Leader limpness

[gordonjudd]

Being that the mass profile of a leader is considered the most important factor in leader turnover,

Lou,
Leader turnover is so complicated that I doubt you could use one parameter to characterize it. For instance I would expect the aerodynamic drag on the fly would be a dominate effect on the turnover of the leader.

If you come across any high speed videos showing the turn over of different leader designs I would love to see them. Tom showed the turnover of one of his casts years ago on the old board but it was hard to make out the frame to frame shape difference.

any increase in diameter increases it's mass...direct relationship?

As discussed in the Jack Moray Leader Design thread on the old board (old board is still in the process of being activated according to Paul) it is the linear mass density of a leader section that determines its mechanical impedance.

The linear mass density varies as the square of the diameter for a given volume mass density. I don't know if the density of fluorocarbon and nylon leaders has been measured somewhere, but assuming the ratio is close to Esa's value of 1.5 then a sqrt(1.5)= 1.22 increase in the nylon leader diameter would produce the same linear mass density as a given fluorocarbon diameter.

If the fluorocarbon material has a Young's modulus that is 1.3 time that of nylon then a diameter increase of 1.3.^.25 = 1.067 in the nylon material would produce the same bending stiffness.

Gordy

[Lou Bruno]

How do we define turnover rate of a leader? What variables control or effect turnover rate?
Lou

[Merlin]

Hi Lou

I'm afraid we have nothing like that, there is no "turnover rate" for a fly line either. Fly line and leader are designed through experiments mainly, I do not know of a calculation related to their turnover, it depends of many parameters (e.g. loop size and shape). Maybe Bruce can comment on this point.

What we know is that the front taper allows a deceleration of the line/ leader, avoiding the "kick" of straight tapers. Sometime the cast is made on purpose (overpowering in order to angle the leader) to change the turnover.

The methodologies proposed by authors for leader taper design is not based on explicit dynamics, as far as I know.

Merlin

[Lou Bruno]

Merlin
The term "turn over rate" is used often, I couldn't find a more definitive meaning. I can define how my leader "turns over," change the variables that control leader turn over...length, stiffness, diameter but, not "turn over rate."

BTW, often I have to research some of the more scientific terms, and meanings used on SL, to refresh my understanding and grasp the meaning. Been to long out of college!
Thanks
Lou

[ACW]

Not good enoughsexy loopers
Wheres the dynamics of balanced level 3 fly leaders when you guys want to baffle me with jargon!

[gordonjudd]

I do not know of a calculation related to their turnover, it depends of many parameters (e.g. loop size and shape).

Merlin,
Like you I don't know what "turn over rate" might mean, but for for the casting accuracy games most good casters will trim the length of the tippet for a given fly (length is different for the dry fly game vs. the trout fly game) so the fly will "hang" as the leader straightens out.

Too short of a leader and the fly will kick over a bit and may tick. Too long and the leader may not fully straighten out on the longer targets.

I don't think that most anglers "hang the fly" before they make a delivery cast since it may spook the fish, but it is interesting the care tournament casters take to tune their fly and leader combinations to take advantage of that technique in the casting games.

Gordy