Ground Fireworks: Witness Epic 20-Minute Show

[BicycleTree]

Has anyone ever set off a really big professional-grade star burst style firework on the ground, in a desert somewhere? Maybe at the Burning Man festival?

I am thinking you could stand within 30 feet of the epicenter in a plexiglass enclosure, with ear protection, and be unharmed. What would an entire 20-minute fireworks show look like when experienced from almost ground 0?

 

[εllipse]

I am thinking you could stand within 30 feet of the epicenter in a plexiglass enclosure, with ear protection, and be unharmed.

You might want to wear sunglasses too.

 

[BicycleTree]

Elwood: "It's 30 feet to ground 0, we've got a Plexiglass bubble and a pair of earplugs, it's dark, and we're wearing sunglasses."

Jake: "Hit it."

 

[honestrosewater]

I've seen shows on professional pyro people. There was just one on yesterday. They have a control booth close to the launch site or whatever it's called. You can try some of these sites if you're bored being home sick. You're looking for Class B a.k.a. 1.3G Fireworks.
http://www.americanpyro.com/index.html (pro)
http://www.fireworksafety.com/safety.htm (seems mostly consumer)
http://www.wf.net/~lcrump1/display.htm
The state laws may specify minimum distances for everything.

 

[cronxeh]

Dear BicycleTree..

what is the point of this idiotic experiment?

 

[honestrosewater]

Separation distances are one of the most important features of display safety. The general rule of thumb is that the radius of the display site should be at least 70 feet for each inch of internal diameter of the largest mortar. All mortars less than 3 inches in diameter are treated as 2-inch mortars. (3.1.3) Therefore, a show with one or more 8-inch diameter shells would require a display site with a 560-foot radius...
- http://firechief.com/mag/firefighting_pyrotechnic_preplan/

Yeah, I'm home with nothing to do. There's much more to the article, BTW.

 

[BicycleTree]

Dear BicycleTree..

what is the point of this idiotic experiment?

To watch professional-grade fireworks go off all around you. It would be awesome.

No, I'm just kidding. It would be done just to piss you off.


If you're willing to sacrifice a little coolness, you could elevate the fireworks to a tower ten feet or so off the ground and have a whole field full of plexiglass viewing bubbles, two hundred people watching white phosphorous flares arching over them, streaking past them, and fissing down among them. In the fireworks that explode to hundreds of feet wide--the type that seemingly cover half of Plymouth Harbor--I wonder just how fast the sub-fireworks exit from the original explosion. That would probably determine the thickness of the Plexiglass.

Regulations might be a problem, but you could probably get an exception made if it were clear you are making proper safety precautions for viewers.

 

[Moonbear]

Regulations might be a problem, but you could probably get an exception made if it were clear you are making proper safety precautions for viewers.

Heh heh, that's an understatement. Just try to get an insurer to provide a policy for that. I expect regulations of such displays require insurance before permits are issued.

 

[Danger]

That would probably determine the thickness of the Plexiglass.

Forget acrylics—they'd melt. Maybe not all the way through, but enough to make them unusable in future and quite possibly enough to release toxic chemicals to the interior.

 

[BicycleTree]

Hmm--you could have the plexiglass sprayed with water or clear oil. Hopefully the trickles wouldn't interfere with the viewing. Maybe there is some solid heat-resistant transparent substance that you could coat the plexiglass with. Some reduction in transparency is OK--you can just wear lighter sunglasses to make up the difference. If you had a rounded bubble, the fireworks could never be in contact with the plexiglass very long.

 

[cronxeh]

plexiglass viewing bubbles.. interesting

consider this however: melting point of most plastics is from 310 degrees F (Noryl) to about 621 F (Teflon). Ah but those arent transparent! The ones you want are transparent plastics, and Acrylic has a continuous service temperature in presence of air of about 180 F max. Coefficient of linear expansion for Acrylic is 1.3 * 10^4. It ranks pretty good with other transparent plastics - at about 92% light transmittance - you may also consider Perspex (92% light transmittence, continuous service temp 180F); or better yet-

Polycarbonate aka Lexan (91% light transmittence, continuous service temp 475F - will start deflecting at 539F, coeff of linear expansion 3.9 * 10^5 );

PALSUN or PALTUF polycarbonate (89% light transmittence, continuous service temp 248 F)

Now the firework components:

Red strontium salts, lithium salts
lithium carbonate, Li2CO3 = red
strontium carbonate, SrCO3 = bright red

Orange calcium salts
calcium chloride, CaCl2
calcium sulfate, CaSO4·xH2O, where x = 0,2,3,5

Gold incandescence of iron (with carbon), charcoal, or lampblack

Yellow - sodium compounds ( sodium nitrate, NaNO3; cryolite, Na3AlF6)

Electric White - white-hot metal, such as magnesium or aluminum, barium oxide, BaO

Green - barium compounds + chlorine producer, barium chloride, BaCl+ = bright green

Blue - copper compounds + chlorine producer, copper acetoarsenite (Paris Green), Cu3As2O3Cu(C2H3O2)2 = blue
copper (I) chloride, CuCl = turquoise blue

Purple - mixture of strontium (red) and copper (blue) compounds

Silver - burning aluminum, titanium, or magnesium powder or flakes

How hot do those burn?

Kelvin Celsius Color
750 480 faint red glow
850 580 dark red
1000 730 bright red, slightly orange
1200 930 bright orange
1400 1100 pale yellowish orange
1600 1300 yellowish white
> 1700 > 1400 white (yellowish if seen from a distance)

So from 750 Kelvin (red) to 1700 Kelvin (white) - that's about 890F to 2600F

You see.. the sucky thing is.. 890F > 475F. That is where those coefficient of expansions come into play - you can even calculate a double integral of the time it would take for a flare to pass through an n inches thick transparent plastic bubble and cook them alive inside.

 

[BicycleTree]

Hmm... sounds like chicken wire in front of the plexiglass might be the only way to go. Unfortunately that would interfere with viewing.

It's not as bad as it seems, though. Most of these things would be moving at probably something like a hundred miles an hour when they hit the plexiglass. They'd bounce right off with hardly enough time to get it warm.