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Having now covered Formula 1 suspension, I thought it would be useful to have a
couple of short videos looking at some of the sneaky but clever advancements
in suspension that were ultimately outlawed. Let’s start with FRIC Suspension, which stands
for Front and Rear Interconnected Suspension. I don’t know if this was ever an official name,
but this is the name the German press coined and it became common parlance.
So far, we’ve seen how the left and right halves of loaded suspension elements are
connected across the front of the car and rear of the car.
But these are both separate, contained systems. Interconnected suspension systems aimed to
join systems in the front and rear of the car together so they can react in
performance enhancing ways, as we’ll see shortly. Now we’ve seen how weight transfer affects the
platform or the ‘attitude’ of the car as the car is pushed hard on track.
Turning through a corner forces the weight to shift towards the outside of the car,
lowering the outside of the chassis and raising the inside in a rolling rotation.
Under braking, the weight shifts dramatically towards the front, moving an extra 300 or
so kilograms over the front tyres under the heaviest braking loads for a second or two.
This dramatically lowers the front end and lifts the rear end in a pitch rotation.
We can also consider how, at high speeds, the aerodynamic load across the entire car
increases, pushing it into the ground, lowering the whole car.
In all of these cases, the aerodynamic platform - that is, the angle and height
that the car sits relative to the ground - is shifted away from its ideal setup.
We’ll want the car to be as low to the ground as legally allowed and pretty flat.
Though, quite a few teams like a car to be designed with a bit of rake - that
is having the rear end higher than the front to turn the whole underbody into a big wing,
essentially - you don’t want the car moving too far away from that ideal platform.
So naturally, two bad things happen during moments of roll, pitch and heave.
One is the car’s attitude changes - its platform moves away from an ideal from an aerodynamic
point of view - and this is particularly noticeable in the significant downforce
gained from underneath the car. The other is that part of the floor
is getting much lower to the ground. And while that may be obvious, what this means
is you need to raise the neutral ride height of the car to stop the car hitting the ground
under aerodynamic load. Not ideal when you want to keep the car as low as possible at all times.
So, to combat all of this: what if, when the car breaks and the front suspension loads up,
we could use this front suspension load to tell the rear suspension to compensate
and level the car out, gaining more control over the car’s platform angle?
We’ve sort of seen this already with anti-roll mechanisms in dampers and anti-roll bars
(go see my earlier suspension videos for a refresher on that), whereby
load on outside suspension will bring the inside suspension lower
to reduce roll as required. But that’s across the car, left-to-right. What about front-to-rear?
Well teams have explored various ways of achieving this for many many years going
back through the sport, with mechanical and electronic systems doing this kind of work,
including active suspension, with driver and computer controlled suspension elements
controlling all four points of suspension. But the system that was gaining traction,
particularly with the Mercedes team, up until the ban in 2014, was a hydraulically connected
passive system. Passive here just means the driver has no input - the suspension
is just reacting to mechanical forces. So, from previous videos we remember the
heave damper - a sprung piston which compresses as both left and right
suspension are put under load together. Let’s pretend the floor of the car is
completely parallel to the ground under neutral load, just for simplicity.
Under braking, the front heave damper will compress as the front lowers,
and the rear heave damper will extend as the rear goes light. The car is pitching forwards.
So at the front, the pressure of the fluid in this chamber increases as the piston compresses.
So you could connect this high pressure chamber with hydraulic piping to the opposite chamber at
the rear heave damper so this pressure is transferred, through the piping,
to this chamber and forces the rear to lower, rebalancing the whole car.
The front end is loaded up and lowers, the heave damper compresses, pressure builds in
this chamber and is transferred to the rear heave damper, lowering the rear.
You can do the same in a cross connected way so that if the rear is put under heavy load,
maybe during acceleration and you don’t want the car to pitch backward,
you can transfer some of the load pressure in the heave damper from the rear to the front to
stabilise your platform in the other direction. You could also have a hydraulic loop in place
across similar chambers of the front and rear heave pistons so that as both ends of
the car are compressed - for example, under heavy aerodynamic load at high speeds - the
two pressure increases resist each other and dampen the overall drop in car height.
Now of course you can also do this directly between right and left suspension points to
control how the car rolls and you can cross connect all four points of the
car to control both pitch and roll at the same time - a rotation known as ‘warp’.
For example, into a corner your car will pitch forward under heavy braking and then
want to roll as it turns. At certain points it will be experiencing warp - pitch and roll at
the same time. In a fast corner, you’ll want to reduce roll to maximise aero stability,
but in a slower corner you’ll want to let the car roll a little to help with mechanical grip across
the tyres, all while minimising the pitch. To have greater control over how this all
works you need to add some flow control values to your hydraulics which dictates
how readily your fluids move in a given direction. In essence you can have all four points of the car
simultaneously affecting each other if they are connected in a clever way via
various flow control valves that passively switch over as required, depending on differences in
pressure across your system. Pretty clever. What all this means is, in reality,
you could chuck out your conventional springs and dampers and control the whole cars suspension via
interconnected hydraulics across the car, with flow control values acting in
lieu of your conventional dampers and springs. Most teams had some variation of this system,
to different levels of sophistication, by 2014, whereby the FIA got the teams
to agree to its banning as the systems were so sophisticated they were moving into territory
of being moveable devices that control the aerodynamics. Which was already illegal.
As FRIC suspension was only developed as an aerodynamic aid, there wasn’t much in the way
of argument, so the 2015 technical regulations included clauses that mandated that front and
rear suspension systems must only respond to loads from their respective wheels. And that was that.
With the move towards more underbody-focussed aerodynamics from 2022 onwards there was some
talk of allowing things like active suspension back into the sport. Part of me thinks there was
no particularly strong case for throwing this clever technology completely out of the window.