Car parameters for vdrift-2009-06-15 and older
The file's fields are mostly the same as the Vamos car parameters, explained in the Vamos docs. The units are all in MKS (meters, kilograms, seconds). It might also help to read The Physics of Racing by Brian Beckman.
The file contains several sections. Each section will now be described, along with example values from the XS.car file.
Top level parameters
drive = RWD
The only top level parameter is the "drive" parameter. It accepts values "RWD", "FWD", "AWD" that correspond to rear wheel drive, front wheel drive, and all wheel drive, respectively.
Steering
max-angle = 33.19
This defines the maximum angle that the wheels will turn in each direction. For the XS, when the steering wheel is full left, the wheels would be at -33.19 degrees.
Engine
position = 0.86, 0.0, -0.21 mass = 140.0 max-power = 1.79e5 peak-engine-rpm = 7800.0 rpm-limit = 9000.0 inertia = 0.25 idle = 0.02 start-rpm = 1000 stall-rpm = 350 fuel-consumption = 1e-9 torque-friction = 0.0003 torque-curve-00 = 1000, 140.0 torque-curve-01 = 2000, 149.14 torque-curve-02 = 2200, 145.07 torque-curve-03 = 2500, 147.78 torque-curve-04 = 3000, 169.50 torque-curve-05 = 3300, 172.19 torque-curve-06 = 4000, 169.50 torque-curve-07 = 4500, 166.77 torque-curve-08 = 5600, 172.19 torque-curve-09 = 5800, 170.83 torque-curve-10 = 6000, 168.12 torque-curve-11 = 6100, 177.61 torque-curve-12 = 6200, 186.42 torque-curve-13 = 6300, 192.53 torque-curve-14 = 6500, 195.92 torque-curve-15 = 6700, 195.92 torque-curve-16 = 7000, 195.24 torque-curve-17 = 7600, 190.49 torque-curve-18 = 8000, 184.39 torque-curve-19 = 8200, 183.04 torque-curve-20 = 8300, 146.43 torque-curve-21 = 9500, 146.43
The position and mass parameters affect the weight distribution of the car. The torque curve is calculated from max-power and peak-engine-rpm using a polynomial expression given in Motor Vehicle Dynamics, Genta (1997), where peak-engine-rpm is the engine speed at which the maximum power output (max-power) is achieved. Alternatively, the torque curve can be explicitly defined, as in the example above. A rev limit can be set with rpm-limit. The rotational inertia of the moving parts is inertia. idle is the throttle position at idle. Starting the engine initially sets the engine speed to start-rpm. Letting the engine speed drop below stall-rpm makes the engine stall. The rate of fuel consumption is set with fuel-consumption.
Clutch
sliding = 0.27 radius = 0.15 area = 0.75 max-pressure = 11079.26
The torque on the clutch is found by dividing the clutch pressure by the value in the area tag and multiplying by the radius and sliding (friction) parameters.
Transmission
gears = 6 gear-ratio-r = -2.8 gear-ratio-1 = 3.133 gear-ratio-2 = 2.045 gear-ratio-3 = 1.481 gear-ratio-4 = 1.161 gear-ratio-5 = 0.943 gear-ratio-6 = 0.763 shift-delay = 0.08
The number of forward gears is set with the gears parameter. The gear ration for reverse and all of the forward gears is then defined. The shift-delay tag tells how long it takes to change gears. For a paddle-shifter, like a modern Formula One car, shift-delay can be set to zero.
Shape factor ........................................... A0 Load infl. on lat. friction coeff (*1000)... (1/kN) .... A1 Lateral friction coefficient at load = 0 (*1000) ....... A2 Maximum stiffness ........................ (N/deg) ..... A3 Load at maximum stiffness ................ (kN) ........ A4 Camber infiuence on stiffness ............ (%/deg/100) . A5 Curvature change with load ............................. A6 Curvature at load = 0 .................................. A7 Horizontal shift because of camber ........(deg/deg).... A8 Load influence on horizontal shift ........(deg/kN)..... A9 Horizontal shift at load = 0 ..............(deg)........ A10 Camber influence on vertical shift ........(N/deg/kN)... A111 Camber influence on vertical shift ........(N/deg/kN**2) A112 Load influence on vertical shift ..........(N/kN)....... A12 Vertical shift at load = 0 ................(N).......... A13 Shape factor ........................................... B0 Load infl. on long. friction coeff (*1000)... (1/kN) ... B1 Longitudinal friction coefficient at load = 0 (*1000)... B2 Curvature factor of stiffness ............ (N/%/kN**2) . B3 Change of stiffness with load at load = 0 (N/%/kN) .... B4 Change of progressivity of stiffness/load (1/kN) ...... B5 Curvature change with load ............................. B6 Curvature change with load ............................. B7 Curvature at load = 0 .................................. B8 Load influence on horizontal shift ....... (%/kN) ...... B9 Horizontal shift at load = 0 ............. (%) ......... B10 Load influence on vertical shift ......... (N/kN) ...... B11 Vertical shift at load = 0 ............... (N) ......... B12 Shape factor ........................................... C0 Load influence of peak value ............ (Nm/kN**2) ... C1 Load influence of peak value ............ (Nm/kN) ...... C2 Curvature factor of stiffness ........... (Nm/deg/kN**2) C3 Change of stiffness with load at load = 0 (Nm/deg/kN) .. C4 Change of progressivity of stiffness/load (1/kN) ....... C5 Camber influence on stiffness ........... (%/deg/100) .. C6 Curvature change with load ............................. C7 Curvature change with load ............................. C8 Curvature at load = 0 .................................. C9 Camber influence of stiffness .......................... C10 Camber influence on horizontal shift......(deg/deg)..... C11 Load influence on horizontal shift........(deg/kN)...... C12 Horizontal shift at load = 0..............(deg)......... C13 Camber influence on vertical shift........(Nm/deg/kN**2) C14 Camber influence on vertical shift........(Nm/deg/kN)... C15 Load influence on vertical shift..........(Nm/kN)....... C16 Vertical shift at load = 0................(Nm).......... C17
