After driving those GP79 cars being converted by Arnao, I'm wondering if rF2 does or will have ground effect downforce? If it does, how complete is the current iteration?
Several of us did a tunnel test to see how well ground effects and downforce worked in rF2 and we were for the most part unable to go beyond 90 degrees on the tunnel walls at full speed with the Formula Renault 3.5. This would indicate that it is likely that at the time it was not fully implemented. Have not tested since then though so can't say for sure now.
how did you do a tunnel test? This I'm curious about! I've been messing with the GP79 mod and trying to tweak the ground effect. I'm going by the GP79 manual for rF1, which explains how to maximize ground effect df. It says that the rake angle is key and using springs, packers (they prevent the wings from compressing the springs and stalling the diffuser and keep the front wing from getting too low and preventing air from getting under the car for the venturi effect) and ride height adjustments to create and maintain a good flow of air below the car to suck it to the track. There is some sort of ground effect going on. I have to lower the wings and make all the other adjustments (from the default setup which in the manual says is high, soft and uses lots of wing to make more driveable) and when I get it right the car does get more grippy. It's a balancing act between wing and suspension settings. But when I hop the wrong curb too much I lose all df and go for a ride. Since ISI plans to make a car from every decade of F1, I have to assume that ground effects will be very advanced at some point.
Did some testing few days ago with a F2 at Mills (Outer loop C). First with a rideheight of 22 front and 45 rear. Then canged rideheight to 45 front / 45 rear, in result laptimes increases about a second. My conclusion: there must be some proper groud effect calculations in Rf2, otherwise laptime would not increase a sec. with wrong (45 front / 45 rear) rake angle.
Cars can flip over when to much air goes under the front of the car. In this case a "wedge" of air lift the front very quickly and flip it over. There are several examples of this effect in reality (Mark Webber in Le Mans, Ricardo Patrese).
We never did hear from ISI about this subject. In the GP79 mod this is especially important to know how much ground effect is implemented. With a properly set up car I do experience extra df that I can only explain as it has to be ground effect- when the set up is right, I can come out of corner, get on the throttle very early and the more I put the hammer down, the more the car sticks- with very shallow wing angles (GP79 mod). In one of the updates recently ISI has something about the diffuser in the changelog and I noticed that a lot of cars' df balance esp. in the rear changed quite a bit.
AFAIK, the only change to the diffuser during rF2's lifetime was the downforce loss calculated when running within the slip-stream of another car. rF1 also had diffusers working, you couldn't possibly simulate an F1 car without some forum of diffuser, but the variables have been expanded a little to allow a little bit more accuracy. An example of the diffuser entry in the HDV below. [DIFFUSER] DiffuserBasePlus=(-0.16, 0.01, 0.8, 1.9) // Base lift, and Half,1st,2nd order with rear ride height DiffuserFrontHeight=(0.0, 0.2, 0.0, 0.1) // Half,1st,2nd order with front ride height, and max height DiffuserRake=( -0.000,-0.50, 2.0) // Optimum rake (rear - front ride height), 1st order with current difference from opt, 2nd order DiffuserLimits=(0.02, 0.11, 0.07) // Min ride height before stalling begins (0.0=disabled), max rear ride height for computations, max rake difference for computations DiffuserStall=(0.10, 0.50) // Function to compute stall ride height (0.0=minimum, 1.0=average), downforce lost when bottoming out (0.0=none, 1.0=complete stall) DiffuserDraftLiftMult=1.08 // Effect of draft on diffuser's lift response DiffuserSideways=(0.355) // Dropoff with yaw (0.0 = none, 1.0 = max) DiffuserPeakYaw=(1.00, 1.001) // Angle of peak, multiplier at peak DiffuserCenter=(0.0, 0.00,-1.15) // Center of diffuser forces (offset from center of rear axle at ref plane) DiffuserOffsetZ=(0.000,-0.000) // Rearward diffuser pressure movement with increase in ride height, and rake Edit: I had forgotten that there was also one change to improve the accuracy of the under-tray points in relation to the ground surface which had an effect on non-flat surfaces.
All credit should go to Chapman and Lotus' engineers of the day for reviving full ground-effects by figuring out how to use the Venturi-effect with skirts to generate downforce but father he is not. Jim Hall's Chaparral 2J really has to be given credit for being the first demonstrably effective full ground-effects racing car. Still ground-effects was being used successfully in racing cars for years prior to the Lotus' 78 most noticeably for front-end downforce. But even Chaparral didn't go back to full body ground-effects after the 2J until after Lotus' success.
