Discussion in 'Car Modding' started by doddynco, Oct 27, 2021.
Where are the spindle positions defined and how do I change them?
In the chassis file ini, together with coordinates for wheels
I just can't figure out why, when loaded into dev mode, the strut mounting points overlap, but in ptool it shows a gap. Even the auto generate ptool shows a gap. So where is dev mode pulling these dimension from and why is it different to ptool?
Chassis.ini (dev mode input)
Chassis with auto sub systems.ini (dev mode output)
@doddynco what do you mean by "overlap"?
I can't work out what the issue is.
If you look where the rear suspension attaches to the rear subbody, there is a gap in Ptool. But in dev mode, the spindle is seemingly moving inwards automatically, and it keeps the suspension points in the same relative position. So now the inner attachment points have moved towards each other and overlapped.
Ah. Now it's obvious. Very obvious. I should have seen that
Are you setting the Track in the hdv? That will override the track width.
Ok so I think I know what I've done here. I thought that track width was the distance between the two tyres, when it's actually the center to center distance. The distance was set correctly in the HDV, but in the spread sheet and in Ptool, the car has an extra tyres width because of my misunderstanding, of which the geometry was then built around. Dev mode then keeps the strut points the same relative to the tyre, whilst forcing tyre position.
Easy to fix now I understand what's happened. I just need to add on half a tyres width to all the inboard strut mounting points, springs, and steering rack.
I only realised this when I started playing with the trackwidth in the HDV and that really helped me troubleshoot, so thank you. I could see then that I can override the 3d model tyre positions. I forgot I could do this and was relying on the mysterious 3d model dimensions (which I did not make, and can't view) so I was completely lost. Turned out to be so simple.
Yes, this is the reason for which, when you are not sure your physics model is perfectly fitting the 3d model ( and therefore trackwidth, or wheelbase ), it’s better to put in HDV values 0 to width and wheelbase
Shouldnt the track width be set to be measured at the outside of the tyres not the centre ? If it is the centre then surely this is flawed as in racing we always measure form the outside.
No, the track width should be calculated in a realistic way, that is with 2 x 1/2 distance between wheel center and the car center.
It's the same concept of the wheelbase size.
When You consider the wheelbase of a car, for example, You don't consider the lenght of car as wheelbase, but the distance between front and rear axle.
Kart racing currently Lazza but isnt a major issue I just wasn't aware this was how the dimensions were determined in rF2 also, so now I have to go and redo my kart mods so they reflect these principles
I think in something like karting it would be easier to measure outside to outside (especially if you're measuring toe the same way), and to some extent you could really use whatever method you wanted as long as everyone is on the same page. (for specifying/comparing setups or cars/karts)
For proper calculations though, roll rates etc as per Milliken et al, you really need to use the proper definition.
Yeah all good and now I am aware I also have work to do on my other mods I have created that are not karts ;P
Question in relation to this answer:
So in the spreadsheet you seem to have to enter figures for track and wheel base (not ZERO because it reflects in the chassis file generated)
i understand that the HDV pushrods position is set with this too
So are you guys changing to Zero in the HDV manually after exporting?
hope it makes sense what i am asking??
Yes, You are right.
In the spreadsheet You can put realistic data. But then, when You put these data in HDV, if your 3d model is not perfectly reporting the same wheelbase ( or track wide…) size, it’s better to leave 0 in HDV.
The negative aspect of this, however, is that physics will correspond to the wheelbase of the model and not to yours.
For example: You make with spreadsheet a file with 3.0 of wherlbase; the 3d model car is made featuring 2.5 wherlbase.
When You put 0 in HDV, car behaviour will be that of 2.5 wheelbase car
Therefore: 0 in HDV is a good solution when there are minimal differences between wheelbase of spreadsheet and 3D model.
It’s easy to understand that when a 3d model is made well, with scaled size, commonly your spreadsheet data may be put in the HDV
Thanks very much Nic,
the model is really super close so we can move everything to the real data for sake of the physics.
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