When you get a car, and the default settings from Turn10 have the front and rear ride height not the same, do you change it to make them the same?
Do you think that it would change the aerodynamics or handling that was built into the car/game?
For us nerds, should I apply some kind of weight transfer to account for the ride height difference? Center of gravity is off I would think, no?
bleh, I’m stupid in these things, cats not so smart.
I’ve studied this anomaly and its consequences. At the end, it only matters if T10 has coded aero/handling changes due to the height difference into the simulation. In RL, they do matter. In simulation, it only matters IF the effects are coded.
That said,
IF the height difference in the set-up has deliberately been put in there by T10 (and hopefully not a mistake or type), then the following are true:
Front to rear height difference is called a “Rake” and it can be used to shift the weight to the front/rear slightly.
Lower front is typically desired to put more weight on the front for better corner exit grip (when rear wants to squat and front wants to lift)
Lower rear would do the opposite. Lower rear may also help really front heavy cars.
In formula cars or cars with flat undertray will create a diffuser (downforce) if front is lower than rear at virtually no drag penalty = fantastic but I have not tested this. Again, it will only work IF this effect is coded into the physics engine. For passenger cars, there will be no downforce gain.
Centre of gravity is absolutely affected: CoG will shift forward for rear high rake & CoG will shift toward the rear for front high rake.
The higher side will tend to roll more in corner.
As for the set-up, you can make front/rear the same or keep the difference. The springs+ARB+Dampers WILL have to be adjusted, either way, for desired handling characteristics.
So, final answer = I do not think the rake would change the aero but it would affect the handling.
Thanks GRD. Of course all the test driving will bring any of these issues out and modifications will be made. I appreciate the background, that is what I was looking for.
As I have mentioned in previous post, this is true in REAL LIFE only.
In ANY SIMULATIONS, this will work ONLY if it is coded into the physics/aerodynamics engine. I am quite certain it is not coded into Forza for the following reasons:
In real life (and in some simulations), one does NOT specify the xxx lbs of downforce but x degree of wing angle.
The rake angle is added to the wing set-up angle for the total actual wing angle (with reference to the ground).
This actual wing angle can and WILL change at high speed as the car gets pressed down.
In Forza, THERE ARE NO WING ANGLES and we specify the downforce using “weight on the wing”
In Forza, the weight on the wing would have to be converted to a wing angle for the rake effect to be incorporated.
If wing angle is used in codes, why would set-up screen bother to ask for the downforce weight? It’s because if wing angle is used, more calculations are required = more processing power.
Therefore my assumption (because I have not tested this) is Forza does NOT simulate rake angle or its effects with regards to aerodynamics. As for the slight CoG shift, it would be difficult to evaluate . . .
GRD,
I agree whole heartily agree with your logic here.
Although it would not be that much more processor overhead to run Bernoulli’s equation with the power of today’s gaming systems.
One equation, yes. But wings are NOT simple shapes therefore Bernoulli’s equation (for simple shapes) will not be adequate, in which case might as well make a table of values and look-up (which I think FM5 is doing).
There are multiple considerations to the wings, splitters, vortex generators, guides, Gurney flaps, double/triple decked wings, air velocity, air temperature/density, angle of attack, drafting from behind, being drafted, etc. For accuracy, the whole is not sum of the components but the entire car has to be addressed as one aerodynamic system. This means the calculations are not simple plug in the variables but a huge matrix to be solved, minimum of 60x per second.
So a lot of estimation, assumptions, simplifications and rounding off has to be done just to bring some aerodynamic effects into the simulation. If the effects are to be derived from estimation/assumptions/simplifications, there is no point in trying to be calculate accurately.
For F1 team such as Red Bull, they can use accurate simulation parameters because they have 1 car design and they practically have months to work on perfecting 1 car. For a title such as Forza (many different cars with vastly different aero characteristics), setting up the matrix for each car would be quite a work. It would be far more efficient to actually measure the aero forces then extrapolate.
I am grateful that T10 has added aero forces, but I am a bit skeptical on how they work. For eg. how are most add on splitters all magically generate 50 lbs of downforce at minimum setting? And why do I feel extra grip at launch? I could be imagining it but as soon as I add wings, I immediately feel additional grip even at launch which should NOT be possible.
I apologize for being such a pain; I have gone through the same questions myself in the past.
I’m going to do some simple tests when I get back home tonight to see if there are any aero affects that can be observed (travel up and down the Mulsanne straight). I’m also going to play around with extreme rakes to see if there are any observable impacts (not sure how to test this one).
So I have subjectively tested 4 configurations using IndyCar at Indianapolis Oval:
High Front & High Rear: No changes to top speed but feels uneasy overall and understeers at all corner exits
High Front & Low Rear: No changes to top speed, understeers at all corner exits, not an enjoyable configuration
Low Front & High Rear: No changes to top speed, decent cornering but rear end feels a bit wobbly
Low Front & Low Rear: No changes to top speed, best handling of all
Top speed was 236~237mph for all configurations. Does Low Front+Rear have more downforce? Inclusive!
High ride height is 4.5" and low ride height is 2.5". That’s quite a drastic height difference. I am inclined to conclude lower CoG contributed more to the handling than the rake/ground effect.
Also checked the weight distribution % on the benchmark window with High Front + Low Rear & Low Front + High Rear configurations and there were NO changes to weight distributions.
Verdict: In FM5, I cannot feel the effects of aero forces as a result of front-rear height difference.
I don’t do drifting nor drag racing but ride height would be a significant consideration for drag racing I think.
My guess is one would want best rear end grip and no concern for cornering so a soft rear spring + higher rear height would be desirable? I’m just guessing because I’ve never tuned a car for drag racing . . .
I regret that I will not be testing any more cars for this study; got plenty of other testing + rivals + race practice to do . . .
indeed it does, at rest, the wheels with the most weight on them have the biggest circles, however once you start moving that changes things, any bumps in the road, any steering correction, or anything that would cause and form of suspension travel. the problem will be trying to nail down a hard observable circle size.[
GRD - thanks for taking the time to test this out and for the update!
Lately I just try to keep the ride height (both F & R) as low as possible [usually min] w/o running into bottoming out issues and the cars feel pretty good. Sometime I even bottom out and do not see any lap time reductions (which I would expect by reduced speed due to friction with tires). Not sure how T10 deals with this.
