Flywheel in change up?

So this year we are trying something weird, we want to use a flywheel for long range shots into the goals. With our current robot we are running a 1800 rpm 4 inch flywheel, and it shoots the balls into the goal about 1 tile away. We want to improve this by quite a lot, by using 3000 rpm. Do you think 1 V5 motor would be able to handle this? I know that some teams used 1 motor 3000 rpm motors for their flywheels in turning point, but change up is a lot different to turning point. The flywheel is made of 2 84 tooth gears, so it’s relatively light. There is some sticky rubber back foam and rubber bands on top.

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Here is an image for reference: image

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It’s hard to say. Personally given the weight and size of these change up balls I don’t see them getting launched farther than one or two tiles with any precision. I’d say test it yourself and see how it goes. One suggestion I can give is to put more mass on your flywheel. More mass = more momentum so when the ball compresses against the flywheel and gets launched the flywheel decelerates less. Using just two 84 tooth gears might make the flywheel just stall out when it tries to shoot.


The problem is, our motor struggles to maintain that 1800 rpm speed consistently, why aren’t we able to get anywhere the rpm of their flywheels? It struggles at those speeds. It takes roughly 1.5 seconds to rev up the intakes.

you can definitely do it, but you really shouldn’t because your robot will suck at close range cycle speed, and that’s whats really important.


I would say while this is a really cool concept. It is just unrealistic. I would say you can test it in your free time but for know make a robot that can just do goals right up next to them.



you could create a compression mechanism that made the balls smaller so they would be easier to shoot


theoretically you could use ratchets to have a 2 speed launcher with one motor, but I don’t really see any reason why it would be remotely worth it. This game just isn’t meant for a shooting robot.

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Although if you were to shoot long range I think a form of catapult would be more effective than a flywheel or puncher

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Catapults are historically quite inaccurate. I do not think this would be a good idea.

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trebuchet Intensifies


he could have it so you can switch how fats the motor spins using a program to increase accuracy at close range.

if you use code to slow down a 5000 rpm flywheels to the 600-1000 rpm close range speed, that flywheel won’t have the torque needed to spit out a ball. When you ramp the speed of a motor down with code, you don’t gain torque, you just lose speed. (you lose a bit of torque too I think, but mostly its a speed loss)


It should be a proportional torque loss, no? I thought if they run at 50% POWER they would both decrease, but I could be wrong

you lose efficiency, so in turn you do lose some torque yeah

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I think that will only work if you change the voltage. I was thinking it would rev it up to full power and once it hits a certain speed it slows down and then repeats the cycle once it goes underneath the target value. Since v5 has the built on motor encoder things this seems reasonable.

Someone who knows more than me about v5 should probably conform or deny this.

The problem is slowing down or speeding up the flywheel in order to change the ranges very quickly.

Or you could go with a portable backboard and raise or lower that to choose short or long range.

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I can’t agree with this statement.
In fact, if you factored in the variant in tolerance of the balls, etc, catapult is very accurate, as it is almost independent on the smoothness of the balls, the compressions, and also there is no worries about whether the EPs spray the anti static on the game elements or not.

And looking at track record, catapults’ performances in worlds have not been shabby at all.


Just remember to have plenty of weight as far out as possible and 1 motor powering it.

Here’s the math:
I = k MR*R (M=mass; R=Radius); k = intertial constant; I = output force thing off fly wheel (depends on shape but let’s assume a circle)

In the end use a heavy enough fly wheel to keep a constant ish output when launching the ball and a high enough rpm to launch the ball fat. The faster the more motors you need to dedicate to it.

Off topic

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Also catapults were one of the most accurate siege machines since it was easy to tune with being able to control how high the counter weight was. Only inconsistently I can think of was whether they were shooting severed heads, flaming oil, or rocks.

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