Posts Tagged ‘whip effect’

when the whip joins the pirouette

Donnerstag, Februar 7th, 2019

Since the publication of my “Experimental investigations on the fly rod deflection” a longer time has passed and meanwhile there have been some discussions (especially on the forum) about the concept Franz- Josef and I have choosen to clarify the redistribution of angular momentum (we call it “redistribution effect”). The preface Franz- Josef wrote for my investigations expresses the concept how we both tried to clarify the physical relations well and we are still convinced that this concept enables much more people to follow the content than too theoretical approaches using differential equations. In section F1 as well as in annex 2 and 3 of my investigations Franz- Josef and I are mainly talking about the “pirouette” and the “whip” effect in order to explain the redistribution of angular momentum. This essay is going to look with fresh eyes on the interrelation between the “pirouette” and the “whip” effect and how both effects redistribute of angular momentum.

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angular velocities of the mass elements on the fly rod shaft

Mittwoch, Juni 28th, 2017

Playing with the GIMP tool (GNU Image Manipulation Program) I superimposed some pictures taken out of a casting sequence of me. I liked the result since it visualizes how the angular velocities of the mass elements on the fly rod shaft vary over the entire casting stroke.

The angular velocity ω is determined by the angle φ divided by time t (ω = φ / t). Due to the deflection of the fly rod during the earlier phase of rotation the lower mass elements are covering a larger angle than the upper ones (shown by the violet lettering, see picture 1). According to the relationship shown above they have the highest angular velocity ω.

During the later phase of rotation it is the other way round. Now the upper mass elements are covering a larger angle (shown by the red lettering, see picture 2), for which reason they have got the highest angular velocity ω.

So what can be detected is a shift of the highest angular velocity from the lower mass elements towards the upper ones over the duration of the fly cast (see picture 3 – visualized by the black arrow), which correspond to the varying contribution of the angular velocities.

The angular velocity (ω) multiplied by the moment of inertia (I) leads to the angular momentum (L). L = I * ω. Taking the modification of the moment of inertia caused by the deflection into account, this relationship points to a contribution of angular momentum, which shifts towards the upper mass elements like the angular velocities.

Due to the energy conservation law the energy can’t just disappear, thus the energy of the lower mass elements must contribute the accelerate the upper ones, resulting in a higher angular velocity, angular momentum respectively during the later phase of rotation (energy transfer).

The towards the tip of the fly rod shifting contribution of angular momentum equals the shift of the center of the rotating mass shown in my “Experimental investigations on the fly rod deflection” (rev. 2.0, November 2014 – section F1) and indicates, that some kinetic energy could climb up along the fly rod shaft towards the tip. This behavior benefits an efficient fly cast (ratio of the output and input energy).
It is obvious that the energy transfer from the grip towards the tip of the fly rod depends on the way the fly rod is deflected. The varying contribution of the angular velocities of the mass elements is a good indicator for that.
The pictures above are taken out of a video, which I produced in order to explain what I wrote before:

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To me the following picture is a good summarizing illustration about the ‘energy flow’, transfer of angular momentum respectively taking place along the fly rod shaft.


experimental investigations on the fly rod deflection

Montag, Mai 19th, 2014

(deutsche Version)


update in november 2014 – the revision 2.0 is published ! The english translation is out now !

In the revision 2.0 I added some investigations – especially about the impact of the mass of both fly rods and about a casting movement that keep the tip of the rigid fly rod on a straight path. With pleasure I anticipate that all the criticism can’t question my investigations. The revision 2.0 is completing my investigations and all opened (“critical”) questions should be answered.

With this videos I try to explain the effect of the conservation of angular momentum in fly casting.


A more detailed physical explanation, why the flexible fly rod concentrates energy towards its tip, could be seen here:



During the past year 2013 I occupied myself with the deflection of the fly rod. With a commercial digital camera, which takes a video by 30 frames per second, a casting sequence of me was catched and I pointed the video out frame by frame. I compared the conclusions of my casting sequence with the conclusions an absolutely stiff rod reveals under the same conditions. This comparison shows that the flexible fly rod possesses a lot of advantages. For example one advantage is the efficiency, which is more than double times higher in comparison with the absolutely stiff fly rod ! It would be a pleasure to me, if my investigations could help to understand the fly cast better.

My special thanks go to the physicist Dr. Franz- Josef Schmitt for his accurate translation, preface and support.

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My latest videos about the contribution of angular momentum: