Delft Car

[Banacek]

Is anyone willing to share what weight saving features they saw on the DUT car at Formula Student?

135kg is unbelievable and I can't really get the details from the pictures on the site.

Off hand, it looks like they have:
- Fibreglass Monocoque (what's used for stupport in the structure?)
- Really slick uprights
- Suspension elements look suspiciously like carbon fibre, but I can't really tell from the pictures. Can anyone confirm/deny?

Anything else?

Anyways, good work Delft, that's some impressive work and will probably go on as one of the best FSAE cars ever.

Bancek

[Dan Deussen @ Weber Motor]

I also caught:
1) Aluminum roll hoops and rear frame
2) Composite drive shafts
3) Composite rims

I would really like to know how much did the drive shafts and rims set you guys back. Or did you make them yourself? http://fsae.com/groupee_common/emoticons/icon_confused.gif

Daniel Deussen

[Igor]

Well, I'll give you a hand here :-)

Carbon fibre:
Monocoque, A-arms, pull rod, rims, drive shafts, steering shaft, steering wheel, restrictor, intake plenum, pedals.

Aluminium rear space frame, one cylinder superchanged engine.

Only try this if you have really good people for you carbon :-)

There are plenty more pictures, but not on the site yet.

Igor

[Banacek]

Wow, that's a lot of carbon, I figure you didn't do too well in the cost segment.

That's a really impressive design, congratulations guys.

Speaking of carbon, can you suggest some references for learning to make shafts out of carbon fibre?

Banacek

[Igor]

Well, material costs are not that high. Carbon components are only expensive because people are willing to pay a lot of money for them.

As for manufacturing references: come to Delft, study aerospace engineering and learn to do carbon properly :-)

I'm sorry, but I don't know of any reference works.

Igor

[inamo]

Not forgetting the "lace" style brakes and sprocket!!

[Jimboblofski]

You are forgetting one thing! yes this car was very light and it did look the dogs b$*$*s but, IT DID NOT PASS THE BRAKE TEST PART OF SCRUTINEERING!

This must say something about engineering a good race car, At least test it properly befor the race!!!!

[Mi_Ko]

I saw the car in burtingthorpe.

Delf did a perfect job with the weight reduction. They saved most of the weight with the ktm engine, which weights only 35kg, the carbon driveshaft and flexplates instead of cv-joints. (which are for me the best invention on the 2003 event. I havent seen them before. Who is manufacturing them?)

2002/03 Team Member - Formula student Europe

[Frank "Ruska"]

The Compisite flexplats are made from GKN. A lot of teams run them in 2001, and some 2002 in Australia, like Tasmania. They are very expensiv and the can compensate only 3?. CTG has some as well, who can compensate 4?. But the problem of this small angel is, that your rearsuspension can´t work probertly. If you have a really short driveshaft like us, you need more flexibility in your joints. Only than you can find a god setup for your car. Otherwise you suspension could by to stiff. So on one side the disks are really light and easy to use, on the other side you have to make a lot of compromisses. And what is more importand, a good working suspension or 600gramms you will save?

Frank Röske
Student Racing Team
University of Applied Sciences Stralsund/Germany

www.student-racing.de (http://www.student-racing.de)

[vinHonda]

I agree with Frank.... only 4 degrees of movement??! And I will guess that they cost quite a bit more then your regular CV cups.

Delft's car was indeed very light and a very good bunch of guys on that team too. Their setup and displays were very nice as well. I would run into one of their drivers a lot and ask how things were going (he also was the first to let us know we won Endurance) and he said it would be interesting to see his car on track to see how the weight savings would influence lap times.

I myself would also be interested to see how the Delft car would perform in our style of events.

Being light is great, but does moving to a single cylinder provide the same power to weight ratio of a typically used Honda? Also, being so light, how effective can you use your tire? Tire temps would be no where near operating temps! So that leads me to ask..... where does the Delft car make it's advantage on track?

Nonetheless, it was a beautiful car. I've never seen so much carbon on an FSAE car before! But I definitely thought it looked pretty.

What do other teams think? How would have the Delft car faired on track?

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Mi_Ko]

Oh,... only 3-4 degrees?! But if you design your suspension for that, you can get enough movement.

Another questin:
At the official weighting, the judge said our car weights 269 kg (Uni. Maribor)! How can this be true? We calculatet our mass below 200kg, and two men can lift the car easyly. Was something wrong or what? What does your car weight in comparisement to the official weighting?

2002/03 University of MARIBOR - Team Member

[inamo]

ours came in at 207kg and seemed about right. Maybe you just have a team of weightlifters?!

[vinHonda]

our car at 217kg was also correct.

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Charlie]

If you don't have scales of your own, you can't really judge it by 'feel'. http://fsae.com/groupee_common/emoticons/icon_smile.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[clausen]

If you dont have scales of your own, how are you setting the corner weights?

Regards

Paul Clausen
Uni of Adelaide

[Mi_Ko]

We did it by feeling and with some testing. But this wasn't realy a problem, because we damaged our home made dampers. http://fsae.com/groupee_common/emoticons/icon_frown.gif

We weightet only the frame (50kg), differential (20kg - alfa 33 + housing) and the driveshafts (20kg - yugo koral 45). The engina has no more than 60kg. That is together 135 kg + aprox 50kg from the wheels and arround 10-20kg other stuff (Steering, seat, electronics, fuel tank, radiator,...) Where did the other 50kg came from?

2002/03 University of MARIBOR - Team Member

[Sam Zimmerman]

I suspect it came from the same place as the 30 lbs our car gained within the last three weeks before competition. I am not sure, but I think the Vandals Racing car was snacking in the evenings when nobody was looking. http://fsae.com/groupee_common/emoticons/icon_confused.gif

Sam Zimmerman
Vandals Racing
2002-2003 Team Leader

[This message was edited by Sam Zimmerman on July 21, 2003 at 08:43 PM.]

[Lyn Labahn UW-Madison]

Things that might have added weight:

Bodywork, Fuel, Oil, Water, Battery, Harness, Padding, exhaust header, muffler....

This year we had our car tearing around the test track at around 420 lbs with no body work. We weighed in at 451 lbs at Detroit. I can't imagine that the Delft car was that light. Job well done boys, maybe consider adding a few more "reliability" pounds in the right area, and I want to see you in Detroit next year!

2002/2003 Team Leader
Best overall average finish of the new millenium http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Daves]

Solidworks (and probably other CAD programs) will give you the overall mass of your car and your center of mass. If you model your parts accurately enough (fudge the densities to get correct weights), then your overall mass and c.o.m. should be dead on.

[This message was edited by dave_s on July 21, 2003 at 03:58 PM.]

[Charlie]

Should be.. http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Sam]

ie. fasteners, wiring, other electricals, fluids, all these little bits and peieces that do not make it into the cad (in most cases) add up!

Sam Graham
Engine Group Leader 2003
UQ Racing

[Big Bird]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by vinHonda:

I myself would also be interested to see how the Delft car would perform in our style of events.

Being light is great, but does moving to a single cylinder provide the same power to weight ratio of a typically used Honda? Also, being so light, how effective can you use your tire? Tire temps would be no where near operating temps! So that leads me to ask..... where does the Delft car make it's advantage on track?

Vinh

University of Toronto Formula SAE Racing Team
http://www.fsae.utoronto.ca<HR></BLOCKQUOTE>

Firstly, congrats to the Delft lads for building something completely "out of the box". Sounds like a great little car, would love to see it one day.

The power to weight arguments came up on the single cylinder thread a couple of months back. Firstly, it would take some sort of miracle for a single to match the power to weight ratio of a well set up four. But to compare the two concepts this way is to miss the point of going to a single in the first place. Teams doing this are trading a little of their power to buy benefits in terms of weight, inertia etc. These benefits come to the fore in places where you are not accelerating in a forward, such as cornering and braking. Since a typical FSAE track has more corners and transients than it does straights, it doesn't make much sense to dismiss a design in terms of how well it goes on the straight bits.

As for tyres, a lightly loaded tyre generally has a greater coefficient of friction than a heavier one. Therefore, as weight increases, the corresponding proportion of grip drops off, essentially meaning that a heavier car will have to corner slower for a given tyre. Sorry if i haven't descrbed this very clearly, Milliken does it pretty well if you have the time to look through it. As for tyre heat, if a tyre isn't heating up quickly enough there are other ways of achieving this than making the car weigh a tonne.

And one more thought for the power/torque junkies - how many of you have measured your engine's inertia? Angular Acceleration = torque/inertia, so if you are comparing power/torque figures between two radically different engines you probably should assess internal inertia as well, or else you are not getting a true indication of potential.

And on that note, it's time to return to the workshop where we are building the slowest and fattest single cylinder FSAE car the world has ever seen.

Cheers,

Geoff

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Break it.

[gug]

Delft have in the past made the very respectable power figures of:
2001: 85bhp, 55nm
2002: 91bhp, 61nm

i know these arent exactly a power curve, but it seems like they can extract a fair bit of power out of an engine. i would love to know what sort of power to weight figures they were getting out of the supercharged single. and what they think they could have got with a bit more time! my team is about to decide on an engine at the moment, so it would be very helpful too!

anyway from Delft want to help out?

on a similar topic, finding any information about forced inducted, restricted singles is quite difficult. does anyone know of a formula that uses these or at least some info/experience for researching stuff like this?

TIA.

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

[ben]

The Delft cars ran with 4-cylinder engines prior to this year. Therefore those figures are for those engines.

Ben

University of Birmingham
www.ubracing.co.uk (http://www.ubracing.co.uk)

[Daves]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>ie. fasteners, wiring, other electricals, fluids, all these little bits and peieces that do not make it into the cad (in most cases) add up! ~~ Sam<HR></BLOCKQUOTE>

I agree. However, when working on the small scale of a formula car, fasteners are not very difficult to add to a CAD model.

Also, the mass of fluids can be added into the part that holds them. For example, add the oil mass into the mass of the engine and transmission.

Another option is to create extremely accurate bills of materials which include all the parts and their respective weights (all the way down to the safety wire). This is probably a better option for overall mass, but the CAD is much more useful for estimating the f/r weight ratio and c.o.m. before actually building the car.

[Disco]

Could someone post a pic of the Delft car?

[gug]

www.dutracing.nl (http://www.dutracing.nl/) has heaps more.
http://www.dutracing.nl/photogallery/galleries/2003_event/IMG_1236.jpg

im guessing you havent found this link either: team listing (http://www.sae.org/students/schools.htm), it lists most of the teams and links to their websites.

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

[Big Bird]

Thanks gug, we'd actually found their website but most of the photos are pretty dark and lack detail. I guess that is one of the beauties of carbon fibre, you can hide your secrets because the stuff is black and no-one can take really good detail shots of your car.

If anyone got any good shots of the car at the comp, we'd love to see them.

Cheers

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Break it.

[Banacek]

Quick note on power from a single:

Tokyo Denki (sp?) used a comparable single cylinder engine in Detroit this year. It was naturally aspirated and I believe it did not even have fuel injection. The Tokyo guys quoted a figure of 40hp at the engine iirc. If someone can ballpark what the benefits of a supercharger and fuel injection would be, that would be a good estimate of output from the Delft car.

I know nothing about engines but let's assume they can get 60hp with the supercharger and injection. Keep in mind that for such a small engine, their supercharging efforts aren't limited by the air restrictor as much as Cornell's turbo.
Feel free to offer better estimates.

So, a typical 600cc car:
85hp/450lbs = 0.19

A light 600cc car (Toronto, 400lbs iirc)
85hp/400lps = 0.21

The estimate for Delft:
60hp/300lbs = 0.2

With a 170lb driver, the numbers come out to:
0.14
0.15
0.13
respectively

So even if my math was a little off, power/weight is more or less comparable. I think if anything my HP estimate for Delft was a little light.

Then tack on the fact that they can corner and brake better than most as someone else pointed out in this thread...

Banacek
"There's an old Polish saying..."

[Banacek]

On another note, the Firenze guys had good pictures of Delft. There's a nice one of the front wheel, suspension, etc. That's a lot of carbon.
http://www.firenzerace.too.it

banacek

[Igor]

The 60hp is a pretty good estimation for the Delft car. However, when you consider that a lot of drivers aren't exactly close to the rev limiter while driving, the torque gains from the supercharger at low revs are making things more interesting.

Igor

[Charlie]

The Toronto car was 400 lbs? Really?

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[V2 - Italy]

The Toronto car was exactly 217 kg.
Official weight!

Daniele

Firenze Race Team V2

http://www.firenzerace.too.it

DUCATI POWER at the UniversitÃ* di Firenze

[Charlie]

477 lbs then, sounds more likely.

I know, everything else equal, a lighter car will corner better. But I think there are many, many variables that matter more. Teams should always strive to reduce weight, however it is my opinion that the lightest car at competition will always have major design flaws that allow it to be the lightest. I may be wrong, and the Delft car certainly looks well done. But from my competition experience that's my opinion.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[vinHonda]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Big Bird:
<HR></BLOCKQUOTE>

Firstly, congrats to the Delft lads for building something completely "out of the box". Sounds like a great little car, would love to see it one day.

The power to weight arguments came up on the single cylinder thread a couple of months back. Firstly, it would take some sort of miracle for a single to match the power to weight ratio of a well set up four. But to compare the two concepts this way is to miss the point of going to a single in the first place. Teams doing this are trading a little of their power to buy benefits in terms of weight, inertia etc. These benefits come to the fore in places where you are not accelerating in a forward, such as cornering and braking. Since a typical FSAE track has more corners and transients than it does straights, it doesn't make much sense to dismiss a design in terms of how well it goes on the straight bits.

As for tyres, a lightly loaded tyre generally has a greater coefficient of friction than a heavier one. Therefore, as weight increases, the corresponding proportion of grip drops off, essentially meaning that a heavier car will have to corner slower for a given tyre. Sorry if i haven't descrbed this very clearly, Milliken does it pretty well if you have the time to look through it. As for tyre heat, if a tyre isn't heating up quickly enough there are other ways of achieving this than making the car weigh a tonne.

And one more thought for the power/torque junkies - how many of you have measured your engine's inertia? Angular Acceleration = torque/inertia, so if you are comparing power/torque figures between two radically different engines you probably should assess internal inertia as well, or else you are not getting a true indication of potential.

And on that note, it's time to return to the workshop where we are building the slowest and fattest single cylinder FSAE car the world has ever seen.

Cheers,

Geoff

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Break it.[/QUOTE]


Curious to know where Milliken says that a lightley loaded tyre creates a greater coefficient of friction???? Clearly, we are looking at lateral loads as something that is equally as important. The Hoosiers and Goodyears that most teams run on typically will not reach operating temps that are optimal for the tires' compound. These tires are designed for heavier application....and this is why I think that a light car won't use it's tire as well. Understandably..... as you increase the vertical load to a point.... the tire will not be able to hold the lateral loads. But i'm sure the graph isn't linear....so it's impossible to say that the lighter the load on a tire.....the more cf it'll produce....... it also depends on the tire itself.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Charlie]

Any car tire, or definitely anything we deal with, will have a greater CF with a lighter car, at the same temperature. This is not from the decrease in normal force (more normal force will always raise CF) but from the reduction in lateral loading of the tire from the vehicle weight. From what I understand this always overcomes the loss of CF from less normal force. This is the same reason weight transfer hurts rather than helps lateral force. Read the Smith books. http://fsae.com/groupee_common/emoticons/icon_smile.gif

As far as tire temps, there are definitely ways to put more heat in the tires without adding vehicle weight. Are they worth it? Depends, of course. But if we could have a lighter car, we'd do it. We'd figure out another way to get higher tire temps.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[gug]

i think you know exactly how to put heat into tires Charlie, ive seen the drifting you call driving! all you need is 4wd hey? http://fsae.com/groupee_common/emoticons/icon_wink.gif

Auburn's multimedia page (http://eng.auburn.edu/organizations/SAE/AUFSAE/)

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

[Engelbert]

Hi Vinh,

when simplified (ie steady state etc), lateral tyre load is determined by (everything alse being equal) the vehicle mass and lateral acceleration (ie. mass transfer).

So by increasing vehicle weight you are automatically increasing the lateral forces at the same rate (when keeping everything else constant, etc).

BUT, you're basically saying to ADD WEIGHT to an FSAE car to get it to corner with a higher lateral acceleration !!!!

Riiiight....

What we are talking about here is why we want our C of G as low as possible = less transfer of mass (as Charlie pointed out) = more equally loaded tyres = better lateral acceleration...

Sam.
2001 UQ-FSAE

PS. sorry about the smartarse-ness of my reply, but you really did ask for that one !!!
Its all in good humour mate !!

[gug]

bump.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> finding any information about forced inducted, restricted singles is quite difficult. does anyone know of a formula that uses these or at least some info/experience for researching stuff like this?

TIA.<HR></BLOCKQUOTE>

- the ever hopeful gug...

[vinHonda]

Sure. Of course we want lower Cg's.....
and of course we want equally loaded tires.

Adding weight does increase lateral forces..... don't you guys pick your heaviest drivers for the skidpad?

Load transfer you can play with using your bars..... all my argument is, is that the kinds of tires we run...... don't produce that much grip because they are designed for heavier cars. If you look at tire data..... lateral forces increase with vertical load (keeping slip angle the same)

No worries about the smartarse-ness...... it's only smartarsed when you think it is. I thought it was a very valid comment.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by vinHonda:
Adding weight does increase lateral forces..... don't you guys pick your heaviest drivers for the skidpad?
<HR></BLOCKQUOTE>

Are you serious?!

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Erik C]

Load sensitivity of tires is one of the basic concepts of vehicle dynamics. If a tire's coefficient of friction does not decrease with load then why worry about CG height at all? If this were true then the car would theoretically be able to corner at the same acceleration if all the weight were on 1 tire, rather then distributed between 4.

www.adamaircraft.net (http://www.adamaircraft.net)

[Denny Trimble]

"Adding weight does increase lateral forces..... don't you guys pick your heaviest drivers for the skidpad?"

You're joking, right?

If not, I've got some ballast I'll sell you.

University of Washington Formula SAE ('98, '99, '03)

[Big Bird]

Crikey, this thread has grown horns since I last looked.

Vinh, in regard to my comment about Milliken, have a look at Figure 2.10, p29 - it's a graph of lateral versus longitudinal load for a Goodyear racing tyre. It is a pretty good depiction of load sensitivity. The relation starts off linear, but as you get to higher vertical loads the slope of the graph drops off. Knowing that coefficent of friction = lateral grip / vertical load, calculating this at a few points along the graph will show you that the cf is actually dropping off at higher loads.

Since the necessary amount of grip increases linearly with increasing mass (mv^2/r), and the cf drops off with increasing mass, more mass means we have to drop our velocity to get the centripetal force back to an acceptable value.

We've never had a problem with our tyres getting up to temperature, so I wouldn't base a whole design around that concept.

Cheers,

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Break it.

[Denny Trimble]

What the heck, let's bring up another question in this thread.

Low tire temps are not a problem in Australia, I'm sure. But in Detroit in May, they can be. In my opinion, this is why certain teams (UTA, Wollongong) run 6" wide tires in Detroit. Getting the tires up to temp quickly may pay off big time in the Friday events.

I'm curious as to the other affects of narrower tires. I've read that they will give larger slip angles, which means easier-to-feel, but possibly more cornering drag. And I don't know about their lateral g limit and over-limit "forgivability".

Anyone out there test 6" and 7" tires?

University of Washington Formula SAE ('98, '99, '03)

[Charlie]

We are by no means experts but we did some tire temp testing in 2002. We made changes to our 03 car to heat up the tires better, and literally I had chunks of rubber on my helmet after our first drive (well you see how I drive, but still, those were off the fronts http://fsae.com/groupee_common/emoticons/icon_wink.gif )

It worked great in Detroit! Australia will be a different story.

We have to run tyres in Australia, which come up to temperature much faster than tires. This can be a problem. We may run wider tyres in Australia (we need to test in the Alabama summer to see). But how do wider tyres compare to tires? Who knows? http://fsae.com/groupee_common/emoticons/icon_confused.gif http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Engelbert]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by vinHonda:
Sure. Of course we want lower Cg's.....
and of course we want equally loaded tires.

Adding weight does increase lateral forces..... don't you guys pick your heaviest drivers for the skidpad?

Load transfer you can play with using your bars..... all my argument is, is that the kinds of tires we run...... don't produce that much grip because they are designed for heavier cars. If you look at tire data..... lateral forces increase with vertical load (keeping slip angle the same)

No worries about the smartarse-ness...... it's only smartarsed when you think it is. I thought it was a very valid comment.

Vinh

<HR></BLOCKQUOTE>

Sorry mate. But you've got it all wrong!

Try and follow.

Yes, adding weight increases lateral FORCE, but REDUCES ACCELERATION, which is the thing you want to increase.

Thats why F1 cars dont add an extra 4 tonnes of ballast to get those cornering speeds.

"If not, I've got some ballast I'll sell you.", Denny Trimble.

Good call Denny !

"If this were true then the car would theoretically be able to corner at the same acceleration if all the weight were on 1 tire, rather then distributed between 4.", SpeedRcr.

So true.

The bottom line is, who cares if the lateral FORCE goes up, as long as you make the ACCELERATION go up...(obviously Im simplifying things again...so could the pedantic ones out there just go easy on me !)

I was under the impression the Hoosier FSAE tyres were well suited to (if not designed for) lighter vehicle weights ? Or are they just re-badged as such ?

Of course no tyres are going to be at operating temp at the start of any event, but if you cant get them hot after a (couple of)hard laps, you're going too slow!

OK, time to open ANOTHER can of worms:
In A LOT of cases, a sliding tyre will heat up quicker than a gripping tyre. So having less weight could heat the tyres quicker....

Stick that in your pipe and smoke it !!!

Out of curiosity, Charlie, what are your tyre heating tricks (besides the obvious!) ?

Sam.
2001 UQ-FSAE

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Engelbert:
[QUOTE]I was under the impression the Hoosier FSAE tyres were well suited to (if not designed for) lighter vehicle weights ? Or are they just re-badged as such ?<HR></BLOCKQUOTE>

Not really. They are softer than the Goodyears, but still not as soft as we'd like to see.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Of course no tyres are going to be at operating temp at the start of any event, but if you cant get them hot after a (couple of)hard laps, you're going too slow!<HR></BLOCKQUOTE>

You only get a couple laps in Autocross. And maybe you are 'going too slow' because your tires are too cold to go fast. http://fsae.com/groupee_common/emoticons/icon_wink.gif Apparently you haven't veen fortunate enough to drive in Detroit. In 2002 is was like driving on ice (which I think helped me)

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Out of curiosity, Charlie, what are your tyre heating tricks (besides the obvious!) ?
<HR></BLOCKQUOTE>

We didn't do anything special, just actively kept tire temps in mind during design. I think we will look a lot smarter by being ambiguous anyway. http://fsae.com/groupee_common/emoticons/icon_wink.gif To prove my point here is a fuzzy, illegible photo. http://fsae.com/groupee_common/emoticons/icon_razz.gif In fact you can't even tell if its a tire or tyre in that photo.

http://www.auburn.edu/~pingiii/tiretesting.jpg

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Daves]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>We have to run tyres in Australia, which come up to temperature much faster than tires.~~ Charlie Ping<HR></BLOCKQUOTE>

What the heck are you talking about? "Tires" are the same thing as "tyres;" just different spellings.

[Denny Trimble]

I think he's talking about the coriolis affect in the southern hemisphere... or maybe the dropbears. They're nasty!

University of Washington Formula SAE ('98, '99, '03)

[vinHonda]

Yes. We do run ballast for our skidpad. Seriously.

Milliken is right... obviously if you overload a tire, it's going to lose grip. If you look at recent tire data on the Goodyear and the Hoosier that 'most of us' run..... the lateral forces peak out at quite high slip angles and higher vertical loads, to a point.

F1 cars get their cornering speeds from their aero downforce.

"If this were true then the car would theoretically be able to corner at the same acceleration if all the weight were on 1 tire, rather then distributed between 4.", SpeedRcr.

I'm not saying that loading a tire vertically to the max is a good thing....because in vehicle dynamics....there's something called weight transfer! My point is..... the tire makes its most grip at fairly high vertical loads before it drops off quite rapidly.

And yes... i'm serious..... we run our fattest drivers in skidpad. Try it one day.... I promise you better skidpad times.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[gug]

if you are looking for an intelligent discussion on the delft car, or actually any sign of intelligence at all, please skip the rest of this post.

here is the definition for tyrefrom www.freedictionary.org (http://www.freedictionary.org)(try it if you dont believe me!):

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>From Webster's Revised Unabridged Dictionary (1913) :

Tyre \Tyre\, [Tamil tayir.]
Curdled milk. [India]<HR></BLOCKQUOTE>

you see, us australians couldnt import any rubber back in the early days (no merchant was prepared to land on oz, because they were scared of the dropbears), so we figured out that very old and curdled milk has almost the same properties. so you americans had better start curdling you milk if you plan to be competitive over here! if you are looking for tips and tricks, email me at gugedy@goodyear_old_milk.com.oz

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

[gug]

im back from the land of la-la, no more stupidity, i promise!


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by vinHonda:
If you look at recent tire data on the Goodyear and the Hoosier that 'most of us' run...<HR></BLOCKQUOTE>

okay, here is my (quite possibly wrong) thoughts on this. im beginning to agree with vinh here. we wouldnt run 30" race tires even if we were allowed tire warmers, because the sidewall design and flexibility of the rubber (ie size of contact patch) would not suit our lightly loaded applications. i think vinh is saying that the tires are designed to give their maximum CoF at a certian verticle loading, and we are too light to give that loading.
if my reasoning is right, then increasing weight transfer is a bad thing (small benefit in CoF from increasing the load on 2 wheels, big loss from decreasing the load on 2 already underloaded (for max CoF) wheels). but increasing the total loading will result in higher CoFs.

but if i remember right, Toronto's car was very light wasnt it? are you sure this applies for the rest of us with fat cars running fsae spec tires vinh?

hope ive cleared up some confusion here. if not, at least i can laugh at you all going cross-eyed trying to understand my confusing explanations http://fsae.com/groupee_common/emoticons/icon_cool.gif

- if it isnt coming, you need a bigger tool

[Charlie]

I can't see better skidpad times from a heavier driver being anything more than a tire temp issue. All things being equal, a lighter car will corner faster (it is a tire property!) Read Tune to Win!

You are sending me back to look at tire data again, but I'm sure its just a trap. http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[This message was edited by Charlie on July 29, 2003 at 07:55 AM.]

[Big Bird]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by gug:

i think vinh is saying that the tires are designed to give their maximum CoF at a certian verticle loading, and we are too light to give that loading.
if my reasoning is right, then increasing weight transfer is a bad thing (small benefit in CoF from increasing the load on 2 wheels, big loss from decreasing the load on 2 already underloaded (for max CoF) wheels). but increasing the total loading will result in higher CoFs.


<HR></BLOCKQUOTE>

Hi there Gug,

A few misguided attempts to explain vehicle dynamics via a text editor. Do you have a copy of Milliken? If so, turn to page 29, figure 2.10 as I referenced in one of my above mails.

Firstly, in terms of CoF, maximum theoretical CoF happens at just above zero loading, stays roughly the same for a while and then starts to drop off at higher loads. I don't think any of us have cars that are too light to achieve zero loading. If you look at the diagram, the ratio of lateral force to load remains roughly constant, then starts to drop off at higher loads. Therefore lower CoF at the high loads.

For example, looking at the 5 degree slip angle graph, at 800lb load the lateral force is approx 920lb, therefore giving a CofF around 1.15. At 1600lb load, the lateral force is approx 1600lb and therefore CofF is around 1.00.

Vinh was stating that we get more GRIP at higher loads, and I won't argue with him on that one. But the issue is that we need even more grip than we are gaining by going to higher mass.

Centripetal force varies linearly with mass, as per F=mv^2/r. For a constant v and r, a doubling of mass will result in a doubling of centripetal force. However we've seen above that the grip available doesn't double, so if effect we have to reduce velocity accordingly to bring the centripetal force back to a value the tyres (sorry, tires??) can cope with. Not good.

To overemphasize the point, consider our 800lb loaded tyre above. Say we are out on the skid pad at a speed where we are right on the edge and using all of our 920lbs of grip to counter the centripetal force. We bring the car into the pits and the chief engineer puts in the biggest driver and it doubles the weight of the car, (and to minimize variables say the CofG doesn't change). The vertical load on the tyre is now doubled to 1600lbs in the same corner, and at the speed we were at before the centripetal force we need to oppose is now doubled to 1840lbs. But the available grip is only 1600lbs. Therefore we don't have enough grip for the centripetal force, so we either slow down or slide off.

As for Vinh's comment about aero downforce in F1, the beauty of aero is that we increase vertical load on the tyres without appreciably adding to the mass of the car. In the case above, say we double the vertical load through aero and our grip goes up from 920lbs to 1600lbs. But the mass might have only gone up say, 25%. Therefore we have 1600lbs of grip, but only around 1000lbs of centripetal force to oppose. We now have more grip than we need, so we can bump up the velocity.

I hope the above hasn't been too patronizing or trivial, I just think it is a little easier to paint a picture with a few numbers. And apologies if you don't have Milliken.

Cheers,

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Break it.

[gug]

i understand exactly what you are saying big bird, and there isnt much arguing with that. so why does vinh run ballast then? and get better times with it!

hey, anyone got a url for the tire data from hoosier or goodyear? or does that only come with the tires?

[Big Bird]

I'm stuffed if I know. It could be any number of other variables, including tyre temps, driver skills, COG shift, shock settings better matching the higher weight. Maybe the driver is so big he's creating his own weather patterns and is getting sucked around in a private tornado.

The point I'm making is that if you try to explain it in terms of CoF and "ground hugging weight", the theory is flawed and the design judges would cane such an answer.

As for the tyre data, sorry. I hate to say it, it is probably best to start generating your own. Maybe if you build up a good relationship with your supplier and show them that you are serious, some might start trickling through....

Cheers mate

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Break it.

[karter]

There are reasons to use balast, but only as a last resort to cure handeling problems. Heavier drivers would cause more chassis roll, possibly a better camber angle on the tire. Anyhow, what are the chances that the weight distribution is ideal given that you have to package the whole car?

[Erik C]

OK, I am sitting here looking at tire data we collected for different tire widths; 7", 7.5", and 9" tires. The 7", and 7.5" tires produce peak CofF at near ### lbs load and decrease rather rapidly, the wide tire produced a peak CofF at ### lbs but maintains a higher overall "average" CofF.

www.adamaircraft.net (http://www.adamaircraft.net)

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Big Bird:
maximum theoretical CoF happens at just above zero loading, stays roughly the same for a while and then starts to drop off at higher loads. I don't think any of us have cars that are too light to achieve zero loading. If you look at the diagram, the ratio of lateral force to load remains roughly constant, then starts to drop off at higher loads. Therefore lower CoF at the high loads.<HR></BLOCKQUOTE>
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SpeedRcr:
The 7", and 7.5" tires produce peak CofF at near ### lbs load and decrease rather rapidly, the wide tire produced a peak CofF at ### lbs but maintains a higher overall "average" CofF.<HR></BLOCKQUOTE>

do you ever get that feeling, like when you are stuck in a maze and you are just certain that you have been past this corner before?

could someone please tell me that SpeedRcr and vinHonda arent directly contradicting Milliken and Carrol Smith? failing that, could someone tell me who is right! http://fsae.com/groupee_common/emoticons/icon_confused.gif

btw, SpeedRcr the numbers just came out as ###, i dont suppose you could replace them with some numbers - and provide tire names and your data files? http://fsae.com/groupee_common/emoticons/icon_wink.gif

seriously though, are you now using ballast in skidpad because of your tire data? thanks to both you and big bird for the help!

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

[Charlie]

From Tune to Win:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The basic equation for cornering force:

F= (mass x velocity x velocity)/radius

assures us that- all other things (especially tires) being equal, a light car will go around a given corner at a greater road speed than its heavier counterpart. <HR></BLOCKQUOTE>

He uses the analogy of a rock and string. The heavier the rock, the sooner the string will break. The heavier the car, the quicker the tires will lose grip. Yes, they have a better CF because of increased normal load. But the lateral force caused by vehicle mass, velocity, and radius will overcome the benefits of increased normal load and slightly better CF.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Erik C]

http://fsae.com/groupee_common/emoticons/icon_smile.gif now if I were to give away such data what would you learn? Young grasshopper, you must test your own tires to understand and become one with its CofF. But trust me, the maximum CofF occurs at very low load, holds steady for about ### lbs and then drops off by #% at ### lbs. This is exactly what most people on this discussion have been saying, and if you don't believe me, try it yourself.

P.S. I would replace the ## with numbers if it didn't hurt my team and give up information we worked so hard to gather.

www.adamaircraft.net (http://www.adamaircraft.net)

[vinHonda]

I don't think I'm contradicting Carrol Smith at all..... if anyone so graciously got to speak with him; he'd tell you to run your heaviest driver in skidpad! Especially on the Goodyear R65 and the Hoosier R25A!

We tested our tires at Smithers Scientific in Ravenna Ohio on a MTS Flat Trac tire testing machine. This is where we got our data.... wasn't hard work......just cost a crap load of money.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Denny Trimble]

NOW you're talking. So, you're saying your C.F. went up with normal load (in the FSAE realm), on your actual tire test data on that machine? That's pretty interesting. So, do you soften your springs/bars/shocks at one end of the car to _reduce_ grip at that end now?

University of Washington Formula SAE ('98, '99, '03)

[vinHonda]

lol! Let's just say tire data doesn't lie! It is quite interesting. If you take a closer look at Cornell, GT and us.....we aren't running Goodyears or Hoosiers....

Had a good conversation with Yuki from Cornell about this; and like us, everyone's going to tire manufacturers to build their own compounds.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Erik C]

What was the surface you tested your tires on? If it is on an MTS Flat Trac then it is more then likely a very grippy, almost sand paper surface. I am in no way a tribology expert, so my knowledge of the exact mechanism of the rubber/road interface is limited to practical experience. If your tire data (which is on a surface not representative of actual tarmac) is telling you that your C.F. goes up with normal force, then you can go and draw whatever conclusions make sense to you. But it goes against every book, article and bit of data I have seen.

[Erik C]

After thinking about this....is it possible that your C.F. is increasing at a faster rate due to the increase in tire temp (due to higher loading), then it is decreasing due to load? Things that make you go, hmmmm..... http://fsae.com/groupee_common/emoticons/icon_confused.gif

www.adamaircraft.net (http://www.adamaircraft.net)

[Charlie]

It is possible, yet still has detrimental effects! The only possible gains from more weight are higher tire temps. You can get these using methods that have additional benefits!

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[woollymoof]

I've been reading this thread and SpeedRcr you are exactly right.

Someone mentioned earlier "all thing being equal", and they are right also. But all things aren't equal, so there's no point comparing.

We all know stiffer anti roll bars increase load transfer. Carrol Smith says to maximise corning acceleration at mid corner decrease your anti roll bar stiffness. He also says to maximise turn in (initial cornering acceleration)increase your antiroll bar stiffness.
A contradiction? Not really. On turn in the tyres are cold. Having stiffer antiroll bars increases load transfer to the outer tyre, speeding up the rate of temperature increase such that the tyre arrives at the optimal temperature faster and thus has a higher CoF. At midcorner the tyre is already at temp so a reduction in load will increase the CoF.

I think.

Cheers,

Kirk Veitch
Swinburne University of Technology

[Engelbert]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by vinHonda:
I don't think I'm contradicting Carrol Smith at all..... if anyone so graciously got to speak with him; he'd tell you to run your heaviest driver in skidpad! Especially on the Goodyear R65 and the Hoosier R25A!

We tested our tires at Smithers Scientific in Ravenna Ohio on a MTS Flat Trac tire testing machine. This is where we got our data.... wasn't hard work......just cost a crap load of money.

Vinh

University of Toronto Formula SAE Racing Team
http://www.fsae.utoronto.ca<HR></BLOCKQUOTE>

What surface do the tyres run on on the test machine ? What temps were run ? What speeds and slip angles ? I wouldnt mind learning more in this area. I wonder if any tyre gurus are reading this and laughing at us !!

If you have data and carrol smith on your side, then I spose there's no way of telling you otherwise. Good luck with your car, but I just cant accept it.

Also, you seem to be splitting your argument between:
a) tyre load effecting temperatures, and,
b) tyre/road interaction due to differnet loads

Yes both have an impact on friction levels, but you switch from one to the other whenever convenient for your argument, or so it seems.

I'd say the temp argument is lost to you (unless you are running in Detroit on ice, as charlie mentioned, but then, you might want to run bicycle rims to get the temps up enough in that case !)

The tyre/road cf might increase with normal load to a point, but I would expect that point to be very low, somewhere between Fn=0 up to when the entire contact patch is touching the road. Anything after that and friction is diverging.

This thread has definitely been interesting though, I'll give it that !

Sam.

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Charlie:
From _Tune to Win_:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The basic equation for cornering force:

F= (mass x velocity x velocity)/radius (*)

assures us that- all other things (especially tires) being equal, a light car will go around a given corner at a greater road speed than its heavier counterpart. <HR></BLOCKQUOTE>

He uses the analogy of a rock and string. The heavier the rock, the sooner the string will break. The heavier the car, the quicker the tires will lose grip. Yes, they have a better CF because of increased normal load. But the lateral force caused by vehicle mass, velocity, and radius will overcome the benefits of increased normal load and slightly better CF.<HR></BLOCKQUOTE>

F = CoF X m X g

subbing this back into * gives

CoF X g = v^2 / r

v^2 is proportional to CoF, and independant of mass. this means that any increase in CoF will result in a better (steady state) conering speed.

cheers for the help here Charlie, but am i right in this case?

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

[Charlie]

Sorry, I should have said lateral force not CF. CF is a ratio of your lateral and normal grip (in a corner steady state situation). When adding weight, your potential lateral grip increases, that grip increase is normal force X CF. If CF was constant throughout the range of normal forces we see, weight would not affect lateral force. As stated in all the resources I've seen, it drops with normal force.

I have not seen a decent arguement from Vin about why more weight works. Maybe he is being secretive, I would not fault him for that. But on the surface it seems like following data and testing results without knowing why.

Take a moment to analyze the public Goodyear data, especially nice becuase Vin mentioned the Goodyears as a specific tire with his characteristics:

13x6.5x20 R065, -4 degrees slip angle:

N: 100 lb
CF: 3.25

N: 250 lb
CF: 1.56

N: 400 lb
CF: 1.175

N: 550 lb
CF: 0.92

Lateral force has been confused with CF more than once in this thread, myself included. Our 04 Cheif Engineer and I put this together in 10 minutes, so it may be flawed, but I don't think the logic is.

As I said before, if there are gains seen from more weight, it surely is strictly a tire temp issue, and there are certainly better ways to acheive higher tire temps than ballast.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by vinHonda:
If you look at recent tire data on the Goodyear and the Hoosier that 'most of us' run..... the lateral forces peak out at quite high slip angles and higher vertical loads, to a point

...

My point is..... the tire makes its most grip at fairly high vertical loads before it drops off quite rapidly.

Vinh

University of Toronto Formula SAE Racing Team
http://www.fsae.utoronto.ca<HR></BLOCKQUOTE>

Charlie, i think thats Vinh's point. his tire testing (i think) suggested to him that peak CoF occurs at quite high loading, i would guess somewhere around 150lbs. im guessing this because off the top of my head, toronto's car weighed 400lbs.

but anyway, is that data that you posted all that you have, or did you read that off a graph with a higher definition? there is still a possibility that a 150lbs loading gives a higher CoF if what you have above is all the data. i know it sounds unlikely, and it goes against the books, but Vinh doesnt sound like he is pulling our legs. how did toronto do in the skidpan anyway? i know they won formula student overall, but my browser has packed it in so i cant see the rest of the results.

also, higher slip angles theoretically require higher load dont they? we normally turn at higher than 4 degrees dont we?

would help if Vinh would get on the forums again...

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

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by gug:
we normally turn at higher than 4 degrees dont we?
<HR></BLOCKQUOTE>

What does this have to do with slip angle?

Anyway, do the math, in a skidpad at, say, 1.3 G, what do you see at the outside tire(s)? We see a lot closer to 250 than 150. Maybe we have an insanely high CG? OU car isn't too terribly heavy (491 at comp, Torontos was 477 at FS if postings here are right)

The data I used was public, because otherwise people can't see for themselves. Do we have better resolution data? Not for the goodyears.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[gug]

sorry, i meant we normally see higher than 4 degrees of slip angle.

hehe, 400lbs is 180kgs. that does sound a bit too light. i really should learn what imperial units are...

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

[Schumi_Jr]

Toronto's car only weighs 400lb on a REALLY windy day http://fsae.com/groupee_common/emoticons/icon_wink.gif

Aaron Johnston
University of Waterloo FSAE

www.eng.uwaterloo.ca/~fsae (http://www.eng.uwaterloo.ca/~fsae)

[vinHonda]

Marion Pottinger is the Technical Director at Smithers Scientific....he is a tire guru and has tested everything from Nascar slicks to a Boeing 747's tires. He's been in the tire industry for over 25 years. They use sand paper that is specified by the NHTSA, National Highway Traffic Safety Administration to simulate tarmac. Marion says that a shift to parking lot tarmac should make little to no difference. I can't remember the grit number.....I have it in my notes somewhere. The tires were testing using normal tire testing protocol so we recorded temps etc. ourselves. Speeds/slip angles/inclination angles/vertical loads/camber sweeps/camber thrusts etc and all of their increments were determined by us and...... we went to the point to make the data very good. But again....tire data doesn't lie.

Temperatures are just an indicator. It's not really part of the argument..... they just indicate how well your tire is working. I apologize for being unclear.....this whole thread has sometimes been unclear! But very very interesting and a lot of great points!

It is correct to say that at about 1.3 G's... the outside front should see about 250-300lbs for a car weighing 450lbs or so.... with a fairly moderate bar. As to what slip angles the tires ACTUALLY run at when the car drives..... No clue!

It was our mistake for not building a 440lbs car this year!

Great thread boyz.

Vinh

P.S. Formula SAE entry fees will be $600 USD next year.

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[vinHonda]

C:\My Documents\MTS&Vinh.jpg

I've never uploaded an image before......

I hope this works!

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[vinHonda]

I guess I'm an idiot.

LOL! Very true Aaron! Like Claude Rouelle..... I think I'll remember and be telling that story til the day I die!

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[fade]

you have to upload the image first you can do that here (http://www.picturetrail.com/)

[inamo]

So was there a suggestion that some teams are running on their own unique compounds? How do you work out what you need and how much does it cost? I'm just curious - don't you get hammered in the cost event?

To add another thought to the thread, I thought for maximum grip you needed about 10% slip to get the heat into the tyres, or something odd like that - I'm not a handling guru!

[zorr0]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by woollymoof:
We all know stiffer anti roll bars increase load transfer. Carrol Smith says to maximise corning acceleration at mid corner decrease your anti roll bar stiffness. He also says to maximise turn in (initial cornering acceleration)increase your antiroll bar stiffness.
A contradiction? Not really. On turn in the tyres are cold. Having stiffer antiroll bars increases load transfer to the outer tyre, speeding up the rate of temperature increase such that the tyre arrives at the optimal temperature faster and thus has a higher CoF. At midcorner the tyre is already at temp so a reduction in load will increase the CoF.
<HR></BLOCKQUOTE>

Do you, perchance, have a subscription to racecar engineering? http://fsae.com/groupee_common/emoticons/icon_wink.gif

In a related vein, if you look at the Goodyear data and compare the 6.5"-13"s with the 8"-13"s, it appears that the 8"s struggle. I called GY and they told me that temp is not logged during the testing and that this discrepancy was because the 6.5 heated up faster. This makes me question basically all of that data.



http://www.auburn.edu/~zornmat/eagleside.jpg

http://www.auburn.edu/~zornmat/pics/img_0399.jpg]

[Sam Zimmerman]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Adding weight does increase lateral forces..... don't you guys pick your heaviest drivers for the skidpad?<HR></BLOCKQUOTE>

SVSU did a factorial experiment which raised this specific question (among others.) I don't have the SAE paper with me but a quick search will find it. They found that more weight had a big influence on skid pad times, raising the times. Of course this could be for a variety of reasons but I have to say that I am with Charlie on this one.

Sam Zimmerman
Vandals Racing (http://www.uidaho.edu/~racing)
2002-2003 Team Leader

[vinHonda]

I've spoken to, seen and felt unique tire compounds from at least 2 other teams. They are very interesting.

As for cost, they are the same as any other racing tire.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[woollymoof]

zorr0, yep!

Cheers,

Kirk Veitch
Swinburne University of Technology

[Engelbert]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by woollymoof:
I've been reading this thread and SpeedRcr you are exactly right.

Someone mentioned earlier "all thing being equal", and they are right also. But all things aren't equal, so there's no point comparing.

We all know stiffer anti roll bars increase load transfer. Carrol Smith says to maximise corning acceleration at mid corner decrease your anti roll bar stiffness. He also says to maximise turn in (initial cornering acceleration)increase your antiroll bar stiffness.
A contradiction? Not really. On turn in the tyres are cold. Having stiffer antiroll bars increases load transfer to the outer tyre, speeding up the rate of temperature increase such that the tyre arrives at the optimal temperature faster and thus has a higher CoF. At midcorner the tyre is already at temp so a reduction in load will increase the CoF.

I think.

Cheers,

Kirk Veitch
Swinburne University of Technology<HR></BLOCKQUOTE>

Are you saying the tyre temp changes radically between corner entry and mid corner (for a tyre that is at operating temperature) ?

Or are you referring to a cold tyre entering the first corner of an event ?

Does a degree here or there make much difference ? I didn't think it would.

Sam
2001 UQ FSAE

[woollymoof]

As far as I know the temp does change a far bit between corner entry and exit. There is a hell of a lot of energy going into these tyres. Whether they chnage radically, probably not, but I guess it depends on the length of the corner.

A degree here or there might not make that much difference, but five might. This is all just speculation though, I don't have any tyre data.

Maybe someone out there could have a look at some CF vs temp graphs and see what difference there is if we change the temp by 1 or 5 degrees.

Cheers,

Kirk Veitch
Swinburne University of Technology

[gug]

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 during a corner. you guys think this happens in fsae? can people with tire data conclusively say that it does or doesnt?

there is some calculations in there about the energy dissapated into the tire which would be interesting to see for a fsae car. but its all in bloody imperial measurements, and i cant get my head around them this early in the morning.

there is also a list of references, anyone who has sae papers <UL TYPE=SQUARE> <LI>sae 2002-01-3302, dynamic traction characteristics of tires, by chuck hallum <LI>sae 982830 understanding race tires, chuck hallum <LI>sae 2000-01-3571, how to work race tires, chuck hallum [/list]
if anyone has these and wants to email me them i would be most grateful.

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

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by gug:
It basically said that a tire's CoF decreases with increasing load because the tire overheats during a corner. you guys think this happens in fsae? can people with tire data conclusively say that it does or doesnt?
<HR></BLOCKQUOTE>

No, I don't think that happens in FSAE. Can people with tire data say? No, because tire data never includes temperature data (not that I've seen. Only 'ambient') This is the major problem. I think the major reason you might see an increase in CoF from more normal load is simply tire temps! More than one way to skin a cat... http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Scott Wordley]

I guess you'd need racks of tire pyros and a whole lot of other on car logging to look at this sort of stuff.

Have any FSAE teams gone this far?

Regards,

Scott Wordley

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

[George]

We're doing that this year, three infra red tyre temps sensors mounted on a bracket out in front of the wheel for real time temp logging. That and a whole host of other stuff. I'll tell you in ~1.5 months how usefully it all is once we have the car together, tested, data aq system working and we're finally getting some useful info from it.

UQ Racing Team Leader 2003
www.uq.edu.au/fsae (http://www.uq.edu.au/fsae)

[El Mug]

I´m curius about those infrared sensors you are planning to use to get tire temp. I have been looking around trying to find a cheap infrared sensor, but the ones that i have found are all really expensives.

[George]

Yeah Omega OS36-APC (Have to double check, not in the workshop at the moment) with the OSM101 analogue convertor.

http://www.omega.com/toc_asp/subsectionSC.asp?subsection=J09&book=Temperature

They were AUD$300 each, we have four, three for tire temps and one for brake temp.

These were the cheapest we could find with an analogue out so we can plug into the data aq box.

UQ Racing Team Leader 2003
www.uq.edu.au/fsae (http://www.uq.edu.au/fsae)

[san]

hi..
i saw all the posts here . its really great to think of a car that weighs only 135 kgs..
so, am curious to 've a look at the picture of the car..
can someone pl post the picture of the delft car???

[Chris_S]

http://www.cosic.org.uk/galleryv2/main.php?g2_itemId=5038
http://www.cosic.org.uk/galleryv2/main.php?g2_itemId=5044
http://www.cosic.org.uk/galleryv2/main.php?g2_itemId=5047
http://www.cosic.org.uk/galleryv2/main.php?g2_itemId=5050
http://www.cosic.org.uk/galleryv2/main.php?g2_itemId=5053
http://www.cosic.org.uk/galleryv2/main.php?g2_itemId=5056

http://www.formula.stadia.fi/FS06/slides/FS06_006.html
http://static.flickr.com/70/197854947_0842be5b41.jpg?v=0
http://static.flickr.com/68/197843558_38fe0bcfb7.jpg?v=0
http://static.flickr.com/72/197843550_e667580aeb.jpg?v=0
http://static.flickr.com/71/197843504_b4dfca2afa.jpg?v=0
http://static.flickr.com/76/197843501_0bdf7543ec.jpg?v=0
http://static.flickr.com/61/197843472_1927d23e6c.jpg?v=0

http://formula.altronix.se/England%20July%202006/Other%.../slides/P7075687.JPG (http://formula.altronix.se/England%20July%202006/Other%20teams/slides/P7075687.JPG)
http://formula.altronix.se/England%20July%202006/Other%.../slides/P7075682.JPG (http://formula.altronix.se/England%20July%202006/Other%20teams/slides/P7075682.JPG)
http://formula.altronix.se/England%20July%202006/Other%.../slides/P7075681.JPG (http://formula.altronix.se/England%20July%202006/Other%20teams/slides/P7075681.JPG)
http://formula.altronix.se/England%20July%202006/Other%.../slides/P7075679.JPG (http://formula.altronix.se/England%20July%202006/Other%20teams/slides/P7075679.JPG)

http://www.formulastudent.strath.ac.uk/data/media/photo...-others/IMG_3072.jpg (http://www.formulastudent.strath.ac.uk/data/media/photos/2005-2006/2006-07-06-competition-others/IMG_3072.jpg)
http://www.formulastudent.strath.ac.uk/data/media/photo...-others/IMG_3075.jpg (http://www.formulastudent.strath.ac.uk/data/media/photos/2005-2006/2006-07-06-competition-others/IMG_3075.jpg)
http://www.formulastudent.strath.ac.uk/data/media/photo...-others/IMG_3074.jpg (http://www.formulastudent.strath.ac.uk/data/media/photos/2005-2006/2006-07-06-competition-others/IMG_3074.jpg)
http://www.formulastudent.strath.ac.uk/data/media/photo...-others/IMG_3076.jpg (http://www.formulastudent.strath.ac.uk/data/media/photos/2005-2006/2006-07-06-competition-others/IMG_3076.jpg)

[drivetrainUW-Platt]

What are those flex joints for the driveshafts made out of? Any part numbers/manufacturers?

[Peter]

http://www.spinningcomposites.com/

Peter
Delft

[Smeagle]

I think UNSW have been using similar ones for a few years now without problems.

[Nihal]

How do they take up plunge? It appears on that site that it just flexes conically like a bellville spring or something.

[kracer]

Is this company, spinning-composites, still in business?

What is the price of their smallest coupling?

[Tom W]

Yes

Lots. The last time we bought them was 08 and from memory it was about £90 for each coupling.