PHYSICS Brake ducts and Tyre damage

Brake ducts, car damage, tyre damage and generally how we can make you lose a race and get angry...

NEW!
ACC v.1.2 brings different brake pads selection, brake pads and brake discs wear

Brake pads and brake discs wear is relative to the brake pad choice, temperatures, driving style, ABS and brake bias usage. Brake disc and pad wear is shown at the end of each driving session, when you return to your strategy setup UI on the "last readings" box.
Additionally brake pads consumption will appear as a red dot in the center of the brake discs heat visualisation in the tyre and brakes HUD, when brake pads are under 10mm thickness.

Normally brake discs should last more than 24 hours race, but because there is no pitstop time penalty (all teams are obliged to at least one fixed time long pitstop so that they can change brakes), all teams prefer to change discs and pads at least one time during long endurance races.
There are 4 different brake pads available to choose from, each with its own characteristics and different combinations of brake pads front and rear are permitted.

• Pad 1: Very aggressive friction coefficient, max braking performance, aggressive disc and pad wear. Pedal modulation can be tricky if out of temperature or as it wears down. Use in hotlap and qualifying sessions, sprint races and can withstand 3 hours races. Risky and dangerous to use over 3 or 4 hours because the pads will wear down, overheat and lose linearity in brake pedal feel.
• Pad 2: Very Good friction coefficient, very good braking performance, good disc and pad wear. Pedal modulation almost always good and linear, good feedback while overheating and gradual wear. Perfect for endurance racing, but can also be used in hotlap , qualifying sessions as well as sprint races as what it loses in performance, regains in braking modulation and predictability. The default choice for long endurance races, easily makes 12 hours and can make 24 hours race too with a bit of care. Will also overheat and lose linearity in brake pedal feel when worn out, but in a more predictable way and after much longer stints. Because of the lower friction, you could possibly use smaller brake ducts.
• Pad 3: Moderate friction coefficient, braking zones can be longer in dry, very moderate disc and pad wear. Excellent pedal modulation also in cold ambient conditions, very linear pedal feedback. Excellent choice for wet conditions and very long endurance races. Very predictable and easy to modulate brake pad. Because of the lower friction, you should use smaller brake ducts.
• Pad 4, Very aggressive fiction coefficient. Max braking performance, extremely aggressive disc and pad wear, bad cold performance. This is a sprint race pad that can last about an hour but will show worse pedal feel, worse performance and overheating towards the end of the one hour stint. Those kinds of pads are not used in endurance racing, but included for demonstration purposes.

ACC v.0.7 brings brake ducts simulation.

Actually brake ducts simulation was always there, but now it is enabled as setup choice. As usual the preset setups have a default brake duct setting, that can work safely pretty much in any condition, different brake duct settings can affect greatly the brake efficiency but also the tyre temperatures and of course up to a point, the aerodynamics of the car.

The obvious functionality of the brake duct is to bring more or less air to the brake discs and keep them in a temperature range that can be effective. Setting 0 is a completely closed duct and can provoke brake fade very very fast, exceeding 1000°C. Never to be used in a real race, but added for simracer's gratification. Setting 6 is completely open and can keep the brakes very cold.

Small and fast note of how the brake heat affects braking performance. The brake discs and pads have a range of optimum friction, just like the tyres. Keeping their temperature between this range, will give you the best possible brake performance. Of course that doesn't mean that it will also stop the car sooner, as this depends on a multitude of reasons like tyre grip, downforce, ABS, setup etc. But it is obvious that a very cold brake system will make your braking zones much longer and the same will happen for a very hot brake system. In addition a very hot brake system will also wear down the pads much faster... but this is a different story for a different release version maybe

The brake duct doesn't only change the peak heat temperature but, most importantly it changes how the heat gets dissipated after you release the brakes. A low setting will keep the brakes hot for a longer period of time after your last braking zone, while a higher setting will not only achieve a lower peak temperature but also cool them down faster.

Ideally you want your front brake HUD to show green or slight yellow at the end of your braking zone and your rear, green. Don't judge after just 2,3 braking zones. Do a couple of laps and let the brakes do some heat/cool cycles to arrive at a balanced condition.
MoTeC channels are available for brake heat.

This behaviour brings us to the next very important influence of the brakes. The red hot discs will warm up the rims and then the air inside the tyre. In that way you can use the brake heat to heat your tyres up or try to run a bit colder brakes to keep the tyres from overheating.
Again, a couple of laps are needed to check the heat behaviour of the whole system brakes and tyres.

Also keep in mind that the brake ducts, especially the fronts, get heat from low near the asphalt. That is why they are influenced more by asphalt temperature. This means that you might have the same ambient temperature but an overcast weather will heat the asphalt and thus the brakes, more than a cloudy condition.
Also, the water now influences the brake discs, so under rain conditions it is better if you use a lower brake duct settings.

Finally, as you might have thought, the brake ducts will influence a bit the aerodynamics of the car, both in downforce and most importantly drag. The differences aren’t massive as you might expect, but they will make 3-4kmh difference at the long straight of Paul Ricard and as you know, every little counts.



ACC V.0.7 also brings an industry first tyre damage implementation.

One of the most risky conditions in a racing car, is cold tyres. Everybody has heard pit radio screaming at the driver to warn him that his tyres are cold and he should warm them up. Obviously a well warmed up tyre gives better grip and improves performance so it makes sense to have warm tyres at all costs. Still, there is a much more dangerous situation that occurs on cold tyres. A tyre is inflated with a low pressure so that with heat going up, the tyre will be at the optimum pressure. On the other hand a cold tyre will go even lower in pressure and this means the tyre can flex and move a lot. Riding a stepped kerb on a very low tyre, will make it vibrate and flex a lot. This can provoke carcass damage, can make the tyre lose contact with the rim and small amounts of pressure, eventually creating a vicious cycle that can provoke permanent deflation of the tyre and puncture! All of this is now simulated in ACC.

When the pressure goes under 24psi, you will get a warning from pitradio to keep an eye on it and avoid kerbs. You should really avoid kerbs at all costs when the pressure is so low. If you ride and slide over stepped kerbs with such a low kerb, the tyre might lose pressure. If the pitradio understands that you lost a good amount it will warn you again. It’s up to you of course to do a pitstop and put new tyres or raise the pressures, or risk it and stay out trying to heat up your tyres and raise your pressures. But don’t blame us if over a kerb the tyre will instantly deflate and you’ll end up spinning with no grip… or tyre.

Go outside the track and rejoining, running wide on grass and sand traps can also provoke similar tyre damage situations. All in all, the more you abuse your tyres when not in correct pressures, the more risk you have to get a puncture or at least to seriously compromise your tyres life.

A typical scenario of what you might experience: You start with slick tyres and correct pressures. Dynamic weather changes and you get night time cloudy with lower temperature or slight rain. You think you can handle it with slicks and decide to stay out. The grip is not bad but the tyres lose temperature and pressure fast. You get a warning from the pit radio which you ignore and you keep pushing on the kerbs. Another different warning, this time the pit radio says they detect a slow puncture or simply you’re losing pressure. Another kerb, and another and then that frightening sound of a tyre exploding, sparks from the under tray scratching the asphalt and your car spinning without control… maybe you should have made that pitstop for rain tyres.

Obviously the system is brand new and needs tweaking, so we appreciate your feedback. There is nothing random in the system, all of it depends on your actions, but some of the causes and effects are not predictable. You can never tell how your tyres hit the kerb or what impact they got in the re-entry from the grass, so some effects might seem random to you, but they are not.
We think it adds extra depth of simulation, realism and decision making while racing.

Finally with ACC v.0.7 we also activate the classic damage. Aero damage, drag and downforce, suspension bends, and total crash can happen. It’s a good system, fairly simple, does the job. We will try to improve on that too, in the near future.

Hope you will enjoy.

 

Thank you, but the whole team has been working day and night for all this and more.

 

The tyre flexes down to the rim, it is pretty visual.
Debris is not possible, many reasons.

 

There is detailed damage notifications now. I believe we will try to improve it even more.

 

Optimum slick tyre pressures as per pirelli advice are 30psi. 31psi for wets. But all teams run a bit lower than this... Watch the tyre HUD, when all bars are equal, means you're close to the optimum tyre pressure range.

At monza (and any circuit), if you want braking and acceleration stability you need to have your pressures equal when hot (operating temperature), so you need them a bit asymmetrical on your setup. But... if you want your car to turn more towards one side, then you could use pressures a bit asymmetrical while hot. Higher pressures on the left, will make the car turn more at right so to say... but obviously more unstable under braking and acceleration transitions.

 

I can't tell you the exact range, you need to experiment