Combat helmets, which appear to be low-tech, no longer are. Advances in the design and construction of helmets have been accelerating in the past five years. The latest effort is to tweak the current ACH (Advanced Combat Helmet) so that it is more stable. That is 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 four years ago that the ACH began to replace the former PASGAT on a wide scale for American troops. The ACH completely replaced all the 1980s era PASGT (Personnel Armor System for Ground Troops) helmets two 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 3.1 pounds (size Extra Small) to 4.2 pounds (size Extra Large). The new ACH weighs a third less than the PASGT, and uses a new type of Kevlar that provides more protection. The ACH will 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 eliminates 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.
Work is already under way to develop an Enhanced Combat Helmet (ECH). This one will be made of a new thermoplastic material (UHMWP, or Ultra-High Molecular Weight Polyethylene). This is lighter and stronger than the Kevlar used in the ACH and PASGT. 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.