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Old 05-22-2013, 12:39 PM   #161
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Here you can see that the Lotus has essentially two inverted air foils. In this case, (a Miata shape may be a whole other ball game) the leading edge collects air which is compressed and accelerated then diffused by the trailing edge of the air foil.

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Old 05-22-2013, 10:17 PM   #162
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That effect requires an entirely flat bottom and a long diffuser, which most miatas don't have. The slope in front feeds air to the rest of the system.

I made the common mistake of referring to one aero element independent of the rest of the car. I was speaking in terms of just having a splitter, and the advantage/disadvantage of sloping it one way or the other relative to the ground. Given the aero setup most guys have (splitter only), I think the effects described above aren't attainable. With an entirely flat underside, perhaps it can be.

I do have a flat underside, but still it may be difficult to achieve this effect.
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Old 05-22-2013, 11:08 PM   #163
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Nascar splitters are horizontal, not angled upwards. They do not have a flat underbody nor a diffuser. Point to consider. If they saw an advantage to any angle they would run it.

However.

All references we make to aerodynamic features of cars in competition series (F1, Nascar, WCC, etc) are somewhat suspect given the tightly regulated nature of said competition series.
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Old 05-23-2013, 03:22 AM   #164
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Quote:
Nascar splitters are horizontal, not angled upwards. They do not have a flat underbody nor a diffuser. Point to consider. If they saw an advantage to any angle they would run it.
THis is absolutely true, howeer they dont have to avound kerbs, bumps, holes and other obstructions in a road driven car.

My perception of the function of the splitter is to "pile" air up on top of and limit airflow behind, thus creating a low pressure zone behind the airdam....resulting in down force.

I agree 100% it is not ideal but my question is, will it still work to some degree....my air dam has a slight turn up to enhance ground clearance from driveways and kerbs etc....over the 14" depth of the air dam it probably rises up 1" towrds the front......
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Old 05-23-2013, 03:35 AM   #165
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Well they do run 3 road courses per season if I recall correctly. We should examine pics from those races.
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Old 05-23-2013, 12:23 PM   #166
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How does that gap between the airdamn and splitter interact? Does it just become one big high pressure zone? Would a flat air damn at the immediate front of the car being more aerodynamically effective?
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Old 05-23-2013, 12:32 PM   #167
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The answer you're looking for is 2 pages back....
https://www.miataturbo.net/race-prep...d-70612/page7/
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Old 05-23-2013, 12:32 PM   #168
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Quote:
Originally Posted by Canyonfive View Post


How does that gap between the airdamn and splitter interact? Does it just become one big high pressure zone? Would a flat air damn at the immediate front of the car being more aerodynamically effective?
Plucas in this thread (or another) did an exhaustive study that showed different front air dam configurations. The most efficient model seems to have been grafted directly onto 949 Racing's "Crusher".
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Old 05-23-2013, 12:34 PM   #169
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Quote:
Originally Posted by Canyonfive View Post


How does that gap between the airdamn and splitter interact? Does it just become one big high pressure zone? Would a flat air damn at the immediate front of the car being more aerodynamically effective?
Depends on your splitter rules. If you look in this thread you can see the data on the different types. However the test doesnt really reflect how anyone would make a splitter in real life. The cfd showed your style air dam being less effective, HOWEVER the straight down crusher style air dam wth the splitter had an unfair advantage of having more splitter area. With equal splitter area your style should produce more downforce but more drag. And on any splitter rules where the area of the splitter is constrained by the dimensions of the bumper your style will make more downforce because it'll have more splitter area. Your style also has the added benefit of generating an equal lateral to each side which stabilizes a car much like the stabilizing effect of end plates, minor side benefits are nice.
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Old 05-23-2013, 01:02 PM   #170
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I like the cone-shaped ducting for the rear brakes
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Old 05-23-2013, 01:07 PM   #171
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Quote:
Originally Posted by ThePass View Post
That effect requires an entirely flat bottom and a long diffuser, which most miatas don't have. The slope in front feeds air to the rest of the system.

I made the common mistake of referring to one aero element independent of the rest of the car. I was speaking in terms of just having a splitter, and the advantage/disadvantage of sloping it one way or the other relative to the ground. Given the aero setup most guys have (splitter only), I think the effects described above aren't attainable. With an entirely flat underside, perhaps it can be.

I do have a flat underside, but still it may be difficult to achieve this effect.
Oh, yes. I agree. I was responding to the people who were talking about splitter angle on purpose built race cars and putting up pictures of the Mclarens. I missed Lightyear's post where he said exactly what I said, but before me.
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Old 05-23-2013, 01:41 PM   #172
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As I see it, Indy and F1 cars get their outrageous downforce from their side pods and wings front and rear, but alot from the side pods. An airplane wing creates lift from the top of the wing being shaped such as to create a low presure area by speeding the air up on the upper surface when it has to climb a rounded surface compared to flowing slower over the underside flat surface. So it stands to reason that if you turn that wing shape over you are going to create the opposite effect. We don't have anything like this working for us.
Nascar is more like us and they run their splitters right on the ground trying to keep the air from getting under the car. If you think about it, our cars are basically an airplane wing shape, flat bottom and rounded top. Everyone well agree that the front upper part of the car is a low pressure area until the windshield then it would get low pressure again at the top of the winshield where the air is speeded up again. Nascar runs their cars hard on the bump stops and adjuust the height when a driver complains the car won't turn with 1/16, 1/8, shims to keep the splitter from causing understeer because of hitting the track to hard.
The DP and LP cars run a wedged sloped nose with a flat bottom to create a lot of downforce up front.
I found that running the undertray on my car with a stock front made it push, when I removed it the push disappeared. I run Emillios air dam up front now. My thought is that the undertray has a downward slope front to back, thus creating a lift bias along with the air flows faster under the tray then hits the underside tunnel and rear suspension and bunches up creating a lift on the car along with all the low pressure areas on top of the car equals lift. I think on our cars we need to do like nascar and keep as much out from under the car as we can. A low splitter with a flat orientation well help keep air from under the car but it traps air on top against the body creating down force as Nascars do. I would think any upward bias to the splitter well marginally decrease that effect as the air getting underneath well want to raise the front as we don't have a flat underside with the proper shape behind that frontal area. If I had a splitter I would have it flat in relationship to the ground. Just my 2c worth.

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Old 05-23-2013, 03:51 PM   #173
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Mashing cones cant be that good for aerodynamics.
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Old 05-23-2013, 04:35 PM   #174
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Quote:
Originally Posted by jmann View Post
I would think any upward bias to the splitter well marginally decrease that effect as the air getting underneath well want to raise the front as we don't have a flat underside with the proper shape behind that frontal area. If I had a splitter I would have it flat in relationship to the ground. Just my 2c worth.
Agreed. I'm not sure how adding angle of attack to the front splitter could possibly help. You want the lowest pressure possible underneath the car, letting more air in will do the opposite of this. I thought the whole point of a splitter was to keep most of the air from going under the car?

Having a diffuser after the upward-pointed splitter will help, but not as much as having a diffuser after the horizontal splitter.
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Old 05-23-2013, 04:46 PM   #175
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Quote:
Originally Posted by triple88a View Post
Mashing cones cant be that good for aerodynamics.
That was the result of a spin, not quite enough lateral grip to go through there WOT, but no, hitting cones isn't good for aero. Nor good for the aero components.
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Old 05-23-2013, 05:04 PM   #176
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Quote:
Originally Posted by jmann View Post
As I see it, Indy and F1 cars get their outrageous downforce from their side pods and wings front and rear, but alot from the side pods.
ScarbsF1 did a series of articles awhile ago, I think for a Greek web site or something, his analysis was essentially:

25% Front wing
25% Rear wing
50% Floor/diffuser

As to where the down force is generated.
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Old 05-23-2013, 05:37 PM   #177
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And by floor I assume they meant the side pods as their isn't any real purpose that I can see to the body floor except to have a smooth surface for the air to flow on so as not to create turbulance.
When I said I run Emillios air dam, I didn't mean like in crusher, I meant the one he sells at 949 for the 99, it seems to balance the wing very well. I also added vents in the top of the fenders to evacuate air from the fenders and side skirts/splitters to keep the air from rolling down the sides and under the car. Now it is trapped on the sides like a splitter does up front and helps with stability in corners plus adds somemore down force along the sides of the car as I have spats at the back end covering the rear tires and also trapping the airback there behind the doors.
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Old 05-23-2013, 06:31 PM   #178
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jmannm sidepods ate not allowed to be wing shaped like the lotus pictured above anymore (and haven't for many years) they get the body downforce from the coke bottle waist of the car feeding the undertray / diffuser and other clever ways.
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Old 05-23-2013, 06:42 PM   #179
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John and I are just goofing around at lapping days having fun terrorizing Porsches and Corvettes so when this discussion involves classing rules then things change. We're trying to make the cars as fast as possible without concern for specific rules.
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Old 05-23-2013, 08:24 PM   #180
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So much misinformation on this last page I don't even know where to start
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