These results above from testing on the NSW track have some significant implications.
Firstly: The low coefficient of friction for the acetal wheel with no tyre fitted suggests
that on many cars wheel slip could be a problem for a significant portion of the race. The
use of a tyre for Sun levels above about 30% is indicated. Do ensure you check this for
your car if you gain a place at the National Event.
Secondly: The low coefficient of friction for the acetal wheel with no tyre fitted suggests
that having steering may not be quite as important on this track as previously thought.
The low friction coefficient will reduce the losses incurred in dragging a fixed wheel
around the corner making the energy loss due to fixed non steering wheels much lower
than on a painted track.
NOTE: The tyre used in testing was a standard 1/16 inch section “O” ring fitted into a
groove 0.050 inch deep.
While it is all very well to know the coefficient of friction of the NSW track how can you
test your car before actually getting to the track. In order to solve this problem, I have
conducted testing using the same car ie. Syndal South Primary car Scorpion.
Tests were conducted in exactly the same way and using the same equipment as was used
for the on track tests. Many different surfaces were tested in an attempt to find a common
surface that would give a similar friction coefficient to that obtained on the NSW track.
Eventually a surface that gave exactly the same results was discovered. Luckily it is a
very common surface which is available to everyone.
It turned out to be a glass table top, consequently any glass top table or indeed any sheet
of glass can be used to test wheel grip expected on the NSW track. Be very careful these
results are for a plastic wheel constructed from acetal (Delrin) tested with and without an
“O” ring tyre.
These results are only accurate for this specific material and configuration.
APPENDIX Q:
COMMENTS ON SOLAR PANEL CRACKING
Over the past few years it has become apparent that some types of solar panels have a far
greater tendency to cell cracking than others.
This year at the 2011 Australian-International Model solar Challenge during panel power
testing we observed a significant number of car panels exhibiting cell cracking, (at least
11 of the 32 panels tested) some with very significant cracks. In general the competitors
were not aware of the cell cracking in their panel.