Anytime JET wants to chime in on tire issues or anything else I'll be happy to read it. However, we can still think and research in the absence of JET.
Energy loss (RR) isn't about how much tread you have in contact with the ground. It's about how much rubber you have, the material properties, how much it's stretched, and how many times a second.
So let's assume a cambered tire gets rid of some footprint area. If the camber is now deflecting some portions more and some less, it could be a wash.
I'll be honest though I don't have much feel for representative behavior in this area.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.
Comparing with a roller-bearing, in a perfect rolling contact, with no slipping present, the resistance comes from the hysteresis in the material itself, the difference between the energy it takes to elastically deform an object and what is returned when the material re-takes it shape, like a valve-spring. This difference in energy is converted into heat in said object.
For a tyre, this should be pretty much regardless of camber I think, either more deflection over a smaller patch or vice versa?
Micro-slip between rubber and road is a different matter however, perhaps a smaller contact-patch could help there?
OT:
In case of a roller bearing, much of the energy is lost through viscous resistance in the lubricant, why a wider bearing loses more.
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My opinion, based on graphs that I remember but can no longer locate, is that the effect is probably tire and condition dependent. IIRC, in a graph of camber vs. rolling resistance at different loads, there were typically local minimums, but they were different at different loads. And they were biased to one side (+1 degree had lower rolling resistance than -1 degree), possibly compensating for some plysteer or conicity of the tested tire.
I don't think it would affect much, would it? I don't know exactly, but when NASCAR races on ovals, don't they run extreme negative cambers on the outside tyre and positive camber on the inside tyre JT? I don't know though.
raymondu999 wrote:I don't think it would affect much, would it? I don't know exactly, but when NASCAR races on ovals, don't they run extreme negative cambers on the outside tyre and positive camber on the inside tyre JT? I don't know though.
Correct on direction of camber. Not sure what you're getting at though.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.
timbo wrote:I always felt camber is used to aid cornering by providing bigger contact patch in roll.
Yep...That's the reason for the short track settings that were mentioned. In the corner that tire that is leaning way over on the straight, is standing straight up mid corner.
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raymondu999 wrote:My point being straight-line speed is also very crucial on ovals, is it not?
Sure. But what's going to get you more speed on a straightaway... getting more speed through the center of a corner, or playing with rolling resistance?
Grip is a four letter word. All opinions are my own and not those of current or previous employers.
Everyone is still directly discussing camber and rolling resistance. Is it really so bad if the discussion veers (pun) from straight-line to corners? Seriously, camber vs rolling resistance is still relevant around corners.
Technical issue--
At NASCAR tracks like Daytona and Talledega I think the cars go WOT all the way around relatively easily. The thing that seperates a good vs bad car is how much resistance they have doing this. Resistance comes from air drag and tire resistance (also powertrain drag, etc. but ignore that here). So a chassis engineer needs to focus on getting the car around the track while optimizing some combination of:
1. dynamically positioning the car into it's lowest air-drag state,
2. minimizing longitudinal tire resistance during cornering and straight-line running.
I would think that due to #2 there would be a lot of detail knowledge about the exact amount of longitudinal tire drag at various cambers, slip-angles, and cornering forces. This knowledge would allow the chassis engineer to design a setup so that the four tires give the necessary lateral force in the corners with the least amount of longitudinal resistance. Perhaps this is the kind of knowledge that JT can't simply give out on a forum.
