DRAGENSTEIN

[Three se7ens]

To the original post:

Look up 2nd law of friction on your favorite search engine.   Friction is independent of surface area. What matters is the amount of force and the slipperiness of the surfaces.  It is really counter-intuitive.  The classic example is dragging a brick across a table.   It doesn't matter which side  of the brick is  on the table.  It takes the same amount of force to move it, even though the sides have different surface areas.  The reason has to do with the the surfaces  not being  flat at the microscopic level.  If you double the surface area you might double the number of tiny contact points, but if the total force is not changed, the force per contact point is cut in half.  So you end up with the same amount of friction.  There is a more accurate  but complicated explanation of this phenomenon, but I don't understand it

From a strictly theoretical standpoint, adding  drag surfaces inside a reel increases the surface area, but does not change the force applied, or the coefficient of friction( slipperiness of the surfaces).      So this should mean that adding drag washers to a stack does not increase the amount of friction, so at a given amount of torque on the star,  the number of drag washers will not change  the actual amount of drag.

That does not mean that the drag stack does not perform better with more washers, or even that it might be possible to get a higher drag setting (perhaps by generating a better torque to lateral force translation).  But it does mean that any improvement in total drag for a given torque setting is not directly attributed to increasing the surface area.

Regarding diameter,  I think it works this way:   Going back to the brick analogy-   if you drag the brick around a  full circle,  the larger the circle, the greater the distance you have to drag the brick, thus converting more energy per rotation for a given amount of friction.   This presumes that the drag setting force can be applied to the outer diameter.  The larger the diameter, the trickier this can get.

In the end, we are converting kinetic energy ( motion) to heat.   IMHO we spend lots of  time thinking about how much heat we can generate ( max drag), and not so much, what to do with the heat.   Makes sense for setting up reels for quick stopping, but maybe not so much for extended runs.


-J.

Based on your brick example, youre missing an important point.  Drag is dependent on surface area and PSI.  With a fixed weight, PSI goes down with an increase in drag area.  In reels, thats not necessarily the case.  If you add drag area, while keeping PSI the same, you can increase the drag numbers.  My insert kits are a perfect example.  The 6/0 Sal tested went from 30 lbs? max drag with the stock cf drag, while my insert kit had a smaller diameter, but due to the larger number of active drag surfaces, Sal saw 74 lbs of drag with my kit.

[johndtuttle]

To the original post:

Look up 2nd law of friction on your favorite search engine.   Friction is independent of surface area. What matters is the amount of force and the slipperiness of the surfaces.  It is really counter-intuitive.  The classic example is dragging a brick across a table.   It doesn't matter which side  of the brick is  on the table.  It takes the same amount of force to move it, even though the sides have different surface areas.  The reason has to do with the the surfaces  not being  flat at the microscopic level.  If you double the surface area you might double the number of tiny contact points, but if the total force is not changed, the force per contact point is cut in half.  So you end up with the same amount of friction.  There is a more accurate  but complicated explanation of this phenomenon, but I don't understand it

From a strictly theoretical standpoint, adding  drag surfaces inside a reel increases the surface area, but does not change the force applied, or the coefficient of friction( slipperiness of the surfaces).      So this should mean that adding drag washers to a stack does not increase the amount of friction, so at a given amount of torque on the star,  the number of drag washers will not change  the actual amount of drag.

That does not mean that the drag stack does not perform better with more washers, or even that it might be possible to get a higher drag setting (perhaps by generating a better torque to lateral force translation).  But it does mean that any improvement in total drag for a given torque setting is not directly attributed to increasing the surface area.

Regarding diameter,  I think it works this way:   Going back to the brick analogy-   if you drag the brick around a  full circle,  the larger the circle, the greater the distance you have to drag the brick, thus converting more energy per rotation for a given amount of friction.   This presumes that the drag setting force can be applied to the outer diameter.  The larger the diameter, the trickier this can get.

In the end, we are converting kinetic energy ( motion) to heat.   IMHO we spend lots of  time thinking about how much heat we can generate ( max drag), and not so much, what to do with the heat.   Makes sense for setting up reels for quick stopping, but maybe not so much for extended runs.


-J.

Based on your brick example, youre missing an important point.  Drag is dependent on surface area and PSI.  With a fixed weight, PSI goes down with an increase in drag area.  In reels, thats not necessarily the case.  If you add drag area, while keeping PSI the same, you can increase the drag numbers.  My insert kits are a perfect example.  The 6/0 Sal tested went from 30 lbs? max drag with the stock cf drag, while my insert kit had a smaller diameter, but due to the larger number of active drag surfaces, Sal saw 74 lbs of drag with my kit.

It is not the surface area per se, it is the additional discs of a given radius that is the key.

[Robert Janssen]

I sometimes find myself wondering if anyone actually bothers to read previous posts.

The two criterion which greatest affect the sum total of drag are 1) the number of sliding surfaces, and 2) distance from center of rotation to center or mean diameter of friction surface. A third is of course coefficient of friction of the chosen sliding materials, but since we use a very limited number of materials in reels, this is of lesser interest right now.

...but due to the larger number of active drag surfaces...  

Yes, exactly.

follow the money....  

What? I don't get it. About the patent, you mean? Yes, the author of this article holds several patents for fishing items, one of them being a drag assembly using Rulon, which appears to be some kind of favorite of his, but he most certainly did not invent Rulon.

.

[Alto Mare]

Smooth drags is key.
I'm finding the best way to get smooth drags in most cases is by adding twice as many washers. A Delrin washer for under the gear helps as well. The star drag reel will give us that option.

The numbers mentioned above are for stress tests.
Testing a, let's say 9/0 with stock drags and comparing it to a 9/0 with Adam's inserts, the difference is amazing.
The 9/0 with stock drags will get jerky at around 32#, even with Cal's, while the 9/0 with Adam's insets will feel silky smooth at those same #'s, the line peels off with very little effort.
This goes for larger or smaller reels as well.

I believe we're doing good here.

Sal

[Tightlines667]

I sometimes find myself wondering if anyone actually bothers to read previous posts.

The two criterion which greatest affect the sum total of drag are 1) the number of sliding surfaces, and 2) distance from center of rotation to center or mean diameter of friction surface. A third is of course coefficient of friction of the chosen sliding materials, but since we use a very limited number of materials in reels, this is of lesser interest right now.

...but due to the larger number of active drag surfaces...  

Yes, exactly.

This was a good thread.

I actually hadn't read the 'DRAGENSTEIN' article before (and I have been here for almost 4 years).  Alot of what he says about the effects of the laws of physics on drag performance makes sense.  You just need to read between the lines a bit on the specific drawbacks of certain reel designs.  

Many modern reels have designs intended to address some of these known concerns to improve adjustability, repeatability/consistency throughout the range, and decrease or mitigate the immediate effects of heat.
Many modern day lever drags have larger diameter, lower surface area drags.  Also heat is typically dissapated more quickly, and designs tend to do a better job of balancing the decreased coefficient of friction with the increased pressure associated with heat generation so that the drag stays more consistent throughout its force and temperature ranges.  One of the drawbacks associated with star drag systems is the tendency for them to retain generated heat, and for things to bind when they become heated.  Typically this results in increased drag, and decreased adjustability once the reel gers hot, which happens faster (esp. true^2 when the drag surfaces are working at greater speeds).  The reel also takes longer to recover.  

Interesting that thin SS drag washers are best for reducing binding, and increased drag pressures due to increased heat, though they usually win out in star drag reel designs.    More drag surface area does convey some advantages though that the author failed to mention.  But diameter really is the key..think speed or diameter effects on drag are squared where as pressure-related changes are dictated by the reels normal drag curve.  We can play with this by changing Belleville (or spring washer) config, and cam ramp.  Greased CF is also helps to mitigate many possible detrimental effects of heat, debris, ect..  

Also interesting is the author's discussion regarding many different possible contributing factors to surginess.  Line angle, spool fullness, etc..  Decreasing spool diameter has a steeply isotope (exponentially growing) curve for multiple reasons though.  Speed is one such factor, but spool height acts at the same rate.  Of course decreasing spool fullness is usually at a point during use when temperatures are higher, so this can compound things further.  No wonder Shimano designed a hydrothermal device that compensates for these negative effects, by simply swelling at a predictable rate as it warms.  

An astute angler that has a properly designed, and adjusted reel, can make adjustments to accomplish the same task throughout the course of a fight.  Unfortunately, many anglers do not fully understand how to properly manage their drag.  One simple rule the author inadvertently mentions is to try to limit the fish speed in favor of increased pressure, and to increase spool diameter, and decrease heat...of course this also must fall within the recommendation of 30% of line strength, and within the reel's specs/capabilities.  Anglers accustomed to catching Big Game on light line in prolonged fights must learn how to manage their drag throughout the course of the fight, or the consequences will be immediately felt.  

Thanks for reviving this discussion.  

BTW I also agree with Lee, though I can't seem to ever recall disagreeing with the man  

[jurelometer]

To the original post:

Look up 2nd law of friction on your favorite search engine.   Friction is independent of surface area. What matters is the amount of force and the slipperiness of the surfaces.  It is really counter-intuitive.  The classic example is dragging a brick across a table.   It doesn't matter which side  of the brick is  on the table.  It takes the same amount of force to move it, even though the sides have different surface areas.  The reason has to do with the the surfaces  not being  flat at the microscopic level.  If you double the surface area you might double the number of tiny contact points, but if the total force is not changed, the force per contact point is cut in half.  So you end up with the same amount of friction.  There is a more accurate  but complicated explanation of this phenomenon, but I don't understand it

From a strictly theoretical standpoint, adding  drag surfaces inside a reel increases the surface area, but does not change the force applied, or the coefficient of friction( slipperiness of the surfaces).      So this should mean that adding drag washers to a stack does not increase the amount of friction, so at a given amount of torque on the star,  the number of drag washers will not change  the actual amount of drag.

That does not mean that the drag stack does not perform better with more washers, or even that it might be possible to get a higher drag setting (perhaps by generating a better torque to lateral force translation).  But it does mean that any improvement in total drag for a given torque setting is not directly attributed to increasing the surface area.

Regarding diameter,  I think it works this way:   Going back to the brick analogy-   if you drag the brick around a  full circle,  the larger the circle, the greater the distance you have to drag the brick, thus converting more energy per rotation for a given amount of friction.   This presumes that the drag setting force can be applied to the outer diameter.  The larger the diameter, the trickier this can get.

In the end, we are converting kinetic energy ( motion) to heat.   IMHO we spend lots of  time thinking about how much heat we can generate ( max drag), and not so much, what to do with the heat.   Makes sense for setting up reels for quick stopping, but maybe not so much for extended runs.


-J.

Based on your brick example, youre missing an important point.  Drag is dependent on surface area and PSI.  With a fixed weight, PSI goes down with an increase in drag area.  In reels, thats not necessarily the case.  If you add drag area, while keeping PSI the same, you can increase the drag numbers.  My insert kits are a perfect example.  The 6/0 Sal tested went from 30 lbs? max drag with the stock cf drag, while my insert kit had a smaller diameter, but due to the larger number of active drag surfaces, Sal saw 74 lbs of drag with my kit.

So using my example, this is like adding bricks,   not changing the surface area of a single brick.   

Or more accurately, x lbs of force onto the stack provides x lbs (more or less) on each set of surfaces. The psi does not decrease with the additional surface area when independent sets are stacked.  Stacking is the key. 

Easy enough to visualize now that I think about it.

Thanks Adam,

-J.

[richard]

 Great replies gentlemen,took me a while to digest that lot.
the posts from JURELOMETER and especially the comment from THREE SE7ENS have explained this in terms I can
get my head round.



"Drag is dependent on surface area and PSI.  With a fixed weight, PSI goes down with an increase in drag area.  In reels, thats not necessarily the case.  If you add drag area, while keeping PSI the same, you can increase the drag numbers".

Soooooooooo....we can say that FOR A GIVEN PRESSURE (PSI) AND SIMILAR DRAG MATERIAL(coefficient of friction) ENLARGING THE SURFACE AREA OF THE DRAG MATERIAL WILL GIVE MORE DRAG.
  (I appreciate that I could achieve the same drag numbers by going "silly tight" with smaller or less drag washers,BUT WHY ON EARTH WOULD I WANT TO DO THAT mr dragenstein?

[Robert Janssen]

No.

Again:

The two criterion which greatest affect the sum total of drag are 1) the number of sliding surfaces, and 2) distance from center of rotation to center or mean diameter of friction surface.

Increasing the number of discs will give more drag.

Increasing the diameter of those discs will give more drag.

Increasing the pressure upon those discs will give more drag.

Increasing the surface area of those discs by utilizing the full face of the disc as a frictional surface as opposed to utilizing only a smaller peripheral portion of said disc as a frictional surface, will not increase drag.


Possibility of misunderstanding: Increasing the number of discs or their diameter will in fact likely also increase the sum total of the surface area, but this is secondary to the primary two criterion as per above.

.

[theswimmer]

In school this portion of physics messed with my head the most.
It wasnt until my tutor broke it down in terms that applied to my personal experience that the light bulb went on.

The first example was the disk brake analogy.

Brembo, one of the finest brake component manufactures found that increasing the disk diameter, adding calipers and pad size in order to increase surface PSI gave improved results. Both also allow  better heat dissipation, end result , better braking.
Increasing surface area alone produced negligible results.

Second example was Snow ski size.
In this example the increase in surface area primarily by increasing ski length, all other variables remaining constant, actually reduces friction allowing the ski and attendant skier to go faster. This is something us oldtime skiers have always known.
When I race Nastar the kids are always amazed at how fast I am on a GS course.
I point out that I ski a 190 cm ski while the kids today usually are on a ski that is 165-175 cm.

Hope this helps.

Tribology is indeed weird science!

[richard]

    

  I know that adding more discs to a star drag works in the real world, or people would not fit them.
  Using both sides of a drag washer increases the drag on an avet RAPTOR, compared to the one face on a normal avet(FOR THE SAME SIDE LOAD)

  Agree that the "outer area" of a drag washer will provide more stopping power than the smaller dia inner area.But ,that is partly down to leverage (its easier to stop a spinning bike wheel
  by applying pressure to the tire rather than the hub).

   I can see that the smaller "inner area" of a drag washer will create less friction than the outer area,and that increasing drag surface here (even if possible) would not be of much use,but
add that same area to the outside with bigger washers,but same gear ratio, and you will have more drag for the same star pressure.Isn't that surface area working?
   

[johndtuttle]

   

  I know that adding more discs to a star drag works in the real world, or people would not fit them.
  Using both sides of a drag washer increases the drag on an avet RAPTOR, compared to the one face on a normal avet(FOR THE SAME SIDE LOAD)

  Agree that the "outer area" of a drag washer will provide more stopping power than the smaller dia inner area.But ,that is partly down to leverage (its easier to stop a spinning bike wheel
  by applying pressure to the tire rather than the hub).

   I can see that the smaller "inner area" of a drag washer will create less friction than the outer area,and that increasing drag surface here (even if possible) would not be of much use,but
add that same area to the outside with bigger washers,but same gear ratio, and you will have more drag for the same star pressure.Isn't that surface area working?
   

Not precisely as the additional radius dominates and the now inner surface contributes much less proportionately.

However, area is proportional to radius ie Area of the Disc is A = ╥ * R ^2

So, it is not contributing nothing, but just less and less so as to be worthless as the disc gets wider. The greater the distance from the center it is applied the more drag force will be created in a linear fashion.

[Alto Mare]

Sorry guys, I needed to clean it up, not fair for others.
We are now back on track.

Dominick, if you want to put yours back, I leave it up to you.

Sal

[jurelometer]

Great replies gentlemen,took me a while to digest that lot.
the posts from JURELOMETER and especially the comment from THREE SE7ENS have explained this in terms I can
get my head round.



"Drag is dependent on surface area and PSI.  With a fixed weight, PSI goes down with an increase in drag area.  In reels, thats not necessarily the case.  If you add drag area, while keeping PSI the same, you can increase the drag numbers".

Soooooooooo....we can say that FOR A GIVEN PRESSURE (PSI) AND SIMILAR DRAG MATERIAL(coefficient of friction) ENLARGING THE SURFACE AREA OF THE DRAG MATERIAL WILL GIVE MORE DRAG.
 (I appreciate that I could achieve the same drag numbers by going "silly tight" with smaller or less drag washers,BUT WHY ON EARTH WOULD I WANT TO DO THAT mr dragenstein?

Thanks Richard.

I too like explanations rather than statements of fact.   I think you are pretty close.  You just need to replace "surface area" with "diameter"

So at the risk of screwing up again  

1.  Friction is the force resisting the relative motion of surfaces (in our case solid surfaces touching each other)

2.  The coefficient of friction is a number that  quantifies the relative slipperiness of the two surfaces (like stainless and carbon fiber)

3.  The amount of friction is determined by the force pushing the surfaces together and the the coefficient of friction.  Changing the surface area will NOT change the amount friction.

4.  Now when friction is used to slow a moving object,  kinetic energy (~motion) is converted to heat.   The simple case is a straight line motion (e.g pulling a brick across a table).  The longer the distance the surfaces are moved against each other at the same speed and friction,  the more kinetic energy is converted to heat.  

5.  Now lets say the motion is not straight, but circular, like a disk brake on a car.   The larger the diameter of the disk, the more distance the braking surfaces move against each other per revolution - therefore converting more energy.  In other words,  A larger disk provides more braking per revolution than a smaller disk for the same amount of friction.  That is one of the reasons why we see big disks and small pads on disk brake systems on cars.   We need diameter, but we don't need surface area.

6. Simply increasing the surface area of a fishing reel's drag washer does not provide more friction, but when it increases the diameter, it will increase the braking power.

So a bigger drag washer system provides more braking power by virtue of having a larger diameter, not by having a more surface area.

7.  At some point it becomes impractical to increase the force on the drag stack to achieve more stopping power (star gets too hard to turn, drag material deforms, etc).   Now we have do one or more of the following:

a) go to a larger diameter drag surface

b) stack additional braking systems under the same source of force.

c) switch to materials with a higher coefficient of friction.


Hopefully, I got it right this time.

-J.

[Alto Mare]

Excellent explanation Dave.
You guys are way smarter than I am, you have the option of using statistics and formulas. I need to depend on facts, but don't mind it at all.
Now, doesn't one large drag create more heat than (7) smaller washers, producing the same #'s?

Sal

[richard]

   
Thank you JURELOMETER once again for a great EXPLANATION in terms I can relate to.
Also appreciate what JT and RJ explained re the "outer " section of a drag washer being more
effective than the smaller( and slower moving?) "inner".
All clear now-----easy in the end eh

Alto Mare......I hope someone answers your question re drag washers and heat.
I cant 'cos my brain hurts!