In kiting, a line is the string or thin cord made of cotton, nylon, silk, or wire, which connects the kite to the person operating it or an anchor. Kites have a set of wings, a set of anchors, and a set of lines coupling the wings with the anchors. Kite lines perform various roles: bridle, control, tug, or special duty.
Successful kiting in particular kite applications depends in large part on the kite line's specifications and handling. The integrity of kite lines is affected by wear, reeling, contact with chemicals, loss of strength from knottings, ultraviolet rays of the sun, repeated cycles of use, and damaging actions during use.
There are historically classic specifications of kite lines. Kite lines for small toy kites differ greatly from kite lines used for kite tugs that pull commercial cargo ships across the ocean. Sport kites using kite line sets of two or three or four lines at a time have a need for very low stretch in the lines. Single-line recreation kite lines may do well with stretchy kite lines. Kite-fighting kites' main tether lines have sharp glass particles bonded to the line. Kite lines misused or abused can cause injury to persons and property. Kite lines vary in pricing and availability. Repair of a particular line has its own arts.
Reeling, handling, and storage methods differ for lines depending on the kite applications. Kite lines terminate at the kite's wing/bridle at one end and at some kite mooring at the other end; the mooring is to some object anchor that provides the tug or tension against the resultant of the lift and drag forces of the kite; the anchor is always powered by something even if that something is the Earth's moving surface relative to the air for air kites; a running human kite operator is the source of human powering.
Depending on the kite application and kite system needs, selecting a kite line will consider one or more of the following parameters: availability, base material, color, density, mass per length, size, manufacturer's reports, serial number or product number, diameter, cross-section shape, tensile strength new, aged tensile strength, resistance damage from chemicals, defects, safety factor, resistance to damage from solar radiation (UV stabilization), electrical conductivity, optical conductivity, heat conductivity, moisture intake from water (via humidity, rain, contact with liquid water), buoyancy in water, abrasion resistance, nature of manufacturer's line joins, feel, degradation from knotting, terminal methods, elasticity, structure, signal transmission capacity, visibility to radar, performance over time, maintenance actions, effect on performance from hours of use, drag, negative lift, auxiliary line uses, performance when being reeled under tension, performance when tensed line touches itself, action upon breaking, memory, veil, sleeving, inspectability, surface finish, reaction to heat and cold, taper (as wanted), flexibility, reeling behavior, breaking strength, critical diameter, reliability, test-results portfolio, visibility, twist, plasticity, safety, price.
Toy kites sold with a manufacturer's selected line makes the decision easy; the decision is more challenging for custom kite applications. For example, the design and handling of the piano-wire kite line for the high-altitude meteorological observations (1749–1933) was a keen engineering process. [1] [2] [3] [4] [5] [6] [7] [8]
To avoid burns and cuts, kite lines for children toy kites are frequently soft, fuzzy, cotton twine.
Some kites are controlled by multiple lines. Low-stretch lines have a stable length and give more responsive control. Kite lines can be dyed, for show and to simplify control line management, either by the manufacturer or the enduser. [9] Melting point is considered when controlling a kite for kite fighting; lower cost cotton line can melt a crossed expensive synthetic line. [10]
Historically, high altitude kite flights were made by atmospheric scientists and meteorologists in the late 19th to early 20th centuries. Routine flights around the world were made using steel wire with single kites and kite trains. The highest recorded flight was made by a German meteorological station at Lindenberg in 1919. It is reported that the top kite reached 31,955 ft above the launch point. The line was over 20 km of high tensile steel piano wire with a breaking strength varying between 134 and 225 kg. [11]
In 2014 the single-line single-kite altitude world record was made using a kite line of Ultra High Molecular Weight Polyethylene (UHMWPE, Dyneema) with 300 pound breaking-strength. Robert Moore and his team used 12,400 metres of line to fly a 12 square metre kite to 16,009 feet above the launch point. [12] Dyneema, a braided Ultra High Molecular Weight Polyethylene (UHMWPE) line, and the identically structured line, Spectra, are stronger and lighter than Kevlar for a given diameter. One of the most important characteristics of line for high altitude kite flying is small diameter and high strength to weight ratio. The greatest barrier to high altitude kite flights is aerodynamic line drag. [13] The use of Dyneema over an extended period has shown that it is highly resistant to ultra violet degradation in comparison to Kevlar. [14] Richard Crawford, a high altitude flyer from the US, made an attempt on the world single kite altitude record using a 220 lb test, Technora line manufactured by Twinline. He reported that he flew a delta kite to approximately 6,500 ft in September 2008. [15] [16]
When a kite application does not fit a common purpose, then specialized kite lines are used. Setting specific records under controlled conditions allows kite operators or competitors to choose kite lines with high specificity and without excessive safety factors.
The short kite line called the hang loop for the free-flying kite hang gliders has received special engineering attention; the further main kite-lines from the hang loop to the pilot's harness are also highly specialized in design. [17]
When maximizing performance for large kites; E. D. Archibald was the first to use piano wire for kiting. [18]
Flatland kiting hang gliders with 3000' of tow line holding the manned hang glider kite takes special care to specify. Protecting the kite line from ground abrasion is considered. [19]
Want to fly an indoor kite without wind? The indoor no-wind kite operator need not worry about line breaks causing damages to downwind property. The choice of line can be very specialized here.
When the kite line is to be invisible, a clear translucent fine thread is chosen.
Making kite lines visible for night flying occurs in short-line and long line applications. Line lights is one solution sometimes used. Lines that carry light is another. Lights on the ground shining on stunt kites and their lines occurs. Flying Kites at Night
Biologists began using the term "ballooning" for mechanical kiting used by spiderlings to disperse to new locations. [20] [21] Another spider silk for the bridge thread is frequently kited. And another thread of the spider is used as a drag line from which spiders frequently swing in the breeze, getting deflected before landing. Humans have used spider silk for making kites. [22]
Fit the kite line to the kite application; handle the line as needed to avoid hazards, accidents, and injury to persons and property. The operator of a kite system is fully responsible for damages done by the operation of his or her kite system; this includes the kite line. Pre-flight plan and pre-flight the kite line; avoid surprises. Piano wire is appropriate for certain applications, but totally inappropriate for recreational or sport kite flying. Fishing monofilament line is not used for most hobby, recreational, or sport power kiting because of its stretch, breaking behavior, and thinness; avoid it unless there is a very special application involved. Metal wire can conduct static and current electricity; avoid metal wires unless a professional scientific or industrial engineer approves the line for a specific purpose.
Gloves, proper reel choices, goggles, guards, tension limiters, and other safety devices help to reduce accidents. Ability to de-power a kite's lift and drag is a part of sound kite systems. Tensed line can act as razors. Moving lines can cut through flesh too easily. Fatalities too often occur from kite line abuse. Keep kite lines in good condition. Realize that knots weaken kite line. Keep kite lines dry and clean. Log any wear and use of the line; replace lines as needed. Choose a safety factor when designing a line for an application. Avoid flying in the rain or stormy weather changes. [23] [24] [25] [26] [27]
A kite is a tethered heavier-than-air or lighter-than-air craft with wing surfaces that react against the air to create lift and drag forces. A kite consists of wings, tethers and anchors. Kites often have a bridle and tail to guide the face of the kite so the wind can lift it. Some kite designs do not need a bridle; box kites can have a single attachment point. A kite may have fixed or moving anchors that can balance the kite. The name is derived from the kite, the hovering bird of prey.
A hot air balloon is a lighter-than-air aircraft consisting of a bag, called an envelope, which contains heated air. Suspended beneath is a gondola or wicker basket, which carries passengers and a source of heat, in most cases an open flame caused by burning liquid propane. The heated air inside the envelope makes it buoyant, since it has a lower density than the colder air outside the envelope. As with all aircraft, hot air balloons cannot fly beyond the atmosphere. The envelope does not have to be sealed at the bottom, since the air inside the envelope is at about the same pressure as the surrounding air. In modern sport balloons the envelope is generally made from nylon fabric, and the inlet of the balloon is made from a fire-resistant material such as Nomex. Modern balloons have been made in many shapes, such as rocket ships and the shapes of various commercial products, though the traditional shape is used for most non-commercial and many commercial applications.
Unpowered aircraft can remain airborne for a significant period of time without onboard propulsion. They can be classified as gliders, lighter-than-air balloons and tethered kites. In the case of kites, lift is obtained by tethering to a fixed or moving object, perhaps another kite, to obtain a flow of wind over the lifting surfaces. In the case of balloons, lift is obtained through inherent buoyancy and the balloon may or may not be tethered. Free balloon flight has little directional control. Gliding aircraft include sailplanes, hang gliders, and paragliders that have full directional control in free flight.
A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct from rotary-wing aircraft, and ornithopters. The wings of a fixed-wing aircraft are not necessarily rigid; kites, hang gliders, variable-sweep wing aircraft and airplanes that use wing morphing are all examples of fixed-wing aircraft.
A fishing line is a flexible, high-tensile cord used in angling to tether and pull in fish, in conjunction with at least one hook. Fishing lines are usually pulled by and stored in a reel, but can also be retrieved by hand, with a fixed attachment to the end of a rod, or via a motor.
Paragliding is the recreational and competitive adventure sport of flying paragliders: lightweight, free-flying, foot-launched glider aircraft with no rigid primary structure. The pilot sits in a harness or in a cocoon-like 'pod' suspended below a fabric wing. Wing shape is maintained by the suspension lines, the pressure of air entering vents in the front of the wing, and the aerodynamic forces of the air flowing over the outside.
Spider silk is a protein fibre spun by spiders. Spiders use their silk to make webs or other structures, which function as sticky nets to catch other animals, or as nests or cocoons to protect their offspring, or to wrap up prey. They can also use their silk to suspend themselves, to float through the air, or to glide away from predators. Most spiders vary the thickness and stickiness of their silk for different uses.
A sport kite, also commonly known as a stunt kite, is a type of kite that can be maneuvered in the air. A related kite, also controllable and used for recreation, but capable of generating a significant amount of pull and used for providing movement, is the power kite.
A box kite is a high performance kite, noted for developing relatively high lift; it is a type within the family of cellular kites. The typical design has four parallel struts. The box is made rigid with diagonal crossed struts. There are two sails, or ribbons, whose width is about a quarter of the length of the box. The ribbons wrap around the ends of the box, leaving the ends and middle of the kite open. In flight, one strut is the bottom, and the bridle is tied between the top and bottom of this strut. The dihedrals of the sails help stability.
A power kite or traction kite is a large kite designed to provide significant pull to the user.
A shackle, also known as a gyve, is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism. The term also applies to handcuffs and other similarly conceived restraint devices that function in a similar manner. Shackles are the primary connecting link in all manner of rigging systems, from boats and ships to industrial crane rigging, as they allow different rigging subsets to be connected or disconnected quickly. A shackle is also the similarly shaped piece of metal used with a locking mechanism in padlocks. A carabiner is a type of shackle used in mountaineering.
Kite types, kite mooring, and kite applications result in a wide variety of kite control systems. Contemporary manufacturers, kite athletes, kite pilots, scientists, and engineers are expanding the possibilities.
Ultra-high-molecular-weight polyethylene is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made.
Ballooning, sometimes called kiting, is a process by which spiders, and some other small invertebrates, move through the air by releasing one or more gossamer threads to catch the wind, causing them to become airborne at the mercy of air currents and electric fields. A 2018 study concluded that electric fields provide enough force to lift spiders in the air, and possibly elicit ballooning behavior. This is primarily used by spiderlings to disperse; however, larger individuals have been observed doing so as well. The spider climbs to a high point and takes a stance with its abdomen to the sky, releasing fine silk threads from its spinneret until it becomes aloft. Journeys achieved vary from a few metres to hundreds of kilometres. Even atmospheric samples collected from balloons at five kilometres altitude and ships mid-ocean have reported spider landings. Ballooning can be dangerous.
Dyneema Composite Fabric (DCF), also known as Cuben Fiber (CTF3), is a high-performance non-woven composite material used in high-strength, low-weight applications. It is constructed from a thin sheet of ultra-high-molecular-weight polyethylene laminated between two sheets of polyester.
Different types of flying kites have niche applications. In nature, some animals, such as spiders, also make use of kiting.
Kites are tethered flying objects which fly by using aerodynamic lift, requiring wind for generation of airflow over the lifting surfaces.
Kite mooring refers to a specific method used to secure a kite in flight. The two fundamental parts of a kite are the wing and the kite line. The kite needs mooring to either a mobile or fixed object to develop the tension in the kite line. This converts to lift and drag enabling the kite to fly in its media.
M5 fiber is a high-strength synthetic fiber first developed by the Dutch chemical firm AkzoNobel. It is produced in the United States by the Magellan Systems International, which became a division of DuPont.
Crosswind kite power is power derived from airborne wind-energy conversion systems or crosswind kite power systems (CWKPS). The kite system is characterized by energy-harvesting parts flying transverse to the direction of the ambient wind, i.e., to crosswind mode; sometimes the entire wing set and tether set is flown in crosswind mode. From toy to power-grid-feeding sizes, these systems may be used as high-altitude wind power (HAWP) devices or low-altitude wind power (LAWP) devices without having to use towers. Flexible wings or rigid wings may be used in the kite system. A tethered wing, flying in crosswind at many times wind speed, harvests wind power from an area that exceeds the wing's total area by many times.
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