Another very likely analysis.
On Feb 2, 2009, at 22:13 , Doug Franklin wrote:
Joseph McAllister wrote:
What I can't fathom is why that car hit the immovable object in the
first place. It may have gotten light when it crested the rise, but
it was fully down on it's suspension shortly thereafter, and
seemingly in control. Perhaps he was trying to start a drift to
cross the bridge between the abutments and discovered he had more
traction than he could deal with, or didn't crank the wheel enough
to break loose.
After viewing it a few times, here's what I think happened.
A) He comes over the hill a little too fast for his suspension setup.
B) When he lands, he compresses the suspension all the way down to
the bump stops, and hits the stops pretty hard.
C) When the suspension bottoms out, it's "spring rate" goes from a
few hundred pounds per corner to several thousands of pounds per
corner.
D) It looks like there's still energy left when the suspension
bottoms, so it squishes the tires vertically to "burn up" the rest
of the downward energy.
E) This makes the car get a little squirrelly. Just after landing
you can see the car "squib" a bit to driver's right (viewer's left).
F) The driver makes a small correction for that movement, turning
the car slightly left. The car is really "heavy" (high normal
force) for the moment, so the small movement has a comparatively
large effect.
G) The car rebounds off the suspension and tires, and loses most of
its weight for a moment ...
H) ... unfortunately, that's the moment he's noticing the abutment
and trying to correct for it. But he doesn't have much traction
because the car is "up in the air" mid-rebound (low normal force).
I) By the time the rebound reverses and he gets significant weight
back on the tires, bang.
Joseph McAllister
[email protected]
“If I could tell the story in words, I wouldn’t need to lug a camera.”
–Lewis Hine
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