Despite the fact that the American military has lost interest in anti-aircraft artillery, the development of new anti-aircraft installations of medium and small caliber in the post-war period did not stop. In 1948, a 75-mm automatic anti-aircraft gun M35 revolving type was created in the USA. The ammunition of this gun was automatically replenished when firing using a special loader. Thanks to this, the practical rate of fire was 45 rds / min, which was an excellent indicator for a towed anti-aircraft gun of this caliber. The appearance of an automatic 75-mm anti-aircraft gun was due to the fact that during the Second World War there was a "difficult" for anti-aircraft artillery range of altitudes from 1500 to 3000 m. was too small. In order to solve the problem, it seemed natural to create anti-aircraft guns of some intermediate caliber.
Due to the fact that jet combat aviation in the post-war period developed at a very rapid pace, the army command put forward a demand that the new anti-aircraft gun mount should be able to deal with aircraft flying at a speed of 1600 km / h at an altitude of 6 km. However, it was unrealistic to withstand such stringent requirements, and the maximum speed of an effectively fired target was subsequently limited to 1100 km / h. It is clear that entering data on target parameters manually at a speed close to sound would be absolutely ineffective, therefore, a combination of search and guidance radar with an analog computer was used in the new anti-aircraft installation. All this rather cumbersome economy was combined with an artillery unit. The T-38 radar with a parabolic antenna was mounted in the upper left part of the gun mount. Guidance was carried out by electric drives. The gun had an automatic remote fuse installer, which significantly increased the effectiveness of firing. Tests carried out in 1951-1952 demonstrated the efficiency of the guidance equipment and the ability to detect and track air targets at a distance of up to 30 km. The maximum firing range reached 13 km, and the effective range was 6 km.
M51 Skysweeper
In March 1953, the 75-mm automatic anti-aircraft gun with radar guidance, dubbed the M51 Skysweeper, began to enter the anti-aircraft units of the ground forces. These gun mounts were placed in stationary positions along with 90 and 120-mm anti-aircraft guns. The transfer of the M51 to a combat position was quite troublesome. In the stowed position, the anti-aircraft gun was transported on a four-wheeled cart, upon arrival at the firing position, it was lowered to the ground and rested on four cruciform supports. To achieve combat readiness, it was required to connect the power cables and warm up the guidance equipment.
At the time of the appearance of the 75-mm gun mount M51 in its caliber, it had no equal in range, rate of fire and accuracy of firing. At the same time, the complex and expensive hardware required qualified maintenance, was quite sensitive to mechanical influences and meteorological factors, and the mobility did not meet modern requirements. In the second half of the 50s, anti-aircraft missiles began to compete sharply with anti-aircraft guns, and therefore the service of 75-mm anti-aircraft guns, coupled with a guidance radar, in the American armed forces was not long. Already in 1959, all anti-aircraft battalions armed with 75-mm guns were deactivated, but the history of the M51 installations did not end there. As usual, the weapons not needed by the American army were transferred to the Allies. In Japan and in a number of European countries, 75-mm anti-aircraft guns served at least until the early 70s.
ZSU T249 Vigilante
In 1956, tests of the ZSU T249 Vigilante began. This anti-aircraft self-propelled gun was intended to replace the 40-mm towed Bofors and ZSU M42. Armed with a 37-mm rapid-firing six-barreled cannon (3000 rounds per minute) with a rotating block of T250 barrels, the Vigilent ZSU, unlike the Daxter with its twin 40-mm Bofors with cluster loading, had a radar for detecting air targets. The base was the lengthened chassis of the M113 armored personnel carrier.
A modernized version of the ZSU T249, created to participate in the DIVAD competition
However, in the late 1950s, the American military, fascinated by anti-aircraft missiles, did not show much interest in the new anti-aircraft artillery installation, considering that the cannon-based air defense systems were outdated, and canceled further funding of the T249 in favor of the MIM-46 Mauler mobile short-range air defense system., which, however, for a number of reasons never entered service. Later, in the mid-70s, the development firm Sperry Rand tried to revive this project by installing a six-barreled anti-aircraft machine gun in an aluminum turret on the chassis of the M48 tank, converted for a 35-mm projectile (NATO 35x228 mm). But this option was not successful either, losing the competition to the ZSU M247 "Sergeant York".
The experience of hostilities gained in large-scale armed conflicts in Southeast Asia and the Middle East showed that it is too early to discard small-caliber rapid-fire anti-aircraft guns, since anti-aircraft missile systems are not always able to cover their troops from attack aircraft operating on small heights. In addition, anti-aircraft artillery installations with significant ammunition are much cheaper than air defense systems, they are less susceptible to organized interference and, if necessary, are capable of firing at ground targets.
In the mid-1960s, General Electric, in conjunction with the Rock Island Arsenal, created two models of anti-aircraft systems to meet the needs of the US Army. Both used the same 20-mm six-barreled cannon, which is a development of the M61 aircraft series.
The towed installation, designated M167, was supposed to replace the 12.7-mm ZPU M55 in the troops. This anti-aircraft gun was intended primarily for airborne and airborne units. So, in the 82nd Airborne Division, stationed at Fort Bragg in the 70s and 80s, there was an anti-aircraft battalion, consisting of a headquarters and four batteries. Each battery, in turn, consists of a headquarters and three fire platoons with 4 M167s each.
Towed anti-aircraft gun М167
The six-barreled 20-mm Vulcan cannon with a belt feed system, an electrically powered turret and a fire control system are mounted on a two-wheeled towed vehicle. According to its concept, the M167 charger corresponds to the 12.7 mm M55 towed unit. The aiming of the anti-aircraft machine gun at the target and the rotation of the barrel block during firing is also carried out by electric drives powered by batteries. A gasoline unit located in the front of the vehicle is used to charge the batteries. The M167 fire control system consists of a radio range finder located to the right of the gun, and a gyroscopic sight with a calculating device. Transportable ammunition - 500 rounds. For firing, shots with fragmentation-incendiary and armor-piercing tracer shells weighing 0.2 kg and an initial speed of 1250 m / s are used. The maximum firing range is 6 km, when firing at air targets flying at a speed of 300 m / s - 2 km. The shooting ranges have repeatedly demonstrated that the highest probability of hitting a target is achieved at a distance of up to 1500 m. The M167 can be towed by a light M715 (4x4) truck or an M998 multi-purpose off-road vehicle, as well as transported on an external sling by a helicopter. The mass in the firing position is 1570 kg, the calculation is 4 people.
The anti-aircraft gun can fire at a rate of 1000 and 3000 rds / min. The first is usually used for firing at ground targets, the second - at air targets. There is a choice of a fixed burst length: 10, 30, 60 or 100 rounds. At the moment, the towed M167 installations are not used by the American armed forces, but are still available in the armies of other states.
ZSU М163
The self-propelled version of the installation received the designation M163, this ZSU was created on the basis of the tracked armored personnel carrier M113A1. Due to the increased weight of the vehicle, additional panels are installed on the upper frontal plate and sides, increasing the buoyancy of the vehicle. Like the basic M113 armored personnel carrier, the M163 ZSU could cross water obstacles by swimming. Movement on the water was carried out by rewinding the tracks. On roads with hard surfaces, the ZSU, weighing 12.5 tons, could accelerate to 67 km / h. In terms of its firing characteristics, the self-propelled version is identical to the towed installation, but due to the significant internal volumes of the armored personnel carrier, the ammunition load has been increased several times and is 1180 shots ready for firing, and another 1100 in stock. The aluminum body armor 12-38 mm thick provides protection against bullets and shrapnel, but the gunner is protected only by an armored "hood" on the side of the rear hemisphere.
Rotation of the turret and aiming of the gun in a vertical plane in the range of angles from -5 ° to + 80 ° is carried out using high-speed electric drives. In case of their failure, there are manual guidance mechanisms. An AN / VPS-2 radar rangefinder with a range of up to 5 km and a measurement accuracy of ± 10 m is installed on the right side of the tower. When working according to target designation data received over the radio channel, the target is detected visually and captured for tracking with an optical sight, which orientates the radio rangefinder antenna to it … Target designation, as a rule, was carried out from the AN / MPQ-49 low-flying target detection radar, which was part of the Chaparel-Vulcan mixed anti-aircraft battalions.
However, at the end of the 70s, the ZSU M163 no longer fully met modern requirements. The anti-aircraft installation was criticized due to the small effective firing range and the absence of a radar for detecting air targets on the machine. In the second half of the 1980s, a significant part of the Vulcan installations - both self-propelled and towed - underwent modernization under the PIVADS program. After the modernization of the fire control system, the radio range finder was able not only to determine the range to the target, but also to automatically track it in range and angular coordinates. In addition, the gunner received a helmet-mounted sighting device, with the help of which the radar antenna was automatically oriented to the observed target for subsequent tracking. Thanks to the introduction of new armor-piercing shells with a detachable pallet into the ammunition load, the firing range at air targets increased to 2600 m.
In the United States, the M163 ZSU, along with the MIM-72 Chaparrel air defense system, were in service with mixed-strength anti-aircraft battalions. In the 70s, the Chaparel-Vulcan air defense system was an important link in the air defense system of the army corps and was the main means of fighting low-flying targets. Serial production of the M163 has been carried out by General Electric since 1967, a total of 671 ZSUs of this type were produced. They were in service with the American army anti-aircraft units until the end of the 90s. After that, the Chaparel-Vulcan system was replaced by the M1097 Evanger air defense missile system, which uses the FIM-92 Stinger missile defense system.
The short range of effective fire of 20-mm towed and self-propelled anti-aircraft guns, the impossibility of all-weather use, the absence of an armored turret and target detection radar caused the American army to announce a competition for the DIVAD (Division Air Defense) program in the mid-70s. level. The emergence of this program is due to the fact that the American military was seriously concerned about the increased capabilities of Soviet fighter-bombers and front-line bombers, capable of effectively operating at low altitudes, where anti-aircraft missiles were ineffective. In addition, Mi-24 combat helicopters armed with anti-tank missiles with a launch range exceeding the effective firing range of the Vulcan anti-aircraft guns appeared in the USSR. After the start of deliveries of M1 Abrams tanks and M2 Bradley infantry fighting vehicles to the troops, the US military faced the fact that the M163 ZSU and MIM-72 Chaparrel air defense systems simply could not keep up with the new vehicles and could not provide anti-aircraft cover. The experience of battles in the Middle East proved that modern SPAAGs can be a serious threat to combat aviation. Israeli pilots, trying to avoid being hit by anti-aircraft missiles, switched to low-altitude flights, and at the same time suffered significant losses from the ZSU-23-4 "Shilka".
The DIVAD competition was attended by five ZSU armed with anti-aircraft machine guns of 30-40 mm caliber. All of them had a target detection and tracking radar. In May 1981, the installation of the Ford Aerospace and Communications Corporation was declared the winner. ZSU received the official name "Sergeant York" (in honor of Sergeant Alvin York, hero of the First World War) and index M247. The contract for the amount of $ 5 billion provided for the supply of 618 ZSU over 5 years.
The new anti-aircraft self-propelled gun turned out to be not light, its mass in the combat position was 54.4 tons. The chassis of the M48A5 tank became the base for the M247 anti-aircraft gun. In the 80s, M48 tanks were already considered obsolete, but a significant number of M48A5 tanks were in storage bases. The use of the chassis of these tanks was supposed to reduce the production cost of the ZSU. A tower with two 40-mm anti-aircraft guns was installed in the center of the hull. On the roof of the tower there are two radar antennas: on the left is a round-shaped tracking radar antenna, and a flat target detection radar antenna on the back. The detection radar was a modified AN / APG-66 type station used on F-16A / B fighters. Both antennas could be folded to reduce the height of the ZSU on the march. The crew of the car is three people. The gunner is located on the left side of the tower, and the commander is on the right, each seat is equipped with a separate hatch. The gunner has a sight with a laser rangefinder at his disposal, the commander's seat is equipped with a panoramic observation device. The guidance system is fully automatic, without the possibility of mechanical control. The 40-mm twin cannons have an electric vertical guidance, the turret rotates 360 °. Each gun is equipped with a separate magazine, 502 rounds of ammunition.
ZSU М247
The 40mm cannons used in the M247 had significant differences from the 40mm Bofors anti-aircraft guns previously used by the US armed forces. The armament of the ZSU consisted of two Swedish-developed L70 automatic cannons, which were specially modified for the ZSU. The L70 cannon uses shots of increased power 40 × 364 mm R with an initial velocity of 0.96 kg of a projectile - 1000–1025 m / s, barrel survivability of 4000 shots. When creating the L70, priority was given not to rate of fire, but to high accuracy of fire in short bursts. The technical rate of fire of one gun is 240 rds / min. The range of destruction of air targets is 4000 m.
Despite the victory in the competition, the adoption of the ZSU M247 into service caused a flurry of criticism. It was indicated that the machine needs fine-tuning, the radio-electronic complex is unreliable, and the combat effectiveness is questionable. An indirect recognition of this can be considered the intention of the developer to install on the tower as an additional weapon of the FIM-92 "Stinger" missile defense system. In addition, the outdated M48A5 chassis could not keep up with the new tanks and infantry fighting vehicles. All this became the reason for the curtailment of production of the ZSU М247 "Sergeant York" in August 1985. Until that moment, American industry had managed to build 50 cars. Due to numerous shortcomings, the army abandoned them, and most of the M247 was used as targets at air ranges. At the moment, the museums have preserved four copies of the ZSU.
After the epic with the DIVAD program, the American army no longer attempted to adopt anti-aircraft artillery installations. Moreover, anti-aircraft missile units underwent significant reductions in the 90s. The American armed forces abandoned the Hawk 21 air defense system, in the modernization of which considerable funds were invested. As already mentioned, the Chaparrel-Vulcan mixed anti-aircraft battalions were replaced by batteries of the M1097 Avenger air defense missile system on the M988 Hammer chassis, which, of course, cannot be considered a full-fledged replacement, since the Hummers are seriously inferior to tracked vehicles in cross-country ability. However, recently the US Army has lost interest in anti-aircraft systems. SAM "Patriot" PAC-3 are not on alert in the United States. In Germany, the American contingent has only four Patriot batteries, which also do not have constant readiness. Anti-aircraft systems are deployed only in potentially missile-prone regions to protect American bases from North Korean, Iranian and Syrian ballistic missiles. The provision of air defense against enemy strike aircraft in the theater of operations is entrusted mainly to the US Air Force fighters.
