# Flywheel Issue

So we’ve built this flywheel using v5 that’s geared 1:21 but although it shoots the ball pretty fast and far, it doesn’t shoot them high enough to hit the top flags. I know that the angle we adjusted, about 60 degrees, should allow it to reach pretty high. Does anyone have ideas what this problem could be coming from?

There are a variety of factors at play here:

1. Pure speed: I think the slowest flywheel I’ve seen so far this season that can still hit both flags from a good distance is 1:15 on high-speed motors. This equates to 2400rpm, whereas your 1:21 gearing (assuming on torque motors) only gets to 2100rpm.

2. Flywheel compression: you may initially think that the ball should make minimal contact with the flywheel and the curved piece behind it in order to minimize friction, but in reality, more compression (within reason) is better. If you run the ball through the flywheel by hand, you should feel a substantial amount of compression but still be able to run it through without getting it stuck. This is (in my opinion) even more important than pure speed, as when I made my first flywheel this season it shot about 50% further when I optimized its compression.

While those are the biggest factors that affect speed in one direction, do be wary that setting your flywheel at a 60 degree angle might not be the best idea. Based on your description it seems like you mean 60 degrees in terms of making it shoot higher, which by convention is really 30 degrees from the horizontal. This does allow the ball to travel higher at a close distance, but keep in mind that the steeper your angle is, the less horizontal force you give the ball. This could potentially cause issues with the flywheel not having enough force to actually flip the flag, despite hitting it.

Hey there! This problem is pretty common, there are a few areas that might be the issue.

1.) Friction. If there’s too much friction in the gear train, your flywheel will spin too slowly. Try removing the motors and “free spinning” the whole assembly. If it doesn’t spin for at least 10 seconds, figure out where the friction is coming from and reduce it.

2.) Rotational inertia. The more rotational inertia you have on your flywheel (aka the heavier it is and the larger the wheels are) the less it will slow down when shooting the ball. Be sure to add several wheels in a row on the flywheel shaft to increase the rotational inertia of your launcher.

3.) Grip. In order to shoot the farthest, you want your flywheel to have as much grip as possible. Try adding rubber bands to the actual wheel and foam or friction matt to the hood.

4.) Compression. This one is much more subtle, but it is also the biggest cause for flywheel problems. Too low a compression rate results in not enough friction between the wheel and the hood, making the ball slip and undershoot. Too much compression puts unnecessary pressure on the wheel and slows it down while launching, again causing the launcher to undershoot. Since the compression rate will depend on the speed, size, grip, and moment of inertia of your flywheel, there’s no magic formula. Just experiment with different compression rates and see if you can maximize your distance.

If the problem persists, be sure to post some pictures of the launcher and we’ll take a look. It’s always easier to trouble shoot if we know what we’re working with

Good luck!

Thanks for the feedback! Sorry I wasn’t too clear about this before but I do believe that compression and grip is not the issue with our flywheel nor is it’s speed as our motor is spinning on 200rpm with the gear ratio. Might be friction though. Attached are some pictures.

Sure!

It looks like your gearbox is quite pretty well and you have rubber bands and friction matt as appropriate, I’d recommend testing the v5 motor to see its rpm (if there’s a lot of friction it’ll be way under 200 rpm, otherwise it should be close) and otherwise just tuning the compression rate. Nice job on the build quality of the whole thing, looks super clean!