Ok,
Take a fiberglass propane tank, wrap with det-cord, & launch.
Detonate by delayed fuse. Launch by black powder tube.
Det-cord provides a cutting charge to cause a BLEVE & heat to ignite the fuel.
The Metal regulator valve needs to be replaced with a fiberglass plug, so no-one gets whacked with it, but 'eh.
NOTE: Class1 explosives like Det-cord launched into the air is very illegal, but other detonators could be used. Other slow acting detonators may be better because the BLEVE may not happen when a huge rupture occurs so quickly with det-cord.(I'm just guessing though)
I called my local Fire-Marshall. Boy he was not enthused about this. But I called my local fireworks company and they started giggling on the phone.
Could you just imagine hundreds of these in the air all at once? Boom, boom, boom, boom!
Now, I call that FIREworks.
Oh by the way, over water is prob the safest, flaming debris and all.-- danheathmoore, Jul 05 2008 Flare heating, shotgun slug rupture http://www.youtube....watch?v=I0u-dgueN8k [danheathmoore, Jul 05 2008] Flare heating, shotgun slug rupture2 http://www.youtube....watch?v=KAyuq8sDCeg [danheathmoore, Jul 05 2008] Mythbusters propane explosion http://www.youtube....-Gk&feature=relatedCould you imagine this in the air? [danheathmoore, Jul 05 2008] WOW! http://www.youtube....watch?v=9DVsdf87aj4Neato! [danheathmoore, Jul 05 2008] Stoichometry http://en.wikipedia.org/wiki/StoichometryAlso called "Stoichiometry" [8th of 7, Jul 06 2008] On the basis that not everybody here is a propane firework expert, maybe you could clarify "BLEVE"?-- david_scothern, Jul 05 2008 "Boiling Liquid Expanding Vapour Explosion", a typically non-stoic low-brisance combustion effect - not a true detonation.
A kissing cousin to fuel-air explosives, but with FAE's a great deal of effort goes into atomising and dispersing the charge to get it as near to stoic equilibrium as possible before detonation.
You wouldn't need det cord to rupture the container.
A major problem will be to get your container strong enough to withstand the whack of a mortar launch (even using the relatively gentle push of BP) without making it strong and thick enough to scatter dangerous FOD. And using an flammable liquid, the effects of FTL's, mining and low breaks could be rather loud and expensive.
[+] anyway for an ingenious and dangerous use for flammable materials.-- 8th of 7, Jul 05 2008 Wouldn't the fuel-air be easier? to do some kind of non-flamable explosive to spread a nice volume of flour then ignite the center with a second charge? I think this would make a nice bass note for your local version of the 1812.-- MisterQED, Jul 05 2008 // a typically non-stoic//An combustion effect that /doesn't/ achieve happiness by submission to destiny?-- AbsintheWithoutLeave, Jul 05 2008 What is a FTL mining and low break? Anyways the hemispherical tank ends might be able to handle a mortar launch. An FTL would be a problem though.-- danheathmoore, Jul 06 2008 Yeah, a fuel-air would be easier but I want a raging compressed fireball. fuel-air explosions do more damage but that's not what I want.-- danheathmoore, Jul 06 2008 hydrogen/oxygen mix in a balloon with a small battery pack and an LED to light it up before you light it up.-- FlyingToaster, Jul 06 2008 [AbsintheWithoutLeave] <link>
// What is a FTL mining and low break? //
FTL: Failure To Launch
Mining: The lifting charge fails, and the main charge of the device explodes in the launch tube, throwing the contents upwards. This can destroy the tube.
Low Break: This can result from a weak lift charge, meaning the device is launched with well below normal velocity, or from a normal lift but with a malfunction of the pyrotechnic delay train to the bursting charge. In both cases, the main charge is triggered at very low altitude, often just after leaving the muzzle. In extreme cases of lift failure, the device may have just enough momentum to hop out of the tube and land on the ground nearby.
A lift failure fortunately produces a very distinctive sound, best described as "ffooop", which gives those in the know a short but useful period of time in which to indulge in a bit of grass-biting.-- 8th of 7, Jul 06 2008 // Low Break: This can result from a weak lift charge...//
At my local municipal fireworks show, there were quite a few (maybe six, maybe more) shells that exploded at a height of about 1/4 their starburst radius. The fireworks were launched far enough from the crowd that none came particularly close to reaching the fence; I was curious whether anyone deliberately does such a thing (cool effect) or whether QC was particularly bad.
BTW, the show began and ended with a ground-based fireball that might have been similar to a BLEVE (though I've never seen the latter).
As for this idea, I would side with FlyingToaster, except I would think it best if the balloon didn't have the hydrogen pre-mixed with nearly enough air for full combustion. It might be good to mix in a little air to start the effect, but mixing in too much air would limit the size of balloon one could safely use without causing hearing damage.-- supercat, Jul 06 2008 // deliberately does such a thing (cool effect) //
No, not if you're underneath it. Sometimes lift charges are removed from small shells to convert them into mines; but no pyrotechnician who wished to see another sunrise would knowingly use a shell with a weak lift.
// ground-based fireball //
They can be bought "off the shelf" but the usual method is to use a bomb tank. Take an 11Kg propane bottle and slice the top off. Put a No. 4 maroon and a flash pot in the bottom, suitably cabled to a firing point. Put two plastic bin lines - one inside the other for safety - in the bomb tank and tape or wire it round the top. Pour in petrol (gasoline) - about 10 litres is typical.
Retreat to a safe distance and fire the pyro. The effect is dramatic, and immensely satisfying.-- 8th of 7, Jul 06 2008 //No, not if you're underneath it. Sometimes lift charges are removed from small shells to convert them into mines; but no pyrotechnician who wished to see another sunrise would knowingly use a shell with a weak lift.//
I would expect the fireworks were fired remotely, and that there was nobody within the maximum blast radius of where they originated. If the effect weren't intentional and were thought dangerous, I would have expected the show to be cut short at some point.-- supercat, Jul 06 2008 fuel:air is not the kind of thing you'd generally want to use for public fireworks.
Take your regular firework: if it misfires while up in the air and lands then even if it goes off, half the explosion will be into the ground.
FA on the other hand, the entire mixture will not only combust above-ground, but can be moved closer or into the crowd by the wind.
Not generally a good idea.-- FlyingToaster, Jul 07 2008 // I would expect the fireworks were fired remotely, //
Some are, some aren't. Some smaller shows are still hand fired. Even with electrical initiation, sometimes the cables get broken or pulled, and the backup team has to move in to keep the show going.
And just now and again, you get a ruptured tube or a rack fire, which can disrupt the aim of the devices and be very dangerous. The only thing to do is get in there fast with extinguishers, get the fire out and disconnect the fuses. The operator on the desk may have stopped the sequence by then but sequences are often linked by delay fuses; once initiated, they burn at a steady rate, firing devices in sequence and the only way to stop them is to cut the fuse line; water or CO2 won't work as the fuse is plastic-cased and can burn under water (P.I.C.).-- 8th of 7, Jul 07 2008 random, halfbakery