Angular acceleration and rolling resistance

> Concerning the other posts: There is indeed a change in rolling
> resistance with slip angle. Also with slip ratio. The example of an
> IndyCar losing speed doesn't have much to do with that, though.
> That's induced drag caused by the component of the lateral force
> pointing rearwards because there's a slip angle, which slows the car
> down.

I assume aerodyanmic drag is also increased by the overall slip angle.
Perhaps this is why the tires used on Indy and the former Champ and
Cart race cars are so stiff compared to the tires used on other racing
cars. The "working" (max g turn) slip angle is about 2 degrees (I
think "working" slip angle means the total yaw angle of the car versus
the direction the car is going, essentially the slip angle of the
rear tires).

On Jan 29, 5:40*pm, "jeffareid" > wrote:
> > Concerning the other posts: *There is indeed a change in rolling
> > resistance with slip angle. *Also with slip ratio. *The example of an
> > IndyCar losing speed doesn't have much to do with that, though.
> > That's induced drag caused by the component of the lateral force
> > pointing rearwards because there's a slip angle, which slows the car
> > down.
>
> I assume aerodyanmic drag is also increased by the overall slip angle.
> Perhaps this is why the tires used on Indy and the former Champ and
> Cart race cars are so stiff compared to the tires used on other racing
> cars. The "working" (max g turn) slip angle is about 2 degrees (I
> think "working" slip angle means the total yaw angle of the car versus
> the direction the car is going, essentially the slip angle of the
> rear tires).

Yes, the drag will change with vehicle sideslip angle, but I'm not
sure in which direction it goes on an Indycar over that first few
degrees. I saw one aero CFD test that showed a very slight increase
in front downforce on a formula style car (I was late to the lecture
so don't know what kind of car it was exactly). The vertical fins in
the front wing were designed to produce that increased downforce with
slip angle, interestingly enough, by getting rid of a little low air
pressure bubble that (simulation-wise at least) developed behind and
to the outside of the front wing. What happens to drag I don't know.
It's possible it increases a bit on some cars and decreases on
others. On a GT car with a spoiler you can wind up with quite a bit
less downforce, but it's probably not safe to say that the drag would
also decrease along with it. Different cars, different effects...