At the beginning of the month John Robinson left a posting about his former
experience sky diving. The conclusion of that post was that he never
experienced chute loads of greater than 2.7 G regardless of his terminal
velocity or the chute opening speed. I though about John's post and also
remember some analysis Mayf did after Nolan White's accident. While John
accepts there might be a "G spike", his data never showed it. John was
recalling data from a long time ago so this is not a criticism but only an
attempt to understand his experience. In fact, thank you John for sharing
the information and causing me to dig deeper.
Chute Yank and Jerk forces are not easily understood. They far exceed the
"steady-state" drag (i.e. "G" force) caused by a fully deployed chute. I
think John's posting left the impression that these destructive forces don't
exist (possibly because they weren't picked up in his data acquisition
system). For further understanding you should visit Mayf's web site
http://www.teknett.com/pwp/drmayf/parchute.htm.
I agree the math may be daunting but just look at the yank loads and then
decide about your own system. -Elon
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