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Question for vodkaman
17 replies to this topic
Posted 18 February 2008 - 09:16 PM
Dave - I have allways assumed the rules would be basically the same for air/water flow over a lure in relation to "Wing effect", assuming the lure is roughly the shape of a wing cross section and has neutral buoyancy in water- am I on the right track ? OR am I going down a dead end alley? I posted this instead of PM you, I thought it may be also of interest to others.
Only go a deep as you have to here. Just wondering. pete
Posted 18 February 2008 - 11:31 PM
You are correct. In fact, the effects are very strong in water. When I started all this, the application of aerodynamics was my first plan. The problem was, I could not find the oscillation (wiggle).
I figured that if I curved one side, it would step out into the flow, reach a stall condition and fall back. This did not happen. The lure stepped out until the stall was reached, it would then reach a balanced condition and swim to one side. Failure.
Only then did I examine existing lipped lures. My aircraft background told me that the lip would just create turbulence. So I googled turbulence, which lead to vortex,then to vortex shedding, Karman vortex street and within an hour, I had the complete(ish) story.
Curvature can be used as part of your design, by adding or subtracting it from the back or the belly. A curved or domed back will raise the dive angle and reduce the size of the lip. But you may want more lip for more action, so reducing the back curvature may be the solution. At the end of the day, the lure has to balance the fore/aft forces, top curvature is just another factor.
Vortices are a major part of flight theory, generally, we try to reduce the vortices to zero and use the laminar flow to obtain pressure differences above and below the wing to generate lift. But only now are we learning that the birds cheat. They use laminar flow, but also utilize the energy in the vortex flow. In fact, insects fly purely off vortices.
The only commercial aircraft to utilize vortices was Concorde. The swept wing created a massive vortex, which sucked the wing upwards. Once the craft gained speed, laminar theory took over.
If you can find a way to make laminar flow make the lure swim, I would like to hear about it, as so far I have failed.
Posted 18 February 2008 - 11:59 PM
Never mind, Vman. My question was answered in another thread a little farther down the page.
Posted 19 February 2008 - 04:05 AM
Thanks for that Dave - No I don't have a solution to vortices unfortunately, but the laminar bit answers some problems I have, I think. Thank you again. pete
Posted 19 February 2008 - 04:45 AM
Pete, just keep one thing in mind when you study planes over lures. Air is compressible whereas water is not and much denser. The other is the speed at which the effects will take hold. Enjoy your discoveries and long quest to understand all this hydro stuff.
Posted 19 February 2008 - 12:07 PM
Interesting note on vortexes and flight: The Russians designed and made a plane that utlilized wing vortices to fly several feet off the water. The lift was predominately or totally create by the compression of wing vortices against the water.
Posted 19 February 2008 - 03:58 PM
A couple of quick things...
Water is a compressible fluid
and I saw an episode on that cold war thing KcDano! It was for an invasion force for the US. Speed like a plane but could carry like a cargo ship! But then the Politboro changed and the inventor lost his supporters...Crazy!
Posted 19 February 2008 - 04:04 PM
The Ekranoplan project.
I think some entrepreneur started making small versions in the US. I saw a documentary on the subject a few years back.
Posted 19 February 2008 - 06:19 PM
Just a strange little thought. I am sure someone has thought of this before. If you could build a bait that could have some type of propulsion system to drive or swim the bait towards the bank, structure or even parallel to bank. Wow what a cool concept. Just think if you had a bait that could swim up underneath a dock or something like that. There is very little fishing pressure underdeath docks, you can skip soft plastics underneath their. Or cast close with spinnerbait, and cranks, but imagine the potential of letting one go from boat and swim right up underneath the dock all the to the back of the walk board. And swim towards the fish. Theres a million dollar idea. Anyone here a expert on mini propulsion hydro motors/submarines.
Posted 19 February 2008 - 07:53 PM
I'm sure every progressive thinking lure designer has given this one a thought for about five minutes, so here are mine.
The propulsion would have to be at the front, because of weight distribution. My idea was a driven prop to draw water in at the nose, into a tube or cowl. The prop would be inside the cowl and not visible. the tube would split into two and vent out the sides at an angle, thus driving the lure forward.
The motor would be switched on and off by a water resistance cmos switch, so it only operates when wet, saving battery power.
Problems. Size, power, sealing the electronics, battery replacement. These are not major problems, easily solved with a little creativity. The main problem is the the water jets would be rotating in opposite directions relative to the body, out of the exhaust vents and will probably cause some rotation of the body. This too could be designed out. But the main problem was that the driven water would kill any vortex driven action and it would probably swim like a lively log!
I moved on to the next idea.
Posted 20 February 2008 - 12:40 AM
I thought I had that one covered already. It not only is self propelled, it carries 12 fish! The Wolf-Pike
Posted 20 February 2008 - 12:48 AM
Pete, I don't follow your links!
So, are we designing a fish now?
Your design inginuity combined with some of the paint artistry on this site, next years bass masters is in the bag.
Posted 20 February 2008 - 03:00 AM
Dave - there was a post here this afternoon on a do dah that you hook on the line and it makes a lure plane sideways (like a planer board), called a BobBop or something. Apparently they have been around for a while, looked like a good idea. I suspect it was an ad rather than a post and has been removed. pete
Posted 20 February 2008 - 03:13 AM
Yes, Pete, That post went bye bye! The basic design has been around for some time.
Posted 20 February 2008 - 03:32 AM
Its shape relative to the line causes it to swim at an angle, a bit like towing a lure from the side. The bubble is filled with water to give it casting weight and so sits low in the water. When it is jerked, it topples over itself and a steady retrieve will now cause it to swim the opposite angle. Thus you could guide it into normally inaccessible areas of the lake, such as reed lines.