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Projectile Launcher

  1. Nov 18, 2013 #1

    So my class is doing a projectile launcher project, in which you build a launcher and have to hit a certain target, constantly, each time. I already based mine off an air compressor. It's a copper tube attached to an air compressor. It works perfectly, but the problem is I haven't found an ammo good enough to be fired constantly (i.e: same distance each time).

    I've tried:

    1. A small Teflon ball
    Advantage: The ball is always placed at the same distance inside the cannon
    Disadvantage: The air would sometimes go around the ball, which messes up the range each time it is fired

    2. Shaved rubber stopper
    Advantage: The compressed air is concentrated on the stopper, does not go around the stopper, like the ball
    Disadvantage: The placement of the stopper inside the cannon is not constant. I can't push it all the way to the bottom because it gets stuck. The friction is also so great that it's hard for me to push the stopper in the same position each time.

    Would a Nerf gun ammo work?

    It would be greatly appreciated if you could help me out! I'm really stuck on what I should use next! All suggestions and inputs are welcomed.

    Thanks so much.
  2. jcsd
  3. Nov 18, 2013 #2


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    As with many engineering problems, it's good to look at how the problem has been solved before, and then morph those solutions into whatever fits your project requirements the best.

    So, what are the shapes and configurations of real-world projectiles? Think bow & arrow, think darts, think artillery shells, think...

    And for your project, you need the projectile to be safe, to be easy to handle and load, and to interact with your launch system consistently. You may want to iterate and modify your launch system a bit to interact more consistenly with your chosen projectile system, for example.

    I can think of a great projectile system for your launcher, and one hint word would give it away. But I think we should let you brainstorm a bit more on your own before giving too many hints. Definitely do some more reading on different kinds of launchers and artillery systems -- I bet you will find the keyword and understand right away how you can use it to make your system *very* consistent.

    Have fun, and post what you figure out! :smile:
  4. Nov 18, 2013 #3

    Simon Bridge

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    I was going to suggest ... but you are right: jackiemendez should brainstorm a bit more first.
  5. Nov 18, 2013 #4


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    Staff: Mentor

  6. Nov 19, 2013 #5
    Thanks for your suggestion but I've been on this project for a while now and I'm still clueless.

    I brainstormed for a while and this forum is my last resort! Please do help :(
  7. Nov 19, 2013 #6


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    Staff: Mentor

    What kinds of projectiles have you been researching? Where have you been doing your reading on the Internet about this? What kinds of military projectiles are there?
  8. Nov 20, 2013 #7

    Simon Bridge

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    Working on your existing design:
    Have you tried altering the inside diameter inside the tube (so it is a different diameter in different places)?
    Have you tried lubricating the inside of the tube?
    Have you tried other kinds of projectile?
    (Presumably you have not tried Nurf in all the while you've been on this project or you would not have been asking about it.)

    Your launcher design is probably closest to a cannon.
    Cannon (the gunpowder kind) rely on a rapid buildup of pressure behind the cannon-ball - they have the same problem you had with the teflon ball, but the manufacturers managed to solve it.
    Think how you load a cannon, or a musket: can that be adapted for your launcher?

    The military no longer uses balls though - what do they use? Why is that? What do they use instead?

    Before gunpowder and guns - what sort of missile weapons did the military use?
    Is there some special reason for rejecting those designs?

    Important note: the while point of this exercise is that you have to think your way through the process.
    We cannot do that for you - well we could but.......... what we can do is nudge your thinking when you go astray. Unfortunately that requires psychic powers on our part ;) You can help out by displaying you thought processes - show us how you have been thinking about the design by telling us what you have tried and how it turned out and so on.

    Don't worry, we've all been where you are: we know what it's like.
  9. Nov 21, 2013 #8
    Thank you for both your replies, I guess I'll just listen to you guys and try my best to do this on my own... I'll need a few days to figure it out and I'll probably need assistance later on, just for confirmations or questions based on my thought processes.

    I'll try my best haha
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