So here I am... feels good!

It's true, my body isn't made for speed or elegance - but strength. I plan to sling the 60mm massive steel balls my friend "Kugel Winnie" sent to me a while ago.

What I am currently looking at is a portable staff sling (or hoopack) that is attached to another stick (or maybe two), cockable like a trebuchet. I plan to use rubber instead of gravity (what else) to swing the staff.

The "release" fork tip can be adjusted so the angle of the shot changes.

My goal is to make a portable trebuchet that can be cocked and fired in a very short time. The outcome may be seen as a "sling robot" really, hopefully with a very repeatable mechansim that will allow some accuracy even for the untrained shooter.

What do you guys think?

Awesome video!

I want to make something much smaller, really the same size as a staff sling - but with a lock and trigger mechanism, to rule out operator errors.

That's right, the hoopak uses a slide-off release for one of the cords just like the regular staff sling. The advantage of the hoopak is that it delivers a rifle-spun release every time and so it works well with biconical ammo.

http://www.youtube.com/watch?v=3QjFam33ng8

JoergS wrote on Sep 13^th, 2012 at 7:10am:

Welcome Joerg!
Sling 60mm steel balls are perfect for crunching.

with fig 8 it's because the momentum is maintained and increases that makes it so effective.

When done properly it's a really smooth natural motion.

I tend to use a flatter rear section than most people which gives me a faster throw, albeit one that requires more strength, but puts a lot more stress on your joints. Might suit you better.
you can see in this video how the whole throw just works as one compound movement.

http://www.youtube.com/watch?v=gAQannIFnMI&feature=relmfu

The more traditional fig 8 suits longer slings, but also has the same roller coaster acceleration principles.
http://www.youtube.com/watch?feature=endscreen&v=y_KiObfGKOc&NR=1

What do the 60mm balls weigh ?

I'm guessing  a few pounds at least. With that kind of weight a sidearm or balearic sidearm style would probably be better.
The kind of stress that fig 8 places on the elbow, is pretty extreme with heavy weights.

One other thing you might want to look at is the murlin style of trebuchet. It's a lot more compact, generates more power and could possibly be configured for multiple shots.

http://www.youtube.com/watch?v=PKA2eUneyj4

Using rubber power you could lose the top tower and simply keep the wheel and the base.

Oh yeah and do you have any plans or a tutorial for the repeater pencil crossbow ?
I'd like to have a go at making one of those

For a repeater sling you defintiely want to use a 'captive pouch' design. This negates the need for the release cord to be retrieved between each throw. Resetting the pouch is almost as simple as recocking a trigger mechanism.

Thomas makes the best and is definitely the forum expert on captive pouch slings - should be links to it in the FAQ section. If not jax should have contact info (thomas is his dad

A murlin with a strong rubber....now that should be efficient and damn fast..

JoergS wrote on Sep 14^th, 2012 at 6:52am:

It has more momentum,speed and more tension on the cords as a simple apache. A fig8 has a lot more power potential than a apache throw.

timpa wrote on Sep 14^th, 2012 at 12:59pm:



Your lead may be slightly alloyed or my math might be slightly wrong, but with a 43mm diameter, a pure lead sphere should weigh 472g by my math.