# Optimizing a trebuchet

1. Nov 23, 2004

### nbnate

Can anyone give me advise on how i would optimize a trebuchet? I think i can figure out most of it except what equations should i use for the rope attached to the projectile.

2. Nov 24, 2004

### so-crates

Hmm, well this would probably due better over on the 'Mechanical Engineering' thread, but I could think of a few qualitative possibilities:

- (Obvious) Height from which you drop weight should be as high as you can make it - this is your only source of power so it sets the maximum amount of energy you can deliver to the projectile.
- Similiarly, you want as much weight as possible!
- Length of catapult arm: should be long, but not so long that you projectile has small exit speed

The rest of considerations all have to do with effiecient energy transfer from the energy of the falling weight to the projectile:

- Catapult arm should be stiff, yet lightweight
- So should the rope
- Minimal gear/belt losses - not too familiar with this area, but if you use a belt their should be a large coefficient of static friction between teh belt and the wheel

3. Nov 24, 2004

### pervect

Staff Emeritus
I would attempt to model the rope as a perfectly rigid beam, myself. This is probably not quite right of course.

There are some shareware programs out there to design trebuchets, but I've never looked at them closely, I don't think they provide much theory.

There are different forms of "optimization", but probably what you're talking about is to get the arm of the trebuchet to essentially stop dead at the end of the cycle due to the load, so that it doesn't slam into the stops. This both makes the machine more efficient, and saves wear & tear on the main beam.

4. Nov 24, 2004

### sigma

Sounds tricky?