# V8FU: Questions, thoughts and ideas

Discussion in 'Team ORSM' started by Günthar Rowe, Sep 21, 2011.

1. ### Günthar Rowe

Messages:
3,796
Ratings:
+30
Simply a point of discussion and shared learning.

I'm wondering why the front splitter:

FWDragParams=(-0.125, 0.00, 0.0)

has negative base drag? I could be argued that the front splitter reduces drag, and that if it is knocked off the drag will increase on the car, but I firstly have not seen a V8SC loose it's FW in the last few years and also believe that the drag on the FW is not removed in gMotor when the FW is remove by force (defined in the damage model) and only the Lift (Downforce) is lost.

I have always worked on the theory that the FW is a useful tool to applying forces (esp Drag) to the front of the chassis which isn't normally defined elsewhere in the chassis physics file.

Another point is the math of using the lowest rear ring setting gives a base drag from the FW, RW and body of: -0.125 + 0.054 + 0.120 = 0.004 = very low ...

Also, there are no 2nd order values applied to the Drag & Lift which isn't really possible IRL as this value models the disruptive turbulence value of the surfaces. Here in the formula that gMotor uses in rF (Drag of the front splitter in this e.g.):

Drag from Front Wing = FWDP_1 + (FWDP_2 x FWSetting) + (FWDP_3 x FWSetting^2) for travel straight ahead.

This (2nd order) is more important for an adjustable control surface such as the rear wing, as the disruptive factor increases as the AOI increases, albeit a small component, it is still an important inclusion I personally believe.

I'm interested in your feedback as I'm happy to learn if there has been testing that proves otherwise to what I have assessed and read in the last few years. Or that you have worked with a different methodology to produce the overall required effects as I have seen to some extent with the alternate use of the FENDER parameter further down in the chassis physics.

Cheers,

Günthar

2. ### krunch

Messages:
79
Ratings:
+58
Hi Günthar. Always happy to discuss things about the MOD and its workings. Let me first say that I am still learning about the various workings of rFactor - its just such a complex beast. I certainly don't know all there is to know and its always nice to find new information. My knowledge of vehicle aerodynamics is - well - pretty minimal. I know its a hardcore science so I've attempted to get ballpark numbers that, with a bit of trial and error seem to work on a basic level at least. Once I gain some understanding of the 2nd order values I'll attempt to implement them in our next mod. I appreciate your explanation of them as the "disruptive turbulence value". That gives me something to go on .

Regarding the front splitter my assumption was that when the front splitter (front wing) was knocked off all its effects were lost from the car, including drag. I had not heard the theory that possibly only the lift force was removed. I'd love to know for sure though so could you tell me how you came to believe that drag is not removed?

As for the base body drag - yes it is now mostly defined in the FENDER section so that it remains in the centre of the car (FenderDragParams=(0.406, 0.0, 0.0)). Doing that meant I could then use the [BODYAERO] section to locate the lift and drag parameters of the radiator and brake ducts at the front of the car rather than the middle. Its a bit of a workaround but its effective. There's also some drag for the front of the chassis in there. I am aware that all the other body aero forces are also affected by the BodyCenter location but I've tried to compensate for those as best I could. Hopefully rF2 will allow us to individually define the force locations of elements such as the radiator and brake ducts.

Cheers,
Neil.

3. ### Günthar Rowe

Messages:
3,796
Ratings:
+30
Hi Neil,

I totally do not confess to be a master of the physics model in gMotor (albeit that I have become a master of learning what doesn't bloody work, esp in Race07 ), but one of the things that I had to nut out when I worked on the free F1 2007 DLC for Race07 was the effects of the aero forces created by the FW, RW and Body. But, I'm starting to think that some testing is required on non-open wheel (tintops) cars, as the drag of a front wing on open wheelers does exist as a positive value and therefore once removed by impulse that drag (and of course Lift(downforce)) would have a value of zero, producing a small speed benefit at the cost of a large loss frontal downforce. Whereas on a tintop the front splitter is used to produce both reduced drag and in most cases in racing negative lift (downforce).

The way to test this is on a faster track with a modified damage model and FW setting. Set the FW to have 0 downforce so that the effects of it being attached or not does not effect the front grip and set the damage model to require 1N of impulse to remove the FW. The to remove it you simple need to brush a pit wall and it's off without any other effects on the car. then you can re-test the effects with it removed. This requires a driver that can produce multiple laps within 0.1xx of each other. Again, the test track doesn't need to be difficult, simply one that in normal circumstances wing settings and therefore drag makes big differences in lap times. Then a simple comparison on the lap times (or maybe terminal speeds at the fastest point on the track or MoTeC data feeds for a specific section of the test track) with and without the front splitter and it's drag effect can be determined. I guess that if the drag values was exaggerated on the splitter, this in theory would exaggerate the differences.

I would say that two sets of tests using:

FWDragParams=(-1.0, 0.0, 0.0) <<theory being that a large factor of drag would be added if splitter gets removed
&
FWDragParams=(1.0, 0.0, 0.0) <<theory being that a large factor of drag would be removed if splitter gets removed

both with:

FWLiftParams=(0.0, 0.0, 0.0)

I have, for sometime thought that the effects on tintops FW needs to be separated from the visual and the effects. As in a V8SC never looses the splitter but does get redesigned on track a lot and this has a big effect on the front aero, but I'm quite sure that is not modeled in gMotor until the splitter is completely removed. I'll have to check my notes again when I finish work about partial aero damage effects.

4. ### Günthar Rowe

Messages:
3,796
Ratings:
+30
Well, after doing a bit of testing on a runway, I have the conclusive results on the FW and it's effect on aerodynamics with respect to drag before and after removal by impulse.

Already known, was the fact of the loss of Lift (downforce) effect after sufficient impulse to remove the FW, but I can also now confirm that the associated drag effect, either positive or negative, created by the FW is also removed after sufficient impulse to remove the FW.

The result of the test tintop car running a FWDragParams=(1.0, 0.0, 0.0) gained a 50km/h increase in terminal speed at the end of the test runway when the FW was removed on track by impulse effect before test run was started. The inverse was also true when testing FWDragParams=(-1.0, 0.0, 0.0), the test car lost 50km/h when the FW was removed on track by impulse effect before test run was started.

On a side note, I also discovered that the game (Race 07 in this test) will lock-up/CTD when the car is being loaded on track if the total default drag is less than 0.000

5. ### Günthar Rowe

Messages:
3,796
Ratings:
+30
My feelings on this now is that on a tintop like the V8SC, is that the FW must have a base FWDragParams of less than 0 so as to have the expected increased aerodynamic drag effect applied when it is removed. But, the 1st and 2nd order effects must still remain positive integers. With the 1st order, simple because to reduce the Lift requires more effective AOI, which therefore creates more drag by default. With the 2nd order, no effect is completely free of charge and therefore the disruptive turbulence value is also applied as positive drag integer too.

Messages:
623
Ratings:
+241
I don't know about setting things up in rFactor on the physics side but when you say if the splitter is removed the drag is "increased" I'd say it's decreased. If the downforce is removed then so is the drag. Downforce creates drag. To set a rear wing and splitter to give the car downforce it's actually working on the air flow to push the car down to the road. The splitter also has the under body defuser which directs the air flow under the car which in turn creates a vacuum of air under the car again creating downforce. Remove the front downforce the air can flow freely under the car thus creating some amount of lift = less drag. The reason the lap times full away isn't because the car has more drag. It's because the cars downforce is reduced and grip is reduced. The V8's can corner at quite high speed. Reduce or remove downforce and the cornering ability of the cars is also greatly reduced even though they could possibly get 5 to 10km faster in a straight line but cornering speed and stability is greatly reduced.

7. ### FlashQld

Messages:
140
Ratings:
+30
In a non open wheeler vehicle it is acceptable to have negative front wing drag at the base setting, as long as this is factored in the BodyDragBase=variable. Doing this will mean as you damage and lose your front bumper(which doesn't happen these days as GR said) you actually lose top speed because it was producing negative drag. If you lose your front spoiler, air flow becomes rough and flows over the newly exposed wheels, creating extra drag.

Messages:
623
Ratings:
+241
9. ### Günthar Rowe

Messages:
3,796
Ratings:
+30
Or by mis-use of the fenders as was done here with this mod. I say mis-used as in only the naming the function doesn't match the applied use, It's more a recycling of a normally unused function in this type of car.

We have to look here at the limit of the damage model (Limited to 12 debris objects + the wheels and a few other components), and what is currently being created to fit this damage model. Every car I have looked closely at combines the tintop front splitter (lower, generally flat looking extension) and the front bumper into one 3D object or multiple 3D objects, but grouped under the same Instance=DebrisX which means they share and are effected as one via the damage physics file. Look below to see what I mean by the two parts:

Full FW Assembly

FW Bumper Assembly

FW Splitter Extension

Since these tend to be grouped, there is a need to model the effects of the aerodynamic advantage of the main bumper assembly as it redirects air over the bonnet and around the side fenders (we don't have to worry about the brake ducts as these are separated in the chassis physics .hdv/.hdc file in the brake section) and also model the drag and negative lift of the splitter both when attached and also the loss of these effects (streamlining, lift and drag) when removed by impulse.

10. ### FlashQld

Messages:
140
Ratings:
+30
But as you said - this part on these cars doesn't fall off these days unless the car is totally wrecked therefore are we trying to achieve realism in the formula for the sake of something that isn't real. I guess I would have to ask now... what is your question or haven't you already answered it yourself? Surely the effect is probably modelled in the RACE07 series of cars better as these cars do lose the front splitter. I would then say - is the game that good a simulation that would really be noticeable whilst sitting in the office chair with a G27 steering wheel?

When you say "Or by mis-use of the fenders as was done here with this mod." What do you mean by the mis use of the fenders?

11. ### Günthar Rowe

Messages:
3,796
Ratings:
+30
Well, SimBin non open wheelers, in my opinion are actually done incorrectly and have positive drag for the front splitter and therefore, having it removed by impulse makes the car faster in a straight line, but at the loss of downforce.

My original question here, I seem to have answered for standard non-open wheelers. With respect to V8SC specifically, as you and I have stated, they seldom loose the front of the car at all. Whincup or Lowndes (I forget) show this perfectly at Hamilton a year back

The re-cycling of the Fender is here:

Code:
```[LEFTFENDER] //(not used in V8FU as the left fender but as a way to add the raw lift component to the body using a different point of force)
FenderFlareRange=(0.0, 0.0, 1)      // front fender flare
FenderFlareSetting=0
FenderCenter=(0.0, 0.45, 1.6)       // center of fender forces (offset from center of front axle in ref plane)
FenderDragParams=(0.406, 0.0, 0.0)  // base, 1st, and 2nd order drag per meter flare
FenderLiftParams=(0.020, 0.0, 0.0)  // base, 1st, and 2nd order lift per meter flare
FenderSideways=(0.1)                // dropoff in downforce with yaw (0.0 = none, 1.0 = max)
```

12. ### boss

Messages:
5
Ratings:
+0
To continue the conversation here as I'm interested.

The base drag on the front of a tin top is about 0.35 to 0.6 for the front of the car, pending make.
The splitter (being 50/80ml below the underbody of the car it should only add a very small amount if any to the drag on the front lets say 0.05, rFactor removes this when the splitter gets removed with the downforce.

The question we have to answer is, dose the front of the car with the splitter removed have more drag than the drag from the frontwing (not taking into account the front of the car as it's already in the cars base drag), I would say yes, and will it not only cancel out the drag on the front splitter, even increase it, I would say yes again, the front of the car isn't very aerodynamic with the splitter removed.

To sim this add the extra drag for the front wing/lower part of the splitter to the base drag and give the front wing a negative drag so when it's removed you go slower.

Cheers Gary

13. ### Günthar Rowe

Messages:
3,796
Ratings:
+30
Hiya Gary,

You have come to the same conclusion as I (for a sim). As some front splitters have adjustment on tintops have the extra "clicks" of downforce adjustment, this can be modelled into the FWDragParams 1st order variable as positive drag, and the base variable for the FWDragParams is negative drag.

To adjust any currently released vehicle is not so complicated, as the FWDragParams needs to have a new negative base value and the difference of the total drag of the vehicle needs to be added to either the FenderDragParams (once this section is added to the .HDC/.HDV) or to the BodyDragBase for the simplest fix.

14. ### boss

Messages:
5
Ratings:
+0
I have been thinking on this, another way to set this up, to keep the aero file as it should be, would be to increase the aerodrag for damage.

Cheers Gary

15. ### Dave Oliver

Messages:
212
Ratings:
+17
As the V8 teams now have a Fuel Mixture rotary dial on their steering wheels, is there a way you could build that into the mod using the boost settings. Like the enduracers mod did. So you can toggle the fuel mixture up and down.

16. ### Günthar Rowe

Messages:
3,796
Ratings:
+30
you mean with the following:

AeroDiv=

17. ### boss

Messages:
5
Ratings:
+0
AeroDiv
AeroMin

I thought there was a multiplier for aero drag/damage as well, but I can't find it.

Gary

18. ### sennannes

Messages:
86
Ratings:
+5
Hello! A little idea or suggestion here.

I have been checking out the V8 Supercars videos of the cars before 2008/2009 which upon downshifts spit flames out of their exhausts, whereas in the post 2008/2009, cars do not spit anymore of the red-orangey flames out of the exhausts.

After observation from the V8FU mod, I noticed that the 2010 & 2011 seasons do have this blue-purplish Bunsen burner yet not so visible fume from the cars' exhausts.

I am an enthusiast to such exhaust flames and as I believe it was due to the introduction of Ethanol fuel for the cars and thus has removed the previously had mean-looking exhaust flames to the current looking tamed exhaust fumes.

As from the V8Factor's 2006 mod, there was this 'proper' exhaust flames which makes me feel happier and therefore a suggestion will be as follows:

- Is it possible if in the Upgrades section of the Vehicle to include an option for Fuel Type as Normal Fuel or Ethanol Fuel to allow for the switch of either the pre-2008/2009 exhaust flames for the first and the post-2008/2009 exhaust fumes for the latter in-game?

It would be really cool if that is the case. Cheers!

19. ### still_bacon

Messages:
415
Ratings:
+159
Doesn't the BA/BF and earlier models run this colour backfire??

20. ### HRT427

Messages:
9
Ratings:
+0
Hi all

A somewhat newbe question; I decided to do a bathurst the other weekend (yes the full 161 laps in stints with the ai driver) as I'm not really fast enough to get online I enjoy pitting my self aganst the computer (I'm only doing 2:09's), so the question is how do you or is there a way to make all of the other cars display the bathurst livery just to add to the realism?

By the way boys awsome mod!