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Annotations restricted to this tutorial Notes before we begin. While this tutorial section is designed mainly for beginners, even those whom consider their skills advanced may learn something new from this tutorial. Generally, this section describes where to start, gives basic definitions, and gives more examples. After reading this, we recommend you visit the physics glossary if you wish to have each variable described in full. Before starting to try make a car realistic it's important to gather as much technical information as you can. I know this is the boring part, but it will really serve you well. Beginners especially have a tendancy to overlook this fact. In fact, gathering data will often be nearly as difficult as altering the actual physics parametres themselves. In reality, most racing teams know the majority of data that would need to go into these files. Unfortunately, teams are usually unwilling to disclose this sensitive information. It would make things comparitively easy if you could have all this data. Regardless, I would recommend you try to find as much as possible, because if you find data to the contrary later, it will usually consume significant time to re-match lap times and/or performance specs again. To give you a general idea, I spend approximately one quarter to a third of my time just researching. Reference photos and other materials can be of great assistance too, especially if technical data is scarce. Photographs most useful are particularly those high-resolution non-perspective suspension photographs. Measuring the photos will give you base values to create suspension geometry. Even if you can get hard data on anti-dive, camber change, toe-change, etc. you may find using these pictures useful to create a base and work from there. Normally, it would be best if the model has been completed before you start the physics. Though that might not be possible, at the very least, the wheels should be in the correct position. If there is any chance of them moving the suspension geometry may need changing, along with other variables. If you reposition the supsension arms at a later date (due to model changes), this will often result in erronous data entries, and at the least, is not favourable. Once the wheels are in the final position, take measurements of where the pivot points are (or ask the modeller for these co-ordinates), it is best to use these co-ordinates for the suspension file, though often not 100% necessary. Wheelbase and track should be 100% correct. If the wheel position of the model has not been positioned as yet and you are aware of the vehicle track and wheelbase you can plug these values into the HDV, you will find these variables under the [SUSPENSION] section. Before creating any physics, I suggest you download EngNet Converter. EngNet converter is a tool that will VERY accurately convert values into other units, such as Horsepower to KiloWatts, or KPa to PSI. I have created a small list of commonly used units in terms of car manufacturers specs, and those used in rFactor. Unit conversion. Because some people misunderstand the range values, they have been further explained here. All the Setting= values create an initial car setup when there is no setup file (*.SVM file) to go from. Remember that 0 is actually the first setting in these cases. The first setting is 0, 2nd is 1, etc.
Introduction - Information Gathering Getting started The first step is to copy the physics files from an original rFactor file which you think is most similar to the vehicle you are creating physics parameters for. Information gathering possibilities will vary according to which vehicle you are creating physics for. If you are developing physics for a vehicle you own, or have the availability to take measurements from and or test, that is a great way to learn. If you own the car, not only do you know how it drives, but you can make some calculations and take measurements straight from the source. The best way to develop physics is to start with the knowns. Always start with the knowns. Mass is the most obvious thing. It's (generally) easy to find, it's a definate that won't need changing in the future. Altering mass will provide you with greater vehicle accuracy and unlike many other values it is not a subjective opinion. If you can weigh the car yourself that's great. It's best to try weigh it with driver and fluids but not fuel. If the car has been weighed with fuel that's ok, just try estimate how much fuel is in the car. Each litre of fuel weighs approximately 0.75kg, from this you could conclude within reasonable accuracy, the weight of the car. If the car weighs 1380kg, with 80 litres of fuel, the real weight should be around 1320kg (80*0.75=60kg 1380-60=1320kg). If you can't measure the weight try to find a reputable source, but make sure you know the method of weighing used. Generally, weight given is curb weight. Curb weight is measured as car + engine fluids (oil, coolant, etc.), no driver, and no fuel. There are many exceptions to this though, you will also find that these conventions are not always followed. Dry weight is vehicle weight without fluids and driver. Formula one vehicles are weighed with fluids, and driver. Next is engine power. To calculate power the following formula applies:
The next value I suggest you change are the RPMTorque values. The engine power curve is located in an engine.ini file (though it could be named almost anything). I have created an excel power curve approximately correct for a Nissan Skyline R32 GTS-T. It peaks at around 212hp @ 6200rpm. Download. You will need to use a suitable spreadsheet program that can view Microsoft Excel spreadsheets to open this file. If you don't have Microsoft Office, I recommend Open Office, it's a great open source office style program, and is free. Ideally, you should try and get access to a real power curve graph. Often you will not be able to so. Generally peak power and torque should be sufficient to reasonably accurately estimate the entire power curve. Torque should be negative at low end because an engine can not overcome friction at 0 rpm (with the obvious exception of an electric motor, which actually produces peak torque near this point). Most engines will not be able to overcome friction forces until they spin to approximately 250-500rpm. An engine should not produce negative torque at any point afterwards, however after the Over Rev/ fuel cut out/RPM limiter the motor should not produce much above 0 NM of torque, going into negative values here is acceptable. Unless you know better and have tried it for yourself, the fuel cut/rev limiter is generally about 200-300rpm over the redline. A Nissan Skyline R32 with a RB20DET for example, engages a fuel cut (rFactor can't simulate this, RPM limiter is close enough though) at just under 7800rpm while the redline is only indicated at 7500rpm. Note that the redline in a race car is also usually the rev limit. Negative power torque should never be greater than engine braking torque, as throttle application never reduces torque. Tires, in the HDV file you should change the name of TireBrand= to something suitable that will be unique to that vehicle or mod. You may consider making it specific to the brand & type of tires. Copy and paste the original game vehicle with the most similar tires. You may choose to use tires from another mod too, but make sure you have permission BEFORE taking any such actions unless you keep the vehicle for private use. The first thing you'll want to do with these tires is give them correct dimensions, Width= & Radius=.
To calculate width, simply take the first value of a specification such as 265/40 R17, then divide the first value by 1000. This converts to a game ready value of 0.265.
Now that you have read this tutorial, feel free to visit the Physics Glossary for more information on specific variables. [Top] Thank you for reading this tutorial, if you have any questions or suggestions feel free to contact one of the creators here. |