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grndpndr
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I suspect the terahedron or even pyramid soldered flat plate
liner will be an exerc cise in futility and given the work involved for a design thats been abandoned possibly for decades if not longer a
dissapointment even if the impossible is done and a relatively precise form is made results will be dissapointing at least.
Id considered AXTs glass cone with a copper overlay until I happened upon a paper that indicated the jet essentially wouldnt be a cohesive one.The tip
of the glass jet would attain a different velocity than the tip of the copper jet resulting in an incoherent jet of different velocitys.I suppose
this extends to composite matrix liners unless the characteristics are carefully matched even in a matrix dissimilar liner materials are bound to
fail.EFPs that retain a solid penetrator dont share this problem apparently.
This is Im sure a very infantile question and if im flamed unmercifully its likely deserved but after a wk or more of searching ive yet to find a
mathematical method to form a sheet metal cone or rostrum.It would seem to be simple geometry but the sheet metal sites treat it as old tech and only
have CAD/CAM to offer and ive been unable to find what must be a simple geometry equation to layout the flat form for fabricating a cone. Using a
copper sheet cone layout and repeated annealing I expect a repeatable cone could be formed using a wood form dead soft annealed copper and plastic
hammer a respectable /repeatable cone could be formed.W/o overlapping or double layers a simple butt joint with a slight amount of soldering.Ive
searched to near my limit and am not asking to be spoonfed i dont believe by the stds ive seen used on the forum.An honest question that I believe Ive
used due diligence in trying to answer myself and its not been a habit in fact i believe its my first request for info. regards.
[Edited on 28-4-2009 by grndpndr]
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nitro-genes
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After all this time I finally had the time to combine most of my shaped charge efforts into 1 single movie. 
For those interested:
http://www.easy-share.com/1908070830/Shaped charges by Nitro-genes.wmv
Cheers,
Nitro-genes
Edit: Copy paste entire url
[Edited on 9-10-2009 by nitro-genes]
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phantasy
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good job nitro-genes !
[Edited on 9-10-2009 by phantasy]
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497
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Very nice indeed! You beat us to it  NameWithheld and I were planning on
collaborating on a similar line of shaped charge experiments this winter, maybe putting them into a little video like that.
Hopefully we'll still get around to it. Probably scale things up a bit though. And maybe use some funner explosive fillers like cast this. Being comparable to pure HMX, it ought to work nicely. 
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nitro-genes
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Classic music and explosives are a great combination IMO...
Little under 400 kbar of pressure surely will produce some nice holes! What liners will u be using?
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497
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We haven't got the liners completely worked out yet. I do have access to small lathe, so we might try doing them like you did. Did you get an idea of
what the upper limits of copper thickness are using your technique?
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hissingnoise
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Could the 'perfect' liner be fabricated by electro-plating a machined resin cathode made conductive by graphiting?
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nitro-genes
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1 mm thick coppersheet could be worked relatively easily using several annealings and a 50 cm long shaping tool for leverage. Had the feeling though
it was about the limit of what the lathe could handle, which is only a very small one and not a real spinning lathe. With a larger lathe, steel
mandrel and enough leverage I think you could easily go 2mm+...
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hissingnoise
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Any increase in the size/weight of the penetrator will require an increase in weight of the charge. . .
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franklyn
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Dual Tandem Charge Array & Monroe effect tamping
Previuosly mentioned by me here _
http://www.sciencemadness.org/talk/viewthread.php?tid=10575&...
and by KemiRockarFett
http://www.sciencemadness.org/talk/viewthread.php?tid=10575&...
Tamping significantly improves penetration !
Glueing the charge to the inside bottom of a plastic jug
so it can be filled with water will work well.
It also provides protection from cast out fragments.
A technique for providing tamping without significant weight is to have two
layers of explosive separated by an air gap , in effect , a charge within a
charge. As the outer layer explodes it sets off the detonator at the apex of
the cone of the inner layer. The impact from standoff of the outer layer
reflects the detonation of the inner layer entirely in the direction of the liner.
See first Illustration attached below _
Also see abstract here _
Active Tamping Experiments
http://www.dtic.mil/srch/doc?collection=t3&id=ADA082061
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
The total force acting from an explosive is in exact proportion to the surface area
in contact. The surface area of a hollow cavity can be made larger by corrugating
or fluting the liner walls without having to increase the diameter of a charge. This
can readily be observed in a coffee percolator filter. The effect is to increase the
power delivered from a given charge for greater depth of penetration.
See second Illustration attached below
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Attaining greater penetration requires having two colinear charges fired in sequence.
The scheme outlined in the third attached sketch illustrates this idea. A conventional
conical shaped charge sets off and shoots through the central opening of a second
charge in front of it. The circumferential detonation wave of the first shaped charge
travels around an inert block ( cement ) to set off the next charge in front from the
outer rim which converges inward to the opening Position 1. The jet produced by the
first charge will have passed on through as the second charge is detonating , and the
two do not combine. Position 2 shows the liner blown out and curling into a cup shape.
The liner imediately around the center opening moves straight away in line with the
central axis indicated by two grey lines. The curvature out to the rim converges the
liner to a focal point.Position 3 The colapse continues to form a truncated hollow
based cone. Position 4 The projectile begins to take final form becoming elongated at
Position 5.
Shallow dish shaped charges ( Misznay-Schardin ) are initiated at the center and
detonate outward to the rim. See this image below.
http://www.sciencemadness.org/talk/files.php?pid=101497&...
It occured to someone how it might be if detonation started at the rim and converged
inward instead and so originated the EFP.
This is similar to the " Metal Storm " concept of packing rounds as a Roman Candle.
Sequential Jet Shaped Charge U.S. Patent 4004515
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
BASIC STUDIES OF THE LETHALITY OF SHAPED CHARGES - 1962
PART 1. PENETRATION DATA
http://handle.dtic.mil/100.2/AD329302
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD329302&Locatio...
Cute , shaped charges as detonators , has interesting X ray shots
Characterization of Jets From Exploding Bridge Wire Detonators
http://handle.dtic.mil/100.2/ADA433795
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA433795&Locati...
.
  
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franklyn
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Related to active tamping , drawing 1 above _
Report on U.S. Patent 5,847,312
Shaped Charge with Dual Confinement
http://handle.dtic.mil/100.2/ADA405843
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA405843&Locati...
Related to drawing 3 above _
Tandem Charge
http://www.ih.navy.mil/working_with_us/technology_transfer/p...
Read Explosively Formed Projectile (EFP) scroll down here _
http://www.globalsecurity.org/military/systems/munitions/bul...
U.S. Patent 5,565,644
Shaped Charge With Wave Shaping Lens
Below is a sketch including both design features in the same device ,
note that the liner can also be corrugated.
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grndpndr
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The last appears to be a fascinating combination of A dual CSC? accelerating an exotic efp.The penetrator appears to be formed to more the shape of an
old stye solid shot arty AP round.I dont qute understand the soft efp materials if kinetic energy were the main means penetration f the different
shapd EFPs.ut always a soft penetrator material ? Such as copper ,soft Iron ,mild steel, even for the long rod penetrator version of the EFP as well
as longer range aerodynamic finned mdels all made by dffering the geometry of the liner and explosive.The long rod efp one of just a few methods f
penetrating modern composite tank armor.lso fascinating are multiple efps from single devices capable of covering 360 degree degrees of Anti-armor
coverage.Multiple efps US 4649828/6606951
capable of off route use unlike static CSC'.
If a depeted uranium/Tungsten carbide type material coul be used for
EFPs a pssibility i think judging from experimenal work and almost an unbeatable warhead.
Thanks for the links to the other devices they appear fascinateing!
The war between the tank designer and the antitank device designer are alive n well!
[Edited on 22-10-2009 by grndpndr]
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Microtek
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Regarding that new nitrate ester, the one that is castable and has about the same detonating properties as HMX, I have worked with that as part of my
Masters dissertation. I can offer a few pointers on the synthesis of the precursor, and also reveal that the nitration gives similar yields with mixed
acids instead of the Ac2O/HNO3 system that the authors use.
I found the lack of a name to be annoying and so have given it the acronym NDBD (from the chemoffice generated name
2,3-bis(nitroxymethyl)-2,3-dinitrobutane-1,4-dinitrate).
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497
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Awesome! That was the one sticking point for me, not knowing whether mixed acid would work for the nitration. Thanks for clearing that up! I might try
a DCM moderated mixed acid nitration, and see if that gets better yields.
As far as the precursor goes, I'd love to hear what you have to say about it. I have a bunch of trishydroxymethyl nitromethane already (ironically, it
is easier to get than nitromethane itself), I was planning on ketalizing it with acetone using H2SO4 catalyst. Then basically following the literature
procedure, except for the final nitration step. I'd be interested in hearing any details you want to share.
Yes, the lack of name annoyed me too.. NDBD sounds good to me..
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Plasmapyrobattics
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Quote: Originally posted by Microtek  | Regarding that new nitrate ester, the one that is castable and has about the same detonating properties as HMX, I have worked with that as part of my
Masters dissertation. I can offer a few pointers on the synthesis of the precursor, and also reveal that the nitration gives similar yields with mixed
acids instead of the Ac2O/HNO3 system that the authors use.
I found the lack of a name to be annoying and so have given it the acronym NDBD (from the chemoffice generated name
2,3-bis(nitroxymethyl)-2,3-dinitrobutane-1,4-dinitrate). |
Excellent.
Is there perhaps an existing thread (or a link to a page) on this topic/material or can you perhaps open a new thread about it?
Thanks
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KemiRockarFett
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As Franklyns says, tamping results in more efficieny, this is related to the Newton second law: F=ma
Inertia increases with acceleration --> fast explosive = more inertia.
Another example: A 1 kg heavy weapon fires 1 gram projetile at 1000 m/s.
Impulse:
Mweap. V1 = Mbullet V2 ---> weapon recoil speed 1 m/s
Associated kinetic energy for bullet and weapon:
Weapon: 0.5 Nm
Bullet: 500 Nm
A lighter weapon --> more recoil and less energy into the bullet.
Think of this in analogy of just a bare explosive surrounding a metal cone compared to a similar situation but with the explosive surronded by a lot
of mass.
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hissingnoise
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I don't know if it's me or the fact that it's Monday morning---but I find none of the above comprehensible. . .
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grndpndr
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A lighter weapon has more recoil simply because the weapons lighter. It has no measurable effect on velocity.a lighter gun with the same lenghth bbl
fires the projecile at exacly the same velocity given the minor manufacturing differences between weapons/ammunition.All else being equal if it were
possible, weapon wieght has no effect on velocity in actual practice.
I do see what your trying to say but its a poor analogy chemically tamping High Explosives and firearms ballistics given the difference in
velocity of the 2.
A better example may be the recoilless rifle that uses a portion of the propellant gasses to act as countermass to the recoil of firing.
[Edited on 30-10-2009 by grndpndr]
[Edited on 30-10-2009 by grndpndr]
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nitro-genes
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About the dual shaped charge... (US5,223,666)
The design is more finicky than appears at first sight. The linerwall will only move at about half the speed compared to the detonation wave of the
explosive itself. Also, the mass of the gasses produced by the explosive is much less compared to the linerwall and thus will accelerate much faster.
This means that the gasses produced by the explosive willl imping on the jet formed by the first penetrator, effectively reducing its length and thus
its effectiveness. It is probably one of the reasons why subcalibration is always designed to be perpendicular to the linerwall and is known as the
"gasseous guillotine". Figure 9 in the patent you posted deals with this concept by adding a flyer plate to act as an "explosive clock".
Reference: --> http://www.dtic.mil/ndia/2002infantry/mcwilliams.pdf
About the explosive tamping...
Interesting read, though I seem to remember reading in FoSC that tamping is only increasing effectiveness of the shaped charge at large standoff
distances, and only marginal. The results of the computer simulations in the PDF you linked to seem to confirm this. Their goal was more to decrease
the amount of explosive needed, while maintaining jettip velocities. The linerwall is accellerating too fast probably to really benefit from the
compression wave reflected by the casing, hence detonation pressure is the most important factor.
[Edited on 30-10-2009 by nitro-genes]
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franklyn
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Determining the kinematic flow of an explosive train is quite a task, only
practicable by computer simulation using numerical finite element analysis (FEA).
Some examples are linked here in a previous post _
http://www.sciencemadness.org/talk/viewthread.php?tid=10575&...
In a virtual setting one can alter the parameters at will to observe and achieve a
desired end. In a tandem charge arrangement each charge would be optimized
individually , then both would be interfaced and combined into one sequence with
the objective of avoiding interference that will degrade performance.
A detonation wave traveling along the periphery of a cylinder in the axial direction
can be delayed by using an explosive having lower velocity of detonation mixed
with aggregate to slow detonation even more. Say perhaps from 8.4 km/s down to 5 ,
then ( 5 / 8.4 ) = 0.6.
Arrival of the wave can be delayed further by elongating the explosive's continuity
in a sinuous or zig zag path. Down to 0.7 for a rounded meander to 0.5 for a square
Castellated form. See attached.
Using combined techniques , 0.6 times 0.5 reduces the wave transit time to 0.3 .
This is in a range where it can see useful application in design of an explosive train.
* Note in this depiction http://www.feainformation.com/avilib/67.avi
the slug at the rear will have protruded into the subsequent converging concentric
detonation of the EFP ahead. I have assumed no interaction or that they may blend.
Without considering the hydrodynamic challenges , it appears that in such case ,
the combined effect would be to enhance the pre-jet.
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LabRatNW
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Thermite shaping...
I was trying to figure out a way to make solid and flexible thermite charges. I thought about adding corn syrup, but that may just make the thermite
highly explosive...
I've also had some wild ideas (do forgive me) about mixing thermite (Al/Fe3O4) into rocket candy for exactly that purpose. Any
experienced/knowledgeable types tried this?
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hissingnoise
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Look LabRatNW, it's now plainly obvious that you know next-to-nothing about explosives; instead of making laughable posts, why not get yourself some
little information on the subject, to start.
No one here is going to attempt to teach you the many complexities of energetic materials from scratch. . .
And thermite isn't explosive in the accepted sense---the highly exothermic metathetical reaction produces iron and the oxide of Al.
There is no evolution of gasses or blast effect.
[Edited on 31-10-2009 by hissingnoise]
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carbonfeind
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Yesterday I fired a micro shaped charge. It was about 2 grams of hexamine diperchlorate with a conical aluminum liner made from a soda can. I have a
video I got of it as well. link Enjoy! Edit: primary was a tad less than .5 grams of silver acetylide picrate.
[Edited on 5-11-2009 by carbonfeind]
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LabRatNW
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metathetical. LOL.
| Quote: Originally posted by hissingnoise | Look LabRatNW, it's now plainly obvious that you know next-to-nothing about explosives; instead of making laughable posts, why not get yourself some
little information on the subject, to start.
No one here is going to attempt to teach you the many complexities of energetic materials from scratch. . .
And thermite isn't explosive in the accepted sense---the highly exothermic metathetical reaction produces iron and the oxide of Al.
There is no evolution of gasses or blast effect. |
Really? I had no idea that thermite wasn't explosive! Thanks for the useful advice and pointers. The entire board is now better for you having
explained that to me.
Adding an easily oxidizable, rapid-burning, gas-producing fuel (sugar, anyone?) to the thermite mixture however, may cause an explosion (or
near-explosive reaction). Especially at the temperatures that thermite reacts... hence the 'may make thermite explosive' comment. I never said
thermite was explosive to begin with. You just assumed I thought that because you didn't read what I said carefully.
My idea wouldn't be a "charge" in the traditional theme of explosives. It would be a shaped unit of thermite for a purpose. Thermite tape to weld two
things together that have some significant length, or a cylinder to carry quantifiable units around easily rather than having to muck about with
powder.
Any idiot can find the following information:
3(Fe3O4) + 8Al -> 4(Al2O3) + 9Fe
dH = approx 3.32 MJ/Equiv. (that's Megajoules)
The ratio of iron oxide would most definitely have to be tweaked to compensate for the sugar gobbling up some of the available oxygen. I'm actually
worried about the explosion that may be created because I don't want to have globs of hot thermite showering my neighborhood.
For the record, I personally know Dr. H. Laine Berghout who did several years of research at China Lake with energetic materials. I'm on a first-name
basis with him. So if I need some explanation on the basics of energetic materials, I have a good source, thanks.
btw: Correct terminology is "metathesis-type reaction"
[Edited on 11-10-2009 by LabRatNW]
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hissingnoise
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I never thought I'd say this to anyone on the board but I'm sorry I responded to any of your posts in the first place. . .
I know you're not going to make an explosive, so stop reading about them. . .
Do something else---anything!
[Edited on 10-11-2009 by hissingnoise]
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