Farfalle, as you mentioned, does literally mean butterfly. The name doesn't seem as obvious when you see them flying through the air. Farfalle are made just like the above tourbillions, except there are two holes instead of 1 toward the end of the tube, opposite one another. When burned on the ground, it sends out two large sprays of metal sparks that resemble a butterfly's wings. You can also put the hole in the center of the tube instead of an end. It probably gives them a straighter trajectory and a more dense spray, but you can't fit as many in a shell. With the holes toward the end of the tube, they can spin and spiral, possibly due to off center holes.
yeah, i know farfalle is the italian name for butterflies... just reading info on pyroguide i was thinking you also know it as 'farfalle' more than 'butterflies'... just like 'spaghetti' or 'pizza'.
anyway farfalle are different from turbillion. maybe you never seen a well-done farfalla device but i can assure to you that 2 holes are needed to obtain that effect.
With the pass-trough hole in the middle of the tube , the flying device oscillate of some degrčč clockwise and counterwise sprying sparks... this is the movement that draw the butterfly wings in the sky. Butterflies should never make a complete turn by it-self... (anyway this can be caused by the launch)
on the countrary i think that tourbillions have a single hole because thay *have to* turn on itself during the flight...
thank you for the reply!