superheating a volume of water under pressure, then releasing the pressure, will generate a tremendous force with the expansion of steam. Part of this probably comes down to whether in your world they have the technology to do that.
     
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  3. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Using steam as a propelling force instead of something like gunpowder is a huge technical problem. What you want to do is create a huge increase in gas volume in a matter of tens of milliseconds. Assuming you begin with liquid water just below the boiling point,You must provide 2260 joules of energy for every gram of water to be converted to steam. What is the source of that heat, and how do you transfer it into the water in milliseconds?

    The alternative, of course is to have a pressure boiler to build up a good head of steam. and release it into the firing chamber through a valve capable of opening in the same few milliseconds. The boiler chamber must have a volume many times larger than the firing chamber plus the barrel so there is not to great a pressure drop before the projectile leaves the barrel.

    It seems a very innefficient means of launching a projectile.
     
  4. minstrel
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    minstrel Leader of the Insquirrelgency Staff Supporter Contributor

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    Forget steam cannons. Just use gunpowder. Gunpowder isn't new; it's an ancient invention, very old technology. Coming up with a cannon strong enough to stand the bang was a bigger leap.

    If your small communities don't have the resources to make gunpowder, then I'd recommend that you look into the trebuchet. Wiki it - it will do what a steam cannon should do, but better, and takes less technology.

    Just a suggestion. :)
     
  5. Mallory
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    Mallory Mallegory. Contributor

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    What does having gunpowder on hand consist of? They might have the resources necessary.

    thanks to all, and +rep. If it didn't let me rep you this time then I promise I will after I spread more around.

    steam info was very helpful, I owe you guys. :) will definitely use what you've told me.
     
  6. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Traditional gunpowder is 75% (by weight) potassium nitrate, 15% carbon (typically charcoal), and 10% sulfur, all as fine powders blended together. The Potassium nitrate is the oxidant, the carbon the fuel, and the sulfur serves both as a fuel and lowers the combustion point of the mixture. Other oxidants and fuels can be used as well, but they will affect the stability or the ignition properties of the product.

    It is self-contained. Once an ignition source is supplied, it does not require either air or additional fuel to combust/explode.

    There are two terms that are commonly confused. An explosion is any exothermic reaction characterised by a rapid, high energy increase in volume. A detonation, however, is an explosion for which the pressure front exceeds the speed of sound.
     
  7. Mallory
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    Mallory Mallegory. Contributor

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    Thanks! That's really helpful. :D
     
  8. Melzaar the Almighty
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    Melzaar the Almighty Contributing Member Contributor

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    I was going to suggest a trebuchet or catapults too - better to go with tried and tested things. A burning rock thrown by one of those will still create a fair bit of damage, even if it isn't particularly new and innovative. However, gunpowder doesn't seem too hard to make - I've read about all sorts of disgusting things people did to collect the chemicals, since they can be broken down from, eh, bodily waste. As long as the knowledge is there your people should be able to find a way to make it :)
     
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  9. Mallory
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    Mallory Mallegory. Contributor

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    Flaming catapults! :D
     
  10. Seye
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    All you have to do is make those steam powered canons plausible.

    There was a canadian inventor who made a canon which could launch a satellite into orbit(or send inter continental missiles). Nobody believed until then that it could be done. (Actually I am unsure if he did fire one off because issues came about and he fled Bermuda :) )

    What he did to gain velocity was use an very long barrel with gradient values along the inside. The initial burst was fired but as the projectile passed by a valve, it would jet out an explosion to hurry the missile along.
    Maybe the fuel your characters are burning, burns hotter, faster, or maybe, because your world still depends on steam, you just know how to manage that captured force better.

    Make your world believable.

    A lot of interesting views giving from the above.
     
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