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Author: Subject: Unconventional Shaped Charges
Laboratory of Liptakov
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[*] posted on 11-8-2015 at 10:43
contruct


OK, thanks. This contructions ?

target.jpg - 101kB
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greenlight
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[*] posted on 11-8-2015 at 18:31


Yes that's pretty much exact design except there was no powder charge in there. The entire charge was 16 grams plastic and explosive height was about 20mm so 2/3 of liner diameter.
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nux vomica
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[*] posted on 12-8-2015 at 02:25
Plastic etn efp


I tried the bug board pib to make some plastic etn I used enamel thinners to dissolve the pib then mixed the etn in, the pib ratio was 13%, this pib will work but its crumbly not a mouldable mix like play doh, so I bought some castor oil and will make some Methyl Ricinoleate and see if that makes a better mix.
I had a copy of Risi rp4 sff so I packed 5 grams of the plastic etn in it and used a 0.6mm thick copper disc 19mm in dia with 6mm offset standoff was 410mm and steel angle 10mm thick, setoff with my standard ebw head at the end of 7 meters of rg6 cable at 3500v.

The bang didn't have that sharp crack that I am used to but I got full penetration through the 10mm steel and the flyer penetrated through 150mm of dense clay behind it then shot off at a angle so I didn't find the flyer :(
p
Pretty happy with result from first try of plastic etn will be making another batch soon for more testing.

cheers nuxy




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[Edited on 12-8-2015 by nux vomica]
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[*] posted on 12-8-2015 at 02:49


Thats a nice result for 5 grams of PE and a 10 mm target.:)
My PE is the same when I mix the binder in it just stays crumbly, try adding some % motor oil as well and working that in. It holds together much better then.
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nux vomica
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[*] posted on 12-8-2015 at 02:54


Quote: Originally posted by greenlight  
Thats a nice result for 5 grams of PE and a 10 mm target.:)
My PE is the same when I mix the binder in it just stays crumbly, try adding some % motor oil as well and working that in. It holds together much better then.

Thanks I will try that if my castor oil methyl ricinoleate experiment don't work out. Nuxy

[Edited on 12-8-2015 by nux vomica]
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[*] posted on 12-8-2015 at 11:28
liner


Hmm, good work, Nuxy. 5g and 10 steel troughout, its nice results. But I see no precise surface on the Copper liner. Pic 2. It is maybe reason, why is on the target so large dispersal. Bridgewire point is precise center? Thanks, Liptakov
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[*] posted on 12-8-2015 at 15:12


Quote: Originally posted by Laboratory of Liptakov  
Hmm, good work, Nuxy. 5g and 10 steel troughout, its nice results. But I see no precise surface on the Copper liner. Pic 2. It is maybe reason, why is on the target so large dispersal. Bridgewire point is precise center? Thanks, Liptakov


Yeah thanks, you have sharp eyes the liner was slightly buckled but I decided to use it anyway, plus the liner curvature was the same as the smaller ones that were jetting so I think the liner may have been trying to form a jet the hence the 6.27 dia hole I am going to try a 140° cone next and see if there is a difference.
The bridgewire is jig driled so I dont think that is affecting the results of the charge. cheers Nuxy

[Edited on 13-8-2015 by nux vomica]
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[*] posted on 12-8-2015 at 22:20


How many mm deep is your depth of curvature (the lowest point in the curve of the liner) nux?
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[*] posted on 12-8-2015 at 22:45


Quote: Originally posted by greenlight  
How many mm deep is your depth of curvature (the lowest point in the curve of the liner) nux?


6mm greenlight it has the same dia to depth ratio that my rivnut cylindrical liners has, I made it a while ago but useing plastic with lower velocities thought it might work ok as a efp .

Edit if you use 30 plastic pipe the steel ball to form the liner would be 30 x 1.0869= 32 rounded so use a 30 mm hole in hardwood block and drive the 32 mm ball into the copper sheet and trim evenly to 30 mm . Cheers nuxy

[Edited on 13-8-2015 by nux vomica]
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[*] posted on 13-8-2015 at 01:33


I drew a quick sketch of your liner and my liner to scale with a mm ruler.
I think it would work better as an EFP and produce a more slug-like projectile if you took the depth of curve down to 3 or 4 mm on your liner.
Yours has much more of a curve height and I think this is causing it to form smaller diameter holes because its is almost acting like a CSC/Munroe effect as the sides of the liner collapse around itself.
If you treat the arrows as a shockwave, they are much closer together as they intersect with the liner on your flyer plate which would definately form a more elongated projectile if I am correct.


20150813_170840.jpg - 3.5MB

[Edited on 13-8-2015 by greenlight]
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[*] posted on 13-8-2015 at 04:30


Quote: Originally posted by greenlight  
I drew a quick sketch of your liner and my liner to scale with a mm ruler.
I think it would work better as an EFP and produce a more slug-like projectile if you took the depth of curve down to 3 or 4 mm on your liner.
Yours has much more of a curve height and I think this is causing it to form smaller diameter holes because its is almost acting like a CSC/Munroe effect as the sides of the liner collapse around itself.
If you treat the arrows as a shockwave, they are much closer together as they intersect with the liner on your flyer plate which would definately form a more elongated projectile if I am correct.




[Edited on 13-8-2015 by greenlight]


You are right about the liners having a effect like a Monroe s/c henning thought the same thing the rivnut ones did the same I was hoping plastic etn would cancel out some of the hybrid affect .
Oh well I wil try a 140° cone next cheers nuxy
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[*] posted on 13-8-2015 at 07:20
Soft recovery system


Projectile recovery system ready to test.
There is a 1 meter pipe filled with packing styrofoam, a 2 meter pipe following filled with sawdust/wood shavings and a 1 meter pipe behind this filled with 9 liters of water and a clear plastic window so the slug can pass through.
All pipes are 110mm ID.
Hopefully this should catch it without causing extensive damage.


20150813_231202.jpg - 3MB

[Edited on 13-8-2015 by greenlight]

[Edited on 13-8-2015 by greenlight]
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[*] posted on 13-8-2015 at 09:32


Huuh.. Super digital aparatus catching system. :cool: But 110 mm diameter is not very. You need very precise aiming on target. I am afraid that slug flips out of tube offside. I look forward to the results. :o Liptakov
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[*] posted on 13-8-2015 at 09:59


I will do my best to get the pipes straight using a level and will aim EFP using a laser pointer.
If it fails to contain the projectile effectively I can always use bigger diameter pipe or cardboard boxes filled up with foam/sawdust/water jugs.
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[*] posted on 13-8-2015 at 16:12


The projectile may sail off course enough to leave the tubes, even if aiming is done perfectly. Interesting experiment, hope it works out.



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[*] posted on 13-8-2015 at 18:19


I am hoping nothing causes it to stray, but thanks I will post results as soon as I can
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[*] posted on 14-8-2015 at 01:20
First recovery no-go


Okay, so the first recovery system went not so well.
Even though a hand level and laser pointer was used to ensure everything lined up correctly, the EFP slug seems to have just touched the side of the first pipe evident by the large piece that has been removed in the picture. This caused it to slide along for a bit before punching through further down and exiting the pipe in the other picture. Theres is a penetration hole in the sawdust pipe right in the middle but after inspecting the contents, it was a small piece of copper shrapnel probably breakup when it exited the tube.

I think for the next test I will use styrofoam boxes with the same setup and contents. Then I will not have to worry about the projectile straying because there will be plenty of room.

[Edited on 14-8-2015 by greenlight]

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[*] posted on 14-8-2015 at 02:00


Really cool to see people are trying to catch the EFP projectile. The idea of holding something in your hand that has travelled around 4000 m/s is pretty awesome.

A thought I had was maybe go to a farmer and ask for a large bale of straw. (It would literally be searching for a needle in a haystack afterwards though...unless you have a metal detector :D) Not sure it would be soft enough to catch the EFP reasonably undamaged though. :)

[Edited on 14-8-2015 by nitro-genes]
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[*] posted on 14-8-2015 at 03:15


Yes the idea that you can actually catch something that penetrates steel with relatively soft materials is very interesting.

Yes straw could work, maybe pack it into boxes and place them end to end.
In a pdf that Hennig linked a few pages ago about EFP penetration into concrete, they caught a few projectiles without much damage by firing them into about 2 meters of styrofoam, 3 meters of vermiculite which I haven't heard of (I think it would be similar to swadust), and a couple of cardboard boxes all wrapped together in bails like you see out the back of shops with a water container behind as a last effort.
Considering that the EFP's had diameters of 110mm and charge weights of 800+ grams this setup did quite well as the slugs never made it into the water, they were all caught in the cardboard.
Very little damage too so the straw would work well.
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[*] posted on 14-8-2015 at 03:20


Its looks a bit like threading a needle greenlight, still nice try pity it didn't work, how big was the efp charge.
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[*] posted on 14-8-2015 at 03:31


Yes it was kind of like that haha, took about 15 minutes to just sight the charge.
I used the exact same EFP dimensions as the last test on steel.
16g plastic/30mm diameter liner/0.9mm Cu/ 60cm standoff.




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[*] posted on 14-8-2015 at 03:32


One pack of straw might be enough to get most of the kinetic energy absorbed for these charge sizes indeed. Maybe a bucket of water placed directly after the straw pack could provide some insurance that it hasn't penetrated the entire pack (else a lot of searching could be done, while the projectile is 1 km further down range :D)

It might even be possible to make a standarized setup in which the fired projectile travels throught the straw and ends up at the bottom of the bucket of water and can be simply fished out. Blocks of gassed concrete (the low density stuff)directly after the pack of straw might also do well indeed, good idea!

[Edited on 14-8-2015 by nitro-genes]
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[*] posted on 14-8-2015 at 03:34


Had a bit of a failure myself too, running low of etn and going to make new batch on the weekend but wanting to try a bigger efp, I tried a annmal charge its 70% ammonium nitrate 23%nitro methane and 7% aluminium powder, used a cardboard tube with a 140 degree cone and 20 grms annmal setoff with a ebw detonator standoff 500mm and the other side of the 10mm angle as a target.

It didn't penetrate the ten mm angle got almost 9mm through in half of the 13mm dia hole and bulged the back of the plate I am drying the ammonium nitrate as I think its slightly damp being stored for several years and will have another go in the next couple of days nuxy.

[Edited on 14-8-2015 by nux vomica]

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[*] posted on 14-8-2015 at 03:49


@ Nitrogenes...Yes I think the water is essential as a last ditch effort to ensure that you collect the EFP slug.
I think another problem is to make sure that it does not ricochet off anything as mine just skimmed the inside of the pipe which sent it straight out the side.
I think I will try: box of foam. box of foam. box of wood dust. box of wood dust. box of water.
Hopefully that should do it with minimal damage.

@Nux...What is the VOD of ANNM? 6000-6500m/s?
I have seen CSC's with ANNM explosive that worked but never EFP. I wonder if it is as suitable as (P)ETN which have higher VOD'S.
Sounds like it worked okay though for a non-plastic explosive. I had the same problems when I was using powder HE's as main charge. Used 30 grams once and still didn't get through the damn 7.5mm plate.:o
Maybe get rid of the aluminium powder, I read somewhere I think that it doesn't work as well in shaped charges. I may be wrong though so don't quote it.

What diameter was your EFP?







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[*] posted on 14-8-2015 at 04:05


28 m dia .6 thick 140 degree cone
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