List,
I am very glad people are talking about this. I have seen two high speed
chute failures.
In both cases the tow line broke where it was attached to the car. The
forces that mayf's
analysis demonstrates are beyond anything I ever imagined. When you are
starting at 300,000
pounds and add a little bit, say 10%, your adding 30,000 pounds!
Burklands car had a problem with the aerodynamic speed brake the first
time. The stress
caused some welds to crack! And Tom is an excellent engineer!
My guess is that the forces a speed break must withstand are staggering.
I would like
to know what could be done with something small which wouldn't provide
much breaking
but would mess up the aerodynamics of the back 1/2 of the car. That
might create a lot
of drag without being a major engineering design problem..??
In my opinion, the first thing I would do is to get a bag made for my
chutes. One that fits
my current system. Bags can be made in any size or shape you need by a
parachute rigger.
Sometimes the bag is a long tube called a sleeve.
According to Bob Stroud a bagged chute hits 30-50% softer than the same
chute without
a bag.
I've ordered a book on the subject and will make a comment about it
later. (delivery time 3-4 weeks)
Bryan
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