members with disturbed childhood: READ

So I have to build a projectile launcher for my physics class. The guidelines are that it must launch a marble/ball bearing between 5 and 10m with good accuracy. No explosives or compressed air. Anyone whip up some plans or ideas for a nice and easy launcher, one that preferably can kick all my other classmates' asses?

I don't have any plans, but you could use the bands from a slingshot to help launch the marble.

Drainpipe bazooka.

2 metres of 3 inch drain pipe, bicycle inner tube for a slingshot.Cut innertube and fix ends over one end of pipe.String from back of slingshot through pipe to a winder on the back end.Ratchet the string up until slingshot is good and tight,then take aim and cut string.

Also good for firing bamboo garden canes.

potato gun

^no compressed air or explosives^

hmm... would a slower-burning material count as an explosive, per se?

Keep in mind, if you want accuracy, you need to figure out how to spin the ball before it gets airborn. Think of like a paintball gun... I do believe they have a little rubber piece inside the barrel that spins the paintballs.

Make a good old fashion mini catapult. Those should work okay.

Take a look at the older rifle style pellet guns. They are essentially a really strong spring and plate at the base with a long barrel for accuracy. The hardest part would be figuring out how to compress the spring and hold it there until you want to release it. If built right, it could pack a pretty good punch.
:2cents:

One word.

Trebuchet.

End of discussion.

steel tube about half and inch wide,
cut off long finger of a glove,
attach glove finger to end of steel tube using heaps of duct tape.
Put marble in the glove finger and pull back.
(use longer tube for accuracy)

One word.

Trebuchet.

Damn, took the word right outta my mouth.

I built a tabletop model once... I found the plans for a full size model on-line lemme google it right quick...

Ahhhh Here we go, tennis ball trebuchet.... Have fun, post pictures

http://www.ripcord.ws/plans/plans.html

Oh yeah, no trebuchets/catapults.

I'm leaning towards a simple spring and plate system. Anyone have any ideas for holding the plate back until its time to release?

Sounds like a fun project... I don't think a trebuchet would work very well for something as light as a marble or ball bearing anyways.

Take a look at a diagram of how a firearm works... Doens't matter what kind. Take a look at how the trigger sear works to hold the firing mechanism in place (oddly enough it uses springs)... Damn though, trebuchets are fun. For the record, I use my tabletop model to launch gumdrops and marshmallows.

Throw it.

just bring a gun to school, then ask the teacher what you get for a grade while waving the gun around in the air, youll get an A.

Sounds like a fun project... I don't think a trebuchet would work very well for something as light as a marble or ball bearing anyways.
It would look inpressive but the accuracy may fall short (pun intended)
A variation on a spring loaded musket is better.