text: Category:Citroën

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

title: Category:Citroën


text:
User:NathanHawking

Introduction
Hello:

I'm Nathan Hawking. Among other things, I write. Contact me on my talk page. Direct personal communication through the Wikipedia email channel.

There seems to be no shortage of editors on Wikipedia, so I focus on writing new articles, or substantially modifying needy existing material. My contributions may reflect my interests, or not. One link leads to another.

I joined the Wikipedia gang on September 25, 2004, making modest revisions to an article about the offspring of a union between a donkey and a zebra.

Donkey liaisons are not prominent in my thoughts—honest!—so what took me to that article? I don't remember; perhaps that random page link to your left.

Wikipedia is a wonderful place to wander, and of no other place can it be more aptly urged: "If you come to a fork in the road, take it."—Yogi Berra

Contributions—major

 * Article on Captain Stubby and the Buccaneers
 * Article on Roto-Rooter
 * Article on Steve Reeves
 * Article on List of redundant expressions
 * Article on Prolixity
 * Article on List of heteronyms
 * Proposal for Wikipedia pronunciation guide

 * Rewrote and refactored much of Serial comma
 * Intro to War
 * "Costs and benefits of war" section of War
 * "Language" section in Redundancy
 * Refactored Pronunciation
 * Addition to and clarification of Zone system
 * Major edit of Suicide to remove POV problems with "commit" terminology and bloated language

Personal

 * User:NathanHawking/Images01
 * User:NathanHawking/Personal style sheet
 * User:NathanHawking/Prototype01
 * User:NathanHawking/Templates

 * Category: Wikipedia official policy

 * Special:Upload

 * Cleanup
 * Copyright
 * 1) Boilerplate request for permission
 * Help desk
 * Ignore all rules
 * Image copyright tags
 * How to edit a page
 * Manual of Style
 * Policies and guidelines
 * Redirect
 * Template messages
 * Village pump
 * Policies and guidelines
 * Redirect
 * Template messages
 * Village pump
 * Village pump
 * Village pump
 * Village pump

Quotes

 * Albert Einstein: Make everything as simple as possible, but not simpler.

 * Groucho Marx: Outside of a dog, books are a man's best friend. Inside of a dog, it's too dark to read.

 * Max Planck: A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

 * Ian Wright--Globe Trekker: Just because somebody lives in a remote village doesn't mean they aren't a complete twit.

title: User:NathanHawking


text:
Category:French mathematicians

fr:Catégorie:Mathématicien français

title: Category:French mathematicians


text:
Mr. Driller

Mr. Driller (ミスタードリラー) is a puzzle video game franchise created by Yasuhito Nagaoka and Hideo Yoshizawa for Namco. The eponymous first game was released in 1999 for arcades and several home consoles, such as the PlayStation. Gameplay in the series consists of controlling Susumu Hori, the titular Mr. Driller, or one of his friends and destroying colorful formations of blocks to make it to the bottom of a well. In order to survive, players need to collect air capsules to replenish their depleting oxygen and avoid being crushed by falling blocks.

Nagaoka intended Mr. Driller to be the third mainline entry in Namco's Dig Dug series. The two franchises have since been directly connected to one another through sharing characters and similar gameplay concepts. Project Driller was established as the development team for the series, which produced four sequels from 2000 to 2004. Bandai Namco Entertainment became the owner of the Mr. Driller property after Namco's 2005 merger with Bandai, where it released several more installments for digital distribution services and mobile devices.

The Mr. Driller series was popular in Japan and its characters have become synonymous with the Namco brand. Reception from western publications has varied depending on the game. Most critics agree the series benefits from its simplicity and addictive nature, though several installments have been criticized for their lack of content and recycling of assets from earlier games.

Games

 * Mr. Driller (1999) was first released to arcades for Namco's System 11 arcade hardware. It was later ported to several consoles, including the Game Boy Color, PlayStation, Dreamcast, WonderSwan Color, Windows, and mobile phones. It introduces the core components of the series, the character Susumu Hori, and a story involving creatures known as Undergrounders flooding the Earth with giant blocks.
 * Mr. Driller 2 (2000) was released for arcades in Japan and later for the Game Boy Advance and Windows. The sequel features Susumu's rival, the hot-headed German driller Anna Hottenmeyer, alongside improvements such as increasing the game speed, two-player cooperative play, and additional game modes.
 * Mr. Driller G (2001) was released for arcades and the PlayStation in Japan, serving as the final Mr. Driller game for arcades and the first developed by Project Driller. In addition to including a story-driven campaign mode, G adds several new playable characters, including Susumu's older brother Ataru Hori, his father Taizo Hori, the dog Puchi, and the drilling robot Horinger-Z.
 * Mr. Driller A (2002) was released in Japan for the Game Boy Advance. The game presents new mechanics and concepts that are designed after classic role-playing games, as opposed to the fast-paced action of previous installments. Players can also care for and train a virtual pet named a "Pacteria" through progress made in the main game.
 * Mr. Driller Drill Land (2002) was released for the GameCube in Japan. The game is more ambitious than previous Mr. Driller games, featuring multiple game modes that vary in gameplay. These modes are tied together through a menu and presentation designed after an amusement park. In 2020, the game was remastered for the Nintendo Switch and PC through Steam with English subtitles.
 * Mr. Driller: Driller Puzzle (2003) was released for Japanese mobile phones through Java and i-Mode. The game has players completing a series of levels in the quickest amount of time. A sequel named Mr. Driller: Driller Puzzle S was released in 2006.
 * Mr. Driller Drill Spirits (2004) was released for the Nintendo DS and takes advantage of the system's dual screens. The game reuses concepts established in Drill Land and includes boss fights, item shops, and multiplayer modes.
 * Mr. Driller Aqua (2006) was released for Japanese mobile phones through the i-Mode and EZweb networks. It features an aquatic theme and was available for a limited time through Namco Bandai Games' mobile phone content providers.
 * Mr. Driller Online (2008) was released for the Xbox 360 as a downloadable release. It contains an online multiplayer mode that is accessible through the Xbox Live online subscription service, though a single-player mode is also available.
 * Mr. Driller: Drill Till You Drop (2009) was released for the Nintendo DSi through the DSiWare service, and is titled Sakkuto Hama Reru Hori Hori Action: Mr. Driller in Japan. It features the "Dristone" role-playing game mode from G and Drill Land, where players collect crystals that have varying effects on the game. The game was delisted as of March 29, 2019.
 * Mr. Driller W (2009) was released for the WiiWare service for the Wii, and is known as Mr. Driller World in Japan. W reuses mechanics from Drill Land while being presented in high-definition and featuring online leaderboards.
 * Mr. Driller VS (2010) was released for i-Mode cellular devices in Japan. It includes a local multiplayer mode and online co-op using Bluetooth. The servers were shut down in May 2011.
 * Mr. Driller for Kakao (2015) was developed and published by Netmarble for iOS in South Korea. It uses free-to-play elements and involves players trying to collect pets that are trapped inside blocks.

Common elements
The Mr. Driller games are puzzle action games and have been described as a cross between Puyo Puyo and Dig Dug. Players control a character that must destroy, or "drill", colorful formations of blocks in order to reach the bottom of a well. Blocks of the same color can connect to each other; if four of a kind connect, they are destroyed, which can be used to create chain reactions. The player has a constantly depleting oxygen meter that can be replenished by collecting blue air capsules. Oxygen is lost by destroying brown "x"-marked blocks, which take five hits to destroy. Certain characters have their own attributes and abilities, such as depleting oxygen less and moving faster. Later games introduce mechanics such as star-marked blocks that disappear after a brief period, boss fights, power-ups, and game modes that implement ideas from role-playing games.

Development
The original Mr. Driller was created by R4: Ridge Racer Type 4 director Yasuhito Nagaoka and former Tecmo employee Hideo Yoshizawa. Nagaoka drafted the game in 1998 as a second sequel to Dig Dug, a classic Namco arcade game from 1982, aptly named Dig Dug 3. The game was designed to be more puzzle-like in gameplay structure, a contrast to the action-oriented gameplay of Dig Dug and Dig Dug II. Yoshizawa made several alterations to Nagaoka's prototype build, including the renaming to Mr. Driller. Namco released the game in arcades in 1999 to critical and commercial success. Mr. Driller was ported to several platforms, including the Dreamcast, PlayStation, and Game Boy Color.

Yoshizawa and Nagaoka quickly began work on a sequel, Mr. Driller 2, in late 1999. The two worked to implement new features, such as a second-player character and making the gameplay faster and more chaotic than the original. The sequel was released for arcades in 2000 to moderate success and was followed by a port for the Game Boy Advance in 2001. The Game Boy Advance version was a launch title for the system and sold over 100,000 copies, however, the game wasn't released in North America and Europe until 2005.

The third entry, Mr. Driller G, was released in 2001 for arcades and later the PlayStation. The game was created to be more story-driven than the previous installments, which expanded on the Mr. Driller universe and helped bridge the connection between the Mr. Driller and Dig Dug franchises. Taizo Hori, the protagonist of the Dig Dug series, is a playable character in G and is revealed to be the father of Susumu and his older brother Ataru Hori. The PlayStation version was only moderately successful with around 10,000 being sold during launch week.

Yoshizawa intended G to be the final game in the series, but Namco was approached by Nintendo to create a Mr. Driller game for the GameCube that took advantage of the console's GameCube – Game Boy Advance link cable peripheral. This resulted in the creation of Mr. Driller A for the Game Boy Advance and Mr. Driller Drill Land for the GameCube in 2002. A implemented a Tamagotchi-inspired virtual pet that could be transferred to Drill Land. Though Drill Land received the most acclaim out of any game in the series, its exclusivity to the GameCube made it a commercial failure. Namco became less interested in supporting the franchise as a result. Mr. Driller Drill Spirits, the second portable entry in the series, was released in 2004 for the Nintendo DS and reused many of Drill Land's game modes and assets, though condensed to meet the system's hardware limitations. Namco's North American division stripped most of its content in order for it to be ready in time for the launch of the DS in the United States, a move that garnered significant criticism from publications.

Namco Bandai Games became the owner of the Mr. Driller intellectual property after Namco's 2005 merger with Bandai. Mr. Driller Online (2008) for the Xbox 360, Mr. Driller: Drill Till You Drop (2009) for DSiWare, and Mr. Driller W (2009) for WiiWare all recycle art assets and pre-established concepts from earlier games. Yoshizawa considered Drill Till You Drop to be the "culmination" of the series and likely the last one he would develop. By the early 2010s, Namco Bandai largely abandoned the property outside several mobile phone spin-offs.

In 2020, Bandai Namco Entertainment began to remaster of Drill Land for the Nintendo Switch and PC as part of its Encore series of remasters. The decision to remaster the game was based on the success of the remake for Katamari Damacy (2004). Yoshizawa, who had left Bandai Namco in 2016, supervised the project. The remaster was released in 2020 worldwide, titled Mr. Driller Encore in Japan. Maya Ito, the producer for Encore, says Bandai Namco would consider continuing the series if the remake was popular enough.

Related games
The scrolling shooters Baraduke (1985) and Bakutotsu Kijutei (1988) have retroactively been connected to the Mr. Driller series through Baraduke's protagonist, Masuyo Tobi, having been formerly married to Taizo Hori. The 2002 arcade game Star Trigon adopts many of Mr. Driller's characters and concepts. Star Trigon is a puzzle game where players hop across planets to create triangles in order to rescue yellow creatures. Project Driller developed Star Trigon and is considered a spin-off of the Mr. Driller series. The game was ported to mobile phones and Windows in 2008.

In 2005, Namco revived its Dig Dug series with Dig Dug: Digging Strike for the Nintendo DS. The game was designed to be closer to the company's original vision of Mr. Driller, and features gameplay that combines mechanics present in Dig Dug, Dig Dug II, and Mr. Driller. Digging Strike was part of Namco's continuing efforts in making Dig Dug and Mr. Driller part of the company's pillar franchises. It received mixed reviews and was primarily criticized for its lack of long-lasting appeal and replay value. The 2005 compilation NamCollection includes Mr. Driller along with four other Namco-published PlayStation games for the PlayStation 2, in addition to bonus material such as conceptual art.

Reception
In Japan, the Mr. Driller series was commercially and critically successful, and its characters have become synonymous with the Namco brand. The original received the 1st Arcadia Grand Prize from the Japanese magazine Monthly Arcadia, and Namco received a prestigious award from Edge for Drill Land. Famitsu awarded the Game Boy Color port of Mr. Driller, Mr. Driller G, and the Game Boy Advance port of Mr. Driller 2 the Silver Hall of Fame awards, while Mr. Driller A and Drill Land received the Gold Hall of Fame award.

Western perception of the series has varied depending on the game, though consensus agrees its gameplay is simple and addictive. The Dreamcast conversion of Mr. Driller received negative attention from the press for being technically inferior to Namco's previous Dreamcast offering, the 3D weapon-based fighter Soulcalibur. Journalist Jeremy Parish speculates this backlash resulted in the series receiving a largely lukewarm reception outside Japan.

Mr. Driller G and Drill Land have been ranked as the best in the series for their quality and amount of content, while Online, W, and Drill Till You Drop have been listed as the weakest for their poor presentation and lack of innovation. Online in particular was negatively received for its online multiplayer, which multiple reviews found to have been unfinished and "broken". Drill Spirits and home ports of Mr. Driller and Mr. Driller 2 were criticized for being barren of content, though the Japanese and European releases of Drill Spirits have been identified as being a far bigger improvement over the North American version for their inclusion of additional game modes.

title: Mr. Driller


text: User talk:69.110.32.150

title: User talk:69.110.32.150


text: File:Daftclub.jpg

title: File:Daftclub.jpg


text:
Pusher configuration

In aeronautical and naval engineering, pusher configuration is the term used to describe a drivetrain of air- or watercraft with propulsion device(s) after the engine(s). This is in contrast to the more conventional tractor configuration, which places them in front.

Though the term is most commonly applied to aircraft, its most ubiquitous propeller example is a common outboard motor for a small boat.

“Pusher configuration” describes the specific (propeller or ducted fan) thrust device attached to a craft, either aerostats (airship) or aerodynes (aircraft, WIG, paramotor, rotorcraft) or others types such as hovercraft, airboats, and propeller-driven snowmobiles.

History

The rubber-powered "Planophore", designed by Alphonse Pénaud in 1871, was an early successful model aircraft with a pusher propeller.

Many early aircraft (especially biplanes) were "pushers", including the Wright Flyer (1903), the Santos-Dumont 14-bis (1906), the Voisin-Farman I (1907), and the Curtiss Model D used by Eugene Ely for the first ship landing on January 18, 1911. Henri Farman's pusher Farman III and its successors were so influential in Britain that pushers in general became known as the "Farman type". Other early pusher configurations were variations on this theme.

The classic "Farman" pusher had the propeller "mounted (just) behind the main lifting surface" with the engine fixed to the lower wing or between the wings, immediately forward of the propeller in a stub fuselage (that also contained the pilot) called a nacelle. The main difficulty with this type of pusher design was attaching the tail (empennage). This needed to be in the same general location as on a tractor aircraft, but its support structure had to avoid the propeller.

The earliest examples of pushers relied on a canard but this has serious aerodynamic implications that the early designers were unable to resolve. Typically, mounting the tail was done with a complex wire-braced framework that created a lot of drag. Well before the beginning of the First World War, this drag was recognized as just one of the factors that would ensure that a Farman-style pusher would have an inferior performance to an otherwise similar tractor type.

The U.S. Army banned pusher aircraft in late 1914 after several pilots died in crashes of aircraft of this type, so from about 1912 onwards, the great majority of new U.S. landplane designs were tractor biplanes, with pushers of all types becoming regarded as old-fashioned on both sides of the Atlantic. However, new pusher designs continued to be designed right up to the armistice, such as the Vickers Vampire, although few entered service after 1916.

At least up to the end of 1916, however, pushers (such as the Airco DH.2 fighter) were still favored as gun-carrying aircraft by the British Royal Flying Corps, because a forward-firing gun could be used without being obstructed by the arc of the propeller. With the successful introduction of Fokker's mechanism for synchronizing the firing of a machine gun with the blades of a moving propeller, followed quickly by the widespread adoption of synchronization gears by all the combatants in 1916 and 1917, the tractor configuration became almost universally favored, and pushers were reduced to the tiny minority of new aircraft designs that had a specific reason for using the arrangement.

Both the British and French continued to use pusher-configured bombers, though there was no clear preference either way until 1917. Such aircraft included (apart from the products of the Farman company) the Voisin bombers (3,200 built), the Vickers F.B.5 "Gunbus", and the Royal Aircraft Factory F.E.2; however, even these found themselves being shunted into training roles before disappearing entirely. Possibly the last fighter to use the Farman pusher configuration was the 1931 Vickers Type 161 COW gun fighter.

During the long eclipse of the configuration the use of pusher propellers continued in aircraft which derived a small benefit from the installation and could have been built as tractors. Biplane flying boats had for some time often been fitted with engines located above the fuselage to offer maximum clearance from the water, often driving pusher propellers to avoid spray and the hazards involved by keeping them well clear of the cockpit. The Supermarine Walrus was a late example of this layout.

The so-called push/pull layout, combining the tractor and pusher configurations—that is, with one or more propellers facing forward and one or more others facing back—was another idea that continues to be used from time to time as a means of reducing the asymmetric effects of an outboard engine failure, such as on the Farman F.222, but at the cost of a severely reduced efficiency on the rear propellers, which were often smaller and attached to lower-powered engines as a result.

By the late 1930s, the widespread adoption of all-metal stressed skin construction of aircraft meant, at least in theory, that the aerodynamic penalties that had limited the performance of pushers (and indeed any unconventional layout) were reduced; however, any improvement that boosts pusher performance also boosts the performance of conventional aircraft, and they remained a rarity in operational service—so the gap was narrowed but was closed entirely.

During World War II, experiments were conducted with pusher fighters by most of the major powers. Difficulties remained, particularly that a pilot having to bail out of a pusher was liable to pass through the propeller arc. This meant that of all the types concerned, only the relatively conventional Swedish SAAB 21 of 1943 went into series production. Other problems related to the aerodynamics of canard layouts, which had been used on most of the pushers, proved more difficult to resolve. One of the world's first ejection seats was (per force) designed for this aircraft, which later re-emerged with a jet engine.

The largest pusher aircraft to fly was the Convair B-36 "Peacemaker" of 1946, which was also the largest bomber ever operated by the United States. It had six 3,800 hp 28-cylinder Pratt & Whitney Wasp Major radial engines mounted in the wing, each driving a pusher propeller located behind the trailing edge of the wing, plus four jet engines. Although the vast majority of propeller-driven aircraft continue to use a tractor configuration, there has been in recent years something of a revival of interest in pusher designs: in light homebuilt aircraft such as Burt Rutan's canard designs since 1975, ultralights such as the Quad City Challenger (1983), flexwings, paramotors, powered parachutes, and autogyros. The configuration is also often used for unmanned aerial vehicles, due to requirements for a forward fuselage free of any engine interference.

The Aero Dynamics Sparrow Hawk was another homebuilt aircraft constructed chiefly in the 1990s.

Configurations
Airships are the oldest type of pusher aircraft, going back to Frenchman Henri Giffard's pioneering airship of 1852.

Pusher aircraft have been built in many different configurations. In the vast majority of fixed-wing aircraft, the propeller or propellers are still located just behind the trailing edge of the "main lifting surface", or below the wing (paramotors) with the engine being located behind the crew position.

Conventional aircraft layout have a tail (empennage) for stabilization and control. The propeller may be close to the engine, as the usual direct drive:

 * The propeller may be ahead of the tail: inside the framework (Farman III), in line with the fuselage (RFB Fantrainer), between tail booms (Cessna Skymaster), above the fuselage on wing (Quad City Challenger), on nacelle or axial pod (Lake Buccaneer), or coaxially around rear fuselage (Gallaudet D-4).
 * The propeller may be located behind the vertical tail, under the horizontal tail (Prescott Pusher).
 * Engines and propellers may be located on wings (Piaggio P.180 Avanti) or on lateral pods (Embraer/FMA CBA 123 Vector ).

The engine may be buried in a forward remote location, driving the propeller by drive shaft or belt:

 * The propeller may be located ahead of the tail, behind the wing (Eipper Quicksilver) or inside the airframe (Rhein Flugzeugbau RW 3 Multoplan).
 * The propeller may be located inside the tail, either cruciform or ducted fan (Marvelette).
 * The propeller may be located at the rear, behind a conventional tail (Bede BD-5).
 * The propeller may be located above the fuselage such as on many small flying boats (Lake Buccaneer)

In canard, designs a smaller wing is sited forward of the aircraft's main wing. This class mainly uses a direct drive, either single-engine axial propeller, or twin engines with a symmetrical layout, or an in line layout (push-pull) as the Rutan Voyager.

In tailless aircraft such as Lippisch Delta 1 and Westland-Hill Pterodactyl types I and IV, horizontal stabilizers at the rear of the aircraft are absent. Flying wings like the Northrop YB-35 are tailless aircraft without a distinct fuselage. In these installations, the engines are either mounted in nacelles or the fuselage on tailless aircraft, or buried in the wing on flying wings, driving propellers behind the trailing edge of the wing, often by extension shaft.

Almost without exception, flexwing aircraft, paramotors, and powered parachutes use a pusher configuration.

Other craft with pusher configurations run on flat surfaces, land, water, snow, or ice. Thrust is provided by propellers and ducted fans, located to the rear of the vehicle. These include:

 * Hovercraft, lifted by an air cushion, such as the 58 passengers SR.N6.
 * Airboats, flat bottomed vessels planing on water.
 * Aerosledges, also known as the aerosleigh, propeller-driven sledge, or propeller-driven snowmobile.

Advantages
The drive shaft of a pusher engine is in compression in normal operation, which places less stress on it than being in tension in a tractor configuration.

Practical requirements
Placing the cockpit forward of the wing to balance the weight of the engine(s) aft improves visibility for the crew. In military aircraft, front armament could be used more easily on account of the gun not needing to synchronize itself with the propeller, although the risk that spent casings fly into the props at the back somewhat offset this advantage.

Aircraft where the engine is carried by, or very close to, the pilot (such as paramotors, powered parachutes, autogyros, and flexwing trikes) place the engine behind the pilot to minimize the danger to the pilot's arms and legs. These two factors mean that this configuration was widely used for early combat aircraft, and remains popular today among ultralight aircraft, unmanned aerial vehicles (UAVs), and radio-controlled airplanes.

Aerodynamics
A pusher may have a shorter fuselage and hence a reduction in both fuselage wetted area and weight.

In contrast to tractor layout, a pusher propeller at the end of the fuselage is stabilizing. A pusher needs less stabilizing vertical tail area and hence presents less weathercock effect; at takeoff roll, it is generally less sensitive to crosswind.

When there is no tail within the slipstream, unlike a tractor, there is no rotating propwash around the fuselage inducing a side force to the fin. At takeoff, a canard pusher pilot does not have to apply rudder input to balance this moment.

Efficiency can be gained by mounting a propeller behind the fuselage, because it re-energizes the boundary layer developed on the body, and reduces the form drag by keeping the flow attached to the fuselage. However, it is usually a minor gain compared to the airframe's detrimental effect on propeller efficiency.

Wing profile drag may be reduced due to the absence of prop-wash over any section of the wing.

Safety
The engine is mounted behind the crew and passenger compartments, so fuel oil and coolant leaks will vent behind the aircraft, and any engine fire will be directed behind the aircraft. Similarly, propeller failure is less likely to directly endanger the crew.

A pusher ducted fan system offers a supplementary safety feature attributed to enclosing the rotating fan in the duct, therefore making it an attractive option for various advanced UAV configurations or for small/personal air vehicles or for aircraft models.

Structural and weight considerations
A pusher design with an empennage behind the propeller is structurally more complex than a similar tractor type. The increased weight and drag degrades performance compared with a similar tractor type. Modern aerodynamic knowledge and construction methods may reduce but never eliminate the difference. A remote or buried engine requires a drive shaft and associated bearings, supports, and torsional vibration control, and adds weight and complexity.

Center of gravity and landing gear considerations
To maintain a safe center of gravity (CG) position, there is a limit to how far aft an engine can be installed. The forward location of the crew may balance the engine weight and will help determine the CG. As the CG location must be kept within defined limits for safe operation load distribution must be evaluated before each flight.

Due to a generally high thrust line needed for propeller ground clearance, negative (down) pitching moments, and in some cases the absence of prop-wash over the tail, a higher speed and a longer roll may be required for takeoff compared to tractor aircraft. The Rutan answer to this problem is to lower the nose of the aircraft at rest such that the empty center of gravity is then ahead of the main wheels. In autogyros, a high thrust line results in a control hazard known as power push-over.

Aerodynamic considerations
Due to the generally-high thrust line to ensure ground clearance, a low-wing pusher layout may suffer power-change-induced pitch changes, also known as pitch/power coupling. Pusher seaplanes with especially high thrust lines and tailwheels may find the vertical tail masked from the airflow, severely reducing control at low speeds, such as when taxiing. The absence of prop-wash over the wing reduces the lift and increases takeoff roll length. Pusher engines mounted on the wing may obstruct sections of the wing trailing edge, reducing the total width available for control surfaces such as flaps and ailerons. When a propeller is mounted in front of the tail, changes in engine power alter the airflow over the tail and can give strong pitch or yaw changes.

Propeller ground clearance and foreign object damage
Due to the pitch rotation at takeoff, the propeller diameter may have to be reduced (with a loss of efficiency ) and/or landing gear made longer and heavier. Many pushers have ventral fins or skids beneath the propeller to prevent the propeller from striking the ground, at an added cost in drag and weight. On tailless pushers such as the Rutan Long-EZ, the propeller arc is very close to the ground while flying nose-high during takeoff or landing. Objects on the ground kicked up by the wheels can pass through the propeller disc, causing damage or accelerated wear to the blades; in extreme cases, the blades may strike the ground.

When an airplane flies in icing conditions, ice can accumulate on the wings. If an airplane with wing-mounted pusher engines experiences icing, the props will ingest shredded chunks of ice, endangering the propeller blades and parts of the airframe that can be struck by ice violently redirected by the props. In early pusher combat aircraft, spent ammunition casings caused similar problems, and devices for collecting them had to be devised.

Propeller efficiency and noise
The propeller passes through the fuselage wake, wing wake, and other flight surface downwashes—moving asymmetrically through a disk of irregular airspeed. This reduces propeller efficiency and causes vibration inducing structural propeller fatigue and noise.

Prop efficiency is usually at least 2–5% less and in some cases more than 15% less than an equivalent tractor installation. Full-scale wind tunnel investigation of the canard Rutan VariEze showed a propeller efficiency of 0.75 compared to 0.85 for a tractor configuration, a loss of 12%. Pusher props are noisy, and cabin noise may be higher than tractor equivalent (Cessna XMC vs Cessna 152). Propeller noise may increase because the engine exhaust flows through the props. This effect may be particularly pronounced when using turboprop engines due to the large volume of exhaust they produce.

Engine cooling and exhaust
Power-plant cooling design is more complex in pusher engines than for the tractor configuration, where the propeller forces air over the engine or radiator. Some aviation engines have experienced cooling problems when used as pushers. To counter this, auxiliary fans may be installed, adding additional weight. The engine of a pusher exhausts forward of the propeller, and in this case, the exhaust may contribute to corrosion or other damage to the propeller. This is usually minimal, and may be mainly visible in the form of soot stains on the blades.

Propeller
In case of propeller/tail proximity, a blade break can hit the tail or produce destructive vibrations, leading to a loss of control.

Crew members risk striking the propeller while attempting to bail out of a single-engined airplane with a pusher prop. At least one early ejector seat was designed specifically to counter this risk. Some modern light aircraft include a parachute system that saves the entire aircraft, thus averting the need to bail out.

Engine
Engine location in the pusher configuration might endanger the aircraft's occupants in a crash or crash-landing in which engine momentum projects through the cabin. For example, with the engine placed directly behind the cabin, during a nose-on impact, the engine momentum may carry the engine through the firewall and cabin, and might injure some cabin occupants.

Aircraft loading
Spinning propellers are always a hazard on ground working, such as loading or embarking the airplane. The tractor configuration leaves the rear of the plane as relatively safe working area, while a pusher is dangerous to approach from behind, while a spinning propeller may suck in things and people nearby in front of it with fatal results to both the plane and the people sucked in. Even more hazardous are unloading operations, especially mid-air, such as dropping supplies on parachute or skydiving operations, which are next to impossible with a pusher configuration airplane, especially if propellers are mounted on fuselage or sponsons.

title: Pusher configuration


text:
Boltzmann equation

The Boltzmann equation or Boltzmann transport equation (BTE) describes the statistical behaviour of a thermodynamic system not in a state of equilibrium; it was devised by Ludwig Boltzmann in 1872. The classic example of such a system is a fluid with temperature gradients in space causing heat to flow from hotter regions to colder ones, by the random but biased transport of the particles making up that fluid. In the modern literature the term Boltzmann equation is often used in a more general sense, referring to any kinetic equation that describes the change of a macroscopic quantity in a thermodynamic system, such as energy, charge or particle number.

The equation arises not by analyzing the individual positions and momenta of each particle in the fluid but rather by considering a probability distribution for the position and momentum of a typical particle—that is, the probability that the particle occupies a given very small region of space (mathematically the volume element $$d^3 \mathbf{r}$$) centered at the position $$\mathbf{r}$$, and has momentum nearly equal to a given momentum vector $$ \mathbf{p}$$ (thus occupying a very small region of momentum space $$d^3 \mathbf{p}$$), at an instant of time.

The Boltzmann equation can be used to determine how physical quantities change, such as heat energy and momentum, when a fluid is in transport. One may also derive other properties characteristic to fluids such as viscosity, thermal conductivity, and electrical conductivity (by treating the charge carriers in a material as a gas). See also convection–diffusion equation.

The equation is a nonlinear integro-differential equation, and the unknown function in the equation is a probability density function in six-dimensional space of a particle position and momentum. The problem of existence and uniqueness of solutions is still not fully resolved, but some recent results are quite promising.

The phase space and density function
The set of all possible positions r and momenta p is called the phase space of the system; in other words a set of three coordinates for each position coordinate x, y, z, and three more for each momentum component $p_{x}$, $p_{y}$, $p_{z}$. The entire space is 6-dimensional: a point in this space is $(r, p) = (x, y, z, p_{x}, p_{y}, p_{z})$, and each coordinate is parameterized by time t. The small volume ("differential volume element") is written $$ d^3\mathbf{r} \, d^3\mathbf{p} = dx \, dy \, dz \, dp_x \, dp_y \, dp_z. $$

Since the probability of $N$ molecules, which all have $r$ and $p$ within $$ d^3\mathbf{r} \, d^3\mathbf{p}$$, is in question, at the heart of the equation is a quantity $f$ which gives this probability per unit phase-space volume, or probability per unit length cubed per unit momentum cubed, at an instant of time $t$. This is a probability density function: $f(r, p, t)$, defined so that, $$dN = f (\mathbf{r},\mathbf{p},t) \, d^3\mathbf{r} \, d^3\mathbf{p}$$ is the number of molecules which all have positions lying within a volume element $$ d^3\mathbf{r}$$ about $r$ and momenta lying within a momentum space element $$ d^3\mathbf{p}$$ about $p$, at time $t$. Integrating over a region of position space and momentum space gives the total number of particles which have positions and momenta in that region:

$$\begin{align} N & = \int\limits_\mathrm{momenta} d^3\mathbf{p} \int\limits_\mathrm{positions} d^3\mathbf{r}\,f (\mathbf{r},\mathbf{p},t) \\[5pt] & = \iiint\limits_\mathrm{momenta} \quad \iiint\limits_\mathrm{positions} f(x,y,z, p_x,p_y,p_z, t) \, dx \, dy \, dz \, dp_x \, dp_y \, dp_z \end{align}$$

which is a 6-fold integral. While $f$ is associated with a number of particles, the phase space is for one-particle (not all of them, which is usually the case with deterministic many-body systems), since only one $r$ and $p$ is in question. It is not part of the analysis to use $r_{1}$, $p_{1}$ for particle 1, $r_{2}$, $p_{2}$ for particle 2, etc. up to $r_{N}$, $p_{N}$ for particle N.

It is assumed the particles in the system are identical (so each has an identical mass $m$). For a mixture of more than one chemical species, one distribution is needed for each, see below.

Principal statement
The general equation can then be written as $$ \frac{df}{dt} = \left(\frac{\partial f}{\partial t}\right)_\text{force} + \left(\frac{\partial f}{\partial t}\right)_\text{diff} + \left(\frac{\partial f}{\partial t}\right)_\text{coll}, $$

where the "force" term corresponds to the forces exerted on the particles by an external influence (not by the particles themselves), the "diff" term represents the diffusion of particles, and "coll" is the collision term – accounting for the forces acting between particles in collisions. Expressions for each term on the right side are provided below.

Note that some authors use the particle velocity $v$ instead of momentum $p$; they are related in the definition of momentum by $p = mv$.

The force and diffusion terms
Consider particles described by $f$, each experiencing an external force $F$ not due to other particles (see the collision term for the latter treatment).

Suppose at time $t$ some number of particles all have position $r$ within element $$ d^3\mathbf{r}$$ and momentum $p$ within $$ d^3\mathbf{p}$$. If a force $F$ instantly acts on each particle, then at time $t + Δt$ their position will be $$ \mathbf{r} + \Delta \mathbf{r} = \mathbf{r} +\frac{\mathbf{p}}{m} \, \Delta t $$ and momentum $p + Δp = p + FΔt$. Then, in the absence of collisions, $f$ must satisfy

$$ f \left (\mathbf{r}+\frac{\mathbf{p}}{m} \, \Delta t,\mathbf{p}+\mathbf{F} \, \Delta t, t+\Delta t \right )\,d^3\mathbf{r}\,d^3\mathbf{p} = f(\mathbf{r}, \mathbf{p},t) \, d^3\mathbf{r} \, d^3\mathbf{p} $$

Note that we have used the fact that the phase space volume element $$ d^3\mathbf{r} \, d^3\mathbf{p}$$ is constant, which can be shown using Hamilton's equations (see the discussion under Liouville's theorem). However, since collisions do occur, the particle density in the phase-space volume $$ d^3\mathbf{r} \, d^3\mathbf{p}$$ changes, so

where $Δf$ is the total change in $f$. Dividing ($$) by $$ d^3\mathbf{r} \, d^3\mathbf{p} \, \Delta t$$ and taking the limits $Δt → 0$ and $Δf → 0$, we have

The total differential of $f$ is:

where $∇$ is the gradient operator, $·$ is the dot product, $$ \frac{\partial f}{\partial \mathbf{p}} = \mathbf{\hat{e}}_x\frac{\partial f}{\partial p_x} + \mathbf{\hat{e}}_y\frac{\partial f}{\partial p_y} + \mathbf{\hat{e}}_z \frac{\partial f}{\partial p_z}= \nabla_\mathbf{p}f $$ is a shorthand for the momentum analogue of $∇$, and $ê_{x}$, $ê_{y}$, $ê_{z}$ are Cartesian unit vectors.

Final statement
Dividing ($$) by $dt$ and substituting into ($$) gives:

$$\frac{\partial f}{\partial t} + \frac{\mathbf{p}}{m}\cdot\nabla f + \mathbf{F} \cdot \frac{\partial f}{\partial \mathbf{p}} = \left(\frac{\partial f}{\partial t} \right)_\mathrm{coll}$$

In this context, $F(r, t)$ is the force field acting on the particles in the fluid, and $$ is the mass of the particles. The term on the right hand side is added to describe the effect of collisions between particles; if it is zero then the particles do not collide. The collisionless Boltzmann equation, where individual collisions are replaced with long-range aggregated interactions, e.g. Coulomb interactions, is often called the Vlasov equation.

This equation is more useful than the principal one above, yet still incomplete, since $f$ cannot be solved unless the collision term in $f$ is known. This term cannot be found as easily or generally as the others – it is a statistical term representing the particle collisions, and requires knowledge of the statistics the particles obey, like the Maxwell–Boltzmann, Fermi–Dirac or Bose–Einstein distributions.

Two-body collision term
A key insight applied by Boltzmann was to determine the collision term resulting solely from two-body collisions between particles that are assumed to be uncorrelated prior to the collision. This assumption was referred to by Boltzmann as the "Stosszahlansatz" and is also known as the "molecular chaos assumption". Under this assumption the collision term can be written as a momentum-space integral over the product of one-particle distribution functions: $$ \left(\frac{\partial f}{\partial t}\right)_\text{coll} = \iint g I(g, \Omega)[f(\mathbf{r},\mathbf{p'}_A, t) f(\mathbf{r},\mathbf{p'}_B,t) - f(\mathbf{r},\mathbf{p}_A,t) f(\mathbf{r},\mathbf{p}_B,t)] \,d\Omega \,d^3\mathbf{p}_B, $$ where $p_{A}$ and $p_{B}$ are the momenta of any two particles (labeled as A and B for convenience) before a collision, $p′_{A}$ and $p′_{B}$ are the momenta after the collision, $$ g = |\mathbf{p}_B - \mathbf{p}_A| = |\mathbf{p'}_B - \mathbf{p'}_A| $$ is the magnitude of the relative momenta (see relative velocity for more on this concept), and $I(g, Ω)$ is the differential cross section of the collision, in which the relative momenta of the colliding particles turns through an angle $$ into the element of the solid angle $dΩ$, due to the collision.

Simplifications to the collision term
Since much of the challenge in solving the Boltzmann equation originates with the complex collision term, attempts have been made to "model" and simplify the collision term. The best known model equation is due to Bhatnagar, Gross and Krook. The assumption in the BGK approximation is that the effect of molecular collisions is to force a non-equilibrium distribution function at a point in physical space back to a Maxwellian equilibrium distribution function and that the rate at which this occurs is proportional to the molecular collision frequency. The Boltzmann equation is therefore modified to the BGK form:

$$\frac{\partial f}{\partial t} + \frac{\mathbf{p}}{m}\cdot\nabla f + \mathbf{F} \cdot \frac{\partial f}{\partial \mathbf{p}} = \nu (f_0 - f),$$

where $$\nu$$ is the molecular collision frequency, and $$f_0$$ is the local Maxwellian distribution function given the gas temperature at this point in space. This is also called "relaxation time approximation".

General equation (for a mixture)
For a mixture of chemical species labelled by indices $i = 1, 2, 3, ..., n$ the equation for species $$ is

$$\frac{\partial f_i}{\partial t} + \frac{\mathbf{p}_i}{m_i} \cdot \nabla f_i + \mathbf{F} \cdot \frac{\partial f_i}{\partial \mathbf{p}_i} = \left(\frac{\partial f_i}{\partial t} \right)_\text{coll},$$

where $f_{i} = f_{i}(r, p_{i}, t)$, and the collision term is

$$ \left(\frac{\partial f_i}{\partial t} \right)_{\mathrm{coll}} = \sum_{j=1}^n \iint g_{ij} I_{ij}(g_{ij}, \Omega)[f'_i f'_j - f_i f_j] \,d\Omega\,d^3\mathbf{p'},$$

where $f′ = f′(p′_{i}, t)$, the magnitude of the relative momenta is

$$g_{ij} = |\mathbf{p}_i - \mathbf{p}_j| = |\mathbf{p'}_i - \mathbf{p'}_j|,$$

and $I_{ij}$ is the differential cross-section, as before, between particles i and j. The integration is over the momentum components in the integrand (which are labelled i and j). The sum of integrals describes the entry and exit of particles of species i in or out of the phase-space element.

Conservation equations
The Boltzmann equation can be used to derive the fluid dynamic conservation laws for mass, charge, momentum, and energy. For a fluid consisting of only one kind of particle, the number density $m$ is given by $$n = \int f \,d^3\mathbf{p}.$$

The average value of any function $A$ is $$\langle A \rangle = \frac 1 n \int A f \,d^3\mathbf{p}.$$

Since the conservation equations involve tensors, the Einstein summation convention will be used where repeated indices in a product indicate summation over those indices. Thus $$\mathbf{x} \mapsto x_i$$ and $$\mathbf{p} \mapsto p_i = m v_i$$, where $$v_i$$ is the particle velocity vector. Define $$A(p_i)$$ as some function of momentum $$p_i$$ only, which is conserved in a collision. Assume also that the force $$F_i$$ is a function of position only, and that f is zero for $$p_i \to \pm\infty$$. Multiplying the Boltzmann equation by A and integrating over momentum yields four terms, which, using integration by parts, can be expressed as

$$\int A \frac{\partial f}{\partial t} \,d^3\mathbf{p} = \frac{\partial }{\partial t} (n \langle A \rangle),$$

$$\int \frac{p_j A}{m}\frac{\partial f}{\partial x_j} \,d^3\mathbf{p} = \frac{1}{m}\frac{\partial}{\partial x_j}(n\langle A p_j \rangle),$$

$$\int A F_j \frac{\partial f}{\partial p_j} \,d^3\mathbf{p} = -n F_j\left\langle \frac{\partial A}{\partial p_j}\right\rangle,$$

$$\int A \left(\frac{\partial f}{\partial t}\right)_\text{coll} \,d^3\mathbf{p} = 0,$$

where the last term is zero, since $A$ is conserved in a collision. The values of $A$ correspond to moments of velocity $$v_i$$ (and momentum $$p_i$$, as they are linearly dependent).

Zeroth moment
Letting $$A = m(v_i)^0 = m$$, the mass of the particle, the integrated Boltzmann equation becomes the conservation of mass equation: $$\frac{\partial}{\partial t}\rho + \frac{\partial}{\partial x_j}(\rho V_j) = 0,$$ where $$\rho = mn$$ is the mass density, and $$V_i = \langle v_i\rangle$$ is the average fluid velocity.

First moment
Letting $$A = m(v_i)^1 = p_i$$, the momentum of the particle, the integrated Boltzmann equation becomes the conservation of momentum equation:

$$\frac{\partial}{\partial t}(\rho V_i) + \frac{\partial}{\partial x_j}(\rho V_i V_j+P_{ij}) - n F_i = 0,$$

where $$P_{ij} = \rho \langle (v_i-V_i) (v_j-V_j) \rangle$$ is the pressure tensor (the viscous stress tensor plus the hydrostatic pressure).

Second moment
Letting $$A = \frac{m(v_i)^2}{2} = \frac{p_i p_i}{2m}$$, the kinetic energy of the particle, the integrated Boltzmann equation becomes the conservation of energy equation:

$$\frac{\partial}{\partial t}(u + \tfrac{1}{2}\rho V_i V_i) + \frac{\partial}{\partial x_j} (uV_j + \tfrac{1}{2}\rho V_i V_i V_j + J_{qj} + P_{ij}V_i) - nF_iV_i = 0,$$

where $u = \tfrac{1}{2} \rho \langle (v_i-V_i) (v_i-V_i) \rangle$ is the kinetic thermal energy density, and $J_{qi} = \tfrac{1}{2} \rho \langle(v_i - V_i)(v_k - V_k)(v_k - V_k)\rangle$  is the heat flux vector.

Hamiltonian mechanics
In Hamiltonian mechanics, the Boltzmann equation is often written more generally as $$\hat{\mathbf{L}}[f]=\mathbf{C}[f], $$ where $L$ is the Liouville operator (there is an inconsistent definition between the Liouville operator as defined here and the one in the article linked) describing the evolution of a phase space volume and $C$ is the collision operator. The non-relativistic form of $L$ is $$\hat{\mathbf{L}}_\mathrm{NR} = \frac{\partial}{\partial t} + \frac{\mathbf{p}}{m} \cdot \nabla + \mathbf{F}\cdot\frac{\partial}{\partial \mathbf{p}}\,.$$

Quantum theory and violation of particle number conservation
It is possible to write down relativistic quantum Boltzmann equations for relativistic quantum systems in which the number of particles is not conserved in collisions. This has several applications in physical cosmology, including the formation of the light elements in Big Bang nucleosynthesis, the production of dark matter and baryogenesis. It is not a priori clear that the state of a quantum system can be characterized by a classical phase space density f. However, for a wide class of applications a well-defined generalization of f exists which is the solution of an effective Boltzmann equation that can be derived from first principles of quantum field theory.

General relativity and astronomy
The Boltzmann equation is of use in galactic dynamics. A galaxy, under certain assumptions, may be approximated as a continuous fluid; its mass distribution is then represented by f; in galaxies, physical collisions between the stars are very rare, and the effect of gravitational collisions can be neglected for times far longer than the age of the universe.

Its generalization in general relativity is $$\hat{\mathbf{L}}_\mathrm{GR}[f] = p^\alpha\frac{\partial f}{\partial x^\alpha} - \Gamma^\alpha{}_{\beta\gamma} p^\beta p^\gamma \frac{\partial f}{\partial p^\alpha} = C[f],$$ where $Γ^{α}_{βγ}$ is the Christoffel symbol of the second kind (this assumes there are no external forces, so that particles move along geodesics in the absence of collisions), with the important subtlety that the density is a function in mixed contravariant-covariant $(x^{i}, p_{i})$ phase space as opposed to fully contravariant $(x^{i}, p^{i})$ phase space.

In physical cosmology the fully covariant approach has been used to study the cosmic microwave background radiation. More generically the study of processes in the early universe often attempt to take into account the effects of quantum mechanics and general relativity. In the very dense medium formed by the primordial plasma after the Big Bang, particles are continuously created and annihilated. In such an environment quantum coherence and the spatial extension of the wavefunction can affect the dynamics, making it questionable whether the classical phase space distribution f that appears in the Boltzmann equation is suitable to describe the system. In many cases it is, however, possible to derive an effective Boltzmann equation for a generalized distribution function from first principles of quantum field theory. This includes the formation of the light elements in Big Bang nucleosynthesis, the production of dark matter and baryogenesis.

Solving the equation
Exact solutions to the Boltzmann equations have been proven to exist in some cases; this analytical approach provides insight, but is not generally usable in practical problems.

Instead, numerical methods (including finite elements and lattice Boltzmann methods) are generally used to find approximate solutions to the various forms of the Boltzmann equation. Example applications range from hypersonic aerodynamics in rarefied gas flows to plasma flows. An application of the Boltzmann equation in electrodynamics is the calculation of the electrical conductivity - the result is in leading order identical with the semiclassical result.

Close to local equilibrium, solution of the Boltzmann equation can be represented by an asymptotic expansion in powers of Knudsen number (the Chapman–Enskog expansion ). The first two terms of this expansion give the Euler equations and the Navier–Stokes equations. The higher terms have singularities. The problem of developing mathematically the limiting processes, which lead from the atomistic view (represented by Boltzmann's equation) to the laws of motion of continua, is an important part of Hilbert's sixth problem.

Limitations and further uses of the Boltzmann equation
The Boltzmann equation is valid only under several assumptions. For instance, the particles are assumed to be pointlike, i.e. without having a finite size. There exists a generalization of the Boltzmann equation that is called the Enskog equation. The collision term is modified in Enskog equations such that particles have a finite size, for example they can be modelled as spheres having a fixed radius.

No further degrees of freedom besides translational motion are assumed for the particles. If there are internal degrees of freedom, the Boltzmann equation has to be generalized and might possess inelastic collisions.

Many real fluids like liquids or dense gases have besides the features mentioned above more complex forms of collisions, there will be not only binary, but also ternary and higher order collisions. These must be derived by using the BBGKY hierarchy.

Boltzmann-like equations are also used for the movement of cells. Since cells are composite particles that carry internal degrees of freedom, the corresponding generalized Boltzmann equations must have inelastic collision integrals. Such equations can describe invasions of cancer cells in tissue, morphogenesis, and chemotaxis-related effects.

title: Boltzmann equation


text:
Talk:WASD keys

Reachable keys
With one hand on the mouse, and one hand on the cursors, I can probably reach punctuation, some of the numpad and and the ins -- pgdown keys, but it's pretty difficult. What's this about being able to reach half the keys? 90.242.37.219 (talk) 12:48, 24 November 2007 (UTC)

Left-handed players
what about left handed players, dont they get a mention?!--GregLoutsenko 19:51, 6 Jun 2005 (UTC)

I'm left-handed and use the keyboard like a right handed person would. --Arm 12:49, 4 October 2005 (UTC)

I've developed an interesting way of playing games with the numpad and the arrows. I use the numpad keys 8456 to move, right arrow to jump, and down arrow to crouch. The thumb is perfect to hit the arrows in that position. And usually the "*" key will reload the weapon, and "/" is the use button. --Vittau 03:17, 14 December 2006 (UTC)

Actually they perfectly fit left handers - try for yourself and see: operating WASD with the right hand might proove somewhat difficult.;) The arrow keys were created for the masses, WASD is for the left-handed elite. INTERNAZI 20:23, 8 January 2007 (UTC)
 * Actually right-handed people are supposed to use WASD with the left hand. While left-handed people would need to use WASD with the right hand, and this is quite hard... Left-handed people out there, try out the configuration I said above.--Vittau 06:19, 4 March 2007 (UTC)

Strafing
The common difference between WASD and the Arrow keys, is that A and D normally strafe instead of turn. Is this really so? I took it out of the article, but it can be put back in. Many of the games that I've played use Arrow keys for strafing also. --pie4all88 02:05, 29 Sep 2004 (UTC)

It's true for the default settings of most modern FPS games, so should probably be added back in. Orange Goblin 17:54, 12 Jan 2005 (UTC)

Please name some, because I personally always use the left and right keys for strafing. I would guess that most people today would use he mouse for turning, not a key. 66.75.49.213 23:34, 16 October 2005 (UTC)

The entirity of the Half-Life and Counter Strike series of games has (from memory) used the left and right arrow keys to turn, but all other movement was controled by the wasd keys by default. I also recal having played other games that used the same layout, however cannot remember their names at this time. Grab some demos of FPS games and you should be able to test this yourself

Game perspective
Should the perspective of games using WSAD really be mentioned? It's popular in several top-down view games as well, usually for moving the camera while moving the character(s) by clicking your LMB. --Ashmodai 23:21, 4 May 2005 (UTC)

Origin
(Earlier discussion, which has been disproved, has been moved to the archive.) Ham Pastrami 03:04, 8 November 2007 (UTC)

Snipes Used WASD for directional firing, and was writen in 1982. Polpo 16:55, 24 August 2007 (UTC)

Terra Nova: Strike Force Centauri (1996) used WASD for movement. The early Blizzard games The Lost Vikings (1992) and Blackthorne (1994) used ESDF for action buttons -- interestingly, neither is an FPS. This claim needs and deserves research; not just people pulling for their favorite or first FPS. With no disrespect to Snipes mentioned above, you'll probably find that WASD predates FPS even if you limit candidates to notable titles. Ham Pastrami 06:02, 7 November 2007 (UTC)

System Shock in 1994 used ASDX. Ham Pastrami 14:34, 7 November 2007 (UTC)

The Wizardry article claims that the game was the first to use WASD, and since it goes as far back as 1981 this could very well be true. However, it doesn't specify exactly which title in the series was the first to do it, so we need some verification. Ham Pastrami (talk) 18:08, 22 November 2007 (UTC)

It was the first one ever released - Wizardry 1:Proving Grounds of the Mad Overlord on the Apple 2 - you can try it out with an Apple 2 emulator by downloading the dsk images here - http://www.apple2.org.za/mirrors/ftp.apple.asimov.net/images/games/rpg/wizardry_I/ —Preceding unsigned comment added by Nevster (talk • contribs) 05:00, 9 May 2008 (UTC)

Also, couple that with the fact that John Carmack was an Apple 2 programmer and D&D player - he's sure to have played Wizardry when he was growing up. —Preceding unsigned comment added by Nevster (talk • contribs) 05:10, 9 May 2008 (UTC)

WSAD and WASD
The page should be under 'WSAD' not 'WASD' which is how most gamers refer to it L1nX 15;18, 7 December 2005 (UTC)
 * Most? I highly doubt it. You can't even say "wsad" because it sounds awkward.  Grue   16:25, 7 December 2005 (UTC)
 * I'm saying "WSAD" because in Polish it is simpler and shorter to say than "WASD". Also in Polish Wiki this article is under WSAD title. I think it is a matter of language, not "most gamers" opinion. Hołek ҉ 17:10, 27 June 2006 (UTC)
 * If anything, WSAD should forward to WASD. I use "WSAD" myself but most people I know use "WASD". (Personally, I play using EDSF.) --- Trevie 17:39, 8 December 2005 (UTC)

Are you sure you're not thinking of WSAD - the IBM Java development tool? —Preceding unsigned comment added by Nevster (talk • contribs) 05:08, 9 May 2008 (UTC)

Well, I have heard of these 4 keys as "ASWD" keys ... in czech language (and maybe some others) it is easier pronouncable than WASD or WSAD. Personally I use YGHJ, as I have roughly equal number of usable keys available on both sides of hand. --Bilboq 20:52, 3 August 2006 (UTC)

If this was pl.wikipedia, then WSAD would be correct. If this was cz.wikipedia, ASWD would be correct. However this is en.wikipedia, and common usage in english speaking countries is WASD; the interlanguage links point at the right places, but this is correct as it stands. --Firi e n § 14:10, 21 September 2006 (UTC)

In the US, I have heard people use ASWD derogatorily -- it is pronounced "ass wad". Ham Pastrami 10:34, 7 November 2007 (UTC) Plus, I like the sound of wasd more than wsad. the most gamers that guy was talking about are usually the extremely immature and small crowd of people who talk in leet speak. the same people spell "the" as teh, and other purposeful typos and speak in bad grammar like "all your base are belong to us" instead of " All of your bases now belong to us" or some other grammatically proper phras —Preceding unsigned comment added by 71.201.151.133 (talk) 22:04, 10 January 2008 (UTC)

User box
Here is a silly template I made. Feel free to add it to your own user page, or copy the source and edit it to make a box reflecting your own control preference. Ham Pastrami (talk) 10:16, 20 January 2008 (UTC)

Template: User ESDF —Preceding unsigned comment added by Ham Pastrami (talk • contribs) 10:18, 20 January 2008 (UTC)

Article scope
I think the article's scope is poorly defined. Is any combination of 4 keys considered to be WASD-like? What are we actually trying to address with this article? Perhaps we should consider renaming this to Movement keys. Ham Pastrami (talk) 06:06, 10 February 2008 (UTC)

Mouse as forwards
We have neglected to address the small minority of game players who use the right mouse button to move forwards. —Preceding unsigned comment added by 125.236.202.220 (talk) 22:31, 5 March 2008 (UTC)

title: Talk:WASD keys


text: User talk:69.109.56.119

title: User talk:69.109.56.119


text:
Battle of Killdeer Mountain

The Battle of Killdeer Mountain (also known as the Battle of Tahkahokuty Mountain) took place during Brig. Gen. Alfred Sully's expedition against the Sioux in Dakota Territory July 28–29, 1864. The location of the battleground is in modern Dunn County, North Dakota. With a total of more than 4,000 soldiers involved in the total operation, and more than 2,000 in the battle, Sully's expedition was the largest ever carried out by the U.S. army against Native Americans.

Background
In the aftermath of the Dakota War of 1862, the U.S. government punished the Sioux, including those who had not participated in the war. Large military expeditions into Dakota Territory in 1863 pushed most of the Sioux to the western side of the Missouri River at least temporarily and made safer, although not entirely safe, the frontier of white settlement in Minnesota and the Dakotas. Four whites were killed by Sioux raiders in the spring of 1864.

An important impetus to another military campaign against the Sioux was the desire to protect lines of communication with recently discovered goldfields in Montana and Idaho. The lifeline for the American gold miners were steamboats plying the Missouri River through the heart of Sioux territory. During the winter of 1863–1864, Sully's superior, Major General John Pope ordered Sully to establish several forts along the Missouri River and in the eastern Dakotas to secure the communication routes to the goldfields and to eliminate the Sioux threat to the settlers east of the Missouri River.

Sully's First Brigade, consisting of up to 1,700 men, followed the Missouri River from its starting point at Sioux City, Iowa. The Second Brigade with about 1,550 men would march overland from Fort Ridgely in Minnesota. On the march up the Missouri, the Sioux killed one soldier and wounded another. The three Sioux perpetrators were caught, killed, and decapitated. Additional soldiers and civilians with 15 steamboats chugged up the Missouri River to support the army on the ground.

Sully's two columns of soldiers united on June 29 and on July 7 he established Fort Rice on the Missouri River in North Dakota as a base, supplied by steamboat, for his military expedition. His scouts, Winnebago and friendly Sioux and mixed-bloods, informed him of a large encampment of Sioux 130 miles northwest near the Little Missouri River. On July 19, he and his men departed Fort Rice to search for the Sioux encampment. Sully was encumbered by a wagon train of 200 miners and their families headed for the goldfields whom he reluctantly agreed to protect and escort.

Sully's scouts reported 1,500 to 1,800 tipis in the Sioux encampment. Sully believed he would be faced by 5,000 to 6,000 warriors. The Sioux later claimed they had 1,600 warriors in the battle – likely closer to the truth with a calculation of one to two adult males per tipi. The Sioux in the encampment consisted mostly of Lakota (Teton) from the Hunkpapa, Sihasapa, Miniconjou, and Sans Arc bands plus Yanktonais, and a few Santees. The Sioux were mostly armed only with bows and arrows and a few short-range muskets and shotguns. Many of the Sioux, especially the Tetons, had not been hostile to the U.S. before this encounter. Sully, after leaving men at Fort Rice and to guard the emigrants, had 2,200 men for the attack. He also had two artillery batteries with eight howitzers. On July 26, Sully's Indian Scouts skirmished with 30 Sioux warriors near present-day Richardton, North Dakota and one scout was wounded. With the Sioux now aware of his presence, Sully advanced rapidly but carefully. On the morning of July 28, scout Frank LaFramboise, a mixed blood Santee, informed Sully of the location of the large Sioux encampment 10 miles ahead.

Killdeer Mountain was at the edge of the Dakota badlands, cut up by "deep, impassable ravines" and "high rugged hills." Realizing that a cavalry charge would be difficult in the broken terrain Sully dismounted his soldiers and formed them in a hollow square, one mile and a quarter (2 km.) per side. His horses and artillery were sheltered inside the square. He advanced on foot, as the Sioux on horseback formed up in groups on Sully's flanks and on hilltops.

Battle
The two sides, Sully' soldiers drawn up in a hollow square and Native forces scattered around the hills, exchanged insults at long distance. One warrior, a Hunkpapa named Lone Dog rode within rifle range of the soldiers, taunting them. Sully ordered him shot by sharpshooters. Accounts differ as to whether Lone Dog was killed or unscathed.

With the first shots fired at Lone Dog, the soldiers advanced with a skirmish line and the Sioux darted at the flanks of the army, seeking weak spots. Artillery fire discouraged the Sioux from congregating in large numbers. A thrust at Sully's rear was broken up by an artillery shell that felled several of the warriors. Sully's square of soldiers advanced steadily. The Sioux quickly realized that they could not hope to turn the soldiers back and they shifted their focus to packing up their tipis and equipment and protecting the flight of their women and children.

Attempting to halt Sully's advance, the Sioux mounted charges on his right and left flanks, the Yanktonai and Santee attacking on the right and the Teton on his left. Major Alfred B. Brackett and his Minnesota Battalion on the right mounted their horses and launched a counter-charge, supported by artillery. He scattered the Native forces after close quarters fighting with sabers and pistols. A renowned hero of the frontier and the Civil War, Lt. George Northrup, was killed in the charge.

It was getting dark as Sully neared the Sioux village. He halted his men for the night, but continued his artillery bombardment of the Sioux and their village. The Sioux fled or fought delaying actions, abandoning most of their tipis and property.

Sully's casualties for the day were 3 killed and 10 wounded. He estimated Sioux casualties of 100 to 150 dead, nearly all of them warriors. The Sioux claimed they suffered 31 dead.

Aftermath
The day after the battle, the Sioux having abandoned their encampment, Sully detailed 700 men to destroy all they had left behind. This included tipis, large supplies of dried buffalo meat (jerky), and up to 3,000 dogs which were shot. A few Sioux, including children, left behind in the camp were killed by the Winnebago scouts.

Most of the Sioux scattered through the Dakota Badlands to the west of Killdeer Mountain, but some remained near Sully. Several Sioux on a hilltop waved a white flag requesting talks but they were fired on by soldiers and fled. That night two of Sully's picket guards were killed and one wounded by a Sioux war party. Another soldier was killed by guards when he was mistaken for an enemy.

Although running short of rations, Sully decided to continue his pursuit of the Sioux. A Blackfoot scout said he knew a route through the Badlands passable by Sully's wagon train. After two days rest, Sully and his men plunged into the unknown terrain ahead. The Sioux would harass their passage in the Battle of the Badlands.

United States
Department of the Northwest: MG John Pope (not present in the field)

Native Americans

 * Lakota (Teton), and Dakota (Yanktonai, Santee) Sioux: Gall, Sitting Bull, Inkpaduta

Killdeer Mountain Battlefield State Historic Site
Killdeer Mountain Battlefield State Historic Site marks part of the battlefield site and is protected by the State Historical Society of North Dakota. This features a sandstone slab monument, flagpole, and two headstones that honor soldiers killed in the conflict, Sergeant George Northrup, Company C, and Private Horace Austin, Company D, Brackett's Battalion, Minnesota Cavalry. The site is located 8.5 miles northwest of Killdeer, North Dakota.

title: Battle of Killdeer Mountain


text:
Western Region

Western Region or West Region may refer to:

Places

 * Al Gharbia, Abu Dhabi, the Western Region
 * Western Region, Bahrain
 * Western Region, Eastern Cape, South Africa
 * Western Region, Ghana
 * Western Region (Iceland)
 * Western Region, Nepal
 * Western Region, Nigeria (former)
 * Western Region, Serbia
 * Western Region, Uganda
 * Western Regions, a historic name for central Asia
 * West Region, Cameroon
 * West Region, Ireland
 * West Region, Singapore
 * Western Krai of the former Russian Empire
 * West Bengal, a state in eastern India, the western part of the Bengal region

Other

 * Western Region (Boy Scouts of America), one of the large geographic divisions of the Boy Scouts of America
 * Western Region of British Railways
 * Western Region Football League, an Australian rules football semi-professional league

title: Western Region


text: User talk:68.199.54.193

title: User talk:68.199.54.193


text:
User talk:Naresuan~enwiki

Hello and welcome to Wikipedia!

Here are some tips to help you get started:

 * Try the Tutorial, and feel free to experiment in the test area.
 * If you need help, post a question at the Help Desk
 * Eventually, you might want to read the Manual of Style and Policies and Guidelines.
 * Remember Neutral point of view
 * Explore, be bold in editing pages, and, most importantly, have fun!

Good luck!

[[User:Meelar|Meelar (talk)]]

P.S. One last helpful hint. To sign your posts like I did above (on talk pages, for example) use the '~' symbol. To insert just your name, type ~~~ (3 tildes), or, to insert your name and timestamp, use ~~~~ (4 tildes).

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Naresuan. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Naresuan~enwiki that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name. If you think you might own all of the accounts with this name and this message is in error, please visit Special:MergeAccount to check and attach all of your accounts to prevent them from being renamed.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 02:05, 20 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 16:48, 22 April 2015 (UTC)

title: User talk:Naresuan~enwiki