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#51
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rb608 wrote:
On Nov 10, 6:22 am, wrote: Some considerations on casting and rod loading. A simple calculation for casting in air is; Frt = Fi * Fa * Ff * Flt Where Frt = the force on the rod tip in kg.m/s², Fi = inertia (mass) in grams, Ff = the coefficient of fluid kinetic friction µk ( air resistance), Fa = the acceleration of the line in ms², and Flt = line tension in kg.m/s² Now, I admittedly can't haul worth a ****, but I do know my physics (maybe that's my problem.) I'm having a bit of difficulty reconciling your theory above with that of Mr. Newton who opined a much simpler equation, F=ma. Force equals mass times acceleration. That's it. The extra terms you included (Ff and Flt) are misplaced IMO. Under no circumstances would they be multiplication terms in the equation. The line tension is just another Force that would be part of the net force on the tip of the rod, not a separate term. The air resistance term (what units are you thinking for that one?) also does not belong there. Any resisting forces due to fluid friction would similarly be a part of the net value of the Force at the rod tip. It does not belong in the equation as a multiplicative term. As I said, I can't haul; but I fear the inaccuracies of your mathematical equation may be detracting from your practical instruction. Line tension is a "special" force, considered to be parallel to the string under tension. However, as the line acceleration is dependent on this tension, it must be proportional to it. The force on the rof tip, and the force on the end of the line are "normal" forces and can be measured directly. Friction and line tension both affect the acceleration of the line when it is moving, and have to be included in the dynamic equation. For a static system they can be ignored. |
#52
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Try again;
Some considerations on casting and rod loading. A simple calculation for casting in air is; Frt = Fi * Fa * Ff * Flt Where Frt = the force on the rod tip in kg.m/s², Fi = inertia (mass) in grams, Ff = the coefficient of fluid kinetic friction µk ( air resistance), Fa = the acceleration of the line in m/s², and Flt = line tension in kg.m/s² As may be seen, the equation depends on line tension being greater than zero to produce a positive value. The higher the line tension, the greater the value. If the value is zero or less, then Frt=0 This equates to " No tension= "no force on the rod tip" To find line tension, rod loading, acceleration,friction, etc. one may simply substitute the equations, you can calculate all the variables, and also prove that line tension is a major factor. Frt = Fi * Fa * Ff* Flt Flt = Frt / fi * Fa * Ff Fi * Fa * Ff = Flt / Frt So, as the rod loading at any given point is known, ( it is simply the curve of the rod, can be measured statically for any weight). We will assume a rod loading of 0.01 kgm/s² (10 grams ). The line mass can be weighed. Assume 30g here. As the static line tension is exactly equal to the static rod loading this must also be 0.01kgm/s² but only when the rod and line are static! What is left when the rod/line is moving must be the acceleration. Tension is required to accelerate the line. However, the actual acceleration of the line, and friction, are extra variables we don?t know yet. Plugged in to the first equation, we get; 0.01kgm/s² = 30g * Fa * Ff * Flt Second equation; Flt = 0,01 kgm/s² / 30g * Fa * Ff Third equation; 30g + Fa * Ff = Flt / 0.01kgm/s² We still need to know the coefficient of friction and the acceleration. Unfortunately, as this coefficient is not a fundamental force, it can not be derived from first principles, and must be observed empirically. In this case we will simply assume it to be 0.3. We don't know the acceleration either, but we will also simply assume a value here, of 1ms² That gives; 30g * 1m/s² * 0.3 = Flt / 0.01kgm/s² 30g * 1m/s² = 0,03kgm/s² * 0,3 = 0.09 kgm/s² Therefore, Flt= 0,09kgm/s² / 0,01kgm/s² The units cancel, and Flt = 9kgm/s² Add the values to all equations; Frt = Fi * Fa * Ff * Flt 0.01kgm/s² = 0,03kgm/s² * 1m/s² * 0.3 * 9kgm/s² Second equation; Flt = Frt / fi * Fa * Ff 9kgm/s² = 0.01kgm/s² / 0,03kgm/s² * 1m/s² * 0.3 Third equation; Fi * Fa * Ff = Flt / Frt 0,03 kgm/s² * 1 m/s² * 0.3 = 9kgm/s² / 0.01kgm/s² This proves all equations. Plugging in the values you have for any particular conditions will tell you the line tension, the rod loading, the acceleration, and the friction. If you graph the information, you can read it off directly. You can also see how changing the mass changes the tension and acceleration, how friction affects the model, and a lot of other things. You can also plug in the force for a haul, and see how it affects the setup. Lots of things are possible. These equations are rudimentary, but cover all major factors. I am still working on equations for the conversion of line tension to line momentum. The equation shown is also primarily designed to show what happens on the forward stroke. From when the rod begins loading. One may of course adjust it, and add other factors if desired. There are a couple of points worthy of note. The fluid friction varies according to the amount of line outside the rod tip, as of course does the mass, and its velocity. Once line has rolled out and is shot or released, the tension on the line itself is governed by the momentum of the line pulling on the backing. This retains some tension on the line. As long as the line stays straight, as a result of this tension, it will fly further. Once it starts to "crinkle" it collapses. In order for the line to turn over completely, there must be sufficient tension for it to do so. The equation shown is just one of a series which I am trying to use to set up a casting simulator, first as a mathematical model, and then including programmed graphical elements. The target is a dynamic model of casting, into which one may plug in any rod or line, and also show the optimal length and weight for shooting heads etc etc. Hopefully it will also show the effects of differences in rod tapers and action. One of the main things of note here, is that it is rod and line tension which keeps the line swinging back and forth when false casting with a fixed line. The force applied to the butt only adds sufficient force to account for "losses" to fluid friction. Also, one does not "throw" or "cast" the line, one rolls it out. When the line is rolling out, it is the tension on the bottom leg of the line loop which causes this. In order to convert the rod and line tension to line momentum, when shooting line, the point at which tension is released, and how this is done, is of major importance. In order to "force" turnover for instance, more tension is required. This can be done by "overpowering" the cast, or by using a "check haul", pulling back on the line before it has unrolled will cause tension to increase, and the line turns over faster. Pulling back on a line which is already unrolled will of course merely brake it. This also demonstrates how hauling works, it does not accelerate the line, or load the rod much, it increases system tension, mainly line tension, which is converted to momentum. This theory, and the related equations, are my original work, if you use it, please credit where you got it from. TL MC |
#53
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#54
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rw wrote in
m: Women are the product of time and money: women = time * money A friend of mine authored a JIR paper on "cliche contradiction", mathematically resolving "absence makes the heart grow fonder" with "out of sight, out of mind". It made one of the "best of" books. -- Scott Reverse name to reply |
#55
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Scott Seidman wrote:
rw wrote in m: Women are the product of time and money: women = time * money A friend of mine authored a JIR paper on "cliche contradiction", mathematically resolving "absence makes the heart grow fonder" with "out of sight, out of mind". It made one of the "best of" books. I stole that from Wikipedia. -- Cut "to the chase" for my email address. |
#56
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Ignoring friction for the moment;
Frt = Fi * Fa * Flt Which gives; 0,01 kgm/s² = 30g *Fa *Flt Therefore, Flt=0,01 kgm/s² * Fa And, 30g+Fa=Flt/0,01kgm/s² Assuming an acceleration of 1m/s² 30g*1m/s²=Flt/0,001kgm/s² 30g*1m/s²=0,03kgm/s² Therefore, Flt= 0,03kgm/s² That seems to be correct. I will try to graph that and see if it correlates with my other stuff. |
#57
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#58
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Russell D. wrote:
wrote: Some considerations on casting and rod loading. A simple calculation for casting in air is; Frt = Fi * Fa * Ff * Flt snipped mucho geeko So, if I memorize all that will I no longer get wind knots? Ever hopeful, ... You better hold off on the memorizing for awhile there, Russell. Turns out The Loony's Hauling and Loading treatise is a work in progress. At least that's the latest story out of Loonyville. At first all of roff was stupid, then he was using European notation (LOL ;-), then his computer didn't do the formatting correctly, now finally he admits it's full of errors and miscalculations but that's exactly why he posted it here in the first place. To subject it to peer review. But it's already been published to much acclaim, he just won't say where. There's no one as good at shameless lying on the fly than His Loony Mikeness. And now he's frantically canceling most of his posts in this thread so that in the future any remembrance of this pathetic episode will be a baldfaced lie. Quite the piece of work our Loony. -- Ken Fortenberry |
#60
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