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Fulmen
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| Quote: | Originally posted by Swany
Perhaps because they may not make them in glass?
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Can't say I've ever seen those in glass, but conical centrifuge tubes are pretty common both with 30 and 60° angle: http://www.schott.com/uk/english/download/04_test_tubes.pdf
| Quote: |
I am developing a ETN/TNP cast comp that may be interesting as a shaped charge explosive, though it needs to be kept very dry. It has some interesting
properties... |
I love it when you talk dirty :-)
[Edited on 1-2-06 by Fulmen]
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Swany
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40g of the cast ETN/TNP mix with a .5g AP cap only partially detted, though I blame bad cap placement and doubtful TNP quality on that.
On a happier note, 11g of ETN/NG plastique in a 2:1 ratio was made into a small ball, and a .5g AP cap stuck into it. It was not nearly enough to
cover the cap, so I simply moulded it around the bottom half of the cap, stuck it on the bottom of an unpside down cup, and called it good. It was
really quite amazing, I belive I will try this comp in some small shaped charges. Adding a fuel (like some of the dark german Al in my lab) would make
quite a nasty mix. It is also extremely mouldable, and holds its shape well. It is like a stiff sugar cookie dough. 
I shall try it with some glass liners from lightbulbs, or whatever I can find soon.
My lb of ASA arrived, so I can make some quality TNP to continue with these expirements.
[Edited on 1-2-2006 by Swany]
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nitro-genes
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| Quote: | Originally posted by Swany
I shall try it with some glass liners from lightbulbs, or whatever I can find soon. |
Lightbulbs certainly work  Best lightbulbs are candel lightbulbs (attachement).
I achieved 4,7 cm with a such a liner of 3 cm diameter with PETN/NM plastique. They have a good conical shape, but unfortunately they are too thin for
a realy good performance.  (Because glass is much less dense than copper you need
a thicker liner to have about the same mass)
Tricky part is cutting a liner out of them, I used a small string of cotton, soaked in gasoline. After the string stops burning, dump the lightbulb in
cold water. It takes a few tries, but it works. 
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Boomer
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That's from the improvised munitions handbook, for cutting wine bottles for SCs. I doubt it works well for a 30mm dia lightbulb. Would not the flame
be at least an inch, heating the whole bulb? How shall it cleanly part in the middle, instead of shattering completely? Why not mechanically remove
the bottom, leaving a build-in 2 CD standoff?
Maybe "a few tries" means you used three packs of bulbs before getting one liner?
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nitro-genes
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It realy works, try for yourself. The trick is very local overheating and
exansion of the glas, so the string should be as thin as possible, just to hold enough fuel to burn for about 5 seconds...The icecold water makes the
glass contract and break. The cut usualy is very clean, but sometimes the glass has some additional cracks, these small cracks don't matter for
performance.
I first mark the boundary of the fitting on the glass, then I make a lasso out of cottonstring and attach it about 0,5 cm under the marking. Then I
add the fuel (lampoil, gasoline, thinner) and light. I have found that these glassliners glue reasonably well to pvc with pvc glue.
You are right removing only the bottom is a better option, but since I detonate all my charges underground I decided it would be too fragile. I indeed
took me 3 lightbulbs before I had a good cone btw, but @ 0.56 cents each is not that much of an expense. It is a lot of work though .
But for me the work is worth the effort. Making a large liner is more easy then a very small one, but a large liner, like the glassfunnels, need a
large amount of explosive which is also expensive, hard to come by and more dangerous...(the 3cm glassfunnels give small performance) So for me the
trade off is work for less explosive material...
[Edited on 3-2-2006 by nitro-genes]
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Swany
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$2 for one cone is a bit too expensive for me, 50 cents is less painful. If the process could be improved to give consistant results, that would be
good.
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nitro-genes
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Just made a clay out of metalpowder, but since I had no copper powder I used zinc instead. I used about 2,5% PIB, extracted from self vulcanizing
tape, with about 8% gasoline. The resulting clay was a bit more sticky and less stiff than with motoroil. This was rolled to about 1,5 mm and put over
a 5 cm diameter hemisphere. (this was the hard part) Thinner than 1,5 mm might prove difficult so small liners may be a problem, but there is room for
improvement of course.
I then waited for the gasoline to evaporate. The resulting material seemed fairly brittle but holds together quite nicely. It isn't strong enough to
be separated from the mold I think...
I was quite excited with this result, so I was stupid enough to try to melt the material together with a blowtorch. Of course the zinc powder started
to oxidate immediately, so copper powder is a better option I guess.  It made a
nice blueish flame though.
On the other hand, maybe it isn't even necessary to melt the powder together? Anyway I will certainly give the vitamin C synthesis a try after the
exams.
[Edited on 4-2-2006 by nitro-genes]
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Chris The Great
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Well I tried my own cylindrical shaped charge today, but unlike Axt's mine failed miserably. 
I made it some time ago. I used black plastic pipe (NBS maybe? Not sure) since I had some sitting around. I drilled a hole through the base, and
stuck the 1/2" copper pipe in using two part fast setting epoxy. I then carefully made a round top from that little plastic thing from the inside of
a pope bottle lid, and glued that to the pipe using more epoxy. The parts where then pushed together, since glueing wasn't necessary as it didn't
leak (and since I had already pulled it apart once already I felt being able to do that again would be helpful).
I measured the volume using some water, and it came out to be 100ml (exactly as I calculated when I designed it on paper).
The target was the cores from two microwave oven transformers, which was roughly 4.5 inches of steel plates about 1mm thick.
At the target site, a small dip in the forest to keep us (me + friendly spectators) safe from anything that might possibly fly out from it, the methyl
nitrate was poured in (I was worried it would dissolve the epoxy and plastic, so transported it to the site in a plastic pop bottle), the cap pushed
on, and a detonater pushed in through the hole on the top (pressed AP in a metal case from a battery, about 0.5ml pressed AP total, didn't weigh it).
It was set on top of the target with high expectations.
Friend tossed me his socks he got covered in mud when he got his shoes stuck in some on the way there, I wrapped them around the charge, and they
retreated to our safe spot about 100 feet away (since there was a thick mound and some trees between us and it, we didn't really need to get that far
back). When they were ready, I lit the cheapass sparkler fuse and ran like hell. It's really amazing how fast you can run when there is 100ml of
methyl nitrate about to blow up behind you.
Anyway, after a wait for the fuse to burn down, there was a flash (despite it being behind a little hill) and the loudest KABOOOOOOOOOOM I have ever
heard, which echoed off into the distance for about two seconds. Opps, wasn't expecting it to be THAT loud. Ran back to the target site, grapped the
target, and left (and forgot to take a picture! Arg!). The target was rammed completely into the ground, and there was only dirt around it, ie it
blew all the stuff on the ground in the first pic away. No penetration.
Got back home, cleaned all the dirt off the metal and put it back together. As can be seen, it bent the metal quite a bit but didn't penetrate at
all. There are copper stains on the top piece. If you look closely you can see that the entire thing is slightly curved from the blast. But I
wanted a hole all the way through the metal!
I think the problem was either that the blasting cap didn't go in straight when I put it in during field conditions and low visibility as as the sun
was setting and the forest was quite dense, or that it didn't quite touch the explosive, or both. The reason it might not touch the explosive is that
the blasting caps will just go into it when inserted fully since the end caps have a ridge in them which puts them up an additional half inch or so.
Since there was tape on this one, it is possible that I did not push it in far enough to make contact with the explosive. Since methyl nitrate is
extremely sensitive to detonation however, it still exploded with a huge amount of force.
Next time I will spend alot more time making sure everything lines up and fits together perfectly before I head out, rather than trying it
once or twice and then assuming it will work under sub-optimum conditions.
[Edited on 10-2-2006 by Chris The Great]
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h0lx
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I think the problem was not providing enough standoff for the chage, from the image I see there was no standoff.
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Deceitful_Frank
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Or more likely that the target was laminated and not one solid peice. This could have caused the softer glue between the layers to absorb all that
hard faught explosive power. Like if you took ten 1 mm steel plates but put a layer of rubber between each. When you struck it with a 9 pound hammer
it would just bounce off!
You should try a much less elastic target A thick solid steel plate next time
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Chris The Great
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| Quote: | | Close to zero standoff should provide the best performance since the jet should be fully formed within the cavity. |
No standoff should be needed for the cylindrical charge. The jet would have penetrated the target no matter if the target happened to be able to
absorb the blast.
So the jet simply failed to form, probably from the reasons I mentioned.
[Edited on 12-2-2006 by Chris The Great]
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Deceitful_Frank
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Next time I would also suggest putting the target onto a SOLID platform like a concrete wall or engine block. This will vastly increase its inertia
and waste less energy than with your test when it was driven into the ground.
I cant see there being a problem with the cap as IIRC myrol either goes pretty much full power or doesnt and does not suffer from LVD like NG.
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Deceitful_Frank
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Next time I would also suggest putting the target onto a SOLID platform like a concrete wall or engine block. This will vastly increase its inertia
and waste less energy than with your test when it was driven into the ground.
I cant see there being a problem with the cap as IIRC myrol either goes pretty much full power or doesnt and does not suffer from LVD like NG.
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Fulmen
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I agree, it's unlikely the fault was either the target or the standoff. I'm guessing that either the cap/liner wasn't properly alligned or that there
was insufficient "overhead" on the charge. You don't happen to have any detailed measurements on the device?
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The_Davster
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If you look at Axt's first post in this thread the liners go only about half the way into the explosive, yours appears to go at least 3/4 in the
pictures. There may not have been enough explosive above the liner, which was what Fulmen was getting at with the insufficient overhead coment
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Chris The Great
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Hmm, yes, it would be that. Here are the measurements, and just for the heck of it the calculations.
Total length of the explosive cavity is 90mm, the liner goes up 60mm leaving 30mm overhead space. The outer diamter of the pipe is 13mm. Diameter
(inside of the plastic) is 38mm. I didn't fill it right to the top at the site so the "overhead" was more around 25mm. I'll try a 45mm:45mm setup
for the next charge, whenever that may be (hopefully soon?).
Jet mass was calculated to be 0.655 grams, travelling at 16,000m/s (KE 84KJ 
major energy on a very small area), the slug calculated to be 19.845g travelling at 510m/s (KE 2.5KJ). The slug velocity may be off since I assumed
methyl nitrate would have a Gurney energy of 2.86 since the brisance is similar/higher than PETN, and that value was used to calculate the slug
velocity using vectors and the angles of the implosion process (maybe advanced math is a little helpful in real life).
Frank, the actual jet penetration process happens so fast that whether or not the target is secure or not means nothing. The jet will be through the
target before the target even begins moving from inertial effects. Things like movement travel through the target at the local speed of sound, which
the penetration process vastly exceeds. The jet is through the target before the rest of the target "knows" it has been penetrated. The force that
hit the target into the ground and bent and twisted it is the force from the detonation shockwave that hits it on the sides of the liner, which
wouldn't go into the liner anyway. This is also the energy that well into causing the spalling of the metal Axt had in his test. So I don't really
care if it gets slammed into the ground, except I did have to dig it out with my hands afterwards.
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Deceitful_Frank
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Wow! I have just learned something new. and it was explained in an excellent manner with plain english. Thanks CTG for that one
Well looking at your measurements and calculations it seems obvious that lack of head height and a bad subcalibration ratio was to blame. I would
suggest giving it 1 or even 1.5X the heght of the liner headheight and either use a narrower tube or make the internal diameter or the charge nearer
to 50-60mm.
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Fulmen
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I agree with Frank here, increasing the subcalibration ratio and charge length seems like the obvious way to go. A fixture to ensure that the
detonator lines opp correctly could also be beneficial.
Keep up the good work. Hopefully I'll get a chance to test my 54mm hemi soon, then we'll se who's the big dog here 
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Coolio
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I think i´ll test in the next few days a cylindrical chaped charge with the same like Axt,..but on a 2" thick (~ 5cm) thick steel plate.
I hope it works because the steel plate is fucking heavy....
And the way to the big wood there is a lot of snow...so I am fucked up with my 50ccm motocycle
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bomberman41688
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I ran out of real HE but do you think some sensitized tannerite my work as a weak shaped charge? I was gonna try using aluminum for the liner just to
see how effective it might be.
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Swany
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No. I will let someone who can explain it best, explain why not exactly. You need a brisant explosive. AN sensitised mixtures are hardly ideal. The
best you will get is an aluminum plated steel plate.
[Edited on 19-2-2006 by Swany]
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bomberman41688
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It was just a thought. I've used all of my good stuff, but I still have about ten bottles of tannerite left over.
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Coolio
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so the ANNMSA didn`t detonated, I used 2g HMTD .....fuu
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Ice
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| Quote: | Ursprugligen inlagt av Axt
<center><b><font size="4">Cylindrical Lined Charges</b></font></center>
Charge was ANNMSA 140:100:70. Initiation was a commercial #8 detonator. Target was 1 inch thick steel plate.
[Edited on 7-6-2005 by chemoleo] |
Is "AN" ammonium nitrate or what?
Exactly what does AN NM and SA stand for? (to avoid having to risk both life and limb)
I'm sorry if I sound like a noob, but the only shaped charges I'm used to are the ones with a hemisphere, cone or parallel plates as a lining. I firs
got the impression that the charge was supposed to go on the outside, but on the picture above on this page, the charge seems to be inside the lining.
How do these exotic babes work?
One final question for this reply: How thick should the copper pipe lining be?
[Ändrad 15-3-2006 av Ice]
If you make it bullitproof, they\'ll just make a bigger bullit.
If you make it waterproof, they\'ll just make a deeper ocean.
If you make it foolproof... Then they\'ll just find \'emselves a redneck!
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Coolio
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AN = ammonium nitrate
NM = Nitromethane
Sa = sulphuric acid (H2SO4)
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