Best 'report' for the buck

[blaster_man]

Hi gang,

 

Been making my own amatuer pyrotechnics for years, and this year's challenge for me was refining my best technique for getting a good report from your typical 70/30 flash powder ratio.

 

Obviously, safety has been a big concern of mine, and also considering the increasing difficulty (and legalities) of getting the required materials, I like to keep things as conservative as possible.

 

Been experimenting with various enclosures and volumes of flash powder mix, and at least for me it seems the typical heaping teaspoon (about 5grams) of perchlorate/german dark in a 1/8 walled 2-3 cardboard tube has always been ideal. I hate affiliating myself with novice M-80 makers, but just like old fashioned stereo amplifiers it seems the standard. Is this just a fluke, or is there actually some chemistry involved here that dictates diminishing returns for the amount of powder I'm using?

[justanotherpyro]

When flash is confined, it goes bang. The forum frowns on talk of bangs, m-80's, quarter sticks..whatever. A bang isn't hard, so there isn't a terrible amount of intelligent discussion from such topics.

[lacrima97]

This seems more along the physics of sound. I wish people didn't look down upon the scientific discussion of loud noises.

[brainfever]

On the matter of sound physics:

-Bigger gas output volume => harder sound.

-Higher confinement (rupture pressure of the container) => harder sound.

-Higher reaction speed (most determining factor imho) => harder sound, but usually also higher frequency.

 

The enviroment also plays a big part in the propagation of the produced sound. Soft or porous materials absorb the higher frequencies with ease, lower frequencies tend to move trough things rather then reflect on them.

If you make some sort of parabolic reflector for your sound guidance, it will travel further then if you make the sound in a padded room.

 

 

For the actual creation of these sound producing items I totally agree with justanotherpyro.

[blaster_man]

When flash is confined, it goes bang. The forum frowns on talk of bangs, m-80's, quarter sticks..whatever. A bang isn't hard, so there isn't a terrible amount of intelligent discussion from such topics.

The forum frowns on talk of bangs, m-80's, quarter sticks..whatever. A bang isn't hard, so there isn't a terrible amount of intelligent discussion from such topics.

 

I don't recall seeing that in any forum guidline, so I'll leave it up to more 'sophisticated discussions like putting BP rocket motors on sticks. I'm also assuming you use compressed air to disperse various effects since 'bangs' are frowned upon. Any other unwritten forum rules I need to abide by?

 

At pretty much every formal fireworks show I've been to, there has been a sequence of report only pyrotechnics that the crowd generally likes - I believe they are referred to as 'titaniums'. That's not what I'm interested in doing, but the physics behind producing a chest thumping burst I consider quite facinating. Given how many pyrotechnicians tend to hide their designs for report enclosures, there is more to it than rapid oxygenation inside an enclosed space.

 

I wish people didn't look down upon the scientific discussion of loud noises.

 

Exactly.

[blaster_man]

Higher reaction speed (most determining factor imho) => harder sound, but usually also higher frequency.

 

Which is why assume sulphur is frequently added to such mixes, correct?

 

Never mind. It's clear you'd all rather talk about appeasing 3yr olds with 3" inch shells I can emulate by shooting a half quid ground fountain into the air with a sling shot

[RUUUUUN]

Did you even read what BrainFever and Justanotherpyro said? they said that the talk of SALUTES was frowned upon simply because anyone with half a brain can make a salute, and discussion of salutes brings down the integrity of the forum.

 

Who hides their "salutes designs"? If you searched at all you could find several casings that work for salutes.

 

Scientific discussion of flash powder salutes.

 

Englishmen these days.

 

edit button maybe?

[lacrima97]

On the matter of sound physics:

-Bigger gas output volume => harder sound.

70/30 KClO4/Al has no gas output. Its just KCl and Al2O3.

[Swany]

In theory, not in practice though.

 

Side reactions and temparture ensue that gaseous products are formed.

[Mumbles]

Ok guys, raise your hand if you're a moderator. Hmmmmm, I sure see a lack of hands. Leave the decisions as to what is allowed to us. This thread has merit. We generally only discourage the discussion of salutes when it is done in an irresponsible or unintelligent manner. Now, play nice.

[lacrima97]

In theory, not in practice though.

 

Side reactions and temparture ensue that gaseous products are formed.

Yeah, you are right swany. I had to say it though, it was soo tempting.

[brainfever]

Okay, I never thought I'd be giving a thruthful answer to a "how do I make the loudest noise with the cheapest materials" question ...

 

 

Make a fast burning 70:30 fash composition. I presume KClO3:Al is cheapest?

 

Find a suitable container, a high tensile strenght is preferred.

Don't overfill the container to allow for proper pressure buildup. The peak pressure (rupture) should occur right before all composition is burned.

Reïnforce presumed weak spots in the container to avoid premature rupture at lower pressures.

 

To allow the pressure to rise fast enough, keep the fuse hole as small as possible, if an e-match is used, seal completely with a strong material.

 

 

So when going at it super cheap:

Take a metal pipe and hammer 1 end shut. Drill a fuse hole in the middle.

Fill half with finely divided and intimately mixed 70:30 fash mixture. Add a tissue to keep the composition on it's place and away from the open end.

Hammer the open end shut, enclosing the composition.

Insert fuse in previously drilled fuse hole.

 

There you have it, you can't possibly get a better "report for the buck"

 

For optimal appreciation of the produced sound, you best light it in a small concrete room hanging the device by a rope in the centre of previously mentioned parabolic reflector aimed at your head.

 

You should be able to get pierced eardrums from the sound wave before the shrapnel does the job properly.

Unless ofcourse you fill the pipe with a high explosive and detonate it with a suitable cap, then you might come across some shrapnel ahead of the sound wave.

[PyroJoe]

If you are making good size titanium or flash salutes, say 3" and above I would mix in maybe 1/3 of rice hulls or lift powder to take up space. It won't make a whole lot of difference in sound and it will save you some flash powder. Also, I read on the internet a guy would cut his flash with 1/3 of lift powder and he said it actually improved the sound. Might have to try it.

[RUUUUUN]

I can't believe this.....

 

I disagree with you brainfever, if you find a good metal sphere it will give a louder report. So all you have to do is find/make a metal sphere out of a good high tensil strength metal, load it about 1/2 to 2/3 with flash powder, drill a hole to insert a fuse, lay your ear up against the metal sphere, and light the fuse. I don't think you can get a louder noise than that without using high explosives.

[Von Bass`]

Hammer the open end shut, enclosing the composition.

You're going to hammer a flash composition in a metal pipe? At least use a vice!

[Swany]

He was being mildly facetious, people. Don't overreact. Brainfever is brilliant, and you could be if you analyzed his writing style a bit more closely.

 

This is somewhat asinine, as simple paper or plastic tubes do it quite nicely.

 

If you could find cheap, small, thin walled plastic containers that would be your best bet IMHO.

[lacrima97]

Actually, I believe you may have had something with the metal spheres. I hate to say this but: My girlfriends dad said to me that a long time ago, when 3g flash charges were still legal, that the spherical cherry b0ms were more powerful than the m80's. I was thinking to myself, that this couldn't be so, since the m80 had more powder, but he swears on his life that the cherry was more powerful, and it might have to do with that spherical shape.

[HoS]

It might also have to do with higher confinement on the round ones.....

[brainfever]

I disagree with you brainfever, if you find a good metal sphere it will give a louder report. So all you have to do is find/make a metal sphere out of a good high tensil strength metal ...

Good luck finding a suitable metal sphere then RUN

Did you have anything suitable in mind allready? Also, how are you going to close it properly without leaving the obvious weak points?

 

 

Good confinement really IS the key to create the best bangs.

 

Thick walled spheres like used in cherry bombs could be easily made by first assembling a filled and fused thin walled sphere and dipping it with drying periods to create the ultimate confinement.

The main difficulty here will be to find a good suspension of binder/glue and filler material to cover the entire sphere evenly and drying it without capturing moisture inside your cherry bomb.

 

I was thinking about wallpaper glue and sharp sand ...

I've seen this stuff dry and it literally becomes rock hard with a sandpaper feel to it.

If you replace the glue/binder with a non water soluble one, it might work in moist enviroments aswell.

And dry faster probably too. NC laquer perhaps?

[RUUUUUN]

hmmm, an old Commie Pineapple? 2 half spheres just like a shell that were threaded to screw together? Ping pong balls full of flash and then covered with muffler tape?

 

If you threaded them together you could put teflon tape in the threads so that they completely sealed.

[brainfever]

The threads are the obvious weak point there, it will definately blow open at the equator.

 

I think the best confinement would be the old iron cannon ball style cast sphere which can be filled with a top opening in which a small bolt with fuse hole can be screwed.

[PyroJoe]

I do believe that cherry bombs are louder than m80's with the same amount of powder. I made about 30 cherry bombs a couple weeks ago in a star roller using saw dust and water glass. After I rolled them so the wall was about 1/4" thick, I let them dry then dipped them in several coats of wood glue and sawdust. They are rock hard and for some reason just have a different/louder sound than my regular m80's.

[RUUUUUN]

reinforce the threaded area, so that it is thicker around the equator like an M67 Frag. Where would you find an old cannon ball?

 

Howabout casting 2 hemis, welding them together and then drilling a pretty large hole that you can get a bolt into...

[AreteVeteran]

whatabout a good old perscription bottle and some duct tape

thats what i use to experiment with my flash

ive gotten great reds greens and some that i have to wear sunglasses to keep from getting blind

 

and sound is all about location

find somewhere you can hear and echo and have fun

 

/AV/