Recreational and competitive sport parachuting, which arose from early twentieth century barnstorming and military parachuting. Skydivers jump from aircraft, high buildings, or cliffs, or are towed by speedboats
Parachuting, originally conceptualized in the fifteenth century by Leonardo da Vinci, became skydiving (or sport parachuting) using steerable parachutes about five centuries later. The first parachute was developed in the eighteenth century by Louis-Sébastien Lenormand. It was a canopy, strengthened at the edge and using rigging to hold an underslung passenger basket. It was tested with animal passengers. At the end of that century the first human parachutist, André-Jacques Garnerin, used a modified Lenormand chute. Nineteenth century barnstorming parachutists used Garnerin’s modified chutes to parachute from balloons. To hone the thrills for spectators, folded and packaged canopies were developed. An outstanding chute was the Broadwick coat pack, worn attached to jackets and held to balloons by static lines designed so that, as parachutists fell, their weight pulled against the line and caused the canopy to open.
In 1912, in Ohio, the first aircraft parachute jump—from 1,500 feet—was made by Captain Albert Berry. High aviator mortality in World War I led Leslie Irvin and Floyd Smith to design a parachute escape system for the U.S. Air Force. Because aircraft that were falling out of control were unsuitable platforms for static-line systems, Smith and Irvin built free-fall packs with ripcords that let pilots control the chute opening. By the end of World War II, 100,000 aviators had been saved by parachutes, and paratroopers were routinely sent into battle.
In the 1950’s, parachute modifications led to steerable chute canopies and people began to parachute for fun. Soon, changes in chute shape allowed good horizontal movement, fine motion control, and soft, precise landings. In 1954, “blank gore” modification removed a panel (gore) from the hemispherical parachute canopy and used escaping air to provide some thrust and direction via pulled steering lines attached to the gore bottom. Then, placing L-shaped slots in the rear of the canopy increased ability to “hold” the wind.
In 1961, Pierre Lemoigne designed the first really steerable parachute, leading to ram-air chutes, inflatable flying wings which hugely increase canopy control. They are rectangular, and inflation of their double surfaces (skins) produces the wing shape. Control is obtained by means of low-porosity canopy material; devices enabling the maximum use of canopy air; steering toggles to turn, brake, and control descent rate; and useful shroud-canopy connection systems at the front and rear of the chute. Overall venting arrangements of sport parachutes thus allow skydivers to fine-tune their descents after the canopy opens.
In skydiving, a jump is usually made from a slow-moving plane flying at altitudes from 10,000 to 12,000 feet. “Free fall” is sustained down to 2,000 to 2,500 feet above the ground before opening the parachute. Free-fall maneuvers are accomplished by controlling body position.
Skydiving events include jumping for style, landing accurately, and performing in teams. Early contests in the 1930’s involved only accuracy in landing on a target. The first world championship in skydiving was in Yugoslavia in 1951. It involved contestants from five countries. After this event, world championship contests were scheduled every two years, under the auspices of the Fédération Aéronautique Internationale (FAI). Currently, thirty-five countries participate in world championship contests. The U.S. Federal Aviation Administration (FAA) regulates all skydiving in U.S. competitions. Governance is by the International Parachuting Committee of the FAI, as represented by the U.S. Parachute Association. American competitive skydiving events occur every year.
In jumping for style, the parachutists are required to perform their stunts (called aerobatic maneuvers), such as back turns, in the shortest time possible during free fall, and are judged on their aerobatic form, not on landing site. In accuracy jumping events, competing parachutists seek to land as close as possible to the center of a circular target, set on the ground. In team events, members perform maneuvers such as baton passing or forming circles or other geometric figures (all called “relative work”). Each competing team attempts to form the largest number of patterns in the time available to them. In “canopy relative work,” team members link together and perform figures after their parachutes have opened.
In all competition jumping, the sport parachute is opened at an altitude designated by FAI judges. The way in which contestants leave the delivery aircraft is likewise predetermined. In most recreational skydiving, jumpers carry an altimeter, which indicates rate of descent and tells them when to open the chute. Two new forms of sport parachuting are BASE (an acronym for building, antennae, span, Earth) and parasailing. In BASE jumping, the parachutist leaps from a very high structure such as a building or a cliff. In parasailing, the parachute is linked to and towed by a long line attached to a moving speedboat. The boat’s forward motion both lifts and tows the parachutist.
A skydiving parachute is manually opened with a ripcord after free fall, and the jumper rides it down to the ground. Each parachute is contained inside a knapsacklike harness container (a rig). In addition to the rig, other equipment includes altimeters, jumpsuits, helmets, and goggles. Most parachutes used are ram-air chutes, named for the way in which they open and fly. The first commercial ram-air canopies, developed in the 1970’s, and more modern canopies use the same flight theory. The canopy leaves the rig and the weight of the jumper causes it to inflate into a shape resembling an aircraft wing or airfoil. The canopy holds its airfoil shape because of two-skin (two-layer) construction, with the top and bottom skins joined at the rear (trailing edge) and ends.
The front, the parachute’s leading edge, is open to the air. The canopy is divided into pockets or cells. Suspension lines between the skydiver and the canopy are shorter at the leading edge than at the trailing edge, causing the airfoil to tilt forward and move downward. Air is thus rammed into the cells and, as the jumper and chute move forward, the leading edge divides the air it meets so that air moves over the top skin faster than the air flowing under the lower parachute skin. This leads to lower pressure on the top surface than the bottom and creates lift force, the mechanics that create flight. The canopy flies enough to make descent to the ground relatively slow. However, the lift is not large enough to allow for ascent.
Canopy materials have changed frequently during the history of skydiving. Early canopies, later modified for sport parachute use, were made of silk. This gave them a small rig volume compared to the cotton or linen used by nineteenth century parachutists, while providing the strength and elasticity needed for fast opening. Silk was replaced with more durable and damp-resistant nylon soon after nylon was discovered in the 1930’s. Most nylon in contemporary skydiving is the “ripstop” used in many garments. Ripstop resists tears because it is woven as many tiny squares, so that damage in any single square is contained within it. Shrouds (lines) that attach the jumper to the canopy need to combine strength and elasticity. Dacron, Kevlar, and zero-porosity (ZP) nylon are used to increase strength and reduce total rig weight for skydiver comfort. The greater the canopy porosity, the faster air passes through and the faster the chute falls. Use of ZP nylon slows fall by allowing little air through the canopy.
Vertical (straight-ahead) ram-air flight is achieved by means of steering toggles situated above the chutist’s right and left shoulders, into which the hands are inserted. The toggles connect to shrouds (suspension lines) in the canopy’s trailing edge and act like ailerons. Equal downward pull on both toggles distorts the trailing edge to slow the canopy’s vertical movement and descent rate, if the pull is not too radical. If, however, both toggles are depressed to waist level, full braking occurs, airspeed becomes negligible, and descent rate increases as the canopy loses its ability for lift. Turning a chute also uses the steering toggles.
With one toggle depressed and the other unmoved, a full turn is produced in the direction of pull because the side of the canopy that is pulled slows down while the other side remains flying at speed. To land, a sport parachutist faces into the wind because opposing airflow slows the parachute somewhat, making it easier to land on one’s feet. However, it does not affect descent rate, and this must be reduced if a hard landing is to be avoided. In order to slow descent rate and forward speed, a parachutist identifies the wind direction and turns directly into the wind by smoothly and quickly pulling down both toggles. This converts the canopy’s forward speed, for an instant, to lift, during which time the sport parachutist steps down onto the ground. Maneuvering is complex and takes practice. However, student skydivers usually have the basics down after four to six hours of individual instruction.
Barrett, Norman S., and Simon Ward. Skydiving. London: Watts, 1987. A nice book on skydiving from the European point of view. Donaldson, Chris. Skydive: Sport Parachuting Explained. Marlborough, England: Crowood Press, 2000. Describes the sport of skydiving, its history, equipment, training, and advanced skills, with a useful glossary and many illustrations. Greenwood, Jim. Parachuting for Sport. Blue Ridge Summit, Pa.: Tab Books, 1978. Describes the evolution of parachuting from its beginnings until well into the development of skydiving. Meeks, Christopher. Skydiving. Mankato, Minn.: Capstone Press, 1991. A solid, well-illustrated book covering many aspects of skydiving. Poynter, Dan. Parachuting: The Skydivers’s Handbook. 8th ed. Santa Barbara, Calif.: Parachuting Publications, 2000. A thorough handbook on parachutes, parachuting, and skydiving.