Hello,
I’m currently debating between a puncher and a catapult for this year’s game. One advantage of the linear puncher is its ability to change its firing angle. Would it be possible to change the angle of the arc on a catapult? From what I know, it would seem like you would have to move the hard stop as well as use pneumatics to change the slip gear. Is there a simpler way to create an arc changer for a catapult?
I won’t say it is an easier way. But I know last season, my teams managed to make some adjustment to the usual catapult plus using programming to have that additional pull back for different arc.
Looking at their performance during worlds, think I would say it is pretty effective.
The arc of a catapult can be changed in multiple ways
The most obvious method is using piston or band boosting, which were used on Spin Up catas to shoot from cross court into the goals. Essentially, the extra power from the piston or the extra bands allows for more energy to be input into the system, allowing for a much higher arc when tuned correctly. The main downsides of these methods thought are that piston boosting is heavily reliant on psi (though it can be optimized) while band boosting doesnt allow you to switch arcs mid match.
The second way of changing the arc of a catapult is doing a slapper/catapult hybrid like 229V Ace, and their slapper acts like a puncher and has a low arc, while their cata has a higher arc.
What do you mean? Could you go into more depth on what you guys did.
I see. Just a question but if more energy is being outputted into the system, wouldn’t that only affect the final velocity of the projectile, not the angle?
I can’t… simply because it was done by my students. So I can only try to describe what I observed. Only they can give a detailed explanation 
But basically they programmed a preset button to crank the catapult further down for a greater range.
But you are right, it is just giving the catapult more energy rather than changing the angle.
Or you can also try using pneumatics to push the c-channel (that the catapult mounted on) further up or down… to change the angle.
You could also try something like here, but for a catapult instead of a puncher. This would have the same effect as meng stated, but without using pneumatics or an extra motor.
So, just an update. I decided to take a look 299V and what they were doing. I found their idea of a slapper and catapult combination was pretty cool so I used that as inspiration to model a prototype.
On that note, would there be a way to make this more compact?
Certainly; it’s up to you to figure that out within the constraints of your robot.
I’ll give you a hint though: do the vertical pieces really need to be vertical like that? Does it need to be that long at all?
Actually, that does make me think. It doesn’t have to necessary be necessarily vertical, but an angle to be more compact. I was also thinking that instead of having standoffs, we could replace it with a piston, so that the longer arc can be activated only when necessary.
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