I was thinking a bit about LFS' aerodynamics today and couldn't help wondering if there's a somewhat important force missing in the current model (I attached a jpeg of what I'm trying to explain):

I always felt like the (road) cars in LFS were somewhat "wobbly" on straights and prone to building up oscillation from left to right. At higher speeds, I'd imagine that there's air flowing by both sides of the car which should help to keep the car straight.
Also, I think that when a car is oversteering, there must be some air pushing against the side of the car, which should help getting the rear end back in line. The higher the speed and the higher the drift angle, the higher this aerodynamic force becomes.

This is a bit speculative as I have no idea how strong these forces really are in relation to the crucial forces but I can imagine that it's quite noticeable

Your assumtpion is correct and it's not modelled in LFS. The lateral force due to crosswinds can be calculated by the formula F_lateral = 0.5 * density of air * frontal area * speed ² * coefficient from the attached diagram

Vain

Quote from Vain :

Your assumtpion is correct and it's not modelled in LFS. The lateral force due to crosswinds can be calculated by the formula F_lateral = 0.5 * density of air * frontal area * speed ² * coefficient from the attached diagram

Vain

Sounds relatively easy to implement

Would you say that crosswinds have a significant impact on car stability?

Yes, I guess so.
For a speed of 125 km/h or 35 m/s at a nice angle of 20° the force should be
F_lateral = 0.5* 2m² * 1.3 kg/m³ * (35 m/s)^2 * 0.6 = 955 N
which is about the gravitational force caused by 100kg.
When a 1 ton car corners at 1g lateral acceleration it's tyres (all four together) generate a lateral force of about 10 000N. Thus the current error is about 10% for the given parameters.

Vain

Setting the sideways drag is actually already possible for wings, so it's not like the code would be missing, the drag coefficient is probably just left at 0 due to the lack of accurate data.

Well as with most things this issue has both a positive and negative effect on car stability. The basic shape of most street cars is actually Aerodynamically backwards and the XRT is a prime example of this. It's shape is not unlike that of a Pontiac Fierbird with a long sloped nose, the passenger section at or behind the physical center of the car and a shorter sloped aft section. Basically the exact opposite shape of a rain drop.

This means a vehicle natural tendency is to swap ends at high speed is the force exerted on the car is not overcome by the forces trying to hold it to the ground. This is the reason why down force is such a major factor in all forms of high speed racing and vehicle design.

Now the weather-vane effect the OP is talking about is also in effect but deals with the surface area in profile and is also dependent on the pivot point, which is the point of contact with the ground that has the most traction.

Which all just goes to say this is not in any way a simple subject or equation.

Quote from AndroidXP :

Setting the sideways drag is actually already possible for wings

It is for the car bodies too, so it's already modeled, albeit simplistically (defaults to 2x drag for pure side drag).

What isn't modeled is the center of pressure moving, so if this was towards the rear of the car, you would get a stabilising torque from the air drag. With the current air drag acting at the CoG, the car just slows faster when sideways. With something like a truck with a front biased center of pressure, the air should destabilise, although with the weight of even race trucks and the low speeds involved, I doubt it makes much difference to high speed handling.

Aerodinamics based on a car shape, are very complex. The mathematical formulas, for air flow and presure were aparently discovered in antiquity, but became usable once computers were invented. The folowing image show the air flow and presure calculated using thoso formulas: http://www.fluent.com/about/news/pr/img/pr77_2_lg.jpg and don`t ask me what are they are, because, all i can remember are bits from an old TV show i saw. Anyway, the complexity of those calculations are just impractical to implement in games.

If you want to improve stability just adjust camber/ toe in setings on your car. No real car wheels are 100% straight, because they would make the car wobly and unstable at speed. The same reason is why rear wheels track is different that the front wheels.

Many important things are currently missing. Now if you crash with formula/fzr... at high speed or go through bumb your car wont flow away from track.That says there are many important features not implemented yet. Currently damaged wings doent change you aerodynamics or so..