# The Dzhanibekov Effect

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If you are prone to headaches, you may want to skip this post.

The Dzhanibekov Effect, also known as the intermediate axis effect or the tennis racquet effect. Is a fairly new theorem of motion, but one that we have all experienced at some time. Me personally, as a table tennis player in my younger days, when I would flip the bat in the air and observe how it rotated 180° before being caught. I would repeat this action over and over, marveling at the motion and never giving it a single engineering thought, but at that time I was just a school kid and not an engineer.

I am not going to try to explain this motion. I will leave it to the linked video for that.

The reason that I am posting this rather obscure enigma is that I believe that there is a possibility of a new lure motion, one not yet discovered. I am thinking about prop lures that travel in a straight line.

There might be something here or not, but as I do not have a workshop, other than casting out a few brain cells at the enigma, I am unlikely to work the idea in the near future. So, rather than keeping the idea a secret, I decided to put the idea out there to y’all and see what you think.

Anyone who thinks that there is nothing new in lure design is sadly mistaken. I firmly believe there is a lot more out there to be discovered.

Dave

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Another amazing post by an amazing thinker , Thank You !!

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I am one of the OLD DOGS I don't know what you are talking about. Just what is this lure going to look like. That would help at least me..

Wayne

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Thanks Dave.  That was a fun video, and a very interesting phenomenon.  It certainly got my head spinning.  :O)

In order to use this idea in a hard bait, I think it would have to have a partially filled liquid interior.  Larry Dahlberg once told me that liquid mercury had been used in the past to get a bait to hunt.

Or maybe a spinning interior ballast that was just off of the lure's major axes.  But I don't know how you would get it to spin without some kind of a motor and power source.  I think this is a job for Livingston Lures!

Edited by mark poulson
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Well, a completely flipping lure might not be a desirable thing but the moment of inertia on that axis might be minimized so that it could wobble around that axis. I don't know what the fish would think... but it's certainly interesting.

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Ravenlures - I have little idea what this is going to look like so far, sorry.

DGagner - The lure would never be able to totally flip. But, if the lure tries to flip then this would induce a change of direction. I don't know whether this would be random in direction or whether it could be controlled.

Mark - The fluid idea would make the lure want to move, with the whole body spinning. I was concentrating on the mechanical effect rather than the liquid idea, but why not.

Dave

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I have given this intermediate axis lure a lot of thought over the last few days, to see if I can come up with a design that actually looks like a lure. This is the only one of several solutions that works aesthetically.

But, before you get your tools out, I must warn you that this is probably my most outrageous, hypothetical post I have ever put out there. There are so many unknowns and ‘what ifs’ that the chances of actually getting this lure to do what I want it to are very slim at best.

Referring to the video that I posted above, this lure is based on the failed satellite (12’35”). The lure spins around its long axis and the side hooks represent the flexible satellite antennae. The rear hook is optional. As with the satellite, the rotating side hooks make the lure want to rotate end over end. Obviously the lure being towed, this is not possible. But, if the lure tries to tip then this would change the direction of the lure, and this is the object; to impart a random ‘hunt’ motion to the retrieve.

Problems, what ifs and maybes.

1 – The satellite was operating in a vacuum, the lure is operating in water. This alone might be enough to cancel the project.

2 – The lure is being towed as opposed to floating freely in space. This too adds forces to the lure that may well be too much to allow the change of direction.

3 – I am not even sure whether this lure obeys the intermediate axis theorem. This will need more thought and calculations.

4 – I have positioned the lateral hooks at the COG. This may not be the optimum. But the swim of the hooks may well move the COG further aft and spoil the effect.

5 – Will the lure spin fast enough, or too fast, will it spin at all.

I see this lure as a slow sinker, so ideal for a resin pour in a silicone mold.

I was asked what the lure would look like, so here is your answer. I do not have a workshop or a 3D printer, otherwise I would have a play for sure. I am putting this out there for interest. If any of you want to experiment with the idea then knock yourselves out, but I refer you back to the second paragraph, this may be a total waste of your time.

What we really need on this project is input from a NASA scientist, so go through your contact lists and see if you can help

Dave

Edited by Vodkaman
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What about a center section that rotates, so it can be somewhat independent of the lure body, like a mid-lure whopper plopper, but with balanced props?

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Yes, I did think about your Whopper Plopper. I simply don't know whether it is necessary to rotate the whole body or not. It would be a better solution for sure, I really don't like the flailing hooks.

Dave

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Mark - I had a sleep on it, and yes, the whole body must rotate.

Dave

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Enjoyed the video as it is and action I have looked at in the past (not for lures) and have always enjoyed toys that seam to defy physics.  Tippy tops and rattle backs have long fascinated me.

Interesting concept lure.  I would point out that while your are tackling a new motion you also must take into account fish ability. Always something new in design the true question is does it perform better than what is available.  Lure makers have a tendency to forget that making something different looking isn't that big of deal making a lure that performs is the key.

The early 1900's every lure manufacturer slapped hooks everywhere on a bait: Dowagiac Minnow  #00 (1930), Wizard Minnow (1903),  Monarch Minnow (1903 and could screw off and on hooks into cavities),   William Shakespeare Jr. Fish Bait (1905), and countless others.   History has shown the multiple hook set ups are a no go.  Why is that?  Simply the concept was not beneficial to catching fish.  Hang ups were common, line tangles, and missed fish (hook up ratio vs hook position plays vital role).

Design it without the counter balanced treble hooks and create the needed "wing nut"  either in body shape or just internally weighted along the proper axis (another issue to overcome) and just go with a single rear hook.  Additionally you have a static variable this way.  Swinging hooks relative to the static x axis creates countless issues in regards to establishing the needed instability and centrifugal forces to flip as they would seek the low energy position/state and increase the needed force to get the lure spinning.    Just a body spinning around the x axis has also been done.

Commercially the spinning body along the x axis didn't make it either.  It was however popular with DIY lure makers.  Common design observed in "folk lures" of the early 1900's from individuals that would have been at home on this site.   Tom Shepherd is featured frequently for his "spinner" lures.   There were also some metal lip "cork screw" baits that intended to rotate the lure around the x axis.  Some designs had dual spinning bodies that were in line but counter threaded.   Maybe Roland was onto something with his helicopter lure.

None of them achieved the action and fairly confident that your points 1 and 2 from above eliminate the possibility in the real world.    The retrieval speed will never be sufficient to generate the RPMs to achieve the centrifugal forces needed to overcome the counter forces exerted on the bait by the water.  Additionally going to be hard to internally weight a lure body to achieve the intermediate axis theorem conditions.  I don't think the spinning momentum needed can be reached without battery powered mechanical intervention to  get the lure to flip in water and definitely not on commercial tackle we use.  If the lure will even just start pump up and down on the retrieve would consider that very successful.

For proof of concept might as well not start by trying to not redesign the wheel. We know, video excellent example that the "wing nut" even in the ball of clay resulted in the desired results.  Seams like much easier place to start is that known entity and weighting of the x, y, z axis core.

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I too am not happy with this first presentation. I do not like the hooks thing either.

I am probably going to leave this project on the shelf until I get any more ideas. I am going back to my triple point lure project for now, with the aim of actually building something.

Dave

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Hmmm.... I've followed this but don't really understand what the final end goal is beyond a new lure movement. Spinning a lure to initiate a wobble (can't flip it because it's being tethered from the front). I'm wondering that if this is the case there might be easier methods of having it look like the same action by simpler methods. Or rather. This is a 'maybe', but I can get a lure to do this by mistake.

I've made deep divers that had the bill and hang point put on wrong. a wobbling spin was the result.

Maybe I've missed the point.

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DG - I don't think you have missed the point, neither of us know where this theory of motion could lead. All I am doing is pointing out a new theory of motion that has never been explored before.

In my best optimistic imagination of the possibilities, I see a spinner type lure that would normally only travel in a straight line, that would actually periodically deviate from this line. It could be zigzag or random deviations. It could be side to side, up and down, or totally random.

I have proven to myself, to my satisfaction, that lures that deviate from a straight line retrieval are more successful. My entire time spent while associated with TU has been all about 'hunting lures', fishing lures that do not swim in a straight line. There is a very good evolutionary explanation for this.

Fish have two types of muscle. One for regular swimming, capable for swimming all day for long periods, and a second type of muscle for attack purposes. This second muscle is only capable of a short period of use before it tires and becomes useless.

Consider the prey – A predator is close by. It has only one chance to use its power muscles. If it fails to escape then it is food. Its best plan is to keep a distance and dart during the attack.

Consider the predator – It knows that if it lunges then the prey will dart, changing direction to avoid the kill. Evolution teaches the predator to cause the prey to dart prematurely, expend its escape energy and then pounce.

The proof – we have all seen predator fish follow our lures back to the boat without taking a bite. The predators are waiting for the prey to make its move. We all know that a straight retrieve is rarely successful. We must work the lure in order for the fish to bite. My aim is to design a lure that is capable of attracting the bite on a straight retrieve. But more than this, a lure that hunts will react more violently when worked.

Many on this site will knock the idea of hunting lures. But, they are already employing the principles of the change of direction theory with a great deal of success. This is the skill of the lure fisherman. What I am trying to develop is a more efficient and more violent change of direction.

Fish are not thinkers, they work on instinct. As anglers, we must embrace these instincts, or as most do, learn from experience. If you tweak a straight swimming lure, it may not get hit. But, a lure that shoots off to the side when tweaked has more of a chance of arousing those attack instincts in the predator.

I have posted this idea many times, so am guilty of repeating myself. But I feel that this is important theory.

Dave

Edited by Vodkaman
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I understand. It's an interesting approach. And a novel idea. If built It might have that hunting action during retrieve. I just think as a mental exercise It's always fun and novel to contemplate, which is what is going on here, but I'm just pointing out that it should be simpler to achieve by other methods.

It would be fascinating to work on an airplane that works by flapping wings, but it is be easier to obtain flight by other methods. Still the mental exercise, like is being done here, is fun.

Simply that I love this idea should it work or not. In reality though, the actual development isn't necessary.

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I think that this was fun, if nothing more than to remind me of my engineering physics classes in the early 90's, when we investigated this motion.

I am quite sure that the extra energy "absorbed" by the lure by towing it in the water will overwhelm the very minimal unstable motion due to the Dzhanibekov Effect.  Still, the TRUE scientific method allows us, even requires us, to consider alternative interpretations to what we think we know.

Thanks for the mental exercise, but I don't think I will be joining in on the development and design on this one.  LOL

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This is an interesting topic. Going through Helicopter flight training this same motion was well discussed. Only to achieve the opposite results "Autorotation" . The forces of this theorem is to have the center of gravity move in a controlled manner similar to a navigational gyro. This could be very costly. Physics  is the plane of finding how to control the action, in a constant manner. Good luck.

By there were a few helicopter pilots, that  have  come very close to this. But the successful ones didn't survive, either the extraneous forces, or the violent impact.

Edited by Fishin Big
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It is one of those strange things that has been around for all time. We have all experienced it at some time. Everyone who has ever picked up a table tennis paddle has seen the effect when they toss the paddle up in the air, watched it flip over and then caught it again.

So well was the movement known that science forgot to look at it and come up with an explanation.

Dave

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@Vodkaman Dave, I believe strongly in the principles of change of direction when lure fishing for predators. There is a great bait on the market now from a company called Gunki, which I am sure you are familiar with. The lure is called the Scunner and is a jointed hard bait with a very slow sink rate. A slow retrieve sees the bait behaving like a swim bait with a smooth glide, but give it a hard twitch and the bait flies off to the side as if darting away from impending attack. I have been very successful using these baits and am going to attempt replicating one in the future.

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I haven't tried a hard twitch in my test tank, but a light twitch will make the lure turn 90 degrees.

Dave

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this is quite interesting. If anyone can figure out the holy grail of fishing lures, im sure it's vodkaman.

vodkaman, you mentioned you don't have a 3d printer. recently, I've been thinking about purchasing one. If in fact I do purchase one, id be happy to print any of your designs if you'd like.

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Just now, Leo's Lures said:

vodkaman, you mentioned you don't have a 3d printer. recently, I've been thinking about purchasing one. If in fact I do purchase one, id be happy to print any of your designs if you'd like.

That is a very kind offer, thanks.

The problem is the postal service. They always charge me some fee or bribe, on top of the already ridiculous cost of postage. This is why many organizations will not deal with Indonesian customers.

I don't source anything overseas any more.

Dave

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2 minutes ago, Vodkaman said:

That is a very kind offer, thanks.

The problem is the postal service. They always charge me some fee or bribe, on top of the already ridiculous cost of postage. This is why many organizations will not deal with Indonesian customers.

I don't source anything overseas any more.

Dave

You're right, that could be an issue. If you wanted, I could print your designs and test them w/ video. I might build a special testing tank if I get the supplies. I also have a hot tub that I use currently to test my lures in. We would have to consider the temperature of the water may cause interference.

Currently I am trying to learn how to 3d model my own lures. My biggest issue is with the aesthetic details (gills, scales, fins) It can be quite frustrating to try and get the results you want as a beginner.

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1 minute ago, Leo's Lures said:

Currently I am trying to learn how to 3d model my own lures. My biggest issue is with the aesthetic details (gills, scales, fins) It can be quite frustrating to try and get the results you want as a beginner.

A basic CAD body shape from scratch can take a couple of hours CAD work, but once you start modeling gills, scales, fins and other details you can add a zero to that time number.

Personally, I don't bother.

Dave

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7 minutes ago, Leo's Lures said:

My biggest issue is with the aesthetic details (gills, scales, fins) It can be quite frustrating to try and get the results you want as a beginner.

Don't worry about that stuff design a lure that works. Then start adding the variables.   Gills and scales aren't usually an issue (ok scales can interfere with hook swing and cause premature wear/hook rash).   Fins... depending on design can kill lure action, reduce hooks ups,  pick up aquatic vegetation, get tangled in branches, reduce casting distance, etc...

The more experienced an angler becomes the more one finds out many lure makers make really pretty lures.

Edited by Travis

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