If you watch the videos of Indy car crashes in the 60's there was no frame deformity, but the driver died anyway. The frames were so strong that all of the crash forces were transferred to the driver.
Highway crashes were the same thing. The crash forces were transferred to the driver.
In both cases deformable structures and decelerable padding or air bags were designed to allow the forces of deceleration to be transferred away from the driver.
Making the streamliner frame is the same challenge. I can't help but laugh when I picture the Buddfab 50cc liner with an 1 5/8 frame.
Both Indycar and NTSA have money to study the situation. Indycar designs have to be crash tested and all of the cars have G force data recorders.
Kent is mostly correct about his description of the crash attitudes for streamliners. At least we don't have walls to hit. The angle of hardest impact can't be determined, so you have to design for any angle of impact. I think SCTA has done a reasonable job in recommending roll cage and safety requirements.
I don't know how these were determined. I suspect that other forms of racing were used as a model. I really doubt SCTA spent any money in engineering studies. Correct me if I am wrong.
The person responsible for the safety of the driver is the person that designs the streamliner. Finite Element Analysis (FEA) of the strength of the structure and crash scenario simulations should be computed.
The result is not only the strength calculations of the frame, but the G force loading on the driver.
Ok, raise your hand if you have that kind of money.
Looking at the VERY suspect frames that have shown up over the years with crappy welding and you name it, it is very responsible that SCTA has made the rules that they have.
I'm very much with Kent and others in my disrespect for rule making that has gone on in the SCTA. Mike Manghelli has made statements to me that were, well, unbelievable.
You still have to work within the system if you want to run SCTA events. Keep it in mind that no one is getting a paycheck, and the spectator dollars are zero. Everything we do, we get to pay for it.
This rule was not in the best interests of the safety of the vehicle. Engineering opinions have been posted on this thread that make it clear to the non-engineer that a 60's Indycar frame would be the result.
Ok, so what is the best path to recommend here? Low buck, possibly dangerous, self designed vehicles? High buck engineered solutions that rule out 99% of us? Or SCTA trying to find a solution that will cover every situation through rule making.