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.
--
Thanks,
DougF (KG4LMZ)
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