Water balloon ballista

[mechanicalbrain]

When I was younger (funny coming from a high school student ) I had a thing for medieval and roman siege weapons. Have you considered a mangonel (also called a onager). They employed woven cable to act as a spring. Very accurate. They were introduced by the Romans after the design of the balistia. A personal favorite of mine.

[Ryan M.]

Originally Posted by mechanicalbrain

When I was younger (funny coming from a high school student ) I had a thing for medieval and roman siege weapons. Have you considered a mangonel (also called a onager). They employed woven cable to act as a spring. Very accurate. They were introduced by the Romans after the design of the balistia. A personal favorite of mine.

Currently, our design does use woven cable, but it's more of a crossbow:


I'm afraid of the cables streching, so I'm hoping to change it to make the lines holding the cup the part which actually provide the force, which should mostly circumvent that problem. Any recommendations on preventing the cables from streching?

Thanks to everyone so far.

[Ian Curtis]

In case you haven't seen it, which you probably have, there is this. But it is complicated, but I've seen one in action and it went far, really far.

[Matt Leese]

Originally Posted by iCurtis

In case you haven't seen it, which you probably have, there is this. But it is complicated, but I've seen one in action and it went far, really far.

Trebuchets really aren't that complicated. I built a computer-targetted one for my senior project. They're simpler in that they don't use tension; they use a counterweight instead. The only real hard part about them is getting a proper sling design.

Matt

[mechanicalbrain]

Originally Posted by Ryan M.

I'm afraid of the cables streching, so I'm hoping to change it to make the lines holding the cup the part which actually provide the force, which should mostly circumvent that problem. Any recommendations on preventing the cables from streching?

Thanks to everyone so far.

Have you actually tested to see if your cable is stretching? I what you are using is having trouble staying taught then maybe a tighter weave. I can't think of the material but lassos (the real ones) are like cable when it comes to bending....

[wingnut1705]

You might want to try a simple catapult. For my Boy Scout troop I built a two foot tall catapult that launched a bean bag around 150 feet. I utilized two rat traps and several rubber bands. It worked really well.