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Fly rod deflection

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Paul Arden
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Fly rod deflection

#91

Post by Paul Arden » Fri Dec 16, 2016 12:00 pm

Counterflex is a strange topic and I know many people claim to be able to minimise it. It's probably worth starting a new topic! I'll do this :)

Cheers, Paul
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Bernd Ziesche
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Fly rod deflection

#92

Post by Bernd Ziesche » Sun Feb 26, 2017 8:08 pm

slack wrote:Has anyone read or watched the video explanation of the above by Tobias Hinzmann all about fly rod deflection? My questions are: Do you agree with his findings? How can understanding this information help me become a better fly caster and last could some one explain his findings in the simplest lay term ways http://www.passionfliegenfischen.de/exp ... eflection/ I sorry you have to recapture the link Thanks in advance slack
Hi Slack,
to me it doesn't make much sense comparing the efficiency of a) a non flexible with b) a flexible fly rod when taking one and the same size of arc for both rods while this arc only matches for the flexible rod perfectly. That is what Tobias did for his investigation + plus he took out rod mass from the equation. His result of the flexible fly rod being more than 2 x more efficient for transfering energy to the line would be even much higher when taking into account the much higher mass of a rigid rod.
This is nowhere near my practical experience and how I understand this.
Simply I use two very different arcs. In case of using a wide arc for the rigid rod I use very different hand pathes as well. Doing so the results of course would be very different.
One could also take one and the same arc matching the none flexible fly rod and failing for the flexible one. For example a small arc and high force profile for the none flexible rod resulting in an excellent loop while the flexible rod may have too much bend for that small size of arc causing the loop to fail and thus dramatically loosing efficiency as well.
Theory is fine and always worth trying to be find and then optimized. But in the end it should match casting reality since practise always wins over theory, I think.

Besides the very opposite results of Tobias his investigation I believe having a none flexible fly rod of the same length, same diameter and same weight distribution would be an impressive distance casting tool outperforming max possible distance of a typical flexible fly rod.
Regards
Bernd
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The first cast is always the best cast.

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Merlin
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Fly rod deflection

#93

Post by Merlin » Mon Feb 27, 2017 9:57 am

Hi Bernd

No way, the broomstick cannot be better than the flexible rod. Your virtual comparison is based on irrealistic assumptions (same weight for example). You met the broomstick limit with the Sage #11. Even if we could have mass less rods, the flexible one would always beat the broomstick, because the flexible one can store extra energy which is released for the line. And I can remember Alejandro experiment with his "under the tip" cast.

Merlin
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Bernd Ziesche
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Fly rod deflection

#94

Post by Bernd Ziesche » Mon Feb 27, 2017 12:53 pm

Merlin wrote: No way, the broomstick cannot be better than the flexible rod. Your virtual comparison is based on irrealistic assumptions (same weight for example). You met the broomstick limit with the Sage #11. Even if we could have mass less rods, the flexible one would always beat the broomstick, because the flexible one can store extra energy which is released for the line. And I can remember Alejandro experiment with his "under the tip" cast.
Hi Merlin,
why is "same weight distribution" an unrealistic assumption while a "mass less" fly rod is not? :)
I agree we won't have any of it in our real world...

What I can tell from casting an unflexible fly rod (in our real world): Even though it had a massive disadvantage by slowing down my rotation due to a lot of extra weight + bad weight distribution my line went out:
a) in the most tightest loops
b) with the straightest line end passing my position
to c) a pretty impressive distance just a tad shorter as it did with a "normal" fly rod.
Having said this I wasn't used to cast such a rod at all. So there was still room to maintain.
In terms of efficiency I think the fact that I could send the end of the fly line on a much shorter path to the same target was a massive advantage. The problem what we called "distance phenomenon" was killed (for me) with that tool.
This is what happened in the real world but I think would be very difficult to be taken into account in a model to get numbers for the efficiency?

Looking for efficiency datas in terms of energy transfere "caster to fly line" I think would have to include not only the first part of line in front of the rod but the whole fly line on it's way to the target. In the end it's always the fly I want to deliever to the fish. If the loop collapses, the energy transfer in my book wasn't efficient either as long as we take all parts being important into the equation. I don't even think I yet can imagine what a complex model that would have to be.

So I rather prefer to not leave out my real experience. Thinking of what a benefit less mass for a broomstick would have given my cast, it would have turned into a hell of a long and impressive cast especially against wind - that I am sure about. It looked to me the only thing it was missing was a bit of speed. That would come with less mass. That's why it feels to me that such a rod would be an amazing tool to play with. :p

Back to the investigation of Tobias:
The flexible rod being several times more efficient in energy transfer doesn't feel right to me.

Tobias set a flexible rod which on the choosen arc resulting in a straight tip path following his calculations. Such a rod would have to be quite bendy for an avg. cast just to come close to a straight tip path for such an arc.
Based on his calculations the efficiency would decrease all the way down to the unflexible rod. Thus his findings were to have the efficiency (in energy transfer) decreasing from a significant flexible to the unflexible fly rod.
Again this does not feel right to me.
I tend to believe that the stiff rods are pretty efficient in energy transfer.

I think to remember Lasse having said something like: The bending behaviour means that some of the energy will be lost in the rod and never enter the line. The more bend the more energy may be lost.
That felt right to me.

Besides all this Tobias calculated the higher tip speed for the none flexible fly rod as far as I understood his investigation. Just he then recalculated this into a direction change to compare with the perfect horizontal direction for the choosen flexible rod. This recalculation meant a significant decrease in the resulting horizontal speed for the none flexible fly rod about factor 0,6. So the tip of the flexible fly rod was 33% faster afterwards.
If the caster is able to optimize tip path just a bit he would change the findings dramatically though...

Regards
Bernd
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#95

Post by hshl » Tue Feb 28, 2017 11:48 am

Bernd,
I think a) section F3, the 17th conclusion as well as the footnotes 49 to 51 should give you an answer b) 'casting feelings' are off topic here !?

Tobias
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#96

Post by Bernd Ziesche » Tue Mar 07, 2017 4:50 pm

hshl wrote:Bernd,
I think a) section F3, the 17th conclusion as well as the footnotes 49 to 51 should give you an answer b) 'casting feelings' are off topic here !?
Hi Tobias,
according to your 17th conclusion it doesn't make a difference if you cast a broomstick within a huge arc or a small arc. It also doesn't make a difference if you maintain rod hand path when using a relatively wide arc for a broomstick in order to achieve a proper tip path. So it seems you can't vary loop shapes here or you think different loop shapes don't make for a difference in efficiency.

In my experience loop shape is one of the most 3 important key factors to effiency in fly casting.

If I cast a broomstick on a pretty small arc but with high force application I shape a tight loop in proper speed. The same arc and the same force application for a medium flexible fly rod and I tail because I force the tip too low for the small arc. Thus I ruin all efficiency for the cast and it goes down the drain. Using this for your calculations in effiency and your numbers would change to more than opposite.

Thus your 17th conclusion is wrong in my book - as is your calculation if it should hold true for all different styles how you would cast these two rods to compare them in efficiency.

The feel in casting isn't part of your own calculation for a significant more than two and a half times higher efficiency for the flexible rod. You left the feel out of this calculation, not me. ;)

According to your 18th conlusion the caster would have to lift his rod hand when casting the broomstick within a wide arc. The longer the broomstick would be the more lift would be necessary not to loose proper tip path (according to you). I don't know why in your 18th conclusion rod hand path suddenly matters, while according to the 17th it doesn't.
Anyway my understanding looks somewhat different: The longer the broomstick would be, the smaller I can keep the arc and still create enough speed (of course at some point it gets too heavy). The small arc again makes for the proper tip path. So in truth it's the very short broomstick which needs a significant arc in order to create enough speed. Yes, here a significant lift is needed then. So for me it's opposite in casting realty.
A good example is my 15ft. DH rod. With a 11m shooting head I cast it within a 11 - 1 o'clock size of arc. Enough speed to send the head until the "horizon". The same size of arc with a much shorter single hand rod of let's say 9 feet gets tricky for that length of head. Definetly much less speed and less distance. I instead open the arc here.
The longer the rod, the smaller of an arc will match to hit the desired speed in my book. Thus less lift would be needed for a proper tip path.
As a short exercise I have asked many of my students to cast (single handed 9 ft.) within a small (11-1) arc. Most failed (for a first trial) and were using a significant wider arc as soon as the head (9-12m) was out of the tip. With the DH students this indeed was very different. We match the size of arc to the desired speed in the first place!
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Bernd
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#97

Post by hshl » Wed Mar 08, 2017 8:01 am

Bernd,

a) in order to generate a proper tip speed using a smaller casting arc than in my investigations you need a significant higher angular velocity. A higher angular velocity increases the effort of the caster (see annex 1 and 2: effort (Arot) = ½ * moment of inertia * angular velocity²) so that the ratio of the energies (output / input) remains unchanged. Thus even if you cast both rods under their best condition – e.g. wider arc for the flexible, shorter arc for the rigid rod - the flexible one will be significant more efficient. Longer DH rods have a longer lever arm, so a higher tip speed requires a higher effort too (due to leverage). So the only thing that is wrong is 'your book'.

b) the vertical swing is part of both conclusions, the 17th and the 18th "... The absolutely stiff fly rod can not deliver an improved transfer of energy also for other pathways, rotational angles or dyanical paths …" are including e.g. the vertical swing too. You should read carefully.

c) tight loops could be formed with both the flexible and the rigid rod. Maybe the rigid one could tighten them a bit more - but the price forming them with a rigid rod is a significant higher effort so that over all the flexible rod will always be more efficient than the rigid one.

You still don't understand my work and what efficiency is about. You talk about ‘real’ casting without having any data about the effort except of your 'feelings' and you ignore physical relations. The broomstick could be effective under some conditions – but never efficient. I’m not willing to continue the discussion here on the board with you. If you’re really interested in my work instead of trying to keep your myth of the ‘efficient broomstick’ alive you can PM me.

Tobias
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#98

Post by Bernd Ziesche » Wed Mar 08, 2017 1:54 pm

hshl wrote: a) in order to generate a proper tip speed using a smaller casting arc than in my investigations you need a significant higher angular velocity. A higher angular velocity increases the effort of the caster (see annex 1 and 2: effort (Arot) = ½ * moment of inertia * angular velocity²) so that the ratio of the energies (output / input) remains unchanged. Thus even if you cast both rods under their best condition – e.g. wider arc for the flexible, shorter arc for the rigid rod - the flexible one will be significant more efficient. Longer DH rods have a longer lever arm, so a higher tip speed requires a higher effort too (due to leverage). So the only thing that is wrong is 'your book'.
Hi Tobias.
When I aerialize my max possible line carry with a soft single hand rod in 9' it costs me a lot of effort not to a) loose control by loosing loop shape and direction for the loop and b) create enough line speed. Changing the same line and carry to a medium stiff rod makes it easier for me (less effort) to control the same carry. Changing to a pretty stiff rod makes it much easier to control that carry. I can pretty much relax then. It would also be possible to lengthen the carry for the same effort on the stiff rod. Taking a 15' DH rod makes it by far easier to aerialize the same carry. Not much effort needed here.I have done this test with several proper casters all ending up in the same conclusion.
I understand you think this to be all opposite based on your calculations. I think it's fine to just disagree then. :cool:

Looking to what casting experts do in the WC I think it's based on better efficiencies why most tend to use pretty stiff fly rods and why the longest casts are done with the longest DH rods (not the shorter ones).
Cheers
Bernd
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#99

Post by Paul Arden » Wed Mar 08, 2017 5:46 pm

I've cast the same rod and would consequently argue that the purpose of bend is to allow us to use a wider arc as well as to make the stop less hard on our joints. I'm not enthusiastic about casting this rod nor anything that tends towards it. But in terms of learning it's very useful indeed. The same goes for fibreglass and to a lesser extent cane of course.

Cheers, Paul
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#100

Post by Bernd Ziesche » Thu Mar 09, 2017 11:55 am

Paul Arden wrote:that the purpose of bend is to allow us to use a wider arc as well as to make the stop less hard on our joints.
Hi Paul,
no one (I know) ever thought a none flexible fly rod (which is no fly rod in my book anyway) would be a better choice for fly fishing. There are a lot of reasons why we use flexible fly rods.
Fighting a fish on a broomstick would not work well, nor would it be fun. Setting the hook often would crack the leader.
The whole resistance profile for a) accelerating and b) decelerating the (flexible) fly rod is much smoother (no sudden rises in resistance). This holds true especially for the beginning of the acceleration and as you say for the process of stopping the fly rod.
Then the fly rod comes in much less weight and a better weight distribution as would any broomstick. Also the air resistance profile based on diameter (surface) is much better for the fly rod. As you say, the fly rod supports wider arcs since the tip path will be straighter during acceleration (without adjusting rod hand path in a more or less difficult way as it would be necessary for the broomstick within the wide arc). Then the fly rod tip section will still accelerate the line while we decelerate the rod butt already. Thus we use the same size of arc between the final stop positions more effective for acceleration. With the broomstick we would start loop formation directly when we would start to decelerate. Also we sometimes can cast a bow and arrow cast - where loading the rod is very helpful.

Of course we have to live with some cons as well. Counterflex opening our loop front again. We - well most of us - have to live with tailing issues from time to time (not to say pretty often). This is hard with the broomstick (for me a tailing loop is impossible here). We also have to live with the tip lag. That means for all casters who pause the rod in the point of return in order to wait for the line to straighten/unroll gravity increases the line sag. With the broomstick we would not have this delay and thus the line sag is kept smaller. The "angle of dangle" is better with the broomstick as is the dangling end! The softer the rod, the bigger the dangling ends are for most casters I have been watching. This is the reason why I see much straighter casts with the Tarpon rods in windless days for the 5wt. MED for all casters I ask to cast that combination. Of course some expert casters have learnt to reposition the soft rods in a way they can very well deal with the tip lag. But this isn't an easy task.

So in the end there are pros and cons that come into play for our fly rods.

Tobias his work wasn't about highligthening the pros and cons of both the fly rod and the broomstick. It was about efficiency in terms of what effort you put in and what you get out. His findings are that a soft rod (soft enough to offer a perfect straight tip path over the full accelleration) has best efficiency and the more you direct your rod to the broomstick side the less efficient it will be. That simply doesn't match for me, since there are many situation in which I am sure a stiffer rod is more efficient (and even more effective) compared to a softer one.
Also I believe that only some of the effort we put in the fly rod which makes it bend will go into the line. Quite some of the effort will go into the bending and straightening of the rod itself. And then easily some of the effort which will go into the line will go in the wrong direction thus making the cast (effort we had) less efficient. As long as we keep the arc small this does not happen with the broomstick. No doubt it still has to be less efficient based on it's much higher weight. But leaving out weight here, I doubt that the effort and what you get is several times lower for the broomstick in general - no matter how and what for we use it. Same goes to the stiffer vs. the softer rods. I believe a lot of key factors come into play when looking at the effort/output side of the cast. It's not just one straight away (constant) result for all our tackle adjustments and situations. Arc sizes, rod hand pathes, positioning of the rotation and all those key elements matter (have an impact on both the efficiency and the effectiveness for a cast).

In the end I want to position my fly to the fish. Even though I have no precise measurement for the effort I do trust my feel for the effort. For the output I have at least a slow motion camera and a tape.
Tobias sais I don't measure the effort. Well, the same holds true for himself. He makes a calculation not a measurement. I have no calculation but feel. He is right I trust more into my feel since his results are so far of what I feel to happen in my casting.

Again no one ever was saying the broomstick would be anything like a valuable tool for fly fishing. All we said was that fly casting mainly is not about loading and unloading the rod, but rotating the rod in order to create the desired speed instead. The broomstick was a proper tool to prove this point. I think Grunde did a fantastic job here to highlight this - as did Alejandro in saying "rod bend is a consequence of our main purpose to rotate the rod".

I made this video about the big loading concept:
https://vimeo.com/60189818

Tobias claimed I was using a wrong (non representative) angle (line to rod) for that test. The results would be very differnt when positioning the rod more into the direction of the cast before letting the line go. He also claimed: "Up to now I'm still missing any physical law, which helps the rigid fly rod to transmit the energy feeded in the grip into the tip."

I still used a much stronger load I would have when casting that length of line. Changing the angle has much less of an effect and does not change the quintessence ime.

Let's have a look at what I do when casting a huge pike fly. I prefer to have a very stiff fly rod making for smaller tip lag. That is because I can't very well accelerate such a fly (without an extra heavy fly line) when using a relatively soft rod. It is impossible to get proper speed before the rod starts to straighten (max load) and then I also couldn't store enough energy in the rod in order to significant further speed up the (high resistance) fly. Changing to a significant stiffer rod helps to already create serious speed before straightening. Also I can store little more energy in such a rod, I think. Then less of this energy will go into huge counterflex mainly. I don't need any physical law to unterstand that I can rotate a broomstick at the butt section while this speeds up the tip pulling my heavy fly as well. How could my effort I add to the butt section not go into the line to some significant degree? I have no clue if there is any physical law supporting that (Tobias his) idea.
Cheers
Bernd
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The first cast is always the best cast.

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