Agreed, the butterflies don't rotate. They have a mild comp with lots of titanium and not much propulsive force, and two holes opposite each other at the center point. The second video definitely shows these. I'm not sure about the first video, as those seem to be spinning, but I think they're hummers not tourbillons because they're spinning on the long axis.
Here's a butterfly insert, by (I think) Vulcan Fireworks. It would look exactly like the inserts in video 2 when lit. The tube is parallel wound (but not very good quality), 11mm ID, 2mm wall, 65mm long. The powder core inside is about 50mm long and the ends have paper plugs, glued in, indicating that it doesn't expect to have to hold much pressure. The grid on the paper is 5mm. I didn't make this so I don't know the composition, but I've made similar inserts and I would guess 60% KNO3, 20% charcoal, 10% sulfur, 10% fine titanium for a first try. Ram or press it solid like a rocket.
I think there is a definite difference between butterflies (farfalle) and tourbillions - the former have 2 opposed nozzles which gives a thicker (2x) trail and a straighter trajectory as there's little overall propulsive effect.
There are different grades of nitrocellulose, depending on whether one, two or three of the -OH ions on each monomer are replaced by -NO3 ions. Which kind you get depends on the strength of the acid used in the process. Lacquers and ping-pong balls use lesser grades of nitration. Only the fully nitrated kind (all three -OH ions) explodes. To make this kind requires exceedingly nasty fuming acids and definitely falls into the "don't try this at home" category. What you get, however, is not a powder. It looks exactly like the material - paper, cotton, woodpulp - that you started with. To powder it, I would dissolve it in acetone, leave it in an open container for the acetone to evaporate and then rasp away the hard glassy residue with a coarse file.
Probably the easiest way to get hold of a small quantity of the powdered kind for dragons eggs, etc. is to take it out of a shotgun cartridge. Nearly everyone knows a farmer.
Use enough flash powder and you get impressive breaks from any old crap header. We've run a seminar two years running at Winter Blast on five minute cylinder shells - take a cheap 40mm spiral wound tube, close and time fuse one end, attach a 1 gram flash bag to the fuse, fill the rest with stars, close the other end, seal up with sticky tape well enough to survive the lift.
Stinger missiles are something different. I make those too. They light at a tangential hole near the nozzle, spin up axially on a pin and then take off when the fire reaches the core. They don't always go where you expect - http://www.amateurpy...ge/910-mishaps/
These devices don't sit on a pin, they start off flat on the ground and spin horizontally like a ground bloom flower at first. When the core lights and pushes them horizontally, they stand up by gyroscopic precession, assuming they're spinning fast enough, and by conservation of angular momentum the spin changes from radial to axial. At that point they behave like a stinger, except that the direction is random.
I use ball milled 60:30:10 in my stingers, normally they fly off with a good amount of zip, though the one in the video above had a bit too much titanium.
A half inch tube is a bit heavy for a backyard firework - you wouldn't want it to hit you. Probably a 1/4 inch version would be zippier and less dangerous.
Some great tracks here, many new to me, some old favorites. Hocus Pocus, excellent. Meri Wilson (Telephone Man) went on to become head of the Education Dept for the State of Georgia. Some wouldn't play ... Stray Cats told me "EMI has blocked this content in your country". I don't know why they bothered, since I went to YouTube and found at least 40 "Stray Cay Strut" videos still working.
Here's one you may not have heard, local Las Vegas band The Killers.
Having read all of this I just give a big sigh. The EU council will have to realise (i shall once again reiterate as many members have previously mentioned) that if you ban any of those chemicals, they can be made via other precursors, some that we use every day and are essential to life. I writhe in jealousy when i read those old fashioned 19th century chemistry articles and hear stories that my senior chemistry teacher tells me about things "back in the day". The psychology just seems so different. Yes we live in a time when terror seems to occur everywhere but at the same time, HSE is making live more and more dull. The reason? I shall leave you all with one of the wisest quotes my chemistry teacher has ever said:
"Unfortunately, we live in a time where nobody knows anything about anything and everybody is scared of everything"
It is psychology, and the psychological exercise is being carried out on YOU at your expense by people who profit from it in one way or another. Life is no more dangerous today than it was fifty years ago. What has changed is the character of government. The Triumph of the Political Classes lays it all out quite clearly. As for banning chemicals, when did prohibiting anything prevent people from getting it? The prohibition of handguns in Britain doesn't seem to have bothered the bad guys, other than inconveniencing them to the extent they have to call and have a weapon brought to them.
I'm afraid that changing the direction things are going will need much more muscle behind it than this or any other special interest group can achieve. It will need a large-scale political awakening and uprising of millions of people to turn it back now.