Aerodynamic LIFT, anyone?

[Rotary Junkie]

While fooling with my 787B at the test track (current best = 313mph), I set it for minimum downforce, dropped it, etc. I softened the front springs slightly, and set the rear spring rate at the minimum, along with the rear bound at 3. The car promptly picked up 10mph off the spray, and ran 291 mph. I regeared it and continued to toy with it. Now, I can hit 280 while cornering on the spray (I hit it slightly before the back stretch), and right at 260-280, the nose gets floaty. It doesn't take the tires off the ground, it gets floaty.

Then, while doing the handling setup, I tried running soft rear springs/shocks with the rear ride height higher than the front by 10mm. Since the rear squatted more than the 10mm, the tail wound up lower than the schnoze. Which in turn took angle away from the wing. Reducing the drag created by the wing.

Guess what? Without changing the ratios, straight line performance was improved, without harming cornering under coast. (Let off and the tail comes back up)

Now if an FGT can be raised enough to do this, it will benefit the most. Unfortunately, I sold mine.

 

[Mt. Lynx]

Well, if you are just tuning for 300+mph, doing the opposite is even faster, IE drop the rear and raise the front.
There is some kind of aerodynamic glitch in GT4, wich seriously effects the cars speed.
If you want to know what I´m saying, try one (or all!) of the 300mph settings I link in my signature.
These are really old, and has been improved on since, but I keep the link for people who wants to get an idea of what 300mph tuning is all about.

 

[Tornado]

I personally don't think GT4 has that good of an aerodynamics engine (for reasons stated by Team666) for what you are talking about to be the result of aerodynamic work so much as it is the result of suspension work.

 

[Rotary Junkie]

Right, aerodynamics experienced normally at 150 are at 200. Lift is nonexistant, except, it seems, in this case.

IRL, a higher rear is a little more aerodynamic as it creates a low pressure area at the rear of the car, and that pulls the air out from under the car.

It seems that the low rear is helping me by effectively reducing the wing angle, which seems to be (aside from speed) the only thing which affects aerodynamics. It would also make some sense of the wheelie glitch, as if GT4's aero model in this area is how I think it is, the less downforce produced, the less drag, bar none. Since the wheelie glitch causes removal of all downforce on the car, (lift, actually) the game drops the drag bigtime, as it actually registers as negative downforce. Why the rear tires stay glued, I have no idea, but the rest makes a modicum of sense, at least with the aerodynamic physics.

EDIT: The angling seems to make no difference after a certain point.

 

[Tornado]

Why the rear tires stay glued, I have no idea, but the rest makes a modicum of sense, at least with the aerodynamic physics.

Because only the front of the car registers as negative downforce, as you say. The rear end stays planted because the downforce is still normal in the back. I'm guessing it is a hex problem, like at speed the two downforces are measured in relation to each other, and when the rear gets a certain number over the front (probably 255 of whatever values) the front resets itself as 0 with the rear still at max.

 

[Rotary Junkie]

Ahh, that'd make sense!

And of course, the aero lift would go away at a certain point. (leverage created by the rear downforce and lift doesn't exceed the nose weight at this point with minimum front and rear downforce. Therefore, the nose stays on the ground, but still loses grip.)