The Old and the New
Newspapers can sometimes convey the impression that improvised explosive devices (IEDs) used in Iraq are innovations developed in response to the US "occupation" of Iraq; a case of homegrown ingenuity defeating a hi-tech superpower. For example, the Washington Post reports:
"Clearly we are not winning the competition over tactics and counter-tactics," said Michael O'Hanlon, a defense analyst who heads Brookings' Iraq Index. "The insurgency's ability to hide IEDs better, detonate them more remotely and build them more powerfully has been at least as effective as our improvements in better armor and better tactics."
Of particular fascination to newspapermen are a newly invented type of shaped charge.
The development of shaped charges appears to be a direct response by insurgents to the Americans' use of more heavily armored vehicles, according to soldiers and U.S. military explosives experts. Those vehicles -- principally five-ton, armor-plated Humvees -- are used by all U.S troops traveling outside military bases. ...
To fashion a shaped charge, one end of a cylindrical object such as a pipe is welded shut, and is then packed with explosive material and a conical piece of metal that becomes a molten projectile when the device is detonated. The charge is designed to focus the blast on a small area. In the case of a Humvee, the charge blasts a hole in the armor plating, propelling the scorching metal into the vehicle's cabin.
These are sometimes called SFFs or self-forging fragment warheads in technical literature, explosive devices that, through the shaping of the explosive backing behind a metal layer, create an explosive plasma slug that travels at high speeds to penetrate armor.
Self-forging warheads are used whenever a weapon of necessarily small size must try to penetrate armor ... a way to create a kinetic penetrator out of a shaped charge, without having to move it a great distance. A block of high explosive is formed with a cavity on one side ... lined with ... malleable but reasonably dense metal. When the explosive detonates ... the thin ... sheeting ... is then pushed outward towards the target with great force by the explosion.
Wikipedia adds that the plasma slug
can ... travel up to, and above 1000 cone diameters (CDs) before it's velocity becomes ineffective at penetrating armor due to aerodynamic drag, or hitting the target becomes a problem. ... If the SFF perforates the armor, extensive behind armor damage (BAD) ... occurs .... mainly caused by the high temperature and velocity armor and slug fragments being injected into the interior space and also overpressure (blast) caused by the impact.
That is what the shaped charges described by the Washington Post are. But although they are deadly, they are not new. A Reuters article notes they have been around, in one form or another, for a long time.
Tim Ripley, special correspondent for Jane's Defence Weekly said armour-piercing was "pretty old technology" and shaped charges had been used since World War Two. "It's nothing a decent car repair workshop couldn't come up with," he said.
What's more, all the types of IEDs that US is encountering in Iraq have been killing thousands of civilians all over the world for the last twenty five years under the name of landmines. This map from the Geneva International Center for Humanitarian Demining (GICHD) has most of Africa and large parts of the Southwest and Southeast Asia colored in. A fascinating manual in PDF format prepared by the GICHD's technical consultants describes every major type of mine that its workers can expect to encounter, as well as prescribing the engineering principles and armor thickenesses that are required in vehicles to defeat them. The mine types described are:
- fragmentation (omnidirectional and directional);
- hollow charge;
- self-forming fragment;
What is fascinating is how the "reference" types of threats described by GICHD, that is the mines most commonly encountered, are Soviet bloc types. Mines are in fact, the most lasting legacy of the Soviet bloc to the Third World, where they are employed as originally designed or in an improvised manner identical to Iraq.
|anti-personnel mine blast type PMN, PMD-6, Type 72|
|anti-personnel mine fragmentation type POM-Z, OZM-4, OZM-72, PROM-1|
|anti-tank blast type TM46, TM57, TMA-3|
|anti-tank blast under wheel TM46, TM57, TMA-3|
|anti-tank blast under hull TM46, TM57, TMA-3|
|anti-tank HC AT-4|
|anti-tank SFF TMRP-6, TMRP-7, TMK-2|
|heavy-size UXO 250-500 kilogram aircraft bombs|
|According to the United Nations, the 10 countries with the most
land mines still in place are:
|Western Sahara||1-2 million|
Stacked or linked IEDs -- landmines, in other words -- were already commonly used to attack armored vehicles in Africa a generation ago. The GICHD manual says on page 14:
Double anti-tank blast mines became common during the middle of 1978 in the former South West Africa with the advent of the first generation mine-protected vehicles (MPVs). These mines appeared in both the linked or “goggle” configuration causing blast effect directly under the vehicle hull or, in the stacked configuration (triple mines were not uncommon), detonating underneath the wheel.
It's not coincidental that many of the armored vehicles now making their way to Iraq are related to designs pioneered in Africa, featuring high cabs and V-shaped armor capsules. (BTW, did you know that filling tires with water greatly attenuates blast damage?) SFFs (in particular the Soviet TMK-2 HC mine which dates from 1955) were also in use to attack protected vehicles in Africa, whose designers naturally tried to figure out countermeasures. Because SFF warheads depend on the formation of the plasma slug some protection schemes devised against them are based on preventing the slug's formation. On page 24 of the GICHD manual we have:
The Munroe effect associated with HC mines requires a stand-off distance in free air to form the high-speed jet. This stand-off distance is usually determined by the cone diameter and length of the charge. The optimal formation of this high-speed jet can be prevented by positioning a “capture plate” between the vehicle hull and the ground surface. This capture plate can cause the break-up of the jet. This will reduce the penetration capability of the jet against the vehicle hull.
The use of IEDs has long been a feature of warfare in Africa and Southwest Asia. Iraqi insurgents, with strong ties to the Al Qaeda and Soviet bloc-trained advisers, would have a great deal of access to these types of attack techniques. The media have recently commemorated the 2,000th US military death in Iraq. What's not commonly realized is that those casualties share something in common with the 26,000 civilians who die each year from landmines. They've been killed by the very methods the late Princess Diana campaigned against. If the US is ever forcibly expelled from Iraq, it is virtually certain to be called upon to return by the United Nations, to remove at American expense the weapons, once glorious, that will have instantly transformed themselves to instruments of evil.