[Oblarg]

One major flaw of the WCP drive calculator that you should take note of: the "max pushing force" and "max current draw" calculations both use static wheel COF instead of dynamic. This is very misleading, as if you're actually traction-limited, you'll be spinning the wheels and the static COF only matters for a moment until the wheels slip. So, if you're trying to see if your current draw in a pushing match is sustainable without tripping a breaker, the numbers they give are not correct.

I emailed them about this some years back, but it doesn't seem that they ever got around to fixing it.

OP: As for your questions, there is no one-size-fits-all answer to any of them. You have to wrap your head around the concepts behind that calculator - the tool is there to save you the effort of doing the calculations by hand, but if you don't have at least a heuristic understanding of what the calculator is doing then it's very hard to use it properly.

That said, here's my best attempt at giving a short-ish answer to each of your questions. Please, do not just read these and ignore what I said above. They are not absolute guidelines, and are meant as prompts for further thinking.

1) It depends. There are several concerns due to excessive power draw; the most pressing are browning out the roborio or tripping the main breaker, but past that you have the individual 40-amp drive breakers, and also overall battery usage (if you have a power-hungry robot this can indeed be a concern). Each of these requires separate consideration. If you are only running a 4-CIM drive, you will likely only have to worry about the drive breakers; if you are running a 6-CIM drive, the others come into play.

2) This depends on the game. A higher top speed means slower acceleration. In a field like 2016, where there was not much open running room for a robot, gearing a single-speed robot for faster than 12 fps or so (YMMV pending drive efficiency and other factors) would have likely been a waste as you'd rarely actually reach that speed (shifters can change that, though it either requires auto-shifting code or very skilled drivers to actually take advantage of them for acceleration). In a game like 2014, with a wide open field, a high top speed could be very useful.

3) "Pushing force" isn't really a value people tend to explicitly design FRC drives around - you rarely "shoot for" a specific value here. Again, as well, this depends on the context - if you're a defensive bot in a contact-heavy game (2014?), being able to push can be extremely valuable. In other contexts, it's completely unimportant. If you do decide that you need to optimize pushing ability (I've never actually done this, but I can imagine some contexts in which you might want to), the "pushing force" value on the calculator isn't really that important - you make your robot as heavy as possible, pick the traction-y-est wheels possible (within reason - I'm sure you could get fabulous pushing performance from the soft rubber BaneBots wheels, but I doubt the field crew would take kindly to the resulting rubber shavings left on the field and you'd probably have to swap every match) and then pick a gearing that will let you push constantly under those parameters without causing any power issues. This will almost certainly require a 2-speed gearbox, because the gearing that allows you to do that is likely to not be very mobile.

4) This, of course, depends on which wheel you're using - if you dig around CD with the search function you can likely find various test results for various wheels that members have done, though I seem to recall being surprised at how much the quoted values from different sources vary when I've looked. I will say that, based on toying with the calculator and comparing it to my actual experiences, .7 is a pretty reasonable guess for AndyMark HiGrip wheels and similar.

If you'd like, you can send me a PM and we can discuss more in-depth.