For our catapult design, we actually took inspiration from Aaron and 7090 in order to create the same degree of rotation as the forward catapults, but backwards. It was also designed to only catapult large balls, as many times it was more useful to keep the buckyball and only fling the large ball. Our season has ended until March, but we ended up not having enough space to have the actual deflection we wanted (60 degrees), and went with something more like 80 degrees, which was not optimal. To add to that, the trajectory was not tuned, so the ball would go much, much higher than we intended. As a result, we just decided to throw pistons at the problem (we had 5 single action pistons, equivalent to 4 double actions), to solve it quickly before our last competition. It worked well, but obviously not as well as we wanted it to.
In addition if someone has a 4/4/2 (four motor drive, four lift, two intake) setup then having 4 tanks on your robot for a backwards catapult is a lot of weight. The tanks aren't light so keeping your robot as lightweight as possible with only four motors on drive is essential. But then again team 1103 in Round Up had a rock solid robot that weighed nearly 20 lbs. (I believe he said this in a video somewhere, don't quote me on it) and had only 4 high speed motors on his drive. Very impressive!
Kids can put on their engineering hats and build the Vex Robotics Catapult, which launches plastic balls up to 10 feet. It comes with more than 100 easy-connect snap pieces and two balls. Once the catapult is assembled, turn the knob to bring the bucket of the catapult however far back you want. Use the launching lever to lock the bucket into place once the bucket has reached your desired angle. You can also change the angle at which the ball will fly by adjusting the T-shaped piece in the middle. Once set up, load a ball into the catapult and press down on the lever to launch. You can also drive the catapult around on its real-rolling wheels.
Littlest Pet Shop Cruise Ship