Frag Out! Magazine
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STANDOFF DISTANCE Another parameter that had to be determined was the standoff distance of the helmet from the head that would provide ballistic protection, ventilation, and ther- mal comfort as well as ensure that the helmet would not obstruct communication or weapon use. The Bio-Physical Laboratories at Edgewood Arsenal con- ducted tests on 2 selected types of Kevlar with differ- ent density, which were bound with resin under high pressure. There were also tests concerning BFD (back face deformation) with test round that did not cause the bullets go through the helmet. It was determined that in terms of ballistic protection, there had to be a 0.5-inch gap between the head and the helmet shell. A larger distance was unnecessary because in case of bigger deformation the bullets would penetrate each proposed material. Specially designed .22 round was used for the testing as sub-caliber rounds shot from a .30 carbine. The thermal comfort was tested at the Army Re- search Institute of Environmental Medicine by using a special mannequin called "Copper Man" (since it was made of copper). It was used for tests of clothes, in- cluding headwear. The tests involved using various helmets: infantry, aviation and football helmets. Sev- eral helmets from other countries were also subject- ed to analyses. The scientists checked the efficiency of ventilation holes and the possibility of increasing or decreasing the thickness of the material layer. The re- search proved that there was no point in adding ven- tilation holes or modifying their thickness because the evaporative heat transfer would be only 30% of what could be achieved by taking off the helmet. Protection against cold was insufficient. However, it was proved that, just as in the case of M1, the most reasonable solution was to use a cap in cold climate. The same institute conducted research on ventila- tion. Plastic molds with varying stand-offs were made. During the tests, it was determined that the 0.5-inch distance assumed for the necessary ballistic protection was sufficient for the ventilation purposes and that an increased distance would not change anything. Once again, a sculptor at Natick Labs prepared 3 molds, but they were 0.5 inch larger than the initial ones and they became the basis for future designs. SHAPE OF THE bOTTOM EDGE AND NOTCH- ES IN THE SHELL Simultaneously to the research on sizing and stand- off, Human Engineering Laboratories worked on the shape of the bottom edge of the helmet. As a part of the works, test models were constructed to determine a shape that would not obstruct the field of view, hear- ing, or that would not collide with ballistic vests, weap- ons, or communication performance. The helmet was also to cover the largest area of the head possible and provide greater protection to ears and temples. The fi- nal selected design had the front edge form sort of a cap, which looked completely straight when seen from the front. Sides of the helmet had recesses for ears, which ensured efficient protection and, at the same time, allowed wearing radio earphones under the hel- met. The tests also covered analyses whether the hel- met did not obstruct shooting and whether that action was possible from any posture. In particular, the helmet could not collide with the collar of the vest when the The original paint of the 1985-dated PASGT helmet www.fragoutmag.com