There are three very important aspects to making a catapult. These three aspects determine how effective your catapult will be. In this article I tell about all three and give you a tip on how to get the most out of your catapult - making it a monster that will perform!

1. The axle - Add a bearing to the axle that the swing arm turns on. This will greatly reduce the friction and significantly improve the performance of your catapult. Here is a drawing that I made to show you where it goes and I have also included here a picture of a bearing. It's really a brilliant but simple thing. Bearings are in everything that turns.

A bearing. Okay, the big thing to consider is the hole in the middle. That should be about the same size as your axle. If you are building a common desktop catapult then your axle might be a 1/4 inch dowel. If so, that hole in the middle should be 1/4 inch.

This can be a little confusing when shopping for bearings. I can help. The hole in the middle is called "the bore". So, if you have a 1/4 inch axle then look for a bearing with a 1/4 inch bore. Typically you can get ten of them on amazon for around six dollars.

Below is a picture of a bearing.

Here is an affiliate link to a wide variety of bearings on Amazon: Bearings

Trivia: Did you know that Leonardo DaVinci played an important role in the development of the ball bearing? I have more about it here in my Da Vinci section

2. Change the Stop position: When the swing arm comes up it hits up, and stops against the stop. The height of this stop is important. Where it is located changes the angle that the projectile is thrown. Change the height of the stop and the angle of throw changes, which changes the distance the projectile is thrown.

So, experiment with your catapult, make temporary stops and measure the distance thrown so you can get the maximum distance.

3. The power source is very important!

You are probably using rubber bands for your catapult. You should experiment with different things -more, rubber bands, sometimes less rubber bands is better, different types too. The goal is to get the absolute fastest stroke on the throw arm. That makes all the difference.

Another suggestion; I have seen catapults that use surgical tubing rather than rubber bands. I haven't done any testing but it might be worth a try.