What I am saying is, in the exception of unorthodox tire characteristics, extra mass ALWAYS reduces performance, in cornering too! You never want extra mass on the car, especially (like Frank said) unsprung or high-centered.

If you didn't realize this you need to pick up a good vehicle dynamics book soon.

I wasn't trying to pick on your statement, I was just curious whether you had a different reason for wanting more mass (something I wasn't aware of, especially as it pertains to tires).

-Charlie Ping
Auburn University FSAE
5th Overall Detroit 2003
? Overall Aussie 2003.

I agree with you charlie but not having enough mass on your tires be it where ever could have adverse handling charicteristics. I have dealt plenty with vehicle dynamics just not pertaining to formula style. Most of my experience comes with 12 inches of ground clearance and jumping them a few feet off the ground. The transition is being able to think in two dimensions (formula) from my usual 3 dimension offroad experience. PS wings offroad are just there to get ripped off.

quote:

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Originally posted by Big Daddy:
I agree with you charlie but not having enough mass on your tires be it where ever could have adverse handling charicteristics.

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I disagree As long as that mass would be applying a lateral force you are better off getting rid of it! Now aero's benefits are that you can have the tires see more 'mass' without the lateral loading. Your statement disagrees with vehicle dynamic fundamentals.

-Charlie Ping
Auburn University FSAE
5th Overall Detroit 2003
? Overall Aussie 2003.

geeze, i make one grumpy post late at night and look what happens! have you found these two threads yet big daddy? got wings (ignore page one, its just flames)
wings topic, and a quote from this one: "So we expect a grand total of around 90kg (200lbs) at 40km/h, or about half the weight of your car." 40kph = average speed of a fsae car...
thats got a ton of data.


and for some debate on tire characteristics, and the fact that toronto run their fattest drivers is skidpan see delft car thread. this thread sort of proves the importance of having tire data, cause no-one really knows whats better in skidpan, more or less weight! actually, i read an interesting article in july '03 racecar engineering. it basically said that a tire's CoF decreases with increasing load because the tire overheats. you guys think this happens in fsae?

actually, this forum is already hard enough to find any data in. ill post that up under the delft thread, and if you have any comments, post them on the delft thread.

- if it isnt coming, you need a bigger tool.

I need to fix up a few of those posts in the wings thread, a couple of our team misread our wind tunnel data last year and posted overly high numbers for our downforce, as seen above in Gugs quote.

The actual result was more like 40-50kg at 40km/h, with the hard part being acurately quantifying the contribution of the front wing in ground effect and the underbody diffusers. We have plans to measure them using different methods this year given some specialised testing equipment and a good venue.

The new aero package should develop about the same amount of downforce, as the wings are bigger but we have dropped the diffusers.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

More pictures of the car in a more complete state taken the other day while on display for the SAE Aero Conference.

Same Link:
http://www-personal.monash.edu.au/~fsae/03build.htm

Can never have enough carbon I say.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

Scott,

I was wondering if you could give us a square footage of those wings?

They're about 1400mm span and 400mm / 700mm chords respectively.

So about 17 square feet I think.
Lots.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae