Thanks to all who responded to my question of why one of my knockoff's
tightened after racing. Your responses (1) generated some brain functions on
my part and (2) answered a question of why the knockoff threads are
directional (clockwise tighten on left side and counterclockwise tighten on
right side) and why they "unscrew" if mounted on the wrong side.
I whipped out the old and trusted Basic Motion and Accident Reconstruction
formula's from Northwestern University Traffic Institute, put my solar
calculator under the heat lamp, and went to work!
Here's what I came up with (subject to variations and adaptations based upon
unknown variables...... {check my math Lou... make sure I'm doing this
right!})
FACTS:
Ole NEWTON said that an object at rest or in constant motion will continue
to do so until acted upon by another force (in this case, acceleration or
deceleration).
My 2 earred knockoff's weigh approx. 23.3 ounces each.
The total diameter (ear to ear) of the knockoff's is 6.5".
The diameter of the knockoff base is 3.5".
The ear height (from the knockoff base) is 1.5", so I'm assuming the
center-of-mass of the ear to be .75" or a 5" diameter relative to the center
of the axle.
The tire circumference (21" diameter) is 65.97" or 5.498'.
At 60 mph (88fps) the tire rotates 16.006 revolutions per second or 960.35
rpm.
The center-of-mass of the ears has a 15.71" circumference, and at 60mph
(88fps) travels 251.45 inches per second (20.95fps).
ASSUMPTIONS:
20% of the weight of the knockoff is in the ears, so the weight of the ears
totals 4.66 ounces.
The wheel could feasibly rotate (on the splines) during acceleration and
braking an equal amount so this motion cancels itself, providing (1) the
knockoff rotates with the wheel or (2) does not rotate on the hub.
At 60mph (88fps) the center-of-mass of the ears possess 31.759 foot ounces
(1.985 foot pounds) of Kinetic Energy.
Drag Factor (during braking) of 0.80% for an acceleration rate of <->25.76
feet/second/second.
Acceleration 0 to 60 in 10 seconds for an acceleration rate of +8.80
feet/second/second.
FINDINGS:
During constant acceleration a force (energy) of 17.468 foot pounds/second
is generated to accelerate (LOOSTEN) the knockoff on the hub.
During constant deceleration (braking) a force (energy) of 51.137 foot
pounds/second is generated to accelerate (TIGHTEN) the knockoff on the hub.
These forces should remain constant until the mechanical drag of the
metal/metal surfaces of the wheel and knockoff PLUS the hub to knockoff
overcame the Kinetic Energy of the knockoff and prevented further loostening
or tightening.
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