Anti-aircraft warfare
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Anti-aircraft warfare, or air defense, is any method of engaging military aircraft in combat from the ground. Various guns and cannons have been used in this role since the first military aircraft were used in World War I, growing in power and accuracy over the years. Starting in the post-World War II era the guns were joined by the guided missile, specifically the "surface-to-air missile", and today both are used in combination in most roles.
Adaptations of standard artillery systems were commonly used for most long-range anti-aircraft artillery, starting with standard pieces on new mountings, and evolving to custom guns with much higher performance prior to World War II. Their shells are usually fitted with different types of fuses (barometric, time-delay, or proximity) to send exploding metal fragments into the area of the target. The classic example of a large calibre, long-range anti-aircraft gun is the German 88 mm gun. Long-range weapons of this sort have for the most part been superseded by the effective anti-air missile systems that were introduced in the 1950s; however, because they are relatively inexpensive and easy to manufacture compared to more modern systems, they are still employed in large numbers by many nations.
For shorter-range work, a lighter weapon with a higher rate of fire is required, to guarantee a hit on a quickly traversing target. Weapons of 20 mm, 37 mm, and 40 mm have been widely used in this role. Unlike the heavier guns, these smaller weapons are still in widespread use today for the same reasons as they were originally introduced: the ability to quickly follow the target. Modern systems often use weapons generally known as autocannon, that were originally intended for air-to-ground use. However, developments in the latest short-range missiles means that these appear to be able to replace guns even in this role.
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 Fliegerabwehrkanone, aircraft defense cannon). An anti-aircraft missile is another name for a surface-to-air missile.
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. It uses the Stinger missile (fired by troops or from vehicles) at one end of the scale and the anti-aircraft/anti-missile Patriot system at the other.
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[edit] History
[edit] Earliest use
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 quickly modified a 1 pounder (20 mm) gun to be mounted on top of a horse-drawn carriage for the purpose of shooting down these balloons. Very little information on this weapon has been published.
[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 the bunch.
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 accuracy, gunners proved unable to get the altitude correct and most rounds fell well below their targets. 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 guns were later supplied with an optical sighting system and soon 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, larger weapons proved too ponderous to aim at the quickly moving 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 20 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 much 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 specificially 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. 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 wholescale 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.
Their 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 later role that it became most widely known, the bane of Allied tank crews everywhere.
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 centralized 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 coast guard frigates.
At the start of the war Britain had started a slow upgrade to their own systems, including a new QF 3.75 inch (94 mm) gun in addition to their existing WWI-era 3 inch guns. Both were 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 make workers on the assembly line 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, and 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 for ranging, and then tracking. Similar systems were introduced by Germany during the war, which also added 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 altitude capability was introduced. The 90 mm and 120 mm guns would continue to be used into the 1950s.
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 on 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 the war the first ventures into the use of rocket-powered missiles for shooting down aircraft began. The British started with unguided missiles, the 2 inch RP, 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.
One 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 favourable 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 newer 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 defense 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 defense 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 (based on the German Wasserfall), 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. Even at the smallest scale, man-portable missiles, MANPADs as they are known today, were introduced in the 1960s.
[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, 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 originally intended to be used in this role since the late 1960s, 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 militaries integrate air defence purely with the traditional arms of the military (i.e. army, navy and air force). 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 surface-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 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 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, say, 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-11 Gadfly.
[edit] Air force
Air defence by air forces is typically taken care of by fighter jets carrying air-to-air missiles which is beyond the scope of this article, however most air forces choose to augment air base defence with surface-to-air missile systems as they are such valuable targets for 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] 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] External links
- Archie to SAM: A Short Operational History of Ground-Based Air Defense by Kenneth P. Werrell (book available for download)
[edit] Japan
- Japanese Imperial Forces(World War Two)
- Japanese Self Defense Forces(present days)
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