Race Car Handling Optimization: Magic Numbers to Better Understand a Race Car

Description

The reader will first learn to measure his racing car himself in order to ultimately get to know and understand the car's setup better. This is followed successively by the teaching of the basics with the claim of immediate applicability of the knowledge. First, the most important properties of the tyres are described in order to convey how to optimally utilise the properties of the tyres. Only then are the mass-spring system, shock absorbers, anti-roll bars, suspension geometries and aerodynamics dealt with, with the aim of making the best possible use of the tyres' potential. What has been learned is optimally applied to driving through a curve, divided into five essential phases of the corner, and an analysis for possible causes of understeer and oversteer is carried out for each phase, and solutions are given. Finaly examples of laptime simulations are being described, and the book ends with a very clear description of the calculation of the Magic Numbers regarding Roll, Roll Resistance, Load Transfer and Total Wheel Load. Introduction Contents 1 Measurement of the Setup Abstract 1.1 Main Dimensions and Centre of Gravity 1.2 Static Axle Loads and Horizontal Centre of Gravity 1.3 Vertical Centre of Gravity 1.4 Moment of Inertia at Vertical Axis 1.5 Suspension Measurement 1.5.1 Camber 1.5.2 Track 1.5.3 Caster 1.5.4 Kingpin Inclination (KPI) and Scrub Radius 1.5.5 Steering Angle and Toe Angle Difference 1.5.6 Motion Ratio 1.6 Aerodynamic Parameters Aerodynamic Parameters 1.7 Summary Reference 2 Introduction and Definitions Abstract 2.1 Significance of Handling and Roadholding 2.2 Vehicle Movements and Degrees of Freedom 2.2.1 The five Phases of a Corner 2.2.2 Description of the five Phases 2.3 Understeer & Oversteer 2.3.1 Centripetal Force or Lateral Force 2.3.2 Centrifugal Force (or: The Invisible Hand...) 2.3.3 Balance 2.4 Determination of Understeer and Oversteer 2.4.1 Method 1 2.4.2 Method 2 References 3 Tyres Abstract 3.1 Non-Linear Characteristic of the Tyre 3.2 The Coefficient of Friction 3.3 The Anti-Roll bar as a Means for Influencing Load Transfer 3.4 “Kamm’s Circle”—or More Precisely: The Force Ellipse 3.5 The Influence of Tyre Pressure and Temperature 3.6 Diagonal Versus Radial Tyres 3.7 Interpretation of Tyre Wear References 4 Shock Absorbers Abstract 4.1 Damper Types 4.2 Damper Characteristics 4.3 The Vehicle as a Reduced Quarter-Vehicle Model 4.4 Assessment of the Dampers Under Racing Conditions Further Readings 5 Geometry Abstract 5.1 Suspension geometry and its significance 5.2 Kingpin Inclination and Caster 5.3 Toe-In and Toe-Out 5.4 Roll Centre and Pitch Centre 5.5 Geometry, a Fascinating Compromise 5.6 Effect of Forces in the Suspension 5.6.1 Load Transfer, Roll and Jacking Forces During Cornering 5.6.2 Load Transfer During Braking and Acceleration 5.7 Ackermann’s Principle 5.8 Analytical Determination of the Motion of a Double-Wishbone Suspension Reference 6 Springs Abstract 6.1 Reasons for Springs in Suspension 6.2 Spring Rate and Spring Types 6.3 Calculation of a Spring 6.4 Roll and Pitch Resistances 6.5 Weighing 6.6 Anti-Roll Bars 6.6.1 Adjustable Anti-Roll bar 6.6.2 Conventional U-shaped Anti Roll bar Reference 7 Differentials Abstract 7.1 Need for Differentials while Cornering 7.2 Locked Differentials Versus Open Differentials 7.2.1 General Information 7.2.2 Disadvantages of Open Differentials 7.2.3 Locked Differentials 7.3 Analysis of the Effect of Torque Bias/Locked Differentials References 8 Aerodynamics Abstract 8.1 Downforce Through Aerodynamic Measures 8.2 Basics in Fluid Technology 8.2.1 Energy and Mass Conservation During Flow 8.2.2 Laminar and Turbulent Flow and Boundary Layer 8.3 Drag and Downforce 8.4 Measures for Generating Downforce 8.4.1 Gurney Flaps and Winglets 8.4.2 Acceleration of the Flow Under the Vehicle Floor and Diffusor 8.4.3 Vortex Generators (Turbulators, Canard Flaps) and the Golf Ball Effect 8.5 Optimum in Aerodynamic Balance 8.6 Assessment of Downforce and Drag from Race Data Acquisition 8.6.1 Analysis of the Dynamic Ride Heights on the Front and Rear Axles 8.6.2 Analysis of the Movement of Suspension on the Front and Rear Axles 8.6.3 Creation of Aero Maps 8.6.4 Achievable Maximum Speed on a flat straight 8.7 Application of Computational Fluid Dynamics Further reading 9 Test Drives Abstract 9.1 The Theory is internalized—now Practice follows 9.2 The Five Characteristic Phases of a Corner at a Glance 9.3 Definitions of Different Tests 9.4 Specific Targeted Tests 9.4.1 Damper Characteristics 9.4.2 Load Transfer 9.4.3 Distribution of Roll Resistance 9.4.4 Weight Distribution and Balance 9.4.5 Aerodynamics 9.5 Tyre Modelling from Race Data 9.5.1 The Purpose of Tyre Modelling 9.5.2 Tyre Modelling by ChassisSim 9.6 Tests for Amateur Teams Reference 10 Simulation of the Handling Dynamics Abstract 10.1 CarMaker 10.1.1 Subsystem Vehicle Including Tyres 10.1.2 Test Runs, Driving Manoeuvres and Driver 10.1.3 Implementation and Documentation of the Simulation 10.2 Chassis Sim 10.2.1 Introduction 10.2.2 Toolboxes 10.2.3 The Importance of Transient Simulations 11 Magic Numbers and Other Important Calculations Abstract Acknowledgements Conversion Tables Index