F&M Data, and *compound* data

[exFSAE]

In my humble opinion, all the F&M data that is now available through TTC is fantastic, but only really good for showing construction attributes.

Compound is a big deal in this series.. given the difference in ambient conditions at say.. Detroit compared to Fontana.. or the heat you'll have in your rubber in Accel compared to Enduro.

Does anyone else feel it would be valuable to have "compound curves" for the variety of Goodyear, Hoosier, Avon, etc tires available? Something showing some sort of friction and wear indicators versus temp?

[flavorPacket]

yes, which is why we do private tests.

honestly, I think that much data would overwhelm most teams. If you're so far along with your development that you can make design decisions based on tire wear models, you should probably quit what you're doing and recruit better drivers. IMO doing work that involved (and ambitious) is really only worthwhile if you're trying to specialize while you're already in college.

[exFSAE]

Maybe not wear then, as I've never seen a set of tires get corded over the course of a competition, but a grip level vs temp would be prime.

"Mo sticky.. mo betta"

[PSUAlum06]

Unless you have alumni with access to a flat-trac(and one that sees a fair amount of down-time at that), I can't imagine it being very cost effective to do any kind of private force and moment testing.

But I agree that the amount of data we'd be talking about here would results in "analysis paralysis." I've seen a fair amount of good teams get bogged down whenever they start taking a look at advanced analysis techniques and test data.

Still, it'd be interesting to see some data that backs up my opinion that softer tires aren't necessarily faster in endurance.

[Mike Cook]

I'm a alumni(well until next spring) and I run a flat-trac machine.

I have also wondered and tested a lot of the questions you bring up here.

With that said, the conditions on a flat trac machine vary so much from a real road surface, testing some of these things are really difficult, because the results don't repeat in real life. My two cents are that you're better off trying some of this stuff out in the field. If you want your tire hotter or colder there are only so many things you can change. Most teams in my opinion have better things to focus on to improve their program anyways. I do agree from a academic POV this stuff is fun to think about...

Mike

[flavorPacket]

Originally posted by PSUAlum06:
Unless you have alumni with access to a flat-trac(and one that sees a fair amount of down-time at that), I can't imagine it being very cost effective to do any kind of private force and moment testing.

Having gone through the process, I'd say that cost is not the top issue. It's much more challenging to determine DOEs, run-in procedures, etc.

From our experience, I also agree with Mike that flat-trac belts will not be close enough to the track surface to produce similar wear/temp characteristics. It's better to just get combined slip maps etc and then correlate those figures with data from testing. This is not easy; just getting a real value for cornering stiffness is a huge headache.

[Mike Cook]

In addition, I think one way to explore temperature effects is to run a really big skid pad, and compare US/OS and lat g at lap 1 to lap 20. Because it is so big you will be putting a ton of heat into the tire. If you have IR sensors you can measure this and start to understand grip vs. temperature.

Mike

[exFSAE]

The idea would be *not* to test compound on a flat track.. since there's no good way of controlling the heat.

Don't see it as a purely academic endeavour either. When it comes to tires, in this series initial grip is huge.. as is grip at medium temperature.

This kind of data is currently unavailable (publically). There are a lot of tires available, in a lot of compounds. Michelin's S6B, Goodyear's R065 and R075, Hoosier's R25A, Dunlop's SAE compound, Conti's, Avon's A45, A41, A89..

Would be interesting to see how they stack up against each other in terms of hardness, hysteresis, and stickyness.. cold and at temp.

Would be one of the first things I'd be after if I was doing this stuff again.

[flavorPacket]

exFSAE, I think the best way to look at what you're interested in would be a 3D g-g diagram (3rd axis is lap number or runtime or avg carcass temp) with different compounds as different colors. You could also do the same for steering vs. yaw rate and the other fundamental vehicle dynamics graphs.

[ben]

A short answer for now:

Are flat tracks poor for assessing compounds, and are they best for looking at constructions alone? Caveats apply, but essentially yes.

Would some data on temperature effects on different compounds be useful? Definitely yes.

Only way to start attacking the problem is to run IR sensors (and internal temp) and do a controlled test programme.

Due to limited testing (with LMS cars in representative conditions) we tend to have "families" of compounds we run specifically for different temperature ranges. We get to ensure there are appropriate gaps between the compounds and tend not to have to attack the problem we're talking about here, which is comparing many compounds that do essentially the same job and work in the same general window.

I'd be interested to see what sort of ideas people have.

Ben

[BillCobb]

You can test for compound effects on a Flat-Trac tire tester if you have the two secret ingredients. Obviously one is to get the temperature up ( how to do that is a secret, too). There is another magic ingredient that completes the job, but I can't tell you (Competitive reasons). The next best way to get the info is by mingling road test tire force and angle data with Flat-Trac results and tell your solver (to solve it) !! A constant radius test is my best suggestion. Minimize the compliance and kinematic steer and camber angle effects and measure the body sideslip angle. It would be col to dedicate an old car to this task. Wheel force transducers are a nice tool, but you guys are our hope for the future, so put your thinking caps on and get 'er done.

[PSUAlum06]

So Bill, do you mount the wheel force transducers before or after you attach the hay trailer to the corvette?

[BillCobb]

After. That way you can pull the trailer thru the fields without getting hay all balled up in the wires.

Actually, the hitch was the only concern. No brakes on trailer, Great brakes on car, 85+ mph on I-696. Exhaust tone off the wall of hay is rich. Hay chaff filling the Mercedes convertible trying to pass; priceless...