• David F.

    SSM Aerodynamics questions

    Hey kind folks of the SCCA world. I am relatively new to the autox community and I've read through the rules about a dozen times but just to be safe I'd like a bit of clarification on a couple of aerodynamics modifications I am thinking about doing.


    The first concerning side skirts, the rules state "side skirts may be modified or replaced" however under the front splitter section I read "Splitters may not extend rearward past the centerline of the front wheels" so does this rule out side skirts that are a flat plane and could provide aerodynamic assist and not just aesthetic styling? Picture for example (not my car) they are clearly detatched from the front splitter but just curious on this as I'd hate to invest in something that I just have to pull off. 


    My next question concerns rear diffusers I did not see anything in the street modified section about them at all is there any standards or guidelines to creating one for underneath the rear of your car?


    And my final question is about rear wings I currently have a small duckbill style wing riveted into my trunk (non oe) and am planning on attaching a larger style wing to it rules state "The total combined surface area of all wings shall not exceed 8 sq. ft. (0.7432 m2 ) as calculated per the Wing Area Computation in Section 12. The number of wing elements is limited to two (2). " Mainly concerning the total number of wing elements does this mean flat planes per stand or does this mean that I can have a total of two wings? I currently have this small spoiler riveted in my trunk.

    I would like to add a wing like so to my car 


    I'm fairly certain all these are legal but would just like to confirm before I go ahead and commit to putting the work into them.

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    • Dr. Tobin Gallawa

      For a Miata, I think Blackbird Fabworx has a larger lexan rear spoiler that would be more effective and less obtrusive than a big old wing.  Side skirts are not splitters.  As long as you are not beating anybody, they are not going to gripe about your spoiler being too big.

    • Brandon S.

      Don't take my word for it but I'm pretty sure your just limited to 1 wing per vehicle just as long as it not over the sq. ft. mark. You can have like a stack wing like on the WRX's going to the elements limited to 2.

    • David F.

      I'm assuming by element what is meant is any plain parallel to the ground that is downforce generating. But read the rules again there is no mention to number of wings just the amount of square footage. And wing elements. I mainly don't want holes in my trunk for no reason hence why I don't want to remove it. 

    • Randall Prince

      This is the line in question that concerns the number of elements:

      16.1.K. Aerodynamic Aids: Wings may be added, removed, or modified. Non-OE wings may only be attached to the rear deck/hatch area behind the centerline of the rear axle. The total combined surface area of all wings shall not exceed 8 sq. ft. (0.7432 m2 ) as calculated per the Wing Area Computation in Section 12. The number of wing elements is limited to two (2).

      Specifically, a small "duck spoiler" is allowed and not considered a wing element, iirc. I know of at least one car that has this which is absolutely SM legal:

      Note: This is Mike Simanyi's car, a member of the SEB (the primary rules body of SCCA Solo). For better pictures of what he has, you can look for "E36 CSL trunk" in Google images. If Mike has it on his car, I would trust that it's allowed.

      As for the side skirts, I believe as long as the skirts do not extend inward, you should be ok (visual only). They can't create any more flat plane which could be construed as part of any aerodynamic aid.

      As for the rear diffuser, this is a case of, "if the rules don't say you can, you can't". There are specific mentions for front splitters and rear wings and are thus legal. Rear diffusers aren't mentioned and thus, not allowed.

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