Currently we’re using a 2 motor flywheel that’s geared 7:1. It’s quite powerful and after some testing, we found that it could shoot into the high goal from most places on the field when it’s going about 2700 rpm, and able to shoot from the furthest corner from the goal at about 3000 rpm.
Because a 5:1 gear ratio is also able to go 3000 rpm, we were wondering if it would be beneficial switch our gearing from 7:1 to 5:1. At first it seemed pretty obvious for the extra torque, but a 5:1 flywheel at 2700 rpm would be coasting much closer to the motor’s maximum rpm than a 7:1, which I assume would draw more voltage? Which would heat up the motor faster?
Recovery time to get back up to speed on the current 7:1 flywheel is about .6 seconds (using just the stock motor functions for now), so would switching to 5:1 cause a significant difference? Any thoughts would be appreciated!
I think the first thing you should test is whether or not you actually need the extra torque. To test this I recommend setting a timer for 2:30 seconds and constantly firing discs from max distance. If it overheats switching the gear ratio may be a good idea but if it doesn’t there is no reason to.
Incorrect, your flywheel should only be as fast as you need it to be. The extra torque is hugely beneficial due to the faster spin up / recovery time, which reduces your cycle time. There are also other benefits such as being able to have a more compact gearbox. If you don’t have the appropriate knowledge to answer a question, don’t answer it.
I think you should think about this the exact opposite way. If you don’t need the extra speed, why not use the extra torque? Having unnecessary torque is always better than having unnecessary speed. Let’s say that something on your robot breaks mid-match and adds friction to your flywheel. A flywheel that has the extra speed will either have much slower spin up times or will not be able to reach the speed that you wanted. A flywheel with extra torque will probably also have slower spin up times, but would be able to power through much better than the higher gear ratio. There is also the issue of overheating, which @EcstaticPilot mentioned. While 2 minutes and 30 seconds is enough to last you a match, you will have much more practice time if your flywheel is able to last longer than that. This is definitely something to consider, as only being able to practice for 3 minute intervals is not great for practice.
Maybe try adding weight to the flywheel so that it has more momentum and won’t be slowed down as much?
The problem with this is that the acceleration will be longer, would just take testing to tune everything up perfectly.
ironically a bunch of other teams and I were discussing this issue the other day. from what I understand, given the info vex has released, No, they will be drawing the same voltage assuming you reach your target RPM on both systems.