Quote from bobvanvliet :

I'm always for making LFS more realistic, so if RL lotus 7 replicas have (semi-)slicks, so should the lx6.

As previously posted, they have both, a semi-slick Avon ACB10 DOT tire, street "legal", but not really streetable, and the Avon Caterham Bias Bly racing slick. LFS doesn't include an equivalent to the ACB10 DOT tire, it's in between the LFS road super and the LFS slick.

An update to my previous post, there are some low powered Catherham classes using the CR500 street tires, but most Caterham racers use the ACB10's or the slicks.

Quote from RacingSimFan :

near-impossible like on road tires.

Try this setup that I use for Blackwood for the road supers. A combination of swaybar and camber settings really helps stabilize the LX6.

http://jeffareid.net/lfss2/LX6_bl1_jeffr.set

Still, since the real LX6's have slicks, the game should offer them also. I think your point about a full field of LX6's is spot on.

slicks for the LX6, since the real ones often use slicks

I've always wanted slicks on the LX6. The stock tires are Avon CR500's, but no one races with these. The lowest grip tire used for racing seven replicas is the Avon ACB10 DOT tire, resutling in about 1.2 to 1.3g's of cornering force. LFS doesn't have an equivalent to this tire. Avon makes a Caterham specific bias ply racing slick, good for 1.4 to 1.5 g's of cornering force. Considering that Caterham includes slicks for sell at it's web site, it seems only fitting that the LX6 should also get slicks.

Tire products available through Caterham:

http://www.caterham.co.uk/aftersales/upgrades/mar03.htm

LX6 should also get more power

The 4 cylinder, 2.3 liter Duratech motor used on the Caterham CSR makes 260hp, a lot more than the 190hp of the LX6 in LFS. In the USA, where premium gas is only 91 octane, Cosworth makes a 240hp version of the 2.3 liter Duratec. I have a similarly tuned Duratech 2.3 liter based Caterham SV that I bought from a local Caterham dealer.

A web site with some nice videos of a Caterham in action

Unlucky guy though. He finally get's his early prototype, customed tuned Durtech motor running right at Spa and then crashes on radiator fluid spilled by another car.

http://www.jackals-forge.com/lotus/

pics of my caterham sv

http://jeffareid.net/ctm/ctm.htm

Last edited by JeffR, Thu 27 Oct 2005, 14:23.

It's a new mod, the 3 "spectators" have sniper rifles and take out the wreckers.

I don't have a favorite racing game. I switch back and forth between games these days, some of which I mostly play offline, others online. I enjoy arcade racing games as well as simualtion games. My favorite games are the TombRaider series; each release of a new version means I won't be playing anything else for a while.

The most time I spent with a single racing game was an arcade game, need for speed high stakes; it was one of the first true online racing games (a host server instead of player server). The next longest time I've spent with a game is Grand Prix Legends, mostly offline working on my GPL Rank (-12, most of which is due to an 8:15.32 at Nordschleife). Since then, I haven't spent that much time with any particular game.

Simulation type games I like (alphabetical order)

F1C99-02, plus RH2004, SCC and Prototype C mods.
Grand Prix Legends
GTR
GTLegends (waiting to receive this one)
LFS
NR2003, mostly road courses, plus Trans Am and GTP mods.

Other racing games:

Ford Racing 2
Mercedes Benz World Racing
Toca Race Driver 2
Need For Speed series, mostly high stakes, porsche unleased, undergound 2

Some of these games had interesting features. Need For Speed High Stakes, had a cool style to it's night time and/or weather graphics. With Mercedes Benz World Racing, the landscapes are fully implemented and you can drive anywhere on them. Toca Race Driver 2 had a story to go along with it's career mode. F1C99-02 RH2004 mod from TV view has incredible sound.

For anyone who's curious about what rFactor looks like, I've made some videos:

Howston at Toban, 1:42 lap
rfrftgp.wmv

Formula (like an F1) at Toban, 1:07.5 lap
rfrf1tgp.wmv

Formula (like an F1) at Sadian, 27.3 lap
rfrf1sh.wmv

Now what will really impress me is when games look this good
(650hp 911 at Road America):
ra.wmv

Last edited by JeffR, Tue 5 Sep 2006, 10:11.

Quote :

LX6 with a new setup. 0 front swaybar and about 10 rear swaybar

Can you post this setup? If not, can you mention what camber settings you used, as these affect cars in LFS about the same as swaybars.

Quote :

Only problem now, the fronts will not heat up

Use induced understeer to heat them up. Take a look at the start of this hot lap world record.

http://www.lfsworld.net/get_spr.php?file=124&w=1

For a race, just use a bit of induced understeer until the fronts get warmed up.

After enabling the F9 screen there are grey bars above the tire temperature diagrams. Do the grey bars indicate the forces on the tire, or do they indicate the camber of the tire?

With the LX6 at Blackwood, in order to get even temperatures, I have to set the camber +1.5 front, +1.0 rear, with a net camber from -.2 to -.1. I reduced tire pressures to the minimum 11.0 psi and there's still a slight bulge in the middle of the grey bars. The grey bars are bigger on the outside when turning, yet the tire temperatures come out even with this setup.

The setup is easy to drive, I'm not that good with LFS but I can get sub 1:25 lap times with this setup, which is slightly quicker for me than the WR edgar setup.

http://jeffareid.net/lfss2/LX6_bl1_jeffr.set

An alternate definition of understeer versus oversteer, at least in terms of defining a car's setup.

You drive a car around in a circle, well below the limits. It takes a certain amount of inwards steering input to maintain the circle. Then, while holding this radius, you speed up the car until it is near the limits. The steering inputs required to maintain the raidus determine if the setup has understeer or oversteer.

Understeer - it takes more inwards steering to maintain the radius.

Neutral - it takes the same amount of inwards steering to maintian the radius.

Oversteer - it takes less inwards steering to maintain the radius.

Critical Oversteer - The steering is centered while maintaining the radius.

Critical oversteer isn't a limit, because rally cars and dirt track racing go beyond this.

Quote :

front SA > rear SA is the definition of understeer

Ok, I sit corrected.

Now can someone explain this to the LX6 that so it behaves properly?

Quote :

I think front SA > rear SA is the definition of understeer.

Assuming that the car isn't in the middle of a spin

Quote :

So how does this technique work? Let's start with an oversteering car in a left corner where the front slip angle is still on the linear part of the graph.

How can this be? Front slip angle is greater than rear slip angle unless you counter steer. The assumption in this case is the fronts are still turned inwards. If the rear tires are spinning because of excessive throttle, there's a small window of time before the slip angle at the rear goes beyond optimal, and you can just lift a bit and/or counter steer.

Generally induced understeer is used in two cases. When a car is slowing, normally you don't get understeer unless the driver downshifts too soon and breaks the rears loose, or the car setup is just too oversteery under lift thottle. In this case induced understeer works well because you can use it while braking. The other case for using induced understeer is in a very high speed turn, where the throttle is floored just to keep the car going against the aerodynamic drag from the high speed. Under this circumstance, the rear tires are driving the car forwards as well as trying to turn the car. Keeping the fronts turned inwards just a bit past optimum can stabilize a car, if the rear end steps out, the increase in slip angle at the front results in the car just drifting instead of oversteering. It's just a bit past optimum, because any more than that and you create too much drag and heat on the tires. It's more of a preventitive method than a recovery method. Again, it's not going to help if the car isn't properly setup for high speed turns.

Countersteering is normally used during acceleration, similar to drifting, or rally style driving, or dirt tracks. You modulate the throttle and steering inputs to control the car. Countersteering and braking don't mix, the reduced slip angle at the fronts allows them to have more available braking grip than the already sliding rear tires and just makes the spin worse.

OK, got the induced understeer to work, but it took increasing the steering lock to 30+ degrees (I maxed it out to 36 degrees), I can transition from oversteer to understeer with a lot of inwards steering input. However, I don't need anywhere near this much steering lock to induce understeer if the rears aren't sliding. Still puzzling me why the rears sliding affects what happens at the front end so much, especially when the car is oversteering, the front tires slip angle is already increased.

Last edited by JeffR, Wed 19 Oct 2005, 11:45.

Induced understeer to recover from oversteer works in real life for most cars. If you have access to a large empty parking lot, you can try this for yourself.

If the rear tires are at an excessive slip angle, then turning the fronts inwards means that they have even more excessive slip angle.

With LFS S2, at least in the case of the LX6, if the rears aren't sliding, then inducing understeer is extremely easy, but once the rears start to go, it's seems to be very difficult. This is what I don't understand. With LFS S1's all or nothing grip, inducing understeer was very easy, even more so than GPL, as shown in this video:

http://jeffareid.net/cgi-bin/lx6.wmv

I've tried messing with setups in attempt to be able to get the front end to wash out after losing the rear end (if I center the steering or steer inwards), and I find I have to max out front sway bar, zero out rear sway bar, and mess with camber settings to just get the car to slide sideways evenly. I'm running minimum pressures in the tires of the LX6 and yet the middles are still the hottest points. I could try increasing front tire pressure while leaving the rears at 11 psi.

Inspite of all my experiements, I can make the LX6 stable, but the setup paramters are a bit extreme, starting with race 1 setup. Lower height to .060, increase springs to 40 rear, 35 front. I max out front sway bar and set rear sway bar to 0. I set the camber +1.5 on the fronts, +1.0 on the rears. Which results in about -.2 on the left, -.1 on the right, as viewed from the suspension diagram with driver and 15% fuel. Fronts get hot on the outer 2/3rds, rears are about even. I set the camber a bit too positive on the front to reduce oversteer. I reduced tire pressure to 11 psi. I set differential to 40/40. I'm not that great a driver with LFS, but was able to do 1:24.5 laps at Blackwood with this setup, anything under 1:25 is a good lap time for me.

OK, so my first experiment was too extreme, however, it only takes a few degrees beyond optimal to drop from 1.15g's to 1.05g's, but this is small enough that you couldn't feel it in real life either.

What I don't understand is that you can create a lot of understeer with higher steering lock settings, but if the rear end starts to slide first, pegging the fronts inwards doesn't seem to cause this same understeer reaction. Maybe an issue with differential settings?

Does anyone, other than the developers, know what the slip angle versus grip curve for the tires in LFS looks like?

Lateral grip must fall off somewhat due to slip angle, otherwise a driver couldn't induce understeer by turning the front tires inwards. The main thing I noticed is that in real life (I've tested this with several cars going in circles at a big parking lot), the induced understeer effect is much less than it is with LFS.

Last edited by JeffR, Wed 19 Oct 2005, 02:42.

Quote :

leads people to believe (falsely) that radial tires are losing a bunch of grip after the peak. T'aint so!

When I do web searches for

radial bias ply racing tire slip angle

most sites reports that there grip remains about the same for bias ply slicks, but does fall off for street radial tires. Racing radials have some fall off but not as much.

Top fuel drag racing tires lose a lot of grip if they spin, but wrinkle wall, high grip tires are in a class by themselves.

The stickiest rubber compounds are found on table tennis rackets, with coefficients of friction 7 or higher.

Quote from xaotik :

I've found that to be the case with all cars with a rear-biased weight distribution in LFS, but it also might have to do with the ride height of these cars as well as all of them (formulas and LXs) are pretty low riding.

Ok, that would make sense, maybe the front end of the car is getting stuck in the sand.

Not sure if this is related, but if the LX6 is stuck in a sand trap, there are times it can not move forwards, but it can move backwards (in reverse).

Quote from ColeusRattus :

I do not know much about physics in general and tyre and grip behaviour specifically, but that statement sounds fundamentally wrong. If the slicks would grip, they wouldn't slide anyway. So it is like the loss of grip is responsible for sliding, but not vice versa.

A tire produces lateral force based on it's slip angle. The slip angle is the difference between the direction the tire is pointed, and the actual direction the tire is moving. There's always some slippage at the edges of the contact patch, and as slip angle increases, the amount of slippage increases, as well as the amount of lateral force, until you reach a peak amount of lateral force. What happens if the slip angle goes beyond this optimal amount of slip angle depends on the type of tire. In the case of go-kart and bias-ply racing slicks, there's very little loss of grip, the curve for lateral force versus slip angle is almost horizontal from the optimal angle and beyond. Street radials, on the otherhand, have a signifcant downwards slope in the curve beyond the peak force, with a resultant loss in lateral force, and negative stabilty at the rear end of a car (once a spin starts, slip angle increases, lateral force decreases, which increase slip angle even more, which reduces lateral force even more, ... ).

The go-kart racer was forcing the go-kart to go into an oversteer situation with throttle inputs, increasing the slip angle beyond optimal. A good driver can do 4 wheel drifts, which is a lot of fun, but wears out the tires. However, because of the nature of the tires, the cornering force stays about the same even with larger than optimal slip angles.

In terms of recovery, if oversteer occurs under braking, a drivers only hope is to induce understeer by turning the front wheels inwards and maybe stabbing the brakes to cause the front end to break loose. Trying to counter-steer while braking just makes a spin worse. Lifting off the brakes probably means you end up off track. If you use left foot braking (go-karts and game players), and have braking balance set very rearward, adding throttle will reduced the braking on the rear tires and stop the oversteer if caught soon enough, but this type of setup is not that common.

If oversteer occurs under acceleration, then easing off the throttle and countersteering is normally used (induced understeer can be used also, but this slows down a car at a time when the goal is to accelerate).

In the case of the go-kart, a driver can really hang out the rear end without spinning the kart, and run about the same lap times.

Quote :

And I don't think that the grip is measurable with the dials at the f9 screen. IIRC they just show the accelerating forces effecting the car. I don't think they are enough information to calculate grip values out of it...

But what I'm interested in is the acceleration forces on the car, I don't really care about the grip, except for the fact that the grip is what determines the amount of force acting on a car.

The net result from my experiments is that understeering or oversteering grip is much less than the grip from a 4 wheel slide or than with all 4 wheels locked up. Something is wrong here.

Quote from skiingman :

Quote :

steer inwards ... 30% loss in grip

Why is this unexpected? The rough spec is that a sliding tyre has 30% less grip than a rolling tyre

If so, then why doesn't this show up when all 4 wheels are locked up or the car is sliding sideways with the steering centered?

I read from an actual go-kart racer that a driver can run an entire lap, doing a 4 wheel slide in every turn, and that lap times will hardly differ from a lap without any sliding. He mentioned that you can do this for several laps before the tires get overheated. Apparently, with go-kart slicks, the loss in grip when sliding is minimal. This is also true with the bias ply slicks used on most lighter non-downforce race cars (I hear this from people who race Caterhams and Formula Fords).

Quote :

Quote :

sliding the car with steering centered

How are you measuring grip in this instance? Via the counter at the bottom of the screen? That figure is AFAIK perpendicular to the vehicle, not the direction of travel. I would therefore assume once again that the component perpendicular to travel would be less than 1.1g.

It shows 1.1gs even as the car slides sideways (90 degrees). The vector sum seems to remain at 1.1g's as the car rotates with all 4 tires sliding. Why is the grip so much less when only 2 of the tires are sliding?

Quote :

Quote :

all 4 tires locked up while braking in straight line

I don't think the locked wheels are dropping in grip as much as they should in straight lines.

Well something is off, as I mentioned. Either the all 4 tires locked up grip is too high, or the steering grip is too low.

I edited my original post to include the rear end sliding without the front, a spin. I think that just like the steering loss, rear end loss from oversteer is reacting in a similar matter, making the spins more severe.

Some experiments I ran with LFS S2 alpha. I chose the LX6 as it has a good power to weight ratio and doesn't have downforce.

Drove in circles until cornering forces approached about 1.15g's, then continued to steer inwards until I reached the steering lock point. As I continued to steer inwards, the cornering forces dropped down to .8g's this is more than 30% loss in grip. Ran another test, initiating a spin, but then centering the steering wheel, grip remained about 1.1g's even with the car going sideways. Last test, slamed on the brakes, locked up the tires, slight loss in grip until the tires over heat. While drifting sideways or with all 4 tires locked up, there is very little loss in grip, but steering inputs can cause an extreme loss of grip. This doesn't make sense to me.

Induced understeer doesn't seem to work as well as it should, especially on the LX6 with front swaybar maxed out, and rear sway bar set to 0. With this setup, it would seem that the much stiffer front end would have significantly less lateral grip than the rear end. If the car starts spinning, pegging the fronts inwards should cause the front end to wash out, because they have a much higher slip angle, and because the suspension is set so much stiffer up front, yet induced understeer doesn't work well or not at all.

My conclusion from these experiments is that something strange is going on when one end of a car loses grip, as opposed to both ends losing grip at about the same time. When one end loses grip, the result is much less grip than when both ends lose grip.

Last edited by JeffR, Tue 18 Oct 2005, 07:49.

There are some players that mostly play offline, and for them something like an F1 would be nice. I found the formula car in rFactor to be fun, and F1C99-02 has been around a long time.

Regarding the F3000 class, it's no longer a supported FIA event. F3 and F2 classes are considered the replacement.