Physical information of a typical FSAE car

[Carlone]

Hello.
For my thesis I need some information of a typical FSAE (or equivalent category) car.
I need:
<UL TYPE=SQUARE>
<LI> mass [kg]
<LI> moment of inertia [kgm2] relative to the vertical axis
<LI> moment of inertia [kgm2] relative to the longitudinal axis
<LI> position of the <STRIKE>barycenter</STRIKE> center of mass: distance from front and rear axis, and height from axis plane. [m]
<LI> width [m]
<LI> wheels radius
<LI> moment of inertia of wheels
<LI> drag coefficient
<LI> reference area
<LI> rolling coefficients of stiffness and dumping
[/list]
If someone knows some of them, please tell me!! If you prefer, mail me: carlone83 AT gmail DOT com

Thank you!
Carlo.

[Carlone]

Hello.
For my thesis I need some information of a typical FSAE (or equivalent category) car.
I need:
<UL TYPE=SQUARE>
<LI> mass [kg]
<LI> moment of inertia [kgm2] relative to the vertical axis
<LI> moment of inertia [kgm2] relative to the longitudinal axis
<LI> position of the <STRIKE>barycenter</STRIKE> center of mass: distance from front and rear axis, and height from axis plane. [m]
<LI> width [m]
<LI> wheels radius
<LI> moment of inertia of wheels
<LI> drag coefficient
<LI> reference area
<LI> rolling coefficients of stiffness and dumping
[/list]
If someone knows some of them, please tell me!! If you prefer, mail me: carlone83 AT gmail DOT com

Thank you!
Carlo.

[exFSAE]

Good luck with anything remotely accurate other than mass, width, and wheel radius.

I've never even heard of a barycenter.

Moment of inertia relative to what vertical axis? At the CG? At the neutral steer point?

Moment of inertia relative to what longitudinal axis? Through the CG, parallel to the ground? Through the neutral roll axis? Of the sprung mass? total mass?

[MalcolmG]

I think you'll find the search function on this forum will probably give you some of that information (mass, length, wheel radius) and as exFSAE states, you will probably struggle to get the other information

[VFR750R]

you forgot
downforce (seperated into front, rear)
center of pressure for your drag

barycenter = cg?

[screwdriver]

LOL
Why don't you just head down to your own team and ask them the questions?
For the rest of the numbers, you can't get, guesstimate.

[Carlone]

Excuse me for the terms, I called "barycenter" the "center of mass".

I explain better my work: I have to simulate the dynamics of a vehicle in order to identify the Pacejka coefficients of the magic formulae for the tyres.
I found a few complete sets of those coefficients only for some FSAE tyres (goodyear and hoosier), so, in order to simulate this tyres, I need to make a physical model of a car of this kind.
I don't need exact values, some approximations are enough: I only need to reproduce the dynamics of a typical vehicle that uses this kind of tyres.

Thanks,
Carlo.

[flavorPacket]

you will have to estimate inertia values. The teams that have such information will never share it, because:
1: they built their own rig to test it, or
2: they used a sponsor's rig and signed an NDA

[Carlone]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by flavorPacket:
you will have to estimate inertia values. The teams that have such information will never share it </div></BLOCKQUOTE>

Yes, I understand that these informations are reserved, but I need only some *realistic* numbers, not *real*... Maybe infos about old cars...

Carlo.

[Steve O]

If you are located close to us, feel free to arrange some time to do testing on our car. Unfortunately, as fp said, NDA's exist for some of the info we do have, and, as I'm sure a lot of other teams will say, we honest haven't physically tested a lot of the items on your list as there just isn't always enough time in a year to go beyond theoretical calculations of what it should be.

What I can tell you... not sure if it helps... our car weighs about 375lbs and with a 180lb driver the car has a F/R distro of 45/55. The cg is about 32 inches from the rear axle and about 7 inches from the ground. The widest portion of my car is 54 inches at the front wheels with a track of 48", the rear does not have the same track as the front. My rolling radius of my tire is 20" and my static ride height is 1.5".

Sorry thats all I got for you.

Steve

[Carlone]

Thank you very much, Steve! You gave me many useful informations!
It's hard for me to do some testings on a real car: I live and study in Italy...

Thanks,
Carlo.

[Matt N]

Steve's cg height estimate may be a little suspect - 9 to 12 inches above ground is a much more reasonable range. A Western Australia team member I chatted with at 07 Detroit claimed that their cg was 240mm (9.3 in) and I'm not sure if that was with driver or without. I am guessing it was without driver as most sensible seating positions place the driver cg 12 to 15 inches above ground. Maybe laydown driver positions (TUFast of Munich) are much lower but I haven't checked.

Matt

[exFSAE]

Also, tire radius is closer to 9-9.5". Unloaded diameter is around 20.

[flavorPacket]

CG is close to double your estimate (11.5-13), Steve. You might get to 10 with a super-thin dry sump pan, super-low pullrod setup etc. But that's pushing it.

that's with driver BTW