Wheel Turbulence

[maguromic]

If the rules allow it on a open wheel hill climb car, is it better to have the rear wheels closer to the body or a abut 8” away from the body. I have been told that anything closer than 6” ads to your frontal area. I want to keep the air flowing on the side of the body in the rear away from the turbulent air from the rear wheel much as possible.

[Locost47]

Unfortunately i think this is really not an easy question. The advice about spacing of the wheels is misleading as it confuses the ideas of drag coefficient and frontal area.

If you move the wheels in close to the body then they can disrupt the flow around it and accentuate its drag, which is equivalent in effect to increasing its frontal area but not the same as doing it. Moving the wheels further outboard IS increasing the frontal area but would probably reduce the drag coefficient. Which approach is better overall would depend on a range of things and could only really be determined by testing it.

From what i've seen though, Hillclimbers are usually not interested in drag because they often have an excess of power for the top speeds they're likely to reach. Unless you are actually power-limited over the courses you run on then i'd say it's not worth sacrificing the mechanical grip of a wider track for an uncertain aero benefit.

[THR]

yea make it as wide as u can as long as it still handles ok.
take the rules to the max.
like locost says the speeds are low in comparison with circuits, mechanical grip is very important.