Grenade/Delay igniter

[stanfield]

I don't know if I shouldn't post this is the "Tools, Techniques, and Plans" section but never mind, here it is :

In a military grenade (frag, explosive, incendiary,...), what is the delay igniter made of ? (schema, plan...), how the delay is made ? electronic ? two chemicals in contact like permangante and glycerine ?

I did a search before 'cause I though it was discussed before but apparently, I was wrong : I found nothing about this subject...

thanx !

[xi]

Hi!

There is a good description on <a href="http://www.howstuffworks.com/grenade2.htm" target="_blank">http://www.howstuffworks.com/grenade2.htm</a> It might give you some ideas...

xi

<small>[ December 10, 2002, 07:39 AM: Message edited by: xi ]</small>

[stanfield]

"chemical delay" doesn't help me :)

How can I make a delay grenade at home ? Again, I really like the permanganate/glycerine method...

[zaibatsu]

This is how I believe it works:

The striker hits a percussion cap and the impact-sensitive comp in the cap ignites. This ignites a starting mix which ignites a delay composition that burns for the required time (3-5 seconds?) and then sets off the det. The delay composition has to produce little gas.

However, I'm sure people can refine (or downright change!) that explanation. Also, there's some info on grenades on the FTP I think :)

[VX]

If I were doing it, I would use a <a href="http://www.eleinmec.com/article.asp?3" target="_blank">555 timer in an astable circuit</a> . An exact time delay can be calculated this way and the circuit is very reliable. You would simply replace the 'device' in this circuit with an electronic igniter of some sort. It would make sense to use a small 12V camera battery to power the circuit as they can provide more current than a 'normal' battery. However it may be necessary to connect the output of the chip via a relay to protect the chip from failing(or literally exploding <img border="0" title="" alt="[Eek!]" src="eek.gif" /> ). Also if the output goes high, then low, this would not be much use as a delay. In this situation you would simply connect the 'device' to the +ve instead of -ve which would reverse the timing.

Another advantage of doing it this way is cost, the whole thing (excluding the battery) costs less than a pound. Also this same circuit can be used re-used just like a normal ignition box. Assuming that it was connected to the igniter via a couple of lengths of wire.

If you were feeling more adventurous, you could use an astable circuit (set to cycle every 1 sec. to run some 7 segment displays. You can have Day: Hour: Min: Sec etc count downs. (Just like in the films.) In GCSE electronics a few years ago I actually designed and built the circuit, but now I've bloody lost it. That only cost about 5 pound. If I get some time I'll re do it, and post it.

[Bitter]

You could always have conventional slow burning fuse taped over the mouth of a cheap, disposable cigarette lighter so a flick of the lighter will set the fuse alight without too much messing around. Or you could have the percussion cap system mentioned by Zaibatsu to ignite a conventional fuse rather than the complex mix of black powder, zirconium and a dozen other things you're not going to get hold of any time soon. I've tested a simple prototype of this system and it works okay as far as I can tell. This might even prove safer than the military design, providing it is made properly.

[stanfield]

VX, I was thinking to this idea long before but I don't like NE555 so I always work with the Jumala's 4541 timer circuit, so, the igniter cost me 5€ (=5$) each time ! it's too expensive but works very well...

Bitter, I don't like NE555 but I really HATE fuses ! is there is some wind, impossible to light the cigarette lighter ! secondly, if the grenade "fall" on the fuse it can snuff out the fuse !
no no no ! :) I dont like fuse at all !

I think an easy grenade could be made by putting permanganate and glycerine in two compartments. When you pull out the ring, it mixes the two components, after 5 to 7 sec, the mix start burning and ignites some lead azide or DDNP too, which will ignite the HE next...

Another question, my detonators are made of 1g PETN and 0.1g of Lead azide. When i will throw my grenade, it will fall on the floor, right ? :) :) Will shock detonate lead azide on impact ? it could be very dangerous... do I need to change my primer ? Maybe something more resistant to shock...

see ya :

[Anthony]

The grenades shouldn't go off on impact if you use LA for the primary, but there's only one way to be *sure*....

IMO the best way is VISCO and pull-string ignition - either party popper or matches + striker.

Glycerine and permanganate is likely to be unreliable and possibly dangerous. What if your vials leak over time, or from external knocks? You wouldn't know about till the grenade went off, possibly taking your nads with it. This kind of delay would also be rather unpredictable as regards to weather. On a real hot day, the delay might become &lt;1sec, in winter, the reaction might not ignite at all.

[nbk2000]

If you use a potato masher style grenade, you could mount the electronics in the handle, and likely recover them intact after explosion.

Chemical delays are fine if the time of explosion is irrelevant, as long as your not around.

But for a grenade used in the normal fashion, reliabilty of delay is vital! You have to know to the second how long you've got to hold onto the grenade (cook-off) before it'll explode.

Visco fuse and pullstring ignitor is utterly simple and reliable.

[stanfield]

ok !
Essential question : how to make homemade pullstring ignitors ? :)

see ya !

EDIT : I ask this because, in my bloody country, it's nearly impossible to buy pyrotechnics from Skylighter or Fireworx,... shitty governement !

<small>[ December 11, 2002, 02:13 AM: Message edited by: stanfield ]</small>

[nbk2000]

<a href="http://isuisse.ifrance.com/emmaf/anarcook/igbook.htm" target="_blank">http://isuisse.ifrance.com/emmaf/anarcook/igbook.htm</a>

I feel dirtied for having to provide a link to an Anarchist Cookbook article. <img src="http://www.roguesci.org/ubb/icons/icon26.gif" alt=" - " />

LEARN TO SEARCH! :mad:

[stanfield]

I browsed google before ! but found nothing ! sorry !

[Anthony]

stanfield, you know Party Poppers - those things where you pull a string and it shoots out a load of paper string?

Disassemble on of those and remove the string attached to the propellant, which is wrapped in paper. Buried in a starter mix, such as BP, will ignite when the string is pulled. Apparently it will also work if inserted into the split end of visco.

[Mr Cool]

Cut a slit down one side of the party popper thing, so you know which way the hot gases will go. Otherwise you might get unlucky and get no sparks etc falling on your igniter (unless it is surrounded by BP).

Edit: and for god's sake, don't use a KMnO4/glycerol delay! Tiny changes in the ambient temp., mixing, proportions, moisture (glycerol is hygroscopic) etc will have quite massive effects on the delay. On a warm day under certain conditions it can be &lt;1 sec, under different conditions it can be a few minutes. And also it'd be a lot better to have a small source of flame to ignite the detonator, otherwise it might take an extra few seconds to burn until it reaches the detonator. You can't use KMnO4/glycerol in small amounts, it never gets hot enough to ignite.

<small>[ December 11, 2002, 02:15 PM: Message edited by: Mr Cool ]</small>

[BoB-]

For a simplified electrical grenade, the E-match would ignite the fuse train, its connected to 2 switches, 1 is a normally-on switch and the other a micro-toggle with a clear on/off indicator, even possibly an LED to let the user know when the fuse train has ignited.

The user would hold down the normally-on switch with his thumb, and flip the toggle, when thrown the normally-on switch is released (duh) and the fuse train is ignited.

The battery, switches, and fuse train could be imbedded in Bondo, or fibreglass in the top of the grenade. For waterproofing of the switches, see-through plastic wrap could be wrapped around the top of the grenade body.

Providing you stay clear of Radio-Hack, the whole deal shold only cost you a few bucks.

[stanfield]

I have some sodium azide for lead azide production... I know this stuuf produces lot of gases when ignited. Is there a way to use this stuff in a grenade or a delay igniter ? this could be fun...and reliable !

see ya !

[Anthony]

You could press it into a tube to create a time fuse, but many pyro comps are good for that. But, this kind of fuse for a grenade is inherently dangerous.

Save the LA for blasting caps...

[Agent Blak]

I will beuploading a PDF to the FTP around new years Called C-Spec_A1. In it there are several(4) ignition Systems. Watch For it.

[stanfield]

ok, say when it's up and where it is ! the ftp is huge :)

thanx...

[Tcell]

Admittedly, this is a bit late... AFAIK, the chemical fuses in a hand grenade is a vial of acid which is broken when the handle pops up, and this eats through a sheet of metal at as specific speed which then ignites the explosive.

[nbk2000]

You're thinking of the delays used for sabotage. All modern grenade fuses are pyrotechnic (burning) delays.

[SMAG 12B/E5]

Although the modern grenade fuse is composed of exotic "gasless" compositions, the WWI and WWII hand grenades used a compressed or tamped fusetrain of black powder or modified black powder. Finely ground coal is an example of a modifier commonly used.
The fusetrain mixture must be moistened very slightly (alcohol/water) and then compressed into the fuse body with a small ram. The mixture and ram pressure must be duplicated with each fuse if repeatable performance is to be expected.
These fuses must be vented but waterproofed (glued disc of AL foil). The primer must be light but hot (addition of AL or MG powder).
The most convient source of fuse bodies are the expended fuses from "practice" grenades generated during troop training. The same fuse bodies may be easily cast from AL or "pot" metal. The striker, striker spring, pin and spoon are easily fabricated.

[stanfield]

could you give me an example of what chemical ignites with sulfuric acid ? Chlorate, no ? is there another ?

thanx !

[vulture]

Both chlorate and permanganate compositions ignite when reacted with concentrated sulfuric acid due to the formation of ClO₂ and Mn₂O₇.

<small>[ December 27, 2002, 01:46 PM: Message edited by: vulture ]</small>

[10fingers]

deleted

<small>[ January 01, 2003, 07:28 PM: Message edited by: 10fingers ]</small>

[Mr Cool]

Hmmm... so it's basically a sort of thermite. Have you tried it? I remember you saying that you'd bought some silicon a while ago...
I like BoB-'s idea for an electric grenade, I'd definitely use something similar to that if I was making one. But the toggle switch (the equivalent of the pin on conventional grenade designs) would need to have a safety mechanism attached to stop the grenade from being initiated by accident. That'd be easy enough to arrange though.

[stanfield]

more of that, on the "ground impact", if the switch goes off, the timer will stop...

[nbk2000]

As long as the switch was recessed, or locked on, then it's be OK.

Obviously the grenade would have to be designed so that the enemy you threw this at couldn't turn it off before it exploded.

<small>[ December 29, 2002, 06:45 PM: Message edited by: nbk2000 ]</small>

[stanfield]

ofcourse, but if the timer is 3 sec, on the "ground impact" it maybe remains 1 or less second,... a bit short to defuse ! :)
Yeah, I think the ideal time is 3 or 4 seconds, no more.

[stanfield]

unfortunately, I believe that with Jumala's Timer I cannot use short time like 3sec, damn... I will look at this.

[vulture]

Just turn around the principle....when the enemy thinks he's defusing it, he's actually engaging the mechanism... :D

[Mr Cool]

Ah, well if you had some sort of 555 timer to set off the detonator, then turning it off could stop the timer, depending on how it was designed. But I would have a pyro delay pressed straight on top of the primary in the detonator (with a little vent hole somewhere), so that as soon as both switches were "on" the delay would be ignited, and the only way to deactivate it would be to open up the grenade, find the detonator, and dig it out, in three seconds!

[10fingers]

deleted

<small>[ January 01, 2003, 07:29 PM: Message edited by: 10fingers ]</small>

[BoB-]

It wouldnt matter if either switch were played with, after the fuse train has been ignited the switches are useless. Thats the beauty of combining the 2, the "un-armability" (Thats a word, right?) of fusetrains, and the simplicity and versatility of modern electronics.

You could even fabricate a "spoon" design with some coat hanger wire.

Mr. Cool- I didnt think of that :) a safety would be vital, you could drill a tiny hole through a push button toggle, and stick a paperclip through it to prevent movement. They also make switchs that have hinged doors on the top to prevent accidental pushing.

[aster]

I have an idea of to make a hand grenade which will explode upon throwing and hit the ground. Below is a simple diagram to explain:

</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> @@@@@@@@@*---|
@ @ ( |
@ @ ( | @=metal casing
@ @ ( | *=hinge
@ @+ | -/|=metal lever to hold the
@ @ | firing pin in cocked position
@ @ | (=firing pin in cocked position
@ @@# | +=hinge and string that makes
@ # | the firing pin strike when
@ @@# | released to hit primary exp.
@ @ | #=primary explosive that impact
@@@@@@@@@ | sensitive</pre><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">This simple diagram maybe made into real grenade casing with the help of a metal and mechanical expert.

This should help - Anthony

<small>[ December 31, 2002, 09:04 AM: Message edited by: Anthony ]</small>

[aster]

oops the diagram looks strange, sorry...

[Eliteforum]

I can't make it out, do the diagram again in Paint as a picture. :)

[aster]

ok, i can make the diagram on a bitmap file in my floopy disk, but how to send/ display this image in this forum? the image must contain http//...

(Go to <a href="http://www.boomspeed.com" target="_blank">www.boomspeed.com</a> and get an account. It only takes 5 minutes to set it up. Then upload the picture and post a link to it. ~ MrC.)

++++++++++++++++++++++++++++++++++++++++++++++

Also, since you're doing it as a bitmap, that means it's going to be huge. If it's more than 50K in size, you have to provide a link to the file, rather than directly displaying it here. Otherwise, it takes forever for the topic to load while the giant BMP file downloads. Not everyone here has broadband. NBK

<small>[ January 01, 2003, 12:57 PM: Message edited by: nbk2000 ]</small>

[aster]

thanks all, i have made my another idiot picture, :D (http://www.boomspeed.com/donnebedian/improvisedgrenadediagram.bmp)this diagram seem far more simple than i have ever seen at "How stuff works", this diagram based from a simple mechanism, like toy...he..he, but this is reliable, and dangerous too, <img border="0" title="" alt="[Eek!]" src="eek.gif" /> because there is no safety pin, only idiot (like me!) makes a simple toy became dangerous /lethal stuff <img border="0" title="" alt="[Wink]" src="wink.gif" />

[Eliteforum]

From 224kb, to 4.1kb.

For those of you on dialup:

<img src="http://www.boomspeed.com/eliteforum/improvisedgrenadediagram.gif" alt=" - " />

[chemofun]

Would a mix of potassium chlorate and sugar be sensitive enough to burn if it was hit by an improvised firing pin/hammer (made of some nuts and bolts powered by a spring that powers the pump of shampoo and lotion bottles). I had started making an improvised hand grenade, but I'm not sure what to use for the percussion cap. It needs to be sensitve enough to ignite from the aforementioned hammer and hot enough to ignite a BP or Potassium nitrate/ sugar fuse. I would buy fuse but I cant find any anywhere.

If anybody is interested in my design, I'll try to put up pictures of the prototype when I finish it.

[Skean Dhu]

What about a Spring and Gear assembly that as soon as the spoon is released it starts
unwinding and when in the correct posistion it trips a spring-loaded center punch or hammer of sorts which in turn hits a rifle primer detonating the booster/main charge? It is both reliable and if design properly near impossilbe to set of due to jarring and such.

[SweNMFan]

I was thinking of toy gun caps.. Alot easier to get than real ammo.. When I was little I used to scrape out the stuff from a few caps and put in one, and my toy gun always made the largest bang :-)

[tiac03]

I know this is an old post and should probably be forgotten but:


First thing, learn about grenades, you can learn some things on sites such as
http://www.globalsecurity.org/military/library/policy/army/fm/3-23-30/index.html

then if you want to make your life more simple you go to a site like

http://www.e-gunparts.com/search.asp (type grenade in the search bar)

and buy a dummy grenade. (most come with everything except the striker/spring, which they acually come with the replacement heads which they also sell.)

Only thing with the dummy grenades is that they have a hole drilled in the bottom, which can be easily fixed by welding.

They are pineapple grenades.

First thing to do is drill out the spent primer
-fill "tube" with delay element of choice (black powder, smokeless powder) anything that burns. If you can put it in a tube or straw and it burns consistantly and right to the bottom, then it will work.
-test out delay length by lighting it in that state.
-if satisfactory cool, clean and refill.
-place new primer back into spot, if for some reason you screwed up and it's slightly loose ,glue it into place with just enough glue to hold it.

Now all you have to do is bring the striker back, lock it into place with the spoon and pin.
Connect a detonator to the bottom of the "tube" (crimp it into place on the given indent.
Lastly screw it back into place in the body of the grenade. (with high explosive filler of choice, nothing heat/spark sensitive or you will get what you deserve for being so stupid) Most new grenades use Comp B.

Finally you pull the pin and throw it, follow first link for exact method of holding and tossing. No hollywood "cooking off the grenade" in home made ones unless you can guarantee (with your life) that the delay element provides you with the delay expected. Lastly you pray to whom ever you pray to that you didn't screw anything up, (make it a quick one though, because if that grenade doesn't make it 5 meters, consider yourself dead, and if it doesn't make it more than 15m then you will have fun explaining your story to the local police whilst the doc pulls what is left of your grenade out of your ass.

(Procedure, is what I would do with my dummy grenade, if I ever wanted to use it for "making holes in ice"...)

[armchairsapper]

I realize this is a rather old post but it is a pretty good one and I have my "two cense".
As Tiac pointed out, the best way is simply rearming an “inert practice” grenade.

However, rather than filling in the fuze hole with blackpowder or whatever. A better method is to drill out the fuze hole to accept ¼ or 7/32 in. safety fuze. Instead of using a rifle primer, a .25 acp round with the bullet removed works much better. The fuze assembly has a cavity just above the fuze and bellow the primer; fill with smokeless powder or black powder. Also, the grenade bodies are cast iron, which is hard to weld. JB Weld is sufficient, especially if you are using HE. This method works very well.

[Charles Owlen Picket]

This is indeed the technique that is a well trodden road. <Cast iron can be brazed.> Additionally the mold for the Mk 2 pineapple bought as a paperweight is so extremely close to original that it MAY be taken from an inert; way back when....The basic problem is that grenade bodies break from the inside out so the scores on a "pineapple" really have less impact in the break up than most folks think.

[file]

I remember reading something on that. The reason they kept the scoring after discovering that it didn't do anything was because it provided a solid gripping surface and because it certainly can't hurt. And it can't hurt performance.

A pull type ignitor like was mentioned or something like on the Japanese grenades(you would hit the end against something hard to trigger it and then you had a three second delay) would be best. A jap type ignition system was a typical pyrotechnic ignition system like in a regular grenade, but without the spoon and it's mechanism.

[armchairsapper]

There is more than just the "pineapple" available. The "baseball" is the same size and shape as the current frag used by the US Army. If you are looking for fragmentation; then just add some ball bearings to whatever HE you use.

But honestly if you were to rearm a "practice" grenade you really shouldn't be to concerned with fragmentation as a 1/4 lb of HE is pretty sufficient for most uses.