FGM-148 Javelin - Design
Javelin is a fire-and-forget missile with lock-on before launch and automatic self-guidance. The system takes a top-attack flight profile against armored vehicles (attacking the top armor, which is generally thinner), but can also take a direct-attack mode for use against buildings, targets inside the minimum top-attack engagement range, and targets under obstructions. The missile also has the ability to engage helicopters in the direct attack mode. It can reach a peak altitude of 150 m (500 ft) in top-attack mode and 60 m (190 ft) in direct-fire mode. It is equipped with an imaging infrared seeker. The tandem warhead is fitted with two shaped charges: a precursor warhead to detonate any explosive reactive armor and a primary warhead to penetrate base armor.
The missile is ejected from the launcher so that it reaches a safe distance from the operator before the main rocket motors ignite – a "soft launch arrangement". This makes it harder to identify the launcher; however, back-blast from the launch tube still poses a hazard to nearby personnel. Thanks to this "fire-and-forget" system, the firing team may change their position as soon as the missile has been launched, or prepare to fire on their next target while the first missile is still in the air. The missile system is most often carried by a two-person team consisting of a gunner and an ammunition bearer, although it can be fired with just one person if necessary. While the gunner aims and fires the missile, the ammo bearer scans for prospective targets, watches for threats, such as enemy vehicles and troops, and ensures that personnel and obstacles are clear of the missile's back blast.
The Javelin consists of a missile in a disposable launch tube and a reusable Command Launch Unit (CLU) with a trigger mechanism and the integrated day/night sighting device for surveillance, and target acquisition and built-in test capabilities and associated electronics. The M98A1 CLU attaches to the LTA, the only reusable portion of the Javelin system. It consists of a main housing, shock absorbers, handgrips, battery compartment, daysight, NVS, eyepiece, test connector, and round interface connector. The CLU, powered by a disposable battery, provides the capability for battlefield surveillance, target acquisition, missile launch, and damage assessment.
The gunner carries a reusable Command Launch Unit (in addition to the Launch Tube Assembly) more commonly referred to as a CLU (pronounced "clue") and is the targeting component of the two-part system. The CLU has three views which are used to find, target, and fire the missile and may also be used separately from the missile as a portable thermal sight. Infantry are no longer required to stay in constant contact with armored personnel carriers and tanks with thermal sights. This makes infantry personnel more flexible and able to perceive threats they would not otherwise be able to detect. In 2006, a contract was awarded to Toyon Research Corporation to begin development of an upgrade to the CLU enabling the transmission of target image and GPS location data to other units.
The first view is a 4× magnification day view. It is mainly used to scan areas for light during daylight operation, because light is not visible in the thermal views. It is also used to scan following sunrise and sunset, when the thermal image is hard to focus due to the natural rapid heating and/or cooling of the Earth.
The second view is the 4× magnification night view, and shows the gunner a thermal representation of the area viewed. This is also the primary view used due to its ability to detect infrared radiation and find both troops and vehicles otherwise too well hidden to detect. The screen shows a "green scale" view which can be adjusted in both contrast and brightness. The inside of the CLU is cooled by a small refrigeration unit attached to the sight. This greatly increases the sensitivity of the thermal imaging capability since the temperature inside the sight is much lower than that of the objects it detects. Due to the sensitivity this causes, the gunner is able to "focus" the CLU to show a detailed image of the area being viewed by showing temperature differences of only a few degrees. The gunner operates this view with the use of two hand stations similar to the control stick found in modern cockpits. It is from this view that the gunner focuses the image and determines the area that gives the best heat signature on which to lock the missile.
The Javelin night vision sight (NVS) is a passive I2R system. The NVS enables observation of things that are not normally visible to the human eye. It receives and measures IR light emitted by the environment. The NVS converts the IR light into an image for the gunner. The NVS is the primary sight used by the gunners during the day or night. This imaging infrared (I2R) system allows the gunner to see during limited visibility conditions, including darkness, obscuration, smoke, fog, inclement weather, and IR clutter. The NVS consists of the NVS lens, a detector dewar cooler (DDC), a CLU display, and an eyepiece that provides the gunner with both 4x wide field-of-view (WFOV) and 9x narrow field-of-view (NFOV) magnification for scanning and target detection.
The IR image also allows the gunner to identify enemy armor targets, his first priority to engage and destroy. Javelin gunners must identify battlefield combatants at night based on the images seen in the NVS. The gunners must distinguish friends from foes to preclude fratricide. The Night Vision Laboratory has developed materials to train Javelin gunners to identify friends and targets based on their IR images.
The third field of view is a 12× thermal sight used to better identify the target vehicle. Once the CLU has been focused in WFOV, the gunner may switch to NFOV for target recognition before activating Seeker FOV. Once the best target area is chosen, the gunner presses one of the two triggers and is automatically switched to the fourth view; the Seeker FOV, which is a 9x magnification thermal view. This process is similar to the automatic zoom feature on most modern cameras. This view is also available along with the previously mentioned views, all of which may be accessed with press of a button. However, it is not as popular as a high magnification view takes longer to scan a wide area. This view allows the gunner to further aim the missile and set the guidance system housed inside the actual missile. It is when in this view that information is passed from the CLU, through the connection electronics of the Launch Tube Assembly, and into the missile's guidance system. If the gunner feels uncomfortable with firing the missile, he can still cycle back to the other views without having to fire the missile. When the gunner is comfortable with the target picture, he pulls the second trigger and establishes a "lock”. The missile launches after a short delay.
Located on the bottom of the main housing, the battery compartment houses the nonrechargeable BA-5590/U or the rechargeable BB390A battery (for training use only). The same battery is used in the single-channel ground and airborne radio system (SINCGARS) and can be interchanged with the CLU. A connector on the battery compartment joins to a corresponding connector on the battery. A wire bail holds the detachable battery compartment cover in place. The Battery coolant unit [BCU] consists of a battery section and a compressed-gas coolant section. Before missile launch, the battery section powers the missile electronics, and the coolant section cools the missile seeker to its operating temperature. The BCU is a single-use unit with 4 minutes of operating time; it is not rechargeable. Once the missile has been fired, the spent BCU is discarded with the LTA.
The round consists of a disposable launch tube assembly, battery coolant unit (BCU). The round has a 10-year shelf life. The only maintenance requirement is stockpile surveillance. Missile range is 2000 meters. The missile locks on to the target before launch using an infrared focal plane array and on-board processing, which also maintains target track and guides the missile to the target after launch. A full-up system weighs 49.5 pounds.
The missile consists of the guidance section, the mid-body section, the warhead, the propulsion section, and the control actuator section. The guidance section provides target tracking and flight control signals. It is the forward section of the missile and includes the seeker head section and the guidance electronics unit. The seeker head section, known as the seeker, contains the missile I2R system and the contact switches used to detonate the warhead. The missile I2R system gives the missile its fire-and-forget capability. During flight to the target, the missile I2R system tracks the target and sends target location information to the onboard guidance electronics unit. The guidance electronics unit serves two functions. It controls the seeker head so that it looks at the target, and it sends signals to the control actuator section to guide the missile to the target during flight.
The Electronic Safe, Arm, and Fire [ESAF] is the principal safety device that prevents accidental ignition of the motors and accidental warhead detonation. The ESAF consists of circuits and two detonators (one for the precursor and one for the main charge). The ESAF controls missile launch sequence and warhead detonation. It permits starting the rocket motors in the proper sequence when the gunner pulls the fire trigger and all other firing conditions have been met. When the missile hits the target, the ESAF detonates each warhead charge in sequence.
The wings provide lift and keep the missile stabilized during flight. The wings fold into slots in the missile skin when the missile is in the LTA and deploy into flight position after clearing the LTA. The control fins maneuver the missile during flight. The spring-loaded fins automatically deploy and lock into flight position after the missile clears the LTA. During flight, they adjust automatically to guide the missile to the target.
The Javelin missile uses a dual-charged warhead. The warhead has a precursor charge and a main charge. The precursor charge is a high-explosive (HE) shaped charge. Its purpose is to cause the target's reactive armor to detonate before the main charge reaches the armor. Once the reactive armor is penetrated, the target’s main hull is exposed to the warhead’s main charge. If the target is not equipped with reactive armor, the precursor charge provides additional explosives to penetrate the main armor. The main charge is the second charge of a dual-charge warhead and is also an HE shaped charge. The primary warhead charge is designed to penetrate the target’s main armor to achieve a target kill.
The launch motor propels the missile out of the LTA. It provides the initial force to push the missile a safe distance from the gunner before the flight motor ignites to ensure the gunner’s safety. The Javelin employs a soft launch mechanism. This means when an operator pulls the trigger, an initial low-g motor ejects the missile from the firing tube. Once it exits the firing tube, the missile then ignites its main flight motor to propel it toward its target. The Javelin’s soft launch mechanism prevents missile exhaust from hitting the operator, enables fires from inside confined spaces and buildings, lowers recoil for shoulder-launched fires, and minimizes launch smoke trails that indicate launch locations and invite counterfire.
The launch motor is completely spent by the time the missile clears the LTA, this accounts for the low signature after launch. The flight motor powers the missile to the target during flight. It ignites when the missile is a safe distance from the gunner, protecting the gunner from hot exhaust gases generated when the motor fires. Thrust Vector Control [TVC] vanes aid the control fins in maneuvering the missile during flight by deflecting the flight motor exhaust. This control changes the angle of thrust from the flight motor, resulting in a change to the missile’s flight path.
|
NEWSLETTER
|
| Join the GlobalSecurity.org mailing list |
|
|
|
