I think I understand at least 50% of what you wrote Ed. This is another
example of "Just because you can do something doesn't mean you should."
High alloy metals are a double edge sword. 3-4 years ago all C-133A's
were finely grounded because the wings came off of two of them. (yes "A"'s)
I fear that the "Law of Unintended Consequences" will rear it's ugly head
when these used chassis are sold to low buck racers. I hope it doesn't
take dead people to wake up the NHRA.
If I was rich, I'd like to have a carbon fiber streamliner built by
Burt Rutan's Scaled Composites. I wouldn't trust anyone else to do it.
Dream on Savage.....
Bryan
Ed Weldon wrote:
> OK, I may be pulling some sacred chains here; but IMHO these drag racers and
> their NHRA are a "ship of fools". That computer analysis of the dragster
> frame is a sad joke. Especially sad because it shows the state of their
> engineering knowledge of this complex engineering problem. Anyone with an
> exposure to a first undergraduate course in ferrous (steel) metallurgy will
> see the absolute folly in what they are doing allowing the use of a heat
> treatable alloy like 4130 for their frames. They have absolutely no
> quantifiable idea of the cyclic stresses that these chassis encounter in the
> racing environment and the variablity of steel properties in the resulting
> fatigue environment, let alone the chassis vibation modes that agravate the
> chassis loadings. Add to that the inconsistencies in welding and thermal
> stress relieving of a large structure like a chassis. Then add the
> variability in material properties as the structure passes through the range
> of low cycle fatigue (which require a far more sophisticated finite element
> stress analysis routine).
> These fools need to follow the wisdom of the SCTA and force everyone back to
> the engineering simplicity of low carbon steel. Messing with chrome moly
> frames in a sport where everyone feels compelled to push the limits even if
> they don't understand them and are hopelessly incompetant to cope with them
> is total folly. Nascar learned the hard way to "throttle back" the
> performance of their race cars to something manageable from a safety
> standpoint. It sure didn't hurt their business model in the long run. NHRA
> will have to do the same. There's a lesson in that for all of us.
> Ed Weldon
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