From: SOON LEE <soonleemd@msn.com>
Date: November 18, 2010 12:03:04 PM EST
To: Gordy Hill <masterstudygroup@comcast.net>
Subject: "Casting stroke" and "stop'

Hi Gordy,

I have altered my previous submission for the study group. Sorry for the inconvenience: 

Data from casting analyzer and modern video have introduced new terms used in loop dynamics. Rod tip path after SLP and line launch passes through RSP-1, maximum counterflex, RSP-2, ending in final rod holding position RSP-3. "Stop" is a sequence/phase: it begins with the "end of angular rod acceleration" and ends at RSP-1. In addition "casting stroke" is said to extend from start of the stroke up until the end of, and including, the "stop" sequence. I find these definitions cumbersome in introducing loop dynamics to beginning students. Many of these new terms are virtual, not easily appreciated by the novitiate, and indeed should be bandied about at this time only in sophisticated company. They should play little part in our search for a simple set of instructions to introduce loop dynamics to the inquisitive beginner.

We teach a casting stroke to produce SLP of rod tip. Unfortunately the micro-definition of "casting stroke" has come to be used in the field. Thus defined it takes a lot of explaining to clarify that only the early portion of the casting stroke before line launch produces the desired SLP. The terminal portion of casting stroke after line launch always has convex tip path. Confusion arises because "casting stroke" has now two components, before line launch and after line launch. I dare-say that line launch is a critical event in fly casting. Once line is launched the profile of the upper leg is established and loop forms. Subsequent rod and rod tip travel after line launch only affects loop size/shape. Using "casting stroke" to encompass two separate functions for two different purposes seems unnecessary and destined for muddled communication. Indeed I have difficulty instructing students if I keep this micro-definition of  "casting stroke" in mind. To throw a straight upper leg: keep early casting stroke in SLP, terminal casting stroke after line launch does not play a role here. To throw a narrow loop: keep early casting stroke in SLP, terminal casting stroke with minute tip convexity at "stop" keeps loop narrow. For a wide loop asked of a CI candidate: convex tip path will only explain the width of the loop; early SLP before line launch is still needed to keep upper leg straight. 

In these newer studies, "stop" delineates a period of time between "end of angular rod acceleration" and RSP-1. Its use in this sterile fashion belittles the traditional importance of the exhortation "stop". While we do not ask the baseball pitcher to stop his arm to throw his ball we use "stop the rod" to command the caster to let the line go. "Stop" is an important essential: its intent is to launch the fly line, not just to describe an eventual state of physical cessation of motion. We launch the line by deviating the rod tip from its SLP path. Furthermore the manner we stop the rod determines loop size. The slightest of angular rod rotation in a brisk "stop" results in a narrow loop. A lengthier angular rod rotation in a gradual "stop" results in a wider loop. 

In the macro-world the terms "casting stroke" and "stop" have understandable meanings to the caster. We use casting stroke to govern the profile of the upper leg: SLP to throw a true loop, concave tip path for a tailing loop. We "stop" the rod to launch line: briskly for a narrow loop, gradually for a wide loop. Refined investigative studies may illuminate further the parameters of "casting stroke" and "stop" in the micro-world of loop dynamics. But we should not conversely let these virtual parameters re-define our real world understanding of "casting stroke" and "stop".

In this regard, I am proposing that "casting stroke" be defined as extending from the start to the point when line is launched.  "Stop" sequence begins with line launch and ends with rod at final rod holding position. These two definitions will cover the entire spectrum of loop formation. With these definitions, I have a simple set of instructions for my students when introducing them to loop dynamics: "Casting stroke governs profile of upper leg; "stop" governs loop size/shape; final rod holding position governs profile of lower leg". 

Respectfully,

Soon.

From: soonleemd@msn.com
To: hillshead@comcast.net; bwrflylines@bresnan.net
Subject: RE: Lovoll & Borger
Date: Mon, 15 Nov 2010 20:42:15 -0800

Hello Gordy and Bruce,

Thanks to you both for taking the time to comment on my thoughts. Pardon me if I have not responded quickly. I am presently in Singapore: my e-mail sevice is erratic.
 
I was putting together this PowerPoint presentation for the inquisitive beginner wishing an "Introduction to Loop Dynamics". From our correspondences so far (my alternative proposals in red):
 
1) We are agreed on "stop" as a sequence, not an instant of time. "Stop" can be brisk/crisp, or it can be gradual/prolonged.
 
2) When does "stop" begin?  "Just when the "stop" begins would be a matter of definition, of course, but most would agree that it coincides with the the end of angular rod acceleration". 
The student cannot perceive when "stop" begins because this "end of angular rod acceleration" is a virtual concept. What is the role of that duration of time between line launch and "end of angular rod acceleration? 
"Stop " is an important essential in fly casting. The purpose of "stop" is to launch the line. "Stop" is a sequence/phase. It begins when we deviate rod tip from its straight line path and line is launched.
 
3) When does "stop" end? "Again, a matter of definition, I could live with MCF, but would prefer RSP-1". "Using RSP-1 (loop formation)  as the end of the casting stroke simplifies things greatly". the start of loop formation; so close to RSP-1 that any difference has not yet been quantified".  
Rod in final holding position.
 
4) Extent of casting stroke: "Again, a matter of what we want terms to mean. Using RSP-1 (loop formation)  as the end of the casting stroke simplifies things greatly." 
Casting stroke includes "stop" sequence. All casting strokes are therefore convex because of convex tip path during the "stop" sequence at the end of casting stroke. It is inaccurate to describe a casting stroke as producing straight line path of rod tip withtout the cumberson explanation that we are referring only to the early portion of casting stroke.
SLP refers to ideal tip path of the casting stroke. Casting stroke ends when line launches. "Stop" phase follows casting stroke.

 5) Loop size:  "When dealing with students I find that tip path is the easiest way to explain the cause of big loops. After that, I relate the reason for the tip path to rod angle, and how it does not match well with casting arc to create a straighter tip path. The audience needs to be considered, of course".
[GH]  It does depend upon the level of the students...... as well as the way each digests information.

Putting it simply, I find that most students do respond well to an explanation and demo of rod tip path as it relates to loop size.  Early students don't understand the matching relationship of rod bend with casting arc though more advanced casters do.

Some relate well to the idea of the position of the rod top being close to the oncoming line for a small loop and the rod tip being farther away from the oncoming line for a large loop.  This is usually though not necessarily due to the timing (duration) of the stop sequence.

Then I go on to show that the former results mostly from a straight line path of the rod tip with just enough convexity at the end to get the rod tip out of the line path while the latter is a larger loop created by greater convexity of rod tip path with loop formation starting with the rod tip farther away from the line path. 
 Use "stop" to explain control of loop size. A brisk "stop" with minimum angular rod rotation after line launch produces narrow loop; a gradual "stop" with lengthier angular rod rotation after line launch produces wider loop. 

 Set of instructions: "instruction to students should be simple, straightforward, and consist of generalities.  The variables should be left to instructing advanced students".
" I do not envision casting definitions commonly being used when teaching typical students. The definitions we've been working on are designed primarily for casting geeks and instructors to use when discussing casting, and when testing. Currently there are so many different understandings of common terms that confusion on the terminology alone causes big problems".
[GH]  I think definitions are best left to instructors.  Further, that the simpler the language used for students, the easier it is for them to understand.
My set of instructions: Casting stroke (from start till line launch) governs upper leg. "Stop" (from line launch through RSP-3) governs loop size/shape. Rod at final holding position, RSP-3,  governs profile of lower leg.

Please do not attribute my stubborn comments here for plain obstinacy, though my wife may differ (:>). I am getting educated here. I can appreciate better now your points of view. Many thanks. Nevertheless I get from our communications that newly coined terminologies on loop dynamics are not easily applied when teaching beginners. My advocacy is that if identifying casting stroke as ending with line launch and defining "stop" as beginning after line launch do not conflict with current data on loop dynamics, then teaching loop dynamics become much easier. (perhaps 

                                                                             ____________________________________________________________________________________________________________________________________

Gordy invited me to present the essence of this discussion to the MCI study group. Here is my submission for posting:

There is a lot of uncertainty with terms used in loop dynamics. Prevailing thought is that "stop" is a sequence/phase. One popular understanding is that it begins with the "end of angular rod rotation" and ends at RSP-1. In addition "casting stroke" is commonly used to encompass a duration of time extending from start of the stroke up until the end of, and including, the "stop" sequence.

 I find these definitions cumbersome in introducing loop dynamics to beginning students. Many of these new terms are virtual, not easily appreciated by the novitiate. For example it takes a lot of explaining to clarify that all casting strokes by definition have convex tip paths because tip path in the "stop" sequence is convex. Care is needed to emphasize that SLP applies only to the early portion of the casting stroke. The terminal portion of casting stroke (after line launch) with the "stop" sequence plays the role of determining loop size. The minutest of "stop" sequence may be trivialized so that SLP is the reason for narrow loop. The largest of "stop" sequence ending with the rod at rest horizontally accounts for the phantom "stopless" cast. The roles played by the period between line launch and "end of angular rod acceleration", and that between RSP-1 and RSP-3, in loop dynamics are not clear at this time.

I have tried with much effort to instruct students in these terms to throw a straight upper leg (keep early casting stroke in SLP, terminal casting stroke does not play a role here), to throw a narrow loop (keep SLP, ignore minute convexity at "stop" may be ignored), to throw wide loop (convex tip path accurately describes it, if we discount the fact that early SLP is needed to keep upper leg straight).

I am proposing, before FFF etches glossaries in stone, that "casting stroke" be defined as extending from the start to the point when line is launched. "Stop" is an important essential: its purpose is to launch the fly line. "Stop" sequence begins with line launch and ends with rod at final rod holding position. These two definitions will cover the entire spectrum of loop formation. With these definitions, I have a simple set of instructions for my students when introducing them to loop dynamics: "Casting stroke governs profile of upper leg; "stop" governs loop size/shape; final rod holding position governs profile of lower leg".

Respectfully,

Soon.

 

Subject: Re: Lovoll & Borger
From: hillshead@comcast.net
Date: Sat, 6 Nov 2010 19:55:26 -0400
CC: soonleemd@msn.com
To: bwrflylines@bresnan.net

Soon & Bruce...

My comments in text below Bruce's in blue preceded by [GH] .

Soon.   You have launched an interesting discussion.  May I have your permission to share this with our Study Group ?

Gordy

On Nov 4, 2010, at 6:40 PM, Bruce Richards wrote:

Hello Soon,
Thanks for sending this, some very good thoughts and observations below. I've made some comments below your text, preceeded by ******
Best,
Bruce
----- Original Message -----
From: SOON LEE
To: Bruce Richards ; Gordy Hill
Sent: Thursday, November 04, 2010 1:35 PM
Subject: Lovoll & Borger

Hello Bruce and Gordy,
 
I'd like to share more thoughts with you both.
 
When I discuss my views on loop dynamics with other MCIs/Governors, most of them quote the article by Lovoll and Borger presented in Sexyloops some years ago. This research was specifically aimed at shedding light on (1) the "stop", and (2) the "spring energy" of a cast.
 
L & B showed that "stop" is not instantaneous but is a sequence of events. Because of this, some ridicule the continued use of "brisk stop" or "dead stop". I take advantage of L & B's observations to support my definition of "stop" as a phase. In my definition, "stop" begins with line launch and ends at RSP-3. 
***Of course the "stop" isn't instantaneous, people aren't capable of that. The word "stop" is very good for instruction though, as a rapid deceleration (often called stop), is what we want.
          [GH]  Depends on whether we are discussing the STOP as that of the hand / rod butt or that of the rod tip.
Either way, it is never close to instantaneous.  I agree with L&B that it is  best seen as a STOP SEQUENCE.  The sequence probably never actually finishing with complete cessation of all motion whether of the hand or rod tip.

That sequence, is one of rapid deceleration.  In the case of the rod tip it is complicated by also including rod vibration characteristics including counterflex, rebound, and all other following rod vibration until full damping has occurred.

I've never really liked the term "hard stop" because it implies an instantaneous cessation of all motion which is, of course, an impossibility when casting (unless the rod strikes a stationary object).  Demonstrations of stops made by striking such objects result in ruined casts due to the vibrations set up that way.

I also agree that while not strictly scientifically correct, that the concept of the STOP being as crisp as possible remains a valuable teaching tool at all levels below investigation of the actual physics involved.

L & B coincides the beginning of "stop" with the point of time when angular rotation and rod hand speed peak (estimated to be some 0.1 second before RSP). That is their privilege while examining the micro world of casting. In the macro world the caster can only perceive the instant of line launch. This instant of line launch is peculiarly not mentioned in the article. Perhaps it coincides with MCL (minimum chord length) at 0.1 second before RSP.
****Just when the "stop" begins would be a matter of definition, of course, but most would agree that it coincides with the the end of angular rod acceleration.
[GH]  OK for the hand / rod butt.  However, the rod tip obviously continues after RSP 1 to RSP 3.
 
L & B credits "stop" as ending with MCF (maximum counterflex). That is their privilege again. In the macro world, the caster can only appreciate the "stop" as ending with the rod in final holding position at RSP-3.
***Again, a matter of definition, I could live wit MCF, but would prefer RSP-1.
 
For the purpose of analysis L & B places RSP at time zero. I hope this is not a reason to consider RSP as the end of the casting stroke. In the macro world the end of the casting stroke should coincide with the beginning of "stop", that is to say, at line launch.
****Again, a matter of what we want terms to mean. Using RSP-1 (loop formation)  as the end of the casting stroke simplifies things greatly.
[GH]  My own preference is to see the end of the casting stroke as the start of loop formation; so close to RSP-1 that any difference has not yet been quantified.
 
There is a favorite assertion that while SLP is the ideal, tip path before line launch is nevertheless always convex to some degree. I am not sure if this is confirmed by researchers or confirmed mathematically but I would intuitively doubt this is so. The tail end of a trailing fly line will hang low with gravity. This may obscure the SLP immediately following the rod tip. L & B's visuals seem to show that the tip path immediately behind the rod tip is straight.
****Straight is certainly rare at best, but both convex and concave are possible. L&Bs visuals are for one cast, there are many other options.

[GH]  Agree.  Long casts with loop leg crossover due to the effect of gravity is sometimes called the TRAILING LOOP or UNDERSLUNG LOOP.

I wonder if it might be better to call it a "GRAVITY LOOP ".   In any event, in the video's I've seen, the rod tip path seems very close to straight line with just a bit of convexity.
 
L & B's paper only depicted the observations on a "brisk stop" for a narrow loop. There was no data for wide loop. Virtual RSP in essence reflects on the position of the rod shaft at the "stop". A small angled deviation from rod shaft position at line launch will produce a narrow loop. A larger angled excursion of the rod shaft produces a wider loop. It is this greater gross movement of the rod shaft that contributes to the wider loop size. The oft-quoted extended convexity of tip path is just a by-product and is not useful in explaining reason for wide loop.
****When dealing with students I find that tip path is the easiest way to explain the cause of big loops. After that, I relate the reason for the tip path to rod angle, and how it does not match well with casting arc to create a straighter tip path. The audience needs to be considered, of course.
[GH]  It does depend upon the level of the students...... as well as the way each digests information.

Putting it simply, I find that most students do respond well to an explanation and demo of rod tip path as it relates to loop size.  Early students don't understand the matching relationship of rod bend with casting arc though more advanced casters do.

Some relate well to the idea of the position of the rod top being close to the oncoming line for a small loop and the rod tip being farther away from the oncoming line for a large loop.  This is usually though not necessarily due to the timing (duration) of the stop sequence.

Then I go on to show that the former results mostly from a straight line path of the rod tip with just enough convexity at the end to get the rod tip out of the line path while the latter is a larger loop created by greater convexity of rod tip path with loop formation starting with the rod tip farther away from the line path.
 
In the macro world of teaching loop dynamics we need definitions to cover the sequence of the entire cast. With rod in hand the caster cannot relate RSP with the end of casting stroke but he can appreciate line launch. He cannot locate that period of time between line launch and RSP that affects loop size whereas he can produce wider loop by a controlled gradual "stop". He cannot visualize stop ending at MCX but he can appreciate that "stop" is a controlled follow through finishing at final rod holding position. 

****I do not envision casting definitions commonly being used when teaching typical students. The definitions we've been working on are designed primarily for casting geeks and instructors to use when discussing casting, and when testing. Currently there are so many different understandings of common terms that confusion on the terminology alone causes big problems.
[GH]  I think definitions are best left to instructors.  Further, that the simpler the language used for students, the easier it is for them to understand.
 
We must keep in mind the limited dual purposes of L & B's experiment (on "stop" and "spring energy"). Other happenstance observations obtained from that worthy experiment are appreciated but should not be casually used to establish other "truths" (a medical research dictum).
****No one has done exhaustive study of a wide variety of casts, most studies, like L&Bs and a couple Noel Perkins and I have done, viewed a single cast, or a small number of similar casts. Conclusions can be drawn from those studies, but those conclusions cannot be applied to different casts. L&Bs study of one cast gave conflicting results to a study Noel and I did, and they berated us for that. Our study of the cast we viewed was accurate, but the cast, and rod, was different than what they studied. They fell into the same trap some accused us of, making a broad conclusion based on limited data. We did not do that... That is all behind us now, and I hope it stays there....
 
Further the micro world of loop dynamics may not be easily applied to the perhaps empirical, but logical method of teaching loop dynamics to the enthusiast off the street. We need an easily understood set of instructions, especially those that have withstood the test of time. For MCI instruction: that may be a different consideration.
****What do you mean by "set of instructions"?
[GH]  Again; I think instruction to students should be simple, straightforward, and consist of generalities.  The variables should be left to instructing advanced students.
 
In my simplified approach to loop dynamics, I have not contradicted L & B's observations. I believe however that Bruce disagrees with their conclusion that "spring energy" contributes only 20% to the energy of the cast.
****Not at all, I am sure there are many casts where spring enegry contributes 20% to the cast, and others where it is even less. But there are also cases where the contribution is much greater.
[GH]  I have only performed the crude demonstration of "potting" a rod butt in a vise and drawing back the line to the point of extreme rod bend (load) then letting it go with the outcome being the pure "spring" yielding little distance and a poor layout.

I follow with a stiff broomstick "rod" which cannot be loaded in the sense of a true bend.  I can cast it farther, though the result far from ideal.

This is a gross simplification which ignores the myriad variations of casting.
I think Bruce is correct when he points out that the percentage of casting energy resulting from "spring" and swing" will vary a great deal from cast to cast.

I have no reason to doubt L& B's observation of 20% being contributed to the "spring".dsf
 
My other thoughts:
Open loop is a hybrid of non-loop and wide true loop.
*****I've never understood what a "non-loop" is, I've never seen a cast where there wasn't a loop. Without definitions, an open loop, wide loop, true loop, etc. can be what someone wants.

[GH]  Some use the term "open loop" to mean one which is so wide that it hardly resembles a loop shape any more.  To me all these are descriptions of very wide loops made by varying amounts of the same mechanisms.
 
Shock wave on lower leg, cause of?
****Most are caused by the counterflex and rebound of the rod tip after RSP. What the rod tip does after loop formation affects the bottom leg. If the rod tip bounces down, then up, it puts a wave in the leg. If it bounces down and stays there, it simply opens the loop.
[GH]  Agree. Aberrations of rod tip path made by either the vibrations of the rod or separate additional actions of the caster after loop formation can lead to loop morphing.  Sometimes the momentum of the traveling loop can result in these being "ironed out".
 
I should stop here. I can hear my wife crying out "You are too opinionated".
****Don't get me in trouble here, but she's wrong, you're not too opinionated! But if she reads this, I retract that statement and agree with her! I've been married long enough to know when to back down....

[GH] Not going there !

Gordy
Best,
Bruce
 
Warmest regards,
 
Soon (:>)