[Gripping Pneus]

A circular test track is the best as it gives you a reading for the coefficient of friction under dynamic conditions.

You can also measure the forward thrust of the car by having it push on a bell crank to load digital scales. That will give you the c.f. too.

 

[Gripping Pneus]

Nice! That would be ideal. Any idea how practical c.f. readings compare to theoretical, esp. for plastic track like Scalextric?


I have no idea what the theoretical c.f. Is but on Ninco track with NSR ultra grips and no traction magnet I measured an apparent c.f. of 1.75

Is that with wheels spinning or a static load situation?

You can measure both depending on the power you use. I got a slightly higher reading than with the same car on the circular track because there were no bumps and track joints to upset the grip.

I suppose the ratio between the two readings is an indication of the efficiency of the chassis to cope with track irregularities - possibly a useful tuning indicator?

 

[Gripping Pneus]

And Normal force rises exponentially with speed.

To be pedantic, it rises as the square of the speed rather than exponentially methinks, but we know what you are meaning.

That downforce on a banking is certainly big. In the old days of ECRA cars with brass and piano wire chassis, we had to fit an "anti-decking rail" running from the front top edge of the motor can to a point on the chassis somewhere under the front axle. This was to prevent the chassis bending down and touching the track on the bankings. Those cars were tough as old boots and it took some force to flex them without the rail in place.