Guided Missiles Working

[Manticore]

Guided Missiles Working

A guided missile is an unmanned explosive-carrying vehicle that moves above the earth's surface in a flight path controlled by an external or internal source. There are many kinds of guided missiles, but all have the same ultimate function: destroy enemy "targets", i.e., personnel, tanks, vehicles, airplanes, ships, and weapons, including attacking missiles.

Some missiles attack targets at long distances - thousands of miles - like the ICBM (Intercontinental Ballistic Missile). These are "strategic" missiles

Other missiles are used offensively or defensively over shorter distances - from a few to a few hundred miles. These are "tactical" missiles.

Missiles can be launched from ships, planes and the ground at targets located on ships, planes and the ground; hence, the classifications as ground to ground Tow, ship to ground Cruise, ground-to-air Stinger, air-to-ground Amraam, Apache, ship-to-air Standard Missile, and so forth.

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http://www.defence.pk/forums/wmd-missiles/120722-anti-tank-missiles.html

 

[Manticore]

Missile Parts and Their Functions.

A tactical missile is from 5 to 20 feet long, 6 inches to 1 foot in diameter, and weighs from 200 to 2,000 pounds. The size is determined by the expected distance to the target (longer distances require more fuel capacity) and the type of target (bigger, heavier targets required more explosive). ' Most of the missile body is made of a titanium alloy, which provides high strength and low weight. Inside the missile are hundreds of electronic, digital and mechanical subsystems that perform thousands of operations to guide the missile from its launcher to its target. A tactical missile travels at about the speed of sound (700 mph), but some travel almost twice that speed. Each missile costs tens to hundreds of thousands of dollars. Its flight time is measured in seconds.

A missile can be divided functionally into 8 sections: radome, guidance, warhead, autopilot, dorsal fins, rocket motor, steering control and control surfaces. These missile sections are described below.


1. Radome. A housing made of ceramic material similar to the household "Corningware" and located at the front end ("nose") of the missile. Here are some radomes on the production line . The radome is non-metallic to act as an electromagnetic (EM) "window" for radar or heat-seeking EM devices located inside the missile. Radar (Radio Ranging and Detection), transmits EM pulses that bounce off the target and return to the radar set to provide target location, direction and speed.

2. Guidance. A system that receives radio information from its launch controller (a computer, not a human), directing it to launch the missile and calculate its most efficient path to the target. The Guidance system also transmits all missile functions back to its launch controller for continuous monitoring of missile subsystem performance.

3. Warhead. A system containing missile internal "homing" radar and an explosive surrounded by thousands of serrated iron pieces or other destroying material, depending on the nature of the anticipated target. As the missile approaches ("homes in on") the target, its internal radar electronically "sees" and locks onto the target to guide the missile towards it. Not all missiles have this "homing" radar. If not, its launch control must continuously direct it to the target.

4. Autopilot. A system that provides missile location, direction, velocity and "attitude" (up, down sideways, etc.) and the capacity to change its motion via the Control Surfaces (see below). The Autopilot contains an antenna to receive and transmit information to its home controller. It also contains a battery that supplies electrical power to the missile electronic and microprocessor components. &bnsp; Transmissions to and from the missile must be encoded and decoded to prevent electronic spying by other countries' surveillance radars.

5. Dorsal Fins. The fins, along with the missile body, provide surfaces against which air exerts pressure. These dorsal surfaces are used by the Control Surfaces (see below) to change the direction and attitude of the missile.

6. Rocket Motor. A mixture of solid chemical fuels. When ignited, the chemicals propel the missile from its launcher into space.

7. Steering Control. A system that electrically changes the Control Surfaces (see below) that change the missile motion. It reacts to information sent to it by the Autopilot (see above).

8. Control Surfaces. These are four "fins" that act against air resistance to change the direction of the missile.

In summary, a guided missile is a combination of electrical, digital and mechanical parts segregated into sections. Each section has specific functions that must operate accurately and safely; otherwise, the missile mission is electronically aborted and the missile is destroyed. Internal controls monitor each function to assure proper coordination among parts. This information is radioed to the launch controller, so that it knows at all times how well each part of the missile is performing to achieve the missile's ultimate goal of destroying the target.

 

[Manticore]

Missile Launch & Target-destruction Process.

The missile launching and target destruction process can be divided into seven stages: long-range and short-range surveillance, target identification, target tracking, missile pre-launch, launch, midcourse guidance, homing, and intercept. Each of these phases is described below:

1. Surveillance. A systematic search by the launcher (ship, plane, or ground station) radars and more radars for targets in the hemisphere surrounding it. Another target tracking diagram that starts from search at the lower right and ends with intercept at the upper left.

Note: "Illumination" means that the missile's own internal radar tracks the target. Not all missiles have their own tracking radar.

2. Identification: "Friend or foe?". All commercial and military airplanes and some weapons and personnel have "transponders", which are receiver- transmitters that receive radio signals on one frequency and return a specific identification (ID) signal on another frequency. When the target code matches a "friendly" code in the launcher electronic library, no launcher action is taken. However, if the ID matches a "foe" code, or if there is no response, the missile launcher assumes a "foe" and prepares to destroy the target. Tragedies can occur when a friendly transponder is inoperable.

3. Pre-launch. The Weapons Officer in charge of missile launch (in airplanes, this would be the pilot) selects a particular missile to attack the target with a push of a button. The selected missile then automatically tests ("checks") hundreds of its subsystems within milliseconds to assure their satisfactory operation. Also, the communications link from the launcher to the missile and the missile to the launcher are automatically tested for satisfactory functioning. If a subsystem or communications link fails after a few attempts, the missile declares itself inoperable (a "dud") and the Weapons Officer selects another missile. On a ship, the missiles are stored in launch boxes below deck. This image shows the white launch canister covers behind the gun on the front deck and behind the superstructure on the rear deck of the ship.

 

[Manticore]

4. Launch. After a satisfactory self-test, the missile ignites its rocket motor, which provides the force to propel the missile away from its platform.

Also, the missile battery is activated soon after launch to provide electrical power to the missile components. Total elapsed time from the push of the button by the Weapons Officer to rocket ignition is only a few seconds, depending on the size and complexity of the missile. The missile rocket motor pushes the missile upwards and outwards from the missile container.

Note: Once the missile is placed on its launch vehicle and electrically connected to its control center, it is ready to be fired by the Weapons Officer. (In an airplane, the Weapons Officer is the pilot.) This is true for encanistered and non-canistered missiles. There is no missile storage from which the missiles have to be physically moved to the ready position. They are always ready to launch from their initial position and need merely be activated by the Weapons Officer.

5. Tracking. The launcher "tracking" radar continuously monitors the target, while computers continuously calculate target location, direction and speed. Human judgment is involved in identification too.

6. Midcourse. During missile flight, target location, direction, and speed are continuously calculated by the launcher radar. This information is transmitted from the ship (or plane, or truck) to the missile via radar, which adjusts its course to intercept the target. Missile functioning is continuously transmitted to the launcher via radio.

7. Homing. When the missile approaches target vicinity, it activates its own radar and searches for the target itself, so that launcher radar no longer is required. The image below is what a target missile (one attacking you) looks like to the attacking missile (one you use to counterattack the attacker):

Note: Not all missiles have their own tracking radar. If not, then the controller at the launching ship, plane or truck must provide continuous tracking of the missile to its target.

8. Intercept (target destruction). The missile IR (Infra-Red) "seeker" determines when the target is at the optimum distance for maximum explosive effect, whereupon it sends a signal to the warhead to detonate. The explosive scatters serrated iron fragments or other destroying material in all directions. Some of these fragments are expected to impair target functioning. When that occurs, the target is a "kill".

http://www.mikalac.com/mis/missile.html

 

[Manticore]

Active radar homing is a missile guidance method in which a guided missile contains a radar transceiver and the electronics necessary for it to find and track its target autonomously.

There are two major advantages to active radar homing:

* Because the missile is tracking the target, and the missile is typically going to be much closer to the target than the launching platform during the terminal phase, the tracking can be much more accurate and also have better resistance to ECM. Active radar homing missiles have some of the best kill probabilities, along with missiles employing track-via-missile guidance.
* Because the missile is totally autonomous during the terminal phase, the launch platform does not need to have its radar enabled at all during this phase, and in the case of a mobile launching platform like an aircraft, can actually exit the scene or undertake other actions while the missile homes in on its target. This is often referred to as fire-and-forget capability and is a great advantage that modern air-to-air missiles have over their predecessors.

There are three major disadvantages to active radar homing:

* Since the missile has to contain an entire radar transceiver and electronics, it was until recently difficult to fit all of this into a missile without unacceptably increasing its size and weight. Even with today's miniaturisation making this possible, it is quite expensive to make these missiles since the sophisticated electronics within the missile are inevitably destroyed upon impact.
* There is very little chance that targets with capable modern radar warning receiver would be unaware that an incoming missile is approaching them. This gives them sufficient time to take evasive action and deploy countermeasures. However, given the accuracy of this homing method, unless the target is especially maneuverable or the missile is not, there may not be much they can do to avoid being intercepted.
* ARH-type missiles lose their effectiveness the closer the target is. Therefore, these types of missiles with this mounted equipment are only effective in long range confrontations.


Passive radiation homing
Many missiles employing this type of guidance have an extra trick up their sleeves; If the target does attempt to jam them using some kind of ECM, they can in effect turn into an anti-radiation missile and home in on the target's radiation passively. This makes such missiles practically immune to ECM, in addition to removing the second disadvantage. Since they already have the radar receiver on board, this should not be a difficult feature to add (at least, it requires extra processing logic but little extra hardware).

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Active radar homing is rarely employed as the only guidance method of a missile. It is most often used during the terminal phase of the engagement, mainly because since the radar transceiver has to be small enough to fit inside a missile and has to be powered from batteries, therefore having a relatively low ERP, its range is limited.[1] To overcome this, most such missiles use a combination of command guidance with an inertial navigation system (INS) in order to fly from the launch point until the target is close enough to be detected and tracked by the missile. The missile therefore requires guidance updates via a datalink from the launching platform up until this point, in case the target is maneuvering, otherwise the missile may get to the projected interception point and find that the target is not there. Sometimes the launching platform (especially if it is an aircraft) may be in danger while continuing to guide the missile in this way until it 'goes active'; In this case it may turn around and leave it to luck that the target ends up in the projected "acquisition basket" when the missile goes active. It is possible for a system other than the launching platform to provide guidance to the missile before it switches its radar on; This may be other, similar fighter aircraft or perhaps an AWACS.

 

[Manticore]

Semi-active radar homing, or SARH, is a common type of missile guidance system, perhaps the most common type for longer range air-to-air and surface-to-air missile systems. The name refers to the fact that the missile itself is only a passive detector of a radar signal – provided by an external (“offboard&#8221 source — as it reflects off the target.

The basic concept of SARH is that since almost all detection and tracking systems consist of a radar system, duplicating this hardware on the missile itself is redundant. In addition, the resolution of a radar is strongly related to the physical size of the antenna, and in the small nose cone of a missile there isn't enough room to provide the sort of accuracy needed for guidance. Instead the larger radar dish on the ground or launch aircraft will provide the needed signal and tracking logic, and the missile simply has to listen to the signal reflected from the target and point itself in the right direction. Additionally, the missile will listen rearward to the launch platform's transmitted signal as a reference, enabling it to avoid some kinds of radar jamming distractions offered by the target.

Contrast this with beam riding systems, in which the radar is pointed at the target and the missile keeps itself centered in the beam by listening to the signal at the rear of the missile body. In the SARH system the missile listens for the reflected signal at the nose, and is still responsible for providing some sort of “lead” guidance. The disadvantages are twofold: One is that a radar signal is “fan shaped”, growing larger, and therefore less accurate, with distance. This means that the beam riding system is not accurate at long ranges, while SARH is largely independent of range and grows more accurate as it approaches the target, or the source of the reflected signal it listens for. Another requirement is that a beam riding system must accurately track the target at high speeds, typically requiring one radar for tracking and another “tighter” beam for guidance. The SARH system needs only one radar set to a wider pattern.


Continuous-wave radar
Modern SARH systems use continuous-wave (CW) radar for guidance. Even though most modern fighter radars are pulse Doppler sets, most have a CW function to guide radar missiles. A few Soviet aircraft, such as some versions of the MiG-23 and MiG-27, used an auxiliary guidance pod or aerial to provide a CW signal. The Vympel R-33 AA missile for MiG-31 interceptor uses SARH as the main type of guidance (with supplement of inertial guidance on initial stage).

SARH missiles require tracking radar to acquire the target, and a more narrowly focused illuminator radar to "light up" the target in order for the missile to lock on to the Radar return reflected off target.[1] The target must remain illuminated for the entire duration of the missile's flight. This could leave the launch aircraft vulnerable to counter attack, as well as giving the target's electronic warning systems time to detect the attack and engage countermeasures. Because most SARH missiles require guidance during their entire flight, older radars are limited to one target per radar emitter at a time.

Electronic counter-countermeasure (ECCM)
Recent-generation SARH weapons have superior electronic counter-countermeasure (ECCM) capability, but the system still has fundamental limitations. Some newer missiles, such as the SM-2, incorporate terminal semi-active radar homing (TSARH). TSARH missiles use inertial guidance for most of their flight, only activating their SARH system for the final attack. This can keep the target from realising it is under attack until shortly before the missile strikes. Since the missile only requires guidance during the terminal phase, each radar emitter can be used to engage more targets. Some of these weapons, like the SM-2, allow the firing platform to update the missile with mid-course updates via datalink.

 

[Manticore]

Infrared homing refers to a passive missile guidance system which uses the emission from a target of electromagnetic radiation in the infrared part of the spectrum to track and follow it. Missiles which use infrared seeking are often referred to as "heat-seekers", since infrared (IR) is just below the visible spectrum of light in frequency and is radiated strongly by hot bodies. Many objects such as people, vehicle engines and aircraft generate and retain heat, and as such, are especially visible in the infra-red wavelengths of light compared to objects in the background.

Early infrared seekers were most effective in detecting infrared radiation with shorter wavelengths, such as the 4.2 micrometre emissions of the carbon dioxide efflux of a jet engine. Such seekers, which are most sensitive to the 3 to 5 micrometre range, are now called single-color seekers. Modern infrared seekers also operate in the 8 to 13 micrometre wavelength range, which is absorbed least by the atmosphere. Such seekers are called two-color systems. Two-color seekers are harder to defeat with countermeasures such as flares and jammers.

Modern all-aspect missiles like the AIM-9M Sidewinder and FIM-92 Stinger use compressed gas or liquid nitrogen to cool their sensors in order to lock onto the target at longer ranges and all aspects. (Some such as the AIM-9J and early-model R-60 used a peltier thermoelectric cooler).



Tracking
Most infrared guided missiles have their seekers mounted on a gimbal. This allows the sensor to be pointed at the target when the missile is not. This is important for two main reasons. One is that before and during launch, the missile cannot always be pointed at the target. Rather, the pilot or operator points the seeker at the target using radar, a helmet-mounted sight, an optical sight or possibly by pointing the nose of the aircraft or missile launcher directly at the target. Once the seeker sees and recognises the target, it indicates this to the operator who then typically "uncages" the seeker (which is then allowed to follow the target). After this point the seeker remains locked on the target, even if the aircraft or launching platform moves. When the weapon is launched, it may not be able to control the direction it points until the motor fires and it reaches a high enough speed for its fins to control its direction of travel. Until then, the gimballed seeker needs to be able to track the target independently.

Finally, even while it is under positive control and on its way to intercept the target, it probably will not be pointing directly at it; unless the target is moving directly toward or away from the launching platform, the shortest path to intercept the target will not be the path taken while pointing straight at it, since it is moving laterally with respect to the missile's view. The original heat-seeking missiles would simply point towards the target and chase it; this was inefficient. Newer missiles are smarter and use the gimballed seeker head combined with what is known as "proportional guidance" in order to avoid oscillation and to fly an efficient intercept path.

 

[Manticore]

Drawbacks of IRCM - Infrared countermeasure

One of the drawbacks of standard IRCM systems is that they broadcast a bright source of infrared. If the modulation of the signal is not effective against a particular seeker system, the IRCM will enhance the ability of the missile to track the aircraft. The aircrews typically brief about potential threats and choose an IRCM modulation that will be effective against likely threats.


Flares create infrared targets with a much stronger signature than the aircraft's engines. The flares provide false targets that cause the missile to make incorrect steering decisions. The missile will rapidly break off a target lock-on.

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DIRCM, or Directional Infrared Countermeasures,
avoid this potential drawback by mounting the energy source on a movable turret (much like a FLIR turret). They only operate when cued by a missile warning system of a missile launch, and use the missile plume to accurately aim at the missile seeker. The modulated signal can then be directed at the seeker, and the modulation scheme can be cycled to try to defeat a variety of seekers. Countermeasure success depend on threat's tracking techniques and requires threats' analysis capabilities.[2] Defeating advanced tracking systems requires a higher level of DIRCM power. Issues of Laser Safety are also taken into account.

Israel has announced a program to develop a system called Multi Spectral Infrared Countermeasure (MUSIC) that will similarly use active lasers instead of flares to protect civilian aircraft against MANPADs.[3] The US Army is deploying a similar system to protect its helicopters.[4]

Department of the Navy Large Aircraft Countermeasures (DoN LAIRCM) provides infrared threat protection for U.S. Marine Corps CH-53E, CH-46E and CH-53D platforms.[5]
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Common Infrared Countermeasures
will be a laser based IR countermeasures solution against current and future IR threat systems for the US Army rotorcraft & fixed wing platforms and US Navy and US Air Force rotorcraft platforms. Currently, systems by ITT Defense and Information Solutions, Raytheon and Lockheed Martin are under consideration

 

[Manticore]

Beam-riding, also known as beam guidance, is a technique of directing a missile to its target by means of radar or a laser beam. It is one of the simplest forms of guidance using radar or lasers.

The main use of this kind of system is to destroy airplanes or tanks. First, an aiming station (possibly mounted in a vehicle) in the launching area directs a narrow radar or laser beam at the enemy aircraft or tank. Then, the missile is launched and at some point after launch is “gathered” by the radar or laser beam when it flies into it. From this stage onwards, the missile attempts to keep itself inside the beam, while the aiming station keeps the beam pointing at the target. The missile, controlled by a computer inside it, “rides” the beam to the target.

The radar beam rider method has been largely abandoned as a form of guidance for surface-to-air missile systems since it is easily detectable and inaccurate at long ranges. For example, though earlier versions of the RIM-2 Terrier missile that were introduced in the 1950s were "beam riders", later variants employed semi-active radar homing to improve their effectiveness against high-performance and low-flying targets.[1] On the other hand laser beam riders are in use and are difficult to detect by a warning receiver.[2]

 

[Manticore]

additional read..

Semi-active Radar Guided AAMs
Conical Scan Semi-active Seekers
Monopulse Semiactive Seekers
Active Radar Guided AAMs
ACTIVE AND SEMIACTIVE RADAR MISSILE GUIDANCE

PRINCIPLES OF
GUIDED MISSILES
AND
NUCLEAR WEAPONS
Principles of Guided Missiles and Nuclear Weapons

 

[Manticore]

LASER-GUIDED MISSILES

BOLT-117
Laser-guided missiles were first developed during the Vietnam War. The Army began to research laser guidance systems in 1962. The first laser-guided bomb, the BOLT-117, was developed by the Air Force in 1967; however, it was not used in combat until 1968. The BOLT-117 worked using two planes. One plane was used to keep a laser illuminating the intended target, while the other’s job was to drop the missile by following the reflected laser bean and directing the missile by sending signals to its control fins. For high efficiency, there was a very narrow region within which the pilot could release the missile. Laser-guided missiles of this time were generally made of standard iron and were simply dumb bombs with a laser guidance and control system attached. They commonly had a range of three to four kilometers.

BOLT-117.

 

[Manticore]

MODERN LASER-GUIDED MISSILES
Modern laser-guided missiles can be self-detonated, thus requiring only a single aircraft, and their range has increased significantly. The laser-guided missiles use a laser of a specific frequency bandwidth to locate the target. The pilot must line up the crosshairs and lock successfully onto target. This laser creates a heat signature on the target. The weapon must be released during a certain window of opportunity. After it is launched, the missile uses its onboard instrumentation to find the heat signature. The target is acquired when the missile locates the heat signature. The missile is able to secure the target even if the target is moving.

Laser-guided missiles work by following the reflected light of a laser beam, which can either be shone on the target by the aircraft itself, by another airplane, or by ground troops with a handheld laser designator. Therefore, once the missile has been launched its own instrumentation is able to remain on target, rather than older laser-guided missiles that required the pilot to continually sight the target with the laser.

Laser-guided missiles are used for those targets that need pinpoint accuracy. A disadvantage of laser-guided missiles is that their guidance systems do not work well in all weather conditions. If it is cloudy, the water droplets in the air cause the laser to diffract. Because the laser only operates within a certain bandwidth, the laser can be completely diffracted if it is too cloudy and the missile will not be able to locate its target. Rain has a similar effect on the laser because each raindrop serves to diffract the laser beam, once again deterring the missile from its target.


OTHER GUIDED MISSILES

The precise work required by pilots sparked the development of other forms of guided missiles that do not require the pilot’s guidance. Additionally, the weather limitations mentioned previously spawned a new breed of missiles that allow for accurate deployment in adverse weather conditions. Such missiles are guided using Global Positioning Satellite (GPS) technology. To guide such missiles, three coordinates are necessary: the latitude, longitude, and elevation. Developed by NASA in 2000, C-band and X-band interferometric synthetic aperture radars (ISFARs) are used to collect the topographic data required to employ this technology. NASA used these ISFARs to create the most complete and high resolution topography of the Earth available today within ten days, with guided weapons being its primary application. These missiles have a longer range than typical laser-guided missiles.


Joint Direct Attack Munition (JDAM) missiles are based on a relatively new technology. JDAM is attached to the tail of the missile to change it from a conventional weapon to a GPS guided smart bomb. Accurate guidance is accomplished through a new tail section that contains a GPS aided Inertial Navigation System (INS) which guides the bomb from the release point to the intended target by the use of three coordinates. The INS with GPS updates allow control fins to correct trajectory until the moment of impact. These coordinates are sent to the bomb by way of an interface from the delivery aircraft. The missiles can be released up to fifteen miles from the target. JDAM also works in the adverse weather conditions that create difficulties in firing laser-guided missiles.

http://www.nd.edu/~techrev/Archive/Spring2002/a9.html


---------- Post added at 01:39 AM ---------- Previous post was at 01:38 AM ----------

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[khurasaan1]

Good work bro. Good work ..Looks like u wanna make us master in Missile tech too after aircraft tech....

 

[Manticore]

its better to have some idea before jumping into discussions , so i'm gradually going through some basic terminologies first and thought to share them aswell!

 

[F-16_Falcon]

thank you bro.