Javelin is a portable anti-tank missile system consisting of a rocket in a transport-launch container and a detachable command-and-launch unit (CPB) for multiple use. The rocket in the transport and launch container consists of a cylindrical transport and launch container, a power supply and cooling unit, and the rocket itself. The command and start-up unit includes a day / night sight for observation, identification and target acquisition. The rocket has a range of approximately 2000 meters and can be used against buildings and bunkers, as well as armored vehicles.
The ATGM operator Javelin looks at the command and launching unit
Portable anti-tank complexes were an important means by which the US infantry had the ability to withstand Soviet armored forces in Central Europe. The Dragon complex was such a means for most of the Cold War. This wire-controlled anti-tank complex was developed at the end of 1960-x - the beginning of 1970-s and was first deployed in 1975-th year. It was also used in the Gulf War in 1990-91.
The dragon had significant flaws. Its limited firing range (about 1000 meters in its original version) meant that the operator had to be too close to the target for firing, and the wire guidance system meant that the shooter had to remain open and hold the sight mark on the target for rocket flight (up to 11 seconds). In addition, the complex was inaccurate. The infantry school at Fort Benning was an adamant supporter of the creation of a new system. In 1979, the army made the first attempt to replace the Dragon with a complex called Rattler, but after a few months, abandoned this idea due to the fact that the prototype was rejected as too heavy.
In 1981, the Advanced Research Projects Directorate (DARPA) conducted a study to develop anti-tank missile systems capable of using infrared (IR) guidance systems and to hit the least protected upper part of the tank. This program was known as "Tankbreaker". The Tankbreaker technology proved promising, and as a result, the Redstone Arsenal of the US Army was assigned to take over the management of the new ATGM project.
Before the Tankbreaker program, a number of requirements were put forward. Among them, for example, was that the rocket had to have a shot-and-forget system, it had to have a range of 2000 meters, weigh less than 16-kg and attack the target from above. As a result of the competition, applications from Hughes Aircraft and Texas Instruments were selected for further development. Both applications were based on an IR homing head (GOS). As the name suggests, in contrast to the simpler GOS Stinger, which distinguishes only thermal spots, this type of GOS converts IR signals into a two-dimensional image. The Tankbreaker program consisted mainly in the development of the IC GOS, the culmination of which was a series of flight tests (funding was insufficient for determining the level of rocket functionality). Throughout 1985-86, the Infantry School at Fort Benning continued to insist on the need to replace the Dragon complex and began to draw up terms of reference for the new complex. Ultimately, a technical assignment to replace the Dragon with the US Marine Corps was created.
In 1986, the army announced that it was accepting proposals for a two-year phase of verification and confirmation of the principle of action (Proof of Principle, POP) for an average modern anti-tank complex (Advanced Antitank Weapons System — Medium, AAWS-M), thereby initiating a second attempt to replace ATRA Dragon. Contracts worth $ 30 million each were made with Texas Instruments (for the development of infrared technology), Hughes (for the development of fiber-optic targeting technologies) and Ford Aerospace (laser beam guidance). Approximately through the 18 months of the verification and validation phase, the US Army and the US Marine Corps published a request for proposals for the full-size design phase. In the end, a joint venture (JV) was selected, consisting of Texas Instruments (whose rocket business was later bought by Raytheon) and Martin Marietta (now Lockheed Martin). The joint venture won the AAWS-M competition using the proposed rocket design, very similar to what Texas Instruments developed for the Tankbreaker program, namely the shot-and-forget system based on the GOS IR, which can attack the target from above or along a straight path. This rocket was later called the Javelin (Spear). The first army unit was equipped with Javelins in 1996.
The Army’s decision to engage a joint venture to develop Javelin ATGMs was an important part of the program’s success. The intention of the US government to require the creation of a joint venture was under a task already at the development stage to attract two main contractors through their chosen structure. At the production stage, the government intended to divide this joint venture in order to obtain competitive products from each of them separately. Later, for several reasons, the government decided not to fulfill this opportunity and continued to work with the joint venture also at the Javelin ATGM production stage.
The management of the Javelin program also assumed responsibility for the overall management of this joint venture; nevertheless, the technical work and most of the production was carried out by both participating companies on the basis of a partnership agreement. Raytheon is now responsible for the command and start-up unit, the electronic module of the missile guidance system, system software and control of system design. Lockheed Martin is responsible for the final assembly of the missiles and the production of the GOS of the rocket (although, as noted below, Texas Instruments was responsible for the development of the GOS of the rocket).
To work with Javelin, the operator uses an IR finder in the command and launching unit, which provides the image necessary for detecting a target, like a television. Then the operator switches to the IC of the GOS of the rocket, which allows him to set the mark on the target, “fix” it and make a shot. Just like the Stinger MANPADS, the Javelin ATGM system uses a soft-start system to launch a missile from a launch tube, which is necessary for firing from the premises (the Javelin technical task requirement). The sustainer rocket engine is triggered as soon as the rocket leaves the launch canister, 6 of small wings and 4 tail flaps are opened, and the rocket at high speed is sent to the target at a height of about 46 meters on the direct attack path or on top of it. The missile is equipped with a tandem cumulative warhead.
ATGM Javelin proved successful on the battlefield. In the 2003 year, more than 1000 rockets were fired in the Iraq war, and the command and launching unit was used independently of the missile and continues to be a popular night vision device in the US military.
In the next section, the command-start unit and the key system components associated with it will be reviewed. First, the design of the CPB will be reviewed, then the GPS and guidance and control systems, as well as the propulsion system and the warhead. The section ends with a discussion of the use of simulations and simulations in the development of a rocket (not shown in this translation).
Command and starting block (CPB)
The firing process begins with the command-start unit (CPB). Unlike the relatively simple PBC used on the Stinger, the Javelina PBC is a complex component of the system. The CPB has a fourfold telescope and a long-wave infrared night sight with two fields of view with fourfold and ninefold magnifications. Both images - visible and IR - are observed in the same monocular. The CPB operates from a standard army battery, providing the energy needed for operation, the CPB electronics and a cooling device that maintains the operating temperature of the detector matrix. The IR detector is the most important part of the PBC. Unlike previous systems denoting a heat source as a simple spot, the Javelina detector creates a detailed picture of the target. The PBC scans the IR array to enable target recognition. It has a higher resolution than the rocket homing, as the operator needs a high resolution image to determine whether the enemy is on target or not. The infrared detector of the missile launch vehicle (see below) simply has to detect the target after the operator has recognized it and installed an aiming mark on it.
Texas Instruments PBC surpassed the alternative projects involved in the competition, allowing you to see over long distances and showing excellent performance through smoke and other obstacles. It had a matrix in the focal area 240x1, later 240x2 and 240x4, made of cadmium mercury telluride detectors operating in the long-wave infrared 8-12 micron. The detectors scanned with a frequency of 30 Hz in two directions alternating, scanning odd pixels from right to left (1, 3, 5, etc.) and even pixels from left to right. The calculating device allowed the PBC to determine the angular position of the scanning mirror so that it is able to carry out a direct and reverse scan to obtain a coherent picture. The bi-directional scan developed for the Javelin ATGM system was unique and provided significant energy savings. This scan method was later applied in several Texas Instruments programs.
The PBC infrared detector has also become available thanks to a new method for normalizing detector chips. Previously, a so-called “black body” with a constant temperature was used to maintain the calibration of the IR system chips. Texas Instruments has developed a thermal calibration unit (Thermal Reference Assembly, TRA), which is a passive optical unit that provides two temperature reference points by which each detector pixel is calibrated. The first point is in one off-axis reference image, the second point is obtained from the "reflection" created by the cold element. Each time the matrix is scanned, the pixels are calibrated based on the reading of two temperature points. It is important to note that TRA is a passive element that does not require additional power or control circuitry. This allowed developers to use existing detector elements for calibration, as well as reduce power consumption and save space.
To increase the signal-to-noise ratio, Stinger and Javelina infrared detectors require cooling to a very low temperature. The CPD uses a Dewar vessel, a container that uses a vacuum between the double walls to provide thermal insulation. Cooling is carried out using a Stirling closed loop engine with a cold probe from the Dewar vessel and to the back of the detector. The Texas Instruments developed cooling device was designed to reduce power consumption (it consumes just 1 / 5 watts) and meets the weight requirements while cooling the video converter to the required temperature for two and a half minutes. The production of the cooling device initially faced some difficulties, but thanks to the joint efforts of DARPA and Texas Instruments, reasonable costs were achieved.
When developing the IR detector, PSC Texas Instruments used the services of the Night Vision Laboratory (NVL) of the US Army Night Vision Laboratory. NVL shared the necessary experience in modeling IR systems, especially in the field of measuring the minimum resolution temperature (Minimum Resolvable Temperature, MRT) and the development of a video converter. To meet the noise immunity requirements of the army and marine corps, a special development team was created led by the army research laboratory (Army Research Laboratory, ARL). The group, in particular, has developed a technical task for the system noise immunity. The methods and simulations developed by NVL are still standard for measuring the characteristics of IR video converters. NVL also helped introduce a measurement technique called 3D noise and used for more accurate thermal modeling of dynamic noise in sensors at the testing stage. Further development of modeling led to the emergence of new, more user-friendly and more high-precision models.
Since the appearance of the original design of the IR detector, it has been constantly upgraded to improve the performance of the system. At the start of 1990, DARPA funded the program, which ultimately made it possible to make more sophisticated detectors (easy to produce). The result was a so-called Dash 6 detector (Dash 6), which quieted down and scanned quieter, which reduced the acoustic visibility of the operator Javelina on the battlefield. Dash 6 detector entered production in 1998-1999's.
The original PCB was developed using the so-called "through-hole" printed circuit board technology, but this design did not meet the weight requirements. These printed circuit boards used surface mount components. The cost reduction program used advances in the integration of semiconductor devices, especially in compaction of logic elements that can be applied in digital specialized integrated circuits to reduce them to two double-sided printed circuit boards.
Weight reduction was an ongoing task for developers, which influenced all aspects of the development of Javelin’s systems, starting from the IC detector of the PBC and its other parts and ending with the rocket itself. The housing of the CPB was originally made of aluminum. The designers even acid-etched the hull in an attempt to reduce the wall thickness as much as possible. It really reduced the weight, but also increased the cost of its manufacture and worsened the reliability of the device. In 1999, aluminum was replaced by 17 layers of carbon composite fiber. This somewhat reduced the weight, but basically made the case stronger. In addition, the manufacturing process was more consistent than acid pickling. In the current PJavelina PBC, the average time between failures is more than 300 hours compared to the 150 specified in the terms of reference.
In the new generation of Javelin Block 1 planned to use an improved CPB. It will be equipped with optics with magnifications of 4x and 12x instead of 4x and 9x. The PBC will also include a color flat display based on organic LEDs. The goal of the upgrade is to increase the range of the detector by 50 percent, but weight restrictions, in turn, impose serious restrictions on the improvement of optics.
To be continued