Illuminating parachute flare

[Tiger]

Last summer I did an army reservist course and along the most interesting pyro we got to use was the illuminating parachute flare. Some might prefer the smoke grenades or the artillery simulator but no, I was fascinated by the hand held launched, rocket propelled flare. Maybe it has something to do with amateur rocketry I was doing in the early 2000's. I found the contractor making those...not surprisingly it's just a marine search and rescue device packaged in dark green instead of the civilian bright orange...but my goal it build a "similar" device on my own.

 

Leaving the rocket part aside, cause I'm not ready to launch one with my hands holding the tube... I was looking at the flare part. Years ago I made some hand held flare using magnesium filing and potassium nitrate, I used a 50/50 mix measured by volume, poured it into a large straw, added a handle and I had good result even with very coarse magnesium filing and inaccurate measurement. BTW I did that without checking any recipe online, I figured out that if KNO3 was providing oxygen in black powder, and that Mg was burning that bright, I could mix both, 10 years later, I think it was clever, but now info is much easier to find online...and somehow there's more reliable site like this one.

 

So, this winter I was looking to dig those memories and my plan was to launch a tube containing a Mg fuelled flare attached to 30 cm of tiny bath chain, then 4 tiny strands on nylon a 50 cm long and a square foot of metalized Mylar. The propelling charge and launcher shouldn't be a challenge, I already did that several time, although a long time ago. My questions start at the delay fuse required in the projectile tube carrying the flare. from the many firework I used to disassemble to see how they worked, I remember that a lot of them use visco fuse sticking out of a cardboard casing, I'm surprised they ignite reliably with the very brief contact they make with the burning propelling charge, is there a trick or it's really just that sensitive ?

 

Next how hard must the bottom of the projectile must be, several layer of glued cardboard is what I always saw, but should I include some tightly packed Bentonite or other things? (I guess it also depend on the diameter/surface area of the bottom of tube) anyway with about 1cm per second of delay, I guess I'll have room to fill with inert stuff.

 

Then comes the flare, I read that topic -> http://www.amateurpyro.com/forums/topic/3045-magnesium-illumination-flares/and noticed 2 recipes:

25.5% Magnesium
34.5% Potassium Nitrate
34.5% Barium Nitrate
5.5% Binder*

 

and

Sodium nitrate - 48 %
Magnalium (~80 mesh) - 45%
Dextrin - 7 %

 

Now comes most of the questions, what is the advantage of adding barium nitrate instead of using only alkali metal nitrate? ( It must be substantial considering it's toxic )

I also read on this forum about the difference between K and Na nitrate, beside price, people seems to have problems with the hygroscopy of NaNO3 but how bad is it, I only have experience with KNO3 and it was already a concern, but not that much. One thing I must note is that living in a city, I won't be able to test flares until next summer when I'll visit my parents living far in a remote region. so anything I make will spend months in storage. I read that NaNO3 gives of more light than KNO3 when burning, does the difference really mater when it will be flooded in burning Mg ? Does it worth the trouble ( hygroscopy, price isn't a concern, and molecular weight is low priority).

I was thinking about making the flare as "humidity proof" as possible no matter which oxidizer I end up using, I considered petroleum jelly or wax as a binder, would it help ? And what about the comment "Magnesium is likely to react with nitrates" does using hydrocarbon based binder would help ? I also read on this forum that this reactivity with nitrate was more of a concern when using Aluminum and that with Mg I would not need to add boric acid and in fact I really should not add boric acid when using Mg, is that true ? I always thought Mg as more reactive than Al ?

I was planing on making a "thick" cylinder of aluminum foil around the flare so it would burn only from the flat under side and progress linearly with a constant surface area ratter than burning all around making the flare progressively smaller in surface area...do you think it's a good idea ?

That would certainly help to shield it from moisture but how could I shield the underside, I'm pretty sure I would have to coat the under side with a layer of black powder so that the charge expulsing the flare and the parachute light the flare, I think I read somewhere that Mg+nitrate required a bit of help to light. (maybe it was about aluminum)

I'm pretty sure BP isn't "moisture proof" so I also had the idea of coating the flare with nitrocellulose lacquer, ( an other idea I had while reading on this forum ) would that help ? I doubt that the lacquer would be sensitive enough, so I would have to coat the flare with NC lacquer then bind a layer of BP over the lacquer ?

 

I'm sorry if I have so many questions, the idea is that I try to reduce as much as possible the number of combinations I'll build cause everything I make here, will be tested 1000Km away next summer, and I won't be able to rebuild anything improved over there, I'll have to comeback, rethink and wait next summer to retry :-)

Edited December 27, 2014 by Tiger

[Arthur]

If you can find a company that services ships' life rafts then you may have a supplier of the date expired SOLAS parachute flares contained inside them. (IIRC SOLAS flares have a two year life to expiry date so ferries and cruise liners swap out hundreds every two years). The lift is a spin stabilised rocket with a steel plate with three angled nozzles. The falling star is only held in by a film lid so it's easy to actually check what is inside and how it's assembled.

 

MOST of the moisture issues are solved by the plastic or metal body and the sealed film over the parachute end, assisted by the packing of everything inside a thick polythene bag.

[mabuse00]

 

what is the advantage of adding barium nitrate instead of using only alkali metal nitrate?

 

All of these salts decomposition products will emit light, but not all of it will be inside the visible spectra of the human eye.

Potassium salts are not optimal in this respect, barium will be better, but sodium is the best.

 

 

I read that NaNO3 gives of more light than KNO3 when burning, does the difference really mater when it will be flooded in burning Mg ? Does it worth the trouble ( hygroscopy, price isn't a concern, and molecular weight is low priority).

Yes, it will matter. And hygroscopy - it depends on where you live. Under tropic conditions or in permanent rain, you'll have problems (or rather, you'll have to take more effort in protecting your device), on a dry winter day most likely wont have any trouble at all.

 

If you find hygroscopy to be a big problem for you, barium nitrate is the best substitute, practically not hygroscopic and more light than potassium nitrate.

 

 

I was thinking about making the flare as "humidity proof" as possible no matter which oxidizer I end up using

No need for that with barium nitrate.

 

 

I considered petroleum jelly or wax as a binder, would it help ? And what about the comment "Magnesium is likely to react with nitrates" does using hydrocarbon based binder would help ?

I would help a little. Ultimately it's all about keeping the stuff dry. Dry nitrate won't do Mg any harm.

 

 

in fact I really should not add boric acid when using Mg, is that true ?

Yes, all correct as you wrote it.

 

 

I was planing on making a "thick" cylinder of aluminum foil around the flare so it would burn only from the flat under side and progress linearly with a constant surface area ratter than burning all around making the flare progressively smaller in surface area...do you think it's a good idea ?

Yes again. Some flares I saw are indeed pressed into very thin walled aluminium tubes, the tube burns away with the composition. I suggest to use thin walled paper tube for that and press the composition inside (ideally using a sleeve to protect the tube from rupture & use high pressure).

 

 

That would certainly help to shield it from moisture

A little maybe. There are always gaps. The best solution would be to put the whole device into an hermetically sealed container. See your handheld rockets cartridge, or a flare gun cartridge.

 

 

My questions start at the delay fuse required in the projectile tube carrying the flare. from the many firework I used to disassemble to see how they worked, I remember that a lot of them use visco fuse sticking out of a cardboard casing, I'm surprised they ignite reliably with the very brief contact they make with the burning propelling charge, is there a trick or it's really just that sensitive ?

Some commercial cakes indeed seem to work this way, and frankly I'm not sure about that. I tried this method several times and it produced an unacceptable amount of duds!

 

 

 

'll build cause everything I make here, will be tested 1000Km away next summer, and I won't be able to rebuild anything improved over there, I'll have to comeback, rethink and wait next summer to retry :-)

I believe you cannot work this way. You'll have to test the individual components individually imho, lift charge, passing fire to the shell, priming, ect. Especially if you're new to pyro. Do small steps, test one part until it works perfectly, then go on with the next. Don't try to put together many untested parts at once, it won't work.

[Tiger]

If you can find a company that services ships' life rafts then you may have a supplier of the date expired SOLAS parachute flares contained inside them.

 

Yes, it could be a way, but it's too easy and the website of the supplier I found here wrote in the FAQ:

 

 

QUESTION : 2 What is the life expectancy of a marine signal? ANSWER : Legally, a marine distress signal must be replaced four years after the date of manufacture. Our products are indicating a expiry date that is irrelevant in Canada. It concerns only consumers from the USA, the rules there being different than in Canada.

 

So I'm not sure they have that many expired ones, but I could still ask the question.

 

 

Reading mabuse00's answer I think I'll go with NaNO3, in the winter here I can easily keep indoor humidity around 50% and I saw it dip as low a 30% a few times, but I'll still use the idea for sealing as much as possible the flair. Won't use boric acid.

I'm still considering the NC lacquer, I'm testing wood stick coated with lacquer to see how good is it a blocking humidity and how sensitive it is.

 

 

 

'll build cause everything I make here, will be tested 1000Km away next summer, and I won't be able to rebuild anything improved over there, I'll have to comeback, rethink and wait next summer to retry :-)

I believe you cannot work this way. You'll have to test the individual components individually imho, lift charge, passing fire to the shell, priming, ect. Especially if you're new to pyro. Do small steps, test one part until it works perfectly, then go on with the next. Don't try to put together many untested parts at once, it won't work.

 

 

 

Well, I don't really see myself testing pyro in Montreal :-) however I do have some experience with pyro from when I was living with my parents 10 years ago but I agree it wasn't much.

For this project, I was planing on using my 26.5mm flare launcher, I have several cartridge that already have a lifting charge, and a working fuse, I just have to swap the original red flair from the cartridge. ( and keeping the total weight similar )

When I'll have a working flare, I might think about making my own shell with fuse. But for the first test, I'll be using proven parts.

 

 

 

Thanks for your help.

[dagabu]

mabuse00 really did a good job answering all your questions but I would like to add a couple observations from my time pursuing the same thing. Use a casing that does not impart another color on your flare such as plastics and PVC. Use paper, a hand rolled tubes with a thinner wall worked well for me.

 

Yes, use a binder but I am not a fan of using Dextrin because you need water to activate it and then the Mg starts to react as well. I had used shellac last time but found that with all the Phenolic resin about, it worked exceedingly well for flares and you dont have to have a fancy press to make them, just watch out for shrinkage so pressing them into a PVC tube, letting them dry and sliding them out THEN wrapping them in paper (4-5 turns of #30 kraft) along with your nicrome wire gives a nice flare with the proper orientation.

 

To finish them, consider dipping the flare in molten wax to seal them or even PVA glue. The flare is mostly waterproof with the phenolic resin but for shelf stability, a nice seal sure cant hurt.

 

For fusing, I like good old perchlorate black match embedded in the end of the flare, 2 doubled strands seemed to be enough to reliably ignite them.

 

For timing, I just relied on the rocket delay to light a pinch of BP that expels the flare (and lights it) and parachute when the delay burns through.

[Arthur]

As a guess the star is pressed in several increments and the bottom one is a BP like prime. I was more thinking that dropping the star out of a red flare will give you dimensions for the star and the parachute and the suspension wires, AND the method of folding them. -Why make guesses when you can see a professional one and measure it?

 

It's quite loud if you take the star out and fill the rocket head with flash. Maybe you could take the red star out and try white, blue, green (etc) stars. Remember however that you never find the parachutes, but someone else may.

 

If you are going up country don't fire anything that will bring out the rescue services.

[Tiger]

As a guess the star is pressed in several increments and the bottom one is a BP like prime. I was more thinking that dropping the star out of a red flare will give you dimensions for the star and the parachute and the suspension wires, AND the method of folding them. -Why make guesses when you can see a professional one and measure it?

 

It's quite loud if you take the star out and fill the rocket head with flash. Maybe you could take the red star out and try white, blue, green (etc) stars. Remember however that you never find the parachutes, but someone else may.

 

If you are going up country don't fire anything that will bring out the rescue services.

 

 

It indeed gives me the dimension, but the flares I have are just red comets, no parachute or suspension wires and no rocket. I know I could buy commercial rocket flares, they would be larger, and launched higher...but I see this as a challenge, I'll try to make a working flare+parachute first launching them with existing flare cartridge, then I'll try to make my own shell with delay fuse once I get a flare+parachute that works, and may be then I'll try to make a rocket for it, but one thing for sure, I'll be using commercial amateur rocket engine, I did try to made my own rocket engine a long time ago, it kinda worked, but they where way to dangerous....

 

Yes, it's a thing I'll be careful with, not to alert rescue service.

Edited December 28, 2014 by Tiger

[dagabu]

I would think making the rocket motor would be the funnest part of the whole ordeal. A flare of a large enough size would take a pretty expensive motor to raise it to a good height, I would think a core burner would be a better lifter, they have been for me.

[Tiger]

I would think making the rocket motor would be the funnest part of the whole ordeal. A flare of a large enough size would take a pretty expensive motor to raise it to a good height, I would think a core burner would be a better lifter, they have been for me.

 

It was fun when I tried, but at that time my goal was to make a rocket launched from a tube held on my shoulder, and I dropped the idea of making my own after a few weeks of testing. Made a working device in 2006, used it to launch a total of about 20 rockets. They were fired from a tube open at both ends, using an electric system, a bank of large capacitors charged at 250V dumped into a tiny wire embedded in a small block of BP fixed to the nozzle of a commercial amateur rocket engine, that charge pushed the rocket so it would exit the tube at great speed helping the rocket accelerate inside the tube, otherwise they exit the tube too slow with a downward trajectory. It was fun, but making those one time use rocket was 10$ and about 2 hours per unit. I used some of them to launch small shells scavenged from consumer fireworks.

 

Now my goal is still to have something portable/hand held, I'm starting with a all steel, heavy duty flair gun, I feel that the rocket part might be an unnecessary risk.

I don't need to make it as good as what we had in the Forces, but I would like to make a working device, no matter if it's rocket propelled or not, as long as it illuminate an area for many seconds, I'll be happy with the result.

 

After a few query on Google, found some things:

Here's the exact device we used in the Forces ->

http://storage.edmontonsun.com/v1/dynamic_resize/sws_path/suns-prod-images/1297462597029_ORIGINAL.jpg?quality=100&size=800x

 

They are listed on the supplier's civilian web-site in the marine section, also available in red and green (but with bright orange casings)

http://www.cilexplosives.com/images/solas/52662.jpg

I could just buy these, but again, too easy.

Edited December 28, 2014 by Tiger

[Arthur]

Remember that the standard SOLAS flare is hand held so there can be little recoil.

 

Remember that end of life solas flares cost the supplier for disposal, so there may be some available to you for the asking.

[User64]

Heck I wouldn't mind having some expired ones to tinker with.

 

The parachute flares were one of my favorites as a child visiting Grayling and watching the National Guard shoot them off. Had an empty casing for the longest time but lost it years ago. These would be a neat alternative.

[Tiger]

So, little update.

I started with the second recipe quoted in my first post which is about 50/50 sodium nitrate/magnesium plus some binder. Works great, it might not be perfectly balanced but any excess of Mg will burn in the air and what matters here is light output anyway. I used 180 mesh Mg, it's a bit finer than what I would have liked, but it's what I had.

Loose unconfined powder burns quite fast, it might not be true flash powder but it all burns in a single POUFFF like those old photographic flash :-)

I'm still trying to chose which binder to use, I tried to compress it without binder in 1/4 inch tubes, it holds itself well. I also made similar tube but using nitrocellulose or polystyrene dissolved in acetone, I'm not sure I really need to used binder, the final product will be a cylindrical flare a little bit smaller then an inch and between 1 and 1.75 inch long with an outer layer made of cardboard/NC lacquer, so I'm wondering if pressure alone will "bind" the flare well enough in it's tube so it won't crumbles.

 

 

Also, I check with the manufacturer of the rocket para-flare, they initially told me they do not sell those items to civilians, which got my wondering cause they can be found ( the red ones however ) in marine equipment stores as distress signals...available to anyone over 18. He told me that those devices are quite powerful and even if no law prevent them from selling to anyone, they don't want those to fall in kids hand's. So I then said that I understand and agreed cause I had the chance to try them in the army and they are indeed impressive. He then said..ha..Ok, well, I guess we could sell you a few in this case... wow... :-p

 

They do not however have expired stock, they produce them only when they receive an order and sell the batch to client/distributor and then they go to stores, where if they go expired...are taken care by the distributor, so I got the name/phone number of the distributor, and I'll check with them if they have expired stock....and he also told me, if you want to buy new ones, on our next order/batch we can make a few more to sell to you...50$ a piece if I take 3...I'll think about it, and keep experimenting with my own. =^.^=

Edited January 22, 2015 by Tiger

[Arthur]

$50 is the scary part

 

For illuminating compounds an excess of fuel is usual! It's the fuel that makes light not the oxidiser. Once the flare is lit the flame pushes metal fuel into the air surrounding the flame where it burns with atmospheric air.

 

Shidlovskii had some good stuff on illuminating flares.