• Guest, RaceDepartment is now on Discord!  Join Here
Alternate Physics 1.0 CTF for RFPE all cars (Increased CG height and more)

Alternate Physics 1.0 CTF for RFPE all cars (Increased CG height and more) 1.0b

Log in to download, or make sure to confirm your account via email
Summary of update 1.0b
Installation instructions included in zip.

Main differences in this update

-center of gravity height increased (more pronounced weight transfer, longer more accurate braking distance).

-increased longitudinal slip, less wheel spin longitudinally under throttle, lateral is the same as before, (based on real world telemetry for gravel and tarmac)
-cars are more neutral interaction, less understeer, more oversteer on braking on gravel.
-increased peak grip for gravel, but lowered rolling resistance so cars are easier to rotate at lower speeds, (they don’t bog down or understeer as much at lower speeds) with just a flick of the wheel or tap on the brake can send the car in a controlled slide that is easier to recover from.


-Aerodynamics, returned side force values to original spec, this was experimental and it was too strong of a setting. It made cars less responsive to steering inputs and added understeer. Downforce is still present and higher at faster speeds so you are rewarded for pushing the car at higher speeds.
-mid engine 037 and Stratos have higher friction lower slip angles for the rear fatter tires, easier to control less oversteer on corner entry but still a handful.

Issues -Alpine and Renault 5 turbo rear tyre grip do not respond to modding. Also, their initial vanilla physics are different than any of the other cars so I have given up on them as far as tyres go. The other values (weight, inertia, etc are still modded)

-fixed correct rev limits for a lot of cars, including modern WRC cars rev up to a correct 8500 rpm now.


*For the center of gravity height I used real data as much as I could find. For example WRC Focus 07 raised cg height from 34 cm to a more accurate 40. This makes a big difference in the way the cars drive.

Info about Dirt Rally loose surface model


Learned more about how the handling model works by looking at an early 0.3 version of the game which included a surface_materials.mxl in the main directory. This file is hidden in the latest version. It includes all the surfaces with different depth and soil densities for loose surfaces. The CTF custom files that I’ve been editing are just the reference tyres values that interact with the surface values from the surface_materials file which has over 21 different surfaces. (including different values for the compact soil where tyre tracks are located)
The surface file is hidden in the latest 1.23 version of the game so I cannot edit all the different surfaces so any changes that I’ve made are still tyre reference values that interact with the values of all surfaces.
This is why setting a reference slip angle for the same tyre will still yield different results since the actual slip angle depends on the tyre value interacting with soil density, soil depth, car properties, suspension setup, weight dist. Cg height etc) and this is how it should be.
There is a hard gravel tyre used in Greece and dry Finland and a soft gravel tyre which is used in all of wales (cold and damp weather) and rain Finland. Same for tarmac dry tarmac compound and wet tarmac compound, snow and ice so six tyres for all the courses used.

(I want to thank Come Over Gaming for the RFPE plugin and the ability to mod the physics

also lots of thanks to Avo77 and Forzakof for helping me with the ctf values)
0.9 beta

-Increased central downforce (except for Pikes Peak, these have strong aero effects already and just modified to correct drag coefficients)
cars with aero kits are more noticeable, more grip at higher speeds, cars don't fly as high on jumps.
-changed drag coefficient and frontal area to realistic values
-fixed vagueness in steering for RWD cars
-tweaked tarmac to higher grip
-added separate CTF files for gravel/loose surfaces and tarmac, this affects suspension height and settings which cannot be changed when using RFPE plugin.


INSTALLATION
This update includes the RFPE launcher and plugin.dll

extract Alt Physics 0.9 files in Dirt Rally main folder, choose gravel or tarmac before etracting for correct suspension height.

Start RFPELauncher then start game

(I thank Come Over Gaming for the RFPE plugin and the ability to mod the physics
also lots of thanks to Avo77 and Forzakof for helping me with the ctf values)

jump.jpg
  • Like
Reactions: kari-tan and miky90
0.8 Hotfix

Fixed grip from copying error for all RWD and FWD cars for gravel, wet gravel and snow. Sorry about that. Too many cars.
  • Like
Reactions: 顾不语
0.8
-Incremental increases to yaw and pitch inertia, more pronounced weight transfer, reworked values to compensate for driver and copilot weight. Used real vehicles for reference as much as I could find, as well as an inertia calculator for rfactor2.

Increasing the yaw inertia proportional to driver and copilot,
added weight makes cars behave better over jumps, cars were already more planted before but this update makes Finland a lot more drivable. Also, with the increased inertia it is harder to recover from a really high jump.

This is a comparison between WRC STI 0.7 version on top and 0.8 on bottom

jump.jpg



I recommend using the brakes mid air to adjust the pitch forward and gas to make the car lean backward while midair.

Also cars suspension soaks up bumps better so RWD cars are not as twitchy in the rear when cornering. Cars carry more speed through corners so brake a little earlier.

-Set default braking bias on RWD cars to be more neutral, easier to trail brake,
brake bias adjustment doesn't seem to work in game with the plugin but all other car settings work normal.


INSTALLATION
This update includes the RFPE launcher and plugin.dll

extract Alt Physics 0.8 files in Dirt Rally main folder

Start RFPELauncher

(I thank Come Over Gaming for the RFPE plugin and the ability to mod the physics)

I recommend turning down throttle sensitivity and driving slower with new physics.
Changes in 0.7
(Working on downforce/aero next update)

Increased brake torque values, brakes properly lock up on gravel.

Tweaked Greece dry gravel, sliding friction doesn't drop off as much as Wales, (was able to get more information on dry gravel)

Tweaked rear slip angles on gravel tires, there is more of an initial lag/understeer when tires first start to dig in heavy gravel.

Car still oversteers under high throttle, heavy braking and high body angles.
  • Like
Reactions: miky90
INSTALLATION (Included basic RFPE Plugin in rar file)

extract all files Alt Physics 0.6 CTF files in Dirt Rally main folder

Start RFPELauncher

0.6
Incremental changes and fixes in this version


Increased grip for Group B and Group A to more closely match WRC cars, gravel grip was lower on these cars and it was really difficult to keep on track in rain gravel compared to other awd cars. Still not as grippy as 2000s and modern WRC cars but more manageable.
Increased slip ratio for gravel to match deep gravel.
Longitudinal slip comes at a higher wheel spin, feels more natural, engine bogs down before reaching redline doesn't spin as freely like it is on ice. Change is not drastic from 0.5. Wet gravel will still spin more freely.
Lateral grip remains the same as 0.5 version.

-Audi Quattro Sport RPM revs up to 8000, HP peaks at 7500
changed weight to correct fully loaded weight, as well as weight balance.
-Fixed power of Ford Cosworth, doesn't feel as sluggish.
  • Like
Reactions: miky90
I uploaded a zip containing 2 sets of ctf files. The second folder contains the updated renault 5 turbo.

Date created on r5t should be 11/14/17
INSTALLATION
After installing RFPE plugin 0.4
extract Alt Physics 0.5 CTF files in Dirt Rally main folder

(I thank Come Over Gaming for the RFPE plugin and the ability to mod the physics)

I recommend turning down throttle sensitivity and driving slower with new physics.

-Increased mass to account for drivers, co-pilot and fuel.
-Used Dash Meter Pro to adjust grip level to match real telemetry for tarmac and gravel.
-Braking should be done earlier, car weight transfer is more pronounced. Trail braking and oversteer under braking more pronounced. Brakes lock up easier in corners.
-Fixed understeer under braking in Ford Escort MKII and other RWD cars.
-Increased rpm limit on Audi Quattro Sport to 7,500 rpm
-Fixed weight distribution of Lancia S4 from 55% front to a correct 45% front

Dirt Rally Telemetry using Dash Pro Meter
lateral_grip.jpg

WRC Reference Tire
wrc_Tarmac.jpg

Tarmac tyre based on WRC Spain tarmac

It peaks at 8-10 degrees slip angle
1.4-1.5 lateral gs
grip drops down by 30-35% just like real WRC telemetry.

gravel wet rough.jpg




Gravel telemetry is erratic to see the typical Pacejka curve because of the erratic nature of driving on gravel. Too much suspension movement and steering but you can see it has higher slip angles than tarmac. Lateral (gs) peak at about 50-60 % of tarmac.

references for wrc telemetry

Measurement and Analysis of Rally Car Dynamics at High Attitude Angles - Michael Croft

PS
still working on figuring out aero values.
The cars on gravel feel like they are sliding but the wheels don't completely lock up until the very end of a slide or unless the car is at an angle. Seems to be an ABS or gravel piling effect in straight line that I haven't been able to completely get rid off. The wheels do lock up on rainy tarmac.
  • Like
Reactions: miky90
Previous version I erroneously thought values for wet gravel were independently set which is why heavy/medium gravel felt like mud even in dry conditions. Gravel grip increased by 8%. Characteristics are the same as before. I settled on these values by comparing my times to real world WRC footage of Fiesta in the last section of Bidno Moorland and I am consistent at 1:12 secs with room for improvement, real world time for same section is around 1:10.

Ideally, the game should have 6 different surfaces to edit (dry heavy,medium,light and wet heavy medium and light) however it only has 2 main different types of gravel settings and then another section controls wetness and other types of surfaces)
Reworked the difference between rolling/ optimal friction to final/sliding friction to match real world data (WRC articles).
Tarmac grip falls down by 20%/26% so sliding is only recommended in sharp turns and hairpins, otherwise you are losing too much grip (just like in real life)
Gravel and snow falls down by 10% so there is still grip to be had in the stalled region (optimal slip angle 15-16 ° based on real WRC data)
New slip angles for Tarmac 6.2 ° ,(more response from steering wheel) 16°s for Gravel, 15 ° for Snow, Ice 12.3° (winter studded tire used as reference)
Fixed Rallycross (AI drivers don't spin out in certain sections)
R4 cars don't feel floaty and wheel spin is properly modeled.
More info coming.

Method to my madness below

Graphs for Grip vs Slip Ratio and Grip vs Slip Angles.



Tarmac_grip_vs_slp_ratio.jpg
gravel grip vs slp_ratio.jpg
sno.ice grip vs slp ratio.jpg

tarmac-slip_angle.jpg
gravel slp. angle.jpg
snow.ice_slp_angle.jpg
  • Like
Reactions: miky90
Added Pikes Peak, 2000, Rallycross, 1960's, 1970's.

Enjoy!!!!

  • Like
Reactions: Jonathan Menéndez