We called Hoosier to ask them about coefficient of friction data, and they said they didn't have the facilities to provide us with a approximation of the coefficient of friction for their R25A compound...

As engineers do, we got a little crazy. But I guess we have more resources than Hoosier for tire testing. :P Got some numbers though. I'd be interested in comparing with other schools that have a number for the R25A compound.




-------------------------
UVIC Formula SAE Team

http://fsae.uvic.ca

Vic,

We're sending our tyres and a few other compounds (our secret for this year) to Ohio to a company called Scientific Research LTD. and they will be giving us data from an MTS machine.

If you want to split the $6000 cost with us, we'll give share the data w/ you!!! Tire data is like GOLD!!!!

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca

Sorry, $3000 would be too easily spent on other things, like a phone line and more than 2 15A breakers for our shop.

-------------------------
UVIC Formula SAE Team

http://fsae.uvic.ca

I'm interested if enough teams join the cause and the price drops...

If enought teams agree, we are doing the testing of the RA25 at 3 camber angles. We will supply the data to the team for the appropriate price. Basically, we have to offset the cost!

Email me if you would like this data. The company doing the testing is Smithers Scientific Services in Ohio.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca

Cost would have to drop significantly, however I would like to be notified of the final price or estimated final price.

You realy can't test it with any scale. The cof changes HUGE as you rip thru the outside of the carcus and get to new fresh rubber. The tire is made of some sort of plastic with a sticky oil in it. If the tire looks oily and is covered in rocks in the pits, they are working. At this point the cof is about 1.7 or 1.8. This is based on the highest gee loads observed on a non aero-car on good concrete. Areo cars can get peaks in the 2.5-3 gee range but there way too many variables like vertical bumps, wind gusts, and all sorts of thing that make interpreting the data with any confidence imposible. As I remember...My car will average about 1.4 gees for an entire run.

Anytime you come off course, wrap the tires in plastic or the gravel and tire dust in the pits and impound will destroy the tires for day two.



Joe Care to chine in?

Hope this helps

Andy

I agree, there is not a simple way to accurately find the data.

What would the difference be if you added other brands of tires? We've got several in mind. Perhaps we could supply more brands for little or no extra cost? Once they set up the test seems like with an extra tire and rim the cost shouldn't be much more.

-Charlie Ping
Auburn University FSAE 1999-present

They're doing it on an MTS machine at 0, 1.5 and 3 degrees of camber for a few tires of our selection. 3 to be exact.

The MTS machine will give very accurate, very dependable tire data.

Pricing will just drop depending on how many teams want the info. It's that simple, currently, I have an ex-FSAE solo/autocrosser....so that cuts the price in half. Any more interested parties?

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca

Don't get me wrong, we realize the shortcomings of our 'estimate'. However, hoosier wasn't able to pinpoint anything within a range of 0.9-2.0. We asked if they were in that range, and we couldn't even get a yes from them. Yikes.

At least we know what ballpark we are in. I would think that contrary to a true CoF number, as your normal force gets higher the effect CoF actually will increase from the zero load test we did due to an increased cogging effect with the blacktop... Thoughts?

-------------------------
UVIC Formula SAE Team

http://fsae.uvic.ca

Hey Andy,

Just wondering where you got that pic of our car from?

Regards,


Scott Wordley & Roan Lyddy Meaney
Monash FSAE Wingmen
http://www-personal.monash.edu.au/~fsae

My first thought is... What question are you tring to answer or problem are you tring to solve? If you are just tring to get in the ballpark for suspension loading and total weight transfer, the 1.7 -1.8 is plenty close enough. I have been looking at data loggers in a-mod cars for 15 or 20 years. If you want to have data to put in your data annalisys I can't help much. Remember that these numbers change HUGE (.9-1.8 or so) depending if the car a cut thru the tire outermost surface and get to the good rubber in the first few turns of the first run. This all assumes you have enough weight and downforce to ever generate enough friction to start cutting thru the rubber. I have seen the go-kart guys take power belt sanders to the tires in the pits to pre warm them. A main reason I got out of A-Mon and went to a Go-Kart is that you need NEW rubber about every 30 runs to be competitive. Joe is the guy that can realy help on this issue. He has fastest autcross car in the country and runs data accusation. Remember that all these numbers are non-aero.

Scott http://www-personal.monash.edu.au/~fsae/02race.htm I love the car

Hope this helps

Andy

[This message was edited by awhittle on January 18, 2003 at 09:10 AM.]