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Skydiving

Skydiving

Parachuting, or skydiving, is a recreational activity, competitive sport and method of deployment of military personnel (and occasionally, firefighters). It involves the breaking of a free fall from a height through the use of a parachute.

Procedure

Typically, a trained skydiver (or jumper) and a group of associates meet at an isolated airport. A fixed base operator at that airport usually operates one or more light cargo aircraft, and takes groups of skydivers up for a fee. In the earlier days of the sport, an individual jumper would go up in a Piper Cub aircraft for reasons of economy. A jump involves individuals jumping out of aircraft (usually an airplane, but sometimes a helicopter or even the gondola of a balloon), usually travelling at approximately 4000 metres (around 12,000 feet) altitude, and free-falling for a period of time before activating a parachute to slow the landing down to safe speeds. Once the parachute is opened, the jumper can control his or her direction and speed with cords called "steering lines," with hand grips called "toggles" that are attached to the parachute, and so he or she can aim for the landing site and come to a relatively gentle stop in a safe landing environment. Most modern sport parachutes are self-inflating "ram-air" wings that provide control of speed and direction similar to the related paragliders. (Purists in either sport would note that paragliders have much greater lift and range, but that parachutes are designed to absorb the stresses of deployment at terminal velocity.) terminal velocity Skydivers skydive because it is the closest one can get to the dream of flying. Experienced skydivers will tell you that in freefall, one can do anything a bird can do, except go back up. But skydiving is the only aerial activity where the body is the flying instrument instead of a machine, however simple. Some jumpers explain the attraction to skydiving by adrenaline addiction. Others suggest a suicidal disposition, but these people are usually not skydivers. Most skydivers make their first jump with an experienced and trained instructor (this type of skydive may be in the form of a "tandem skydive"). During the tandem jump the jumpmaster is responsible for the stable exit, maintaining a proper stable freefall position, and activating and controlling the parachute. With training and experience, the fear of the first few jumps is supplanted by the tact of controlling fear so that one may come to experience the satisfaction of mastering aerial skills and performing increasingly complicated maneuvers in the sky with friends. Other training methods include static line, IAD (Instructor Assisted Deployment), and AFF (Advanced Freefall) aka Progressive Freefall (PFF) in Canada. See below.

Skills

Parachuting has complex skills that can take thousands of jumps to master but the basics are often fully understood and useful during the first few jumps. There are four basic areas of skill: basic safety, free fall maneuvers, parachute operation, and landing. Basic safety includes knowing how and when to: do a gear check, exit normally, react in an emergency, deploy a parachute, handle common malfunctions, pick a landing area, and set up and execute a landing. Most national sport organizations certify instructors, most operators who fly skydivers retain an instructor, and all certified instructors can teach the basics well enough for a student to be licensed by the national sport organization. In freefall most skydivers start by learning to maintain a stable belly to earth "box" position. In this position the average fallrate is around 125 mph. Learning a stable box position is a basic skill essential for a reliable parachute deployment. Next, jumpers learn to move or turn in any direction while remaining belly to earth. Using these skills a group of jumpers can create sequences of formations on a single jump, a discipline known as relative work (RW). In the late 1980s more experienced jumpers started experimenting with freeflying, falling in any orientation other than belly to earth. Today many jumpers start freeflying soon after they earn their license, bypassing the RW stepping stone. Choosing when to deploy the parachute is a matter of safety. A parachute should be deployed high enough to give the parachutist time to handle a malfunction should one occur. Two thousand feet is the practical minimum for advanced skydivers. In freefall, skydivers monitor their altitude meters to decide when to break off from the formation (if applicable) and when to open their parachutes. Many skydivers open higher to practice flying their parachute. On a "hop-and-pop," a jump in which the parachute is immediately deployed upon exiting the aircraft, it is not uncommon for a skydiver to be under canopy as high as 4000 or 5000 feet. Flying the parachute has two basic challenges: to land where planned, often on a target; and to avoid injury. On a more advanced note, some skydivers enjoy performing aerobatic maneuvers with parachutes. An example of this would be the "Swoop", an extremely exciting, but dangerous skill which entails a fast speed approch towards the ground, and then levelling off a couple of feet above the ground to cover as much distance as possible (as much as 600 feet). terminal velocityA modern parachute or canopy "wing" can glide substantial distances. Elliptical canopies go faster and farther, and some small, highly loaded canopies glide faster than a man can run, which can make them very challenging to land. A highly experienced skydiver using a very small canopy can achieve over 60 mph horizontal speeds in landing. A good landing will not have any discomfort at all, and will land the skydiver within a few feet of his intended location. Champion accuracy skydivers routinely land less than two inches from the center of a target even in competitions. Nowadays, most of the skydiving related injuries happen under a fully opened and functioning parachute, the most common reasons for these injuries are badly-executed, radical maneuvers near to the ground, like quick turns, or too-low or too-high landing flares.

Safety

Despite the seeming danger of the leap, fatalities are rare. About 30 skydivers are killed each year in the US out of roughly 100,000 jumpers [http://stuffo.howstuffworks.com/skydiving8.htm]. In the US and in most of the western world skydivers are required to carry a second, reserve parachute which has been inspected and packed by a certified parachute rigger (in the US, an FAA certified parachute rigger), and many now use an altitude-sensitive automatic activation device (AAD) that activates the reserve parachute at a safe altitude if the skydiver somehow fails to activate the chute on their own. They also routinely carry both visual and audible altimeters to help maintain altitude awareness. Each year, a number of people are hurt or killed in parachuting, world-wide (see [http://www.skydivingfatalities.info/ fatality statistics], or the newer [http://www.dropzone.com/fatalities/ dropzone.com statistics]) The fundamental nature of the sport might suggest why that is so. On the other hand, statistics suggest that, with due care and attention (not to mention sound training and a good attitude) the more likely outcome is that hundreds of thousands of people make millions of jumps, and go back to do it again. A particularly telling point might be the increasing numbers of sport parachutists who have each logged well over 10,000 jumps in their respective careers. Inexperienced skydivers are a substantial hazard in the air. For the first few jumps, many beginners choose to jump in a linked harness, with an instructor in the other harness. Even newly-licensed skydivers sometimes are shunned by groups until they've completed fifty to a hundred jumps, and their experience is personally known to a number of people on the field. For many skydivers this is not nastiness, or elitism, but a simple desire not to have anything broken. The most dangerous period for a skydiver is between 100 and 500 jumps (known as hundred jump wonders), where the jumper has jumped enough to get over the initial fear factor, but has not yet learned all the skills for handling bad situations. Often jumpers with jump numbers in this range are over-confident and somewhat gung-ho. In recent years, one of the most common sources of injury is the inexperienced or overconfident (mis)use of perfectly good, high-performance parachutes to effect crowd-pleasing landings. High-speed maneuvers performed very close to the ground can be exhilarating to perform, and exciting to watch, but they necessarily increase the risk. Changing wind conditions are another risk factor. In strong wind conditions and hot days with turbulence the parachutist can be caught in downdrafts near the ground. Shifting winds causing a crosswind or downwind landing which have a high potential for injury due to the air speed and wind speed adding to give the landing speed. Equipment failure only very rarely causes fatalities and injuries. While approximately one in 400 jumps results in a primary parachute malfunction and cut away, reserve chutes are professionally packed and are designed to be highly reliable, and while a reserve ride is a rather unnerving experience, it does not cause injury. Some skydiving disciplines are notably more dangerous than others. BASE jumping has many times a greater risk than high altitude jumps. Skydive disciplines involving equipment such as wing suit flying and sky surfing have a higher risk factor due to the lower mobility of the jumper and the greater risk of entanglement. For this reason these disciplines are generally restricted to experienced jumpers. It is worth noting that what is depicted in commercial films -- notably Hollywood action movies -- usually exaggerates the dangerous-looking aspects of the sport. Often, the characters in such films are depicted performing feats that are physically impossible without special effects assistance. In other cases, their practices would cause them to be grounded or shunned at any safety-conscious drop zone or club. Drop zones in the US and Canada are required to have a drop zone safety officer (DSO) who are resposible for dealing with the rule breakers. In many countries, either the local regulations or the liability-conscious prudence of the dropzone owners require that parachutists must have attained the age of majority before engaging in the sport.

Types of Parachuting

drop zone Once individuals have mastered the basic jump, there are several different disciplines to embrace within parachuting. Each of these is enjoyed by both the recreational (weekend) and the competitive participants. There is even a small group of professionals who earn their living with parachuting. They win competitions having cash prizes or are employed or sponsored by skydiving related manufacturers. Parachutists can participate both in competitive and in purely recreational skydiving events. World championships are held regularly in locations offering flat terrain and clear skies. An exception is Paraski, where winter weather and ski-hill terrain are required. Types of parachuting include:
- Accuracy landing - Landing as close as possible to a target.
- BASE jumping - From buildings, antennas, bridges (spans) and cliffs (earth).
- Blade running - A kind of slalom with parachute.
- Big-ways - Formation skydiving with many people.
- Canopy formations - Making formations with other parachutists while under canopies. (Known also as canopy relative work or simply CRW)
- Canopy piloting - Also known as 'swooping'.
- Formation skydiving - Making formations during freefall. (Known also as relative work or simply RW)
- Freefall cinematography
- Freefall style
- Freeflying
- Freestyle skydiving
- Military Parachuting
- HALO/HAHO
- Treejumping
- Para-ski
- Skysurfing - Skydiving with a board strapped to your feet.
- Wingsuit flying - Skydiving with a suit which provides extra lift.

Training

There are ways to practice different aspects of skydiving, without actually jumping. Wind tunnels can be used to practice skills for free fall, while virtual reality skydiving simulators can be used to practice parachute control. Beginning skydivers seeking training have a few different options available to them: tandem, static line, IAD, and AFF(Known as PFF in Canada).

Tandem

Tandem jumps are perhaps becoming the most common type of jump selected by first-time or one-time skydivers. The jump is usually done from 10,000+ feet--often as high as 14,000 feet. As mentioned earlier, the jumper is strapped to the front of a jumper, known as the "Tandem Master," who has been specially trained and certified for the specific brand of tandem equipment to be used. This method is popular with those who only want to make one skydive, since it requires very little training to experience freefall. If desired, someone who starts off with a tandem jump can progress into student training to become an experienced jumper.

Static line

In a static line jump, students exit the plane on their own and their parachute is activated as they exit by a static line attached to the aircraft. These initial jumps are usually conducted from 3,500 feet and the student receives one-way radio guidance from an instructor on the ground from deployment until landing. If the student desires to continue training using this method, the first few jumps are static line jumps. After a few static line jumps, students are introduced to new equipment allowing them to deploy their own parachutes. Generally, most modern parachutes are activated by removing a small parachute, about 1 foot in diameter, called a "pilot chute" from a pocket on the rig and throwing it away from the body. This small parachute is inflated and drags out the main parachute. Before allowing students to activate their parachutes on their own, they generally conduct one or two static line jumps simulating throwing out their own pilot chutes. Then, students are gradually introduced to freefall with gradual increases in altitude, first activating after a five-second count. Once students are comfortable activating their own parachutes, they are gradually introduced to use of altimeters and further increases in altitude.

IAD

Instructor Assisted Deployment, or IAD, is the successor to static line. The main difference is that instead of being deployed by a static line, the student's jumpmaster (who is in the plane with them) deploys the student's parachute by throwing the pilot chute out the door as the student exits. Among the benefits to IAD are increased reliability and the ability to use the same parachute equipment as the students will use when they progress to deploying their parachutes on their own.

AFF/PFF

Accelerated Freefall -- AFF -- (known in Canada as Progrssive Freefall -- PFF--) is a method of training preferred by many for those students who are serious about wanting to become skydivers. The "accelerated" comes from the fact that instead of building up the amount of freefall the student is exposed to, the student exits at maximum altitude (9k-14k feet) starting with the first jump. Instructors jump with the student during AFF jumps, and as they freefall with the student, they are able to monitor and correct the student's body position and other problems during freefall. Later exercises include things such as turns, backflips, and being able to dock. During the first several AFF jumps, as with the other training methods, the student has radio contact with ground personnel while they are under canopy.

Parachute Deployment

At a skydiver's designated deployment-altitude; the individual throws the pilot chute from a pocket at the bottom of the rig (the backpack-like container holding both parachutes a.k.a., canopies). This is known as a bottom of container (B.O.C.) deployment system. This small parachute is connected to the main parachute by a cord known as the "bridle" which feeds through a grommet on a small black bag which has the carefully folded parachute inside and the lines stowed through rubber bands across the top. At the bottom of the container's tray which holds the main parachute is a loop which, in the closing sequence of the parachute system, is fed through grommets on each of four flaps that closes the container. Attached to the bridle is a curved pin through which the closing loop is put after it has been fed through each of these grommets. When the pilot chute is thrown out; it catches the wind and pulls the pin out of the closing loop, releasing the black bag off the back of the individual (who is in the stable belly-towards-earth arched position). The lines are pulled loose from the rubber bands and extend as the canopy starts to open. To reduce the risk of injury, A piece of fabric called the "slider" (which has the lines separated into four main groups fed through grommets in the four respective corners) slows the opening of the parachute and works its way down until the canopy is fully open and the slider is just above the head of the skydiver. If a skydiver experiences a malfunction with their main parachute which they cannot correct, they have a "cut-away" handle on the front right-hand side of their container (on the chest) which will release the main chute after which they can activate a reserve handle on the front left (sometimes triggered by a RSL or Reserve Static Line which, if connected, will deploy the spring loaded Reserve Canopy located in the top of the container upon cutting away the main). Recently, a new type of RSL has been developed called the skyhook. This new system uses the "cut-away" canopy as a super-sized pilot chute to deploy the spring loaded reserve canopy. The sky hook is an incredibly fast system that has the jumper under the reserve canopy and flying within 2 seconds (compared to the 5-10 seconds of the old system).

Other Fun Stuff

In addition to the various "disciplines", for which people actually train and purchase specialized equipment and get coaching, the recreational skydiver finds ways to just have fun.

Hit and Rock

One example is "Hit and Rock", which is a variant of Accuracy parachuting devised to let people of varying skill-levels "compete" for fun, while spoofing the age and abilities of some participants. It is a good way to have fun on days when the cloud-cover is high enough to be legally jumpable, but too low for meaningful freefall. In classic accuracy, the parachutist exits at 800 meters, flies a big, boxy, purpose-built parachute toward a dinner-plate sized target with a 3-centimeter dot in the middle. Near the ground, the parachutist aligns above the target and then sinks elevator-style until the target can be poked with a heel. The target has electronic sensors that show the precise distance of that heel-strike from target center. In swoop accuracy, the parachutist exits at whatever altitude, flies a zippy, high-aspect-ratio wing to the vicinity of the target, then executes a diving turn that levels out into a long, high-speed swoop, close over the ground. At some point in that swoop, the parachutist (... excuse me, "canopy pilot") passes over the target and attempts to stab it with a foot on the way by. Both of those styles involve considerable skill, such that junior parachutists would have little hope against people with years of experience. So, to add some fun and frivolity, the target is replaced by a rocking chair. The object now becomes: to land as close as possible to the chair, doff the parachute harness, sprint to the chair, sit fully in the chair and rock back and forth at least one time. The contestant is timed from the moment that feet touch the ground until that first rock is completed.

Pond Swooping

Pond swooping is a form of competitive parachuting wherein parachuters attempt to touch down at a glide across a small body of water, and onto the shore. Events provide lighthearted competition rating accuracy, duration spent skimming the surface of the water, and style. Points and peer approval are reduced when a participant "chows", or fails to reach shore and sinks into the water.

Hit and Chug

Very similar to Hit and Rock, except the target is replaced by a crate of beer bottles with screwtop caps. Contestants are timed from the moment their feet touch the ground until the they drink a bottle of beer and place the empty bottles upside-down. Of course, it must be mentioned that dropzones enforce strict rules prohibiting anyone from jumping any more that day once alcohol has been consumed.

Cross-Country

A cross-country jump refers to a skydive where the participants open their parachutes immediately after opening, with the intention of covering as much ground under canopy as possible.

Tracking jump

Tracking is assuming a body position that maximizes horizontal speed while minimising vertical speed. It is most commonly used at the end of freefall to gain enough separation from other skydivers for a safe parachute deployment. A tracking dive is a skydive where the intention is to track for the entire duration of freefall. One person, usually the most experienced tracker, is designated the leader (or "rabbit"). The rabbit directs the direction of the group and maintains the groups tracking speed. Other participants chase the rabbit and try to maintain a relative position. See also Freeflying/Tracking

Camera Flying

In camera flying, a cameraman (or camerawoman) jumps with other skydivers and films them. The camera flyer often wears specialized equipment, such as a winged jumpsuit to provide a greater range of fallrates, helmet-mounted video and still cameras, mouth operated camera switches, and special optical sights. Some skydivers specialize in camera flying and a few earn significant fees for filming students on coached jumps or tandem-jumpers, or producing professional footage and photographs for the media. There is always a demand for good camera flyers in the skydiving community, as many of the competitive skydiving disciplines are judged from a video record.

Night Jumps

Skydiving is not always restricted to daytime hours. Experienced skydivers sometimes perform night jumps. For obvious safety reasons, this requires more equipment than a usual daytime jump and in most jurisdictions requires both an advanced skydiving licence and specialized training (night rating). A lighted altimeter (preferably accompanied with an audible altimeter) is a must. Skydivers performing night jumps often take flashlights up with them so that they can check their canopies once they deploy, so they can be assured that the canopy has opened correctly and is safe to fly and land. Visibility to other skydivers and other aircraft is also a consideration; FAA regulations require skydivers jumping at night to be wearing a light visible for three miles in every direction, and to turn it on once they are under canopy.

Stuff Jumps

Skydivers are always looking for somthing new to do in the air. With the availability of a rear door aircraft and a large, unpopulated space to jump over 'stuff' jumps become possible. In thse jumps the skydivers jump out with some object. Rubber raft jumps are popular, where the jumpers sit in a rubber raft. Cars, Bikes, Motorcycles, water tanks and inflatable companions have also been thrown out the back of an aircraft. At a certain height the jumpers break off from the object and deploy their parachutes, leaving it to crash into the ground at high speed.

Parachuting organizations

National parachuting associations exist in many countries (many affiliated with the Fédération Aéronautique Internationale (FAI)), to promote their sport. In most cases, national representative bodies, as well as prudent local dropzone operators, require that participants carry certification, attesting to their training, their level of experience in the sport, and their proven competence. Anyone who cannot produce such bona-fides is treated as a student, requiring close supervision. Within the sport, associations promote safety, technical advances, training-and-certification, competition and other interests of their members. Outside their respective communities, they promote their sport to the public, and often intercede with government regulators. Competitions are organized at regional, national and international levels in most these disciplines. Some of them offer amateur competition. Many of the more photogenic/videogenic variants also enjoy sponsored events with prize money for the winners. The majority of jumpers tend to be non-competitive, enjoying the opportunity to "get some air" with their friends on weekends and holidays. The atmosphere of their gatherings is relaxed, sociable and welcoming to newcomers. Party events, called "boogies" are arranged at local, national and international scale, each year, attracting both the enthusiatic young jumpers and many of their elders -- Parachutists Over Phorty (POPs), Skydivers Over Sixty (SOS) and even older groups who have yet to choose a catchy name for themselves. Fédération Aéronautique Internationale

Commercial parachuting services vs. parachuting clubs

At larger centers, mostly in "sun-belt" locations, training in the sport is often conducted by professional instructors and coaches at commercial establishments. The advantages to the newcomer are year-round availability, larger aircraft (which translates to greater comfort, higher jump altitudes, and more frequent jumping), and staff who are very current in both their sport and their instructional skills. It is also common for instructors and newcomers to jump while strapped together (see picture). For the newcomer, this gives an added measure of safety should something go wrong. In the other latitudes, where winter (or monsoon) gets in the way of year-round operation, commercial skydiving centers are less prevalent and much of the parachuting activity is carried on by clubs. Most clubs cannot support larger aircraft. Training may be offered (by volunteer instructors who, nevertheless, are rigorously tested and certified) only in occasional classes as demand warrants. These clubs are usually weekend only operations as the volunteers have full-time jobs during the week. The entire experience tends to be informal and surrounded by a lot of socializing. Some observers have suggested that commercial operations cater to a "fast-food" sensibility that leaves their novice graduates with very compartmentalized skill sets that may be lacking in important peripheral areas. This is countered by the observation that students at busy commercial operations receive concentrated exposure and experience, and are thus able to improve rapidly without backtracking or developing bad habits. The observation about participants who started learning in the club setting is that their progression can be slower due to smaller aircraft and fewer "good jumping days" (weather). They may experience some backsliding as they need to re-learn some skills after weather-enforced lay-offs. By contrast, the progression of a novice in a club usually involves learning all the ancillary skills out of necessity. Everyone at a club learns all the skills and takes on all the roles. For example, a large aircraft must be "spotted" (directed to fly over the optimum exit point) by an experienced jumper who is usually a parachute-center staffer. Having experienced staff perform this duty ensures that everybody leaves the aircraft within range of the landing zone. Nobody needs to hike or take a taxi back to the dropzone because their jumprun was spotted by a novice. The downside is that the novices never learn the skill of reading the winds, the terrain and the aircraft movement, and of directing the aircraft where it should go. They remain dependent on the "pro." At clubs, the aircraft are smaller, and everybody is a friend. A bad spot is an excuse for some teasing, but it doesn't interrupt the smooth flow of a moneymaking operation. Therefore, most people who join parachuting clubs are taught spotting skills very early in their careers. Similar contrasts apply to parachute packing, equipment maintenance and other skills of a well-rounded skydiver. The answer to both sets of critics is that they are correct as far as they go. The perceived shortcomings of each learning environment are ameliorated by the fact that most skydivers eventually partake of both settings. Club members often visit larger centers for holidays and events and for some concentrated exposure to the latest techniques. People who learned at commercial centers often make friends with visiting club jumpers and then visit them at their home dropzones -- or start their own clubs.

Equipment

Costs in the sport are not trivial. As new technological advances or performance enhancements are introduced, they tend to nudge equipment prices higher. Similarly, the average skydiver carries more equipment than in earlier years, with safety devices (such as an automatic reserve activation device) contributing a significant portion of the cost. A full set of brand-new equipment can easily cost as much as a new motorcycle or half a small car. The market is not large enough to permit the commoditization and price-erosion that is seen in other technologically intensive industries (like the computer industry). In many countries, the sport supports a substantial used-equipment market. For many beginners, especially those with limited funds, that is the preferred way to acquire "gear", and has two advantages:
- First, they can try different types of parachutes (there are many) to learn which style they prefer, before paying the price for new equipment.
- Second, they can acquire a complete system and all the peripheral items in a short time and at reduced cost. Novices generally start with parachutes that are large and docile relative to the jumper's body-weight. As they improve in skill and confidence, it is customary to graduate to smaller, faster, more responsive parachutes. An active jumper might change parachute canopies several times in the space of a few years, while retaining his or her first harness/container and peripheral equipment. Older jumpers, especially those who jump only on weekends in summer, sometimes tend in the other direction, selecting slightly larger, more gentle parachutes that do not demand youthful intensity and reflexes on each jump. They may be adhering to the maxim that: "There are old jumpers and there are bold jumpers, but there are no old, bold jumpers." Most parachuting equipment is ruggedly designed and is enjoyed by several owners before being retired. Purchasers are always advised to have any potential purchases examined by a qualified parachute rigger. A rigger is trained to spot signs of damage or misuse. Riggers also keep track of industry product and safety bulletins, and can therefore determine if a piece of equipment is up-to-date and serviceable.

External links

- [http://www.dropzone.com Dropzone.com] - The single best source for skydiving information
- [http://www.fai.org FAI] The Federation Aeronautique Internationale -- The international governing body for all airborne sports.
- [http://www.uspa.org USPA] The United States Parachute Association -- The governing body for sport skydiving in the U.S.
- [http://www.cspa.ca CSPA] The Canadian Sport Parachuting Association -- The governing body for sport skydiving in Canada.
- [http://www.extremesportscafe.com/skydiving1.html Skydiving Advice Globally. Free Service]
- [http://www.aero.com/publications/parachutes/9511/pc1195.htm]- A brief website about the history and the etomology of the parachute
- [http://inventors.about.com/library/inventors/blparachute.htm]- History, Design, and Information about parachutes.
- [http://www.skygod.com/quotes/skydive.html Parachute Quotations]

Notes

Malone, Jo (June, 2000). [http://www.bpa.org.uk/skydive/pages/articles/jun00/birthoffreefly.htm Birth of Freefly]. Skydive the Mag. Phen (September, 2005). [http://www.phentree.com Kickass site]. Live on the internet. Category:Parachuting ja:スカイダイビング

Sport

:Sports redirects here. For other senses of that word, see sports (disambiguation). A sport consists of a physical activity or skill carried out with a recreational purpose: for competition, for self-enjoyment, to attain excellence, for the development of a skill, or some combination of these. A sport has physical activity, side by side competition, and a scoring system. The difference of purpose is what characterises sport, combined with the notion of individual (or team) skill or prowess.

History of sport

Main article: History of sport The development of sport throughout history teaches us a great deal about social changes, and about the nature of sport itself. There are many modern discoveries in France, Africa, and Australia of cave art (see, for example, Lascaux) from prehistory which provide evidence of ritual ceremonial behaviour. Some of these sources date from over 30,000 years ago, as established by carbon dating. Although there is scant direct evidence of sport from these sources, it is reasonable to extrapolate that there was some activity at these times resembling sport. There are artifacts and structures which suggest that Chinese people engaged in activities which meet our definition of sport as early as 4000 BC. Gymnastics appears to have been a popular sport in China's past. Monuments to the Pharaohs indicate that a range of sports were well developed and regulated several thousands of years ago, including swimming and fishing. Other sports included javelin throwing, high jump, and wrestling. Ancient Persian sports such as the traditional Iranian martial art of Zurkhaneh had a close connection to the warfare skills. Among other sports which originate in Persia are polo and jousting. A wide range of sports were already established at the time of the Ancient Greece. Wrestling, running, boxing, javelin, discus throwing, and chariot racing were prevalent. This suggests that the military culture of Greece was an influence on the development of its sports and vice versa. The Olympic Games were held every four years in Ancient Greece, at a small village in Pelopponisos called Olympia. Sport has been increasingly organised and regulated from the time of the Ancient Olympics up to the present century. Activities necessary for food and survival became regulated activities done for pleasure or competition on an increasing scale, for example hunting, fishing, horticulture. The Industrial Revolution and mass production brought increased leisure which allowed increases in spectator sports, less elitism in sports, and greater accessibility. These trends continued with the advent of mass media and global communication. Professionalism became prevalent, further adding to the increase in sport's popularity. Not only has professionalism helped increase the popularity of sports, but additionally the need to have fun and take a break from a hectic workday or to relieve unwanted stress, as with any profession.

A classification of sports

Main article: List of sports One system for classifying sports is as follows, based more on the sport's aim than on the actual mechanics. The examples given are intended to be illustrative, rather than comprehensive.

Opponent

- Combat (Wrestling, Judo, karate, boxing, fencing, tae kwon do...)
- Court (Tennis, shuttlecock sport, badminton, volleyball, squash, Table tennis...)
- Team (Baseball, cricket and football (soccer) are the most popular globally, with baseball being popular in the Americas and in Japan, cricket in the Commonwealth of Nations and football being popular throughout the world. Other examples include: Rugby, ice hockey, field hockey, softball, basketball, American Football...)

Achievement

- Target (Archery, shooting ...)
- Display (Gymnastics, bodybuilding, equestrianism, diving...)
- Strength (Weight-lifting, triple jump, shot put ...)

Sports that fall into multiple categories

- Biathlon
- Curling
- Paintball

Sportsmanship

Sportsmanship is defined as "conduct and attitude considered as befitting participants, including a sense of fair play, courtesy toward teammates and opponents, a striving spirit, and grace in losing." It is interesting that the motivation for sport is often an elusive element. For example, beginners in sailing are often told that dinghy racing is a good means to sharpen the learner's sailing skills. However, it often emerges that skills are honed to increase racing performance and achievements in competition, rather than the converse. Sportsmanship expresses an aspiration or ethos that the activity will be enjoyed for its own sake. The well-known sentiment by sports journalist Grantland Rice, that it's “not that you won or lost but how you played the game," and the Modern Olympic creed expressed by its founder Pierre de Coubertin: "The most important thing . . . is not winning but taking part” are typical expressions of this sentiment. But often the pressures of competition (See the related article, "Winning isn't everything; it's the only thing." or an obsession with individual achievement - as well as the intrusion of technology - can all work against enjoyment and fair play by participants. People responsible for leisure activities often seek recognition and respectability as sports by joining sports federations such as the IOC, or by forming their own regulatory body. In this way sports evolve from leisure activity to more formal sports: relatively recent newcomers are BMX cycling, snowboarding, wrestling, etc. Some of these activities have been popular but uncodified pursuits in various forms for different lengths of time. Indeed, the formal regulation of sport is a relatively modern and increasing development. Sportsmanship, within any given game, is how each competitor acts before, during, and after the competition. Not only is it important to have good sportsmanship if one wins, but also if one loses. For example, in football it is considered sportsmanlike to kick the ball out of play to allow treatment for an injured player on the other side. Reciprocally, the other team is expected to return the ball from the throw-in. Compare Sportsmanship with Gamesmanship. Violence in sports involves crossing the line between fair competition and intentional aggressive violence. Athletes, coaches, fans, and parents sometimes unleash violent behaviour on people or property, in misguided shows of loyalty, dominance, anger, or celebration.

Professionalism and the regulation of sport

The entertainment aspect of sport, together with the spread of mass media and increased leisure time, has led to professionalism in sport. This has resulted in some conflict, where the paycheck can be seen as more important than recreational aspects: or where the sport is changed simply to make it more profitable and popular therefore losing some of the traditions valued by some. The entertainment aspect also means that sportsmen and women are often elevated to celebrity status, or in some cases near-god-like. Today the consensus is that David Beckham (England and Real Madrid Footballer) is the most famous sportsman in the world, with a fanatical following particularly in Asia where statues have been erected of his likeness. The successful execution of a sport requires the consensus agreement of the participants on a set of rules for fair competition. This has led to the control of each sport through a regulatory body to define what methods of competition are acceptable and what are considered cheating.

Sport and politics

There have been many dilemmas for sports where a difficult political context is in place. When apartheid was the official policy in South Africa, many sportspeople adopted the conscientious approach that they should not appear in competitive sports there. Some feel this was an effective contribution to the eventual demolition of the policy of apartheid, others feel that it may have prolonged and reinforced its worst effects. The 1936 Summer Olympics held in Berlin was an illustration, perhaps best recognised in retrospect, where an ideology was developing which used the event to strengthen its spread through propaganda. In the history of Ireland, Gaelic sports were connected with cultural nationalism. Even until the mid 20th century a person could have been banned from playing Gaelic football, hurling, or other sports administered by the GAA if s/he played or supported Football, or other games seen to be of British origin. Until recently the GAA continued to ban the playing of soccer and Rugby union at Gaelic venues under the controversial Rule 42, although Gaelic games are frequently played on soccer and rugby arenas, particularly outside of Ireland. Until recently, under Rule 21, the GAA also banned members of the British security forces and members of the RUC, now reconstituted as the PSNI, from playing Gaelic games, but the advent of the Good Friday Agreement in 1998 led to the eventual removal of the ban. Nationalism in general is often evident in the pursuit of sport, or in its reporting: people compete in national teams, or commentators and audiences can adopt a partisan view. These trends are seen by some as contrary to the fundamental ethos of sport being carried on for its own sake, for the enjoyment of its participants. See also: List of countries by national sport

Art and sport

Sport has many affinities with art. Ice skating and Tai chi, for example, are sports that come close to artistic spectacles in themselves: to watch these activities comes close to the experience of spectating at a ballet. Similarly, there are other activities that have elements of sport and art in their execution, such as performance art, artistic gymnastics, Bodybuilding, Parkour, Yoga, dressage, etc. The fact that art is so close to sport in some situations is probably related to the nature of sport. The definition of "sport" above put forward the idea of an activity pursued not just for the usual purposes, for example, running not simply to get places, but running for its own sake, running as well as we can. This is similar to a common view of aesthetic value, which is seen as something over and above the strictly functional value coming from an object's normal use. So an aesthetically pleasing car is one which doesn't just get from A to B, but which impresses us with its grace, poise, and charisma. In the same way, a sporting performance such as jumping doesn't just impress us as being an effective way to avoid obstacles or to get across streams. It impresses us because of the ability, skill, and style which is shown. Art and sport were probably more clearly linked at the time of Ancient Greece, when gymnastics and calisthenics invoked admiration and aesthetic appreciation for the physical build, prowess and 'arete' displayed by participants. The modern term 'art' as skill, is related to this ancient Greek term 'arete'. The closeness of art and sport in these times was revealed by the nature of the Olympic Games which, as we have seen, were celebrations of both sporting and artistic achievements, poetry, sculpture and architecture.

The terms 'sport' and 'sports'

In Commonwealth English, sporting activities are commonly denoted by the collective noun "sport". In American English, "sports" is more common for this usage. In all English dialects, "sports" is the term used for more than one specific sport. For example, "football and swimming are my favourite sports" would sound natural to all English speakers, whereas "I enjoy sport" would sound less natural than "I enjoy sports" to many North Americans.

External links

- [http://www.sports.ie Sports.ie - Live Sports news and RSS feeds]
- [http://www.thefamousquotations.com/subjects/sports-and-competition-quotations.htm Sports Quotations]
- [http://www.newworldsports.net New World Sports - Sports Commentary]
- [http://www.pressboxnews.com/ Sports News Aggregator]
- [http://dmoz.org/Sports/ Open Directory Project - Sports]
- [http://dir.yahoo.com/Recreation/Sports/ Yahoo! - Sports]
- [http://news.google.com/news?topic=s Google - Sports News]
- [http://uk.newsbot.msn.com/s/?id=2 MSN - Sports News] (UK)
- [http://news.yahoo.com/news?tmpl=index&cid=755 Yahoo! - Sports News]
- [http://www.sportsfilter.com SportsFilter - Community Weblog]
- [http://www.kungfufollowme.com/ Chinese Kung Fu: Tai Chi And Shaolin Kung Fu]
- [http://www.sports-facts.com/ Sports-Facts.Com!] Category:Games
- Category:Technology ko:스포츠 ms:Sukan ja:スポーツ simple:Sport th:กีฬา

Free-fall

Free-fall or free fall in the strict sense is the condition of acceleration which is due only to gravity. In other words, the objects undergoing free fall experience only one force: their own weight. Examples include:
- a spacecraft with the rockets off
- the Moon's trajectory around the Earth, or the Earth's orbit around the Sun.
- on Earth, falling through a vacuum tube or shaft, e.g.:
- for a physics demonstration
- at NASA's Zero-G Research Facility as opposed to the cases where other forces are acting, including:
- standing on the ground, sitting in a chair on the ground, etc. (gravity is cancelled by the reaction force of the ground)
- flying in a plane (gravity is cancelled by the lift the wings provide) - see below for special trajectories which form an exception
- atmospheric reentry, landing on a parachute: gravity is opposed by atmospheric drag
- during an orbital maneuver in a spacecraft: the rocket provides thrust thrust More generally, free fall is the condition of acceleration which is due only to gravity and air friction: in parachuting, free fall (skydiving) refers to the act of falling and delaying the opening of a parachute. Freeflying is skydiving in other body positions than the more standard belly flying. With air friction acting upon an object that has been dropped the object will eventually reach terminal velocity (around 120 miles/hour for a human body flying in the belly-down arched position; terminal velocity depends on many factors including mass, drag coefficient, and relative surface area) if the fall is from sufficient altitude (2,000 ft) and also otherwise uninterrupted.

People surviving free fall

At least three airmen have survived free falls of around 20,000 ft (6,000 m) without a parachute in the Second World War; Lt. I.M. Chisov was a Russian bomber, Sgt. Alan Magee an American gunner on a B-17, and Sgt. Nicholas Alkemade a British gunner on a Lancaster bomber. It is estimated that a person free falling horizontally, reaches a terminal velocity of around 120 mph (200 km/h) after a fall of just 2,000 ft (600 m), so the additional 18,000 ft (5,500 m) doesn't make these falls that much more dangerous, apart from the lack of oxygen at high altitude. All three men lost consciousness during their falls, and two of them landed on terrain covered in deep snow, which was probably a significant factor in the survivability of the falls. Vesna Vulović, a flight attendant from Yugoslavia, survived a fall from 10,160 m (33,330 ft) when the DC-9 airplane she was traveling in blew up over Srbská Kamenice, Czechoslovakia, on January 26, 1972. She remained strapped into her flight attendant's seat in the tail section of the plane, which remained attached to the washrooms. The assembly struck the snow-covered flank of a mountain. A terrorist bomb was thought to be the cause. Vulović broke both legs and was temporarily paralyzed from the waist down. No other passengers survived. [http://www.guinnessworldrecords.com/content_pages/record.asp?recordid=43941] Stories about desperate Russians deploying paratroopers without parachutes (unsuccessfully) during World War II are most likely fabricated. [http://www.greenharbor.com/fffolder/questions.html#anchor1234559] It is reported that two of the victims of the Lockerbie bombing survived for a brief period after hitting the ground.

Record free fall

Lockerbie bombing As part of Project Excelsior on 16 August 1960, Joseph Kittinger achieved the record for the longest free fall jump and the fastest maximum speed of 614 mph (982 km/h), before opening his parachute at around 18,000 feet (5,500 m). Kittinger started the jump from a specially constructed balloon at an altitude of 102,800 feet (31,300 m), which also qualified him for the highest balloon ascent and highest parachute jump. Some people claim that Kittinger's jump wasn't true free-fall as he used a drogue chute for stability. According to the Guinness book of records, Eugene Andreev (USSR) holds the official FAI record for the longest free-fall parachute jump after falling for 80,380 ft (24,500 m) from an altitude of 83,523 ft (24,458 m) near the city of Saratov, Russsia on November 1, 1962. Andreev did not use a drogue chute during his jump.

References

- [http://www.greenharbor.com/fffolder/ffresearch.html Free fall accidents, mathematics of free fall - detailed research on the topic]
- [http://members.aol.com/MercStG/FFAccPage1.html Free fall accidents] and [http://www.parachutehistory.com/other/bonusday.html parachute history] Category:Gravity Category:Parachuting Category:Introductory physics ko:자유 낙하

Parachute

A parachute is a soft fabric device used to slow the motion of an object through an atmosphere by creating drag. Parachutes are generally used to slow the descent of a person or object to Earth or another celestial body with an atmosphere. Parachutes are also sometimes used to aid horizontal deceleration of a vehicle (an airplane or space shuttle after touchdown, or a drag racer). The word parachute comes from the French words para, protect or shield, and chute, to fall. Therefore parachute actually means to protect from a fall. Many types of modern parachute are quite maneuverable, and some can be flown like gliders. Parachutes were once made from silk but these days are almost always constructed from more durable woven nylon fabrics, sometimes coated with a zero porosity coating to improve performance and consistency over time.

History

A few medieval documents record the use of parachute-like devices to allow a person to fall (somewhat) safely from a height. In 852, an Andalusian daredevil named Armen Firman jumped from a tower in Cordoba using a loose cloak stiffened with wooden struts to arrest his fall, sustaining only minor injuries. In 1178, another Muslim attempted a similar feat in Constantinople, but he broke several bones and later died of his injuries. According to Joseph Needham there were working parachutes in China as early as the twelfth century. twelfth century.]] Leonardo da Vinci sketched a parachute while he was living in Milan around 1485. However, the idea of the parachute may not have originated with him: the historian Lynn White has discovered an anonymous Italian manuscript from about 1470 that depicts two designs for a parachute, one of which is very similar to da Vinci's. The first known test of such a parachute was made in 1617 in Venice by the Croatian inventor Faust Vrančić. A 1595 sketch of Vrančić's parachute is at left. The parachute was re-invented in 1783 by Sebastien Lenormand in France. Lenormand also coined the name parachute. Two years later, Jean-Pierre Blanchard demonstrated it as a means of safely disembarking from a hot air balloon. While Blanchard's first parachute demonstrations were conducted with a dog as the passenger, he later had the opportunity to try it himself when in 1793 his hot air balloon ruptured and he used a parachute to escape. Subsequent development of the parachute focused on it becoming more compact. While the early parachutes were made of linen stretched over a wooden frame, in the late 1790s, Blanchard began making parachutes from folded silk, taking advantage of silk's strength and light weight. In 1797, André Garnerin made the first jump using such a parachute. Garnerin also invented the vented parachute, which improved the stability of the fall. Gleb Kotelnikov invented the first knapsack parachute, later popularized by Paul Letteman and Kathchen Paulus. At San Francisco in 1885, Thomas Scott Baldwin was the first person in the United States to descend from a balloon in a parachute. On March 1, 1912, US Army Captain Albert Berry made the first parachute jump from a moving airplane over Missouri. Štefan Banič from Slovakia invented the first actively used parachute, patenting it in 1913. The first military use for the parachute was for use by artillery spotters on tethered observation balloons in World War I. These were tempting targets for enemy fighter aircraft, though difficult to destroy, due to their heavy antiaircraft defenses. Because they were difficult to escape from, and dangerous when on fire due to their hydrogen inflation, observers would abandon them and descend by parachute as soon as enemy aircraft were seen. The ground crew would then attempt to retrieve and deflate the balloon as quickly as possible. Aircraft crews, however, were forbidden from carrying their own parachutes. It was believed to encourage a lack of nerve in action. As well, early parachutes were very heavy, and fighters lacked the performance to carry the additional load through most of WW1. Only in 1918 did the German air service become the world's first to introduce a standard parachute. The first emergency freefall parachute jump ended in a grape arbor in the back yard of the still-standing house at 335 Troy St in Dayton, Ohio. The jump was made by McCook Field test pilot Lt. Harold H. Harris on Oct 20, 1922. Harris' airplane crashed three blocks away in the yard of a double house that once stood at 403 Valley Street.

Uses

McCook Field Paratroopers (now called airborne, Soviet/Russian desantniki) are soldiers who arrive in enemy territory by parachutes. Smokejumpers are firefighters who parachute into remote areas to build firebreaks. Most space vehicles descend to Earth using several parachutes. The pair of reusable solid-fuel rocket boosters (SRB) of the Space Shuttle have parachutes; they are recovered after falling to the ocean. Some exploration rovers (such as NASA's Spirit and ESA's Beagle 2) descend to their target destination with parachutes. Early reconaissance satellites ejected a film pack that came to earth and was recovered from under its parachute by specially-equipped aircraft. Some bombs are equipped with a parachute, such as the World War Two "parafrag" (an 11kg fragmentation bomb), the Vietnam-era daisy cutters, and the bomblets of some modern cluster bombs. Parachutes slow the bomb's descent, thus giving the dropping aircraft time to get to a safe distance from the explosion. (This is especially important with airburst nuclear weapons.) Food aid packages are sometimes delivered by parachute, and military forces routinely drop cargo on pallets under parachutes. Heavy loads have used a special system which uses a braking rocket. Parachutes (commonly called "drag 'chutes") can also be deployed from a jet aircraft horizontally from the tail cone at the point of touchdown or shortly afterwards to shorten its landing run, for example if landing on an aircraft carrier or with a tailwind, or on a relatively short runway. The parachute will normally be jettisoned after the aircraft has slowed to taxiing speed and then retrieved by ground crew. This technique reduces the chance of it becoming entangled with the airframe. A similar parachute is used to slow the Space Shuttle after touchdown. Drag racers use a related technique. Jet fighter ejector seats are equipped with automatically deployed parachutes. Aircraft flight testing has also used parachutes on aircraft to provide additional safety. A recent development led to a method able to safely bring down an entire general aviation aircraft (with passengers), the Ballistic Recovery System. Parachuting is a hobby and sport based on human parachute jumps. Paragliding instead uses a parafoil as a form of glider. A paraglider with a motor and possibly wheels is called a powered parachute or, sometimes, a paraplane.

Design

General

A parachute is made from thin, lightweight fabric, support tapes and suspension lines. The lines are usually gathered through loops or rings at the ends of several strong straps called risers. The risers in turn are attached to the harness containing the load.

Deployment systems

Freefall deployed parachutes are pulled out of their containers by a smaller parachute called a pilot chute. A way of deploying a parachute directly after leaving the aircraft is the static line. One end of the static line is attached to the airplane, and the other to the deployment system of the parachute container.

Types of parachutes

Round parachutes

static line Round parachutes, which are pure drag devices(ie. they provide no lift like the ram-air types), are used in military, emergency and cargo applications. These have large dome-shaped canopies made from a single layer of cloth. Some skydivers call them "jellyfish 'chutes" because they look like dome-shaped jellyfish. Rounds are rarely used by skydivers these days. Some round parachutes are steerable, but not to the extent of the ram-air parachutes. An example of a steerable round is provided in the picture of the paratroopers canopy; It is not ripped or torn but has a "T-U cut". This kind of cut allows air to escape from the back of the canopy, providing the parachute with limited forward speed. This gives the jumpers the ability to steer the parachute and to face into the wind to slow down the horizontal speed for the landing.

Annular & pull down apex parachutes

A variation on the round parachute is the pull down apex parachute, essentially a round parachute but with suspension lines to the canopy apex that applies load there and therefore pulls the apex closer to the load distorting the round shape into a somewhat flatenned shape often these designs have the fabric removed from the apex to open a hole through which air can exit, giving the canopy an annular geometry. Annular pull down apex designs tend to be stable while offering an increase in drag and therefore reduction in decent rate for the pack volume of the canopy.

Ribbon and ring parachutes

Ribbon and ring parachutes have similarities to annular designs, they can be designed to open at speeds as high as Mach 2 (two times the speed of sound). These have a ring-shaped canopy, often with a large hole in the center to release the pressure. Sometimes the ring is broken into ribbons connected by ropes to leak air even more. The large leaks lower the stress on the parachute so it does not burst when it opens. Often a high speed parachute slows a load down and then pulls out a lower speed parachute. The mechanism to sequence the parachutes is called a "delayed release" or "pressure detent release" depending on whether it releases based on time, or the reduction in pressure as the load slows down.

Ram-air parachutes

Most modern parachutes are self-inflating "ram-air" airfoils known as a parafoil that provide control of speed and direction similar to paragliders. Paragliders have much greater lift and range, but parachutes are designed to handle, spread and mitigate the stresses of deployment at terminal velocity. All ram-air parafoils have two layers of fabric; top and bottom, connected by shaped fabric I-beams and/or gores. The space between the two fabric layers fills with high pressure air from vents that face forward on the leading edge of the airfoil. The fabric is shaped and the parachute lines trimmed under load such that the ballooning fabric inflates into an airfoil shape.

Personnel parachutes

terminal velocity

Reserves

Paratroopers and sports parachutists carry two parachutes. The primary parachute is called a main parachute, the second, a reserve parachute. The jumper uses the reserve if the main parachute fails to operate correctly. Reserve parachutes were introduced in World War II by the US Airborne Unit, and are now almost universal. For human jumpers only emergency bail-out rigs have a single parachute rather than two and these tend to be of round design.

Deployment

Reserve parachutes usually have a ripcord deployment system, but most modern main parachutes used by sports parachutists use a form of hand deployed pilot chute. A ripcord system pulls a closing pin (sometimes multiple pins) which releases a spring loaded pilot chute and opens the container, the pilot chute is propelled into the air stream by it's spring then uses the force generated by passing air to extract a deployment bag containing the parachute canopy, to which it is attached via a bridle. A hand deployed pilot chute once thrown into the air stream pulls a closing pin on the pilot chute bridle to open the container then the same force extracts the deployment bag. There are variations on hand deployed pilot chutes but the system described is the more common throw-out system. Only the hand deployed pilot chute may be collapsed automatically after deployment by a kill line reducing the in flight drag of the pilot chute on the main canopy. Reserves on the other hand do not retain their pilot chutes after deployment. The reserve deployment bag and pilot chute is not connected to the canopy in a reserve system, this is known as a free bag configuration and the components are often lost during a reserve deployment. Occasionally a pilot chute does not generate enough force to either pull the pin or extract the bag, causes may be that the pilot chute is caught in the turbulent wake of the jumper (the burble), the closing loop holding the pin is too tight or the pilot chute is generating insufficient force, this effect is known as pilot chute hesitation and if it does not clear in can lead to a total malfunction requiring reserve deployment. Paratrooper main parachutes are usually deployed by static lines which release the parachute yet retain the deployment bag which contains the parachute without relying on a pilot chute for deployment, in this configuration the deployment bag is known as a direct bag system, the deployment is rapid, consistent and reliable. This kind of deployment is also used by student skydivers going through a static line progression, a kind of student program.

Varieties of personnel ram-airs

Personnel ram-air parachutes are loosely divided into two varieties. High performance ram-air parachutes have a slightly elliptical shape to their leading and trailing edges when viewed in plan form and are known as ellipticals. These are usually only used by sports parachutists. Usually they have smaller, more numerous fabric cells and are shallower in profile. Lower performance parachutes look more like square inflatable air-mattresses with open front ends. Smaller parachutes tend to fly faster for the same load and ellipticals respond faster to control input, small elliptical designs are therefore often chosen by experienced canopy pilots for the thrill of the flying they provide. This requires much more skill and experience to pilot and is considerably more dangerous to land. With high performance elliptical canopy designs nuisance malfunctions can be much more serious than with a square design and may quickly escalate into emergencies. All reserve ram-air parachutes are of the square variety because of the reliability and handling characteristics.

General charasteristics of ram-airs

Main parachutes used by skydivers today are designed to open softly, rapid deployment was an early problem with ram-air designs. The primary innovation that slows the deployment of a ram-air canopy is the slider; a small rectangular piece of fabric with a grommet near each corner through which four collections of lines are routed to the risers. During deployment the slider slides down from the canopy to just above the risers, the slider is slowed by air resistance as it descends and reduces the rate at which the lines can spread and therefore the speed at which the canopy can open and inflate. The overall design of a parachute still has a significant influence on the deployment speed. Modern sport parachutes deployment speed varies considerably between designs but most modern parachutes open comfortably with individual skydivers preferring different deployment speeds. The deployment process is inherently a chaotic one and rapid deployments can still occur even with well behaved canopies, on rare occasions deployment can even be so rapid that the jumper suffers bruising or even injury. Emergency and reserve parachutes by design tend to deploy more rapidly than sports main canopies, they still have sliders but the sliders are designed to descend rapidly with for example a partial mesh construction to catch less air resistance than a fully fabric slider design.

Safety

A parachute is carefully folded, or "packed" to ensure that it will open reliably. In the U.S. and many developed countries, emergency and reserve parachutes are packed by "riggers" who must be trained and certified according to legal standards. (For saftey, drag racing regulations require professional riggers be used.) Paratroops and sport skydivers are always trained to pack their own primary "main" parachutes. Parachutes can malfunction in several ways. Malfunctions can range from minor problems that can be corrected in-flight and still be landed to catastrophic malfunctions that require the main parachute to be cut away using a modern 3-ring release system and the reserve be deployed. Most skydivers are also equipped with small barometric computers (known as an AAD or Automatic Activation Device like Cypres, FXC or Vigil) that will automatically deploy the reserve parachute if the skydiver himself has not done so at a preset altitude and descent rate. Exact numbers are difficult to estimate but approximately one in a thousand sports main parachute openings malfunction and must be cut away, although some skydivers have many thousands of jumps and never cut away, (either they pack their mains more carefully than average or they are just lucky). Reserve parachutes are packed and deployed differently, they are also designed more conservatively and built & tested to more exacting standards so they are more reliable than main parachutes, but the real safety advantage comes from the probability of an unlikely main malfunction multiplied by the even less likely probability of a reserve malfunction. This yields an even smaller probability of a double malfunction although the possibility of a main malfunction that cannot be cutaway causing a reserve malfunction is a very real risk. In the U.S., the average fatality rate is considered to be about 1 in 80,000 jumps. Most injuries and fatalities in sport skydiving occur under a fully functional main parachute because the skydiver performed unsafe maneuvers or made an error in judgement while flying their canopy typically resulting in a high speed impact with the ground or other hazards on the ground. The average skydiver in the U.S. makes about 150 jumps per year and will leave the sport before the 5th year.

External links

- [http://www.fai.org FAI] The Federation Aeronautique Internationale -- The international governing body for all airborne sports.
- [http://www.uspa.org USPA] The United States Parachute Association -- The governing body for sport skydiving in the U.S.
- [http://www.cspa.ca CSPA] The Canadian Sport Parachuting Association -- The governing body for sport skydiving in Canada.
- [http://www.dropzone.com Dropzone.com] the Premier web resource for information on Skydiving, Dropzones and modern parachuting
- [http://www.aero.com/publications/parachutes/9511/pc1195.htm Parachute]
- [http://www.getkidsgoing.com/parachute_skydiving_skydive.htm Charity Parachute Jumps] Experience skydiving, parachuting and tandem jumps across the UK by raising money for disabled children. Category:Parachuting ja:パラシュート

Airport

An airport is a facility where aircraft can take off and land. At the very minimum, an airport consists of one runway (or helipad), but other common components are hangars and terminal buildings. Apart from these, an airport may have a variety of facilities and infrastructure, including fixed base operator services, air traffic control, passenger facilities such as restaurants and lounges, and emergency services. A military airport is known as an airbase in North American terminology (other countries may use the term airfield or air station in current parlance). The terms airfield and airstrip may also be used to refer to a facility that has nothing more than a runway. The term aerodrome refers to any surface used for take off or landing. The term airport refers to an aerodrome that is licensed by the responsible government organization (ie FAA, Transport Canada). Airports have to be maintained to higher safety standards. There is usually no minimum standards for a basic aerodrome.

Attributes

Airports vary in size, with smaller or less-developed airports often having only a single runway shorter than 1,000 m (3,300 ft). Larger airports for international flights generally have paved runways 2,000 m (6,600 ft) or longer. Many small airports have dirt, grass, or gravel runways, rather than asphalt or concrete. In the United States, the minimum dimensions for dry, hard landing fields are defined by the FAR Landing And Takeoff Field Lengths. These include considerations for safety margins during landing and takeoff. Typically heavier aircraft require longer runways. The longest public-use runway in the world is at Ulyanovsk-Vostochny International Airport, in Ulyanovsk, Russia. It has a length of 16,404ft. As of 2005, there were approximately 50,000 airports around the world, including 19,815 in the United States alone.

Airport structures

Russia Airports are divided into landside and airside areas. Landside areas include parking lots, tank farms and access roads. Airside areas include all areas accessible to aircraft, including runways, taxiways and ramps. Access from landside areas to airside areas is tightly controlled at most airports. Passengers on commercial flights access airside areas through terminals, where they can purchase tickets, clear security, check or claim luggage and board aircraft. The waiting areas which provide passenger access to aircraft are typically called concourses, although this term is often used interchangeably with terminal. The area where aircraft park next to a terminal to load passengers and baggage is known as a ramp. Parking areas for aircraft away from terminals are generally called aprons. Both large and small airports can be towered or uncontrolled, depending on air traffic density and available funds. Due to their high capacity and busy airspace, most international airports have air traffic control located on site.

International airports

Customs facilities for international flights define an international airport, and often require a more conspicuous level of physical security. International airports generally have a complex of buildings where passengers can embark on airliners, and where cargo can be stored and loaded. The largest international airports are often located next to freeways or are served by their own freeways. Often, traffic is fed into two access roads, designed as loops, one sitting on top of the other. One level is for departing passengers and the other is for arrivals. Many airports also have light rail lines or other mass transit systems directly connected to the main terminals.

Shops and food services

mass transits.]] Most international airports have shops and food courts. These services usually provide the passengers food and drinks before they board their flight. Many recognizable chain food restaurants have opened branches in large airports to serve often hungry passengers. London's Heathrow Airport, for example, is home to both a Harrods and a Hamleys Toy Shop, providing Duty Free for international passangers. International areas usually have a duty-free shop where travellers are not required to pay the usual duty fees on items. Larger airlines often operate member-only lounges for premium passengers. Airports have a captive audience, and consequently the prices charged for food is generally higher than are available elsewhere in the region. However, some airports now regulate food costs to keep them comparable to so-called "street prices". captive audience

Cargo and freight services

In addition to people, airports are responsible for moving large volumes of cargo around the clock. Cargo airlines often have their own on-site and adjecent infrastructure to rapidly transfer parcels between ground and air modes of transportation.

Support services

Aircraft maintenance, pilot services, aircraft rental, and hangar rental are most often performed by a fixed base operator (FBO). At major airports, particularly those used as hubs, airlines may operate their own support facilities.

History and development

The earliest airplane landing sites were simply open, grassy fields. The plane could approach at any angle that provided a favorable wind direction. Early airfields were often built for the purpose of entertainment. These aerodromes consisted of a grassy field, with hangar for storage and servicing of airplanes, and observation stands for the visitors. Increased aircraft traffic during World War I led to the construction of regular landing fields. Airplanes had to approach these from certain directions. This led to the development of aids for directing the approach and landing slope. Following the war, some of these military airfields added commercial facilities for handling passenger traffic. One of the earliest such fields was Le Bourget, near Paris. The first international airport to open was the Croydon Airport, in South London [http://www.sutton.gov.uk/leisure/heritage/croydon+airport.htm]. In 1922, the first permanent airport and commercial terminal solely for commercial aviation was built at Königsberg, Germany. The airports of this era used a paved "apron", which permitted night flying as well as landing heavier airplanes. The first lighting used on an airport was during the later part of the 1920s; in the 1930s approach lighting came into use. These indicated the proper direction and angle of descent. The colors and flash intervals of these lights became standardized under the ICAO. In the 1940s, the slope-line approach system was introduced. This consisted of two rows of lights that formed a funnel indicating an aircraft's position on the glideslope. Additional lights indicated incorrect altitude and direction. Following World War II, airport design began to become more sophisticated. Passenger buildings were being grouped together in an island, with runways arranged in groups about the terminal. This arrangement permitted expansion of the facilities. But it also meant that passengers had to travel further to reach their plane.

Airport designation and naming

Airports are uniquely represented by their IATA airport code and ICAO airport code. IATA airport codes are often, but not always, abbreviated forms of the common name of the airport, such as PHL for Philadelphia International Airport. Exceptions to this rule often occur when an airport's name is changed. O'Hare International Airport in Chicago, Illinois retains the IATA code ORD, from its former name of Orchard Field. In many countries airports are often named after a prominent national celebrity, commonly a politician, e.g. John F. Kennedy International Airport, Indira Gandhi International Airport or Charles de Gaulle International Airport.

Airport security

Airports are required to have safety precautions in most countries. Rules vary in different countries, but there are common elements worldwide. Airport security normally requires baggage checks, metal screenings of individual persons, and rules against any object that could be used as a weapon. Since the September 11, 2001 attacks, airport security has been dramatically increased worldwide.

Airport operations

Outside the terminal, there is a large team of people who work in concert to ensure aircraft can land, take off, and move around quickly and safely. These processes are largely invisible to passengers, but they can be extraordinarily complex at large airports.

Air traffic control

Air traffic control (or ATC) is system whereby ground-based controllers direct aircraft movements, usually via radio. This coordinated oversight facilitates safety and speed in complex operations where traffic moves in all three dimensions. Air traffic control responsibilities at airports are usually divided into two main areas: ground and tower. radio.]] Ground Control is responsible for directing all ground traffic in designated "movement areas," except the traffic on runways. This includes planes, baggage trains, snowplows, grass cutters, fuel trucks, and a wide array of other vehicles. Ground Control will instruct these vehicles on which taxiways to use, which runway they will use (in the case of planes), where they will park, and when it is safe to cross runways. When a plane is ready to take off it will stop short of the runway, at which point it will be turned over to Tower Control. After a plane has landed, it will depart the runway and be returned to Ground Control. Tower Control controls aircraft on the runway and in the controlled airspace immediately surrounding the airport. Tower controllers use radar to identify and accurately locate an aircraft's position in three-dimensional space. They coordinate the sequencing of aircraft in the traffic pattern and direct aircraft on how to safely join and leave the circuit. Aircraft which are only passing through the airspace must also contact Tower Control in order to be sure that they remain clear of other traffic and do not disrupt operations.

Traffic pattern

radar Smaller airports and military airfields use a traffic pattern to assure smooth traffic flow between departing and arriving aircraft. Generally, this pattern is a circuit consisting of five "legs" that form a rectangle (two legs and the runway form one side, with the remaining legs each form another side). Each leg is named (see diagram), and ATC directs pilots on how to join and leave the circuit. Traffic patterns are flown at one specific altitude, usually 1000 ft AGL. Most traffic patterns are left-handed, meaning all turns are made to the left. Right-handed patterns do exist, usually because of obstacles such as a mountain or to reduce noise for local residents. The predetermined circuit helps pilots look for other aircraft, and helps reduce the chance of a mid-air collision. At extremely large airports, a circuit is not usually used. Rather, ATC schedules aircraft for landing while they are still hours away from the airport. Airplanes can then take the most direct approach to the runway and land without worrying about interference from other aircraft. While this system keeps the airspace free and is simpler for pilots, it requires detailed knowledge of how aircraft are planning to use the airport ahead of time and is therefore only possible with large commercial airliners on pre-scheduled flights. The system has recently become so advanced that controllers can predict whether an aircraft will be delayed on landing before it even takes off; that aircraft can then be delayed on the ground, rather than wasting expensive fuel waiting in the air.

Navigational aids

Before takeoff, pilots usually check an Automatic Terminal Information Service (ATIS) for information about airport conditions where they exist. The ATIS contains information about weather, which runway and traffic patterns are in use, and other information that pilots should be aware of. When flying, there are a number of aids available to pilots, though not all airports are equipped with them. A VASI helps pilots fly a perfect approach for landing once they have found the airport. Some airports are equipped with a VOR to help pilots find the direction to the airport, VORs are often accompanied by a DME to determine the distance to the airport. In poor weather, pilots will use an Instrument Landing System to find the runway and fly the correct approach, even if they cannot see the ground. Larger airports sometimes offer Precision Approach Radar (PAR). The aircraft's horizontal and vertical movement is tracked via radar, and the controller tells the pilot his position relative to the approach slope. Once the pilots can see the runway lights, they may continue with a visual landing.

Guidance signs

approach slope Airport guidance signs provide direction and information to taxiing aircraft and airport vehicles and assist in safe and expedient movement of aircraft. Smaller airports may have few or no signs, relying instead on airport diagrams and charts. There are two classes of signage at airports, with several types of each:

Operational guidance signs

- Location signs - yellow on black background. Identifies the runway or taxiway currently on or entering.
- Direction/Runway Exit signs - black on yellow. Identifies the intersecting taxiways the aircraft is approaching, with an arrow indicating the direction to turn.
- Other - Many airports use conventional traffic signs such as stop and yield signs throughout the airport.

Mandatory instruction signs

Madatory instruction signs are white on red. They show entrances to runways or critical areas. Vehicles and aircraft are required to stop at these signs until the control tower gives clearance to proceed.
- Runway signs - White on a red. These signs simply identify a runway intersection ahead.
- Frequency Change signs - Usually a stop sign and an instruction to change to another frequency. These signs are used at airports with different areas of ground control.
- Holding Position signs - A single solid yellow bar across a taxiway indicates a position where ground control may require a stop. If a two solid yellow bars and two dashed yellow bars are encountered, this indicates a holding position for a runway intersection ahead; runway holding lines must never be crossed without permission. At some airports, a line of red lights across a taxiway is used during low visibility operations to indicate holding positions.

Lighting

Many airports have lighting that help guide planes using the runways and taxiways at night or in rain or fog. On runways, green lights indicate the beginning of the runway for landing, while red lights indicate the end of the runway. Runway edge lighting is white lights spaced out on both sides of the runway, indicating the edge. Some airports have more complicated lighting on the runways including lights that run down the centerline of the runway and lights that help indicate the approach. Low-traffic airports may use Pilot Controlled Lighting to save electricity and staffing costs. Along taxiways, blue lights indicate the taxiway's edge, and some airports have embedded green lights that indicate the centerline.

Wind indicators

Planes take-off and land into the wind in order to achieve maximum performance. Wind speed and direction information is available through the ATIS or ATC, but pilots need instantaneous information during landing. For this purpose, a windsock is kept in view of the runway.

Safety management

Air safety is an important concern in the operation of an airport, and almost every airfield includes equipment and procedures for handling emergency situations. Commercial airfields include one or more emergency vehicles and their crew that are specially equipped for dealing with airfield accidents, crew and passenger extractions, and the hazards of highly flammable airplane fuel. The crews are also trained to deal with situations such as bomb threats, hijacking, and terrorist activities. Potential airfield hazards to aircraft include debris, nesting birds, and environmental conditions such as ice or snow. The fields must be kept clear of debris using cleaning equipment so that loose material doesn't become a projectile and enter an engine duct. Similar concerns apply to birds nesting near an airfield, and crews often need to discourage birds from taking up residence. In adverse weather conditions, ice and snow clearing equipment can be used to improve traction on the landing strip. For waiting aircraft, equipment is used to spray special deicing fluids on the wings. During the 1980s, a phenomenon known as microburst became a growing concern due to accidents caused by microburst wind shear. (For example, see Delta Air Lines Flight 191.) Microburst radar was developed as an aid to safety during landing, giving two to five minutes warning to aircraft in the vicinity of the field of an microburst event.

Environmental concerns

The traffic generated by airports both in the air and on the surface can be a major source of aviation noise and air pollution which may interrupt nearby residents' sleep or, in extreme cases, be harmful to their health . The construction of new airports, or addition of runways to existing airports, is often resisted by local residents because of the effect on the countryside, historical sites, local flora and fauna. As well, due to the risk of collision between birds and airplanes, large airports undertake population control programs where they frighten or shoot birds to ensure the safety of air travellers. The construction of airports has been known to change local weather patterns. For example, because they often flatten out large areas, they can be succeptible to fog in areas where fog rarely forms. In addition, because they generally replace trees and grass with pavement, they often change drainage patterns in agricultural areas, leading to more flooding, run-off and erosion in the surrounding land.

Military Airbase

An Airbase, sometimes referred to as a military airport or airfield, provides basing and support of military aircraft. Some airbases provide facilites similar to their civilian counterparts. For example, RAF Brize Norton in Oxfordshire, England has a terminal which caters to passengers for the Royal Air Force's scheduled Tristar flights to the Falkland Islands. A special military airfield is an Aircraft Carrier.

Aircraft Carriers

An aircraft carrier is a warship that functions as a floating airport for military aircraft. Aircraft carriers allow a naval force to project air power great distances without having to depend on local bases for land-based aircraft. After their development in World War II, aircraft carriers rapidly replaced the battleship as the centrepiece of a modern fleet. Unescorted carriers are considered vulnerable to missile or submarine attacks and therefore travel as part of a carrier battle group that includes a wide array of other ships with specific functions.

Airports in Entertainment

Airports have occasionally played major roles in motion pictures and television shows due to being transportation hubs, but also because of their unique characteristics. One such example of this is the movie The Terminal, a film about a man who becomes permanently grounded in an airport terminal and must survive only on the food and shelter provided by the airport. If nothing else, this movie demonstrates the sustaining properties of airport terminals. Movies such as Airplane!, Airport, Die Hard II, Jackie Brown, and Get Shorty also revolve around the unique culture of the major city airports.

Airport Directories

Each national aviation authority has its own system for pilots to be able to keep track of information about airports in their country.
- The United States uses the Airport/Facility Directory (A/FD), seven volumes that contain information such as elevation, airport lighting, runway information, communications, hours of operation, nearby NAVAIDs and much more.
- In Canada, a single publication, the Canada Flight Supplement (CFS) provides equivalent information.

External links

- [http://www.airnav.com/airports/ AirNav.com] - complete list of U.S. airports, with detailed airport information
- [http://www.pspda.com/efad.html eFAD] - the most powerful electronic airport directory (A/FD) on earth!
- [http://www.fly.faa.gov/flyfaa/usmap.jsp ATCSCC Real-time Airport Status page] - shows airport delay times for major U.S. airports
- [http://www.africaspotter.at.tt AFRICASPOTTER.at.tt] - Airports in Southern Africa
- [http://www.fortliberty.org/american-politics/airport-security.shtml U.S. airport security]
- [http://www.dft.gov.uk Department for Transport] (United Kingdom)
- [http://www.centennialofflight.gov/essay/Government_Role/landing_nav/POL14.htm History of Aircraft Landing Aids]
- [http://www.numlink.com Airport satellite images] Category:Aviation Category:Transport infrastructure Category:Buildings and structures ko:공항 ms:Lapangan terbang ja:空港 simple:Airport th:สนามบิน

Aircraft

An aircraft is any machine capable of atmospheric flight. flight. This is a wide-bodied long-haul aircraft]]

Categories and classification

Aircraft fall into two broad categories:

Heavier than air

- Heavier than air aerodynes, including autogyros, helicopters and variants, and conventional fixed-wing aircraft: aeroplanes in Commonwealth English (excluding Canada), airplanes in North American English. Fixed-wing aircraft generally use an internal-combustion engine in the form of a piston engine (with a propeller) or a turbine engine (jet or turboprop), to provide thrust that moves the craft forward through the air. The movement of air over the airfoil produces lift that causes the aircraft to fly. Exceptions are gliders which have no engines and gain their thrust, initially, from winches or tugs and then from gravity and thermal currents. For a glider to maintain its forward speed it must descend in relation to the air (but not necessarily in relation to the ground). Helicopters and autogyros use a spinning rotor (a rotary wing) to provide lift; helicopters also use the rotor to provide thrust. The abbreviation VTOL is applied to aircraft other than helicopters that can take off or land vertically. STOL stands for Short Take Off and Landing. Mainly used internationally.

Lighter than air

STOL
- Lighter than air aerostats: hot air balloons and airships. Aerostats use buoyancy to float in the air in much the same manner as ships float on the water. In particular, these aircraft use a relatively low density gas such as helium, hydrogen or heated air, to displace the air around the craft. The distinction between a balloon and an airship is that an airship has some means of controlling both its forward motion and steering itself, while balloons are carried along with the wind.

Types of aircraft

:See also: List of aircraft There are several ways to classify aircraft. Below, we describe classifications by design, propulsion and usage.

By design

A first division by design among aircraft is between lighter-than-air, aerostat, and heavier-than-air aircraft, aerodyne. Examples of lighter-than-air aircraft include non-steerable balloons, such as hot air balloons and gas balloons, and airships (sometimes called dirigible balloons) such as blimps (that have non-rigid construction) and rigid airships that have a rigid frame. The most successful type of rigid airship was the Zeppelin, although there were some accidents such as the Hindenburg Zeppelin which was destroyed in a fire at Lakehurst, NJ, in 1937. In heavier-than-air aircraft, there are two ways to produce lift: aerodynamic lift and engine lift. In the case of aerodynamic lift, the aircraft is kept in the air by wings or rotors (see aerodynamics). With engine lift, the aircraft defeats gravity by use of vertical thrust greater than its weight. Examples of engine lift aircraft are rockets, and

Skydiving

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Parachute

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Lighting