To the point of this discussion, measuring rod stiffness at some lesser flexion and then projecting values to some other, greater, dynamically functional flexion is the same as tape measuring the bass to weigh it. Projecting values from a lesser flexion itself invokes ANOTHER model with all it’s own assumptions. Even more specifically said, If you are going to measure rod “stiffness” for purposes of use at some defined FULL flexion, do not measure stiffness at some lesser flexion (such as 1/3) and then project and calculate to the full flexion state. For goodness sake, eliminate the variables within the assumptions and pull the rod down to the defined full flexion position and measure it. THAT is the real figure with a greater degree of accuracy.
All models of a cast consistently break what looks to be a single, fluid motion into three stages: the initial loading phase, the middle acceleration phase, and the final unloading phase (Bolton’s “Stop” phase.
See Fig 1. from Bob Bolton’s “The Mechanics of Fly Casting” ( http://www.hatofmichigan.org/uploads/Mechanics_of_Fly_Casting_5.pdf)
In the initial LOADING phase the assumptions are:
1) the rod starts in a neutral rod straight position (rsp) angled back (variably) and the line is static straight behind the rod.
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