This calculates to 26% of the height of the lifter or in this case 456 mm (18.0 inches). This posi
-
tion is shown as it is considered to be the start of the second pull phase and therefore the high
-
est power output of the lift and the most instrumental phase in completing a successful flip. If
the second pull yields a high position relative to the lifter, the transition and push phases will be
possible.
Forces Applied:
A free body diagram of the image in Figure 14 is presented in Figure 15 below. The line of ac
-
tion from the foot contact (A) to the shoulder (B) is considered the powerhouse of hip, knee and
ankle extension to rapidly drive the FLIPPER up. This force of the body is represented by force
vector
F
B
. The connection of the body to the FLIPPER is made by the lifter’s hands on the handles.
This tensile force of the arm is represented by force vector
F
T
. This vector (
F
T
) is made up of two
component vectors, the force against the chest pad (
F
C
) and the rotation force (
F
R
) which drives
the motion of the FLIPPER up. Optimally the rotation force
F
R
and the power force of the body
F
B
will be parallel, as this is 90 degrees to the line of action from the handle to the point of contact
of the FLIPPER with the ground (pivot point). Any additional horizontal forces applied to FLIPPER
will act to try to drag it on the ground. These forces would not be transmitted to the torque of
rotating the FLIPPER up.
Using the Flipper - Foot Placement
0.26*H
90°
17°
A
B
F
F
F
F
B
C
R
T
Fig 15
14