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Ballooning never did emerge as a serious military force, but did encourage the development of the parachute. First as a daredevil spectacle, and later as a practical safety measure. Interestingly, prior to the first flights by heavier-than-air craft in the early 1900s, manned parachute jumps were being regularly made from moored balloons. The earliest military parachutists were balloon observers on both sides of the Western Front during World War I. These artillery spotters, in wicker baskets dangling from flammable hydrogen balloons, were terribly vulnerable to machine-gun fire from roving enemy aircraft. So the observers were equipped with crude parachutes and trained to bail out whenever an attack was threatened.
    Despite parachutes being well developed and fairly reliable, few tactical aviators of the Great War ever used them. Early pursuit (fighter) aircraft of the day simply did not have the necessary lift to carry a man, the machine itself, guns, ammunition, a parachute, and other safety equipment. By 1918, though, the German Air Force had realized that parachutes could save the lives of irreplaceable and scarce veteran pilots, and began to issue them. None of the Allied air forces ever gave parachutes to tactical aviators.
    A conceptual view of Leonardo da Vinci’s parachute design.
    OFFICIAL U.S. ARMY PHOTO

    The inter-war years were a time of slow and quiet development in parachute technology. By the opening of World War II, the state of the art in parachute development was based upon the labor of the industrious silkworm. This may seem odd in light of the then-recent development (in the 1930s) of such synthetic fibers as nylon by the DuPont Corporation. However, the first applications of nylon were limited to making household items like toothbrushes and women’s stockings. Thus, the many potential benefits of synthetic fibers to airborne warfare were to be denied until after World War II. Virtually every parachute used by airmen and paratroopers in that war was made from that most comfortable of fabrics: silk. Silk has many desirable qualities when used in parachutes. These include light weight, an extremely dense thread count (the number of fibers per inch when woven), a favorable porosity to air, and great tensile strength when woven into fabric and lines. Given a careful cycle of packing and cleaning, the World War II-era parachute could be used several dozen times with confidence.
    The personnel parachutes used in World War II by most nations were fairly similar in design. Most utilized a circular canopy or shroud of woven silk cloth. Around the base of the canopy was a fabric support base called a skirt, from which the support or shroud lines hung. Usually the paratrooper would be held by a special harness, designed to spread the shock and loads of the parachute opening over the body. The harness was attached to a set of thick fabric supports called risers, which fed up to shroud lines.
    The basic design of most non-steerable parachutes has changed little over the last six decades. A circular canopy chute will, once inflated, essentially fall in a straight and vertical line. Notwithstanding the effects of cross-winds, this means that if a stick (or line) of paratroops is dropped at regular intervals behind an aircraft, they will be spaced fairly evenly as they descend. Using circular parachutes also minimizes the chances of a midair collision between two or more paratroopers trying to maneuver. This is the reason why today, in an era when sport parachutists (“sky divers”) almost always use square parafoil parachutes which are steerable, the older-design circular models are always used in mass airdrops.
    When packed, the parachute is attached to a tray which is mounted on the back of the paratrooper and attached to the harness. Around the tray are a series of overlapping fabric panels, which form a protective bag to keep the chute from being snagged or damaged prior to opening. When folded over, the bag