Roller and Catapult

A Roller and a Catapult, who is better and why?
Just a student with a question… Thanks for answering!!

Whats a roller?
Which type of catapult?

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For a shooter

Simple answer is a flywheel because a catapult would be too slow to launch 5 balls one after another.


Then launch all 5 at the same time. :thinking: :thinking: :thinking: :thinking: :thinking:


Fair enough my guy lol

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Ah. I’m assuming the “roller” is a single wheel shooter, like many FRC bots have.
I’d say the best wheeled shooter is better than the best catapult. Like Alex said:

In personal experience with a catapult on a robot, it is also harder to be consistent when flinging balls. (Granted that was with the 2014 yoga ball)

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*Speaking from my experience in VRC here: *

Catapults shooting multiple balls at one is difficult because the distance between the fulcrum and the ball drastically changes the flight path of the ball. If you wanted to run a side by side ball placement, you’d have to go wide robot. As for accuracy I haven’t had trouble but the balls and overall scale of the game was drastically different. Our target was about 2x the height and width of the ball and relied on hitting any part of the target not sending a ball inside the target.

Single ball catapult is just too slow compared to flywheel design.

Here’s a thread which might help you & your teams.

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Isn’t this the exact opposite experience of teams in 2016? And 16 in 2012?

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This is generally regarded as the opposite of conventional wisdom. A catapult does not have to deal with variations in foam density, skin surface stickiness, compression, etc. A wheeled shooter has to deal with all of this.

That said, getting a catapult rate of fire to be competitive with a wheeled shooter is fairly difficult.


Not at all. Teams in 2016 with wheeled shooters were often considerably more consistent than those with catapults or similar. IIRC, the 16 Bomb Squad robot in 2012 had an intake that stacked three balls up side-by side and shot them with wheels, and did quite well. The basketballs of 2012 were a bit sticky, but had some texture which limited it somewhat. In any case, not as sticky as I understand the power cell to be, so the 16 in 2012 stackup may not work as well this year.

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People here are quick to dis the catapult (or I prefer, dog-a-pult), but in fact they do have some advantages.

yes, unfortunately they are harder to load quickly and accurately.

I’m pretty sure that spin on the power cells caused by wheeled shooters will cause more shots that hit the edge of the exhaust port to miss three points (but still be two) than it will make some go in.

A dog-a-pult doesn’t spin the ball. I mean power cell.

A pneumatic dog-a-pult doesn’t have the disadvantage of using up it’s energy with every shot because it’s energy is stored in a tank nearby.

Any pneumatic shot is more likely to be more precise because the energy available is exactly the same as the previous shot as long as you have 60 psi.

It’s the association with cats that causes you all to bias against it.


No, it was a catapult. The intake loaded 3 balls.


There were many, many top tier robots that performed accurately with catapults. 195, 118, 148 immediately come to mind.

Ironically, this is probably the most notable example of a catapult shooter in a “wheeled shooter game”. 16 was famous for their surgical tubing catapults for awhile.

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Back to the “in my personal experience” part, we only did a catapult in 2014, and while we made most every shot, there were always difficulties getting that large ball into the same exact position in the “basket” of the catapult.


wheeled shooters were often considerably more consistent than those with catapults or similar

Team 2877 (LigerBots), begs to differ. We had pneumatic catapult shooters in 2014 and 2016, and they were extremely consistent. Take a look at all of our shots at BattleCry 2016: We really never miss, aside from mechanical failure or being bumped during the shot. More consistent than 195.

However, much as we love our pneumatic catapult shooters, we’re not doing one this year. Too slow. It’s really best for games that only allow one ball at a time – like 2014 and 2016.

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