Ok. I finally took some time to answer your question. btw: slatted, slotted = same thing.
Before I get into the slotted wing thing - we need to explain a few basics.
RC CAR WING
: is it really? We call them wings because it sounds right and because they kinda look like the aero devices used on real racecars, however real racecars actually do use wings with an actual "wing profile". In order to be a genuine wing it needs to have a cross section profile that differs between the top surface and the bottom wing surface. http://library.thinkquest.org/2819/g...s/bernoull.jpg
Back in the 1700's a Swiss brainiac discovered a theory that applies perfectly to the understanding of how a "real" wing works. Bernoulli's Principle formulated by Daniel Bernoulli states that as the speed of a moving fluid (liquid, air or gas) increases, the pressure within the fluid decreases. Because of these pressure changes (at speed) "lift" is created on the top side of an airplane wing - and when inverted - downforce is created by a racecar wing.
Unfortunately, RC car guys have never perfected a practical and effective "wing" for rc cars. The wing would need to be very
light, and very durable and very simple. This has always been the problem. Years ago a few oval racers used real wings - but they almost worked too well - and killed the efficiency of the battery run-time. The other problem is that clean airflow needs to flow across the bottom side of the wing for it to create downforce. There's simply too much turbulence close to the bodies of our rc cars for this to happen - especially given the fact that the wing needs to be down close to the trunk area of the body.
So - with that established, I hope we can agree with the fact that we are really dealing with air deflectors at best - not true wings. In fact, it's my belief that if the body is mounted correctly - nice and low, with small wheel openings - that the whole body becomes a sort of ground-effects device. The rear wing/deflector is simply changing the invisible airflow profile over the whole car. It definitely adds unwanted drag - but that's a necessary evil - especially when racing on asphalt.
So - what's all this have to do with slots in the wing?
Well - in theory
it simply adds a small amount of efficiency to just one component in an aero package that's for the most part very inefficient
. Even when running the full "kick-up" height on the back edge of the wing there's a very small surface area that recieves pressure from the air flowing over the body. Air - just like liquid doesn't want to conform to sharp changes in direction. The lower portion of the wing "bucket" simply fills up with turbulent static "boundary layer" air - forcing the "laminar flow" over the top of the wing/deflector. By cutting those slots in the right area of the lexan, the turbulent, boundary layer of air can escape, thus allowing the laminar flow air layer to come into the wing/deflector in a lower location - and actually make contact with the "kick-up" portion of the wing. ( the P905B on-road body I re-released today has air reliefs below the kick-up too. http://www.pro-lineracing.com/p-587-p905b.aspx
This is a way of mimicking what's done on the most sophisticated race cars in the world. Formula 1 cars. The current F1 rules only allow a 2 element rear wing - however years ago they would run as many as 5 elements - with small slots between them. The most rearward wing elements were almost verticle - so it would be impossible to say they were functioning as a "real" wing (as per Bernoulli's Principle) but were also relying on an air-deflecting type theory. These 5 element wings would not have worked at all without the "air relief" slots - nor would the current (2008) 2 element F1 wings work as well.
*NOTE: None of this is to be considered earth-shaking information for the RC racer. It might be worth a tenth of a second here or there. I'm just a bit of a nut for wanting to take the performance of RC racebodies to the next level. With the kind of amazing motors and batteries available now - the bodies have just got to work well
. I'm also probably guilty of getting a bit (anal) carried away.
That's just me.
Hope that answers your questions though. Sorry to get so "wordie" - I didn't know how to explain it any other way.
Dale Epp - Protoform