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ossassin
December 7th, 2003, 08:20 PM
Illumination rounds are crucial for modern warfare. If the world's major powers collapse, a few of these would be good to have. The military uses a rifle-mounted 37mm launcher similar to the M203 to shoot these. They usually consist of a propelling charge, a timed fuse, a slow-burning main composition and a parachute to hold it in the air for several minutes. Does anyone have any ideas on how to make these? The hardest part to me is finding something that would burn very slowly and very brightly.

Mods, I wasn't sure if this should be under Improvised Weapons or Pyrotechnics, so I put it here, in accordance with the rules. Please move it to the appropriate section. If you don't feel that it's a valid topic, delete it. I'd rather you do that than ban me. :)

Bert
December 7th, 2003, 09:23 PM
The hardest part to me is finding something that would burn very slowly and very brightly.

Try about 40% NaNO3 : 60% coarse Mg powder coated with linseed oil.

The flare isn't the hard part in my experience- Getting reliable parachute deployment & function is a bit of a task. I haven't made these to fire from military launchers, only from fireworks mortars of larger dia. than 37 mm (4" is a good size).

ossassin
December 7th, 2003, 10:40 PM
Interesting idea. Do you think a small explosive charge would be necessary to deploy the parachute and/or to remove the casing from the flare?

Bert
December 8th, 2003, 01:02 AM
Yes.

a_bab
December 9th, 2003, 10:54 AM
A composition which burns slow and extremly bright is one containing barium nitrate and Al powder (can't remember the percentages). It worked great for me, and the light is white.

vulture
December 9th, 2003, 10:55 AM
PTFE/Mg flares should work nicely too. Although they lose quite a bit of power as IR radiation.

IIRC, Zr compositions are also used because of it's (Zr) very high light output.

Bert
December 9th, 2003, 12:09 PM
Tried to post this before, let's see if it's working now-
(edit)
Nope, looks like the attachment feature has been disabled again. I'm trying to post a diagram of a parachute shell.

Axt
December 9th, 2003, 12:24 PM
I believe its just in the watercooler Bert, youve never been able to insert images into here. Threads like this should really be put in their right place .. this one being in the pyrotechnic section, remember all these watercooler posts eventually get deleted.

Bert
December 9th, 2003, 01:13 PM
Thanks, Axt.

Mods, I agree, this is a subject worth moving to the pyrotechnics section.

Anthony
December 9th, 2003, 02:36 PM
Since Bert obviously has good information on this subject, and the topic is fairly original, I do agree that it would find a better home in the Pyrotechnics section.

Moving...

Bert
December 9th, 2003, 02:47 PM
Thanks Anthony!

OK, here's a diagram of the fireworks version of a parachute flare shell.

The "spolette" is a type of time fuse.

The "filler" around the parachute is to prevent it becoming burned or melted during expulsion from the shell. Sawdust, rice chaff, bran, cottonseeds or similar cheap fillers are used.

The caseing is made strong at the end holding the weak bursting charge and weak at the end with the parachute.

nbk2000
December 9th, 2003, 08:41 PM
You may wish to use only IR compositions for your flares. Night vision is fairly cheap now, less than $200 dollars, and would give you a huge advantage over the typical rabble who don't have a clue to the use of NVDs.

The flares would light up a sizeable area without giving away your position to anyone who does have NVDs like a spotlight would, and doesn't help or warn non-equipped enemies that they're visible in (what to them is) total darkness.

ossassin
December 9th, 2003, 08:50 PM
Any idea of what sort of compositions I should use? You'll have to forgive me; I'm not very experienced in the field of pyrotechnics. It seems like any explosion would give off infrared, but would it illuminate a large area with it? That wouldn't be pitch black, either, so I assume that you have a certain composition in mind.

Bert
December 9th, 2003, 10:58 PM
An infrared flare mix using (fairly) common ingredients:

Silicon powder 10%

Potassium nitrate 70%

Hexamine 16%

Epoxy resin 4%

ossassin
December 10th, 2003, 01:07 AM
I'll get right on that! :) I'll make sure to post an update once I have a successful test. It's nice to have a legal experiment that you can really carry out without fear of prosecution.

By the way, does anyone know where to get silicon powder? I've never heard of using that in pyrotechnics. Is there an easy OTC source?

Bert
December 10th, 2003, 03:23 AM
Silicon is used for hot primes. It's available from pyro suppliers- Firefox, Skylighter, etc. Why wouldyou think that such a project would be any more legal or immune from prosecution than others mentioned here?

Crazy Swede
December 10th, 2003, 12:55 PM
When it comes to the production of invisible light, or NIR (near IR) radiation, the most important thing is to keep the pyrotechnic reaction and flame as cool as possible. Bright sparks must be avoided and the most successful compositions actually burn in a smouldering way. Silicon has mostly been used as a secondary fuel, probably to ensure heat propagation in the otherwise cool burning composition.

Organic fuels, like hexamine and resins, are often used together with oxidisers and additives that contribute as little as possible in the visible part of the spectrum.

The radiation from potassium lies just at the border of visible and invisible light. It is effective to use potassium nitrate and/or perchlorate in a "black light" flare if it's okay to reveal the source of radiation. If the flare has to be totally invisible to the unaided eye however, potassium compounds cannot be used!

Some patents, US5811724, US5639984 and US5587552, describe the use of caesium nitrate or rubidium nitrate that emit in the NIR region. They also describe how the peroxides of barium and strontium, which in ordinary compositions would contribute with lots of visible light, can be used if the formula is composed in such a way that the formation of light emitting species is minimized.

ossassin
December 10th, 2003, 07:39 PM
Bert, nothing is illegal about loading your own "flares" for a 37mm launcher. Only rounds that you actually shoot at people are illegal (even non-lethal rounds). Many things on this forum relate to the illegal manufacture of explosives and weapons.

Bert
December 10th, 2003, 08:46 PM
ossassin-

You're in the US, correct? You might want to read THIS (http://www.atf.gov/explarson/fedexplolaw/index.htm) . The ATFE has made a determination that hobbyist experiments do not fall under their definition of "business", and has so far allowed small scale experimentation to go on "under the RADAR". But they DO NOT ignore storage of pyrotechnics in non approved facilities- They might not care that you built and tested a 37mm illumination round. But if you make several and store them (even overnight) other than in an approved magazine, you've done something they WOULD bust you for. And if you sell or even give away a single such item, you're breaking the law and they will fry you for it if they become aware. Regardless of whatever politicized enforcement actions ATFE has been involved in, they really do have a legitimate function- Safety. Hence their primary interest in those who make and store explosives is actually that they be stored properly and with good record keeping of any distribution.

Lots of unlicensed, small scale experimenters and hobbyists flout these regulations, obviously. But the day you attract their attention, have an accident, piss off your neighbor, shoot something that a cop sees and objects to- You'd best not be storing anything, and better not have given any away to your buddies, let alone sold something. ATFE is allowed to go anywhere that explosives related accidents have occurred, BTW. No need to ask for a warrant, they just DO IT. And you don't want to be the object of such a search.

I'm sure this information isn't likely to change what you all are likely to do- But you should allways know what laws you are breaking. In addition, you allmost certainly will have state and local or municipal laws, which are usualy far more restrictive than the federal ones.

ossassin
December 11th, 2003, 02:37 AM
A 37mm launcher is exempt from that, because it isi a signalling device for which no anti-personnel rounds have ever been made. Go here (http://www.37mm.com/legal/). You can reload/manufacture your own ammunition for it, although there are restrictions as to what types you can make and how much powder you can use.

Bert
December 11th, 2003, 09:58 AM
If you manufacture stars, burst & etc. and have them in "bulk" (not loaded into the finished article) they must be properly stored regardless of what you're using them in. The ATFE doesn't consider the launcher and signal type cartridges a destructive device, that's fine. If you are storing pyrotechnic compositions however, you ALLWAYS have to store them in an approved magazine. It's a completely separate issue from the DD classification of the completed round and launcher. The letter from ATFE spelling this out is on the site you directed me to. http://www.37mm.com/legal/hobbyexplosives.jpg

ossassin
December 11th, 2003, 10:26 AM
Well then where can I get one of these "magazines"? According to some of the websites I've seen, many require a license. :confused: Where can I get one no-questions-asked to stay legit?

EDIT:
By the way, the laws that latter refers to can be found here (http://www.atf.gov/explarson/fedexplolaw/subpartk.pdf).

Bert
December 11th, 2003, 11:25 AM
You can buy a type 2 from several manufacturers. Here's a link to a small unit suitable for indoor use: http://www.merlinmissiles.com/explosives_magazine.html The license isn't to BUY the magazine- However, the magazine and a proper place to put it with the specified safety distances are required for a federal license. You're supposed to have the magazine inspected and your license issued before you use it. If you're old enough, don't have a felony conviction and have a suitable area, getting an ATFE license is not a huge deal. Local laws are usually a bigger problem- Most magazines in the US are in unincorporated areas for this reason (the first thing a municipality usually does is restrict what you can store inside city limits-) And you can build a magazine yourself, if you're handy. I've seen an ATFE inspected indoor magazine made out of a 55 gal drum by lineing it with old carpet scraps and having a good locking mechanism welded on. ATFE will let you submit a drawing of your proposed magazine design and tell you if they'll accept it or not-

ossassin
December 11th, 2003, 07:16 PM
One minute you say that a license isn't necessary as long as you store the rounds properly, and the next you say that a license is necessary before you can use the magazine. I was pretty sure that I didn't need a license as long as I kept them in a magazine.

Bert
December 11th, 2003, 09:24 PM
Sorry, I don't mean to be confusing. But we're talking about government here!

A license to manufacture pyrotechnic compositions and devices for your own non-commercial use is not necessary. If you make it and use it immediately, you need not worry about storage or licensing. That's what the ATFE ruling (http://www.37mm.com/legal/hobbyexplosives.jpg) letter on your 37 mm site says-

BUT-

In the same letter, ATFE says bulk pyrotechnic mixes and components must be stored in compliance with sub part K (http://www.atf.gov/explarson/fedexplolaw/subpartk.pdf) . And that requires you to put them in a magazine- Which ATFE has to approve before it's acceptable. And the way you get that magazine approved- is you apply for a license. Yes, it's catch-22. If you just want to mix a bit of this and that and burn it immediately, no federal license needed. But if you want to store anything, you're going to need the license because you need it to get your storage (magazine) approved. You would also need to keep records of what goes in and out of the magazine. I'd suggest you get an ATFE type 50 manufacturer of display fireworks, you would be covered for just about anything that you could want to build short of HE. Yes, it costs $200.00 for 3 years. But you could then legitimately pass your products on to others...

I'd guess this discussion is pretty much academic. Somehow, I don't think too many of the US based roguesci.org folks would be interested in getting legal. Between the hassle and expense, and the paranoia of having "them" know who you are, it seems unlikely. But if anyone really cares, maybe a new thread could be split off about this? Like I said earlier, even if you aren't going to follow the exact letter of the law, you should at least know what it is.

ossassin
December 11th, 2003, 11:01 PM
That magazine that you showed us earlier seemed to be good enough. Would I have to get it approved even though it's commercially manufactured? It says that it exceeds BATF regulations, but it doesn't say that it's been specifically approved.

As to the relevance of the topic, I'm sure that many members would like to legalize their projects if they can do it easily. This magazine (http://www.merlinmissiles.com/explosives_magazine.html) looks like it's just what they need. :)

Bert
December 12th, 2003, 10:19 AM
That magazine is intended for folks who do high power rocketry- They need to store their fuel grains for reloadable motors. People who want to have more than 5lb. of black powder around would also want something like this. We've got a couple of similar boxes, they are used as "day boxes" for holding the amount of explosives to be used during a work day, as on a small blasting job. You need two if you're blasting, one for the caps and one for the explosives.

Getting a magazine approved includes not just the physical construction of the magazine, but its placement. That is, it must be located in an area sufficiently far from occupied structures, highways, railroads and any other magazines as specified in the distance tables you will find at the end of sub part K. For less than 1,000 lb. of low explosives, you would only need 75' of space from occupied structures and highways, and 50' from another magazine. This would be the most likely range for the project you're considering in my estimation. Got a shed or garage at least 75' from your house or your neighbors?

And, remember: Your local laws are almost certainly more restrictive than the federal ones, you will need to check these out too-

nbk2000
December 13th, 2003, 12:54 AM
Here's a an IR-DIM tracer formulation I found that's being used by Thiokol for the US Army. It'd be a start for formulation an IR illumation formulation as it's totally invisible to the naked eye, not even a glowing ember, though I don't know what spectral emissions or intensities are for it.

Barium Nitrate 10.0%
Silicon (99.9% Metals Basis) 1.0%
Calcium Resinate 10.0%
Magnesium Carbonate 10.0%
Barium Peroxide 34.5%
Strontium Peroxide 34.5%

Also, the term "Blacklight" would be for UV only and, as far as I know, there are no purely UV emitting pyrotechnics.

Crazy Swede
December 13th, 2003, 11:46 AM
NBK, You're right about that that it's almost impossible to create substantial amounts of UV radiation with pyrotechnics. Only the hottest Mg/Teflon-mixtures provide small amounts of radiation in that frequency range. What I actually meant was "Black Night Flares", as these devices were called in a patent (I read it wrong though!).

The formula you quote is indeed invisible when shot as a tracer, but if you whatch it burn stationary, as loose powder or as a pressed pellet, there is a flame similar to a stearin candle. When the projectile is shot however, the flame is enlarged because of the vacuum behind the bullet and the flame becomes more or less transparent, though still emitting in the nearest IR range. (Yes, I have been working with compositions like this!)

During experiments of my own, I have found that slow burning compositions based on potassium nitrate/organic fuels, with hexamine added as a flame expander and coolant, works well in a parachute flare since they are so dim that it�s usually hard to spot them without night vision goggles.

The problem with most NVD's (Night Vision Devices) today, is that the sensitivity of the photo cathode still lies very much in the visible area. An effective NIR flare must therefore work as close as possible to the visible range, otherwise you will not get illumination enough!

RIP
December 31st, 2003, 09:47 PM
On the subject, I make many types of 40mm and 37mm for personal use, and also have a limited number of military pyrotechnics including some 40mm white star paras. Do you guys know the formula for the star composition in these stars? They seem to burn very bright and have a pretty good duration for a star. The ones I've made up all seem to burn really fast compared to the military formulation. Also, what do you recommend using as a prime comp? I have a few 26.5mm flares that have a sort of grey prime comp, and I've tried using firefox's prime comp with negative results. I'm launching them out of a 40mm launcher using black powder as a lift charge. I want to get away from using cannon fuse as an ignition source if it's not needed. Thanks very much, RIP

Crazy Swede
January 2nd, 2004, 05:08 PM
The standard white parachute flares I've made were always based on coarse magnesium, sodium nitrate and linseed oil. For longest duration and highest light output, atomized magnesium is most effective.

A typical formula can be:

55% Coarse Magnesium
43% Sodium Nitrate
2% Linseed Oil

But, the fuel/oxidizer ratio will vary depending on flare dimensions and desired output.

The composition is mixed and dried in shallow trays for one to two weeks, depending on temperature and influx of air.

For me, commercial sulphur-free black powder has worked very well as a prime. Ordinary bp usually burns too quick to give a reliable ignition. But, many slow burning mixtures, compatible with magnesium of course, will work given that they are granulated in advance and pressed into the mixture. The easiest way to achieve this is to add the prime in the bottom of your pressing tool together with the first increment of illuminating composition.

vulture
January 2nd, 2004, 05:25 PM
By coincedence, I found out that a mixture of 200g meal powder, 10g fine Ti, 10g fine Mg en 10g Fe will create a very bright flare with a long burn duration.

This can probably be optimized using more Ti and Mg and leaving out the Fe.

Crazy Swede
January 3rd, 2004, 02:03 PM
Vulture, I'm sure that your bp/Mg/Ti/Fe flare is easily ignited, burns slow and might function well as a handflare, but it will not be anywhere near a real illuminating composition when it comes to light output. Your mixture will produce too much solid particles in the flame and the potassium will emit much of its energy outside the visible part of the spectrum.

The type of formula I mention in my post above will emit over 300 000 candela when pressed at 2000 kg/cm2 as a flare body with 40 mm diameter.

keith
January 10th, 2004, 05:49 PM
I have a rocket launcher that shoots Estes model rockets very high with a parachute recovery system that allows it to hang for about 1 min. I'll use this rocket for the delivery system. It will be easy if I can get the flare composition correct.

BTW, 5 pounds of black powder would easily blow that magazine thing into scrap metal.

vulture
January 10th, 2004, 06:09 PM
Vulture, I'm sure that your bp/Mg/Ti/Fe flare is easily ignited, burns slow and might function well as a handflare, but it will not be anywhere near a real illuminating composition when it comes to light output. Your mixture will produce too much solid particles in the flame

What's wrong with solid particles in the flame? They'd only increase light output by blackbody radiation. Certainly red hot MgO en TiO2.

Ofcourse it doesn't come close to an out-of-the-book illumination composition, but notice I said it probably has to be improved. As you could have guessed, that would mean increasing the metal content and decreasing the sulfur/carbon content.

FYI, the tube I used had an ID of 50mm. No way it could have been hand holdable, unless you consider a cinder of ash as a hand.
The light output was quite impressive for such a mixture that was not optimized for illumination. I'm talking about a fountain that turned night into day within a radius of 100m on the ground. As you probably know, the circle of light increases with deployment altitude.

Furthermore, I'm getting the idea you're always having to prove yourself against me. That is not necessary.

Bert
January 10th, 2004, 06:26 PM
Keith-
Magazines aren't to keep an explosion IN. They're to keep children, thieves and sources of ignition OUT. Obviously, 3" of hardwood and 1/4" of steel won't keep a ton of HE from escaping confinement if it's initiated. But with good locks it keeps it from growing legs and walking away, and stops rifle bullets, etc.

Vulture-
He's in the biz. After a few times saying: "This is how it's done, this is optimum, I do this for a living and I know" and having no one believe you, it's easy to develop a bit of a 'tude. Anything burning Aluminum, Magnesium and/or Titanium is going to LOOK quite bright from the near neighborhood. But he's very correct in that maximum illumination for size/weight is less than an optimized military formulation.

vulture
January 10th, 2004, 08:19 PM
He's in the biz. After a few times saying: "This is how it's done, this is optimum, I do this for a living and I know" and having no one believe you, it's easy to develop a bit of a 'tude.


I know. The thing is, he might have access to all those chemicals and optimized formulas, but I don't. So, instead I TRY something else. Nobody ever got dumber because of experimenting.

And we all know what happens to the "you can't possibly get it better than firm Y" types in the end. History has proven them wrong every time again.

If we'd all stick to the attitude of "It's in a book and already discovered, why bother?" then the progress of science would come to a grinding halt.

Crazy Swede
January 11th, 2004, 03:26 PM
Bert,
Thanks for supporting me! :)

Vulture,
I agree I tend to be somewhat irritated on your posts and I apologise for that!

The reason is that I�ve got a good impression of you from other threads, where you seem to be knowledgeable, experienced and intelligent. But, when it comes to pyrotechnics you sometimes seem to lack fundamentals that I would expect anyone of your calibre already to have utilised. It is wrong of me to judge you like this and once again, I apologise! :o

To answer your question regarding black/grey body emission in illuminating flares, it is correct that glowing particles of metal oxides strongly emit continuous radiation at high temperatures. But, optimum performance is only achieved if the fuel can be vaporised in the reaction zone to form a gas-colloidal oxide. Titanium and iron will only react in the solid state and can therefore never reach as high light output as magnesium or aluminium. Also, the latter is only effective if the oxidation takes place over or near its boiling point, which is the necessary condition for vapour phase oxidation.

Finally, from all possible oxidisers, sodium nitrate is the best choice for high energy white flares since sodium exhibits luminescent properties that add significantly to the useful, i.e. visible, radiation.

So, compared to sodium nitrate/magnesium systems, everything else will be inferior when it comes to candle seconds per gram of composition.

This said, I don�t mean that your composition is useless! It�s just a bit too far from what I judge as being an effective illuminating composition.

vulture
January 11th, 2004, 04:46 PM
So, compared to sodium nitrate/magnesium systems, everything else will be inferior when it comes to candle seconds per gram of composition.


Hmm, I always thought Ba/Srnitrate + Mg flares had optimum light output, because of the high temperature light emitting properties of group II oxides...The question is ofcourse, will BaO and SrO vaporize at the flame temperature?

BaO boils at 2000C, SrO can't find it right now. Apparently, a Mg flame reaches just over 2000C so that probably isn't enough. Therefore, one could try adding Ti to this mixture, to increase the flame temperature and vaporize everything except the TiO2. Ofcourse, the percentage of Ti should be kept as low as possible.

What do you think?

Crazy Swede
January 12th, 2004, 03:17 AM
Vulture, if the titanium is very fine (less than 10�m), you will get scary fast burning speeds, probably not suitable for flares. If coarser, I guess you risk ending up with a flare with a great white plume of sparks.

The reasons why Ba/Sr mixtures will not be optimal is that the boiling point of SrO is around 3000 degrees Celsius and that the BaO has its peak of emission around 750 nm and higher, which is at the end of the visible spectrum.

vulture
January 12th, 2004, 04:40 PM
Vulture, if the titanium is very fine (less than 10�m), you will get scary fast burning speeds

Very true! I once had a few grams of shitty BP with Ti explode on me instead of burn. :eek:

BaO has its peak of emission around 750 nm

Correct me if I'm wrong, but that is getting near infrared, isn't it? So it might have it's use in a poor mans IR flare?

Crazy Swede
January 13th, 2004, 03:01 AM
It is true that some Ba species has very interesting peaks of emission in the near IR area. But, since they also emit some of their energy in the visible part of the spectrum, the burning temperature must be very low to minimise the emission of visible light.

Crazy Swede
January 13th, 2004, 07:03 AM
Vulture and Bert,
I thought that since Vulture seem to think along different lines than I'm used to and Bert has lots of experience from fireworks manufacture, I should ask you a question (of course everyone else is also welcome to contribute):

Do you have any practical experience or theoretical ideas regarding how to minimise the deposits of slag (mostly SrO+MgO) that often is ejected as white glowing sparks from Sr(NO3)2/Mg/Cl donor flares?

Since the slag is so high melting and viscous, I have been thinking along the lines of finding an additive that would decrease the viscosity of the slag so it could be ejected as smaller drops instead of big blobs of material. But what would that be?

Or, is there something else that could be added to make the slag fluffier so it could be expelled as something resembling ordinary particles of ash?

Blackhawk
January 13th, 2004, 07:59 AM
If the slag is a liquid or a semi-liquid then perhaps modifying the compostition to produce a lot of gas may fill the slag with 'bubbles' to make it fluffier. Well anyway that probably wouldn't work for some reason, but hey I'm here to learn thought that might help.

Bert
January 13th, 2004, 11:01 AM
What is the Chlorine donor, and does your formulation contain any Sulfur? If it's not proprietary, could you give the whole formulation?

vulture
January 13th, 2004, 03:03 PM
I would try adding some percent of SrCO3 to the Sr(NO3)2 before preparation, since it'll decompose to SrO giving off CO2 which might just do it.

Excess chlorine donor could be interesting too, since MgCl2 and SrCl2 have lower melting points than the oxides.

Crazy Swede
January 13th, 2004, 04:22 PM
Blackhawk,
Additional fuels could be beneficial to produce more gas. I'm a little afraid though that the temperature would drop which could ruin the light output.

Bert,
The problem is visible in three different products but it is only in one of them that the sparking is disturbing. The chlorine donor is always pergut (chlorinated alloprene rubber) and the binder is always linseed oil. A typical formula could be:

44% Sr(NO3)2
38% Mg
14% Pergut
4% Linseed oil

Vulture,
I will try to add strontium carbonate and oxalate respectively to the system. Thanks!

Higher amounts of pergut have resulted in a flickering burning character and low light output. This is probably because pergut is a quite lousy fuel and also because the temperature of reaction is lowered too much!

chemoleo
January 13th, 2004, 04:27 PM
In thermite mixtures, calcium flouride CaF2 is added to the oxide/metal powder to *increase* the flux of the reacting mixture. Here you are working at temperatures >2000 K (at least in the common thermites), and in case of an aluminium based thermite, the resulting Al2O3 would normally prevent easy isolation of the reduced metal. In the presence of CaF2, however, Al2O3 and metal separates nicely, in part by an increased fluidity of the Al2O3/metal.
So maybe this is something to try, add CaF2 to your pyrotechnic mixture and see whether it decreases the viscosity and potentially the deposit of the slag.

Bert
January 13th, 2004, 06:48 PM
Crazy Swede-

The first think I'd do is try Saran resin instead of the Pergut (Chlorinated Isoprene, right?). Chlorinated rubber makes for large cinders in my experience. Even using 50:50 Pergut and Saran would help- I don't know if the total mix is up for discussion, but I'd be tempted to substitute about 10% KClO4 for 10% of the Sr(NO3)2 as well. The basic mix is quite similar to a WWII Very pistol star formulation I'm familiar with, with the substitution of Pergut for double chlorinated PVC? Somthing from the BIOS reports that's re-printed in Lancaster's Pyrotechnics.

The Saran resin burns much better than the chlorinated rubber, lights easier and has a larger percentage of Chlorine to boot.

Crazy Swede
January 14th, 2004, 03:32 AM
chemoleo,
Thanks for the tip of CaF2, I will evaluate that!

Bert,
Your'e right about that Pergut is chlorinated isoprene and nothing else!

I'll order some Saran resin to experiment with.

We have tried double chlorinated PVC some times but not noticed any advantages from that compound. Have you?

Addition of KClO4 to this system tend to make the burning time too short. Also, the luminous output decreases if I drop the Sr(NO3)2 level too much. Maybe the situation will be different with Saran instead of Pergut?

Thanks for all tips! It will take some time to evaluate this, but I will let you know about the results.

Bert
January 14th, 2004, 12:17 PM
Crazy Swede-
You can drop the proportion of Chlorine donor slightly when using Saran. I've never been able to purchase the double chlorinated PVC in the US. Another trick to break up ash is to incorporate a small quantity of moderately coarse Sulphur crystals (3 - 5%) in place of some of the other fuels- I know that it's not desirable for storage of Mg mixes to contain Sulfur, but your Mg is pretty coarse & is coated with oil, right? I've heard Strontium oxalate recommended for Magnesium mixes, but haven't yet tried it.

vulture
January 14th, 2004, 04:17 PM
Strontiumcitrate might be an option. I've made it myself and found that it'll decompose at low temperatures and produces a nice red color without any chlorine donor.
It produces alot of gas too.

However, it's a MAJOR pain in the ass to make, because it forms a complex rather than an ionic compound. Therefore it behaves like a very viscous and extremely sticky gel.

chemoleo
January 14th, 2004, 05:57 PM
I made some strontium nitrate (not citrate) myself recently, from SrCO3. I found it wouldn't dry at room temperature, and after a few months under those conditions crystals did form, but yet a viscous liquid remained. Conversely, the corresponding barium nitrate wouldnt be as highly soluble, in fact some of it would precipitate and be easily dried! Both produced the expected colour under a Bunsen flame.
Anyway, I was thinking this problem with the nondrying Sr-citrate could be solved by precipitating with 100% EtOH (or other solvents, ether precipitates ionic compounds), in a huge excess. I am sure one might solve the problem this way (Edit: If citrate still produces problems, the corresponding acetate might be a better choice (for me, Calcium acetate worked very nicely), as it wont complex the Sr ion as citrate does).
On another note - as Vulture suggested to add SrCO3 which would decompose - I found that SrCO3 would not produce (just as CaCO3) a red colour under a Bunsen flame. In fact, the flame colour did not change, while the nitrates, acetates, etc caused intense red coloration. Hence I wouldn't think that SrCO3 would be more than just additional ballast.

Bert
January 14th, 2004, 10:07 PM
Chemoleo, SrCO3 is a very widely used red colorant in pyrotechnics. Try adding a bit of Chlorine to the flame- Dip a platinum wire in HCl, then in a bit of SrCO3. Hold it in a burner flame- You'll see red.

chemoleo
January 14th, 2004, 10:53 PM
That's very strange, I tested this not even a week ago. I brought SrCO3 (commercial) to the glow on a metal spatula (no HCl dipping, that's cheating! ;) ), and it did not colour the flame red (try it!). Because I was confused by this result, I thought, let's check CaCO3. No red flame again. When I dissolved the SrCO3 in HNO3, the resulting solution produced the expected strongly red colour, and so did the calcium nitrate!
So... presumably red glowing heat won't be enough to decompose the SrCO3 to SrO and CO2, hence no spectral absorption to give the red colour. At the thermal conditions of a pyrtotechnic mixture, temperatures are surely a lot higher, reaching the decomposition temrperature of SrCO3, thus red light? Come to think of it, this makes sense. So SrCO3 wouldnt be ballast, in fact. Thanks for pointing this out.

Bert
January 18th, 2004, 01:25 PM
SrCO3 will work well in perchlorate or chlorate oxidized color mixes with either organic or metalic fuels. If you were not getting any coloring from heating SrCO3 or CaCO3 in a flame, it's most likely that you're just not getting them hot enough. The use of the thin platinum wire for a carrier in the hottest part of a bunsen flame will certainly produce colors-

ossassin
January 19th, 2004, 02:01 PM
Hello, everyone! My computer is fixed, so you'll see my replies starting to pop up again. :) I've had some delays with the purchase of the 37mm, but I'm not giving up. I know that I said I'd test those mixtures, and I apologize.

Sobe_Death
January 20th, 2004, 01:34 PM
for the parachute, you could check army/navy surplus stores. they usually have second-hand illumination flare 'chutes that are spring loaded to open when not under tension. they are anywhere from 12" to 20" in diameter and cost maybe $5. i used to use these as recovery chutes on my rockets.

rebelpride33
January 5th, 2007, 05:10 PM
It appears to me that maybe the most difficult part of your flare idea would be a reliable parachute deployment. In this case, I had a good idea. Being a model rocket enthusiast like I am, perhaps you could try finding a thick walled cardboard tube that fits the size you were looking for most, and use an ejection charge just like a rocket engine and wrap your parachute in the flame resistant recovery wadding to prevent it from lighting. If you ran the shroud lines from the parachute to the flare somehow and just balled up the parachute in a few sheets of this wadding at the end of the tube containing the ejection charge (I believe in regular Model Rocket engines it is 3fg grained powder) then this might work? Then again, it depends on the design and parachute.