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Air Cannon School Project Firing Paper Projectile

  1. Feb 4, 2016 #1
    Hey guys building an air cannon for class that shoots a wad of paper from a normal sheet of 8.5/11 paper will be dry. Question is... Is Psi more important or CFM with this light weight projectile?
    Plan on building from PVC, can do 100psi easy.
    Plan on using a diaphragm valve with a solenoid for fast opening.
    What about using a plunger to compress the air like an air rifle?
    Barrel will be around 18", 3/4 OD PVC
    Sound good? Got any ideas? Love to hear your input :)
  2. jcsd
  3. Feb 5, 2016 #2
    What you seem to be concerned with here is muzzle velocity. (I don't know how important accuracy or other considerations are.) Safety is always a consideration as well. (No high pressure plungers, they can explode and can be a fire hazard with paper dust.)

    Pressure is only useful to get fluid (air) speed. Air volume is needed (at least for muzzle velocity) to accelerate the paper. So you need a balance. (Given the added effect a large volume of air might have in carrying the paper past the muzzle, you might want to err on the side of more volume than pressure.)

    Another consideration is gun caliber.

    So you might want to brush up on acceleration equations. Fluid dynamics would be a nice addition but may be beyond high school level. (I don't know it myself,as an electrical engineer.) But best of all would be to design a proper test plan to see what actually works. Run the tests, get numbers, and choose a final design. With foresight and good records this could serve as one or several science projects at a later date.

    To make a science project you would need to start with an hypothesis. (Ex. "Tighter muzzle fit increases [or decreases] range variability in crumpled paper projectiles.") The foresight comes in designing the test plan to collect the data you would need. Who knows, you might even publish and win an Ig Noble Prize.
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