Scrutineering question ---

[Christopher Crowe]

We've constructed our rear wing to the maximum allowable width for F1000. In checking some other wings we'd gotten (to reverse engineer), they're about a half inch inside the max. That is, the end plates are well inside the mandated width.

Which bothered us. Do the scrutineers consider things like bolts that hold the wing elements into the end-plates as part of the end plate in terms of the bolts also having to be inside the mandated width? Our bolts stick out -- exactly the amount of a 1/4" bolt head. Does this put us in violation of the rule-book? Our end-plates are inside the max width. But the bolt-heads are not.

Thanks!

[S Lathrop]

I don't think that there is a definitive answer about bolts but logic would tell me that the bolt is an integral and required part of the wing to function, therefore they are part of the wing.

A more important consideration is the shape of the end fence. By putting a gurney along the rear edge of the end fence, with the gurney facing outward, you not only stabilize the end fence but you improve the flow of air along the inside of the end fence -- the wings work better.

I use the gurney to define the width of the rear wing. It is easy to trim and make the wing exactly the legal width. It is also easy to measure.

I intentionally leave enough space to have good functioning gurneys.

Now the gurus of airflow may say this is not efficient but it works.

[starkejt]

I always thought that even the fasteners must be within the max width.

[brownslane]

Buttonhead screws. Lower profile so they will protrude less, lowering drag and a little less width.

[Jnovak]

Bolts and other fasteners count when measuring the width.

Thanks ... Jay

[kea]

I seem to recall the SCCA changing the interpretation of the wing measurement rule for FC to read outside of end plates, not including the fasteners.

[KevinFirlein]

I am sure as you travel the country you will find differnece in the way it gets measured. Yes this can be maddening. I can only speak as to what happened in all my Runoffs tech apprearences and they always included the bolt heads and aero washers. now I havent been since 2005 so the interpertation may have changed but I always count the bolts to be safe.

[R. Pare]

At some point in the not too distant past - 10 years ago maybe? - , it was determined that bolt heads did not count in the measurement. However, since whatever the ruling was didn't get into the GCR, one would have to assume that the bolt heads count.

Better to be on the safe side and make the wings narrow enough to have the bolt heads inside the max dimension (as well as any gurneys you might want to employ).

[R. Pare]

I am sure as you travel the country you will find difference in the way it gets measured.

Just bring along you own shrink rules for the scrutineers to use........

[TimW]

A more important consideration is the shape of the end fence. By putting a gurney along the rear edge of the end fence, with the gurney facing outward, you not only stabilize the end fence but you improve the flow of air along the inside of the end fence -- the wings work better.

Shouldn't the leading edge of the end plate be as thick as the rear wicker at the back? I recall that the leading edge had its own shape (flat on the inner face, curved on the outer) at the leading edge and then flat as it approached the rear wicker.

[S Lathrop]

Tim;
That is not a bad practice but I don't know of any study on the subject. Nathan would be to guru here, I will deferr to him.

[Christopher Crowe]

We should go through the hell of narrowing the thing a bit, it seems.

Again thanks, this kind of information is invaluable to us.

Chris

[Wren]

For some other classes measurements are sometimes given without regard for bolt heads. Nothing like that is said in the FB rules, but the rule is for "maximum rear airfoil width, including endplate." It says nothing about bolts.

I also cannot imagine a rear wing endplate lasting very long without some kind of thickness to it beyond a single sheet of aluminum(gurney or otherwise).

[R. Pare]

Shouldn't the leading edge of the end plate be as thick as the rear wicker at the back? I recall that the leading edge had its own shape (flat on the inner face, curved on the outer) at the leading edge and then flat as it approached the rear wicker.

Not any expert here either, but that would seem to be logical as a means to better keep the airflow attached when in yaw. I would think that you would want a curve on both faces, but there may be some other reasons for having the inside face flat that I am unaware of.

[Rick Ross]

A more important consideration is the shape of the end fence. By putting a gurney along the rear edge of the end fence, with the gurney facing outward, you not only stabilize the end fence but you improve the flow of air along the inside of the end fence -- the wings work better.

There has been plenty of research which confims that this practice can indeed improve rear wing downforce. Of course it also increases wing drag, which can be a concern on some cars. Here is a plot from a 1989 research paper by Katz:

Attachment 31395

The end plate gurneys work by creating a low pressure area on the inside surface of the end plates, which then increases the downforce generated by the upper wing elements. The same effect could be had by adding some outward camber to the end plate trailing edges. Gurney flaps in general have the same effect as increasing the trailing edge camber.....their primary advantage is that they are very easy to fabricate and install. IMO, if drag is not a concern, they are a relatively easy way to increase downforce.

BTW, most research I have seen indicates that a 45 deg angle gurney is the most efficient (best L/D), yet you rarely if ever see this shape around the paddock.

[nulrich]

What Rick said. Also, anecdotal evidence suggests that Gurneys are often more effective on track than CFD and wind tunnel testing would predict.

FB cars have a lot more power to play with than F2000 cars, but producing downforce efficiently is still key. Very small Gurneys may be efficient, but the massive ones you often see are not nearly as efficient as a little more wing angle.

Nathan

[Daryl DeArman]

We should go through the hell of narrowing the thing a bit, it seems.

Again thanks, this kind of information is invaluable to us.

Chris

For some other classes measurements are sometimes given without regard for bolt heads. Nothing like that is said in the FB rules, but the rule is for "maximum rear airfoil width, including endplate." It says nothing about bolts.

I don't know that I'd go through the trouble of narrowing it without first getting a clarification/ruling. Which is going to be more work?

My logic is that if they left off "including endplate" I'd argue that their intent was the entire airfoil assembly. Since they added the words "including endplate" it is logical to infer that the width measurement stops at the endplate.

Since many fasteners are free, I'd be careful that my fasteners didn't perform some other prohibited function.

[Jnovak]

An official ruling will cost you $300.

Thanks ... Jay Novak

[RobLav]

Use AN countersunk screws and those nifty washers.

[starkejt]

Wing fasteners are free?!?

So, who else is trying to figure out how to fasten the wing together using tunnels and a supercharger?

[Wren]

Wing fasteners are free?!?

So, who else is trying to figure out how to fasten the wing together using tunnels and a supercharger?

Brandon got his attached with a second '07 GSXR1000 engine.

[Christopher Crowe]

But I sure wish the SCCA would be a bit clearer on these issues. For those of you that are professional car builders... the GCR's ambiguities must absolutely drive you insane.

Again thanks to everyone for the advice.

[Jnovak]

In my opinion the rules are clear. It states:

[FONT=Univers][FONT=Univers]I. Maximum rear aerofoil width (includes endplates) 95cm[/FONT]
[FONT=Univers][/FONT]
[FONT=Univers]It is pretty clear that anything that has to do with the wing or end plates cannot be any wider than 95cm. Any other interpretation is a stretch of the imagination PERIOD. If you think the fasteners are not part of the wing and or the end plates I suggest that you remove all those fasteners and race without them and see if you have a wing of any sort.[/FONT]

[FONT=Univers]Tech might let you slide but if the fasteners are wider than 95cm outside to outside it is illegal.[/FONT]

[FONT=Univers]Thanks ... Jay Novak[/FONT][/FONT]

[R. Pare]

In my opinion the rules are clear.

It is pretty clear that anything that has to do with the wing or end plates cannot be any wider than 95cm. Any other interpretation is a stretch of the imagination PERIOD.

Not necessarily, based on the fact that some years ago it was "clarified" that it did not include the fasteners. Phil Creighton probably will remember the timing better than I - I think he was the CRB chairman at the time.

You are correct in that since the "clarification" did not get published in subsequent GCRs, it does not exist as a rule. However, IF someone were to protest a wing for the heads sticking out too far, AND the person being protested had a copy of that clarification to present as "prior ruling history", the Stewards would most likely take that clarification into account.

This unfortunately is another of those "gray" areas that those of us who have been around for way too long remember as having been settled at some point in time, but never got properly incorporated into the GCR.

[Jnovak]

Like I said Richard, if the bolts are not part of the wing then take them out & I think you will see that they are part of the wing.

This thread is not worth anyone's time IMHO. People looking for holes in the rules where there are none.


I'm done.

Jay

[Daryl DeArman]

But I sure wish the SCCA would be a bit clearer on these issues. For those of you that are professional car builders... the GCR's ambiguities must absolutely drive you insane.

Glad you found a solution.

Those of us that aren't professional car builders see the ambiguities. The ones who build cars or have been around a long time are certain what the rules mean and generally aren't open to too many other interpretations. Many of them appear to have some measure of insanity...so perhaps you've discovered the root cause.

[R. Pare]

Glad you found a solution.

Those of us that aren't professional car builders see the ambiguities. The ones who build cars or have been around a long time are certain what the rules mean and generally aren't open to too many other interpretations. Many of them appear to have some measure of insanity...so perhaps you've discovered the root cause.

Unfortunately, those of us who are, or have been, both know the rules, their history and just how crazy/stupid the interpretations can be over the years as the personnel in charge of final interpretation change. And, yes, it does/did drive us nuts - what was declared legal one year may be declared illegal 3 years on down the line, or visa versa. Hence the push by the manufacturers to get the rules written more clearly.

If I remember correctly, the clarification I spoke of was issued sometime in the mid-'90's, and we as well as most other manufacturers took advantage of it. Now, if indeed the interpretation is that the bolt heads count, there are probably a lot of cars out there with non-compliant wings.

And that IS worth someone's time to get straight.

[starkejt]

Just curious. Has anyone been at an event where there was someone working tech that was capable of measuring something to +/- bolthead?

[Phil Creighton]

I can't remember which class the issue came up with but I remember somebody making the argument that if it said including endplates but didn't include fastners - they must be exempt. I thought it got bounced anyway. It comes up quite often and C/S screws fix most issues permanently. I wouldn't risk a Runoffs result on the argument that fastners don't count - I think it would be a loser.

The addition of the 'and endpates' came when the first FB Stohrs were built and the rules were written 'width of airfoil' . This was a mistake in the rules writing by the committee and it was fixed quickly - otherwise anything could have been hung on to each end as 'endplates'. the F2000 rules were always different.

As to the problems of the GCR remember the convoluted discussions on this and other sites - everytime an issue gets brought up the rules get added to and it seems illogical till you understand the history: hence the much reviled attempts at rewrites.

Phil

[Phil Creighton]

Actually there are a lot of good guys that can measure things at Tech if they were allowed to - unfortunately the membership sees any checks as a witch-hunt if they are the ones checked so tech has been largely gutted except for the Runoffs. The only times things get measured if protests fly.
Now stewards remeasuring things - thats a more interesting subject
phil

[Daryl DeArman]

Unfortunately, those of us who are, or have been, both know the rules, their history and just how crazy/stupid the interpretations can be over the years as the personnel in charge of final interpretation change. And, yes, it does/did drive us nuts - what was declared legal one year may be declared illegal 3 years on down the line, or visa versa. Hence the push by the manufacturers to get the rules written more clearly.

If an interpretation is crazy/stupid but official personnel rule such interpretation correct is it still a crazy/stupid interpretation? rhetorical as I've seen plenty of rulebooks with crazy/stupid rules over the years....rules mostly written rearward looking.

[R. Pare]

When someone tries to argue that the person/people who actually wrote the rule are wrong, or argues against 25-30 years of interpretive history, then yes, I would have a tendency to question their sanity!

Probably I'm incorrect in that, though - most likely it is more their ego getting in the way.

BUT, whatever way the official interpretation ends up being, crazy or not, that's what we all have to abide by, until the rule or interpretation changes again.

[starkejt]

http://youtu.be/x6YkEUPKEX4