Different Types of Catapult Grouping

From what I’ve seen online and in other catapult-design robots, there are many different ways to group the discs when launching them. The main ones I’ve seen are standard grouping, mingo-mech, and dodo-mech. I’m sure there are more tactics out there but those are just the ones I’m curious about. Some people have said that mingo-mech is the best, but I’m not sure exactly how or why. Can anyone explain in general how each kind of grouping works and the pros-cons of each?

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Note that these are ways to achieve good/better grouping, not actual types of disc grouping. Essentially what it boils down to is the better your grouping is, the more likely you are to score 3/3 discs shot.
There are many ways to achieve this, and I recommend looking at the physics behind grouping to see what factors inherently affect grouping and what your team can do to mitigate them.

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Sorry… what is mingo and dodo (that bird?) ?

I would easily list my team as one of those that know quite fair bit about catapult, but I have no idea what are these mech. Care to explain?


A Mingo mech is where the catapult basket is on a pivot point such that the basket rotates in a manner inverse of the shot motion, which helps to cancel out the rotation of the discs and improve grouping.

I don’t know a whole lot about the dodo mech, but from what I could gather it is simply a Mingo mech with the basket banded down in a different manner.


it is similar enough that the difference is irrelevant and both options will be sufficient for grouping purposes. There are other ways to group discs and @RoboCatz is correct in suggesting you research ways to achieve said grouping.

What I don’t get it is - how are all these “mech” different from the usual catapult?

Don’t be misled and confused by those that threw in “names” to their mechanism. Instead, go by what @RoboCatz and @AliA have suggested.

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The usual catapult has the basket hard mounted to the arm of the catapult while these variations all have to do with having the basket have a range of motion independent of the catapult arm.

But I do agree that there are plenty of things to look at and analyze first with grouping, such as stop angle and other things

Take a slo-mo of the shot from the side on the highest frame setting you can afford (a decent iPhone / Android phone can do that, if yours can’t borrow a teammate’s). It will reveal to you what happens to that third disc that does not want to stay grouped with his other friends and what part of the “mech” causes it to fly out separately. For us it was a Lexan piece that would bend out and then in at the moment the discs left the basket and add an extra bit of rotation we could not see with the naked eye.

How does one find the physics behind grouping? I’ve had trouble with the standard setup for a while, and I think with some grouping mods I could nail 3 disc shots during auton. My catapult has enough power in auton config but the grouping is horrible; I can get 2/3 discs inconsistently.

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