megalomania
May 24th, 2003, 02:45 PM
outsider
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Posts: 91
From:
Registered: FEB 2001
posted 03-18-2001 03:16 PM
--------------------------------------------------------------------------------
Does anyone have any suggestions for making a FLSC? Because the frame shaped charge I made out of P.E. tube (12mm) filled with NM explosive isn't gonna work. As mentioned earlier (see "NM explosive" in H.E. section and "shaped charges" in Improvised Weapons section) it produces only a dent in mild steel (3-4mm) while the tube contained 150 gram of explosive per meter. I still don't know if it caused by the lowered VoD (because of the low confiment/amount) or just because of too little amount. What I do know is that a tube is very inefficient because the power is not directed (it can be compaired with det. cord which probably has the same dissappointing results, I think but someone still has to tell me). So putting it in a case would improve it because the power gets directed to the surface it's put on. Adding a V-shaped cavity would be a further improvement. And using a metal liner would produce the maximum result. So I think it's not the NM explosive I use which is to blame for the disappointing results. It's just the way I used it. Making a FLSC would probably get good results.
I know FLSCs consisting of 150 gram PETN per meter can cut through mild steel of 10 mm. So I want to know if anyone has any suggestions improvising them. The only thing is: I use a NM based explosive so the whole construction must be airtight.
[This message has been edited by outsider (edited March 18, 2001).]
c0deblue
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Posts: 229
From:
Registered: JAN 2001
posted 03-19-2001 12:20 AM
--------------------------------------------------------------------------------
I'm no expert on this, but I think your conclusions are correct concerning the inefficiency of a tubular contact charge. It's well known that the small diameter of PETN detonating cord makes it a poor choice as a stand-alone charge, so I think a 12mm cross-section of NM explosive might be a little anemic.
The "Breaching Charges" file on NBK's site bears careful viewing as it shows clearly that the Hydrocut-designed frames embody the two elements essential to a successful FLSC: (a) A nominal inertial counter to the explosive mass, and (b) a cavity providing the correct geometry to support the charge at the optimal "V" angle and standoff distance. In this system, the charge is customized to the task at hand using a more or less universal frame.
While such a frame could be constructed using angle iron, the shrapnel produced would be unacceptable - the Hydrocut frames are designed to pulverize without producing shrapnel. How about using a frame fabricated from a high-weight low-density material such as homesote or gypsum? This could either be cast using angle iron as a mold, or glued up from strips of homesote or gypsum wallboard reinforced with gauze glued on all surfaces. This should provide the necessary inertial mass while disintegrating almost to dust on detonation.
It's not certain that an NM explosive would work against concrete or steel due to the lower VoD (relative to the plastic explosives used in the Hydrocut system), but it's certainly worth a try. A gypsum frame prototype could be made using only scraps from a construction site, a sheetrock knife and some glue.
[This message has been edited by c0deblue (edited March 19, 2001).]
outsider
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From:
Registered: FEB 2001
posted 03-19-2001 08:42 AM
--------------------------------------------------------------------------------
Thanks for the suggestion. I've seen the file "breaching charges" of NBK2000 but the part where they actually construct the device was to short to see how they did it. I just saw them glueing somekind of tape to the frame and that was it. But the thing what amased me was that when they used the frame shaped devices at one time there were people standing in front of it! So like you mention it must apperently produce no shrapnel, it's just blown to dust. But at the same time the frame must act as a countermass for the explosive (or maybe in this particular case a countermass was not used). That hydrocut uses water as a countermass I should have known (in the thread "effect H.E. on safety glass" I say it produces a kind of waterjet which is kind of a dumb thing to say).
The suggestion of using gympsum wallboard for constructing the frame is a good one. Because it's indeed heavy but it crumbles easy when broken (or exploded). So this should minimalize dangerous shrapnel flying around which is an important thing for the frame shaped charges I want to make. The only disadvantage is how I can use it for the volatile NM explosive. By the way, NM explosives (almost any type) have a high VoD. The ANNM explosive for example has A VoD somewhere between TNT and RDX/PETN so I think it's effective for frame shaped charges.
[This message has been edited by outsider (edited March 19, 2001).]
Microtek
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From:
Registered: JAN 2001
posted 03-19-2001 10:02 AM
--------------------------------------------------------------------------------
On a slightly different note, does anyone know the composition of sheet explosive ?
I know that PETN is the explosive ingredient, but I read in an army field-manual that sheet explosive is a
"PETN/nitrocellulose composite", so I was wondering how you would go about making it pliable without acetone or something else that will evaporate.
c0deblue
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Posts: 229
From:
Registered: JAN 2001
posted 03-19-2001 01:20 PM
--------------------------------------------------------------------------------
The fact that it's liquid does complicate things. How about using a larger diameter PE tube flattened (before filling) between steel rollers. If done under heat the reconfiguration would be permanent. This would provide a more favorable (flatter) cross-section while maintaining the desired charge weight per foot. It's possible too that a PE (or other inert material) extrusion of the ideal cross-section might already be in production somewhere (for use as a door gasket or some such).
Microtek: Most of the "recipes" I've seen call for some sort of gum as a binder. I guess the only requirement would be that the material be chemically inert so as not to react with the explosive. Has anyone tried using the flexible caulking products used in the electrical trade for sealing conduits and raceways? These are about the consistency of modeling clay and designed to stay malleable for years. Thinning with the right quantity (and type) of oil would allow the desired consistency to be maintained even with high explosive to binder ratios.
For that matter, has anyone tried plain old butyl caulking compound? Or (aluminum-rich) rain gutter seal?
[This message has been edited by c0deblue (edited March 19, 2001).]
outsider
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Posts: 91
From:
Registered: FEB 2001
posted 03-19-2001 01:32 PM
--------------------------------------------------------------------------------
All the sheet explosives I've heard of consist of PETN and some plasticizer. Dupont produces "detasheet A" and the military use "flex-x" or "detasheet B" (the first one consists of 85% PETN with a binder and flex-x consist of only 63% PETN). The sheet the military uses is also called M118 or M186 (the first is 0.25 " thick 3" wide and 12 " long the M186 has the same width and thickness but is a roll of 50 foot long. The colour is olive green (suprisingly) and the commercial ones can have different colour and are sometimes made of RDX instead of PETN) Of course sheet explosives are the best for making frame shaped charges but I don't have 'em and Dupont won't sell it to me so.... I use homemade explosives. And NM is a very good one.
Back to the topic again: as stated to produce an effective FLSC you need to use a countermass. And it's better to use material that's heavy but easily broken so no shrapnel is produced. Now, gypsum wallboard was mentioned which is a good suggestion. But I was just thinking about using sand to fill up the casing in which the explosive and metal liner is put. May be even wet sand. And the casing would be of some kind of paper or plastic. Wet sand is heavy and acts as a good countermass while after the explosion it's just sandgrains flying around. And it's easier to make than something like the Hydrocut device which is filled with water.
By the way in the hardware store they sell different kinds of "profiles" made of different materials (iron, brass, plastic, wood). I've seen a nice profile made of brass: 90 degree angle; each side 10 mm; and 1 mm thick. Fits nice in between the two tubes and if I put it in a some paper casing filled with sand it should be a nice FLSC (or not?). Shaping a thicker tube is also a good idea. Thanks c0deblue.
[This message has been edited by outsider (edited March 20, 2001).]
Microtek
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Posts: 205
From:
Registered: JAN 2001
posted 03-19-2001 04:33 PM
--------------------------------------------------------------------------------
Hmm.. I'm sorry to sidetrack your string a little bit but actually my point was that when making plastique, finding a binder that will hold a high percentage of explosive without crumbling is quite difficult.
If NC could be used ( and be so good as to be employed by the military ), then not only would you have an easily obtainable binder, but also one that contributed to the energy.
So it was a query of my own rather than a suggestion for you.
c0deblue
Frequent Poster
Posts: 229
From:
Registered: JAN 2001
posted 03-19-2001 11:34 PM
--------------------------------------------------------------------------------
This isn't overly detailed, but may be useful nonetheless:
"Composition C contained 88.3 percent RDX and 11.7 of a nonexplosive oily plasticizer.
Composition C was replaced by C-2, which contained 80 percent RDX and 20 percent explosive plasticizer. This explosive plasticizer was composed of mononitrotoluene.
C-2 was replaced by C-3, which contains 77% (+/- 2%) RDX and 23% (+/- 2%) explosive plasticizer.
C-3 has been replaced by C-4 because of its hardening, volatility, and its hygroscopicity. C-4 contains, RDX, Polyisobutylene, Motor Oil, and Di (2-ethylhexyl) sebacate."
nbk2000
Moderator
Posts: 1096
From: Guess
Registered: SEP 2000
posted 03-20-2001 07:29 AM
--------------------------------------------------------------------------------
The hydrocut frames contain no water, just polyethylene plastic. It's simply the mass of the frame that provides the needed resistance for the explosive forrce to do its work before blowing apart into harmless bits.
I've seen info on opposing explosive strips cutting by shockwave collison, but the explosive needs to be in a ribbon (wide and flat) shape. Round tubes would probably be much less effective.
Liquid explosives are unsuitable for FLSCs, that's why it's not used in military devices. Since you have NM, why not make a plastique instead, which would be much easier to form into the proper shape?
------------------
"The knowledge that they fear is a weapon to be used against them"
Go here to download the NBK2000 website PDF.
Go here to download the NBK2000 videos.
outsider
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Posts: 91
From:
Registered: FEB 2001
posted 03-20-2001 10:58 AM
--------------------------------------------------------------------------------
Are you sure "hydrocut" uses no water? I've seen a picture of a frame shaped "hydro-cut" device and it was pretty big. Cross section would at least be 10 cm by 5 cm. And there where holes to put somekind of liquid in. And somewhere else it was mentioned to watch out for leakage. And why they call it hydrocut anyway? And P.E. alone would not be enough countermass I think. But I'm not sure and I seem to be unable to get through to the "hydrocut" site.
But anyway to use water (or wet sand) as a counter mass would be a good idea don't you think?
And that liquid explosives are not used for frame shaped charges/FLSC is probably because it's not practical. Sheet or plastic explosives are a lot more easy to use. But as long as the VoD (and power) of the liquid explosive is high enough I see no reason why it can't be used. It should also produce a liquid metal jet out of the metal liner of the V-shaped cavity and thereby producing a progressive cutting force along the linear charge. And liquid NM explosives are in general very powerful and with high VoD. Some exceed the power and VoD of TNT.
And making plastique with NM is a solution but then you need another chemical: ammoniumnitrate. And that's a bit more trouble making it, drying it and protecting it from moisture.And still you end up with a plastique with the water attracting AN and volatile NM. So my bet is on the gelled NM explosives. I just have to find solutions for the practical problems it raises.
Microtek
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Posts: 205
From:
Registered: JAN 2001
posted 03-21-2001 10:11 AM
--------------------------------------------------------------------------------
...Which was exactly my point in asking about gelling nitrocellulose.
The only difference is that I would use a crystalline explosive, so I need something else for gelling the NC, preferably something that wouldn't evaporate and isn't poisonous. So you see, my question is related to FLSC manufacture.
c0deblue
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Posts: 229
From:
Registered: JAN 2001
posted 03-21-2001 11:52 PM
--------------------------------------------------------------------------------
A possible solution:
Polyethylene sheet fuses extremely well to heated metal surfaces, and this fact could be exploited to fabricate a linear charge "vessel" capable of holding liquid explosives while maintaining a more desireable cross-section.
Beginning with a piece of copper (or brass) angle heated to the correct fusing temperature, both edges of a strip of *heavy* polyethylene or other plastic (what is the plastic used for IV bags?) could be fused to the metal angle such that it formed a C-shaped "bag" surrounding the angle's outside surfaces. Sealed at the ends (or assembled as a continuous frame shape), this system would provide the ideal flat-surfaced V-shape critical to "blade-jet" formation. The profile could be improved further by backing the "bag" surfaces up with a (gypsum?) frame of the type previously discussed. The correct standoff distance could be achieved by forming the angle from copper flashing with an extra "leg" on either side.
Sort of like this:
./\
|..| (ignore the dots) The poly plastic would be fused to the two vertical legs.
An alternative might be to heatseal a sleeve (bladder) of poly and sandwich the filled bladder between the liner and outer frame. This would provide the ideal shape by conforming to the frame and liner surfaces without the tricky business of fusing the poly to metal surfaces.
[This message has been edited by c0deblue (edited March 22, 2001).]
outsider
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Posts: 91
From:
Registered: FEB 2001
posted 03-22-2001 06:26 AM
--------------------------------------------------------------------------------
OK, thanks for the info. That's the kind of replies that I want; they answer my question and are useful.
shady mutha
Frequent Poster
Posts: 149
From: australia
Registered: SEP 2000
posted 04-03-2001 04:34 AM
--------------------------------------------------------------------------------
Although the final geometries of the linear explosives may vary,they all generally start out as a metal tube(or sheath),e.g.lead,aluminum,silver,or copper of some manageable length,approximately 10 feet,and an outside diameter between 0.38 and 0.75 inches(1 and 2 centimeters),whose inside diameter is approximately 50% of the outside diameter.One end of the tube is capped and the tube is incrementally packed,under high pressure,with a granular high explosive such as PETN RDX,or HNS.After the tube has been completely filled and capped,it is subjected to a drawing process that may include reduction dies and many proprietary processes and procedures that are,understandably,selfishly guarded.The unit used to define the quanity of explosive per given length(core loading)are the grains per foot method.The dominant core loadings are between 2 and 500 grains per foot,although for special application they have been drawn as low as 0.2 grain per foot and as large as 2000 grains per foot.
Frequent Poster
Posts: 91
From:
Registered: FEB 2001
posted 03-18-2001 03:16 PM
--------------------------------------------------------------------------------
Does anyone have any suggestions for making a FLSC? Because the frame shaped charge I made out of P.E. tube (12mm) filled with NM explosive isn't gonna work. As mentioned earlier (see "NM explosive" in H.E. section and "shaped charges" in Improvised Weapons section) it produces only a dent in mild steel (3-4mm) while the tube contained 150 gram of explosive per meter. I still don't know if it caused by the lowered VoD (because of the low confiment/amount) or just because of too little amount. What I do know is that a tube is very inefficient because the power is not directed (it can be compaired with det. cord which probably has the same dissappointing results, I think but someone still has to tell me). So putting it in a case would improve it because the power gets directed to the surface it's put on. Adding a V-shaped cavity would be a further improvement. And using a metal liner would produce the maximum result. So I think it's not the NM explosive I use which is to blame for the disappointing results. It's just the way I used it. Making a FLSC would probably get good results.
I know FLSCs consisting of 150 gram PETN per meter can cut through mild steel of 10 mm. So I want to know if anyone has any suggestions improvising them. The only thing is: I use a NM based explosive so the whole construction must be airtight.
[This message has been edited by outsider (edited March 18, 2001).]
c0deblue
Frequent Poster
Posts: 229
From:
Registered: JAN 2001
posted 03-19-2001 12:20 AM
--------------------------------------------------------------------------------
I'm no expert on this, but I think your conclusions are correct concerning the inefficiency of a tubular contact charge. It's well known that the small diameter of PETN detonating cord makes it a poor choice as a stand-alone charge, so I think a 12mm cross-section of NM explosive might be a little anemic.
The "Breaching Charges" file on NBK's site bears careful viewing as it shows clearly that the Hydrocut-designed frames embody the two elements essential to a successful FLSC: (a) A nominal inertial counter to the explosive mass, and (b) a cavity providing the correct geometry to support the charge at the optimal "V" angle and standoff distance. In this system, the charge is customized to the task at hand using a more or less universal frame.
While such a frame could be constructed using angle iron, the shrapnel produced would be unacceptable - the Hydrocut frames are designed to pulverize without producing shrapnel. How about using a frame fabricated from a high-weight low-density material such as homesote or gypsum? This could either be cast using angle iron as a mold, or glued up from strips of homesote or gypsum wallboard reinforced with gauze glued on all surfaces. This should provide the necessary inertial mass while disintegrating almost to dust on detonation.
It's not certain that an NM explosive would work against concrete or steel due to the lower VoD (relative to the plastic explosives used in the Hydrocut system), but it's certainly worth a try. A gypsum frame prototype could be made using only scraps from a construction site, a sheetrock knife and some glue.
[This message has been edited by c0deblue (edited March 19, 2001).]
outsider
Frequent Poster
Posts: 91
From:
Registered: FEB 2001
posted 03-19-2001 08:42 AM
--------------------------------------------------------------------------------
Thanks for the suggestion. I've seen the file "breaching charges" of NBK2000 but the part where they actually construct the device was to short to see how they did it. I just saw them glueing somekind of tape to the frame and that was it. But the thing what amased me was that when they used the frame shaped devices at one time there were people standing in front of it! So like you mention it must apperently produce no shrapnel, it's just blown to dust. But at the same time the frame must act as a countermass for the explosive (or maybe in this particular case a countermass was not used). That hydrocut uses water as a countermass I should have known (in the thread "effect H.E. on safety glass" I say it produces a kind of waterjet which is kind of a dumb thing to say).
The suggestion of using gympsum wallboard for constructing the frame is a good one. Because it's indeed heavy but it crumbles easy when broken (or exploded). So this should minimalize dangerous shrapnel flying around which is an important thing for the frame shaped charges I want to make. The only disadvantage is how I can use it for the volatile NM explosive. By the way, NM explosives (almost any type) have a high VoD. The ANNM explosive for example has A VoD somewhere between TNT and RDX/PETN so I think it's effective for frame shaped charges.
[This message has been edited by outsider (edited March 19, 2001).]
Microtek
Frequent Poster
Posts: 205
From:
Registered: JAN 2001
posted 03-19-2001 10:02 AM
--------------------------------------------------------------------------------
On a slightly different note, does anyone know the composition of sheet explosive ?
I know that PETN is the explosive ingredient, but I read in an army field-manual that sheet explosive is a
"PETN/nitrocellulose composite", so I was wondering how you would go about making it pliable without acetone or something else that will evaporate.
c0deblue
Frequent Poster
Posts: 229
From:
Registered: JAN 2001
posted 03-19-2001 01:20 PM
--------------------------------------------------------------------------------
The fact that it's liquid does complicate things. How about using a larger diameter PE tube flattened (before filling) between steel rollers. If done under heat the reconfiguration would be permanent. This would provide a more favorable (flatter) cross-section while maintaining the desired charge weight per foot. It's possible too that a PE (or other inert material) extrusion of the ideal cross-section might already be in production somewhere (for use as a door gasket or some such).
Microtek: Most of the "recipes" I've seen call for some sort of gum as a binder. I guess the only requirement would be that the material be chemically inert so as not to react with the explosive. Has anyone tried using the flexible caulking products used in the electrical trade for sealing conduits and raceways? These are about the consistency of modeling clay and designed to stay malleable for years. Thinning with the right quantity (and type) of oil would allow the desired consistency to be maintained even with high explosive to binder ratios.
For that matter, has anyone tried plain old butyl caulking compound? Or (aluminum-rich) rain gutter seal?
[This message has been edited by c0deblue (edited March 19, 2001).]
outsider
Frequent Poster
Posts: 91
From:
Registered: FEB 2001
posted 03-19-2001 01:32 PM
--------------------------------------------------------------------------------
All the sheet explosives I've heard of consist of PETN and some plasticizer. Dupont produces "detasheet A" and the military use "flex-x" or "detasheet B" (the first one consists of 85% PETN with a binder and flex-x consist of only 63% PETN). The sheet the military uses is also called M118 or M186 (the first is 0.25 " thick 3" wide and 12 " long the M186 has the same width and thickness but is a roll of 50 foot long. The colour is olive green (suprisingly) and the commercial ones can have different colour and are sometimes made of RDX instead of PETN) Of course sheet explosives are the best for making frame shaped charges but I don't have 'em and Dupont won't sell it to me so.... I use homemade explosives. And NM is a very good one.
Back to the topic again: as stated to produce an effective FLSC you need to use a countermass. And it's better to use material that's heavy but easily broken so no shrapnel is produced. Now, gypsum wallboard was mentioned which is a good suggestion. But I was just thinking about using sand to fill up the casing in which the explosive and metal liner is put. May be even wet sand. And the casing would be of some kind of paper or plastic. Wet sand is heavy and acts as a good countermass while after the explosion it's just sandgrains flying around. And it's easier to make than something like the Hydrocut device which is filled with water.
By the way in the hardware store they sell different kinds of "profiles" made of different materials (iron, brass, plastic, wood). I've seen a nice profile made of brass: 90 degree angle; each side 10 mm; and 1 mm thick. Fits nice in between the two tubes and if I put it in a some paper casing filled with sand it should be a nice FLSC (or not?). Shaping a thicker tube is also a good idea. Thanks c0deblue.
[This message has been edited by outsider (edited March 20, 2001).]
Microtek
Frequent Poster
Posts: 205
From:
Registered: JAN 2001
posted 03-19-2001 04:33 PM
--------------------------------------------------------------------------------
Hmm.. I'm sorry to sidetrack your string a little bit but actually my point was that when making plastique, finding a binder that will hold a high percentage of explosive without crumbling is quite difficult.
If NC could be used ( and be so good as to be employed by the military ), then not only would you have an easily obtainable binder, but also one that contributed to the energy.
So it was a query of my own rather than a suggestion for you.
c0deblue
Frequent Poster
Posts: 229
From:
Registered: JAN 2001
posted 03-19-2001 11:34 PM
--------------------------------------------------------------------------------
This isn't overly detailed, but may be useful nonetheless:
"Composition C contained 88.3 percent RDX and 11.7 of a nonexplosive oily plasticizer.
Composition C was replaced by C-2, which contained 80 percent RDX and 20 percent explosive plasticizer. This explosive plasticizer was composed of mononitrotoluene.
C-2 was replaced by C-3, which contains 77% (+/- 2%) RDX and 23% (+/- 2%) explosive plasticizer.
C-3 has been replaced by C-4 because of its hardening, volatility, and its hygroscopicity. C-4 contains, RDX, Polyisobutylene, Motor Oil, and Di (2-ethylhexyl) sebacate."
nbk2000
Moderator
Posts: 1096
From: Guess
Registered: SEP 2000
posted 03-20-2001 07:29 AM
--------------------------------------------------------------------------------
The hydrocut frames contain no water, just polyethylene plastic. It's simply the mass of the frame that provides the needed resistance for the explosive forrce to do its work before blowing apart into harmless bits.
I've seen info on opposing explosive strips cutting by shockwave collison, but the explosive needs to be in a ribbon (wide and flat) shape. Round tubes would probably be much less effective.
Liquid explosives are unsuitable for FLSCs, that's why it's not used in military devices. Since you have NM, why not make a plastique instead, which would be much easier to form into the proper shape?
------------------
"The knowledge that they fear is a weapon to be used against them"
Go here to download the NBK2000 website PDF.
Go here to download the NBK2000 videos.
outsider
Frequent Poster
Posts: 91
From:
Registered: FEB 2001
posted 03-20-2001 10:58 AM
--------------------------------------------------------------------------------
Are you sure "hydrocut" uses no water? I've seen a picture of a frame shaped "hydro-cut" device and it was pretty big. Cross section would at least be 10 cm by 5 cm. And there where holes to put somekind of liquid in. And somewhere else it was mentioned to watch out for leakage. And why they call it hydrocut anyway? And P.E. alone would not be enough countermass I think. But I'm not sure and I seem to be unable to get through to the "hydrocut" site.
But anyway to use water (or wet sand) as a counter mass would be a good idea don't you think?
And that liquid explosives are not used for frame shaped charges/FLSC is probably because it's not practical. Sheet or plastic explosives are a lot more easy to use. But as long as the VoD (and power) of the liquid explosive is high enough I see no reason why it can't be used. It should also produce a liquid metal jet out of the metal liner of the V-shaped cavity and thereby producing a progressive cutting force along the linear charge. And liquid NM explosives are in general very powerful and with high VoD. Some exceed the power and VoD of TNT.
And making plastique with NM is a solution but then you need another chemical: ammoniumnitrate. And that's a bit more trouble making it, drying it and protecting it from moisture.And still you end up with a plastique with the water attracting AN and volatile NM. So my bet is on the gelled NM explosives. I just have to find solutions for the practical problems it raises.
Microtek
Frequent Poster
Posts: 205
From:
Registered: JAN 2001
posted 03-21-2001 10:11 AM
--------------------------------------------------------------------------------
...Which was exactly my point in asking about gelling nitrocellulose.
The only difference is that I would use a crystalline explosive, so I need something else for gelling the NC, preferably something that wouldn't evaporate and isn't poisonous. So you see, my question is related to FLSC manufacture.
c0deblue
Frequent Poster
Posts: 229
From:
Registered: JAN 2001
posted 03-21-2001 11:52 PM
--------------------------------------------------------------------------------
A possible solution:
Polyethylene sheet fuses extremely well to heated metal surfaces, and this fact could be exploited to fabricate a linear charge "vessel" capable of holding liquid explosives while maintaining a more desireable cross-section.
Beginning with a piece of copper (or brass) angle heated to the correct fusing temperature, both edges of a strip of *heavy* polyethylene or other plastic (what is the plastic used for IV bags?) could be fused to the metal angle such that it formed a C-shaped "bag" surrounding the angle's outside surfaces. Sealed at the ends (or assembled as a continuous frame shape), this system would provide the ideal flat-surfaced V-shape critical to "blade-jet" formation. The profile could be improved further by backing the "bag" surfaces up with a (gypsum?) frame of the type previously discussed. The correct standoff distance could be achieved by forming the angle from copper flashing with an extra "leg" on either side.
Sort of like this:
./\
|..| (ignore the dots) The poly plastic would be fused to the two vertical legs.
An alternative might be to heatseal a sleeve (bladder) of poly and sandwich the filled bladder between the liner and outer frame. This would provide the ideal shape by conforming to the frame and liner surfaces without the tricky business of fusing the poly to metal surfaces.
[This message has been edited by c0deblue (edited March 22, 2001).]
outsider
Frequent Poster
Posts: 91
From:
Registered: FEB 2001
posted 03-22-2001 06:26 AM
--------------------------------------------------------------------------------
OK, thanks for the info. That's the kind of replies that I want; they answer my question and are useful.
shady mutha
Frequent Poster
Posts: 149
From: australia
Registered: SEP 2000
posted 04-03-2001 04:34 AM
--------------------------------------------------------------------------------
Although the final geometries of the linear explosives may vary,they all generally start out as a metal tube(or sheath),e.g.lead,aluminum,silver,or copper of some manageable length,approximately 10 feet,and an outside diameter between 0.38 and 0.75 inches(1 and 2 centimeters),whose inside diameter is approximately 50% of the outside diameter.One end of the tube is capped and the tube is incrementally packed,under high pressure,with a granular high explosive such as PETN RDX,or HNS.After the tube has been completely filled and capped,it is subjected to a drawing process that may include reduction dies and many proprietary processes and procedures that are,understandably,selfishly guarded.The unit used to define the quanity of explosive per given length(core loading)are the grains per foot method.The dominant core loadings are between 2 and 500 grains per foot,although for special application they have been drawn as low as 0.2 grain per foot and as large as 2000 grains per foot.