A target drone is an unmanned aerial vehicle , generally remote controlled , usually used in the training of anti-aircraft crews.
86-769: High Angle Control System ( HACS ) was a British anti-aircraft fire-control system employed by the Royal Navy from 1931 and used widely during World War II . HACS calculated the necessary deflection required to place an explosive shell in the location of a target flying at a known height, bearing and speed. The HACS was first proposed in the 1920s and began to appear on Royal Navy (RN) ships in January 1930, when HACS I went to sea in HMS ; Valiant . HACS I did not have any stabilisation or power assist for director training. HACS III which appeared in 1935, had provision for stabilisation,
172-600: A 75 mm 12-pounder, and even a 105 mm gun. Erhardt also had a 12-pounder, while Vickers Maxim offered a 3-pounder and Schneider a 47 mm. The French balloon gun appeared in 1910, it was an 11-pounder but mounted on a vehicle, with a total uncrewed weight of two tons. However, since balloons were slow moving, sights were simple. But the challenges of faster moving aeroplanes were recognised. By 1913 only France and Germany had developed field guns suitable for engaging balloons and aircraft and addressed issues of military organisation. Britain's Royal Navy would soon introduce
258-553: A document dated as "revised Aug 1940": Anti-aircraft Anti-aircraft warfare is the counter to aerial warfare and includes "all measures designed to nullify or reduce the effectiveness of hostile air action". It encompasses surface-based, subsurface ( submarine-launched ), and air-based weapon systems, in addition to associated sensor systems, command and control arrangements, and passive measures (e.g. barrage balloons ). It may be used to protect naval , ground , and air forces in any location. However, for most countries,
344-628: A full military structure. For example, the UK's Anti-Aircraft Command, commanded by a full British Army general was part of ADGB. At its peak in 1941–42 it comprised three AA corps with 12 AA divisions between them. The use of balloons by the U.S. Army during the American Civil War compelled the Confederates to develop methods of combating them. These included the use of artillery, small arms, and saboteurs. They were unsuccessful, and internal politics led
430-451: A large traverse that could be easily transported on a wagon. Krupp 75 mm guns were supplied with an optical sighting system that improved their capabilities. The German Army also adapted a revolving cannon that came to be known to Allied fliers as the " flaming onion " from the shells in flight. This gun had five barrels that quickly launched a series of 37 mm artillery shells. As aircraft started to be used against ground targets on
516-543: A maritime force against attacks by airborne weapons launched from aircraft, ships, submarines and land-based sites". In some armies the term all-arms air defence (AAAD) is used for air defence by nonspecialist troops. Other terms from the late 20th century include "ground based air defence" (GBAD) with related terms " short range air defense " (SHORAD) and man-portable air-defense system (MANPADS). Anti-aircraft missiles are variously called surface-to-air missiles , ("SAMs") and surface-to-air guided weapons (SAGWs). Examples are
602-504: A new 3.6-inch gun, in 1918. In 1928 a 3.7-inch (94 mm) gun became the preferred solution, but it took six years to gain funding. Production of the QF 3.7-inch gun began in 1937; this gun was used on mobile carriages with the field army and transportable guns on fixed mountings for static positions. At the same time the Royal Navy adopted a new 4.5-inch (113 mm) gun in a twin turret, which
688-624: A new field mounting was introduced in 1916. Since most attacks were at night, searchlights were soon used, and acoustic methods of detection and locating were developed. By December 1916 there were 183 AA sections defending Britain (most with the 3-inch), 74 with the BEF in France and 10 in the Middle East. AA gunnery was a difficult business. The problem was of successfully aiming a shell to burst close to its target's future position, with various factors affecting
774-666: A par with the army, navy, or air force. In the Soviet Union, this was called Voyska PVO , and had both fighter aircraft, separate from the air force, and ground-based systems. This was divided into two arms, PVO Strany, the Strategic Air defence Service responsible for Air Defence of the Homeland, created in 1941 and becoming an independent service in 1954, and PVO SV, Air Defence of the Ground Forces. Subsequently, these became part of
860-475: A range of 2,000 yards (1,800 m). RN destroyers were hampered by the lack of good dual-purpose weapons suitable for ships of destroyer size; for much of the war 40° was the maximum elevation of the 4.7-inch (119 mm) guns equipping such ships, which were consequently unable to engage directly attacking dive bombers , although they could provide "barrage" and "predicted fire" to protect other ships from such attacks. Destroyers did not use HACS, but rather
946-506: A technique known as " lobe switching " but only crude estimates of altitude. It could not, therefore, "lock on" to aerial targets and was unable to provide true blindfire capabilities, which no other navy was able to do until the USN developed advanced radars in 1944 using technology transfers from the UK. This situation was not remedied until the introduction of the HACS Mark VI director in 1944 that
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#17328483507541032-475: Is assisted but not governed by identification friend or foe (IFF) electronic devices originally introduced during the Second World War . While these rules originate at the highest authority, different rules can apply to different types of air defence covering the same area at the same time. AAAD usually operates under the tightest rules. NATO calls these rules "weapon control orders" (WCO), they are: Until
1118-631: Is deployed in several ways: Air defence has included other elements, although after the Second World War most fell into disuse: Passive air defence is defined by NATO as "Passive measures taken for the physical defence and protection of personnel, essential installations and equipment in order to minimise the effectiveness of air and/or missile attack". It remains a vital activity by ground forces and includes camouflage and concealment to avoid detection by reconnaissance and attacking aircraft. Measures such as camouflaging important buildings were common in
1204-454: Is operated by specialists, batteries may have several dozen teams deploying separately in small sections; self-propelled air defence guns may deploy in pairs. Batteries are usually grouped into battalions or equivalent. In the field army, a light gun or SHORAD battalion is often assigned to a manoeuvre division. Heavier guns and long-range missiles may be in air-defence brigades and come under corps or higher command. Homeland air defence may have
1290-459: Is the apparent target motion along the line of sight. This was also printed on a paper plot so that a range rate officer could assess its accuracy. This calculated range rate was fed back to the UD4 where it powered a motor to move prisms within the UD4. If all the measurements were correct, this movement would track the target, making it appear motionless in the sights. If the target had apparent movement,
1376-414: Is to detect hostile aircraft and destroy them. The critical issue is to hit a target moving in three-dimensional space; an attack must not only match these three coordinates, but must do so at the time the target is at that position. This means that projectiles either have to be guided to hit the target, or aimed at the predicted position of the target at the time the projectile reaches it, taking into account
1462-573: Is usually accomplished via the combined use of systems optimized for either short-, medium-, or long-range air defence. In some countries, such as Britain and Germany during the Second World War , the Soviet Union , and modern NATO and the United States, ground-based air defence and air defence aircraft have been under integrated command and control. However, while overall air defence may be for homeland defence (including military facilities), forces in
1548-425: The 13-pr QF 9 cwt and these proved much more satisfactory. However, in general, these ad hoc solutions proved largely useless. With little experience in the role, no means of measuring target, range, height or speed the difficulty of observing their shell bursts relative to the target gunners proved unable to get their fuse setting correct and most rounds burst well below their targets. The exception to this rule
1634-519: The Fuze Keeping Clock (FKC), a simplified version of HACS. Starting in 1938 all new RN destroyers, from the Tribal class onwards, were fitted with a FKC and continuous prediction fuse setting trays for each main armament gun. WWII experience from all navies showed that dive bombers could not be engaged successfully by any remote computer-predictive AA system using mechanical fuzes due to the lag time in
1720-415: The QF 2 pdr (40mm) "pom pom" mounts , and a long range Type 281 radar Warning Air (WA) radar which also had precision ranging panels for aerial and surface targets. This placed HMS Prince of Wales in the forefront of naval HA AA fire control systems at that time. In August and September 1941, HMS Prince of Wales demonstrated excellent long range radar directed AA fire during Operation Halberd . Although
1806-458: The QF 3-inch and QF 4-inch AA guns and also had Vickers 1-pounder quick firing "pom-poms" that could be used in various mountings. The first US anti-aircraft cannon was a 1-pounder concept design by Admiral Twining in 1911 to meet the perceived threat of airships, that eventually was used as the basis for the US Navy's first operational anti-aircraft cannon: the 3-inch/23 caliber gun . On
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#17328483507541892-647: The RIM-66 Standard , Raytheon Standard Missile 6 , or the MBDA Aster missile. Non-English terms for air defence include the German Flak or FlaK ( Fliegerabwehrkanone , 'aircraft defence cannon', also cited as Flugabwehrkanone ), whence English flak , and the Russian term Protivovozdushnaya oborona ( Cyrillic : Противовозду́шная оборо́на), a literal translation of 'anti-air defence', abbreviated as PVO. In Russian,
1978-653: The Royal Naval Volunteer Reserve (RNVR) was manning AA guns and searchlights assembled from various sources at some nine ports. The Royal Garrison Artillery (RGA) was given responsibility for AA defence in the field, using motorised two-gun sections. The first were formally formed in November 1914. Initially they used QF 1-pounder "pom-pom"s (37 mm versions of the Maxim Gun ). All armies soon deployed AA guns often based on their smaller field pieces, notably
2064-658: The United States Air Force 's operating bases in the UK. All ground-based air defence was removed from Royal Air Force (RAF) jurisdiction in 2004 . The British Army's Anti-Aircraft Command was disbanded in March 1955, but during the 1960s and 1970s the RAF's Fighter Command operated long-range air-defence missiles to protect key areas in the UK. During World War II, the Royal Marines also provided air defence units; formally part of
2150-649: The 1950s, guns firing ballistic munitions were the standard weapon; guided missiles then became dominant, except at the very shortest ranges. However, the type of shell or warhead and its fuzing and, with missiles, the guidance arrangement were and are varied. Targets are not always easy to destroy; nonetheless, damaged aircraft may be forced to abort their mission and, even if they manage to return and land in friendly territory, may be out of action for days or permanently. Ignoring small arms and smaller machine-guns, ground-based air defence guns have varied in calibre from 20 mm to at least 152 mm. Ground-based air defence
2236-465: The 30th of September, 1915, troops of the Serbian Army observed three enemy aircraft approaching Kragujevac . Soldiers fired at them with shotguns and machine-guns but failed to prevent them from dropping 45 bombs over the city, hitting military installations, the railway station and many other, mostly civilian, targets in the city. During the bombing raid, private Radoje Ljutovac fired his cannon at
2322-420: The 8.8 cm FlaK 18 in 1933, the 36 and 37 models followed with various improvements, but ballistic performance was unchanged. In the late 1930s the 10.5 cm FlaK 38 appeared, soon followed by the 39; this was designed primarily for static sites but had a mobile mounting, and the unit had 220 V 24 kW generators. In 1938 design started on the 12.8 cm FlaK . Britain had successfully tested
2408-484: The AA systems are called zenitnye (i.e., 'pointing to zenith ') systems. In French, air defence is called Défense contre les aéronefs (DCA) , aéronef meaning 'aircraft'. The maximum distance at which a gun or missile can engage an aircraft is an important figure. However, many different definitions are used and unless the same definition is used, performance of different guns or missiles cannot be compared. For AA guns only
2494-485: The British Isles increased in 1915 and the AA efforts were deemed somewhat ineffective, so a Royal Navy gunnery expert, Admiral Sir Percy Scott , was appointed to make improvements, particularly an integrated AA defence for London. The air defences were expanded with more RNVR AA guns, 75 mm and 3-inch, the pom-poms being ineffective. The naval 3-inch was also adopted by the army, the QF 3-inch 20 cwt (76 mm),
2580-534: The British adopted a new instrument developed by Vickers. It was a mechanical analogue computer - the Predictor AA No 1. Given the target height, its operators tracked the target and the predictor produced bearing, quadrant elevation and fuse setting. These were passed electrically to the guns, where they were displayed on repeater dials to the layers who "matched pointers" (target data and the gun's actual data) to lay
2666-468: The French 75 mm and Russian 76.2 mm, typically simply propped up on some sort of embankment to get the muzzle pointed skyward. The British Army adopted the 13-pounder quickly producing new mountings suitable for AA use, the 13-pdr QF 6 cwt Mk III was issued in 1915. It remained in service throughout the war but 18-pdr guns were lined down to take the 13-pdr shell with a larger cartridge producing
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2752-544: The German Flugzeugabwehrkanone ), "ack-ack" (from the spelling alphabet used by the British for voice transmission of "AA"); and "archie" (a World War I British term probably coined by Amyas Borton , and believed to derive via the Royal Flying Corps , from the music-hall comedian George Robey 's line "Archibald, certainly not!" ). NATO defines anti-aircraft warfare (AAW) as "measures taken to defend
2838-624: The HACP, which transmits direction and fuse timing orders to the guns. The HACP transmits the computer generated range rate and generated bearing back to the HADT, creating a feedback loop between the HADT and HACP, so that the fire control solution generated by the computer becomes more accurate over time if the target maintains a straight line course. The HADT also observes the accuracy of the resulting shell bursts and uses these bursts to correct target speed and direction estimates, creating another feed back loop from
2924-470: The HACS into a tachymetric system. Also in 1940, radar ranging was added to the HACS. The GRU and its associated computer, the "Gyro Rate Unit Box" (GRUB) no longer assumed straight and level flying on the part of the target. GRU/GRUB could generate target speed and position data at angular rates of up to 6 degrees per second, which was sufficient to track a 360- knot (670 km/h; 410 mph) crossing target at
3010-924: The Luftwaffe with stabilised HACS IV systems with GRU/GRUB and Type 279 radar with the Precision Ranging Panel, which gave +/- 25 yd accuracy out to 14,000 yds. HMS Fiji was sunk in the Battle of Crete after running out of AA ammunition but her HACS IV directed 4-inch AA gun battery fended off Luftwaffe attacks for many hours. Demonstrating the RN's rapid strides in naval AA gunnery, in May 1941, HMS Prince of Wales went to sea with HACS IVGB, with full radar ranging systems, and nine AA associated fire control radars: four Type 285 radar , one on each High Angle Director Tower (HADT) and four Type 282 radar , one on each Mk IV director for
3096-468: The Second World War. During the Cold War the runways and taxiways of some airfields were painted green. While navies are usually responsible for their own air defence—at least for ships at sea—organisational arrangements for land-based air defence vary between nations and over time. The most extreme case was the Soviet Union and this model may still be followed in some countries: it was a separate service, on
3182-505: The UD4 operator would adjust the range and height, and in so doing would update the generated range rate, thereby creating a feedback loop which could establish an estimate of the target's true speed and direction. The HACS also displayed the predicted bearing and elevation of the target on indicators in the Director tower, or on later variants, the HACS could move the entire Director through Remote Power Control so that it could continue to track
3268-606: The United States Army's Balloon Corps to be disbanded mid-war. The Confederates experimented with balloons as well. Turks carried out the first ever anti-airplane operation in history during the Italo-Turkish war . Although lacking anti-aircraft weapons, they were the first to shoot down an airplane by rifle fire. The first aircraft to crash in a war was the one of Lieutenant Piero Manzini, shot down on August 25, 1912. The earliest known use of weapons specifically made for
3354-647: The air force and ground forces respectively. At the other extreme, the United States Army has an Air Defense Artillery Branch that provides ground-based air defence for both homeland and the army in the field; however, it is operationally under the Joint Force Air Component Commander . Many other nations also deploy an air-defence branch in the army. Some, such as Japan or Israel, choose to integrate their ground based air defence systems into their air force. In Britain and some other armies,
3440-413: The altitude at which a gun could deliver a series of shells against a moving target; this could be constrained by maximum fuse running time as well as the gun's capability. By the late 1930s the British definition was "that height at which a directly approaching target at 400 mph [640 km/h] can be engaged for 20 seconds before the gun reaches 70 degrees elevation". The essence of air defence
3526-545: The anti-aircraft role occurred during the Franco-Prussian War of 1870. After the disaster at Sedan , Paris was besieged and French troops outside the city started an attempt at communication via balloon . Gustav Krupp mounted a modified 1-pounder (37 mm) gun – the Ballonabwehrkanone (Balloon defence cannon) or BaK — on top of a horse-drawn carriage for the purpose of shooting down these balloons. By
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3612-425: The army adopted in simplified single-gun mountings for static positions, mostly around ports where naval ammunition was available. The performance of the new guns was limited by their standard fuse No 199, with a 30-second running time, although a new mechanical time fuse giving 43 seconds was nearing readiness. In 1939 a machine fuse setter was introduced to eliminate manual fuse setting. Target drone One of
3698-407: The ascending part of the trajectory can be usefully used. One term is "ceiling", the maximum ceiling being the height a projectile would reach if fired vertically, not practically useful in itself as few AA guns are able to fire vertically, and the maximum fuse duration may be too short, but potentially useful as a standard to compare different weapons. The British adopted "effective ceiling", meaning
3784-457: The battlefield, the AA guns could not be traversed quickly enough at close targets and, being relatively few, were not always in the right place (and were often unpopular with other troops), so changed positions frequently. Soon the forces were adding various machine-gun based weapons mounted on poles. These short-range weapons proved more deadly, and the " Red Baron " is believed to have been shot down by an anti-aircraft Vickers machine gun . When
3870-408: The competition for a share of limited defence budgets. Demobilisation meant that most AA guns were taken out of service, leaving only the most modern. However, there were lessons to be learned. In particular the British, who had had AA guns in most theatres in action in daylight and used them against night attacks at home. Furthermore, they had also formed an Anti-Aircraft Experimental Section during
3956-522: The computer and the minimum range of optical rangefinders. In common with other contemporary navies, pre-war designed RN destroyers suffered from a lack of short-range, rapid-fire AA with which to engage dive bombers. The Auto Barrage Unit or ABU, was a specialised gunnery computer and radar ranging system that used Type 283 radar . It was developed to provide computer prediction and radar anti-aircraft fire control to main and secondary armament guns that did not have inherent anti-aircraft capability. The ABU
4042-583: The director. The HACS was a control system and was made possible by an effective data transmission network between an external gun director, a below decks fire control computer, and the ship's medium calibre anti-aircraft (AA) guns. The bearing and altitude of the target was measured directly on the UD4 Height Finder/Range Finder , a coincidence rangefinder located in the High Angle Director Tower (HADT). The direction of travel
4128-565: The earliest drones was the British DH.82 Queen Bee , a variant of the Tiger Moth trainer aircraft operational from 1935. Its name led to the present term "drone". In their simplest form, target drones often resemble radio-controlled model aircraft. More modern drones may use countermeasures , radar , and similar systems to mimic manned aircraft. More advanced drones are made from large, older missiles which have had their warheads removed. In
4214-674: The early 20th century balloon, or airship, guns, for land and naval use were attracting attention. Various types of ammunition were proposed, high explosive, incendiary, bullet-chains, rod bullets and shrapnel. The need for some form of tracer or smoke trail was articulated. Fuzing options were also examined, both impact and time types. Mountings were generally pedestal type but could be on field platforms. Trials were underway in most countries in Europe but only Krupp, Erhardt, Vickers Maxim, and Schneider had published any information by 1910. Krupp's designs included adaptations of their 65 mm 9-pounder,
4300-482: The enemy aircraft and successfully shot one down. It crashed in the city and both pilots died from their injuries. The cannon Ljutovac used was not designed as an anti-aircraft gun; it was a slightly modified Turkish cannon captured during the First Balkan War in 1912. This was the first occasion in military history that a military aircraft was shot down with ground-to-air artillery fire. The British recognised
4386-723: The extreme heat and humidity in Malayan waters and her 2-pdr ammunition had deteriorated badly as well. The RN made the following claims for ship borne anti-aircraft fire against enemy aircraft, from September 1939 up to 28 March 1941: :Certain kills: 234, Probable kills: 116, Damage claims: 134 The RN made the following claims for ship borne anti-aircraft fire against enemy aircraft, from September 1939 up to 31 Dec 1942: HACS used various director towers that were generally equipped with Type 285 as it became available. This metric wavelength system employed six yagi antennas that could take ranges of targets, and take accurate readings of bearing using
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#17328483507544472-654: The field, wherever they are, provide their own defences against airborne threats. Until the 1950s, guns firing ballistic munitions ranging from 7.62 mm (.30 in) to 152.4 mm (6 in) were the standard weapons; guided missiles then became dominant, except at the very shortest ranges (as with close-in weapon systems , which typically use rotary autocannons or, in very modern systems, surface-to-air adaptations of short-range air-to-air missiles , often combined in one system with rotary cannons). It may also be called counter-air , anti-air , AA , flak , layered air defence or air defence forces . The term air defence
4558-578: The ground-based air defence of the British Army's Anti-Aircraft Command , although field-deployed air defence relied on less sophisticated arrangements. NATO later called these arrangements an "air defence ground environment", defined as "the network of ground radar sites and command and control centres within a specific theatre of operations which are used for the tactical control of air defence operations". Rules of engagement are critical to prevent air defences engaging friendly or neutral aircraft. Their use
4644-400: The guns to the HADT and thence to the HACP, again increasing the accuracy of the solution, if the target maintains a straight line course. Most guns controlled by the HACS had Fuze Setting Pedestals or Fuze Setting Trays where the correct fuze timing was set on a clockwork mechanism within the AA shell warhead, so that the shell would explode in the vicinity of the target aircraft. The HACS
4730-579: The guns. This system of repeater electrical dials built on the arrangements introduced by British coast artillery in the 1880s, and coast artillery was the background of many AA officers. Similar systems were adopted in other countries and for example the later Sperry M3A3 in the US, was also used by Britain as the Predictor AA No 2. Height finders were also increasing in size; in Britain, the seven-foot optical base World War I Barr & Stroud UB 2 stereoscopic rangefinder
4816-500: The intersection of the outer edge of the ellipse where it was crossed by the rotating metal wire. The intersection of the ellipse and the target direction was used as a basis for calculating elevation and training of the guns. The ellipse method had the advantage of requiring very little in the way of mechanical computation and essentially modelled target position in real-time with a consequent rapid solution time. The HADT provides target direction, range, speed, altitude and bearing data to
4902-494: The late 1930s for development work on sound-locating acoustic devices to be generally halted, although equipment was retained. Furthermore, in Britain the volunteer Observer Corps formed in 1925 provided a network of observation posts to report hostile aircraft flying over Britain. Initially radar was used for airspace surveillance to detect approaching hostile aircraft. However, the German Würzburg radar put into use in 1940
4988-601: The main effort has tended to be homeland defence . Missile defence is an extension of air defence, as are initiatives to adapt air defence to the task of intercepting any projectile in flight. Most modern anti-aircraft (AA) weapons systems are optimized for short-, medium-, or long-range air defence, although some systems may incorporate multiple weapons (such as both autocannons and surface-to-air missiles ). ‘Layered air defence’ usually refers to multiple ‘tiers’ of air defence systems which, when combined, an airborne threat must penetrate in order to reach its target; This defence
5074-513: The mobile naval base defence organisation, they were handled as an integral part of the army-commanded ground based air defences. The basic air defence unit is typically a battery with 2 to 12 guns or missile launchers and fire control elements. These batteries, particularly with guns, usually deploy in a small area, although batteries may be split; this is usual for some missile systems. SHORAD missile batteries often deploy across an area with individual launchers several kilometres apart. When MANPADS
5160-487: The need for anti-aircraft capability a few weeks before World War I broke out; on 8 July 1914, the New York Times reported that the British government had decided to "dot the coasts of the British Isles with a series of towers, each armed with two quick-firing guns of special design," while "a complete circle of towers" was to be built around "naval installations" and "at other especially vulnerable points". By December 1914
5246-418: The possibility of destroying expensive targets. The RN allowed media coverage of AA target practice and a 1936 newsreel has footage of a shoot. In 1935 the RN also began to practice HACS controlled shoots of target aircraft at night. The RN moved quickly to add true tachometric target motion prediction and radar ranging to the HACS by mid 1941. The RN was the first navy to adopt dedicated FC AA radars. However
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#17328483507545332-461: The shells' predicted trajectory. This was called deflection gun-laying, where "off-set" angles for range and elevation were set on the gunsight and updated as their target moved. In this method, when the sights were on the target, the barrel was pointed at the target's future position. Range and height of the target determined fuse length. The difficulties increased as aircraft performance improved. The British dealt with range measurement first, when it
5418-507: The shortcomings of HACS are often blamed for the loss of Force Z , the scope of the Japanese attack far exceeded anything the HACS had been designed to handle in terms of aircraft numbers and performance. The failure of anti-aircraft gunnery to deter the Japanese bombers was also influenced by unique circumstances. The HACS was originally designed with Atlantic conditions in mind and Prince of Wales ' s AA FC radars had become unserviceable in
5504-569: The single artillery branch has been responsible for both home and overseas ground-based air defence, although there was divided responsibility with the Royal Navy for air defence of the British Isles in World War I . However, during the Second World War , the RAF Regiment was formed to protect airfields everywhere, and this included light air defences. In the later decades of the Cold War this included
5590-477: The speed and direction of both the target and the projectile. Throughout the 20th century, air defence was one of the fastest-evolving areas of military technology, responding to the evolution of aircraft and exploiting technology such as radar, guided missiles and computing (initially electromechanical analogue computing from the 1930s on, as with equipment described below). Improvements were made to sensors, technical fire control, weapons, and command and control. At
5676-422: The start of the 20th century these were either very primitive or non-existent. Initially sensors were optical and acoustic devices developed during World War I and continued into the 1930s, but were quickly superseded by radar, which in turn was supplemented by optoelectronics in the 1980s. Command and control remained primitive until the late 1930s, when Britain created an integrated system for ADGB that linked
5762-488: The system, in common with all World War II-era mechanical AA fire control system still had severe limitations as even the highly advanced United States Navy (USN) Mk 37 system in 1944 needed an average of 1,000 rounds of 5-inch (127 mm) ammunition fired per kill. In 1940 the Gyro Rate Unit (GRU) was added to the HACS system, an analogue computer capable of directly calculating target speed and direction, converting
5848-463: The target and having its height. Second, that the target would maintain a steady course, speed and height. This HAA was to engage targets up to 24,000 ft (7.3 km). Mechanical time fuses were required because the speed of powder burning varied with height, so fuse length was not a simple function of time of flight. Automated fire ensured a constant rate of fire that made it easier to predict where each shell should be individually aimed. In 1925
5934-597: The target if the target became obscured. The angle measured by the graticule also caused a metal wire to rotate around the face of a large circular display on one side of the HACS, known as the Deflection Display . The measured value of altitude and range, and estimated value of target speed, caused optics to focus a lamp onto a ground glass screen behind the wire, displaying an ellipse whose shape changed based on these measures. The deflection operator used two controls to move additional wire indicators so they lay on top of
6020-409: The war and accumulated large amounts of data that was subjected to extensive analysis. As a result, they published the two-volume Textbook of Anti-Aircraft Gunnery in 1924–1925. It included five key recommendations for HAA equipment: Two assumptions underpinned the British approach to HAA fire; first, aimed fire was the primary method and this was enabled by predicting gun data from visually tracking
6106-437: The war ended, it was clear that the increasing capabilities of aircraft would require better means of acquiring targets and aiming at them. Nevertheless, a pattern had been set: anti-aircraft warfare would employ heavy weapons to attack high-altitude targets and lighter weapons for use when aircraft came to lower altitudes. World War I demonstrated that aircraft could be an important part of the battlefield, but in some nations it
6192-440: The years immediately after World War I, the prospect of another major war seemed remote, particularly in Europe, where the most militarily capable nations were, and little financing was available. Four years of war had seen the creation of a new and technically demanding branch of military activity. Air defence had made huge advances, albeit from a very low starting point. However, it was new and often lacked influential 'friends' in
6278-571: Was capable of providing data suitable for controlling AA guns, and the British Radar, Gun Laying, Mark I , was designed to be used on AA gun positions and was in use by 1939. The Treaty of Versailles prevented Germany having AA weapons, and for example, the Krupps designers joined Bofors in Sweden. Some World War I guns were retained and some covert AA training started in the late 1920s. Germany introduced
6364-497: Was designed to allow the guns to be pre-loaded with time fused ammunition, and it then tracked incoming enemy aircraft, aimed the guns continuously to track the aircraft, and then fired the guns automatically when the predicted aircraft position reached the preset fuse range of the previously loaded shells. The ABU was also used with guns that were nominally controlled by the HACS to provide a limited blind fire capability. By May 1941, RN cruisers, such as HMS Fiji , were engaging
6450-581: Was determined by time of flight, but the burning rate of the gunpowder was affected by altitude. The British pom-poms had only contact-fused ammunition. Zeppelins , being hydrogen-filled balloons, were targets for incendiary shells and the British introduced these with airburst fuses, both shrapnel type-forward projection of incendiary "pot" and base ejection of an incendiary stream. The British also fitted tracers to their shells for use at night. Smoke shells were also available for some AA guns, these bursts were used as targets during training. German air attacks on
6536-404: Was electrical; the operator entered the target range and had displays at guns; it was used with their 75 mm. The British Wilson-Dalby gun director used a pair of trackers and mechanical tachymetry; the operator entered the fuse length, and deflection angles were read from the instruments. By the start of World War I , the 77 mm had become the standard German weapon, and came mounted on
6622-437: Was fitted with centimetric Type 275 radar . Another improvement was the addition of Remote Power Control ( RPC ), in which the anti-aircraft guns automatically trained with the director tower, with the necessary changes in bearing and elevation to allow for convergent fire. Previously the gun crews had to follow mechanical pointers that indicated where the director tower wanted the guns to train. HACS Directors fitted to ships in
6708-462: Was hydraulically driven, featured much improved data transmission and it introduced the HACS III Table. The HACS III table (computer) had numerous improvements including raising maximum target speed to 350 kn (650 km/h; 400 mph), continuous automatic fuze prediction, improved geometry in the deflection Screen, and provisions for gyro inputs to provide stabilisation of data received from
6794-525: Was measured by aligning a binocular graticule with the target aircraft fuselage. The early versions of HACS, Mk. I through IV, did not measure target speed directly, but estimated this value based on the target type. All of these values were sent via selsyn to the HACS in the High Angle Calculating Position (HACP) located below decks. The HACS used these values to calculate the range rate (often called rate along in RN parlance), which
6880-575: Was probably first used by the UK when Air Defence of Great Britain (ADGB) was created as a Royal Air Force command in 1925. However, arrangements in the UK were also called "anti-aircraft", abbreviated as AA , a term that remained in general use into the 1950s. After the First World War it was sometimes prefixed by "light" or "heavy" (LAA or HAA) to classify a type of gun or unit. Nicknames for anti-aircraft guns include "AA", "AAA" or "triple-A" (abbreviations of "anti-aircraft artillery"), "flak" (from
6966-472: Was realised that range was the key to producing a better fuse setting. This led to the height/range finder (HRF), the first model being the Barr & Stroud UB2, a two-metre optical coincident rangefinder mounted on a tripod. It measured the distance to the target and the elevation angle, which together gave the height of the aircraft. These were complex instruments and various other methods were also used. The HRF
7052-572: Was replaced by the nine-foot optical base UB 7 and the eighteen-foot optical base UB 10 (only used on static AA sites). Goertz in Germany and Levallois in France produced five m (16 ft) instruments. However, in most countries the main effort in HAA guns until the mid-1930s was improving existing ones, although various new designs were on drawing boards. From the early 1930s eight countries developed radar ; these developments were sufficiently advanced by
7138-551: Was soon joined by the height/fuse indicator (HFI), this was marked with elevation angles and height lines overlaid with fuse length curves, using the height reported by the HRF operator, the necessary fuse length could be read off. However, the problem of deflection settings — "aim-off" — required knowing the rate of change in the target's position. Both France and the UK introduced tachymetric devices to track targets and produce vertical and horizontal deflection angles. The French Brocq system
7224-479: Was the first Naval AA system to be used against radio controlled aircraft , and achieved the first AA kill against these targets in 1933. In March 1936, six Queen Bee targets were destroyed by the RN Mediterranean Fleet during intensive AA practice at a time of extreme tension between the UK and Italy. Target practice against target drones was carried out using special shells which were designed to minimise
7310-501: Was the guns protecting spotting balloons, in which case the altitude could be accurately measured from the length of the cable holding the balloon. The first issue was ammunition. Before the war it was recognised that ammunition needed to explode in the air. Both high explosive (HE) and shrapnel were used, mostly the former. Airburst fuses were either igniferious (based on a burning fuse) or mechanical (clockwork). Igniferious fuses were not well suited for anti-aircraft use. The fuse length
7396-496: Was the prospect of strategic air attack that was the main issue, presenting both a threat and an opportunity. The experience of four years of air attacks on London by Zeppelins and Gotha G.V bombers had particularly influenced the British and was one of if not the main driver for forming an independent air force. As the capabilities of aircraft and their engines improved it was clear that their role in future war would be even more critical as their range and weapon load grew. However, in
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