Caseless Detonator

[Microtek]

I have been experimenting with a way to produce a more effective detonator in order to overcome my trouble with detonating plastique.
Simply increasing the size of the cap is not an option.

It is common knowledge that an initiating explosive in direct contact with a relatively insensitive HE is much more effective in detonating said HE than if said initiating explosive was contained in a cap. This effect becomes more aggravated when the wall thickness of the cap increases.
Because of this, I have experimented with a caseless detonator
( CLD ) consisting essentially of a cast cylinder of nipolit. The CLD was prepared as follows:
- 35 parts of NC was dissolved in 140 parts of warm acetone.
- To this was added 65 parts of finely powdered RDX, and the resulting pliable compound was kneaded and air-dried until a uniform wax-like appearance was achieved.
- The compound was divided into balls that were able to fit into a 6mm ID paper-tube.
- These balls were then rammed into said paper-tube while still pliable in sufficient quantity to fill the tube to a 30 mm depth.
- The CLD was dried for 24 hours at room temp and the paper was removed.
- A 2.5 mm core was drilled ( carefully ) along the axis of the cylinder to a depth of 10 mm.
- The lower 5 mm was filled with compressed RDX, the next 2 mm with compressed MHN, then 2 mm HMTD and finally 0.5 mm silveracetylide to get the HMTD going.

Upon ignition, this CLD detonated completely, leaving no residue in the hard wooden block that I tested it on. Judging from the depth of the crater in the wood, it seemed more powerful than a conventional detonator of the same size.

[xoo1246]

How sensitive is this NC/RDX casing to chock and flame?

[nbk2000]

Neither is very sensitive to impact or friction.

NC burns, without detonation, same for RDX, in small quantities.

So it should be very safe to handle.

Micro, have you thought about trying extrusion? Though I don't know if there's a significant density difference between that and compression.

This is a good idea though because the lack of metal means no metal detector can pick it up.

[Microtek]

NBK: Yes I did try using a sort of extrusion into a paper tube, but the problem is that when the acetone evaporates, a large cavity is formed in the center of the CLD ( at least it did when I used PETN instead of RDX ). If this is consistent behaviour then you could of course drill a core almost all the way to the end, and fill it with RDX or PETN, which probably wouldn't hurt performance in the least.
With regards to the clandestine perspective it would also be advantageous that a block of plastique detonated with a CLD would leave no fragments that could possibly hold a partial fingerprint, or be used for metallurgical forensics.

PS: If ignited, nipolit burns fiercely, but not nearly violently enough to make the DDT.
It is a slight problem that it ignites so easily from flame; if a primitive fuse is used, care must be taken that sparks do not strike the CLD.
I am confident that this could be overcome by coating it in a thin layer of varnish or wax.

<small>[ March 15, 2002, 04:36 AM: Message edited by: Microtek ]</small>

[DBSP]

It's a nice idea. The spark thing should definately be solved using a wax coating. What kind of fuse are you using?
If you put some pressure during the evapouration of the acetone maby it wouldn't form a cavity, but I'm nut shure how much pressure you should use.

[Madog555]

i might try this out with PETN putty and either AP puty or AP pressed into a cavity (the same way tou did it.

[Microtek]

I have recently developed a variation on the CLD which works excellently:

The idea is that for initiating thin layers of explosive such as sheet-explosives, conventional detonator shapes with length to diameter ratio of about 50:6 are not really suited. The problem is that these kinds of cap does not have sufficient contact with the plastique when placed externally. This causes unreliable initiation characteristics as well as neccessitating an extra means of securing the cap to the charge.
Consequently, an alternate form of detonator is presented:
A piece of aluminium pipe 10 mm inner diameter and 1 mm wall thickness
is cut off to a length of 7 mm.
Both ends are left open and an amount of nipolit, cyclotol or similar
type of explosive is cast or extruded into the tube, which must be placed on a flat, non-porous surface.
The end-plug thereby made is allowed to dry completely without removing the tube from the flat surface, as it is essential that the explosive only dries from the inner end-surface. This produces a smooth outer end-surface which is neccessary for optimum contact with the PBX that is to be initiated.
When dry, the cavity which is formed because of the shrinking of the NC is filled with pressed PETN or RDX.
A means of igniting the cap is introduced at the rear center of the tube; in my case a piece of drinking straw 2.5 mm OD was used. It was pushed slightly into the pressed PETN without endplug. Then Al foil was pressed down around the straw with a rocket tamping tool and epoxy cement was used to seal the tube around the straw.
A coloumn of MHN, 3 mm in height, was pressed into the straw and 0.5 mm silver azide on top of this. 0.5 mm double salts was used to ensure ignition.

The cap was placed externally on one end of a ribbon of latex-based plastique 3 mm in thickness, 12 mm in width and 25 mm long.
This ribbon was placed on a witness plate of 2 mm thick mild steel.
Upon detonation a hole of 18 mm by 23 mm was blown in the plate, demonstrating both the viability of the latex-based plastique and of the detonator.

[Mr Cool]

Sounds good.
Have you ever tried making sucrose nitrate? If you use the procedure on my site the product is a putty when warm, but when cold it is a fairly brittle solid (although it will still bend when a gradual, small force is applied).
If you used this as a base charge in that cap, and had about 1g sticking out of the bottom, then when you wanted to use it you could hold it in your hand for a few minutes to warm it up, then press the sucrose nitrate onto the main charge. This would hold the detonator in place, and provide a very large contact area between the detonator's base charge and the main charge.

[Microtek]

Yes I did try sucrose nitrate once. I didn't actually detonate it, just examined the mechanical and chemical properties. I obtained a tough bubblegum-like product, but I figured it must contain lots of acid so I dissolved it in acetone, neutralized the solution with bicarb, and crash precipitated the ONS by drowning in water. The result was brittle crystals that wasn't directly suitable as an energetic binder for plastique ( which was what I was researching at the moment ).
On this topic, I have found that if a little NG is added to acetone and an amount of MHN is then dissolved in this liquid and the acetone is allowed to evaporate, a wax-like material is produced. I'm certain that this would yield really high performance plastique if a slightly oxygen deficient but very brisant explosive such as PETN or RDX was added to suitable consistency. It would be slightly poisonous due to the NG, but not much is needed to plasticize the MHN.

[Mr Cool]

How long did you keep that NG/MHN mixture? I tried a similar mixture of MHN/SorbitolHN, but even with vaseline added it gradually crystalised and lost its plasticity. It was pretty good for a few days though, very mouldable, slightly sticky, and didn't break up too easily. And it was almost as sensitive as MHN alone. It'd be a good mixture for base charges.

[Microtek]

At present, I've kept it for 4 days, but I don't think it will lose the plasticity as long as the NG hasn't evaporated. As you know, many nitric esters are plasticized by NG, and while such a thing as blasting gelatine does set after some time, it doesn't become brittle.

[Boomer]

Hi again everybody!

Thanks to fuckdefense the whole discussion that started again after I revived this thread is gone. All I have left is my memory and the locally stored post below.

From memory:

The PETN/NG mix mentioned by Microtek + NBK is similar to my mix described in the plastic explosives thread, consisting of MHN/NG 3:1, though I used I little less MHN to get a softer mass, allowing to knead in the same weight of RDX.

Using even more solid nitrate ester, you get a mass that is soft at 50C and quite hard at RT. But I found that it is not too easy to initiate as there are neither gas bubbles nor crystal surfaces inside.

Instaed, I tried pressing the MHN at up to 60000 PSI (4 tons per square cm or one ton (big vice) on a 6m column) inside a metal pipe. Though even a 1mm wall pipe deformed, the block was hard to get out without crumbling.

Next I tried 5-10% epoxy. Only little is needed since the density (1.7) is near the crystal density (1.77 IIRC). I tried MHN, HMTD and AP, but none worked well, see below!

Last post from cache:

There seems to be hardly any binder for making caseless caps out there. After the disappointment with epoxy, which either reacts (peroxides) or doesn’t harden (nitric esters), I tried several others:

Super glue (cyano-acrylate) hardens within second, catalysed by moisture from the air (that is why it hardens faster if you breeze on it, and instantly if it gets in the eyes). The explosive cannot be mixed in fast enough.

Thinning it down with 9x its weight of acetone worked to keep it soft, you could kneed enough MHN/AP mix (4:1) in, then let most of the solvent evaporate. The resulting mass was still mouldable, and could be shaped into form.

I abandoned this mix for some reasons: It takes ages to harden, you do not know whether it has voids afterwards (though less then APP), and I hate kneading AP+solvent while it is drying: bigger crystals might be formed ….

Next I wanted to try a two-compound silicone, but it was too old and would not work. The one-compound kind needs air to dry, and will take ages again to get hard inside a cap body. Plus, it is acidic.

The last thing (so far) I tried was a PU system (PU + blue filler / diisocyanate). I tested compatibility by mixing three samples with MHN, AP and HMTD, and heat curing these at 80C. The MHN mix turned nearly black, but did not catch fire or start to smoke. The AP mix turned dark blue, but nothing further happened. The HDN mix stayed the original nice light blue and showed no reaction whatsoever.

If curing at room temperature (preferable), the MHN mix got about as hard as normal rubber (pencil eraser), the AP mix as hard as hard rubber (tyres), and the HMTD mix got as hard as wood.

I prepared three caps, one of each, by pressing 2g (+0.2g binder) of each mix into a pipe, then cutting it lengthwise to peel the block out. I tried PE and aluminium, coated with PTFE inside using an “oil- and fat-free PTFE lubricant spray” which left a dry, white residue. The HMTD block (right, with hole for primary of EBW) peeled out easily, the MHN block (middle) was OK, but the MHN/AP block (left) got deformed. I must admit that in the last case I had pressed too hard, which partially split the pipe.

If I get the digicam in time tomorrow, I will edit this and add pics. There are also some improvements in the pipeline (two-part die for pressing, dowel with pin to form cavity for primary, filler-free PU to get by with less binder …. ).

So far the old post.

Here comes a pic of the caps described above, and the die used for pressing the small cap which is still inside. The inner surface of the die was sprayed with PTFE before screwing together and filling.