1995 McLaren - WOW
01-16-2003, 05:36 AM
#12
WSB,
LOL, I know, it's pretty hard to support something entirely on magazine racing. That said, when it comes to the McLaren F1, that's about all you CAN base it on - they're not exactly available for test drives or purchase on a regular basis.
Still, I'm wondering, why such low cornering limits? I thought the F1 used/uses the Pirelli P-Zero Assymmetricos, which are awfully high-tech tires (I've seen them on Lamborghinis as well). You'd think the cornering limits would be higher. Integra Type-Rs corner that well (and better) in every test I've seen (and they are quite balanced in doing so).
Anyone else have comments?
LOL, I know, it's pretty hard to support something entirely on magazine racing. That said, when it comes to the McLaren F1, that's about all you CAN base it on - they're not exactly available for test drives or purchase on a regular basis.
Still, I'm wondering, why such low cornering limits? I thought the F1 used/uses the Pirelli P-Zero Assymmetricos, which are awfully high-tech tires (I've seen them on Lamborghinis as well). You'd think the cornering limits would be higher. Integra Type-Rs corner that well (and better) in every test I've seen (and they are quite balanced in doing so).
Anyone else have comments?
01-16-2003, 11:04 AM
#13
Good point about magazine racing of the F1 
The F1 does use the Goodyear Tires, at least in OEM form.
I didn't really want to get into a dissertation on why the F1 might have such low skidpad numbers, but since you asked:
First off, the skidpad does not measure cornering limits. It primarily measures lateral grip of the tires, and to a lesser degree front/rear balance. From this, the cornering ability of a vehicle can be inferred. The skidpad offers nothing in terms of absolutes unless you are comparing different tires on the same car.
Let's look at how this number is found. On a level, smooth chunk of asphalt, a large circle is drawn (300' diameter is common for passenger cars and light trucks, but other sizes can be used). The test car is centered on the circle, and the driver drives the car in a circle as fast as the car permits. Drive around the circle a couple times at that speed, recording the lateral acceleration, and take the average of the lateral acceleration recorded during 2-3 laps, then do it going the other way. During the testing, at any time, at least one tire's grip is (nearly) 100% saturated. If not, the driver isn't going fast enough. In a perfectly balanced car, the driver would be able to attain a speed such that all 4 tires are at the saturation point at the same time. More often than not, the front outside tire saturates first - the car understeers. This is true even in rear drive sports cars. An example of a car that saturates the outside rear would be the Dodge Viper - excessive power to the rear wheels and plenty of grip up front. Let's look at 3 cars, only 2 of which I'm familiar with (darn)
McLaren F1 (M/R): 0.86g
Honda S2000 (F/R): 0.90g
Jeep Grand Cherokee (F/R): 0.76g
Now, based on this, the Grand Cherokee is 88% as good of a cornering vehicle as the F1. This is obviously NOT true. Likewise, the S2000 is actually 5% better than the F1 - possible but highly unlikely (I have faith that McLaren with a $1 million price tag can outdo Honda with a $33k price tag). If you were to see these 3 vehicles on the skid pad, you'd see very large differences in what the cars were doing. The S2000 would be teetering back and forth between understeer and oversteer, the F1 (I think) would be at the edge of oversteering, and the Jeep would be at the brink of plowing. Remember, as soon as one wheel saturates, the vehicle will lose it's circular path. The goal is to stay just below this saturation point. Another aspect to consider is the ease of attaining these numbers. The F1, with it's low yaw moment, would likely be very smooth to this point, while the S2000 would be a handful (as many of us can attest to). However, because the S2000 is nearly saturating both the outside tires, and not just the rear, it achieves a higher lateral acceleration. The Jeep is very uneasy at this point, due to the high levels of load transfer from body roll.
To bring this back to cornering limits, I'll say this - at the speed you drive a Grand Cherokee on a skidpad to achieve 0.76g (about 42-43 mph, if memory serves), any significant wheel input would result in a rollover. For the F1 and S2000, a comparitively painless spin would result. On a track, where rapid dynamic inputs are used, the tires pure lateral grip is only one factor. Typically you're either braking or accelerating as well, so the tires' longitudinal grip comes into play as well. Additionally, spring rates, track width, mass and CG height, and countless other factors all come into play. Thus, the skidpad number is merely a fleeting glimpse into a cars actual handling. The slalom is similarly flawed, although it takes into account more of the factors I mentioned.
Lastly - How to solve the F1's low (paper) cornering limits? If my assumptions are correct (oversteer bias), options would include going from a P235/P315 combo to a P235/P335 combo, decreasing the 45 tire profile to 35 or 40, or increasing the rear camber. Any of these would probably put it into Enzo territory (1 g) on paper, possibly at the expense of overall handling (and decreasing the profile would definately be at the expense of the driver/passengers). In the real world, the F1 is fairly balanced with a tendancy towards power-on oversteer (as any supercar should be). Lastly, I'm not sure about the tires - the Koenigsegg CC achieves 1.15g using the same Goodyear Eagle F1 tires.
Hope that helps. I can dig up a few reference books if you want to dig more.
The F1 does use the Goodyear Tires, at least in OEM form.
I didn't really want to get into a dissertation on why the F1 might have such low skidpad numbers, but since you asked:
First off, the skidpad does not measure cornering limits. It primarily measures lateral grip of the tires, and to a lesser degree front/rear balance. From this, the cornering ability of a vehicle can be inferred. The skidpad offers nothing in terms of absolutes unless you are comparing different tires on the same car.
Let's look at how this number is found. On a level, smooth chunk of asphalt, a large circle is drawn (300' diameter is common for passenger cars and light trucks, but other sizes can be used). The test car is centered on the circle, and the driver drives the car in a circle as fast as the car permits. Drive around the circle a couple times at that speed, recording the lateral acceleration, and take the average of the lateral acceleration recorded during 2-3 laps, then do it going the other way. During the testing, at any time, at least one tire's grip is (nearly) 100% saturated. If not, the driver isn't going fast enough. In a perfectly balanced car, the driver would be able to attain a speed such that all 4 tires are at the saturation point at the same time. More often than not, the front outside tire saturates first - the car understeers. This is true even in rear drive sports cars. An example of a car that saturates the outside rear would be the Dodge Viper - excessive power to the rear wheels and plenty of grip up front. Let's look at 3 cars, only 2 of which I'm familiar with (darn)
McLaren F1 (M/R): 0.86g
Honda S2000 (F/R): 0.90g
Jeep Grand Cherokee (F/R): 0.76g
Now, based on this, the Grand Cherokee is 88% as good of a cornering vehicle as the F1. This is obviously NOT true. Likewise, the S2000 is actually 5% better than the F1 - possible but highly unlikely (I have faith that McLaren with a $1 million price tag can outdo Honda with a $33k price tag). If you were to see these 3 vehicles on the skid pad, you'd see very large differences in what the cars were doing. The S2000 would be teetering back and forth between understeer and oversteer, the F1 (I think) would be at the edge of oversteering, and the Jeep would be at the brink of plowing. Remember, as soon as one wheel saturates, the vehicle will lose it's circular path. The goal is to stay just below this saturation point. Another aspect to consider is the ease of attaining these numbers. The F1, with it's low yaw moment, would likely be very smooth to this point, while the S2000 would be a handful (as many of us can attest to). However, because the S2000 is nearly saturating both the outside tires, and not just the rear, it achieves a higher lateral acceleration. The Jeep is very uneasy at this point, due to the high levels of load transfer from body roll.
To bring this back to cornering limits, I'll say this - at the speed you drive a Grand Cherokee on a skidpad to achieve 0.76g (about 42-43 mph, if memory serves), any significant wheel input would result in a rollover. For the F1 and S2000, a comparitively painless spin would result. On a track, where rapid dynamic inputs are used, the tires pure lateral grip is only one factor. Typically you're either braking or accelerating as well, so the tires' longitudinal grip comes into play as well. Additionally, spring rates, track width, mass and CG height, and countless other factors all come into play. Thus, the skidpad number is merely a fleeting glimpse into a cars actual handling. The slalom is similarly flawed, although it takes into account more of the factors I mentioned.
Lastly - How to solve the F1's low (paper) cornering limits? If my assumptions are correct (oversteer bias), options would include going from a P235/P315 combo to a P235/P335 combo, decreasing the 45 tire profile to 35 or 40, or increasing the rear camber. Any of these would probably put it into Enzo territory (1 g) on paper, possibly at the expense of overall handling (and decreasing the profile would definately be at the expense of the driver/passengers). In the real world, the F1 is fairly balanced with a tendancy towards power-on oversteer (as any supercar should be). Lastly, I'm not sure about the tires - the Koenigsegg CC achieves 1.15g using the same Goodyear Eagle F1 tires.
Hope that helps. I can dig up a few reference books if you want to dig more.
01-17-2003, 02:37 AM
#14
No, that's plenty good - that's more what I was looking for.
01-17-2003, 05:06 PM
#17
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Hell Funcar, it doesn't even have a radio. Maybe you are expecting too much for your $1,000,000.
EDIT: Oops, you meant a RADIO radio heh. You are right.
That video is just amazing. I like how the guy is talking to the camera as he's flying through corners and gunning it down the straights at 150+.
