text:
Hair

Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types, and hair care, but hair is also an important biomaterial primarily composed of protein, notably alpha-keratin.

Attitudes towards different forms of hair, such as hairstyles and hair removal, vary widely across different cultures and historical periods, but it is often used to indicate a person's personal beliefs or social position, such as their age, gender, or religion.

Meaning
The word "hair" usually refers to two distinct structures:
 * 1) the part beneath the skin, called the hair follicle, or, when pulled from the skin, the bulb or root. This organ is located in the dermis and maintains stem cells, which not only re-grow the hair after it falls out, but also are recruited to regrow skin after a wound.
 * 2) the hair shaft, which is the hard filamentous part that extends above the skin surface. A cross section of the hair shaft may be divided roughly into three zones.

Hair fibers have a structure consisting of several layers, starting from the outside:
 * 1) the cuticle, which consists of several layers of flat, thin cells laid out overlapping one another as roof shingles
 * 2) the cortex, which contains the keratin bundles in cell structures that remain roughly rod-like
 * 3) the medulla, a disorganized and open area at the fiber's center

Etymology
The word "hair" is derived from heer and hêr, in turn derived from hǽr and hér, with influence from hár. Both the Old English and Old Norse words derive from hēran and are related to terms for hair in other Germanic languages such as här, Dutch and haar, and her. The now broadly obsolete word "fax" refers specifically to head hair and is found in compounds such as Fairfax and Halifax. It is derived from feax and is cognate with terms such as Old Norse and fax.

Description
Each strand of hair is made up of the medulla, cortex, and cuticle. The innermost region, the medulla, is an open and unstructured region that is not always present. The highly structural and organized cortex, or second of three layers of the hair, is the primary source of mechanical strength and water uptake. The cortex contains melanin, which colors the fiber based on the number, distribution and types of melanin granules. The melanin may be evenly spaced or cluster around the edges of the hair. The shape of the follicle determines the shape of the cortex, and the shape of the fiber is related to how straight or curly the hair is. People with straight hair have round hair fibers. Oval and other shaped fibers are generally more wavy or curly. The cuticle is the outer covering. Its complex structure slides as the hair swells and is covered with a single molecular layer of lipid that makes the hair repel water. The diameter of human hair varies from 0.017 to 0.18 mm. Some of these characteristics in humans' head hair vary by race: people of mostly African ancestry tend to have hair with a diameter of 60-90 μm and a flat cross-section, while people of mostly European or Middle Eastern ancestry tend to have hair with a diameter of 70-100 μm and an oval cross-section, and people of mostly Asian or Native American ancestry tend to have hair with a diameter of 90-120 μm and a round cross-section. There are roughly two million small, tubular glands and sweat glands that produce watery fluids that cool the body by evaporation. The glands at the opening of the hair produce a fatty secretion that lubricates the hair.

Hair growth begins inside the hair follicle. The only "living" portion of the hair is found in the follicle. The hair that is visible is the hair shaft, which exhibits no biochemical activity and is considered "dead". The base of a hair's root (the "bulb") contains the cells that produce the hair shaft. Other structures of the hair follicle include the oil producing sebaceous gland which lubricates the hair and the arrector pili muscles, which are responsible for causing hairs to stand up. In humans with little body hair, the effect results in goose bumps.

Root of the hair
The root of the hair ends in an enlargement, the hair bulb, which is whiter in color and softer in texture than the shaft and is lodged in a follicular involution of the epidermis called the hair follicle. The bulb of hair consists of fibrous connective tissue, glassy membrane, external root sheath, internal root sheath composed of epithelium stratum (Henle's layer) and granular stratum (Huxley's layer), cuticle, cortex and medulla.

Natural color
All natural hair colors are the result of two types of hair pigments. Both of these pigments are melanin types, produced inside the hair follicle and packed into granules found in the fibers. Eumelanin is the dominant pigment in brown hair and black hair, while pheomelanin is dominant in red hair. Blond hair is the result of having little pigmentation in the hair strand. Gray hair occurs when melanin production decreases or stops, while poliosis is white hair (and often the skin to which the hair is attached), typically in spots that never possessed melanin at all, or ceased for natural reasons, generally genetic, in the first years of life.

Human hair growth
Hair grows everywhere on the external body except for mucus membranes and glabrous skin, such as that found on the palms of the hands, soles of the feet, and lips.

The body has different types of hair, including vellus hair and androgenic hair, each with its own type of cellular construction. The different construction gives the hair unique characteristics, serving specific purposes, mainly, warmth and protection.

The three stages of hair growth are the anagen, catagen, and telogen phases. Each strand of hair on the human body is at its own stage of development. Once the cycle is complete, it restarts and a new strand of hair begins to form. The growth rate of hair varies from individual to individual depending on their age, genetic predisposition and a number of environmental factors. It is commonly stated that hair grows about 1 cm per month on average; however reality is more complex, since not all hair grows at once. Scalp hair was reported to grow between 0.6 cm and 3.36 cm per month. The growth rate of scalp hair somewhat depends on age (hair tends to grow more slowly with age), sex, and ethnicity. Thicker hair (>60 μm) grows generally faster (11.4 mm per month) than thinner (20-30 μm) hair (7.6 mm per month).

It was previously thought that Caucasian hair grew more quickly than Asian hair and that the growth rate of women's hair was faster than that of men. However, more recent research has shown that the growth rate of hair in men and women does not significantly differ and that the hair of Chinese people grew more quickly than the hair of French Caucasians and West and Central Africans. The quantity of hair hovers in a certain range depending on hair colour. An average blonde person has 150,000 hairs, a brown-haired person has 110,000, a black-haired person has 100,000, and a redhead has 90,000. Hair growth stops after a human's death. Visible growth of hair on the dead body happens only because of skin drying out due to water loss.

The world record for longest hair on a living person stands with Smita Srivastava of Uttar Pradesh, India. At 7 feet and 9 inches long, she broke a Guinness World Record in November 2023, having grown her hair for 32 years.

Texture
Hair exists in a variety of textures. Three main aspects of hair texture are the curl pattern, volume, and consistency. All mammalian hair is composed of keratin, so the make-up of hair follicles is not the source of varying hair patterns. There are a range of theories pertaining to the curl patterns of hair. Scientists have come to believe that the shape of the hair shaft has an effect on the curliness of the individual's hair. A very round shaft allows for fewer disulfide bonds to be present in the hair strand. This means the bonds present are directly in line with one another, resulting in straight hair.

The flatter the hair shaft becomes, the curlier hair gets, because the shape allows more cysteines to become compacted together resulting in a bent shape that, with every additional disulfide bond, becomes curlier in form. As the hair follicle shape determines curl pattern, the hair follicle size determines thickness. While the circumference of the hair follicle expands, so does the thickness of the hair follicle. An individual's hair volume, as a result, can be thin, normal, or thick. The consistency of hair can almost always be grouped into three categories: fine, medium, and coarse. This trait is determined by the hair follicle volume and the condition of the strand. Fine hair has the smallest circumference, coarse hair has the largest circumference, and medium hair is anywhere between the other two. Coarse hair has a more open cuticle than thin or medium hair causing it to be the most porous.

Classification systems
There are various systems that people use to classify their curl patterns. Being knowledgeable of an individual's hair type is a good start to knowing how to take care of one's hair. There is not just one method to discovering one's hair type. Additionally it is possible, and quite normal to have more than one kind of hair type, for instance having a mixture of both type 3a & 3b curls.

Andre Walker system
The Andre Walker Hair Typing System is the most widely used system to classify hair. The system was created by the hairstylist of Oprah Winfrey, Andre Walker. According to this system there are four types of hair: straight, wavy, curly, kinky.

 * Type 1 is straight hair, which reflects the most sheen and also the most resilient hair of all of the hair types. It is hard to damage and immensely difficult to curl this hair texture. Because the sebum easily spreads from the scalp to the ends without curls or kinks to interrupt its path, it is the most oily hair texture of all.
 * Type 2 is wavy hair, whose texture and sheen ranges somewhere between straight and curly hair. Wavy hair is also more likely to become frizzy than straight hair. While type A waves can easily alternate between straight and curly styles, type B and C Wavy hair is resistant to styling.
 * Type 3 is curly hair known to have an S-shape. The curl pattern may resemble a lowercase "s", uppercase "S", or sometimes an uppercase "Z" or lowercase "z". Lack of proper care causes less defined curls.
 * Type 4 is kinky hair, which features a tightly coiled curl pattern (or no discernible curl pattern at all) that is often fragile with a very high density. This type of hair shrinks when wet and because it has fewer cuticle layers than other hair types it is more susceptible to damage.

FIA system
This is a method which classifies the hair by curl pattern, hair-strand thickness and overall hair volume.

Composition
Hair is mainly composed of keratin proteins and keratin-associated proteins (KRTAPs). The human genome encodes 54 different keratin proteins which are present in various amounts in hair. Similarly, humans encode more than 100 different KRTAPs which crosslink keratins in hair. The content of KRTAPs ranges from less than 3% in human hair to 30–40% in echidna quill.

Functions
Many mammals have fur and other hairs that serve different functions. Hair provides thermal regulation and camouflage for many animals; for others it provides signals to other animals such as warnings, mating, or other communicative displays; and for some animals hair provides defensive functions and, rarely, even offensive protection. Hair also has a sensory function, extending the sense of touch beyond the surface of the skin. Guard hairs give warnings that may trigger a recoiling reaction.

Warmth

While humans have developed clothing and other means of keeping warm, the hair found on the head serves primarily as a source of heat insulation and cooling (when sweat evaporates from soaked hair) as well as protection from ultra-violet radiation exposure. The function of hair in other locations is debated. Hats and coats are still required while doing outdoor activities in cold weather to prevent frostbite and hypothermia, but the hair on the human body does help to keep the internal temperature regulated. When the body is too cold, the arrector pili muscles found attached to hair follicles stand up, causing the hair in these follicles to do the same. These hairs then form a heat-trapping layer above the epidermis. This process is formally called piloerection, derived from the Latin words 'pilus' ('hair') and 'erectio' ('rising up'), but is more commonly known as 'having goose bumps' in English. This is more effective in other mammals whose fur fluffs up to create air pockets between hairs that insulate the body from the cold. The opposite actions occur when the body is too warm; the arrector muscles make the hair lie flat on the skin which allows heat to leave.

Protection
In some mammals, such as hedgehogs and porcupines, the hairs have been modified into hard spines or quills. These are covered with thick plates of keratin and serve as protection against predators. Thick hair such as that of the lion's mane and grizzly bear's fur do offer some protection from physical damages such as bites and scratches.

Touch sense
Displacement and vibration of hair shafts are detected by hair follicle nerve receptors and nerve receptors within the skin. Hairs can sense movements of air as well as touch by physical objects and they provide sensory awareness of the presence of ectoparasites. Some hairs, such as eyelashes, are especially sensitive to the presence of potentially harmful matter.

Eyebrows and eyelashes
The eyebrows provide moderate protection to the eyes from dirt, sweat and rain. They also play a key role in non-verbal communication by displaying emotions such as sadness, anger, surprise and excitement. In many other mammals, they contain much longer, whisker-like hairs that act as tactile sensors.

The eyelash grows at the edges of the eyelid and protects the eye from dirt. The eyelash is to humans, camels, horses, ostriches etc., what whiskers are to cats; they are used to sense when dirt, dust, or any other potentially harmful object is too close to the eye. The eye reflexively closes as a result of this sensation.

Eyebrows and eyelashes do not grow beyond a certain length (eyelashes are rarely more than 10 mm long). However, trichomegaly can cause the lashes to grow remarkably long and prominent (in some cases the upper lashes grow to 15 mm long).

Evolution
Hair has its origins in the common ancestor of mammals, the synapsids, about 300 million years ago. It is currently unknown at what stage the synapsids acquired mammalian characteristics such as body hair and mammary glands, as the fossils only rarely provide direct evidence for soft tissues. Skin impression of the belly and lower tail of a pelycosaur, possibly Haptodus shows the basal synapsid stock bore transverse rows of rectangular scutes, similar to those of a modern crocodile, so the age of acquirement of hair logically could not have been earlier than ≈299 ma, based on the current understanding of the animal's phylogeny. An exceptionally well-preserved skull of Estemmenosuchus, a therapsid from the Upper Permian, shows smooth, hairless skin with what appears to be glandular depressions, though as a semi-aquatic species it might not have been particularly useful to determine the integument of terrestrial species. The oldest undisputed known fossils showing unambiguous imprints of hair are the Callovian (late middle Jurassic) Castorocauda and several contemporary haramiyidans, both near-mammal cynodonts, giving the age as no later than ≈220 ma based on the modern phylogenetic understanding of these clades. More recently, studies on terminal Permian Russian coprolites may suggest that non-mammalian synapsids from that era had fur. If this is the case, these are the oldest hair remnants known, showcasing that fur occurred as far back as the latest Paleozoic.

Some modern mammals have a special gland in front of each orbit used to preen the fur, called the harderian gland. Imprints of this structure are found in the skull of the small early mammals like Morganucodon, but not in their cynodont ancestors like Thrinaxodon.

The hairs of the fur in modern animals are all connected to nerves, and so the fur also serves as a transmitter for sensory input. Fur could have evolved from sensory hair (whiskers). The signals from this sensory apparatus is interpreted in the neocortex, a section of the brain that expanded markedly in animals like Morganucodon and Hadrocodium. The more advanced therapsids could have had a combination of naked skin, whiskers, and scutes. A full pelage likely did not evolve until the therapsid-mammal transition. The more advanced, smaller therapsids could have had a combination of hair and scutes, a combination still found in some modern mammals, such as rodents and the opossum.

The high interspecific variability of the size, color, and microstructure of hair often enables the identification of species based on single hair filaments.

In varying degrees most mammals have some skin areas without natural hair. On the human body, glabrous skin is found on the ventral portion of the fingers, palms, soles of feet and lips, which are all parts of the body most closely associated with interacting with the world around us, as are the labia minora and glans penis. There are four main types of mechanoreceptors in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles.

The naked mole-rat (Heterocephalus glaber) has evolved skin lacking in general, pelagic hair covering, yet has retained long, very sparsely scattered tactile hairs over its body. Glabrousness is a trait that may be associated with neoteny.

Evolutionary variation
Primates are relatively hairless compared to other mammals, and hominini such as chimpanzees, have less dense hair than would be expected given their body size for a primate. Evolutionary biologists suggest that the genus Homo arose in East Africa approximately 2 million years ago. Part of this evolution was the development of endurance running and venturing out during the hot times of the day that required efficient thermoregulation through perspiration. The loss of heat through heat of evaporation by means of sweat glands is aided by air currents next to the skin surface, which are facilitated by the loss of body hair.

Another factor in human evolution that also occurred in the prehistoric past was a preferential selection for neoteny, particularly in females. The idea that adult humans exhibit certain neotenous (juvenile) features, not evinced in the other great apes, is about a century old. Louis Bolk made a long list of such traits, and Stephen Jay Gould published a short list in Ontogeny and Phylogeny. In addition, paedomorphic characteristics in women are often acknowledged as desirable by men in developed countries. For instance, vellus hair is a juvenile characteristic. However, while men develop longer, coarser, thicker, and darker terminal hair through sexual differentiation, women do not, leaving their vellus hair visible.

Curly hair

Kinky hair is a uniquely human characteristic, as most mammals have straight hair, including the earliest hominids. Jablonski asserts head hair was evolutionarily advantageous for pre-humans to retain because it protected the scalp as they walked upright in the intense African (equatorial) UV light. While some might argue that, by this logic, humans should also express hairy shoulders because these body parts would putatively be exposed to similar conditions, the protection of the head, the seat of the brain that enabled humanity to become one of the most successful species on the planet (and which also is very vulnerable at birth) was arguably a more urgent issue (axillary hair in the underarms and groin were also retained as signs of sexual maturity). Sometime during the gradual process by which Homo erectus began a transition from furry skin to the naked skin expressed by Homo sapiens, hair texture putatively gradually changed from straight hair (the condition of most mammals, including humanity's closest cousins—chimpanzees) to Afro-textured hair or 'kinky' (i.e. tightly coiled). This argument assumes that curly hair better impedes the passage of UV light into the body relative to straight hair (thus curly or coiled hair would be particularly advantageous for light-skinned hominids living at the equator).

It is substantiated by Iyengar's findings (1998) that UV light can enter into straight human hair roots (and thus into the body through the skin) via the hair shaft. Specifically, the results of that study suggest that this phenomenon resembles the passage of light through fiber optic tubes (which do not function as effectively when kinked or sharply curved or coiled). In this sense, when hominids (i.e. Homo erectus) were gradually losing their straight body hair and thereby exposing the initially pale skin underneath their fur to the sun, straight hair would have been an adaptive liability. By inverse logic, later, as humans traveled farther from Africa and/or the equator, straight hair may have (initially) evolved to aid the entry of UV light into the body during the transition from dark, UV-protected skin to paler skin.

Jablonski's assertions suggest that the adjective "woolly" in reference to Afro-hair is a misnomer in connoting the high heat insulation derivable from the true wool of sheep. Instead, the relatively sparse density of Afro-hair, combined with its springy coils actually results in an airy, almost sponge-like structure that in turn, Jablonski argues, more likely facilitates an increase in the circulation of cool air onto the scalp. Further, wet Afro-hair does not stick to the neck and scalp unless totally drenched and instead tends to retain its basic springy puffiness because it less easily responds to moisture and sweat than straight hair does. In this sense, the trait may enhance comfort levels in intense equatorial climates more than straight hair (which, on the other hand, tends to naturally fall over the ears and neck to a degree that provides slightly enhanced comfort levels in cold climates relative to tightly coiled hair).

Further, it is notable that the most pervasive expression of this hair texture can be found in sub-Saharan Africa; a region of the world that abundant genetic and paleo-anthropological evidence suggests, was the relatively recent (≈200,000-year-old) point of origin for modern humanity. In fact, although genetic findings (Tishkoff, 2009) suggest that sub-Saharan Africans are the most genetically diverse continental group on Earth, Afro-textured hair approaches ubiquity in this region. This points to a strong, long-term selective pressure that, in stark contrast to most other regions of the genomes of sub-Saharan groups, left little room for genetic variation at the determining loci. Such a pattern, again, does not seem to support human sexual aesthetics as being the sole or primary cause of this distribution.

The EDAR locus
A group of studies have recently shown that genetic patterns at the EDAR locus, a region of the modern human genome that contributes to hair texture variation among most individuals of East Asian descent, support the hypothesis that (East Asian) straight hair likely developed in this branch of the modern human lineage subsequent to the original expression of tightly coiled natural afro-hair. Specifically, the relevant findings indicate that the EDAR mutation coding for the predominant East Asian 'coarse' or thick, straight hair texture arose within the past ≈65,000 years, which is a time frame that covers from the earliest of the 'Out of Africa' migrations up to now.

Disease
Ringworm is a fungal disease that targets hairy skin.

Premature greying of hair is another condition that results in greying before the age of 20 years in Europeans, before 25 years in Asians, and before 30 years in Africans.

Hair care
Hair care involves the hygiene and cosmetology of hair including hair on the scalp, facial hair (beard and moustache), pubic hair and other body hair. Hair care routines differ according to an individual's culture and the physical characteristics of one's hair. Hair may be colored, trimmed, shaved, plucked, or otherwise removed with treatments such as waxing, sugaring, and threading.

Removal practices
Depilation is the removal of hair from the surface of the skin. This can be achieved through methods such as shaving. Epilation is the removal of the entire hair strand, including the part of the hair that has not yet left the follicle. A popular way to epilate hair is through waxing.

Shaving
Shaving is accomplished with bladed instruments, such as razors. The blade is brought close to the skin and stroked over the hair in the desired area to cut the terminal hairs and leave the skin feeling smooth. Depending upon the rate of growth, one can begin to feel the hair growing back within hours of shaving. This is especially evident in men who develop a five o'clock shadow after having shaved their faces. This new growth is called stubble. Stubble typically appears to grow back thicker because the shaved hairs are blunted instead of tapered off at the end, although the hair never actually grows back thicker.

Waxing
Waxing involves using a sticky wax and strip of paper or cloth to pull hair from the root. Waxing is the ideal hair removal technique to keep an area hair-free for long periods of time. It can take three to five weeks for waxed hair to begin to resurface again. Hair in areas that have been waxed consistently is known to grow back finer and thinner, especially compared to hair that has been shaved with a razor.

Laser removal
Laser hair removal is a cosmetic method where a small laser beam pulses selective heat on dark target matter in the area that causes hair growth without harming the skin tissue. This process is repeated several times over the course of many months to a couple of years with hair regrowing less frequently until it finally stops; this is used as a more permanent solution to waxing or shaving. Laser removal is practiced in many clinics along with many at-home products.

Cutting and trimming
Because the hair on one's head is normally longer than other types of body hair, it is cut with scissors or clippers. People with longer hair will most often use scissors to cut their hair, whereas shorter hair is maintained using a trimmer. Depending on the desired length and overall health of the hair, periods without cutting or trimming the hair can vary.

Cut hair may be used in wigs. Global imports of hair in 2010 was worth $US 1.24 billion.

Social role
Hair has great social significance for human beings. It can grow on most external areas of the human body, except on the palms of the hands and the soles of the feet (among other areas). Hair is most noticeable on most people in a small number of areas, which are also the ones that are most commonly trimmed, plucked, or shaved. These include the face, ears, head, eyebrows, legs, and armpits, as well as the pubic region. The highly visible differences between male and female body and facial hair are a notable secondary sex characteristic.

The world's longest documented hair belongs to Xie Qiuping (in China), at 5.627 m (18 ft 5.54 in) when measured on 8 May 2004. She has been growing her hair since 1973, from the age of 13.

Indication of status
Healthy hair indicates health and youth (important in evolutionary biology). Hair color and texture can be a sign of ethnic ancestry. Facial hair is a sign of puberty in men. White or gray hair is a sign of age or genetics, which may be concealed with hair dye (not easily for some), although many prefer to assume it (especially if it is a poliosis characteristic of the person since childhood). Pattern baldness in men is usually seen as a sign of aging that may be concealed with a toupee, hats, or religious and cultural adornments; however, the condition can be triggered by various hormonal factors at any age following puberty and is not uncommon in younger men. Although pattern baldness can be slowed down by drugs such as Finasteride and Minoxidil or treated with hair transplants, many men see this as unnecessary effort for the sake of vanity and instead shave their heads. In early modern China, the queue was a male hairstyle in which the hair at the front and top was shaved every 10 days in a style mimicking pattern baldness, while the remaining hair at the back was braided into a long pigtail.

A hairstyle may be an indicator of group membership. During the English Civil War, followers of Oliver Cromwell cropped their hair close to their head in an act of defiance against the curls and ringlets of the king's men, which led to them being nicknamed Roundheads. Recent isotopic analysis of hair is helping to shed further light on sociocultural interaction, giving information on food procurement and consumption in the 19th century. Having bobbed hair was popular among the flappers in the 1920s as a sign of rebellion against traditional roles for women. Female art students known as the Cropheads also adopted the style, notably at the Slade School in London. Regional variations in hirsutism has caused practices regarding hair on the arms and legs to differ. Some religious groups may follow certain rules regarding hair as part of religious observance. The rules often differ for men and women.

Many subcultures have hairstyles which may indicate an unofficial membership. Many hippies, metalheads, and Indian sadhus have long hair, as well many older hipsters. Many punks wear a hairstyle known as a mohawk or other spiked and dyed hairstyles, while skinheads have short-cropped or completely shaved heads. Long stylized bangs were very common for emos, scene kids, and younger hipsters in the 2000s and early 2010s.

Heads were shaved in concentration camps, and head-shaving has been used as punishment, especially for women with long hair. The shaven head is common in military haircuts, while Western monks are known for the tonsure. By contrast, among some Indian holy men, the hair is worn extremely long.

In the time of Confucius (5th century BCE), the Chinese grew out their hair and often tied it, as a symbol of filial piety. Regular hairdressing in some cultures is considered a sign of wealth or status. The dreadlocks of the Rastafari movement were despised early in the movement's history. In some cultures, having one's hair cut can symbolize a liberation from one's past, usually after a trying time in one's life. Cutting the hair also may be a sign of mourning.

Tightly coiled hair in its natural state may be worn in an Afro. This hairstyle was once worn among African Americans as a symbol of racial pride. Given that the coiled texture is the natural state of some African Americans' hair, or perceived as being more "African", this simple style is now often seen as a sign of self-acceptance and an affirmation that the beauty norms of the (eurocentric) dominant culture are not absolute. African Americans as a whole have a variety of hair textures, as they are not an ethnically homogeneous group, but an ad-hoc of different racial admixtures.

The film Easy Rider (1969) includes the assumption that the two main characters could have their long hairs forcibly shaved with a rusty razor when jailed, symbolizing the intolerance of some conservative groups toward members of the counterculture. At the conclusion of England's 1971 Oz trials, the defendants had their heads shaved by the police, causing public outcry. During the appeal trial, they appeared in the dock wearing wigs. A case where a 14-year-old student was expelled from school in Brazil in the mid-2000s, allegedly because of his fauxhawk haircut, sparked national debate and legal action resulting in compensation.

Religious practices
Women's hair may be hidden using headscarves, a common part of the hijab in Islam and a symbol of modesty required for certain religious rituals in Eastern Orthodoxy. Russian Orthodox Church requires all married women to wear headscarves inside the church; this tradition is often extended to all women, regardless of marital status. Orthodox Judaism also commands the use of scarves and other head coverings for married women for modesty reasons. Certain Hindu sects also wear head scarves for religious reasons. Sikhs have an obligation not to cut hair (a Sikh cutting hair becomes 'apostate' which means fallen from religion) and men keep it tied in a bun on the head, which is then covered appropriately using a turban. Multiple religions, both ancient and contemporary, require or advise one to allow their hair to become dreadlocks, though people also wear them for fashion. For men, Islam, Orthodox Judaism, Orthodox Christianity, Roman Catholicism, and other religious groups have at various times recommended or required the covering of the head and sections of the hair of men, and some have dictates relating to the cutting of men's facial and head hair. Some Christian sects throughout history and up to modern times have also religiously proscribed the cutting of women's hair. For some Sunni madhabs, the donning of a kufi or topi is a form of sunnah. Brahmin males are prescribed to shave their heads, but leave a tuft of hair unshaved, worn in the form of a topknot.

In Arabic poetry
Since ancient times, women's long, thick, wavy hair has featured prominently in Arabic poetry. Pre-Islamic poets used only limited imagery to describe women's hair. For example, al-A'sha wrote a verse comparing a lover's hair to "a garden whose grapes dangle down upon me", but Bashshar ibn Burd considered this unusual. One comparison used by early poets, such as Imru al-Qays, was to bunches of dates. In Abbasid times, however, the imagery for hair expanded significantly - particularly for the then-fashionable "love-locks" (sudgh) framing the temples, which came into style at the court of the caliph al-Amin. Hair curls were compared to hooks and chains, letters (such as fa, waw, lam, and nun), scorpions, annelids, and polo sticks. An example was the poet Ibn al-Mu'tazz, who compared a lock of hair and a birthmark to a polo stick driving a ball.

title: Hair


text:
Hawker Siddeley Harrier

The Hawker Siddeley Harrier is a British jet-powered attack aircraft designed and produced by the British aerospace company Hawker Siddeley. It was the first operational ground attack and reconnaissance aircraft with vertical/short takeoff and landing (V/STOL) capabilities and the only truly successful V/STOL design of its era.

It was the first of the Harrier series of aircraft, being developed directly from the Hawker Siddeley Kestrel prototype aircraft following the cancellation of a more advanced supersonic aircraft, the Hawker Siddeley P.1154. In the mid 1960s, the Harrier GR.1 and GR.3 variants were ordered by the British government for the Royal Air Force (RAF). The Harrier GR.1 made its first flight on 28 December 1967, and entered RAF service in April 1969. During the 1970s, the United States opted to procure the aircraft as the AV-8A; it was operated by the US Marine Corps (USMC).

Introduced to service amid the Cold War, the RAF positioned the bulk of their Harriers across West Germany to defend against a potential invasion of Western Europe by the Warsaw Pact forces; the unique abilities of the Harrier allowed the RAF to disperse their forces away from vulnerable airbases. The USMC used their Harriers primarily for close air support, operating from amphibious assault ships, and, if needed, forward operating bases. Harrier squadrons saw several deployments overseas. Its ability to operate with minimal ground facilities and very short runways allowed it to be used at locations unavailable to other fixed-wing aircraft. The Harrier received criticism for having a high accident rate and for a time-consuming maintenance process.

In the 1970s, the British Aerospace Sea Harrier was developed from the Harrier for use by the Royal Navy (RN) on Invincible-class aircraft carriers. Both the Sea Harrier and the Harrier fought in the 1982 Falklands War, in which the aircraft proved to be crucial and versatile. The RN Sea Harriers provided fixed-wing air defence while the RAF Harriers focused on ground-attack missions in support of the advancing British land force. The Harrier was also extensively redesigned as the AV-8B Harrier II and British Aerospace Harrier II by the team of McDonnell Douglas and British Aerospace. During the late 1980s and 1990s, the first-generation aircraft were gradually replaced by the newer Harrier IIs.

Origins
The Harrier's design was derived from the Hawker P.1127. Prior to developing the P.1127, Hawker Aircraft had been working on a replacement for the Hawker Hunter, the Hawker P.1121. The P.1121 was cancelled after the release of the British Government's 1957 Defence White Paper, which advocated a policy shift away from manned aircraft and towards missiles. This policy resulted in the termination of the majority of aircraft development projects then underway for the British military. Hawker sought to quickly move on to a new project and became interested in Vertical Take Off/Landing (VTOL) aircraft, which did not need runways. According to Air Chief Marshal Sir Patrick Hine this interest may have been stimulated by the presence of Air Staff Requirement 345, which sought a V/STOL ground attack fighter for the Royal Air Force.

Design work on the P.1127 was formally started in 1957 by Sir Sydney Camm, Ralph Hooper of Hawker Aircraft, and Stanley Hooker (later Sir Stanley Hooker) of the Bristol Engine Company. The close cooperation between Hawker, the airframe company, and Bristol, the engine company, was viewed by project engineer Gordon Lewis as one of the key factors that allowed the development of the Harrier to continue in spite of technical obstacles and political setbacks. Rather than using rotors or a direct jet thrust, the P.1127 had an innovative vectored thrust turbofan engine, the Pegasus. The Pegasus I was rated at 9000 lb(f) of thrust and first ran in September 1959. A contract for two development prototypes was signed in June 1960 and the first flight followed in October 1960. Of the six prototypes built, three crashed, including one during an air display at the 1963 Paris Air Show.

Tripartite evaluation

In 1961, the United Kingdom, the United States and West Germany jointly agreed to purchase nine aircraft developed from the P.1127, for the evaluation of the performance and potential of V/STOL aircraft. These aircraft were built by Hawker Siddeley and were designated Kestrel FGA.1 by the UK. The Kestrel was strictly an evaluation aircraft and to save money the Pegasus 5 engine was not fully developed as intended, only having 15000 lb(f) of thrust instead of the projected 18200 lb(f). The Tripartite Evaluation Squadron numbered ten pilots; four each from the UK and US and two from West Germany. The Kestrel's first flight took place on 7 March 1964.

A total of 960 sorties had been made during the trials, including 1,366 takeoffs and landings, by the end of evaluations in November 1965. One aircraft was destroyed in an accident and six others were transferred to the United States, assigned the US designation XV-6A Kestrel, and underwent further testing. The two remaining British-based Kestrels were assigned to further trials and experimentation at RAE Bedford with one being modified to use the uprated Pegasus 6 engine.

P.1154
At the time of the development of the P.1127 Hawker and Bristol had also undertaken considerable development work on a supersonic version, the Hawker Siddeley P.1154, to meet a North Atlantic Treaty Organization (NATO) requirement issued for such an aircraft. The design used a single Bristol Siddeley BS100 engine with four swivelling nozzles, in a fashion similar to the P.1127, and required the use of plenum chamber burning (PCB) to achieve supersonic speeds. The P.1154 won the competition to meet the requirement against strong competition from other aircraft manufacturers such as Dassault Aviation's Mirage IIIV. The French government did not accept the decision and withdrew; the NATO requirement was cancelled shortly after in 1965.

The Royal Air Force and the Royal Navy planned to develop and introduce the supersonic P.1154 independently of the cancelled NATO requirement. This ambition was complicated by the conflicting requirements between the two services—while the RAF wanted a low-level supersonic strike aircraft, the Navy sought a twin-engine air defence fighter. Following the election of the Labour Government of 1964 the P.1154 was cancelled, as the Royal Navy had already begun procurement of the McDonnell Douglas Phantom II and the RAF placed a greater importance on the BAC TSR-2's ongoing development. Work continued on elements of the project, such as a supersonic PCB-equipped Pegasus engine, with the intention of developing a future Harrier variant for the decades following cancellation.

Production
Following the collapse of the P.1154's development the RAF began considering a simple upgrade of the existing subsonic Kestrel and issued Requirement ASR 384 for a V/STOL ground attack jet. Hawker Siddeley received an order for six pre-production aircraft in 1965, designated P.1127 (RAF), of which the first made its maiden flight on 31 August 1966. An order for 60 production aircraft, designated as Harrier GR.1, was received in early 1967. The aircraft was named after the Harrier, a small bird of prey.

The Harrier GR.1 made its first flight on 28 December 1967, and it officially entered service with the RAF on 1 April 1969. The aircraft was built in two factories—one in Kingston upon Thames, southwest London, and the other at Dunsfold Aerodrome, Surrey—and underwent initial testing at Dunsfold. The ski-jump technique for launching Harriers from Royal Navy aircraft carriers was extensively trialled at RNAS Yeovilton from 1977. Following these tests ski-jumps were added to the flight decks of all RN carriers from 1979 onwards, in preparation for the new variant for the navy, the Sea Harrier.

In the late 1960s the British and American governments held talks on producing Harriers in the United States. Hawker Siddeley and McDonnell Douglas formed a partnership in 1969 in preparation for American production, but Congressman Mendel Rivers and the House Appropriations Committee held that it would be cheaper to produce the AV-8A on the pre-existing production lines in the United Kingdom—hence all AV-8A Harriers were purchased from Hawker Siddeley. Improved Harrier versions with better sensors and more powerful engines were developed in later years. The USMC received 102 AV-8A and 8 TAV-8A Harriers between 1971 and 1976.

Overview
The Harrier was typically used as a ground attack aircraft, though its manoeuvrability also allows it to effectively engage other aircraft at short ranges. The Harrier is powered by a single Pegasus turbofan engine mounted in the fuselage. The engine is fitted with two air intakes and four vectoring nozzles for directing the thrust generated: two for the bypass flow and two for the jet exhaust. Several small reaction nozzles are also fitted, in the nose, tail and wingtips, for the purpose of balancing during vertical flight. It has two landing gear units on the fuselage and two outrigger landing gear units, one near each wing tip. The Harrier is equipped with four wing and three fuselage pylons for carrying a variety of weapons and external fuel tanks.

The Kestrel and the Harrier were similar in appearance, though approximately 90 per cent of the Kestrel's airframe was redesigned for the Harrier. The Harrier was powered by the more powerful Pegasus 6 engine; new air intakes with auxiliary blow-in doors were added to produce the required airflow at low speed. Its wing was modified to increase area and the landing gear was strengthened. Several hardpoints were installed, two under each wing and one underneath the fuselage; two 30 mm ADEN cannon gun pods could also be fitted to the underside of the fuselage. The Harrier was outfitted with updated avionics to replace the basic systems used in the Kestrel; a navigational-attack system incorporating an inertial navigation system, originally for the P.1154, was installed and information was presented to the pilot by a head-up display and a moving map display.

The Harrier's VTOL abilities allowed it to be deployed from very small prepared clearings or helipads as well as normal airfields. It was believed that, in a high-intensity conflict, air bases would be vulnerable and likely to be quickly knocked out. The capability to scatter Harrier squadrons to dozens of small "alert pads" on the front lines was highly prized by military strategists and the USMC procured the aircraft because of this ability. Hawker Siddeley noted that STOL operation provided additional benefits over VTOL operation, saving fuel and allowing the aircraft to carry more ordnance.

"I still don't believe the Harrier. Think of the millions that have been spent on VTO in America and Russia, and quite a bit in Europe, and yet the only vertical take-off aircraft which you can call a success is the Harrier. When I saw the Harrier hovering and flying backwards under control, I reckoned I'd seen everything. And it's not difficult to fly."

The Harrier, while serving for many decades in various forms, has been criticised on multiple issues; in particular a high accident rate, though Nordeen notes that several conventional single-engine strike aircraft like the Douglas A-4 Skyhawk and LTV A-7 Corsair II had worse accident rates. The Los Angeles Times reported in 2003 that the Harrier "...has amassed the highest major accident rate of any military plane now in service. Forty-five Marines have died in 148 noncombat accidents". Colonel Lee Buland of the USMC declared the maintenance of a Harrier to be a "challenge"; the need to remove the wings before performing most work upon the engine, including engine replacements, meant the Harrier required considerable man-hours in maintenance, more than most aircraft. Buland noted however that the maintenance difficulties were unavoidable in order to create a V/STOL aircraft.

Engine

The Pegasus turbofan jet engine, developed in tandem with the P.1127 then the Harrier, was designed specifically for V/STOL manoeuvring. Bristol Siddeley developed it from their earlier conventional Orpheus turbofan engine as the core with Olympus compressor blades for the fan. The engine's thrust is directed through the four rotatable nozzles. The engine is equipped for water injection to increase thrust and takeoff performance in hot and high altitude conditions; in normal V/STOL operations the system would be used in landing vertically with a heavy weapons load. The water injection function had originally been added following the input of US Air Force Colonel Bill Chapman, who worked for the Mutual Weapons Development Team. Water injection was necessary in order to generate maximum thrust, if only for a limited time, and was typically used during landing, especially in high ambient temperatures.

The aircraft was initially powered by the Pegasus 6 engine which was replaced by the more powerful Pegasus 11 during the Harrier GR.1 to GR.3 upgrade process. The primary focus throughout the engine's development was on achieving high performance with as little weight as possible, tempered by the amount of funding that was available. Following the Harrier's entry to service the focus switched to improving reliability and extending engine life; a formal joint US–UK Pegasus Support Program operated for many years and spent a £3-million annual budget to develop engine improvements. Several variants have been released; the latest is the Pegasus 11–61 (Mk 107), which provides 23,800 lbf (106 kN) thrust, more than any previous engine.

Controls and handling

The Harrier has been described by pilots as "unforgiving". The aircraft is capable of both forward flight (where it behaves in the manner of a typical fixed-wing aircraft above its stall speed), as well as VTOL and STOL manoeuvres (where the traditional lift and control surfaces are useless) requiring skills and technical knowledge usually associated with helicopters. Most services demand great aptitude and extensive training for Harrier pilots, as well as experience in piloting both types of aircraft. Trainee pilots are often drawn from highly experienced and skilled helicopter pilots.

In addition to normal flight controls, the Harrier has a lever for controlling the direction of the four vectoring nozzles. It is viewed by senior RAF officers as a significant design success, that to enable and control the aircraft's vertical flight required only a single lever added in the cockpit. For horizontal flight, the nozzles are directed rearwards by shifting the lever to the forward position; for short or vertical takeoffs and landings, the lever is pulled back to point the nozzles downwards.

The Harrier has two control elements not found in conventional fixed-wing aircraft: the thrust vector and the reaction control system. The thrust vector refers to the slant of the four engine nozzles and can be set between 0° (horizontal, pointing directly backwards) and 98° (pointing down and slightly forwards). The 90° vector is normally deployed for VTOL manoeuvring. The reaction control is achieved by manipulating the control stick and is similar in action to the cyclic control of a helicopter. While irrelevant during forward flight mode, these controls are essential during VTOL and STOL manoeuvres.

The wind direction is a critical factor in VTOL manoeuvres. The procedure for vertical takeoff involves facing the aircraft into the wind. The thrust vector is set to 90° and the throttle is brought up to maximum, at which point the aircraft leaves the ground. The throttle is trimmed until a hover state is achieved at the desired altitude. The short-takeoff procedure involves proceeding with normal takeoff and then applying a thrust vector (less than 90°) at a runway speed below normal takeoff speed; usually the point of application is around 65 kn. For lower takeoff speeds the thrust vector is greater. The reaction control system involves a thrusters at key points in the aircraft's fuselage and nose, also the wingtips. Thrust from the engine can be temporarily syphoned to control and correct the aircraft's pitch and roll during vertical flight.

Rotating the vectored thrust nozzles into a forward-facing position during normal flight is called vectoring in forward flight, or "VIFFing". This is a dog-fighting tactic, allowing for more sudden braking and higher turn rates. Braking could cause a chasing aircraft to overshoot and present itself as a target for the Harrier it was chasing, a combat technique formally developed by the USMC for the Harrier in the early 1970s.

Differences between versions
The two largest users of the Harrier were the Royal Air Force and the United States Marine Corps (USMC). The exported model of the aircraft operated by the USMC was designated the AV-8A Harrier, which was broadly similar to the RAF's Harrier GR.1. Changes included the removal of all magnesium components, which corroded quickly at sea, and the integration of American radios and Identification Friend or Foe (IFF) systems; furthermore the outer pylons, unlike the RAF aircraft, were designed from delivery to be equipped with self-defence AIM-9 Sidewinder heat-seeking air-to-air missiles. Most of the AV-8As had been delivered with the more powerful Pegasus engine used in the GR.3 instead of the one used in the earlier GR.1. Two-seat Harriers were operated for training purposes; the body was stretched and a taller tail fin added. The RAF trained in the T.2 and T.4 versions, while T.4N and T.8 were training versions the Navy's Sea Harrier, with appropriate fittings. The US and Spain flew the TAV-8A and TAV-8S, respectively.

All RAF GR.1s and the initial AV-8As were fitted with the Ferranti FE541 inertial navigation/attack suite, but these were replaced in the USMC Harriers by a simpler Interface/Weapon Aiming Computer to aid quick turnaround between missions. The Martin-Baker ejection seats were also replaced by the Stencel SEU-3A in the American aircraft. The RAF had their GR.1 aircraft upgraded to the GR.3 standard, which featured improved sensors, a nose-mounted laser tracker, the integration of electronic countermeasure (ECM) systems and a further upgraded Pegasus Mk 103. The USMC upgraded their AV-8As to the AV-8C configuration; this programme involved the installation of ECM equipment and adding a new inertial navigation system to the aircraft's avionics. Substantial changes were the Lift Improvement Devices, to increase VTOL performance; at the same time several airframe components were restored or replaced to extend the life of the aircraft. Spain's Harriers, designated AV-8S or VA.1 Matador for the single-seater and TAV-8S or VAE.1 for the two-seater, were almost identical to USMC Harriers differing only in the radios fitted.

The Royal Navy's Fleet Air Arm (FAA) operated a substantially modified variant of the Harrier, the British Aerospace Sea Harrier. The Sea Harrier was intended for multiple naval roles and was equipped with radar and Sidewinder missiles for air combat duties as part of fleet air defence. The Sea Harrier was also fitted with navigational aids for carrier landings, modifications to reduce corrosion by seawater and a raised bubble-canopy covered cockpit for better visibility. The aircraft were later equipped to use AIM-120 AMRAAM beyond-visual-range anti-aircraft missiles and the more advanced Blue Vixen radar for longer range air-to-air combat, as well as Sea Eagle missiles for conducting anti-ship missions.

The McDonnell Douglas AV-8B Harrier II is the latest Harrier variant, a second-generation series to replace the first generation of Harrier jets already in service; all the above variants of the Harrier have mainly been retired with the Harrier II taking their place in the RAF, USMC and FAA. In the 1970s the United Kingdom considered two options for replacing their existing Harriers: joining McDonnell Douglas (MDC) in developing the BAE Harrier II, or the independent development of a "Big Wing" Harrier. This proposal would have increased the wing area from 200 to 250 ft2, allowing for significant increases in weapons load and internal fuel reserves. The option of cooperation with MDC was chosen in 1982 over the more risky isolated approach. The original Harrier served as the basis for the British Aerospace Sea Harrier as it was required to fill the fighter role.

Royal Air Force
The first RAF squadron to be equipped with the Harrier GR.1, No. 1 Squadron, started to convert to the aircraft at RAF Wittering in April 1969. An early demonstration of the Harrier's capabilities was the participation of two aircraft in the Daily Mail Transatlantic Air Race in May 1969, flying between St Pancras railway station, London and central Manhattan with the use of aerial refuelling. The Harrier completed the journey in 6 hours 11 minutes. Two Harrier squadrons were established in 1970 at the RAF's air base in Wildenrath to be part of its air force in Germany; another squadron was formed there two years later. In 1977, these three squadrons were moved forward to the air base at Gütersloh, closer to the prospective front line in the event of an outbreak of a European war. One of the squadrons was disbanded and its aircraft distributed between the other two.

In RAF service, the Harrier was used in close air support (CAS), reconnaissance, and other ground-attack roles. The flexibility of the Harrier led to a long-term heavy deployment in West Germany as a conventional deterrent and potential strike weapon against Soviet aggression; from camouflaged rough bases the Harrier was expected to launch attacks on advancing armour columns from East Germany. Harriers were also deployed to bases in Norway and Belize, a former British colony. No. 1 Squadron was specifically earmarked for Norwegian operations in the event of war, operating as part of Allied Forces Northern Europe. The Harrier's capabilities were necessary in the Belize deployment, as it was the only RAF combat aircraft capable of safely operating from the airport's short runway; British forces had been stationed in Belize for several years due to tensions over a Guatemalan claim to Belizean territory; the forces were withdrawn in 1993, two years after Guatemala recognized the independence of Belize.

In the Falklands War (Guerra de las Malvinas) in 1982, 10 Harrier GR.3s of No. 1 Squadron operated from the aircraft carrier HMS Hermes (R12). As the RAF Harrier GR.3 had not been designed for naval service, the 10 aircraft had to be rapidly modified prior to the departure of the task force. Special sealants against corrosion were applied and a new deck-based inertial guidance aid was devised to allow the RAF Harrier to land on a carrier as easily as the Sea Harrier. Transponders to guide aircraft back to the carriers during night-time operations were also installed, along with flares and chaff dispensers.

As there was little space on the carriers, two requisitioned merchant container ships, SS Atlantic Conveyor and SS Atlantic Causeway, were modified with temporary flight decks and used to carry Harriers and helicopters to the South Atlantic. The Harrier GR.3s focused on providing close air support to the ground forces on the Falklands and attacking Argentine positions; suppressing enemy artillery was often a high priority. Sea Harriers were also used in the war, primarily conducting fleet air defence and combat air patrols against the threat of attacking Argentine fighters. However, both Sea Harriers and Harrier GR.3s were used in ground-attack missions against the main airfield and runway at Stanley.

If most of the Sea Harriers had been lost, the GR.3s would have replaced them in air patrol duties, even though the Harrier GR.3 was not designed for air defence operations; as such the GR.3s quickly had their outboard weapons pylons modified to take air-to-air Sidewinder missiles. From 10 to 24 May 1982, prior to British forces landing in the Falklands, a detachment of three GR.3s provided air defence for Ascension Island until three F-4 Phantom IIs arrived to take on this responsibility. During the Falklands War, the greatest threats to the Harriers were deemed to be surface-to-air missiles (SAMs) and small arms fire from the ground. In total, four Harrier GR.3s and six Sea Harriers were lost to ground fire, accidents, or mechanical failure. More than 2,000 Harrier sorties were conducted during the conflict—equivalent to six sorties per day per aircraft.

Following the Falklands War, British Aerospace explored the Skyhook, a new technique to operate Harriers from smaller ships. Skyhook would have allowed the launching and landing of Harriers from smaller ships by holding the aircraft in midair by a crane; secondary cranes were to hold weapons for rapid re-arming. This would potentially have saved fuel and allowed for operations in rougher seas. The system was marketed to foreign customers, and it was speculated that Skyhook could be applied to large submarines such as the Russian Typhoon-class submarine, but the system attracted no interest.

The first generation of Harriers did not see further combat with the RAF after the Falklands War, although they continued to serve for years afterwards. As a deterrent against further Argentine invasion attempts, No. 1453 Flight RAF was deployed to the Falkland Islands from August 1983 to June 1985. However the second generation Harrier IIs saw action in Bosnia, Iraq, and Afghanistan. The first generation Hawker Siddeley airframes were replaced by the improved Harrier II, which had been developed jointly between McDonnell Douglas and British Aerospace.

United States Marine Corps
The United States Marine Corps began showing a significant interest in the aircraft around the time the first RAF Harrier squadron was established in 1969, and this motivated Hawker Siddeley to further develop the aircraft to encourage a purchase. Although there were concerns in Congress about multiple coinciding projects in the close air support role, the Marine Corps were enthusiastic about the Harrier and managed to overcome efforts to obstruct its procurement.

The Marine Corps accepted its first AV-8A on 6 January 1971, at Dunsfold Aerodrome, England and began testing it at Naval Air Station Patuxent River on 26 January. The AV-8A entered service with the Marine Corps in 1971, replacing other aircraft in the Marines' attack squadrons. The service became interested in performing ship-borne operations with the Harrier. Admiral Elmo Zumwalt promoted the concept of a Sea Control Ship, a 15,000-ton light carrier equipped with Harriers and helicopters, to supplement the larger aircraft carriers of the US Navy. An amphibious assault ship, USS Guam (LPH-9), was converted into the Interim Sea Control Ship and operated as such between 1971 and 1973 with the purpose of studying the limits and possible obstacles for operating such a vessel. Since then the Sea Control Ship concept has been subject to periodic re-examinations and studies, often in the light of budget cuts and questions over the use of supercarriers.

Other exercises were performed to demonstrate the AV-8A's suitability for operating from various amphibious assault ships and aircraft carriers, including a deployment of 14 Harriers aboard USS Franklin D. Roosevelt (CV-42) for six months in 1976. The tests showed, amongst other things, that the Harrier was capable of performing in weather where conventional carrier aircraft could not. In support of naval operations, the USMC devised and studied several methods to further integrate the Harrier. One result was Arapaho, a stand-by system to rapidly convert civilian cargo ships into seagoing platforms for operating and maintaining a handful of Harriers, to be used to augment the number of available ships to deploy upon.

When the reactivation of the Iowa-class battleships was under consideration, a radical design for a battleship-carrier hybrid emerged that would have replaced the ship's rear turret with a flight deck, complete with a hangar and two ski jumps, for operating several Harriers. However, the USMC considered the need for naval gunfire support to be a greater priority than additional platforms for carrier operations, while the cost and delay associated with such elaborate conversions was significant, and the concept was dropped.

The Marines Corps' concept for deploying the Harriers in a land-based expeditionary role focused on aggressive speed. Harrier forward bases and light maintenance facilities were to be set up in under 24 hours on any prospective battle area. The forward bases, containing one to four aircraft, were to be located 20 mi from the forward edge of battle (FEBA), while a more established permanent airbase would be located around 50 mi from the FEBA. The close proximity of forward bases allowed for a far greater sortie rate and reduced fuel consumption.

The AV-8A's abilities in air-to-air combat were tested by the Marine Corps by conducting mock dogfights with McDonnell Douglas F-4 Phantom IIs; these exercises trained pilots to use the vectoring-in-forward-flight (VIFF) capability to outmanoeuvre their opponents and showed that the Harriers could act as effective air-to-air fighters at close range. The success of Harrier operations countered scepticism of V/STOL aircraft, which had been judged to be expensive failures in the past. Marine Corps officers became convinced of the military advantages of the Harrier and pursued extensive development of the aircraft.

Starting in 1979, the USMC began upgrading their AV-8As to the AV-8C configuration—the work focused mainly on extending useful service lives and improving VTOL performance. The AV-8C and the remaining AV-8A Harriers were retired by 1987. These were replaced by the Harrier II, designated as the AV-8B, which was introduced into service in 1985. The performance of the Harrier in USMC service led to calls for the United States Air Force to procure Harrier IIs in addition to the USMC's own plans, but these never resulted in Air Force orders. Since the late 1990s, the AV-8B has been slated to be replaced by the F-35B variant of the Lockheed Martin F-35 Lightning II, a more modern V/STOL jet aircraft.

Like the next generation AV-8Bs, nevertheless, the AV-8A/C Harriers suffered many accidents, with around 40 aircraft lost and some 30 pilots killed during the 1970s and 1980s.

Other operators

Due to the Harrier's unique characteristics it attracted a large amount of interest from other nations, often as attempts to make their own V/STOL jets were unsuccessful, such as in the cases of the American XV-4 Hummingbird and the German VFW VAK 191B. Operations by the USMC aboard USS Nassau (LHA-4) in 1981 and by British Harriers and Sea Harriers in the Falklands War proved that the aircraft was highly effective in combat. These operations also demonstrated that "Harrier Carriers" provided a powerful presence at sea without the expense of big deck carriers.

Following the display of Harrier operations from small carriers, the navies of Spain and later Thailand bought the Harrier for use as their main carrier-based fixed-wing aircraft. Spain's purchase of Harriers was complicated by long-standing political friction between the British and Spanish governments of the era; even though the Harriers were manufactured in the UK they were sold to Spain with the US acting as an intermediary. During tests in November 1972, the British pilot John Farley showed that the wooden deck of Dédalo was able to withstand the temperature of the gases generated by the Harrier. Since 1976, the Spanish Navy operated the AV-8S Matador from their aircraft carrier SPANISH AIRCRAFT CARRIER Dédalo (formerly the USS Cabot (CVL-28)); the aircraft provided both air defence and strike capabilities for the Spanish fleet. Spain later purchased five Harriers directly from the British government mainly to replace losses.

Hawker Siddeley aggressively marketed the Harrier for export. At one point the company was holding talks with Australia, Brazil, Switzerland, India and Japan. Of these only India became a customer, purchasing the Sea Harrier. At one point China came very close to becoming an operator of the first generation Harrier. Following an overture by the UK in the early 1970s, when relations with the West were warming, China became interested in the aircraft as it sought to modernise its armed forces; British Prime Minister James Callaghan noted significant hostility from the USSR over the sales bid. The deal was later cancelled by the UK as part of a diplomatic backlash after China invaded Vietnam in 1979.

The Spanish Navy, Thai Navy, Royal Air Force, and U.S. Marine Corps have all retired their first-generation Harriers. Spain sold seven single-seat and two twin-seat Harriers to Thailand in 1998. The Royal Thai Navy's AV-8S Matadors were delivered as part of the air wing deployed on the new light aircraft carrier HTMS Chakri Naruebet. The Thai Navy had from the start significant logistical problems keeping the Harriers operational due to a shortage of funds for spare parts and equipment, leaving only a few Harriers serviceable at a time. In 1999, two years after being delivered, only one airframe was in airworthy condition. Around 2003, Thailand considered acquiring former Royal Navy Sea Harriers, which were more suitable for maritime operations and better equipped for air defence, to replace their AV-8S Harriers; this investigation did not progress to a purchase. The last first-generation Harriers were retired by Thailand in 2006.

Potential operators
Some countries almost purchased Harriers. British Aerospace held talks with Argentina, Australia, Brazil, China, Switzerland, India, and Japan.

Argentina
When the Argentinian Navy looked for newer fighters in 1968 the US government only offered old A-4A planes instead of the A-4Fs Argentina wanted. Argentina contacted the British government in 1969 and expressed interest in buying from six to twelve Harrier GR.1s. In 1969 the Argentinian Navy received its second carrier, ARA Veinticinco de Mayo, from the Netherlands. On her voyage home, Hawker Siddeley demonstrated a RAF Harrier GR.Mk.1 (XV757) but Argentina opted for the A-4Q Skyhawk instead. There were several problems to supply Argentina with Harrier jets and engines that prevented the deal from being closed, and when the US learned of the Harrier negotiations they quickly offered a better deal to Argentina. Some years later, before the 1982 war, British officials again offered Argentina an aircraft carrier and Sea Harrier aircraft.

Australia
Planning for a HMAS Melbourne aircraft carrier replacement began in 1981. After considering American, Italian, and Spanish designs, the Australian government accepted a British offer to sell HMS Invincible (R05), which would be operated with Harriers and helicopters. However, the Royal Navy withdrew the offer after the Falklands War, and the 1983 election of the Australian Labor Party led to the cancellation of plans to replace Melbourne.

China
As early as 1972 the Chinese government started negotiating a purchase of up to 200 Harrier aircraft. Due to internal political issues, China put the negotiations on hold. In 1977 Li Chiang, the Chinese Minister of Foreign Trade, visited the UK and British Aerospace organised a Harrier flying demonstration. In November 1978, the Harrier-demonstration was repeated for the Chinese Vice-Premier Wang Chen during his UK visit. The Harrier deal would have meant British Government ignored United States laws that prohibited such sales to communist countries. The Soviet Union was also actively opposed to the UK selling weapons to the Chinese. In spite of that, British Aerospace convinced China that the Harrier was an effective close-support fighter and was good enough to act in a defensive role. In 1979, the Anglo-Sino deal was nearly finalised before being cancelled by the Sino-Vietnamese War.

Switzerland
The Swiss Air Force was interested in purchasing some Harriers as its doctrine was to operate in hidden and dispersed locations during the Cold War. British Aerospace held talks with Switzerland offering AV-8s to replace De Havilland Venoms. A demonstration was made by test pilot John Farley and XV742/G-VSTO in 1971.

Variants

 * Harrier GR.1, GR.1A, GR.3: Single-seat versions for the RAF.  The RAF ordered 118 of the GR.1/GR.3 series, with the last production aircraft delivery in December 1986. 122 built.
 * AV-8A, AV-8C Harrier: Single-seat versions for the US Marine Corps. The USMC ordered 102 AV-8As (company designation: Harrier Mk. 50). The AV-8C was an upgrade to the AV-8A. 110 built.
 * AV-8S Matador : Export version of the AV-8A Harrier for the Spanish Navy, who designated them as VA-1 Matador; later sold to the Royal Thai Navy. 10 built.

 * Harrier T.2, T.2A, T.4, T.4A: Two-seat training versions for the RAF, with a stretched body and taller tail fin. 25 built.
 * Harrier T.4N, T.8, T.60: Two-seat training versions for the Royal Navy and Indian Navy with avionics based on the Sea Harrier.
 * TAV-8A Harrier : Two-seat training version for the USMC, powered by a Pegasus Mk 103.
 * TAV-8S Matador: Two-seat training version for the Spanish Navy and later sold to the Royal Thai Navy.

Operators

 * Indian Navy (see Sea Harrier)
 * Indian Navy (see Sea Harrier)
 * Spanish Navy
 * Royal Thai Navy
 * Royal Air Force
 * Royal Navy
 * United States Marine Corps
 * Royal Air Force
 * Royal Navy
 * United States Marine Corps
 * United States Marine Corps

Belize
No. 1417 Flight RAF
 * GR.3
 * ZD669 – Philip S. W. Goldson International Airport, Ladyville, Belize

Canada

 * AV-8A
 * 158966 – Canada Aviation and Space Museum, Ottawa, Ontario

China

 * GR.3
 * XZ965 – Beijing Air and Space Museum

Germany

 * GR.1
 * XV278 – Luftwaffenmuseum der Bundeswehr, Gatow
 * GR.3
 * XZ998 – Flugausstellung Hermeskeil at Hermeskeil

Poland

 * GR.3
 * XW919 – Polish Aviation Museum, Kraków, Poland

New Zealand

 * GR.3
 * XZ129 – Ashburton Aviation Museum, Ashburton, New Zealand

Thailand

 * AV-8S
 * 3109 – Royal Thai Air Force Museum

United Kingdom

 * GR.1
 * XV277 – National Museum of Flight, East Fortune
 * XV281 (Under Restoration) – South Yorkshire Aircraft Museum, Doncaster, South Yorkshire
 * XV741 – Brooklands Museum, Surrey

 * GR.3
 * XV744 – Tangmere Military Aviation Museum, Chichester, West Sussex
 * XV748 – Yorkshire Air Museum, Elvington
 * XV751 – Gatwick Aviation Museum, Surrey
 * XV752 – South Yorkshire Aircraft Museum, Doncaster, South Yorkshire
 * XV753 – Classic Air Force, St Mawgan, Newquay, Cornwall
 * XV779 – RAF Wittering (Gate Guardian)
 * XZ133 – Imperial War Museum, Duxford
 * XZ964 – Royal Engineers Museum, Gillingham, Kent
 * XZ968 – Muckleburgh Collection, Norfolk
 * XZ997 – RAF Museum, Hendon
 * XZ971 – MoD Donnington, Telford
 * ZD667 – Bentwaters Cold War Museum, Suffolk
 * Mk.52 G-VTOL
 * ZA250 – Brooklands Museum, Surrey
 * T.2
 * XW269 – Caernarfon Airworld Aviation Museum, Gwynedd
 * T.4
 * XW934 – Farnborough Air Sciences Trust, Farnborough, Hampshire
 * XW268 – Coventry University, Engineering and computing building, Coventry, West Midlands
 * XW268 – City of Norwich Aviation Museum, Norfolk
 * AV-8A
 * 159233 – Imperial War Museum North

United States

 * AV-8A
 * 158695 – Air Park, MCAS Yuma, Yuma, Arizona
 * 159239 – San Diego Air and Space Museum, San Diego, California
 * 158963 – Craven County Regional Airport, Grantham, North Carolina
 * 158976 – City of Havelock, Havelock, North Carolina
 * Cockpit on display at Moffett Historical Museum, Moffett Federal Airfield, California

 * TAV-8A
 * 159381 – Oakland Aviation Museum, Oakland, California
 * 159382 – Pima Air & Space Museum, Tucson, Arizona
 * AV-8C
 * 158387 – Fort Worth Aviation Museum, Fort Worth, Texas
 * 158710 – Quonset Air Museum, North Kingstown, Rhode Island
 * 158959 – Pacific Coast Air Museum, Santa Rosa, California
 * 158975 – National Naval Aviation Museum, NAS Pensacola, Pensacola, Florida
 * 158977 – Museum of Flight, Seattle, Washington
 * 159232 – Intrepid Sea, Air & Space Museum, New York City, New York
 * 159238 – Hangar 25 Museum, Webb AFB (formerly), Big Spring, Texas
 * 159241 – Pima Air & Space Museum, Tucson, Arizona
 * 159247 – Naval Inventory Control Point (NAVICP) Philadelphia, Philadelphia, Pennsylvania
 * 159249 – United States Naval Museum of Armament and Technology, NCC China Lake (North), Ridgecrest, California

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Hawker Siddeley Harrier


text:
Hawker Harrier

The Hawker Harrier was a British experimental biplane torpedo bomber aircraft built by Hawker Aircraft to a specification issued in the 1920s for the Royal Air Force.

Development
In 1925, the British Air Ministry laid down specifications for a high altitude bomber to replace the Hawker Horsley and for a coastal torpedo bomber (Specifications 23/25 and 24/25). As these specifications were similar, the Air Ministry announced that a single competition would be held to study aircraft submitted for both specifications.

Sydney Camm of Hawker Aircraft designed the Harrier to meet the requirements of Specification 23/25, with the prototype (J8325) first flying in February 1927, the first of the competitors for the two specifications to fly. The Harrier was a two-seat biplane with single-bay wings powered by a geared Bristol Jupiter VIII radial engine. It was armed with one .303 in (7.7 mm) Vickers machine gun and one .303 in (7.7 mm) Lewis gun carrying a maximum of 1000 lb of bombs.

The prototype Harrier was tested at the Aeroplane and Armament Experimental Establishment (A & AEE) at Martlesham Heath in November 1927, where, while it met the requirements of Specification 23/25 and had satisfactory handling, the geared engine meant that it was underpowered, and it had an inferior bombload to the Hawker Horsley, the aircraft it was meant to replace. It was therefore modified to carry a torpedo. On testing the modified aircraft, however, it was found to still be underpowered, being incapable of taking off with a torpedo, gunner and full fuel load. It was therefore not considered further, the competition ultimately being won by the Vickers Vildebeest.

The prototype was used by Bristol as an engine testbed, flying with the 870 hp Bristol Hydra and the 495 hp Bristol Orion engines.

title: Hawker Harrier