Constant Acceleration

[Lou Bruno]

My overall distance regardless pretty much stays constant. When I overline the 5wt Sage by going heavier by one line weight, I'm not expelling as much force...I think. My acceleration stays constant; my loops are noticeable narrower.
Trying to understand the overall dynamics by observation can be misleading. That's why reading your graphs are important, the data doesn't lie. So what I think I'm changing, I might not; what I think are my results could be wrong.
I'm finding this topic to be interesting....thanks.
Lou

[Merlin]

Lou,

The main parameter involved is air drag on the line, and the lighter the line is, the larger air drag effect is. A heavier line rolls over easily; it can even accelerate during its flight, contrary to a light line which can decelerate. Loop size is important of course and is one of the other factors at play.

Consequently you need to generate more speed for lighter lines, which means larger acceleration for smaller mass. It is then difficult to theorize about the final level of force required (two antagonists effects), but practice shows that casting a heavier line at a given distance is easier, requiring less force to get sufficient speed for the line.

Merlin

[Bernd Ziesche]

I'm interested in this topic and it's importance. I've been experimenting with overlining and underlining 5,6, and 7 wt rods; most of the time by 2 line weights. Using the F= m*a equation, I know we're changing the mass component; how would overlining & underlining affect the acceleration?

Hello Lou,
Hard to give an accurate short answer.
Where I mostly fish, we often have some wind. Using a lighter line asks for more speed to deal with wind.
The heavier line goes further and gets less blown out of direction by wind.
Most casters increase speed with the lighter line. That offers the amount of rod bend feeling fine, while up lining increases bend and feels fine with little less speed.
But then it all depends what the purpose is.
Regards
Bernd

[Lou Bruno]

Good replies, practical and relative advice. Sort of takes the theory of the topic and applies it to what we do....fly cast.

[Lou Bruno]

Merlin

Still on the subject...sort of. I started to read the post on 'what does the hit do'

Referring to your diagram. What's the difference between peak haul acceleration and peak haul velocity? They both relate to change in distance?
Lou

[Merlin]

Lou

It's a question of timing. Peak haul acceleration is roughly halfway between the beginning of the haul and its peak velocity (which corresponds to zero acceleration). Idealy if I can say so, peak haul velocity should take place just after MAV, and before RSP anyway. Earlier than that and you risk a tail in the line (unless your haul is mild).

Can you please elaborate on the reference you made to distance, I do not understand what you mean.

Thanks

Merlin

[Lou Bruno]

Merlin

I see velocity and acceleration both having a relationship to distance. Correct me if my understanding is wrong. Velocity is the change in distance something travels in a certain direction over time. Whereas, acceleration, as I see it, is the rate of change something moves in a certain direction at a certain time.

When we are casting aren't we changing our velocity of the fly rod? Our fly rod changes direction over a certain distance in time.
The rate of change, the velocity or speed, in which the fly rod travels in that direction at a specific time is our acceleration.

So, both velocity and acceleration both have a relationship to distance?

Lou

[Stoatstail50]

Hi Lou

Simple as I can make it.

Velocity is a measure of an objects speed and direction, there is no link with distance.

Acceleration is a measure of the objects rate of change of velocity.

"Work" is a measure of force applied to the object over distance.

"Impulse" is a measure of force applied to the object over time.

"Momentum" is the mass of the object times its velocity.

That's it

[Graeme H]

I’ll also add a version …

Displacement is the location of an object.

Velocity is the rate of change of displacement. (Distance per time, or metres per second)

Acceleration is the rate of change of velocity. (Velocity per time, or metres per second, per second)

[Stoatstail50]

Heck...