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Heat-seeking
Infrared homing is a passive weapon guidance system which uses the infrared (IR) light emission from a target to track and follow it seamlessly. Missiles which use infrared seeking are often referred to as "heat-seekers" since infrared is radiated strongly by hot bodies. Many objects such as people, vehicle engines and aircraft generate and emit heat and so are especially visible in the infrared wavelengths of light compared to objects in the background. Infrared seekers are passive devices, which, unlike radar, provide no indication that they are tracking a target. That makes them suitable for sneak attacks during visual encounters or over longer ranges when they are used with a forward looking infrared or similar cueing system. Heat-seekers are extremely effective: 90% of all United States air combat losses between 1984 and 2009 were caused by infrared-homing missiles. They are, however, subject to a number of simple countermeasures, most notably by dropping flares behin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air-to-air Missile
An air-to-air missile (AAM) is a missile fired from an aircraft for the purpose of destroying another aircraft (including unmanned aircraft such as cruise missiles). AAMs are typically powered by one or more rocket motors, usually solid-fuel rocket, solid fueled but sometimes liquid-fuel rocket, liquid fueled. Ramjet engines, as used on the Meteor (missile), Meteor, are emerging as propulsion that will enable future medium- to long-range missiles to maintain higher average speed across their engagement envelope. Air-to-air missiles are broadly put in two groups. Those designed to engage opposing aircraft at ranges of around 30 km to 40 km maximum are known as short-range or "within visual range" missiles (SRAAMs or WVRAAMs) and are sometimes called "dogfight" missiles because they are designed to optimize their agility rather than range. Most use infrared guidance and are called heat-seeking missiles. In contrast, medium- or long-range missiles (MRAAMs or LRAAMs), which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flare (countermeasure)
A flare or decoy flare is an aerial infrared countermeasure used by an aircraft to counter an infrared homing ("heat-seeking") surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust. The aim is to make the infrared-guided missile seek out the heat signature from the flare rather than the aircraft's engines. Tactics In contrast to radar-guided missiles, IR-guided missiles are very difficult to find as they approach aircraft. They do not emit detectable radar, and they are generally fired from behind, directly toward the engines. In most cases, pilots have to rely on their wingmen to spot the missile's smoke trail and alert of a launch. Since IR-guided missiles have a shorter range than their radar-guided counterparts, good situational awareness of altitude and potential threats continues to be an effective defense. Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flare
A flare, also sometimes called a fusée, fusee, or bengala, bengalo in several European countries, is a type of pyrotechnic that produces a bright light or intense heat without an explosion. Flares are used for distress signaling, illumination, or defensive countermeasures in civilian and military applications. Flares may be ground pyrotechnics, projectile pyrotechnics, or parachute-suspended to provide maximum illumination time over a large area. Projectile pyrotechnics may be dropped from aircraft, fired from rocket or artillery, or deployed by flare guns or handheld percussive tubes. Origin The earliest recorded use of gunpowder for signaling purposes was the 'signal bomb' used by the Chinese Song dynasty, Song Dynasty (960–1279) as the Mongol-led Yuan dynasty, Yuan Dynasty (1271–1368) besieged Yangzhou in 1276. These soft-shelled bombs, timed to explode in midair, were used to send messages to a detachment of troops far in the distance. Another mention of the signal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 million tons in 2021. It has the world's largest aircraft carrier fleet, with List of aircraft carriers in service, eleven in service, one undergoing trials, two new carriers under construction, and six other carriers planned as of 2024. With 336,978 personnel on active duty and 101,583 in the Ready Reserve, the U.S. Navy is the third largest of the United States military service branches in terms of personnel. It has 299 deployable combat vessels and about 4,012 operational aircraft as of 18 July 2023. The U.S. Navy is one of six United States Armed Forces, armed forces of the United States and one of eight uniformed services of the United States. The United States Navy traces its origins to the Continental Navy, which was established during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timeline Of United States Military Operations
This timeline of United States military operations, based in part on reports by the Congressional Research Service, shows the years and places in which United States Armed Forces units participated in armed conflicts or occupation of foreign territories. Items in bold are wars most often considered to be ''major conflicts'' by historians and the general public. Note that instances where the U.S. government gave aid alone, with no military personnel involvement, are excluded, as are Central Intelligence Agency operations. In domestic peacetime disputes such as riots and labor issues, only operations undertaken by active duty personnel (also called "federal troops" or "U.S. military") are depicted in this article; state defense forces and the National Guard are not included, as they are not fully integrated into the U.S. Armed Forces even if they are federalized for duty within the United States itself. Conflict names and dates Throughout its history, the United States has eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface-to-air Missile
A surface-to-air missile (SAM), also known as a ground-to-air missile (GTAM) or surface-to-air guided weapon (SAGW), is a missile designed to be launched from the ground or the sea to destroy aircraft or other missiles. It is one type of anti-aircraft warfare, anti-aircraft system; in modern armed forces, missiles have replaced most other forms of dedicated anti-aircraft weapons, with anti-aircraft guns pushed into specialized roles. The first attempt at SAM development took place during World War II, but no operational systems were introduced. Further development in the 1940s and 1950s led to operational systems being introduced by most major forces during the second half of the 1950s. Smaller systems, suitable for close-range work, evolved through the 1960s and 1970s, to modern systems that are man-portable. Shipborne systems followed the evolution of land-based models, starting with long-range weapons and steadily evolving toward smaller designs to provide a layered defence. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), nonmetal, and a potent oxidizing agent that readily forms oxides with most elements as well as with other chemical compound, compounds. Oxygen is abundance of elements in Earth's crust, the most abundant element in Earth's crust, making up almost half of the Earth's crust in the form of various oxides such as water, carbon dioxide, iron oxides and silicates.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. It is abundance of chemical elements, the third-most abundant element in the universe after hydrogen and helium. At standard temperature and pressure, two oxygen atoms will chemical bond, bind covalent bond, covalently to form dioxygen, a colorless and odorless diatomic gas with the chemical formula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver
Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. Silver is found in the Earth's crust in the pure, free elemental form ("native metal, native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc Refining (metallurgy), refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes bimetallism, alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. Other than in currency and as an in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Movietone Sound System
The Movietone sound system is an optical sound, optical sound-on-film method of recording sound for motion pictures, ensuring synchronization between sound and picture. It achieves this by recording the sound as a variable-density optical track on the same strip of film that records the pictures. The initial version of this system was capable of reproducing sounds up to 8500 Hz. Although modern sound films use variable-area tracks instead, modern motion picture theaters (excluding those that have transitioned to digital cinema) can play a Movietone film without modification to the projector (though if the projector's sound unit has been fitted with red LED or laser light sources, the reproduction quality from a variable density track will be significantly impaired). Movietone was one of four motion picture sound systems under development in the U.S. during the 1920s. The others were DeForest's Phonofilm, Warner Brothers' Vitaphone, and RCA Photophone. However, Phonofilm was p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodore Case
Theodore Willard Case (December 12, 1888 – May 13, 1944) was an American chemist who invented the Movietone sound system, Movietone sound-on-film, sound-on-sound film, film system. Early life and education Case was born on December 12, 1888 in Auburn, New York, to Willard Erastus Case (1857–1918) and Eva Fidelia Caldwell Case (1857–1952). He attended a few boarding schools as a youth including The Manlius School near Syracuse, New York and Cloyne House School in Newport, Rhode Island, He also attended the St. Paul School in Concord, New Hampshire, to finish his secondary education. Following his high school graduation he attended Yale University from 1908 to 1912, where he earned his Bachelor of Arts, BA in chemistry. He then attended Harvard University where he studied law. He did not find this as fulfilling as pursuing science so he left after about a year. During the years prior to opening the Case Research Lab he worked with his father in laboratories set u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galena
Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the Cubic (crystal system), cubic crystal system often showing octahedral forms. It is often associated with the minerals sphalerite, calcite and fluorite. As a pure specimen held in the hand, under standard temperature and pressure, galena is insoluble in water and so is almost non-toxic. Handling galena under these specific conditions (such as in a museum or as part of geology instruction) poses practically no risk; however, as lead(II) sulfide is reasonably reactive in a variety of environments, it can be highly toxic if swallowed or inhaled, particularly under prolonged or repeated exposure. Occurrence Galena is the main ore of lead, used since ancient times, since lead can be smelted from galena in an ordinary wood fire. G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jagadish Chandra Bose
Sir Jagadish Chandra Bose (; ; 30 November 1858 – 23 November 1937) was a polymath with interests in biology, physics and writing science fiction. He was a pioneer in the investigation of radio microwave optics, made significant contributions to botany, and was a major force behind the expansion of experimental science on the Indian subcontinent. Bose is considered the father of Bengali science fiction. Bose (crater), A crater on the Moon was named in his honour. He founded the Bose Institute, a premier research institute in India and also one of its oldest. Established in 1917, the institute was the first interdisciplinary research centre in Asia. He served as the Director of Bose Institute from its inception until his death. Born in Mymensingh, Bengal Presidency (present-day Bangladesh), during British Raj, British governance of India, Bose graduated from St. Xavier's College, Calcutta (now Kolkata, West Bengal, India). Prior to his enrollment at St. Xavier's College, Calcut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
