Here is a proof of concept prototype our team made (see photos below). The idea behind an indexing catapult is that you don’t need to wait for a back-stroke like on a typical catapult. This would increase the launching rate.
The center tri-arm launch assembly rotates independently (and freely) from the geared cocking assembly. A release mechanism would hold back the tri-launch arm as the cocking assembly rotates forward stretching the rubber-bands. The cocking assembly (or release mechanism) stops the forward motion of the tri-arm launch assembly where the next ball is waiting to load.
This assembly is able to launch balls from the starting tiles into the high goal.
Sure. Here is a video, but the mechanics in the video are backwards. It’s the arm that should be stationary while the barrel rotates to load the rubber-bands.
Wow. Really cool. It would require some unique intaking system, though. How large is it right now? Looks like it is just barely within the 17.5" c-channel in that picture.
The length is maxed out to accommodate the longest lever arm possible. The width is less than 11" right now for the main body. The mechanism could go narrower than 11" without a problem.
I would love to see this concept refined past just a proof of concept. I don’t think the team has the time right now to take this concept further, they have had too many re-builds already.
This was able to shoot to the high goal. During testing & tweaking, it was able to shoot from the starting tiles over the high goal at times.
It took (12) rubber bands in this configuration to shoot to the high goal. Of course the number of rubber bands needed to shoot to the high goal will depend on the particular rubber band attachment set-up, friction, motor programming etc.
The accuracy/repeat-ability was very high, as you would expect from a catapult. Unfortunately motors were never added to the contraption, so rate of fire is still to be determined.
The rate of fire will depend on the torque/speed trade-off it takes to load the rubber bands. If rubber-band “loading” can be done quickly, then this design would have the accuracy advantages of a catapult without the handicap of waiting for a back stroke of loading a conventional catapult. Now this design is just waiting for someone to finish testing the concept
