MediaWiki API result

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            "*": "Subscribe to the mediawiki-api-announce mailing list at <https://lists.wikimedia.org/mailman/listinfo/mediawiki-api-announce> for notice of API deprecations and breaking changes."
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            "*": "Because \"rvslots\" was not specified, a legacy format has been used for the output. This format is deprecated, and in the future the new format will always be used."
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            "2793": {
                "pageid": 2793,
                "ns": 0,
                "title": "Reentry",
                "revisions": [
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                        "*": "'''Reentry''' is in spaceflight the process of (re-)entering a atmosphere from space. Commonly this term means to reduce the very high speed by drag, requiring heavy [[Heat shield|heat shields]]. But its also possible to slow the speed down using propulsion systems, with very high fuel costs.\n\nFor aerodynamic reentry, there are three major strategies available:\n* Ballistic reentry (eg Mercury)\n* Gliding reentry (eg Gemini, Apollo, Soyuz and [[STS]] )\n* Skip reentry (eg Zond)\n\n==Aerodynamic basics==\n\nAny object moving through the atmosphere usually creates two forces: [[Lift]] and [[Drag|drag]]. Even a sphere can create lift, if it rotates. The drag vector is always in the opposite direction of the [[Airspeed|airspeed]] vector, the lift vector always orthogonal to the drag vector (yes, that means the lift vector can point in many directions).\n\nDrag slows the vessel down, lift changes its trajectory. \n\nThere are two types of lift:\n* Positive lift, means the lift vector points away from the surface.\n* Negative lift, means the lift vector points to the surface.\n\nThe kinetic energy the spacecraft loses during reentry gets conserved by heating the air and the outside of the spacecraft.\n\nOne very important value in atmospheric flight is the [[dynamic pressure]], which is defined as the product of density (<math>\\rho</math>) and velocity (v) squared, multiplied by <math>\\frac{1}{2}</math>:\n\n<math>p_d = \\frac{1}{2} \\cdot \\rho \\cdot v^2</math>\n\nThe product of dynamic pressure and the velocity is called the [[aerodynamic heatflux]] - it's the energy the spacecraft puts into the air for heating it and its hull. \n\n<math>Q = p_d \\cdot v = \\frac{1}{2} \\cdot \\rho \\cdot v^3</math>\n\nA typical satellite is designed for only withstanding 1800 W/m\u00b2 - thats the same energy it can get from the sun during solar maximum.\n\n===Ballistic coefficient===\n\nThe ballistic coefficient is a value to tell how much a object is affected by drag and lift.\n\n\n===Relation between descent rate and dynamic pressure===\n\nThe most important task during reentry is to control heating and aerodynamic loads on the spacecraft. Both values are linked to the dynamic pressure and the velocity of the spacecraft. \n\nThe dynamic pressure is a function of speed and air density (which depends on altitude). As such, it stays constant, if the speed decreases faster, as the air density increases:\n\n<math>v = \\sqrt{\\frac {2 \\cdot p_d}{\\rho}}</math>\n\nIf the density increases by 4, the velocity has to be reduced by 50% to keep the same dynamic pressure, and thus, the same deceleration (as deceleration is proportional to dynamic pressure). \n\nThat also means: If the spacecraft descends faster than a special descent rate, the deceleration and heating increases, if the spacecraft descends slower than this rate, the deceleration drops.\n\n==Ballistic reentry==\n\nThe ballistic reentry is the simplest strategy. The spacecraft just drops into the atmosphere and uses only drag for slowing down. For this strategy it is important to neutralize any lift, as negative lift would be very bad for the spacecraft. This is usually done by rotating the capsule slowly. Temperatures range from 3,500 \u00b0F (1,926 \u00b0C) up to as high as 6,000 \u00b0F (3,315 \u00b0C)\n\nDuring a ballistic reentry, if the reentry angle is big enough, the trajectory forms a straight line, because inertia and drag are much higher than the gravity of the planet.\n\n==Gliding reentry==\n\nA gliding reentry makes use of lift to control the trajectory through the atmosphere. The craft does not need much lift to do such a reentry, but it needs to control its lift vector. For controlling the lift vector, a vessel has two possible ways: By changing the AOA and by banking the craft. \n\nWith the angle of attack, the vessel only changes the amount of lift available (including to negative lift), while the full range of directions are possible by banking the craft. That's why the AOA is kept constant for most vessels at the ideal value for a given speed and altitude, while the trajectory gets controlled by banking the craft. This leads to the typical S-turn trajectory of such vessels. \n\nThe craft stays in the atmosphere all the time, unlike the skipping reentry. The gliding reentry is the most effective reentry strategy in terms of complexity and effect.\n\n==Skipping reentry==\n\nThe skipping reentry gets used if a long reentry ground track is possible and a lot of velocity has to be lost. The spacecraft enters the atmosphere, slows down, but leaves it again on a suborbital trajectory.\n\n[[Category: Articles]]\n[[Category: Glossary]]"
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            "1450": {
                "pageid": 1450,
                "ns": 0,
                "title": "References",
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                        "*": "==General rocket engines==\n\n*'''PWR Engineering Threshold Journal - \"Turbopumps for Liquid Rocket Engines\"''' [http://www.rocketdynetech.com/articles/turbopump.htm] Very detailed explanation of rocket engine turbo pumps and their complexity.\n\n==ISS==\n* '''Description of the Common Berthing Mechanism''' [http://spacecraft.ssl.umd.edu/design_lib/ICES01-2435.ISS_CBM.pdf]\n* '''Mars Center''' [http://www.marscenter.it/eng/veicol.asp?pa=605] Homepage with lots of 1:100 paperscale models of [[ISS]], [[space shuttle]] and [[Soyuz]].\n*'''Space Station User's Guide''' [http://www.spaceref.com/iss/ops/sm.comp.system.man.controls.pdf] Detailed info about the computer displays, systems and procedures.\n\n==Soyuz==\n*'''Suzy's Russian Space Site'''[http://suzymchale.com/kosmonavtka/index.html] Lots of information on Baikonur and the Soyoz and Proton programs. A wealth of info on the Russian space program in general!\n*'''Samara Space Center''' [http://www.samspace.ru/ENG/index.htm] The manufacturer of the Soyuz launch vehicle and its various upper stages.\n*'''Sven's Space Place''' [http://www.svengrahn.pp.se/histind/RvDRadar/IGLA.htm] The IGLA radio system for rendez-vous and docking\n\n==Space Shuttle, STS==\n*'''NASA drawings of the Space Shuttle''' [http://www.spaceflight.nasa.gov/shuttle/reference/sodb/] detailed plans in PDF format\n*'''NASA Shuttle Flight Data Files''' [http://www.nasa.gov/centers/johnson/news/flightdatafiles/index.html]\n*'''Scaled Drawings of the Space Shuttle'''[http://models.lemut.net/drawings/Space_Shuttle/index.html] 1:200 scale drawings\n*'''Clip Art from NASA'''[http://www.dfrc.nasa.gov/Gallery/Graphics/STS/index.html] Images of the Shuttle (and most of the other craft flown at Edwards from the 1940's to present) \n*'''Historic SpaceSystems'''[http://www.space1.com/Spacecraft_Data/Handbook_Illustrations/Space_Shuttle/Orbiter_Dimensions/orbiter_dimensions.html ] detailed drawings with dimensions of the Shuttle.\n*'''Data Processing System Dictionary''' [http://shuttlepayloads.jsc.nasa.gov/training/pdf/DPSj4.pdf] Contains detailed descriptions of the CRT displays shown in the shuttle.\n\n==Collections, Miscellaneous==\n*'''Space Launch Vehicles''' [http://www.b14643.de/Spacerockets_1/index.htm]detailed information and specs about launchers, space centers, rocket engines, etc. Essential performance data about the various rocket engines used from all the countries in the world.\n*'''Capcom Espace''' [http://www.capcomespace.net/] detailed description of the various world space programs, with detailed diagrams and high resolution photos (in French).\n*'''NASA Dryden Graphics'''[http://www.dfrc.nasa.gov/Gallery/Graphics/] Hundred of drawings of various aircraft flown at Dryden Test Center (Edwards).\n*'''Ninfinger Productions'''[http://www.ninfinger.org/~sven/models/vault2004/index.html] Mailing list archive with lots of drawings and photographs about spaceflight.\n*'''The Blueprint Collection'''[http://the-blueprints.com/blueprints/modernplanes/] A collection of drawings of aircraft and other vehicles.\n*'''Simviation''' [http://www.simviation.com/designresources.htm ] A link page for three view drawings of historic aircraft.\n*'''Dimensions of the Human Figure'''[http://www.jneuhaus.com/human.html] Useful for the designer of cockpits and spacecraft.\n*'''Vessel Aerodynamics''' [[Vessel aerodynamics|A brief description]] of how aerodynamics are modelled in Orbiter.\n*'''ISS Acronyms and Abbreviations''' [[ISS:List of Acronyms and Abbreviations|Specific]] to the International Space Station.\n*'''Russian glossary''' [[Russian glossary|of important words]] from Russian spaceflight.\n*'''Atomic Rockets''' [http://www.projectrho.com/rocket/index.html] Resource for SF writers; good info for anyone interested in rocket engines; great SciFi pictures!\n*'''Roskosmos''' [http://www.roscosmos.ru/index.asp] The Russian federal space agency.\n*'''MARS center - paper scale models''' [http://www.marscenter.it/eng/veicol.asp?pa=605] High quality paper scale models of ISS and related space hardware.\n*'''Simple Hohmann Calculator''' [http://home.att.net/~ntdoug/smplhmn.html] Calculate Hohmann transfers between Orbits on various bodies.\n\n[[Category: Articles]]"
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