Assumed Lateral and Longitudinal Acceleration for 1st year team.

[OspreysGoSWOOP]

Hello all,

1st Year team here.

I'd like to get some input from experienced teams on what types of lateral and longitudinal acceleration your car experiences.

I've read a ton of posts and I've seen assumptions anywhere from 1g to 3g's (for both lat and long). Using numbers from some team's acceleration event times I came up with average .75g longitudinal acceleration.

What did you assume or find via testing? Thanks.

[OspreysGoSWOOP]

Hello all,

1st Year team here.

I'd like to get some input from experienced teams on what types of lateral and longitudinal acceleration your car experiences.

I've read a ton of posts and I've seen assumptions anywhere from 1g to 3g's (for both lat and long). Using numbers from some team's acceleration event times I came up with average .75g longitudinal acceleration.

What did you assume or find via testing? Thanks.

[BMH]

Chapter 3 of Carrol Smith's Tune To Win should help give you some numbers for this.

[exFSAE]

What can you figure out from skid pad times?

[OspreysGoSWOOP]

Should I be using skid pad times/radius for lateral load? I used 45mph through a 7.25m turn.

I calculated 7.25m from autocross minimum hairpin turn radius of 9m (Rule D7.2.1) minus center of minimum track width
r=9-1.75=7.25m

Maybe I should be using r=15.25/2 + 1.5 = 9.125m

[Mikey Antonakakis]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by OspreysGoSWOOP:
Should I be using skid pad times/radius for lateral load? I used 45mph through a 7.25m turn.

I calculated 7.25m from autocross minimum hairpin turn radius of 9m (Rule D7.2.1) minus center of minimum track width
r=9-1.75=7.25m

Maybe I should be using r=15.25/2 + 1.5 = 9.125m </div></BLOCKQUOTE>
Skidpad times would be a good place to start. Looks like you've already found the skidpad radius too, so go for it. Check out Rule D6.8.1.

[Mike Cook]

1.5 g lateral
1 g long.

[Wagz]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by OspreysGoSWOOP:
Should I be using skid pad times/radius for lateral load? I used 45mph through a 7.25m turn.

I calculated 7.25m from autocross minimum hairpin turn radius of 9m (Rule D7.2.1) minus center of minimum track width
r=9-1.75=7.25m

Maybe I should be using r=15.25/2 + 1.5 = 9.125m </div></BLOCKQUOTE>

It won't matter what radius you use if you don't have the correct speed. What kind of lateral accelerations did 45 mph through a 7.25 m turn give you? I would kill for our car to be able to do something like that. Since you don't seem to know about the vehicle speeds through the corners, you were pointed to skidpad times. The acceleration can be determined for the fixed skidpad layout if you can somehow find the times of the cars that go around it, hmmm....

[thewoundedsoldier]

For some reason max braking grip always seems higher than max acceleration grip. And I don't buy the whole aero thing, myself.

@ Mike - I love it! everytime I see a bunch of people yacking out longer answers i know you have a two- or three- word reply coming.

[The AFX Master]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by thewoundedsoldier:
For some reason max braking grip always seems higher than max acceleration grip.
</div></BLOCKQUOTE>

Easy.. 4 wheels stop the car, 2 wheels give thrust to it.