Catapult & Intake Prototyping

The Clawson Middle School Robostangs had several successful prototype tests this weekend, including a rubber-band intake ( and a catapult with the ability to easily shoot up to 30 feet… obviously overkill for NBN ([

The idea of the intake is fairly obvious. We originally tried using plexiglass, however the ball would constantly bind behind the table (we were testing on) and plexiglass, due to the high grip on the test balls. We tried rubber bands because of their grippy texture and their ability to form around the ball. We were extremely happy with the result.

The idea of the catapult is to simply use rubber bands that release the tension and shoot the ball… like most catapults. To hold the strength of 16 rubber bands, we used a gear ratio of ~1:19 in order to mechanically lock the arm down using pneumatics (not shown). We consistently shot to about 30 feet… clearly overkill. We are continuing to design and plan the mechanism to feed and reload the catapult.

Let us know what you think!

NOTE! *******Ensure that safety is stressed when testing these shooters… whether flywheel, catapult, etc.; these mechanisms are extremely powerful- so please use extreme caution.]( )

Intake looks good, how well does it do at picking up stacks of balls and balls at different angles?

How fast were you able to rearm the catapult after each shot?

Is the catapult ever larger that 18"^3?

The catapult seems pretty powerful, have you tried puling it back with motors and using your pneumatic release with that? How many motors do you need?

P.S. I have a couple of those balls too, if you want try to find all the typos on it, it’s actually quite funny!

Awesome catapult! Release mechanism and re-arm is an issue with the much tension. Interesting and very good work!

Nice job guys… Maybe I can post some stuff here if you don’t mind.

Here are a few videos of 1508 LancerBots choo choo catapult shot distribution testing. We have had this working since last year as a demo robot for the school fair to raise money. Made a few mods for the new game and works fine. It has a single motor choo choo reset that does the job and a state machine coded software. Right now the reset time is about 3 seconds with 7:1 gearing. Catapult has shock absorbing mechanism to minimize recoil.