nbk2000
August 14th, 2007, 01:10 AM
(BTW, I realize I misspelled planar in the GIF. I'll correct it later)
Large EFP's are complicated to make because of the requirement of spinning the platters, which are made of thick metal and thus requiring a hydraulic press or lathe - things most people don't have handy.
:(
But I had the thought that, if you made the design of an EFP a two-dimensional problem, instead of a three-dimensional one, you'd greatly simplify the design problem, as all your charge dimensions can now be 2D linear instead of 3D circular.
:)
To wit, the attached animated GIF (to scale for an X-charge).
Gray=Steel, Green=Plastic, Yellow=Explosive, Orange=liner, Black=Bolts, Blue=Detonator
Two flat steel plates sandwich another plate, made of plastic, which serves as the confinement/waveformer for the explosive charge, with a curved strip of copper/steel/aluminum serving as the EFP platter.
The EFP strip is a flat strip of the appropriate metal bent to the appropriate curvature and held in place by the plastic former, and resting against two steel reinforcing bolts, which provide the necessary resistance to the strip to cause it to invert into the required shape under explosive loading.
Other reinforcing bolts support the plastic against explosive expansion, long enough to direct the majority of the explosives power against the EFP strip, rather than blowing out the side.
Since an EFP's effective range is a function of it's size (mass, actually), this design allows for greatly increased range since you can make it much larger than a home-spun EFP, as the simplicity of the design allows such.
Also, larger sizes mean less precision is required as regardstolerances, as EFP's small enough to be home spun are very sensitive to any design flaws, especially in the platter itself.
As an example:
Assuming a requirement of a platter thickness of 1-2% of charge diameter (width, in this case), a 1/8th thick strip would mean a charge width of (12.5"@1%, 6.25" @2%), so we'll use 8" as an average for simplicity.
At 1/8x1"x9", that strip will weigh (assuming steel) 5.1 ounces, or 5.8 ounces for copper.
That 9" strip, when bent to fit in an 8" slot, will have a curve to it that brings it almost about .7" in.
At 8", and typical EFP effective range of 100x CD, that makes for up to a 66' range. :)
(Though EFP's can have up to 1,000x CD, I'm being very conservative.)
An SC version (such as the GIF) would still punch a hole, but an EFP version would not, as the hole created by a round platter would, by the nature of this version, also have to be a 2D segment, thus a slot.
This design is by no means optimized for materials or anything else, so don't hold me to anything, but I think there's much to recommend this idea.
One thing would be the fact that it's flat. That makes it easy to fit in places that a round charge of similar size wouldn't. A small one could be disguised inside of a magazine or book cover. :)
Other places would be attached to walls, behind road signs, on roads, on top of/underneath vehicles (parked or otherwise), in the expansion gaps of bridges to attack vehicles from underneath, and many other places.
Large EFP's are complicated to make because of the requirement of spinning the platters, which are made of thick metal and thus requiring a hydraulic press or lathe - things most people don't have handy.
:(
But I had the thought that, if you made the design of an EFP a two-dimensional problem, instead of a three-dimensional one, you'd greatly simplify the design problem, as all your charge dimensions can now be 2D linear instead of 3D circular.
:)
To wit, the attached animated GIF (to scale for an X-charge).
Gray=Steel, Green=Plastic, Yellow=Explosive, Orange=liner, Black=Bolts, Blue=Detonator
Two flat steel plates sandwich another plate, made of plastic, which serves as the confinement/waveformer for the explosive charge, with a curved strip of copper/steel/aluminum serving as the EFP platter.
The EFP strip is a flat strip of the appropriate metal bent to the appropriate curvature and held in place by the plastic former, and resting against two steel reinforcing bolts, which provide the necessary resistance to the strip to cause it to invert into the required shape under explosive loading.
Other reinforcing bolts support the plastic against explosive expansion, long enough to direct the majority of the explosives power against the EFP strip, rather than blowing out the side.
Since an EFP's effective range is a function of it's size (mass, actually), this design allows for greatly increased range since you can make it much larger than a home-spun EFP, as the simplicity of the design allows such.
Also, larger sizes mean less precision is required as regardstolerances, as EFP's small enough to be home spun are very sensitive to any design flaws, especially in the platter itself.
As an example:
Assuming a requirement of a platter thickness of 1-2% of charge diameter (width, in this case), a 1/8th thick strip would mean a charge width of (12.5"@1%, 6.25" @2%), so we'll use 8" as an average for simplicity.
At 1/8x1"x9", that strip will weigh (assuming steel) 5.1 ounces, or 5.8 ounces for copper.
That 9" strip, when bent to fit in an 8" slot, will have a curve to it that brings it almost about .7" in.
At 8", and typical EFP effective range of 100x CD, that makes for up to a 66' range. :)
(Though EFP's can have up to 1,000x CD, I'm being very conservative.)
An SC version (such as the GIF) would still punch a hole, but an EFP version would not, as the hole created by a round platter would, by the nature of this version, also have to be a 2D segment, thus a slot.
This design is by no means optimized for materials or anything else, so don't hold me to anything, but I think there's much to recommend this idea.
One thing would be the fact that it's flat. That makes it easy to fit in places that a round charge of similar size wouldn't. A small one could be disguised inside of a magazine or book cover. :)
Other places would be attached to walls, behind road signs, on roads, on top of/underneath vehicles (parked or otherwise), in the expansion gaps of bridges to attack vehicles from underneath, and many other places.