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Bombettes (Question)

BJV

By BJV
in Pyrotechnics

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BJV Newbie

BJV

Posted
Posted

Hi All,

I have a question on what burst to use in my Bombettes.

These bombettes are 2-1/2" by 1" ID. They have a pressed star comp

for an ascending tail. What is the best bursting charge and the

amount of burst to use? (Slow Flash?) They will be filled with small micro stars.

Thanks,

BJV

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dagabu Newbie

dagabu

Posted
Posted

Hi All,

I have a question on what burst to use in my Bombettes.

These bombettes are 2-1/2" by 1" ID. They have a pressed star comp

for an ascending tail. What is the best bursting charge and the

amount of burst to use? (Slow Flash?) They will be filled with small micro stars.

Thanks,

BJV

 

Just thinkin out loud here, how about rolling a cunnule on a pencil, filling it with 1/2 gram hot flash and 4FA for a break?

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BJV Newbie

BJV

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Thanks Guys for the reply's.

I think I am going to go with the slow flash.

I have only 30 bombettes made ready for filling.

Going to test them as soon as the weather permitted.

I will try to get some video.

Thanks again,

Barry

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AdmiralDonSnider Newbie

AdmiralDonSnider

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In commercial bombettes (most 30mm "cake" units are chinese in origin) the break of choice is hot magnalium based flash with or without grain gunpowder. The latter is said to enlarge the breaks.

 

Slow flash is a somewhat uncommon choice, but it - too - seems to work. I personally dislike the nitrate-based breaks because of their light output.

 

Stars also here do a have a tremendous effect upon the appearance of the break. The break charge is often blamed while the real problem was the use of an unsuitable kind of stars (too small, too fast burning, or the contrary). You´ll quickly find out that round stars are essential particularly in small items.

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BJV Newbie

BJV

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Posted

In commercial bombettes (most 30mm "cake" units are chinese in origin) the break of choice is hot magnalium based flash with or without grain gunpowder. The latter is said to enlarge the breaks.

 

Slow flash is a somewhat uncommon choice, but it - too - seems to work. I personally dislike the nitrate-based breaks because of their light output.

 

Stars also here do a have a tremendous effect upon the appearance of the break. The break charge is often blamed while the real problem was the use of an unsuitable kind of stars (too small, too fast burning, or the contrary). You´ll quickly find out that round stars are essential particularly in small items.

 

AdmiralDonSnider, a hot magnalium based flash has less light output than a nitrate based flash??

What Ma/Al flash are you useing in your bomettes?

BJV

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dagabu Newbie

dagabu

Posted
Posted (edited)

In commercial bombettes (most 30mm "cake" units are chinese in origin) the break of choice is hot magnalium based flash with or without grain gunpowder. The latter is said to enlarge the breaks.

 

Slow flash is a somewhat uncommon choice, but it - too - seems to work. I personally dislike the nitrate-based breaks because of their light output.

 

Stars also here do a have a tremendous effect upon the appearance of the break. The break charge is often blamed while the real problem was the use of an unsuitable kind of stars (too small, too fast burning, or the contrary). You´ll quickly find out that round stars are essential particularly in small items.

 

That has not been my experience, Mg/Al is too expensive for Chinese cakes, standard flash with 4-7FA is what I have found in the duds after shows. Being across the pond, do you think you get different cakes then us Yanks?

Edited by dagabu
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AdmiralDonSnider Newbie

AdmiralDonSnider

Posted
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AdmiralDonSnider, a hot magnalium based flash has less light output than a nitrate based flash??

What Ma/Al flash are you useing in your bomettes?

BJV

 

I´ve currently been into other projects and have left bombettes aside. I haven´t used MgAl based flash in these yet, but I´ll run some tests with a new construction and flash this winter. Up to now I´ve always used perchlorate/Al/ (S) based flash.

 

Concerning the light output: the problem is connected with the amount that has to be used as well as with general construction principles. If four grams of nitrate flash are used compared to just 1g of MgAl/perc flash, the nitrate will be brighter even if the comp itself doesn´t emit more light.

Furthermore much depends on the casing: Light output is a matter of break economy also. If the casing fails prematurely, a large explosion flash is the result (same principles as in round shells).

 

 

That has not been my experience, Mg/Al is too expensive for Chinese cakes, standard flash with 4-7FA is what I have found in the duds after shows. Being across the pond, do you think you get different cakes then us Yanks?

 

Ok. I think I´ll have to narrow my sayings down to consumer cakes (even if SOME display cakes do use MgAl flash). In chines consumer cakes MgAl based flash is ubiquitous, as MgAl is ubiquitous is their stars. Larger bombettes may be different, but I tried to recreate the small ones.

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dagabu Newbie

dagabu

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Concerning the light output: the problem is connected with the amount that has to be used as well as with general construction principles. If four grams of nitrate flash are used compared to just 1g of MgAl/perc flash, the nitrate will be brighter even if the comp itself doesn´t emit more light.

Furthermore much depends on the casing: Light output is a matter of break economy also. If the casing fails prematurely, a large explosion flash is the result (same principles as in round shells).

 

If one adds BP to flash, the light output is lessened to almost zero.

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AdmiralDonSnider Newbie

AdmiralDonSnider

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If one adds BP to flash, the light output is lessened to almost zero.

 

Didn´t know that. Obscured by smoke?

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dagabu Newbie

dagabu

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Didn´t know that. Obscured by smoke?

 

Nope, it has something to do with chemistry, we just covered this topic yesterday on Passfire and Fulcanelli and Shimitzu were both cited as reference.

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BJV Newbie

BJV

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If one adds BP to flash, the light output is lessened to almost zero.

 

dagabu, What percentage of BP to the flash?

Thanks,

BJV

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AdmiralDonSnider Newbie

AdmiralDonSnider

Posted
Posted (edited)

What about on bp coated rice hulls?

 

Where gunpowder is added to the flash for the break, some use grain and others coated rice hulls. But straight rice hulls in such small units won´t give admirable breaks.(Also here much depends on the case design and the diameter - in larger bombettes rice hull powder may be adequate.)

Edited by AdmiralDonSnider
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Richtee Enthusiast

Richtee

Posted
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If one adds BP to flash, the light output is lessened to almost zero.

Huh... cool. Wish I'd have known that when I was practicing. I LOVE the "sneaky" booms... people jump higher :D

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FrankRizzo Apprentice

FrankRizzo

Posted
Posted (edited)

Hi this is it how I made bombettes.

 

Wonderful video! If I may ask, what is the track that is playing ~1:33 during the second edit? Is it part of a set? :)

 

Small safety issue to think about as well. Glue guns have been known to short-circuit and spit sparks/fire while plugged in. It's best to have the gun plugged-in away from pyrotechnic composition, and unplug it when bringing it near the device being manufactured. The stored heat is usually good for at least half of a large glue stick before needed to be plugged back in.

Edited by FrankRizzo
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Mumbles Explorer

Mumbles

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I agree, quite good. The other thing that I would probably avoid is the scissors to cut the visco delay on the loaded bombettes. The shearing action has been reported to potentially cause ignitions.
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Col Newbie

Col

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Nice vid, Arte.

It shows just how much effort goes into making bombettes.

I always cut the fuse to length with a razor after pressing it into the clay bulkhead.. there`s nothing that can catch light at that point.

Its worth adding a tail comp for a bit more effect, it doesnt add very much to the overall construction time.

Edited by Col
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fredhappy Newbie

fredhappy

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Hi this is it how I made bombettes.

 

Well done! Thanks to your vid I learned some extra stuff about bombettes. I could not quite get my head around on how to get the visco in the clay plug, but now I understand the principle.

 

And I like that little tool you use. Did you made it yourself? It looks like wood to me.

 

Thanks for sharing......

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Arte valdo Newbie

Arte valdo

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FrankRizzo the glue gun was plugged out you can't see because it's out of frame.. track it's played from my computer.. sorry about that :) but scissors made from stainless steel so how can it be possible? I sow people use some special tools with the blade, in my opiniom is the same if you can explain me more details, please. The tool is simple made from wood.. I just wanna show basics about bombettes not something special.. I use nitrate flash with 7mic dark aluminum..

I would like to apologize for my poor English..

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