I should make another note that the direction you take in design with a Kinetics suspension system lead you towards longer VSALs (less camber gain in Roll). Stiffer in roll means less roll angle. However the tyres move more in bump etc. This means you want less camber gain again.

It is funny. Before we applied Kinetics the VSALs were getting a little shorter each year. After Kinetics the tendancy is to make them longer.

I wonder how many teams have had adjustable pickups on their cars to change VSALs on the track and have had enough time and an organised program to use them. It would be a nice excercise of intellectual masturbation ... would love to do the tests myself.

Kev

VSAL's is a fascinating topic

i made a bit of a mistake on the numbers, our VSAL's were about 900mm front and rear for 2005, they've got longer 2003=700, 2004=800, 2005=900, but i'd not make them longer again (for Werribee anyway)

the problem is that it's really hard to test different VSAL's (hard to vary the geom.), adjustable pickups can only get you so much adjustment

i see what you mean about kinetics requiring longer VSAL's, thanks for the explanation on that!!, and the castor thing also

with low warp stiffness does that mean you essentially don't have to set corner weights?, all you do is level the chassis? that would be coooool, i hate chassis alignment with a passion

i've always believed that (for conventional suspension) that it's very unlikely that an "optimum" VSAL is found due to spring rates/bar rates. When I started analysing VSAL's, it occurred to me that non-aero cars (especially those doing heaps of cornering), with high spring rates and low amounts of ARB, require short VSAL's. The final trade-off (determining the minimum VSAL's) is the loss of grip due to camber change over small bumps (warp mode?, my chassis vocab is slight), and the second trade-off is how sensitive the chassis becomes to ride height (a setup nightmare with different weight drivers)

in summary, i believe that minimum VSAL's is a function of how rough the course is, and how patient the engineer is (the guy setting up the chassis)

back to tyre pressures again, I'm curious as to weather you are setting camber and pressures with pyro's? I found that pyro's lead you into running low pressure and low camber.

I'm a firm believer that the centre of the tyre should be significantly hotter than the outer edge.

20PSI is high? WOW,

I've heard of people running the c2000's at very low pressures (even 10 PSI), but I have not been game to do this. The tyre does have an exceptionally stiff sidewall, but I don't think it should be run at that low a pressure.

I had a few conversations with the Hoosier guys about how low a pressure these tyres can be run. I seem to remember someone from Hoosier saying that he was "aghast at how low a pressure the FSAE'ers run with (their) tyres, and they advise against this".

Funny thing is, that until we had carbon wheels, it was almost impossible to run the tyres at that low a pressure without leaks (undersize bead diameter on Keizers).

You can't optimize your VSAL without knowing how sensitive your tires are to camber change. I know where you can get some data.

I agree that 20psi is the highest I've heard of in FSAE. 10-15 is more typical.

quote:

the problem is that it's really hard to test different VSAL's (hard to vary the geom.), adjustable pickups can only get you so much adjustment

...and your RC location & movement go up the creek if you're not really smart about it.

quote:

with low warp stiffness does that mean you essentially don't have to set corner weights?, all you do is level the chassis? that would be coooool, i hate chassis alignment with a passion

It's still painful, just a little less so. It's not as sensitive to adjustments.

quote:

i've always believed that (for conventional suspension) that it's very unlikely that an "optimum" VSAL is found due to spring rates/bar rates. When I started analysing VSAL's, it occurred to me that non-aero cars (especially those doing heaps of cornering), with high spring rates and low amounts of ARB, require short VSAL's. The final trade-off (determining the minimum VSAL's) is the loss of grip due to camber change over small bumps (warp mode?, my chassis vocab is slight), and the second trade-off is how sensitive the chassis becomes to ride height (a setup nightmare with different weight drivers)

RMIT know about that one more than most...

quote:

back to tyre pressures again, I'm curious as to weather you are setting camber and pressures with pyro's? I found that pyro's lead you into running low pressure and low camber.

Static temps from pyro's, and dynamic temps from a couple of racks of IR sensors. Just as important as those is the condition of the tyre, How it's wearing, where it's wearing, what the wear looks like, etc.

Do your drivers think the grip improved with higher camber/pressure, or did the car's characteristics change?

quote:

I'm a firm believer that the centre of the tyre should be significantly hotter than the outer edge.

Inner and centre hotter than outside isn't unusual, depending on your definition of 'significantly'. What's your reasoning on this one?

quote:

I've heard of people running the c2000's at very low pressures (even 10 PSI), but I have not been game to do this. The tyre does have an exceptionally stiff sidewall, but I don't think it should be run at that low a pressure.

The Hoosier sidewall's got nothing on Goodyear. We've run below 10, but yes we're nervous about it. The force keeping the bead seated from air pressure exceeds the max lateral force you might get out of it by a significant margin, and we've not had problems with leaks. The tyre still moves around a lot - check out photos of our car going through slaloms, or around skidpan - but everything we've done seems to suggest that's how it wants to work.

Nick,

how is the 7" Hoosier tyre "working better" at 10 PSI?

A the wear pattern is better?
B the pyros are giving values you prefer?
C the lap times (g's or whatever) are better?
D the spring rate of the tyre is what you want?

or a combination of some or all of these?

note: when i'm saying "pyros" i mean "a rack of 3 infrared pyrometers"

isn't that tyre data available on someone's FTP server yet?

quote:

Originally posted by Frank:

isn't that tyre data available on someone's FTP server yet?

I know you're joking, but remember that data was paid for by your fellow FSAE / FStudent / FSAE-A teams. Perhaps the only thing lower than cheating would be stealing from your fellow teams.

sorry denny, that wasn't funny

quote:

Originally posted by Frank:
how is the 7" Hoosier tyre "working better" at 10 PSI?

A the wear pattern is better?
B the pyros are giving values you prefer?
C the lap times (g's or whatever) are better?
D the spring rate of the tyre is what you want?

I'm not convinced it's working better at 10psi than any other pressure, but we haven't found much evidence to suggest we're going the wrong way with it. I'm keen to find some, though...

All of the above, as well as the all-important driver feedback. A & B are the quickest, C is still used but takes a bit more thought. The spring rate least of all, we use that as a starting point, and as a last minute balance tweak.

In all the rush before a comp we don't get too far past tuning for temps, wear patterns and happy drivers. The data gear helps a lot, if only to confirm or deny our suspicious as to what might be happening. Detailed analysis takes time, and that's what summer's for...

i agree very much with what you say

perhaps uq will try less pressure now they better rims....

we found the spring rate of those tyres didn't change much with pressure (stiff sidewall dominating at low pressures)

Why RMIT didnt finish the endurance?

Wow....

Look at the picture of UWA's suspension I found on there website.

http://www.motorsport.uwa.edu.au/photos/pastcomps/2005-...ll_size/RIMG0035.jpg

Can anyone from UWA tell me, Will you be going overseas with this car?

Kes

Yep we are going somewhere!

Hey guys,

Werribee was my first F-SAE comp, just wondering if the low finish rate in the enduro is normal? how has it been in previous years?

Timbo
Curtin Motorsport Team

My understanding after 3 comps in Detroit is that less than half the cars finish endurance, usually closer to only a quarter of them. Might it be the same at FSAE-A?