Maximizing Efficiency of 2-Ball Catapult


#1

We plan on making a two ball catapult and already have a few prototypes but I’ve seen videos such as 240p’s catapult that only needs about 4 rubber band to shoot far enough. Our best prototype had around 10 and the motors could barely pull it back. Thank you in advance and any other catapult tips not related to the original rubber question will be appreciated since we started last year and weren’t around for nbn.


#2

What gear ratio are you using?
The gear ratio will affect how many rubber bands you can spammed.

But you don’t really need that many rubber bands, I don’t remember how my guys are using, but i would say it is 4 rubber band sounds right.


#3

But just stating the rubber bands isn’t sufficient, right? Where are they attached? Are they wrapped around and to the far side or just straight to the catapult from one side? Are they 32s or 64s? Are you seeing up your rubber bands the same way they’re set up in that video?

@meng is right about the gear ratio. You can change the internal ratio the motors have or change the ratio externally or both.


#4

It isn’t all that easy to make, but some robots intake and shoot from the same direction. This makes driving a lot easier.
Not to plug my own region or anything, but here’s a link of the comp we had earlier today, where a front loading catapult (5588C) won as the first seed pick.


You can see them in the Finals at 6:01:27 and quarterfinals at 5:18:19

#5

Try not to overstretch your bands. I find that an increased number of bands spanning a shorter distance translates to more power when compared to stretching them really far.

You can achieve this by not hooking your bands all the way to the end of the catapult, and instead putting them on the arm closer to the vertex where it moves. I would stretch pictures of one if my prototypes, but there’s enough else wrong in it that I don’t want to supply false information.

For a point of reference, I have 6, (3per side) but could probably change placement and tone it down to 4.


#6

Hi our team had a working double catapult and the best advice I can give you is to have a long arm for the catapult, this helps a lot as our team found out. Best of luck