Kangaloosh carFactory

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What is Kangaloosh carFactory

Kangaloosh.com Homepage (Defunct):

  • carFactory lets you define the physical characteristics of a car's suspension and will then generate suspension geometry, spring rates, damper settings and roll bars to meet your needs.
  • carFactory currently generates the physics files for rFactor, which is currently the racing simulator offering the most realistic physics engine.
  • In the near future carFactory will output real-life data for use in designing home-built specials or for smaller race teams.

[1]

Informer.com Page:

  • carFactory is a car suspension simulation software that lets you create a new set of suspension or edit an existing one by defining physical characteristics, like springs rates, tire types, dampers, roll bars and other configurations intended for racing simulation software like rFactor.
  • The goal of this software is to tweak your models’ handling by modifying ratios and other real world settings, then run an analysis of the configuration and build a model with the results. Once you have a nice configuration you can load this data to your model in the racing software, and test it either online or locally.
  • Unless you are dedicated to design suspensions and know all the ratios, specs and data, you might need to take the Getting started guide in the website, and download some files in order to start modifying your own settings.
  • CarFactoy lets you define the type of chassis you want by choosing in a drop list from the monocoque type to a space frame or a structural frame and tub, then define the wheel base distance in mm, the total mass in kg, specify the front and rear tires, the roll bar type, camber, and see the solutions for rear and front suspension independently through graphics like roll center migration and roll camber rate.
  • And in the analysis section you can even load a specific curve to graph the slip angle versus the grip factor for the tire set.

[2]

Gallery

Resources

Status

Guides

Getting Started

Getting started with Kangaloosh! carFactory - Part I 'Caterham Classic'  
		
	

This guide will take you through the steps of creating a new car based on an existing Mod.

You will need V0.8.2 or later of carFactory to follow this guide.

We will use the Caterham Mod by Major Parts / Cubits, so you need to download and install that before you start.  If you plan to race on-line then make a backup of your Caterham folder, because we will be changing the .pm and .hdv files.

We will create a road-spec version of the Caterham Classic mod.  As downloaded this is quite racy, stiffly sprung and damped with virtually no roll.  We will be creating a version as close as possible to the showroom spec as the current version of carFactory allows.

Click on the 'Open .hdv' button and browse to the \Program Files\rFactor\GameData\Vehicles\Caterham folder and choose Classic.hdv.

Load an existing mod

The Wheelbase and track dimensions will be propagated across the Car, Front Suspension and Rear Suspension tabs.

Now enter the following accurate values for the rest of the boxes on the Car tab:

Total Mass:        610kg
Front/ rear split    46%
CofG Height        365mm

We can now estimate a rough set of inertia values.  Make sure that 'Behind front axle' is set for the engine location and 'Spaceframe' is chosen for the chassis configuration and click 'Estimate'.

Your screen should now look like the following:

Editing the car properties

Save your work so far; click File -> Save -> Car and save the Car as RoadClassic.car.  CarFactory will automatically save the Front and Rear Suspension and Ride and Roll settings with matching filenames.

Click on the 'Front Suspension' tab and enter the following details:
Tyre spec:            185 60 R 14
Roll centre height:        21mm
Camber:            -2.0 deg
Roll camber rate:        0.3 deg / deg
Ride height:            110mm
Bump travel:            80mm
Rebound travel:        80mm
Kingpin inclination:        11 deg
Scrub                36mm
Castor:            5 deg
Ackerman angle        40%

These are all accurate values except for the bump/rebound travel, but +/-80mm should be fine for the smoothly surfaced tracks available in rFactor.

Here is what your Front Suspension tab should now look like:

Editing front suspension

 Move on to the 'Rear suspension' tab and enter the following values:

Tyre spec:                185 60 R 14
Roll centre:                175mm
Camber:                -1.3 deg
Camber rate:                0.4 deg / deg
Ride height:                110mm
Bump travel:                80mm
Droop travel:                80mm

The roll centre, at 175mm, looks quite high compared to the front axle's roll centre.  The Caterham Classic in real-life has a DeDion rear axle.  The roll centre of a DeDion axle is exactly where it is connected to the Watts Linkage, which is limited by ride height considerations from being any where near the ground.

Choose 'De Dion with Watts linkage' from the Arrangements list.  Your 'Rear Suspension' tab should remble the following:

Editing rear suspension

Now click on the 'Ride and Roll' tab.  The usual way to design a car's spring rates is to work from desired ride frequencies, but we know that a Caterham Classic fitted with a 1.4 K Series engine has 150lb front springs and 170lb rear springs, which convert to 24079 N/m front and 27261 N/m rear.  Also,  the springs do not act directly on the wheel centres, but slightly inboard.  They are also mounted at an angle to the vertical which gives us Motion ratios of approximately 1.3:1 for the front and 1.25:1 for the rear.

Click the 'Spring Rates' radio button and enter the following values:

Spring rate front:            24079 N/m
Motion ratio front:            1.3
Spring rate rear:            27261 N/m
Motion ratio rear:            1.25

You will see that the corrected Wheel rates are automatically calculated.

Now we need to set the damper settings.  A K-Series Caterham Classic comes as standard with Bilstein F4 B48 1899 H0 front dampers and F4 1900 H0 rear dampers.  I have absolutely no idea what valving is fitted so we will have to let carFactory work out sensible damper settings by entering Damping Ratios and letting it calculate the required low and high speed bump and rebound values.  A sensible value for a road / race or track day car as sporty as the Caterham is in the 0.5 to 0.65 range.  One of Colin Chapman's documented beliefs was that there is nothing wrong with a softly sprung car as long as it is well damped, so we will go to the upper end of that range:

Set the front and rear damping ration to 0.65.

Again, we have no idea what transition speed is used by those Bilstein dampers so leave the 0.127 m/s Transition Speed unchanged.

Now we will set the roll bar values.  A K-Series Caterham Classic has a 900mm wide front roll bar with 200mm effective lever lengths, a motion ratio of approximately 2:1 and an outside diameter of 1/2” (12.7mm).  Unfortunately without cutting one in half it is very hard to know the inside diameter!  So we will specify a sensible roll gradient and TLLTD and let carFactory work out the technical details:

Enter a value of 1.5 deg / G for the roll gradient and a value of 53% for the TLLTD.  1.5 deg roll in a 1G corner is about right for a fairly racy road / track car and a value of 53% TLLTD puts the handling balance 7% in front of the centre of gravity (46%, we entered it on the 'Car' tab), to give a car that will be stable in very mild understeer unless provoked by sudden lift or application of power.

Save everything again, Click File->Save->Car.  Your screen should resemble this:

Editing spring, damper and roll bar settings

Now we must build our front and rear suspension.  Go to the Build tab, choose standard build quality (Low is only still there to help with rapid debugging and testing, it should never be used otherwise.) and click 'Build'.  You should now be able to view and choose a front suspension solution:

Browse front suspension solutions in 3D, adjusting your trade-off preferences in real-time

The carFactory manual explains how to choose a trade-off between scrub, roll centre migration and camber rate.

Once you are happy with your solution for the front suspension, return to the 'Build' tab, select 'Rear Suspension' and click 'Build' again:

The single DeDion rear suspension solution

Because we chose a 'DeDion' arrangement there is only a single solution.

We can now generate our .pm and .hdv file snippets:

Go to the 'Generator' tab and click 'Generate':

Generate rFactory physics file snippets

You must now use Notepad to open the Classic.hdv and Narrow.pm files in the Program Files/rFactor/GameData/Vehicles/Caterham folder.  If you have never worked with cars in rFactor before you will need to be exceedingly careful to copy everything to the correct location.  A sigle typo can cause rFactor to crash when loading the car, with no helpful error message or error log explaining the reason :-(

The .pm file produced by carFactory is an entire replacement for the existing car's Narrow.pm file.

The .hdv snippets must carefully replace the existing settings in their respective sections ([GENERAL], [SUSPENSION], . . .).

You are now ready to load up rfactor and try your new car.  The more experienced may prefer to create a new .veh file that points to new .hdv and .pm files thus preserving the existing Caterham Classic.  It will certainly make side by side comparison easier.

What you should find is a softer, more forgiving Caterham, that matches the existing Classic mod's lap times very well.  Despite suspension far more suited to the road than the track, the new geometry makes the tyres work harder making up for the road specification, right up until the brick-like aerodynamics cause terminal high speed understeer!

Basic Manual

Basic Manual  
	
Car Page

'Based on existing rFactor mod':  Choose this setting to browse for an existing .hdv file.  carFactory will import the tracks and wheelbase, wheel and upright locations and use them unchanged in the generated .pm and .hdv snippets.

'A new rFactor mod': Choose this setting to start from scratch, entering new values for track and wheelbase.
Suspension

Roll centre:
All suspension has a geometric roll centre about which the car pivots. Enter a value in mm above the ground. Unfortunately the geometry alters as the suspension deflects and one of the aims of good suspension design is to prevent the roll centre from migrating wildly.

Roll camber rate:
This is the amount of camber you would like added to the static camber for each degree of body roll. Tyres like a bit of negative (top in) camber to compensate for contact patch distortion in cornering. As the car rolls, if the wheels to not have any camber gain they will present a reduced contact patch to the track.
e.g. A rate of 1 deg/deg will add 1 degree of additional negative camber for every degree of roll causing compression and add 1 degree of positive camber for every degree of roll causing rebound.

Ride height:
This is used as a constraint to prevent the generation of solutions with suspension control arms dangling below the car!

King Pin Inclination:
The angle that the virtual king pin formed by the outer ends of the two wishbones makes with the vertical. Positive angle is top towards the centreline of the car. Also known as SAI or steering axis inclination.

Scrub Radius:
The lateral distance between the centre of the tyre's contact patch and the point where the extended line of the kingpin intersects the tyre's contact patch. Positive scrub radius adds feel under braking for rwd cars as the tyre with most grip exerts a trque efect around the steering axis. Fwd cars should have this set nearer to zero to avoid torque steer.

Castor:
Angle that the virtual king pin formed by the outer ends of the two wishbones makes with the vertical. Positive angle is top towards the back of the car. Adds stability but causes mechanical trail.

Trail:
The longitudinal distance between the centre of the tyre contact patch and the point where the extended line of the kingpin intersects the tyre's contact patch. Adds stability but causes mechanical trail.

Ackerman %:
For a normal road car that never slides this should be 100%. There is a good explanation on Wikipedia. For a race car it is not so straightforward as the tyres are always sliding (hopefully at their maximum slip angle) while cornering. The ackerman angle is therefore dependent on the relative slip angles of the tyres on the front and rear axles. In extreme cases 100% negative Ackerman might be appropriate.
Rear Suspension

Settings as for front.
Build

1. Choose an axle.

2. Choose how many cups of tea you want to drink :-; The low setting should not really be used except as a test to make sure that carFactory is happy with the settings you have entered. The solution envelope produced at this level is so 'lumpy' as to be next to useless. The setting was more to help me debug without waiting 90 seconds for a sensible build.

3. At the moment I have greyed out the server option for the downloads, I am not sure I want half the rFactor community hammering away just yet . . . .
Choosing a Solution

At the moment carFactory will only offer Double Wishbone or DeDion solutions.  In the future multilink arrangements may be available. (and then you will have time to seed a tea plantation, wait until harvest, crush the leaves yourself and make a well deserved cup of ta before the solution envelope completes, or ask nicely to use a server or two . . .:-)

Don't bother playing too much with a Low quality build, the results of moving the sliders may become counter intuitive due to the low quality of the solution set.

carFactory has selected the best configuration it could find for every permutation and combination of the trade-offs between scrub, roll centre migration and camber rate accuracy. You use the sliders to explore this envelope to choose the configuration you would like to drive.

The Envelope

(Skip this bit if Mathematics send you into a coma)
The solution set is a three pointed circle. Either visualise an equilateral triangle with curved sides or a circle with three equidistant points marked around the circumference.
In a perfect solution the circle would be dished downwards somewhere between a disc and a hemisphere. Double Wishbones are constrained by the track / wheel rim size (got to fit the upright inside the rim) / ride height etc. (I will add more constraints later) So the solution set is an undulating dish. The higher the build quality the more smoothly it undulates. Quality is not proportional to the number of solutions but is proportional to the smoothness.
Imagine the sliders as three magnets that attract or repel a ball bearing inside this dish. With a slider set to zero you repel the ball to the far side, with the slider set to 100 you are on full tractor beam. As the ball slides around the charts are loaded with the behaviour of each solution the ball is resting upon.
The statistical accuracy of any single solution is proportional to its distance from the geometric centre of the three pointed circle. If ever you achieved a perfect hemisphere then the lowest point, in the middle would imply zero scrub, zero roll centre migration and perfect camber rate.
When you click the search button , it finds the point on the surface that is furthest from the centre of the circle. This may not be the best point for you. For example if the total range of scrub is less than 5mm over full scale deflection of the suspension you may be willing to ignore scrub completely and manipulate the sliders to find the best trade off between roll centre migration and camber rate.
Ride and Roll

This tab lets you define your handling requirements for the chassis.

Specify spring rates either as front and rear frequencies, in Hz.  (You can enter values manually for either Wheelrate or Springrate).  In general rear frequency should be 20-25% higher than front frequency to prevent harmonics.  Typical settings are about 1Hz for a comfortable road car, 2Hz for a track-day car and possibly as high as 10Hz for extreme downforce sports cars.

Damping ratios are typically 0.25 for comfortable road cars, with lots of suspension travel, about 0.5 for a track day car and maybe 0.75 for a very racy ride.

The transition speed may be changed.  This speed is the damper piston velocity at which the suspension is no longer coping with handling behaviour but is starting to cope with bumping over kerbs.  Ideally the transmissibility should be reduced for these impacts by having reduced high speed forces.

The roll bars can be specified by a roll gradient and TLLTD or by entering the values manually.

The roll gradient is the degrees of body roll required in a 1-G corner.  Not many zero-downforce cars, 2CV for example, will achieve 1G so you must extrapolate a value.  Typical values might be 40 deg for a 2CV! , 2 deg for a hot Gti, 1 deg for a track car down to a fraction of a degree for formulae cars - in the mid-90s Williams F1 cars appeared to be rolling into the corner, a negative roll gradient!  If the spring settings you have chosen mean that the car already has a stiffer roll gradient then a little blue exclamation mark will appear – hover the mouse over it to see an explanation.

The TLLTD, or total lateral load transfer distribution is a measure of the handling balance of the chassis.  The roll bars main function is to tune how much weight transfer in roll is split between the front and rear wheels.  Make the front wheels work harder to induce understeer and make the rear wheels work harder to induce oversteer.  In general a value 5% forward of the front/rear weight distribution is used for racy cars.  The further in front of the CofG, the more the chassis wants to understeer.  The further aft, the more it wants to oversteer. A value equal to the front/rear weight distribution would give you a neutral but unstable car with no natural tendancy to keep the front wheel ahead of the rear ones on the limit!  The definition of TLLTD is not consistent.  MoTeC have a consultant who promotes the concept of the 'Magic Number' and deprecates TLLTD - in fact they refer to it as the relative roll resistance of the antiroll bars alone, not so terribly useful.  Despite the marketing hype it would appear that their magic number is merely what everyone else calls TLLTD!

It may not be possible to achieve the handling balance you require with roll bar settings.  If so a little blue exclamation mark will appear.  Hover the mouse above it to read the explanation.

Two factors outside carFactory's control can make any effort you put into this screen worthless.  If your roll centres migrate wildly or if your mod uses a .tbc file with unusual settings.  Do check that the mod uses a tyre (.tbc) file that does not defy the laws of physics :-)
Generator

Creates an entire .pm file and snippets for the .hdv file. At the moment the fuel tank and driver head are arbitrarily located.

Don't forget to use the Estimate button, or to enter your own values for the car's inertia settings.

The .hdv snippets should be inserted into the [SUSPENSION] and [FRONTLEFT] etc. sections of your .hdv file.

If you based the car on an existing mod, the wheel and spindle settings will have been copied verbatim.

Trivia

About Page - From The Defunct Homepage

About: [4] 

Despite building carFactory I'm afraid I have no academic or professional qualifications in any engineering discipline.  I did, however, grow up surrounded by parts of my parents' vintage cars and motorbikes and can remember, at an age when most children would be playing lego, being sat cross-legged on the floor of the garage sorting a tin of nuts, bolts and washers into metric, BSF, ASF and Whitworth.  For a while in my late teens I worked as a motor mechanic for Terry Hoyle Limited in Maldon, Essex, who at that time restored Ferraris and built race car engines.  I have never worked in more beautiful surroundings since then, nor have I achieved much as rewarding as helping to rebuild a 275 GTB/4 engine.  Perhaps art historians feel the same way about the paintings they restore? 

I got to ride in some fairly interesting machinery (MG 6R4, part of a batch Terry Hoyle made road legal, and various Ferraris), though unfortunately as a teenager the closest I got to driving was blipping the throttle of a Koenig 512 Boxer on a four-post lift, while somebody below listened to the butterflies chattering on overrun.

I.T. offered a more lucrative future and that was the end of my professional career, such as it was, in motorsport.  A career in I.T. means I am better than most at creating bugs in software.  Combined with a non-existent academic background in engineering means carFactory is built on the two shakiest foundations of any software product known to man.  Despite this it seems to work quite well.
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