Re: Canned Spins, Bollocks mate.

> Compared to driving at high speed with the downforce, DEFINATELY yes. > However, modern F-1 tires (not sure about the new grooved ones) arecapable of > upwards of 1.8 g's cornering at light load. It's probably safe to saythat a > modern F-1 car could still pull 1.5 g's or so through a corner if youremoved > the wings and all downforce stuff. Your acceleration to the centre of the corner (i.e. G force) is proportional to the grip of the car. If you have NO downforce, the only force keeping you on the road is the weight of the car. The maximum cornering 'force' is therefore the same ammount. F=ma Hence, only ever 1 g. Doug

Requested dissection #1 :-) >They >reckon you could drive one of these things on the ceiling because of the >speed and downforce combination True (if you can fuel it and stay in your seat, of course) :-). F-1 cars have been known to generate upwards of 4.5 g's cornering acceleration with maximum downforce, if I'm not mistaken. That's enough to not only drive upside down, but drive upside down and run a skidpad on the ceiling at 2-3 g's. Better wear your harness! >If you took the wings off these cars >cornering would be seriously difficult (obviously) even at low speeds. Compared to driving at high speed with the downforce, DEFINATELY yes. However, modern F-1 tires (not sure about the new grooved ones) are capable of upwards of 1.8 g's cornering at light load. It's probably safe to say that a modern F-1 car could still pull 1.5 g's or so through a corner if you removed the wings and all downforce stuff. >Most low speed spins are caused by over acceleration at a >time when downforce is not working at it`s true potential.... Definately true, and being in a low gear on top of this doesn't help either. Indycars (not sure about F-1), should be able to spin their rear tires through 80+mph or so, even when they aren't in a corner. >.... people surely >don`t think that upon loosing control putting your foot down and turning >into it is going to help a recovery. Taking your foot off the gas and >fighting it is what is called for, remembering that sharp movements of the >wheel will result in sharp movements of the car which will alter the cars >sensitive characteristics. Bingo. I'm not sure about the '67 F-1 cars, but I suspect a modern car has a much lower polar moment of inertia. (For those who don't know, imagine spinning a dumbell with the weights far apart vs. close to the center, then changing the spin direction as quickly as you can. Same weight, but it's a lot easier to change directions when the weights are in the middle). Another thing folks may keep in mind are the current F-1 tires vs. '67. They're stickier, but that's not the point, really. A modern F-1 tire generates it's peak force at a very small slip angle compared to the '67's, probably. Everybody know how the GPL cars will rotate sideways pretty far and perhaps wobble, then travel at a pretty good angle? I'd expect the same basic behavior from an F-1 sim, but the angle should be much smaller (if noticable at all, we're talking 3-5 degrees probably), and the short wobble should be much more rapid and halt very quickly, if there's a perceptable one at all. This should still be apparent at speeds of maybe 50-70 mph or less. One more thing, modern F-1 tires MAY have a tendency to drop peak force more quickly after the optimum slip has been reached than a '67 tire (if a '67 tire did this at all). This, on top of lower polar moment of inertia and higher grip levels, should give a more snappy feel to the modern car. I forgot where I was going with this, but that's a long winded enough know-it-all reply for me today! Todd Wasson ^--- Never played GP3

I posted this earlier on a thread concerning canned spins, but I need a good flaming anyway so I thought in case anyone hadn`t seen it I`d put here aswell, so disect away and please forward whats left to my family. Well, I have read all this thread with a grin on my face, some say canned and others not. My personal opinion is not. People have made comments on the laws of physics which are the thing in question here. F1 cars are an individual breed, they rely (especially at present with the grooved tyre regulatons) mainly on the downforce given by the front and rear wings. They reckon you could drive one of these things on the ceiling because of the speed and downforce combination. If you took the wings of these cars cornering would be seriously difficult (obviously) even at low speeds. If you watch TV coverage of the sport, which I have been lucky enough to see here in the UK from being a young lad to a 30 year old man on a regular basis, you will have seen the many accidents and unfortunate fatalaties that have occured in the sport. Most of these occur because the driver is on the absoloute limit, obviously only a fraction of speed , late braking etc.. takes you beyond that point. You find that That the cars just go ping!, and there out of control, spinning away or just sliding sideways at some serious velocity leaving the driver helpless and at the mercy of fate. These cars are not designed to be powerslided it`s not efficient, it costs laptime, there designed to stick by downforce. When downforce is gone you are usually travelling at a silly speed ( hair on fire ) thus regaining control is not easy. I`ve seen some good recoveries, but they usually entailed spinning 540 degrees heading off backwards on the grass, track or wahtever with the driver being able to get the car pointed in the right direction and get away without hitting anything and without loosing much time ( oh! being alive aswell). I`ve heard people give it the old " it`s no GPL " routine, and I couldn`t agree more. It is NOT GPL,as in it is not trying to replicate hoe cars back then handled, It is trying to replicate how cars handled in 1998. I personally like the physics model, the best way to regain control of a lost car is too bleed off the speed, try to get it back within the limit, I think this is correct. Most low speed spins are caused by over acceleration at a time when downforce is not working at it`s true potential, people surely don`t think that upon loosing control putting your foot down and turning into it is going to help a recovery. Taking your foot off the gas and fighting it is what is called for, remembering that sharp movements of the wheel will result in sharp movements of the car which will alter the cars sensitive characteristics. Gp3 seems to give a good idea of how things work in a modern day F1 car, bearing in mind it`s not a easy thing to model. Shit I didn`t intend to waffle on that long, anyway thats my humble take on the handling. Snake.

I propably had the following to say about the control of the car in spins, so what gives if you can get the car back in control if you slam the brakes real hard, realistic? I dont think so. Marko Snake <[email hidden]> wrote in message news:eQni5.8778$[email hidden]... > I posted this earlier on a thread concerning canned spins, but I need agood > flaming anyway so I thought in case anyone hadn`t seen it I`d put here > aswell, so disect away and please forward whats left to my family. > > > Well, I have read all this thread with a grin on my face, some say canned > and others not. My personal opinion is not. People have made comments onthe > laws of physics which are the thing in question here. F1 cars are an > individual breed, they rely (especially at present with the grooved tyre > regulatons) mainly on the downforce given by the front and rear wings.They > reckon you could drive one of these things on the ceiling because of the > speed and downforce combination. If you took the wings of these cars > cornering would be seriously difficult (obviously) even at low speeds. > If you watch TV coverage of the sport, which I have been lucky enough tosee > here in the UK from being a young lad to a 30 year old man on a regular > basis, you will have seen the many accidents and unfortunate fatalatiesthat > have occured in the sport. > Most of these occur because the driver is on the absoloute limit,obviously > only a fraction of speed , late braking etc.. takes you beyond that point. > You find that That the cars just go ping!, and there out of control, > spinning away or just sliding sideways at some serious velocity leavingthe > driver helpless and at the mercy of fate. These cars are not designed tobe > powerslided it`s not efficient, it costs laptime, there designed to stickby > downforce. When downforce is gone you are usually travelling at a silly > speed ( hair on fire ) thus regaining control is not easy. I`ve seen some > good recoveries, but they usually entailed spinning 540 degrees headingoff > backwards on the grass, track or wahtever with the driver being able toget > the car pointed in the right direction and get away without hittinganything > and without loosing much time ( oh! being alive aswell). > I`ve heard people give it the old " it`s no GPL " routine, and I couldn`t > agree more. It is NOT GPL,as in it is not trying to replicate hoe carsback > then handled, It is trying to replicate how cars handled in 1998. I > personally like the physics model, the best way to regain control of alost > car is too bleed off the speed, try to get it back within the limit, Ithink

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> this is correct. Most low speed spins are caused by over acceleration at a > time when downforce is not working at it`s true potential, people surely > don`t think that upon loosing control putting your foot down and turning > into it is going to help a recovery. Taking your foot off the gas and > fighting it is what is called for, remembering that sharp movements of the > wheel will result in sharp movements of the car which will alter the cars > sensitive characteristics. > Gp3 seems to give a good idea of how things work in a modern day F1 car, > bearing in mind it`s not a easy thing to model. > > Shit I didn`t intend to waffle on that long, anyway thats my humble take

on > the handling. > > Snake. > > >

Oh...aha...I meant...that....you know....heck, I just wasn't expecting it do that. Could be that I'm comparing it to GPL... Marko Alan <[email hidden]> wrote in message news:[email hidden]...

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> Besides the fact that JV used this very technique to control a spin at > Canada to good effect? > > Alan > > Marko Aaltonen wrote: > > > > I propably had the following to say about the control of the car in

spins, > > so what gives if you can get the car back in control if you slam thebrakes

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> > real hard, realistic? I dont think so. > > > > Marko > > > > Snake <[email hidden]> wrote in message > > news:eQni5.8778$[email hidden]... > > > I posted this earlier on a thread concerning canned spins, but I need

a > > good > > > flaming anyway so I thought in case anyone hadn`t seen it I`d puthere > > > aswell, so disect away and please forward whats left to my family. > > > > > > > > > Well, I have read all this thread with a grin on my face, some saycanned > > > and others not. My personal opinion is not. People have made commentson > > the > > > laws of physics which are the thing in question here. F1 cars are an > > > individual breed, they rely (especially at present with the groovedtyre > > > regulatons) mainly on the downforce given by the front and rear wings. > > They > > > reckon you could drive one of these things on the ceiling because ofthe > > > speed and downforce combination. If you took the wings of these cars > > > cornering would be seriously difficult (obviously) even at low speeds. > > > If you watch TV coverage of the sport, which I have been lucky enoughto > > see > > > here in the UK from being a young lad to a 30 year old man on aregular > > > basis, you will have seen the many accidents and unfortunatefatalaties > > that > > > have occured in the sport. > > > Most of these occur because the driver is on the absoloute limit, > > obviously > > > only a fraction of speed , late braking etc.. takes you beyond thatpoint. > > > You find that That the cars just go ping!, and there out of control, > > > spinning away or just sliding sideways at some serious velocityleaving > > the > > > driver helpless and at the mercy of fate. These cars are not designedto > > be > > > powerslided it`s not efficient, it costs laptime, there designed tostick > > by > > > downforce. When downforce is gone you are usually travelling at asilly > > > speed ( hair on fire ) thus regaining control is not easy. I`ve seensome > > > good recoveries, but they usually entailed spinning 540 degreesheading > > off > > > backwards on the grass, track or wahtever with the driver being ableto > > get > > > the car pointed in the right direction and get away without hitting > > anything > > > and without loosing much time ( oh! being alive aswell). > > > I`ve heard people give it the old " it`s no GPL " routine, and Icouldn`t

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> > > agree more. It is NOT GPL,as in it is not trying to replicate hoe cars > > back > > > then handled, It is trying to replicate how cars handled in 1998. I > > > personally like the physics model, the best way to regain control of a > > lost > > > car is too bleed off the speed, try to get it back within the limit, I > > think > > > this is correct. Most low speed spins are caused by over acceleration

at a > > > time when downforce is not working at it`s true potential, peoplesurely > > > don`t think that upon loosing control putting your foot down andturning > > > into it is going to help a recovery. Taking your foot off the gas and > > > fighting it is what is called for, remembering that sharp movements ofthe > > > wheel will result in sharp movements of the car which will alter thecars > > > sensitive characteristics. > > > Gp3 seems to give a good idea of how things work in a modern day F1car, > > > bearing in mind it`s not a easy thing to model. > > > > > > Shit I didn`t intend to waffle on that long, anyway thats my humbletake

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> > on > > > the handling. > > > > > > Snake. > > > > > > > > >

Besides the fact that JV used this very technique to control a spin at Canada to good effect? Alan Marko Aaltonen wrote:

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> > I propably had the following to say about the control of the car in spins, > so what gives if you can get the car back in control if you slam the brakes > real hard, realistic? I dont think so. > > Marko > > Snake <[email hidden]> wrote in message > news:eQni5.8778$[email hidden]... > > I posted this earlier on a thread concerning canned spins, but I need a > good > > flaming anyway so I thought in case anyone hadn`t seen it I`d put here > > aswell, so disect away and please forward whats left to my family. > > > > > > Well, I have read all this thread with a grin on my face, some say canned > > and others not. My personal opinion is not. People have made comments on > the > > laws of physics which are the thing in question here. F1 cars are an > > individual breed, they rely (especially at present with the grooved tyre > > regulatons) mainly on the downforce given by the front and rear wings. > They > > reckon you could drive one of these things on the ceiling because of the > > speed and downforce combination. If you took the wings of these cars > > cornering would be seriously difficult (obviously) even at low speeds. > > If you watch TV coverage of the sport, which I have been lucky enough to > see > > here in the UK from being a young lad to a 30 year old man on a regular > > basis, you will have seen the many accidents and unfortunate fatalaties > that > > have occured in the sport. > > Most of these occur because the driver is on the absoloute limit, > obviously > > only a fraction of speed , late braking etc.. takes you beyond that point. > > You find that That the cars just go ping!, and there out of control, > > spinning away or just sliding sideways at some serious velocity leaving > the > > driver helpless and at the mercy of fate. These cars are not designed to > be > > powerslided it`s not efficient, it costs laptime, there designed to stick > by > > downforce. When downforce is gone you are usually travelling at a silly > > speed ( hair on fire ) thus regaining control is not easy. I`ve seen some > > good recoveries, but they usually entailed spinning 540 degrees heading > off > > backwards on the grass, track or wahtever with the driver being able to > get > > the car pointed in the right direction and get away without hitting > anything > > and without loosing much time ( oh! being alive aswell). > > I`ve heard people give it the old " it`s no GPL " routine, and I couldn`t > > agree more. It is NOT GPL,as in it is not trying to replicate hoe cars > back > > then handled, It is trying to replicate how cars handled in 1998. I > > personally like the physics model, the best way to regain control of a > lost > > car is too bleed off the speed, try to get it back within the limit, I > think > > this is correct. Most low speed spins are caused by over acceleration at a > > time when downforce is not working at it`s true potential, people surely > > don`t think that upon loosing control putting your foot down and turning > > into it is going to help a recovery. Taking your foot off the gas and > > fighting it is what is called for, remembering that sharp movements of the > > wheel will result in sharp movements of the car which will alter the cars > > sensitive characteristics. > > Gp3 seems to give a good idea of how things work in a modern day F1 car, > > bearing in mind it`s not a easy thing to model. > > > > Shit I didn`t intend to waffle on that long, anyway thats my humble take > on > > the handling. > > > > Snake. > > > > > >

On Fri, 4 Aug 2000 13:46:52 +0300, "Marko Aaltonen" <[email hidden]> wrote: >Oh...aha...I meant...that....you know....heck, I just wasn't expecting it do >that. Could be that I'm comparing it to GPL... Then again, the tyres and subsequently the mechanical grip between '68 GP cars and '98 GP cars is like comparing apples with oranges.

That works in GPL as well ;) -- Ian Parker "Ambition is a poor excuse for not having sense enough to be lazy." <email invalid due to spam> Marko Aaltonen <[email hidden]> wrote in message news:8me70k$be8$[email hidden]... > Oh...aha...I meant...that....you know....heck, I just wasn't expecting it do > that. Could be that I'm comparing it to GPL... > > Marko > Alan <[email hidden]> wrote in message > news:[email hidden]... > > Besides the fact that JV used this very technique to control a spin at > > Canada to good effect? > > > > Alan > > > > Marko Aaltonen wrote: > > > > > > I propably had the following to say about the control of the car in > spins, > > > so what gives if you can get the car back in control if you slam the > brakes > > > real hard, realistic? I dont think so. > > > > > > Marko

On Fri, 4 Aug 2000 15:40:54 +0100, "Ian P" <[email hidden]> wrote: >> > > so what gives if you can get the car back in control if you slam the >> > > brakes real hard, realistic? I dont think so. >That works in GPL as well ;) Yes, I've found the best way to keep the car not spinning in GPL is to keep the brake firmly planted down ;)

[email hidden] (Toni Lassila) writes:

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> On Fri, 4 Aug 2000 15:40:54 +0100, "Ian P" <[email hidden]> wrote: > >> > > so what gives if you can get the car back in control if you slam the > >> > > brakes real hard, realistic? I dont think so. > >That works in GPL as well ;) > > Yes, I've found the best way to keep the car not spinning in GPL is to > keep the brake firmly planted down ;)

Not necessarily unrealistic, imho. The best way to stop a spin is to get rid of all side force on the front wheels, preferably while keeping it in the back. Slamming the breaks is a bullet-proof way of losing the fronts, and since you probably have the brakes biased to the front you may also keep some grip at the rear as long as you don't push the break pedal all the way to the floor. This is easier than only steering into the spin and moderating the throttle since neither is going to help at all unless done almost perfectly. _ Mats Lofkvist [email hidden] GPLRank +3.69

"Douglas Ellison" <[email hidden]> wrote in message news:8mhrq9$1kn$[email hidden]...

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> Your acceleration to the centre of the corner (i.e. G force) is > proportional to the grip of the car. > > If you have NO downforce, the only force keeping you on the road is the > weight of the car. > > The maximum cornering 'force' is therefore the same ammount. > > F=ma > > Hence, only ever 1 g.

Assuming that gravity is the only force acting on the car, which is not true once the car is in motion. G is constant, relatively. The mass of the car remains constant, relatively. The "weight" of the car -- that is, the force vector acting on the car -- changes as it lightens at the top of a rise, or becomes heavier at the bottom of a dip, or tilts as it accelerates laterally or longitudinally. Examining F=ma: Mass, as we said, is relatively constant. Also, G from gravity remains relatively constant. Thus, F should remain constant. However, we know that the force acting on the car changes for various reasons. We found nothing new by examing this simple, if important, relationship in isolation. A tire's available grip is strongly coupled to its normal loading. However, there is no simple relationship between the two. Michael.

On Fri, 04 Aug 2000 14:14:26 GMT Toni Lassila <[email hidden]> wrote: % On Fri, 4 Aug 2000 13:46:52 +0300, "Marko Aaltonen" % <[email hidden]> wrote: % >Oh...aha...I meant...that....you know....heck, I just wasn't expecting it do % >that. Could be that I'm comparing it to GPL... % Then again, the tyres and subsequently the mechanical grip between '68 GP cars % and '98 GP cars is like comparing apples with oranges. Very true, but both apples and oranges must follow the same laws of physics. -- **************************** Michael E. Carver ************************* Upside out, or inside down...False alarm the only game in town. [email hidden] http://www.teleport.com/~mcarver =-=-=-=-=-=-=-=-=-=-=-=-=-=-=<[ /./. [- < ]>=-=-=-=-=-=-=-=-=-=-=-=-=-=

Douglas Ellison wrote:

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> > Compared to driving at high speed with the downforce, DEFINATELY yes. > > However, modern F-1 tires (not sure about the new grooved ones) are > capable of > > upwards of 1.8 g's cornering at light load. It's probably safe to say > that a > > modern F-1 car could still pull 1.5 g's or so through a corner if you > removed > > the wings and all downforce stuff. > > Your acceleration to the centre of the corner (i.e. G force) is > proportional to the grip of the car. > > If you have NO downforce, the only force keeping you on the road is the > weight of the car. > > The maximum cornering 'force' is therefore the same ammount. > > F=ma > > Hence, only ever 1 g.

It is not uncommon for modern tires to produce more sideforce than the normal force (weight) on them. (Peak friction coefficients larger than 1.0) Some numbers for peak friction coefficients reported in "Race Car Vehicle Dynamics": Goodyear Eagle GT-S P215/60R15: 1.16 800/820-15 Stock Car Short Oval: 1.62 Formula One Front 25x9-13: 1.83 Another example: Goodyear Formula SAE Tire 20x6-13: 1.9 "Race Car Vehicle Dynamics," W.F. Milliken and D.L. Milliken, SAE, 1995. ISBN-1-56091-526-9 -- Matthew V. Jessick Motorsims [email hidden] http://www.motorsims.com Vehicle Dynamics Engineer (972)910-8866 Ext.125, Fax: (972)910-8216

"\"Michael E. Carver\" mcarver"@teleport.com wrote:

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> > On Sun, 06 Aug 2000 11:19:17 GMT Toni Lassila <[email hidden]> wrote: > % On Sat, 05 Aug 2000 14:49:04 GMT, "Michael E. Carver" [email hidden] > % wrote: > % >Very true, but both apples and oranges must follow the same laws of > % >physics. > > % Yes, but just because a sim doesn't act like GPL doesn't mean that it's breaking > % the laws of physics. The parameters involved are just so different. > > Since GP3 is wrapped around 90+% of GP2 code, I don't see how GP3 could > even hope to have as sophisticated physics model as GPL. That is the

Why shouldn't GC be able to enhance the algorithms used for the car physics? Just because the graphics look very much like GP2 + 3D support? > point..... Whether we are talking about a 1998 F1 car or a 1967 F1 car, > the laws of physics were the same for both. However, GP3 doesn't seem > to actually simulate the physics as much as it mimics them.... Well, it mimics it very well then, so who cares? I'd say it mimics the physics of a modern F1 car as well as GPl mimics that of a '67 F1 car. -- l8er ronny Your mouse has moved. Windows must be restarted for the change to take effect. Reboot now? |\ _,,,---,,_ I want to die like my Grandfather, ZZZzz /,`.-'`' -. ;-;;,_ in his sleep. |,4- ) )-,_. ,\ ( `'-' Not like the people in his car, '---''(_/--' `-'\_) screaming their heads off!

On Sat, 05 Aug 2000 14:49:04 GMT, "Michael E. Carver" [email hidden] wrote: >Very true, but both apples and oranges must follow the same laws of >physics. Yes, but just because a sim doesn't act like GPL doesn't mean that it's breaking the laws of physics. The parameters involved are just so different.

On Sun, 06 Aug 2000 11:19:17 GMT Toni Lassila <[email hidden]> wrote: % On Sat, 05 Aug 2000 14:49:04 GMT, "Michael E. Carver" [email hidden] % wrote: % >Very true, but both apples and oranges must follow the same laws of % >physics. % Yes, but just because a sim doesn't act like GPL doesn't mean that it's breaking % the laws of physics. The parameters involved are just so different. Since GP3 is wrapped around 90+% of GP2 code, I don't see how GP3 could even hope to have as sophisticated physics model as GPL. That is the point..... Whether we are talking about a 1998 F1 car or a 1967 F1 car, the laws of physics were the same for both. However, GP3 doesn't seem to actually simulate the physics as much as it mimics them.... -- **************************** Michael E. Carver ************************* Upside out, or inside down...False alarm the only game in town. [email hidden] http://www.teleport.com/~mcarver =-=-=-=-=-=-=-=-=-=-=-=-=-=-=<[ /./. [- < ]>=-=-=-=-=-=-=-=-=-=-=-=-=-=

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>"Douglas Ellison" <[email hidden]> wrote in message >news:8mhrq9$1kn$[email hidden]... >> Your acceleration to the centre of the corner (i.e. G force) is >> proportional to the grip of the car. >> >> If you have NO downforce, the only force keeping you on the road is the >> weight of the car. >> >> The maximum cornering 'force' is therefore the same ammount. >> >> F=ma >> >> Hence, only ever 1 g.

F=ma doesn't prove that a vehicle can't accelerate at more than 1 g. Let's look at a real tire test for an Indy 27x14.5-15 rear tire here, from the same source Matthew Jessick was referring (Race Car Vehicle Dynamics, Douglas and William Milliken): With 1000 lbs vertical load (that's your "F", or Force, in F=ma)---- A bit over 1700 lbs lateral force is generated. Really, you want A=F/m here. If the 1000 lbs downforce on the tire is all from weight of the car, what's the mass of the car? 1000/32.16=31.09 slugs. Acceleration=Force/Mass Acceleration=1700/31.09 Acceleration=54.68 ft/sec^2 54.68/32.16 = 1.7 G lateral acceleration By golly, that's the same thing as: 1700/1000=1.7G If the coefficient of grip/friction can never exceed 1 as Doug said, a quarter mile dragster could never do any better than about 9 seconds at 200 mph (roughly). We know that's not true, even cars with no downforce beat that these days by a long shot. Top Fueler dragster tires show a grip /friction coefficient of about 4 when they're hot.

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> >Assuming that gravity is the only force acting on the car, which is not true >once the car is in motion. > >G is constant, relatively. The mass of the car remains constant, relatively. >The "weight" of the car -- that is, the force vector acting on the car -- >changes as it lightens at the top of a rise, or becomes heavier at the >bottom of a dip, or tilts as it accelerates laterally or longitudinally. > >Examining F=ma: Mass, as we said, is relatively constant. Also, G from >gravity remains relatively constant. Thus, F should remain constant. >However, we know that the force acting on the car changes for various >reasons. We found nothing new by examing this simple, if important, >relationship in isolation. >

G and F are "relatively constant"? I doubt the acceleration of gravity changed much during the above tire test. :-) Also, I was referring to skidpad testing in the earlier post, where everything is as constant as you can get it. >A tire's available grip is strongly coupled to its normal loading. However, >there is no simple relationship between the two. > >Michael. > You're right about that. Coefficient of grip/friction changes with the load on the tire. For instance, the Indy tire from the example above shows about 1.7 at 1000 lbs load, while the same tire shows a little over 2500 lbs of lateral/sideways force with 1800 lbs pushing down on it. That's 2500/1800 = 1.38. That's quite a change in grip coefficient from the 1.7g's in the other example. Tire engineers call this effect "load sensitivity." You're right about there being no simple relation between the two, Michael, but in both cases, the coefficient of grip is well above 1, as Matthew Jessick pointed out. (Thank you, Matt, BTW, for posting those numbers.) The numbers he quoted are at one particular load and are not constant, but the really sticky ones will stay above 1 pretty much no matter what ya do! Cheers, Todd Wasson --- Shameless plug: Performance Simulations Drag Racing and Top Speed Prediction Software http://PerformanceSimulations.Com **No tires were injured or killed in the production of this post.