ប្រភេទប្រព័ន្ធការពារអាកាស

Types of Air Defense Systems

This section is dedicated to introducing air defense systems that have attributes

pertinent to a solution required by the problem statement.

ក្នុងផ្នែកនេះនិយាយអំពីប្រព័ន្ធការពារអាកាសដែលប្រើសម្រាប់ដោះស្រាយបញ្ហារំលោភផ្ទៃអាកាស

1. Antiaircraft Artillery

Antiaircraft artillery (AAA) systems fire gun-launched unguided, ballistic flight path​ projectiles at air targets. They are usually found in the role of terminal defense, most effectively for engaging targets within four kilometers. The only controls  over a gun-launched projectile flight path are the two gun aiming angles: azimuth and  elevation.

ប្រព័ន្ធកាំភ្លើងធំការពារអាកាស (AAA) គឺជាបណ្តុំឬប្រជុំកាណុងកាំភ្លើងធំគ្មានប្រព័ន្ធនាំផ្លូវ ជាគ្រាប់កាំភ្លើងធំហោះវិលលើផ្ទៃអាកាសនិងមានបំផ្ទុះជាអំបែង ទៅលើគោលដៅ។ ជាទូទៅគេប្រើសម្រាប់ការពារផ្ទៃអាកាសពេលដែលគោលដៅហោះដល់នាទីចុងក្រោយ ជាប្រព័ន្ធអាវុធដែលមានប្រសិទ្ធិភាពបាញ់ចនោះ ៤គីឡូម៉ែត្រ។ ប្រព័ន្ធគ្រប់គ្រងការបាញ់មានតែ ០១គត់គឺប្រើវិធី វាស់មុំ៖ វាស់មុំរយៈកំពស់/មុំរេទិស (azimuth) និងវាស់មុំរយៈចម្ងាយ/មុំឡើងចុះ (elevation angle)

Guns are considered open loop systems; gun aiming angles are calculated for​​ a predicted target flight path (i.e. predicted future position) such that the  projectile will hit the target without any further corrections. Most AAA gun systems employ power-driven mounts to elevate the gun to the commanded azimuth and elevation angles with the smallest possible error. The difference between the commanded angle and the actual response angle is the position error. Employing a AAA system successfully requires an accurate error analysis. In addition to target tracking and flight path prediction, Macfadzean lists the following eight major contributions to  miss distance of AAA fire.

កាំភ្លើងធំការពារអាកាស​ប្រើ ប្រព័ន្ធបើកបាញ់ ពោលគឺកាំភ្លើងតម្រង់តាមមុំដោយគណនាផ្លូវហោះរួច ព្យាករណ៍អំពីផ្លូវហោះ (ឧ. ព្យាករណ៍កម្រិតកំពស់យន្តហោះឡើងឬចុះឬ ហោះស្មើរ?) បែបនេះគឺប្រព័ន្ធបើកបាញ់ និងហោះបំបុកគោលដៅដោយគ្មានការ កែប្រែមុំឬទិសបាញ់។ កាំភ្លើងធំការពារអាកាសភាគច្រើនភ្ជាប់មុំឡើងចុះ ជាមួយមុំរេទិសឲ្យមានកម្រិតលំអៀងតូចបំផុត។ កម្រិតខុសគ្នារវាង មុំបញ្ជាបាញ់ និងមុំជាក់ស្តែង ហៅថា កម្រិតលំអៀង។ ការប្រើប្រាស់ប្រព័ន្ធកាំភ្លើងធំការពារអាកាសមានប្រសិទ្ធិភាពខ្ពស់ អាស្រ័យលើការវិភាគអំពី កម្រិតលំអៀង។ លើសពីនេះទៀត ដើម្បីជាការច្បាមគោលដៅ និង ការព្យាករណ៍ទុកជាមុនអំពីផ្លូវហោះ លោក Macfazean បានកត់ត្រាទុកចំណុចចំនួន ០៨ជាសំខាន់ដែលទាក់ទងនឹងការគណនាខុសរយៈចម្ងាយ នៃ ប្រព័ន្ធកាំភ្លើងធំការពារអាកាសដូចខាងក្រោម៖

• Initial velocity ល្បឿនសំទុះជាមធ្យម (ល្បឿងដើម១០ម/វិនាទី, ចម្ងាយរត់១២វិនាទី,​ល្បឿនចុងក្រោយ ២០០ម/វិនាទី ដូច្នេះល្បឿនមធ្យម ២០០វិនាទី-១២០​វិនាទី= ៨០ម/ វិនាទី)

• Air density ដង់ស៊ីតេខ្យល់ ដង់ស៊ីតេសំណើម/ម៉ែត្រគូប

• Air temperature សីតុណ្ហភាពបរិយាកាស (អង្សារសេ)

• Range wind ល្បឿនខ្យល់

• Projectile weight ទម្ងន់ក្បាលគ្រាប់

• Gun elevation angle មុំកាំភ្លើងការពារអាកាស

• Crosswind គណនាទិសខ្យល់ឆ្លងកាត់

• Gun azimuth គណនាមុំរេទិស

Both the gun itself and the ammunition fired from it are designed to achieve consistent, predictable firing velocities (the velocity at which the projectile leaves the muzzle) between successive shots. In reality, the initial velocity varies between each gun and each projectile round. One example that Macfadzean points out is that the gun barrel wears more with each shot fired, which increases the barrel diameter and allows some of the gases to escape around the projectile body, thereby reducing the initial firing velocity. Even variations in the temperature of the gun powder can have measurable effects on firing velocity. Manufacturing tolerances drive the variation of the projectile rounds themselves. Macfadzean gives a basic feel for the magnitude of the possible variations in initial velocity. Ammunition from the same manufacturing lot may have small variation from round to round, about 2 to 3 m/s 1σ error (assuming the error is normally distributed around the desired value). Poorly manufactured or mixed lots may have greater than 5 m/s 1σ error.

Differentials in air density and temperature only add a significant contribution to position error when dealing with great variations in altitude over long distances. Range wind, which is the velocity component of wind parallel to the direction that the projectile travels, directly modifies the projectile airspeed and the drag force component in the down range direction (denoted as the X direction). Crosswind is the airspeed component perpendicular to the range axis (denoted as the Y direction). The variation of weight of the projectile results in a change in velocity along the entire trajectory. Macfadzean states that variations from 0.5 to 1 percent are common, and controlled by the manufacturing process and quality control. Gun elevation controls the vertical plane trajectory, and therefore elevation angle variations induce vertical errors that are in the velocity vector normal plane. The azimuth angle controls the motion in the horizontal X-Y plane, and the effect of error produces a lateral effect. Error analysis of AAA trajectories may be based on baseline standard conditions,

defined as:

Projectile specification initial velocity (i.e. fixed exit muzzle velocity)

• Standard atmosphere conditions

• Published drag coefficient versus Mach number

• No wind

• Projectile specification weight

• No aiming error (azimuth or elevation)

2/ Surface-to-Air Missiles

Surface-to-Air Missiles (SAM) are missiles that are launched from land (or sea) based platforms. The missiles themselves are self-propelled, and are usually large enough to carry a warhead for long ranges using some type of onboard guidance system. They use movable control surfaces that are deflected by guidance system commands to direct flight, and on board sensors may be used to track the target. However, the complexity of SAM’s usually limits their use against large targets, such as a piloted aircraft and cruise missiles, and therefore will not be elaborated on further. The SAM topic is simply included here to show how surface to air guided weapons are generally used.

3.  Integrated Air Defense System

A “layered” air defense is a combination of the different types of air defense where one or more point or area defense weapons are assigned overlapping areas. The linking together of the various air defense target sensors, weapon firing platforms, and command centers is known as an Integrated Air Defense System (IADS). An IADS consists of 1) surveillance sensors (surface-, air-, and/or space-based); 2) various weapon system installations (including target detection, tracking, and guidance sensors for fire control); 3) filter centers used for data fusion; 4) decision making command centers, or command, control, communication, and information (C3I) centers; and 5) communication links between the sensors, weapon systems, and command

centers.