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A southern constellation.
(AKA 17: dp. 6,556; 1. 459'3": h. 63': dr. 26'4": s. 16 k.
cpl. 247; a. 1 6"; cl. Andromeda)
Centaurus (AKA-171 was launched 3 September 1943 by Federal Shipbuilding and Dry Dock Co., Kearny, N.J., under a Maritime Commission contract; sponsored by Mrs. J. L. Wilson, acquired by the Navy 20 October 1943; and commissioned the next day, Captain G. E. McCabe, USCG, in command.
Centaurus put to sea from Norfolk, VA., 11 December 1943 with cargo for Pearl Harbor, where she arrived 30 December. On 22 January 1944, she cleared with the Southern Attack Force, bound for Kwajalein Atoll in the Marshall Islands, off which she arrived 31 January. During the initial assault, she landed four waves of cargo-laden craft under the protective fire of Pennsylvania(BB-38) with a smoothness belying her newness at amphibious warfare, and until 6 February she remained off the atoll landing combat cargo to support troops ashore as they encountered stiffening opposition. She returned to Noumea for training and cargo duty until 31 March, when she sailed from Tulagi to carry men and cargo to Manus and proceeded to Langemak Bay, New Guinea. Here she loaded for the landings on northern New Guinea, and on 15 April put to sea in the second assault echelon for Aitape. While her landings here on 23 April were unopposed, difficult surf and beach conditions challenged her skill. After several brief voyages to other New Guinea ports to transport reinforcements to the Hollandia area, Centaurus sailed for amphibious exercises in the Solomon Islands.
From 3 June to 30 June 1944, the attack cargo ship was at sea as part of the reserve force standing by during the invasion of the Marianas, and then returned to Eniwetok to prepare for the return of U.S. forces to Guam. She sailed in the Southern Attack Force for this assault 17 July, and on 21 July, day of the initial attack, began landing combat cargo on the difficult beaches near Agat, where Japanese forces offered stiff resistance. She completed offloading cargo and vehicles, and embarking casualties, a week later when she cleared for Eniwetok.
After brief overhaul at Espiritu Santo, Centaurs sailed to Guadalcanal to embark cargo and vehicles for the assault on the Palau Islands, for which she cleared 8 September, At Peleliu on 15 September 1944 she began landing her cargo as heavy opposition developed from the Japanese defenses, cleverly concealed. A fierce fight developed for the marines ashore, and Centaurus remained off the island pouring ashore the equipment essential to the maintenance of the offensive. Taking on board casualties and prisoners of war, the attack cargo ship also carried marines when she cleared on 4 October for the Russells, where all passengers were disembarked. She herself continued on to San Francisco where from 26 October to 22 December she was in overhaul.
Centaurus returned to the Pacific by way of Guam. and after rehearsal landings in the Solomons, joined the Northern Attack Force for the invasion of Okinawa with which she sailed from Ulithi 27 March. Arriving off the island for the assault on 1 April, Centaurus began to discharge cargo at an ever.quickening pace as she supported the first rapid advances of the 6th Marines across the island. Operations went smoothly despite heavy kamikaze attacks; Centaurus guns helped slash two. She cleared Okinawa 9 April for Pearl Harbor' where she loaded additional cargo for the Okinawa operation. Returning to Okinawa 3 June, she offloaded and on 14 June sailed for the United States via Pearl Harbor, and between 19 July and 23 August was in after overhaul at Seattle. Centaurus returned to the Far East and operated in the redeployment of troops. On 31 January 1946 she returned to Seattle and thence proceeded to New York City, where she arrived on 23 March and was decommissioned 30 April 1946. She returned to the Maritime Commission 11 September 1946.
Centaurus received six battle stars for World War II service.
- The Centaurus A is the largest and nearest radio galaxy, a massive source of radio wavelengths in the constellation Centaurus.
- It has an active nucleus which means that matter falls into the supermassive black hole in its centre and shoots electrons from its poles at the half the speed of light, creating massive jets that spread thousands light years into space.
- It is probably a result of two galaxy smashing onto each other, one older elliptical galaxy that merges with a smaller spiral galaxy.
- The epic radio lobes that spreads millions of light years in the opposite direction from the dust band is probably a result of this collision.
- It shoots two gigantic jets of high-energy radiation from its centre which is a result of the black hole swallowing the falling matter.
- There is evidence of enormous starburst, a process of formation of new blue stars in the dust band, as well as the edges of the two massive radio lobes.
Distance: 10-16 million light years (3 -5 megaparsecs)
Diameter: 60 000 light years
Other designations: NGC 5128, PGC 46957, LEDA 46957, ESO 270-9, Arp 153, Caldwell 77, 4U 1322–42
Located in the Virgo Supercluster, the deep sky galaxy Centaurus A is the fifth brightest galaxy visible in the sky and the closest active radio galaxy with radio lobes and high-energy X-ray jets shooting millions light years across the Universe. This beautiful deep sky object is particularly interesting for astronomers because it emits strong radiation across all wavelengths of the electromagnetic spectrum.
How TSH Levels Change
TSH levels are not very intuitive. Why does a high TSH mean you have an underactive thyroid gland? Why do low levels means the gland is overactive?
Understanding exactly how the thyroid gland works can help.
Your thyroid gland produces thyroid hormone. When it functions properly, your thyroid is part of a feedback loop with your pituitary gland that involves several actions:
First, your pituitary gland senses the level of thyroid hormone that is released into the bloodstream.
Your pituitary then releases the special messenger hormone TSH, which makes the thyroid release more thyroid hormone. From there:
- If your thyroid doesn't produce enough thyroid hormone, your pituitary triggers your thyroid to make more. (This might happen in cases of illness, stress, or surgery, for example.)
- If your thyroid is overactive and producing too much thyroid hormone, your pituitary senses that and slows or shuts down TSH production.
2 THE DESIRED AND UNDESIRED OUTCOMES OF THERAPEUTIC INTERVENTIONS
As COVID-19's suffering spreads, world populations place their faith in public health and medicine. Will we be able to produce and deploy the immunizations and antivirals we desire? Will we implement appropriate public health programs? The history of therapeutics offers imperfect hope, with evidence of both overuse and underuse of our capabilities in clinical medicine and public health.
Humans had the knowledge and technology needed to eradicate smallpox in 1798 but did not succeed until 1977. Immunizations have suppressed many other human infections, especially polio and measles, but these still persist, enabled by burgeoning anti-vaccination sentiment. 29 29 Conis ( 2015 ) Walloch ( 2015 ).
AIDS offers many warnings. 30 30 France ( 2016 ).
Once scientists had identified its modes of transmission, the epidemic, in theory, could have been stopped. That did not happen. Health officials promised an AIDS vaccine by 1986, but this goal remains elusive. The advent of effective antiretroviral therapy transformed the global fight against HIV, but its impact has been incomplete: 770,000 people died of AIDS in 2018. 31 31 Centers for Disease Control and Prevention ( 2020 ).
As Brandt argued, “the promise of the magic bullet has never been fulfilled.” 32 32 Brandt ( 1985 , p. 161).
As we struggle with COVID-19 now, we have neither an immunization nor a proven antiviral. In the absence of modern medical therapy, we have turned to history. In 2007, motivated by fears of resurgent influenza, two teams of historians and epidemiologists looked closely at the 1918 pandemic. Some American cities quickly closed schools, prevented public gatherings, and implemented other forms of social distancing. Other cities delayed. There are some inconsistencies in the data. St. Paul, Minnesota, for instance, suffered only a mild epidemic despite implementing a weak public health response. Nonetheless, a clear trend emerged: early response with layered interventions (such as school closures and public gathering bans) reduced both peak mortality rates and total mortality. 33 33 Hatchett, Mecher, & Lipsitch ( 2007 ) Markel et al. ( 2007 ).
So-called “non-pharmaceutical interventions” could flatten the curve. When COVID-19 struck, some countries—especially those hit hard by SARS in 2003—put this history to good use. China implemented a program of isolation, quarantine, and social distancing unprecedented in its scale and intensity. As other countries awoke to the threat in March, many followed suit. Other countries used what they had learned from SARS and pursued a more targeted approach: widespread testing, contact tracing, and supported isolation. These measures contained COVID-19 in Taiwan without requiring a broad lockdown. 34 34 Hernández & Horton ( 2020 ).
Are these responses appropriate for COVID-19? Which ones? That is the great question of our moment. Analyses of clinical decision-making are useful here. Patients, doctors, and their historians have long been fascinated by the question of how to balance the risks and benefits of therapeutic interventions. 35 35 Pernick ( 1985 ).
Clinical leaders in the United States have become convinced that physicians are not doing this well—they are not “choosing wisely.” 36 36 Morden, Colla, Sequist, & Rosenthal ( 2014 ).
Overuse has been a particular concern. Why would anyone overuse medical interventions? Financial conflicts of interest offer one easy answer. The problem, however, goes much deeper.
When researchers develop new treatments, they ask the key question: “does it work?” They design research studies that measure the desired outcomes. Did the antibiotic kill the bacteria? Did the antihypertensive reduce blood pressure? A second question is equally important: “is it safe?” That is much harder to answer. Some new treatments have unexpected adverse effects. These can be missed if initial studies only measure the desired effects. 37 37 Topol ( 2004 ) Avorn ( 2006 ).
To ascertain the full consequences of an intervention, researchers need to document a wide range of outcomes in their clinical trials and post-marketing surveillance. Since this is expensive and time consuming, it is not done systematically.
To make matters worse, researchers sometimes fail to monitor adverse effects even when those could have been foreseen. In the 1950s, for instance, cardiac surgeons began to use heart-lung machines to perform open-heart surgery. Surgeons knew that these machines were not perfect and that patients' brains would be at particular risk. Sure enough, early case series revealed a devastating toll of coma, strokes, seizures, delirium, and subtler changes in cognition and memory. Innovation soon reduced—but did not eliminate—these cerebral complications. And yet when surgeons rolled out a new operation in the 1960s and 1970s, coronary artery bypass grafting, they initially paid little attention to its cerebral complications. Hundreds of thousands of patients consented to a procedure whose risks had not been fully characterized. When the risks were acknowledged, they were often downplayed or dismissed. 38 38 Jones ( 2013 ).
Case after case has shown that it is easier (and more desirable) to generate knowledge of the efficacy of therapeutic interventions than to ascertain their adverse effects. This asymmetry in information quality leads inevitably to the overuse of therapeutic interventions. When patients and doctors know more about benefit than risk, they will tend towards intervention. This is exacerbated by how patients and doctors frame therapeutic choice. They rarely ask “given all that we know, is the treatment likely to do more good than harm?” Instead, they often ask “is there any chance that this well help?” Since the answer to that second question is almost always “yes,” many patients with dire prognoses pursue any credible therapy in a last-ditch effort to save their lives. 39 39 Brody ( 2019 ).
American medicine in particular has valorized “heroic medicine,” the idea that powerful diseases require powerful cures. 40 40 Warner ( 1986 ) Sullivan ( 1994 ).
From bloodletting to cancer chemotherapy, patients and doctors have pursued a logic of therapeutic assault, the more aggressive and dramatic the better.
These miscalculations may play out again with COVID-19. In the setting of a novel pathogen and a dire pandemic, patients, physicians, and presidents are eager to gamble on the calculus of risk and benefit. There is tremendous pressure to bring new treatments to clinical trial and then to market. Research will focus on the desired effects: can the drugs relieve symptoms? Shorten the course of illness? Reduce mortality? Safety will be a secondary concern. Even though the National Institutes of Health has held firm so far and still requires Phase 1 trials to demonstrate the safety of potential COVID-19 treatments before proceeding to therapeutic testing through Phase 2 and Phase 3 trials, there is pressure to move quickly. The trials will be small and fast. It is likely that adverse effects will only become clear after the new medications and immunizations are deployed widely.
Societies and their citizens misunderstand the relative importance of the health risks they face. The future course of Covid-19 remains unclear (and I may rue these words by year's end). Nonetheless, citizens and their leaders need to think carefully, weigh risks in context, and pursue policies commensurate with the magnitude of the threat. 42 42 Jones ( 2020 , p. 1683).
Other skeptics joined the chorus. John Ioannidis, Stanford's guru of evidence-based medicine, questioned the models and assumptions that justified social distancing. He warned of “a once-in-a-century evidence fiasco” if policies outpaced the evidence behind them. 43 43 Ioannidis ( 2020 ) Finley ( 2020 ).
Our current goal is clear and reasonable: we want to flatten the curve and prevent uncontrolled exponential growth of the epidemic. We do not want to get to the point at which the epidemic would burn itself out for lack of new, susceptible victims, something that could entail the deaths of millions of people. Journalists and researchers have created terrific visualizations to show how we can flatten the curve. Their graphs show case counts and deaths over time, with sliders that let viewers change the intensity of the interventions. The harder we try (for example, the more severely we limit our contacts with other people, the longer we endure this regime of social distancing), the greater the benefit. 44 44 Kristof & Thompson ( 2020 ). For an interactive graphic that gives you power over infection and fatality rates, see Katz, Sanger-Katz, & Quealy ( 2020 ).
These visualizations make the case for heroic public health: we face an unprecedented threat and must commit to unprecedented action, whatever the cost. The sacrifices required by social distancing are a perverse part of its appeal, as they demonstrate the depth of our commitment.
Such interactive graphics, however, only show one approach to social distancing. They do not offer the option that has proven successful in Taiwan, Australia, New Zealand, or Vietnam: aggressive programs of testing, tracing, and targeted isolation. 45 45 Hernández & Horton ( 2020 ) Cave ( 2020 ).
Nor do they show the likely adverse effects of severe social distancing. Where are the plots of job losses, poverty, or domestic violence? All will increase in proportion to the intensity of social distancing. We risk triggering a new epidemic of deaths of despair. 46 46 Case & Deaton ( 2020 ).
Those deaths might not rise exponentially with the drama of an incoming viral epidemic, but their effects could linger and accumulate over many years. The course of an epidemic of poverty and despair, however, is even more uncertain and difficult to quantify than that of COVID-19 itself. Do we know that aggressive social distancing will do more good than harm? Our historical insight comes up short once again. While historians have written extensively about the crisis phase of epidemics, much less is known about their enduring effects.
Stars and Constellations
Images (at bottom of page): | Centaurus Chart: (Figure 1) | Hyginus, 1482, page F3r: (Figure 2) | Bayer, 1661, page zRr: (Figure 3) | Bayer, 1697, page N1v: (Figure 4) | Bayer, 1697, page N2r: (Figure 5) | Bode, 1801, page l: (Figure 6) | Bode, 1801, page r: (Figure 7) | Images digitized by Hannah Magruder.
- Name: Centaurus
- Translation: Centaur (half horse, half man)
- Abbreviation: Cen
- Genitive: Centauri (What is the Genitive form?)
- Size: 9 of 88
- Regions: Southern Southern.
- Located between: Antlia, Argo Navis, Carina, Circinus, Crux, Hydra, Lupus, Musca, Vela
- RA: 13 hours. (What is Right Ascension?)
- Decl: -50 degrees. (Is this constellation ever visible from my latitude? What is Declination?)
- Season: Fall
- Midnight Culmination: 30 March (Where should I look for a constellation on a date before or after its midnight culmination? What is Midnight Culmination?
- References: Chet Raymo, 365 Starry Nights, 64-65,66,113.
Skylore and Literature
- Books: (Book list maintained by JoAnn Palmeri).
- Movies: Internet movie database. (Movie list maintained by Sylvia Patterson).
Origin and History
Hadar, a knee of the Centaur, is on a line from Alpha Centauri to Crux.
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Oklahoma History of Science exhibits: http://hos.ou.edu/exhibits/. Page revised 4/15/04
Bad links, misplaced images, or questions? Contact Kerry Magruder. Thank you.
"If the stars should appear one night in a thousand years, how would men believe and adore, and preserve for many generations the remembrance of the city of God which had been shown. But every night come out these envoys of beauty, and light the universe with their admonishing smile." R. W. Emerson, Nature
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Exhibit credit: Kerry Magruder.
These teaching resources provided by the History of Science Department at the University of Oklahoma.
Centaurus AKA-171 - History
Bamileke (Cameroon, western grasslands region)
c. 19th to 20th Century C.E.
Elephant mask composed of colorful cloth and beads
Hoodlike face- round eyes with red beads and white cloth- strong navy blue tones in the cloth
Cowrie shell decoration on the face and rest of mask
Two long panels- represent the elephant’s trunk- woven raffia fiber adorns the edges of the trunk
Isosceles triangle- geometric designs- sometimes in the shape of an hourglass
Two circles- elephants ears .
This piece of art was meant to be used in performance- the wearer also wore a tunic and a decorative headdress
Very dramatic- many people would wear these masks and emerge from “a large palace compound”
People often added ivory bracelets and rare leopard pelts to adorn these outfits
Headdress- symbol of privilege
Made of red feathers usually (from the African gray parrot)- left the audience awestruck
Purpose was to emphasize the complete power and dominance of the Bamileke king
Intended to worship the elephant- this animal was always seen as a symbol of sovereignty/royal authority
Beads imported from Venice and the Middle East- represent great wealth and status
Black beads- relationship between living and the dead
White beads- ancestors and medicines
Triangular pattern of beads- similar to the configuration of a leopard's spots- this animal was also seen as a great symbol of power and authority- required a lot of respect
Kuosi- elite masking society that owned and wore these Aka Elephant masks
Included royal family, wealthy title holders, and ranking warriors- all came together and showed off the masks during the masquerade
Night Sky Creatures: How to Spot the Centaur and the Wolf
One of the most interesting of the constellations is now dominating the low southern sky at around 9:30 p.m. local daylight time — the mythical half-horse, half-man creature known as the Centaur.
Actually, this particular star pattern, known as Centaurus, is one of two centaurs in our night sky. The other is Sagittarius, the Archer, who traditionally has been depicted as a centaur about to shoot an arrow in the direction of Scorpius, the Scorpion.
Centaurus can be seen completely from the Florida Keys, southernmost Texas and the Hawaiian Islands. Yet in the high latitudes of southern England, an assiduous stargazer must carefully watch the southern horizon for a short look at the 2nd-magnitude star Menkent (about as bright as Polaris, the North Star). In the northern United States, we can use Menkent (also known as Theta Centauri), to guide us to other stars in the constellation such as Iota Centauri and Eta Centauri. [Best Stargazing Events for June (Sky Maps)]
Omega: A great ball of stars
Centaurus is also home to Omega Centauri. This is not a single star but a great swarm of them — indeed, the brightest and most splendid globular cluster in the entire sky.
Shining at a moderately dim magnitude +4, it is easy to glimpse under good sky conditions with the naked eye. Omega Centauri has, in fact, been known since ancient times (albeit as a star). It appeared in the star catalogue of Ptolemy over 18 centuries ago and received the Greek letter designation of Omega from Johannes Bayer.
Edmond Halley (of comet fame) called Omega a nebula in 1677. It was not until 1835 that its true glory as a cluster was revealed by the 18.75-inch (47.6 centimeters) telescope that Sir John Herschel took to South Africa to survey the southern skies.
Of Omega, Herschel wrote: "It is beyond all comparison the richest and largest object of its kind in the heavens." Omega Centauri is about 17,000 light-years away and probably contains more than one million stars.
In 1986, I led a tour to Easter Island and the Chilean Andes to view Halley&rsquos Comet and had an opportunity to view the southern skies firsthand. My view of Omega Centauri through a 3.1-inch (7.9 cm) refracting telescopewas nothing short of amazing — a great ball of stars so closely packed in the center that it appeared as a blur of light.
Theoretically, Omega Centauri can be seen from places as far north as New York or Philadelphia. But I can offer no encouragement to residents of the Big Apple or the City of Brotherly Love, because even if all of their streetlights were somehow extinguished and a fresh, clean Canadian air mass positioned itself directly over the northeastern U.S., the thick haze that is perpetually evident along and near the horizon almost always hides Omega.
And even if one were to somehow get it in view through a telescope, the cluster would be robbed of its full glory. To see Omega Centauri adequately, one should be no farther north than about latitude 35 degrees.
Our nearest stellar neighbors
Of course, Centaurus' greatest claim to fame is that it contains the nearest star in the sky, Rigil Kentaurus. That isn't how this particular star is best known more often than not, it is referred to by the designation Alpha Centauri.
This is the third-brightest star in the sky and is also a beautiful double star, composed of two yellow stars somewhat like the sun. Alpha Centauri is a mere 4.3 light-years from us and has a faint 11th-magnitude companion about 2 degrees away known as Proxima Centauri. Proxima&rsquos position relative to the main pair actually places it a trifle closer to us at the present time. [Alpha Centauri Stars & Planet Explained (Infographic)]
To the upper right of Alpha is the first-magnitude Beta Centauri, which has the name Hadar and seems to be a neighbor. But in reality, Hadar — a blue star about 10,000 times brighter than the sun — lies about 500 light-years away.
And then there&rsquos the Wolf
Just to the east of Centaurus is Lupus, the Wolf. Allegorical star pictures often show Lupus impaled on a sword triumphantly held by the Centaur perhaps he killed the Wolf while hunting and offered it to the gods as a sacrifice.
But in his classic star guide, "The Stars: A New Way to See Them," H.A. Rey depicts Lupus as "trotting beneath one arm of the Centaur, who seems about to seize him." No matter. Lupus' stars seem to be entangled with those of Centaurus, so it is perhaps best to study the two constellations together.
Although none of them are very bright, the dozen or so stars of Lupus make for a sparkling display between Centaurus immediately to the west and the stars of Scorpius to the east.
In their way, the ancients had imaginations as facile and fanciful as ours. While some of us would people the universe with little green men, they placed in the sky a number of exotic beasts of which Centaurus is just one. In the sky itself, we are hard put to imagine the mythological character in the confusing jumble of stars that form Centaurus. This star pattern is often associated with the mythological centaur, Chiron, who was highly skilled in medicine.
This leaves me ending this column with a question. If a centaur fell ill, who would he consult: a physician or a veterinarian?
Centaurus AKA-171 - History
Location: Southern Hemisphere
Right Ascension: 13h
Source: Greek mythology
The story behind the name: Centaurus is one of two constellations said to represent Centaurs, mythical creatures with a human head and torso on top of a horse's body. Centaurus was the name of the first Centaur. The constellation is primarily associated with Chiron (Cheiron), a wise, immortal being who was King of the Centaurs. He was said to be skilled in the healing arts, and to be a scholar and a prophet. From his cave on Mount Pelion, he is said to have raised, tutored, or counselled several persons prominent in Greek mythology, including Jason, Heracles and Asclepius.
There are several stories which explain Chiron's association with this constellation. One legend says that Chiron was the first to identify the constellations and teach them to humans. He placed an image of himself in the sky to help guide Jason on his quest for the Golden Fleece. A different story says that Chiron was placed in the sky by Zeus. There are several variants of the story, but the incident common to most is that Chiron was accidentally wounded by a poisoned arrow and was in such continuous pain that he offered to give up his immortality. In one version, Heracles was attacked by a group of Centaurs who were enraged that he drank from their communal wine jar. An arrow fired at the attackers hit Chiron instead.
In another, Chiron, Achilles and another Centaur, the prophet Pholus, were entertaining Heracles and an arrow (somehow) pierced Chiron's foot. Another version says that Chiron was not so much in pain but just tired of his long life. At this point Chiron's story connects with the legend of Prometheus, the Titan who underwent perpetual torture for stealing fire from the gods to give to humans. Prometheus could not be released from his torture until an immortal being volunteered to give up immortality and go to Tartarus in his place. Someone - there are variants suggesting Zeus, Heracles, or Chiron himself - suggested that Chiron's offer be used to release Prometheus. Zeus honored Chiron with a place in the sky.
Another story suggests that the constellation represents the Centaur Pholus who was honored by Zeus for his skill in prophecy.
The constellation has a large, four-sided shape representing the human head and torso, attached to two legs. Rigel Kentaurus, the triple star system that contains Proxima Centauri, the closest star to our Sun, forms one of the Centaur's feet.
THE BRISTOL family of SLEEVE-VALVE ENGINES
As far back as 1926, the Bristol Aeroplane Co. foresaw the speed and load limitations which would eventually be met in high-performance engines which have push-rod operated over-head valves. The increasing seriousness of maintenance problems with this mechanism was also foreseen. With the encouragement and support of the British Air Ministry, the Company therefore decided to develop the single sleeve-valve.
The first complete Bristol sleeve-valve engine, a nine-cylinder air-cooled radial of 24.9 liters capacity, was designed and built in 1932. It completed its official trials with great success soon afterwards. This was the Perseus. With further development it was the first sleeve-valve aero-engine in the World to be put into large quantity manufacture.
The potential advantages of the sleeve-valve for high-output two-row radial engine design were also apparent. In 1936, the Bristol Hercules fourteen-cylinder radial sleeve-valve engine of 38.7 liters capacity appeared and this was followed by the Taurus, a similar but much smaller engine of 25.4 liters. The latest type is the Centaurus, an eighteen-cylinder development of the Hercules.
After the most thorough endurance and overload testing, which make up many thousands of hours on the dynamometer and in flight, and nearly six years of operational service in the Royal Air Force, Bristol sleeve-valve aero-engines have now definitely achieved a leading position.
All Bristol sleeve-valve engines have high-speed, centrifugal, gear-driven superchargers, either single or two-speed. The supercharger is associated with a carburetor of the latest fully automatic type, incorporating variable-datum servo devices for the control of both boost-pressure and mixture strength.
Later production types employ pressure injection carburetors enabling a closer control of mixture strength under varying conditions and greater freedom from ice formation.
(Photo right: Courtesy of AirArchive.com)
An installation feature of great importance is the arrangement of engine-driven accessories. The crankcase rear cover carries only those accessories which serve the engine unit itself, namely the engine oil pump, the dual fuel pump, the magnetos and the constant-speed airscrew governor unit. All other accessories are carried by a separate accessory gear-box mounted on the bulkhead and driven by the engine through an enclosed flexibly-jointed shaft.
Several alternative arrangements of the gear-box drives are available to provide for the full range of accessories involved in modern aircraft equipment. This arrangement considerably simplifies installation work, and also lends itself to the adoption of standardized, interchangeable power units - a policy long recommended by the Bristol Company.
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