Catapult Stopper


#1

What do you suppose would be the best, most accurate way to stop a catapult? A physical stopper like a piece of metal? Or a winch and pulley string?


#2

I use a physical stopper connected with rubber links for my slapper. Acts as a pretty good shock absorber, if you’re worried about breaking pieces.


#3

We use a steel c-channel with foam covering the area where the arm strikes the metal. Make sure you reinforce everything really well, as it will bend over time depending on how strong your catapult is.


#4

I just used a steel c-channel on my tower. no padding or shock absorption or anything. worked decently well.


#5

After a couple of variations, I decided to use the edge of a steel C-channel braced with bearing flats and a couple of aluminum rails. I also tried just an offset (bent like crazy), and an offset wrapped in tubing (worked too well and absorbed too much). I wouldn’t want to use a string for fear of it snapping, but I do like the idea.

Picture

image
I’ve since added that steel C-channel underneath those standoffs and it worked pretty well. This is an older picture and probably the best one I have.


#6

I used 4 pieces of strapping underneath the arm of the catapult itself. It was built so that there were 2 on top connected to the two on the bottom at a single point of rotation that would be able to compress when the catapult was down, but when it shot, the pieces would straighten out and stop the catapult from going any farther. It’s worked very well for us.


#7

If I’m thinking of this correctly, you had pieces acting as a folding spring in compression that moved along with the catapult and stopped it at its apex? I would think that this would have the same dangers as braiding a large amount fo nylon rope to act as a stop. Did you experimente any bending problems?


#8

Nope, no bending here. It’s because the forces are pulling on it lengthwise, which is where strapping is stronger. If there was anything on the sides, it probably would’ve bent.
Here’s a photo of one of our earlier catapults (it’s the only one I had, but the mechanical stop has stayed pretty constant throughout all of our designs).
IMG_0044