Roll hoop TOP bend Radius???

[Janko]

What is the minimum bend radius for the top of the main roll hoop?

GCR page rulebook p148 states:
The radius of bends in the roll cage
hoop (measured at centerline of tubing) shall not be less than
three (3) times the diameter of the tubing.
Alloy Steel:
Up to 1500 lbs. DIAM: 1.375 x .080wall

Can someone point me to the section where formula cars can have a smaller bend at the top of the roll hoop?

Outside to Outside of the bend minimum distance would be:
centerline Radius 4.125 * 2 = Diam 8.250" plus Tube thickness of 1.375" we end up at a hair above 9.5in for a 180deg bend.
For a 160 deg bend we will be around 9.25in which is about the width of a helmet.

From pictures of many F1000's and other formula cars, it seems that the width at the top of the roll hoop is around 7in with bodywork included.
Can someone point me to where I can find the REAL minimum bend size?

[cparsons]

I can't. Those are the specs I used when bending my tubes. Older cars could have have been homologated with different specs though. I never paid any attention to it until recently (ie F1000 build). There is an approval process for "alternate design", perhaps designers have gone that route.

[S Lathrop]

If you can find a certified engineer who will sign off on your design, SCCA will let you have anything you want.

Don't waste your time asking for logic or consistency in the enforcement or interpretation of the rules.

[Dave Harmison]

What I think has not been said is that the "alternate design" allowance is poorly written.

I am a PE (certified engineer) and I don't like some of the alternate designs that have been allowed, but the precident has been set by VD with their bolt-on roll hoop.

I would never sign it off, but it is the standard now. I think it seriously overlooks the purpose of a roll hoop, but you get what you get. I could design some real junk that would pass under the "alternate design" but I would never race it.

And no, I'm not going to get into a long discussion of roll hoop design. Too much liability.

[S Lathrop]

Dave's statement is correct.

I would add that the rules imply a certain minimum frontal area that the roll bar structure will have. The alternative structure rule has been used to circumvent that requirement. Thus anyone who follows the GCR is at a disadvantage.

At Elkhart this will be an issue.

I also think that we should do a rethink on the roll bars. In particular I think that the Ralt RT41 roll bar, which does not meet SCCA rules and has to be replaced when the car is homologated for a different class, is possibly a better approach to roll bar structures. In short the Ralt roll bar has a crush structure above a much more rigid base. The base structure is about even with the driver's head and the crush structure is well above the driver's helmet.

As I mentioned earlier, I have had an SCCA roll hoop sheer off at the point where the braces attach to the main hoop. In that particular car the hoop was braced forward and aft at the same point. That accident involved a FV but there are a lot of cars with a similar design that weigh more and go way faster using just that design.

[Herman Pahls]

I recently purchased an 07 Phoenix F-1000.
I have read many of the older posts to update myself with the class.
Coming from the off road world( full halo cages) I feel very exposed just sitting in the chassis which appears to have a very similar roll hoop design as the other formula cars.
The previous post refered to a Formula V hoop breaking off at the fore and aft bracing point.
Would roll hoops have greater intergrity if the bracing attached higher to reduce the cantilever?
Do Formula car roll hoops sacrafice safety to reduce drag and improve esthetics?
Are we playing playing Russian Roulette in a roll over especially if we end up tangled with another car, wall or railing.
Sorry for the hard questions but I want to know if others question as I do.
Thanks for your consideration
Herman Pahls

[nulrich]

A roll hoop design that really meets the alternate design criteria (FIA based) in the GCR is quite a bit stronger than the suggested (minimum) SCCA design, on the order of three or four times stronger.

Not all roll hoop designs homologated under the "alternate design" section of the GCR actually meet the FIA criteria. I won't say anything more about that.

Any roll hoop design that has a single main roll hoop braced ~6 inches below the top (as allowed in the GCR) will not meet the FIA criteria, the minimum allowed tubing size is not strong enough in bending to resist the required fore/aft loads.

Personally, I wouldn't feel comfortable in a formula car that didn't have a double main roll hoop design (like the Citation or our new car) or one where the main roll hoop was braced at or near the top. But I might be more risk averse than others.

The minimum required bend radius is likely to prevent wrinkling or extreme thinning of the roll hoop material that can happen at smaller radii. Not really an issue with modern bending equipment, at least down to 2.25 to 2.5 CLR.

There are a lot of scary designs out there.

Nathan

[Jnovak]

This is a great discussion. I have built many cars that have been built to the SCCA specification but with the forward facing bracing a bit higher (.5", 5.5" from top) . I also use 1.25" x .083" tube for the forward facing braces.

I expected that the SCCA spec was very similar to the FIA spec. However now that I hear that the FIA spec is much stronger than the SCCA spec I will look it up.

Is it possible for those who have info on the FIA spec to post some pics of viable or existing designs that meet the FIA spec?

Thanks ... Jay Novak

[RussMcB]

(deleted)

[nulrich]

Here are some photos I just found. The first is a Citation with the Fit engine, I found it here under a message Mike Eakin posted (I assume he won't mind if I copy it here). The second is a Mygale. The third is a CAD image of the Rn.10 main roll hoop area (I can post some actual photos later, but it isn't accessible right now).

Not sure about the Citation, but I assume it was homologated under the "alternate design" section, which would mean it meets the FIA standard in the GCR.

The Mygale was probably certified in France to FIA standards, but I don't know for sure.

The Rn.10 meets F3 rollover standards, which are about 30% higher than the FIA standard in the "alternate design" provision of the GCR.

All three of these look pretty reasonable to me, and I think anyone can see they are better braced against fore/aft loads. I'm assuming the FV failure was due to that kind of load.

Nathan

[formulasuper]

I've always thought the forward facing brace bars attached near the top of the rollbar would give the driver's head better protection from an upside down, forward sliding scenario. Without them you are fully exposed to whatever comes. Also, maybe a little better for a deal like happen in the previous Indycar race with Moraes landing on top of Marco Andretti.

[Stan Clayton]

I recently purchased an 07 Phoenix F-1000. I have read many of the older posts to update myself with the class. Coming from the off road world( full halo cages) I feel very exposed just sitting in the chassis which appears to have a very similar roll hoop design as the other formula cars.

The standards laid out in the GCR are minimums, Herman, and one is free to exceed them in any and all regards. FWIW, there was a competitor from the mid-West who raced in Formula Atlantics for many years, and competed at the Runoffs until ~2005 with a complete double-hoop, sprint-car style roll cage. It was perfectly legal even if it incurred a performance disadvantage.

The previous post refered to a Formula V hoop breaking off at the fore and aft bracing point. Would roll hoops have greater intergrity if the bracing attached higher to reduce the cantilever?

The short answer is..."of course!", especially if the AFT bracing is closer to the top of the roll bar. Cars are designed to travel in a forward direction, and while freak circumstances can get it going backwards, the vast majority of incidents, and hence safety risk, occur with the car moving in the forward direction (ignoring rollovers). In any case, aft braces running to the top of the bar will aid in forward strength, as well, and if they are designed to be removable to aid in engine changes, then I don't see any real downside to them.

Do Formula car roll hoops sacrafice safety to reduce drag and improve esthetics?

Certainly the former, and probably the latter.

Are we playing playing Russian Roulette in a roll over especially if we end up tangled with another car, wall or railing. Sorry for the hard questions but I want to know if others question as I do. Thanks for your consideration. Herman Pahls

Let's cut to the chase...you are playing Russian Roulette with your life and limb every time you get in your race car (or dune buggy, homebuilt airplane, etc.). To quote the very first paragraph in the GCR:

The General Competition Rules of the Sports Car Club of America are
intended to assist in the orderly conduct of race events. They are in no
way a guarantee against injury or death to participants, spectators, or
others. No express or implied warranties of safety or fitness for a particular
purpose are intended or shall result from publication of or compliance
with these rules.

That said, there is more than a little FUD (Fear, Uncertainty and Doubt) interspersed in the comments above, not to mention some naked self-interest. Are the rules perfect? No. Can they be improved? Almost certainly. Have they served the members well? Arguably, yes, since IMO they largely balance the real-world affordability and safety needs of the members. Historically, SCCA has experienced an average of less than 2 fatalities per year from about 120,000 "competition events" per year (40,000 national and regional road racing entries averaging 3 on-track sessions per event). In terms of fatalities, that makes our events 99.998+ % safe.

But make no mistake, the user of the racing car assumes the final responsibility for ascertaining the appropriate level of safety structures built into the car. If for whatever reason the driver feels not capable of making that determination then it is incumbent upon the him or her to find/hire someone who can. Just bear in mind that nobody is G_d, and that no arbitrary level of safety cannot be overcome with enough velocity and mass.

Speaking of velocity and mass, the minimum safety standards mandated by SCCA (and FIA, etc.) are just arbitrary numbers, and are recognized as such by the insurance and legal communities. For many years they were based on SCCA's accumulated record and experience, and the FIA standards of 7.5G vertical, 5.5G longitudinal and 1.5G lateral. The FIA's standards have been raised somewhat in recent years, but they still represent sustaining minimal damage from hitting a solid object at about 30 mph. Since formula cars commonly average 100 mph on road circuits, it stands to reason that it is pretty easy to exceed the design parameters of your car's safety structures.

In the final analysis there are some common sense things anyone can do to minimize the risk: ensure there is a robust front impact attenuator installed; install better-than-minimum side anti-intrusion, and build a double-hoop rear bar with better-than-required bracing. Those simple measures will address the vast majority of real-world risk areas.

[nulrich]

The short answer is..."of course!", especially if the AFT bracing is closer to the top of the roll bar. Cars are designed to travel in a forward direction, and while freak circumstances can get it going backwards, the vast majority of incidents, and hence safety risk, occur with the car moving in the forward direction (ignoring rollovers). In any case, aft braces running to the top of the bar will aid in forward strength, as well, and if they are designed to be removable to aid in engine changes, then I don't see any real downside to them.

Uh, Stan...you realize that tubes are generally stronger in tension than compression, right?

That said, there is more than a little FUD (Fear, Uncertainty and Doubt) interspersed in the comments above, not to mention some naked self-interest.

I'm a little confused if you're referring to my post. I don't have any financial interest in Citation or Mygale, so why is it in my "naked self-interest" to acknowledge the benefits of their design as well as our own? Or disclose the details of our roll structure? Besides the fact this is in the FB forum, and we don't even make a FB car!

Are the rules perfect? No. Can they be improved? Almost certainly.

The SCCA safety rules, especially in regards to rollover structures and impact attenuation, are years behind the rest of the world. Some of us feel it's our responsibility as designers to improve the safety of these cars whether required by the SCCA or not. That requires substantial additional design effort, incurs increased manufacturing cost, and can even impact performance, but I think it's the right thing to do.

You are welcome to disagree, but don't disparage my motives.

If I'm mistaken, and you were not accusing me of "naked self-interest," then I apologize.

Nathan

[Stan Clayton]

Uh, Stan...you realize that tubes are generally stronger in tension than compression, right?

You may have missed my point, which was that back braces are far more effective when run to the top of the bar than when they leave the top 6" cantilevered out the top. Running braces to the top of the bar on the front side over the driver's head is often not practical from a driver extraction perspective (and is prohibited IIRC in FIA formula designs).

The SCCA safety rules, especially in regards to rollover structures and impact attenuation, are years behind the rest of the world.

I disagree. SCCA's minimum safety standards are literally identical to (i.e., borrowed directly from) those of the international racing community in many respects; e.g., FIA specs for fuel cells, non-metallic composite chassis, personal safety gear, etc. They include FIA standards in others: e.g., personal safety gear, impact attunuators, etc. And they exceed FIA specs in at least one area that readily comes to mind: inter-tubular anti-intrusion specs for tube-frame chassis.

In at least one area, the world (read...FIA) was grossly deficient compared to SCCA in that they had no standard whatsoever for tube frame formula chassis until just a few years ago. FIA appeared to think that if they ignored tube frame chassis and kept insisting that the word abandon them in favor of composite tubs that they would disappear. It was only after years of pressure from member organizations that FIA finally agreed to apply F3 quasi-static and dynamic testing to tube frame chassis. Even then the job is only half done, since the latest set of rules for tube frames I've seen do not incorporate mandatory bottom shear panels nor side anti-intrusion, as required by SCCA.

Some of us feel it's our responsibility as designers to improve the safety of these cars whether required by the SCCA or not. That requires substantial additional design effort, incurs increased manufacturing cost, and can even impact performance, but I think it's the right thing to do.

Good! I am pleased that you feel that way and back it up with your actions. SCCA is a participant-member organization, though, that IMO needs to ensure that there is always an avenue for the budget-conscious member to build his or her own race car in their own garage without the need for expensive formal testing, which is where a clear set of dimensional chassis construction standards comes in.

In Europe and much of the rest of the world the FIA require certified materials, certified welding, certified designs and certified crash testing at certified facilities before one can take even the lowest powered junior formula car on track. While one can argue that this makes sense under some circumstances, I feel that requiring exclusively that approach does not serve our members needs nor SCCA's long term interests.

As I noted earlier, SCCA's roll structure standards could possibly use updating, but IMO they are neither "silly" nor woefully out-of-date.

YMMV...

[martyb]

Uh, Stan...you realize that tubes are generally stronger in tension than compression, right?

True enough for the tube, but not necessarily true for the weld that is attaching it, or for the part of the tube that was welded on for the attachment.

Marty

[S Lathrop]

Herman:

I don't know if it is one of my FV cars that you refer to having a roll bar failure or not. The top of the roll bar sheered off a Citation FV at the entrance to corner 5 at Elkhart Lake. That happened nearly 20 years ago. The bracing and all support structures remained in their original position and provided adequate safety to the driver. The roll bar was braced forward and rearward at the same height on the roll bar. The resultant stresses on the bar caused a total failure of the tubing at the joint. After that we added box gussets ( made from curved tubing) to the roll bars.

We did use the same material on a FF (87 Citation FF) that took a really large impact on the roll bar. The roll hoop was deformed at the impact point and we had to replace the entire engine bay because of the forces. That car is still racing today.

The original 94 Citation (FF and FC) roll bars did not require special homologation procedures because I was able to demonstrate that I could build the structure the met the exact letter of the GCR if I used 1" dia. braces 6" from the top per the GCR or I could make the brace tubing a double hoop. The CRB at the time accepted my substitute design because it was obviously stronger. In 2006 the then management of SCCA required that I get an engineers certification (not an insignificant cost because of the firm I used). The results were that the design on the current Citation can be cycled almost infinitely at the GCR loads and not yield, leave alone fail.

Scott Rubenzer's car has been on its roll bar once and Dave Weitzenhof's twice.

The worst test of one of my roll bars was in 1979 on the oval at Texas World pro Super Vee race when one of my cars went on the roll bar and slid to a stop just before it ground completely through the top of the bar. That car had roll bars built to the current GCR specifications. The rules had been proposed and were to go ineffect in 1984.

Though it is not SCCA legal, I think a roll bar structure similar to that on the Ralt R41 FA should be considered. That Structure allows for a progressive collapse with a big increase in the strength of the structure even with the drivers head. The problem with the current GCR specifications is that the failure point or mode for most roll bars is complete and somewhere below the driver's neck. Example: my car where the point is around the area of the engine block or a VD which might be the mounting point on the frame.

When we modeled my car we did the entire structure from the belly pan to the top of the hoops. We did not explore how much force it would take to yield and collaps the structure.

[nulrich]

As I noted earlier, SCCA's roll structure standards could possibly use updating, but IMO they are neither "silly" nor woefully out-of-date.

I am not familiar with the history, but it sounds like you have been involved with this issue for some time. I can only address the current standards.

The FIA regulates tube frame (what they call "cars with space frame technology") in Appendix J, Article 277. The 2010 version is quite comprehensive, and covers, as a sampling:

- Roll hoop minimum strength to withstand a static load of 60 kN vertically, 45 kN longitudinally, and 12 kN laterally with less than 50 mm of deflection. That corresponds to about 11x, 8x, and 2.2x a car weight of 1220 lbs like an FC car, as opposed to the 7.5/5.5/1.5x required in the GCR "alternate design" criteria. A roll hoop built to the general guidelines in the GCR can fail at forces as low as 2x longitudinally, for reference.

- Front impact attentuation structure that can decelerate a 1220 pound car from about 27 mph at no more than 25g. The aluminum "crush box" in most FC cars doesn't even come close, it has less than 10% the attenuation capability to meet this standard in our preliminary tests.

- Three separate side load tests on the space frame, including the fuel cell area.

- A cockpit side panel resistant to penetration...and it's a massive 10 mm thick panel, not 10 oz of Kevlar (even our panels aren't quite 10 mm thick everywhere).

- Penetration resistance for front suspension components.

- Rear impact attenuation structures passing a test similar to the front but with a lower speed (~22 mph).

It's a comprehensive document, and I can't find any area where SCCA has stricter safety standards (certainly not anti-intrusion). I'm not advocating that SCCA adopt such stringent regulations, but I agree with you that some updating is necessary. How much is the debate, since the last thing anyone wants is to obsolete all the older cars.

We have chosen to meet as many of the FIA 2010 standards as practicable, although full compliance would put us in violation of the GCR (ironic).

Nathan

[Stan Clayton]

I am not familiar with the history, but it sounds like you have been involved with this issue for some time. I can only address the current standards.

Yes...too long, some might argue.

The FIA regulates tube frame (what they call "cars with space frame technology") in Appendix J, Article 277. The 2010 version is quite comprehensive, and covers, as a sampling:

- A cockpit side panel resistant to penetration...and it's a massive 10 mm thick panel, not 10 oz of Kevlar (even our panels aren't quite 10 mm thick everywhere).

Good to see that 277 has been updated to include anti-intrusion.

Now, if they would just get with the floor pan.

It's a comprehensive document, and I can't find any area where SCCA has stricter safety standards (certainly not anti-intrusion). I'm not advocating that SCCA adopt such stringent regulations, but I agree with you that some updating is necessary. How much is the debate, since the last thing anyone wants is to obsolete all the older cars.

We have chosen to meet as many of the FIA 2010 standards as practicable, although full compliance would put us in violation of the GCR (ironic).

Nathan

You and I are probably closer in these regards than you may think, Nathan. FWIW, as far as I know FIA do not require updating of older cars. When new specs come out, all new cars covered by that spec must meet it, but older models can soldier on under their original homologation certificate. This is also the general approach taken by SCCA, with some exceptions. Outlawing of older cars by rules creep is to be strenuously avoided.

By the way, which FIA spec would put your car in violation of the GCR?

[nulrich]

You and I are probably closer in these regards than you may think, Nathan.

That's likely, I think we both have the same basic interest in the health of SCCA formula car racing, just different viewpoints at times.

By the way, which FIA spec would put your car in violation of the GCR?

The FIA requirements for side impact protection require composite panels that are mounted with centers closer than six inches, which violates the FF/FC rules. We simply mounted ours on 6+ inch centers which is almost as good. We tried to make up for it in other ways, though.

Nathan

[Stan Clayton]

The FIA requirements for side impact protection require composite panels that are mounted with centers closer than six inches, which violates the FF/FC rules. We simply mounted ours on 6+ inch centers which is almost as good.

According to my copy of 277, FIA's spec is way larger than 6" as a practical matter. Are you looking at something else?

The specification of this panel is: DYOLEN of a minimum thickness
of 10 mm which must be solidly attached to the main structure of
tubular frame in the requested area in the following way: at its
extreme corners, the upper, lower, forward and rearward edge
halfway between the corners, and halfway along each diagonal
tube.

Note: Dyolen is better known in the US as zylon.

[nulrich]

According to my copy of 277, FIA's spec is way larger than 6" as a practical matter. Are you looking at something else?

Note: Dyolen is better known in the US as zylon.

If you look at the details, they require you to use 8 mm U-bolts, which means you effectively have mounting points that are the diameter of the tube + 8 mm apart at every mounting position.

Instead, we weld bungs into the frame every 6+ inches and through bolt the panels using a custom fastener I designed.

Also, we don't use Zylon, we use carbon fiber in combination with a newer fiber used a lot in F1 now. We have developed a panel design that we believe is superior to the typical Kevlar/Zylon/Dyneema approach. And it's a LOT cheaper, which we think is consistent with the class philosophy.

Of course, the GCR still requires that we reinforce our glass bodywork with two layers of Kevlar!

Nathan

[Herman Pahls]

S Lathrop
You posted 3-31-09 about a FV roll hoop failure and that failure got my attention.
I currently race a full halo roll cage homebuilt sports racer. Not competitive but my start into racing.
I recently purchased a F-1000 and hope to have on track mid summer.
My concern was the strength of the cantilevered roll hoop above the braces.
You mentioned that the driver in the FV roll hoop failure turned out OK.
The rules state that the roll hoop needs to be so far above drivers helmet and that the bracing needs to be within 6 inches of the top of hoop and at least a minimum angle.
My inquiring mind asks what good is a roll hoop that is 2 inches above the helmet and the bracing is 4 inches below the helmet and the 6 inch cantilever will fracture or bend at or near the bracing?
Nathan gave a link to a Citation picture that shows a double hoop with plating between the hoops. That design looks like it would take much more abuse than the typical single hoop.
I realize that a double hoop would weigh more and possible not be as esthetic as designers would like.
Also the GCRs are minimums and minimums can be exceeded.
Thanks Herman Pahls

[R. Pare]

.... as far as I know FIA do not require updating of older cars. When new specs come out, all new cars covered by that spec must meet it, but older models can soldier on under their original homologation certificate. This is also the general approach taken by SCCA, with some exceptions. Outlawing of older cars by rules creep is to be strenuously avoided.

Unless I am mis-reading the intent of your wording, cars in these SCCA classes are required to update themselves to whatever the current specs are for that class. Where it can confuse some is that Club Fords only need to meet the pre-'86 rules (plus whatever the requirements are in the general requirements sections of the GCR), but do not need to meet any additional requirements that are stated only in the '86 FF rules. A good example was the requirement in the early half of the '90's for fuel cell enclosures and dash hoops - even the CF's had to make the change in order to stay legal.


Nathan: You will not need to add kevlar to the inside of the cockpit side panels if you add it to the bolted-on panels. Both methods are allowed.

[Matt Conrad]

Herman,

Obviously our frame (no pun intended) of reference comes from where we've been before and since I've only driven open-cockpit cars I always felt very secure in the F1K07 that Dustin designed. Since you've driven cars with a more substantial roll cage you may feel a bit "naked" when you are in the car. That's natural, but it doesn't mean the car isn't safe.

I have a few points...

The Phoenix was designed to meet the GCR specs and was not an "Alternate Design" as was the Maloy chassis which preceeded it. From memory, I believe we did use a thicker tubing in the hoop (to also help prevent the possibility of the tubing buckling during bending) and in the support structure, but whatever we did was carefully engineered by Dustin. I'm certain he spent many days and nights on FEA analysis on his design. We didn't merely use the thoery that "thicker is better" because just making one area stronger will move stresses to weaker areas and could cause even more problems. All Phoenix Chassis' are TIG welded and only professional welders are used to construct them.

Someone sort of touched on this before, but it needs to be repeated...

You can never plan for every possible scenario in a race car. People have been killed and injured in crashes in every possible type of race car with full cages, no cages, carbon tubs, aluminum tubs, etc, etc. Even extra roll hoop structure would probably have not saved Senna or kept the errant spring from smashing into Felipe Massa's head.

I would be personally very comfortable driving the Phoenix F1K07 just as it is, but if you are going to make changes to the roll hoop I'd suggest consulting with Dustin first. I know he's extremely busy, but I'm certain he'd find some time to assist.

Matt Conrad

[nulrich]

The Phoenix was designed to meet the GCR specs and was not an "Alternate Design" as was the Maloy chassis which preceeded it. From memory, I believe we did use a thicker tubing in the hoop (to also help prevent the possibility of the tubing buckling) and in the support structure, but whatever we did was carefully engineered by Dustin. I'm certain he spent many days and nights on FEA analysis on his design. We didn't merely use the thoery that "thicker is better" because just making one area stronger will move stresses to weaker areas and could cause even more problems. All Phoenix Chassis' are TIG welded and only professional welders are used to construct them.

Just to be clear, it is not my intent to criticize all roll hoops built to the GCR specs. It is possible to build a very safe roll structure following those guidelines, just as it is possible to build a marginal roll hoop. It's hard to see roll structure in many FB cars, so I can't make a specific comment, but I'm sure Dustin did a good job.

Nathan: You will not need to add kevlar to the inside of the cockpit side panels if you add it to the bolted-on panels. Both methods are allowed.

I agree that's a sensible interpretation, but I've been told otherwise by the SCCA. Here's the applicable language:

D.7.b. The area between the upper and lower main frame tubes from the front roll hoop bulkhead to the rear roll hoop bulkhead shall be protected by one of the following methods to prevent the intrusion of objects into the cockpit.
1. Panel(s), minimum of either .060 inch heat treated aluminum (6061-T6 or equivalent) or 18 gauge steel, attached to the outside of the main frame tubes. No other material types will be allowed for these panels.
2. Reinforced body - at minimum, consisting of two layers of 5 ounce, bi-directional, laminated Kevlar material incorporated into the body which shall be securely fastened to the frame. (5 layers are highly recommended.)
For either method, fasteners shall be no closer than 6 inch centers (no stress-bearing panels). The material used for the chassis braces in this area shall be at least equivalent to the roll hoop brace material.

I was told that because our cockpit side panels are not aluminum or steel, they can't be considered the required panels under this section and we would need to either: (a) add additional aluminum or steel panels; or (b) reinforce the body with two 5 ounce layers of Kevlar.

I would think, especially given the latest FIA regulations requiring Zylon panels, this might be an area that should be updated.

Nathan

[R. Pare]

You are correct - I forgot that it read as alu only if attached to the frame.

[Herman Pahls]

Matt: You are absolutely correct re: the naked feeling I get just sitting in a formula car or in modern sports racers..
I have rolled several times in off road cars in the sand or dirt without a second thought.
If have not gotten use to the idea in a formula car with the minimalist roll over structure.
I want to thank the forum for informing this formula car newbie.
Herman

[S Lathrop]

Herman;

You asked a question that I did not answer. In that FV that had the roll bar failure, the hoop was 3 to 5 inches above the drivers head.

The important thing about the failure to me was it pointed out a short coming in the GCR rules that has never been addressed. In fact I referenced the issue by referring to the Ralt RT41 roll bar structure.

In short, we need to look at incorporating a crushable structure in the roll bar structure. The hoop does a reasonable job but as my car proves it can fail and leave the driver vulnerable. My current design and that of all the pictures that Nathan posted are for structures that will not fail. My structure is probably strong enough to with stand an impact that the driver could not survive. Better would be a structure that could absorb the impact forces to reduce the forces imparted to the driver.

The GCR is written to discourage integrated structures incorporated into the roll bars. The Claytons ran into this when they had to remove the Ralt roll bar when they changed classes with their Ralt. I know of 2 SCCA FA fatalities that involved roll bars that failed at the mounting points, mounting points that were so low that the driver was unprotected.

[quartzracer]

Steve, When did the Clayton's have to change roll bars? I see that Rennie ran as a CSR and converted back to FA. However I think both times they used their inovative Claton Spike (or whatecer you guys call it)

Eric

[S Lathrop]

Steve, When did the Clayton's have to change roll bars? I see that Rennie ran as a CSR and converted back to FA. However I think both times they used their inovative Claton Spike (or whatecer you guys call it)

Eric

If you change class for a chassis you have to get new homologation papers. As I understand, they had to have a new roll bar structure when the converted to CSR. The oroginal Ralt roll bar was approved for FA only.

[Stan Clayton]

Steve is correct. We had to update the Ralt's main roll "hoop" to comply with current GCR wording when we wanted to add CSR to our FA homologation. The "spike" passes all specs called out in the GCR...tubing sizes, bend radii, FEA study, etc. The original hoop is probably just as strong (I have a copy of the original FEA study done on it), but it is a "birdcage" design of smaller diameter tubing, rather than the large-diameter tubing called out in the GCR.