Safe milsim prop advice

[Karma]

Hello everyone,

 

My name is Blane, and I am up in Washington State. I belong to an organization that hosts military simulation events in conjunction with airsoft. I have always been interested in the science and technique behind pyrotechnics, but have never had a good reason to look into it much. Now my club needs some good props, and it seems like I am their man.

I have much to read and learn, but I thought that I might ask my first question just to see what comes up.

What we would like to do is house a small charge in a vented cylinder to contain the explosion. I am assuming that we would not need much more of a bang than what you would commonly get from a large firecracker. What would you guys recommend for such a charge, is it possible for us to put these together ourselves to recharge our canisters, and what is the most cost effective way to do this?

When it comes to this type of discussion, I know that people are weary of disclosing much. I tend to think that I am a pretty stable person that is committed to safety first. If anyone has any questions about our intent, by all means let me know. I look forward to hearing from you guys.

 

Thanks again,

 

Blane

[mike_au]

I am a newbie here too, so one of the more experienced people might come correct me, take all this with grain of salt.

 

What you are after is possible, it is called a ground salute (this covers everything that doesn't fly and makes a bang) and while they are mentioned around here occasionally they aren't popular (I believe they are illegal in a lot of places), that combined with the fact that a lot of the people asking about them are kids who want to "blow shit up" means that they don't get talked about much.

 

Since you have a legit reason people might be a bit more understanding but maybe not.

 

The other issue is that the mixture normally used is rather dangerous, I think most people would be hesitant to encourage you to make it until you have experience with something a little safer (e.g. black powder).

 

Having said that, black powder can make a reasonable bang if you have decent confinement but it wouldn't be as small or as loud as some of the other compositions.

 

What sort of simulations? I'm assuming its something like modern warfare rather that reenacting ye olde' battles?

[BPinthemorning]

I do airsoft simulations, and know where you're coming from, but here we don't like salutes no matter how experienced you are. You said a vented cylinder. You trying to make simulation of an artillery, or a hand held gun mounted M203? If it's an M203 I would tell you to forget about it. No noob, much less experienced person, should ever hold a mortar tube like that... Give us more info, and we will be more prone to help you. The more people supporting pyrotechnics, the better.

[Karma]

I understand that people may be hesitant about offering advice. I am assuming that the rather dangerous material that you are talking about is flash powder. It would be easy enough to gather the chemicals for flash powder, and some tubes to make a bang, but I prefer to be safe and try to find out how to do this the right way. I am totally open to experimenting with black powder and seeing what results we would get from that. What is the best way to house black powder for a report? The charge would be placed in a vented cylinder, in a pot. This device will NOT be handheld.

 

We simulate various scenarios, and would like to simulate the report of artillery, and grenades. Of course it's not going to be as loud as artillery, but on the relatively quiet battle field, we are looking for a little controlled bang to spice things up.

[hst45]

This *is* sort of touchy subject, as most newbies who ask for info about making something that goes bang but who don't have a background in either chemistry or display pyro usually have an agenda that is really more negative than most of us feel comfortable with. That being said, you seem to be asking a reasonable question in an intelligent way, so while I can't give you an answer that covers all the possiblities, I think that I can help you out with some basics.

 

If I were to attempt to make a bang to simulate an artillery burst, I would only consider black powder. Don't try to use higher-energy things like flash powder. Black powder can be obtained, legally, from sporting goods stores or gun shops. Black powder should NEVER be ignited in a metal tube. If you put BP into a stout CARDBOARD tube, with a large amount of space above the charge, you should get the "boom/smoke" effect that most people find to be fun. DO NOT, EVER put your head, hand, finger, or genitalia above a tube filled with a BP charge. Be cautious of the spark debris that will emerge from the tube. Have fun, and stay safe.

[Karma]

hst45, to create the bp charge that you describe, do you cap the ends of the tube, or just cap one end? Or do you just cap one end and add wadding to the other end to create compression?

 

If I used a tube caped on one end with a charge of bp, but left completely open on the other end, it seems like the charge would just cook off, and not create a report. Am I wrong?

[Mumbles]

You would probably need to close each end securely, and then reinforce it with string or fiberglass tape or something to that effect. You might find some info about making canister shells here. The design is the same, just instead of using stars and effects, fill the whole thing with black powder. It should make a nice grenade/artillery fire type of simulation. Some may even add dirt on top of it, but then you have to start worrying about rocks and debris causing injury. Might be better off just sticking with the charge alone.

[jacob]

I suggest a strong paper tube plugged at one end with a BP charge, maybe some wading (news paper, foam ball, ect) if you don't find the bang without it satisfactory, and be carefull if you're going to reload it, you don't want glowing embers to ignite the next charge.

[Karma]

This is a lot of help everyone. What is the best way to plug the ends of the paper tubes? I like the idea of using wadding to create the report. Any recommendations on fuse?

 

If reloaded, we would do so only after visual inspection for embers, or any other variable that would create an unsafe situation.

[tentacles]

Why not get a small report cannon? Ie a miniature "live" cannon. I suppose it wouldn't be practical if you need a rapid rate of fire, though.

 

Charlie, any thoughts?

[Karma]

We don't need a rapid rate of fire so that may work.

[Miech]

For a realistic effect you could think of using the same manner used in Hollywood. This is basically a fully buried tube, with the lower end having a strong end plug. In the tube an electrical igniter is placed at the bottom, and a sufficient layer of black powder is poured on top of it. On top of the black powder some cotton wool is placed, and above that an amount of dirt, debris and cork pieces. The cork is great for simulating flying pieces of ground, while some dust will give the typical looks of a grenade impact.

These devices usually aren't too loud, but when using more dirt on top of the BP you'll get a better boom due to better confinement. For a 3" mortar usually 200 grams of dirt and 50 grams of BP give good results this way.

 

Note: never put things like rocks, sand or otherwise dangerous stuff in devices like this, it could cause serious injury. Do not fire it when someone is standing close the device.

[BPinthemorning]

Dam. Meich, you beat me too it. I had that idea last night when I couldn't fall asleep lol. This would probably be the best simulation, just make sure all the people involved are aware of it and its location.

[Richtee]

Why not get a small report cannon? Ie a miniature "live" cannon. I suppose it wouldn't be practical if you need a rapid rate of fire, though.

Hmm what about a mild whistle mix or maybe Benzolift? Less required and easier to confine a bit for a sound/concussion.

 

I'm using about 6-8 grams of Benzo to launch 3" shells, and gives quite a thump. I'd think a 2" tube and the foam ball plug might be satisfactory with perhaps 5 grams of Benzo.

[GalFisk]

I'd recommend benzolift before whistle for a pure report, it's much less shock/friction sensitive (couldn't set it off with a hammer against concrete) and the production following this guide is relatively safe and straightforward: http://www.creagan.net/fireworks/benzolift.html

[Karma]

Benzolift sounds like it may be a good option, but isn't Potassium Perchlorate pretty regulated now? Is it hard to get ahold of? How is the availability of the other chemicals?

 

It would be a nice effect to burry a mortar tube as mentioned, but the blast wouldn't be as contained as we would like.

 

One last question. What are the differences between black powder and smokeless powder in reguards to burn rate? Would it be acceptable to use smokeless powder to create the report?

[Swede]

You can obtain a very satisfactory (and safe) report, without all the flying debris, with a simple, well-wrapped (paper, cardboard, fiberglass tape) Black Powder device set into a pit, initiated with either fuse or an electrical system. By pit I simply mean a hole in the ground, maybe a foot or two deep, depending upon the size of the charge. Any fragments will be paper, and will be directed upwards safely.

 

I don't think you need to get fancy, nor do I think you need anything except BP. I'd not try to "contain" the blast in the sense of a tube, although that's certainly possible, but the charge itself must be contained, and that is where the grunt work comes in. Inadequate containment will diminish the report, but I think you might be surprised at the power of the boom you can make from modest quantities of BP.

 

BP is easy to buy or make, is safer than other compositions, and for want of a better description, is "politically correct." People may tend to freak a bit with more exotic comps, but "plain ol' black powder" generally calms people down a bit, if there is opposition to the project.

[Karma]

BP sounds promising. What are the differences between black powder, and smokeless powder used in modern bullet casings?

[Swede]

Smokeless powder comes in various ratios of nitrocellulose and nitroglycerin, and unless confined very well, it burns rather than explodes. If you were to place a tablespoon of smokeless powder on the ground, and compare it to a TBS of BP, the BP would disappear in an instantaneous WHOOMP of fire and smoke; the burn time would be negligible. The smokeless powder might take 5 seconds to burn, maybe more.

 

Smokeless is considered safer to store and ship. It is also a LOT more expensive, per boom, than BP. You can make a pound of BP for $3 easily; a pound of smokeless from a store is what? maybe $25, $30? If you want a nice smoke cloud along with the report, use BP.

 

I've personally never tried using smokeless in any sort of a salute, simply because there are better and cheaper materials... like BP. I really cannot see any advantage to using smokeless. Same deal - must be tightly wrapped to go BANG.

[Sylar]

Black powder is a mix of chemicals (known to all ofcourse) where smokeless powder is a chemical called nitrocellulose. Sometimes doped with a small percentage of nitroglycerine for extra power.

 

So basicly there no real comparison between a high explosive and Black Powder. Although not used as a high explosive in a bullet, but more like a deflagrating mixture, it really requires very good confinement to accelerate the burning. Black powder is much more forgiving on the case of confinement.

 

I recommend staying away from high explosives and sticking to black powder. Especially for this matter, where sound is most important.

The higher burn rate will generate a higher pitched sound and wont be very realistic.

 

EDIT: Swede beat me to it :-)

[OneEyeCharlie]

I would suggest using BP. When suitably confined, it produces one hell of a boom along with a nice smoke ring. You can almost imagine someone is calling in a ranging shot from a 155 howitzer.

 

I found that one of the best waddings to use is green grass. It doesn't ignite like newspaper, paper towels etc. Also, because of the inherent dampness, you get some really good compression and thus a louder boom.

 

I also preconfigure charges for my cannon. Find yourself a wooden dowel that has an OD that is equivalent to the ID of your barrel. Cut a strip of aluminum foil roughly 2" wide by 12" long. Wrap the foil around the dowel and squeeze it tightly by hand to form a cylinder. Slide a bit of the cylinder off the dowel and then compress against the dowel's end to close it off. Then slide the foil cylinder off the dowel, pour in your BP, and squeeze tighten the open end.

 

This helps negate a bit the hazards of loose powder. Simply slide your charge down the barrel, tamp lightly, add clumps of grass, ram a bit firmer. Then use a non-sparking spike to pierce the charge through your touch-hole. I use a piece of brass rod filed to a point.

 

Insert visco, light, run like hell giggling all the way.

 

 

As a sidenote... I've added a safety modification to my ramrod <insert juvenile chortle here> On the end, I glued and screwed a cross strut several inches long. At the end of the strut, I glue/screwed a shorter section of dowel to use as a handle. The handle runs parallel with the rammer.

 

When ramming wadding, your hand is several inches away from the muzzle of the barrel and behind the opening. If something catastrophic were to occur, it reduces some of the danger.

[Karma]

Black powder sounds like it's the winner. I suppose that I'll make a batch myself. I'm off to search now, but before I leave, what are some key materials that I need, and good, safe directions on how to make bp? You guys are great!

 

Edit: Reply to Charlie. I like your idea of pre fabed charges. How do you transport them, and what do you use for fuse? It sounds like you have quite a bit of fun with your cannon.

 

Sorry for all the newb questions guys, but please be assured that if I'm not replying to a post on this tread, than I am searching, and reading the rest of the forum for info. Thanks again.

[JCrewPyros]

Black Powder

 

75 KNO3 (Saltpeter)

15 Charcoal

10 Sulfur

 

If your making it yourself...

 

Most people use a ball mill... Pretty much a beefed up rock tumbler with lead grinding media inside...

 

After all is mixed together and powdered you can either corn it or granulate it...

[OneEyeCharlie]

Karma - I usually keep my charges in a mil surplus 7.62 ammo box. If I'm in a hurry, I grab whatever Rubbermaid container happens to be handy. The fuse is just Chinese visco from Pyrocreations.

 

Additional handy tool for prospective cannoneers...

 

I made a combination swab/worm for my cannon. On a length of dowel, staple a chunk of cotton rag to act as a swab. On the other end, I used a coarse thread lag screw with the head cut off. Then drilled a hole in the dowel and glued in the screw.

 

The pre-fabbed charges tend to leave remnants of Al foil compacted at the base of the barrel. Insert the lag screw end until it hits bottom and then give a half dozen clockwise turns. This "grabs" the compacted foil so that you can remove it. Then give the swab end a healthy spray of WD-40 and run it forth and back several times to kill off stray embers.

[BPinthemorning]

Don't use smokeless powder. Shells and grenades make smoke on detonation. Go with traditional gun powder. Use a somewhat slow charcoal like pine or oak. They should make some smoke, sparks, and if you put it in a tube with dirt above it, it would certainly be a spectacle.