Contributions of lever, spring and inertial acceleration

[crunch]

Does the lever effect come low because DH casting stroke/power input ends when rod still has lots of bend?

Esa

[Merlin]

Hi Esa

In this study case, the stroke ends just as the rod acheives RSP. The rather low lever effect is linked to the general slow pace of the rod. The rod is very long, and not extraordinary stiff. The lever is the sign of stiffness. I am going to illustrate that and post it on Paul's thread (whip effect).

Merlin

[hshl]

Hi Daniel,

The general trend whatever the rod length is, is that the "whip" effect (I use to call that the inertial effect) is important for light carry. It explains why a cane rod can cast a leader only with ease. If the topic refers to long carries, then the whip effect is unlikely to dominate, unless an adequate study shows the opposite.

the reason why I ask might be due to my rather weak english... I didn't get your important point above. Does a light carry equal a shorter cast and a longer carry a longer cast (false casting amount of line) ?
Thanks, Tobias

[Merlin]

Hi Tobias

You are right

Merlin

[hshl]

Thanks Daniel,
but than a further question arises since I don't expect this behavior. To me the "whip effect" requires rather a "well deflected" fly rod which tends to be generated by longer casting strokes / longer line carries (letting the double haul out of the consideration) ?! For example when looking videos of some shorter accuracy casts I see just a very little deflection and for this case I expect a lever dominated cast and not a "whip or spring dominated" ?!
Cheers, Tobias

[Merlin]

Tobias

Look ar the graphic in post #8 of the thread on whip effect. The « intermediate carry » is constant (10 grams) for all rods. This is a high load for soft rods (left hand side of the graphic), and small for the stiff rods (right hand side).

The relative share of the whip effect is larger for the softer rods, and the lever is most important for the stiff ones. That corresponds to your comment.

Merlin

[VGB]

If we are talking about casting a heavy tipped bendy rod that wobbles a lot then I agree with Daniel, I use a cane rod on the small streams just for that purpose because I rarely have room for a long carry. However, I never see second or third modes with this rod.

Regards

Vince

[VGB]

That said it doesn’t take much for it to become a “well deflected rod” but I’m not convinced we are all talking about the same thing.

[hshl]

Merlin,
no question about the grafic of your post #8 on the thread "whip effect" from my side (however, I was also surprised about the less lever contribution for a very soft fly rod). How does this grafic changes for a given stiffness (let's say a "medium to fast" action) and a varying line carry ? This would face the fishing situation as the same fly rod is used for different distances. And I expect a rising whip / spring and a declining lever contribution for an increasing line carry ... about this my question was before. Therefore I wonder why the whip effect should be important for a shorter line carry ?!

Cheers, Tobias

[Merlin]

Hi Tobias

Comparisons vary with the assumptions taken. On top of that there are interferences in between mechanisms, and the split becomes tricky sometimes. I tested a variable input for a variable carry for a given rod. I increase the maximum rotation speed as the carry increases. Now the results depend on the procedure I use to define the split. I have to work on that point, otherwise we can come to different conclusions.

The "leader only" casting case: For such cast one tends to use a sharper stroke with a "hard" stop. The deceleration imposed to the rod is then amplified by the inertial effect, and this is the phenomenon I am refering to (it comes out from Lagrangian equations). Change the assumptions (or the casting style) and the split is changing accordingly.

Merlin