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Smike

CMC Wing Development - Am I Nuts? (likely)

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Smike

Lets just start off with the rules:

 

7.5.5 Any rear spoiler/wing that fits the following criteria may be used:

1. A vertical line from every point on the spoiler/wing and end plates must intersect the car body/bumper cover when the car is on a level surface.

2. The maximum height of any point on the spoiler/wing from any point on the deck lid/rear hatch may not be greater than 12 inches.

3. The overall depth (leading edge to trailing edge) including end plates may not be more than 12 inches.

4. The spoiler/wing and mounts as installed must be readily available to the public from a retail source for less than $700.

5. The wing must be fixed for competition and may not be adjusted from the driver’s seat

 

In the ~45 mins of seat time I got with my new-to-me CMC car; the back end is very loose on faster sweepers. I ran with car without any rear wing (OEM or otherwise). Saw most went with a NASCAR style trunk flap with some adjustment for rake. I mocked up that as well; however, it severely limited how much I could see out of my rear mirrors. CMC is much like TT - you race with your mirrors. So NASCAR for me is out.

 

In the spirit of CMC...I have the OE wing from the car, bunch of metal stock, and time.

 

Contours of the OE spoiler follow the body and it is a semi-symmetrical airfoil. Should create a low pressure under it and high pressure above (negative lift / downforce).

 

Mock-up last night (nothing bolted correctly - just to see it):

IMG_20120820_182105.jpg

 

IMG_20120820_182059.jpg

 

IMG_20120820_182115.jpg

 

Rear bracket has 2 bolt holes to add more height to the rear of the wing (increase rake). Right now its level. Wanted to over engineer the brackets. Not a fan of having it rip off at speed. I am sure you guys wouldn't appreciate that either.

 

I will be using some AL sheets to wrap the brackets and funnel more air under the wing.

 

Pass rules?

1 - Yes. Follows body and does not extend past sides or rear.

2 - Pass. 11in measured at rear top center.

3 - Pass. Not that deep.

4 - Pass. $40 bucks mostly in bolts.

5 - Pass. Fixed.

 

Do I get the crazy award? Or is my logic semi-sound?

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Steve91T

You could have used plexi glass for the NASCAR style spoiler like I'll be using.

 

I'm very interested to see if this is legal. I was under the impression that it wouldn't be, but maybe it is.

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Smike

I did that with a section of Plexi I have. Distorted my rear mirror vision too much for me. Basically, AI, AIX, and SU cars would look like nothing more than colored blobs approaching at high rates of speed.

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cozog1548534733

I like your thinking, but IMHO, you'll get about 20lbs of downforce @ 100mph, while creating enough drag to lose 3-4mph down the straights. Bad trade off if you ask me.

 

If you want to put a wing on it, get a real wing. Those OEM spoilers are only good for slowing the car down.

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Smike

Thanks Todd.

 

I need to think about the maths and how much it might add. Both to drag and downforce.

 

Ha, true. Those real wings cost a bunch too.

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Glenn

Legal - yes.

Good idea - no. W/out some type of structure under the rear deck, that thig is gonna rip off. As said above, lots of drag for little downforce.

 

Low speed balance and high speed balance is a trade off. Consider air pressure changes to fix it. Combined w/ spring rate changes, sway bar changes and even wheel spacers, you could find a happy balance w/out adding drag.

 

Not sure why your spending so much time looking behing you. All I do is see there is something there. A 2nd look tells me how fast it is. Beyond that, they have to pass me safely, not the other way around.

 

Use some plaexiglass. Build a spoiler.

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cozog1548534733

Mike,

Also consider the tracks you're going to run on. Do they have a lot of high speed sweepers where the spoiler will be a good benefit? Or do they have long straights and relatively tight turns. You're not going to see much benefit below 50-60mph. I put Mid-O in the long straight/tight turn category. Most turns are "slow" and the aero isn't a big factor for us. T1 is the exception. But Keyhole and China Beach are at the end long straights, where passing is likely to happen.

 

Just food for thought...

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Smike

Was planning on a structure under the deck as well.

 

From what I've been able to find of Mustang wind tunnel data. Looks like anything under 10in will not be in the air stream over the roof line.

 

I may be swapping over to the H&R Super Race spring in the front (875 lb/in v. 800lb/in I have in the car now). I need to sit down with some scales and measure the motion ratio and think over the cars suspension. Saving that for winter time.

 

Haha, might be a regional difference. AI and SUs come in packs. Mirror is always your best friend in my book. And if I am racing in PTB, the SE30s and Miatas are never predictable. In front, next to, or behind you. I know its the passing cars responsibility to pass safety...often not what I see in the PT race.

 

Cobra R (which is functional) and Steeda race wing I see on most AI cars is functional as well. Not much off this variation.

 

I have time to create both. Instructing a PCA event and test/tuning at Mid Ohio a little more. I can do both back to back and see what feels better without as much lose in the straight.

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suck fumes1548534743

The 2000 cobra R wing is legal in Cmc right?

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Smike

T1, 9-11 Complex and T13.

 

I guess the dilemma is fast in straights or faster in turns.

 

Fast tracks would need different setups. Wing various might come into play as well. RA is fast. Might run with no wing for that type of track. Its all about the straights there. M/O is mixed for me. Grattan is a more fast than turning track.

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Smike

Cobra R should be based on the 1-5 rules. They are about $170 unpainted.

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CMC#11
Cobra R should be based on the 1-5 rules. They are about $170 unpainted.

I'd recommend adjusting the car so you don't have to run a wing. There are plenty of changes to spring rates, track width, and tire pressures you could do to fix an oversteer issue and chances are it would help you in other parts of the track as well.

I've just never heard of a Mustang with "too much front grip".

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Adam Ginsberg

I've found this style of spoiler to be very effective:

 

bw_13.jpg

 

bw_14.jpg

 

bw_15.jpg

 

Doesn't reduce visibility, is adjustable, and CMC legal. It helped eliminate a high-speed front push I'd had in the car for several years using this previous type of spoiler:

 

old_bw01.jpg

 

old_bw02.jpg

 

old_bw03.jpg

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DrC

Mike I was thinking the same thing since the current set up has no benefit.

I was thinking of moving it back and increase the angle up in the back.

 

Still thinking about how to reattach it back to the car.

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DrC

Adam so are you saying that you had problem with the nice looking wing and better luck with the one you made with parts from the local hardware store?

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Adam Ginsberg
Adam so are you saying that you had problem with the nice looking wing and better luck with the one you made with parts from the local hardware store?

 

The picture showing the factory spoiler with the formed, AL unit attached provided a high speed push that took me forever to figure out (there are times I'm not the brightest bulb in the pack). That unit provided too much rear downforce. Since we are very limited to what can be done to the front (no splitters), a change had to be made.

 

After some discussions, I decided to try out the adjustable spoiler. I didn't build that unit - I bought it from Alan Blaine. He's made them for the 3rd and 4th Gen crowd for several years, but only recently began making them for Foxes (although it's not listed on his website for some reason). The hardware is a combination of hand made AL (brackets) and stainless steel (turnbuckles, and bolts). A very well made spoiler.

 

The change was noticeable. As in, "heading in the right direction" noticeable.

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DrC

Or something like this

 

ugly-spoiler-1-450x278.jpg

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Smike

I was going to go with the full wood unit as well. Splinters hurt too much though.

 

I designed and sprung my S197 to be tight at high speeds. Use the throttle inputs (lift oversteer) to rotate more.

 

Increase to front rate will help with the overseer more too. Ha, I don't think it has too much front. Just too little rear.

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Smike

On this subject.

 

Rear diffuser. No mention in the rules. Legal?

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MHISSTC
On this subject.

 

Rear diffuser. No mention in the rules. Legal?

 

no mention = no legal

 

 

 

Also, for Adam...

How did your AL and plexi spoilers compare in feel to the factory GT spoiler and NO spoiler on the hatch?

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Smike

Thanks. Even a flat sheet to cover the tank?

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MHISSTC
Thanks. Even a flat sheet to cover the tank?

 

OEM fuel tank or fuel cell?

 

If OEM fuel tank...would probably be considered an aero bit similar to an underbody tray. Not legal.

 

If aftermarket fuel cell, you could likely be somewhat creative in designing a "box" or "cover" for it as long as it clearly wasn't designed with any other purpose in mind... ie. aero. Grey area... ...check with your regional director.

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Glenn
Thanks. Even a flat sheet to cover the tank?

 

Not legal. Gonna be viewed as aero or illegal ballast.

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Smike

Gotcha. Thanks guys.

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Adam Ginsberg
On this subject.

 

Rear diffuser. No mention in the rules. Legal?

 

Although I'll agree sometimes it can be difficult due to various items in our ruleset, the thought process should always be "stock".

 

Diffusers are not legal.

 

Also, for Adam...

How did your AL and plexi spoilers compare in feel to the factory GT spoiler and NO spoiler on the hatch?

 

I only raced the car with the stock GT spoiler once or twice, and that was the first few times I'd EVER raced. I also removed it for the 2010 Nationals at MMP, and dropped a full second a lap (remember that long-assed straight?!?).

 

It was never raced without ANYTHING on the rear - at a minimum, it always had the stock spoiler.

 

Shortly thereafter (early 2004), the formed AL "duckbill" was added to the stock spoiler. There were a few tracks were it proved VERY effective with rear downforce - particularly, Iowa Speedway. On the front banking, and into T1/T2, I could gain ground on several cars, including a few AI cars, as I was able to stay on the throttle, through that entire section of track, into the braking zone. The rear was completely planted.

 

I raced with that configuration from 2004 until this year (like I said, I'm not the brightest bulb in the pack). I'd made a large change to the front suspension, but was still unable to fix the HS push the car had. As I mentioned before, there were discussions with a few folks, and the idea was to pull the duckbill, and try the Blaine Fab adjustable spoiler. The change has been very positive.

 

The reason I wanted an adjustable unit was the lesson I learned at MMP in 2010 - removing the duckbill clearly helped, but when left off the car for the next event at Buttonwillow (Oct 2010), it proved way too loose. It went back on the car before qualifying that day.

 

BTW - the Blaine Fab rear spoiler will fit on Fox hatches, as well as coupes and does not require the Ford emblem to be removed (I've taken the measurements).

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