Steve:
Myself and others have offered numerous rules clarifications in the past year and a half. As far as I know, none have been considered by the F/SRAC. I believe the current rules, last revised comprehensively in 2009, are quite clear, well written, and easily interpreted and enforced. I would suggest one change to the section on cockpit protection, which I believe would provide the guidance you'd like on cockpit protection. I base this version on the latest proposal but using realistic limitations, easily measured:
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 at least one of the following methods to prevent the intrusion of objects into the cockpit. Panels may extend to the forward most bulkhead, but must otherwise comply with these regulations.
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.
2. Reinforced body, at minimum, consisting of at least two layers of 5 ounce, bi-directional, laminated Kevlar material incorporated into the body which shall be securely fastened to the frame. (5 or more layers are highly recommended.)
3. Composite panels attached to the outside of the main frame tubes. Carbon fiber is permitted but must be used in conjunction with at least .050 inch of "anti-ballistic" type material (for example, Kevlar, Zylon, Innegra or similar materials).
For any of these methods, fasteners attaching panels to the frame shall be no closer than 6 inch centers. The material used for the chassis braces in this area shall be at least equivalent to the roll hoop brace material.
I would welcome an updated Citation design, I'm sure it would have some innovative ideas. For me, the main attraction of FF and FC is that they are not spec classes, and I like seeing a variety of cars.
Having explored a number of different designs using both composite and aluminum panels mounted to a full tube frame, I can offer some advice. Aluminum panels, mounted on six inch centers, will give the highest torsional rigidity for a given weight. Composite panels end up roughly 20% less stiff, but can be more easily shaped to the complex contours. And, of course, they provide MUCH more penetration resistance.
In any case, as I suspect you know, the area between the main roll hoop and rear suspension is generally the "softest" part of a tube frame formula car and panels can't help you there! Despite all the misinformation, the Radon chassis has about the same axle-to-axle torsional rigidity as a Citation. The originator of the six inch rule was either very lucky or very good, the number is exactly correct to provide no performance difference between stiffening with panels or stiffening with tubes.
Nathan