title: Stuart Sutcliffe

text: While studying in West Germany, Sutcliffe began suffering from intense headaches and experiencing acute light sensitivity. In February 1962, he collapsed in the middle of an art class after complaining of head pains. German doctors performed tests, but were unable to determine what was causing the headaches. After collapsing again on 10 April 1962, he was taken to a hospital, but died in the ambulance on the way there. The cause of death was later found to have been a brain haemorrhage – severe bleeding in the right ventricle of his brain.


title: Stuart Sutcliffe

text: Sutcliffe was the eldest child of Martha (known as Millie; 1907–1983), a schoolteacher at an infants' school and Charles Sutcliffe (25 May 1905 – 18 March 1966) a senior civil servant. Sutcliffe's father had moved to Liverpool to help with wartime work in 1943 and subsequently signed on as a ship's engineer, and so was often at sea during his son's early years. Sutcliffe had two younger sisters, Pauline and Joyce, as well as three older half-brothers, Joe, Ian, and Charles, and an older half-sister, Mattie, from his father's first marriage, to a woman whose name was also Martha.


title: Stuart Sutcliffe

text: Sutcliffe was born at the Edinburgh Royal Maternity Hospital and Simpson Memorial Maternity Pavilion in Edinburgh, Scotland, and after his family moved to England, he was brought up at 37 Aigburth Drive in Liverpool. He attended Park View Primary School, Huyton (1946–1951), and Prescot Grammar School from 4 September 1951 to 1956. When Sutcliffe's father returned home on leave, he invited his son and art college classmate Rod Murray (also Sutcliffe's housemate and best friend), for a "real good booze-up", slipping £10 into Sutcliffe's pocket before disappearing for another six months. Beatles' biographer Philip Norman wrote that Charles Sutcliffe was a heavy drinker and physically cruel to his wife, which the young Sutcliffe had witnessed.


title: Stuart Sutcliffe

text: During his first year at the Liverpool College of Art, Sutcliffe worked as a bin man on the Liverpool Corporation's waste collection trucks. Lennon was introduced to Sutcliffe by Bill Harry, a mutual friend, when all three were studying at the Liverpool College of Art. According to Lennon, Sutcliffe had a "marvellous art portfolio" and was a very talented painter who was one of the "stars" of the school. He helped Lennon to improve his artistic skills, and with others, worked with him when Lennon had to submit work for exams.


title: Stuart Sutcliffe

text: Sutcliffe shared a flat with Murray at 9 Percy Street, Liverpool, before being evicted and moving to Hillary Mansions at 3 Gambier Terrace, the home of another art student, Margaret Chapman, who vied with Sutcliffe to be the best painter in class. The flat was opposite the new Anglican cathedral in the rundown area of Liverpool 8, with bare lightbulbs and a mattress on the floor in the corner. Lennon moved in with Sutcliffe in early 1960. (Paul McCartney later admitted that he was jealous of Sutcliffe's relationship with Lennon, as he had to take a "back seat" to Sutcliffe.)


title: Stuart Sutcliffe

text: Sutcliffe and his flatmates painted the rooms yellow and black, which their landlady did not appreciate. On another occasion the tenants, needing to keep warm, burned the flat's furniture.


title: Stuart Sutcliffe

text: After talking to Sutcliffe one night at the Casbah Coffee Club (owned by Pete Best's mother, Mona Best), Lennon and McCartney persuaded Sutcliffe to buy a Höfner President 500/5 model bass guitar on hire-purchase from Frank Hessey's Music Shop. Sutcliffe's prior musical experience consisted of singing in the local church choir in Huyton (his mother had insisted on piano lessons for him since the age of nine), playing bugle in the Air Training Corps, and his father having taught him some chords on the guitar.


title: Stuart Sutcliffe

text: In May 1960, Sutcliffe joined Lennon, McCartney, and George Harrison (then known as "the Silver Beatles"). Sutcliffe's fingers would often blister during long rehearsals, as he had never practised long enough for his fingers to become calloused, even though he had previously played acoustic guitar. He started acting as a booking agent for the group, and they often used his Gambier Terrace flat as a rehearsal room.


title: Stuart Sutcliffe

text: In July 1960, the Sunday newspaper "The People" ran an article entitled "The Beatnik Horror" that featured a photograph taken in the flat below Sutcliffe's of a teenaged Lennon lying on the floor, with Sutcliffe standing by a window. As they had often visited the Jacaranda club, its owner, Allan Williams, arranged for the photograph to be taken, subsequently taking over from Sutcliffe to book concerts for the group: Lennon, McCartney, Harrison and Sutcliffe. The Beatles' subsequent name change came during an afternoon in the Renshaw Hall bar when Sutcliffe, Lennon, and Lennon's girlfriend, Cynthia Powell, thought up names similar to Holly's band, the Crickets, and came up with Beetles.


title: Stuart Sutcliffe

text: Sutcliffe's playing style was elementary, mostly sticking to root notes of chords. Harry—an art school friend and founder and editor of the "Mersey Beat" newspaper—complained to Sutcliffe that he should be concentrating on art and not music, as he thought that Sutcliffe was a competent musician whose talents would be better used in the visual arts. While Sutcliffe is often described in Beatles' biographies as appearing very uncomfortable onstage and often playing with his back to the audience, their drummer at the time, Best, denies this. He recalls Sutcliffe as being usually good-natured and "animated" before an audience. When the Beatles auditioned for Larry Parnes at the Wyvern Club, Seel Street, Liverpool, Williams later claimed that Parnes would have taken the group as the backing band for Billy Fury for £10 per week (), but as Sutcliffe turned his back to Parnes throughout the audition—because, as Williams believed, Sutcliffe could not play very well—Parnes said that he would employ the group only if they got rid of Sutcliffe. Parnes later denied this, stating his only concern was that the group had no permanent drummer. Klaus Voormann regarded Sutcliffe as a good bass player, although Beatles' historian Richie Unterberger described Sutcliffe's bass playing as an "artless thump".


title: Stuart Sutcliffe

text: Sutcliffe's profile grew after he began wearing Ray-Ban sunglasses and tight trousers. Sutcliffe's high spot was singing "Love Me Tender", which drew more applause than the other Beatles, and increased the friction between him and McCartney. Lennon also started to criticise Sutcliffe, making jokes about Sutcliffe's size and playing. On 5 December 1960, Harrison was sent back to Britain for being under-age. McCartney and Best were deported for attempted arson at the Bambi Kino, which left Lennon and Sutcliffe in Hamburg. Lennon took a train home, but as Sutcliffe had a cold he stayed in Hamburg. Sutcliffe later borrowed money from his girlfriend, Astrid Kirchherr, in order to fly back to Liverpool on Friday, 20 January 1961, although he returned to Hamburg in March 1961, with the other Beatles.


title: Stuart Sutcliffe

text: In July 1961, Sutcliffe decided to leave the group to continue painting. After being awarded a postgraduate scholarship, he enrolled at Hochschule für bildende Künste Hamburg, where he studied under the tutelage of Eduardo Paolozzi. He briefly lent McCartney his bass until the latter could earn enough to buy a specially made smaller left-handed Höfner 500/1 bass guitar of his own in June 1961, but specifically asked McCartney (who is left-handed) not to change the strings around or restring the instrument, so McCartney had to play the bass as it was. In 1967, a photo of Sutcliffe was among those on the cover of the "Sgt. Pepper's Lonely Hearts Club Band" album (extreme left, in front of fellow artist Aubrey Beardsley).


title: Stuart Sutcliffe

text: Sutcliffe met Astrid Kirchherr in the Kaiserkeller club, where she had gone to watch the Beatles perform. She had been brought up by her widowed mother, Nielsa Kirchherr, on Eimsbütteler Strasse, in a wealthy part of the Hamburg suburb of Altona. After a photo session with the Beatles, Kirchherr invited them to her mother's house for tea and showed them her bedroom, which she had decorated in black, including the furniture, with silver foil on the walls and a large tree branch hanging from the ceiling. Sutcliffe was smitten and began dating Kirchherr shortly afterwards.


title: Stuart Sutcliffe

text: He wrote to friends that he was infatuated with her, and asked her German friends which colours, films, books and painters she liked. Best commented that the beginning of their relationship was "like one of those fairy stories". Kirchherr and Sutcliffe got engaged in November 1960, and exchanged rings, as is the German custom. Sutcliffe later wrote to his parents that he was engaged to Kirchherr, which they were shocked to learn, as they thought he would give up his career as an artist, although he told Kirchherr that he would like to be an art teacher in London or Germany in the future. After moving into the Kirchherr family's house, Sutcliffe used to borrow her clothes. He wore her leather trousers and jackets, collarless jackets, oversized shirts and long scarves, and also borrowed a corduroy suit with no lapels that he wore on stage, which prompted Lennon to sarcastically ask if his mother had lent him the suit.


title: Stuart Sutcliffe

text: Sutcliffe displayed artistic talent at an early age. Helen Anderson, a fellow student, remembered his early works as being very aggressive, with dark, moody colours, which was not the type of painting she expected from such a "quiet student". One of Sutcliffe's paintings was shown at the Walker Art Gallery in Liverpool as part of the John Moores exhibition, from November 1959 until January 1960. After the exhibition, Moores bought Sutcliffe's canvas for £65 (), which was then equal to 6–7 weeks' wages for an average working man. The picture Moores bought was called "Summer Painting", and Sutcliffe attended a formal dinner to celebrate the exhibition with another art student, Susan Williams. Murray remembered that the painting was painted on a board, not a canvas, and had to be cut into two pieces (because of its size) and hinged. Murray added that only one of the pieces actually got to the exhibition (because they stopped off in a pub to celebrate), but sold nonetheless because Moores bought it for his son.


title: Stuart Sutcliffe

text: Sutcliffe had been turned down when he applied to study for an Art Teachers Diploma (ATD) course at the Liverpool Art College, but after meeting Kirchherr, he decided to leave the Beatles and attend the Hamburg College of Art in June 1961, under the tutelage of Paolozzi, who later wrote a report stating that Sutcliffe was one of his best students. He wrote: "Sutcliffe is very gifted and very intelligent. In the meantime he has become one of my best students."


title: Stuart Sutcliffe

text: Sutcliffe's few surviving works reveal influence from the British and European abstract artists contemporary with the Abstract Expressionist movement in the United States. His earlier figurative work is reminiscent of the kitchen sink school, particularly of John Bratby, though Sutcliffe was producing abstract work by the end of the 1950s, including "The Summer Painting", purchased by Moores. Sutcliffe's works bear some comparison with those of John Hoyland and Nicolas de Staël, though they are more lyrical (Sutcliffe used the stage name "Stu de Staël" when he was playing with the Beatles on a Scottish tour in spring 1960). His later works are typically untitled, constructed from heavily impastoed slabs of pigment in the manner of de Staël, whom he learned about from Surrey born, art college instructor, Nicky Horsfield, and overlaid with scratched or squeezed linear elements creating enclosed spaces. "Hamburg Painting no. 2" was purchased by Liverpool's Walker Art Gallery and is one of a series entitled "Hamburg" in which the surface and colour changes produced atmospheric energy. European artists (including Paolozzi) were also influencing Sutcliffe at the time. The Walker Art Gallery has other works by Sutcliffe, which are "Self-portrait" (in charcoal) and "The Crucifixion". Lennon later hung a pair of Sutcliffe's paintings in his house (Kenwood) in Weybridge, and McCartney had a Paolozzi sculpture in his Cavendish Avenue home.


title: Stuart Sutcliffe

text: While studying in Germany, Sutcliffe began experiencing severe headaches and acute sensitivity to light. According to Kirchherr, some of the headaches left him temporarily blind. In February 1962, Sutcliffe collapsed during an art class in Hamburg. Kirchherr's mother had German doctors examine him, but they were unable to determine the exact cause of his headaches. They suggested he return to the United Kingdom and have himself admitted to a hospital with better facilities; however, after arriving there, Sutcliffe was told nothing was wrong, so he returned to Hamburg. He continued living with the Kirchherrs, but his condition soon worsened. After he collapsed again on 10 April 1962, Kirchherr took him to hospital, riding with him in the ambulance, but he died before they arrived. The cause of death was brain haemorrhage, specifically a ruptured aneurysm resulting in cerebral paralysis due to severe bleeding into the right ventricle of the brain. He was 21 years old.


title: Stuart Sutcliffe

text: On 13 April 1962, Kirchherr met the group at Hamburg Airport, telling them that Sutcliffe had died a few days earlier. Sutcliffe's mother flew to Hamburg with Beatles manager Brian Epstein and returned to Liverpool with her son's body. Sutcliffe's father did not hear of Stuart's death for three weeks, as he was sailing to South America on a cruise ship, although the family arranged for a padre, a military chaplain, to give him the news as soon as the ship docked in Buenos Aires. After Sutcliffe's death, Kirchherr wrote a letter to his mother, apologizing for being too ill to attend his funeral in Liverpool and saying how much she and Lennon missed him:


title: Stuart Sutcliffe

text: Oh, Mum, he (Lennon) is in a terrible mood now, he just can't believe that darling Stuart never comes back. [He's] just crying his eyes out ... John is marvellous to me, he says that he knows Stuart so much and he loves him so much that he can understand me.


title: Stuart Sutcliffe

text: The cause of Sutcliffe's aneurysm is unknown, although authors of books on the Beatles have speculated that it was caused by an earlier head injury. He may have been either kicked in the head, or thrown, head first, against a brick wall during an attack outside Lathom Hall, after a performance in January 1961. According to booking agent Allan Williams, Lennon and Best went to Sutcliffe's aid, fighting off his attackers before dragging him to safety. Sutcliffe sustained a fractured skull in the fight and Lennon's little finger was broken. Sutcliffe refused medical attention at the time and failed to keep an X-ray appointment at Sefton General Hospital.


title: Stuart Sutcliffe

text: Although Lennon did not attend or send flowers to Sutcliffe's funeral, his second wife, Yoko Ono, remembered that Lennon mentioned Sutcliffe's name very often, saying that he was "[My] alter ego ... a spirit in his world ... a guiding force".


title: Stuart Sutcliffe

text: The Beatles' compilation album "Anthology 1", released in 1995, featured previously unreleased recordings from the group's early years. Sutcliffe plays bass with the Beatles on three songs they recorded in 1960: "Hallelujah, I Love Her So", "You'll Be Mine", and "Cayenne". In addition, he is pictured on the front covers of all three "Anthology" albums.


title: Stuart Sutcliffe

text: In 2011, Sutcliffe's estate released a recording claimed to be Sutcliffe singing a cover of Elvis Presley's "Love Me Tender", recorded in 1961 and donated to the estate in 2009. The cover art shows a Sutcliffe painting entitled "Homage to Elvis". The recording was quickly proven to be fake by amateurs and industry professionals alike; it was clearly an amateur 'pitch shift' edit of the 1967 recording of "Love Me Tender" by The Boston Show Band (later known as the Glittermen).


title: Stuart Sutcliffe

text: Part One of "The Beatles Anthology" video documentary covers Sutcliffe's time with the group. There is no mention of his death in the documentary, but it is discussed in the accompanying book.


title: Stuart Sutcliffe

text: Sutcliffe was portrayed by David Nicholas Wilkinson in the film "Birth of the Beatles" (1979) and by Lee Williams in "" (2000). Sutcliffe's role in the Beatles' early career, as well as the factors that led him to leave the group, is dramatised in the 1994 film "Backbeat", in which he was portrayed by American actor Stephen Dorff. Sutcliffe does not appear in the 2009 film "Nowhere Boy", but is briefly mentioned toward the end of the film.


title: Stuart Sutcliffe

text: The Stuart Sutcliffe Estate sells memorabilia and artifacts of Sutcliffe's, which include poems written by him and the chords and lyrics to songs Lennon and Sutcliffe were learning.


title: Mateusz Gamrot

text: Mateusz Gamrot (born December 11, 1990) is a Polish professional mixed martial artist. He currently competes in the Lightweight division in the Ultimate Fighting Championship (UFC). Gamrot is a former KSW Featherweight Champion and KSW Lightweight Champion. As of December 13, 2022, he is #7 in the UFC lightweight rankings.


title: Mateusz Gamrot

text: Gamrot started wrestling at the age of ten. In middle school age, he moved to a boarding school in Milicz to train there in freestyle wrestling. While studying in a technical school, he belonged to the national wrestling team where he won medals in the Polish junior and youth championships. As a 20-year-old he moved permanently to Poznań. There he trains and has a family and two children.


title: Mateusz Gamrot

text: In 2002, he began his journey with martial arts, starting with wrestling. During his wrestling career he achieved many successes in Poland and internationally. He fought over 300 duels on the mat, wrestling, among others, at the European and World Championships. Since 2011, he has been training mixed martial arts. He gained his training experience under the supervision of an excellent trainer, Andrzej Kościelski, World Champion in wrestling.


title: Mateusz Gamrot

text: In 2012, he won a gold medal at the European Amateur MMA Championships (Brussels) and a year later he defended the championship title again winning gold in the 70 kg category (Budapest).


title: Mateusz Gamrot

text: Two times in a row (2013, 2014) he won the gold medal at the Polish championships in grappling in the purple stripes category (Luboń). In 2014 he won the ADCC Submission Wrestling European championships in up to 77 kg class.


title: Mateusz Gamrot

text: He made his professional MMA debut on February 4, 2012 at XFS Night of Champions, defeating Chechen Arbi Shamayev. By the end of the year he had won two more fights for the federation and then he signed with KSW. On June 8, 2013 he had his first fight in KSW, beating Mateusz Zawadzki via TKO at . On September 28 at he defeated former UFC fighter Andre Winner on points. At , Mateusz defeated Jefferson George on points.


title: Mateusz Gamrot

text: On September 13, 2014 he fought for the British organization Cage Warriors, defeating Welshman Tim Newman in the 1st round at CW 72. He returned on December 6, 2014 to defeat Łukasz Chlewicki at via unanimous decision. At on February 21, 2015, he won over Brazilian Rodrigo Cavalheiro Correia by technical knockout six seconds before the final bell. Gamrot earned a Knockout of the Night bonus award with the performance.


title: Mateusz Gamrot

text: At , Mateusz defeated Marif Piraev via TKO in the second round, getting his tenth straight win to start his career.


title: Mateusz Gamrot

text: On May 27, 2016 at , he fought for the vacant KSW Lightweight Championship belt against former British BAMMA and Russian M-1 Global champion Frenchman Mansour Barnaoui. He claimed the title via unanimous decision and both fighters were awarded the Fight of the Night bonus.


title: Mateusz Gamrot

text: At on October 1, 2016, he defended his title via heel hook against Renato Gomes Gabriel in the second round.


title: Mateusz Gamrot

text: Gamrot faced former UFC fighter Norman Parke at on May 27, 2017. He won the bout and retained the title via unanimous decision.


title: Mateusz Gamrot

text: Gamrot rematched Norman Parke at on October 22, 2017. At the weigh-ins, Parke came in one pound over the championship limit and the bout was deemed a non-title bout. After the bout was stopped due to eye pokes that left Parke unable to continue, Parke shoved Gamrot's cornerman, Borys Mankowski, which resulted in Marcin Bilman, another professional fighter who was in the champion's corner, responded by landing a punch on Parke. Gamrot was subsequently fined 30% of his purse and Bilman was handed a two-year ban from KSW events.


title: Mateusz Gamrot

text: On March 3, 2018 at , Gamrot defeated Grzegorz Szulakowski via keylock submission in the fourth round, defending the KSW Lightweight Championship.


title: Mateusz Gamrot

text: On December 1, 2018 at , he fought for a second belt, this time for the KSW Featherweight Championship, against submission specialist Kleber Koike Erbst, where he won the bout after a five-round domination, capturing the organization's second crown.


title: Mateusz Gamrot

text: On May 17, 2019, in a video on Borys Mankowski's YouTube channel, Gamrot announced that he had vacated his two belts and did not renew his contract with KSW.


title: Mateusz Gamrot

text: On March 6, 2020, KSW announced Gamrot's return to the organization. The KSW double champion was scheduled to return at in Lodz, Poland against the Brazilian Edimilson Souza, but due to a coronavirus pandemic the event was canceled. On July 11 he fought his third bout at against Norman Parke. Parke missed weight for the bout and was fined, which went to Gamrot. Gamrot won the fight in the third round via technical knockout.


title: Mateusz Gamrot

text: On August 29, 2020, he fought his last fight under his KSW contract against Marian Ziółkowski at , who replaced the injured Shamil Musayev. After a 5-round bout, Gamrot won via unanimous decision.


title: Mateusz Gamrot

text: Gamrot, as a replacement for Renato Moicano, was scheduled to face Magomed Mustafaev at on October 18, 2020. In turn, Mustafaev pulled out in early October due to undisclosed reasons. Gamrot faced fellow promotional newcomer Guram Kutateladze instead. He lost the close fight via split decision. Both fighters earned the "Fight of the Night" award.


title: Mateusz Gamrot

text: Gamrot faced Scott Holtzman on April 10, 2021 at . He won the fight via knockout in the second round. This win earned him the "Performance of the Night" award.


title: Mateusz Gamrot

text: Gamrot faced Jeremy Stephens on July 17, 2021 at . He won the fight via kimura in round one, this submission is the quickest of its kind in UFC history. This win earned him the" Performance of the Night" award.


title: Mateusz Gamrot

text: As the first bout of his new four-fight contract, Gamrot faced Carlos Diego Ferreira on December 18, 2021 at UFC Fight Night: Lewis vs. Daukaus. He won the bout via TKO in round two, forcing Ferreira to submit with a knee to the body.


title: Mateusz Gamrot

text: Gamrot faced Arman Tsarukyan on June 25, 2022 at UFC on ESPN 38. He won the closely contested fight via unanimous decision. Both fighters earned the "Fight of the Night" award.


title: Mateusz Gamrot

text: As the first fight of his four-fight contract, Gamrot faced Beneil Dariush on October 22, 2022 at UFC 280. He lost the fight by unanimous decision.


title: Chieftain (tank)

text: A development of the Centurion, the Chieftain introduced the supine (reclining) driver position to British design allowing a heavily sloped hull with reduced height. A new powerpack and improved transmission gave it higher speed than the Centurion despite being heavier due to major upgrades to armour protection and the armament; this allowed it to replace both the Conqueror and Centurion while performing their roles effectively. It remained in service until replaced by the Challenger 1 which shared many of the Chieftain's features.


title: Chieftain (tank)

text: The Chieftain was an evolutionary development of the successful cruiser line of tanks that had emerged at the end of the Second World War. Its predecessor, the Centurion main battle tank (MBT), is widely considered to be one of the most successful of post-war MBT designs. However, the introduction of the Soviet IS-3 /IS-4 heavy tank along with Soviet T-54/T-55 forced the introduction of the Conqueror heavy tank armed with a gun. A single design combining the firepower of the Conqueror's 120 mm gun with the mobility and general usefulness of the Centurion was seen as the ideal combination.


title: Chieftain (tank)

text: Leyland, who had been involved in the Centurion tank, had built their own prototypes of a new tank design in 1956. Several aspects of the design were trialled by the production of the FV4202 "40-ton Centurion" with a reclined driver position and mantletless gun mounting. In effect, the FV4202 was a shorter Centurion chassis with a prototype of what would become the Chieftain turret, but armed with the 20pdr gun.


title: Chieftain (tank)

text: This work led to a War Office specification for a new tank. The General Staff specification drew on the experience of Centurion tanks in the Korean War as well as that of the Conqueror tank. The tank was expected to be able to engage the enemy at long range, from defensive positions, and be proof against medium artillery. To this end, the gun was to have a greater angle of depression than the 8 degrees of Conqueror and would be equipped with better frontal armour. The tank was expected to achieve a firing rate of 10 rounds per minute in the first minute and six per minute for the following four.


title: Chieftain (tank)

text: The first few prototypes were provided for troop trials from 1959 which identified a number of changes. Improvements to address engine vibration and cooling resulted in a redesign of the rear hull. This increased the design weight to nearly 50 tons and accordingly the suspension (which had been designed for 45 tons) was strengthened. Trackpads had to be fitted to protect roads from damage and the ground clearance increased. The design was accepted in the early 1960s.


title: Chieftain (tank)

text: Britain and Israel had collaborated on the development in its latter stages with a view to Israel purchasing and domestically producing the vehicle. Two prototypes were delivered as part of a four-year trial. However, it was eventually decided not to sell the marque to the Israelis (since, at that period of time in the late 1960s, the UK was more friendly towards the Arab states and Jordan than to Israel), which prompted them to follow their own development programme.


title: Chieftain (tank)

text: In 1957, NATO had specified that its forces should use multi-fuel engines. The early Leyland engine delivered around to the sprocket, which meant a top road speed of around and cross-country performance was limited. This was further hampered by the Horstmann coil spring suspension, which made it a challenge to drive cross country and provide the crew with a comfortable ride. Due to the cylinder linings being pressure fitted, coolant leaks within the cylinder block were common, resulting in white smoke billowing from the exhaust.


title: Chieftain (tank)

text: In the late 1970s, engine design changed with the introduction of Belzona which was used to improve the lining seals. Engine output also increased, with later engines delivering some to the sprocket. This meant better performance and an increased speed. However, cross-country performance remained limited.


title: Chieftain (tank)

text: The design of the Chieftain included a heavily sloped hull and turret which greatly increased the effective thickness of the frontal armour – on the glacis (from an actual thickness of ) and on the turret (from ). It had a mantletless turret in order to take full advantage of reclining the vehicle up to ten degrees in a hull-down position.


title: Chieftain (tank)

text: For security reasons early prototypes had a canvas screen covering the mantlet and a sheet metal box mounted over the sloping glacis plate to disguise the configuration of the vehicle.


title: Chieftain (tank)

text: The driver lay semi-recumbent in the hull when his hatch was closed down which helped to reduce the profile of the forward glacis plate. The commander, gunner and loader were situated in the turret. To the left side of the turret was a large searchlight with infrared capability in an armoured housing.


title: Chieftain (tank)

text: The Leyland L60 engine is a two-stroke opposed piston design intended for multi-fuel use so that it could run on whatever fuel was available. In practice the engine did not deliver the expected power and was unreliable, estimated to have a 90% breakdown rate but improvements were introduced to address this. Primary problems included cylinder liner failure, fan drive problems and perpetual leaks due to vibration and badly routed pipework. However, as the engine power improved the tank itself became heavier.


title: Chieftain (tank)

text: The tank was steered by conventional tillers hydraulically actuating onto external brake discs. The discs worked via the epicyclic gearbox providing "regenerative" steering. The Merritt-Brown TN12 triple-differential gearbox was operated motorcycle-style with a kick up/kick down "peg" on the left, which actuated electro-hydraulic units in the gearbox, the accelerator cable was operated by the right foot. In the turret, the loader was on the left and the gunner on the right of the gun with the commander situated behind the gunner. The suspension was of the Horstmann bogie type with large side steel plates to protect the tracks and provide stand-off protection from hollow charge attack.


title: Chieftain (tank)

text: The main armament was the 120 mm L11A5 rifled gun. This differed from most contemporary main tank armament as it used projectiles and charges that were loaded separately, as opposed to a single fixed round. The charges were encased in combustible bags. Other tank guns such as the 120mm L1 gun on the Conqueror, needed to store the spent shell cartridges or eject them outside. The combustible charges were stored in 36 recesses surrounded by a pressurised water/glycol mixture – so-called "wet-stowage". In the event of a hit penetrating the fighting compartment, the jacket would rupture soaking the charges and preventing a catastrophic propellant explosion. As there was no shell case, the firing of the charge was by vent tubes automatically loaded from a ten-round magazine on the breech. Due to the length of the gun, which required balancing, and the need for storage space, the turret has a large overhang to the rear. This contains radios, ammunition and fire control equipment and has further stowage externally.


title: Chieftain (tank)

text: The gun could fire a wide range of ammunition but the most commonly loaded types were high explosive squash head (HESH), armour-piercing discarding sabot (APDS), or practice round equivalents for both types. The Chieftain could store up to 64 projectiles (although the propellant stowage allowed a maximum of 36 charges for APDS rounds). The gun was fully stabilised with a fully computerized integrated control system. The secondary armament consisted of a coaxial L8A1 7.62 mm machine gun and another 7.62 mm machine gun mounted on the commander's cupola. An advantage of using two-part ammunition was that in the case of inert rounds like APDS the loader could reach for the next round and hold it in his lap, ready to load while the gunner was acquiring the target and firing. This practice increases the rate of fire but would be hazardous with one-piece ammunition.


title: Chieftain (tank)

text: Chieftain had an NBC protection system which Centurion lacked. An infantry telephone was fitted to the rear of the tank to facilitate communication with infantry.


title: Chieftain (tank)

text: The initial Fire-control system (FCS) was the Marconi FV/GCE Mk 4. A .50-inch (12.7 mm) ranging gun was mounted above the main gun (with 300 rounds available). This fired ranging shots out to a maximum of , at which point the tracer in the ranging rounds burned out although the high explosive tip still created a visible "splash" on impact. The tank commander had a rotating cupola with nine vision blocks -giving all round view, plus the 7.62 mm machine-gun and an infrared (IR) capable projector coaxial with the weapon. The aiming systems were provided for both the gunner and the tank commander; they had 1x or 10x selectable magnification power, increasing to x15 in the Mk5 and beyond, and they were replaceable with IR vision systems for night operations (3x magnification power). The commander could rotate his cupola to bring his sight onto a target and then engage the mechanism that brought the turret round on to the correct bearing so that the gunner could complete the aiming.


title: Chieftain (tank)

text: The left side of the turret had a large searchlight with an electrically controlled infrared filter inside an armoured box, with a relatively long range – up to .


title: Chieftain (tank)

text: From the beginning of the 1970s, the Mk 3/3 version replaced the ranging gun with a Barr and Stroud LF-2 laser rangefinder with a range. This allowed engagements at much longer ranges, and also could be linked to the fire control system, allowing more rapid engagements and changes of target.


title: Chieftain (tank)

text: On later models, fire control was provided by the Marconi IFCS (Improved Fire Control System), using a digital ballistic computer. The upgrade was not finished until the end of 1980, when some examples (but not the majority) had the IR searchlight replaced with TOGS. Many later examples had Stillbrew armour, intended to defeat Soviet 125 mm tank guns and heavy anti-tank missiles. These became the Mark 11 version.


title: Chieftain (tank)

text: Chieftain equipped British units of the British Army of the Rhine (BAOR) during the Cold War, defended West Germany against possible Warsaw Pact attack.


title: Chieftain (tank)

text: Like its European competitors, the Chieftain found a large export market in the Middle East, but unlike the Centurion, it was not adopted by any other NATO or Commonwealth country.


title: Chieftain (tank)

text: The Chieftain proved itself capable in combat and able to be upgraded, both for overall improvement and to meet local requirements. It was continuously upgraded until the early 1990s, when it was replaced by Challenger 1. The final Chieftain version, which was used by the British Army until 1995, incorporated "Stillbrew" armour named after Colonel Still and John Brewer from the Military Vehicles and Engineering Establishment (MVEE), the Improved Fire Control System (IFCS) and the Thermal Observation Gunnery Sight (TOGS). The last British Regiment equipped with Chieftains was the 1st Royal Tank Regiment, which was based at Aliwal Barracks, Tidworth.


title: Chieftain (tank)

text: The first model was introduced in 1967. Chieftains were supplied to at least six countries, including Iran, Kuwait, Oman and Jordan. An agreement for sales to Israel and local production was cancelled by the British Government in 1969, despite considerable Israeli technical and tactical input into the development of the tank, especially the capacity to operate successfully in desert environments, and the provision for the tank to make good use of hull-down positioning. Two examples were delivered to, and extensively trialled by, the Israeli Armoured Corps. This experience spurred the creation of the indigenous Israeli Merkava, the development programme was led by General Israel Tal, who had worked closely with the British in the Anglo-Israeli Chieftain project. The largest foreign sale was to Iran, who, at the recommendation of General Tal, took delivery of 707 Mk-3P and Mk-5P (the letter P standing for Persia), as well as 187 FV4030-1, 41 ARV and 14 AVLB before the 1979 revolution. Further planned deliveries of the more capable FV4030-2 (Shir 1) and FV4030-3 (Shir 2) series were cancelled at that point.


title: Chieftain (tank)

text: It was in the Middle East that the Chieftain was to see all of its operational experience. It was first used extensively by Iran, during the Iran–Iraq War of 1980–88, including the largest tank battle of the war, with mixed results as the Chieftain Mk 3/5 suffered from chronic engine problems and low power-to-weight ratio, making it unreliable and slow when manoeuvering over harsh terrain, which in turn made it prone to breakdowns in the midst of battle or a sluggish target and thus vulnerable to enemy tank fire. After the tank battle at Susangerd, captured Chieftains of the Iranian 92nd Armoured Division were taken back to Baghdad for trials. According to Aladdin Makki, the Iraqi Army Corps chief of staff, in a post-war interview, Iraqi sabot rounds "Went through the front Armour of the Chieftain and came out the backside". This as well as the Chieftain's poor off-road capability influenced the Iraqis to reject British arms sale propositions, who were at the time courting Iraq for arms sales that included Chieftain MBT's. According to Makki, when the British telephoned the Iraqi director of Armor, Salah Askar, he responded with "We don't want your stupid tanks!". Ra'ad Al-Hamdani, an Iraqi general in the Iraqi Republican Guard, also expressed negative opinion on the Chieftain's performance in combat, stating "The 16th Iranian Armored Division, which was equipped with Chieftain tanks, lost a battle against the 10th Iraqi Armored Brigade with T-72 tanks. It is hard for an armored brigade to destroy a division in 12 hours but it happened; it was a disaster for the Iranians". Out of the 894 Chieftain tanks that had started the war only 200 were left by the war's end.


title: Chieftain (tank)

text: Kuwait had 143 Chieftains on the eve of the 1990 Iraqi Invasion of Kuwait. Thirty-seven Chieftains of the Kuwaiti 35th Armored Brigade fought at the Battle of the Bridges against elements of the Iraqi Hammurabi and Medina divisions before withdrawing over the Saudi border. None of the brigade's tanks were lost in the battle, and the 35th Armored Brigade (known as Al-Fatah) became part of "Joint Command Forces East" during the 1991 Gulf War and was able to return into Kuwait undefeated.


title: Chieftain (tank)

text: Besides those of the 35th Armored Brigade, the rest of the Kuwaiti Armed Forces' Chieftains (136 tanks) were either destroyed or captured by the invading forces after they had been abandoned by their Kuwaiti crews when their ammunition ran out. After the liberation of Kuwait, the ageing Chieftains were replaced by the Yugoslav M-84.


title: Chieftain (tank)

text: Mark 1 and Mark 2 models had a coaxial Browning .50-inch (12.7 mm) ranging machine guns prior to the introduction of the laser rangefinder.


title: Chieftain (tank)

text: In 1975 all British Army earlier Marks of tanks except Mark 1's were upgraded to Chieftain Mk.5 standard as part of the 1975 "Totem Pole" programme. "Exercise Totem Pole" was carried out in six-to-nine phases depending on the Mark of vehicle being modified (Chieftain Mk.5's already had some of the required changes incorporated at the factory) between 1975 and 1979 and included fitment of the Marconi Improved Fire Control System (IFCS), replacement of the searchlight with the Barr & Stroud Thermal Observation Gunnery System (TOGS), along with modifications for using FSAPDS ammunition. Upon completion of each phase the vehicle received an additional suffix to the designation, e.g., "Chieftain Mk.3/S(Y)2" denoting a Mark 3/S having completed the first three phases of "Totem Pole".}} including addition of Clansman radios, fitting of TLS, fitment of Muzzle Reference System (MRS) upon replacement of L11A3 barrel with L11A5 barrel, and fitment of 750 hp L60 Mark 8A. These vehicles were re-designated Chieftain Mk's.6 to Mk.8.


title: Chieftain (tank)

text: In 1977 the engines of all British Army vehicles were upgraded to the 750 hp L60 Mark 9A, followed by further upgrading with the L60 Mark 11A or L60 Mark 12A in 1978 as part of the 1977 "Dark Morn" and the 1978 "Sundance" programmes. "Exercise Sundance" concerned improvements in engine power, reliability, and other power train improvements, and was carried out in five main phases between 1976 and 1979. These, in themselves, had been preceded by "Dark Morn", "High Noon", and the initial "Fleetfoot" engine development programme which had completed in October 1971. Vehicles on which "Sundance" modifications had been carried out received an additional 'Z' suffix appended to their designations, the "Sundance" engines themselves were signified with a distinctive orange/yellow-coloured upper crankcase.


title: Rolls-Royce Merlin

text: The Rolls-Royce Merlin is a British liquid-cooled V-12 piston aero engine of 27-litres (1,650 cu in) capacity. Rolls-Royce designed the engine and first ran it in 1933 as a private venture. Initially known as the PV-12, it was later called "Merlin" following the company convention of naming its four-stroke piston aero engines after birds of prey.


title: Rolls-Royce Merlin

text: After several modifications, the first production variants of the PV-12 were completed in 1936. The first operational aircraft to enter service using the Merlin were the Fairey Battle, Hawker Hurricane and Supermarine Spitfire. The Merlin remains most closely associated with the Spitfire and Hurricane, although the majority of the production run was for the four-engined Avro Lancaster heavy bomber. A series of rapidly-applied developments, brought about by wartime needs, markedly improved the engine's performance and durability. Starting at 1,000 hp for the first production models, most late war versions produced just under 1,800 hp, and the very latest version as used in the de Havilland Hornet over 2,000 hp.


title: Rolls-Royce Merlin

text: One of the most successful aircraft engines of the World War II era, some 50 versions of the Merlin were built by Rolls-Royce in Derby, Crewe and Glasgow, as well as by Ford of Britain at their Trafford Park factory, near Manchester. A de-rated version was also the basis of the Rolls-Royce/Rover Meteor tank engine. Post-war, the Merlin was largely superseded by the Rolls-Royce Griffon for military use, with most Merlin variants being designed and built for airliners and military transport aircraft.


title: Rolls-Royce Merlin

text: The Packard V-1650 was a version of the Merlin built in the United States. Production ceased in 1950 after a total of almost 150,000 engines had been delivered. Merlin engines remain in Royal Air Force service today with the Battle of Britain Memorial Flight, and power many restored aircraft in private ownership worldwide.


title: Rolls-Royce Merlin

text: In the early 1930s, Rolls-Royce started planning its future aero-engine development programme and realised there was a need for an engine larger than their 21-litre (1,296 cu in) Kestrel which was being used with great success in a number of 1930s aircraft. Consequently, work was started on a new -class design known as the PV-12, with PV standing for "Private Venture, 12-cylinder", as the company received no government funding for work on the project. The PV-12 was first run on 15 October 1933 and first flew in a Hawker Hart biplane (serial number "K3036") on 21 February 1935. The engine was originally designed to use the evaporative cooling system then in vogue. This proved unreliable and when ethylene glycol from the U.S. became available, the engine was adapted to use a conventional liquid-cooling system. The Hart was subsequently delivered to Rolls-Royce where, as a Merlin testbed, it completed over 100 hours of flying with the Merlin C and E engines.


title: Rolls-Royce Merlin

text: In 1935, the Air Ministry issued a specification, F10/35, for new fighter aircraft with a minimum airspeed of . Fortunately, two designs had been developed: the Supermarine Spitfire and the Hawker Hurricane; the latter designed in response to another specification, F36/34. Both were designed around the PV-12 instead of the Kestrel, and were the only contemporary British fighters to have been so developed. Production contracts for both aircraft were placed in 1936, and development of the PV-12 was given top priority as well as government funding. Following the company convention of naming its piston aero engines after birds of prey, Rolls-Royce named the engine the "Merlin" after a small, Northern Hemisphere falcon ("Falco columbarius").


title: Rolls-Royce Merlin

text: Two more Rolls-Royce engines developed just prior to the war were added to the company's range. The Rolls-Royce Peregrine was an updated, supercharged development of their V-12 Kestrel design, while the 42-litre (2,560 cu in) Rolls-Royce Vulture used four Kestrel-sized cylinder blocks fitted to a single crankcase and driving a common crankshaft, forming an X-24 layout. This was to be used in larger aircraft such as the Avro Manchester.


title: Rolls-Royce Merlin

text: Although the Peregrine appeared to be a satisfactory design, it was never allowed to mature since Rolls-Royce's priority was refining the Merlin. As a result, the Peregrine saw use in only two aircraft: the Westland Whirlwind fighter and one of the Gloster F.9/37 prototypes. The Vulture was fitted to the Avro Manchester bomber, but proved unreliable in service and the planned fighter using it – the Hawker Tornado – was cancelled as a result. With the Merlin itself soon pushing into the range, the Peregrine and Vulture were both cancelled in 1943, and by mid-1943 the Merlin was supplemented in service by the larger Griffon. The Griffon incorporated several design improvements and ultimately superseded the Merlin.


title: Rolls-Royce Merlin

text: Initially the new engine was plagued with problems such as failure of the accessory gear trains and coolant jackets. Several different construction methods were tried before the basic design of the Merlin was set. Early production Merlins were unreliable: Common problems were cylinder head cracking, coolant leaks, and excessive wear to the camshafts and crankshaft main bearings.


title: Rolls-Royce Merlin

text: The Merlin II and III series were the first main production versions of the engine. The Merlin III was the first version to incorporate a "universal" propeller shaft, allowing either de Havilland or Rotol manufactured propellers to be used.


title: Rolls-Royce Merlin

text: The first major version to incorporate changes brought about through experience in operational service was the XX, which was designed to run on 100-octane fuel. This fuel allowed higher manifold pressures, which were achieved by increasing the boost from the centrifugal supercharger. The Merlin XX also utilised the two-speed superchargers designed by Rolls-Royce, resulting in increased power at higher altitudes than previous versions. Another improvement, introduced with the Merlin X, was the use of a 70%–30% water-glycol coolant mix rather than the 100% glycol of the earlier versions. This substantially improved engine life and reliability, removed the fire hazard of the flammable ethylene glycol, and reduced the oil leaks that had been a problem with the early Merlin I, II and III series.


title: Rolls-Royce Merlin

text: The process of improvement continued, with later versions running on higher octane ratings, delivering more power. Fundamental design changes were also made to all key components, again increasing the engine's life and reliability. By the end of the war the "little" engine was delivering over 1,600 horsepower (1,200 kW) in common versions, and as much as 2,030 horsepower (1,540 kW) in the Merlin 130/131 versions specifically designed for the de Havilland Hornet. Ultimately, during tests conducted by Rolls-Royce at Derby, an RM.17.SM (the high altitude version of the Merlin 100-Series) achieved 2,640 horsepower (1,969 kW) at 36 lb boost (103"Hg) on 150-octane fuel with water injection.


title: Rolls-Royce Merlin

text: With the end of the war, work on improving Merlin power output was halted and the development effort was concentrated on civil derivatives of the Merlin. Development of what became the "Transport Merlin" (TML) commenced with the Merlin 102 (the first Merlin to complete the new civil type-test requirements) and was aimed at improving reliability and service overhaul periods for airline operators using airliner and transport aircraft such as the Avro Lancastrian, Avro York (Merlin 500-series), Avro Tudor II & IV (Merlin 621), Tudor IVB & V (Merlin 623), TCA Canadair North Star (Merlin 724) and BOAC Argonaut (Merlin 724-IC). By 1951 the time between overhauls (TBO) was typically 650–800 hours depending on use. By then single-stage engines had accumulated 2,615,000 engine hours in civil operation, and two-stage engines 1,169,000.


title: Rolls-Royce Merlin

text: In addition, an exhaust system to reduce noise levels to below those from ejector exhausts was devised for the North Star/Argonaut. This "cross-over" system took the exhaust flow from the inboard bank of cylinders up-and-over the engine before discharging the exhaust stream on the outboard side of the UPP nacelle. As a result, sound levels were reduced by between 5 and 8 decibels. The modified exhaust also conferred an increase in horsepower over the unmodified system of , resulting in a 5 knot improvement in true air speed. Still-air range of the aircraft was also improved by around 4 per cent. The modified engine was designated the "TMO" and the modified exhaust system was supplied as kit that could be installed on existing engines either by the operator or by Rolls-Royce.


title: Rolls-Royce Merlin

text: Power ratings for the civil Merlin 600, 620, and 621-series was continuous cruising at , and for take-off. Merlins 622–626 were rated at continuous cruising at , and for take-off. Engines were available with single-stage, two-speed supercharging (500-series), two-stage, two-speed supercharging (600-series), and with full intercooling, or with half intercooling/charge heating, charge heating being employed for cold area use such as in Canada. Civil Merlin engines in airline service flew 7,818,000 air miles in 1946, 17,455,000 in 1947, and 24,850,000 miles in 1948.


title: Rolls-Royce Merlin

text: Most of the Merlin's technical improvements resulted from more efficient superchargers, designed by Stanley Hooker, and the introduction of aviation fuel with increased octane ratings. Numerous detail changes were made internally and externally to the engine to withstand increased power ratings and to incorporate advances in engineering practices.


title: Rolls-Royce Merlin

text: The Merlin consumed an enormous volume of air at full power (equivalent to the volume of a single-decker bus per minute), and with the exhaust gases exiting at 1,300 mph (2,100 km/h) it was realised that useful thrust could be gained simply by angling the gases backwards instead of venting sideways.


title: Rolls-Royce Merlin

text: During tests, 70 pounds-force (310 N; 32 kgf) thrust at , or roughly 70 horsepower (52 kW) was obtained which increased the level maximum speed of the Spitfire by to . The first versions of the ejector exhausts featured round outlets, while subsequent versions of the system used "fishtail" style outlets which marginally increased thrust and reduced exhaust glare for night flying.


title: Rolls-Royce Merlin

text: In September 1937 the Spitfire prototype, "K5054," was fitted with ejector type exhausts. Later marks of the Spitfire used a variation of this exhaust system fitted with forward-facing intake ducts to distribute hot air out to the wing-mounted guns to prevent freezing and stoppages at high altitudes, replacing an earlier system that used heated air from the engine coolant radiator. The latter system had become ineffective due to improvements to the Merlin itself which allowed higher operating altitudes where air temperatures are lower. Ejector exhausts were also fitted to other Merlin-powered aircraft.


title: Rolls-Royce Merlin

text: Central to the success of the Merlin was the supercharger. A.C. Lovesey, an engineer who was a key figure in the design of the Merlin, delivered a lecture on the development of the Merlin in 1946; in this extract he explained the importance of the supercharger:


title: Rolls-Royce Merlin

text: The Merlin supercharger was originally designed to allow the engine to generate maximum power at an altitude of about . In 1938 Stanley Hooker, an Oxford graduate in applied mathematics, explained "... I soon became very familiar with the construction of the Merlin supercharger and carburettor ... Since the supercharger was at the rear of the engine it had come in for pretty severe design treatment, and the air intake duct to the impeller looked very squashed ..." Tests conducted by Hooker showed the original intake design was inefficient, limiting the performance of the supercharger. Hooker subsequently designed a new air intake duct with improved flow characteristics which increased maximum power at a higher altitude of over ; and also improved the design of both the impeller, and the diffuser which controlled the airflow to it. These modifications led to the development of the single-stage Merlin XX and 45 series.


title: Rolls-Royce Merlin

text: A significant advance in supercharger design was the incorporation in 1938 of a two-speed drive (designed by the French company Farman) to the impeller of the Merlin X. The later Merlin XX incorporated the two-speed drive as well as several improvements that enabled the production rate of Merlins to be increased. The low-ratio gear, which operated from takeoff to an altitude of , drove the impeller at 21,597 rpm and developed 1,240 horsepower (925 kW) at that height; while the high gear's (25,148 rpm) power rating was 1,175 horsepower (876 kW) at . These figures were achieved at 2,850 rpm engine speed using +9 pounds per square inch (1.66 atm) (48") boost.


title: Rolls-Royce Merlin

text: In 1940, after receiving a request in March of that year from the Ministry of Aircraft Production for a high-rated () Merlin for use as an alternative engine to the turbocharged Hercules VIII used in the prototype high-altitude Vickers Wellington V bomber, Rolls-Royce started experiments on the design of a two-stage supercharger and an engine fitted with this was bench-tested in April 1941, eventually becoming the Merlin 60. The basic design used a modified Vulture supercharger for the first stage while a Merlin 46 supercharger was used for the second. A liquid-cooled intercooler on top of the supercharger casing was used to prevent the compressed air/fuel mixture from becoming too hot. Also considered was an exhaust-driven turbocharger but, although a lower fuel consumption was an advantage the added weight and the need to add extra ducting for the exhaust flow and waste-gates, meant that this option was rejected in favour of the two-stage supercharger. Fitted with the two-stage two-speed supercharger, the Merlin 60 series gained 300 horsepower (224 kW) at over the Merlin 45 series, at which altitude a Spitfire IX was nearly faster than a Spitfire V.


title: Rolls-Royce Merlin

text: The two-stage Merlin family was extended in 1943 with the Merlin 66 which had its supercharger geared for increased power ratings at low altitudes, and the Merlin 70 series that were designed to deliver increased power at high altitudes.


title: Rolls-Royce Merlin

text: While the design of the two-stage supercharger forged ahead, Rolls-Royce also continued to develop the single-stage supercharger, resulting in 1942 in the development of a smaller "cropped" impeller for the Merlin 45M and 55M; both of these engines developed greater power at low altitudes. In squadron service the LF.V variant of the Spitfire fitted with these engines became known as the "clipped, clapped, and cropped Spitty" to indicate the shortened wingspan, the less-than-perfect condition of the used airframes, and the cropped supercharger impeller.


title: Rolls-Royce Merlin

text: The use of carburettors was calculated to give a higher specific power output, due to the lower temperature, hence greater density, of the fuel/air mixture compared to injected systems. However, the Merlin's float controlled carburettor meant that if Spitfires or Hurricanes were to pitch nose down into a steep dive, negative "g"-force ("g") produced temporary fuel starvation causing the engine to cut-out momentarily. By comparison, the contemporary Bf 109E, which had direct fuel injection, could "bunt" straight into a high-power dive to escape attack. RAF fighter pilots soon learned to avoid this with a "half-roll" of their aircraft before diving in pursuit. A restrictor in the fuel supply line together with a diaphragm fitted in the float chamber, jocularly nicknamed "Miss Shilling's orifice", after its inventor, went some way towards curing fuel starvation in a dive by containing fuel under negative G; however, at less than maximum power a fuel-rich mixture still resulted. Another improvement was made by moving the fuel outlet from the bottom of the S.U. carburettor to exactly halfway up the side, which allowed the fuel to flow equally well under negative or positive g.


title: Rolls-Royce Merlin

text: Further improvements were introduced throughout the Merlin range: 1943 saw the introduction of a Bendix-Stromberg pressure carburettor that injected fuel at 5 pounds per square inch (34 kPa; 0.34 bar) through a nozzle directly into the supercharger, and was fitted to Merlin 66, 70, 76, 77 and 85 variants. The final development, which was fitted to the 100-series Merlins, was an S.U. injection carburettor that injected fuel into the supercharger using a fuel pump driven as a function of crankshaft speed and engine pressures.


title: Rolls-Royce Merlin

text: At the start of the war, the Merlin I, II and III ran on the then standard 87-octane aviation spirit and could generate just over 1,000 horsepower (750 kW) from its 27-litre (1,650-cu in) displacement: the maximum boost pressure at which the engine could be run using 87-octane fuel was +6 pounds per square inch (141 kPa; 1.44 atm). However, as early as 1938, at the 16th Paris Air Show, Rolls-Royce displayed two versions of the Merlin rated to use 100-octane fuel. The Merlin R.M.2M was capable of 1,265 horsepower (943 kW) at 7,870 feet (2,400 m), 1,285 horsepower (958 kW) at 9,180 feet (2,800 m) and 1,320 horsepower (984 kW) on take-off; while a Merlin X with a two-speed supercharger in high gear generated 1,150 horsepower (857 kW) at 15,400 feet (4,700 m) and 1,160 horsepower (865 kW) at 16,730 feet (5,100 m).


title: Rolls-Royce Merlin

text: From late 1939, 100-octane fuel became available from the U.S., West Indies, Persia, and, in smaller quantities, domestically, consequently, "... in the first half of 1940 the RAF transferred all Hurricane and Spitfire squadrons to 100 octane fuel." Small modifications were made to Merlin II and III series engines, allowing an increased (emergency) boost pressure of +12 pounds per square inch (183 kPa; 1.85 atm). At this power setting these engines were able to produce 1,310 horsepower (977 kW) at while running at 3,000 revolutions per minute. Increased boost could be used indefinitely as there was no mechanical time limit mechanism, but pilots were advised not to use increased boost for more than a maximum of five minutes, and it was considered a "definite overload condition on the engine"; if the pilot resorted to emergency boost he had to report this on landing, when it was noted in the engine log book, while the engineering officer was required to examine the engine and reset the throttle gate. Later versions of the Merlin ran only on 100-octane fuel, and the five-minute combat limitation was raised to +18 pounds per square inch (224 kPa; 2.3 atm).


title: Rolls-Royce Merlin

text: In late 1943 trials were run of a new "100/150" grade (150-octane) fuel, recognised by its bright-green colour and "awful smell". Initial tests were conducted using of tetraethyllead (T.E.L.) for every one imperial gallon of 100-octane fuel (or 1.43 cc/L or 0.18 U.S. fl oz/U.S. gal), but this mixture resulted in a build-up of lead in the combustion chambers, causing excessive fouling of the spark plugs. Better results were achieved by adding 2.5% mono methyl aniline (M.M.A.) to 100-octane fuel. The new fuel allowed the five-minute boost rating of the Merlin 66 to be raised to +25 pounds per square inch (272 kPa; 2.7 atm). With this boost rating the Merlin 66 generated 2,000 hp (1,491 kW) at sea level and 1,860 hp (1,387 kW) at .


title: Rolls-Royce Merlin

text: Starting in March 1944, the Merlin 66-powered Spitfire IXs of two Air Defence of Great Britain (ADGB) squadrons were cleared to use the new fuel for operational trials, and it was put to good use in the summer of 1944 when it enabled Spitfire L.F. Mk. IXs to intercept V-1 flying bombs coming in at low altitudes. 100/150 grade fuel was also used by Mosquito night fighters of the ADGB to intercept V-1s. In early February 1945, Spitfires of the Second Tactical Air Force (2TAF) also began using 100/150 grade fuel. This fuel was also offered to the USAAF where it was designated "PPF 44-1" and informally known as "Pep".


title: Rolls-Royce Merlin

text: Production of the Rolls-Royce Merlin was driven by the forethought and determination of Ernest Hives, who at times was enraged by the apparent complacency and lack of urgency encountered in his frequent correspondence with the Air Ministry, the Ministry of Aircraft Production and local authority officials. Hives was an advocate of shadow factories, and, sensing the imminent outbreak of war, pressed ahead with plans to produce the Merlin in sufficient numbers for the rapidly expanding Royal Air Force. Despite the importance of uninterrupted production, several factories were affected by industrial action. By the end of its production run in 1950, 168,176 Merlin engines had been built; over 112,000 in Britain and more than 55,000 under licence in the U.S.


title: Rolls-Royce Merlin

text: The existing Rolls-Royce facilities at Osmaston, Derby were not suitable for mass engine production although the floor space had been increased by some 25% between 1935 and 1939; Hives planned to build the first two- or three hundred engines there until engineering teething troubles had been resolved. To fund this expansion, the Air Ministry had provided a total of £1,927,000 by December 1939. Having a workforce that consisted mainly of design engineers and highly skilled men, the Derby factory carried out the majority of development work on the Merlin, with flight testing carried out at nearby RAF Hucknall. All the Merlin-engined aircraft taking part in the Battle of Britain had their engines assembled in the Derby factory. Total Merlin production at Derby was 32,377. The original factory closed in March 2008, but the company maintains a presence in Derby.


title: Rolls-Royce Merlin

text: To meet the increasing demand for Merlin engines, Rolls-Royce started building work on a new factory at Crewe in May 1938, with engines leaving the factory in 1939. The Crewe factory had convenient road and rail links to their existing facilities at Derby. Production at Crewe was originally planned to use unskilled labour and sub-contractors with which Hives felt there would be no particular difficulty, but the number of required sub-contracted parts such as crankshafts, camshafts and cylinder liners eventually fell short and the factory was expanded to manufacture these parts "in house".


title: Rolls-Royce Merlin

text: Initially the local authority promised to build 1,000 new houses to accommodate the workforce by the end of 1938, but by February 1939 it had only awarded a contract for 100. Hives was incensed by this complacency and threatened to move the whole operation, but timely intervention by the Air Ministry improved the situation. In 1940 a strike took place when women replaced men on capstan lathes, the workers' union insisting this was a skilled labour job; however, the men returned to work after 10 days.


title: Rolls-Royce Merlin

text: The factory was used postwar for the production of Rolls-Royce and Bentley motor cars and military fighting vehicle power plants. In 1998 Volkswagen AG bought the Bentley marque and the factory. Today it is known as Bentley Crewe.


title: Rolls-Royce Merlin

text: Hives further recommended that a factory be built near Glasgow to take advantage of the abundant local work force and the supply of steel and forgings from Scottish manufacturers. In September 1939, the Air Ministry allocated £4,500,000 for a new Shadow factory. This government-funded and -operated factory was built at Hillington starting in June 1939 with workers moving into the premises in October, one month after the outbreak of war. The factory was fully occupied by September 1940. A housing crisis also occurred at Glasgow where Hives again asked the Air Ministry to step in.


title: Rolls-Royce Merlin

text: With 16,000 employees, the Glasgow factory was one of the largest industrial operations in Scotland. Unlike the Derby and Crewe plants which relied significantly on external subcontractors, it produced almost all the Merlin's components itself. Hillingdon required "a great deal of attention from Hives" from when it was producing its first complete engine; it had the highest proportion of unskilled workers in any Rolls-Royce-managed factory”. Engines began to leave the production line in November 1940, and by June 1941 monthly output had reached 200, increasing to more than 400 per month by March 1942. In total 23,675 engines were produced. Worker absenteeism became a problem after some months due to the physical and mental effects of wartime conditions such as the frequent occupation of air-raid shelters. It was agreed to cut the punishing working hours slightly to 82 hours a week, with one half-Sunday per month awarded as holiday. Record production is reported to have been 100 engines in one day.


title: Rolls-Royce Merlin

text: Immediately after the war the site repaired and overhauled Merlin and Griffon engines, and continued to manufacture spare parts. Finally, following the production of the Rolls-Royce Avon turbojet and others, the factory was closed in 2005.


title: Rolls-Royce Merlin

text: The Ford Motor Company was asked to produce Merlins at Trafford Park, Stretford, near Manchester, and building work on a new factory was started in May 1940 on a site. Built with two distinct sections to minimise potential bomb damage, it was completed in May 1941 and bombed in the same month. At first, the factory had difficulty in attracting suitable labour, and large numbers of women, youths and untrained men had to be taken on. Despite this, the first Merlin engine came off the production line one month later and it was building the engine at a rate of 200 per week by 1943, at which point the joint factories were producing 18,000 Merlins per year. In his autobiography "Not much of an Engineer", Sir Stanley Hooker states: "... once the great Ford factory at Manchester started production, Merlins came out like shelling peas ...".


title: Rolls-Royce Merlin

text: Some 17,316 people worked at the Trafford Park plant, including 7,260 women and two resident doctors and nurses. Merlin production started to run down in August 1945, and finally ceased on 23 March 1946.


title: Rolls-Royce Merlin

text: As the Merlin was considered to be so important to the war effort, negotiations were started to establish an alternative production line outside the UK. Rolls-Royce staff visited North American automobile manufacturers to select one to build the Merlin in the U.S. or Canada. Henry Ford rescinded an initial offer to build the engine in the U.S. in July 1940, and the Packard Motor Car Company was selected to take on the $130,000,000 Merlin order (equivalent to $ in dollars). Agreement was reached in September 1940, and the first Packard-built engine, a Merlin XX designated the V-1650-1, ran in August 1941. Total Merlin production by Packard was 55,523.


title: Rolls-Royce Merlin

text: This is a list of representative Merlin variants, describing some of the mechanical changes made during development of the Merlin. Engines of the same power output were typically assigned different model numbers based on supercharger or propeller gear ratios, differences in cooling system or carburettors, engine block construction, or arrangement of engine controls. Power ratings quoted are usually maximum "military" power. All but the Merlin 131 and 134 engines were "right-hand tractor", "i.e." the propeller rotated clockwise when viewed from the rear. In addition to the mark numbers, Merlin engines were allocated experimental numbers by the Ministry of Supply (MoS) – e.g.: RM 8SM for the Merlin 61 and some variants – while under development; these numbers are noted where possible. Merlin engines used in Spitfires, apart from the Merlin 61, used a propeller reduction ratio of .477:1. Merlins used in bombers and other fighters used a ratio of .42:1.


title: Rolls-Royce Merlin

text: In chronological order, the first operational aircraft powered by the Merlin to enter service were the Fairey Battle, Hawker Hurricane, and Supermarine Spitfire. Although the engine is most closely associated with the Spitfire, the four-engined Avro Lancaster was the most numerous application, followed by the twin-engined de Havilland Mosquito.


title: Rolls-Royce Merlin

text: At the end of World War II, new versions of the Merlin (the 600- and 700-series) were designed and produced for use in commercial airliners such as the Avro Tudor, military transport aircraft such as the Avro York, and the Canadair North Star which performed in both roles. These engines were basically military specification with some minor changes to suit the different operating environment.


title: Rolls-Royce Merlin

text: A Spanish-built version of the Messerschmitt Bf 109 G-2, the 1954 Hispano Aviación HA-1112-M1L "Buchon", was built in Hispano's factory in Seville with the Rolls-Royce Merlin 500/45 engine of  – a fitting powerplant for the last-produced version of the famous Messerschmitt fighter, as the Bf 109 V1 prototype aircraft had been powered by the Rolls-Royce Kestrel V-12 engine in 1935.


title: Rolls-Royce Merlin

text: The CASA 2.111 was another Spanish-built version of a German aircraft, the Heinkel He 111, that was adapted to use the Merlin after the supply of Junkers Jumo 211F-2 engines ran out at the end of the war. A similar situation existed with the Fiat G.59 when available stocks of the Italian licence-built version of the Daimler-Benz DB 605 engine ran short.


title: Rolls-Royce Merlin

text: The Australian built Avro Lincoln from A73-51 used Australian built Commonwealth Aircraft Corporation Merlin 102s.


title: Rolls-Royce Merlin

text: A non-supercharged version of the Merlin using a larger proportion of steel and iron components was produced for use in tanks. This engine, the Rolls-Royce Meteor, in turn led to the smaller Rolls-Royce Meteorite. In 1943, further Meteor development was handed over to Rover, in exchange for Rover's gas turbine interests.


title: Rolls-Royce Merlin

text: In 1938, Rolls-Royce started work on modifying some Merlins which were later to be used in British MTBs, MGBs, and RAF Air-Sea Rescue Launches. For these the superchargers were modified single-stage units and the engine was re-engineered for use in a marine environment. Some 70 engines were converted before priority was given to producing aero engines.


title: Rolls-Royce Merlin

text: Experiments were carried out by the Irish Army involving replacing the Bedford engine of a Churchill tank with a Rolls-Royce Merlin engine salvaged from an Irish Air Corps Seafire aircraft. The experiment was not a success, although the reasons are not recorded.


title: Rolls-Royce Merlin

text: One of the most successful of the World War II era aircraft engines, the Merlin continues to be used in many restored World War II vintage aircraft all over the world. The Royal Air Force Battle of Britain Memorial Flight is a notable current operator of the Merlin. In England the Shuttleworth Collection owns and operates a Merlin-powered Hawker Sea Hurricane IB and a Supermarine Spitfire VC – Both can be seen flying at home displays throughout the summer months.


title: Lincoln–Kennedy coincidences urban legend

text: Claimed coincidences connecting U.S. Presidents Abraham Lincoln and John F. Kennedy are a piece of American folklore of unknown origin. The list of coincidences appeared in the mainstream American press in 1964, a year after the assassination of John F. Kennedy, having appeared prior to that in the GOP Congressional Committee Newsletter. In the 1970s, Martin Gardner examined the list in an article in "Scientific American" (later reprinted in his 1985 book, "The Magic Numbers of Dr. Matrix"), pointing out that several of the claimed coincidences were based on misinformation. Gardner's version of the list contained 16 items; many subsequent versions have circulated much longer lists.


text: A 1999 examination by Snopes found that the listed "coincidences are easily explained as the simple product of mere chance." In 1992, the "Skeptical Inquirer" ran a "Spooky Presidential Coincidences Contest." One winner found a series of sixteen similar coincidences between Kennedy and former Mexican President Álvaro Obregón, while the other came up with similar lists for twenty-one pairs of U.S. presidents.


text: The following are the list of "coincidences" that are commonly associated with the conspiracy, some of which are not true statements:


text: Some urban folklorists have postulated that the list provided a way for people to make sense of two tragic events in American history by seeking out patterns. Gardner and others have said that it is relatively easy to find seemingly meaningful patterns relating any two people or events. The psychological phenomenon of apophenia - defined as "the tendency to perceive order in random configurations" - has been proposed as a possible reason for the lists's enduring popularity.


text: Most of the items above are true, such as the year in which Lincoln and Kennedy were each elected President, but this is not so unusual given that Presidential elections are held only every four years. A few of the items are simply untrue: for example, Lincoln never had a secretary named Kennedy; Lincoln's secretaries were John Hay and John G. Nicolay. However, Lincoln's footman, William H. Crook did advise Lincoln not to go that night to Ford's Theatre. David Mikklenson, on Snopes, also points out numerous ways in which Lincoln and Kennedy don't match, to show the superficial nature of the alleged coincidences: For example, Lincoln was born in 1809 but Kennedy in 1917; though Lincoln and Kennedy were both elected in '60, Lincoln was already in his second term when assassinated but Kennedy was not, and neither the years, months, nor dates of their assassinations match.


text: Buddy Starcher wrote a song recounting many of these coincidences and parallels between the two presidents' careers and deaths entitled "History Repeats Itself." It became a U.S. Top 40 hit for him during the spring of 1966, and reached number two on the Country chart. Cab Calloway also scored a minor chart hit with the song that same year.


title: Allergy

text: Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis. Symptoms may include red eyes, an itchy rash, sneezing, coughing, a runny nose, shortness of breath, or swelling. Note: food intolerances and food poisoning are separate conditions.


title: Allergy

text: Common allergens include pollen and certain foods. Metals and other substances may also cause such problems. Food, insect stings, and medications are common causes of severe reactions. Their development is due to both genetic and environmental factors. The underlying mechanism involves immunoglobulin E antibodies (IgE), part of the body's immune system, binding to an allergen and then to a receptor on mast cells or basophils where it triggers the release of inflammatory chemicals such as histamine. Diagnosis is typically based on a person's medical history. Further testing of the skin or blood may be useful in certain cases. Positive tests, however, may not necessarily mean there is a significant allergy to the substance in question.


title: Allergy

text: Early exposure of children to potential allergens may be protective. Treatments for allergies include avoidance of known allergens and the use of medications such as steroids and antihistamines. In severe reactions, injectable adrenalin (epinephrine) is recommended. Allergen immunotherapy, which gradually exposes people to larger and larger amounts of allergen, is useful for some types of allergies such as hay fever and reactions to insect bites. Its use in food allergies is unclear.


title: Allergy

text: Allergies are common. In the developed world, about 20% of people are affected by allergic rhinitis, about 6% of people have at least one food allergy, and about 20% have or have had atopic dermatitis at some point in time. Depending on the country, about 1–18% of people have asthma. Anaphylaxis occurs in between 0.05–2% of people. Rates of many allergic diseases appear to be increasing. The word "allergy" was first used by Clemens von Pirquet in 1906.


title: Allergy

text: Many allergens such as dust or pollen are airborne particles. In these cases, symptoms arise in areas in contact with air, such as the eyes, nose, and lungs. For instance, allergic rhinitis, also known as hay fever, causes irritation of the nose, sneezing, itching, and redness of the eyes. Inhaled allergens can also lead to increased production of mucus in the lungs, shortness of breath, coughing, and wheezing.


title: Allergy

text: Aside from these ambient allergens, allergic reactions can result from foods, insect stings, and reactions to medications like aspirin and antibiotics such as penicillin. Symptoms of food allergy include abdominal pain, bloating, vomiting, diarrhea, itchy skin, and hives. Food allergies rarely cause respiratory (asthmatic) reactions, or rhinitis. Insect stings, food, antibiotics, and certain medicines may produce a systemic allergic response that is also called anaphylaxis; multiple organ systems can be affected, including the digestive system, the respiratory system, and the circulatory system. Depending on the severity, anaphylaxis can include skin reactions, bronchoconstriction, swelling, low blood pressure, coma, and death. This type of reaction can be triggered suddenly, or the onset can be delayed. The nature of anaphylaxis is such that the reaction can seem to be subsiding but may recur throughout a period of time.


title: Allergy

text: Substances that come into contact with the skin, such as latex, are also common causes of allergic reactions, known as contact dermatitis or eczema. Skin allergies frequently cause rashes, or swelling and inflammation within the skin, in what is known as a "weal and flare" reaction characteristic of hives and angioedema.


title: Allergy

text: With insect stings, a large local reaction may occur in the form of an area of skin redness greater than 10 cm in size that can last one to two days. This reaction may also occur after immunotherapy.


title: Allergy

text: Risk factors for allergies can be placed in two broad categories, namely host and environmental factors. Host factors include heredity, sex, race, and age, with heredity being by far the most significant. However, there have been recent increases in the incidence of allergic disorders that cannot be explained by genetic factors alone. Four major environmental candidates are alterations in exposure to infectious diseases during early childhood, environmental pollution, allergen levels, and dietary changes.


title: Allergy

text: Dust mite allergy, also known as house dust allergy, is a sensitization and allergic reaction to the droppings of house dust mites. The allergy is common and can trigger allergic reactions such as asthma, eczema, or itching. It is the manifestation of a parasitosis. The mite's gut contains potent digestive enzymes (notably peptidase 1) that persist in their feces and are major inducers of allergic reactions such as wheezing. The mite's exoskeleton can also contribute to allergic reactions. Unlike scabies mites or skin follicle mites, house dust mites do not burrow under the skin and are not parasitic.


title: Allergy

text: A wide variety of foods can cause allergic reactions, but 90% of allergic responses to foods are caused by cow's milk, soy, eggs, wheat, peanuts, tree nuts, fish, and shellfish. Other food allergies, affecting less than 1 person per 10,000 population, may be considered "rare". The use of hydrolyzed milk baby formula versus standard milk baby formula does not appear to affect the risk.


title: Allergy

text: The most common food allergy in the US population is a sensitivity to crustacea. Although peanut allergies are notorious for their severity, peanut allergies are not the most common food allergy in adults or children. Severe or life-threatening reactions may be triggered by other allergens and are more common when combined with asthma.


title: Allergy

text: Rates of allergies differ between adults and children. Children can sometimes outgrow peanut allergies. Egg allergies affect one to two percent of children but are outgrown by about two-thirds of children by the age of 5. The sensitivity is usually to proteins in the white, rather than the yolk.


title: Allergy

text: Milk-protein allergies are most common in children. Approximately 60% of milk-protein reactions are immunoglobulin E-mediated, with the remaining usually attributable to inflammation of the colon. Some people are unable to tolerate milk from goats or sheep as well as from cows, and many are also unable to tolerate dairy products such as cheese. Roughly 10% of children with a milk allergy will have a reaction to beef. Beef contains small amounts of proteins that are present in greater abundance in cow's milk. Lactose intolerance, a common reaction to milk, is not a form of allergy at all, but due to the absence of an enzyme in the digestive tract.


title: Allergy

text: Those with tree nut allergies may be allergic to one or to many tree nuts, including pecans, pistachios, pine nuts, and walnuts. In addition, seeds, including sesame seeds and poppy seeds, contain oils in which protein is present, which may elicit an allergic reaction.


title: Allergy

text: Allergens can be transferred from one food to another through genetic engineering; however genetic modification can also remove allergens. Little research has been done on the natural variation of allergen concentrations in unmodified crops.


title: Allergy

text: Latex can trigger an IgE-mediated cutaneous, respiratory, and systemic reaction. The prevalence of latex allergy in the general population is believed to be less than one percent. In a hospital study, 1 in 800 surgical patients (0.125 percent) reported latex sensitivity, although the sensitivity among healthcare workers is higher, between seven and ten percent. Researchers attribute this higher level to the exposure of healthcare workers to areas with significant airborne latex allergens, such as operating rooms, intensive-care units, and dental suites. These latex-rich environments may sensitize healthcare workers who regularly inhale allergenic proteins.


title: Allergy

text: The most prevalent response to latex is an allergic contact dermatitis, a delayed hypersensitive reaction appearing as dry, crusted lesions. This reaction usually lasts 48–96 hours. Sweating or rubbing the area under the glove aggravates the lesions, possibly leading to ulcerations. Anaphylactic reactions occur most often in sensitive patients who have been exposed to a surgeon's latex gloves during abdominal surgery, but other mucosal exposures, such as dental procedures, can also produce systemic reactions.


title: Allergy

text: Latex and banana sensitivity may cross-react. Furthermore, those with latex allergy may also have sensitivities to avocado, kiwifruit, and chestnut. These people often have perioral itching and local urticaria. Only occasionally have these food-induced allergies induced systemic responses. Researchers suspect that the cross-reactivity of latex with banana, avocado, kiwifruit, and chestnut occurs because latex proteins are structurally homologous with some other plant proteins.


title: Allergy

text: About 10% of people report that they are allergic to penicillin; however, 90% turn out not to be. Serious allergies only occur in about 0.03%.


title: Allergy

text: Typically, insects which generate allergic responses are either stinging insects (wasps, bees, hornets and ants) or biting insects (mosquitoes, ticks). Stinging insects inject venom into their victims, whilst biting insects normally introduce anti-coagulants.


title: Allergy

text: Another non-food protein reaction, urushiol-induced contact dermatitis, originates after contact with poison ivy, eastern poison oak, western poison oak, or poison sumac. Urushiol, which is not itself a protein, acts as a hapten and chemically reacts with, binds to, and changes the shape of integral membrane proteins on exposed skin cells. The immune system does not recognize the affected cells as normal parts of the body, causing a T-cell<nowiki>-</nowiki>mediated immune response. Of these poisonous plants, sumac is the most virulent. The resulting dermatological response to the reaction between urushiol and membrane proteins includes redness, swelling, papules, vesicles, blisters, and streaking.


title: Allergy

text: Estimates vary on the percentage of the population that will have an immune system response. Approximately 25 percent of the population will have a strong allergic response to urushiol. In general, approximately 80 percent to 90 percent of adults will develop a rash if they are exposed to of purified urushiol, but some people are so sensitive that it takes only a molecular trace on the skin to initiate an allergic reaction.


title: Allergy

text: Allergic diseases are strongly familial: identical twins are likely to have the same allergic diseases about 70% of the time; the same allergy occurs about 40% of the time in non-identical twins. Allergic parents are more likely to have allergic children, and those children's allergies are likely to be more severe than those in children of non-allergic parents. Some allergies, however, are not consistent along genealogies; parents who are allergic to peanuts may have children who are allergic to ragweed. The likelihood of developing allergies is inherited and related to an irregularity in the immune system, but the specific allergen is not.


title: Allergy

text: The risk of allergic sensitization and the development of allergies varies with age, with young children most at risk. Several studies have shown that IgE levels are highest in childhood and fall rapidly between the ages of 10 and 30 years. The peak prevalence of hay fever is highest in children and young adults and the incidence of asthma is highest in children under 10.


title: Allergy

text: Ethnicity may play a role in some allergies; however, racial factors have been difficult to separate from environmental influences and changes due to migration. It has been suggested that different genetic loci are responsible for asthma, to be specific, in people of European, Hispanic, Asian, and African origins.


title: Allergy

text: Allergic diseases are caused by inappropriate immunological responses to harmless antigens driven by a TH2-mediated immune response. Many bacteria and viruses elicit a TH1-mediated immune response, which down-regulates TH2 responses. The first proposed mechanism of action of the hygiene hypothesis was that insufficient stimulation of the TH1 arm of the immune system leads to an overactive TH2 arm, which in turn leads to allergic disease. In other words, individuals living in too sterile an environment are not exposed to enough pathogens to keep the immune system busy. Since our bodies evolved to deal with a certain level of such pathogens, when they are not exposed to this level, the immune system will attack harmless antigens, and thus normally benign microbial objects—like pollen—will trigger an immune response.


title: Allergy

text: The hygiene hypothesis was developed to explain the observation that hay fever and eczema, both allergic diseases, were less common in children from larger families, which were, it is presumed, exposed to more infectious agents through their siblings, than in children from families with only one child. The hygiene hypothesis has been extensively investigated by immunologists and epidemiologists and has become an important theoretical framework for the study of allergic disorders. It is used to explain the increase in allergic diseases that have been seen since industrialization, and the higher incidence of allergic diseases in more developed countries. The hygiene hypothesis has now expanded to include exposure to symbiotic bacteria and parasites as important modulators of immune system development, along with infectious agents.


title: Allergy

text: Epidemiological data support the hygiene hypothesis. Studies have shown that various immunological and autoimmune diseases are much less common in the developing world than the industrialized world, and that immigrants to the industrialized world from the developing world increasingly develop immunological disorders in relation to the length of time since arrival in the industrialized world. Longitudinal studies in the third world demonstrate an increase in immunological disorders as a country grows more affluent and, it is presumed, cleaner. The use of antibiotics in the first year of life has been linked to asthma and other allergic diseases. The use of antibacterial cleaning products has also been associated with higher incidence of asthma, as has birth by Caesarean section rather than vaginal birth.


title: Allergy

text: Chronic stress can aggravate allergic conditions. This has been attributed to a T helper 2 (TH2)-predominant response driven by suppression of interleukin 12 by both the autonomic nervous system and the hypothalamic–pituitary–adrenal axis. Stress management in highly susceptible individuals may improve symptoms.


title: Allergy

text: Allergic diseases are more common in industrialized countries than in countries that are more traditional or agricultural, and there is a higher rate of allergic disease in urban populations versus rural populations, although these differences are becoming less defined. Historically, the trees planted in urban areas were predominantly male to prevent litter from seeds and fruits, but the high ratio of male trees causes high pollen counts, a phenomenon that horticulturist Tom Ogren has called "botanical sexism".


title: Allergy

text: Alterations in exposure to microorganisms is another plausible explanation, at present, for the increase in atopic allergy. Endotoxin exposure reduces release of inflammatory cytokines such as TNF-α, IFNγ, interleukin-10, and interleukin-12 from white blood cells (leukocytes) that circulate in the blood. Certain microbe-sensing proteins, known as Toll-like receptors, found on the surface of cells in the body are also thought to be involved in these processes.


title: Allergy

text: Gutworms and similar parasites are present in untreated drinking water in developing countries, and were present in the water of developed countries until the routine chlorination and purification of drinking water supplies. Recent research has shown that some common parasites, such as intestinal worms (e.g., hookworms), secrete chemicals into the gut wall (and, hence, the bloodstream) that suppress the immune system and prevent the body from attacking the parasite. This gives rise to a new slant on the hygiene hypothesis theory—that co-evolution of humans and parasites has led to an immune system that functions correctly only in the presence of the parasites. Without them, the immune system becomes unbalanced and oversensitive. In particular, research suggests that allergies may coincide with the delayed establishment of gut flora in infants. However, the research to support this theory is conflicting, with some studies performed in China and Ethiopia showing an increase in allergy in people infected with intestinal worms. Clinical trials have been initiated to test the effectiveness of certain worms in treating some allergies. It may be that the term 'parasite' could turn out to be inappropriate, and in fact a hitherto unsuspected symbiosis is at work. For more information on this topic, see Helminthic therapy.


title: Allergy

text: In the initial stages of allergy, a type I hypersensitivity reaction against an allergen encountered for the first time and presented by a professional antigen-presenting cell causes a response in a type of immune cell called a T2 lymphocyte, a subset of T cells that produce a cytokine called interleukin-4 (IL-4). These T2 cells interact with other lymphocytes called B cells, whose role is production of antibodies. Coupled with signals provided by IL-4, this interaction stimulates the B cell to begin production of a large amount of a particular type of antibody known as IgE. Secreted IgE circulates in the blood and binds to an IgE-specific receptor (a kind of Fc receptor called FcεRI) on the surface of other kinds of immune cells called mast cells and basophils, which are both involved in the acute inflammatory response. The IgE-coated cells, at this stage, are sensitized to the allergen.


title: Allergy

text: If later exposure to the same allergen occurs, the allergen can bind to the IgE molecules held on the surface of the mast cells or basophils. Cross-linking of the IgE and Fc receptors occurs when more than one IgE-receptor complex interacts with the same allergenic molecule and activates the sensitized cell. Activated mast cells and basophils undergo a process called degranulation, during which they release histamine and other inflammatory chemical mediators (cytokines, interleukins, leukotrienes, and prostaglandins) from their granules into the surrounding tissue causing several systemic effects, such as vasodilation, mucous secretion, nerve stimulation, and smooth muscle contraction. This results in rhinorrhea, itchiness, dyspnea, and anaphylaxis. Depending on the individual, allergen, and mode of introduction, the symptoms can be system-wide (classical anaphylaxis) or localized to specific body systems. Asthma is localized to the respiratory system and eczema is localized to the dermis.


title: Allergy

text: After the chemical mediators of the acute response subside, late-phase responses can often occur. This is due to the migration of other leukocytes such as neutrophils, lymphocytes, eosinophils, and macrophages to the initial site. The reaction is usually seen 2–24 hours after the original reaction. Cytokines from mast cells may play a role in the persistence of long-term effects. Late-phase responses seen in asthma are slightly different from those seen in other allergic responses, although they are still caused by release of mediators from eosinophils and are still dependent on activity of T2 cells.


title: Allergy

text: Although allergic contact dermatitis is termed an "allergic" reaction (which usually refers to type I hypersensitivity), its pathophysiology involves a reaction that more correctly corresponds to a type IV hypersensitivity reaction. In type IV hypersensitivity, there is activation of certain types of T cells (CD8+) that destroy target cells on contact, as well as activated macrophages that produce hydrolytic enzymes.


title: Allergy

text: Effective management of allergic diseases relies on the ability to make an accurate diagnosis. Allergy testing can help confirm or rule out allergies. Correct diagnosis, counseling, and avoidance advice based on valid allergy test results reduce the incidence of symptoms and need for medications, and improve quality of life. To assess the presence of allergen-specific IgE antibodies, two different methods can be used: a skin prick test, or an allergy blood test. Both methods are recommended, and they have similar diagnostic value.


title: Allergy

text: Skin prick tests and blood tests are equally cost-effective, and health economic evidence shows that both tests were cost-effective compared with no test. Early and more accurate diagnoses save cost due to reduced consultations, referrals to secondary care, misdiagnosis, and emergency admissions.


title: Allergy

text: Allergy undergoes dynamic changes over time. Regular allergy testing of relevant allergens provides information on if and how patient management can be changed to improve health and quality of life. Annual testing is often the practice for determining whether allergy to milk, egg, soy, and wheat have been outgrown, and the testing interval is extended to 2–3 years for allergy to peanut, tree nuts, fish, and crustacean shellfish. Results of follow-up testing can guide decision-making regarding whether and when it is safe to introduce or re-introduce allergenic food into the diet.


title: Allergy

text: Skin testing is also known as "puncture testing" and "prick testing" due to the series of tiny punctures or pricks made into the patient's skin. Tiny amounts of suspected allergens and/or their extracts ("e.g.", pollen, grass, mite proteins, peanut extract) are introduced to sites on the skin marked with pen or dye (the ink/dye should be carefully selected, lest it cause an allergic response itself). A small plastic or metal device is used to puncture or prick the skin. Sometimes, the allergens are injected "intradermally" into the patient's skin, with a needle and syringe. Common areas for testing include the inside forearm and the back.