Amateur pyrotechnics experiment: Puzzling results

[Hypercube]

Seeing as it's Victoria Day weekend, I decided to carry out a little experiment with a firework. I've always been fond of amateur pyrotechnics, so I decided to see what would happen if I put the core of a simple 'Air Bomb' firework wrapped in electrical tape, just to make sure it didn't somehow fall apart, into a can with some sparkler powder, and then light it.

 

For any of you who don't know what an 'Air Bomb' is, it's basically a really simple firework where you light the fuse, something shoots out of the end, which a few seconds later makes a loud bang, and that's it. So I figured that more or less the same would happen here. What actually happened, however, I can't really explain. In general, the same thing happened as would have happened if I used the firework the proper way, except for the fact that the bang was much louder than it normally would have been; it sounded like a gun had gone off.

 

Does anyone know why this would be? I mean sparkler powder is not explosive, it simply burns in a manner akin to thermite, so I don't see how that could have contributed. Does anyone have any guesses?

[Klaynos]

The tape containing the blast for slightly longer would be my guess. You get a higher pressure build up and therefore a louder bang.

[Hypercube]

The tape containing the blast for slightly longer would be my guess. You get a higher pressure build up and therefore a louder bang.

 

Maybe, but the tape was FAR from airtight though. And even if it was, the burning sparker powder that the core was immersed in would have melted it long before it actually went bang.

[John Cuthber]

You need to do a lot more research before you carry on playing with explosives.

[zapatos]

Don't know if this is related but we sometimes make 'bombs' out of sparklers.

 

Group five sparklers or so with the top of the center sparkler sticking up about an inch higher than the others. Wrap tightly with multiple layers of duct tape leaving the one inch of the center sparkler exposed. Light the center sparkler and run like hell. Shockingly loud explosion.

 

Edit: Just thought of another fun 'bomb'.

 

Take an empty plastic liter bottle, drop in a piece of dry ice and a small amount of water, screw the cap on tight and again run like hell. Sometimes takes a minute or so to explode so don't approach it. Also shockingly loud.

Edited May 20, 2012 by zapatos

[Hypercube]

You need to do a lot more research before you carry on playing with explosives.

 

Give me a break! What I did was perfectly safe, barring someone standing directly over the thing or startling someone into a heart attack. It's not like I was making home-made dynamite or something. This is a firework that you can usually buy in the local dollar store, and it is one of the simplest ones there is. In fact, I would say that if anything, I made the firework more safe because I took away it's ability to shoot anything. I might not know all of the physics behind what I'm doing, but I certainly know when what I'm doing is safe or not.

[CaptainPanic]

Seeing as it's Victoria Day weekend, I decided to carry out a little experiment with a firework. I've always been fond of amateur pyrotechnics, so I decided to see what would happen if I put the core of a simple 'Air Bomb' firework wrapped in electrical tape, just to make sure it didn't somehow fall apart, into a can with some sparkler powder, and then light it.

 

For any of you who don't know what an 'Air Bomb' is, it's basically a really simple firework where you light the fuse, something shoots out of the end, which a few seconds later makes a loud bang, and that's it. So I figured that more or less the same would happen here. What actually happened, however, I can't really explain. In general, the same thing happened as would have happened if I used the firework the proper way, except for the fact that the bang was much louder than it normally would have been; it sounded like a gun had gone off.

 

Does anyone know why this would be? I mean sparkler powder is not explosive, it simply burns in a manner akin to thermite, so I don't see how that could have contributed. Does anyone have any guesses?

The something that shoots out the end is still contained in some container. If you make that container stronger with tape, the bang will become louder.

 

Such a container does not have to be air tight. If the gases that are created in the explosion cannot escape quick enough, the pressure will build up. At some point, the pressure will rip open the container (that actually all happens in a fraction of a second). But in the case of your air bomb, it seems that the pressure can build up even more (there is enough powder to make more gas)... so if you make the container stronger, more gas will be formed before the container breaks, and that bang will be louder.

 

The original container it was in is already mostly closed

[John Cuthber]

Give me a break! What I did was perfectly safe, barring someone standing directly over the thing or startling someone into a heart attack. It's not like I was making home-made dynamite or something. This is a firework that you can usually buy in the local dollar store, and it is one of the simplest ones there is. In fact, I would say that if anything, I made the firework more safe because I took away it's ability to shoot anything. I might not know all of the physics behind what I'm doing, but I certainly know when what I'm doing is safe or not.

 

That's the second illustration of why you should stop.

 

You did not know what you were doing.

Playing with explosives when you don't know what you are doing is bad idea.

Thinking that "What I did was perfectly safe" when, by your own admission, you didn't know what you were doing is another bad idea.

 

People whoo get killed playing with these sorts of things think "What I did was perfectly safe", right up until it's too late.

[SomethingToPonder]

The tape holding the rocket in tighter packed, And also the can would echo and explode at the same time.

[King Thando Mathe]

Greater force was required to break up the tape,bearing in mind the pressure build up as well.This results in a greater amount of air being pushed outwards (expanding) and leads to louder sound since sound comes from rarefaction and contraction of air molecules! bang

[Chrispen Evan]

if the sparkler material contained powdered aluminium then you would get a more energetic bang.