Camber curve

[raptor93]

Hey Guys.We are a new Fsae team from Dubai and i am in the process of designing the suspension.Now,I have a doubt pertaining to camber curve.We have purchased tire data and are using it for numerous purposes like determining steering geometry,tire forces ,SAT etc.However on most of the forums I have read that tire data should be used to determine camber curves.At the moment I have entered my suspension points,calculated maximum roll expected and seen how much static camber I should have to give good tire contact patch for maximum roll in Optimum K.I understand this is just a starting point and tire temperature readings will help determine the proper camber settings.I would be grateful if you can tell me how to exactly use tire data for a proper camber curve.I would really appreciate if you can help me.Thanks

[BillCobb]

Well, to keep this thread from burning out, let me suggest an alt.tactic far removed from the book of conventional suspension design religion:

Synthesize front and rear dynamic camber curves that deliver optimum front and rear tire force and wear results. This includes the static settings.

By now I would have expected the Peanut Gallery to have chimed in with comments about how the camber output of all the tires tested in the last few rounds does not amount to anything significant. Posts already in the TTC Forum already have issued that memorandumb. But you can consider another approach and use a tactic you can optimize your suspension mechanism with:

Determine what a jounce/rebound function needs to be such that the left and right side tire's combined Mx output is minimized. This requires a parametric suspension representation (as opposed to a mechanistic one), a nonlinear tire model, accurate weights and distribution, and load transfer effects during cornering flow. This generally requires a combined front and rear approach because adding grip at the front with a soggy rear is not a winning combination as is the opposite case.

The goal is to have an optimization umbrella run simulations to compute camber functions that deliver the best Mx control during a cornering maneuver. Highest max lat plus stable control are the only objectives.

When this step is completed, you then have to package a front and rear suspension mechanism that delivers these functions, is easy to construct, fits into the chassis, lives and looks cool.

Then you can write up a nice report on how you used engineering tools to produce your designs instead of just pulling it out of thin air, considering greenhouse gas output during manufacture, or how you copied a design taken from pictures in a Formula 1 series magazine.

You might have to evaluate a few tires, pressures and wheels before you start welding stuff together, but once the process is in place, the end product will be worthy of High 5s all around.

I use Matlab to do this. Optimization of max Fy with oversteer no worse than the vehicle's Ackerman gradient, using parabolic (2nd order) camber curve models. That's just 4 terms.

[BillCobb]

I'm posting a sample of typical results for a suspension 'camber curve' synthesis process on the TTC Forum. It's there because it contains material produced from a specific tire and conditions tested in Round 6. The technique is applicable to all the TTC test rounds (In fact all performance vehicles and their tires, front and rear suspensions).

Just another example of why teams should buy into this data source.