Forums > Technical Discussion > Critical Mass / Designs that could mess with physics

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517 posts
Location: Sheffield, England

Recently I have been engaged in debates about the 'transferrability' of poi moves and have been thinking quite a bit about it.

I know that physics tells us all poi of the same length should behave identically (mass is insignificant to circular motion) ie. the same 'minimum speed' applies before 'circle collapse'.

Of course, the above statement only applies in a perfect world. There are other factors at play here.

The one conspicuous variable we can play with seems to me to be 'air resistance'

This is the main factor effecting the behaviour of different poi of the same length.

I really don't think this has been played with much on a design level - infact only 'comet' poi spring to mind and their air resistance acts only as drag.

4 ideas:

Poi with 'outward / centrifugal' acting air resistance. This would increase cord 'tension' and make all moves potentially much slower, or make lighter structures more 'spinnable'

Poi with 'inward / centripetal' acting air resistance. This would decrease cord 'tension' and make all moves potentially much faster, or make much heavier structures more 'spinnable'

Poi with an 'air stablised' structure. Could be designed to hold its 'planes' like glue, with little drag.

Poi with a passive airbrake, correlated to tension. Could keep the poi's speed constant at low speeds, and annoy you at high speeds wink

Any other thoughts / ideas? smile

Any concepts other that 'air resistance' we can play with? smile


EDITED_BY: Jo (1109426551)

Educate yourself in the Hazards of Fire Breathing STAY SAFE!

garthySILVER Member
old hand
717 posts
Location: Bristol, England

I've noticed this with my sock/cone poi which seem to drag alot.

Moving to tennis balls on strings make the poi much faster due to lower air resistance.

Heavier poi seem to give you more momentum allowing the poi to be un powered for some parts of the move making some thing easier and some harder. Heavier allows you to put your hands in strange places allowing the weight to carry it through were as light poi tend to fall out the sky.

The heavier poi with more momentum make abusing the planes harder?

Maybe a poi head that span on the end due to propeller wingy type things would give a gyroscope effect giving you better planes?

Hmm... Food for thought!

"**grumble*spuriouswindmills*grumble**" - Coleman
"if poi was only for girls there wouldnt be many good poi spinners...." - Nx

517 posts
Location: Sheffield, England

Garthy, you know, that's not a bad idea man!

I mean, you could even design a re-usable silicone rubber 'fin sheath' I guess... ...nice and squishy...

...suitable for 'universal' things like glowsticks for example?

for a more controlled speed?

or maybe 'stability' for throws?

Hmmm... ...Nice one mate smile

EDITED_BY: Jo (1109448091)

Educate yourself in the Hazards of Fire Breathing STAY SAFE!

RevBRONZE Member
Bastard Newbie Messiah
1,269 posts
Location: Apparently lost in my ego, USA

balanced poi hold planes.. if the cord does nto cause significantly more resitance than the force exerted by the mass of the poi..

weighted poi overcome the effects of airresistance on the cord.. the more the mass overcomes the airresistance, the straighter the poi will spin.. (because the mass is determining the spin.. )

the lighter a poi is, the more likely it is to be affected by the airresistance on the cord.. subsequently its harder to maintain clean planes naturally, as well as control.. the you have to adjust the poi on the hole, and not just adjust the force on the poi head.. if that makes sense..

ultimately it ocmes down to either spinning itself.. or being spun.. heaiver poi/ poi with less resistance will give you a mass to adjust, whihc in turn swings itself.. the lighter /mroe resistant poi don't swing and must be spun through any given motion.. each having obvious advantages..

heavier poi spin more naturally but are hard to make precise changes.. lighter poi require more skill, but can preform finer adjustments in motion..

but then I'm playing capt. obvious.

More useless information courtesy of Rev...
Confusing the masses, one post at a time...
"Obviously, you're not a golfer.."- The Dude
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517 posts
Location: Sheffield, England

Rev I think you raised an interesting point there I would like to expand on a little re: 'poi balance' ... smile

The effective length of your poi is the length from finger loops to the 'centre of mass' of the poi/string combination.

This means a 'tennis ball' poi can be effectively twice as long as a 'balanced/tube' poi of the same loop-to-end length.


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Whiffle Squeekaddict
416 posts
Location: Hartford, CT USA

poi with bottle rockets at the end?

you wouldnt even have to spin em, just light em and hold on


(kidding, i hope someone doesnt go try this...)

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ado-pGOLD Member
Pirate Ninja
3,882 posts
Location: Galway/Ireland

i think someone already did smile

i was thinkin about puttin wind socks on my sticks today to create drag...

Love is the law.

MikeIconGOLD Member
2,109 posts
Location: Philadelphia, PA - USA

Yep, rocket poi has been done.

Let's turn those old bridges we crossed into ashes.
We'll blaze a new trail,
and torch the rough patches.


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