While the MR2 has been partially converted to rf2, I’ve run into some graphical roadblocks. Because so much effort was put into making the car look good, I don’t want to release it for rf2 until it is possible for it to look as good as it does in rf1. We should be getting regular updates, so things might turn around. For now I’ll continue working on the new bodykit, which just needs the reflections smoothed out.
MR2 status update
January 15th, 2012MR2
August 25th, 2011
Tire cam videos
July 5th, 2009Here’s some vids while you wait for an update. Stay tuned, something new might be around the corner.
Tire pressure and load
June 7th, 2009This writeup is about how tire load affects the optimum tire pressure, and how it is defined in the tbc file.
If you’re reading this, you probably already know that tire pressure affects the contact patch. Too much pressure and only the center of the tire touches the ground. Too little tire pressure and only the two outside edges touch the ground. Well, tire load affects the contact patch similarly. A heavily loaded tire will tend to sag as if it were under pressured. Likewise, a lightly loaded tire will tend to crown as if it were over pressured.
The optimum tire pressure to best suit the track and driver must be found for every event. When I say ‘and driver’, I really do mean there is some preference in selecting tire pressures. That’s because it also affects the springrate and the sidewall flex. More tire pressure gives a stiffer springrate, and less sidewall flex resulting in lower slip angles and can result in lower tire temperature. There can be a compromise between feel and grip if a driver likes the tight, responsive feel from a high pressure, but also wants the grip given from lower a pressure.
One can also use tire pressures to give unique handling characteristics. For example high front tire pressures can improve front grip when the front tires are heavily loaded such as during turn-in and in high speed corners. Likewise low rear tire pressures can improve rear grip in low-load situations such as during braking and exiting slow speed corners. Both of these characteristics are often desired, and can partially explain why front tire temperatures tend to crown and rear tire temperatures tend to sag.
That should about cover the general idea. Here are the relavent lines in the tbc:
SpringkPa=1200.00
// Spring rate per unit pressure
OptimumPressure=(60.5, 0.0221)
// Base pressure to remain flat on ground at zero deflection, and multiplier by load to stay flat on ground
GripTempPress=(2.50, 1.40, 1.00)
// Grip effects of being below temp, above temp, and off-pressure (higher number -> faster grip dropoff)
I’m not certain how ISI defined ‘optimum’, and it seems only marginally useful to look up the values while making setups for an unfamiliar mod.
That’s all folks!
Coulthard funnies
May 20th, 2009
about 40seconds in…