V5 and Flywheels

Our team is using one V5 200 RPM motor to spin a single flywheel using two traction wheels. It’s geared at 15:1. My question for you flywheel experts is whether or not the V5 motor can withstand spinning full speed for the entire 1:45 of a match or if we should be trying to reduce motor effort between shots. Let’s assume that we have a decent build with minimal friction.

I would just use 600 RPM and a 5:1 instead of 200RPM 15:1. When we used one motor we could not survive longer than 30 seconds so we used a ratchet on the flywheel and used a series of limit switches to act as indexers. Instead of using a ratchet you could also use slew rate

Do you have a spare 600 RPM Cartridge you could send me? Because, well, ships in eight weeks…

JK. I understand what you are saying and we are trying to find some 600 RPM Cartridges. Right now we don’t seem to be having trouble while practicing but i’m concerned about during competition.

I would say that you shouldn’t run it for the full time. Sometimes you might have back to back matches, plus you will be running every other motor as hard as it can in competition. This could overheat your motors, and will most definitely cause a lot of battery drainage.

I agree just thats a lot of strain on 2 motors even for V5. My teams robot is a flywheel bot as well and we’re running a 21:1 and hitting around 5000 RPM with 4 of last years vex motors and we have no problem with start up time, not to mention I cant imagine its good for you to run them the whole match.
I’d say just assign them to a button and wind up a few seconds before you need to shoot it’ll save you battery.
Oh not to mention when your running power to multiple things it splits the power up so your drive speed will be slower if you run it the whole time.

I used a 200 RPM motor on a 15:1 ratio for my old flywheel, and it could run for exactly 4:20 non-stop (not kidding XD). I did take friction reducing measures such as drilling out axle holes and using teflon lube.

We have a 50:1 (60 to 12 tooth connected to another 60 to 12 tooth) single flywheel (tandem traction wheels + rubber bands), and we find that with a 200 RPM cartridge it refuses to go past 50 RPM. We just put in the 100 RPM cartridge to see if it’s better, but haven’t tested yet. It just slows down when the motor goes too far past 80 RPM. Not sure if it’s because of friction or sheer torque…

I would recommend keeping with your ratio. We used that for multiple competitions and never has a problem. The only times our flywheel overheated were when we were practicing for about 10 minutes. Also I highly recommend keeping your flywheel running. It is way more stressful on the motor to suddenly have to spin up to speed than to add small amounts of power to keep it at full speed. We have always kept our flywheel running at full power through the previously mentioned scenarios. Like @Ryan_26982E said, do your best to keep friction to a minimum for the most effective single motor flywheels.

run the flywheel using your program, then
while the program is still running go to the dashboard (press power button to go to run screen, then select devices, then select your flywheel motor) and monitor the power the motor is using. If it’s up near 11W then the motor will probably overheat. If it’s down at say 2-3W then you are probably ok.

I have noticed when using multiple V5 motors on a flywheel using internal velocity PID control, the motors end up slightly fighting each other because the PID is slightly off on each motor. Has anyone else experienced this issue?

I would stick to the 200 RPM flywheel with a 15:1 gear ratio. My team uses that and we hit 170 rpm on the motor with it. Keep in mind, we went through to ensure there was little to no friction, and utilized physics to our advantage. Now, I can’t say how our flywheel motor stays at this rpm, but here’s a hint (F=ma)… Maybe when we approach worlds we will reveal how we got the flywheel to spin so fast with only one motor, we can almost shoot the high flags across the field and we can hit the middle ones from the far back. Keep in mind, compression has to be perfect, even if you have a fast flywheel, the ball won’t travel if the rotational force isn’t evenly applied to the ball.

I agree with mvas8037 here. We have a very similar flywheel with the same gear ratio that can also spin for significant amounts of time and can shoot full field. He’s right. Compression is key.

Thanks for the replies. We’ve been happy with our gear ratios and the power we are getting on shots. With an eye towards reducing friction and the use of lithium grease our wheel seems to spin rather freely. I think trying to find the exact right compression is key to the shot and the motor stress.

@jpearman How about 8 watts on overheating? Double 5” traction wheels on a ratchet geared 11.67:1 spun by single 200 rpm consistently delivering 180 rpm on motor and at least 2100 rpm on flywheel. Considering compound gearing, we really expected a reduction in efficiency. Once spun up, it does not appear the motor is doing much work. We sometimes think the wheel is moving faster than the motor.