Lift force acting on a fly line

[Dirk le Roux]

Brilliant, Graeme!

Do you think that a similar experiment with same length sufficiently stretchy rubber bands inserted at regular intervals, so that we can see tension, would be feasible? A concern with this idea may be that the fly line may becomes too boingy and therefore not realistically representative?

Best regards,
Dirk

[Paul Arden]

That's great Graeme! Is this the line you are bringing Snakehead fishing?

Do you think that a similar experiment with same length sufficiently stretchy rubber bands inserted at regular intervals, so that we can see tension, would be feasible

I believe that Lee has something like this.

Cheers, Paul

[IBM]

Excellent Graeme.
From a frustrated long time lurker.

[Graeme H]

Welcome out IBM! And thanks, I'm glad you like it.

Thanks too Dirk. I think it might be possible to insert rubber bands, but I believe it might be too much for me to do it. If Lee has something like that already set up, I'd love to see how it goes.

Cheers,
Graeme

[Merlin]

Graeme

Excellent video and I guess the trick was suggested by Vince. Here is another snapshot:

tell tails 1.JPG (20.04 KiB) Viewed 2930 times

Our eyes like to see what fits out thinking. Here is another picture from the video. The yellow lines show the tangential direction of “rotation speed” and the blue ones the horizontal direction of the front loop speed (best guess in both cases). The green lines show the direction of the theoretical resulting air flow which cuts the angle between blue and yellow lines in two equal parts. If you look at the two visible tails in the inclined section, the theoretical approach does not look so wrong sometimes.

Merlin

[Paul Arden]

As I watch them go around the point of the loop, Merlin, they all are pointing straight up. At the bottom of the loop they often align at a slight angle backwards. I found this very interesting and I think it means that there is some forward movement of the line in the rod leg. From the tracker videos I believe that we have seen this.

Cheers, Paul

[Graeme H]

Our eyes like to see what fits out thinking. Here is another picture from the video. The yellow lines show the tangential direction of “rotation speed” and the blue ones the horizontal direction of the front loop speed (best guess in both cases). The green lines show the direction of the theoretical resulting air flow which cuts the angle between blue and yellow lines in two equal parts. If you look at the two visible tails in the inclined section, the theoretical approach does not look so wrong sometimes.

Merlin

I've got a large selection of videos to choose from Merlin. They all show the same thing I've described above. This is a VERY repeatable experiment. Please try it yourself.

The tracking data from earlier casts shows there is no "rotation speed" of any point in the rod leg unless it's a snap cast. The points move forward in the fly leg until they hit the loop, at which point they go straight down in the rod leg (in a tethered cast). Your tangents are things you want to see but aren't really there. If you'd like me to track these tell-tails to show you that, I can do so. Just say the word.

Yes Paul, there is a little forward movement of the line as the cast progresses, so the tell tails lay back somewhat, and even point down as the rod tip bounce travels along the rod leg towards the loop.

(And no, this was my idea. I came up with it after ongoing discussions with Vince, but it was part of a bigger experiment in which the fly line was paired to a 3 metre length of wool. This it the aftermath after the wool was mostly removed. Did you know that dramatically increasing skin and form drag on a Rio Permit line doesn't add any lift to the cast either?)


Cheers,
Graeme

[Graeme H]

Tracked Tell-Tails

These are the paths of the bits of wool. What was the theoretical path supposed to look like? Where is a tangent applicable?

[Paul Arden]

That’s a truly excellent experiment, Graeme. Thank you!

[Graeme H]

Thanks Paul.