Success is all about being in the right place at the right time ….. and the axiom is a guiding principle for designers of motorsport circuits. To avoid problems you need know where and when things are likely to go wrong before cars turn a wheel –and anticipating accidents is a science.
Take barriers, for example .there is little point erecting them in the wrong place –but predicting the right place is a black art. The FIA has developed bespoke software, the Circuit and Safety Analysis System (CSAS), to predict problemareas on F1 circuits.
Where and when cars leave circuits is due to the complex interaction between their design, the driver’s reaction and the specific configuration of the track, and the CSAS allows the input of many variables-lap speeds ,engine power curves, car weight changes, aerodynamic characteristics etc –to predict how cars may leave the circuit at particular places. The variables are complex. The impact point of a car continuing in a straight line at a corner is easy to predict, but if the driver has any remaining control and alters the car’s trajectory, or if a mechanical fault introduces fresh variables, its final destination is tricky to model.
Modern tyre barriers are built of road tyres with plastic tubes sandwiched between them. The side facing the track is covered with conveyor belting to prevent wheels becoming snagged and distorting the barrier. The whole provides a deformable ‘cushion’ a principle that has found its way to civilian roads. Barriers made of air filled cells, currently under investigation may be the final answer. Another important safety factor is the road surface. Racing circuits are at the cutting edge of surface technology, experimenting with new materials for optimum performance.
2. Circuit and Safety Analysis System (CSAS)
Predicting the trajectory and velocity of a racing car when it is driven at the limit within the confines of a racing track, is now the subject of a great deal of analytical work by almost all teams involved in racing at all levels. However, predicting the trajectory and velocity of a car once the driver has lost control of it has not been something the teams have devoted a great deal of time to. This can now also be analyzed though in the same sort of detail, to assess the safety features of the circuits on which it is raced. The two tasks are very different, and the FIA had to start almost from scratch when it set out to develop software for its Circuit and Safety Analysis System (CSAS). [pic]
The last two decades have seen a steady build up of the R&D effort going into vehicle dynamics modeling, particularly by those teams that design and develop cars as well as race them. The pace of development has been set by the availability of powerful PC's, the generation of vehicle and component data, and the supply of suitably qualified graduates to carry out the work. Their task is to be able to model and predict the effects of every nuance of aerodynamic, tire, engine, damper etc., characteristic on the speed of their car at every point on a given circuit. The detail in the model will only be limited by available dynamic characteristics and track data, and will require a driver model to complete the picture. However, they are only interested in the performance of the car while the tires are in contact with the tarmac, and the driver is operating them at or below their peaks.
Fig.1. Examples of straight trajectories.
Fig.2. Examples of all possible trajectories.
Fig.3. Stopping distances in the run-off area, highlighting points where the run-off is inadequate to stop the car.
Fig.4. Residual velocity, perpendicular to the boundary of the run-off area.
Fig.5. Residual velocity, perpendicular to a 2-row tyre barrier, after impact with it.
The FIA, on the other hand, starts to be interested in what happens when the driver exceeds the limit...