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Light Night Striking Force
The Pathfinders were target-marking squadrons in RAF Bomber Command during World War II. They located and marked targets with flares, which a main bomber force could aim at, increasing the accuracy of their bombing. The Pathfinders were normally the first to receive new blind-bombing aids like Gee, Oboe and the H2S radar. The early Pathfinder Force (PFF) squadrons was expanded to become a group, No. 8 (Pathfinder Force) Group in January 1943. The initial Pathfinder Force was five squadrons, while No. 8 Group ultimately grew to a strength of 19 squadrons. While the majority of Pathfinder squadrons and personnel were from the Royal Air Force, the group also included many from the air forces of other Commonwealth countries. History Background At the start of the war in September 1939, RAF Bomber Command's doctrine was based on tight formations of heavily armed bombers attacking during daylight and fending off attacks by fighters with their defensive guns. In early missions ov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathfinder (USAAF)
The 482d Operations Group is a United States Air Force Reserve unit assigned to the 482d Fighter Wing. It is stationed at Homestead Air Reserve Base, Florida. During World War II, the group was activated in England as the 482d Bombardment Group (Pathfinder), the only Eighth Air Force radar-equipped pathfinder heavy bomber group. Its Boeing B-17 Flying Fortress and Consolidated B-24 Liberator aircraft were equipped with first generation radars to guide other bombardment groups to targets obscured by cloud cover over Occupied Europe and Nazi Germany, earning a Distinguished Unit Citation. In 1944, it was removed from combat to focus on training pathfinder aircrews and develop tactics, although its developmental work occasionally required it to fly combat missions. After V-E Day, the group returned to the United States and was inactivated. The group became a reserve organization, serving as a bombardment unit from 1947-1949 and briefly as an airlift unit in 1952. It became a f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luftwaffe
The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabteilung'' of the Imperial Navy, had been disbanded in May 1920 in accordance with the terms of the 1919 Treaty of Versailles which banned Germany from having any air force. During the interwar period, German pilots were trained secretly in violation of the treaty at Lipetsk Air Base in the Soviet Union. With the rise of the Nazi Party and the repudiation of the Versailles Treaty, the ''Luftwaffe''s existence was publicly acknowledged on 26 February 1935, just over two weeks before open defiance of the Versailles Treaty through German rearmament and conscription would be announced on 16 March. The Condor Legion, a ''Luftwaffe'' detachment sent to aid Nationalist forces in the Spanish Civil War, provided the force with a valuable testing grou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperbolic Navigation
Hyperbolic navigation is a class of radio navigation systems in which a navigation receiver instrument is used to determine location based on the difference in timing (phase) of radio waves received from radio navigation beacon transmitters. Such systems rely on the ability of two widely separated stations to broadcast a signal that is highly correlated in time. Typical systems either broadcast short pulses at the same time, or continual signals that are identical in phase. A receiver located at the midpoint between the two stations will receive the signals at the same time or have identical phase, but at any other location the signal from the closer station will be received first or have a different phase. Determining the location of a receiver requires that the two synchronized stations be tuned in at the same time so the signals can be compared. This reveals a ''difference'' in time, corresponding to a relative distance closer to one station or the other. Plotting all the loc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehousing
Frederick Lindemann, 1st Viscount Cherwell, Professor Frederick Lindemann, Baron Cherwell, the British government's chief scientific adviser, sent on 30 March 1942 to British Prime Minister Winston Churchill a memorandum which, after it was accepted by the Cabinet (government), Cabinet, became known as the dehousing paper.Also known as the "dehousing memorandum", the "Lindemann memorandum/paper", and the "Cherwell memorandum/paper" (he was ennobled in 1956) The paper was delivered during a debate within the British government about the most effective use of the nation's resources in waging war on Germany: whether the Royal Air Force (RAF) should be reduced to allow more resources to go to the British Army and Royal Navy, or the Strategic bombing during World War II, strategic bombing option should be followed and expanded. The paper argued that from the analysis of the reaction of the British population to the Blitz, the demolition of people's houses was the most effective way to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frederick Lindemann, 1st Viscount Cherwell
Frederick Alexander Lindemann, 1st Viscount Cherwell, ( ; 5 April 18863 July 1957) was a British physicist who was prime scientific adviser to Winston Churchill in World War II. Lindemann was a brilliant intellectual, who cut through bureaucratic red tape that was hampering vital defence preparations against a German invasion. This caused sharp disagreements with many of the permanent bureaucracy. His contribution to Allied victory lay chiefly in embracing the art of the possible. He was particularly adept at converting data into clear charts to promote a strategy. His approach to technology focused on rapid experiments and fast failures, to come up with the proper answer; this made him at target for bureaucratic ire and accusations. He was involved in the development of radar and infra-red guidance systems. He was skeptical of the first reports of the enemy's V-weapons programme. He pressed the case for the strategic area bombing of cities. His abiding influence on Churc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ruhr
The Ruhr ( ; german: Ruhrgebiet , also ''Ruhrpott'' ), also referred to as the Ruhr area, sometimes Ruhr district, Ruhr region, or Ruhr valley, is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 2,800/km2 and a population of over 5 million (2017), it is the largest urban area in Germany. It consists of several large cities bordered by the rivers Ruhr to the south, Rhine to the west, and Lippe to the north. In the southwest it borders the Bergisches Land. It is considered part of the larger Rhine-Ruhr metropolitan region of more than 10 million people, which is the third largest in Europe, behind only London and Paris. The Ruhr cities are, from west to east: Duisburg, Oberhausen, Bottrop, Mülheim an der Ruhr, Essen, Gelsenkirchen, Bochum, Herne, Hagen, Dortmund, Lünen, Bergkamen, Hamm and the districts of Wesel, Recklinghausen, Unna and Ennepe-Ruhr-Kreis. The most populous cities are Dortmund (with a population of approximately 588 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butt Report
The Butt Report, released on 18 August 1941, was a report prepared during World War II, revealing the widespread failure of RAF Bomber Command aircraft to hit their targets. At the start of the war, Bomber Command had no real means of determining the success of its operations. Crews would return with only their word as to the amount of damage caused or even if they had bombed the target. The Air Ministry demanded that a method of verifying these claims be developed and by 1941 cameras mounted under bombers, triggered by the bomb release, were being fitted. Contents The report was initiated by Lord Cherwell, a friend of Churchill and chief scientific advisor to the Cabinet. David Bensusan-Butt, a civil servant in the War Cabinet Secretariat and an assistant of Cherwell, was given the task of assessing 633 target photos and comparing them with crews' claims. The results, first circulated on 18 August 1941, were a shock to many, though not necessarily to those within the RAF, who k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Course Setting Bomb Sight
The Course Setting Bomb Sight (CSBS) is the canonical ''vector'' bombsight, the first practical system for properly accounting for the effects of wind when dropping bombs. It is also widely referred to as the Wimperis sight after its inventor, Harry Wimperis. The CSBS was developed for the Royal Naval Air Service (RNAS) in order to attack submarines and ships. It was introduced in 1917, and was such a great advance over earlier designs that it was quickly adopted by the Royal Flying Corps, and the Independent Air Force. It has been called "the most important bomb sight of the war". After the war the design found widespread use around the world. A US version of the CSBS was used by Billy Mitchell on his famous attack on the ''Ostfriesland'' in 1921. The basic design was adapted by almost all air forces and used well into World War II. It was eventually replaced in British service by more advanced designs like the Mark XIV bomb sight and the Stabilized Automatic Bomb Sight. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dead Reckoning
In navigation, dead reckoning is the process of calculating current position of some moving object by using a previously determined position, or fix, and then incorporating estimates of speed, heading direction, and course over elapsed time. The corresponding term in biology, used to describe the processes by which animals update their estimates of position or heading, is path integration. Dead reckoning is subject to cumulative errors. Advances in navigational aids that give accurate information on position, in particular satellite navigation using the Global Positioning System, have made simple dead reckoning by humans obsolete for most purposes. However, inertial navigation systems, which provide very accurate directional information, use dead reckoning and are very widely applied. Etymology The term "dead reckoning" was not originally used to abbreviate "deduced reckoning," nor is it a misspelling of the term "ded reckoning." The use of "ded" or "deduced reckoning" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Navigation
Radio navigation or radionavigation is the application of radio frequencies to determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of radiodetermination. The basic principles are measurements from/to electric beacons, especially * Angular directions, e.g. by bearing, radio phases or interferometry, * Distances, e.g. ranging by measurement of time of flight between one transmitter and multiple receivers or vice versa, * Distance ''differences'' by measurement of times of arrival of signals from one transmitter to multiple receivers or vice versa * Partly also velocity, e.g. by means of radio Doppler shift. Combinations of these measurement principles also are important—e.g., many radars measure range and azimuth of a target. Bearing-measurement systems These systems used some form of directional radio antenna to determine the location of a broadcast station on the ground. Conventional navigation techniques a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Searchlight
A searchlight (or spotlight) is an apparatus that combines an extremely bright source (traditionally a carbon arc lamp) with a mirrored parabolic reflector to project a powerful beam of light of approximately parallel rays in a particular direction. It is usually constructed so that it can be swiveled about. Military use The first use of searchlights using carbon arc technology occurred during the Siege of Paris during the Franco-Prussian War. The Royal Navy used searchlights in 1882 to dazzle and prevent Egyptian forces from manning artillery batteries at Alexandria. Later that same year, the French and British forces landed troops under searchlights. By 1907 the value of searchlights had become widely recognized. One recent use was to assist attacks by torpedo boats by dazzling gun crews on the ships being attacked. Other uses included detecting enemy ships at greater distances, as signaling devices, and to assist landing parties. Searchlights were also used by battles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freya Radar
Freya was an early warning radar deployed by Germany during World War II; it was named after the Norse goddess Freyja. During the war, over a thousand stations were built. A naval version operating on a slightly different wavelength was also developed as the ''Seetakt''. Development First tests of what would become the "''Freya''" were conducted in early 1937, with initial delivery of an operational radar to the ''Kriegsmarine'' in 1938 by the GEMA company. Freya supported an early version of Identification friend or foe (IFF). Aircraft equipped with the FuG 25a "''Erstling''" IFF system could be successfully queried across ranges of over 100 km. The "AN" version gained a switchable phasing line for the antenna. Switching in the phasing line led to a phase displacement of the antenna's radiation pattern and with that, a squinting to the left or right. This enabled the system in effect to switch from the rather broad "scanning for maxima" to narrow lobe switching. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
