November 1, 2011: The U.S. Marine Corps has ordered 150,000 NAPPs (nape protector pads) to protect the back of the neck from explosion fragments. The flexible pad, made of ballistic material (that will stop most shell, grenade and bomb fragments) is needed because the new ECH helmet the marines are soon to receive has a high back, so that soldier can arch their neck back while prone. Older helmets were longer in back, but this tended to bump up against the higher collar of the new protective vests. The current ACH helmet is the same basic shape as the new ECH, and the marines have noted more fragment injuries to the back of the neck. Thus the need for NAPP, although many marines will not wear NAPP, because of heat and neck mobility issues. The army does not yet plan to adopt the NAPP.

Soldiers and marines were supposed to have their new ECH (Enhanced Combat Helmet) by now, but this was delayed when problems were encountered in the mass production process. While testing showed that the lighter (than previous helmets) ECH was even more resistant to bullets and fragments, a screw up by the manufacturer led to the first ECHs that were mass produced to be rejected. The problem was that a seemingly minor change was made in the manufacturing process that unexpectedly rendered the ECH less bullet proof. It was something as simple as speeding up a manufacturing step involving using more heat to dry paint and a change in the curing process for the complex plastics. These problems are being fixed, but now troops won't get the ECH until later this year, rather than five months ago.

Earlier this year, there was nothing but good news with the ECH. Testing found that the ECH was even more bullet proof than expected. It was discovered that the machine firing metal fragments at the ECH (to represent shell and bomb fragments) could not fire fragments fast enough to penetrate. The ECH was supposed to be invulnerable to pistol bullets, and it was, but some types of metal fragments were expected to still be dangerous. So ECH was tested to see how well it could resist high-powered rifle bullets. ECH was not 100 percent invulnerable, but in most cases, it would stop anything fired from a sniper rifle. Overall, it was calculated that the ECH was 40 percent more resistant to projectiles and 70 percent stronger than the current ACH helmet.

The ECH is made of a new thermoplastic material (UHMWP, or Ultra-High Molecular Weight Polyethylene). It is lighter and stronger than the Kevlar used in the ACH and earlier PASGT and, it turned out, provided much better protection as well. The ECH costs $600 each, twice as much as the ACH. But for troops under fire, the additional cost is well worth the additional protection. But given the complexity of the thermoplastic material, you have to pay close attention to chemistry and the manufacturing process, and constantly test the resulting helmets. The army is buying 200,000 ECHs, the marines 38,500, and the navy 6,700.

Combat helmets, which appear to be low-tech, have been anything-but over the last three decades. Advances in the design and construction of helmets have been accelerating, especially in the last decade. For example, the current ACH (Advanced Combat Helmet) recently underwent some tweaks to make it more stable. That was required because more troops are being equipped with a flip down (over one eye) transparent computer screen. The device is close to the eye, so it looks like a laptop computer display to the soldier, and can display maps, orders, troop locations or whatever. If the helmet jumps around too much, it's difficult for the solider to make out what's on the display. This can be dangerous in combat.

It was only six years ago that the ACH began entering service. The ACH completely replaced all the 1980s era PASGT (Personnel Armor System for Ground Troops) helmets four years ago. The Kevlar PASGT design was a third generation combat helmet, nicknamed the "Fritz" after its resemblance to the German helmets used in both World Wars. That German World War I design, which was based on an analysis of where troops were being hit by fragments and bullets in combat, was the most successful combat helmet in both world wars. This basic design was finally adopted by many other nations, after the American PASGT helmet appeared in the 1980s. Most of the second generation helmets, which appeared largely during World War II, were similar to the old American "steel pot" design, which lasted about 40 years. The fourth generation helmets, currently in service, use better synthetic materials and more comfortable design.

The PASGT came in five sizes, and weighed between 1.4 kg/3.1 pounds (size Extra Small) to 1.9 kg/4.2 pounds (size Extra Large). The ACH weighed a third less than the PASGT, and used a new type of Kevlar that provided more protection. The ACH can stop a 9mm bullet at close range, and rifle bullets at longer ranges. The ACH is smaller, and does not cover as much of the neck. This was important, because the newer protective vests (like the bullet-proof Interceptor) ride high on the back, thus becoming very uncomfortable when the soldier is prone and trying to fire his rifle. The ACH eliminated this problem. The ACH was first developed as a special project by the U.S. Army Special Forces, and was so successful that the rest of the army began buying them. The success of the ACH led to the ECH.

The first modern combat helmets appeared during World War I (1914-18), with the U.S. adopting the flat, British design steel model, and using it for 25 years. The PASGT lasted 25 years, but it looks like the ACH will be gone in less than ten, replaced by the ECH.