8 replies to this topic

[Alex]

Latteral acceleration posted on the skidpad is very popular in today's car mags. How much G's do you think an F1 car would get if you were to put it on the skidpad with a maximum dowforce setup? 4,5...?

Most good road cars are able to post 0.75-0.85. Some even above 0.9 g. But my question is the following...Why are some cars rated at 1g or even more when it is known that road cars have no aero grip, mechanical only? You can't go over 1g with mechanical grip only right?

[Paolo]

Yes, you can.
As a rule of thumb, you'll get as many g as your tires' friction coefficient. So, if yoi use Formula 1 tires (say 1.8 coefficient) on your road car, you'll go very near to 1.8 on the skidpad, without downforce.
Of course your performance will be worsened by suspension problems and so on, but still you'll make a lot more than 1 g.

[goGoGene]

standard co-eff of friction max's out at 1.0, physics 101.

You need to get into adhesion, i.e. tires acting like glue, before you can go >1.0

this can happen with really soft tires when warm, but not for street cars, the tires would be good for an hour or two, then you need a new pair.

ggg

[blkirk]

Coefficients of Static Friction

1.40 Silver on Silver
1.35 Aluminum on Aluminum
1.20 Platinum on Platinum
1.00 Copper on Copper
1.00 Iron on Iron
0.80 Steel on Steel
0.70 Nickel on Nickel
0.60 Brick on Wood
0.35 Brass on Steel
0.04 Teflon on Steel
1 - 4 Solids on Rubber

From Machinery's Handbook, 25th Edition, Industrial Press, 1996.

ggg is correct about wear. The really sticky rubber compounds tend to not last very long. F1 tires only last ~150-200 km.

F1 cars on a skid pad...
Traditional skid pads are quite small (100 ft, 30 m diameter) compared to the big sweeping turns on some F1 tracks. You would need a larger diameter skid pad for the F1 car to reach the speeds needed to generate enough downforce to pull 4.5 g. On a traditional skid pad, 4.5 g is a measly 92 km/h (57 mph). A 60 m pad would probably do the trick.

[PDA]

It would need to be a very big skid pan, as the very high downforce needed to achieve those 4 g cornering speeds requires speeds in excess of 150 mph. The Road and track analysyse of the Jaguar at Indianapolis shows 2g or less at the lower speed corners (50 - 80 mph)

[kober]

IIRC there's big skidpad used also for F1 testing at the Ferrari's testing circuit, Fiorano.

[Amadeus]

Originally posted by Alex
...Why are some cars rated at 1g or even more when it is known that road cars have no aero grip, mechanical only? You can't go over 1g with mechanical grip only right?

What makes you say that road legal cars have no aero grip? I'm eating lunch and being lazy so I don't have the numbers, but the new Ferrari has an aero undertray that generates substatial downforce, the Porsche 911 has the speed activated 'whale tail' and all the frippieries on cars like the Skyline do generate downforce - not F1 levels, but downforce all the same.

[Mellon]

Or you could take a look on a Viper. You'll realize it's rear 'bumper' is quite high because of the diffuser.

[JamesW]

Originally posted by PDA
The Road and track analysyse of the Jaguar at Indianapolis shows 2g or less at the lower speed corners (50 - 80 mph)

Where did you get this information from mate? Sounds as though it could be useful for me...

Thanks

James