Bungee jumping

Bungee jumping is an activity that involves jumping from a tall structure while connected to a large elastic cord. The tall structure is usually a fixed object, such as a building, bridge or crane; but it is also possible to jump from a movable object, such as a hot-air-balloon or helicopter, that has the ability to hover over one spot on the ground. The thrill comes as much from the free-falling as from the rebounds. [Kockelman JW, Hubbard M. Bungee jumping cord design using a simple model. "Sports Engineering" 2004; 7(2):89-96]

When the person jumps, the cord stretches to absorb the energy of the fall, then the jumper flies upwards again as the cord snaps back. The jumper oscillates up and down until all the energy is used up.

History

The word bungee (pronEng|ˈbʌndʒi:) first appeared around 1930 and was the name for a rubber eraser. The word bungy, as used by A J Hackett, is said to be "Kiwi slang for an Elastic Strap". [ [http://www.ajhackett.com.au/faq.htm www.ajhackett.com.au] Dead link|date=January 2008] Cloth-covered rubber cords with hooks on the ends have been available for decades under the generic name "bungee cords."

In the 1950s David Attenborough and a BBC film crew 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. A similar practice, only with a much slower pace for falling, has been practiced as the Danza de los Voladores de Papantla or the 'Papantla flyers' of central Mexico, a tradition dating back to the days of the Aztecs.

The first modern bungee jumps were made on 1 April, 1979 from the 250-foot Clifton Suspension Bridge in Bristol, by David Kirke, Chris Baker, Simon Keeling, Tim Hunt and Alan Weston of the Dangerous Sports Club. The jumpers were arrested shortly after, but continued with jumps in the US from the Golden Gate and Royal Gorge bridges, (this last jump sponsored by and televised on the American program "That's Incredible") spreading the concept worldwide. By 1982 they were jumping from mobile cranes and hot air balloons, and putting on commercial displays.

Commercial bungee jumping began with the New Zealander, A J Hackett, who made his first jump from Auckland's Greenhithe Bridge in 1986. [cite web|url=http://unlimited.co.nz/unlimited.nsf/default/E71409A1DAE3EA24CC256EEC0010D618|title=Can you Hackett?|author=Fiona Rotherham|date=1 August 2004] 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, and opening the world's first permanent commercial bungee site; the Kawarau Bridge Bungy at Queenstown in the South Island of New Zealand. [ [http://www.bungy.co.nz/index.php/pi_pageid/17 AJ Hackett Bungy ] ] 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. As with any sport, injuries can still occur (see below), and there have been fatalities. A relatively common mistake in fatality cases is to use a cord that is too long. The cord should be substantially shorter than the height of the jumping platform to allow it room to stretch. When the cord reaches its natural length the jumper either starts to slow down or keeps accelerating depending upon the speed of descent. One may not even start to slow until the cord has been stretched a significant amount, 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.

Equipment

The elastic rope first used in bungee jumping, and still used by many commercial operators, is factory-produced braided shock cord. This consists of many latex strands enclosed in a tough outer cover. The outer cover may be applied when the latex is pre-stressed, 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, accidents in which participants became detached led 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.

Highest Jump

The Guinness Book of World Records states the highest commercial bungee jump is off of the Bloukrans River Bridge, 40 kilometres east of Plettenberg Bay in South Africa. This jump takes place from a platform below the roadway of the bridge, and the height from the platform to the valley floor is convert|216|m|ft. There is another commercial bungee jump currently in operation which claims to be slightly higher, at convert|220|m|ft. This jump is located near Locarno, Switzerland and takes place from the top of the Verzasca Dam. This jump was prominently featured in the opening scene of the James Bond film Goldeneye. In December 2006, AJ Hackett added bungee jumping to his Macau Tower facility in Macau S.A.R. China, making it the world's highest commercial jump at convert|233|m|ft.Fact|date=February 2007. The latter of these higher jumps does not qualify as the world's highest "bungee" as it is not strictly speaking pure bungee, but instead what is referred to as a 'Decelerator-Descent' jump. The bridge at Bloukrans and the Verzasca Dam jumps are pure freefall swinging bungee from a single cord, while the Macau Tower jump has a secondary cable which controls descent and trajectory, thereby failing to take the place in the record books.

Guinness only records jumps from fixed objects to guarantee the accuracy of the measurement. John Kockleman however recorded a convert|2200|ft|m|-1|adj=on bungee jump from a hot air balloon in California in 1989. In 1991 Andrew Salisbury jumped from convert|9000|ft|m|-2 from a helicopter over Cancun for a television program and with Reebok sponsorship. The full stretch was recorded at convert|3157|ft|m. He landed safely under parachute.

One commercial jump higher than all others is at the Royal Gorge Bridge in Colorado. The height of the platform is convert|321|m|ft|0. However, this jump is rarely available, as part of the Royal Gorge Go Fast Games—first in 2005, then again in 2007.

In popular culture

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 in Switzerland: Verzasca Dam, and the jump was genuine, not an animated special effect).

It appears in the title of the South Korean film Bungee Jumping of Their Own (Beonjijeompeureul hada 번지점프를 하다, 2001), although it does not play a large part in the film.

In 1986, the BBC TV program 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 while rehearsing a bungee jump.

A fictional proto-bungee jump is a plot point in the Michael Chabon novel The Amazing Adventures of Kavalier and Clay.

In the film Selena, in which Jennifer Lopez plays Selena Quintanilla-Perez, she is shown bungee jumping at a carnival. This is an actual event which took place shortly before Selena's death in 1995.

Variations

In "Catapult" (Reverse Bungee or Bungee Rocket) the 'jumper' starts on the ground. [cite web |title= Bungee Rocket BASE Jump - Wow!|url=http://www.asterpix.com/console/?avi=8502201] The jumper is secured and the cord stretched, he/she is then released and shoots up into the air. This is often achieved using either a crane or a hoist attached to a (semi-)perma 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 a higher jump than could normally be made from a trampoline alone.

Bungee Running involves no jumping as such. It merely consists of, as the name suggests, running along a track with a bungee cord attached. One often has a velcro-backed marker which is used to mark how far the runner got before the bungee cord pulled back. There is always someone else running alongside.

afety and possible injury

There is a wide spectrum of possible injuries during a jump. One can be injured during a jump if the safety harness fails, the cord elasticity is miscalculated, or the cord is not properly connected to the jump platform. In most cases this is a result of human error in the form of mishandled harness preparation. Another major injury is if the jumper experiences cord entanglement with his/her own body. Other injuries include eye trauma [ Krott R, Mietz H, Krieglstein GK. Orbital emphysema as a complication of bungee jumping. Med Sci Sports Exerc 1997;29:850–2. ] [ Vanderford L, Meyers M. Injuries and bungee jumping. Sports Med 1995;20:369–74] , rope burn, uterine prolapse, dislocations, bruises, pinched fingers and back injury.

Age, equipment, experience, location and weight are some of the factors, and nervousness can exacerbate eye traumas [ Filipe JA, Pinto AM, Rosas V, et al. Retinal complications after bungee jumping. Int Ophthalmol 1994–95;18:359–60 ] [ Jain BK, Talbot EM. Bungee jumping and intraocular haemorrhage. Br J Ophthalmol 1994;78:236–7. ] .

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.

In August 1998, Jerome Charron died in a bungee ride accident at the Ottawa Exhibition in Ottawa, Ontario, Canada when he was hurled 40 meters into the air before plummeting to his death as his harness had detached. In February 2000, the firm responsible for the ride, Anderson Ventures, was fined $145,000 for this incident. Provincial inspectors had inspected the ride just 4 days before the incident and approved it, but did not see the strap because it was in a nearby box.

References