Bungee jumping

From Free net encyclopedia

Bungee jumping (or bungy jumping) is an activity in which a person jumps off from a high place (generally of several hundred feet/meters) with one end of an elastic cord attached to his/her body or ankles and the other end tied to the jumping-off point. When the person jumps, the cord will stretch to take up the energy of the fall, then the jumper will fly upwards as the cord snaps back. The jumper oscillates up and down until the initial energy of the jump is dissipated.

1 History
2 Equipment
3 Competition
4 Bungee jumping in the mass media
5 Variations
6 See also
7 External links

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History

The word bungee (pronounced bunjie) first appeared around 1930 and was the name for rubber eraser. The word bungy, as used by A J Hackett, is said to be "Kiwi slang for Elastic Strap"[1]

Image:BungyViewCairns.jpg In the 1950s David Attenborough and a BBC film crew had brought back footage of the "land divers" of Pentecost Island in Vanuatu, young men who jumped from tall wooden platforms with vines tied to their ankles as a test of courage. This film inspired Chris Baker of Bristol, England to use elastic rope in a kind of urban vine jumping. The first modern bungee jump was made on 1 April, 1979 from the 250ft Clifton Suspension Bridge in Bristol, and was made by four members of the Dangerous Sports Club. The jumpers, led by David Kirke, were arrested shortly after, but continued with jumps in the US from the Golden Gate and Royal Gorge bridges, spreading the concept worldwide. By 1982 they were jumping from mobile cranes and hot air balloons, and putting on commercial displays.

The first operator of a commercial bungee jumping concern was New Zealander, A J Hackett, who made his first jump from Auckland's Greenhithe Bridge in 1986. During the following years Hackett performed a number of jumps from bridges and other structures (including the Eiffel Tower), building public interest in the sport. Hackett remains one of the largest commercial operators, with concerns in several countries.

Despite the inherent danger of jumping from a great height, several million successful jumps have taken place since 1980. This is attributable to bungee operators rigorously conforming to standards and guidelines governing jumps, such as double checking calculations and fittings for every jump. Unfortunately accidents in this sport tend to be of the spectacular, bizarre, and terminal variety. A relatively common mistake is to use too long a cord. The cord should be substantially shorter than the height of the jumping platform to allow it room to stretch. To illustrate how easy it is to overestimate the permissible length of cord, consider the following question:

When the cord reaches its natural length, does the jumper:

(a) stop?
(b) start to slow?
(c) keep getting faster?

The answer, perhaps surprisingly, is (c). One does not even start to slow until the cord has already stretched somewhat, because the cord's resistance to distortion is zero at the natural length, and increases only gradually after, taking some time to even equal the jumper's weight. See also Potential energy for a discussion of the spring constant, and the force required to distort bungee cords and other spring-like objects.

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Equipment

The elastic rope first used in bungee jumping, and still used by many commercial operators, is factory-produced braided shock cord. This is comprised of many latex strands enclosed in a tough outer cover. The outer cover may be applied when the latex is prestressed, so that the cord's resistance to extension is already significant at the cord's natural length. This gives a harder, sharper bounce. The braided cover also provides significant durability benefits. Other operators, including A J Hackett and most southern-hemisphere operators, use unbraided cords in which the latex strands are exposed. These give a softer, longer bounce, and can be home-produced.

Although there is a certain elegance in using only a simple ankle attachment, the many accidents in which participants have become detached lead many commercial operators to use a body harness, if only as a backup for an ankle attachment. Body harnesses are generally derived from climbing equipment rather than parachute equipment.

Retrieval methods vary according to the site used. Mobile cranes provide the greatest recovery speed and flexibility, the jumper being lowered rapidly to ground level and detached. Many other mechanisms have been devised according to the nature of the jump platform and the need for a rapid turn-around.

The highest commercial bungee jump, according to the Guinness Book of Records, is off of the Bloukrans River Bridge, 40km east of Plettenberg Bay in South Africa. The jump takes place from a platform below the roadway of the bridge, and the height from the platform to the valley floor is a terrifying 216m (708 feet). One higher commercial jump took place from Colorado's Royal Gorge Bridge, in conjunction with the 2005 Go Fast Games. The height of the platform was 321m (1053 feet). However, this opportunity lasted for only three days, and it is unclear if it will be repeated in future games.

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Competition

For the many participants who make jumps as a one-off thrill, the idea of competing is irrelevant, but regular jumpers have gone to great lengths to devise criteria for competition, mostly based on acrobatics. Bungee jumping was featured in the early days of the ESPN X-Games but the lack of an objective measure of skill detracted from the event compared to other extreme sports.

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Bungee jumping in the mass media

Several major movies have featured bungee jumps, most famously the opening sequence of the 1995 James Bond film GoldenEye in which Bond makes a jump over the edge of a dam in Russia (in reality the dam is on the Switzerland-Italy border, and the jump was genuine, not an animated special effect).

In the television program The Fresh Prince of Bel-Air, the secondary character Trevor was killed while proposing to Hilary Banks during a bungee jump aired live on his television news program.

In 1986, the BBC TV programme The Late, Late Breakfast Show, presented by Noel Edmonds, was taken off the air after a volunteer for its 'Whirly Wheel' live stunt section, Michael Lush, was killed in a tragic accident while rehearsing a bungee jump.

In the second season of the television program Scrubs, episode 207 "My First Step," the character JD is a medical resident, comfortable in what he calls his "wait-and-see" approach to treating his patients. When his fellow resident and friend Elliot Reid takes a chance in diagnosing a patient and the patient dies, he taunts her because his tactic was "fail proof." Eventually, she is commended and praised for giving the patient "a popsicle's chance in hell" (according to Dr. Kelso) and subsequently teaches JD the value of taking a chance on things. The episode ends with her encouraging him to bungee jump and the two leap from a bridge in a tandem style.

In 1997, Laura Patterson, one of a 16-member professional bungee jumping team, died of massive cranial trauma when she jumped from the top level of the Louisiana Superdome with improperly handled bungee cords and smashed head-first into the concrete-based playing field. She was practicing for an exhibition intended to be performed during the halftime show of Super Bowl XXXI. The bungee jumping portion of the show was removed from the program and a commemoration of Patterson was added.

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Variations

In "Catapult" (Reverse Bungee or Bungee Rocket) the 'jumper' starts on the ground. The jumper is secured and the cord stretched, then they are released and shoot up into the air. This is often achieved using either a crane or a hoist attached to a (semi-)permanent structure. This simplifies the action of stretching the cord and later lowering the participant to the ground.

"Twin Tower" is similar with two oblique cords.

Bungy Trampoline uses, as its name suggests, elements from bungy and trampolining. The participant begins on a trampoline and is fitted into a body harness, which is attached via bungy cords to two high poles on either side of trampoline. As they begin to jump, the bungy cords are tightened, allowing higher than could normally be obtained from a trampoline alone.

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