90 http://www.racecar-engineering.com SEPTEMBER 2019
TECHNOLOGY – CHASSIS SIMULATION
sweet spot. This is where being able to read your
aeromaps and ride height channels become
absolutely critical, and your first port of call is to
read the aeromap, as shown in Figure 3.
For obvious reasons this aeromap has been
significantly redacted. The rows are front ride
height and the columns are rear ride height.
Also, all the values have been normalised. Where
you see the max values of CLA, or in this case
when they are all 1, will tell you where in the
aeromap you need to be from turn-in to mid-
corner. These form the ride height targets that
you are shooting for at this stage of the corner.
Sweet spots
To hit these sweet spot targets the front and
rear third springs really need to become your
best friend. I must confess, I have always been
a bit nervous with third springs because from a
vehicle dynamics perspective it is very easy to
screw this up and the drivers complain terribly
when you do. However, for the set-up strategy
on this car the third springs were a lifesaver.
Once the third springs were dialled in the ride
Figure 3: The sweet spot you need to hit mid-corner
heights where in the sweet spot. Figure 4
provides a very good illustration of this.
Here the baseline is coloured the optimum
set-up is black. The channels are speed, steering,
front and rear pitch and front and rear ride
heights. The two channels to watch are the
bottom traces, the front and rear ride heights.
In particular, what you are concentrating on ismaking sure that in the mid-corner conditions
they are in the sweet spot as seen in Figure 3.
In this case the front ride height wasn’t
too bad. However, the rear third spring for
the baseline set-up was too stiff. Once this
was addressed it put it right in the ride height
envelope and the corner deltas where + 2 to
3km/h. This is a big jump for a simulated changeFigure 4: Comparison of standard set-up with third springs with ride heights in the sweet spot