Assetto Corsa Competizione ACC Rake-Aero Test (1 Viewer)

[kobusnell]

A simple test to see what the effect of rake is on 2018 Bentley GT3 in ACC

Setup
Motec
I'm using a Motec workbook available on Nils's discord, by k.witch. In it, he calculates wheel loads based on suspension travel and wheel rates. You set the wheel rates manually in the workbook, which I did. I applied a 1s filter to wheel travel to have less noise on the wheel loads.

Car
I'm running the Bentley. I made the suspension wheel rates as hard as possible to try and stop it from bottoming out. I set the bumpstop range to maximum, because I don't know how bumpstops will affect the calculation, but I assume it will skew it due to the difference in wheel rates. (Initially I had bumpstop range on 0, but then I thought about how loading would work)
I ran aero in the following configs:

Front (mm)	Rear (mm)	Wing
54​	90​	0​
54​	73​	0​
54​	54​	0​
54​	90​	10​
54​	73​	10​
54​	54​	10​

Track
Paul Ricard. On the mulsanne straight I tried to keep the car just below the limiter in 4th. Generally 216 kmh.


Findings
It is typically a bit difficult to get super clear data, but I'll give values for areas that seem consistent, where the graph doesn't vary too much...

Front Load (N)	Rear Load (N)	Total Load (N)
8540​	7350​	15890​
8140​	7840​	15980​
7160​	8070​	15240​
8530​	8330​	16860​
7890​	8770​	16660​
6830​	8840​	15680​

Edit, add graph:

Conclusion
I tried to get wheel loads due to aero in ACC. I saw the following trends
1. Total aero loading at maximum rake and intermediate rake is similar for car with no rear wing, and full rear wing
2. Total aero load at minimal rake is definitely less, due to a major reduction in fron axle load.
3. Full rear wing adds to rear downforce. As rake decreases, adding rear wing reduces front aero load.
4. Adding rake increases total car downforce, up to a point. Knowing where downforce plateaus will take extra work, for later, and is probably car dependent.

 

[kobusnell]

Variance with speed
Ooof, just realised there is another important component with regards to this - how downforce on each axle is affected by speed. Doesn't fall properly within this scope, but it's interesting, so here goes just a short summary.
For maximum rake, as the car speed increases, the aero balance shifts towards the front. For minimal rake, the aero balance generally stays the same. Intermediate is in between.

No wing:
Max rake, no wing:



Intermediate rake, no wing:



Min rake, no wing:



With wing, similar:
Max rake, with wing:



Intermediate rake, with wing:



No rake, with wing: