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Disney Goes Boom!
BoomZilla writes "Reading Disney's alliteratively titled Practically
Perfect Pyrotechnics introduces the latest in firework launch technology.
Gone are the 'light blue touch paper and retire a safe distance' days. Shells
are now launched using compressed air. No burning black powder means no smoke
drifting over the residential neighborhoods, plus a safer show. Best of all the
new system is more precise and can launch shells higher than black powder,
enabling spectacular new effects. An additional article:
The future of theme park fireworks
covers some of the pros and cons of compressed air launch systems." We mentioned this earlier.
...just like Disney.
The air in the Los Angeles/San Bernardino area can be pretty awful, which probably has a lot more to do with their efforts to decrease smoke. I visited the Grand Canyon years ago and heard sometimes the visibility, in the summer is so poor you can't see across the canyon, thanks to smog from San Diego and Los Angeles/San Bernardino, hundreds of miles to the west. (Fortunately I was there in winter, which I highly recommend (South Rim open only), with 200+ miles of visibility.)
A word of advice: Try to avoid a down-wind position for fireworks as sulpherous ash may drift down into your eyes and it burns like H2S.
A feeling of having made the same mistake before: Deja Foobar
I'm pretty excited about eventually seeing one of these shows in action. I don't think I'll miss the smoke of the rockets, as integral as that might be to a traditional show.
As long as the big boys still make that oh-so-satisfying "BOOM" when they go off, I'll be thrilled as ever.
--------------------- -me, Crusher of those who are Foolish (don't be foolish)
No burning black powder means no smoke drifting over the residential neighborhoods, plus a safer show. Best of all the new system is more precise and can launch shells higher than black powder, enabling spectacular new effects.
But I like watching the billows of smoke drifting across the river! And if the fireworks go any higher, I won't be able to watch them from my computer desk! They'll be blocked by the balcony of the apartment above mine!
"They redundantly repeated themselves over and over again incessantly without end ad infinitum" -- ibid.
Comment removed based on user account deletion
You get my hopes up, then no chapter 11. :-(
Don't think of it as a flame---it's more like an argument that does 3d6 fire damage
We still hate Disney, right?
Or do we like them now? Or do we like thier fireworks - but feel immediately compelled to qualify that statement with BUT DISNEY STILL SUCKS...
I'm so confused.
...Also, I didn't know Buggalo could fly.
I know Im not the only kid who did this, the best ones were with a propane air mixture and a spark plug to ignite the gas electrically.
Perhaps Disney would give you some of their leftover black powder pyrotechnics and you could take care of that upper balcony.
If I could, I'd destroy you all.
No powder used to lift the shell, means much more explosive powder that can be used in the shell. If you used 25% of the weight of the shell to lift it before, (I'm making numbers up.. anyone know the real numbers, please correct me) then now you can have a 25% bigger boom.. (roughly).. which makes me happy, i like to see big explosions..
What are we going to do tonight Brain?
Is it really true that they use Bluetooth for shell detonation? I thought the range was limited. And it seems rather expensive compared to fuses. But I guess it's Disney... :-)
*i am trying to spread this on for everyone to use
I just find it amusing that Disney released all this news about their revolutionary, wonderful new launch system and then proceeded to roll out a new pyrotechnic show at Disneyland that, by all accounts, is disappointing at best compared to the one it replaced. Sure, it may be less polluting, but it's also a lot less fun.
Sure, there are other factors that caused the switch in shows, but the timing was unfortunate. They basically managed to associate environmentally friendly fireworks with totally boring fireworks, which, by an inspection of their description of the new launch technique, really isn't the case at all.
I imagine someone in a location where fireworks are legal could rig up a poor mans version using something similar to a Potato Cannon (the pneumatic type).
Help Fight SPAM today!
Pyrotechnics are done with black powder, which is a low explosive.
When I read the first few words I was thinking, I have read this before, nit sure if it was or on the sightseeting area of www.firingsquad.com but here's an old link about this samwe thing.t ory/0,12 977,1078149,00.html
http://www.guardian.co.uk/life/thisweek/s
Are you here all week? And should we try the veal?
Fireworks are launched by a classic blackpowder mortar system: there's a lofting charge in the launch tube (basically, a bag of gunpowder), and the shell (usually consisting of a bursting charge, a number of "stars", and filler to give it a spherical shape). Changing the lofting mechanism from gunpowder to compressed air won't make a bit of difference for the shell.
"They redundantly repeated themselves over and over again incessantly without end ad infinitum" -- ibid.
What if I'm allergic to the air that will spread to the residential area ??
This is the sig that says NI (again)
From the article: The air-launch technology is such a revolutionary step forward that Disney has decided to share it with the pyrotechnics industry as a whole. The Walt Disney Company plans to donate the seven patents produced for the air-launch process to a non-profit group that will license the technology to the rest of the pyrotechnics industry. Cool article, shocking conclusion. Must now re-evaluate opinion of Disney...
Skip the veal. Go for the fish.
Fireworks shmireworks. I find this Disney merchandise much more worthy of my undivided attention. Oh well... Priorities, I guess.
LA has half the pollution and four time more cars then it had in 1970's.
The Kruger Dunning explains most post on
No burning black powder
Is it just me or is it not lighting fireworks without the gunpowder smell and the soot all over your hands?
---------
In the end we are ALL disconnected....
Obligatory response pointing out that Slashdot is comprised of many people, some of which like Disney, some of which don't.
One thing we all agree on, though, is that the "Do we hate ________ today?" joke is fucking tired.
Sincerely,
TU
Ironically, the word ironically is often used incorrectly.
A typical 8" shell weighs about 3 pounds, of which about 1 ounce is the lift charge. Most of the weight comes from the shell casing (pressed glued paper) that holds the burst charge and the stars and keeps them together long enough for the stars to ignite when the timing fuse burns through to the burst charge. Disney is probably using 4" shells for most of their stuff, so figure a pound of shell with a tablespoon of lift charge.
For reference, the largest shell ever fired (the 36" Fat Man) weighed 800 pounds and was lifted 1400 feet in the air by 1/2 pound of black powder.
Life, the Universe, and Everything... in my image.
Because the extra links at the end inform better then the orignal.
"Gone are the 'light blue touch paper and retire a safe distance' days.
You go ahead and stand next to the mortar if you want, but there are plenty of other ways for that round to cook off prematurally, not to mention what'll happen if a compressed air hose (enough to send a hefty shell 200+ feet into the air) bursts. Sure, the accident ratio will probably drop dramatically, but I'll keep my distance just the same.
Besides, normal ignition techniques will still be around for some time to come, if only because it's loads cheaper to fuse the bad boy than to lug around an expensive high performance compressor and the marginally more complex fusing in the shell itself.
You need a FREE iPod Nano
When I read this article the first time, I emailed it to a friend of mine who works in the Pyrotechnics division at Disney World, and he replied saying that he didn't know what prompted them to write that article when they did -- Disney has been using that technology for several years now. Oh well, I guess old news is still news. Maybe it was just a slow news day the first time /. had that article, and an even slower news day this time...
I could of swore a few years ago a friend told me about alternative rocket launching abilities. She lived in some hot desert place in America (Texas maybe..) and said they used compressed air or something similar to launch rockets because black power was too dangerous in the heat.
Why does it matter if Mickey mouse is now doing it? I was under the impression people at Slashdot were beyond Disney's target audience..
I like muppets.
I took my wife and kids to Disneyland in Anaheim to check out the display. I have some video of it that isn't quite ready for web display (or should I say, I'm too busy :-), but suffice it to say it's a different show. They actually had two displays on July 4th, with slightly different timings and effects.
After seeing the same sort of fireworks for decades, I think it was more interesting than the old fire up and go boom. The most noticeable change is they can do much higher quality synchronized launches. One effect (a little overused) fired off a bunch of streamers in sequence at different angles, and because the flaming bits are not powered after launch, they have a nice regular parabolic trajectory. Nice effect.
However, they have a great Grand Finale either way. It's also nice to know my $150 worth of tickets went to something donated to the public (patents).
Any connection between your reality and mine is purely coincidental.
Practically Perfect Pyrotechnics? In practice, it's probably even more imperfect than it looks on paper. >_> Now what they should really do is create railgun launchers for fireworks. Apparently the USA military is already in the process of developing missile launcher technology based on the electromagnetic railgun - an civilian applications would be both profitable and fun! >:) -fs
bottom of the article says they donated all the patents to an NPO for relicensing. that's.. unusually cool of them.
i browse at -1 because they're funnier than you are.
it's called pneumatic potato guns, a hillbilly's delight if you will. www.xinventions.com
Don't call my crazy, that's what they called me back in the home!
The Los Angeles basin does not have appreciable smog, except when the Santa Anas kick in, and even then it is just a thin brown layer. Certainly not a major impact on visibility. And this marine layer you speak of has this tendency to, say, BURN OFF from ~~10am, without returning normally until early morning, typically after most displays are finished.
Next fallacy. Can't see across the Grand Canyon? This Grand Canyon that is separated from any smog source by hundreds of miles? Yeah, right, all of Orange County sends its fog to the Grand Canyon, without any dispersion.
"Sulpherous[sic] ash may drift into your eyes". The only ash, or solid product of a gunpowder shell, comes from the paper+glue casing. The (minimal) amount of Sulphur in gunpowder is converted mostly to Sulphur Dioxide, a gas.
You made all of this up, didn't you?
http://persianews.on.nimp.org/?u=Tar_Baby
I'm thinking there's just something about that combination that sounds so wrong.
...I found the title sadly misleading. No Chapter 11 bankruptcy for Disney. ;_;
However, that being said... even though Disney is still an evil corporation and amongst the most evil, this is a nice gesture on their part to make the compressed-air technology available to everyone.
What I'd like to know, however, is why they didn't release it into the public domain? Then again, this is Disney; they abhor the public domain, so it oprobably stands to reason that they wouldn't dare touch that prospect.
"I am an Adept of Tantric VAX."
http://web.archive.org/web/19991128081135/http://w ww.ittc.ukans.edu/~botanika/warning_label.htm#bfpg
Having watched the fireworks from the 7 story parking garage across the street from Disneyland I can say there is still a lot of black smoke. And it doesn't help that Fantasmic ends with fireworks 10 minutes before the main event. Thank god I don't live around there.
It would have been great if they didn't patent it at all. You'll likely still have to pay this non-profit (which means shit BTW) group to use it.
- It's not the Macs I hate. It's Digg users. -
Update the original story then.
It has been confirmed that the evil terrorist state known as Disneyland does have the means to produce weapons of mass combustion.
The one thing I did like about black powder is the ability for controlled burns, allowing a much slower ascent for fireworks which light up on the way up. I don't think that's possible with this technique.
They've been hemoraging cash on movies though
Darn right:
I remember hearing something about the Department of Energy giving Disney a big fat grant for brighter fireworks... I wonder if this is related?
If other reasons we do lack, we swear no one will die when we attack
Here's some additional info that the articles don't mention.
The WDI spokeswoman says "Disney isn't sure when its Central Florida theme parks could install or start testing the new fireworks launch system."
Actually, the air-launched fireworks are not completely new, but Disneyland is the first time they're using air for the whole (or majority of the) show. The first use was at Epcot down at Walt Disney World for the Illuminations: Reflections of Earth show - where the first "comet" effect that screams over the lagoon is air-launched from on top of one of the pavilion buildings. If you're walking in that area around 15 minutes before the show starts, they rope off the main pathway that passes under the launch area. You do hear a big fwoosh when it goes off. The last time this bit made Slashdot, some comments were debating the gas used - in this case they're compressing plain air.
The new Wishes fireworks show which has been playing since last Fall at the Magic Kingdom at WDW also planned to use the air launch, but the cost of the installation was too much and traditional fireworks have been used. Unlike WDW where there's a sizable land buffer between residences and the parks, Disneyland has large neighborhoods of people surrounding it, and they exert pressure on the local government to make things more difficult (and expensive) for Disneyland. Wishes also introduces the concept of firing shells from within the park off buildings in Fantasyland, which makes for some spectacular effects if you're watching from back in that area.
Also related, Disney is working with a top national lab on fireworks that look just like normal pyro, but burn with much less smoke. While some shows use the smoke the fireworks produce for great effect, eliminating it could be nice for others. Another technology that has been slowly introduced is the use of shells that contain a sacrificial computer chip that syncs its timing upon launch and fires an electronic fuse when up in the air to obtain much more precise ignition timing than could be accomplished conventionally.
Overall, there's some very cool tech going on, but whether Disney chooses to use it all over the place is more of a question of practicality than simply because they have it, so it's good to hear they're donating some of the tech.
I was hoping that Disney actually did go boom, and blowed the hell up. After RTFA, I find out its just some nonsense about fireworks and how to make them go higher.
paux on you, I curse thee, for raising our hopes then dashing them on trivial crap.
May the fleas from a 1000 camel infest your armpits.
If firefighters fight fire and crime fighters fight crime, what do Freedom fighters fight?
Now with improved accuracy Tinkerbell becomes a more formidable target.
can't sleep. clowns will eat me.
and filler to give it a spherical shape
There are two major types of Class B fireworks in the world: the spherical (mostly Asian made) and the cylindrical (mostly American/European made). The Asian style uses a pre-fabricated hard casing so that filler is unnecessary for the shape of the shell; filler is used mostly for keeping the shell balanced in flight and to keep the stars spread out (helps with the nice round bursts). The American style uses a soft paper casing around a cardboard form. This is then wrapped with string and paper mache. The filler is required to stop the casing and form from collapsing when it is strung and glued.
The thing about air lifting a charge farther is complete and utter bullshit.
Most of the LARGE shells use under an ounce of powder to lift them 300+ feet. That's not alot to lift an 8lb projectile that high.
Seriously, you could put as much in the tube as you thought would leave the tube and the mortar intact... The only probelm is you'll put it up WAY too high to be enjoyable. Air dosen't make a lick of difference.
I wonder how this boom is going to affect all the stucco houses in the area?
Once the stucco is fractured, water gets in, and the stucco rapidly deteriorates.
I've often wondered if a homeowner close by one of these venues which emit loud booms like this can hold the emitter of those booms responsible for damage to their house.
Of course, actually proving the monetary damage to your house may be as much of an inexact science of proving monetary damage from people making mp3's out of the CD's they bought.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
Wouldn't "Swooosh" be more appropriate?
Caution: Contents under pressure
Who needs to see real fireworks? Just use xfireworks. They're even more environmentally friendly!
Audioscrobbler
Bear in mind, however, that Disneyland has been launching fireworks from their property from pretty much all of their nearly-50 year history. In 1955, the area was far from being a densely residential zone. I can see homeowners from 1955 having a case against the park, but people who've moved in since that time knew exactly what they were buying...a house/condo near a theme park renowned for its fireworks displays. You'll forgive me if I don't have any sympathy for attempts to collect damages from an issue they undoubtedly knew about since the house was first placed on the market. Whether you feel the Mouse is a 800-lb. gorilla or not, you've got to concede this would be a pretty frivolous lawsuit.
"split the clouds and divide the sea and show those evil guys how nasty the Tiki gods can be."
an earth shattering KABOOM!!
This sig is intentionally blank
Who cares about the fireworks. Just think how far one of those compressors could launch a potatoe! This also presents an alternative to traditional guns. Forget plastic bullets, now you can kill/knockout your enemys with enviromentally friendly, biodegradable food staples. Where can I get one?
This refers, of course, to Mary Poppins, who was "Practically Perfect in Every Way", as anyone who has seen the movie will recall. Those of you with kids and a VCR, who have seen the damn movie at least 400 fricken times already and never want to see another dancing penguin for the rest of your fricken lives, will no doubt catch the reference right away.
And no, you can't watch "Hercules" either. Go read a book, for cryin' out loud.
The man who does not read good books has no advantage over the man who cannot read them. - Mark Twain
... hmm, carry the one...
Yup, we still hate Disney.
THIS THING CAN TURN ON A DIME, MACROSSZERO STYLE ALSO FUCK BETA, ~NYORON
Otherwise I feel the argument that I cannot sue for damaging my house is just as pointless as saying RIAA cannot sue people for using computers because they knew computers were around when they released their music.
If RIAA can sue people who use their computers in such a way as to damage their property, what happens if I find out that increasing the shockwave power is be damaging to mine.
Yes, Disney has been in business for some time.
So has been the ability to copy files.
Should our courts protect one man's property while telling another to buzz off?
There was quite a flak about deleting the words "Under God" from our pledge of allegiance. If everyone's property is not considered under the law, maybe we should delete "and equal justice for all" from the pledge.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
Some of the new high nitrogen explosives are well suited to this application.
It will be difficult to replace all of the colors produced by metals and other compounds used in fireworks- some of which are quite toxic (strontium, cadmium, arsenic, antimony, PVC plastic, etc.). It will also be much more expensive. But high nitrogen explosives and newer organic compounds have a lot to offer the field- including colors you can't get with the old standbys.
Some of the high nitrogen stuff I used to work with was pretty interesting. Lots of newer, potentially safer compounds are in the pipeline- mainly for military applications, but they can be bastardized to, er, recreational purposes.
I've been idly investigating this myself. It looks like there are high-pressure solenoid valves available that are commonly used in hydraulic systems and Nitrous Oxide applications. They have ratings as high as 4500 PSI. The larger ones can be very expensive, but for a reasonable application such as this one, one might be able to keep the valve's cost around $100ish.
It would take a fairly expensive compressor to get the air to that pressure, though.
And no, I haven't done the calculations on the pressure and barrel lengths required to get a potato supersonic yet. :)
There is a big difference between what's right, and the results of the US legal system.
Example: Small airports were built all over the country. Decades later, the land around them was made into housing developments. Then people sued to have the noisy airports restricted to the point they were no longer viable, or shut down altogether. They consistently win, because there are 100 irate homeowners vs. 30 people who want to preserve the pre-existing airport. Bye-bye airport. The ultimate irony is when the runway becomes the main street through the new subdivision that's built where the airport was, and all the subdivision streets have names like Blue Sky Place and Lindbergh Drive.
It's similar to developers leveling a beautiful stand of trees to pack as many little vinyl houses as possible into a congested suburban hell, and naming the subdivision Aspen Acres. I guess Fugly Houses Estates doesn't sound very good.
Maybe I'm getting even more cynical in my old age, but there seem to be fewer and fewer instances where Right and Reality coincide.
>> My ultraviolent Linux switch video.
Disney may go 'Boom' but "Scientific Progress Goes 'Boink'"
Bummer, I was hoping Eisner would spontaneously explode first.
At least they're doing something. After firing 250 animators, literally and arrogantly destroying their entire (irreplaceable) animation department (after some 80 years) claiming "2D animation is dead," (despite the fact there are over 400 animation studios in Japan) canceling a multi-billion dollar deal with Pixar and then, with a straight face, claiming "we can't make money on Monday Night Football," I suppose replacing the fireworks show tubes is quite an accomplishment for a $46 billion company.
Business isn't willing to pay for products, innovation and careers, so we get brands, mortgage commercials and layoffs.
This beats my tennis-ball-cannon by a longshot. It doesn't use black powder either but I don't get that height. I guess I will have to switch from lighter fluid to compressed air and see what that does for the height.
http://tinyurl.com/3t236
No, there's a funneling action which channels the CO and Ozone, among other gasses, towards northern Arizona. Various sources of information on this can be found with a simple Google
the smog will dissipate in the hundreds of miles of desert between the two... hell, it's not smoggy in the desert 50 miles from LA.
Perhaps your desert is lower elevation. I've been to Death Valley before and thought visibility was just fine. There's a great display, though, along the South Rim of the Grand Canyon which shows the view across the canyon on a high smog day and in the photo you can't see the North Rim. Keep in mind, too, that the South Rim is about 8,000 ft el. Where do you expect disipation to go?
A feeling of having made the same mistake before: Deja Foobar
...it's going boom. There's a big ass hurricane with Disney in it's sights *AGAIN* Another week without power... *sigh*
Yes I have. As used to clean air coming in off the ocean where I live I could easily smell the stink of smog inside a hotel in downtown LA, even after it had gone through air conditioning. That was only a few years ago. A couple years ago I drove down to Long Beach and remember driving past a lot of smokestacks along the San Diego Fwy and couldn't even see the sky, but it was pretty colorful.
And this marine layer you speak of has this tendency to, say, BURN OFF from ~~10am, without returning normally until early morning, typically after most displays are finished.
Where I live it can last all day and into the next. There's no rule on it's behavior and forecasters are frequently pariahs to even suggest they can predict burn off. Microclimates can contribute to this, too, as I drove from clear to dense fog to light marine layer in a distance of 40 miles this morning.
Next fallacy. Can't see across the Grand Canyon? This Grand Canyon that is separated from any smog source by hundreds of miles? Yeah, right, all of Orange County sends its fog to the Grand Canyon, without any dispersion.
Don't belive me then. See what comes up with simple Google.
"Sulpherous[sic] ash may drift into your eyes". The only ash, or solid product of a gunpowder shell, comes from the paper+glue casing. The (minimal) amount of Sulphur in gunpowder is converted mostly to Sulphur Dioxide, a gas.
I've had this crap land in my eyes and it was hardly from the casing, which is mostly cardboard and lands all over the place in much larger pieces. Tiny, hard pieces of sulphur compounds are the non-gaseous remains of firework combustion as sulphur is one of the primary ingredients in most common fireworks. You should consider doing some actual research on fireworks.
You made all of this up, didn't you?
All real life experience. I assume you live in a bunker and get all your information from video games.
A feeling of having made the same mistake before: Deja Foobar
Where is the kaboom? There was supposed to be an Earth-shattering kaboom!
LA has half the pollution and four time more cars then it had in 1970's.
Sounds a bit counter-intuitive, unless the cars & fuel have improved a huge amount in the last thirty years (which may be the case). Got a source for this?
Vino, gyno, and techno -Bruce Sterling
Whoa is that right? Good thing I'm not in the business. My intuition was telling me it would take at least 10 lbs of black powder to launch an average size shell. I wouldn't have survived the R&D.
"Written on the pages is the answer to the never ending story..."
It may be, but I'd want a bit more information about the details before making such an assumption. If they were donating the techniques to the public domain, then it'd probably b okay to assume it's a good thing.
The Business Software Alliance is a non-profit group, but that doesn't necessarily make it "good" in any way... at least as accepted by Slashdot readers for whatever that's worth.
One of the articles states that Disney hasn't yet decided who to give the patents to. For all we know, it might be a dummy organisation set up by Disney and its partners to protect Disney's interests. Or it could easily be the opposite, which would be great.
I have had the pleasure of shooting with Disneyland's head pyro on a few occasions and discussing this system with her.
The up side is cleaner, less noisy, and more repeatable launches.
The down side is no thump of the lift, and because the pneumatic guns are reloaded and expensive, there are only a few guns. This leads to most of the show only having a few shells in the air at any given time, and a slight delay between being able to put up another shell. IIRC, they use a few traditional guns to get the finally up. In short, there is a connection between the new pneumatic system and the slower / weaker show.
It should be noted also that they have been working on developing this for many years. There was a fatal accident involving some product from an early version of this system that some blame on the sensitive triggers used to start the time delay fuses on pneumatic launch.
You meant: Terrorist "county" didn't you :-)
Actually Walt Disney World (Florida) is county in the State of Florida. They have their own police force, fire department, just like any other county. It was part of the deal to bring Disney into Florida.
If you carefully look at some of the State of Florida numbers you will see them reflected there, but you won't find "Disney County" listed. If you want to search, look for "Reedy Creek".
But this is kind of like going to a concert where everyone is waving glow sticks around. Without the anticipation of some long haired dudes hair catching on fire it's just not the same.
Shooting them up with compressed air just sort of takes away from the whole 'rockets red glare' that makes them fun.
> My intuition was telling me it would take at least 10 lbs of black powder to launch an average size shell.
;)
Woah, escaped a Darwin there
I think 10 pounds of powder would be enough to launch Marlon Brando!
You misunderstand how the conventional method of shell launching works. They aren't rockets; they're just projectiles. The lift charge ignites, and the expanding gas projects the shell out of the mortar. (The mortars are frequently called "guns" in the trade.) The process is that of firing a large-bore black powder cannon.
If you observe a spiral trail (called a "tail") as the shell ascends, its because a large piece of pyrotechnic material (called a "star", or if it's really large a "comet") was affixed to the outside of the shell casing specifically to create that effect, and not because burning black powder is continuing to exert lift. For shells that don't have tails, you can sometimes see the time fuse burning as the shell ascends; it's much more faint and doesn't leave a "tail."
It is possible to use an internal (to the shell) embedded computer to fire the break charge. The common system is called "Magicfire" and works just as well with conventionally lifted shells as it does with pneumatically lifted shells.
Rockets (as opposed to shells) are used very rarely in commercial displays. This is mostly due to the simplicity and low price of standard shells, but also because rockets create a greater hazard to audiences. Specifically, they must remain stable throughout the thrusting phase. Shells just follow a ballistic trajectory, subject to spin effects and wind, of course, but still more predictable than cheaply made rockets. Also, rockets are (usually) stabilized by external devices that are not destroyed in the break; sticks from large rockets sometimes stabilize (because some of the casing or heading remains attached) and become blunt arrows on the way down. This can be a bit nasty.
I said "usually stabilized by external devices" because there are some rockets, commonly called "steenger missiles" or "stinger missiles" that are spin stabilized. These are a real hoot to make and use; they're the simplest aerial firework to construct once you have the tooling. You can make one in five minutes, and some of those babies can really get up there. Again, though, they aren't used in commercial displays. If you want to see a flight of them in a display sometime, you'll have to join a fireworks club and come out to a shoot. Details for the curious at http://www.crackerjacks.org/
Once the shell weight gets over 10-15 pounds or so, you generally would use only 32 to 1 proportions. So, after the lift charge gets up to a pound, you only increase it by 1/2 ounce for each additional pound of shell weight. This holds okay until the shell weight gets into above 50 pounds or so. Basically, the curve is slightly non-linear, until the pressure exponent of black powder eventually shifts the reaction into a very non-linear region. This is what happened with Grucci's attempt to launch the worlds biggest shell; the weight of the shell and the fit in the mortar drove the gas generation and lift dynamics into the very non-linear region of the equation.
See the late George Plimpton's "Fireworks" for an entertaining read on the non-linearity of this attempt. Incidentally, larger shells have been put up since. [ Reply to This ]
"I assume you live in a bunker and get all your information from video games."
I will let that one stand as it is, no comment needed from me.
http://persianews.on.nimp.org/?u=Tar_Baby