Quaternions

[Frank LoPresti]

Mike,

I think you can overcomplicate any model of the cast especially when you get into the mechanical side of the equation and I literally do mean the mechanical side of the equation, from an engineers point of view. I'm a motion based caster I look at caster movement and it's effects on the fly line, then I think about how the rod tip effects the path of that line or the shape of the loop itself. Then I draw some basic observable conclusions.

This is why I framed the question to Merlin as to point of view. Ask an engineer what Stroke Length means to them, and then ask almost every instructor I know, and you will get a very different answer. Im only concerned with rod rotation or the size of the casting arc. In some examples like the Paradigm video, Merlin mentions that there was only rotation involved in that stroke because the translational effect of the rod rotation was so low as to not even be considered as a factor.

Then you might have a cast like Lasses 120, which when maxed out translation in that stroke gives you a 25 % increase in line speed. Then you look at a Rajeff stroke which is nowhere close to a 120 degree arc, more like in the neighborhood of 95 to 100 degrees. Same for Menno Van Damn's casts. So the translational boost in line speed is less then it might be for the 120 simply because the stroke is not as long, nor the arc as wide. Keeping in mind that in both examples the cast requires almost max effort, although I suspect Steve holds back a bit some times and this of course I'm relating back to the 5wt distance game.

So for me at any rate, as a laymen, when it comes to engineering, looking at the quantitative analysis of both those styles as to the effect that translation has upon rotation is simply that of additional line speed. Thats great! But both styles result in identical distances. Beyond that translation has no direct bearing on the path of the rod tip or loop formation, only the rod tip as it relates to tip speed.

As Merlin noted, translation has the effect of "stretching" out the path of the rod tip, so indirectly if you stretch out the path of the rod tip, I suppose in effect it makes it a little less convex or slightly less domed then would be the case for a stroke that used less translation. But without the rotational aspect of the stroke and or the angular acceleration of the rod butt there would be no tip path shaping the line/loop for translation to stretch out.

This is why my sole focus is on the rotational aspect of the casting stroke, it's the engine that pulls the rod tip along it's path, the caboose can't do that. So the fixation on translation is from an engineering standpoint, as it goes to the rod it self. My fixation is on the caster's motions, primarily the rotational aspect of the casting arc and angular acceleration about that arc.

The engineered model of the stroke as far as I can figure has at least 4 or 5 casters reading this thread out there, maybe more most likely, believing that translation of the rod from a mechanical engineering point of view would some how, as a result of the increase in line speed attributed to translation, would some how offset or mitigate the excessive angular rotational force of the rod butt, that resulted in a concave path of the rod tip, and that somehow, this stretching out the concave path of the rod tip would some how flip over a concave tip path, and turn it into a convex one. That's what I'm asked to believe judging by many of the comments I've been reading.

This misunderstanding or misreading goes back to the upper casting model and it's related to 2 issues. First the upper model would lead one to believe that translation can turn a concave tip path into a convex one. And right now I suspect that Magnus next comment might be, "Frank no one ever said that translation could turn a concave tip path into a convex one, where did you get that from." Gordy is probably got a brain cramp just from reading this. But when you think about it, translation is being turned into an alchemy attempting to convert a stretching of the concave path of the rod tip, and turning it into gold, or a convex path of the rod tip. That's not going to happen try as you might.

The second issue is that a little knowledge can be a dangerous thing when it is used to support a position that can't quite possible be true. This too is reflected in the upper model, as it is based on engineering "what ifs." as to intent and fault. It leads one to believe that something that can not be true is indeed possible. That's why all the confusion over tip path as it relates angular acceleration and the casting arc as tip path relates to loop formation, and translation of that arc as it goes to tip speed as it relates to the stretching out that tip path, somewhat, but not all that much.


I'm not the lone star I'm not the lone anything, I'm iterating what the majority of instructors who understand tip path and rotation is it relates to loop formation understand. Nor am I antsy over any of this. I suspect that is true for those now reconsidering the effect that translation has on the rod tip. If no one wants to agree that they were mistaken and move, on I suspect we'll see more of the same character assaults and endless questions, as if that too would turn a concave path into a convex one. Okay then ! That's just grand.

Cheers
Frank

[Magnus]

I've no idea is this supports or challenges your observations Frank.

[Frank LoPresti]

is that a 5wt rod and line ? Take a look at the BOTW clip the arc is way smaller is what I'm comparing the 120 arc to in my post.

[Magnus]

Nope that's a tournament outfit. Same physics applies as far as I know. None of the BOTW footage I can find is filmed from a similar position. If anyone can find any from side on I can do the same overlay.

[Frank LoPresti]

Same physics apply sure. Except in the BOTW you have a cast that use a much smaller arc and far and away less translation. That is the only distinction I am making as to more or less arc or translation as to end results. I tried to post up the link from you tube but it told me that video was not available. But it's there if you go to you tube, and it's a pretty clear shot at angle and translation. You can't miss the differences in stroke. You would have to be blind.

[Magnus]

Ok Frank

Here's Rajeff SAYING a long stroke is a good idea and demonstrating it.

http://www.youtube.com/watch?v=A3eYHn6Azs4&feature=related

[Frank LoPresti]

So for me at any rate, as a laymen, when it comes to engineering, looking at the quantitative analysis of both those styles as to the effect that translation has upon rotation is simply that of additional line speed. Thats great! But both styles result in identical distances. Beyond that translation has no direct bearing on the path of the rod tip or loop formation, only the rod tip as it relates to tip speed.

This is to my point, not that Steve is telling us it's a good thing to lengthen the stroke. That's great ! I get my casters to length or shorten their stroke depending upon the cast. I'm not going to use a long stroke to cast a short line either. My larger concern is someone thinking that translation can reverse the path of the rod tip from a concave one to a convex one or that translation is a fix for tailing loops. That's the point, not the ancillary stuff.

[Magnus]

Tim Rajeff showing his stroke and then pantomining his brother's style

http://www.youtube.com/watch?v=5hCwu6u2jBA&feature=related

[Frank LoPresti]

Mike,

I think you can overcomplicate any model of the cast especially when you get into the mechanical side of the equation and I literally do mean the mechanical side of the equation, from an engineers point of view. I'm a motion based caster I look at caster movement and it's effects on the fly line, then I think about how the rod tip effects the path of that line or the shape of the loop itself. Then I draw some basic observable conclusions.

This is why I framed the question to Merlin as to point of view. Ask an engineer what Stroke Length means to them, and then ask almost every instructor I know, and you will get a very different answer. Im only concerned with rod rotation or the size of the casting arc. In some examples like the Paradigm video, Merlin mentions that there was only rotation involved in that stroke because the translational effect of the rod rotation was so low as to not even be considered as a factor.

Then you might have a cast like Lasses 120, which when maxed out translation in that stroke gives you a 25 % increase in line speed. Then you look at a Rajeff stroke which is nowhere close to a 120 degree arc, more like in the neighborhood of 95 to 100 degrees. Same for Menno Van Damn's casts. So the translational boost in line speed is less then it might be for the 120 simply because the stroke is not as long, nor the arc as wide. Keeping in mind that in both examples the cast requires almost max effort, although I suspect Steve holds back a bit some times and this of course I'm relating back to the 5wt distance game.

So for me at any rate, as a laymen, when it comes to engineering, looking at the quantitative analysis of both those styles as to the effect that translation has upon rotation is simply that of additional line speed. Thats great! But both styles result in identical distances. Beyond that translation has no direct bearing on the path of the rod tip or loop formation, only the rod tip as it relates to tip speed.

As Merlin noted, translation has the effect of "stretching" out the path of the rod tip, so indirectly if you stretch out the path of the rod tip, I suppose in effect it makes it a little less convex or slightly less domed then would be the case for a stroke that used less translation. But without the rotational aspect of the stroke and or the angular acceleration of the rod butt there would be no tip path shaping the line/loop for translation to stretch out.

This is why my sole focus is on the rotational aspect of the casting stroke, it's the engine that pulls the rod tip along it's path, the caboose can't do that. So the fixation on translation is from an engineering standpoint, as it goes to the rod it self. My fixation is on the caster's motions, primarily the rotational aspect of the casting arc and angular acceleration about that arc.

The engineered model of the stroke as far as I can figure has at least 4 or 5 casters reading this thread out there, maybe more most likely, believing that translation of the rod from a mechanical engineering point of view would some how, as a result of the increase in line speed attributed to translation, would some how offset or mitigate the excessive angular rotational force of the rod butt, that resulted in a concave path of the rod tip, and that somehow, this stretching out the concave path of the rod tip would some how flip over a concave tip path, and turn it into a convex one. That's what I'm asked to believe judging by many of the comments I've been reading.

This misunderstanding or misreading goes back to the upper casting model and it's related to 2 issues. First the upper model would lead one to believe that translation can turn a concave tip path into a convex one. And right now I suspect that Magnus next comment might be, "Frank no one ever said that translation could turn a concave tip path into a convex one, where did you get that from." Gordy is probably got a brain cramp just from reading this. But when you think about it, translation is being turned into an alchemy attempting to convert a stretching of the concave path of the rod tip, and turning it into gold, or a convex path of the rod tip. That's not going to happen try as you might.

The second issue is that a little knowledge can be a dangerous thing when it is used to support a position that can't quite possible be true. This too is reflected in the upper model, as it is based on engineering "what ifs." as to intent and fault. It leads one to believe that something that can not be true is indeed possible. That's why all the confusion over tip path as it relates angular acceleration and the casting arc as tip path relates to loop formation, and translation of that arc as it goes to tip speed as it relates to the stretching out that tip path, somewhat, but not all that much.


I'm not the lone star I'm not the lone anything, I'm iterating what the majority of instructors who understand tip path and rotation is it relates to loop formation understand. Nor am I antsy over any of this. I suspect that is true for those now reconsidering the effect that translation has on the rod tip. If no one wants to agree that they were mistaken and move, on I suspect we'll see more of the same character assaults and endless questions, as if that too would turn a concave path into a convex one. Okay then ! That's just grand.

Cheers
Frank

This is typically what I see, you miss or avoid the larger issue and single out a single passage from a long post as if that disputed the larger issue behind the post. It does not.

[Magnus]

Frank

What I read is a badly written series of half points which taken together make no sense.

[Frank LoPresti]

Good that you've voiced an opinion. But that opinion will not turn a concave tip path into a convex one or explain how translation might fix a tailing loop as a result of a concave tip path. Not a problem, no worries here.

[Frank LoPresti]

I like the top one Frank, take out the drift (optional) and take out the creep (undesirable) and that's my stroke,

Mike,

I took out the creep and drift from the upper diagram and just left in the drag with some translation and a little bit of rotation with little or no force applied to the rod butt. If I got that right and that motion is part of your casting stroke that applies a force to the line to form the loop you have reduced the angular force applied to the rod but by drifting forward with little force. So what you have done according to the diagram is "creep," and even though it was intentional, it still has the unintended effect as creep would on the casting stroke. So I would expect to see a slight tailing in the loop. You sure that you want that in your casting stroke ?

[Magnus]

Frank

No You didn't get that right

I don't like these diagrams because we can draw things that can't happen - but let that go.

We have been over this ground Frank, moving the rod forwards (FFF creep) needs to be linked with poor power application (late burst of acceleration) before it creates a tailing loop. Nothing in these drawings indicates how the power was applied at the butt, nothing says if the translation is accelerating or at a constant speed, nothing says if Mike mis-timed his haul (for that matter if he'd stop eating ice cream while casting he'd get on a lot better.)

What I understand is in one set of posts you are saying that translation reduces power - makes a weaker stoke - the next it causes too much power over a narrowed arc.

[Frank LoPresti]

Here's another view Mike, just for laughs of course.

Frank

[Frank LoPresti]

Here we go.. But on the PDf the ideal tip path and rod tip path are slightly out of sync and could not re edit the original doc. But you get the picture anyway.