Rule Clarification

[S Lathrop]

I was asked a question today and I do not have an answer that gives me confidence.

Question: How high does a body feature have to be above the bottom of the car to not be subject to the 1 inch deviation rule? If the sides of a car tapper out wards from the bottom, is this legal or must the bottom extend out wards so that only the bottom of the car casts a shadow on the ground?

My cars have the top entrance to the radiators opening extending slightly forward of the bottom entrance. Do I have to add a splitter to hid this overlap?

Are barge boards legal? If not then why not? Or if they can be legal what must they look like?

Better this be discussed now than after some race.

[Rennie Clayton]

What's your case for each scenario you outline?

The most conservative approach would consider the "lower surface" of the car to be anything visible as viewed from below. In which case, anything that throws a shadow should be considered within the purview of that rule. Plan accordingly, and make sure you've got your mirrors covered too...


Cheers,
Rennie

[Art Smith]

Steve-

interesting questions most likely not addressed by the current rules as written in the GCR. I recommend you pony-up the $300 for an 8.4.1 request for clarification; ie: through an Appeal Court. while there are lots of smart folks here at ApexSpeed, it's my sense the only thing constructive that might be achieved is an informed list of potential protest avenues. the opinions of all of the smart folks here, like those of the national staff, have "no standings" with respect to the GCR. as best I can tell, it's about the only way to force the "objectively verifiable" conversation into the aero domain; too many thought (think) the FC aero rules were perfect....................................

Art
artesmith@artesmith@earthlink.net

ps: the F1 Benetton in the large poster on the wall in my computer room has shadow plates for its mirrors...... does the Club have a flat bottom rule or an expedient flat bottom rule?? and if the latter, where in the GCR does it say who gets to decide if it's flat enough?

[S Lathrop]

Art;
I was required to piss away way more money than that to get my current car homologated. It seems that what was acceptable in 1994 was no longer acceptable for 2007. By the same token what has been illegal since 1984 for all formula cars is now allowed, if you are willing to pay for an alternative structure.

More to the point. We obviously have a rule in effect, other wise every DB1 and DB6 would be illegal for FF. This part of the rule is in effect for FF, FC and F1000.

I am trying to get a sense of what people think. As the rule is written, if your mirrors over hang the bottom side of the car you are illegal. As Rennie correctly points out.

[Art Smith]

Steve-

the FF bodywork (ie: aero) rules have been an embarassment for years; none of the terms are defined and the tortured language that attempts to define "flat" is ambigous best-on-best! in the absense of objectively verifiable rules, the rules mean whatever the "Big Dog" in Topeka threatens people with. see Fastrack posted February 20, 2008 keeping in mind a complete "rewrite and reorganization for clarity" of the FF engine rules is also included (full of new rules masquading as anything but).

It is the intent of these rules to minimize the use of “ground effects” to achieve aerodynamic downforce on the vehicle. Thus, for thefull width of the body between the front and rear axles, the lower surface (surface licked by the airstream) shall not exceed 2.54cm (1 inch) deviation from the horizontal in any longitudinal section through that surface. (This is not to be interpreted as requiring a floor pan beneath the motor, transaxle, transmission, or final drive housing.) Diffuser undertrays or venturi tunnels are prohibited. No aerodynamic devices (e.g., skirts, body sides, etc.) may extend more than 1cm (0.394 inches) below the lower surface of the floor pan to the rear of the front axle. Seat buckets or other protrusions shall not circumvent this rule. It is not permitted to duct air through any part of the bodywork for the purpose of providing aerodynamic downforce on the car. All ducted air for heat exchangers (water/oil) shall pass through those heat exchangers

as written, the rule says "flat" within 2.54cm (ie: 1") of the local horizontal
(diviation has NO direction constraint) between the front and rear axles with
no flatness restrictions in front of the front axle line and behind the rear axle
line. the "Big Dog" now says diviations are only "up" apparantly meaning the
equivalent of plus or minus 1.27cm from local horizontal or plus 0.00cm minus
2.54cm from local horizontal. then there's the sticky problem of how, when,
and where to make measurements to confirm compliance with the rule......

as written, I'm good with 3.08cm of total curvature up at any angle with respect
to the direction of travel (assuming a Zero Tolerance approach to compliance
verification). since I have no idea what any of the undefined terms mean AND
I know your heart is devoid of any of the prohibited "intent", you'd be good to
go!!

without objectively verifiable definitions of all of the terms in the rules as written,
the conversation will always be circular and in my opinion devoid of any value
except humor.

Art
artesmith@earthlink.net

[Stan Clayton]

As Art points out, SCCA does not have a "expedient flat bottom rule" rule (nor for that matter a flat bottom rule in FC, at all). What we do have is the following verbiage on p. 192:

Ground effects are prohibited. Deviation of the undertray may not exceed 2.54cm (1”) in the area between the rearmost point of the front tire to the frontmost point of the rear tire. Diffuser undertrays are permitted.

Furthermore, the term "undertray" is defined in the GCR as:

Undertray (Belly Pan) - An attachment to the underside of a car intended to smooth airflow and/or to offer driver protection in this region of the car.

I have never met anyone who considers the mirrors part of the 'undertray'.

Note that there is no reference to 'as seen from underneath' or any other qualification like which has appeared for many years in FIA regs:

All sprung parts of the car situated more than 330mm behind the front wheel centre line and more than 330mm forward of the rear wheel centre line, and which are visible from underneath, must form surfaces which lie on one of two parallel planes, the reference plane or the step plane. This does not apply to any parts of rear view mirrors which are visible, provided each of these areas does not exceed 12000mm² when projected to a horizontal plane above the car. The step plane must be 50mm above the reference plane. [Emphasis added.]

Stan

[Rennie Clayton]

As Art points out, SCCA does not have a "expedient flat bottom rule" rule (nor for that matter a flat bottom rule in FC, at all). What we do have is the following verbiage on p. 192:

...

Furthermore, the term "undertray" is defined in the GCR as:

...

I have never met anyone who considers the mirrors part of the 'undertray'.

...

Stan

Yes, but the pertinent discussion here is the FB rules, which do not mention the word "undertray" - only "lower surface", hence the issue at discussion here.

But speaking of interpretation leading to all kinds of uncertainty, nice insertion of the word "flat" into the discussion, Art... since the rules in question don't mention "flat" anywhere.


Cheers,
Rennie

[Stan Clayton]

My bad...I saw Art's and Steve's references to FC and failed to notice the topic title.

Do carry on...

[R. Pare]

So that we are all looking at the same wording:

GCR - 243
9.1.1. Formula Car Category Specifications
FCS

D. The entrant shall designate a flat rectangular reference area with minimum dimensions of 30cm by 30cm. This reference area is located on the lower surface of the car (the surface licked by the air stream) between the rear of the front tire and the front of the rear tire. The center of the reference area must be no more than 75mm from the longitudinal centerline of the vehicle.

Between the rear of the front tire and the front of the rear tire, no point on the lower surface of the car (the surface licked by the air stream) shall be more than 25mm above the plane determined by the reference area designated by the entrant and on a line perpendicular to that reference plane. No point on the lower surface of the car may be below the plane determined by the reference surface on a line perpendicular to that reference plane, except as specifically permitted herein. Compliance with these requirements shall be accomplished by placing a straight edge on the reference surface designated by the entrant and verifying that the requirements are met. A maximum of four (4) rub blocks of maximum dimension 75mm by 125mm are allowed anywhere on the lower surface of the chassis, and may extend below the reference plane.

From the wording used, I would think that a valid arguement would be that the "lower surface" is pretty much described as being the bottom of the car. If that is valid, then anything above that lower surface is not subject to that measurement rule. Of course, the counter arguement is : "Where is the cutoff point as to how close an item must be to that bottom surface to be considered part of it??

In other words, right back to Steves' original question!

In FF and FC, the rule on "deviation" is worded as "for the full width of the bodywork". As such, any sidepanels that taper outward past the undertray or floorpan would technically be illegal (I doubt there ar many cars that comply right now!) as well a mirrors - mirrors are officially "bodywork" as per the Glossary definition ( never mind that suspension arms, wheels and tires are lumped in that category also!)

[S Lathrop]

The item that sparked my inquire is the shape of the new Phoenix under tray with their "vortex generators" at the leading edge of the side pod bottoms. I think those items are neat and for sure legal.

My question is what are the limits for such items. If I attach a barge board to that protrusion(Phoenix type), will it also be legal? If I were to add a deflector to the leading edge of the side pod similar to those found on the front fenders of a sports car, would it be legal? If I added a wing between the front and rear tires that extended to the full width of the body, how high would it have to be to be legal?


Richard correctly points out that there might not be any legal cars if there was a strict interpertation of the rules. So what is legal and what is not?

[Art Smith]

to me, conceptually, the "lower surface of the car" (the surface licked by the airstream) is what you see looking straight up from below a car parked on a sheet of glass. my bad for not recommending that the suspension and tires be explictly excluded from the domain of the rule (ie: after all, they are part of the car)!!! shadow plates for mirrors have always been in my "required" for compliance jar.

that said, I see no compliance issue with "barge boards" given their lower surface licked by the airstream meets the 25mm requirement. same goes for fender like devices and any associated turning vanes given they meet the width requirement(s).

given compliance with the "lower surface licked by the airstream" rule, I see no compliance issue with one or more wings mounted between the rear of the front tire and the front of the rear tire. the "airfoils are required for this class (see Table 5)" crowd will probably have a very different view given the aerodynamic sophistication required is likely well beyond most home builders.........................

in the world of compliance, there's "compliance" and "non-compliance" with the rule as currently written. if the rule as currently written isn't being verified, that's a Topeka problem. we all are entitled to compete on a fair and level track in compliance with the same rules!! 8.4.1 requests for clarification are a non-targeted means to force a binding decision that puts everyone on notice when it is published (competitors and tech staff). most competitors value their good name and will not knowingly run non-compliant hardware; protests, while normally thought of as unseemly, are always available to deal with the exceptions.

it's my sense the club is better served by adding an exclusion for suspension and tires AND requiring compliance with the rule as currently written. that will leave "aero stuff" above the "lower surface licked by the airstream" wide open. using non-compliance going unchecked as an excuse to pry the rule open on the bottom side of the car is a fandamentlly dangerous path to start down. the car's current horsepower-to-weight ratio and aerodynamic downforce potential have already probably reached (or very very near) the safety limits of the Club's tube frame rules.

Art
artesmith@earthlink.net