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Live for Speed, Tyre Physics Progress Report

Hello LFS Racers,

As we said in our news item on 21st August, we have been working on a new tyre physics model. It has a good mathematical basis for the forces a tyre produces under varying circumstances and does feel good to drive, so we are very pleased with the new model. The new physics and plans for the VW Scirocco have inspired some other developments that are now important to get the best experience from the updates.

Most of the remaining development is in the following sections :

- Tyre heating and cooling
- AI driver improvements
- Limited setup system
- Suspension updates
- VW stability control

We'll now talk a little about these things, and some of our plans. Please be aware that these are just plans as we see them now. Plans can change, and they often do, so it is very likely that some things you read below will be different from the final result.

Tyre heating and cooling

As the tyre model is completely different, both in the contact patch (frictional effects) and also the way the tyre reacts to loads (deflection depending on air pressure and sidewall stiffness) the old tyre heating system no longer worked properly. So we have been trying new things, with some success, but at this time there are still noticeable issues that need to be sorted out. We found it impossible to simply use the old heating model with some adjusted figures as we had hoped. Some more real updates are needed to get the heating and cooling of tyres right.

AI driver improvements

Just recently we discovered that the AI were driving around too slowly because they were underestimating the available grip. But because available grip depends on tyre load in a non-linear way, it turns out that some of the programming for the AI drivers needs a little reorganising. Many community members like to drive with AI in single player mode, so it is important for them to drive at a good speed.

Limited setup system

We mentioned before that the VW Scirocco would be our first car with a limited setup. But as time went by, that plan changed a little. We realised that limited setups would be a popular option for online hosts. It is a feature that has often been requested. It would allow people to race in road cars that feel like road cars (not stiffened and lowered) and still be competitive. So we decided the limited setups should be an option that applies to many of the LFS cars. For example, in limited setup mode, the standard road cars would only allow tyre pressure and toe adjustments. The LX6 / RAC / FZ5 class (LRF) would also allow compression and rebound damping to be adjusted along with ride height and adjustable anti roll bars (in some cases). The idea is to allow the same adjustments you could make on the real car without changing any parts.

Suspension updates

In order to implement the limited setup system, we needed some good standard setups, the kind that these cars would have in real life. In comparison with most LFS setups currently in use, the new default road car setups are a lot softer. Our testers noticed that with the new setups some cars can be a bit tricky at times, for example when adjusting the accelerator while cornering or when braking into corners. In real life, the suspension geometry is designed to produce an anti-dive effect under braking and anti-squat under acceleration. This has until now been absent from the LFS suspension systems, but now looks like an important development to support the realistic setups.

VW stability control

The special traction control and stability control systems for the VW Scirocco still need to be completed. We don't intend to make this as complex and refined as the real VW systems. We do want to recreate some of the beneficial effects of those systems that can apply individual wheel brakes to help the car go where the driver wants it to, when things begin to get out of shape.

We hope this progress report gives some insight into what has been going on. As you can see there are still important things to be completed. It's hard to know how long the tyre heat and suspension updates will take, so we are still not able to estimate a release date.

A reminder :
- The new physics will be a free update for all LFS users
- The VW Scirocco will be available to S1 and S2 license holders