How to build your own armour killers
|If you belong to the resistance and want fast improvements of your killing capacity then go here.|
Everything of the information on this webpage is
available from the U.S governments websites. And it is also available on the weapons
industries homepages. And you have seen them on TV.
Shaped charges are also used in the oil industry and for civilian
"According to defence sources, basic armour-piercing weapons are easy to manufacture, drawing on principles discovered more than a century ago and in use since World War Two. "
Two different types
Jet weapons are too easy to disable with easy countermeasure.
That's why we only should use EFP.
"Long standoff demolition warheads to defeat
armour, masonry and concrete targets"
Home made kitchen improvised armour killer, anyone can build an EFP.
The picture is from a demonstration by the U.S. military.
You can build these at home
At first glance it looks like a bomb, but it is not a bomb.
It's a cannon.
EFP consist of a housing, explosives and a metal dish in front of
When it detonates, a projectile is created.
Projectile speed : 1500 - 3000 m/s.
Penetrates an armour plate of half the dish diameter in thickness.
The EFPs in the U.S military M303 SOFDK Special_Operations_Forces_Demolition_Kit
|Housing :||Glass filled Polyuretahne|
|Explosive :||C-4 (RDX mixture)|
|EFP Liner :||Iron|
|Diameter (cm)||Weight (kg)||Explosives (kg)||Armour penetration at 15 meters standoff (cm)|
|EFPs optimized against different targets
Penetration : Long rod EFP.
Demolition : Short rod EFP, flat projectile
Hole in 63.5mm (2.5 inch) thick armour steel.
OK, we know that the EFP is a cannon.
The question is, will I hit the target,
Or will I miss the target ?
Testing of Medium SOFDK EFP Warhead
|Avg radial miss distance (cm)||7||37 ?||16||27||43||23|
You can't miss the target.
How big EFP do you need ?
Armoured vehicles can be split up in at least two classes of armour thickness.
The EFPs should have the size of penetrating more than 40 mm armour
An EFP of size 150 mm diameter is optimum
A heavy battle tank can only be penetrated by a 150 mm EFP at the top or
bottom where the armour is thinner. A top or belly attack.
The side armour of an Abrams is 150 - 200 mm in thickness. (If you does
not hit the additional thickness of the wheels and tracks.)
The penetration in aluminium armour is 2.7 times the
penetration in armour steel.
The penetration in concrete is 3 - 5 times the penetration in
Attacking fortified concrete buildings
If you intend to attack and destroy a building :
What you need is a surprise attack of 0.1 seconds that kills the enemy before they even have a chance to start using their superior weapons. And you need a weapon that can shoot over all those concrete obstacles that the enemy have put up to stop you. A car loaded with multiple EFPs is one of the best weapons for that job.
A single fighter in a car can do the job that 100 men with conventional heavy weapons can't do.
You can pack the firepower of an entire army into a single car filled with 100 EFPs.
But the resistance will rather put 20 EFPs in line
on a truck and aim 1 meter above the ground ?
Concrete barricades can't protect a building against a vehicle filled up
with the EFPs above.
The most important question, why use EFPs ?
Only EFP can penetrate the armour.
Big fertilizer bombs made of ANFO Ammonium Nitrate Fuel Oil are heavy and take long time to plant. Which becomes a logistics problem for the resistance. But they are still useful.
Most other types of roadside bombs under the road or too close to the road are useless because of the enemy's metal detectors. And these bombs that the enemy can find and neutralize too easy are a big waste of your time and money.
It's a question about becoming more effective.
War cost money, and you must try use some mathematics and planning to become more
The disadvantages of the big bombs are obvious :
An EFP of 3 kg is more effective than 500 kg of artilleryshells, if you look at
how much damage you can give the enemy per kg of explosives and per worked hour. Which
means that you can kill more armoured vehicles per worked hour if you start using EFP.
EFPs are 6 times more effective at killing the enemy compared to all other types of bombs.
99 EFPs planted in July 2007 killed 23 and wounded 89
The U.S. battlefield statistics for July 2007 reveals that the EFPs have a killing efficiency of 23% while other types of bombs have an efficiency of less than 4%. But the killing efficiency of the EFP can be improved up to 40% in the future while the other types of bombs will have a decrease in their killing efficiency down to perhaps 1%, because the easy target Humvees are being replaced with the new types of MRAP vehicles.
The EFPs advantages :
The main disadvantage of EFPs is that you must build them.
|EFPs are also used in anti-helicoptermines.
Microphones, IR-sensors and electric motors are used to automatically aim the EFP at the helicopter and BOOM it is shot down.
SADARM, an armour destroying EFP weapon delivered by a howitzer,
M-killing and K-killing tanks.
The countermeasure against these new mines is to hang armour as close to
the ground as possible.
These mines have 2 explosive charges, the first small charge blows off the
soil which hides the mine, the second big charge launches the EFP.
The EFP can be placed at the bottom of a tube ( otherwise the alternative
is to use a second charge to blow off the soil and camouflage ). The end plug should be of
Hezballahs roadsidebombs forced the occupation of lebanon to end.
How to build EFPs in the kitchen
The easiest EFP is built from a simple steel bar.
The more precise you do the work the more precise will the EFP hit the
For homemade EFPs it is trial and error.
Else, take it from the artilleryshells.
Before trying to melt the explosives, remove any heat sensitive
TNT melts at 70 degrees C (some temperature variation dependent on which
atoms in the toulene molecule were nitrated, don't be confused if you hear different
sources tell different temperatures.)
Try heat up the grenade in a water tank. The water temperature never exceeds 100 degrees as long as there is water. It's more safe if the grenade never comes in contact with the bottom of the tank.
RDX is more powerful than TNT. RDX gives more penetration and
Make sure there are no big air bubbles in the explosives when packing the
For multiple EFPs, you must use explosives filled tubing of exactly the
same length, instead of separate blastingcaps.
Use your fantasy when planting EFPs.
If you need a popup weapon then try build something from a gas-spring that
you can take from a cars backdoor or from an office chair..
Shaped charges can be divided into two types, those producing relatively slow moving projectiles, the so- called"explosively formed penetrator or projectile" (EFP) and those producing fast moving stretching jets,"jetting shaped charges". These two types can be distinguished by fundamental differences.
The liner of an EFP is a shallow dish with the depth of the dish typically being less than 0.25 of its diameter whereas the liner of a jetting shaped charge is typically a cone or hemisphere in which the depth of the liner cavity is greater than 0.4 of its diameter.
The shape most commonly used for the jetting liner is a cone, with an internal apex angle of 40 to 90 degrees. Other widely used shapes include hemispheres, tulips, trumpets, ellipses, and bi-conics; the various shapes yield jets with different velocity and mass distributions.
The chief advantage of the EFP over a conventional (e.g., conical) shaped charge is its effectiveness at very great standoffs
Explosively Formed Projectile (EFP)
Wide angle cones and other liner shapes such as plates or dishes do not jet, but give instead an explosively formed projectile or EFP. The projectile forms by dynamic plastic flow and has a velocity of 1-3 kms-l . Target penetration is much less than that of a jet, but the hole diameter is larger with more armour backspall.
An EFP must be aerodynamically stable so as to strike the target within a small miss
distance and a small angle of obliquity. In the U.S., extensive work has focused on
forming EFPs with canted fins, to induce spin-up. By forming canted fins on an EFP,
improvements in aerodynamic stability can be realized.
The need for an aerodynamic shape is not necessary for the medium or short-standoff.
EFP liners are typically thicker than jetting shaped charge liners of a
The EFP projectile velocity depends on the liner to explosives layer
Because EFPs are not intended to produce very fast moving jets, they require less explosive. Jetting shaped charges in the prior art are therefore typically longer than EFPs of a similar diameter.
The EFP is relatively unaffected by first-generation reactive armour. (Armour made of explosives.)
If the EFP perforates the armour, extensive behind armour effects BAE will occur. The BAE is mainly caused by the hot armour and slug fragments being injected into and bouncing inside the interior space and the overpressure (blast) caused by this debris.
Aluminium and composite armour limits the BAE caused from fragments.
What happends if you are hit from an EFP ?
The picture below is for comparison and shows what happens if you are hit from US fine calibre munition and splinter.
If you are hit by an EFP the same thing will happen as if you are hit from a cannon.
Anyone hit by an EFP and surviving will never go back to work again. The limb is off,
and can't be repaired.
A clue :
Designing Explosively Formed Projectiles
Explosively formed projectiles (EFP) have been used to defeat armored
vehicles for more than 30 years. The EFP warhead was derived from the Misznay-Schardin
device, which consists of a right circular cylinder of explosive, with a shallow cavity in
one end that is fitted with a thin metallic liner. Upon detonation, the liner dynamically
transforms into an aerodynamic projectile traveling at high velocity (typically 1500-2000
m/s). Figure 1 shows the formation process for a tactical EFP warhead from its initial
predetonation state to the fully formed profile.
1 The shape of the liner.
The geometry of the liner's bottom surface primarily affects the velocity of the liner as a function of radius early in the EFP formation process. Making this surface too concave will cause the liner material to be driven inward more than desired. Making this surface too flat will result in a broad, flat projectile.
2 The thickness of the liner as a function of radius.
Altering the geometry of the top surface of the liner (defined by a
second-degree polynomial) relative to the bottom surface changes the thickness of the
liner as a function of radius. This changes the mass distribution and strength of the
liner across its radius. These effects determine the shape of the liner late in the EFP
formation process. While the explosive charge accelerates the liner, the center begins to
move with a greater velocity than the outer edge. During EFP formation, the material near
the outside edge of the liner slows the material near the center of the liner. This
process produces a tremendous amount of strain in the liner. If the liner is made too
thick towards its outer edge, localized strain will cause the metal to fail, resulting in
metal chunks instead of an EFP. Making the liner too thin will cause the same problem. A
correctly designed liner balances the competing effects.
3 The explosives / liner thickness ratio.
The thickness ratio between the explosives layer and the liner determines the
4 Shaping the detonation wave propagation
The arrows in the picture below show the delay time between when the detonation wave
reaches the center and when it reaches the outer edge of the liner, for three different
flat liner locations.
Some types of shaped charges have elongated explosives layer or use explosive lenses
combining two layers of different types of explosives. Or other smart solutions for
shaping the detonation wave.
Also remember that big air bubbles in the explosives can destroy the shape of the detonation wave.
(The blue thing in this picture is
the blasting cap.)
5 Creating fins
(Also see patent : 5365852 at the bottom of this page, about creating fins.)
EFP liners can be made of circular plates or made of steel bars. And the
main difference is that the circular liners creates conetailed aerostable projectiles
while steel bars creates unstable projectiles.
The projectiles penetration cabability is proportional to the projectiles lenght in the direction of the movement.
The penetration depth depends on the impact angle. And the maximum
penetration is at a perpendicular impact.
Some extremely long stretched circular EFP designs have no cone tail and is also broken up into multiple fragments, and have no aerostability, and can only be used at short to medium distance.
A simpler EFP made of a steel bar is easier to build, and the aerodynamic instability will not affect the impact angle at short roadside bomb distance.
Is an easy homebuilt EFP built from a flat steel plate with plastic explosives attached
to one side.
If the projectile isn't aerodynamically stable then this is a short to medium distance weapon.
The countermeasures against RPG does not work against EFP.
The U.S. and British military are hanging empty metal boxes and
"slat_armour" (metal bars) and chicken wire on their vehicles, to predetonate
the RPG-7 grenades.
EFP from the news
IED Blows Up British Army's Main Battle Tank;
BAGHDAD, Iraq - Of the many dangers lying in wait for American soldiers in Iraq, the U.S. military increasingly fears one thing: the new, advanced roadside bombs planted by insurgents.
"There are very few things we fear," says Col. Douglass Heckman. "When a simple roadside bomb goes off, it's not going to kill us most of the time. A sniper can't penetrate -- we keep the gunners down -- small arms can't penetrate. ... In fact, a vehicle-borne suicide bomber typically isn't going to hurt us. The thing that scares us is the advanced roadside bombs."
Heckman's teams of military trainers embedded with the 9th Iraqi Army Division have reason to be wary.
In their sector of Baghdad east of the Tigris River, at least five U.S. military advisors have been killed by roadside bombs in the last two weeks -- among them the first full colonel killed in combat in the war and two lieutenant colonels who died in the same vehicle.
Unlike regular roadside bombs, EFP's -- explosive-formed penetrators -- remain intact as they explode. The steel tubes with curved metal seals form a kind of super bullet that can go directly through a tank's armor.
The new, more lethal shaped charges are behind most of the attacks that often kill several servicemembers with one blast. Eleven U.S. troops were killed on Wednesday, making it the deadliest day this year. Five of those servicemembers died in a single roadside bomb attack near Tikrit, the military said.
It's obvious that these are not factory made in Iran, but simple sewage pipes or lamp-posts cut in a garage in Iraq.
NYTimes August 8, 2007
Of the 69 members of the American-led forces killed in action in July, the lowest toll in months, 23 died as a result of attacks with the devices, according to data supplied by General Odierno?128;™s command. Of the 614 allied troops who were wounded that month, 89 were hit in penetrator attacks.
Though explosively formed penetrators account for a small fraction of roadside bomb attacks in Iraq, they cause a disproportionately large number of casualties.
Many of the penetrators faced by American forces are difficult to counter. Because they
fire from the side of the road, the militants do not need to dig a hole to plant them,
making them well suited for urban use. Because they are set off by a passive infrared
sensor, they cannot be thwarted by electronic jamming.
1200 roadsidebombs each month but only 99 of them are EFP's
The EFP's Killing efficiency :
Compare to the other types of roadsidebombs which have less than 4% killing efficiency.
Patents on EFP
You can also create fins by placing pieces of metal in front of the liner to slow down the acceleration. Textron EFP with a cone shaped liner instead of a dish shaped.
Not usable by the resistance because it's too complicated, but it gives a clue about an easier way to build EFPs.
Patent : 6606951 EFP antiarmour mine
http://www.freepatentsonline.com download the pdf-files
A possible easier way to build EFPs
The resistance consist of amateurs which most of them are unskilled in
using tools or shaping EFP liners. Which means that if a a weapon need to much work then
noone will build it.
You can't find circular dish shaped liners ready to use anywhere, you
can't buy them.
The clothes-pin shaped EFP from patent 4649828 tells us that there might be an easier way to build EFPs.
Simplified Improvised Multiple EFP SIM-EFP
At shorter roadside bomb distance there is no need for any aerostable cone tailed projectiles, which means that the liner can be simplified.
A SIM-EFP is built of simple cut and bent steel bars.
A SIM-EFP is a construction that fits in between the linear cutting charge and the
A simplified EFP has a thicker liner and thicker explosives layer.
No trouble with timing differences anymore
The SIM-EFP is by it's construction optimized for killing armored vehicles.
When the production of EFPs becomes too easy, then it will become the standard weapon instead of a rarely used special weapon. And that will improve the resistance's striking power and killing efficiency and force the enemy to abandon the roads.
EFPs are 6 times more effective than the big bombs at killing the enemy.
Try evaluate the design below, because it is so powerful that it will change the battlefield if it works.
Heavy tank killer ?
With this it's too easy to build a weapon launching a projectile half a meter in length. The penetration in armour is almost the same as the projectile length, which means that it can penetrate a heavy battle tank like Abrams or Merkava from a side attack.
It's flat design also makes it easier to hide in the terrain.
See the picture below that shows a circular and a flat EFP side by side.
It's easier to create a long rod projectile from a flat EFP design compared to a
circular EFP design.
With this design you are not limited to attacking the heaviest tanks from the top or bottom anymore. You can kill them from a side attack.
Circular EFPs of that size are difficult to build. Which means
that if you want a homebuilt heavy tank penetrator then you must abandon circular EFPs and
try a flat EFP design.
If you got nothing else then take a railroad track. Send it like a projectile through the enemy's tanks.
Flat EFPs are only useful at short and medium roadside bomb distance because they are not aerostable.
The flat EFP design is also an argument for redesigning nuclear powerplants because
it's easy to build at home a weapon launching a projectile straight through a nuclear
Very big homebuilt efp
Some home built EFPs found in Iraq.
The EFPs were abandoned by the Mahdi resistance because their leader the chicken Mr Al-Sadr stabbed the resistance in the back and told them to lay down their weapons and not to fight the enemy. And he prolonged the US occupation with many years. What a hero.
Demining machines and weapons.
What they all got in common is that they are all useless against EFP because the EFP strikes from a side attack.
Most of the resistance's big bombs are too easily neutralized with the tools below.
This machine below whips the ground with chains with heavy force and detonates the
The mine roller blows up the bombs, and only the roller is damaged instead of the
The mine plow digs up the mines and creates a safe passage for tanks and troops.
Ground penetrating radar and a computer memory is used to save a record of what the
road looks like for many miles. If anything has changed since last then there is a bomb.
The robot arm and the remote controlled tiny machine in the picture below is used to
undig bombs at safe distance away from
The MCLC and other similar antimine weapons.
The main disadvantage of EFPs is that they must be remote controlled.
The difference between a point weapon and line weapon
EFPs on the other hand is a line weapon, a cannon. And there is no safe distance from a cannon.
More advantages of line weapons :