pic: Shooter damaged a Boulder

[Tom Line]

Originally Posted by electronicsdude

I will testify that the catapult works, I will also testify that it creates one hell of an accuracy problem.

I suggest you take a look at the end of the catapult. Do some slow motion video on it - even the slow motion that a Samsung phone can shoot. We did quite a bit of testing in 2014 and found the biggest contributor to inaccuracy from a catapult is when the ball 'rolls' off the ends of the catapult as it is shooting. As a result, we put wedges on the end of the catapult to keep the ball on until the end of motion.

In addition, keep close mind of how you are powering the catapult. If you are using motors, it will be inaccurate unless you are accounting for battery voltages, motor speeds, etc. If you are using some type of spring, get a fish scale so you can measure the spring tension and make sure it is consistent. Also insure you are shooting from a hard stop to another hard stop on the motion so that the catapult follows a proscribed motion each time.

People with wheels need to worry about slip, moment of inertia, and wheel velocity and how the ball is introduced to the shooter. Catapults just offer different challenges.