1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Setup mistake?

Discussion in 'F1 2016 - The Game' started by RoMaN14, Aug 16, 2016.

  1. F1 2016 states that moving the weight distribution to the rear will reduce understeer, which to my knowledge is untrue. The same mistake I believe is made in F1 2015. I have tried contacting them but to no avail.

    Any thoughts? Am I wrong perhaps?
  2. Piotr

    Premium Member

  3. Quoting the article...

    For this model, we will make the following assumptions:
    - there is no longitudinal load transfer

    So it's a "kinematic" model that deals with tyre angles and paths. The "understeer" there means path taken by wheels not what racers understand as "understeer" or lack of front grip. Which makes the article irrelevant to OP's problem.

    And @RoMaN14 is right, moving weight to the rear should (in general) induce understeer not oversteer but the dynamics of it are quite complicated and by cherry picking car type, setup etc. it's possible to prove the opposite as well.
    It might be that codies have physics set up in such a way that it actually does what it says there, and importantly it's not "wrong" either! Just lacking of some fine physics elements or being a byproduct of some coefficients that need to be set that way to keep more important relations correct.
    Last edited: Aug 20, 2016
  4. Piotr

    Premium Member

    So let's not cherry pick and read opening post again. It says about changes of weight distribution in vehicle made by ballast movement in garage, not by how hard we brake for the corner entry. OP does NOT mention whether it concerns driver's feel of understeer on decelertation, acceleration or constant speed. That's why I eliminated the longitudal weight transfer from this and that's why I linked this very article.

    Moving CoG forward will induce understeer due to simple laws of inertia, centrifugal forces and all other laws I cannot even spell now. It's been 30 years since I took last physics classes and it was not in English ;-)

    As OP did not mentione anything alse I stand behind what I said. More weight on front, more inertia and more understeer.

    Of course, I have also read number of times some F1 quotes going like "we had to move some ballast to front of the car to improve front grip". But with 99% probability the issue there was not enough load on front tyre to generate temperatures into operating window. Again, OP post did talk about tyres loads and temps but about overall vehicle dynamics. That's why I stand behind my post from yesterday.
  5. In a simple case it all balances out. For a case of steady cornering, moving CoG forward has an effect of front needing to increase lateral force to balance the torque between front and rear tyres on the center of mass. But at the same time moving CoG forward changes weight distribution so there is more weight to do that extra work. So moving CoG will not have direct effect on balance.

    That article you quoted is made as a part (or according to) a curriculum and is too simplified to describe real cars. (I mean litrally - they move CoM around while keeping CoG fixed, just to show tyre kinematics).

    Moving CoG will affect balance of a real car thanks to complex interactions within suspension and tyres, and it can induce either over or under steer.
    For example just introducing "tyre load sensitivity", front coefficient of friction will go down with more weight causing "understeer". Or having different ARB settings front-rear can create "oversteer" tendencies with more weight on the front due to relative changes in spring stiffness. It is really all about the details.
  6. Piotr

    Premium Member

    Don't introduce ARB, spring stifness and other things. We are not talking abou that. We could as well introduce one's 150 kg mother-in-law in back seat ;-)

    challenge that

    and I will rest my case :)
  7. I swear... of all interesting engineering related youtube channels this one has the most videos that i'd nitpick to hell :p (their content is sound, but the "vagueness" like this one triggers me~).

    Again it's a case of academics vs real life. Yes more load on the front will require more steering input to corner - ergo it's understeer. But it's under the limit cornering, where cornering stiffness dictates the amount of lateral force. While when racing we operate at the limit of grip, where coefficient of friction takes over. Look at the first graph on page4 in this (randomly found) link:
    What the video is talking about is in range of ~0-2°, while we are concerned about what happens after the 5+°.

    In other words, the kind of understeer you are writing about is the literal steering wheel angle needed to perform city driving maneuvers. It has nothing to do with what racecar drivers call understeer.
    Last edited: Aug 20, 2016
  8. Piotr

    Premium Member

    OK I admit you might have a better understanding of that.
    I got my experience from couple of track days I did in my life with rented cars and things I heard from instructors. So I based it on a bit higher level than "city driving maneuvers" ;-) as you put it, but I got your point.

    have a good weekend