My 2 cents worth in line below...
mayf
BWANA343@aol.com wrote:
>can withstand 40g acceleration without serious injury. It is nearly
>impossible for a Bonneville streamliner to incur a 40g impact with the course
>surface, regardless of the unplanned excursions about the salt.
Well. I have no idea about what forces a human body can sustain. One in
good shape might take a lot, but remember, most of us are old farts who
are past the prime of life and are on the downhill slide into being out
of shape. Well, some of us are, I raise my hand. I do not want to
experience 40 g's at all.
Can the salt cause a car to sustain 40g deceleration? Maybe not in a
glancing blow but a full frontal head on, yeah I'd say so. BAck in the
old days when I worked for a living, oneof the things I worked on was
shipping cask design for spent nuclear fuel. We had to drop a fully
laden cask iontoan unyeilding surface from 20 or 30 ft, I don't
remember, without leaking. A rail cask weighs 100 tons.... I kinda
figu=re that the decel is governed by the amount of deformation in coth
the surface and the impacting object. If the crumple of the frame is
sufficient then the distance for deceleration to act is lengthened and
the g forces drop significantly. Ditto for the salt surface. So can a
car develop 40 g's? Yeah maybe.
>First of all, it's the deceleration that's the problem
>Second, let's not generalize and assume a 40g impact is the fatal threshold.
I do not want to try 40 gs to see if I die... nope, no way..you can have
my place in line for that test
>The way I see it, short wheelbase cars are more likely to destabilize due
>mostly to less efficient steering as opposed to long wheelbase cars.
I don't know if efficient is the right word to use. But a small short
wheelbase car requires more corrective action on the steering wheel vs
a long car. Is that efficiency?I don't know. And while I haven't done
any math, I suspect that the polar moment is far less in a small car, so
yes, I would expect it to spin easier. The thought about pencil rolling
is intersting but I would need to think some more on that> I think the
reason for roll overs is not how long the car is, but how narrow it is.
Long cars for the salt, special construction, tend to be narrow beasts.
And in a sideways spin type movement, if a wheel catches then the force
acting through the cg and the short moment arm to the point of contact
make it problematic of a roll over. A short wide car has to lift the car
weight upward as well as go sideways to roll. I know this is all murky
because of the way I am explaining but if you dray a picture I think it
all becomes clearer.
>But a
>short car spins, while a long car tends to pencil-roll and get airborne and
>impact, albeit more parallel with the surface, but with enough inertial impact
> to
>cause serious injury, as we are tragically reminded of last year.
Any roll over in which the car and occupant get airborne then impact is
not good. If you are strapped in such that you and the car are one, that
is much, much better IMHO. The part that flops around, your head is the
really bad issue though. First the unrestrained movement can cause
severe whiplash which in itself is bad but it also lets the head build
up some velocity befor impacting secondary structure like the roll bar
or even the stiff padding. To be safe, the head should be immobilized.
So should the hands, and feet and legs...oh how we gonna drive, well we
can't, so there is risk imvolved. Best to make the cockpit as tight as
possible so there is little rattle room and hope for the best...if you
wanna do this kind of sport.
>IMHO, the ideal driver compartment would be as round as possible, both for
>strength and to better survive impact if the front and rear portions of the
>car ideally would break away. I don't envision this capsule to roll off down
>the
> Salt like a giant Hamster cage, but to slow more gradually, with subsequent
>impacts absorbed by the caging.
Round dissapates little energy. Evre see a wheel come off a race car at
speed? Sucker goes forever or it bounces really high. Best to have some
sort of energy dissapation devices like crush zones or fenders or
bendable sections of the cage. In this every car is different so no real
way to test to see if it works. Have to rely on best guess and go for
it. Don't ignore it, just use best and sound engineering principles in
the design and fab. Or if you are blessed with lots of money, a finite
element analysis with energy and impact capabilities is the ticket.
>I realize this has been gone over a million times but Turk told me to ask
>and said you'd be kinder to my thoughts than his...
>Opinions ? Comments? Flames?
>Bob, still newbie,W
Shoot, you been listening to tha bama boy again? next time tell him I
said hello...
mayf, the rednecked ignorant desert rat in Pahrump....where ever that is
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