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milstar: http://www.ucsusa.org/assets/documents/nwgs/section_6.pdf To maneuver, a satellite in orbit must use rocket engines (thrusters) to change the magnitude or direction of its velocity. Because the orbital speed of satellites is so large, the velocity changes required for maneuvering may also be large, requiring the thrusters to use large amounts of propellant. How much and how quickly a satellite can maneuver depends on the amount and type of propellant it carries. There are practical limits to the amount of propellant a satellite can carry since it increases the total mass that must be launched into orbit. These constraints on maneuvering in space have important consequences for satellite operations. This section discusses the different types of satellite maneuvers and the changes in satellite velocity required for each. Section 7 outlines the amount of propellant required for these maneuvers. Three basic maneuvers are used to change orbits: (1) changing the shape or size of an orbit within the orbital plane; (2) changing the orbital plane by changing the inclination of the orbit; and (3) changing the orbital plane by rotating the plane around the Earth’s axis at constant inclination. (Recall that all satellite orbits lie in a plane that passes through the center of the Earth.) We discuss each of these in more detail below, as well as several common orbital changes that use these basic maneuvers. Maneuvers within the orbital plane allow the user to change the altitude of a satellite in a circular orbit, change the shape of the orbit, change the orbital period, change the relative location of two satellites in the same orbit, and de-orbit a satellite to allow it to return to Earth. A velocity change is typically referred to as delta-V, or DV, since the term “delta” is commonly used in technical discussions to indicate a change in some quantity. In addition, as Section 7 shows, generating a velocity change of 2 km/s ################################################ with conventional propulsion technologies would require a satellite to carry its own mass in propellant—thus doubling the mass of the satellite. ############################################# Table 6.1. This table shows the change in satellite velocity (DV) required for various types of maneuvers and activities in space, where Dq is the change in inclination. Type of Satellite Maneuver Required DV (km/s) Changing orbital altitude within LEO (from 400 to 1,000 km) 0.3 Stationkeeping in GEO over 10 years 0.5–1 De-orbiting from LEO to Earth 0.5–2 Changing inclination of orbital plane in GEO by Dq = 30° 2 by Dq = 90° 4 Changing orbital altitude from LEO to GEO (from 400 to 36,000 km) 4 Changing inclination of orbital plane in LEO by Dq = 30° 4 by Dq = 90° 11 These numbers are calculated in the Appendix to Section 6. (LEO = low earth orbit, GEO = geosynchronous orbit)
milstar: ychebnik MAI sputnikowie sistemi navigazii 300 str na russkom jazike smotri sistemi koordinat so str 28 5 http://www.aerokos.ru/navigation/SNS.pdf Bolschaja poluos ellipsoida Zemli M -6378136 metra GRawit konstanta - 398600.44 *10^9 klassischeskie elementi orbit str.38 s grafikom
milstar: Для жилых зданий, высота которых неизвестна, но известна этажность, общая высота вычисляется по формуле, рекомендуемой специалистами Совета по высотным зданиям и городской среде: для жилых зданий и отелей высота этажа принимается равной 3,1 м, для офисных — 3,9 м, для многофункциональных — 3,5 м[1]. http://ru.wikipedia.org/wiki/%D0%9D%D0%B5%D0%B1%D0%BE%D1%81%D0%BA%D1%80%D1%91%D0%B1%D1%8B_%D0%A0%D0%BE%D1%81%D1%81%D0%B8%D0%B8 Pri yglax elevazii 75 ° ,cos =0.2588 Sputnik budet imet prjamuju widimost ( s odnoj iz storon) ylizax schirinoj wsego 10.1 metra , zastroennix 10 etaznimi oofisnimi po 3.9 metra =39 metra ili s ljuboj tochki pri schirine 20.2 metra ********************************** http://www.mall-academy.ru/articles/gum/changes-on-the-moscow-shopping-streets-in-17th-century.php 21 мая 1626 года царь Михаил Федорович и патриарх Филарет Никитич издали указ, в котором говорилось, что на территории московского Кремля большие улицы, идущие мимо каменных крепостных стен, следует оставить без изменений. Ширина улиц, проходящих мимо деревянных стен к Никольским и Ризположенским воротам, составляла полшесты сажени. Ширина улицы, которая проходит мимо каменных стен и двора князя Федора Ивановича Мстиславского к водяным воротам, составляла более 10 метров. Примерно такую же ширину имели улицы с дворами Дохтурова Фалентина, боярина Федора Ивановича Шереметьева, князя Бориса Михайловича Лыкова, князя Ивана Голицына, поповских дворов и Симоновского монастыря. Ширина переулков доходила до 8 метров. Ширина улицы между Чудовским монастырем и Чудовскими конюшнями составляла около 10 метров. Районы от Никольских ворот до Вознесенского монастыря, от Фроловских ворот до круглых башен, и от круглых башен до водяных ворот оставили без изменений. В Китай-городе на расстоянии от Никольских до Сретенских ворот и от Васильевских до Водяных ворот ширина от городских построек до городской стены должна была составлять около 5 метров. Расстояние от Сретенских до Ильинских, Варварских и Васильевских ворот оставили без изменений. Ширину улиц Никольской, Ильинской и Варварской не изменяли в тех районах, где улицы проходили между каменных построек. Районы с деревянными постройками расширили до 12 метров. Ширина Зачатской улицы составляла более 8-ми метров, так как она была не проезжая. Переулки, связывающие улицы, имели ширину 8 метров, а тупики и переулки – по 4 метра. http://www.gai.ru/press/news17349.htm Московские власти планируют расширить ряд улиц в центральном округе столицы.Речь идет, в частности, о Малой Пироговской улице и улице Россолимо их ширина будет увеличена с 10,5 до 12 метров, Оболенском переулке (с 10 до 14 метров). Также будут расширены Языковский переулок (с 7 до 14 метров), Малая Трубецкая улица (с 9 до 14 метров) и Несвижский переулок (с 6,5 до 9 метров). Помимо этого планируется расширение Ростовской набережной на участке от 1-ого Вражского переулка до Бородинского моста (с 14,25 до 22,5 метра) http://slovari.yandex.ru/~%D0%BA%D0%BD%D0%B8%D0%B3%D0%B8/%D0%AD%D0%BD%D1%86%D0%B8%D0%BA%D0%BB%D0%BE%D0%BF%D0%B5%D0%B4%D0%B8%D1%8F%20%C2%AB%D0%9C%D0%BE%D1%81%D0%BA%D0%B2%D0%B0%C2%BB/%D0%95%D0%BB%D0%B8%D0%B7%D0%B0%D0%B2%D0%B5%D1%82%D0%B0%20%D0%9F%D0%B5%D1%82%D1%80%D0%BE%D0%B2%D0%BD%D0%B0/ По указу 22 мая 1742 ширина улиц в Москве должна быть не менее 8 саженей, переулков — 4 саженей. За соблюдением указов следил «архитекторский класс» (архитектор и 4 помощника). Следствием больших пожаров 1748 и 1752 стал указ, устанавливавший ширину улиц в 10 саженей, переулков — 6 саженей. (sazen w 18 weke - 2.13 -2.16 metra ) http://www.stroimsja.ru/ulica-gorkogo-v-proshlom-i-nastojaschem.html Эта часть улицы Горького при запроектированной ширине в 55— 59 м будет застроена 6—7-этажными домами, средней высотой в 30 м. Та-ким образом, отношение ширины улицы к высоте застройки составит 1,75//—2,0//, что отвечает гигиениче-ским и архитектурным требованиям. Вновь возводимые корпуса равны по длине новым укрупненным кварта-лам, которые они оформляют.
milstar: 24 декабря 2006 г. в 11:34:44.402 ДМВ (08:34:44 UTC) с 1-го Государственного испытательного космодрома МО РФ Плесецк, с ПУ №4 «Санкт-Петербург» площадки №43, боевыми расчетами Космических войск (КВ) РФ был осуществлен пуск ракеты-носителя «Союз-2-1А» (14А14) №76033135 с разгонным блоком «Фрегат» (14С44) №1012. На орбиту был успешно выведен новый связной космический аппарат «Меридиан» (№11Л). Отделение КА «Меридиан» от РБ состоялось в 18:32 ДМВ в зоне радиовидимости средств российского командно-измерительного комплекса. Параметры орбиты спутника после отделения от РБ составили: наклонение – 62.83°; минимальная высота – 1018 км; ********************************** Yazwimo dlja ASAT . Wisotu nad zemlej perigeja neobxodimo ywelichit максимальная высота – 39820 км; период обращения – 727.0 мин. Основные особенности КА «Меридиан» Отвечая на вопрос о назначении запущенного КА и его отличиях от спутников, используемых сегодня, В.А.Поповкин рассказал, что группировка КА «Меридиан» будет заменять группировки трех различных связных аппаратов: «Молния-3», «Молния-1» и «Парус». Его основные отличия таковы: по сроку активного существования у названных аппаратов ресурс полтора, два и один год соответственно; у «Меридиана» – 7 лет; - по полезной нагрузке – на указанных КА по одному ретранслятору, на «Меридиане» – три, причем не прежние, а модифицированные, под новые сроки службы; - по мощности – на «Молниях» по 1 кВт, на «Парусе» всего 700 Вт, здесь – 3 кВт; естественно, другие, большие солнечные батареи (СБ). http://www.iss-reshetnev.ru/?cid=mass_media&nid=189 ******************************* Спутник связи Меридиан выведен на орбиту 2 ноября 2010 г. Космические войска осуществили успешный пуск ракеты-носителя Союз-2.1а, оснащенной разгонным блоком Фрегат. Пуск, в ходе которого на орбиту был доставлен спутник связи двойного назначения Меридиан, был произведен в 03:58:39 мск (00:58:39 UTC) с пусковой установки №3 площадки №43 космодрома Плесецк. В 06:13 мск спутник был выведен на расчетную орбиту. КА Меридиан получил международное обозначение 2010-058А и зарегистрирован в каталоге Космического командования США под номером 37212. Согласно сообщению производителя, НИИ им. Решетнева, КА выведен на расчетную орбиту и работает в штатном режиме. Параметры орбиты КА: наклонение 62.8 градусов, перигей 966 км, апогей около 39800 км и период обращения 726 минут. Это третий КА в серии спутников связи Меридиан. Первый пуск был произведен в декабре 2006 г., второй - в мае 2009 г. http://russianforces.org/rus/blog/2010/11/sputnik_svyazi_meridian.shtml
milstar: Awtorpredpolagaet chto orbitalnij period y sputnika Meridian skoree 717 minut kak ykazanno w zarubeznix istochnikax ##################################### a ne 727 minut ,kak w rossijskix (smotri wische) MERIDIAN 3 can be found in the following categories: Military NORAD ID: 37212 Int'l Code: 2010-058A Perigee: 964.5 km Apogee: 39,400.2 km Inclination: 62.8° Period: 717.7 min Semi major axis: 26,553.3 km Launch date: November 2, 2010 Source: Commonwealth of Independent States (former USSR) (CIS) Comments: MERIDIAN 3 is a Russian military communications satellite. http://www.n2yo.com/satellite/?s=37212
milstar: В.А.Поповкин заявил, что полную группировку из четырех «Меридианов» планируется развернуть в 2009 г. Запускать резервные КА нет необходимости, так как срок гарантированного активного существования достаточно велик. А когда гарантийный срок истечет, «Меридианы» устареют и будут заменяться новыми. Командующий сказал, что гарантия на «Меридиан» установлена на 7 лет, а не на традиционные уже десять, из-за того, что его орбита высокоэллиптическая и 4 раза в сутки он проходит сквозь радиационные пояса. Это одна из основных причин, по которой конструкторы были вынуждены сделать совершенно новую базовую платформу герметичной. На «Меридианах» стоит не аналоговая аппаратура, как на «Молниях», а цифровая, и ее проще защитить от различных заряженных частиц в гермоконтейнере. http://www.novosti-kosmonavtiki.ru/content/numbers/289/16.shtml - по сроку активного существования у названных аппаратов ресурс полтора, два и один год соответственно; у «Меридиана» – 7 лет; - по полезной нагрузке – на указанных КА по одному ретранслятору, на «Меридиане» – три, причем не прежние, а модифицированные, под новые сроки службы; - по мощности – на «Молниях» по 1 кВт, на «Парусе» всего 700 Вт, здесь – 3 кВт; естественно, другие, большие солнечные батареи (СБ). Neobxodimo rassmotret varianti 4 tjazelix sputnikow ili 8 srednix w poslednem sluschae mozno poluchit ygli elevazii 75-80 ° ( widen pri schirine ylizi 10 metrow i wisote zdanij 56.7 metra) grad na schirotax okolo 56 ° ot SPB do Krasnojarska kruglosutochno ##################################################
milstar: The challenge of entering, or reentering, the Earth’s atmosphere is not new. For years, NASA has successfully designed vessels that have endured the harsh process of reentry. However, in most cases, this is made possible only through the act of over-engineering; designing to withstand conditions far beyond what is expect to be encountered and moving on to concentrate on other objectives. http://spacegrant.colorado.edu/symposium/papers/CUSRS11_16%20Reentry%20Experiment%20SAT_X.pdf Sfera massoj 1 kg i 0.007 kw.metra swobodno padaet s wisoti 120 km ############################################## na wisote 100 km skorost - 600 metr/sec na wisote 40 km skorost maximalna - 1200 metr/sec na wisote 20 km skorost padaet do -400 metr/sec pri wstreche s Zemlej padaet do menee 100 metr/sec
milstar: Blunt body entry vehicles Various reentry shapes (NASA) using shadowgraphs to show high velocity flow These four shadowgraph images represent early reentry-vehicle concepts. A shadowgraph is a process that makes visible the disturbances that occur in a fluid flow at high velocity, in which light passing through a flowing fluid is refracted by the density gradients in the fluid resulting in bright and dark areas on a screen placed behind the fluid. In the United States, H. Julian Allen and A. J. Eggers, Jr. of the National Advisory Committee for Aeronautics (NACA) made the counterintuitive discovery in 1951[3] ################################ that a blunt shape (high drag) made the most effective heat shield. ##################################### From simple engineering principles, Allen and Eggers showed that the heat load experienced by an entry vehicle was inversely proportional to the drag coefficient, i.e. the greater the drag, the less the heat load. Through making the reentry vehicle blunt, air cannot "get out of the way" quickly enough, and acts as an air cushion to push the shock wave and heated shock layer forward (away from the vehicle). Since most of the hot gases are no longer in direct contact with the vehicle, the heat energy would stay in the shocked gas and simply move around the vehicle to later dissipate into the atmosphere. The Allen and Eggers discovery, though initially treated as a military secret, was eventually published in 1958.[4] http://www.enotes.com/topic/Atmospheric_entry
milstar: http://www.fas.org/nuke/intro/missile/basics.htm RVs possess a tremendous amount of kinetic energy, which must be dissipated during reentry as the vehicles decelerate to their impact or landing velocity.The RV reenters the Earth's atmosphere at velocities of up to Mach (M) 25. As the RV passes through the atmosphere, atmospheric friction decelerates it to below M 1, and converts its kinetic energy primarily into thermal energy (heat). Within the stagnation zone, an area immediately in front of the RV, an area of compressed, extremely hot, ionized and stagnant air is formed. Heat from the hot gas is transferred to the surface of the RV. The heat generated during reentry is not only dependent on atmospheric density, but is also inversely proportional to the square root of the radius of the RV's nose cone and proportional to the cube of its velocity. Hence, blunt nose RVs are heated less than slender ones; and lifting RV designs, which use the glider principle, produce less heat than ballistic hyperbolic descent designs because their velocity is typically lower. Thus, a full evaluation of thermal impacts during reentry is dependent on both vehicle- and mission-specific criteria. Temperatures generated within the hottest area (the stagnation zone) during ballistic reentry may exceed 11,100�C (20,000�F). Heat generation is not as severe on vehicles which are capable of some degree of lift during reentry; the temperature of the Apollo capsule surface reached about 2,760�C (5,000�F). Thermal protection systems are required for RVs to ensure the vehicle does not burn up during reentry. The choice of systems to be used is dependent upon the vehicle design, the reentry temperatures the RV may be subject to, and mission-specific requirements of the warhead. Thermal protection systems for the exterior of RVs which may be feasible include ablation, radiative heat shield, heat sink, transpiration, and radiator. However, to date, heat sink, transpiration, and radiator systems have not been used to protect the exterior surface of RVs from the thermal stress of reentry. Ablation cooling or simple ablation is a process in which heat energy is absorbed by a material (the heat shield) through melting, vaporization and thermal decomposition and then dissipated as the material vaporizes or erodes. In addition, high surface temperatures are reached and heat is dissipated by surface radiation, pyrolysis of the surface material causing formation of a "char," and the generation of chemical by-products which move through the char carrying heat outward towards the surface boundary. The rejected chemical by-products then tend to concentrate in the ablation boundary layer where they further block convective heating. These ablative materials may be chemically constructed or made from natural materials. A common man-made ablative material in current use is a firm silicone rubber whose chemical name is phenolmethylsiloxane. It has a silicone elastomer base, with silica filler and carbon fibers for shear strength. Its primary use is in high shear, high heatflux environments; it is used on control surfaces and nose cones of hypervelocity vehicles, including some parts of the Space Shuttle. This material yields a carbonaceous char on pyrolysis, which is a glassy, ceramic-type material composed of silicon, oxygen, and carbon. An ablative material known as polydimethylsiloxane has been used on manned reentry capsules in the past, including the Mercury program. An elastomeric silicon ablative material was used in the Discoverer program. An example of a natural material is the oak wood heat shield used on the Chinese FSW reentry vehicles. During reentry, the ablative processes begin in the upper atmosphere when the pyrolysis temperature of the material is reached resulting from an increase in atmospheric friction. At altitudes above 120 km (75 mi), atmospheric density is generally insufficient to cause the onset of ablation.
milstar: Reentry is incredibly severe, with a necessary tradeoff between survivability and ac- curacy. In general, steeper reentry angles yield more accurate ballistic vehicles. How- ever, the steeper the angle, the greater the temperature encountered and G-loading (stress caused by maneuvering during reentry) induced on the RV. The challenge is to design a reentry vehicle that will not vaporize from the heat or break up from the G-loading when reentering the earth’s atmosphere and yet will maintain the needed accuracy. During development of reentry vehicles, an intense program, including shock tests, materials research, hypersonic wind-tunnel tests, ballistic research, nose-cone drop tests, and hypersonic flight, was used to optimize design of the reentry vehicles. There are several design requirements for an RV. Foremost is the ability to survive the heat encountered during reentry; the internal temperature must be kept low enough to allow the warhead to survive reentry. A body reentering the atmosphere at speeds ap- proaching Mach 20 experiences temperatures in excess of 15,000 degrees Fahrenheit (F). In practice, the RV never reaches this temperature because of a strong shock wave ahead of the blunt body that dissipates more than 90 percent of this energy to the at- mosphere. As the RV reenters the atmosphere, it encounters tremendous deceleration forces—as high as 50 Gs, or 50 times the normal force of gravity. All internal opera- tional components must function under these extreme conditions and additionally must withstand the high lateral loads and intense vibrations encountered. http://space.au.af.mil/au-18-2009/au-18_chap18.pdf
milstar: An RV may be deflected from its calculated trajectory by aerodynamic lift forces. Stability, assisted by a form of attitude control and further augmented by some means of averaging deflection, must be designed into the RV. An arming and fusing mecha- nism must also be incorporated into the RV to prevent non programmed weapon deto- nation. From a defensive standpoint, the higher the terminal velocity, the less likely an RV will be intercepted. Higher velocity also decreases the probability of missing the target due to atmospheric deflection. Further, an RV must have a sensing mechanism to indicate the proximity of the target and to arm the warhead. What must also be con- sidered is that the weight of the vehicle must be kept to a minimum in order to maxi- mize the range of the weapon.
milstar: Atmospheric Re-Entry There are two types of entry which control the design of manned or unmanned vehicles for hypersonic re-entry into the earth’s atmosphere from space: · Ballistic (Re-Entry Vehicles, Decoys, Mercury Capsule) · Lifting (Maneuverable Re-Entry Vehicles, Gemini and Apollo Capsules, Space Shuttle, HL-10, ASSET, PRIME, X24-A, X24-B)
milstar: the primary design parameter for ballistic entry is the Ballistic Coefficient b Beta= W/(Cd*A) W -weight ,Cd -drag coefficient , A -reference area http://exoaviation.webs.com/pdf_files/Atmospheric%20Re-Entry.pdf The Ballistic Coefficient b is the single most important parameter in controlling flight trajectory during entry. Heating and deceleration are less intense for a low b value (low weight and/or high drag and large frontal area) than for a high b value (high weight and/or low drag and small frontal area) since the entry occurs high in the atmosphere where the air is less dense. Early Inter-Continental Ballistic Missiles (ICBM) with highly blunted sphere-cone-cylinder-flare geometries utilized this re-entry method. Thermal protection for these early warheads was a massive metallic heat shield, which merely provided a "heat sink" for the short heating pulse at high altitudes. It was soon discovered that delivery accuracy could be improved by increasing the values of b using slightly blunted slender sphere- cone geometries thus increasing the impact velocity so that the final descent phase was less affected by winds. A b value between 100 and 500 is representative of the early ICBM highly blunted sphere-cone-cylinder-flare geometry, while a b value of 1000 to 5000 is representative of the slightly blunted slender sphere-cone geometry used in modern ICBM re-entry vehicles. The stagnation point heat transfer is for a sphere having a nose radius of 1.0 ft using the Fay-Riddell correlation. -- Entry times vary from slightly over three minutes for a b = 100 value to slight less than one minute for a b = 5000 value. Range distance is about 160 miles for the lowest value of b (below about 50,000 ft in altitude the vehicle has slowed to subsonic velocities and literally falls out of the sky), and increases to 190, 200, and 210 miles for the other three b values in increasing order. Representative ballistic earth entry trajectories are presented in Figure 1 based on application of a point mass ballistic entry computer program using the 1976 U.S. standard atmosphere model (see Appendix A). Initial entry conditions are: Altitude = 250,000 ft Velocity = 22,500 ft/sec Flight Path Angle = 12 deg with four values of b, namely 100, 500, 1000, and 5000 (recall from the above discussion that the units on b are lbf/ft2). A b value between 100 and 500 is representative of the early ICBM highly blunted sphere-cone-cylinder-flare geometry, while a b value of 1000 to 5000 is representative of the slightly blunted slender sphere-cone geometry used in modern ICBM re-entry vehicles. The stagnation point heat transfer is for a sphere having a nose radius of 1.0 ft using the Fay-Riddell correlation. Note how peak deceleration, dynamic pressure, dynamic energy, stagnation point pressure, and stagnation point heat transfer are shifted to a lower altitude with increasing b. Entry times vary from slightly over three minutes for a b = 100 value to slight less than one minute for a b = 5000 value. Range distance is about 160 miles for the lowest value of b (below about 50,000 ft in altitude the vehicle has slowed to subsonic velocities and literally falls out of the sky), ---------------------------------------------------------------------------------------------------------- and increases to 190, 200, and 210 miles for the other three b values in increasing order. The flight path angle at entry controls range distance and entry times, with shallow angles increasing range distance and flight time. Further observe that modern ballistic re-entry vehicles with b values on the order of 5000 impact the earth’s surface at hypersonic conditions! ############################################# http://exoaviation.webs.com/pdf_files/Atmospheric%20Re-Entry.pdf --
milstar: System Implications The above example ballistic and lifting trajectory illustrations show quite clearly that there are three primary factors available to the re-entry system designer 1. Ballistic Coefficient b 2. Lift to Drag Ratio L/D 3. Flight Path Angle at Entry http://exoaviation.webs.com/pdf_files/Atmospheric%20Re-Entry.pdf For a given warhead and associated arming device, the designer selects the re-entry vehicle base diameter and vehicle length, which effectively determines the cone half-angle. The nose bluntness ratio is then selected based on drag and heat transfer considerations, with Figure 5 illustrating the effects of nose bluntness ratio on sphere-cone drag coefficient CD for a family of sphere-cone half-angles on classical Newtonian theory. Bluntness Ratio = Rnose/Rbase ----------------------------------- Vehicle weight is now fixed as the combined weight of the warhead, arming device, and re-entry vehicle. At this point the Ballistic Coefficient b is fully determined so the designer can assess ballistic trajectory performance of the design relative to mission requirements, e.g., deceleration g loads, range, and flight time. It is these mission requirements which effectively set the flight path angle at entry. Iteration of this process may be required several times before all mission requirements are fully satisfied.
milstar: A similar approach is followed for a MaRV warhead delivery system. Maneuvering is a defensive tactic that a re-entry vehicle designer uses to confound the guidance algorithms of an interceptor vehicle. There are multiple ways for the designer to provide maneuverable capability in a re-entry vehicle, such as moveable flaps which can provide one, two, or three degrees of freedom (pitch, yaw, and roll). Control can also be effected by moving a mass laterally in the vehicle to offset the vehicle’s center of gravity (e.g., the Gemini capsule had a slight mass offset to provide a trim angle of attack whose direction and magnitude could be controlled by the astronaut). The resulting mass asymmetry is equivalent to an aerodynamic asymmetry. Another aerodynamic approach is jet interaction, but this appears best suited to steering out navigational errors rather than defensive maneuvering. The common element is that the additional design variable of L/D lift to drag ratio is introduced. Figure 6 illustrates the effects of nose bluntness ratio (Rnose/Rbase) on a 10.0 deg half-angle sphere-cone lift to drag coefficient L/D based on classical Newtonian theory over an angle of attack range from zero up to the cone half-angle.
milstar: По отрывочным сведениям, просочившимся в печать, можно понять, что в головной части «Тополя» находится несколько маневровых реактивных двигателей и прямоточный реактивный ускоритель. В результате боеголовка, затормозившая при вхождении в атмосферу, снова увеличивает скорость до гиперзвуковой и совершает зигзагообразные маневры. Предсказать ее полет становится просто невозможно. Следовательно, и поразить ее средствами противоракетной обороны тоже нельзя, поскольку их нельзя точно навести. Вот как об этом однажды сказал Юрий Балуевский, комментируя испытания боеголовки: «Это гиперзвуковой летательный аппарат. Полет нового летательного аппарата производился по «неклассической схеме». Он способен летать не только по баллистической траектории с гиперзвуковой скоростью, но и в атмосфере, произвольно изменяя траекторию полета. Это позволяет ему преодолевать любые перспективные системы противоракетной обороны». Назвав боеголовку «летательным аппаратом», начальник российского Генштаба дал понять, что она как минимум имеет собственную двигательную установку. Более того, не исключено, что это не просто боевой блок баллистической ракеты с двигателем, а самостоятельный летательный аппарата, доставляемый с помощью межконтинентальной ракеты на территорию противника. Скорее всего это крылатая ракета, потому что только она может летать в атмосфере с гиперзвуковой скоростью. http://nvo.ng.ru/printed/88996
milstar: There are multiple ways for the designer to provide maneuverable capability in a re-entry vehicle, 1. ...moveable flaps which can provide one, two, or three degrees of freedom 2. ...Control can also be effected by moving a mass laterally in the vehicle to offset the vehicle’s center of gravity.The resulting mass asymmetry is equivalent to an aerodynamic asymmetry. ################################## 3. ....Another aerodynamic approach is jet interaction, but this appears best suited to steering out navigational errors rather than defensive maneuvering. ############################################################ The common element is that the additional design variable of L/D lift to drag ratio is introduced. -------------------------------------------------------------------------------------------------------- http://exoaviation.webs.com/pdf_files/Atmospheric%20Re-Entry.pdf
milstar: Opredelija NASA http://www.grc.nasa.gov/WWW/K-12/airplane/lift1.html Lift is the force that directly opposes the weight of an airplane and holds the airplane in the air. Lift is generated by every part of the airplane, but most of the lift on a normal airliner is generated by the wings. Lift is a mechanical aerodynamic force produced by the motion of the airplane through the air. Because lift is a force, it is a vector quantity, having both a magnitude and a direction associated with it. Lift acts through the center of pressure of the object and is directed perpendicular to the flow direction. There are several factors which affect the magnitude of lift. HOW IS LIFT GENERATED? There are many explanations for the generation of lift found in encyclopedias, in basic physics textbooks, and on Web sites. Unfortunately, many of the explanations are misleading and incorrect. Theories on the generation of lift have become a source of great controversy and a topic for heated arguments. To help you understand lift and its origins, a series of pages will describe the various theories and how some of the popular theories fail. Lift occurs when a moving flow of gas is turned by a solid object. The flow is turned in one direction, and the lift is generated in the opposite direction, according to Newton's Third Law of action and reaction. Because air is a gas and the molecules are free to move about, any solid surface can deflect a flow. For an aircraft wing, both the upper and lower surfaces contribute to the flow turning. Neglecting the upper surface's part in turning the flow leads to an incorrect theory of lift. NO FLUID, NO LIFT Lift is a mechanical force. It is generated by the interaction and contact of a solid body with a fluid (liquid or gas). It is not generated by a force field, in the sense of a gravitational field,or an electromagnetic field, where one object can affect another object without being in physical contact. For lift to be generated, the solid body must be in contact with the fluid: no fluid, no lift. The Space Shuttle does not stay in space because of lift from its wings but because of orbital mechanics related to its speed. Space is nearly a vacuum. Without air, there is no lift generated by the wings. NO MOTION, NO LIFT Lift is generated by the difference in velocity between the solid object and the fluid. There must be motion between the object and the fluid: no motion, no lift. It makes no difference whether the object moves through a static fluid, or the fluid moves past a static solid object. Lift acts perpendicular to the motion. Drag acts in the direction opposed to the motion. You can learn more about the factors that affect lift at this web site. There are many small interactive programs here to let you explore the generation of lift. You can view a short movie of "Orville and Wilbur Wright" discussing the lift force and how it affected the flight of their aircraft. The movie file can be saved to your computer and viewed as a Podcast on your podcast player. Подъёмная сила — составляющая полной аэродинамической силы, перпендикулярная вектору скорости движения тела в потоке жидкости или газа, возникающая в результате несимметричности обтекания тела потоком. В соответствии с законом Бернулли, статическое давление среды в тех областях, где скорость потока более высока, будет ниже, и наоборот. Например, крыло самолета имеет несимметричный профиль (верхняя часть крыла более выпуклая), вследствие чего скорость потока по верхней кромке крыла будет выше, чем над нижней. Создавшаяся разница давлений и порождает подъёмную силу. Полная аэродинамическая сила — это интеграл от давления вокруг контура крыла. http://ru.wikipedia.org/wiki/Подъёмная_сила
milstar: With reference to Appendix B, the weight of the warhead in a typical high performance re-entry vehicle is between 50 and 75 percent of the total vehicle weight. If the decoy has the same physical size characteristics (and thus aerodynamic drag) as the warhead carrying vehicle, then the Ballistic Coefficient b for the decoy will be between 25 and 50 percent of the warhead carrying vehicle. With reference to Figure 1, assume the warhead carrying vehicle has a b of 1000 and the decoy has a b of 500. http://exoaviation.webs.com/pdf_files/Atmospheric%20Re-Entry.pdf
milstar: http://www.scribd.com/doc/53416290/Atmospheric-Re-Entry-Vehicle-Mechanics Minimal energy trajectory ################ str.124/142 Fig. 7.4 Initial flight path angle as function of range s zemli 2000 km -40° 4000 km -36 ° 6000 km -32 ° 8000 km -27 ° 9000 km -25° 10000 km -22.55° 11000 km -20 ° 18000 km -5 °
milstar: http://www.scribd.com/doc/53416290/Atmospheric-Re-Entry-Vehicle-Mechanics Minimal energy trajectory ################ str.124/142 Fig. 7.4 Initial flight path angle as function of range s zemli 2000 km -40° 4000 km -36 ° 6000 km -32 ° 8000 km -27 ° 9000 km -25° 10000 km -22.55° 11000 km -20 ° 18000 km -5 °
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