Frame and roll cage design

[77fmod]

Hello again,
I am wondering where the specifications for all frame designs are located... I know I have seen them before but I am not finding them in the GCR under Rules and Specifications nor in the Formula Car section.. A little help would be greatly appreciated..

All the best,

Johnny B.

[brian]

Start with appendix I on page 153 then go to the FV section on page 200 for the frame section. Make sure you understand the interplay with the body and frame so that you don't paint yourself into a corner.

[77fmod]

Thanks for the reply.. I have looked through both of those but I seem to remember there were some specs concerning the cockpit sides.. Like how many bars are required and the vertical spacing between them but I cannot find that anywhere..

More help please..

[FV80]

As far as FV is concerned, there are no specific 'side bar' requirements. There is a requirement for EITHER 6 oz. kevlar from the roll bar to the front roll bar OR - something like 6061T6 Aluminum panels (about 0.060 IIRC) attached to the closest frame member ... or something like that. The side protection rules are "weak", but they do exist. If you found that, then you found it all...
Steve, FV80

[77fmod]

Holy Crap! Okay. I thought for sure that I had read something on it once upon a time...

Thanks for your help..

JGB

[brian]

At one time there were minimum width and heighth measurements for the cockpit but they have passed on in the update rewrites. When I made my frame, I made sure that the upper rails were high enough to protect my shoulders and used the kevlar to prevent punctures. It is preferred to have all human parts inside the frame including the steering wheel so that your hands don't get run over.

[cendiv37]

As far as I can see, there have been no substantive changes in the frame requirements within the FV rules section since at least 1994. For 2008 we did change the wording of the last line of C.2

from:
Body depth at firewall, Minimum: 25"

to:
Body height at firewall (bottom of frame to top of bodywork),
minimum: 25”

Nothing about frame width anywhere that I can see unless it comes from 9.4.5 and upon a cursory reading, I don't see anything there either.

[brian]

You're right Bruce. I forgot that measurement since it's in another section. I found the measurement for side height in the frame section.

[fvracer]

9.4.5.A says in part - "On Formula cars and single seat Sports Racing cars the vertical members of the main hoop shall not be less than 15 inches apart (inside dimension) at their attachment to the chassis." This gives a minimum width of the chassis at some point along the main hoop. Some cars have tried to cheat this by defining the chassis attachment point as being a bracing point near the level of the valve covers to minimize the chassis width under the motor, but I've always thought that interpretation to be vulnerable to protest.

Doug

[hardingfv32-1]

"at their attachment to the chassis" It is not saying attachment point to the main frame rail. How would you define the main frame rail of a true space frame if it did read that way? You can attach the roll hoop anyway you want as long as it looks safe to an inspector.

Brian

[cendiv37]

Doug, you are right about the 15" minimum inside dimension at the attachment of the main hoop to the chassis. As I said, only did a cursory reading of 9.4.5.

When I did my frame modification a while ago, I read it all very carefully and Brian H. is right about what defines the chassis: it is not the lower frame rails. Still the 15" inside dimension has to be met somewhere on the main hoop however you want to define where the chassis ends and the main hoop begins.

[fvracer]

This is a little late since I've not been on the forum for a couple of weeks, but while I agree with what Brian and Cendiv37 say, I think that there is a difference between the chassis and a chassis brace. I have seen cars that used a 1", or smaller, chassis brace as the declared attachment point to the chassis to meet the 15" rule. That is where I see that there may be some vulnerability for protest. Of course there is no rule that says that anything on the chassis has bigger than 1", other than the roll hoops. It's all down to semantics and definitions and the "gray" areas in our rulebook which is what makes things so lively and fun on the forum.

Doug

[hardingfv32-1]

This is not gray. There are clear specs for the size and dimensions of the main hoop. There are specs for the forward roll hoop braces. The chassis is made up of many parts. The rules do not define the individual components of the chassis. So mounting the main hoop to something you might call a brace is acceptable by the letter of the rule. That is not to say it would not be declared unsafe, IF it is ever actually detected by tech. When challenged, it is up to you to prove your design is safe.

Brian