Gear ratiosThis spreadsheet takes the driver diameter, and works out the driver rpm to achieve a target mph for both for the prototype and model. The next input is the top speed you want your model to achieve.
|Green - motor revs below 75% of no load speed||Yellow - motor revs between 75% and 100% of no load speed||Red - motor revs above no load speed, so not feasible.|
Frame spacingThe top part of this spreadsheet is set up for P4; for other gauges you will need to amend the initial wheel tyre back to back measurement accordingly. It works by prompting for the dimensions of all the items I can think of that may exist around the axle between the back of the wheel and the inside of the frame. If any aren't applicable, e.g. shorting strips, then put a zero in that row. The dimensions are then applied to both sides with the resulting figure being the required distance between the frames.
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