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Hans Device

To: "land-speed submit" <land-speed@autox.team.net>
Subject: Hans Device
From: "3 liter" <saltfever@comcast.net>
Date: Wed, 14 Jun 2006 00:55:23 -0700
Dick, think of your head as a 15-20 lb mass with its CG just about center.
When you stop abruptly that mass pivots about the CG or slams forward.
Either your chin or the helmet front hits your sternum with enough force to
lift the base of your skull in back. That upward force on your brain-stem or
spinal column can cause a separation. The force at the base of your skull
can be greater than 20lb x 25-40 Gs because of leverage caused by the chin
hitting the sternum.  When the helmet slams forward the Hans reacts this
force and distributes it over a much broader area than the sternum. The Hans
allows you to escape the car. The seat scenario you suggest doesn't offer
protection in a frontal assault (i.e. hitting a wall) and tying the helmet
to the seat back might prevent egress. Even though LSR is straight-line
(hopefully) a frontal impact is still a great danger in any tumbling
vehicle.  -Elon

From: Dick J

It seems to me that since head mobility is not an issue in an LSR car (no
need to look around), then a Hans device is a stopgap measure to something
that could just be built into the car.  Why not just have a seat and head
support that does the job without a snap in restraint attached to the
helmet?  If you are totally supported, back and sides, by a well fitting
seat and headrest which is incapsuled in a good cage, then there should be
no need for a Hans device.




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