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Forums > Technical Discussion > Designing -The Perfect Wick-

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Face_NL
PLATINUM Member since Sep 2002

Face_NL

addict
Location: Netherlands - Breda

Total posts: 513
Posted:Hello my fellow Poiers!

I had to study last night , but wasn't in the mood, so I took my strokes of Kevlar and started to fold it in different designes... I've folded a few thingies and started to think ....

In theory you have a fixed amount of Kevlar in your hand, so the volume should be the same in different designes... Because of small spaces between the strokes it will differ a bit, but not significant (with good designes).

What can be changed is the surface of the wick ! For the cathedral or 'just fold it like this /\/\/\' method you can change the length of the fold, and therefore the size of all surfaces. With the tubecore you can change the surface by changing the diameter of the tubecore.

And then, I thought, maybe the perfect wick could be made according:

Burning time = Constant * (Volume / Surface)

-> The bigger the volume, the more fuel it can hold, the longer the burning time
-> the larger the surface, the more flames and the faster the fuel burns away.
-> The constant contains factors as climate, fuel, etc; independant of your pois...

so: Max burn time = const * (max Volume / smallest surface)

Now is my question: 1 - what do you think of this? , and
2 -> Can you guys & Girls please post your design wick (just the name), size of the sides etc and what burning time it gives with what kind of fuel?


|| "Is True Mastery of the Elements But a Dream?" ||

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Face_NL
PLATINUM Member since Sep 2002

Face_NL

addict
Location: Netherlands - Breda

Total posts: 513
Posted:Ow, and more questions...:

- would the surface of the poi-bottom be more importand because fuel transports to there as a result of centrifugal forces? Or is the wick absorbant enought to let the fuel burn equally over the entire poi?

- What to think of aerodynamica-design (just cathedral, Monkeyfist (interesting) of tube-core)? Should the poi cause much disturbance or not in order to get big flames, and does it affect the burning time?


|| "Is True Mastery of the Elements But a Dream?" ||

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vanize
SILVER Member since Aug 2001

vanize

Carpal \'Tunnel
Location: Austin, Texas

Total posts: 3899
Posted:well, the mathematical solution to your argument goes like this - the more volume you have and less surface are you have, the longer it is going to burn.

the three dimentional solution to this maximizing this volume to surface area problem is a sphere. the cube of a cathedral fold is closer to this sphere ideal than a cylindrical shaped wick.

normally, increasing the size of a sphere will increase the volume to surface area ratio (since volume goes as the cube of the radius and area as the square), but since we are talking about a fixed amount of wick (and therefor a fixed amount of volume), then increasing the diameter of the sphere will only increase the surface area and your burn will be shorter (effectively you are creating thinner and thinner shells of wicking as the radius gets bigger and bigger).

of course there are chaotic factors like the interation of the flame with the spin, how much turbulance is created - more turbulance allows more oxygen to come into contact with the fuel, increasing the burn rate. cube wicks will definitely create more turbulance than spherical ones or perhaps even cylyndrical ones.

so then, once must balance the theories of classical logic (our volume vs surface area argument) with the effects of non-linear effects like how wick shape affects the turbulance around a rapidly moving wick. Of course the sphere is also close to an ideal solution for minimizing the turbulance as well (short of maing wicks of an airfoil shape, which won't do so well with our volume to surface are considerations).

so I vote spherical wicks. good luck making spherical wicks though...


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PoiBox


member
Location: Bangkok

Total posts: 85
Posted:Smallest Surface = Smallest Flame

and we surely dont want that to happen !!!


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darkpoet
BRONZE Member since May 2003

darkpoet

Irish
Location: Dallas.........ish

Total posts: 525
Posted:if your talking about HOP wicks

the tubecores suck, if you losen the screws to increase diameter (surface area) they stretch
they have a VERY short burn time
they dont look all to great
only time 4inch looks half decent is w\ the 4inch double wick set

2.5 inch are OK, but their just tiny and dont burn all too long because of it

the cathedrals actually last a decent amount of time, and they look good while spinning

the monkeyfists last forever!! and they look really really nice on fire, only drawback is how much fuel they soak up and the weight

thats just what ive learned from personal experiance...enjoy


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MikeIcon
GOLD Member since Mar 2003

MikeIcon

Pooh-Bah
Location: Philadelphia, PA - USA

Total posts: 2109
Posted:This thread made me think. Has anyone ever made a wick that is somewhat like a cathedral but the sides are extended so a top view of the wick would look like a plus sign? The center would still have the volume of a cathedral wick, the outside extensions would work to make a much greater surface area.

They would burn a bit shorter than normal cathedrals (not that much shorter since youre still adding volume when you extend the sides) and be much larger flames in theory.


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adamrice


adamrice

poo-bah
Location: Austin TX USA

Total posts: 1015
Posted:I actually got this question via e-mail, but I thought I'd post my reply here to kick around:

Volume:Surface area is probably a factor, but I don't think that increased surface area necessarily reduces burn time (I am pretty sure that interleave wicks have more surface area than tube-core wicks, and they clearly burn longer), and I think there are other factors anyhow.

The critical factors are probably fuel capacity, the rate at which fuel moves to the surface (motility, or wicking action), and surface area. If you have high capacity but poor wicking action, you'll burn out before you run out of fuel. If you have good capacity and good wicking action, but the surface area is too small, then not enough fuel will ever be at the surface (after initial burn-off) to create a flame large enough to resist being extinguished by spinning before running out of fuel--effectively, this is the same problem as poor motility. If you have good wicking action and high surface area, all the fuel will move efficiently to the surface, create a large flame that exhausts all the fuel quickly.

My guess is that there is a "golden ratio" between the motility and surface area--so that there's not a magic number for either one, but as long as they're in the right proportion, you'll get a complete burn.

This is all in the abstract. In practical terms, the wicking material you use, how tightly it is compressed, how fast you spin, etc, will affect burn time. Towel wicks have better burn time than kevlar wicks because (I assume) they hold more fuel and wick it more efffectively.


Laugh while you can, monkey-boy

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Face_NL
PLATINUM Member since Sep 2002

Face_NL

addict
Location: Netherlands - Breda

Total posts: 513
Posted:Heyhey,

sorry for my late response, but I had exam week, and I don't have an internet-connection at home anymore :-(... Anyhow, thnx for thinking along with me!

vanize

Thnx for your explanation on the theory!
"the three dimentional solution to this maximizing this volume to surface area problem is a sphere."
:-(, that's what I already feared, the most difficult wick-form to make... For my next wicks I'll probabebly make cathedrals if that is closer to it, but I didn't have enough kevlar to make a cube, so it became an tubecore without a tube :-).
"Of course the sphere is also close to an ideal solution for minimizing the turbulance as well, so I vote spherical wicks."
Entirely spherical wicks will be difficult, but I guess that monkey fists will come pretty close. I tried to make a monkey fist around a little ball, and that wasn't too difficult... Just wondering, does anyone know how HoP attached the metal loops to the monkeyfists / in them, and what do they use as 'absorbant core' ?

"Smallest Surface = Smallest Flame" well, yeah, but only relative, so with a really large volume (= heavy :-s) you have with 'the smallest surface' possible still a large flame...

"the monkeyfists last forever!! and they look really really nice on fire, only drawback is how much fuel they soak up and the weight"
much fuel = good! I like them kinda heavy and slow, and they should burn longer...

Royal:

Hmmz, never heard of a wick like that, vewy intewesting... Sounds difficult to make them durable/strong though, and costing lots of kevlar... when you make them or something like that, let me know! (btw, sounds like kind of the opposite from my starting point, but large flames is also cool... matter of preference


This thread made me think. Has anyone ever made a wick that is somewhat like a cathedral but the sides are extended so a top view of the wick would look like a plus sign? The center would still have the volume of a cathedral wick, the outside extensions would work to make a much greater surface area.

adam:

Hey, thnx for your quick response! *reads and nods*. hmmz, wicking action is indeed also important... More difficult to modify though, there are only a few materials possible to use... Maybe if you combine them that you can get perfect wicking action, but I don't feel like rebuilding my poi's after each 3 burns... Do you know btw how much longer the burning time is with towels instead of kevlar? (approx..) If it is a difference of 5 minutes for example, it would be worth the trouble for shows and stuff...

----
Hmmz, considering all the xtra little factors i don't think I will be able to make a working formula with it... ah well... Made me wiser though :-)



|| "Is True Mastery of the Elements But a Dream?" ||

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BoomShankar
GOLD Member since Jul 2003

BoomShankar

member
Location: Leeds UK

Total posts: 95
Posted:I believe the monkeyfists on this site have a cotton centre, which is what I intend to use when I make some - only I don't know how much (14mm diameter) kevlar rope to buy so if anyone's already made some of their own monkeyfists and has some idea how much rope they used on them please let me know

cheers biggrin
Wolfie~


progger

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Big Andy
BRONZE Member since Apr 2003

member
Location: Dallas, Tx

Total posts: 186
Posted:Quote:
Originally posted by adamrice
I actually got this question via e-mail, but I thought I'd post my reply here to kick around:

Volume:Surface area is probably a factor, but I don't think that increased surface area necessarily reduces burn time (I am pretty sure that interleave wicks have more surface area than tube-core wicks, and they clearly burn longer), and I think there are other factors anyhow.



This is assuming the cathedrals and tube cores in question use the same volume of wicking. Otherwise the burn time differences aren't valid as they apply to this discussion.

Quote:
Originally posted by adamrice
The critical factors are probably fuel capacity, the rate at which fuel moves to the surface (motility, or wicking action), and surface area. If you have high capacity but poor wicking action, you'll burn out before you run out of fuel. If you have good capacity and good wicking action, but the surface area is too small, then not enough fuel will ever be at the surface (after initial burn-off) to create a flame large enough to resist being extinguished by spinning before running out of fuel--effectively, this is the same problem as poor motility. If you have good wicking action and high surface area, all the fuel will move efficiently to the surface, create a large flame that exhausts all the fuel quickly.

My guess is that there is a "golden ratio" between the motility and surface area--so that there's not a magic number for either one, but as long as they're in the right proportion, you'll get a complete burn.


I'm wondering if the tube core design has better motility than the cathedral design. Because of it's simplicity, I kinda think it might. It has a clean face, with the fibers lined up nicely. It seems like a fluid would flow through it more smoothly and efficiently. This isn't based in any kind of science or factual information, just my own logic.

Think about it, layer cloth on top of itself and pour water through it, it will flow quickly from one side to the other. Take the same cloth and interleave fold it. Now pour the water through it. I haven't done this experiment yet, but my hypothesis is that it will take longer to travel the same distance and more liquid will be retained without actually dispersing to the outer limits. Just a theory, I'll play with it and get back with you guys.

As far as the "perfect" wick design, it depends on what one's standards are. What is most important? Burn time? Flame size? Fuel consumption? I know I want a wick that burns efficiently, with a minmal fuel consumption/burn time ratio. But I also want the flame to be as large and in charge as possible! There is a balance between these factors, with preferences differing for everybody. For me, I need a wick that could provide the surface area/turbulence to generate a large flame, but maximize the efficiency of the wicking action. Meaning that the wicking action isn't wasteful.

I dunno, I'll mess around with some cloth and water and see if I come up with anything.


"We can't stop here! This is bat country!"

"Welcome to the U-S-A,
We'll treat you right, unless you're black or gay, or Cherokeeeeee!!"

-Brian Griffin from "Family Guy" (the dog)

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adamrice


adamrice

poo-bah
Location: Austin TX USA

Total posts: 1015
Posted:Quote:
This is assuming the cathedrals and tube cores in question use the same volume of wicking. Otherwise the burn time differences aren't valid as they apply to this discussion.




Of course. And I've done side-by-side tests of tube-core and interleave wicks that use exactly the same amount of the same material, and posted the results on the web.

Quote:
I'm wondering if the tube core design has better motility than the cathedral design. Because of it's simplicity, I kinda think it might


Think again. Motility through a material is a function of the individual fibers' ability to wick, not of macro-scale features: think of 1970's era polyester opposed to modern-day capilene or other miracle fibers. That said, water would drip through the 4-5 layers of a tube-core wick before it would drip through the 10+ layers of an interleave wick simply because there is more material.


Laugh while you can, monkey-boy

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Big Andy
BRONZE Member since Apr 2003

member
Location: Dallas, Tx

Total posts: 186
Posted:Quote:
Of course. And I've done side-by-side tests of tube-core and interleave wicks that use exactly the same amount of the same material, and posted the results on the web.


I knew you had tested these from visiting your site in the past, wasn't sure whether they actually were the same amount of material or not. Since they are, then cool! Nevermind, lol.

Quote:
Think again. Motility through a material is a function of the individual fibers' ability to wick, not of macro-scale features: think of 1970's era polyester opposed to modern-day capilene or other miracle fibers. That said, water would drip through the 4-5 layers of a tube-core wick before it would drip through the 10+ layers of an interleave wick simply because there is more material.


Well, you seem to be more educated on the science of this, so I can't really comment on that, lol. ubbrollsmile

BTW, I couldn't get those smaller rings you sent me on my handles, so I think I'm gonna go with some quick links. A friend of mine is gonna order some stuff from ya pretty soon here, so I'll get it the order in with his and he'll give them to me.


"We can't stop here! This is bat country!"

"Welcome to the U-S-A,
We'll treat you right, unless you're black or gay, or Cherokeeeeee!!"

-Brian Griffin from "Family Guy" (the dog)

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