Picture the scene. It’s a quiet Friday afternoon - sunny sky, gentle breeze - when suddenly the silence is broken by the roar of a 3 litre V10 engine tearing past you. Your quiet Friday is, in fact, being spent watching a Grand Prix practice session. If you are not actually trackside, then you are more than likely in front of the TV back home. Whilst you’re enjoying the race, your friend - a newcomer to Formula One - asks you, “Why do they spend so much time plodding round the circuits when not actually competing with each other?”
To be honest, you can't quite say. A lot of fans find the length of Grand Prix weekends, and the amount of testing done between races, puzzling. The normal family saloon/estate car doesn’t ever have to be adjusted or optimised. You don’t say to the wife, “I’m just going to test the car before we go shopping.” The overall design of the family car is the same for everybody and, once the car leaves the factory, never needs altering. Surely, with all the money they throw at the F1 car during its design and manufacture, they can make it perform ‘out of the box’ as well - can’t they? The answer is basically, no. Even the most sophisticated car design cannot allow for, or adjust, to the wide variety of tracks and corners that the F1 season covers. The car’s handling properties must be finely adjusted for each individual track if the driver is to get the most out of his steed. Also, different drivers prefer their cars to handle differently. You've probably already read car magazine reviews that go to great lengths to describe each car's handling characteristics. You are also probably aware of the problems that many of Michael Schumacher's team-mates have had adjusting to his particular settings.
What is a set up then? Basically, the setup is how the driver likes each of the parameters of his car - suspension, aerodynamics, tyres - to be adjusted to suit his individual style and the changing conditions of the track. A car is said to oversteer, understeer or remain neutral and drivers prefer their individual car to handle to different degrees of these:
Oversteer: A car is oversteering when it feels as though the back is going round faster than the front. The car appears to want to turn into the corner at a steeper angle than the driver wanted. It is caused by a lack of traction at the rear either through lack of mechanical grip or too much acceleration.
Understeer: A car is understeering when the front doesn’t want to grip the road, and prefers to head to the outside of the corner at a narrower angle than the driver would wish. It is caused by a lack of grip at the front or too much speed through the corner.
So what can the driver and engineers of the car alter to optimise its handling? This week we're going to deal with tyres, suspension, aerodynamics and ride height adjustment:
Tyres
One of the most important aspects of the modern Formula One car is the tyres. They're noticeably larger on an F1 car than on a standard family car and have no tread. The reason for them being slick is to maximise the surface area of the tyre and, therefore, prevent overheating. Of course, when it rains there would be no grip, since the tyres would be running on a cushion of water. Wet tyres therefore have a deep tread to disperse the water.
The requirement of the tyres is to provide a contact patch between the car and the road. Obviously this contact patch must be as large as possible. The engineers can alter the size of this contact patch by altering the tyre pressure. A modern Formula One car's tyres are run at around 100oC for optimum grip. Any higher, and the tyre is being worked too hard: any less, and the full grip potential of the tyre is not being used.
The drivers and engineers can determine whether a tyre is being used to its optimum by measuring the temperature at the middle and outside extremes. If the contact patch is ideally sized, then the three measurements should be fairly equal. If the central temperature is too high, the centre of the tyre is working too hard and needs to be deflated slightly. If the extremities of the tyre are too high, the tyre needs to be inflated slightly. The front tyres usually operate at a pressure of 23-24 psi and the rears at a pressure of 19-20 psi. If one side of the tyre is working harder than the other, then the angle of the tyre can also be adjusted. This phenomenon is due to the tyres being pressed into the ground whilst being driven. The contact patch of the tyre alters as all the other aspects of the car are adjusted and, consequently, the tyres are often one of the last parameters to be adjusted.
Suspension
The suspension of a Formula One car has to carry phenomenal loads. It is used mainly for weight transference - sorry Mr. Driver, no smooth rides here. In fact, tyre squash provides the main source of ‘comfort’ for the driver over bumps. Despite having a spring on each tyre, the suspension is grouped as front and rear. Indycar drivers use springs on each corner, since they are permanently cornering - this can lead to unusual handling when braking in a straight line though. The springs are graded as hard, soft or a variety of levels in between. Hard springs provide less overall grip but offer the driver a more responsive feel for the car. Soft springs provide better grip, but cause the car to roll and pitch excessively. Think of how a very soft bed reacts as you move around on it. Would you want your car’s suspension to handle like that? I think not. The driver must find a suitable overall stiffness for the course, and a balance of stiffness between the front and the rear of the car if he is to prevent oversteer or understeer.
Aerodynamics
The most noticeable difference between a standard road car and a Formula One car is the large wings at the front and back. These are shaped in a similar way to airplane wings, but inverted to generate downforce rather than uplift. As the angle of these is increased, the downforce increases. This is fine, but for one problem - drag. Time for another ‘Toby Waller Home Science Lesson’. When you’re next in your car, stick your hand out of the window (for those of you who haven’t seen previous articles, don’t forget to check if it’s safe to do so first!). See how the force pushing back on your hand varies as you rotate it. When your palm is pointing downwards, there is very little force. When you point your palm forwards, the force on it is intense - even more so, the faster you travel. In fact, a Formula One car's drag coefficient (a measure of a car's effectiveness at reducing drag, the higher the value the less effective) is usually around 1.0 - your standard road car probably has a value around 0.3. This drag effect limits a car’s top speed. At tracks with long straights, where time can be gained by having a faster top speed, the wing angle is minimised. This results in less downforce - a problem when it comes to cornering. The compromise is hard to find for a driver, but see how the wing angle varies massively on a car between a tracks with very different natures such as Hockenheim and Monaco. There also must be a balance between the front and back wings to prevent oversteer and understeer. Sorting out the difference between aerodynamic and suspension handling is the often mark of a great driver.
Ride Height
Whilst the wings on top of the car are the most noticeable producer of downforce, they are not the only aerodynamic part of the car. When a car travels close to the ground, the air rushing between the underside and the road creates a vacuum effect that helps to suck the car onto the tarmac. This was very noticeable during the days of flat bottomed cars, but has a lesser effect now that the mandatory 50mm step has been introduced. The step reduces the amount of undercar area that is situated close to the track, thus reducing overall downforce. The actual thickness of this gap must be closely controlled - of the order of millimetres - and the suspension and tyre squash must be taken into account. As the car pitches and rolls under braking, acceleration and cornering, the ride height - and therefore downforce - at the four corners of the car varies. Cars are nowadays set very stiff to take account of this and help prevent any rotation of the car.
In 1992, the Williams team successfully adopted a technology known as Active Suspension. The suspension springs were replaced by gas filled containers that could be adjusted. The dip and roll of the car could be controlled and, therefore, downforce and grip increased. The technology was costly and difficult to develop and has now been banned. The extent of the effect was so great that Nigel Mansell, when testing the active car for the first time, returned to the pits after one lap complaining of no brakes. He had been fooled by the lack of dip that he normally associated with a normal suspension car.
Well, that's it for this time. Hopefully you're a little wiser now and you’re beginning to understand the complexity of the cars. Next issue we'll be dealing with the finer points of brakes, engine settings, gear ratios, fuel and wet weather settings. See you then.