Overhang, Loops and Post Loop Flight - Shooting Head Physics

Aitor · Post by **Aitor** » Sun Apr 05, 2009 3:02 am

robk wrote:Ian:

So is shooting line friction ( in the guides) or mass the most important factor in making the head unfurl properly?

Rob

Rob,

I think that this proves that friction isn't the key. Don't you agree?

Ian Walker · Post by **Ian Walker** » Sun Apr 05, 2009 5:30 am

So is shooting line friction ( in the guides) or mass the most important factor in making the head unfurl properly?

Rob

Hi Rob,

The only thing I am sure of is that a high speed loop with the 300g hi-density head and 15' of running line that I used in my test casts will completely fall apart very quickly (my crude estimate would be 70 to 80 feet in front of the caster). The resulting spaghetti may travel some distance after the loop falls apart.

So at least for the type of casting I'm doing, the resistance of the running line is essential for maintaining the shape of the loop beyond 80 feet.

Best regards,

Ian Walker

Lasse Karlsson · Post by **Lasse Karlsson** » Sun Apr 05, 2009 6:58 am

robk wrote:Lasse:

Was your head a HiD, Int or floater? I can't see the line

Ian:

So is shooting line friction ( in the guides) or mass the most important factor in making the head unfurl properly? I may try to play around with different shooting lines tomorrow, to see if I can duplicate any of these results.

Rob

Hi Rob

I used a floater. It turns to spaghetti when my tracking is of. As soon as I make a clean delivery, it just flies straight and in a nice loop turning over.

I'm in Japan at the moment, but will be home next week, I'll make some casts with a high density leadcore shootinghead and see what happens there

Cheers
Lasse

Ian Walker · Post by **Ian Walker** » Sun Apr 05, 2009 11:53 am

Hi Aitor,
In your excellent video, what tackle did you use (Rod, shooting head, running line type and length)? What was your casting technique (Hauling or not)?

It's very hard for me to tell from the video but it appears that the distance the fly travels in front of the caster is approximately 1.5 to 2 times the length of the shooting head. The flying spaghetti effect that I observe on my casts without a running line isn't really significant until the cast has traveled in front of the caster about 2 to 2.5 times the length of the shooting head. Under normal conditions with a running line my casts using the same technique would travel about 5 times the length of the shooting head.

Perhaps the length and time of the flight of the shooting head is a factor in whether or not the loop is stable with little or no running line.

Best regards,

Ian Walker

Magnus · Post by **Magnus** » Sun Apr 05, 2009 12:12 pm

Hi Ian
Does wind direction make any difference with the gear your using?

Ian Walker · Post by **Ian Walker** » Sun Apr 05, 2009 12:56 pm

Hi Magnus,

My casts were made outdoors and there was a slight breeze 1-3 mph blowing. Viewed from above with the forward cast direction as 12:00 (clock analogy), the wind was blowing along a line from 4:30 to 10:30. In other words a quartering tail wind from the right side.

Yes it's certainly possible that wind plays some factor in de-stabilizing the loop in the test casts I made with no running line. Unfortunately it will be difficult to eliminate this factor from my test casts. I can easily reduce the effect of wind by casting early in the morning. The wind at this time would probably be between 0 and .5 mph. Indoors would be better, but its hard to find an indoor venue with 200' of room (50' for back cast plus 150' for forward cast). Also my experience is that even indoor venues have surprisingly strong air currents.

My gut feeling is that wind is not the main cause of my test casts de-stabilizing. But my gut feelings aren't too reliable for predicting something as complicated as the flight of a shooting head which probably requires both mechanics and aerodynamics to completely explain.

Best regards,

Ian Walker

Aitor · Post by **Aitor** » Sun Apr 05, 2009 1:09 pm

Ian Walker wrote:Hi Aitor,
In your excellent video, what tackle did you use (Rod, shooting head, running line type and length)? What was your casting technique (Hauling or not)?

Hi Ian,

I thought that the .gif I posted was an interesting model in order to understand a "free loop" mechanics, but I see is no use. Sorry.

My best.

Ian Walker · Post by **Ian Walker** » Sun Apr 05, 2009 1:28 pm

Hi Aitor,

I don't understand why your saying your video isn't relevant. Would you mind explaining a little more? Thanks for the effort, even if the video isn't quite right for this discussion.

Best regards,

Ian Walker

Aitor · Post by **Aitor** » Sun Apr 05, 2009 2:15 pm

Ian,

The video shows that in order for the loop to unroll isn't necessary any friction of the line with the guides. But you are right, that isn't relevant for this discussion.

My best.

robk · Post by **robk** » Mon Apr 06, 2009 1:31 am

I think that this proves that friction isn't the key. Don't you agree?

Aitor. I am not sure what I am looking at. I think it is a section of bead chain being looped across a table top. Is that correct?

So at least for the type of casting I'm doing, the resistance of the running line is essential for maintaining the shape of the loop beyond 80 feet.

How much has your head unfurled at 80 feet out? Would it be about 40 or 50%? If so, I am going to indulge in some wild speculation

My guess is that at that point the forces acting on either side of the loop equal out, which causes the loop to stall. Air resistance on the face of the stalled loop then lowers its velocity relative to the two legs. The result- spaghetti.

Am I thinking along the right lines or is this just another load of bollocks

BTW. I did not get a chance to do any line experiments today. Decided to get a mild Flu instead....

Lasse Karlsson · Post by **Lasse Karlsson** » Mon Apr 06, 2009 2:55 pm

Hi Rob

We accelerate the whole line/shootinghead in one direction, at the RSP/CF the loop is set, and the part of flylin closest to the rodtip changes direction, the loop is started. At this point the majority of flyline has been pulled in one direction while a small part is stalled. For the topleg to stall in the air, there has to be more resistance in it than the bottom leg. If a shooting head made of floating line won't stall unless casted into a headwind, why would a sinking one?

Cheers
Lasse

robk · Post by **robk** » Mon Apr 06, 2009 3:28 pm

For the topleg to stall in the air, there has to be more resistance in it than the bottom leg.

Lasse:

I can see that maybe stall was the wrong word. What I meant was that the loop stopped turning. Both legs of the line would have equal forward velocity.

How long is your shooting head ? Is it 30 feet, like the ones Ian and I are making pasta with or is it longer?

Lasse Karlsson · Post by **Lasse Karlsson** » Mon Apr 06, 2009 7:22 pm

Hi Rob

The one I used for the clip is 35 feet, I can try something like 25 feet if it makes a difference

Cheers
Lasse

Lasse Karlsson · Post by **Lasse Karlsson** » Tue Apr 07, 2009 7:43 pm

Ok, went out with a 30 foot type 2 sinker of 300 grains this afternoon.

Didn't see how far I could chuck it, but went straight to letting it fly on it's own. I had 15 feet of 17 lbs shootingline on it, so I could haul it and give it greater speed than with just letting it fly like I did with the floating one.

I didn't get any spaghetti, instead I got a nice loop, unfurling completly, and then someting interesting happened. There was still quite alot of momentum left in the head, and after it had straightned completly in the air, I got a second loop, now forming the other way around from the fly and back into the shooting head. And the second loop even unfurled on one of the casts, making the backend the furthest part :O

No video, had enough of a hard time getting an orange line to show up today, so a dark brown was completly hopeless...

Cheers
Lasse

Ian Walker · Post by **Ian Walker** » Tue Apr 07, 2009 8:21 pm

Hi Lasse,

What your reporting with the 300 grain type 2 sinking head may not be too different to what I observed with the 300 grain tournament head. I think the loop may unroll completely before the cartwheeling begins.

It's very hard for me to observe accurately what is happening with the casts even during the day. The loop travels so fast, especially for the first 70 to 80 feet where most of the action seems to happen, and the tournament head is a light gray color that blends in very well with the sky.

So maybe what happens with no running line attached is that the shooting head unrolls faster than with a running line? There is a lot of tension on the lower (rod side) leg of the loop. Normally this tension is used to pull out the running line. However if there is no running line attached, then perhaps the tension on the lower leg causes the loop to unroll from the bottom as well as the top.

Kind of a wild theory but its all I got right now.

Best regards,

Ian Walker

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