Add drag to any car from Upgrade

P

PlanRZ

Guest
Hello, is it possible to add drag effect to any car with an Upgrade ?

I've seen some parameters like RWDragParams tweakable in Upgrade ini file.
How to manage that if it is usable ?

I would like to add some drag effect to add speed to the car behind more effective,
to add more chance to overtake on straight lines.

Thanks for any info on the subject.
 
You can modify every Entry from the HDV in Upgrade ini Files, by using the Syntax HDV=.
For Example for the RWDragParams, you would use.
HDV=
HDV=[REARWING]
HDV=RWDragParams=( X.X, Y.Y, Z.Z)
 
Keep in mind there are two kinds of upgrade files. For upgrade as a whole different model, and as upgrade as components for a model. I remember I got stuck very bad once because not knowing that.

These drag values for this main parameter are not X;Y;Z. They are - base drag value>drag value change per aero setup setting>and third is exponential value that adds per aero settup setting.

There is also main drag value in [BODY] section. You can also have some drag manipulation by assigning certain drags per radiator setting and brake duct setting. You can have radiator settign to work as grille tape setting, but I personally had poor luck with grille setting as it have had extremely minimal effects comparing to simple radiator change.

You can also alter several other not aero dependant values to alter top speeds. For example, changing how much tires get expansion due to high rotational velocity. I found that you can even assign a lot of tire rolling resistance by tweaking .TGM and bascially almost get a flat tire effect haha

If you want to add speed to car behind, or car in front due to slipstreaming there are these values, I have never worked with them, but I suppose they work:


Code: 
BaseDropoff=0.165            // RFM Drafting override: Higher number -> more drafting effect (default=0.185)
LeadingExponent=2.1          // RFM Drafting override: Higher number -> lower effect on leader (default=2)
FollowingExponent=2.1        // RFM Drafting override: Higher number -> lower effect on followers (default=2)
VehicleWidth=1.89            // RFM Drafting override: Helps determine base width of wake (default=1.9)
SideEffect=1.00              // RFM Drafting override: Negative effects of side-by-side drafting (default=0.35)
SideLeadingExponent=2.0      // RFM Drafting override: Added to regular LeadingExponent to affect the side wake
SideFollowingExponent=25     // RFM Drafting override: Added to regular FollowingExponent to affect the side wake

Also there is an interesting parameter to assign slipstreaming effect severity on radiators cooling efficiency. Just little spicy fun thing, to make people suffer and to be sad, when they have to actually do something instead of just sprinting mindlessly for six hours.
 
Adding drag to a device like the rear wing does not 'add' speed to the trailing car. Using the drafting lines provided above by @mantasisg should provide the overtaking advantage you are looking for.
Or...you can save yourself a ton of grief by choosing cars like the BMW Class 1 or the rFPro that have DRS.
 
I tried multiple combinations, and nothing seems to work, only BodyDragBase alone which only affects max speed.

UpgradeLevel="DropoffLeadFollow"
{
HDV=
HDV=[BODYAERO]
HDV=DraftBalanceMult=1.0
HDV=BodyDraftLiftMult=1.0
HDV=BaseDropoffLeadFollow=(0.09,0.18)
}

:confused:
 
DanRZ said:
I tried multiple combinations, and nothing seems to work, only BodyDragBase alone which only affects max speed.

UpgradeLevel="DropoffLeadFollow"
{
HDV=
HDV=[BODYAERO]
HDV=DraftBalanceMult=1.0
HDV=BodyDraftLiftMult=1.0
HDV=BaseDropoffLeadFollow=(0.09,0.18)
}

:confused:
Click to expand...
Did you try higher values in the LeadFollow parameter?

(and no, you don't need to put any in you don't want to change)
 
I'm using the Porsche Cup and try to add draft effect.
Later, i will try higher values on BaseDropoffLeadFollow like (1.00,1.00).

UpgradeLevel="DropoffLeadFollow"
{
HDV=
HDV=[BODYAERO]
HDV=BaseDropoffLeadFollow=(1.00,1.00)
HDV=
}

The Porsche Cup have almost no draft effect at all. Easy to check on LeMans straight.
 
DanRZ said:
I'm using the Porsche Cup and try to add draft effect.
Later, i will try higher values on BaseDropoffLeadFollow like (1.00,1.00).

UpgradeLevel="DropoffLeadFollow"
{
HDV=
HDV=[BODYAERO]
HDV=BaseDropoffLeadFollow=(1.00,1.00)
HDV=
}

The Porsche Cup have almost no draft effect at all. Easy to check on LeMans straight.
Click to expand...
Just be aware that by not specifying some values you leave them at their current setting, not necessarily default. So for example if there is currently a small draft effect and they kept the zone short by using high Exponent values, you might still have a short effect zone even when you make it stronger.

So it may be prudent to specify the default values for all the lines above (per the blog post I'd suggest) at least for testing. You can always try removing later if you want to restore what's there now.
 
I tried on DevMode with the SkipBarber, and this one works :
Code: 
    UpgradeLevel="VehicleWidth 3.00"
    {
        HDV=
        HDV=[BODYAERO]
        HDV=DraftBalanceMult=1.00           // Effect of draft on aerodynamic downforce balance of car (bigger numbers exaggerate the effect)
        HDV=BodyDraftLiftMult=1.00          // Effect of draft on body's lift response
        HDV=RadiatorDraftFract=1.00         // effect of draft on the radiator cooling, 0.0 (no effect) to 1.0 (full effect)
        HDV=BaseDropoff=1.00                // RFM Drafting override: Higher number -> more drafting effect (default=0.185)
        HDV=LeadingExponent=2.20            // RFM Drafting override: Higher number -> lower effect on leader (default=2.0)
        HDV=FollowingExponent=2.20          // RFM Drafting override: Higher number -> lower effect on followers (default=2.0)
        HDV=VehicleWidth=3.00               // RFM Drafting override: Helps determine base width of wake (default=1.9)
        HDV=SideEffect=0.90                 // RFM Drafting override: Negative effects of side-by-side drafting (default=0.35)
        HDV=SideLeadingExponent=2.0         // RFM Drafting override: Added to regular LeadingExponent to affect the side wake
        HDV=SideFollowingExponent=10.0      // RFM Drafting override: Added to regular FollowingExponent to affect the side wake    
        HDV=
    }

I deliberately exagerated VehicleWidth.

Here is how it shows on DevMode (CTRL+Z ) :


Now i will try that on the Porsche Cup ...
 
I just edited an upgrade of the Porsche Cup with that :
Code: 
UpgradeType="Slingshot Draft"
{
    UpgradeLevel="Width 3.00 + BaseDropoff"
    {
        HDV=
        HDV=[BODYAERO]
        HDV=BaseDropoffLeadFollow=(1.00,1.00)
        HDV=DraftBalanceMult=1.00
        HDV=BodyDraftLiftMult=1.00
        HDV=RadiatorDraftFract=1.00
        HDV=BaseDropoff=1.00
        HDV=LeadingExponent=2.20
        HDV=FollowingExponent=2.20
        HDV=VehicleWidth=3.00
        HDV=SideEffect=0.90
        HDV=SideLeadingExponent=2.0
        HDV=SideFollowingExponent=10.0
        HDV=
    }
}

Adding the line BaseDropoffLeadFollow is necessary to make it work. And it works !
I will try removing the simple BaseDropoff and see if it still works. It seems useless.

This makes a very funny "slingshot" effect.
See on the video, at the exit of the bus stop after the tertre rouge and the straight.
I rejoin a 100 % full gaz IA which was impossible on "stock" Porsche Cup.


You can also notice the "Radiator" effect, making the engine suffering when getting too close of car exhaust.
Very interesting effect.

It is totally unrealistic, it needs to be balanced better, but it definitely works.

Thanks.
 
Last edited:
Here are my final parameters for the Porsche Cup, which make it quite realistic at least on LeMans.

Code: 
UpgradeType="Draft"
{
    UpgradeLevel="Added draft"
    {
        HDV=
        HDV=[BODYAERO]
        HDV=BaseDropoffLeadFollow=(0.40,0.40)
        HDV=DraftBalanceMult=1.00
        HDV=BodyDraftLiftMult=1.00
        HDV=RadiatorDraftFract=0.00
        HDV=LeadingExponent=2.0
        HDV=FollowingExponent=1.5
        HDV=VehicleWidth=1.920
        HDV=SideEffect=0.90
        HDV=SideLeadingExponent=2.0
        HDV=SideFollowingExponent=5.0
    }
}

From what i've learn with my tests :

- BaseDropoffLeadFollow values are associated to speed gained (Cx value lowered from draft i guess ...).
- FollowingExponent values are associated to the distance of the draft "effect" (The higher the lower).
- SideEffect is same as BaseDropoff values but in reverse.

BaseDropoffLeadFollow 0.40 gains at least 3 or 4 km/h "faster" gained (the slingshot effect is here).
FollowingExponent=1.5 offers gains at less than 0.7 s gap in Le Mans straights.

The SideEffect should not be neglected or follower will pass leader too easilly.
With a good SideEffect value, passing car will almost get at the same speed of the leading car.
It will generate some balance when cars are side by side.
The two cars will get to their max speeds at same pace, the "passer" will slightly be slower.
The gain is there but don't "slingshot" too early ...

These parameters are very fun to play with.

I will do some refinement on Sebring, a track i know well and see if the behaviour is good too.

I tested it with only a specific .mas (Upgrade embeded), and IAs must use the same vehicle.
Other IAs won't have the effect. If only "your" driven car has this upgrade it won't work.
 
Last edited:
If you just want to adjust the slipstream strength I'd advise to only change BaseDropoffLeadFollow with a multiplier function. All the other parameters affect the outwash and whatnot, which is most likely already in a good spot. However, if you still want to adjust the other parameters, I highly recommend using a multiplier function for them as well so you don't mess up the original values too much.

Example of what I would've done:

Code: 
UpgradeType="Draft"
{
   UpgradeLevel="Effect +10%"
   {
       HDV=
       HDV=[BODYAERO]
       HDV=BaseDropoffLeadFollow*=(1.1,1.1)
   }
}
 
Nice idea @Robin Pansar, very clever.

On a car with not enough drag but with some it would surely work better.
But i think 1.1 won't work on Exponents which are surely not "linear" and i will still have guess work.

I use DevMode to see the visualization of drag to "at least" make it plausible. Very useful.

And it looks like the Porsche Cup has zero drag at all. 1.1 x 0 = still 0.

I forgot we can use the += or *= like when we set Mass penalties.
There is still some possibilities with that. I will keep that in mind.

I don't know the actual "native" values of the car. And probably nobody knows right now :D

I updated my mod on the Workshop and i will see if there is no "unexpected" behaviours.

I acted with my own feelings and tried many situations, everything seems fine
and it adds some challenge to this "boring" car in race whith no draft at all.
It adds a little fun factor and even more challenge to it.

Only thing i noticed is a slight "oversteer" when driver passes right in front of a car,
surely due to "Lead" Dropoff, which is "as intended" actually but maybe too high.

And IAs have a weird behaviour, sometimes they brake for no apparent reason.
They might be affected by the new parameters in some way and react weirdly.
The slingshot effect makes them "give up" or some thing like that. They loose their agressivity.

And i totally removed the "RadiatorEffect" which is also quite fun to see working.
It can remove the capacity to push cars, i think. Nice possibility too.

;)
 
@DanRZ Nice to hear that you are discovering extra fun in rF2. It really is like discovering some hidden minigames and achievements when working on rF2 physics, studying and learning them. The devmode with all the tools is especially like a game by itself. Try to play with engine life stuff, it is fun to see realtime readout how engine life gets affected. It is interesting to be tsting how certain parameters are working by applying extreme values, usually it is very exciting, but there are times where it seems like things aren't working.

I wonder what is the situation about Porsche Cup drag. I wonder if there is any possible test to clear it, other than what you are doing right now. I wonder if it could be the case if all of the drag of it would be assigned to [wings] and drafting only affecting [body] section. There just can't be no drag, because it is such a basic parameter and yet fundamental, and without it car would be just weird.

I think some of the cars in rF2 are extremely well developed where data comes at, and then they often fall a little short where some of artistic interpretations kick in, even though it is still logical, related to data and is of course very technical. Especially for old cars it could be something about how tires work, and how aerodynamics work. I think ISI cobra is most fantastic car ever with a lot more aerodynamic lift added, which is now probably with better lift aero than Daytona, some rethink of tire to make it grip in right way and detune to 289... just that. A lot of mods I find falls short with aerodynamic lift, and some of the data available for cars does show how huge aerodynamic lift can be even on a small car without any measures to steer air flow upwards at front and rear. Aerodynamic lift/downforce is like second tires. Some of the older cars with aero elements still develops lift, it is not like with little spoiler 250GTO or Daytona Cobra is suddenly getting negative lift, they just get less of it.

IMO the real life races, footage of it is pretty good data for drafting effects. Besides that there surely should be data of speed and acceleration increases during slipstreaming episodes. There is almost no way to get it wrong for modern racecars, other than ignoring it or forgetting about it.

To me it makes sense if creators of Porsche Cup just didn't have data for draft properties, and went for something super conservative, or maybe it was causing some kind of issues which they avoided on purpose, by reducing draft effect. It is nice that it is possible to give these cars upgrades to have slight alterations, with respect to original build.

I think reasonably working radiator effect is crucial for proper simulation of races where lots of drafting will take place. I have raced in very fun HSO league race, where we pretty much slip streamed for several hours in four notFerraris. It was all fun at first, but there was almost no way to escape. If somehow one of us would get a bit away, others would bump draft and catch soon, and it could have taken forever, because oil temps were setup EXTREMELY safe, it would have never overheated, radiator draft effect also was not that much.

I have worked on cars for league that focuses on endurance races. And believe me, even though endurance races are the subject. What people really want is long lasting sprint races. They don't want cars to overheat, they don't want engines to go boom, they don't want brakes to go "no". It makes sense if devs conform to this, and as a result they do physics that aren't very slipstreamable, because without overheating it would end up as absurd and people would just laugh at it, on the other hand if it was rougher and more severe simualtion, people would get saaaaaaad DNFs :(
 
DanRZ said:
Only thing i noticed is a slight "oversteer" when driver passes right in front of a car,
surely due to "Lead" Dropoff, which is "as intended" actually but maybe too high.
Click to expand...

That's what the blog mentioned, and is the reason there's now a LeadFollow parameter replacing the old BaseDropoff. The blog showed a car that previously had a high leading exponent to avoid this issue. Now you can just (/also) lower the lead base value.
 
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