Analysing loop propagation 2

[Paul Arden]

I don’t think it will accomplish anything! There are two many other variables. But you never know with experiments. That’s why we do them, right? I would like to eliminate the low backcast from the equation, or indeed otherwise prove it right!

Cheers, Paul

[Paul Arden]

Hi Walter,

I think Graeme’s argument was that the loop stays horizontal in flight because the backcast is low and the fly leg has upwards momentum. Which might be true. Certainly in Graeme’s videos this appears to be the case.

However the flip side to this argument is that if the backcast was high then the forward loop should noticeably fall away.

Just like we don’t see loops veering left/right, I don’t see loops falling away that have been started from a high backcast position. Maybe they do which is why I need to film them from another angle.

It’s not about right or wrong, it’s about discovering what happens When it is about right/wrong no one believes the outcome anyway!

Cheers, Paul

And just like 99.9% of all discussions that happen in this board we’ve now gone totally into a different direction. You personally decribed a situation where you cast downhill and the line appears to fall slower than expected. I spent time and effort and provided an explanation for why you are seeing that. Now you are changing initial parameters or assumptions, describing something totally different imo, totally ignoring my response to your original discussion and sending everything back to the right vs wrong mindset by saying “it isn’t about right or wrong it’s about discovering what happens” when you totally ignore a perfectly good explanation of what happens by changing what you say was happening,i.e initial parameters. If history on this board repeats itself then I expect we will now see a lot of discussion about a mixed bag of situations with different experiments and ever changing assumptions that go nowhere and that may or may not ever happen. Someday in a year or two the topic or one similar to it will come up and someone, not me, will say, “hey, it’s not that you aren’t seein what you think you are seeing, it’s that your perception of horizontal vs vertical is skewed”.

Hi Walter, I totally agreed with your post and am quite aware of that. Hence the requirement to film from the side. I had no intention of filming from my perspective of course, but if I can find such a location, to film from the perpendicular using a drone.

Cheers, Paul

[Walter]

Hi Walter, I totally agreed with your post and am quite aware of that.

Normally the way you say you agree with someone’s post is to say something like, “I agree with what you’ve said”. After that adding the bits about changing directions or clarifying something makes it clear that you are still within the realm of the original topic but there is some aspect that you wish to explore further.

[Paul Arden]

I should have done that Walter. Apologies. It was a discussion from last month and I was in part refreshing my own mind too!

Cheers, Paul

[Walter]

Nice of you to say that Paul. Thank you.

I’m going to break a rule by going off topic to, ironically, talk about going off topic. One of my pet peeves with the Flycasting Physics is that it purports to be science based but the very first thing it abandons is the scientific method which is the heart of all science based discussion. Far too many discussions are started with few or no assumptions. Occasionally some one will ask about the initial conditions but that is rare and they are never thought of again. It seems to be a contest at times to find ways to undermine a conversation by changing assumptions or changing a limited topic of discussion into something about some unified theory of casting. A really common one is constantly flip flopping between line being shot or not and the flips often happen without stating that the flip is being made.

I highly commend Torsten for introducing standard definitions and I know that he has a nightmare trying to keep things on topic or to convince people to start a new thread when appropriate but I also see far too many people saying that it’s a public forum, get over it. Yes it’s a public forum but it’s one that purports to be science based.

Done with going off topic. If anyone is interested in discussing the scientific method how to improve things I suggest starting a new thread but I’ve said my 2 cents worth for now.

Thanks

[Paul Arden]

Yep fair enough Walter. In the past one of the more fun things about Board discussions was going off topic. However I agree in the physics forum this may not be the best approach. So we should avoid doing this

Back to topic, I’ll see if I can get some video. I suspect it’s going to prove Graeme right by the way. I was studying some loops about a month ago. Where I have been unsure of is one of two things happen…

Either a horizontal thrown fly leg falls directly under the influence of gravity. Or skin drag forces help maintain its height.

That’s really what I’m looking for. And can be measured in the way I suggest by comparing the descent of a fly leg angled with the horizon (or slightly below to the sure) compared to the free-fall approaching or following loop straight.

Cheers, Paul

[Walter]

There’s the issue of going off topic and there’s the issue of purposely changing the assumptions or parameters without explicitly stating so just for the purposes of undermining an argument.

Your post is what I consider a better approach. Your hypothesis is that an unrolling loop doesn’t fall as fast as an equivalent amount of line, held straight and near horizontally. You feel that the cast needs to belong enough to actually show this and that the backcast (and maybe loop shape?) affect this. Is that it? Is there anything I’m missing or overstating?

Given this people can help formulate a reasonable experiment that would provide some definitive answer. I like that.

While you are at it I would suggest that this experiment could help the push me pull you discussion. If the loop is pulling the fly leg then the greater the angular momentum in the loop the farther the cast should be able to go given enough height to fully unroll without hitting the ground. So maybe some clever person can determine what conditions provide the maximum amount of angular momentum in your loop. You could then see which casts go farthest based on loop momentum. I expect that distance will not satisfy everyone so maybe final line speed? Maybe some other measurement such as initial speed vs terminal speed? Don’t know at the moment but, in my opinion, that’s the sort of thing this board should be trying to help people work out.

Cheers

[Paul Arden]

Indeed that is pretty much it, Walter. The cast’s flight time needs to be long enough to give the line sufficient time to appreciably fall.

What I think I see is a long loop unroll without much deviation in height. But once it has unrolled it falls quickly away.

To put this in perspective I’ve spent hundreds of hours casting off cliffs, high platforms and occasionally even mountain tops. I know that makes everyone a bit strange who doesn’t do that but I can live with that.

It may well be that an unrolling loop falls away at the same acceleration as a dropped line. To me it doesn’t appear to be the case, could be perspective, could also be an angle change between back and front casts as Graeme proposes. Certainly I don’t see how the loop front can support the fly leg, which was one such proposal.

So if it exists I would think it has to do with drag. If it doesn’t then we/I can put it all to rest and tell everyone to aim higher.

—

The two dropped chains off a wall, for me at least, indicated that both push and pull exist.

Cheers,
Paul

[Walter]

I think any long cast takes on the order of a second to unroll. That should be plenty of time to see if there is any difference in fall rate without having to find a tower to prove otherwise.

I think the issue is more about what you are measuring and whether it has any application to casting.

It has been pointed out that the line isn’t a single point so Newton’s laws may or may not apply. They apply. Let me repeat that strongly - THEY APPLY! Unless you are in the realm of very fast (relativity theory) or the very small (quantum mechanics) THEY APPLY. It’s just that when you get away from point masses you first have to look at the Center of mass (like in the falling slinky experiment) and then whether the distribution of the mass has any affect (such as when we have a coin on a the free end of a lever where the other end is constrained to rotate only. Releasing the lever we see that the free end falls faster than the coin that was resting on it). These two examples are predictable and explained with Newton. Anyone who disagrees does not actually understand Newton’s laws like they think they do.

What does that mean when talking about an unrolling fly line? When we look at the sum of forces and the Center of mass as the distribution of the mass changes we can understand and make reliable predictions about what the line is doing. Dropped feathers, fly lines and lead balls all fall through the air at different rates. Except for the fly line part Galileo showed that a long time ago.

We all accept that fly lines fall slower than lead balls and that air resistance (drag) is the main reason. Is there something creating extra lift that makes an unrolling line fall even more slowly than just a dropper section of line?

Some sort of wing affect because of the shape of the loop? Possibly, but on the order of so small we’re almost getting into the quantum realm. Something like a javelin where angle of attack is a factor? Possibly, in fact likely, and significant enough to take it out of the quantum realm but not enough to make a significant distance in the cast even for someone who wants to maximize distance.

I suspect that what you are really more interested in is whether mass distribution as the line unrolls can affect your casting distance to any significant degree and if you can affect that changing mass distribution. I personally think that has merit because we know the distance is measured at the fly, not the farthest point the line reaches, so one of the ways of increasing distance is to put more line in the air and get it to fully unroll rather than collapsing. We all have a personal wall where we can get the line to unroll and adding the tiniest bit of line beyond that results in a collapse instead. The standard answer to that is that we simply need to practice, add more speed and things will improve. But there is always the nagging suspicion that, just like the javelin, there might be something else I can do to optimize distance instead of just trying harder.

The flying fly line concept may be personally interesting to some but certainly not worth getting worked up about.