Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Engineering a machine

  1. Nov 21, 2004 #1


    User Avatar

    ok, so here it is:
    "You are to design and construct a bean bag launcher, which will launch a bag filled with dried beans, rice etc. Beanbag launchers will launch their projectiles through the ait in an attemp to have them land in a large coffee tin. The coffee tin will be mounted at the top of a 1.0 m long 2x4 with the open end pointing upwards. Launchers must starts 6.0 m away from the coffe tin and are required to move a minimum distance of 1.0 m before they launch their projectiles.

    the trick is that i'm not allowed to use compressed gases or wires or electric motors or anything. the method for first propelling the object and second launching a bean bag from that object must be mechanical. i've been thinking something about elastics to move the wheels to start the thing ... and some sort of trebuchet catapult type thing to launch it ... but i can't figure out exactly how one would trigger the other and exactly a good way of making it all happen.

    anyway, that's where i need help. any good ideas would be appreciated. i'm not asking you guys to put lots of effort into replying; just if you have any ideas off the top of your head to get me started i'd really like that.

    thanks! :smile:
  2. jcsd
  3. Nov 22, 2004 #2


    User Avatar
    Science Advisor

    Sounds like a good challenge.

    To activate some simple mechanical linkage would easily do the trick. A camshaft/eccentric part of a shaft could fire, maybe a crankshaft too. Both could be on a jackshaft turning at a slower RPM than the wheel axle.

    But a string wrapped around the axle that pulled the firing pin once it wound tight would be super simple once you could get it consistent!

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook