The suspension system of a Formula One
car forms the critical interface
between the performance
generating components of
Power Unit, chassis,
aerodynamics and tyres.
It comes as no surprise therefore
that the design, manufacture and
set-up of suspension is an
extremely complex affair.
We manufacture all of our
suspension in-house. This is
because they are very complex
and also, they are what we call
safety critical items. They are structural
items and the safety of the car and
the driver depend on them. We make
them in-house because we can control
the quality, we are using expensive
materials and we need precision.
The biggest challenges in designing
Formula One suspension are to make
the trade-offs between the strength,
the weight and the physical size of
the suspension. And I say the size,
because these components are in
the air stream. They have a huge
effect on the car aerodynamics, so
we need to minimise that effect.
But, at the same time, they are
structural, safety-critical devices and
we have to achieve the strength.
And then, we have to minimise the weight.
So, this means all together this is one of
our big structural challenges and big
manufacturing challenges that we
have in Formula One.
Now we can look at the three main
parts of a Formula One suspension system.
We have the inboard suspension,
hidden away underneath the bodywork,
where we have the springs, the dampers
and the anti-roll bar. And here hidden away
under the tyre we have the outboard suspension,
which is the upright, the wheel bearings
and the axle. And in-between,
the parts that you can see,
which are the wishbone elements
and the steering rod, which are the
only items that really see the external airflow.
In designing all three of these, the common
theme is stiffness. We have to have the
wheel position controlled as accurately as
possible.
Outboard, we’re looking at the challenges
of high temperatures, they’re close to
the brakes. Inboard, we have the complex
components, the hydraulic system, the
dampers, the springs, the anti-roll bars,
and in the middle, in the leg elements,
we have the structural and aerodynamic challenge.
You’ll hear a lot in Formula One drivers
and engineers talking about balance.
The reason is that these four tyres
behave differently every part of
the track, every corner of the track.
What we want to do is to control the
relative amount of grip of those
four tyres, as the driver goes through
the different phases of the corners
of the circuit. What the suspension
allows us to do is to change minutely
the amount of grip that those four
tyres generate at any one point
on the track. And the way we
do that is by adjusting the inboard
settings of the suspension,
by adjusting the damping and
by adjusting what we call the
mechanical balance. That’s because,
with that adjustment we can control
the change of grip from the rear axle
to the front axle, and that depends
on the car speed and the track conditions.
When we are running the car on the track,
we make sure that we look at the
suspension loads we are generating.
Sometimes we take that from sensors
on the internal suspension and
sometimes we take that from sensors
built into the suspension itself.
And it’s very critical for us to
understand the real loads the
suspension sees. So, the maximum loads
that we design the suspension for are
based on simulation and are based on
previous years’ experience, and also a
collection of unusual loads that we
have recorded over the years in
unusual conditions. Spinning the car,
going backwards over a kerb, hitting
the brakes while the car is in the air and
landing.
And these are all critical additional load
cases that have to be dealt with in the
suspension design and testing.
The suspension systems on a road car
provide two functions and we call those
ride and handling. Ride is about dealing
with the surface of the road, undulations,
bumps, kerbs, changes in camber, ensuring
that the grip is spread correctly between
the four tyres. The handling is about dealing
with the dynamics of the car. How the car
behaves under braking, how it changes
direction, how it does what the driver
wants to do. Now, a Formula One
car has got the same demands of ride
and handling, dealing with lumps and
bumps, kerbs on the track, dealing with
more aggressive dynamics of corner entry,
braking, steering, acceleration.
But, the Formula One suspension has a
third function which we call platform control.
Because Formula One cars generate
enormous vertical forces from their aerodynamics,
the suspension has to deal with
literally tonnes of extra load on the car
at high speed and we have to make sure
that the position of the car relative to
the road is well controlled,
because this has a very important
effect on the aerodynamic performance
of the car. Road cars and Formula One
cars are very similar. They both have ride,
and both have handling control. The
difference is with the Formula One car,
that it needs the platform control
as well because of its dominant
aerodynamic effects.
We’ve been working with Daimler,
in particular the ride and handling group,
for many years developing our tools for
developing suspension systems.
In the early days we had Daimler engineers
working directly with us and as we’ve
evolved our relationship, we’ve been
developing the models, the tools
that allow us to design. And the interesting
thing is that although these components
look very different, the fundamental physics
is very similar, and we’ve been able to
share
lots of techniques in designing and analysing
these complex systems, particularly the complex
hydraulic components of the suspension.
And some of these components
on the road cars now share very
much the same design philosophy as
the Formula One components. So, the
suspension is just one of the many systems
that link the Formula One car to the road
car
and show the bi-directional link between
Daimler and Mercedes-Benz Formula One.
