Re-Visiting CoG

[slurp]

This is something I need to cut into the mechanics pages, just giving a little more thought to the position of the Center of Gravity. I've pictured something that's closer to the servo based mini sumo but it will apply equally to those that look like Bob Cook's Thin Man or PeterW's LowBlow.



Previously we've used the calculations to give a basic idea of frictional forces in relation to the CoG.

Using this spread sheet (google docs) you can play with the numbers a little to give you a picture of what happens if you get tipped up. I've assumed the wheel is as far back as can be and started the calcs with a 35mm radius wheel. Tilting back I've looked at the nose being 10, 20 & 30mm off the ground.

You have an effective arm radius from the scoop/nose to the wheel center, and to the CoG. My consideration was for any possible loss of traction rather than resisting over turning or having the scoop lifted.

You might note the comparison of reactions to wheelie bars, especially with larger wheels and not just co-efficients of friction for battery boxes!

Also worth a note is the marginal increase you can get when the CoG is level with the wheel center (Y2 = 0) and your getting tipped back.


I hope it give some useful food for thought....

Best regards,
Colin