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NHIndustries

NHIndustries (NHI) is a helicopter manufacturing company specifically established to be NATO Helicopter Management Agency's prime contractor for the design and development, industrialisation, production and logistic support of the NHIndustries NH90 series of helicopters.

Established in 1992, NHIndustries was formed as a partnership between Eurocopter of France and Germany (now Airbus Helicopters), Agusta of Italy (now Leonardo) and Stork Fokker Aerospace of the Netherlands (now Fokker Aerostructures).

History
The NHIndustries NH90 is a medium-sized, twin-engine, multi-role military helicopter developed in response to NATO requirements calling for a battlefield helicopter which would also be capable of being operated in naval environments. Both development and manufacture of the rotorcraft has been principally handled by NHIndustries, a collaborative company. It is presently owned by Airbus Helicopters, Leonardo (formerly AgustaWestland) and Fokker Aerostructures.

In 1985, France, West Germany, Italy, the Netherlands, and the United Kingdom teamed to develop a NATO battlefield transport and anti-ship/anti-submarine helicopter for the 1990s. The United Kingdom left the team in 1987. On 1 September 1992, NH Industries signed an NH90 design-and-development contract with NAHEMA (NATO Helicopter Management Agency). This agency represented the four participating nations: France, Germany, Italy, and the Netherlands. Portugal later joined the agency in June 2001.

Design work on the helicopter started in 1993. The first prototype, PT1, made the type's first flight on 18 December 1995. The second prototype, PT2, first flew on 19 March 1997 and the third prototype, PT3, on 27 November 1998. On 12 December 2002, PT3 became the first helicopter to fly exclusively with fly-by-wire controls following the removal of mechanical back-up controls.

The NH90 was developed into two main variants: the Tactical Transport Helicopter (TTH) and the NATO Frigate Helicopter (NFH). These two main variants share about 75% commonality with each other. Many of the operators have requested specific configurations to their own helicopter fleets, thus each nation's NH90 is effectively customized to the end-user's requirements. During the development phase of the programme in the 1990s, both technical and funding problems were experienced. In June 2000, the partner nations placed a large production order for the type, valued at US$8.6 billion, for a total of 366 helicopters. Additional orders have since followed from customers in Europe, Asia, and Australia. By April 2013, a total of 529 NH90s of all variants were on order by various customers.

The NH90 was initially intended to be produced at three exporting final assembly lines (FAL); Cascina Costa in Italy for AgustaWestland, Marignane in France and Donauwörth in Germany for Airbus Helicopters. The Nordic and Australian contracts stipulated production locally (the Nordic ones at Patria in Finland and the Australian ones in Brisbane). Spain has a final assembly line at Albacete. The Marignane assembly line can reportedly complete up to 22 NH90s per year.

The production responsibilities were divided amongst the major sections/components amongst each of the shareholding companies: Once fabricated, items are shipped from these companies to the six final assembly facilities, at Marignane, France; Tessera, Italy; Donauwörth, Germany; Halli, Finland; and Brisbane, Australia.
 * Airbus Helicopters France 31.25% (Engines, Rotors, the Electrical, flight control and the core avionics systems)
 * Airbus Helicopters Deutschland 31.25% (Forward and centre fuselage, the fuel, communications and avionics control systems)
 * Fokker 5.5% (Tail structure, doors, sponsons, landing gear and the intermediate gearbox)
 * AgustaWestland 32% (Rear fuselage, main gearbox, hydraulic system, automatic flight control and plant management systems, power plant and the NFH mission system)

During 2007, the NH90 first entered operational service with the German Army. During April 2010, the Royal Netherlands Navy was the first customer to receive the navalised NH90 NFH variant. In order to speed up delivery and reduce the complexity of manufacturing a large number of variants, NH Industries proposed the adoption of a simplified baseline airframe which could be configured to the individual customer's requirements. Between 2004 and 2016, the production lead times for the NH90 had reduced from 18 months to 7.5 months. During 2014, worldwide production of the NH90 peaked at 53 helicopters. By January 2017, the NH90 had logged 127,000 flight hours in the armed forces of thirteen nations.

title: NHIndustries


text:
Ralliement créditiste

Historically in Quebec, Canada, there were a number of political parties that were part of the Canadian social credit movement. There were various parties at different times with different names at the provincial level, all broadly following the social credit philosophy; at various times they had varying degrees of affiliation with the Social Credit Party of Canada at the federal level.

The greatest success achieved by a provincial social credit party in Quebec was the Ralliement créditiste du Québec, which won 12 seats in the 1970 Quebec provincial election.

Union des électeurs
The Union des électeurs (UE) (in English: "Union of Electors") was founded in 1939 by Louis Even and Gilberte Côté-Mercier. It was the first créditiste political movement to be active in Quebec. It ran two candidates, Even and Armand Turpin in the 1940 federal election as part of the Canada-wide New Democracy movement. Even won 17% of the vote and placed third in the riding of Lake St-John—Roberval. Turpin placed second with over 31.8% of the vote in Hull. Even and the Union attended the founding convention of the Social Credit Association of Canada in 1944 and opposed the bid of the western Canada-based Social Credit federal caucus to establish a central party under the leadership of Solon Low. While Even's group ran candidates in the 1945 federal election under the national Social Credit banner and again in subsequent by-elections, by 1949 the Quebec créditistes were again running candidates under the Union des électeurs banner as they were also doing in the Quebec provincial elections.

The Union was accused of anti-Semitism and of distributing the Protocols of the Elders of Zion in Quebec. The Canadian Jewish Congress referred to it as "fast becoming the rallying point of the numerous Jew-haters in French Canada".

The Union des électeurs' electoral philosophy was that it was not a partisan political party but an organization which marshals voters to enforce their wishes on their elected representatives. Even's belief, like that of social credit originator C.H. Douglas, was that parties were corrupt and that the party system should be replaced by a "union of electors" who would compel elected officials to follow the popular will. Even and the Union broke with the national Social Credit organization in 1947 due to Ernest Manning's increasingly hostile attitude towards them and his purge of anti-Semites from the movement. The Union influenced some Social Crediters outside of Quebec, including the Social Credit Association of Ontario which stood its candidates in the 1948 Ontario elections under the name "Union of Electors". In British Columbia, there was a "Union of Electors" party which ran as a rival to the British Columbia Social Credit League in the 1949 provincial election.

With Réal Caouette and then P. Ernest Grégoire as leader, the Quebec provincial party contested seats in the 1944 provincial election but won no seats and the 1948 provincial election when it managed to get 9.25% of the popular vote, but again won no seats. It also ran candidates federally: Caouette was elected to the House of Commons of Canada in a 1946 by-election under the Social Credit banner. He failed to win re-election in the 1949 federal election as a Union des électeurs candidate, when the party ran a total of 56 candidates. None were successful.

The Union des électeurs faded away as a political party after 1949. In the 1950s, Caouette contested seats in various by-elections against the wishes of Even and Côté-Mercier. In 1958, Caouette broke with Even and Côté-Mercier and founded the Ralliement des créditistes, which ran candidates in federal elections in the 1950s and 1960s and was, at times, the Quebec branch of the Social Credit Party of Canada. In 1970, the federal Ralliement des créditistes founded a distinct provincial branch, the Ralliement créditiste du Québec.

In 1939, Even and Côté also founded a lay Catholic group called the "Pilgrims of Saint Michael", based in Rougemont, Quebec, that continues to promote social credit monetary policy coupled with conservative Catholicism. The Pilgrims publish The Michael Journal in English and Vers Demain in French. The group was founded in 1939 and is nicknamed "the White Berets" for the headgear worn by members.

Candidats des électeurs
Réal Caouette ran under this label in the 1957 and 1958 federal elections, but failed to win a seat.

Candidats libéral des électeurs
In the 1962 and 1963 federal elections, a small breakaway from Social Credit ran a single candidate under the name Candidat libéral des électeurs without success. The 1962 candidate, J.-Edouard Pharon, received 1,800 votes – 500 more than the Social Credit candidate.

Ralliement des créditistes du Canada
Réal Caouette had been a social credit stalwart since the joining the movement in 1939, running as a candidate for the Union des électeurs. He won a seat in the House of Commons in a by-election, but lost it in the next general election. He was a true believer in social credit theory and a charismatic, almost evangelical speaker.

In 1958, he broke with Union des électeurs founders Louis Even and Gilberte Côté-Mercier, and formed the Ralliement des créditistes du Canada as the Quebec wing of the Social Credit Party of Canada on May 4, 1958. Caouette was named leader of the new organization. His party political broadcasts on Quebec television developed a great following. Caouette ran for the leadership of the Social Credit Party of Canada in 1961, but was defeated by Robert N. Thompson.

Driven by Caouette's fiery oratory, the Social Credit Party achieved a breakthrough in the 1962 federal election, winning 26 seats in Quebec. Only four Social Credit MPs were elected in the rest of Canada.

Thompson insisted on remaining national party leader after 1962, even though the Social Credit caucus was overwhelmingly from Quebec and regarded Caouette as its leader. Thompson accepted Caouette as his deputy leader.

This tension led to a split: in 1963, the Quebec wing became independent from the party in the rest of country as the Ralliement des créditistes, or Social Credit Rally in English. Of the 20 Social Credit MPs elected in Quebec in the 1963 federal election, 13 followed Caouette into the Ralliement, five ran in the next election as independents and two joined the Progressive Conservative Party of Canada.

The Ralliement ran as a separate party in the 1965 federal election. Nine of its candidates were elected in Quebec in 1965. It went on to win 14 seats in Quebec in 1968, and then creditiste leader Caouette became leader of the Social Credit Party. The party took seats in Quebec in the 1970s.

In 1968, Thompson joined the Progressive Conservative Party.

Ralliement créditiste
In October 1967, the Ralliement des créditistes changed its name to Ralliement créditiste.

In the 1968 federal election, the Social Credit Party won no seats in the House of Commons, while Caouette's Ralliement créditiste returned 14 MPs.

In 1969, the federal Ralliement créditiste entered provincial politics by running candidates in four Quebec by-elections. The candidates appeared on the ballot without party designation, as the party did not run candidates in the last general election. All were defeated. A dissident group opposed to Caouette's leadership founded the Parti crédit social uni in this period.

The Ralliement créditiste du Québec was created in January 1970 and fielded candidates in the 1970 and 1973 provincial elections.

In 1971, Caouette and the Ralliement créditiste rejoined the Social Credit Party of Canada, and Caouette was elected national leader.

The Social Credit Party under Caouette's leadership won 15 seats in 1972 and 11 in 1974. Under Fabien Roy’s leadership it won 6 in 1979. It won no seats in 1980.

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

title: Ralliement créditiste


text:
J. M. Andrews

John Miller Andrews, (17 July 1871 – 5 August 1956) was the second prime minister of Northern Ireland from 1940 to 1943.

Family life
Andrews was born in Comber, County Down, Ireland in 1871, the eldest child in the family of four sons and one daughter of Thomas Andrews, flax spinner, and his wife Eliza Pirrie, a sister of Viscount Pirrie, chairman of Harland and Wolff.

He was educated at the Royal Belfast Academical Institution. In business, Andrews was a landowner, a director of his family linen-bleaching company and of the Belfast Ropeworks. His younger brother, Thomas Andrews, who died in the 1912 sinking of the RMS Titanic, was managing director of the Harland and Wolff shipyard in Belfast; another brother, Sir James Andrews, 1st Baronet, was Lord Chief Justice of Northern Ireland.

In 1902 he married Jessie (died 1950), eldest daughter of Bolton stockbroker Joseph Ormrod at Rivington Unitarian Chapel, Rivington, near Chorley, Lancashire, England. They had one son and two daughters. His younger brother, Sir James, married Jessie's sister.

Political career
Andrews was elected as a member of parliament in the House of Commons of Northern Ireland, sitting from 1921 until 1953 (for County Down constituency from 1921 to 1929 and for Mid-Down from 1929 to 1953). He was a founder member of the Ulster Unionist Labour Association, which he chaired, and was Minister of Labour from 1921 to 1937. He was Minister of Finance from 1937 to 1940, succeeding to the position on the death of Hugh MacDowell Pollock; on the death of Lord Craigavon, in 1940, he became leader of the Ulster Unionist Party (UUP) and the second Prime Minister of Northern Ireland. Andrews was an opponent of the Irish language and called for it to be banned in schools.

In April 1943 backbench dissent forced him from office. He was replaced as Prime Minister by Sir Basil Brooke. Andrews remained, however, the recognised leader of the UUP for a further three years. Five years later he became the Grand Master of the Orange Order. From 1949, he was the last parliamentary survivor of the original 1921 Northern Ireland Parliament, and as such was recognised as the Father of the House. He is the only Prime Minister of Northern Ireland not to have been granted a peerage; his predecessor and successor received hereditary viscountcies, and later prime ministers were granted life peerages.

Throughout his life he was deeply involved in the Orange Order; he held the positions of Grand Master of County Down from 1941 and Grand Master of Ireland (1948–1954). In 1949 he was appointed Imperial Grand Master of the Grand Orange Council of the World.

Andrews was a committed and active member of the Non-subscribing Presbyterian Church of Ireland. He regularly attended Sunday worship, in the church built on land donated by his great-grandfather James Andrews in his home town Comber. Andrews served on the Comber Congregational Committee from 1896 until his death in 1956 (holding the position of Chairman from 1935 onwards). He is buried in the small graveyard adjoining the church.

He was named after his maternal great-uncle, John Miller of Comber (1795–1883).

title: J. M. Andrews


text:
Ruhleben Barracks

The Ruhleben barracks (Ruhleben-Kaserne) is part of the German naval establishment located in Plön, Holstein, Germany.

From 1940 to 1945 it was home to the III U-Boat Training Division (III Untersee-Boot Ausbildungsabteilung). On April 22, 1945 Grand Admiral Karl Dönitz moved the headquarters of the Naval High Command (Oberkommando der Marine) there. As of April 30, 1945 until May 2, 1945, following Dönitz being named head of the German Reich, it was the de facto capital of Germany.

On May 7, 1945, the installation was captured by British forces who installed themselves there and renamed it the Connaught Barracks. Towards the end of formal British occupation, the British set up the King Alfred School on March 10, 1948, to teach the children of the British military service personnel stationed in Germany.

Following the re-establishment of the German Navy, the barracks reopened as the home of the Naval NCO School (Marineunteroffizierschule Plön) on September 9, 1960.

title: Ruhleben Barracks


text:
Talk:Sex ratio

Wiki Education Foundation-supported course assignment
This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Peer reviewers: Yesi10garcia.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 09:03, 17 January 2022 (UTC)

Untitled
I'm not happy with this, so I'm going to change it. It appears you may be coming from a geography background whereas I'm coming from biology. A permille number is not a ratio. a ratio should be 1:1 or 0.96:1.00 or something.

 * Yes, User:Hemanshu Hemanshu said that Sex Ratio is counted in different ways... clarification is needed. But, AFAIK, it is expressed just in number here in India. Example: 953 - which means 953:1000. The important thing to note is: it's not expressed as percentage; but counted for 1000. Your modification sounds bit odd for me as I never heard this. BTW, I'm not from geography. --Rrjanbiah 05:24, 12 Mar 2004 (UTC)

Another limitation to this article is it's fixating on a particular sex ratio at birth of 105:100 for human populations. While this may be the best estimate from a strictly biological standpoint for all human populations, demographers seem to recognize that in actual societies the "natural" sex ratios at birth vary from roughly 103:100 to 107:100. I hope someone more familiar than I with this literature will address the issue of variation from one society to the next, including also differences by "race" and ethnicity. Thank you. Mack2 04:28, 21 June 2006 (UTC)

 * Honestly, just do it yourself. Wikipedia is a work in progress. Regards, User:Samsara (talk • contribs) 14:22, 21 June 2006 (UTC)

Re the "natural" range in societies: I think adding the range up to 120:100 for Jewish populations in Russia in 19th C confuses the issue, especially without any citation and discussion. This this may be a case (citation needed, however) where special cultural practices created an unusual sex ratio at birth in a particular population. But the point of my previous edit was to show that demographers have widely come to accept a range of 103 to 107 as "normal" (i.e., typical in a statistical sense) in the absence of particular "culturally" derived interventions. I have now provided a citation of the range that I entered earlier (103-107) but would regard reporting this normal range as 103 to 120 as inappropriate. If someone wants to speak to the specific case of some 19th C Russian villages, or, for that matter, the more extreme sex ratios observed in parts of the world today, in particular those with strong son preferencd, and then to elaborate the analysis of cultural influences on sex ratios, then I encourage them to do so. There's a place-holder already for Social Factors, and this is where, it seems to me cultural and social factors should be elaborated. Mack2 01:24, 25 June 2006 (UTC) Mack2 05:42, 25 June 2006 (UTC)

To Samsara: Thanks, the Livonian Jewish communities reference is good as documented, though a curious  figure that deserves further confirmation and explanation, most likely in cultural/historical terms. There's apparently another recent book that mentions this (article was referred to me from NYT I a few weeks ago). If I can find it, I'll add it to your citation; not sure it refers to Darwin and Livonia specifically or to alternative sources.Mack2 00:49, 26 June 2006 (UTC)

Monogamy
From the article: ...socially-monogamous species such as humans... I think this is misleading, monogamy may be a Western idea l but is not universal. From the article on polygamy: "According to the Ethnographic Atlas Codebook, of the 1231 societies noted, 186 were monogamous. 453 had occasional polygyny, 588 had more frequent polygyny, and 4 had polyandry." Swans may be a better example of a monogamous species. 80.73.222.245 20:38, 30 October 2007 (UTC)

Sources for Demographic Statistics
It appears to be common practice in Wikipedia to report country-level population statistics from the CIA World Factbook. The CIA does not create these data nor, for the most part, evaluate or correct them. It gets them from the UN's collections or from US Census Bureau reports. I've written a note on the "map" of sex ratios that's included in this article to point out that the map doesn't give a reference year; in fact it doesn't even cite the year of the CIA World Factbook edition. Of course, assuming, say, that the 2005 Factbook is used still doesn't tell us the year to which the sex ratio data refer. Certainly not 2005, since there is a lag between the collection of data and their reporting to UN agencies. Furthermore, data from different countries reported in the Factbook may refer to different years, so that country-to-country comparisons should be made cautiously. I also pointed out that the figure for China (112) in the latest Factbook is out of date, perhaps by 10 years; I suspect the data for many other countries are also out of date by quite a few years. In the case of sex ratios, which may undergo rapid change from year to year, reporting the date and recognizing that there may be trends in the data are very important. This is an issue not just for sex ratios but for many of the statistics (economic, population, etc.) reported in the Factbook. As it stands, the map in this article is undocumented as to the date of publication of the source used or the date of the underlying demogrpaphic data that is being summarized.Mack2 00:50, 5 July 2006 (UTC) I've noted the same problem with the map in the infant mortality rate article.Mack2 00:52, 5 July 2006 (UTC)

Remove Map
In addition to the criticism above, I believe the map is misleading. The typical male female ratio at birth is say 1.05 and since women tend to live longer, it decreases in time. This far outweighs any but a very huge imbalance and therefore the map effectively only gives an indication of the age of a country's population.

—Preceding unsigned comment added by 87.254.81.209 (talk) 20:05, 14 December 2007 (UTC)

Claim about motility of X and Y sperm
I just did a quick search for references supporting the unreferenced claim that sperm bearing the Y chromosome swim faster than those bearing the X chromosome. I wasn't able to find any such references, and furthermore, I found this page suggesting that the idea is nothing but an "old wives' tale":

If anyone has more time / knowledge to apply to this issue, I would flag it as a high priority for improving this article.

Amber Kerr 22:20, 5 February 2007 (UTC) Amber Kerr

 * My mother always told me that male sperm swim faster than female sperm, but female sperm are stronger than male sperm. I'm not sure if it is true or not, but it sounds feasible, as female infants are stronger and more likely to survive than male infants. --Candy-Panda 06:54, 4 March 2007 (UTC)

Country sex ratios
I will be busy, so I do not have enough time to do this, but if anyone is brave enough, could someone please put the list of countries in alphabetical order? Thank you --Robin63 09:28, 12 February 2007 (UTC)
 * Why?? Sorting by numbers has its advantages, and if a person is looking for a specific country they can search with their browser. Mathmo Talk 05:56, 24 March 2007 (UTC)

Bare Branches
I think there should be an article about the "Bare Branches" effect experiences in some Asian contries. —The preceding unsigned comment was added by 206.248.161.207 (talk) 05:17, 4 May 2007 (UTC).

far too human-centric
there needs to be a separate article on sex ratio in humans as this is all about humans and humans are not the only sexual organisms.

Need editing assistance
at Evolutionary theory of sex--Filll 23:10, 26 July 2007 (UTC)

Negative feedback
I have removed the following section. I am removing it for a few reasons. First of all, it's a fairly fringe theory which does not appear to have had a significant impact on the field and including it here gives it undue weight. Secondly, the author of the paragraph is Mr Geodakian's son and as such is in an odd position to include this material. Last but not least it is too poorly written to be understandable. I should note that any study of the sex ratio in harems would appear suspect to most scientists since the data is utterly unreliable and does not take into account the strong possibility of selective infanticide. It also seems clear that no experiment on plants or animal species will be of any help to explain the increased birth rate of boys in war-times or in harems and, as far as I know, there is no solid study even establishing such an imbalance in war-times. Pascal.Tesson 17:02, 9 August 2007 (UTC)
 * Negative feedback is responsible for increased boy’s birth rates during war-times and also in harems. It realizes, through different levels of sexual activity, differential gamete aging and elimination and amount of pollen in plants. The concept was proposed by V. Geodakian in 1965 and confirmed using many plant, animal species and also on humans.

Hi, Pascal

The main characteristics of a dioecious population: sex ratio, variation and sexual dimorphism should be considered by not as constants, specific for given species, as it was believed earlier, but as variables closely related to the environment. They determine evolutionary flexibility of a species.

In stable conditions (the optimum environment) they should decrease thus reducing the evolutionary plasticity of the species and in changeable conditions (the extreme environment)—grow, raising the plasticity. Similar to pharmacokinetics which with development of models moved from tables to curves, functions and parameters, sex ratio can be presented the same way.

All sex ratio values (primary, secondary and tertiary) depend upon each other: primary determines secondary which in turn determines tertiary (direct relationship). Some environmental conditions selectively kill one sex, so sex ratio gets altered. If there is no compensation in the next generation the change will continue to grow which eventually can lead to complete elimination of one sex. There should exist a regulating mechanism (negative feedback) to bring sex ratio back to its equilibrium. This is a modern consistent view backed up with a lot of data. Harems just a small, not so significant fraction of it. Selective infanticide will increase number of reported boys. Contrary, the effect of high male mortality under harsh conditions (confirmed on many species) will decrease it. I was surprised to see that different harems had similar sex ratio close to 62% boys. Which was also the case for families with 5 wives. If exposed (with all careful wording) this material can bring more data and stimulate research. From the other hand I understand that encyclopedia is (and should be) a conservative source of trusted information. Therefore I completely trust your judgment if you decide to remove it.Sashag 23:57, 10 August 2007 (UTC)

red/blue
Call me traditional or an old fogey, but I would have thought it would have been more intuitive to have males represented by blue and females by red. Jooler 12:52, 12 September 2007 (UTC)

 * That occured to me, as well. When I first looked at the maps, I was truely thrown, thinking it showed a few countries as the exact opposite of what I expected. Then I noticed the key. Argh.
 * I think the gender boys=blue, girls=pink thing is firmly engrained enough to think it would be a general expectation, like red/blue for hot/cold, etc.
 * Mdbrownmsw 16:17, 19 September 2007 (UTC)

Agreed. I wrote this before noticing this section:

I am sure there are many sexist things in this topic against men, so I've chosen not to read it. All I have to say right now is that it's odd that women are indicated by blue, men with red. Blue is the color of Men, Pink traditionally of women. This only becomes an issue when you start to wonder why Men have been explicitly marked in red, against all tradition. I propose it is to subconsciously imply that anywhere with an overwhelming male presence is a problem. I cannot think of any other reason why women would be denoted by a nice cool male blue, and men with a "Uh-oh, Saudi Arabian terrorists" red. Red on maps is traditionally the color used for "cause for concern" or "danger" or something similar. It's a very simple point-Male is blue, female is pink. If you don't like pink, use green. Given the constant vilification of males in all media, one must be vigilant. —Preceding unsigned comment added by 87.254.81.209 (talk) 20:40, 14 December 2007 (UTC)

 * I find your claims somewhat ridiculous and please assume good faith. Also, firstly as you have already said it is pink that is usually associated with feminity or females not red. Also it's not true the claim that this is this is some sort of tradition. The evidence suggests that in reality that this tradition is fairly recent with blue representing females and pinks males prior to around the 1940s in Western countries. See for example Baby blue and Pink. And I emphasises Western countries here for a reason. While I think given the strong influence of Western culture the blue=boys, pink=girls trend has some degree of hold in much of the world, I highly doubt it's universal even more so when you start to think about blue and red (which is different from blue/pink). Red for example is a popular colour in many East Asian societies and I'm not convinced it's going to be strongly associated with feminity (perhaps you don't know this but in many such East Asian societies, profits or positive are usually red whereas black or green is used for losses or debts i.e. the opposite of the norm in much of the West, see and  for example). Nil Einne (talk) 11:21, 6 February 2008 (UTC)
 * Aw come on, you know the unsigned contributor above is right on target (and possibly equally serious). Red on maps is "traditionally the color used for 'cause for concern' or 'danger' or something similar". Why just this morning the news showed a map depicting the incoming warm air giving us record-breaking high temps today -- obviously chosen because of the "cause for concern" that we are in "danger" from global warming.
 * Our civic association just put up a map showing our boundries. The civic association to our North is dangerous to us, so they're shown in red. We're all lovey-dovey with our nice, cool neighboring association to the South, shown in blue.
 * I work in a hospital. Nothing more comforting to a family than hearing "Code Blue", I assure you.
 * There's very real danger to me, if I don't find a nice card for my partner before February 14. That's why red is associated with Valentine's Day. And the "Red Menace". And Christmas. E. coli might lurk in that red meat. Election results in the U.S. typically show the dangerous, male Republicans in red and the nice, cool, female Democrats in blue. It's. All. So. Clear.
 * That said, given the widespread association of pink=girl/blue=boy, using red=boy/blue=girl is somewhat counterintuitive, IMO. - Mdsummermsw (talk) 13:55, 6 February 2008 (UTC)
 * That said, given the widespread association of pink=girl/blue=boy, using red=boy/blue=girl is somewhat counterintuitive, IMO. - Mdsummermsw (talk) 13:55, 6 February 2008 (UTC)

 * The pink=girl / blue=boy scheme apparently only dates back to the early 20th century (at most), while there's an alternative old "alchemical" color scheme of (male = planet Mars = metal iron = rust = red) vs. (female = planet Venus = metal copper = patina = green) which dates back to the Renaissance or late middle ages -- though probably only a few people knew about it at any one time... AnonMoos (talk) 14:08, 6 February 2008 (UTC)
 * As soon as wikipedia has a large number of 19th century readers, that will be relevant. At present, however, we have solid evidence that large numbers of people associate pink with girls and blue with boys and the reasonable assumption that many people will be at least momentarily confused by the current color scheme.
 * We could have an argument that weather maps have their colors wrong: blue hot is hotter than red hot. Maybe they should use black for cold and white/yellow/orange/red/blue/whatever for hot. Realistically, though, we know that many people associate blue with cold and red with hot::pink (light red) with girls and blue with boys.
 * The possibly Western-ness of this association is moot unless we have reason to believe the opposite would (not "gee, maybe, could") be confusing elsewhere.
 * That people 65, 100, 9000 or however many years ago might have viewed this differently is moot. We do not know this to be the case today.
 * Reversing the current colors would clear up a known confusion.
 * Mdsummermsw (talk) 14:24, 6 February 2008 (UTC)

 * Actually, that would be 15th-19th century readers, including a few 20th- and 21st-century occultists and/or historically-minded types... [[Image:SFriendly.gif|20px]] -- AnonMoos (talk) 14:46, 6 February 2008 (UTC)
 * Clearly, the 15th-19th century readers are unlikely to unite with the occultists and/or historically-minded types to overrule us. We are wikipedia. Resistance is futile. Oh, and they're dead, too. - Mdsummermsw (talk) 15:22, 6 February 2008 (UTC)

First map is incorrectly colored
I believe that the first map on this page is incorrectly colored. If you look at the table on the page for the countries of Pakistan, Syria, Bangladesh, and Libya you'll see that they have a higher male/female sex ratio (>1.0). But on the map all four countries are colored blue, indicating they have lower male/female ratio (<1.0).

There may be other countries that have this problem but I only noticed some of the larger ones because they stand out. Can someone please update/correct the main map for this page? Ender qa 15:09, 12 September 2007 (UTC)

"cultural preferences"
I commented out: "Still more extreme ratios documented in some populations should be attributed rather more to cultural preferences, than to biological variation in the propensity to bear boys or girls."

What? Was the documentation skewed by preferences? Do preferences impact gender at conception? Did preferences alter reported gender? I just don't understand what it's saying. Mdbrownmsw 16:19, 19 September 2007 (UTC)

 * md brown your an idiot. He's talking about people who choose if they have a boy or girl. Take japan for example, all of the Japanese hate females so they either abort them or give them up for adoption. There offspring in turn may be adopted to another country thus changing the sex ratio not biologically but culturally. —Preceding unsigned comment added by 71.252.30.254 (talk) 21:23, 30 September 2007 (UTC)

 * Thank you for your input. However, the section I commented out discussed variation in sex ratio at brith "in the absence of sex selection practices". This would exclude effects from gender-specific abortion and adoption.
 * I'll assume that you were being ironic when you wrote "your [sic] an idiot", then discussed what they do with "(t)here [sic] offspring" in your example, Japan. However, this is completely at odds with the well-sourced data in the very article you're commenting on.
 * I am sorry that I cannot relate this to you more directly, but you seem to have forgotten to log on before you left your comment, which you also forgot to sign.
 * Mdbrownmsw 18:46, 1 October 2007 (UTC)
 * I am sorry that I cannot relate this to you more directly, but you seem to have forgotten to log on before you left your comment, which you also forgot to sign.
 * Mdbrownmsw 18:46, 1 October 2007 (UTC)

There seem to be no respective article-discussion sections. This is to draw attention to the fact that paragraph 2 of Genetics doesn't make any sense. The entire section seems to have been written by a feminist or at least with a bias. It also continually cites elephants for some reason, despite that last time I checked we were not elephants. Indeed the elephant examples seem to illustrate directly the opposite trend from humans. Also when it cites human sexual availability (male/female) it assumes that they are the same. I think any male, let alone any scientist, will tell you that this couldn't be more inaccurate. Generally the only harems in modern society serve females, and there has never been such inequality. 14 December 2007 —Preceding unsigned comment added by 87.254.81.209 (talk) 21:00, 14 December 2007 (UTC)

105:100
The article cites a human sex ratio of 105 then gives an evolutionary argument that the sex ratio must be 1:1. What's up with that? How can the ratio in fact be 105 (NB. that's 105 without counting sex-selective abortion). Emmazunz84 (talk) 21:50, 10 March 2008 (UTC)

 * It says "approximately equal" and 105/100 is in fact approximately equal to 1... However, the 105:100 ratio at birth seems to be adjusted so that the number of males and females of breeding age will be more closely equal than if there were a 100:100 ratio at birth. AnonMoos (talk) 23:12, 10 March 2008 (UTC)

Social unrest
I have just removed the following:"Gender imbalance may result in the threat of social unrest, especially in the case of an excess of young males unable to find a spouse."

This was removed previously for lacking a cite. Now it has a partial cite. Is that a book, newspaper article, undergrad essay, chat room posting, comic book, ... or what? - Mdsummermsw (talk) 16:27, 14 March 2008 (UTC)

 * It's a book which received rather extensive media coverage in 2004 (as you could have easily discovered in about three seconds of Google searching). AnonMoos (talk) 18:17, 14 March 2008 (UTC)

 * Your citation is still incomplete. "All citation techniques require detailed full citations to be provided for each source used....Full citations for books typically include: the name of the author, the title of the book or article, the date of publication, and page numbers." WP:CITE - Mdsummermsw (talk) 19:32, 14 March 2008 (UTC)

 * Unfortunately, my various skills and talents do not really extend to being able to easily coerce bibliographic information into a pre-specified rigid narrow format. If you consider it extremely important that the relevant bibliographical information be coerced into a pre-specified precise and exact technical format, then you should be able to do so based on information which is findable in about three seconds of Google searching. AnonMoos (talk) 20:12, 14 March 2008 (UTC)

 * The page numbers for your cite are not available via google. To be clear here, you are asking me to say where you found it. - Mdsummermsw (talk) 20:32, 14 March 2008 (UTC)

 * Whatever, Dude -- the sentence in question is a reasonable summary of the main thesis of the whole entire book (as you could have rather easily ascertained with about three seconds of Google searching. If you want a page reference, it would be "passim".  I fail to see what all this flailing around on your part has accomplished or was intended to accomplish. AnonMoos (talk) 21:36, 14 March 2008 (UTC)

New article: human sex ratio
If nobody has any strenuous objections, I will move some of this material in this article to human sex ratio which should then be a less confusing subarticle.

Please don't panic. All species where there are sexes have sex ratios, not only humans (anthropology). To concentrate on humans is anthropocentric, and I would say that anthropocentricism is not NPOV. There is a lot of very interesting theoretical and experimental work on sex ratios in non-human species. --I am not a dog (talk) 13:54, 11 April 2008 (UTC)

 * OK I have made human sex ratio. The next stage will be to remove information from this article, so it can be about sex ratios generally.  That no doubt will cause some upset, so I shall leave it for tomorrow. I am not a dog (talk) 21:26, 14 April 2008 (UTC)

 * And now I have removed material from here (don't say I didn't warn you). It is still a bit disjointed but hopefully it is less so and thus can be tidied. I am not a dog (talk) 17:03, 16 April 2008 (UTC)

Hermaphrodites
Nothing is said in the article about hermaphrodites. Which sex do they belong to? What percentage of society do they constitute?66.65.129.159 (talk) 21:50, 29 August 2008 (UTC)
 * This brings up the question of how sex ratios are determined. Is it based on a visual examination of genitalia or on a DNA/SRS test? Pendragon39 (talk) 17:37, 4 January 2009 (UTC)

 * It's presumably determined by birth registration records. I strongly doubt that the number of visbly-intersexed people at birth is enough to significantly affect overall sex-ratio statistics. AnonMoos (talk) 20:04, 4 January 2009 (UTC)

Vandalism??
This article is clearly wrong about the at birth sex ratio of 210 girls to 100 boys given that that would mean that pretty soon there will be double the number of women as men in the world or that most girls die very quickly after birth. I checked its reputed source the cia world fact book: https://www.cia.gov/library/publications/the-world-factbook/fields/2018.html and it clearly does not say that. I could not find where it has global statistics on sex ratio but given that it lists most countries as having something like a ration of 1.05 male births to female births I do not see how a ration of 210 to 100 in the opposite direction globally could be possible. I have never edited wikipedia before and do not know where to find the actual global statistic so I am not going to change it but clearly someone with the proper information should or it should be deleted. It is clearly some form of vandalism or a huge typo. — Preceding unsigned comment added by 76.171.97.117 (talk) 05:35, 11 December 2012 (UTC)

Never mind it was just recent vandalism and i reverted the numbers back to what they were before. — Preceding unsigned comment added by 76.171.97.117 (talk) 06:11, 11 December 2012 (UTC)

Types of Sex Ratio
Anyone know whats up with this block? I tried editing it so that it appears as whoever wrote it intended, but it appears that there is a lot of german in there as well. I'm not sure what to do with it so i didn't edit it, but would urge someone who knows more to do so. — Preceding unsigned comment added by 174.112.234.80 (talk) 19:10, 15 September 2013 (UTC)

Geodakyan's evolutionary theory of sex
Help required with Geodakyan's evolutionary theory of sex: the article of apparently fringe theory is based almost exclusively on primary sources and edited by a people with strong connection to the subject. Staszek Lem (talk) 17:12, 13 October 2016 (UTC)

The absent of South Sudan
All maps with the color black representing water are missing South Sudan's independency from Sudan, and shows it as a part of Sudan. — Preceding unsigned comment added by מנחם ברמן (talk • contribs) 16:05, 4 February 2017 (UTC)

Sex ratio
What are the importance of sex ratio 154.72.160.84 (talk) 21:40, 23 March 2024 (UTC)
 * How many guys to every girl, or vice versa. AnonMoos (talk) 22:23, 23 March 2024 (UTC)
 * That's its meaning, the definition of the phrase. About its importance: sex ratios may be totally unimportant to some people, interesting or even paramount to others. Cultures where boys are preferred to girls obviously show a preference for sex ratios greater than 1 in (at least) their family, while (as mentioned in the text) farmers prefer the sex ratio of their livestock to be low, but not too low: you need cows to produce calfs and milk, hens to lay eggs, while one bull can service many cows, one rooster many hens: IOW, you need at least one full male, and as may females as you can get and feed. Anthropologists and biologists, OTOH, would probably become worried if the sex ratio wandered far enough from 1.0 in all or part of their field of study to make reproduction problematic (i.e., in mathematical terms, if the absolute value of its logarithm became too high): obviously, a sex ratio tending toward zero (females only, log r → –∞) or toward infinity (males only, log r → +∞) would make it extremely difficult bordering on impossible to find a sex partner, and I'm not so much talking about sex-for-pleasure here, as about sex-for-offspring. — Tonymec (talk) 21:48, 4 April 2024 (UTC)

title: Talk:Sex ratio


text:
The Practice

The Practice is an American legal drama television series created by David E. Kelley centering on partners and associates at a Boston law firm. The show ran for eight seasons on ABC, from March 4, 1997, to May 16, 2004. It won an Emmy in 1998 and 1999 for Outstanding Drama Series, and spawned the spin-off series Boston Legal, which ran for five more seasons (from 2004 to 2008).

Conflict between legal ethics and personal morality was a recurring theme with light comedy being occasionally present. Kelley claimed that the show was intended to be something of a rebuttal to L.A. Law and its romanticized treatment of the American legal system and legal proceedings.

Overview
In season 1, Robert Donnell and Associates features Bobby Donnell as the sole senior partner in a firm that he started a decade prior with his receptionist Rebecca Washington. Ellenor Frutt, Eugene Young and Lindsay Dole are his associates. Jimmy Berluti is hired as an associate after losing his job in finance in an attempt to help Donnell and Associates with a loan.

In season 2, Eugene, Lindsay and Ellenor become partners after Lindsay insists on equity. Robert Donnell and Associates becomes Donnell, Young, Dole and Frutt. Helen Gamble, an assistant district attorney, becomes regularly entangled in the cases and personal lives of the employees of the firm. She is a personal friend of Lindsay and viewers learn several episodes into the season that Bobby and Lindsay have had an on-again/off-again secret affair. Her romantic relationship with Bobby ends after a high-profile murder case pits them against one another.

In season 3, Rebecca Washington, who had been attending law school in secret, becomes an associate after passing the bar exam. Lucy Hatcher is then hired as the new receptionist.

In season 4, Assistant District Attorney Richard Bay, like Helen, becomes a frequent ally and opponent of Donnell, Young, Dole and Frutt.

In season 5, Lucy becomes a rape crisis counselor in addition to her job as the firm's receptionist. Richard Bay is later assassinated after refusing to throw a murder trial.

In season 6, Assistant District Attorney Alan Lowe becomes an antagonist of the firm for a short period of time.

In season 7, Lindsay leaves Donnell, Young, Dole and Frutt to start a new law firm with Claire Wyatt. To fill the void left by Lindsay, Jamie Stringer is hired as an associate. Bobby later leaves the firm.

In season 8, Donnell, Young, Dole and Frutt has been renamed to Young, Frutt and Berluti. Eugene has taken Bobby's place as a senior partner. Lucy has left the firm to become a full-time rape crisis counselor. Rebecca has also left the firm for unknown reasons. Helen is no longer present at the firm's cases. Tara Wilson is hired as a paralegal, and Alan Shore becomes an associate. After firing Alan and Tara – as well as being sued by the former – Young, Frutt and Berluti dissolve. Eugene then becomes a judge. Ellenor focuses her attention on motherhood. Jimmy and Jamie begin a new firm. Alan and Tara are hired by another firm, Crane, Poole and Schmidt and their story is continued in Boston Legal.

Main cast

 * Dylan McDermott as Bobby Donnell (seasons 1–7; guest season 8), the senior partner of the firm who struggles with his conscience and the idea of being a lawyer.
 * LisaGay Hamilton as Rebecca Washington (seasons 1–7), the firm's first receptionist and paralegal. She later passed the bar exam and became an associate.
 * Steve Harris as Eugene Young, the second highest-ranking partner at the firm and later senior partner who is more strongly devoted to the letter of the law and legal ethics than his colleagues. Later he even becomes a judge.
 * Camryn Manheim as Ellenor Frutt, an associate and later senior partner at the firm who brought in various nefarious clients. A recurring gag on the show was that the men she dated often turned out to be murderers.
 * Kelli Williams as Lindsay Dole (seasons 1–7), an associate at the firm and, later, wife of Bobby Donnell.
 * Michael Badalucco as Jimmy Berluti, an associate and later partner at the firm from a working-class background. Jimmy often struggles with his conscience, loneliness, feelings of inadequacy, and a gambling addiction.
 * Lara Flynn Boyle as Helen Gamble (seasons 2–7), an Assistant District Attorney and friend of the firm partners who was relentless in her attempts to prosecute those who do wrong.
 * Marla Sokoloff as Lucy Hatcher (seasons 3–7; recurring season 8), the firm's wise-cracking, nosy receptionist who was hired after Rebecca became an attorney. She later became a part-time counselor for rape victims in addition to her job as a receptionist.
 * Jason Kravits as Richard Bay (season 5; recurring season 4), a diminutive, hard-nosed Assistant District Attorney who believed in the guilt of all those he prosecuted.
 * Ron Livingston as Alan Lowe (season 6), an Assistant District Attorney who replaced Richard Bay.
 * Jessica Capshaw as Jamie Stringer (seasons 7–8), a high-strung, promiscuous Harvard Law School graduate and associate at the firm.
 * Chyler Leigh as Claire Wyatt (season 7), Lindsay's associate at her new practice.
 * Rhona Mitra as Tara Wilson (season 8), a paralegal and law student. She would later appear in Boston Legal as an attorney.
 * James Spader as Alan Shore (season 8), an amoral associate and an old friend of Ellenor. He would later appear in Boston Legal.

Recurring cast

 * Ray Abruzzo as Detective Mike McGuire (45 episodes)
 * Holland Taylor as Judge Roberta Kittleson (29 episodes)
 * Linda Hunt as Judge Zoey Hiller (23 episodes)
 * Bill Smitrovich as A.D.A. Kenneth Walsh (22 episodes)
 * Richard McGonagle as Judge Patrick Wilcox (16 episodes)
 * James Pickens, Jr. as Detective Mike McKrew (15 episodes)
 * Frank Birney as Judge Warren West (14 episodes)
 * Herb Mitchell as Judge Rodney White (12 episodes)
 * Michael Monks as George Vogelman (11 episodes)
 * Edward Herrmann as Anderson Pearson (10 episodes)
 * Anna Gunn as A.D.A. Jean Ward (10 episodes)
 * Kate Burton as A.D.A. Susan Alexander (9 episodes)
 * Bruce Davison as Scott Wallace (9 episodes)
 * Paul Dooley as Judge Philip Swackheim (8 episodes)
 * Lynn Hamilton as Judge Fulton (7 episodes)
 * Billee Thomas as Kendall Young (7 episodes)
 * Susan Blommaert as Judge Rudy Fox (7 episodes)
 * Steven Gilborn as A.D.A. Gavin Bullock (6 episodes)
 * Vince Colosimo as Matthew Billings (6 episodes)

Notable guest stars
The series holds the Emmy Awards record for most wins in the Guest Actor and Actress categories for a single series, as well as most nominations in those categories. Emmys went to John Larroquette, Edward Herrmann, James Whitmore, Beah Richards, Michael Emerson, Charles S. Dutton, Alfre Woodard, Sharon Stone and William Shatner. In addition, Tony Danza, Paul Dooley, Henry Winkler, Marlee Matlin, René Auberjonois and Betty White were nominated but did not win. Larroquette, who won for his guest appearance during the second season, was nominated again for an episode from the sixth season, but did not win. The series won the Outstanding Guest Actor in a Drama Series for five consecutive years (from 1998 to 2002).

 * Gabrielle Anwar as Katie Defoe
 * Ed Asner as Judge Matlin Pratt / Judge Marcus Winnaker
 * René Auberjonois as Judge Mantz
 * Dylan Baker as Keith Ellison
 * Kathy Baker as Evelyn Mayfield
 * Lake Bell as Sally Heep
 * Gil Bellows as Billy Thomas
 * Tempestt Bledsoe as Roberta Baylor
 * Andre Braugher as Ben Gideon
 * Christian Clemenson as Barry Wall
 * Jon Cryer as Terry Pender
 * Tony Danza as Tommy Silva
 * Viola Davis as Aisha Crenshaw
 * Bruce Davison as Scott Wallace
 * Rebecca De Mornay as Hannah Rose
 * Patrick Dempsey as Paul Stewart
 * Charles Durning as Stephen Donnell
 * Charles S. Dutton as Leonard Marshall
 * Aunjanue Ellis as Sharon Young
 * Michael Emerson as William Hinks
 * Giancarlo Esposito as Ray McMurphy
 * Calista Flockhart as Ally McBeal
 * Billy Gardell as Manny Quinn
 * Gina Gershon as Glenn Hall
 * Anthony Heald as Wallace Cooper/Scott Guber
 * Doug Hutchison as Jackie Cahill
 * John Larroquette as Joey Heric
 * Virginia Madsen as Marsha Ellison
 * Marlee Matlin as Sally Berg
 * Chi McBride as Steven Harper
 * Thomas McCarthy as Kevin Riley
 * Paul McCrane as Martin Parks
 * John C. McGinley as Leonard Good
 * Leslie Moonves as Himself
 * Chris O'Donnell as Brad Stanfield
 * Vincent Pastore as Lenny Pescatore
 * Teri Polo as Sarah Barker
 * CCH Pounder as Helene Washington
 * Kim Raver as Victoria Keenan
 * Christopher Reeve as Kevin Beally
 * Beah Richards as Gertrude Turner
 * Ernie Sabella as Harland Bassett
 * William Shatner as Denny Crane
 * Sharon Stone as Sheila Carlisle
 * Rider Strong as Gary Armbrust
 * Ralph Waite as Walter Josephson
 * Betty White as Catherine Piper
 * James Whitmore as Raymond Oz
 * Henry Winkler as Henry Olson
 * Alfre Woodard as Denise Freeman
 * D. B. Woodside as Aaron Wilton

Budget reduction and major revamp
By the end of the seventh season, faced with sagging ratings, ABC conditioned the show's renewal on a drastic budget reduction. As a result, Dylan McDermott, Kelli Williams, Lara Flynn Boyle, Chyler Leigh, Marla Sokoloff, and LisaGay Hamilton were fired as regulars. McDermott and Sokoloff reappeared as special guest stars and a recurring character respectively in the eighth season. The addition of James Spader and Rhona Mitra to the cast somewhat revived the ratings as Spader went on to win an Emmy for his appearance. However, ABC announced that The Practice would not return for a ninth season on March 11, 2004. Instead, Kelley would create a new spin-off series called Boston Legal which starred Spader, Mitra, Lake Bell and William Shatner.

Episodes
The Practice had 8 seasons and a total of 168 episodes.

Crossovers

 * "Axe Murderer" (S02E26) – The lawyers of Robert Donnell and Associates work with the lawyers of Cage & Fish on a case in which a woman is accused of killing a wealthy client who may have been Lizzie Borden in a past life. The case had begun on Ally McBeal: "The Inmates" (S01E20).
 * "The Day After" (S05E14) – Ellenor Frutt and Jimmy Berlutti are hired to represent Coach Riley, who's been fired from Winslow High for withholding information about Milton Buttle's affair. The hearing happens on Boston Public: "Chapter Thirteen" (S01E13).
 * "Gideon's Crossover" (S05E16) – When Ellenor Frutt has trouble with her pregnancy, Dr. Ben Gideon helps out in Gideon's Crossing: "Flashpoint" (S01E17).

Additionally, Bobby Donnell (Dylan McDermott) appears in the Ally McBeal season 1 finale "These Are the Days", while Lara Flynn Boyle and Michael Badalucco each make cameos in "Making Spirits Bright" and "I Know Him by Heart".

Lara Flynn Boyle had an uncredited guest appearance as a rebuttal witness, opposite of guest star Heather Locklear's character in the season 5 episode "Tom Dooley".

Home media
The Practice, Volume 1, was released as a four-disc DVD set in North America on June 12, 2007. The set includes all six episodes of season 1 and the first seven episodes of season 2. It also includes a featurette, "Setting Up The Practice". The set was also released in Region 4 on June 6, 2007 and in Region 2 on June 29, 2008.

On January 3, 2014, it was announced that Shout! Factory had acquired the rights to the series in Region 1 and would release the final season on DVD on April 15, 2014.

In 2012, Medium Rare Entertainment acquired the rights to the series in Region 2 and released the first and second seasons on DVD in the United Kingdom on February 27, 2012.

In 2014, StudioCanal released the first and second seasons over three volumes in Germany with German and English audio. The third, fourth, and eighth seasons have also been released in 2016 with plans to release the fifth and sixth at a later date.

Volume 1 was released in Italy and Greece on July 1, 2007.

In March 2019, all seasons and episodes of The Practice were released on the streaming service Amazon Prime Video. By 2021, seasons 1–8 became available on the streaming service Hulu.

U.S. television viewership
Viewer numbers per season of The Practice on ABC.

Note: Each US network television season starts in late September and ends in late May, which coincides with the completion of May sweeps. The first two seasons include the household rating. Seasons 4 and 5 reached the top 10 rankings.

The exposure from its January 30, 2000, post-Super Bowl episode (attracting 23.8 million viewers) plus their weekly lead-in from early 2000 to mid-2001, the then mega-hit Who Wants to Be a Millionaire, helped the series reach its ratings peak.

 * Series High: 15.4 rating/23.8 million viewers
 * lead in: Super Bowl: Post Game — 25.6 rating
 * Series Low: 4.9 rating/7.3 million
 * Series Debut: 11.3 rating/16.1 million viewers
 * Series Finale: 7.5 rating/10.9 million viewers

title: The Practice


text:
Liquid-propellant rocket

[[File:Liquid-Fuel Rocket Diagram.svg|thumb|300px|A simplified diagram of a liquid-propellant rocket.1. Liquid rocket fuel.

2. Oxidizer.

3. Pumps carry the fuel and oxidizer.

4. The combustion chamber mixes and burns the two liquids.

5. Combustion product gasses enter the nozzle through a throat.

6. Exhaust exits the rocket.]] A liquid-propellant rocket or liquid rocket utilizes a rocket engine burning liquid propellants. (Alternate approaches use gaseous or solid propellants.) Liquids are desirable propellants because they have reasonably high density and their combustion products have high specific impulse (Isp). This allows the volume of the propellant tanks to be relatively low.

Types
Liquid rockets can be monopropellant rockets using a single type of propellant, or bipropellant rockets using two types of propellant. Tripropellant rockets using three types of propellant are rare. Liquid oxidizer propellants are also used in hybrid rockets, with some of the advantages of a solid rocket. Bipropellant liquid rockets use a liquid fuel such as liquid hydrogen or RP-1, and a liquid oxidizer such as liquid oxygen. The engine may be a cryogenic rocket engine, where the fuel and oxidizer, such as hydrogen and oxygen, are gases which have been liquefied at very low temperatures.

Most designs of liquid rocket engines are throttleable for variable thrust operation. Some allow control of the propellant mixture ratio (ratio at which oxidizer and fuel are mixed). Some can be shut down and, with a suitable ignition system or self-igniting propellant, restarted.

Hybrid rockets apply a liquid or gaseous oxidizer to a solid fuel.

Advantages and disadvantages
The use of liquid propellants has a number of advantages:
 * A liquid rocket engine can be tested prior to use, whereas for a solid rocket motor a rigorous quality management must be applied during manufacturing to ensure high reliability.
 * Liquid systems enable higher specific impulse than solids and hybrid rocket motors and can provide very high tankage efficiency.
 * A Liquid rocket engine can also usually be reused for several flights, as in the Space Shuttle and Falcon 9 series rockets, although reuse of solid rocket motors was also effectively demonstrated during the Shuttle program.
 * Liquid rocket engines can swivel throughout flight. Swiveling allows the rocket engine to be pointed in different directions, which allows for finer-tuned control over the trajectory of the rocket.
 * The flow of propellant into the combustion chamber can be throttled, which allows for control over the magnitude of the thrust throughout the flight. This enables real-time error correction during the flight along with efficiency gains.
 * Shutdown and restart capabilities allow for multiple burn cycles throughout a flight.
 * In the case of an emergency, liquid propelled rockets can be shutdown in a controlled manner, which provides an extra level of safety and mission abort capability.

Use of liquid propellants can also be associated with a number of issues:

 * Because the propellant is a very large proportion of the mass of the vehicle, the center of mass shifts significantly rearward as the propellant is used; one will typically lose control of the vehicle if its center mass gets too close to the center of drag/pressure.
 * When operated within an atmosphere, pressurization of the typically very thin-walled propellant tanks must guarantee positive gauge pressure at all times to avoid catastrophic collapse of the tank.
 * Liquid propellants are subject to slosh, which has frequently led to loss of control of the vehicle. This can be controlled with slosh baffles in the tanks as well as judicious control laws in the guidance system.
 * They can suffer from pogo oscillation where the rocket suffers from uncommanded cycles of acceleration.
 * Liquid propellants often need ullage motors in zero-gravity or during staging to avoid sucking gas into engines at start up. They are also subject to vortexing within the tank, particularly towards the end of the burn, which can also result in gas being sucked into the engine or pump.
 * Liquid propellants can leak, especially hydrogen, possibly leading to the formation of an explosive mixture.
 * Turbopumps to pump liquid propellants are complex to design, and can suffer serious failure modes, such as overspeeding if they run dry or shedding fragments at high speed if metal particles from the manufacturing process enter the pump.
 * Cryogenic propellants, such as liquid oxygen, freeze atmospheric water vapor into ice. This can damage or block seals and valves and can cause leaks and other failures. Avoiding this problem often requires lengthy chilldown procedures which attempt to remove as much of the vapor from the system as possible. Ice can also form on the outside of the tank, and later fall and damage the vehicle. External foam insulation can cause issues as shown by the Space Shuttle Columbia disaster. Non-cryogenic propellants do not cause such problems.
 * Non-storable liquid rockets require considerable preparation immediately before launch. This makes them less practical than solid rockets for most weapon systems.

Principle of operation
Liquid rocket engines have tankage and pipes to store and transfer propellant, an injector system and one or more combustion chambers with associated nozzles.

Typical liquid propellants have densities roughly similar to water, approximately 0.7–1.4g/cm3. An exception is liquid hydrogen which has a much lower density, while requiring only relatively modest pressure to prevent vaporization. The density and low pressure of liquid propellants permit lightweight tankage: approximately 1% of the contents for dense propellants and around 10% for liquid hydrogen. The increased tank mass is due to liquid hydrogen's low density and the mass of the required insulation.

For injection into the combustion chamber, the propellant pressure at the injectors needs to be greater than the chamber pressure. This is often achieved with a pump. Suitable pumps usually use centrifugal turbopumps due to their high power and light weight, although reciprocating pumps have been employed in the past. Turbopumps are usually lightweight and can give excellent performance; with an on-Earth weight well under 1% of the thrust. Indeed, overall thrust to weight ratios including a turbopump have been as high as 155:1 with the SpaceX Merlin 1D rocket engine and up to 180:1 with the vacuum version. Instead of a pump, some designs use a tank of a high-pressure inert gas such as helium to pressurize the propellants. These rockets often provide lower delta-v because the mass of the pressurant tankage reduces performance. In some designs for high altitude or vacuum use the tankage mass can be acceptable.

The major components of a rocket engine are therefore the combustion chamber (thrust chamber), pyrotechnic igniter, propellant feed system, valves, regulators, propellant tanks and the rocket engine nozzle. For feeding propellants to the combustion chamber, liquid-propellant engines are either pressure-fed or pump-fed, with pump-fed engines working in a variety of engine cycles.

Pressurization
Liquid propellants are often pumped into the combustion chamber with a lightweight centrifugal turbopump. Recently some aerospace companies have used electric pumps with batteries for this. In simpler small engines an inert gas stored in a tank at a high pressure is sometimes used instead of pumps to force propellants into the combustion chamber. These engines may have a higher mass ratio, but are usually more reliable, and are therefore used widely in satellites for orbit maintenance.

Propellants
Thousands of combinations of fuels and oxidizers have been tried over the years. Some of the more common and practical ones are:

Cryogenic

 * Liquid oxygen (LOX, O2) and liquid hydrogen (LH$2$, H2) – Space Shuttle main engines, Space Launch System core stage, Ariane 5 main stage and the Ariane 5 ECA second stage, the BE-3 of Blue Origin's New Shepard, the first and second stage of the Delta IV, the upper stages of the Ares I, Saturn V's second and third stages, Saturn IB, and Saturn I as well as Centaur rocket stage, the upper stages of the Long March 3, Long March 5, Long March 8, the first stage and second stage of the H-II, H-IIA, H-IIB, and the upper stage of the GSLV Mk-II and GSLV Mk-III. The main advantages of this mixture are a clean burn (water vapor is the only combustion product) and high performance.
 * Liquid oxygen (LOX) and liquid methane (CH4, liquefied natural gas, LNG) – the Raptor (SpaceX) and BE-4 (Blue Origin) engines. (See also Propulsion Cryogenics & Advanced Development project of NASA, and Project Morpheus.)

One of the most efficient mixtures, oxygen and hydrogen, suffers from the extremely low temperatures required for storing liquid hydrogen (around 20 K) and very low fuel density (70 kg/m3, compared to RP-1 at 820 kg/m3), necessitating large tanks that must also be lightweight and insulating. Lightweight foam insulation on the Space Shuttle external tank led to the 's destruction, as a piece broke loose, damaged its wing and caused it to break up on atmospheric reentry.

Liquid methane/LNG has several advantages over LH$2$. Its performance (max. specific impulse) is lower than that of LH$2$ but higher than that of RP1 (kerosene) and solid propellants, and its higher density, similarly to other hydrocarbon fuels, provides higher thrust to volume ratios than LH$2$, although its density is not as high as that of RP1. This makes it specially attractive for reusable launch systems because higher density allows for smaller motors, propellant tanks and associated systems. LNG also burns with less or no soot (less or no coking) than RP1, which eases reusability when compared with it, and LNG and RP1 burn cooler than LH$2$ so LNG and RP1 do not deform the interior structures of the engine as much. This means that engines that burn LNG can be reused more than those that burn RP1 or LH$2$. Unlike engines that burn LH$2$, both RP1 and LNG engines can be designed with a shared shaft with a single turbine and two turbopumps, one each for LOX and LNG/RP1. In space, LNG does not need heaters to keep it liquid, unlike RP1. LNG is less expensive, being readily available in large quantities. It can be stored for more prolonged periods of time, and is less explosive than LH$2$.

Semi-cryogenic

 * Liquid oxygen (LOX) and RP-1 (kerosene) – Saturn V's first stage, Zenit rocket, R-7-derived vehicles including Soyuz, Delta, Saturn I, and Saturn IB first stages, Titan I and Atlas rockets, Falcon 1 and Falcon 9, Long March 5, Long March 6, Long March 7 and Long March 8 first stages.
 * Liquid oxygen (LOX) and alcohol (ethanol, C2H5OH) – early liquid rockets, like German (World War II) A4, aka V-2, and Redstone
 * Liquid oxygen (LOX) and gasoline – Robert Goddard's first liquid rocket
 * Liquid oxygen (LOX) and carbon monoxide (CO) – proposed for a Mars hopper vehicle (with a specific impulse of approximately 250s), principally because carbon monoxide and oxygen can be straightforwardly produced by Zirconia electrolysis from the Martian atmosphere without requiring use of any of the Martian water resources to obtain Hydrogen.

Non-cryogenic/storable/hypergolic

Many non-cryogenic bipropellants are hypergolic (self igniting).
 * T-Stoff (80% hydrogen peroxide, H2O2 as the oxidizer) and C-Stoff (methanol, CH3OH, and hydrazine hydrate, N2H4*n(H2O) as the fuel) – used for the Hellmuth-Walter-Werke HWK 109-509A, -B and -C engine family used on the Messerschmitt Me 163B Komet, an operational rocket fighter plane of World War II, and Ba 349 Natter crewed VTO interceptor prototypes.
 * Nitric acid (HNO3) and kerosene – Soviet BI-1 and MiG I-270 rocket fighter prototypes, Scud-A, aka SS-1 SRBM
 * Inhibited red fuming nitric acid (IRFNA, HNO3 + N2O4) and unsymmetric dimethyl hydrazine (UDMH, (CH3)2N2H2) – Soviet Scud-C, aka SS-1-c,-d,-e
 * Nitric acid 73% with dinitrogen tetroxide 27% (AK27) and kerosene/gasoline mixture (TM-185) – various Russian (USSR) cold-war ballistic missiles (R-12, Scud-B,-D), Iran: Shahab-5, North Korea: Taepodong-2
 * High-test peroxide (H2O2) and kerosene – UK (1970s) Black Arrow, USA Development (or study): BA-3200
 * Hydrazine (N2H4) and red fuming nitric acid – MIM-3 Nike Ajax Antiaircraft Rocket
 * Unsymmetric dimethylhydrazine (UDMH) and dinitrogen tetroxide (N2O4) – Proton, Rokot, Long March 2 (used to launch Shenzhou crew vehicles.)
 * LGM-25C Titan II Test Launch.jpgine 50 (50% UDMH, 50% hydrazine) and dinitrogen tetroxide (N2O4) – Titans 2–4, Apollo lunar module, Apollo service module, interplanetary probes (Such as Voyager 1 and Voyager 2)
 * Monomethylhydrazine (MMH, (CH3)HN2H2) and dinitrogen tetroxide (N2O4) – Space Shuttle orbiter's orbital maneuvering system (OMS) engines and Reaction control system (RCS) thrusters. SpaceX's Draco and SuperDraco engines for the Dragon spacecraft.

For storable ICBMs and most spacecraft, including crewed vehicles, planetary probes, and satellites, storing cryogenic propellants over extended periods is unfeasible. Because of this, mixtures of hydrazine or its derivatives in combination with nitrogen oxides are generally used for such applications, but are toxic and carcinogenic. Consequently, to improve handling, some crew vehicles such as Dream Chaser and Space Ship Two plan to use hybrid rockets with non-toxic fuel and oxidizer combinations.

Injectors
The injector implementation in liquid rockets determines the percentage of the theoretical performance of the nozzle that can be achieved. A poor injector performance causes unburnt propellant to leave the engine, giving poor efficiency.

Additionally, injectors are also usually key in reducing thermal loads on the nozzle; by increasing the proportion of fuel around the edge of the chamber, this gives much lower temperatures on the walls of the nozzle.

Types of injectors
Injectors can be as simple as a number of small diameter holes arranged in carefully constructed patterns through which the fuel and oxidizer travel. The speed of the flow is determined by the square root of the pressure drop across the injectors, the shape of the hole and other details such as the density of the propellant.

The first injectors used on the V-2 created parallel jets of fuel and oxidizer which then combusted in the chamber. This gave quite poor efficiency.

Injectors today classically consist of a number of small holes which aim jets of fuel and oxidizer so that they collide at a point in space a short distance away from the injector plate. This helps to break the flow up into small droplets that burn more easily.

The main types of injectors are
 * Shower head
 * Self-impinging doublet
 * Cross-impinging triplet
 * Centripetal or swirling
 * Pintle

The pintle injector permits good mixture control of fuel and oxidizer over a wide range of flow rates. The pintle injector was used in the Apollo Lunar Module engines (Descent Propulsion System) and the Kestrel engine, it is currently used in the Merlin engine on Falcon 9 and Falcon Heavy rockets.

The RS-25 engine designed for the Space Shuttle uses a system of fluted posts, which use heated hydrogen from the preburner to vaporize the liquid oxygen flowing through the center of the posts and this improves the rate and stability of the combustion process; previous engines such as the F-1 used for the Apollo program had significant issues with oscillations that led to destruction of the engines, but this was not a problem in the RS-25 due to this design detail.

Valentin Glushko invented the centripetal injector in the early 1930s, and it has been almost universally used in Russian engines. Rotational motion is applied to the liquid (and sometimes the two propellants are mixed), then it is expelled through a small hole, where it forms a cone-shaped sheet that rapidly atomizes. Goddard's first liquid engine used a single impinging injector. German scientists in WWII experimented with impinging injectors on flat plates, used successfully in the Wasserfall missile.

Combustion stability
To avoid instabilities such as chugging, which is a relatively low speed oscillation, the engine must be designed with enough pressure drop across the injectors to render the flow largely independent of the chamber pressure. This pressure drop is normally achieved by using at least 20% of the chamber pressure across the injectors.

Nevertheless, particularly in larger engines, a high speed combustion oscillation is easily triggered, and these are not well understood. These high speed oscillations tend to disrupt the gas side boundary layer of the engine, and this can cause the cooling system to rapidly fail, destroying the engine. These kinds of oscillations are much more common on large engines, and plagued the development of the Saturn V, but were finally overcome.

Some combustion chambers, such as those of the RS-25 engine, use Helmholtz resonators as damping mechanisms to stop particular resonant frequencies from growing.

To prevent these issues the RS-25 injector design instead went to a lot of effort to vaporize the propellant prior to injection into the combustion chamber. Although many other features were used to ensure that instabilities could not occur, later research showed that these other features were unnecessary, and the gas phase combustion worked reliably.

Testing for stability often involves the use of small explosives. These are detonated within the chamber during operation, and causes an impulsive excitation. By examining the pressure trace of the chamber to determine how quickly the effects of the disturbance die away, it is possible to estimate the stability and redesign features of the chamber if required.

Engine cycles
For liquid-propellant rockets, four different ways of powering the injection of the propellant into the chamber are in common use.

Fuel and oxidizer must be pumped into the combustion chamber against the pressure of the hot gasses being burned, and engine power is limited by the rate at which propellant can be pumped into the combustion chamber. For atmospheric or launcher use, high pressure, and thus high power, engine cycles are desirable to minimize gravity drag. For orbital use, lower power cycles are usually fine.

 * Pressure-fed cycle: The propellants are forced in from pressurised (relatively heavy) tanks. The heavy tanks mean that a relatively low pressure is optimal, limiting engine power, but all the fuel is burned, allowing high efficiency. The pressurant used is frequently helium due to its lack of reactivity and low density. Examples: AJ-10, used in the Space Shuttle OMS, Apollo SPS, and the second stage of the Delta II.
 * Electric pump-fed: An electric motor, generally a brushless DC electric motor, drives the pumps. The electric motor is powered by a battery pack. It is relatively simple to implement and reduces the complexity of the turbomachinery design, but at the expense of the extra dry mass of the battery pack. Example engine is the Rutherford designed and used by Rocket Lab.
 * Gas-generator cycle: A small percentage of the propellants are burnt in a preburner to power a turbopump and then exhausted through a separate nozzle, or low down on the main one. This results in a reduction in efficiency since the exhaust contributes little or no thrust, but the pump turbines can be very large, allowing for high power engines. Examples: Saturn V's F-1 and J-2, Delta IV's RS-68, Ariane 5's HM7B, Falcon 9's Merlin.
 * Tap-off cycle: Takes hot gases from the main combustion chamber of the rocket engine and routes them through engine turbopump turbines to pump propellant, then is exhausted. Since not all propellant flows through the main combustion chamber, the tap-off cycle is considered an open-cycle engine. Examples include the J-2S and BE-3.
 * Expander cycle: Cryogenic fuel (hydrogen, or methane) is used to cool the walls of the combustion chamber and nozzle. Absorbed heat vaporizes and expands the fuel which is then used to drive the turbopumps before it enters the combustion chamber, allowing for high efficiency, or is bled overboard, allowing for higher power turbopumps. The limited heat available to vaporize the fuel constrains engine power. Examples: RL10 for Atlas V and Delta IV second stages (closed cycle), H-II's LE-5 (bleed cycle).
 * Staged combustion cycle: A fuel- or oxidizer-rich mixture is burned in a preburner and then drives turbopumps, and this high-pressure exhaust is fed directly into the main chamber where the remainder of the fuel or oxidizer undergoes combustion, permitting very high pressures and efficiency. Examples: SSME, RD-191, LE-7.
 * Full-flow staged combustion cycle: Fuel- and oxidizer-rich mixtures are burned in separate preburners and driving the turbopumps, then both high-pressure exhausts, one oxygen rich and the other fuel rich, are fed directly into the main chamber where they combine and combust, permitting very high pressures and high efficiency. Example: SpaceX Raptor.

Engine cycle tradeoffs
Selecting an engine cycle is one of the earlier steps to rocket engine design. A number of tradeoffs arise from this selection, some of which include:

Cooling
Injectors are commonly laid out so that a fuel-rich layer is created at the combustion chamber wall. This reduces the temperature there, and downstream to the throat and even into the nozzle and permits the combustion chamber to be run at higher pressure, which permits a higher expansion ratio nozzle to be used which gives a higher I$SP$ and better system performance. A liquid rocket engine often employs regenerative cooling, which uses the fuel or less commonly the oxidizer to cool the chamber and nozzle.

Ignition
Ignition can be performed in many ways, but perhaps more so with liquid propellants than other rockets a consistent and significant ignitions source is required; a delay of ignition (in some cases as small as a few tens of milliseconds) can cause overpressure of the chamber due to excess propellant. A hard start can even cause an engine to explode.

Generally, ignition systems try to apply flames across the injector surface, with a mass flow of approximately 1% of the full mass flow of the chamber.

Safety interlocks are sometimes used to ensure the presence of an ignition source before the main valves open; however reliability of the interlocks can in some cases be lower than the ignition system. Thus it depends on whether the system must fail safe, or whether overall mission success is more important. Interlocks are rarely used for upper, uncrewed stages where failure of the interlock would cause loss of mission, but are present on the RS-25 engine, to shut the engines down prior to liftoff of the Space Shuttle. In addition, detection of successful ignition of the igniter is surprisingly difficult, some systems use thin wires that are cut by the flames, pressure sensors have also seen some use.

Methods of ignition include pyrotechnic, electrical (spark or hot wire), and chemical. Hypergolic propellants have the advantage of self igniting, reliably and with less chance of hard starts. In the 1940s, the Russians began to start engines with hypergols, to then switch over to the primary propellants after ignition. This was also used on the American F-1 rocket engine on the Apollo program.

Ignition with a pyrophoric agent: Triethylaluminium ignites on contact with air and will ignite and/or decompose on contact with water, and with any other oxidizer—it is one of the few substances sufficiently pyrophoric to ignite on contact with cryogenic liquid oxygen. The enthalpy of combustion, ΔcH°, is -5105.70 ±. Its easy ignition makes it particularly desirable as a rocket engine ignitor. May be used in conjunction with triethylborane to create triethylaluminum-triethylborane, better known as TEA-TEB.

Russia–Soviet Union
The idea of a liquid-fueled rocket as understood in the modern context first appeared in 1903 in the book Exploration of the Universe with Rocket-Propelled Vehicles by the Russian rocket scientist Konstantin Tsiolkovsky. The magnitude of his contribution to astronautics is astounding, including the Tsiolkovsky rocket equation, multi-staged rockets, and using liquid oxygen and liquid hydrogen in liquid propellant rockets. Tsiolkovsky influenced later rocket scientists throughout Europe, like Wernher von Braun. Soviet search teams at Peenemünde found a German translation of a book by Tsiolkovsky of which "almost every page...was embellished by von Braun's comments and notes." Leading Soviet rocket-engine designer Valentin Glushko and rocket designer Sergey Korolev studied Tsiolkovsky's works as youths and both sought to turn Tsiolkovsky's theories into reality.

From 1929 to 1930 in Leningrad Glushko pursued rocket research at the Gas Dynamics Laboratory (GDL), where a new research section was set up for the study of liquid-propellant and electric rocket engines. This resulted in the creation of ORM (from "Experimental Rocket Motor" in Russian) engines ORM-1 to ORM-52. A total of 100 bench tests of liquid-propellant rockets were conducted using various types of fuel, both low and high-boiling and thrust up to 300 kg was achieved.

During this period in Moscow, Fredrich Tsander – a scientist and inventor – was designing and building liquid rocket engines which ran on compressed air and gasoline. Tsander investigated high-energy fuels including powdered metals mixed with gasoline. In September 1931 Tsander formed the Moscow based 'Group for the Study of Reactive Motion', better known by its Russian acronym "GIRD". In May 1932, Sergey Korolev replaced Tsander as the head of GIRD. On 17 August 1933, Mikhail Tikhonravov launched the first Soviet liquid-propelled rocket (the GIRD-9), fueled by liquid oxygen and jellied gasoline. It reached an altitude of 400 m. In January 1933 Tsander began development of the GIRD-X rocket. This design burned liquid oxygen and gasoline and was one of the first engines to be regeneratively cooled by the liquid oxygen, which flowed around the inner wall of the combustion chamber before entering it. Problems with burn-through during testing prompted a switch from gasoline to less energetic alcohol. The final missile, 2.2 m long by 140 mm in diameter, had a mass of 30 kg, and it was anticipated that it could carry a 2 kg payload to an altitude of 5.5 km. The GIRD X rocket was launched on 25 November 1933 and flew to a height of 80 meters.

In 1933 GDL and GIRD merged and became the Reactive Scientific Research Institute (RNII). At RNII Gushko continued the development of liquid propellant rocket engines ОРМ-53 to ОРМ-102, with ORM-65 powering the RP-318 rocket-powered aircraft. In 1938 Leonid Dushkin replaced Glushko and continued development of the ORM engines, including the engine for the rocket powered interceptor, the Bereznyak-Isayev BI-1. At RNII Tikhonravov worked on developing oxygen/alcohol liquid-propellant rocket engines. Ultimately liquid propellant rocket engines were given a low priority during the late 1930s at RNII, however the research was productive and very important for later achievements of the Soviet rocket program.

Peru
Peruvian Pedro Paulet, who had experimented with rockets throughout his life in Peru, wrote a letter to El Comercio in Lima in 1927, claiming he had experimented with a liquid rocket engine while he was a student in Paris three decades earlier. Historians of early rocketry experiments, among them Max Valier, Willy Ley, and John D. Clark, have given differing amounts of credence to Paulet's report. Valier applauded Paulet's liquid-propelled rocket design in the Verein für Raumschiffahrt publication Die Rakete, saying the engine had "amazing power" and that his plans were necessary for future rocket development. Hermann Oberth would name Paulet as a pioneer in rocketry in 1965. Wernher von Braun would also describe Paulet as "the pioneer of the liquid fuel propulsion motor" and stated that "Paulet helped man reach the Moon". Paulet was later approached by Nazi Germany, being invited to join the Astronomische Gesellschaft to help develop rocket technology, though he refused to assist after discovering that the project was destined for weaponization and never shared the formula for his propellant. According to filmmaker and researcher Álvaro Mejía, Frederick I. Ordway III would later attempt to discredit Paulet's discoveries in the context of the Cold War and in an effort to shift the public image of von Braun away from his history with Nazi Germany.

United States
The first flight of a liquid-propellant rocket took place on March 16, 1926 at Auburn, Massachusetts, when American professor Dr. Robert H. Goddard launched a vehicle using liquid oxygen and gasoline as propellants. The rocket, which was dubbed "Nell", rose just 41 feet during a 2.5-second flight that ended in a cabbage field, but it was an important demonstration that rockets utilizing liquid propulsion were possible. Goddard proposed liquid propellants about fifteen years earlier and began to seriously experiment with them in 1921. The German-Romanian Hermann Oberth published a book in 1922 suggesting the use of liquid propellants.

Germany
In Germany, engineers and scientists became enthralled with liquid propulsion, building and testing them in the late 1920s within Opel RAK, the world's first rocket program, in Rüsselsheim. According to Max Valier's account, Opel RAK rocket designer, Friedrich Wilhelm Sander launched two liquid-fuel rockets at Opel Rennbahn in Rüsselsheim on April 10 and April 12, 1929. These Opel RAK rockets have been the first European, and after Goddard the world's second, liquid-fuel rockets in history. In his book "Raketenfahrt" Valier describes the size of the rockets as of 21 cm in diameter and with a length of 74 cm, weighing 7 kg empty and 16 kg with fuel. The maximum thrust was 45 to 50 kp, with a total burning time of 132 seconds. These properties indicate a gas pressure pumping. The main purpose of these tests was to develop the liquid rocket-propulsion system for a Gebrüder-Müller-Griessheim aircraft under construction for a planned flight across the English channel. Also spaceflight historian Frank H. Winter, curator at National Air and Space Museum in Washington, DC, confirms the Opel group was working, in addition to their solid-fuel rockets used for land-speed records and the world's first crewed rocket-plane flights with the Opel RAK.1, on liquid-fuel rockets. By May 1929, the engine produced a thrust of 200 kg (440 lb.) "for longer than fifteen minutes and in July 1929, the Opel RAK collaborators were able to attain powered phases of more than thirty minutes for thrusts of 300 kg (660-lb.) at Opel's works in Rüsselsheim," again according to Max Valier's account. The Great Depression brought an end to the Opel RAK activities. After working for the German military in the early 1930s, Sander was arrested by Gestapo in 1935, when private rocket-engineering became forbidden in Germany. He was convicted of treason to 5 years in prison and forced to sell his company, he died in 1938. Max Valier's (via Arthur Rudolph and Heylandt), who died while experimenting in 1930, and Friedrich Sander's work on liquid-fuel rockets was confiscated by the German military, the Heereswaffenamt and integrated into the activities under General Walter Dornberger in the early and mid-1930s in a field near Berlin. Max Valier was a co-founder of an amateur research group, the VfR, working on liquid rockets in the early 1930s, and many of whose members eventually became important rocket technology pioneers, including Wernher von Braun. Von Braun served as head of the army research station that designed the V-2 rocket weapon for the Nazis. By the late 1930s, use of rocket propulsion for crewed flight began to be seriously experimented with, as Germany's Heinkel He 176 made the first crewed rocket-powered flight using a liquid rocket engine, designed by German aeronautics engineer Hellmuth Walter on June 20, 1939. The only production rocket-powered combat aircraft ever to see military service, the Me 163 Komet in 1944-45, also used a Walter-designed liquid rocket engine, the Walter HWK 109-509, which produced up to 1,700 kgf (16.7 kN) thrust at full power.

Post World War II
After World War II the American government and military finally seriously considered liquid-propellant rockets as weapons and began to fund work on them. The Soviet Union did likewise, and thus began the Space Race.

In 2010s 3D printed engines started being used for spaceflight. Examples of such engines include SuperDraco used in launch escape system of the SpaceX Dragon 2 and also engines used for first or second stages in launch vehicles from Astra, Orbex, Relativity Space, Skyrora, or Launcher.

title: Liquid-propellant rocket


text:
Proposed bombing of Vietnam's dikes

During the Vietnam War, the U.S. Joint Chiefs of Staff considered and rejected some additions to strategic bombing campaigns that would include targeting a series of dikes and dams along Vietnam's Red River delta. A classified 1965 USAF report suggested that the Red River flood control system could probably not be destroyed by conventional aerial bombing.

In 1966, John McNaughton, Secretary of Defense for International Security Affairs, proposed the destruction of the Red River Valley dams and dikes in order to flood rice paddies, disrupt the North Vietnamese food supply, and leverage Hanoi during negotiations; then-Secretary of Defense Robert McNamara, however, rejected the idea.

Background
The dike and dam system on the Red River had been expanded steadily since independence was declared and by 1972 consisted of nearly 2500 miles of dikes, levees, dams and sluices. Heavy monsoon rains coupled with the preoccupation of the civilian population that normally maintained the water works, led to extensive flooding in 1971. In an attempt to garner international opposition against the newest U.S. strategic bombing campaign, Rolling Thunder, the North Vietnamese Government began a propaganda campaign using images of the flood to allege that the U.S. had begun a strategic bombing campaign against the Red River dikes. Given the North Vietnamese tactic of forcing U.S. aircraft to jettison their bombloads and abort their missions, the dikes undoubtedly were their point of impact on occasion, as they may have been for some downed U.S. aircraft.

North Vietnam
As the North Vietnamese called on the local population to maintain the military lines of communication, labor was drawn away from dike maintenance. The problem was exacerbated by the placement of air defense equipment (AA and GCI) on the dikes and the resulting deterioration caused by the vibration of the guns. North Vietnamese SAMs that missed their mark often fell back to earth before exploding, causing additional damage to the dikes. As the dikes deteriorated, however, the North Vietnamese sought a way to continue to fight the war and maintain the dikes. In order to extract a greater effort from their population, they turned the issue into one that would rally the people, alleging that the United States was bombing the dikes intentionally in order to flood the entire delta. Foreign visitors were provided tours of damaged dikes — photographic coverage indicates that most visitors were taken to the same "damaged" dike over a period of several years — to exploit the issue in the foreign press.

United States
President Richard Nixon and Secretary of State Henry Kissinger discussed bombing the dike network in a 1972 conversation on Operation Linebacker II, later published by Daniel Ellsberg:

Nixon: We've got to quit thinking in terms of a three-day strike [in the Hanoi-Haiphong area]. We've got to be thinking in terms of an all-out bombing attack - which will continue until they - Now by all-out bombing attack, I am thinking about things that go far beyond. I'm thinking of the dikes, I'm thinking of the railroad, I'm thinking, of course, the docks.

Kissinger: I agree with you.

President Nixon: We've got to use massive force.

Two hours later at noon, H. R. Haldeman and Ron Ziegler joined Kissinger and Nixon: President: How many did we kill in Laos?

Ziegler: Maybe ten thousand - fifteen?

Kissinger: In the Laotian thing, we killed about ten, fifteen.

President: See, the attack in the North that we have in mind, power plants, whatever's left - POL [petroleum], the docks. And, I still think we ought to take the dikes out now. Will that drown people?

Kissinger: About two hundred thousand people.

President: No, no, no, I'd rather use the nuclear bomb. Have you got that, Henry?

Kissinger: That, I think, would just be too much.

President: The nuclear bomb, does that bother you?...I just want you to think big, Henry, for Christsakes.

U.S. investigation into the North Vietnamese claims revealed that U.S. bombing had caused minor damage to the dikes but none of the damaged structures were part of the system protecting Hanoi, and none of the damage was severe enough to cause a major breach. Further complicating matters was the North Vietnamese placement of anti-aircraft radars, surface to air missiles, and artillery atop dike structures. The dike system was also part of the North Vietnamese transportation network, with roads and rail lines in close proximity to the dikes. Although authorization was given during Operation Linebacker II to attack these sites, only the use of napalm, cluster bombs, and other antipersonnel weapons were permitted to be used in an attempt to minimize structural damage.

International reaction
The North Vietnamese used these incidents as part of their propaganda campaign. Actress Jane Fonda is often credited with helping publicize the bombing, for which then U.S. Ambassador to the UN George H. W. Bush accused her of lying. Columnist Joseph Kraft who was also touring North Vietnam, believed that the damage to the dikes was done in error and was being used as propaganda by Hanoi, and that if the U.S. Air Force were "truly going after the dikes, it would do so in a methodical, not a harum-scarum way." Others, like Jean Thoraval of Agence France-Presse, reported personally witnessing a U.S. bombing raid where a dozen planes had dropped bombs and fired rockets on a nearby dike, concluding that "the attack was aimed at a whole system of dikes." Sweden's Ambassador to Hanoi, Jean-Christophe Öberg, along with two Swedish journalists, described the damage to the dikes as "methodic."

An investigation into the bombing of the dikes carried out by a French geographer, Yves Lacoste, concluded that the bombing was based on a systematic policy to flood the eastern part of the delta. According to the investigation, the eastern part was targeted more than the western part which had more military targets (for instance, Hanoi). The investigation stated that the overwhelming majority of dike bombing also occurred on the concave sections of dike, the most vulnerable to such bombing and that the effects of the bombing were profound, as 'minor damage' actually severely weakened the dike structure through sub-surface cracking, which increased vulnerability during periods of high discharge.

title: Proposed bombing of Vietnam's dikes


text:
XV Corps (India)

XV Corps, or 15 Corps, also known as Chinar Corps, is a Corps of the Indian Army which is presently located in Srinagar and responsible for military operations in the Kashmir Valley. It has participated in all military conflicts with Pakistan and China till date. Lieutenant General Rajiv Ghai is its current Corps Commander since 14 June 2023 taking over from Lieutenant General Amardeep Singh Aujla.

History
HQ XV Corps was first raised in Egypt at Port Said on January 12, 1916, under the command of Lieutenant General Sir Henry Horne who was sacked after killing of five under command Indian soldiers. It was part of the British Indian Army during the First World War for operations in Egypt and France. Disbanded in 1918, it was re-raised on March 20, 1942, at Barrackpore for combat operations in Burma during World War II, and after the war, it served in Java and Sumatra.

Disbanded in Karachi in 1947 after repatriation, it was re-raised after India gained independence, as part of the Indian Army, in 1948 as HQ Jammu and Kashmir Force. It underwent a number of name changes till its final re-designation as HQ 15 Corps in 1955 in Udhampur. In June 1972, HQ Northern Command was raised to take over operational control of Jammu & Kashmir. HQ 15 Corps moved to Srinagar to take charge of the Kashmir Valley and Ladakh. After Operation Vijay, HQ 15 Corps was made solely responsible for military operations in the Kashmir Valley.

Formation Sign
The design consists of the 'red-white-red background' depicting a corps of the Indian Army with a Chinar leaf and a battle axe superimposed on it.

Composition
The corps currently consists of:

 * 19th Mountain Division (Dagger Division) headquartered at Baramulla
 * 28th Infantry Division (Vajr Division) headquartered at Kupwara
 * Kilo Force, 'Victor Forceof the Rashtriya Rifles come under the operational control of the corps

title: XV Corps (India)