# Working on interesting projects

My season has ended since I was in open and US Open has since past due to this I’ve started working on other things to help learn further about the vex system and its limitations I’m currently working on a drive that is geared by x7 (12:84) for speed using speed (200rpm) motors how many would it he estimated to need to just move the chassis weight? The chassis is purely as little metal as needed to have a functioning drive so its very light

TL:DR how many 200 rpm motors geared 1:7 would it take to move a lightweight chassis

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just to move it, could probably be done with 4.
But it would have very very slow acceleration, and would likely take many seconds to get to full speed (which would be so fast anyways I don’t see how you could even begin to control it), and it would overheat extremely fast.

if you want to get greater acceleration, try upping the motor count to 6, 8 or maybe even 10.

no matter how many motors you put on it though, it won’t have enough torque to push much of anything at all, and will likely stall very quickly and have difficulty moving around.

if you want something super fast but actually controllable and with snappy acceleration, I might suggest lowering the target speed a bit, maybe to around the 400-800 rpm range (on 4" wheels).

these speeds won’t at all be viable for a competition robot, but for a lightweight drive you just want to push the speed on, they might be more manageable than your target of 1400 rpm.

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I put some numbers into a spreadsheet I made for analyzing drivetrains and here are some of the results I got. I think that to get any reasonable acceleration you will need at least 8 motors. All calculations were done assuming that the drive was 4in and 3 kg. This is a lot of data, but all of the important values are bolded.

4 Motors:

6 Motors:

8 Motors:

10 Motors:

12 Motors:

20 Motors(Why not?):

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I came here to talk about my interesting project, but changed my mind once I saw the thread was actually about speed bots.
But yeah, try it and see. Make it easy to add or subtract motors, and use aluminum.
Here is a sketch of what a friend of mine is making. He hasn’t added the exterior motors yet, and I don’t know if he will.

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