We must all make our own decisions about the level of acceptable risk in racing. The SCCA mandates a very minimal level of protection, and I don't think it's fair to judge someone who would like to improve that.
Even with anti-intrusion bars suspension wishbones break at other points all the time, and you also have pullrods, pushrods, steering linkages, and other miscellaneous parts that can form sharp penetrating objects. In my limited exposure to formula car racing over the last three years or so I've seen at least five accidents where someone has been seriously injured by sharp objects intruding into the cockpit. I've also seen nose cones penetrate an opening between chassis bars and injure drivers.
Burky's accident looks similar. I've often looked at the aftermath of these crashes and noticed that a few inches either way could have resulted in a much more serious injury (or death).
There are two things you'd like to accomplish with an anti-intrusion panel: (1) prevent penetration of sharp objects that could impale you; (2) prevent intrusion of larger blunt objects (like a nose cone) that could bruise or crush you. The ideal anti-intrusion panel should do both.
Eight layers of five ounce Kevlar on the bodywork (or .060" aluminum) will help a little with sharp objects and is certainly better than the required 2 layers, but won't help much with blunt objects.
Last I looked, the FIA standards for anti-intrusion panels require 10 mm of Zylon (an exotic composite material with many of the characteristics of Kevlar and the strength and stiffness of carbon fiber). I believe the IRL required 10 mm of Dyneema (another ballistic fabric) at one time. F1 cars have 10 mm of Zylon on the outside of the monocoque, which itself is a pretty effective protective structure. That's roughly 8 times as much protection against sharp object penetration as .060" of aluminum or Kevlar, and about 250 times better against blunt object penetration.
Sharp object penetration resistance is very roughly proportional to panel thickness and the characteristics (tenacity) of the material. Kevlar is very good, as is Zylon and Dyneema. Carbon fiber and aluminum are much less effective.
For blunt object penetration (sounds a bit kinky, sorry
) you are relying upon the structural characteristics of the entire panel and that heavily depends on how it is mounted. If it's just "floating" against the frame, maybe held on with tie-wraps or sheet metal screws, you'll need a much stiffer panel and it will need to overlap the tubes by at least a couple inches all around. Otherwise it can be pushed into the gap quite easily. If you're allowed to bolt it to the frame (sorry, don't know the rules in FV) then that helps a lot: it both prevents the panel from buckling and prevents it from "falling" into the gap. You can either use U-bolts around the frame tubes or weld tabs or bungs to the tubes themselves.
For protecting against something like nose cone penetration, the most important characteristic is panel thickness, since that's what gives bending resistance to the panel (prevents it from buckling). To first order, that's proportional to the THIRD power of the panel thickness (so a 10 mm thick panel is 1000 times better than a 1 mm thick panel).
The ideal panel is one that possesses high stiffness, strength, and tenacity and also has very low density (we can make a thicker panel for a given amount of weight). One way to think about it is to consider an anti-intrusion panel as a catch fence. We need both the posts (which have to be strong and stiff) and the fencing itself (which should be strong and flexible and not break even if stretched a lot). Zylon actually has both of those characteristics, but it's horrendously expensive. Carbon fiber combined with Kevlar is a very good solution.
You can see (and intuitively it makes sense) that reinforced bodywork won't do much to prevent blunt object penetration.
You do have a fairly small opening: 11 x 24 inches if I read correctly. For that sized opening, and to protect against both sharp object and blunt object penetration, I would suggest something like a 4-6 mm thick composite panel (composites are VASTLY superior to metals in penetration resistance for a number of reasons I won't go into here).
For the Radon Rn.10 we used a combination of carbon fiber and Innegra (a low-density and low-cost ballistic fabric used fairly often in F1) to get a thick panel with a massive amount of penetration resistance. You could buy the materials and lay it up yourself in your garage or any of the suppliers on Apex could make you such panels.
If you need specific assistance, send me a PM. We've done a lot of analysis and testing. I'd extend that offer to anyone who is considering adding cockpit protection panels. Glad to help on design suggestions and potential suppliers. Just don't ask me whether they are legal or not.
"Intrusion panels"
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Originally Posted by fvracer27
