This online course is aimed at engineers who want to improve the setup of their race car in a mathematically sound way. In addition, it is also aimed at Bachelor and first-year Master students in automotive engineering.
Detailed description of the content of the book:
Chapter 1 Measurement: Describes how all dimensions which an engineer ought to know – like the position of the centre of gravity in three directions, wheel loads, moment of inertia, camber, caster, track, KPI, motion ratio, aerodynamic drag etc – can be measured and calculated. These dimensions will be discussed throughout the book.
Chapter 2 Definitions: From a vehicle dynamic point of view, a corner can be divided in 5 phases, and each phase has its own cause for under/oversteer. To solve this it is vital to understand during which phase of the corner the car is showing its attitude. The phenomena understeer and oversteer are explained in detail. Also it is described how under/oversteer can be measured and calculated.
Chapter 3 Tyres: the non-linear character of the Coefficient of Friction is explained, and how the anti-roll bar is making use of that. Also it is explained how to manage tyres in terms of their pressure, humidity and temperature, and the interaction between these dimensions. A method is given for measuring and calculating the Traction Circle.
Chapter 4 Shock absorbers: how dampers deliver their forces of a large amplitude at low-frequency and by the same token forces of a low amplitude at a high-frequency. Different types of dampers are discussed, plus the mathematics of hydraulic damping. By means of examples it is shown how the proper damper rate is being determined. An eye opener is the way the dampers influence the behaviour of the car, especially in the transient phase of pitch to roll and vv. Finally the use of histograms is explained.
Chapter 5 Suspension geometries: Geometry is an often underestimated phenomenon. Too often problems caused by a non-optimal geometry – about which the engineer is not aware of – are being solved by excessive settings of the springs, dampers, etc. This chapter describes the interaction between KPI and caster, and the influence of the geometry on the tyres wear and temperature. The importance of the positions of the roll centre and the pitch centre are being described in large detail. load transfer and jacking forces are discussed extensively. On top of that a method is provided for the construction of a bump steer free geometry of the steering mechanism. Finally the Ackermann principle is discussed.
Chapter 6 Mass-spring system: Many useful methods of measuring, calculating and assessing torsion bars, coil springs and leave springs are presented. Both linear and progressive coil springs are calculated. A deeper insight in the motion ratio is given. A method of interpretation of the spring diagram from your springs is given. Resistance against roll and pitch is calculated. Weight and balance is shown. Finally the calculation of anti-roll bars is given.
Chapter 7 Differentials: The difference in wheel speed between the inner and outer driven wheels during cornering has to be facilitated by the differential. This chapter discusses locked versus open differentials, and provides calculations of the torque bias. The relation between a locked differential and tyre behaviour is being discussed. Various tips, calculations and examples are provided. Finally the differential effect for electric hub engines is assessed.
Chapter 8 Aërodynamics: After discussing the elementary theory concerning aerodynamics the boundary layer, drag, downforce, air density and gurney flaps are being explained. With the aid of explanatory calculations the influence of wing settings and undertrays are made clear. Also the influence of vortex generators and golf ball profiles on wings is shown. Furthermore the optimum aero balance is found, and an assessment is given of finding the drag and downforce values from (existing race) data, resulting in enlightening aero-maps and graphics. Finally an example of CFD simulation on a formula car is shown.
Chapter 9 Tests: how to prepare for a test, how to run the tests, and how to interpret the results. Key elements in the handling of race cars are being discussed, like the test of dampers, tyres and aerodynamics. Besides that, the dynamic behaviour of a race car is discussed by elaborating on load transfer during banking, distribution of the roll resistance, weight distribution and the balance of the static mass.
Chapter 10 Simulations: Laptime simulations can be very helpful in finding a good setup in a relative short time. By simulating all sorts of setups, the engineer will learn much about the car, and will be better prepared for trying out the optional settings at the track. This chapter describes the use of two simulations packages: CarMaker and ChassisSim. The software, however, will return a laptime plus data after each run, but it remains the engineer who will have to interpret these data intelligently and decide concerning the next improvement.
Chapter 11 Five Magic Numbers: In this chapter all you have learned in the previous chapters comes together to calculate the 5 Magic Numbers. Based on the data from an imaginary example car, the following main numbers are being calculated in 10 steps:
Percentage front static weight
Percentage front roll resistance
Percentage front load transfer
Percentage front aerodynamic load.
With these data in mind, an engineer is able to make the right and quick decisions, and to choose useful setting to start lap time simulations.
The total online training consists of more than 14 hours of training at bachelor level.
About the Authors:
Prof. Dr Ralph Pütz teaches combustion engines and transmission technology at Landshut University of Applied Sciences. As an avid motorsport enthusiast and active Formula 3 driver, he also regularly passes on his experience to his students in the practical course Motorsport Practice and Chassis Setup.
Ton Serné BSc is a trained mechanical engineer who has spent more than 40 years working on the subject of the road holding of racing cars. He has not only been a mechanic, race engineer, team manager and designer, but also a racing driver in formula racing cars and touring cars. He would like to pass on his experience and knowledge to young students.