Anti-aircraft warfare
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Anti-aircraft warfare, or air defense, is any method of engaging hostile military aircraft in defence of ground objectives, ground or naval forces or denial of passage through a specific airspace region, area or anti-aircraft combat zone[1]. It is also used in denying entry into national air space to unauthorised aircraft.
From the initial introduction of aircraft into combat during the First World War the means to achieve air defense included infantry firearms, light anti-aircraft weapons, cannons and anti-aircraft artillery as well as barrage balloons and Interceptor aircraft, with all, aided by radar installations, growing in power and accuracy over the course of the 20th century, particularly with the introduction of the surface-to-air missile.
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[edit] Origin of the term
Nicknames for anti-aircraft guns include AAA or triple-A, an abbreviation for anti-aircraft artillery, ack-ack (from the World War I phonetic alphabet for AA), archie (a WWI British term believed to derive via the Royal Flying Corps from the music-hall comedian George Robey's line "Archibald, certainly not!"), and flak (from the German Flugabwehrkanone, aircraft defence cannon).[1] An anti-aircraft missile is another name for a surface-to-air missile, abbreviated and pronounced SAM.
The United States Navy uses the term Anti-Air Warfare (AAW); most groups of ships have a designated AAW commander among them. The Soviet Anti-Air Defense was a separate armed service, but in Russia has been subordinated to the Air Force. The United States Army has generally been able to count on air superiority to reduce the threat from air attack on its ground units, and settles for a two-tier structure: the man-portable Stinger missile (fired by troops or from vehicles) and the anti-aircraft/anti-missile Patriot system. Countries less assured of air superiority have more tiers. Russia, for example, has a system consisting of battalion-level MANPADS, regimental SHORAD (typically autocannon and IR/SACLOS SAMs), divisional SHORAD (typically short-ranged radar guided SAMs), medium range Army level (SA-11) and long range Front level (SA-12) systems.
[edit] Anti-aircraft warfare systems
Although the firearms used by the infantry can be used to engage air targets, on occasion with notable success, they are in general not effective against modern jet aircraft, or aircraft designed for the ground attack role.
Adaptations of the standard autocannon, originally intended for air-to-ground use, and heavier artillery systems were commonly used for most anti-aircraft gunnery, starting with standard pieces on new mountings, and evolving to specially designed guns with much higher performance prior to World War II. The ammunition and shells fired by these weapons are usually fitted with different types of fuses (barometric, time-delay, or proximity) to send exploding metal fragments into the area of the airborne target. For shorter-range work, a lighter weapon with a higher rate of fire is required, to increase a hit probability on a fast airborne target. Weapons between 20 mm and 40 mm caliber have been widely used in this role. Smaller weapons, typically .50 caliber or even 8 mm rifle caliber guns have been used in the smallest mounts. Unlike the heavier guns, these smaller weapons are in widespread use due to their low cost and ability to quickly follow the target. The classic examples of autocannons and large caliber guns are the 40 mm autocannon and the 8,8 cm FlaK 18, 36 gun, both designed by Bofors of Sweden. Artillery weapons of this sort have for the most part been superseded by the effective surface-to-air missile systems that were introduced in the 1950s, although still retained by many nations.
The development of surface-to-air missiles began in Nazi Germany (hard pressed by Allied air superiority) during the late World War II with missiles such as the Wasserfall though no working system was deployed before the war's end, and represented new attempts to increase effectiveness of the anti-aircraft systems faced with growing threat from the bombers. Land-based SAMs can be deployed from fixed installations or mobile launchers, either wheeled or tracked. The tracked vehicles are usually armoured vehicles specifically designed to carry SAMs. Larger SAMs may be deployed in fixed launchers, but can be towed/re-deployed at will. The SAMs launched by individuals are known in the United States as the Man-Portable Air Defence Systems (MANPADS). MANPADS of the former Soviet Union have been exported around the World, and can be found in use by many armed forces. Targets for non-ManPAD SAMs will usually be acquired by air-search radar, then tracked before/while a SAM is "locked-on" and then fired. Potential targets, if they are military aircraft, will be identified as friend or foe before being engaged. The developments in the latest and relatively cheap short-range missiles have begun to replace autocannos in this role.
The interceptor aircraft (or simply interceptor) is a type of fighter aircraft designed specifically to intercept and destroy enemy aircraft, particularly bombers, usually relying on high speed and altitude capabilities. A number of aircraft such as the F-104 and the MiG-25 were built in the period starting just prior to World War II and ending in the late 1960s, when they became less important due to the shifting of the strategic bombing role to ICBMs. Invariably the type is differentiated from other fighter aircraft designs by higher speeds and shorted operating ranges, as well as much reduced ordnance payloads.
The radar systems use electromagnetic waves to identify the range, altitude, direction, or speed of aircraft and weather formations to provide tactical and operational warning and direction, primarily during defensive operations. In their functional roles they provide target search, threat, guidance, reconnaissance, navigation, instrumentation, and weather reporting support to combat operations.
[edit] History
[edit] Earliest use
The use of balloons by the Union 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, but internal politics led the Union's Balloon Corps to be disbanded in midwar. For further information, see "Confederate Responses to Union Balloon Operations during the American Civil War," in the Spring 2007 issue of the American Association of Aviation Historians Journal.
The earliest known use of weapons specifically made for 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 resupply via balloon. Krupp mounted a modified a 1-pounder gun (~32 mm) on top of a horse-drawn carriage for the purpose of shooting down these balloons, the balloonkanone.
[edit] World War I
Given this early history, it is perhaps not surprising that it was only in Germany that development of anti-aircraft guns continued. In 1909, a number of Krupp's designs were shown, including adaptations of their 65 mm 9-pounder, a 75 mm 12-pounder, and even a 105 mm gun. By the start of World War I, the 75 mm had become the standard German weapon, and came mounted on a large traverse that could be easily picked up on a wagon for movement.
Other countries seem to have largely ignored the possibility of aircraft being an important part of hostilities, but this soon changed when German spotter aircraft started calling down increasingly accurate artillery fire. All armies soon deployed a number of guns based on their smaller field pieces, notably 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 decided on an entirely new weapon, and deployed a 3-inch (76 mm) gun that was perhaps the best of all the designs at that time. The German Army also adapted a revolving-cannon that came to be known to Allied fliers as the "flaming onion". This gun had five barrels that quickly launched a series of 37 mm artillery shells.[2]
In general, these ad-hoc solutions proved largely useless. With little experience in the role, and no ability to spot the "fall" of their rounds with any accuracy, gunners proved unable to get the altitude correct and most rounds fell well below their targets (discovering this, British fliers gave German AAA the mocking nickname, "Archie"). The exception to this rule were the guns protecting spotting balloons, in which case the altitude could be accurately measured from the length of the cable holding the balloon. The Krupp 75 mm guns were later supplied with an optical sighting system that improved their capabilities, but these sorts of systems were not deployed by other forces.
As aircraft started to be used in tactical roles against ground targets, these larger weapons proved too ponderous to aim at the quickly traversing targets. Soon the forces were adding various machine gun based weapons mounted on poles. The British introduced a heavier weapon — their 1-pounder "pom-pom" (a 37 mm version of the Maxim Gun) on an elevated mounting. These short-range weapons proved more deadly, and the Red Baron arguably fell victim to an anti-aircraft Vickers machine gun.
When the war ended, it was clear that the increasing capabilities of aircraft would require a more serious attempt at downing them. Nevertheless the pattern had been set: anti-aircraft weapons would be based around heavy weapons attacking high-altitude targets and lighter weapons for use when they came to lower altitudes.
[edit] World War II
World War I had proven that the aircraft was an important part of the battlefield. As the capabilities of aircraft improved, and more specifically their engines, it was clear that their role in future combat would be even more critical as their warload grew. Many felt that the higher speeds and altitudes would render anti-aircraft systems useless, so little effort was put into improving systems.
Once again, it was only Germany that seriously considered what to do about this with any lead time before the war started. They developed a number of new anti-aircraft weapons in the late 1920s and early 1930s, often in collaboration with Swiss and Swedish companies, including a new rapid-fire 20 mm gun for low-altitude work, and a 37 mm gun for low and medium altitudes. By the mid-1930s the 20 mm was considered to be too low power against the increasingly fast planes but, instead of introducing a new gun, Krupp managed to squeeze four of the existing 20 mm guns onto a single carriage of about the same weight. This improved firepower enough to make a switch to a larger gun unattractive in comparison. By the end of the war Germany had essentially given up on the 20 mm as it lacked punch. It was never cleanly replaced however; the 37 mm was available in limited numbers, and a new dual-30 mm system based on the MK 108 aircraft gun was never put into widespread use.
Germany's high-altitude needs were originally going to be filled by a 75 mm gun from Krupp, designed in collaboration with their Swedish counterpart Bofors, but the specifications were later amended to require much higher performance. In response Krupp's engineers presented a new 88 mm design, the FlaK 88. The eighty-eight would go on to become one of the most famous artillery pieces in history. First used in Spain during the Spanish Civil War, the gun proved to be one of the best anti-aircraft guns in the world, as well as particularly deadly against tanks. It is in this latter role that it became most widely known, the bane of Allied tank crews wherever it appeared.
After the Dambusters raid in 1943 an entirely new system was developed that was required to knock down any low-flying aircraft with a single hit. The first attempt to produce such a system used a 50 mm gun, but this proved inaccurate and a new 55 mm gun replaced it. The system used a centralised control system including both search and targeting radar, which calculated the aim point for the guns after considering windage and ballistics, and then sent electrical commands to the guns which used hydraulics to point themselves at high speeds. Operators simply fed the guns and selected the targets. This system, modern even by today's standards, was in late development when the war ended.
In the late 1920s the Swedish Navy had ordered the development of a 40-mm naval anti-aircraft gun from the Bofors company. The new gun proved to be light, fast and reliable, and a mobile version on a four wheel carriage was soon developed. Known simply as the 40 mm, it was adopted by some 17 different nations just before WWII and is still in use today in some applications such as on coastguard frigates.
Prior to the war, Britain had followed conventional wisdom that the "bomber would always get through" and spent little effort on air defence. The introduction of radar so upset this conventional wisdom that, starting in the second half of the 1930s, a major effort was made to dramatically improve all defensive weapons. Up to this point, they had relied on their WWI-era 3 inch guns, but these were clearly outdated and a new QF 3.75 inch (94 mm) gun was introduced that was arguably the best anti-aircraft weapon of WWII. Both the 3 inch and 3.7 inch delivered with optical sighting systems for ranging. At the small-end of the scale a number of 20 mm designs were used, but testing showed, as Germany had discovered, that these weapons were of little use against modern aircraft.
They had already arranged license building of the 40 mm Bofors gun, and introduced these into service. These had the power to knock down aircraft of any size, yet were light enough to be mobile and easily swung. The gun became so important to the British war effort that they even produced a movie, The Gun, in order to encourage workers on the assembly line to work harder. The Imperial measurement production drawings the British had developed were supplied to the Americans who produced their own (unlicensed) copy of the 40 mm at the start of the war—moving to licensed production in mid-1941.
Service trials demonstrated another problem however: that the problem of ranging and tracking the new high-speed targets was almost impossible. At shorter ranges, the "lead" required (aiming in front of the target because it is moving) is so small that it can be done manually while, at very long ranges, the apparent speed is so slow that simple mechanical slide rules could be used. For the ranges and speeds that the Bofors worked at, neither solution was good enough.
The solution was automation, in the form of a mechanical computer, the Kerrison Predictor. Operators kept it pointed at the target, and the Predictor then calculated the proper aim point automatically and displayed it as a pointer mounted on the gun. The gun operators simply followed the pointer and loaded the shells. The Kerrison was fairly simple, but it pointed the way to future generations which incorporated radar, first for ranging and then later for tracking. Similar predictor systems were introduced by Germany during the war, also adding radar ranging as the war progressed.
Although they receive little attention, US Army anti-aircraft systems were actually quite competent. Their smaller tactical needs were filled with four M2 .50 caliber machine guns linked together (known as the “Quad Fifty”), which were often mounted on the back of a half-track to form the Half Track, M16 GMC, Anti-Aircraft. Although of even less power than Germany's 20 mm systems, they were at least widely available. Their larger 90 mm M3 gun would prove, as did the eighty-eight, to make an excellent anti-tank gun as well, and was widely used late in the war in this role. Finally, just as the war was ending, the new 120 mm M1 gun stratosphere gun with an impressive 60,000 ft (~18km) altitude capability was introduced. The 90 mm and 120 mm guns would continue to be used into the 1950s.
The US Navy had also put some thought into the problem, and came up with the 1.1"/75 (28mm) gun to replace the inadequate .50 caliber. This weapon had the teething troubles that most new weapons have, but the issues with the gun were never sorted out. It was replaced by the Bofors 40 mm wherever possible. The 5"/38 caliber gun turned out to be an excellent anti-aircraft weapon, once the Proximity fuze had been perfected.
The Germans developed massive reinforced concrete blockhouses, some more than six stories high, which were known as Hochbunker "High Bunkers" or "Flakturm" Flak Towers, on which they placed anti-aircraft artillery. Those which were in cities attacked by the Allied land forces became fortresses. Several in Berlin were some of the last buildings to fall to the Soviets during the Battle of Berlin in 1945. The British built structures in the Thames Estuary and other tidal areas upon which they based guns. After the war most were left to rot. Some were outside territorial waters, and had a second life in the 1960s as platforms for pirate radio stations.
During WWII, the use of rocket-powered missiles for shooting down aircraft began. The British started with a unguided rocket, the 2 inch RP which was fired in large numbers from Z batteries. The firing of one of these devices during an air raid is suspected to have caused the Bethnal Green Disaster in 1943. By the end of the war, the British had developed a surface-to-air missile, Stooge, which would have been launched from Royal Navy ships against the Japanese Kamikaze attacks. The Germans invested heavily in various anti-aircraft missile projects as well, but none of these was ready for service before the war ended. In particular, the Wasserfall missile, based on a scaled-down V-2, was particularly powerful and would have been a deadly weapon had the electronics ever matured.
Another aspect of anti-aircraft defence was the use of barrage balloons to act as physical obstacle initially to bomber aircraft over cities and later for ground attack aircraft over the Normandy invasion fleets. The balloon, a simple blimp tethered to the ground, worked in two ways. Firstly, it and the steel cable were a danger to any aircraft that tried to fly among them. Secondly, in avoiding the balloons, the bombers were forced up to a higher level which was more favorable for the guns. The barrage balloon was limited in application and direct success at bringing down aircraft—being largely immobile and passive weapons.
[edit] Post-war
Post-war analysis demonstrated that even with newest anti-aircraft systems employed by both sides, the vast majority of bombers reached their targets successfully, on the order of 90%. This was bad enough during the war, but the introduction of the nuclear bomb upset things considerably. Now even a single bomber reaching the target would be unacceptable.
The developments during WWII continued for a short time into the post-war period as well. In particular the US Army set up a huge air defence network around its larger cities based on radar-guided 90 mm and 120 mm guns. But, given the general lack of success of guns against even propeller bombers, it was clear that any defence was going to have to rely almost entirely on interceptor aircraft. Despite this, US efforts continued into the 1950s with the 75 mm Skysweeper system, an almost fully-automated system including the radar, computers, power, and auto-loading gun on a single powered platform. The Skysweeper replaced all smaller guns then in use in the Army, notably the 40 mm Bofors.
Things changed with the introduction of the guided missile. Although Germany had been desperate to introduce them during the war, none were ready for service, and British countermeasures were likely to defeat them even if they were. With a few years of development, however, these systems started to mature into practical weapons. The US started an upgrade of their defenses using the Nike Ajax missile, and soon the larger anti-aircraft guns disappeared. The same thing occurred in the USSR after the introduction of their SA-2 Guideline systems.
As this process continued, the missile found itself being used for more and more of the roles formerly filled by guns. First to go were the large weapons, replaced by equally large missile systems of much higher performance. Smaller missiles soon followed, eventually becoming small enough to be mounted on armored cars and tank chassis. These started replacing, or at least supplanting, similar gun-based SPAAG systems in the 1960s, and by the 1990s had replaced almost all such systems in modern armies. Man-portable missiles, MANPADs as they are known today, were introduced in the 1960s and have supplanted or even replaced even the smallest guns in most advanced armies.
[edit] Future developments
If current trends continue, missiles will replace gun systems completely in "first line" service. Guns are being increasingly pushed into specialist roles, such as the Dutch Goalkeeper CIWS which uses the GAU-8/A Avenger 30 mm seven-barrel Gatling Gun, or the US Phalanx CIWS which uses a 20 mm M61 Vulcan gun firing at over 4,500 rounds per minute for last ditch anti-missile and anti-aircraft fighting. Even this formerly first-rate weapon is currently being replaced by a new missile system, the Rolling Airframe Missile, which is smaller, faster, and allows for mid-flight course correction (guidance) to ensure a hit.
Upsetting this development to all-missile systems is the current move to stealth aircraft. Long range missiles depend on long-range detection in order to provide significant lead. Stealth designs cut detection ranges so much that the aircraft is often never even seen, and when it is, often too late for an intercept. Systems for detection and tracking of stealthy aircraft are a major problem for anti-aircraft development.
Another potential weapon system for anti-aircraft use is the laser. Although air planners imagined lasers in combat since the late 1960s, only the most modern laser systems are currently reaching what could be considered "experimental usefulness". In particular the Tactical High Energy Laser can be used in the anti-aircraft and anti-missile role. If current developments continue, it is reasonable to suggest that lasers will play a major role in air defense starting in the next ten years.
[edit] Force structures
Most Western and Commonwealth militaries integrate air defence purely with the traditional services, of the military (i.e. army, navy and air force), as a separate arm or as part of artillery. In the United States Army for instance, air defence is part of the artillery arm, while in the Pakistan Army, it was split off from Artillery to from a separate army of its own in 1990. This is in contrast to some (largely communist or ex-communist) countries where not only are there provisions for air defence in the army, navy and air force but there are specific branches which deal only with the air defence of territory, for example, the Soviet PVO Strany. The USSR also had a separate strategic rocket force in charge of nuclear ICBMs.
[edit] Navy
Virtually all modern vessels contain anti-aircraft weapon systems. Smaller boats and ships typically have machine-guns or fast cannons, which can often be deadly to low-flying aircraft if linked to a radar-directed fire-control system. Larger vessels (patrol boats, frigates, destroyers and on up) are typically equipped with surface-to-air missile systems, with increased range and deadliness as the vessel size increases, although virtually all also carry radar-controlled cannon for point defence. Some vessels like Aegis cruisers are as much a threat to aircraft as any land-based air defence system. In general, naval vessels should be treated with respect by aircraft, however the reverse is equally true. Carrier battle groups are especially well defended, as not only do they typically consist of many vessels with heavy air defence armament but they are also able to launch fighter jets for combat air patrol overhead to intercept incoming airborne threats.
Some modern submarines, such as the Type 212 submarines of the German Navy, are equipped with surface-to-air missile systems, since helicopters and anti-submarine warfare aircraft are significant threats.
[edit] Army
Armies typically have air defence in depth, from integral MANPADS like RBS 70, Stinger and Igla at smaller force levels up to army-level missile defence systems such as Angara and Patriot. Often, the high-altitude long-range missile systems force aircraft to fly at low level, where anti-aircraft guns can bring them down. As well as the small and large systems, for effective air defence there must be intermediate systems. These may be deployed at regiment-level and consist of platoons of self-propelled anti-aircraft platforms, whether they are self-propelled anti-aircraft guns (SPAAGs), integrated air-defence systems like Tunguska or all-in-one surface-to-air missile platforms like Roland or SA-8 Gecko.
[edit] Air force
Air defence by air forces is typically taken care of by fighter jets carrying air-to-air missiles. However most air forces choose to augment airbase defence with surface-to-air missile systems as they are such valuable targets and subject to attack by enemy aircraft. In addition, countries without dedicated air defence forces often relegate these duties to the air force. For example, the United States' strategic air defence is the domain of the Air Force, even when it is performed by missiles launched from fixed installations. For example, see Project Nike.
[edit] Area air defence
Area air defence, the air defence of an specific area or location, (as opposed to point defence), have historically been operated by both armies (Anti-Aircraft Command in the British Army, for instance) and Air Forces (the USAF's Nike Hercules and its sibling programmes). Area defence systems have medium to long range and can be made up of various other systems and networked into an area defence system (in which case it may be made up of several short range systems combined to effectively cover an area). An example of area defence is the defence of Saudi Arabia and Israel by MIM-104 Patriot missile batteries during the first Gulf War, where the objective was to cover populated areas.
[edit] Tactics
[edit] Mobility
Most modern air defence systems are fairly mobile. Even the larger systems tend to be mounted on trailers and are designed to be fairly quickly broken down or set up. In the past, this was not always the case. Early missile systems were cumbersome and required much infrastructure—many could not be moved at all. With the diversification of air defence there has been much more emphasis on mobility. Most modern systems are usually either self-propelled (i.e. guns or missiles are mounted on a truck or tracked chassis) or easily towed. Even systems which consist of many components (transporter/erector/launchers, radars, command posts etc.) benefit from being mounted on a fleet of vehicles. In general, a fixed system can be identified, attacked and destroyed whereas a mobile system can show up in places where it is not expected. Soviet systems especially concentrate on mobility, after the lessons learnt in the Vietnam proxy war between the USA and USSR. For more information on this part of the conflict, see SA-2 Guideline.
North Korea (officially the DPRK) has inherited a lot of older Soviet equipment. One major reason for the success of the U.N. forces during the Korean War (1950–1953) against the DPRK and PRC was the air superiority they were able to attain. As tensions still exist on the Korean Peninsula and the DPRK is so heavily militarised, their air-defence network is amongst the strongest of a non-superpower. A large part of it consists of a number of older, fixed systems like SA-2, SA-3, SA-4 and SA-5. But the DPRK is also in possession of many mobile systems which have proven to be deadly in the past.
[edit] Air defence versus air defence suppression
The U.S. Air Force, in conjunction with the members of NATO, has developed significant tactics for air defence suppression. Dedicated weapons such as anti-radiation missiles and advanced electronics intelligence and electronic countermeasures platforms seek to suppress or negate the effectiveness of an opposing air-defence system. It is an arms race; as better jamming, countermeasures and anti-radiation weapons are developed, so are better SAM systems with ECCM capabilities and the ability to shoot down anti-radiation missiles and other munitions aimed at them or the targets they are defending. Now that Russia is beginning to offer top quality SAM systems for export, it is possible that the U.S. and NATO forces could face serious challenges in maintaining air superiority in future conflicts. This will mainly be determined by the effectiveness of these devices and tactics.
[edit] See also
[edit] References
- ^ The anti-aircraft combat zone is defined by the technical capabilities of the available defensive weapons to engage the targets
- ^ flaming onions? - The Aerodrome Forum
[edit] External links
- Archie to SAM: A Short Operational History of Ground-Based Air Defense by Kenneth P. Werrell (book available for download)
- Japanese Antiaircraft land/vessel doctrines in 1943-44
