average speed for smallest curve in auto cross 9 m outer diameter

[mohab]

what is the average speed that vehicles inter this curve ??

thank you

[Charles Kaneb]

a = v^2 / r

if you put it all in meters and seconds you might get the right answer the first time.

[mohab]

thank you

I don't have tire data so i don't know the maximum lateral acceleration that the vehicle can to withstand

I assumed that vehicle inter curve in 3m radius I need to assume lateral acceleration around 1.5 g

so 24 km/hr
it that acceptable or too small

[Charles Kaneb]

I'm from Massachusetts, go to school in Texas, and have very little sense of what a "kmh" is. I know what a meter (1.1 yards) is, a millimeter (39 and a half thou), but aside from the little numbers inside my speedometer don't know how fast 24 kmh is on a 9 m outer diameter.

1.5g (15 m/s^2) is reasonable. Assume the car's about 1m from the center of gravity to the wheel, and you've got a 3.5m radius.

a = v^2 / r, so
v^2 = a * r

Enter a = 15 m/s^2, r = 3.5m, and v^2 ~= 49 m^2/s^2 so v ~= 7 m/s.

[Edward M. Kasprzak]

Originally posted by mohab:

I don't have tire data so i don't know the maximum lateral acceleration that the vehicle can to withstand

You don't need tire data for this. Competition results list skidpad times. You can calculate lateral acceleration from there.

[MCoach]

Ed,

I know of at least two teams involved in the Le Mans series that work backwards to the tire data from on track testing. Road map, coarse radii, log a bunch of vehicle parameters (velocity, steering wheel torque, wheel speed, accel + gyro, etc)

It helps with the traction control models to just code the algorithms that way and then tune it for the individual drivers. It doesn't get you an exact curve nor sometimes anything that would be realistic, but just getting the limits correctly seems to be enough.