Airfoil Suspension Arms

[TKemp]

Hi Guys,

I have a question concerning Rule B.1 paragraph 3.

"It is not permitted to construct any suspension member in the form of an airfoil or to incorporate a spoiler in the construction of any suspension member."

I work for a company that is producing all new race chassis systems for FB, FC, FF, DSR, CSR. I am low on the authority pole and thought I would put this to you.

I noticed that we are making the control arms for the FC cars from round tubing and the others are made from symmetrical airfoil shaped tubing. I noticed that almost all the FC cars at an event I attended, had control arms made of the airfoil shaped tubing. I asked my boss about it and said that the FC cars are mandated by the aformentioned rule, against the use of the airfoil tubing.

My question is that is this a new rule and are all the cars going to have to convert the control arms? or, is this a rule that is simply not enforced?

Thanks
Todd

[DaveW]

This means that symmetrical, horizontal with the air flow, aero tubing is legal. Tubing that creates downforce is not.

[Stan Clayton]

My question is that is this a new rule and are all the cars going to have to convert the control arms? or, is this a rule that is simply not enforced?

Neither, Todd. At the time that rule was written (~1976) suspension tubes that were 'ovalized' or 'symmetrically streamlined' were not considered 'airfoils'. Tubes shaped like an upside down wing (flat on top with a cambered undersurface) were considered airfoils and are prohibited under the rule, as are attachments to the tubes which have the same effect. Stan

PS - Thanks Dave. I see you weighed in while I was stirring the pasta sauce...

[TKemp]

Turns out, If I would have been more clear with my question to my boss I would have got the same answer you gentlemen replied with. I asked him why we weren't making arms with wing shapes for the Continentals, he replied with the reg that I quoted from memory and recommended that I look it up.

Turns out, we do use an airfoil shape on the more expensive arms but it is a symmetrical one. The round tube arms are being made for all the cars also as a means of offering a very economical option for those that choose so. I could not believe the price difference between the TIG welded 4130 aero arms and the DOM MIG welded round tube arms. If it means the difference between racing or not, less than half the price makes sense.

There seems to be a great emphasis here with producing cost effective counter parts to the high dollar options. With the economy the way it is, I think it is wise.

Next time I will attempt to be more clear with my questions in the shop before going outside for answers. Thanks for the rapid reply, you guys are great.

Todd

[R. Pare]

.... MIG welded round tube arms.

Todd

I do hope that is a typo.

[Art Smith]

Todd-

after first agreeing with everything posted to date, here's an orthogonal view that might offer an enterprising young man like your self a business opportunity to serve the top 5-10% of the market that constitute what I call the "bleeding edge" market.

first and foremost it's important to recognize that what is commonly referred to as "airfoil" tubing is NOT, it's correctly called "streamline" tubing. I've included for reference an image of p.63 of the current Aircraft Spruce catalog illustrating that even suppliers that service the lowspeed aircraft and related markets refer to it as streamline tubing in their catalogs. it's been a while since I've looked at a copy of the streamline tubing Mil Spec so don't remember if Mil-T-6736 will get you there or it's just the specification on the 4130; pulling a copy is time well spent and you'll find the detailed information provided fascinating.

streamline tubing's origins date back to the late 1920's and/or early 1930's. stronger more reliable solutions were required for structural elements in the airstream and round tubing's drag coefficient was then as now unacceptable. the country's answer was a comprimise solution that balanced the then state-of-the-art forming capability, the properties of 4130, the structural properties of the resulting section, and last but not least the low speed drag coefficient of the resulting section. more than eighty years later it still remains an outstanding material when properly used!!

like all cost driven comprimises in a performance driven market, the comprimes made 80+ years ago in the specification for streamline tubing present potential opportunities in a "bleeding edge market". the low speed drag coefficient for streamline tubing while a factor of three better than a round tubes does not compare well with real fairings such as NACA 0008, or NACA 0010, or NACA 0012, or even NACA 0014. better catalogs for streamline tubing frequently include a figure of merit column labeled equivalent tension round tubing, equivalent compression round tubing, and weight per foot. the catalogs are attempting to provide useable guidance on column buckling capability of the streamline tubing. the mil spec for streamline tubing and better texts on aircraft structures have the actual moments of inertia so the approximate values in the catalogs don't have to be used. columns (suspension arms) always fail in the direction of minimum moment of interia and as a consequence drives sizing decisions on the use of streamline tubing for suspension pieces.

given some design work and a little fabrication cleverness, it's my sense a lower drag AND lower weight per foot fabricated all steel product (for GCR compliance) should be possible for the bleeding edge market. a quick look at the tables will confirm that the equivalent compression round tube diameter is always smaller than the thickness of the streamline tube meaning smaller frontal area for the drag calculation (in addition to the vastly improved drag coefficient from use of one of the real fairing profiles) and lower weight assuming a 0.005'-0.010" fairing implementation with intermittent ribs. no end fittings to get the loads into the fabricated all steel product would be required, lighter than all current approaches used with streamline tubing. the product would work particularly well on modern push-rod suspension cars where the A-arm rod-ends see almost no bending loads, only tesnion and compression with the resulting much smaller threaded shank diameters.

projected market size is unknown and likely small. YMMV.

Art
artesmith@earthlink.net

[TKemp]

I do hope that is a typo.

I don't understand. What do you mean?

[TKemp]

Todd-

after first agreeing with everything posted to date, here's an orthogonal view that might offer an enterprising young man like your self a business opportunity to serve the top 5-10% of the market that constitute what I call the "bleeding edge" market.

first and foremost it's important to recognize that what is commonly referred to as "airfoil" tubing is NOT, it's correctly called "streamline" tubing. I've included for reference an image of p.63 of the current Aircraft Spruce catalog illustrating that even suppliers that service the lowspeed aircraft and related markets refer to it as streamline tubing in their catalogs. it's been a while since I've looked at a copy of the streamline tubing Mil Spec so don't remember if Mil-T-6736 will get you there or it's just the specification on the 4130; pulling a copy is time well spent and you'll find the detailed information provided fascinating.

streamline tubing's origins date back to the late 1920's and/or early 1930's. stronger more reliable solutions were required for structural elements in the airstream and round tubing's drag coefficient was then as now unacceptable. the country's answer was a comprimise solution that balanced the then state-of-the-art forming capability, the properties of 4130, the structural properties of the resulting section, and last but not least the low speed drag coefficient of the resulting section. more than eighty years later it still remains an outstanding material when properly used!!

like all cost driven comprimises in a performance driven market, the comprimes made 80+ years ago in the specification for streamline tubing present potential opportunities in a "bleeding edge market". the low speed drag coefficient for streamline tubing while a factor of three better than a round tubes does not compare well with real fairings such as NACA 0008, or NACA 0010, or NACA 0012, or even NACA 0014. better catalogs for streamline tubing frequently include a figure of merit column labeled equivalent tension round tubing, equivalent compression round tubing, and weight per foot. the catalogs are attempting to provide useable guidance on column buckling capability of the streamline tubing. the mil spec for streamline tubing and better texts on aircraft structures have the actual moments of inertia so the approximate values in the catalogs don't have to be used. columns (suspension arms) always fail in the direction of minimum moment of interia and as a consequence drives sizing decisions on the use of streamline tubing for suspension pieces.

given some design work and a little fabrication cleverness, it's my sense a lower drag AND lower weight per foot fabricated all steel product (for GCR compliance) should be possible for the bleeding edge market. a quick look at the tables will confirm that the equivalent compression round tube diameter is always smaller than the thickness of the streamline tube meaning smaller frontal area for the drag calculation (in addition to the vastly improved drag coefficient from use of one of the real fairing profiles) and lower weight assuming a 0.005'-0.010" fairing implementation with intermittent ribs. no end fittings to get the loads into the fabricated all steel product would be required, lighter than all current approaches used with streamline tubing. the product would work particularly well on modern push-rod suspension cars where the A-arm rod-ends see almost no bending loads, only tesnion and compression with the resulting much smaller threaded shank diameters.

projected market size is unknown and likely small. YMMV.

Art
artesmith@earthlink.net

The fabricators in the shop called it "Aerotube" and "Strut Tubing", the plans refer to it a "seamless streamline tubing 4130N", the boss called it "streamline tubing", the invoice and packing slip refere to it as "airfoil alloy tubing 4130N mil spec......" the steel rack is labeled "USE with PERMISSION ONLY - sign-out requred of all streamline and oval tubing on rack" There is oval shaped tubing on the rack. Terminology can be hard to learn and I know that there is always hell to pay here when someone calls steel tubing "pipe".

As far as the top 5% to 10% of the market, we ar making some very expensive stuff for them, but for they guys that have to pinch every penny, it seems like we are bulding an different option for them as well.

As far as all the "AERO TECH", it is not up to me. I do however, believe that the airflow must be very chopped up behind the front wing.

My boss gave me some stuff to take home to read. It looks like some of it is data from fatigue testing and other testing such as destructive testing. I am now suppose to come back in tomorrow and provide a reason for why the welded joints are designed as they are on the two different arm styles. I also have to figure out why they put the expensive arms in the heat treat oven but the round tubing arms don't have to go in the oven. I think it has to do with the materials that the arms are made of but I am not allowed to guess.

I have also been watching the process for making the arms and the process is completely different. I can see why the costs are so much different. I would really want the advantage of a reduction in drag from the expensive arms, but by the time you start adding up all the costs associated with only using the best stuff, someone on a limited budget may never get on the track. Low cost options are good for people that have not yet developed the skills to win anyway. Gaining that experience with less expensive options is better than not getting any experience at all. In reading the doom and gloom thread up in the General Forum, cost reductions are definitely stuff than needs to be considered.

Time to go home
Todd

[DaveW]

I don't understand. What do you mean?

I assume he is referring to MIG welded vs TIG welded...

[Modo]

This is a formula ford rule (no wing) meaning practically no downforce et. al.........so it would be in the interest of a FF (no wing) manufacturer to cheat the 4130 aerotube in the downwards direction....unintentionally of course....Hi!! Hi is telegraphers laugh....dit dit dit dit.... dit dit!!!......expensive if discovered (time and trouble) BOTTOM LINE IS, THERE ARE SYMETRICAL AIRFOILS, SO WE ARE ALL ILLEGAL...GOOD POINT NEW GUY!!

[TKemp]

So, in tech inspection, do they measure the angle of attack, of your control arms, in reference to the ground or chassis floor.

What else I have to report is that I had a chance to look at some CFD stuff on the new cars and noticed that on the FC car, the front wing changes the angle of "relative wind", new buzz words from my boss, in relation to the level mounted "STREAMLINE TUBING" control arms. It was pointed out that, even with political correct use of that tubing, the net result is conterproductive, to a point, because the angle of attack in relation to the airflow is actually positive, ie lift. A point to considder is that the closer the wing is mounted to the control arms, the more tendancy there is to actually stall the control arm tubes with airflow seperation at the top near the trailing edge resulting in more turbulance. What I saw was really cool, and in paying attention to what was said would have meant nothing without the visual representation.

If the airstream is modified by the front wing, how much would you have to angle your control arms forward for any realistic downforce gain??

After all this I was told to look at the airstream behaviour behind the control arms and it was pointed out that even with the issues I have described, the "streemline" tubing causes the streamlines to consolidate whereas the round tubing did not consolidate the streamlines and the air looked more turbulant for a great distance to the rear.

By the way, I bet you know this, but the reason that they heat treat the 4130 arms is to normalize the metal so that it does not fail at the weld due to weld related embrittlement, the mild steel is not as suseptable as the alloy steel. Alloy steel is stronger but the mild steel is cheaper and less finiky but ends up heavier due to the strength difference. I am learning .

By the way, the tubing producer define the streamline tubing as an airfoil for the purpose of streamlining the airflow or controlling the direction of airflow in applications such as: wing strut supports, landing gear struts; stator and turbine impellers, blades and fins; race car suspension components; suspension cable shrouds to minimize wind induced flutter; etc....

Todd

[Modo]

WHewwwww!! again...............power in numbers...we all use areo tube!! do u wrk fer steve??? Orrrr, new US Chassis GUYS!!

[BoulderG]

Todd,
Just as a side comment, I think you are extraordinarily lucky to have a boss who puts so much time and effort into helping you learn.

I've been fortunate enough to have a couple of great bosses and it's a wonderful experience.
Make the most of it!

[TKemp]

Aerotube ........ sound cool, kind of like Slip-n-Side is a more vogue name for a flat piece of plastic. Whats more, it was made by "Wham-O".

Not for Steve, Steve Who?

Todd

[TKemp]

Todd,
Just as a side comment, I think you are extraordinarily lucky to have a boss who puts so much time and effort into helping you learn.

I've been fortunate enough to have a couple of great bosses and it's a wonderful experience.
Make the most of it!

I know.

I was late for work this morning and I know that I did myself no favor. I will work through lunch while off the clock.

Todd

[Modo]

u r in Illinois, not Indiana, I see now.....no Steve...r u new chassis group?? be nice fer US since everyone thinks this place is going down the tubes..... bank any US engineer against ...well whatever....can crunch numbers as well...do I have too...pay the Asian Indians and call it a day!!!! aerotube...ok calling 4130 STREAMLINE makes it not an airfoil....doubt it, don't take that to court!!!Hi HI HI !!.... tubing available at the Spruce Goose and Dillsburg Aeroplane wrks in PA in 4130.....I have the additional problem of coming up with whatever the stuff is on my Tatuus....better give TaTTo a call and get the original before I go to wide track....squished round is what it is....dc region racer did that for a 96 VD and vowed never to go thru that again...not easy

[TKemp]

LMAO

OK Guys, even though the public release will come very soon, I was provided a teaser shot in order to show you the kind of opportunity I have been granted here. This is a picture of Matt, doing the "Wax-On-Wax-Off Grasshopper" routine on mold. Matt is a college student working his way through school and has worked his butt off here. We are encouraged to learn and apply what we learn. This is neat stuff but very hard work.

As for the picture, this is a engine cover and rear turtle deck mold that represents a glimpse of what will be coming out soon. This will be used on several car designs here and is a part of a common fuselage used for new FC, FF, FB, DSR, CSR cars. I will leave it at that. please don't ask for more untill the official release of information, soon.

[Larry]

So, in tech inspection, do they measure the angle of attack, of your control arms, in reference to the ground or chassis floor.

____________________________________________

I have never seen any tech inspector attempt to measure angle of attack (AOA). I doubt they have either the ability or the equipment to do it. I don't mean this disparingly, as I spent 5 years as a tech inspector. In aviation, AOA is the angle between the mean aerodynamic chord and the relative wind. Therefore, if tech ever attempted to measure AOA, it should be done in relation to the ground (in hopes that the chassis is contacting the ground and moving forward, creating the relative wind).

Larry Oliver
International Racing Products

[TKemp]

So, in tech inspection, do they measure the angle of attack, of your control arms, in reference to the ground or chassis floor.

____________________________________________

I have never seen any tech inspector attempt to measure angle of attack (AOA). I doubt they have either the ability or the equipment to do it. I don't mean this disparingly, as I spent 5 years as a tech inspector. In aviation, AOA is the angle between the mean aerodynamic chord and the relative wind. Therefore, if tech ever attempted to measure AOA, it should be done in relation to the ground (in hopes that the chassis is contacting the ground and moving forward, creating the relative wind).

Larry Oliver
International Racing Products

Larry, I believe the conversation became facetious. I was asking the question in the beginning because of the exact wording in the FC section of the GCR. For FC, the content in the FC section takes presidents over the FF section.

It was explaned to me that the relative wind varies over a shaped body based on the influance of the shape on the flow of the air. I was told that aircraft designers attempt to place AOA sensor veins, in a location that airflow influence, nearly represents the viable angle of attack of the general lifting body in order that that stall and lift charactoristics are acuratly reflected in the instuments relative to the wings and other lifting surfaces.

Technically, unless you maintain a true parallel relationship between the flowing airstream and the "symmetrical streamline tubing", it becomes a viable lift inducing device and Bernoulli Principals apply, based on what I read in a book loaned to me last night by my boss, "Theory of Wing Designs" by Ira H. Abbot Director of research NASA, based on both NACA and NASA studies. My boss somehow manipulated my purely facetious internet experience, into a learning experience for me. Had this not taken place I would have gone out chasing desirables last night, instead I found myself fascinated with the theories of flight, or non flight for cars, until 3:10 am. I have never been motivated to dive into homework when I was in school, like I find myself doing while working here. I feel really cheated that my school teachers cheated me so badly from real viable learning due to their inability to inspire my quest for excellence as I am starting to hunger for. It is to bad that teachers don't seem to have the ability to inspire by example. It seems that my none of my teachers, in retrospect, had any real tangible hands on experience.

Chasing knowledge instead of chicks????

Oh no, I am becomming a nerd !!!

In all seriousness, why would SCCA specifically deviate from the wording in the FF section for the FC cars, if they did not have other intent for FC. It is very specific in the FF specs they allow the symetrical airfoil arms but in the FC section they specifically seem to dissallow them.

Does anyone know of this issue being addressed before?

Todd

[TimW]

I have never been motivated to dive into homework when I was in school, like I find myself doing while working here. I feel really cheated that my school teachers cheated me so badly from real viable learning due to their inability to inspire my quest for excellence as I am starting to hunger for. It is to bad that teachers don't seem to have the ability to inspire by example. It seems that my none of my teachers, in retrospect, had any real tangible hands on experience.

Sorry, this is a bit off topic but living with a professor of education has enlightened things about my own education quite a bit recently.

Sadly, this is not entirely the fault of the teachers as over the last 20 years education has become standardized and scripted leaving teachers little room for individual creative inquiries by students. No Child Left Behind has exacerbated the problem even further with even more widget manufacturing methods coming to schools. Whats really sad is that the really good teachers who creatively develop their lesson plans to inspire the set of kids they have in the room are leaving the profession in droves because they now must only present the material & reading lists that are within whatever curricula was purchased from a large curricula planning company which is directed to appeal to a vast audience that is not specific for the particular experiences the kids in the room bring to class. Largely the teachers that remain are those that have been monodrone teaching repetition all along and the good ones who are still fighting the fight that not all students learn the same things the same ways and adapt their curricula to the given set of kids. Obviously, good and bad teachers exist in the profession (just like good and bad professionals in any profession) but cutting the good ones off at the knees to prevent the bad ones from being useless can be a myopic solution, IMO

</soapbox>

[R. Pare]

In all seriousness, why would SCCA specifically deviate from the wording in the FF section for the FC cars, if they did not have other intent for FC. It is very specific in the FF specs they allow the symetrical airfoil arms but in the FC section they specifically seem to dissallow them.

Does anyone know of this issue being addressed before?

Todd

While the wording may be poor, there is no conflict between the two - you have to remember the Glossary definition of an "airfoil" - ie - it has to create a vertical force from the airflowing over it.

"Streamlined" and "airfoil" are not necessarily the same thing in all cases. Nor is "streamlined" necessarily the same thing as "symmetrcialy streamlined".

I won't bother at the moment outlining the various meanings - that should be your next assignment in educating yourself!

[TKemp]

Tim W.


Inspiring a whole new generation of mind numb little communists, that is what I was being taught to be in school, more so before No Child Left Behind than after. Your complaint is flawed.

I learned that it is OK not to understand math as long as my feelings weren't hurt because I was not as smart as someone else. This was what they called "OUTCOME BASED EDUCATION"

I learned that our Founding Fathers intended our nation to grow into more of what Karl Marx intended instead of people getting rich by owning large corporations.

I learned that it was immoral to join the Navy.

I learned that Ronald Regan was like Hitler.

I was told that George H. W. Bush worshiped the devil and was a member of the Illuminati and planned to round up people and eliminate them to control population.

I was taught that the President conspired with the Japanese to bomb Perl Harbor.

I was taught that the Constitution really provides that businesses should pay the government and then the government is suppose to provide us what we need in order to promote the general welfare.

I was taught that my grandfather murdered children because he was in the Army.

I was taught that my dad was being an abusive parent because he grounded me for not memorizing my Times Tables.

I was taught that everyone should have the same pay regardless of how much skill or talent is required for a job.

I was taught that Lewis and Clark raped and plundered all the Indians they met on their exploration.

I was taught that Benedict Arnold was really a true patriot and should in high regard just like Michal Moore.

I was taught that the battle at Fort Wagner by the 54th Massachusetts was really a fabrication in order to provide propaganda for Lincoln.

I was taught that President Johnson had Kennedy assassinated in order to go to war in Vietnam.

I was taught that the second amendment was added in secret and was never really agreed to be in the Bill of Rights.

AND I CAN GO ON AND ON.

This was all taught to me before the No Child Left Behind program was initiated. And even after that, what was taught was garbage, worthless garbage. I was cheated, by a bunch of Communist Union Hacks. Abortion, hell yes, but not kids, abort the Teachers Unions. They get raises and got more time off, we learned less and had our industrial arts programs cut. There is no accountability in public education and they don't give a damn if kids learn accurate information or not as but they and the Union Thugs get their pay rises and extortion fees..

I grew up in a financially challenged family and I wish to GOD, that somehow, if I have kids I will be able to choose the school they attend and not be a victim like me.

I am going to drop this now because I am now hotter than an acetylene torch.

Todd

[Wren]

Well, this thread has gone well.

So when is the big announcement of the FF, FB, FC, DSR, and CSR? Any word on who might actually be interested in buying them?

[rickb99]

Well, it's pretty obvious from the photo above that something is really going on here. It isn't just random ramblings testing the knowledge base of Forum members.

What is rather amazing is, a project of this magnitude going on without more information leaking out about it. Or, who's the Big Kahuna, who's the Leader of the Pack and better yet, who's Shekel's are making this happen?

[Wren]

Well, it's pretty obvious from the photo above that something is really going on here. It isn't just random ramblings testing the knowledge base of Forum members.

What is rather amazing is, a project of this magnitude going on without more information leaking out about it. Or, who's the Big Kahuna, who's the Leader of the Pack and better yet, who's Shekel's are making this happen?

It's a company called shaw chassis technology. There is very little information out there about them.

Anyone know anything? It looks like a new chassis and design into the market.

I don't understand the desire to develop in private, it certainly shuts out a lot of potential customers.

[TKemp]

No blue sky sales.

This is premature, but I have been tasked with providing some degree of followup after my earlier posts.

Too many times the cart is placed before the horse and orders are taken before a product is really ready for market. This is a venture that has been moved along through stubborn tenacity and is coming to light in spite of serious capital losses in the real estate industry and other assorted obstacles.

I am told that the reason for looking to SCCA venues has a lot to do with the enthusiasm of single F1000 competitors insistence that his class and others would grow provided that builders would be willing to risk business ventures geared toward club racing.

The main reason for tipping this project over the edge, with respect to commitment and that ptojects have gone as far as they have, is that there are many formula and sportscar classes here that can share much of the same components and basic foundation. There is also a demand for new options for competitors in the fledgling F2000 Pro-Series that seems to have no difficulty in regularly fielding 44 cars or so.

The Track Day market is very good to us with customers that are willing to spend a great deal on toys with a one-upmanship mentality. Club racing offers these clients an oportunity to take part in sanctioned competition for the generl fun of it. This without the large committment and outlay to run a pro series and be mocked for being a "Gentelman Competitor", very condesending. There is a strong belief here that club racing can prove to be a venue, like Track Day driving at Autobahn Country Club, where enthusiasts can use the events for business relationship building, hob knobbing with conteporaries, and just haveg fun without the stress of high profile racing. Our clients relate it to a high speed exilerating alterative to golf.

Club racing needs an infusion of new blood and Formula car and sports racer classes need a new infusion of modern and exciting new race cars.

Watching guys like Matt Conrad taking risks to base his future on the belief that there is prospects and business sense to be had with club racing, has motivated us. Looking at projects accomplished by Mike Devins enthusiasticly for a limited number of customers with drive and passion for what he is doing is motivating. Reading about individual projects comprised of creative juices that flow regardless of large piles of cash on hand. It is obvious you are all passinate.

The company I work for is going out of its way to not only build cars but to produce project components like frames, subframes, suspenbsion pieces, composite parts, aero parts and a myriad of other useful items geared toward the do it yourselfers. The circle track and drag race enthusiasts have access to all kinds of ecconomical components, sports racers and formula racers and builders want the same, so we hope.

It is said around here almost every day, stop talking about it, build it.

I had some help with this reply and would encourage you to keep an eye out for us. We maintain a low profile at this point because we are not quite ready for official release. Secondly we are not accepting or soliciting deposits or sales orders right now because we have plenty of obligations in work to keep us buisy. Sales orders will be based on what we have to sale, not what we hope to have..


Patience

Thanks
Todd

[Larry]

There is an incredible amount of bad information floating around. We completely expect everyone to do whatever they can to reduce drag, and this certainly includes a wide variety of fairings, streamlining, etc. To this extent, a piece of symetrical aero tubing angled slightly downward can cause downforce. So, if I run 3/4" of rake on my car, which puts my aero-tube wishbones at a downward angle, it could produce downforce--but just how much, and can this really be proven?

I guess it could be proved using a wind tunnel and a couple hours of high-$ time, but I suspect the amount of downforce would bea pound or two. The primary reason for using either aero or oval tube is drag reduction.

Personally, I find the cost of the more expensive tubing in comparison with normal, round tube to be outrageous, but in the quantities used, it probably adds only $300 to the cost of a chassis, so no sense trying to legislate against it.

Larry Oliver
International Racing Products

[Greg Mercurio]

All the foregoing is nice and all, but there is already a formal request to the CRB to change the FC suspension wording to match the FB wording. I'm still waiting for the resolution as it was "tabled for further study".

An airfoil is an airfoil is an airfoil. Symmetrical or asymmetrical is the difference between the FC and FB GCR descriptions. Whether or not it creates downforce is moot, the GCR specifically forbids airfoil shaped suspension components in FC but specifically forbids assymetrical airfoils in FB.

[Dave Gomberg]

All the foregoing is nice and all, but there is already a formal request to the CRB to change the FC suspension wording to match the FB wording. I'm still waiting for the resolution as it was "tabled for further study".

See the October Fastrack (which should be out tomorrow).

Dave

[R. Pare]

An airfoil is an airfoil is an airfoil. Symmetrical or asymmetrical is the difference between the FC and FB GCR descriptions. Whether or not it creates downforce is moot, the GCR specifically forbids airfoil shaped suspension components in FC but specifically forbids assymetrical airfoils in FB.

Sorry, but according to the Glossary definition, which is the OFFICIAL definition of what constitutes an "airfoil", vertical force production IS the only thing that matters in the determination - no definition is given on shaping.

GCR - 109
Appendix B. Technical Glossary
General

Airfoil - An aerodynamic device or part of a car which the flow of air over its surface will generate a vertical force by creating a pressure differential between top and bottom surfaces.

By this current definition, anything on the car that creates a vertical force via air flow over upper and lower surfaces is an airfoil, regardless of the shape.

In FC, the rule is:

GCR - 192
9.1.1. Formula Car Category Specifications

B. FORMULA CONTINENTAL PREPARATION RULES

B.1. Chassis

It is not permitted to construct any suspension member in the form of an airfoil or to incorporate a spoiler in the construction of any suspension member.

This rule disallows ANY suspension component from creating a vertical force from air flow. The shape is irrelevant - assymetrical or symmetrical makes no difference according to this definition.

In FB, the rule is:

GCR - 242
9.1.1. Formula Car Category Specifications

H.2.Chassis

G. It is not permitted to construct any suspension member in the form of an asymmetrical airfoil or to incorporate a spoiler in the construction of any suspension member. Symmetrical streamlining of suspension members is permitted.

This wording actually allows symmetrically shaped airfoils (ie - vertical force producing), since the rule only forbids assymetrically shaped airfoils.

The problem in using this Glossary definition is in determining, and then proving, whether or not a suspension member is creating a vertical force. As Larry stated, the angle of attack to the local airflow is what will determine whether or not a vertical force is created - and remember that the creation of lift also makes something an airfoil by that glossary definition!

It will be interesting to see what the new wording is, and if it has actually been corrected correctly!

[Stan Clayton]

With all due respect for Richard's excellent deconstruction of the GCR's vebiage, I have to ask what folks want...a GCR that is filled with obstruce, lawyeresk/engineer-speak language (shall I call it 'objectively verifiable'? ), or a common-sense GCR that anyone can read and understand?

(Yes, I understand that it's a balance of the two.)

Now, before you go off on a tangent, bare in mind that the passage in question has been in the GCR since (IIRC) 1976. In other words, for 30+ years folks have understood what this passage means - don't build your suspension members in the shape of an airfoil! And don't weld your car's suspension members in such a shape that they accomplish the same thing...our Tech Inspectors aren't as dumb as some might think.

This "tempest in a teapot" pales in comparison to my favorite passage in the GCR...see the first sentence of the third paragrpah in 9.1.1.B.2. on page 192, "Ground effects are prohibited."

Off to make a pot of tea...

[TKemp]

Clarity, plain English, non gibberish definitions is what we need. In reading through the rules of many classes in SCCA, I see a lot of double talk and a lot what looks to be worded with ambiguity deliberately. When enthusiasts are paying tens of thousands of dollars every year to pour their guts into racing for what amounts to a pat on the back, it is imperative that they have enough confidence that what they are racing is legal based on clear language in the specifications.

As far as symmetrical versus non symmetrical, it could be argued that even an airfoil that is symmetrical when static and mounted on a car level and bolted tight to a surface plate, becomes asymmetrical as soon as any angle of attack is introduced because the center of pressure on the leading edge shifts upward and the angle of attack slants negative.

Here is the beef, what is going to happen when someone builds a fully webbed symmetrical streamlined shaped arm? Say this arm has fully symmetrical NACA 0012-64 shape that is triangular in plan view. This shape, having a cord of 24" at the tub mount and 2" at the ball joint. This arm mounted exactly parallel to the lower floor of the car. By definition, this arm meets the requirements just as much as the "streamlined tube" shape arms, except that the surface area in magnitudes greater. The same argument can be made that this design is such to merely cleanup the airflow and reduce the induced drag. Are the same people defending the symmetrical shaped aero tube arms going to also defend the arm that I described, especially if the vehicle it is attached to supplies a substantial case of whoop-ass? I would guess that a major squawk session would ensue specially if this is a car constructed new with all modern technology and computer aided design and simulation resources.

It is one thing for organizations to put a set of rules down based on “Intended purpose” “common knowledge” and “this is the way we have always interpreted it before”. It is another issue when after spending a butt load of money getting a bunch of cars in the hands of racers only to find that the game gets changed after the fact based on a status quo being upset.

The bodywork on these cars is designed to induce downforce, or at least it should be, as long as those components are strongly attached to the car as the book defines.
Jack Roush commented that a champion is always in search of successful implementation of advantage based on interpretation of the regulations. Every racer should be always in search of the edge while the governing body should create regulations that are clear and concise as practical on order to eliminate potential issues with false interpretations. Even though this is hobby racing, people are spending a ton of cash and they are racing these more technical classes because they want to tinker as well as drive. Otherwise, we should all play rent-a-ride Spec racer game.
This and other issues need to be brought to the table so all of us do not have to rely on BS definitions like “INTENT OF THESE RULES”.

Another one

“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.”

What the hell is a diffuser used for if not ground effect???????? This entire phrase is a complete monkey F***.

And everyone out the is screaming for companies to manufacture new race cars ??????????
As the racers that have to live with these rules, I think it is in your best interest to get them cleaned up. We don't care if airfoil arms, "streamline tubing" arms, deviated undertrays, diffucers or any other thing is allowed or dissallowed, it is our interest to be able to produce and market a product that does not become disallowed because "INTENT" does not equal what is "Written". "INTENT" is a mind reader game that we cannot afford to play, especially with $5.00 per gallon gas and bread costing $4.00 per loaf.

[R. Pare]

Stan:

I agree that what we all want is language that is as simple as possible, BUT, it has to be just complex enough (or more correctly, cleverly simple enough) to not have the interpretation drift over the years as the personnel doing the interpretation change. WE know what we want to see and not see, but in too many cases, the written word no longer matches the intent.

In the case of a-arms, the desire is obviously to prevent significant amounts of downforce being produced by the arms. In my opinion, the only language that make sense is to NOT use the term "airfoil", simply because of the now-mandatory-to-use definition given in the Glossary.

Before the Glossary was made official, the interpretation problem was pretty much a non-issue, because everyone understood that "airfoil" meant a non-symmetrical, wing-like shaping. With the advent of the Glossary definition that it had to be producing a vertical force becoming official, that understanding now means diddly squat - the DB1 tail is probably no longer legal to use on newer FFs, as an example.

There are a host of examples of now-unclear language like this all over the GCR, and I've really only paid attention to the sections concerning FV, FF, FC,and now FB. I, and others, have written and talked about many of these discrepancies over many, many years, and have even gone so far as to totally rewrite the FF and FC rules twice (and submitted them to the BoD and CRB), with ZERO action taken to date. You would think that the members of the CRB would take it upon themselves to get this stuff cleared up, but instead it seems to take and act of god to get them to even look at it.

Is it time to get out the 2x4's to get your attention?

[Wren]

Here is the beef, what is going to happen when someone builds a fully webbed symmetrical streamlined shaped arm?

Then they will have spent a shocking amount of time and money for something of dubious advantage.

If it's good enough, it will just raise the bar for others to reach.

specially if this is a car constructed new with all modern technology and computer aided design and simulation resources.

I would say that would put it on a level playing field with the rest of the cars. Do you think Dustin Wright drew those CFD images by hand?

And everyone out the is screaming for companies to manufacture new race cars ??????????

Really, I don't think anyone is screaming for new cars. It's a very, very limited market. There aren't a bunch of people out there sitting on $40-60k waiting for something better to come along than a VD/Piper/Stohr/Citation/Phoenix/etc.

[TKemp]

So you are in favor of ambiguous regulations?

Please direct me to information concerning the new Stohr and Phoenix Formula Ford and Formula Continental cars. I am interested in seeing them.

[Wren]

So you are in favor of ambiguous regulations?

No, but this is hardly a serious issue, and I am in favor of effective use of the volunteer's time.

After 30 years in the GCR, with no problems, it's not the low hanging fruit for rule improvement.

I'm not even aware of anyone offering non-symmetric tubing, although someone with superior google skills might be able to turn some up. I think you are describing a fabricated arm, which might possibly work.

No one is winning races in SCCA on their suspension arm downforce.

Please direct me to information concerning the new Stohr and Phoenix Formula Ford and Formula Continental cars. I am interested in seeing them.

Obviously they don't, but they are still offering cars for SCCA formula racing.

[TKemp]

I think you are missing the point so I will be as clear as possible.

If a customer is disqualified for using a car that based on a rule that is written ambiguous but is ruled on based on "INTENT". This is a problem. As stated before, we don't care if arms have airfoil tubes or not, we care about a customer being upset with us due to a protest brought about and ruled upon based on "intent" instead of what is actually written. Quite frankly, I really question any net gain from streamlined arms at all if everything else on the car is not optimized.

If a device works or not, is not the issue to me as much as minimizing the potential protests and disqualifications because the rules can be interpreted six ways to Sunday.

The whole FC rule governing ground effects and diffusers is a great example of this ambiguity. Your allowed to have a diffuser but ground effects are strictly forbidden. So Am I to understand that it is OK to use a diffuser but it is not allowed to actually work??????

Todd

[TKemp]

"Item 3. (FC) Effective 11/1/08: Change the third paragraph of section 9.1.1.B.1 as follows:
It is not permitted to construct any suspension member in the form of an asymmetrical airfoil or to
incorporate a spoiler in the construction of any suspension member. Symmetrical streamlining of
suspension members is permitted."

This is much better and less ambiguous . Some other folks must have identified the same issues.

Now what about the "Ground Effects" section wording?

[R. Pare]

Just as I thought - the CRB is still not capable of figuring out the wording necessary for the result they want.

The rule still allows symmetrical airfoils.

And if someone protests sloped, streamlined tube a-arms, I challenge them to prove that they are producing a vertical force as per the Glossary requirement as to what constitutes an airfoil!

If they want to clear it up once and for all, but still keep using the word "airfoil", just modify it to state that both symmetrical and asymmetrical airfoils are not allowed. Still not perfectly correct, but much better.

[TKemp]

Like adding this?:

"Mounting orientation is unrestricted"