Picking one F1 ban that you would like to see lifted

When I was asked recently whether there was anything that had been banned in Formula 1 that I would like to see reinstated, I had to exercise a significant amount of discipline to pare down the list.

Creativity is, after all, a significant part of what attracts engineers to the sport, and the frustration of seeing that creativity deemed ‘illegal’ is just something we get used to.

Some of those innovations such as the Brabham ‘fan car’ or the Williams FW08 six-wheeler obviously represented a significant amount of engineering resource. Others, although apparently less complex such as the tuned mass damper we ran on the Renault some years ago, still required significant development time.

Going through my long list I tried to balance what might have been fun to develop but was either too expensive or perhaps not relevant. The tyre war of the mid-2000s was an example of the first, and things like the F-duct maybe fall into the latter category.

What eventually rose to the top was active suspension. I must admit a vested interest here, having developed the Benetton system in the early 1990s, which I regard as perhaps the most interesting of the many engineering projects I’ve been involved in.

The main difference between an active and a passive system is that, as well as storing and dissipating energy as a passive system does, the active system can introduce energy to the suspension.

Brabham’s BT46B ‘fan car’ won on its debut at the 1978 Swedish Grand Prix – then was withdrawn by the team

Photo by: Sutton Images

To control a car with a fully hydraulic active suspension system requires significant energy and such systems are termed ‘high bandwidth systems’. In F1 only Lotus employed such a system. More common were low bandwidth systems, used by Benetton, McLaren and Williams.

At Benetton, we used gas springs to both absorb bump energy and give the basic support to the aerodynamic loads. There was also a small passive damping element, which just dealt with the ‘wheel hop’ frequency of around 18Hz. The main system could deal with all the normal pitch, bounce and roll frequencies as well as controlling the vehicle ride height at anything up to around 10-12Hz.

The hydraulic actuators ran at a pressure of around 200 bar (3000psi) and the maximum power the system used was around 7kW, although this would only be instantaneous, the average power being much lower.

In some ways it was too good initially because in trying to keep a constant height relative to the centre of the Earth, it wanted to drive through hills rather than follow them

The reason these systems were so good was not just that they could control the ride height but that they could do so without the need for a very stiff suspension. Stiff suspensions are poor for grip on anything other than an ultra-smooth surface because, rather than being compliant and allowing the tyre to maintain good ground contact, they let the tyre bounce off the bumps, reducing the vertical load that the tyre needs to promote grip. 

At Benetton we built our own onboard computer to control the system, which worked on the principle known as skyhook control. This replicated a system whereby the chassis was suspended from a virtual skyhook at a constant height above the centre of the Earth. The wheels then moved independently of this.

In some ways it was too good initially because in trying to keep a constant height relative to the centre of the Earth, it wanted to drive through hills rather than follow them. Once the vertical accelerometer signals were passed through a high pass filter set at a very low frequency, this problem was solved.

Symonds, here sharing a joke with Michael Schumacher, reckons active suspension was his most interesting project

Photo by: Sutton Images

As well as controlling ride height, the system also eliminated roll. In fact, the chassis banked inward to counteract the compression of the highly loaded outside tyres. Although we experimented with power assisted anti-roll bars, the best solution came from controlling roll purely hydraulically.

This gave us the advantage that we could dynamically control the roll stiffness distribution and, based on sensing whether the car was understeering or oversteering, we could control it back to a neutral state.

The drivers also had a manual control so they could dial in the handling balance they liked. We could even map this to distance around the circuit to save using the manual control continually and leave the driver to compensate purely for things like uneven tyre degradation.

I was recently reminded how good active suspension is when I drove a Cadillac Celestiq, which has active damping and active air springs, at a demanding test track. On a washboard surface that made every other car move sideways, the Celestiq didn’t even register a disturbance.

Today, an active F1 system would be particularly suited to the extremely low ride heights current cars need to run at to extract maximum performance.

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With its active suspension, Cadillac’s Celestiq impressed Symonds mightily – and so it should at more than £300,000 a pop…

Photo by: Cadillac Communications