At the end of the day, you have to decide what properties are important to you and design your lure accordingly, the hard part is getting it to do what you want it to do, rather than saying, ‘that’s nice, I like that’.
Thanks Everybody. I had not really paid attention to other movements until I started with a deep belly flat side design. And.. Yes I got what you are calling the X thing going on. It was the hardest thing to control that I had come upon. It may not be a fishcatcher but it is fun (Frustrating) to play around with. Now I have some other movements to look at I had not even thought of. The tweaking goes on! And since I said the action behind the bill...Is the bill doing the same thing the body is doing but in a much tighter fashion? I guess it is since it is attached to the body. Why have I not looked at it that way before? Thanks Vodkaman for waking up my brain!
Placing the weight in the keel or the lowest point of the body is my preferred choice. It gives good static or motionless stability as the centre of mass and the centre of buoyancy are kept as far apart vertically as possible, the lure will stay upright. This is also a good arrangement if you are looking for yaw action or 'waggle'. The ballast centre is lying on the z axis, therefore their is no moment distance to hinder the motion (re the stick experiment in my previous reply), the towing and water pressure forces prevent the waggle from becomming unstable. However, if you are looking for roll or wobble action, a low slung weight will reduce the wobble due to its offset distance from the wobble axis (x axis). If you move the weight up too far ie close or even in line with the x axis, the roll will become unstable and turn over.
Once the action or movement has started, their has to be a force to stop it or it will continue. In the case of yaw or waggle and pitch or porpoise, it is the pressure of water. In the case of roll, it is the vertical stability caused by the distance between the centre of buoyancy of the wood and the centre of gravity of the ballast.
Instability As with the ballast instability, for each type of movement (yaw, roll and pitch) their is a point of no return, an unstable condition. Unfortunately, if you are searching for a maximum effect, this occurs just before the unstable condition takes over. At this point, the lure no longer returns to centre but continues its movement and rotates about its particular axis, out of control. The point at which all these instabilities occur is at the centre of forces, where all the axes intersect.
Yaw and pitch instabilities are most unlikely ever to be experienced unless you position the line tie half way down the back. At which point the line tie would coincide with the z axis and the yaw or waggle would become unstable. The line tie would be at its closest to the y axis, therefore the pitch or porpoise effect would be at its maximum, close to instability.
Roll instability This is the biggest cause of lure failure. The lure spirals out of control. Some call it 'death roll' and to be brutally honest, I am still trying to get my head around it. Explanations have been posted but I have yet to be convinced of a good explanation. In keeping with the previously discussed instabilities which are easy to picture, including the ballast instability, then the roll instability must be tied in with the intersecting axes, the centre of forces.
Unfortunately, this majic point takes on a new life of its own once the lure is moving as more forces are acting on the lure, therefore its position moves accordingly. At this point the brain starts to hurt. By far the main force that changes everything is the weight of the water acting on the lures surfaces. Another force to join the mix is caused by curvature, the same type of force that allows a wing to lift a 747 off the ground and is not to be ignored.
So, after all the technical research, prototype experiments and discussions, I am no closer to predicting roll than when I started all of this, several months ago. But when I find a lure that rolls, I get a little excited, an opportunity to search for the explanation why. I would like to collect everyones 'rollers' and continue the search.
I would definately like to hear everyone elses opinion on roll over.
So...x-ing is half roll and half yaw? A Bagley B or square bill would be mainly yaw? I have taken the tail and moved it up above the x axis and it seems to have knocked alot of the roll off. Does that make sense? I was allready maxed on weight. I still may have to change the bill angle. Trying to tweak it so it runs at all speeds. I guess it is better to have too much roll and come down from there than to start with none at all. Thanks for the last post, that has the information I need. Maybe no anti-depressants tonight!
With a lure shape like that, it is dificult to know exactly where the x axis ran. If it had good roll before the mod and the roll reduced after, then the axis probably ran through the tail. This would be good design.
By raising the tail, you have pushed it 'into the wind' as far as roll is concerned. You have introduced a side load with a distance from the rotation axis and stifled the roll action (re-the stick and weights experiment). Unless I am misunderstanding your modification.
I think another part of the roll equation maybe the fact that a lure acts somewhat as an airfoil. The airfoil is "unbalanced" by the lip as you begin the retrieve, creating lift on side of the bait. When the lure begins it's motion to the right say, you need enough "lift" in the body of the lure to counteract this right motion and send it the other way. If the body does not have enough surface area, or the lip creates to much pressure, the lure will simply continue to spiral.
Roll instability This is the biggest cause of lure failure. The lure spirals out of control. Some call it 'death roll' and to be brutally honest, I am still trying to get my head around it. Explanations have been posted but I have yet to be convinced of a good explanation. In keeping with the previously discussed instabilities which are easy to picture, including the ballast instability, then the roll instability must be tied in with the intersecting axes, the centre of forces.
Vodkaman, I'm no physicist, but your explanations make some sense if you read carefully. In the near death roll I've seen, it was a combination of factors.....
1) Balsa wood....very bouyant, but used too little weight to offset the flat side design. If you throw a piece of wood into water, it will float flat side up.
2) Jointed bait....not really sure how much the jointed action made it different. But this was different from any I've seen.
3) What I call "obtuse" lip angle. The lip angle was near "vertical" on the Z axis. Basically near the angle of topwater, but slightly skewed out to dive angle. And the lip was too long for that design. Trapezoidal shape rounded at corners.
Bottom line, near death roll. This bait will swim normally at slow speed, and then kick on it's side and flounder on the top of the water at higher speed.
A failure by our standards, but just the kind of thing that might trigger a huge fish to strike.
AGREED!!!
