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Possible Indian Military Scenarios - Part IX

BRFite -Trainee
Posts: 75
Joined: 29 May 2007 15:32
Location: Mumbai

Postby gauravjkale » 05 Nov 2007 14:09

welcome back shankar.

Posts: 1905
Joined: 28 Aug 2002 11:31
Location: wai -maharastra

Postby Shankar » 05 Nov 2007 15:08

Squadron leader Scott hunched down on his shoulders and rotated the arms first clockwise and then anti clockwise to get rid of the cramps slowly setting in .In the distance ,about 35 kms to south east he could see the navigation lights of the Indian navy IL-38 turning in lazy circles at about 5000 ft waiting his clearance to start the MAD run .The suspect or rather Hostile Submarine have been bracketed successfully by both of them over the last 3 hrs and now it was time to move in for the kill before any serious damage on the sensitive Darwin Port can be done (this includes the off shore and onshore massive LNG installations)
The attack plan called for the Indian anti submarine aircraft to firm up the contact by a grid wise MAD run as the submarine approached the shallow water of the coast of Darwin. Once located the ,The Indian aircraft will clear the attack zone and move up to 10000 ft quickly as his aircraft will move in on the marked zone and drop a pair of torpedoes on the sub and again climb out of the attack zone .The two Indian sea king helicopters will then move in and confirm the kill has been made –if not the Indian IL-38 will do a second attack run
MAD or magnetic anomaly detection can be used from a height of up to 1000 ft but the usual or optimal deployment altitude for the magnetic anomaly detector located on the tail boom of Il-38 is usually 300 ft which gives the aircraft a 1000 ft under water search corridor under normal sea conditions with moderate turbulence .
Since the magnetic detection sensor is located on the tail, a detection signal is received only after the aircraft has flown past the target submarine. So the usual tactics is to fly past the suspected location of the sub in moderate speed say around 270-290 knots ,get a contact on the MAD detector array then fly back on a reciprocal course. at minimum air speed almost near its stall speed , and get a second confirmatory signal ,followed immediately by dropping the colored smoke marker buoy at the point of contact and then clear the zone . The second attacking aircraft or helo then zeroes on to the zone marked by the MAD carrying aircraft and drops the torpedoes to do the final coup de grace.
A problem arises when a MAD run is attempted on or near a busy sea lane having a high density of surface ships which will also give a good MAD return very similar to a submarine at low depth say less than 100 ft but it will not give SAD return which a submarine will always give unless it is at high depth of more than 1000 ft or more .

Here about 150 km north of north Australian coast lien ocean depth was about 2 km or 2000 plus mtrs ,so if the kilo was diving real deep a SAD return will not be there but Scott hoped the suspect submarine would be found with both the MAD and SAD since no sane sub commander would drive a sub so deep along the treacherous shoreline of northern Australia .

As the banked in to a tight climbing turn the Indian navy May anti submarine aircraft leveled out at precisely 300 ft over sea level and started its first of many MAD runs ,first time in Australian waters .

Posts: 1905
Joined: 28 Aug 2002 11:31
Location: wai -maharastra

Postby Shankar » 05 Nov 2007 16:39


Commander Dixit nodded to the MAD boom operator and he flicked on the circuit breaker that triggered the extension of the telescopic boom from the tail cone smoothly with a slight hiss of hydraulic fluid .The screen came alive with variety of contacts but the clutter quickly cleared up as the filter circuit energized leaving only a few surface contacts on the display .Each was automatically tagged and given a contact number and coded green Dixit eased the large aircraft into a shallow diving bank lining up on the imaginary grid lines on the oceans surface and pulled back on the collective throttle to loose both altitude and air speed for an effective search .

Light, radar, or sound energy cannot pass from air into water and return to the air in any degree that is usable for airborne detection. The lines of force in a magnetic field are able to make this transition almost undisturbed, however, because magnetic lines of force pass through both water and air in similar manners. Consequently, a submarine beneath the ocean's surface, which causes a distortion or anomaly in the earth's magnetic field, can be detected from a position in the air above the submarine. The detection of this anomaly is the essential function of MAD equipment.
When a ship or submarine hull is being fabricated, it is subjected to heat (welding) and to impact (riveting). Ferrous metal contains groups of iron molecules called "domains." Each domain is a tiny magnet, and has its own magnetic field with a north and south pole. When the domains are not aligned along any axis, but point in different directions at random, there is a negligible magnetic pattern. However, if the metal is put into a constant magnetic field and its particles are agitated, as they would be by hammering or by heating, the domains tend to orient themselves so that their north poles point toward the south pole of the field, and their south poles point toward the north pole of the field. All the fields of the domains then have an additive effect, and a piece of ferrous metal so treated has a magnetic field of its own. Although the earth's magnetic field is not strong, a ship's hull contains so much steel that it acquires a significant and permanent magnetic field during construction. A ship's magnetic field has three main components: vertical, longitudinal, and athwart ship, the sum total of which comprises the complete magnetic field.
The steel in a ship also has the effect of causing earth's lines of force (flux) to move out of their normal positions and be concentrated at the ship. This is called the "induced field," and varies with the heading of the ship.
A ship's total magnetic field or "magnetic signature" at any point on the earth's surface is a combination of its permanent and induced magnetic fields. A ship's magnetic field may be reduced substantially by using degaussing coils, often in conjunction with the process of "deperming" (neutralizing the permanent magnetism of a ship); but for practical purposes it is not possible to eliminate such fields entirely.
The lines comprising the earth's natural magnetic field do not always run straight north and south. If traced along a typical 200-kilometer path, the field twists at places to east or west and assumes different angles with the horizontal. Changes in the east-west direction are known as angles of variation, while the angle between the lines of force and the horizontal is known as the angle of dip. Short-trace variation and dip in the area of a large mass of ferrous material, although extremely minute, are measurable with a sensitive magnetometer.
The function, then, of airborne MAD equipment is to detect the submarine-caused anomaly in the earth's magnetic field. Slant detection ranges are on the order of 500 meters from the sensor. The depth at which a submarine can be detected is a function both of the size of the submarine and how close the sensor is flown to the surface of the water.
Improving MAD detection ranges have proved extremely difficult. Increasing the sensitivity of the MAD gear is technically feasible, but operationally, due to the nature of the magnetic anomaly, is not productive. The magnetic field of a source, such as a sub, falls off as the third power of the distance; hence an eight-fold sensitivity increase would serve merely to double the range. Additionally, magnetometers are non-directional; the physics of magnetic fields do not permit the building of instruments that would respond preferentially to a field coming from a particular direction. Hence, a valid submarine caused disturbance frequently is masked by spurious "noise". Also, the ocean floor in many areas contains magnetic ore bodies and similar formations of rock, which can confuse the signal. Further confusion comes through magnetic storms, which produce small but significant variations in the earth's field.
MAD equipment is primarily used as a localization/targeting sensor by aircraft with optimum employment being by helicopters considering their smaller turn radius. Additionally, fixed-wing ASW aircraft MAD configurations are fixed in the tail boom, and helicopters tow the sensor on a 25 - 55 meter cable below and behind the aircraft, which reduces "noise" caused by the helicopter. Because of the relatively short detection ranges possible, MAD is not generally utilized as an initial detection sensor.

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