hahah, yeah it was a joke.

I'm sure the evos with the big wings and actually do well rotate just fine.

 

Wouldn't a front splitter offset (or partially offset) the decreased force on the front tires caused by the rear wing? Theoretically?

Dave

 

yes.

You might actually get a genuine 70lbs of downforce out of the car, and could run an even bigger rear wing (or more stalled).

 

Sorry my thoughts were more focused on ST* based cars. In SM and higher cars where the size and the number of the wings tend to get towards unlimited I think it would make a greater difference. Double or triple decker wings with a lot of suface area and really high AOA would probably provide more downforce. Also a trick from the Subaru WRC cars could help increase airflow through the wing by sectioning it into portions.

I'm not sure I follow the logic of drag being applied as moment around the CG. I'm assuming, your assumption is based on the fact that drag is another force being applied to the some portion of the rear wing. And by mapping out a perpendicular line to the CG of the car you are saying a moment is being applied that pushes down the rear tires and thus additional amount of down force is being applied.

But isn't drag just created as an undesirable after effect of the wing and the entire rear structure of the car which is "pulling" the car backwards? I'm not sure it is a seperate force on it's own, but is associated with the wing that generates the downforce. What I'm trying to say is that in the real world the force vector is being applied diagonally if viewed from the side. The force vector if divided into a verticle and horizontal components at the wing would represent downforce and drag. In that case the force that is helping the rear squat is already being accounted for in the downforce vector. Drag would be what is left impeding the forward motion of the car ... The collective sum of the drag forces if taken at a single point may be acting on a location different than 3ft from the CG ...

Still the question is are all these fancy aerodynamic tricks helping much @ auto-x speeds? Is there a noticeable improvement in levels of grip? Thoughts?

 

the drag is the component of the force vector that is horizontal and perpendicular to the downforce. There are two main types of drag, shape drag and induced drag. What you describe as the component of the downforce vector that points backwards is the induced drag (ie, induced from the downforce although slightly more complex then just that). the shape drag (kind of self explanitory) in the autox sense is by far the larger of the two, particularly when the wing is stalled. It is very possible, and more likely the case, to generate more drag then downforce. Especially using single element wings at crazy high AOA's. As a side note, I personally find it rather funny when i see several hundred dollar carbon wings doing essentially the same work as a 2 dollar piece of plywood. That's a different disscussion though.

When the wing is mounted higher then the cg (vertically) the drag creates a moment on the car. It's not adding downforce, obviously the force isn't pointing down, but it does change the balance of the car. This effect by its self isn't going to increase or decrease the grip level. It's more akin to having movable balast in the car, and the faster you go the more the ballast moves forward. The effect is very substanial even at autox speeds, whether it makes the car faster depends on the tuning.

 

LOL! the same thought has run through my mind a few times ... but I am sure asthetics has a little to do with choice.

In that case if you take the system as a lever and the point of fulcrum being the CG then essentially these wings are essentially adding grip to the rear while sacrificing grip to the front of the car. Without the allowance in STU to add splitters, cannards or other significant aerodynamic tweaks to the front of the car. This would be a way to tune the balance of the car. Taking away grip from one side to add to the other ... instead of increasing grip both in the front and the rear. Not sure if this something we would want on a car that has a tendency to understeer.

 

14.2 Bodywork

"F. Addition of spoilers, splitters, body kits, rear wings and nonfunctional scoops/vents is allowed. The intent of this allowance is to accommodate commonly available appearance kits, and replicas thereof, which have no significant aerodynamic function at Solo speeds. Body kits are limited to bumper covers, valances, side skirts, and fender flares. Standard parts may not be removed except for the substitution of spoilers, rear wings, bumper covers and valances. Rear wings must attach only aft of the rear wheel centerline. Total surface area of all spoilers, splitters and rear wing may not exceed 5 square feet as seen from above (see 12.9). Substitution of rear spoilers or wings must retain any original third brake light functionality unless otherwise equipped. No underbody panels may be added or substituted. The drilling of holes for the purpose of mounting these pieces is permitted."

Dave