PHYSICS Suspension and Spart... setups, I mean setups!

“You have to redo all the alignment again? This is madness!”

When we started working on ACC, we wanted to improve on our suspension simulation and specifically the dampers simulation. Everybody in the racing automotive industry, continuously talk about how much dampers are improved nowadays, while in the same time, we keep simulating dampers with 4, 5 linear values for bump, rebound, fast bump and rebound and threshold times. For ACC we can now simulate fully blown damper graphs. We can get damper graphs from the manufacturer, and input those directly. It is a bit tiresome to design 24 or 36 or whatever number, different curves for bump and rebound but the results are definitely worth it, plus we have another part of the simulation that we can be sure that “that’s it” without having “what if” situations when numbers do not do what they are expected to do. Obviously, research never ends and everything can get better, but on the other hand it is a clear step forward and we believe you will appreciate their effect during driving, attacking kerbs, bumps and weight shift situations.

Bumpstops is another heavily used suspension feature in real life. In AC they were generally avoided by fast simracers because they had a fixed stiffness value and so when the suspension would hit them it would be like hitting something hard instantly, resulting in heavy load changes on the tyre and general loss of grip. Occasionally they would be necessary and unavoidable, but their use was always a bigger compromise than it should have been.

In ACC bumpstops are greatly improved by adding variable stiffness. The actual rate is controllable both in the force and the shape of a stiffness curve, making the presence of bumpstops much more useful. Actually necessary, as the new areo modelling requires proper bumpstop usage, as the real teams do. Τhe stiffness, the curve of it and the “window” of suspension movement before it touches the bumpstop, are extremely important. It is practically the rule that modern GT3 cars roll on top of their bumpstops at the front suspension, or just some mere millimetres of “window”. It is infact one of the best ways to control pitch movement and maintain a better and more stable aero platform.

During the development of ACC, we had some top secret meetings with some teams race engineers, who I will never thank enough, that helped us to validate the simulation with their data and telemetry and even test real life setups on the simulator and vice versa. We had some amazing results, but I’ll leave out what might sound as marketing talk and I’ll focus to one of the lessons learned.
We were going in depth, changing values on the setup of the car and trying to do fine tuning. I would change ride height, then go back to change camber, toe, bumpstop windows. Or I would change wheel rate and then back again to fix the alignment again, the ride height… you know the story, you are all doing it with AC, because as you know everything you touch in AC, moves the suspension in real time, changes the angles and you have to modify them again in the original values.
While in AC the whole process would be a bit macroscopic, in ACC the cars are even more sensitive to changes so we were doing like 2mm of ride height different, out to drive again, back 1mm of change, out again and so on…
At some point the race engineer looks a me and goes:
“You really have to redo all the alignment everytime? This is madness!”
It was clear at this point that we had to work on the setup screens and do something to help ourselves, our users and everybody that would like to keep sane while using ACC. First of all, I don’t want to showcase this as something revolutionary, but IMHO it is a good step forward and from some point of view, not just a good thing to have but a necessity.

So first step was to eliminate the distinction from real time values (on the right box of AC) and actual slider values. Real time values are now directly in the sliders. You change the slider and you get to see what the actual real time value is. So practically the setup values are now WYSIWYG (What You See Is What You Get)… wow

2nd step was to make setup changes closer to what happens in reality. In reality the race engineer will handle the mechanics his request. i.e. 2mm lower front ride height. The mechanics will do the change and make sure that ALL the other values of the setup, have remained unchanged. The race engineer doesn’t have to repass all the values again, one by one to verify that they are correct. That’s the job of the mechanics. You guys do 2 jobs, driver and race engineer, so let’s not make you do the mechanics too, right? In ACC you can change various values and at the same time the other settings will be recalculated to their initial status. Add fuel? Ride height will remain the same. Changed the wheel rate? Height, camber and toe will remain the same. Change the ride height? Camber, toe and bumpstop window will remain the same! Welcome back sanity.

3rd step. Give useful data and feedback to work with. Not everybody is a telemetry master or a alien driver that gets everything correct by feel. We are trying to give you meaningful data that you can understand or learn to understand and use them to make the setup better.

Now, I know that some of you might think that all of the above is nothing new, other sims show final values on their setup sliders since...ages. I'm not trying to impress you or present something different from what it is, but as you know since netKarPro we have the physics working in the background while in the setup screens and everything remains interactive. With ACC we had to work to control everything that is happening in the background, including moving the car to an invisible plane to make sure it is always 100% flat when working on the setup as well as many other details.
Here are some examples:

• You set your tyre pressure at the initial blanket temperature. (65°C slicks (except hotlap which is 80°C), 25°C wets). By the side of the values, you get LAST READINGS box for each tyre. Those are the hot readings of the tyres when you just arrived at your pitbox again (being by driving back or hitting return to pits at any place). This shows you hot IMO core temperatures, hot pressures and last wear reading of the tyre wear in tread depth mm. 3.00mm is brand new, 1.5 is extremely worn. Extra info is still in the works, like graining, blistering, tyre set used (because you’re going to have limited sets as per rules, but also infinite option if you like) and so on.
• TC and ABS simple tables to give you a generic idea and starting points on how to use them on dry green, rubbered and wet conditions, as well as fresh or consumed tyres.
  Sidenote: Is this worth mentioning? It’s just a generic table. Well yes, first of all we still working on the setup and have ideas, but most importantly, TC and ABS simulation in ACC has been improved. Really? This too? Yes. Both systems do not just cut power or releasing brakes when they sense slipping, but they have now actual maps that understand the amount of lateral and/or longitudinal slipping and apply different strategies of power modulation or cut for the traction control, and brake releasing for ABS. They can make driving completely “boring” but also slow, to extremely fun but at the same time won’t save you from a spin if you overdo it. As in real life, drivers use them extensively depending on the track conditions, tyre wear as well as to save tyres for a longer stint or simply driving style preference.
• Aerodynamic balance. We can’t show you the actual aerodynamic data. But we do show you real time the aerodynamic shift front/rear as you change the ride height and wings. We believe this is a great help. As we explained on our last aero post, the cars are now extremely ride height sensitive. This interactive setup visualization will help you understand how the aero balance shift with every click of ride height. As usual, do small changes at a time, check the values, drive and then change again. Small steps at a time.

We work on more such features. For example we are working on an interactive graph that will show you in real time in the setup (not while driving) the actual suspension “window” travel, before hitting the bumpstops, or riding the bumpstops right away. We have a strategy setup page that will help you decide which on of your limited tyre sets you want to use for the session, with a complete history and information of each tyre set. We are creating help pages for each setup value, etc. etc.

It’s just the start of the Early Access. We’ve got great plans and once more we want to thank you for helping us to make our and your simracing dream reality. Thank you for all your feedback and support… let the fun games begin!

 

You put your setup value and in the background everything is adjusted to keep your value. You don't have to double think about anything.

 

Fuel has weight and weight compresses the suspension. In AC if you go from full fuel to empty fuel tank, the car (while in the setup), will raise and you'll get higher ride height, different camber and toe settings from the suspension movement and so on. In ACC the ride height and alignment will remain the same.