Does air space make a difference?

[ronmoper76]

i have a question,im about to do some testing but any input to save me time would be appreciated... salutes,ground bombs,whatever you guys wanna call it,does how full the tube is,make any difference ti performance... I would imagine more space means more oxygen? but shimizu has a article saying to fill em to the top without any air space???? I even read a thread where someone said about lightly packing it.. I feel like less is better,or performs better anyhow,but i'm not convinced yet. Please real answers guys,if that's not possible just block the thread and move on please. I'm tired of bickering about stuff with every bad attitude i encounter.A simple"we can not discuss that is more than suffice.

[ronmoper76]

i kinda found answer on here from dagabu talking about bottom shots.. i believe he was trying to say it makes a difference in bottom shots because of tube strength but in other devices the casing will fail before all the powder ignites,ejecting a lot of unburnt powder? How close am i?

[SeaMonkey]

The salutes I make from time to time are always fairly small.

 

I don't pack mine full but always leave an "air space" by filling the tube from 1/4 to 1/2 with Black Powder.

 

I prefer the dull thud of Black Powder rather than the sharp crack of flash.

 

Unless the powder used "fulminates" in confinement, packing the tube full of powder can be counter-productive.

[ronmoper76]

I have only found one reference to a "fulminating mix" online,and i don't remember where. I understand what fulminates are,mercury,silver,etc But they are made them by using acids to create a explosive compound...as i understand it,LOL So how can a fireworks formula fulminate,what does that even mean i guess that is what im asking..

Edited March 14, 2021 by ronmoper76

[Piccaso]

I, like Seamonkey prefer the black powder as well for salutes. Black powder maroons are kind of my thing if I want to just make noise. The oxidizer in your formula provides all of the oxygen needed for the reaction as long as it is proportioned properly i.e. the correct stochiometric ratio. That is the purpose of chems like nitrates , chlorates ect. is to provide the oxygen for combustion. This is kind of need to know info and why people encourage you to read and learn all aspects of this hobby. Basic chemistry knowledge is very important and if you where never exposed to it in school I would suggest getting yourself a few books on basic chemistry and doing some reading as it will help you greatly in understand how things in this hobby work and why. It will also make this a much safer hobby for you and cut down on failures and wasted chems.

[SeaMonkey]

Question from ronmoper 76:

 

So how can a fireworks formula fulminate,what does that even mean i guess that is what im asking..

 

 

Fulminate is an old term which in modern language would be equivalent to "detonate."

 

Flash Powder is capable of detonation in confinement.

 

In the old days we'd take firecracker duds which had defective fuses and

break them in half to expose the internal flash mix.

 

We'd lay the opened up dud on the ground and ignite the exposed flash

mix. As it fizzled we'd then stomp on the fizzling dud to make it explode.

 

If we emptied the flash from the duds in those days into a small pile and

ignite it, the burn rate was rather slow. It didn't poof all at once but just

burned sorta like a sparkler mix.

 

But when confined it detonated nicely.

[ronmoper76]

I completely understand now. Thank you because i would have looked forever and probably never found that even though i knew what detonate meant. I'm working on some 6 inch shells so i can get a few more rockets finished for a upcoming wedding,then im gonna play with this a bit more. I was getting detonation often except with strobe rockets,Im curious what changes a mix from simply burning to detonation other than confinement,i had a large list somewhere of flash formulas that listed 3 of the formulas as fulminating mixes. flash usually only detonates for me when its in a larger quantity or the case is almost bulletproof,I know you can use a blasting cap to detonate flash,i have a book on that,but i'm more curious how it moves to that phase with just a spark from a fuse

Edited March 15, 2021 by ronmoper76

[Carbon796]

Bottom shots should be consolidated full. Because it contributes to the shells structural integrity, especially with a hand rolled case. Salute or report inserts for cylinder shells, follow the same principle.

 

Additional/extra air space will not add additional effect. The traditional 70:30 mix is already oxygen rich. A minor amount of atmospheric gasses (which is not 100% oxygen ) will have a negligible effect.