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Thread: The Making of a Cannon (lab)

  1. #1 The Making of a Cannon (lab) 
    New Member
    Join Date
    May 2006
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    1
    So our class just got this "cannon lab" where we are given the choices of ethanol, methanol, and 2-propanol as fuel. The purpose is to choose the best fuel to air ratio and shoot two paper cups (taped together in the shape of a bullet) out of a tube composed of tin cans (one end open for the papercups, and one end with a hole poked in it to ignite the fuel). The measurements for fuel can be between .1 ml to 2.0 ml. I was tipped off by a class mate who had already done this lab that 1.0ml of methanol was the best, however I can't figure out how you could tell that 1.0ml would give the best results (which factors to consider, etc.). Other questions that the lab ask that I have no clue about are:
    - How will you prepare the air inside the cannon before you load it with your fuel? (only normal lab air can be used) What conditions will promote combustion?
    - What pre-ignition temperature will you use for the fuel in the ignition chamber? (Should it be cold, room temperature, or warm?) Explain how this will affect combustion.

    Any help would be GREATLY APPRECIATED!!!
    Thanks so much!!
    P.S. If this will help, the balanced combustion equation for methanol is:
    2CH(3)OH + 3O(2) --> 2CO(2) + 4H(2)O


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  3. #2  
    Forum Ph.D.
    Join Date
    Feb 2005
    Location
    Dublin, Ireland
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    well if i were doing it, id figure out how much air will be in the combustion chamber to find out how much oxygen will be avaible for combustion. excess oxygen would be best. so like 21% of that volume is oxygen. and work out from there. by working out, the most possible amout of methanol to the maxium oxygen. i think


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