Butch said,
So would any of you have an idea of the max
g's that autox induces. From my personal experience, it should be less than
a
roller coaster ride.
I've run with an accelerometer and got numbers about where one would expect.
It hasn't been actually calibrated but has fudge factors you can apply for
expected body lean, etc. At Marina last 6/1, a high-grip venue, on sticky but
not R tires, the readings showed a maximum G level of a little over 1.05.
This was cornering, or braking transition into corners. It was sustained for
at least a couple of seconds. The hottest cars cornering wise would probably
be the Mods, which might well max out over 1.3 G as they're actually getting
to speeds where downforce comes into play and have wings to manage it. And if
you're using your brakes properly you'll also generate peak (backwards) values
in the 1.0 G range. At GGF or Oakland these values would probably drop more
than 10%.
Engineering-wise the peak load on the neck will vary with position. Most car
drivers tend to lean their heads into a corner, which takes some of the side
loads and makes them into downwards load at the spine. Muscles cannot react
to compressive loads, only tension, so any side load on the neck will result
in a downward load on the spine as the opposing neck muscles tighten to resist
the moment. A second factor is that, racing, you're wearing a helmet, which
substantially increases the load on the neck due to the added weight.
Finally, the "instantaneous" peak loads will be higher. My meter has only a
0.1 second update, so shorter events won't show up. In a venue like
Candlestick that is very bumpy there will be shock loads - I remember saying
"Oooof!" when approaching the finish line there last time as the car got air
and wheelspin, then slammed down, after a large bump.
You might want to ask whether a helmet collar would help your situation. I
believe that racers in higher performance cars use these to assist with
resisting side loads. Because of the way the leverage is applied, these could
actually result in lifting forces on the spine / neck in corners. Finally
there are the various neck travel limiting devices increasingly used such as
the HANS. These transfer some of the loads to a hard support that is strapped
to the helmet.
Comparing to roller coasters, some of them have some pretty high peak G loads.
But as researchers point out,
http://www.uphs.upenn.edu/news/News_Releases/oct02/GForce.html for instance
from University of Pennsylvania, you can get 8 - 10 peak G's for a very short
time by "plopping down onto the couch". One article claims that they keep the
G-forces in roller coaster design under 4.0.
http://search.csmonitor.com/durable/1998/08/11/p8s1.htm
I hope that this is some value.
PaulT
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