Pushpendra



INTRODUCTION TO THE ARMOURED FIGHTING VEHICLES:
By Pushpendra Singh

1.1) CONCEPT OF MODERN BATTLE TANK DEVELOPMENT:
The idea of development of the modern tracked fighting vehicle arose from the visualization of the armoured Rolls Royce cars used in 1914.The awareness to create such a vehicle arose in the mind in the First Lord of the Admiralty, Winston Churchill, who sponsored the Landships Committee to oversee development of this new weapons system. The first successful prototype tank, nicknamed "Little Willie", was tested for the British Army on September 6, 1915. Although initially termed "landships" by the Admiralty, the initial vehicles were colloquially referred to as "water-carriers", later shortened to "tanks", to preserve secrecy. The word "tank" was used to give the workers the impression they were constructing tracked water containers for the British army in Mesopotamia.
Fig.1. This German photograph from World War I shows a captured British tank.This diagram shows the past scenario of the tanks. The foremost part of the tracks is high off the ground in order to climb obstacles. The main guns are side-mounted to keep the centre of gravity low.

The first tank became operational when Captain H. W. Mortimore of the Royal Navy took a Mark I into action at Delville Wood during the Battle of the Somme on September 15, 1916. The French developed the Schneider CA1 working from Holt caterpillar tractors, and first used it on April 16, 1917. The first successful use of massed tanks in combat occurred at the Battle of Cambrai on November 20, 1917.
The tank would eventually make trench warfare obsolete, and the thousands of tanks, fielded by French and British forces ,made a significant contribution to the war. Initial results with tanks were mixed, with problems in reliability causing considerable attrition rates when getting the tanks into combat and on the move. They lacked the mobility and flexibility.This forced the development of tanks such as the Mark IV, which rhomboid shape could navigate large obstacles, especially long trenches. The development of the modern battle tank concept arose from the mobility and maneuverability characteristics of Mark IV tank.
With the tank concept now established, several nations designed and built tanks between the two world wars.

1.2) OVERVIEW OF MODERN MATTLE TANKS:
A modern battle tank is a tracked, armoured combat vehicle (armoured fighting vehicle), designed primarily to engage enemy forces by the use direct fire. A modern main battle tank (MBT) is distinguished by its high level of firepower, mobility and armour protection relative to other vehicles of its era. It can cross comparatively rough terrain at high speeds, but is fuel, maintenance, and ammunition-hungry and is logistically demanding. It has the heaviest armour of any vehicle on the battlefield, and carries a powerful weapon able to engage a wide variety of ground targets. It is among the most versatile and fearsome weapons on the battlefield, valued for its shock action against other troops and high survivability.
Tanks are usually employed with infantry in combined arms warfare, supported by engineers, artillery, aircraft, and other support arms. If not properly protected, tanks can be vulnerable to attack by infantry, mines, artillery, and aircraft strikes.
1.3) GENERAL CHARACTERISTICS OF MODERN BATTLE TANKS:
The characteristics of main battle tanks can be viewed in terms of various factors:
1.WEAPON SYSTEM:
The main weapon of any modern tank is a single large gun. Tank guns are among the largest calibre weapons in use on land, with only a few artillery weapons being larger. Although the calibre has not changed substantially since the end of the Second World War, modern guns are technologically superior. The current common sizes are 120-mm calibre for Western tanks and 125-mm for Eastern (Soviet and Chinese legacy) tanks. Tank guns have fired many types of rounds, but their current use is commonly limited to kinetic energy (KE) penetrators and high explosive (HE) rounds. Some tanks can fire missiles through the gun. Smoothbore (rather than rifled) guns are the dominant type of gun today. The British Army and the Indian Army are now the only ones to field main battle tanks with rifled guns.
Modern tank guns are generally fitted with thermal jackets which reduce the effect of uneven temperature or cooling of the barrel. Eg if it were to rain on a tank barrel the top would cool faster than the bottom, or a breeze on the left might cause the left side to cool faster then the right. This uneven cooling will cause the barrel to bend slightly and will effect long range accuracy. The thermal jacket reduces this uneven cooling.
Usually, tanks carry other armament for short range defence against infantry or targets where the use of the main weapon would be ineffective or wasteful. Typically, this is a small calibre (7.62 to 12.7 mm) machine gun mounted coaxially with the main gun. However, a couple of French tanks such as the AMX-30 and AMX-40 carry a coaxial 20-mm cannon that has a high rate of fire and can destroy lightly armoured vehicles. Additionally, many tanks carry a roof-mounted or commander's cupola machine gun for close-in ground or limited air defence. The 12.7-mm and 14.5-mm machine guns commonly carried on US and Russian tanks and the French Leclerc are also capable of destroying light armoured vehicles, such as APCs and possibly IFVs at close range.
Some tanks have been adapted to specialised roles and have had unusual main armaments such as flame-throwers. These specialised weapons are now usually mounted on the chassis of an armoured personnel carrier.
2. FIRE CONTROL:
Historically, tank weapons were aimed through simple optical sights and laid onto target by hand, with windage estimated or assisted with the reticule. Range-finding was initially estimated, then estimated again with the aid of the reticule (which uses the measurement of angles, measured in the reticule of known sized objects as a method for range finding), which was later supplemented with stereoscopic optical range-finders, which remained the standard until the introduction of laser range-finder. Consequently, accuracy was limited at long range and made concurrent movement and shooting largely impossible.
Most of the modern MBTs and upgraded MBTs in the armies of industrialised countries use a laser range-finder but optical and reticule range-finders are still in use in older and less sophisticated vehicles. Modern tanks have a variety of sophisticated systems to make them more accurate. Gyroscopes are used to stabilise the main weapon; laser range-finders are used to measure the range to the target; computers calculate the appropriate elevation and aim-point, taking into account many factors such as wind speed, air temperature, humidity, the temperature of the gun, the speed of the target (calculated by taking at least two sightings of the target with the range-finder), the speed of the tank, the bend of the barrel, and the wear of the barrel. Night and infrared vision equipment is also commonly included. Laser target designators may also be used to illuminate targets for guided munitions. As a result modern tanks can fire reasonably accurately while moving. .
Most of the modern MBTs and upgraded MBTs in the armies of industrialised countries use a laser range-finder but optical and reticule range-finders are still in use in older and less sophisticated vehicles. Modern tanks have a variety of sophisticated systems to make them more accurate. Gyroscopes are used to stabilise the main weapon; laser range-finders are used to measure the range to the target; computers calculate the appropriate elevation and aim-point, taking into account many factors such as wind speed, air temperature, humidity, the temperature of the gun, the speed of the target (calculated by taking at least two sightings of the target with the range-finder), the speed of the tank, the bend of the barrel, and the wear of the barrel. Night and infrared vision equipment is also commonly included. Laser target designators may also be used to illuminate targets for guided munitions. As a result modern tanks can fire reasonably accurately while moving.
3.PROTECTION:
The main battle tank is the most heavily armoured vehicle in modern armies. Its armour is designed to protect the vehicle and crew against a wide variety of threats. Commonly, protection against kinetic energy penetrators fired by other tanks is considered the most important. Tanks are vulnerable to antitank guided missiles. Antitank mines, larger bombs, and direct artillery hits can also disable or destroy a tank. Tanks are especially vulnerable to airborne threats. Most modern MBTs do offer near complete protection from artillery shrapnel and lighter antitank weapons such as rocket propelled grenades. The amount of armour needed to protect against all conceivable threats from all angles would be far too heavy to be practical, so when designing an MBT much effort goes into finding the right balance between protection and weight.
4. MOBILITY:
The main battle tank is the most heavily armoured vehicle in modern armies. Its armour is designed to protect the vehicle and crew against a wide variety of threats. Commonly, protection against kinetic energy penetrators fired by other tanks is considered the most important. Tanks are vulnerable to antitank guided missiles. Antitank mines, larger bombs, and direct artillery hits can also disable or destroy a tank. Tanks are especially vulnerable to airborne threats. Most modern MBTs do offer near complete protection from artillery shrapnel and lighter antitank weapons such as rocket propelled grenades. The amount of armour needed to protect against all conceivable threats from all angles would be far too heavy to be practical, so when designing an MBT much effort goes into finding the right balance between protection and weight.
For most tanks, water movements are also possible. The water operations are limited to fording. The fording depth is usually limited by the height of the air intake of the engine, and to a lesser extent the driver's position. Typical fording depth for MBTs are 90 to 120 cm. However, with preparation some tanks are able to ford considerably deeper depths. The West German Leopard I and Leopard II tanks can ford to a depth of several metres, when properly prepared and equipped with a snorkel. Some light tanks such as the PT-76 are amphibious, typically being propelled in the water by hydrojets or by their tracks.Often a fold down trim vane is erected to stop water washing over the bow of the tank and thus reducing the risk of the vehicle being swamped via the driver's hatch.

1.4) ARE THESE CHARACTERISTICS SUFFICIENT?

“In modern tanks, in first gear, you can take your pet turtle for a walk. In the sixth, you can walk away from almost anybody. Its like a pussy cat on metalled roads or built up areas and a lion in the open fields and deserts.”
The present day tanks are equipped with the necessary characteristics, such as-1.Adequate Fire Power capability, 2.Protection facilities, 3.Provision of Surplus power, as required, 4.Shock Action capability and 5. Good Mobility and Maneuverability characteristics. Undoubtedly these are the necessary factors for an effective tank operation; but not sufficient enough for the required present day combat effectiveness.
In addition to the above, some of the other suggested qualities include-1.Capability of avoiding enemy detection, 2.Reduced target size(Presentation of low silhoutte) and weight for greater mobility, 3.Reduced crew size for weight reduction, 4.More unmanned operational effectiveness, 5.Crew comfort improvement, 6.More destructive potential with advanced weapons systems, 7.Dual Purpose Armour development, both for protection as well as reaction to enemy attacks, 8.Capability of Silent operations, required for Shock Action purpose, 9.Enhanced endurance and what not! Thus, creativity plays a great role behind establishing these sufficient facilities.

2. NEED FOR FURTHER RESEARCH IN COMBAT FIELD:

“A battle tank can be described as an unique animal. It needs the speed of a greyhound, the strength of a bull, the suspension of a kangaroo and the staying power of a mule. Then, when its all put together, its supposed to handle like a champion show horse.”
Battle tanks are offensive weapons system; thus they should be equipped with advanced protection systems also to suffice their survivability aspect in the modern devastating battlefield. In order to improve upon the tank qualities, as mentioned above, new designs of battle tanks are necessary. Tanks and tank tactics have undergone many generations of evolution over nearly a century. Although weapons systems and armour continue to be developed, many nations have been reconsidering the need for such heavy weaponry in a period characterised by unconventional warfare.
The new designs are directed to increasing the battlefield lethality of the tanks by improved ammunition and increased calibers and also towards a higher level of tank protection.In order to decide for the possible new designs to be conducted, a short glimpse at the present combat system drawbacks should be taken. The present day tanks have-1.Thicker and heavier armour, 2.Increased size and weight, 3.Increased target size, 4.Increased armoured volume and 5.Reduced survivability and mobility. These are not at all the acceptable status for the modern tanks. Thus other alternative actions should be adopted.
Military Researchers are resorting to radical designs in order to achieve: 1.Reduced volume, 2.Reduced target size, 3.Reduced weight, 4.Enhanced protection, 5.Detection Avoidance, 6.Hit Avoidance and 7.Enhanced endurance.
Need for further design may arise due to desire to abandon the classical concept of the turreted tank in favour of concepts for lighter vehicles, featuring external or overhead-mounted main armament. There will be demands for increased lethality of tank armaments against other hostile tanks and against hostile helicopters(The most dreaded and undefeatable enemy of the modern tanks). In this respect there seems to be no second opinion to use a high pressure gun in the forseable future. It may be necessary to increase its caliber and to introduce new types of ammunition. To help improved crew survivability and vehicle restorability, the main armament has to be located in such a position that the volume of the tank can greatly be reduced. An automatic loader will have to be introduced to load rounds from a magazine that well may be totally separated from the crew and other vital components. One very important aspect of battletank design, that has a significant bearing on the effectiveness of such vehicles, is their availability, ie, the ability of an individual tank to be ready for battle at any given time and in any location. There may be a requirement to alter the present shape of the tanks, in order to achieve this area. To enhance availability, the vehicle weight must be kept down to a level at which maximum use can be made of all infrastructure in potential warzones. Increased availability is also a function of speed, fuel consumption, reliability and life of mechanical and electrical components. To cite an example, both NATO and Warsaw Pact countries are trying to rectify this problem, especially the NATO countries, whose battle tank weight lies between 55-65 tonnes. Improvements are continually being made in this respect, leading to greater component weight savings and volume reductions in the future(in the field of propulsion, notably). However these savings are not the only remedy, which might enable researches to work along traditional improved lines.

2.1) BASIS OF BATTLE TANK DESIGN:
The three traditional factors determining a tank's effectiveness are its firepower, mobility, protection and shock action . The psychological effect of a tank's imposing battlefield presence on enemy soldiers is called shock action. Thus, initially a silent operation of the tank is needed from a non-detectble range; as it approaches very near to the enemy line, it needs to generate huge noise so as to confuse the enemy about the side from which the tank is approaching.Thus the tank needs to have a flexible and well maintained power train in opeation. Firepower is the ability of a tank to defeat a target. This includes the maximum distance at which targets can be engaged, the ability to engage moving targets, the speed with which multiple targets can be destroyed, the capability to defeat armoured vehicles or entrenched infantry, and the ability to continue fighting after damage has been sustained.
Mobility includes the speed and agility of driving cross-country, the types of terrain that can be covered, the size of obstacles, trenches, and water that can be crossed, the ability to cross small bridges, and the distance that can be covered before refuelling is required. "Strategic mobility" also includes the ability to travel at high speed on roads, and the ability to be carried on rail or truck transport. Traditionally AFV mobility is measured by the following metrics:
engine power
engine torque
power-to-weight ratio
road speed
off-road speed (a somewhat nebulous figure given the possible variation)
road range
off-road range
weight (bridge classification)
ground pressure
width of trench crossed
vertical step climbed
angle of slope that can be climbed
angle of side slope that can be negotiated
ground clearance
unprepared fording depth
prepared fording depth (if different)
Protection is the amount of armour, the type(s), how it is arranged (e.g., whether it is sloping or not), and which areas are given more protection (e.g., the turret and tracks) and which receive less (e.g., the rear of the chassis). It also includes low profile, low noise and thermal signature, active countermeasures, and other methods of avoiding enemy fire.
Tank design is traditionally considered to be a compromise between these three factors—it is not possible to maximise all three. For example, increasing protection by adding armour will increase weight and therefore decrease manoeuvrability; increasing firepower by using a larger gun will decrease both manoeuvrability and protection (due to decreased armour at the front of the turret).
However,the compromise is achieved by a combination of factors, including military strategies, budget, geography, political will, and the requirement to sell the tank to other countries.
Let us take examples of a few countries to briefly discover basis of their designs:
Britain has historically opted for better firepower and increased protection at the expense of some manoeuvrability. Britain maintains a small, highly trained professional army, and so tank crew survivability is important. As limited resources may be available, the crew needs to be able to maintain their tanks in the field, and, with a succession of secondary sites available, are able to keep fighting if the primary site is out of action.
USA has a large army with sophisticated weaponry and a complex array of mobile support services. As their tanks are expected to rarely be away from support and repair units, less emphasis is placed on the crew's ability to maintain the tank themselves or to continue fighting with it once damage has been sustained.
Germany had tanks were completely outmanoeuvred on the Russian front during WWII by the T-34, which was a major factor in their defeat. Also they lost more of their overly complex Tiger and Panther tanks due to mechanical breakdowns than enemy action. As a result German tanks in the post war era have been designed to be very manoeuvrable, with a resulting decrease in protection. Enhanced reliability and lower maintenance requirements have also been important design goals.
Israel is a small, but relatively rich, nation, with limited manpower in a hostile political environment. Its primary concern is therefore crew survivability. To this end it is the only nation to have produced a modern tank with the engine placed at the front, to increase protection for the crew behind it.

3) CURRENT DESIRED RESEARCH PROGRAMS:
Modern progressing Research and Development activities, taking place in the field of Combat Engineering, are mostly directed towards the upgradation of the already existing facilities on an armoured fighting vehicle, for improved flexibility, survivability and surveillance activities on the battlefield. Its not totally devoted to the generation of a completely new Future Combat System, which cannot be identified as a particular category of the present day battle tank, as we see today.
Tank research and development activities were in the booming stage, during the period when the United States and the Soviet Union were engaged in a massive arms race. It continued in many industrial countries despite the end of the Cold War;but with a low investmest because of the lack of forecasting future threats.One of the most pioneer contributors to innovative tank designs, is the Kharkiv Morozov Machine Building Design Bureau, which is at present a unit of the Ukranian government. Another important contributor to the battle tank protection and reconnaissance systems, is the U.S. Defence Advanced Research Program Agency(DARPA), which we’ll see later.
The latest battle tanks show a growing trend for computerization and automation of components. Future tank designs, such as the Russian T-95 and the US MCS, are proposed with unmanned turrets, with the crew in a single compartment in the hull of the tank, from which they can control the turret remotely. The turret's automatic loading system can then fire ammunition faster and of a size too large for a human loader, as well as store ammunition more efficiently since there is no need for crew space in the turret. Thus, the trend towards production of turretless tanks(ie, abandoning of two-tier arrangement for a single tier) can be achieved in two ways:1.Main Armament out of the crew compartment and 2.Remote controlled automatic gun-loading system. Because the crew are contained in a single compartment space in the hull, the tank's size and mass can be reduced. Composite designs and lighter chassis are also proposed to reduce the tank's weight further to improve deployment and logistics.Thus research is conducted accordingly. Thus, the desired activities are mainly concentrated on the following areas:
1.Weapons Research.
2.Armour Research.
3.Stealth Research.
4.Power Plant Research.

3.1) Weapons Research:
A battle tank is not a defensive weapons system; but totally an offensive one in the Army. It is an attacking system. Thus one of the major prerequisites of battlefield survivability of the tank, is the advanced weapons systems on it. Initially battle tanks were fitted with the main cannon system.Since the end of the second world war and the general introduction of missiles, many have speculated that the modern battle tank's main cannon has become inferior and thus have become obsolete. With anti-tank missile having greater range, accuracy and ergonomics, the battle tank’s cannons had proved ineffective.
Thus, it was proposed for a missile as the tank armament system,initially. A missile-carrying tank could be turret-less, thus reducing the tanks visible profile, weight and construction costs. Missiles could be launched vertically to reduce target acquisition time and increase the rate of fire. Also a missile tank with advanced computerize missiles could target anything from airplanes, helicopters, ships and stationary targets. But then came the supporters of the advanced guns system.They were opposed to missiles, pointing out that advanced gun systems can do all of the above, in addition to killing enemy soldiers with shrapnel rounds, in a more cost-effective way. They have also pointed out that anti-tank missiles have proved ineffective in penetrating the rapidly developing armour standards, with their increased protective and reactive potential. The debate on the relevance of guns and missiles continued over the decades.
Modern tank armament development has tended to focus on cannon fired KE penetrators,ie armour piercing ammunitions,such as High Explosives Squash Head, High Explosive Anti Tank and hollow shaped charges as well.It was found that most of the developed armour systems could not defeat these very basic rounds. Increasing the velocity of gun-fired penetrators has been a major focus to increase range, accuracy and penetration. At present, weapons research is conducted in the following areas:
1.Conventional 140mm guns.
2.Liquid Propellant Guns.
3.Electromagnetic Guns.
4.Electrothermal Chemical Guns.
5.Plasma Impulse Guns.

3.1.1) Conventional 140mm guns:
The latest tanks are already well armed with guns of 120mm or 125mm, which are capable of defeating heavy armor, and their performance can be stretched further. However, there are indications that, even at their best, these guns will not be able to defeat the kinds of armour that are being developed for future tanks. In that situation, it is necessary to resort to guns of larger calibre, and several countries have been working for some time on 140mm guns that fire APFSDS projectiles with twice the muzzle energy of those fired by the current 120mm tank guns.

A major consequence of the diminished urgency to develop novel guns in the near foreseeable future is that conventional, Solid Propellant (SP) guns will remain in service for many years to come, and their lethality will be gradually enhanced. The typical High Velocity Armor PiercingFin Stabilized Discarding Sabot(HV-APFSDS) projectile has been successively improved over the last three decades with suggested near-future penetration capability of up to 800-900+ mmof Rolled Homogenized Armor (RHA).This was primarily achieved by a progressive increase of the geometrical ratio ‘Length/Diameter’ (L/D) of relatively long and slender rod penetrators and continuous improvements to their corresponding materials (Tungsten Alloys,Powder Metallurgy-PM, Depleted Uranium-DU, and Variable Density Penetrators-VDP). Penetrators with high ‘L/D’ ratios proved effective against RHA but they were found considerably less effective against composite and/or complex armor. To augment its effectiveness against thelatter, the penetrator rod must have a larger diameter. Without reverting to lower and adverse ratios of ‘L/D’ (approximately20/1 for 120mm and experimental140mm and still increasing), it must ultimately result in an increase of volume and mass of the penetrator rod and therefore, inevitably, in a corresponding undesirable reduction of the effective muzzle velocity. Utilization of progressively heavier rod penetrators to defeat contemporary and ever-improving armor protection required higher muzzle energy [presently 18-20 megajoules(MJ)]. Consequently, it led to guns withever-increasing chamber pressures and likewise, larger gun calibers (90, 105,120, 140mm, Western preference). Following a MOU previously signed in 1988 with the U.S., Giat (France), Rheinmetall (Germany) and Royal Ordnance (U.K.) are contemplating a joint venture to develop, market and produce a standardized 140mm smoothbore/rifled gun and ammunition. The weapon system is designated by NATO as the Future Tank Main Armament(FTMA) and is claimed to have a significant increase in armor penetration over the standard 120mm tank gun.

As part of this development, the German firm of Rheinmetall has mounted its 140mm gun in a Leopard II tank. The Swiss Federal Construction Works has also mounted its 140mm gun in a Leopard II. These experiments indicate that the retrofitting of 140mm guns in the existing tanks is possible. But it presents a number of major problems. In particular, 140mm rounds are large and heavy, which makes them difficult, if not impossible, to manhandle. As a result they require automatic loading systems, and this implies major changes to tank turrets and a reduction in the size of tank crews from four to three men. The UK, Germany and France are working on a 140mm tank gun. While these can be fitted to tank turrets, the size of the rounds and the need for an autoloader make the practicality of this doubtful. One option may be to adopt an assault gun configuration capable of high elevation fire. A 140mm high velocity gun could be at least equal in range to a 155mm howitzer [5.5" (140mm) were the standard medium field piece of the British Army in the Second World War]. A 140mm gun on an assault gun body could be a useful weapon system both for divisional artillery and to reinforce armored or infantry attacks. The only problems with this idea at present is that the prototype 140mm gun is smoothbore, and no 140mm guided projectiles currently exist. The only type of automatic loading system, which may readily be installed in existing tanks, is one installed in the turret bustle. In consequence, the configuration of tanks rearmed with 140mm guns should resemble that already adopted for the Japanese Type 90 and the French AMX Leclerc. In fact, this configuration has actually been adopted for CATTB, (Component Advanced Technology Test Bed) built recently in the US, to explore the future form of tanks. Thus CATTB has a three-man crew and a bustle auto loader for its XM-291 gun, which can be fitted with either a 120mm or a 140mm barrel. Because of the problems they pose and the absence of a threat, which would urge their adoption, the development of 140mm tank guns is proceeding slowly. The problems they pose are also encouraging people to consider potential alternatives to conventional 140mm guns. One of them is liquid-propellant guns, which were seriously considered for tanks.
Notwithstanding the 140mm gun andammunition’s indisputable potential, the larger gun size will command a bigger and heavier vehicle. If the requirement to reduce weight and volume is going to remain firm and strictly enforced, it is most unlikely that the 140mm gun andheavy ammunition will find their way into the FCS.

3.I.2) LIQUID PROPELLANT GUNS:
Regardless of how SP guns will ultimately evolve, both users and defense research community have concluded that solid propellants are not the most efficient medium of conveying to a projectile, the energy required to defeat the ever-evolving threat. Consequently, since the mid 80’s, there has been a significant increase in Western R&D interest and research efforts, aimed particularly at developing new technologies, which will substitute for contemporary SP gun systems.
Thus, Liquid Propellant(LP) gun propulsion technology is another viable alternative. LP technology is the outcome of extensive R&D efforts performed in several countries, ever since the end of WWII. Though LP is technologically based on a sound engineering foundation, it is presently known to experience inherent prematuration, nagging problems such as ignition control, excessive corrosion, combustion non-repititiveness, sealing, exorbitant weight growth, material contamination and difficulties in handling of LP. LP requires the continuous resupply of propellant working fluid, which does not conform favourably with stringent requirements of reduced logistics. LP, in conjunction with 120/140 mm tank guns with regenerative, multistaging propellant injection systems, could reach muzzle velocities up to 220-22500 m/s respectively at best. Its about 10-15% higher than that what could ultimately be achieved with SP 120/140 mm guns. This only holds true if ailing problems with traveling charge or stage propellant will be satisfactorily resolved to match the injected charge front propagation speed, through the entire injection process with that of the projectile as it advances down the barrel. It has already been demonstrated that by using a 30mm two stage traveling charge, velocities as high as 3100m/s and beyond could be achieved. Thus LP guns have a high level of design flexibility and possess controlled, variable lethality and permit a relatively large stowed load due to improved efficiency of LP storage and reduced volumetric requirements in comparison to SP combustible cases. Other advantages are safer storage of LP via compartmentalization, improved piezometric efficiency and extended barrel life due to a much cleaner and better controlled combustion processes. Last, but not the least, RILP technology represents a rational leverage of the substancial investment already made in the LP version of the revolutionary Crusader.
But, LP technology, though belived to be the prime alternative to SP, is sometimes viewed as less attractive for ground mobile applications and thus may not become the main armament of the FCS. Nonetheless, all this may dramatically change if these technical difficulties would somehow be removed satisfactorily. Inspite of its recent handicap, research and development of Regeneratively Injected LP guns (RILP) for various ground tank applications will most likely continue. Figure below demonstrates the inteaction between the liquid propellant and the moving mechanical components of the gun.

FIG.2. RILP gun with its moving mechanical parts.

3.1.3) ELECTROTHERMAL CHEMICAL GUNS:
Encouraging results have been obtained with Electrothermal Chemical (ETC) experimental guns. In principle, it uses a chemically energetic working liquid instead of conventional solid propellants. It requires considerably less electrical energy to achieve adequate projectile propulsion than its predecessor-Electrothermal experimental guns. It needs relatively smaller and lighter auxiliary equipment to produce and store electricity. Electrothermal-Chemical (ETC) technology is an advanced gun propulsion candidate that can substantially increase gun performance with less system burden than any other advanced gun propulsion technology. It has been under development since the mid 1980s.ETC uses electrical energy to augment and control the release of chemical energy from existing or new propellants, and can significantly improve the performance of existing conventional cannons, both direct fire (e.g., tanks) and indirect fire (e.g., howitzers and Navy guns). The electrical energy is used to create a high-temperature plasma, which in turn both ignites the propellants and controls the release of the chemical energy stored in the propellants during the ballistic cycle.This equipment could ultimately be reduced to a suitable size to warrant its installation on armoured vehicles. Energetic working fluid is naturally prone to be problematic in operation, handling, storage and supply, such that its utilization will pose a potential safety concern and a logistic burden, similar to LP guns. As in LP, ETC implementation requires new industrial and military infrastructures for production, deployment, and logistics. Current developments are aimed at a medium caliber (60-80mm), antitank gun with a firing rate of 10-15 rounds/min. At this caliber range, various types of rounds could be comprised of KE projectiles and CE rounds, as well as future‘smart’ sensor-fuzed munitions.
United Defense Industries achieved an industry first recently when it successfully fired a 120mm Electrothermal Chemical (ETC) gun from a hybrid electric drive combat vehicle(Shown below).This effort, using a fully integrated 100kJ pulse power system, was accomplished through a Cooperative Research and Development Agreement with the US Army's Armament Research Development and Engineering Center (ARDEC). ARDEC is the Army's center of excellence for armament systems development.
Fig.3.United Defense Industries' 120mm Electrothermal Chemical gun.
The ultimate objective is aimed at an ETC automatic gun with a muzzle energy of 20+MJ (corresponding to 2500-3000 m/secfor medium calibers) which is comparable to that of the conventional, solid propellant140mm gun. Much like LP guns, ETC technology allows better control of the pressure (propulsion) generated, so that it is maintained relatively close to its maximum while the projectile is moving down the barrel, resulting in more energy conveyed to the projectile. This is quite contrary to conventional SP technology, where the pressurequickly diminishes as the projectile departsfrom the combustion chamber. ETC technology is recognized by many to show promise of “infinite” or multistage variable lethality and improved propulsion controllability. It also requires significantly less electrical energy in comparison to Electro-Magnetic (EM) guns that use only electricity for projectile propulsion. Nevertheless, ETC technology, as promising as it may seem, requires further fundamental research beyondthe laboratory stage. Much detailed research and testing has yet to be accomplished in the field and at weapon systemlevel. It must achieve maturation to warrant its applicability asa stand-alone solution, or in conjunction with other mature technologies, or with existing 120/140mm guns. As an additional practical alternative, ETC technology could be combined with existing conventional SP 120mm and/or future 140mm guns and ammunition, though a new cartridge and modifiedgun chamber are required. It represents a near-term upgrade application of already leveraged and proven technology. Thesize of the electrical equipment is much smaller than that of current EM research guns and present ETC as a viable upgrade proposition. Research has shown that specially designed ammunition and ETC gun technology could be combined with existing conventional SP guns to further enhance the performance of the latter up to 30% and beyond. Augmenting the energy of solid propellant is possible by implementing a plasma regenerative injector and combustion control to the conventional pressure chamber. In the event that ETC technology will become practical, existing conventional 120mm and future 140mm guns could be economically converted into ETC/SPguns as one more step in the evolutionof SP guns. There are still various predominating problems to be addressed and resolved before ETC guns can become a practical proposition in conjunction with conventional solid propulsion. The combination of controllable, repeatable inner ballistics with a compatible solid propellant, and the significant increase in performance (e.g. muzzle velocity) in large caliber guns, has yet to be demonstrated. Regardless of whether ETC technology will become a viable proposition, the useof large consumable ammunition in addition to ‘energetic’ liquid propellant is contradictory to the requirement of reduceddependency on logistics andweight. The combined implementation of SP with ETC, will probably not justify the enormous investment in design, development and deployment associated with the fielding of an entirely new tank fleet. Though new and promising technology, it will not change the nature of armored warfare.

3.1.4) ELECTROMAGNETIC GUNS:
These are also known as the Pulsed-Power EM guns. They consist of two varieties-1.Rail guns and 2.Coil guns.
3.1.4.1)RAIL GUNS:


Fig.4. Schematic Diagram of an Electromagnetic Rail gun.
Railgun is a form of gun that converts electrical energy—rather than the more conventional chemical energy from an explosive propellant—into projectile kinetic energy. Railguns utilize an electromagnetic force called the Lorentz force to propel an electrically conductive projectile that is initially part of the current path. Sometimes they also use a movable armature connecting the rails. The current flowing through the rails sets up a magnetic field between them and through the projectile perpendicularly to the current in the rail. This results in a mutual repulsion of the rails and the acceleration of the projectile along them.The world's first large scale railgun was designed and constructed in the 1970s by John P. Barber, a Ph.D. Scholar from Canada and his advisor Richard A. Marshall from New Zealand, in the Research School of Physical Sciences at the Australian National University. The system used the very large (500MJ of stored energy) Mark Oliphant homopolar generator as its energy source.

Theory and construction:


Fig.5. Schematic diagram of a railgun

Although conceptually simple, the operation of a railgun involves several factors that have to this day made a practical design (one that can be employed in the field in order to replace conventional weapons) impossible.A wire carrying an electrical current, when in a magnetic field, experiences a force perpendicular to the direction of the current and the direction of the magnetic field. This is the principle behind the operation of an electric motor, where fixed magnets create a magnetic field, and a coil of wire is carried upon a shaft that is free to rotate. When electricity is applied to the coil of wire a current flows, causing it to experience a force due to the magnetic field; the wires of the coil are arranged such that all the forces on the wires act to make the shaft rotate, and so the motor runs.
A railgun is even simpler than a motor. It consists of two parallel metal rails (hence the name) connected to an electrical power supply. When a conductive projectile is inserted between the rails (from the end connected to the power supply), it completes the circuit. Electrical current runs from the positive terminal of the power supply up the positive rail, across the projectile, and down the negative rail back to the power supply again.This flow of current makes the railgun act like an electromagnet, creating a powerful magnetic field in the region of the rails up to the position of the projectile. In accordance with the right-hand rule, the created magnetic field circulates around each conductor. Since the current flows in opposite direction along each rail, the net magnetic field between the rails (B) is directed vertically. In combination with the current (I) flowing across the projectile, this produces a Lorentz force which accelerates the projectile along the rails. There are also forces acting on the rails attempting to push them apart, but since the rails are firmly mounted they cannot move. The projectile is able to slide up the rails away from the end with the power supply.
If a very large power supply, providing a million amperes or so of current, is used, then the force on the projectile will be tremendous, and by the time it leaves the ends of the rails it can be travelling at many kilometres per second. 20 kilometers per second has been achieved with small projectiles explosively injected into the railgun.
3.1.4.2) COIL GUNS:
Coil guns use electric currents within coils inside a barrel that generates a magnetic field. This magnetic field then induces a current in an armature that creates a counter magnetic field, creating an acceleration on the armature and its projectile. The armature and projectile are accelerated to high velocities by sending it through a series of switched coils timed to the passage of the armature and projectile. Because the armature and barrel coils are coupled magnetically, the armature and projectile are self-centering within the barrel coils, with no physical contact between the armature and the barrel coils, eliminating barrel wear. The current state of development of coilgun technology makes them better suited for lower velocity, higher mass uses than kinetic weapons applications (e.g., missile or torpedo launchers, or even mortars).Sandia National Laboratory is one organization that is currently working on coil gun technologies (Picture shown below).
Fig.6 Diagram showing coil gun concept.

Thus, a Coilgun (also known as Gauss gun rifle or Gauss) is a type of cannon that uses a series of electromagnets to accelerate a magnetic shell to very high velocities. The appellation "Gauss gun" comes from Carl Friedrich Gauss, who formulated mathematical descriptions of the electromagnetic effect used by coilguns. Coilguns are often mistakenly called railguns by many sources, and while they are similar in general concept (that is, a magnetic gun), they differ in operation, as a railgun accelerates projectiles down two parallel conducting rails. Coilguns are essentially identical to mass drivers, though on a smaller scale. Kristian Birkeland is commonly considered the inventor of the electromagnetic coilgun, for which he obtained a patent in 1900. The attempts to turn his invention into a usable weapon failed, and the idea was more or less forgotten for many years.Many hobbyists use low-cost rudimentary designs to experiment with coilguns. One such design would incorporate the use of photoflash capacitors from a disposable camera as the energy source, and a low inductance coil to propel the projectile forward.
The power must be delivered to each successive electromagnet with precise timing, due to hysteresis. Electromagnets take some time to reach full strength after voltage is applied , so the power supply must start before the shell has reached a particular magnet. The same is true after the power is turned off, and if the shell is on the "far side" of the magnet at that time, the magnet will continue pulling on it, slowing it down. One obvious solution would be to trigger the magnets long before the shell reaches them, but because magnetic force drops off with the square of distance (that is, very quickly) too much power would be lost with such a solution. For this reason most coilguns that use more than one magnet include some sort of electronic timing device for powering the magnets, one that can be adjusted for various parameters such as power of the shot, and the mass of the shell. The gun starts with all of the magnets turned on, and then turns them off one by one before the shell reaches them. One advantage of the coilgun over the railgun is that it can be made arbitrarily long. This has a number of side effects, but the main one is that the acceleration can be much slower over a longer length, meaning that the power needed in any one section of a coilgun is much lower. However this advantage is offset by the cost and complexity of the switching system needed to supply a longer gun.
Electromagnetic (EM) railguns or coilguns, also known as Pulsed-Power EMguns, are expected to launch light projectiles(KE, up to 5 kg) with 30-60mmin diameter, at unprecedented hypervelocities between 4000-8000 m/sec (30-60MJ). Contrary to conventional SP guns, the EM pulse travels at near the speed oflight (@ 186K miles/sec) and thus provides propulsion means inherently immune to natural limits of gas expansion. At these extremely high velocities, EM guns are unsurpassed, being more efficient than any other type of existing gun. EM railguns operate on the sameprinciple as ‘linear’ electric motors. The barrel consists of two (or more?) highly conductive rails with the projectile positioned between the latter and enclosed in the leading bore. As high current is supplied to the rails, a strong magnetic field is created by the electric arc across the rails which accelerates the projectile down the barrel. Hypervelocities appear to improve the effectiveness of kinetic energy projectiles against some types of homogenized armor but may not do so against others. It increases with velocity against explosive reactive armour if the projectiles are segmented, but will not increase against a variety of complex composite armors. The benefit of hypervelocity projectiles is obvious against RHA, missiles, helicopters, and low flying ground support aircraft, but requires further development for full adaptation to antiarmor complex applications. Considerable size, low energy density, and a multitude of unresolved technical problems indicate that EM guns still have a long way to go before they could become practical enough to be incorporated as the main gun armament in a relatively small, highly mobile weapon system such as the FCS. Because of the high secrecy associated with outer-space military weapons applications, no recent information has been published nor released about EM guns and their applicability. Many in the research community believe that significant technical breakthroughs have been achieved over the last ten years, but havenot become public knowledge.
There are still fundamental issues that must be investigated, researched, and developed before EMguns could become a practical proposition, among them: 1) Material ablation effects due to extremely high friction with the atmosphere at hypervelocities could cause the projectile to burn unevenly,resulting in substantial degradation of its ballistic trajectory accuracy,velocity attenuation, and subsequent reductionin penetration effectiveness. Materials, demonstrating low ablation must also possess high mechanical strength(hard to find); 2) Interface repulsive force between the projectile and the accelerators(rails or coils) must be determined to quantify the critical implications in safety, structural integrity and launch reproducibility; 3) Selection of gun barrel material for overall weight reduction while maintaining adequate resistance to ablation and durability; 4) Accelerationsof 106 g’s produce previously unknown and unique material problems (e.g. vaporization) with critical implications for both lethality and accuracy. [At hypervelocities, materials behave like liquids, requiring the implementation of hydrodynamics, gas thermodynamics, and compressible fluid dynamics to representthe impact interaction between thepenetrator and its target]; and 5) Reductionof electrical equipment size (e.g capacitors, compulsators, and homopolar generators) and development of coaxial inductors and first-generation, barber repetitive opening switches operating atextremely high-current; 6)Railguns exhibit difficulty with initial acceleration.To avoid excessive heat and stress associated with the initial projectile launchphase, a method of gas-injected running startfor initial acceleration (up to practically1 km/sec), prior to the projectile entering the railgun breech, has been developed.This method introduces mechanical complexity and additional undesired logistic burden. Nevertheless, in spite of immense technical challenges, especially extensive pulse and power requirements for extremely short periods of time, and virtually nonexistent infrastructure, EM gun technology is the preferred long-term ultimate choice.
3.1.5) PLASMA IMPULSE GUNS:
Railguns and coilguns have been proposed, as these systems could provide much greater velocities and removed the need for dangerous explosive; but such systems require space-consuming generators and capacitors and have technical problem related to their mechanisms of action. A railgun is limited only by the amount of power available, but projectiles faster then 6000m/s would be seriously hindered by atmospheric friction, putting a upper limit on projectile speeds. An intermediate solution is the use of electrically-enhanced explosives or plasma impulse guns. They would use electricity to vaporize or even turn into plasma an inert or explosive liquid that would propel a bullet. One such type is the Plasma Thermal Gun (Shown below), which utilizes the electrothermal energy obtained from vaporizing a metallic material, creating a pressure wave of sufficient magnitude to cause a projectile to accelerate to ballistic velocities.
Fig.7. Schematic Diagram of the Plasma Thermal Gun.
Gas velocities and pressures much higher then conventional explosives could be achieved resulting in greater bullet velocities, inert liquids or less-combustible explosives could be used. An electrically-enhanced explosives cannon could achieve speeds of 3000m/s.
All the above weapon systems are still in their infancy; but its probable thaxt their drawbacks can be removed for their reliable use in the Future Comat Vehicles.

3.2) ARMOUR RESEARCH:
Undoubtedly, proper attacking and destructive potential, is one of the most essential requirement of a modern battle tank. But, a battle tank of a particular developed nation won’t be the only dominating weapons system on the battlefield.It will also have to encounter the threats from its opponents’ battle tank,more or less advanced in technology to the country. Thus, strong competition prevails in the battlefield. So, beyond having adequate firepower capability and proper fire control systems, upgradation of the protection levels of the tank is equally important for improved survivability aspects. This protection can only be provided by the tank armour.
Most of the modern armoured fighting vehicles are manufactured of hardened steel plate, or in some cases aluminium. These vehicles consist of the rolled homogeneous armour. Most armoured vehicles are best protected at the front, and their crews always strive to keep them pointed in the likeliest direction of the enemy. The thickest and best-sloped armour is on the glacis plate and the turret front. The sides have less armour and the rear and roof are least protected.Taking a glimpse to World War II,American Sherman tank crews found the German Tigers to be practically invulnerable from the front.But inspite of the good front protection,still today, tanks are vulnerable to specialised top-attack missile weapons and air attack.
In part to combat the threats of handheld anti-tank weapons and other advanced weapons system, as well as to investigate ways of maintaining protection levels while reducing weight, many countries,especiallyU.S. and U.K., are investigating a series of advanced armour technologies.Its light weight can increase strategic deployability by allowing two to three vehicles per cargo plane and increasing the number of vehicles, that can be transported by ship,rail or highway. Now-a-days, armours,besides being a protective shield of the tanks,are also thought to be the induced warriors of the modern battlefield, having the capability to fight against the dreadful anti-tank ammunitions and warheads. Most of the modern day battle tanks are equipped with Reactive armours, that react efficiently,in some way,to the impact of a weapon to reduce the damage done to the vehicle being protected. The most common type of reactive armour is by far Explosive Reactive Armor (ERA), but other types include Self-Limiting Explosive Reactive Armor (SLERA), Non-Energetic Reactive Armor (NERA), Non-Explosive Reactive Armor (NxRA), and electric reactive armor. Unlike ERA and SLERA, NERA and NxRA modules can withstand multiple hits, but a second hit in exactly the same location will still penetrate.So, basically all Reactive armours can be defeated with multiple hits in the same place, employed in tandem-charge weapons, which use two or more shaped charge explosions in rapid succession. ERA tiles are used as add-on armour to the most vulnerable portions of an armoured fighting vehicle, typically the front of the hull and the front and sides of the turret. They require fairly heavy armour on the vehicle itself, since the exploding ERA would otherwise damage the vehicle and injure or kill the personnel inside. Usually, ERA is not mounted on the sides or rear of a vehicle, since the underlying armour is not as heavy on those parts. Exploding ERA also poses a danger to friendly troops in close proximity to the vehicle. Though it was once quite common for a dozen or so infantrymen to ride on the outside of a tank's hull, this is not done with ERA-plated vehicles—for obvious reasons. Considering all the above disadvantages of the present day reactive armours, military scientists are recently trying for other alternatives . Thus, at present, research is going on to develop the following types of armour shields:
1.Electromagnetic Armour.
2.Electric Armour.
3.Active Armour.

3.2.1) ELECTROMAGNETIC ARMOUR:
This is a technology,still under development .Its used to defeat shaped charge warheads.The armour uses a massive magnetic charge to break apart and disperse shaped charge jets. One proposed system uses a sensor net of fibre optics, covering the vehicle. An impacting warhead will interrupt the flow of light through the fibre optics, registering a hit. An automated system registers the location and sends a signal to energise a powerful electric coil located behind the armour.The spiralling electrons in the coil give rise to an intense magnetic field that interacts with the particles within the shaped charge jet. Although shape charges generate enormous forces by travelling at up to 9 km/s, the stream maintains its penetrating power over a very short, and specific, distance. The magnetic field "pinches" the charge jet, making it unstable and dispersing its force so the warheads penetration power is significantly degraded. Figure below demonstrates the working of an electromagnetic armour.
Fig.8.Diagram showing the working of the electromagnetic armour.
Other proposals use a layered electrified armor underneath standard armour. Penetration of the armor by a shaped charge results in a massive discharge of electricity powered by a capacitor array in the tank. The electricity discharges into the incoming jet of explosive gas/plasma and this disrupts its flow and direction by adding extra heat and electric_charge. The electric discharge can also vaporize the molten metal used in some shape charges to increase penetration.
Using such systems could reduce main battle tanks from their current scale-tipping weight of 70 tons, down to a more manageable 20 tons, while providing superior protection. This would also have strategic implications. Current U.S. heavy armour divisions can take months to move from the continental United States to locations around the world. A lighter MBT could make deployment faster.
3.2.2) ELECTRIC ARMOUR:
Recent research has produced the idea of Electric Reactive Armour, where the armour is made up of two electrically charged plates separated by an insulator. When an incoming body penetrates the two plates and closes the circuit, a high current will flow through the penetrator, attempting to vaporize it, significantly reducing the resulting attack. It is not public knowledge whether this is supposed to function against both KE-penetrators and shaped charge jets, or only the latter. Rocket Propelled Grenades (RPGs) are the most prolific ground launched threat to British and Allied armoured fighting vehicles world-wide. To combat this very real and dangerous threat the Defence Science & Technology Laboratory, Dstl, has developed an 'Electric Armour' that reduces the effect of impacts by such projectiles to almost zero, and will ultimately save the lives of soldiers. Picture shown below demonstrtates the New Age Electric Armour - Tough enough to face modern threats.
Fig.9 Showing encountering power of the electric armour system.
Dstl scientists have developed a revolutionary Electric Armour system which can resist attack by RPGs or other shaped charge weapons whilst remaining of a practical weight and size for armoured vehicles to carry. A recently demonstrated system, consisting of bulletproof metal plating, insulation, power distribution lines, and storage capacitors weighs a mere couple of tonnes, but has a protective effect equal to carrying an extra 10-20 tonnes of steel armour. But this technology is still in its infancy and has not yet been introduced on any operational platform( battlefield).

3.2.3) ACTIVE ARMOUR SYSTEMS:
These systems are proposed to act more or less like the tank armament systems, thus adding great destructive potential to the battle tank. They form the sole warriors in the tank system, acting as the vehicle’s exoskeleton. They protect a tank or other armoured fighting vehicle from incoming fire before it hits the vehicle's armour. There are two general categories: soft kill systems, which use jamming to confuse a missile's guidance system, and hard kill systems, which attempt to detect and destroy incoming projectiles.
Active Protection Systems commonly consist of an array of soft- and hard-kill techniques. Soft-kill methods, similar to Electronic Counter-Measures (ECM) in aircraft, seduce and confuse an incoming missile, by using decoys, smoke and electro-optical signals, infrared or laser jamming. Other concepts which include "Hard-kill" means, are designed to intercept and destroy the incoming projectile or missile before it hits its target. Countermeasures include fragmentation charges, steel bars, high pressure shock waves that will destroy the threat, destabilize or disrupt it flight path, or divert it from its course. The optimal implementation of APS should be "design-dependent" thus, make it adaptable to tracked or a wheeled vehicle as well as fixed positions. Most of the currently available systems are, however, too heavy and are therefore suitable only for AFVs with weight class over 25 tons. (In photo - US Army M-1A1 equipped with the active protection system, in Iraq, 2003).

Fig.10 Showing Active Protection System on M1-A1 Abrams.

3.2.3.1) SOFT KILL SYSTEMS:
Soft kill systems were unsuccessfully deployed by Iraq in the Gulf War. These were essentially strobe lights fitted to Iraqi tanks, which misguided the guidance beacon on the back of a TOW missile. The multinational force was aware of their use, and adjusted the frequency of their guidance systems so they wouldn't be confused. Russia is the major contributor to the existence of this system. A soft kill system, currently in service, is the Russian Shtora, deployed on Russian and Ukrainian tanks. During the International Defense Exposition (IDEX) held in Abu Dhabi in 1995, the system was shown fitted to a Russian MBT. The first known application of the system is the Russian T-90 MBT that entered service in the Russian Army in 1993.
It is an electro-optical countermeasures suite, designed to disrupt the laser target designation and rangefinders of incoming ATGMs. It is an electro-optical jammer that jams the enemy's semiautomatic command to line of sight (SACLOS) antitank guided missiles, laser rangefinders and target designators. It is most effective when used in tandem with a hard kill system such as the Arena (active countermeasures system).
3.2.3.2) HARD KILL SYSTEMS:
Hard kill systems are activated when a millimetre-wavelength radar or other sensor detects an incoming projectile. In considerably less than a second they launch a counter-projectile in an attempt to physically damage or destroy the incoming round. In these systems also, Russia is a great contributor. Examples of the previously used systems include the TROPHY Active Protection System, Drozd, Arena and Zaslon.
One of the most important active hard kill systems prevalent today is the Arena Active Protection System (APS). It is an active countermeasure system developed at Russia's Kolomna-based Engineering Design Bureau to provide anti-missile defense for T-90 tanks. Arena was designed partly in response to vulnerabilities in T-80 and other tanks, discovered during fighting in Chechnya in the 1990s. It is intended to help protect a tank from light anti-tank weapons and ATGMs, including those with top-attack warheads.It uses millimeter-wavelength radar to detect timed to detonate immediately in front of the target.Different countries are trying to install these systems gradually, but most of them are limited by the huge cost of installation( roughly $300,000).
Future research should be aimed at not only the traditional survivability but also at the non-traditional survivability of the tank. In addition to ballistic protection of the tank, the armour should also be designed for good signature management and other related countermeasures.
3.3) POWER PLANT RESEARCH:
The battle tank’s power plant is a part of the power train, consisting of the tank propulsion system, transmission and steering system. The prime mover of the battle tank is the engine(also known as the power plant of the tank).The tank's power-plant supplies power for moving the tank and for other tank systems, such as rotating the turret or electrical power for a radio.
Tanks fielded in WWI all used petrol (gasoline) engines as power-plants. In the Second World War there was a mix of power-plant types used; a lot of tank engines were adapted aircraft engines. As the Cold War started, tanks had almost all switched over to using diesel, improved multi-fuel versions of which are still common. Starting in the late 1970s, turbine engines began to appear.
All modern non-turbine tanks use a diesel engine because diesel fuel is less flammable and more economical than petrol. Some Soviet tanks used the dark smoke of burning diesel as an advantage and could intentionally burn fuel in the exhaust to create smoke for cover. Modern tank engines are in some cases multi-fuel engines, which can operate on diesel, petrol or similar fuels. Gas turbine engines also have been used as an auxiliary power unit (APU) in some tanks.
3.3.1) EXAMPLES OF POWER PLANTS IN MODERN TANKS:
Gas turbine engines are the main power plant in the Soviet/Russian T-80 and U.S. M1 Abrams. The M1A2 was nicknamed “Whispering Death” for its quiet operation. T-80 was dubbed as the “Flying Tank” for its high speed. Some of the models of the M1 have a small secondary turbine engine as an APU to power the tank's systems while stationary, saving fuel by reducing the need to idle the main turbine. T-80 tanks are commonly seen with large external fuel tanks to extend their range. Russia has replaced T-80 production with the less powerful T-90 (based on the T-72), while Ukraine has developed the diesel-powered T-80UD and T-84 with nearly the power of the gas-turbine tank.
3.3.2) RELATIVE ADVANTAGES AND DISADVANTAGES OF THE
USED ENGINES:

Gas Turbines are comparatively lighter and smaller than diesel engines, at the same level of sustained power output (the T-80 was dubbed the Flying Tank for its high speed).However they are much less fuel efficient, especially at low RPMs, requiring larger fuel tanks to achieve the same combat range. Because of their lower efficiency, the thermal signature of a gas turbine is higher than a diesel engine at the same level of power output. On the other hand the acoustic signature of a tank with a muffled gas turbine can be quieter than a piston engine–powered one. A turbine is theoretically more reliable and easier to maintain than a piston-based engine, since it has a simpler construction with fewer moving parts. In practice, however, those parts experience a higher wear due to their higher working speeds. The turbine blades are also very sensitive to dust and fine sand, so that in desert operations special filters have to be carefully fitted and changed several times daily. An improperly fitted filter, or a single bullet or piece of shrapnel can render the filter useless, potentially damaging the engine. Piston engines also need well-maintained filters, but they are more resilient if the filter does fail.Like most modern diesel engines used in tanks, gas turbines are usually multi-fuel engines.

3.3.3) PROPOSED ALTERNATIVE PROPULSION SYSTEMS:
The turbine engine long ago supplanted piston engines in both military aircraft and ships, but whether it will be successful in tanks has yet to be seen. Miitary Researchers are now wanting to fulfill the requirement of the Future Combat System. They desire to significantly lessen the dependency on conventional fossil fuels, thus making the FCS more independent and capable of operating over long periods of time without resorting to periodic maintenance and logistical support. This requirement is extremely difficult to satisfy, and necessitates a dramatic departure from any conventional power sourcepresently in use. The FCS power pack is configured for an all-electric front drive installation. Electrical propulsion for mobility applicationsis widely recognized today as the wave of the future. Researchers are also proposing for reducing the thermal signatures as well as the acoustic signatures of battle tanks, which are not firmly established with diesel as well as gas turbines. Also, increased compactness is another requirement.
Many types of alternate power-plants such as fuel cells have been experimented with. One proposal is to use a diesel-electric or turbine-electric series-hybrid. These power plants would provide power by spinning a generator that would provide electricity to electric motors mounted inside the wheel hubs. In conjunctions with electric batteries or ultracapacitors for storing excess and recaptured energy such a system would be far more fuel efficient then traditional tank power plants while providing some advantages in maneuverability and performance. A system of this kind could be more rugged and damage sustaining with the use of multiple engine/generators and electric motors. Such a power plant could also provide electricity for energy weapons and defense systems like the ones mentioned above. Other types of power plants proposed are-
1.Solar Power Propulsion Plants.
2.Nuclear Power Propulsion Plants.
3.3.3.1) FUEL CELL PROPULSION SYSTEM:
A fuel cell is an electrochemical device similar to a battery, but differing from the latter in that it is designed for continuous replenishment of the reactants consumed; i.e. it produces electricity from an external fuel supply of hydrogen and oxygen as opposed to the limited internal energy storage capacity of a battery. Fuel cells are often considered to be very attractive in modern applications for their high efficiency and ideally emission-free use, in contrast to currently more common fuels such as methane or natural gas that generate carbon dioxide. The only by-product of a hydrogen fuel cell is water vapour.
Besides being applicable as useful power sources in remote locations, such as spacecraft, remote weather stations, military researchers have proposed these cells for use in certain military applications-including battle tanks, particularly because of the following military benefits: 1.A Fuel cell system running on hydrogen can be compact, light weight and have relatively few moving parts, which is required for improved maneuverability, 2.Endurance of the tank is enhanced as effective mileage is provided, 3.Quiter tank operation is provided, much needed advancing undetected by the enemy,with reduced acoustic signature, 4.Lower maintenance is required for the lack of moving parts, 5.Its practically a emission-free propulsion system, which is very much required for reducing the thermal signatures of the tank, 5.Reduced logistics are required.
Bernard I Robertson, Senior Vice President, Research and Regulatory Affairs has said, "This unique technology could have great benefits for the military: in particular, it is nonflammable, greatly improving safety in battle zones, and the main ingredient can be transported as a dry powder, dramatically reducing the enormous logistical demands of fueling our military in advanced battle settings. In addition, the greater fleet fuel efficiency would greatly reduce the amount of fuel used by our armed forces--fuel that can cost hundreds of dollars per gallon to deliver to the battlefield. And this technology produces zero smog-forming and greenhouse gases, contributing to a cleaner environment. Finally, sodium borohydride has the potential to reduce or eliminate our dependence on oil for our transportation needs." To cite an example, the U.S. armed forces have expressed interest in alternative-fuel vehicles in order to stretch the military's mobility into the future with improved fuel economy and range. Benefits include a decreased dependency on oil which significantly decreases cost of operation and increases the range and reach of individual task forces.
Supporting Special Forces during extended operations requires lots of power. Thirteen BA-5590 batteries weighing more than 29 lbs and costing $100 each are currently required to support a typical 72-hour deployment. The US Army is evaluating the use of inexpensive, injection-molded fuel cell technology formed into a common BA-5590 form factor, to power SOF PRC-117 field radio, resulting in a weight saving of over 13 lbs and decrease its cost by at least 50%. Figure below demonstrates the fuel cell power unit which is thought of to be installed in the tank.
Fig.11 Showing the Fuel Cell Power Unit.
But again, much frustrations have also taken place due to the use of these cells due to:
1. The hydrogen typically used as a Fuel is not a primary source of energy: it is only an energy carrier, and must be manufactured using energy from other sources. Some critics of the current stages of this technology argue that the energy needed to create the Fuel in the first place may reduce the ultimate energy efficiency of the system to below that of the most efficient gasoline internal-combustion engines. Thus, the fuel cells lack competition in this respect to the diesel engines also.
2. Because Fuel cells have a high cost per kilowatt, and because their efficiency drops with increasing power density, they are usually not considered for applications with high load variations. Large variations of load occur in battle tanks during normal conditions and also during war.Thus fuel cells are unable to provide sudden changes in load demand.
3. In particular, they are not suited for energy storage systems, unless weight is a major consideration. An electrolyzer and Fuel cell would return less than 50 percent of the input energy, while a much cheaper lead-acid battery might return about 90 percent.
4. There is concern, however, about the energy-consuming process of manufacturing the hydrogen, which may still generate pollution and still requires either fossil fuel, nuclear power generation, or as yet undeveloped alternative generation. In this regard, hydrogen fuel technology itself cannot be said to reduce fossil fuel dependence.
5. However, another environmental problem faced by all types of hydrogen fuel cells has been pointed out in a paper published in Science magazine by a group of Caltech scientists. They note that if hydrogen fuel cell usage becomes widespread enough to replace gasoline internal-combustion engines, small amounts of hydrogen leaking from storage containers and pipelines will have a detrimental impact on the Earth's ozone layer.
6. Finally, roughly 70% of all electricity produced in the United States comes from Coal. The problem is that coal is a relatively dirty energy source. If electrolysis (a process that uses electricity) is used to create hydrogen using energy from power plants, it is essentially creating hydrogen fuel from coal. Though the fuel cell itself will only emit heat and water as waste, the problem of pollution is still present at power plants.
Since the disadvantages of these cells in military use outnumber the advantages, researchers are discouraged to use these cells. They have realised that a better performance of the armoured fighting vehicles can occur from the hybrid(diesel and electric power sources combined) engine systems.
3.3.3.2) HYBRID ELECTRIC PROPULSION SYSTEM:
A number of land vehicles use a diesel-electric powerplant for providing locomotion. A diesel-electric powerplant includes a diesel-electric connected to an electrical generator, creating electricity that powers electric motors. The most well-known vehicle to use this technology is the locomotive, used for pulling or pushing trains. Diesel-electric powerplants have also been used in submarines and surface ships. Vehicles using a diesel-electric power system can be considered as a class of hybrid electric vehicles. Now they are also being proposed for use in military vehicles as well.
Defence Advanced Research Projects Agency (DARPA) is embarking upon anew venture to find a contractor teamable to inexpensively develop and demonstrate the capabilities of a highly-effective, Hybrid Electric Power System(HEPS) for generation and storage of electricity. HEPS is intended for automotive applications as a prime-mover in advanced combat vehicles (FCS and the Future Scout Cavalry System - FSCS).In essence, HEPS is comprised of a diesel engine or gas turbine directly coupled to generators to produce electrical energy for storage and subsequent use by the vehicle systems.DARPA has announced its intention to invest more than $40 M(!) to develop and test the HEPS over the coming few years.
A Hybrid Electric Drive, an 8x8 wheeled vehicle has been demonstrated following several years of field testing, accumulating over 4,200 km of road and cross-country testing.(Picture shown below).
Fig.12 Showing the interior installation of the hybrid system.
A first hybrid-electric tracked armored vehicle(Shown below),developed by the U.S. Army’s National Automotive Center and BAE Systems (formerly United Defense) was the hybrid-drive 15-ton M-113 prototype. The vehicle's battery power was used to provide transient power needs, on acceleration, steering and climbing. When stationary, the vehicle can generate about 200 kilowatts of electricity and function as an auxiliary power unit.
Fig.13 Showing the first tracked vehicle with hybrid engine.
Competing teams will develop and demonstrate an integrated HEPS for a 15-ton vehicle (e.g. FSCS), but they will also be required to demonstrate, by computer simulation and computer virtual modeling, that a more powerful version of the HEPS could be integrated into a 40-ton vehicle (e.g., FCS). Nonetheless, though same basic technology could be used to power the FCS, it is not in accordance with the requirement for simplified and reduced logistics. Integrated HEPS are more efficient, and have improved performance compared to contemporary diesels or turbine-based power packs. The internal combustion engine in a hybrid type is much smaller, lighter and more efficient than the one used in a conventional tank, because the engine can be designed for an average power demand only, rather than peak power demand. Also with proper regenerative braking, much of the kinetic energy is conserved, which helps the motor to charge the battery. Thus, these engines have better efficiency in stop and go missions, although less in long duty periods. The advantage is that the electric motors get the better storage capacity for offroad maneuverability- in gradients especially when too much mechanical stresses can be induced in conventional diesel power plants. Thus frequent charging of the battery from outside is eliminated. They operate with less noise and with reduced thermal signature, thus improving survivability. With hot noisy diesel engines turned off, the batteries, ultracapacitors or fuel cells of hybrid provide silent watch power in stationary tanks to avoid detection. These engines can provide stealthy sources of power for battlefield sensors, weapons, command and fire control systems, laser range finders, etc. Thus, they provide exportable power to run other equipments. It has been estimated by the United States that the hybrid electric wheeled Future Combat System can travel at the rate of 5 miles per hour for about 30 minutes, using electric power only. A hybrid electric version of the MII3 APC created by United Defence L.P. outperformed the conventional M113 in many areas, in an experimental setting. Thus they provide exportable power to run other equipments. According to the Defence Science Board, fuel takes up about 70% of the total logistic burden tonnage in an armoured fighting division. The Army expects that the hybrid-electric Future Combat System is likely to reduce the fuel consumption by about 75%.
It remains to be seen whether integrated HEPS will come out less costly in production and deployment than contemporary power packs. Attempting to capture the best of two worlds, HEPS seem to be more applicable, as a near-term solution, to the lighter FSCS and similar vehicles, though less so for the longer-term, heavier FCS. Currently no battle tank uses this principle for movement, but it's quite appropriate to train the turret and/or guns with electric motors powered by diesel or turbine APUs.
The only problem, HEPS is still going to require diesel or turbine fuel for its operation, and would add a piston engine or a gas turbine, in addition to a sophisticated electrical power generating system, to worry about.

3.3.3.3) SOLAR POWER PROPULSION SYSTEM:
Its been pondered as a possible long term energy source solution for the Future Combat System.
Solar energy is considered by many as an ideal energy source. It is clean; it produces no pollution and there are none of the nuclear residual radioactive wastes that make nuclear energy so unpopular in the public eye. It is practically unlimited, so it will still exist in abundance long after fossil fuel reserves become scarce, sometime during the next century. And best of all, solar energy is free,short of the cost of harnessing it for humanconsumption. A Solar Power Satellite System(SPS) is placed in a geostationary orbit (36,000 km) above the equator,similar to the orbit being used for communication satellites. The SPS is so positioned in space that it revolves at the same rate as the Earth spins, being relatively fixed to the equator, and can intercept at least four times as much solar energy as the sunniest spot on Earth. The SPS intercepts unobstructed sunlight (noclouds, bad weather, or darkness inspace), converts it into microwaves(short-wavelength radio waves) and beams them back to collector arrays on Earth where they could be convertedwith high efficiency into electricity.

Fig.14 Showing a photovoltaic cell, which make up the solar panel in the SPSS.
Depending on its size, the SPS could deliver thousands of millions of watts, practically in a continuous manner. DOE concluded that it was feasible to construct a fleet of 60 solar power satellites, the first of which will be in operation in 2010 and the last by 2040.A SPS could reach a mass of about 50,000 tons, but it is weightless in space.Solar cell arrangement is preferred, becausethere are no moving parts to malfunction,and the use of solar cells in space is already well established. Solar cells, made of silicon (or gallium arsenide forbetter efficiency) convert sunlight directlyinto electricity. Remotely-controlled and operated ‘space robots’ could construct the lightweight structures which support the array of solar cells. Whether the SPS uses turbines or solar cells, the electricity generated will be converted into microwaves by devices known as Amplitrons (also Klystrons) and then beamed to Earth at an area of limited diameter. At a wavelength of 10cm (2450 MHz) this type of microwave radiation passes through the atmosphere virtually unabsorbed. At the ground, receiving arrays termed Rectennas, installed on the FCS as shown, will collect the microwaves to convert them very efficiently (83+ %) into electricity. The rectennas will consist of panels studded with T-shaped aerials linked to rectifying devices known as Schottky barrier diodes, which convert the microwave beam back into electricity. Picture below demonstrates the use of the Rectennas in powering other devices.
Fig.15 Showing the mode of use of the solar collectors, installed on the battle tank.
One of the arguements against beaming power to Earth is that microwave beam radiation might damage humans. This problem could be mitigated by using a beam that is stronger in the center, but it must be very accurate. The accuracy of beaming could be much improved with the aid of the Global Positioning System (GPS), which is also satellite-based. Any realistic assessmentof the dangers of power satellites must be balanced against the pollution from fossil fuels, and the waste from nuclear reactors. The SPS concept may resemble “StarWars” and frontier-of-science type of technology, but successful and promising experiments have been conducted in the past that validated the feasibility of such an idea. Using its Global PositioningSystem (GPS), each individual FCS could identify its definite location so that it could receive the transmission with high accuracy and, better yet, while on the move. Once the transmitted energy has been absorbed by the FCS, it will be converted into electrical energy and stored in high-density energy to the various “consumers” (EMgun, fire control system, laser gun, prime-mover, etc.). The FCS could also receive electrical energy from a dedicated “refueling” vehicle (generator) and by physical connection to another FCS that could share some of its own electrical energy. Admittedly, there is a vast array of problems yet to be solved in order to harness this type of energy source for automotive applications. To mention just a few :- The rectennas on the FCS must be small to accommodate its limited size, and still be efficient. The safety hazard of exposure to microwave radiation must be eliminated or reduced to controllable and acceptablelevels. Radio noise disruption over a wide range of frequencies, and detrimental ionospheric and atmospheric effects, must be mitigated. The beaming process must be sufficiently accurate to hit a single FCS, or a group of them, in a pre-planned rendezvous location, and recharge them within a reasonable duration. The high efficiency of microwave power transmission and reception is crucial to the economics of placing the SPS in space for practical military applications. In conclusion, the authors realize that one may challenge the feasibility and practicality of such an approach to their fueling problem. It stands to reason that, if we are to be independent from conventional fossil fuels, we must use a different source of energy.
3.3.3.4) NUCLEAR ENERGY PROPULSION SYSTEM:
Nuclear energy is also conceived of as a prime-mover energy source. The energy produced by a nuclear reactor is released by the fission of atomic nuclei in a controlled and self sustaining manner, and appears as heat, which is then converted to electrical energy by using conventional turbine generators.As an example, the Fast BreederReactor2 (FBR) now under active development, uses fast neutrons produced by fission without slowing them down, such as in a conventional Thermal Reactor(TR). The fuel used has a higher concentration of fissile material (plutonium-239and uranium-235) with the high concentration resulting in a much smaller core. Molten sodium or high-pressure helium are used as coolants. In essence, the FBR generates more fuel than it burns, so it could continuously operate for extended periods of time. By processing the burned fuel, it is possible to use up to 60 pecent and more of the energy stored in the uranium, as opposed to just a few percent with thermal reactors. The energy potentially available from the fissioning of uranium and thorium in FBRs is at least a few orders of magnitude greater than that of all fossil fuels sources combined. The emergence of nuclear power as aviable energy source for automotive military applications comes at a time when additional environmentally acceptable sources of energy for civil and military consumption are sorely needed to meet continued rapid increases in demand Despite its undeniable potential, the authors decided to reject this alternative up front on both environmental and political grounds. It is primarily because of the inherent difficulties and safety hazards involved in dealing with radioactive radiation in peacetime, accidents and war, demilitarization problems associated with discarding radioactive products and radioactive residual materials. Furthermore, there are insurmountable difficulties in cooling the nuclear reactor and ‘purifying’ the working liquid when the only available coolant in abundance is ambient air (a poor heat conductive substancewith a much lower heat transferefficiency than water), rather than the unlimited sea water supply commonly used in submersible and surface naval applications. The reactor under armor must be ruggedized, and the control rods— which regulate the speed of reaction— must be stabilized to account for the jagged motion over typical cross-country terrain. In addition, the nuclear reactor and its auxiliaries — its insulation, cooling, pumps, controls, monitoring and redundant safety devices — must all be made inexpensive to produce in order to make any economical sense. Present commercial and military nuclear applications are considered unpopular because they contradict the current trend towards diminishing civil nuclear applications, and in particular, the trend toward banning the proliferation of nuclear weapons.
This option may be regarded as feasible if there was a safe, practical, and economical way to neutralize radioactive radiation and demilitarize residual nuclear materials while preserving the natural environment. The above systems bear a disadvantage with respect to installation in a tank. But the researchers have realized that even a more potent synthetic fuel is not going to provide the desired level of independence from the burden of the logistical “umbilical cord”. Compact, reliable, and economical diesel engines have probably reached their peak performance. Turbocharging, recuperation, intercooling, high-temperature resistant materials (e.g. ceramics) and combustion control, in addition to some emerging technologies like variable compression ratio piston engines, adiabatic engines, employing ceramic liners and compound engines, have all contributed to their performance with limited progressive improvements yet to be expected. One way or another, this particular problem of using the alternative sources of power must be addressed sometime in the course of the next century, when fossil fuel reserves become scarce.

3.4) STEALTH RESEARCH:
A battle tank is an offensive weapons system, which has to progress aggressively in the battlefield. So adequate protection facilities are provided and some are being developed to be used in future. But because of the advancement of technology in various countries with regard to the armoured protection systems, its not always possible to save the disability of the tank from the powerful armour piercing weapon systems,now being developed. Thus, besides protection, sometimes hiding of the tank is also required in the battlefield to the maximum extent in order to cheat the enemy detection systems. Most armoured vehicles carry smoke grenade launchers which can rapidly deploy a smoke screen to visually shield a withdrawal from an enemy ambush or attack. The smoke screen is very rarely used offensively, since attacking through it blocks the attacker's vision and gives the enemy an early indication of impending attack. Some smoke grenades are designed to make a very dense cloud capable of blocking the laser beams of enemy target designators or range finders and of course obscuring vision, reducing probability of a hit from visually aimed weapons, especially low speed weapons, such as antitank missiles which require the operator to keep the tank in sight for a relatively long period of time. But the installation of these grenades affect the health of the moving infantry, thus reducing their working capabilities.Thus, such smoke grenades are not used for hiding purposes. Modern technologies, which supports the tank to move through the field in a hidden manner, is known as Stealth Technology.
The concept of stealth itself is not new. Being able to operate without the knowledge of the enemy has always been a goal of military technology and techniques. It covers a wide range of techniques, initially and now often used with aircraft, ships and missiles, in order to make them less visible (ideally invisible) to radar and other detection methods.Radar avoidance technology was first used on a large scale during the Gulf War in 1991. However, F-117A Stealth Fighters were used for the first time in combat during Operation Just Cause in 1989. Since then it has become less effective due to developments in the algorithms used to process the data received by radars, such as Bayesian particle filter methods.
Thus, we see that the concept of stealth has been developed in the fields of air-defence and in ships also. But no such concept has yet been undertaken in the combat field, except in a few armoured personal carriers. Its typically very tough to hide such a big metal block of tank in the moving condition, though some success has occurred during the time when the tank is stationary. Military researchers are now trying to follow the methods for activating stealth to the maximum possible extent in combat enviroment by using the methods of stealth, used in air-defence and in navy. So in order to realise the techniques of hiding the tank, we have to first take a glimpse as how this technology is used in the Air Force.

3.4.1) STEALTH METHODOLOGY IN AIRCRAFTS:

A stealth aircraft is an aircraft which has been designed to absorb and deflect radar signals;these are not completely "invisible" to radar, they are simply harder to detect than conventional technology. In general the goal is to allow a stealth aircraft to execute its attack while still outside the ability of the opposing system's detection. In this context, it can be seen that the tremendous supersonic velocities of most of the fighter jets also gives an added advantage to the non-detectability. Stealth aircraft were most notably used during the Gulf War (1991). To cite a few examples of these stealth aircrafts,first-generation stealth aircraft include the F-117 Nighthawk. Second-generation aircraft include the B-2 Spirit and F-22 Raptor.

The Lockheed F-117A Stealth fighter was the world’s first operational combat aircraft designed to exploit the stealth technology with its unusual shape (Picture shown below).

Fig.17 Showing the world’s first combat aircraft.

If the shape of the external structure of the aircraft is curved, then they have the maximum possibility of reflecting the radar waves towards the radar direction(Picture shown below-Fig.18). In general, the main method, used by stealth crafts to avoid detection,is by using a body shape that deflects radar signals in a direction roughly perpendicular from the radar signals origin, rather than reflecting the signal back to enemy radar sensors (Picture shown below- Fig.19).

Fig.18 Showing the shape of the conventional aircrafts and their detection.


Fig.19 Showing the shape of the stealth aircrafts and their non-detectability.

To a lesser extent, they also use a covering of some type of radar absorbing material. Stealth aircraft are also harder to detect and track via other methods:
1.The normally hot exhaust is cooled by ambient air before leaving the aircraft and partially shielded from below, as a result the infrared signature of stealth aircraft is minimized.
2.Stealth aircraft are painted in dark colors and typically fly at night to make visual identification more difficult.
3.Stealth aircraft are not supersonic, they have no afterburners, and the exhaust nozzles are tuned for low noise rather than peak performance, making them difficult to detect via sound waves.
Application of Stealth Technology in tanks have similarity with that in aircrafts, as both vehicles try to reduce the radar cross section as much as possible. The various ways, applicable to aircrafts, to reduce the radar cross section are:
a) Vehicle shape: It has been known since at least the 1960s that aircraft shape makes a very significant difference in how well an aircraft can be detected by a radar. Another important factor is the internal construction; behind the aircraft skin there is a special structure known as re-entrant triangles. Radar waves penetrating the skin of the aircraft get trapped in this structure, bouncing off its internal faces and losing energy. The vertical and horizontal components of the tail of any conventional craft is set at right angles, which facilitate more radar detection. Stealth aircrafts are arranged in a different manner. Here the vertical component of the tail is set at an angle; in some cases no tail is provided at all. As well as altering the tail, stealth design must bury the engines within the wing or fuselage, or in some cases where stealth is applied to an existing aircraft, install baffles in the air intakes, so that the turbine blades are not visible to radar. The shape of the aircraft must be devoid of complex bumps or protrusions of any kind if it is to be stealthy. This means that all weapons, fuel tanks, and other stores may not be carried on under wing pylons but must be stored internally.
b) Use of non-metallic materials: Nonmetallic components, such as composites may be used for the airframe. The composites used, often contain high amount of ferrites as filling. Composites are transparent to radar, whereas metals reflect waves back to the radar transmitter if the metal happens to be perpendicular to the radar.But certain alloys are there which reflect less electromagnetic radiation than others.
c) Use of Radar absorbing paint: RAM (Radar Absorbent Material) coating may be used especially on the edges of metal surfaces. The RAM coating, known also as "iron ball" paint, contains tiny spheres coated with carbonyl iron ferrite. Radar waves induce alternating magnetic field in this material, which leads to conversion of their energy into heat. Early versions of F-117A planes were covered with neoprene-like tiles with ferrite grains embedded in the polymer matrix, current models have RAM paint applied directly. The aircraft must be painted by robots, because the solvent used is highly toxic.
d) Reducing signatures: Aircraft signatures include infra-red, visible, and accoustis ones. Stealth aircraft need to stay subsonic to avoid being tracked by sonic boom. Some early stealth observation aircraft utilised very slow-turning propellers in order to be able to orbit above enemy troops without being heard. Most stealth aircraft use matte paint and dark colors, and operate only at night. The primary means of reducing the infrared signature is generally to have a non-circular tail pipe (a slit shape) in order to minimise the exhaust area and maximise the mixing of the hot exhaust with cool ambient air. Often, cool air is deliberately injected into the exhaust flow to boost this process. Sometimes, the jet exhaust is vented above the wing surface in order to shield it from observers below.
e) Reducing radar emissions: Infrared emissions and sound aren't the only detectable means on ships or aircraft. The stealth vehicle must not radiate any energy which can be detected by the enemy, such as that of a height finding radar, terrain following radar or search radar. The F-117 uses a passive infra-red system to navigate and the F-22 has an advanced Low Probability of Interception (LPI) radar which can illuminate enemy aircraft without triggering a radar warning receiver response.
f) Plasma stealth is another proposed process that uses ionized gas to reduce the radar cross section (RCS) of an aircraft. Interactions between EM radiation and ionized gas have been extensively studied for a variety of purposes, including the possible concealment of aircraft from radar that plasma stealth theorizes. While the theoretical possibility of reducing an aircraft's RCS by wrapping the airframe in ionized gas flow is not in question, the technological aspects of applying such methods represent considerable challenges. There are many possible means of accomplishing this effect, running from "simple" electrostatic discharges to complex and power-hungry plasma lasers. The Journal of Electronic Defense reported that "plasma-cloud-generation technology for stealth applications" developed in Russia reduces an aircraft's RCS by a factor of 100.
Sukhoi Design Bureau is the main competitor-colleague of Mikoyan-Gurevich Design Bureau. The Bureau was able to create, develop, build, and start testing of the 5th generation fighter in just 10 years comparing to MFIs long 15 years. This aircraft is called S-37 Berkut [Ber-koot]( Picture shown below). The configuration of forward-swept wings combined with canard wings, can be compared to the American X-29. This configuration makes the aircraft more stealthier and maneuverable. The aircraft was designed in such a manner so as to get its stealth capability from the electro - magnetic plasma field around the aircraft. This technology is one of the most closely guarded secrets of the Russian Airforce, at present. N

Fig.20 Showing the aircraft based on plasma stealth.
A number of methodologies to detect stealth aircraft at long range have been developed. Both Australia and Russia have announced that they have developed processing techniques that allow them to detect the turbulence of aircraft at reasonably long ranges (possibly negating the stealth technology).
Passive (multistatic) radars are known to detect stealth aircraft better than receivers connected to the transmitters (active or monostatic radars). In addition, it has been suggested that use of low frequency broadcast TV and FM radio signals as the illuminating source produces a much higher RCS than high frequency monostatic radars as the long wavelengths cause whole structural portions of the targets to resonate. Researchers at the University of Illinois with support of DARPA, have shown that it is possible to build a synthetic aperture radar image of an aircraft target using passive multistatic radar, possibly detailed enough to enable Automatic Target Recognition (ATR).The United Kingdom has announced a system that uses the signals broadcast from the huge number of cellular telephone towers to generate a synthetic picture, although it is not clear if this method is actually practical. Stealth aircraft can also be passively detected from their electromagnetic emissions (terrain-following radar, radio communications, missile guidance communications etc.). Stealth aircraft typically attempt to minimize these emissions (using low probability of intercept radars, satellite communications etc.). The problem of successfully countering stealth aircraft on the battlefield remains essentially unsolved. Although stealth technology has since become less effective, the United States continues to develop stealth aircraft.
Stealth Technology is also applied in naval field. Ships, which employs stealth technology, are constructed in an effort to ensure that it cannot or can hardly be detected by radar. These techniques borrow heavily from stealth aircraft technology, though there are some aspects, such as wake reduction, that are unique to their design.
3.4.2) APPLICABILITY OF STEALTH TECHNOLOGY IN BATTLE TANKS:
Undoubtedly, the size and weight of any battle tank is much more than that of any aircraft. Therefore, hiding the tank from enemy detection system is not a matter of simple research, as tanks always present a bigger target before the enemy than aircrafts. With the urgest need of hiding themselves to suit the modern day conflicts, tanks have been the focus of speculation as to what role and changes they will have. Some have suggested that given the unconventional warfare, that is likely to be seen in the future, more agile tanks are likely to be seen even, if some non-detectable technologies are used. The stealth technology, applied to tanks, is similar to the one used in stealth aircraft,making the tank nearly invisible to enemy radar, by absorbing rather than reflecting radar beams. Some of the radar absorbing materials and paints may be coated on the surface of the armour of the tanks for absorbing the radar signals. A further modification that makes this harder to detect is to give stealth tanks a special color, such as orange, which camouflages it with the desert sands. Non-detectability is also possible by active camouflage. Active camouflage (or adaptive camouflage) is a group of camouflage technologies which would allow an object (usually military in nature) to blend into its surroundings by use of panels or coatings capable of changing color or luminosity. Active camouflage can be seen as having the potential to become the perfection of the art of camouflaging things from visual detection. Theoretically, active camouflage should differ from more conventional means of concealment in two important ways. First but less importantly it should replace the appearance of what is being masked with an appearance that is not simply similar to the surroundings (like in conventional camouflage) but with an exact representation of what is behind the masked object. Second and more importantly, active camouflage should also do so in real time. Ideally active camoflage would not only mimic nearby objects but also distant ones, potentially as far as the horizon, creating perfect visual concealment. In principle, the effect should be similar to looking through a pane of glass making that which is hidden perfectly invisible. This technology is poised to develop at a rapid pace, with the development of organic light-emitting diodes (OLEDs) and other technologies which allow for images to be projected from oddly-shaped surfaces. With the addition of a camera, while not allowing an object to be made completely invisible, theoretically the object might project enough of the background to fool the ability of the human eye or other optical sensors to detect a specific location. As motion would still be noticeable, an object would merely be more difficult to hit, and not undetectable under this circumstance.
But "Stealth Technology" redesigns the vehicle itself to dramatically reduce its observability. The British Researchers have proposed that a stealth tank prototype should have a low center of gravity and should almost crawl on the ground to avoid detection. By virtue of its light weight and size it should be more of a scout vehicle than a main battle tank though.Other invisible tanks that blend into the visual environment by controlling luminosity via the use of flares and diodes are in conceptual stages in the US and UK military. Such a tank would not only be very difficult for the radar to pick up but also for the naked human eye.

Other ideas of a stealth tank have been provided by researchers. Tanks have very noisy heavy armour and smoky diesel engines running loud. If instead of conventional diesel engines, if battery stores are added, to help propulsion of the tanks, then a much quiter operation can be obtained. The batteries once charged, will provide power to much quieter and environmentally friendly electric engines for temporary periods, thus allowing tanks to travel with less chance of detection by the enemy. It has been found that this would be rather useless in flat terrain as deserts or plains, but in areas where the terrain would allow for some cover(woodslands, semi-mountainous regions and the like) the tanks could more easily avoid detection This battery can be charged while the engines are running or through blankets of solar panels installed on the vehicle,during vehicles down time. Potential shortcomings are effected while using electric engines, such as: 1)battery life maybe insuffient to sustain "stealth mode" for prolonged periods. 2)electric engine output would be inferior to diesel, so "stealth mode" would be slower. 3)power generated from primary engines to charge the batteries may drain valuable electricity needed to power targeting and navigation systems.
Stealth can also be provided by a well designed suspension system. An alternative propulsion system, such as four tires on an adjustable suspension which could be lowered down and support the tank instead of the treads, would remove additional noise caused by the creaking treads.
Researchers have also forecasted that stealth would be better effected by employing solar-powered tanks, on which research is going on as mentioned earlier. Giat Industries of France has revealed that several years ago it developed and produced the prototype of a stealth vehicle based on its AMX-30 main battle tank (MBT) (Picture shown below). The project was funded by France's Delegation Generale Armement (DGA) defence procurement agency.

Fig.21 Showing AMX-3O Stealth tank.
Experiments were conducted with an AMX-30 main battle tank whose turret and chassis were enclosed in a Ram covering shaped to reduce the radar cross section, by the methods used for aircrafts, more or less. Also, cold air was pumped between the covering and the hull in order to minimise the vehicle’s IR signature.
Still some researchers believe that this technology might prove useless because a silent running tank moving through open terrain can easily be spotted by it's profile or dust trail from miles around is why I said it would be useless. True, tanks aren't known for their subtley but they have been used in ambushes (which have very high requirements on subtley) against other armour in the past, being able to move silently would insure their chance to move into position for an ambush without the enemy knowing. I would have thought that the sheer size of a tank would make subtlety futile in most situations. Maneuvering even a silent tank in a woodland area is sure to cause one hell of a lot of branches breaking, which in turn creates the noise that one wants to avoid. The output power of the Stealth Electric Power vehicles is only 100Kw, or roughly 134 HP.Obviously, these vehicles are not very heavily armored, and not very fast. So the idea isn't practical for heavy armor yet. The army is currently working on armored vehicles with electric drive, but this is not necessarily for stealth purposes. But , according to the researchers, if this idea is given a decade or so and the technologic advances in battery life, energy output and engine efficiency may even allow the electric engines to surpass current conventional engines, providing good stealth technics. The researchers have thought of a Future Combat System, involving this technology.(Picture given below)

Fig.22 Showing the stealthy based Future Combat System.

The Future Combat System-Tracked prototype will deliver superior survivability through a lightweight composite structure, modular armors, signature control and a survivability suite. It will be highly mobile in all terrains with a reduced logistics burden due to its fuel-efficient hybrid-electric drive, hydropneumatic suspension and band track. The platform allows the user to operate in one of three modes (hybrid, engine-only or battery-only) to provide superior mobility and silent operations. The FCS-T's engine will drive a 300-KW generator to provide high-power, high-speed operation of the vehicle. It will also work in conjunction with batteries, which may be used on their own without the engine runningto power other systems and accessories on the vehicle during silent watch or slow-moving stealth operations. Current prototypes like the British stealth tank prototype, developed alone as the TRACER when the U.S. dropped out of its FSCS part of the project, have pointed out that the future of tanks lies in invisibility rather than invincibility as modern missiles can penetrate any tank's defence.


4) OTHER MISCELLINEOUS RESEARCH ACTIVITIES:
There are some of the additional research activities going on in other fields of interest, such as in tank transmission systems, suspension systems as well as improvement in operating conditions of the night vision devices. Thus, the following activities, noteworthy of mentioning, are-
4.1) MICROPROCESSOR BASED STEERING CONTROL OF TANKS :
The propulsion system is one of the most important limbs of the battle tank. The propulsion includes engine, transmission and steering systems. The driver of the tank has got the control for all these. The steering of high speed track layers is accomplished by applying controlled speed differences between the tracks. It’s a notoriously brutal technique, for which a number of mechanisms have been developed.
When the tank is given an angular motion, every part of the track must rotate about a vertical axis, with the same angular velocity as the tank, thus skidding over the surface. The driver, therefore has to apply a couple, necessary to overcome the resistance to slewing , with the help of the steering mechanism. Resistance to slewing, being large, the effort applied by the driver is also considerable. It causes fatigue to the driver, which will be more intense while driving on a highway, through built-up areas or in deserts, where the resistance to slewing is still higher. Thus, better capability to change speed and direction simultaneously- in other words, significantly better acceleration and deceleration capabilities and improved steering are major parameters for maneuverability. In present tactical scenario, a tank may have to continue advancing and fighting for 72 hours at a stretch. It is,therefore, a requirement to make the drivers’ control as easy as possible to enable him to sustain the stress and strain for a long time. The latest trend to go in favour of a smaller crew in order to reduce the bulk of the tank, has a disadvantage of putting extra work on the rest of the crew in terms of observation and scanning of the battlefield. The driver also cannot contribute maximum to this if he is too busy with his controls.
The microprocessors, though may be a source of complexity and costly, can help in reducing the driver’s effort considerably by making the steering control easier and transmission semiautomatic or automatic. It is certainly true that for some tasks, electric systems out perform human operators- their reaction time is fast, their attention does not wander and they can perform complex mathematical computations that would battle most soldiers. Thus, microprocessors can be used alone in a very competitive arena of armoured combat. It is most persuasive to the designers of military vehicles for reduction in crew workloads. The microprocessor contols different operations with the help of a hardware and a software. The hardware consists of
a)A microprocessor.
b)Two sensors for sensing the positions of the steering sticks and converting them into digital output.
c)Two comparators and one sensor for sensing the engine speed and comparing them with prefixed values.
d)Three stepped motors with drive units for controlling valves.
e)Choice of AUTO/MANUAL mode.
The software involves:
a)Getting digital equivalent as input from steering sticks.
b)Rotating the stepper motors as per the input.
c)Readjusting the stepper motor for any variation in input, if any.
d)After being interrupted by lower limit or upper limit of engine speed, shifting gear range accordingly and displaying the number engaged.
e)Ensuring that no upshift is there beyond seventh gear, auto-downshift below neutral and downshift below reverse.
Thus, the microprocessor system selects an optimum speed range for a particular radius of turn automatically.
Other miscellineous research activities are inclined to the areas of tank suspension and navigation systems and also in fields, related to the improvedworking of the night vision devices.
4.2) RESEARCH ON ELECTROMAGNETIC SUSPENSION SYSTEM:
So far emphasis has been laid on passive suspension design for military vehicles. This was the only system in production uptil now. Now, attempts have been made to nvestigate the possibilities of incorporating a suspension, whose characteristics, instead of remaining fixed under all circumstances,can be altered under all prevailing conditions. This optimizes the ride. Such suspensionsystems are known as 'active systems'. A number of research vehicles have undergone demonstration. One such important approach may be accomplished by the use of electromagnetic suspension systems. These systems owned the combination of speed, strength and lectromagnetic efficiency. But, the installation of these systems require significant advances in four key disciplines: linear electromagnetic motors, power amplifiers, control algorithms and computation speed. A linear electromagnetic motor can be installed at each roadwheel of the track. The motor consists of magnets and coils of wire. When electrical power is applied to the coils, the motor can retract and extend, causing relative motion between the tank body and wheel. This reduces the jerk of the crews. A power amplifier can be used to supply electricity to the motor in response to signals from the control algorithms. These control algorithms can operate by observing sensor measurements, taken from around the tank vetronics. Then these algorithms send commands to the power amplifiers installed in each corner of the vehicle. Whenever the suspension encounters any obstruction, power is used to extend the motor and isolate the vehicle occupants from the disturbance. On the far side of the obstruction the motor operates as a generator and returns back the power to the amplifier. Thus this suspension requires less than half the power of an air-conditioning system installed in the tank. Thus, this system facilitates driving of the tank on all terrains smoothly, maintaining both control and crew comfort.

4.3) RESEARCH ON DIRECT PROPULSION LASER GUNS:
One of the most lethal weapon systems on the modern battlefield, is the laser. Researchers have pondered over the Future Combat System(FCS) to be equipped with a high-power, extremely accurate,fully-stabilized laser gun. Even low-power lasers with only a few milliwatts of output power can be hazardous to a person's eyesight. At wavelengths which the cornea and the lens can focus well, the coherence and low divergence of Laser Light means that it can be focused by the eye into an extremely small spot on the retina, resulting in localised burning and permanent damage in seconds or even faster. As the FCS is visualised as an ‘all-electric’ vehicle, it was also forecasted that the operation of a laser gun can be facilitated against a variety of close-in threats- helicopters,drones, ground ‘soft’ targets and infantry.The FCS laser gun application will probably represent a tremendous step towards independence from logistic support. There is no need for frequent ammunition resupply since it will be ‘firing’ variable,high-energy short pulses (bursts) ofconverted electrical energy. During target acquisition, a low-energy laser beam will be pointed at the target toverify ‘on-target’ position and the corresponding effective range. Subsequently, the low-energy beam will be substituted with a short, high- energypulse, ultimately yielding target destruction.
A case in point is the USAF’s High-Energy Chemical-Oxygen Airborne Laser(ABL), currently being developed to destroy ballistic missiles early in their boost phase of flight, immediately following their launch phase. A full power prototype baseline configuration laser module in the hundreds of kilowatts class has already been demonstrated to meet stringent performance requirements. Another notable program is the U.S.-Israeli Tactical High-EnergyLaser (THEL), developed to engage and destroy incoming missiles. Though chemical laser technology is considered mature, a compact and transportable tactical laser weapon system, well integrated into a smaller mobile armored vehicle, remains to be demonstrated. Typical outstanding issues are integrationof optics, energy pressurization system, radar, and command & control. To facilitate its development, the U.S.Army is already leveraging technology from the USAF’s space-based laser program. These developments and similar projects imply that future ‘spin-off’ versions, on a much smaller scale, could be implemented in various, armored ground-to-ground and ground to-air offensive weapons and active self-defense applications. The high power, direct line-of-sight (LOS) laser beam must have the ability to travel through the atmosphere at tactical operational ranges (10-15 km) without detrimental losses from beam spreading, divergence, dispersion, diffraction and scattering. Additionally, it must maintain its ‘self-focus’ characteristics and high-energy density, which are mandatory for achieving an effective target kill.
4.4) RESEARCH ON UPGRADATION OF NIGHT VISION DEVICES:
The modern infrared cameras, which are employed for night-vision during counterattacks at night, have to capture the heat signatures of the enemy objects, to transform the heat wave into a visible and identifiable image of the object. Thus, proper image resolution is the prime criterion for the functioning of these devices. Uncooled thermal cameras use sensors that operate at room temperature. Modern uncooled detectors use sensors that work by changing electrical properties of the material when heated by infrared radiation. These changes (in resistance, voltage, or current) are then measured and compared to the values at the operating temperature of the sensor. Uncooled infrared sensors can be stabilized to an operating temperature to reduce image noise, but they are not cooled to low temperatures and do not require bulky, expensive cryogenic coolers. This makes small, relatively inexpensive infrared cameras possible. However, they tend to have low resolution and poor image quality relative to cooled detectors.
Therefore, now-a-days cooled detectors are normally preferred for better resolution. They are still in a stage of research, inclined to enriching the field of Cryogenics. Cooled detectors are typically contained in a vacuum-sealed case and cryogenically cooled. This greatly increases their sensitivity since their own temperatures are much lower than that of the objects from which they are meant to detect radiation. Without cooling, these sensors (which detect and convert light in much the same way as common digital cameras, but are made of different materials) would be "blinded" or flooded by their own radiation. However, they have some disadvantages. The drawbacks of cooled infrared cameras are that the vacuum container is often expensive and difficult to produce, and the cooler requires a lot of power to function, and time to bring the sensor down to the operating temperature, as the camera may need several minutes to cool down before it can begin taking pictures. These devices make cooled infrared cameras generally bulky and expensive, but they also provide superior image quality compared to uncooled cameras. Materials used for infrared detection include a wide range of narrow gap semiconductors.
Another field where tank technology wants to upgrade itself is in the field of ‘Prognostics’. The Expeditionary Fighting Vehicles (EFV) Prognostics program was sponsored by the Office of Naval Research with the purpose of transitioning technology to the Fleet. This program was aimed to meet defined performance requirements for detection, diagnosis and prognosis.
Prognostics is defined as the ability to reliably predict the remaining useful life of mechanical or structural components, within an actionable time period, within acceptable confidence limits. The EFV program is developing an on-vehicle prognostics system that detects and isolates impending critical and/or catastrophic failures of the: 1.Engine, 2.Automotive Drive Train(Transmission and final drives) and 3.Vehicle Batteries.
The overall objective of prognostics is to provide information to support better management of operational and maintenance resources, integrated with vehicle diagnostics and testability. The EFV prognostics system will collect, store and process prognostic system sensor and vehicle information using on-vehicle processing and data bus resources. The vehicle’s Fault Manager will integrate prognostics system information with vehicle diagnostics information. The resulting prognostics fault codes will be displayed at crew stations if action by the operator is required. In addition, the prognostics information will be downloadable to the vehicle’s Portable Maintenance Device for access by other information customers. These information customers include: 1. Vehicle maintainers and 2. Operational Commanders.

5. CONTINUED:
Advanced Robotics Concepts:
Now-a-days, concepts have already risen about converting the present battle tanks to a remotely operated one or in other words, Robotic Battle Tanks.
DARPA has a heavy emphasis in advanced robotics concepts, to be applied to military vehicles. It focusses on those applications or technologies that are particularly stressing. One effort involves the development of very small robots that can work cooperatively on the tank itself. The challenge in this effort is to pack useful capability into a very small package, and to develop the software to allow these robots to work together. Another important effort will bring useful robotics technology to the work of dismounted operations in an effort to save soldiers’ lives.
Thus DARPA has initiated the Distributed Robotics program to develop microrobots that can work together in groups in dynamically changing environments. These small robots are proposed to be five centimeters (two inches) or smaller in any single dimension. They will work cooperatively together in groups, be capable of different modes of locomotion (land, water, vertical climbing, etc.) and will adapt their behavior based on remote user inputs or onboard sensors. The program has 13 contractor teams investigating different approaches, such as robots that can dynamically change their shape and locomotion mode. All contractors are now trying to demonstrate a single robot
Accomplishing a specific task, but in future,contractors will start work on multiple robots,working together.
DARPA has also initiated the Tactical Mobile Robotics program which aims at developing robotic technologies and platforms
designed to revolutionize dismounted operations by projecting operational influence and situational awareness into previously denied areas. These portable robots will be robust and able
to adapt to complex environments while employing specially designed payloads and devices. The program has selected three platform development concepts, demonstrated key component technologies for robust urban mobility (climbing up stairs, over rubble, etc.). Basic mobility platforms are likely to be outfitted with revolutionary perception aids such as Omni-cameras and laser scanners in conjunction with development of semi-autonomous navigation capabilities for non-GPS conditions (indoors, underground, deep jungle, etc.). The program is thus aimed at integrating enabling technologies and specialized payloads into functional platforms.

Advanced Energy Technologies:
DARPA is investing in a variety of technologies to provide high energy-density power sources for military systems. The program is investigating alternatives to traditional batteries for portable power applications through the use of fuel cells and solar cells, as well as methods to harvest energy from the environment for use in the vehicles. The program has already demonstrated robust, multi-kilowatt logistics fuel processing with fuel cell stack integration and transitioned the technology to the Navy’s Ship Service Power Program.The program will focus on generating electrical power in the 300- to 500-watt range directly from logistics fuels using compact, low-signature technologies such as thermophotovoltaics and solid oxide fuel cells, installed in military vehicles. The program is also investigating electostrictive polymers and piezoelectric materials for power generation from mechanical motion of the crew in the tanks. These materials can be easily loaded in the tank armour. Thus the program is trying to integrate these energy-harvesting technologies by testing them with sensors and small devices.

ADVANCED CRYOGENIC SYSTEM TECHNOLOGY:
Because of the electromagnetic interference in the present day electronic warfare, the radars installed on the ground military vehicles are not able to detect the weaker signals from the enemy forces. Thus DARPA has encouraged the Cryo-Systems program for developing high-temperature superconducting components packaged with cryogenic devices for use in radar, electronic warfare suites and communications systems, so that increasingly weaker signals are detected within a background of interference and clutter.
Initially, most of the vetronics systems rely on software algorithms. High-temperature superconducting filters and amplifiers are very selective, and can screen out unwanted signals to receive only the desired frequencies. But this type of multiband performance is particularly useful for signals intelligence collection systems and for improved GPS jamming rejection.
Cryogenic systems have been employed at ground-collection sites and installed in Navy and Air Force reconnaissance aircraft as well as ships. Now further demand is made for their use in tank technology. All are showing greatly improved reception of low-power signals within a noisy background. The range enhancement is typically two to three times greater than previously possible. A signals intelligence collection system for multiple cellular bands, using cryogenic components, is likely to be demonstrated. Thus the program is likely to focus on developing tunable superconducting filters, while maintaining their superior selectivity, enabling reductions in size and weight while increasing the coverage in detection of low-level signals.

ADVANCED MATERIALS TECHNOLOGY:
Research in advanced materials for military vehicle application technologies is the last of DARPA’s historical core investment area. Past achievements have tended to be in the area of structural materials such as advanced composites and ceramics. Both were instrumental in achieving the desired performance on armoured vehicles. Work continues in structural materials, focusing on ultra lightweight, high-strength materials for specific military applications, including body armor. In addition, they are investigating new materials that are termed “functional” in that they contribute to tank system operations or capabilities beyond simply forming the system structure. In this area, they are looking at magnetic materials, smart materials (which sense and respond to their surroundings), electroactive polymers, and frequency-agile materials. Thus researchers continue to support the development of high-temperature superconducting components, as well as a variety of advanced energy technologies and an effort to develop a new high energy explosive material.
DARPA has started the Ultra Lightweight Materials program to pursue metals that have the light weight of a composite material but without the traditional worries of corrosion and delamination. The metal is fabricated with a variety of internal microstructures, giving it strength with minimum weight. This will lead to substantial weight and cost savings in a number of military applications. In addition, the internal microstructures allow the metal normally used as part of a structure to also perform a useful function such as blast mitigation or thermal control. These new materials are to be demonstrated for antenna masts on tanks. The program is investigating other military applications such as the development of bullet-resistant fuel tanks in military vehicles.
DARPA has also activated the Smart Materials and Actuators program to develop new classes of materials and structures that use integrated sensors and actuators to respond and adapt to mission needs and the environment. This technology is being developed to suppress vibration and actively tune structures to reduce noise in armoured systems.
As part of the Functional Materials effort, the Electroactive Polymers project is another challenge undertaken by DARPA. Researchers are trying to develop polymers that can conduct and respond to an electrical current. The polymers can take the form of a thin film or a fiber and move or change shape when an electric current is applied. Such materials provide great help in the Robotics concept of the tank. These materials can be used as artificial muscles for small robots. These robots will have artificial “retinas” to process images quickly and efficiently.
DARPA’s efforts in the Frequency Agile Materials for Electronics program are investigating new materials that can be modified by the application of either an electric or a magnetic field. In these new materials, the application of this field changes the property of the material in some way. The materials can be used as communications systems filters and antennas – the magnetic or electric field “tunes” the filter or the antenna to be more responsive to a particular frequency. Antennas constructed from these frequency agile materials can be smaller and lighter weight, and can be a variety of shapes. These antennaes can be installed on military vehicles, easily conforming to the shape of the tanks. The materials fabricated and tested to-date in the program have shown promising performance.
One of the very interesting programs of DARPA has inaugurated the Spintronics program or the Non-Volatile Memory program for the military vehicles. The program has demonstrated a radiation-hard, 16-kilobit memory that is only one square centimeter in size –this chip is desired to be used on military systems to upgrade memory capabilities. The program has also proposed to develop a memory chip slightly larger than one square centimeter holding more than one megabit of information. This program is surely capable of upgrading the capability of the Vetronics system on tanks.
DARPA is also advocating the High Energy Density Materials program to investigate the synthesis of new molecules that will have 200 percent to 500 percent more explosive and/or propulsive energy per unit weight than does dynamite, and have between two and six times as much propulsive or explosive energy as current state-of-the-art operational materials. In addition, they are looking at molecules made solely or mostly of nitrogen, whose production and use should be environmentally friendly. If the program succeeds, the capabilities of the new materials could provide increased range and maneuverability and/or increased kill-effectiveness for the tank armament systems against missiles( greatest of all tank threats) through improvements in both the propellant's thrust and the warhead's lethality (per weight and volume). One research team recently proved the existence of a new nitrogen ion, a key step in synthesizing the new high energy-density form of nitrogen sought by the program.
Thus, the new reasonable technologies pursued by DARPA towards the supportive development of military vehicles are worth appreciable. As DARPA takes its role as the technical enabler for innovation for national security very seriously, it will surely be the key to the success of the tank warriors of the 21st century.
7. PROPOSED MODERN LAND OPERATIONS:
The future of land operations is likely to be multidimensional, complex and largely unstructured. That's why the MoD is instigating development of the Future Rapid Effects System (FRES), to meet the need for greater mobility, survivability and systems integration for armoured fighting vehicles.Among the wide-ranging programmes that are being used to support FRES are:
1. vehicle architectures
2. the development of standards and guidelines
3. improved survivability and Command, Control, Communications, Computers and Intelligence (C4I).
Improved survivability: Survivability is perhaps the key issue. So the programmes include defensive aid systems and electro-optical counter measures - including an anti-dazzle CMOS camera. Involvement with C4I includes:
1.Vehicle system integration and electronics
2.Crew system technologies.
In every area, long-established experience in human factors integration is applied to support the technologies and ensure that troops are better able to fight and survive. Improvements are being made for C4I both within and between platform structures, to raise crew awareness and knowledge, and increase their survivability.
Sensors bring the digitised battlefield and network centric warfare closer. With advanced data processing techniques, sensors improve situational awareness and survivability, and increase the probability of real-time links between sensor and shooter. And they will - as they develop further - make it easier and more efficient to mount precision attacks on high value targets, at greater depths of engagement.Artificial intelligence technologies and unmanned systems are also being developed to improve troop protection, making it possible to remove soldiers from danger in close combat zones.
6.1) CASE STUDY OF RECENT ARMOURED DEVELOPMENT:
Qinetiq has built their innovative Advanced Composite Armoured Vehicle Platform demonstrator (ACAVP)(Figure shown below) from revolutionary materials. They developed fibre composites, and affordable titanium alloys in a business venture with British Titanium. Together they gave Qinetiq strong, lightweight structures suitable for lightweight ordnance, vehicles and armour.
Fig.23 Showing the Plastic Tank.Nicknamed the 'plastic tank', ACAVP has been thoroughly tested, driven over 1,800 km and found to have significant stealth advantages over traditionally-structured vehicles, including its radar thermal and electromagnetic signatures. The ballistic tests carried out on composite materials have also been an outstanding success. Building on this success they are now developing new composite-material armoured fighting vehicle demonstrators, including main battle tanks.
6.1.1) PLASTIC TANK:
AFV construction hasn't changed much since the 1960s, when aluminium was introduced as an alternative to steel, so why was there the need for such a radical departure now? It's all a question of weight and of how the British Army is increasingly becoming involved in policing the world. The answer was to develop a vehicle with at least the same protective capabilities as those currently in use, but light enough to be airlifted easily at short notice. This meant abandoning metals for a lightweight, but extremely tough, moulded E-glass fibre composite: plastic.
The 'plastic tank' is a world first in military engineering. It's a groundbreaking new project, in conjunction with the UK Ministry of Defence and Vickers Defence Systems. The Advanced Composite Armoured Vehicle Platform (ACAVP) is the first composite moncoque plastic AFV to have been made in the world. The vehicle can withstand attack from a whole range of threats - including high performance cannon fire - while increasing the survivability of the crew against small arms fire, shaped charge anti-tank rounds and shrapnel from artillery shells, compared with conventional vehicles. In addition, the vehicle incorporates stealth technology to reduce its visibility to radar and infrared sensors. The new plastic armoured fighting vehicle (AFV) has sailed through its battle tests and proved to have major advantages over conventional metallic armoured vehicles of a similar size. Vickers believe it could prove a tremendous asset; it's faster, lighter and therefore easier to transport by air than conventional vehicles, so it can be flown rapidly to war zones.
Fig.24 Showing the ACAVP on trials at QinetiQ's test track.
For many years, composites have been used to make protective liners in armoured vehicles to prevent spallation - the potentially deadly shower of metal shards that can shear off inside the hull when the vehicle is hit. By removing the metal hull and replacing it with a plastic construction, there is no need for the weight-increasing spall liner and the danger to the crew from a hit is reduced by the design. It has passed all the tests required of a fully operational military vehicle and the technology can now be taken up by industry to be used in production vehicles. The plastic tank at a glance:
§ Weight: just 24 tons, four tons lighter than the similar metallic vehicle.
§ Top speed of 40mph over rugged terrain.
§ Decreased fuel consumption, reducing the need for supporting fuel tankers
§ Increased survivability for the crew, through: reduced visibility to radar and infra-red scanners; reduced risk of shrapnel inside the hull; better protection against bullets, mortars and land-mines.
§ Ideal for use in salt-water conditions, as plastic is less susceptible to corrosion than metal.
7. CONCEPT OF THE FUTURE COMBAT SYSTEM (FCS) :
The mentioned brainstorming research activities in the various fields, such as in the areas of weapons, armour,power plants, etc, will give rise to a new conception of the Future Combat System( may be in the 20 ton class ), representing a dramatic departure from the previous concept of the main battle tanks. According to the US Amy Tank-Automotive and Armaments Command’s picture of the FCS, it would be based on evolutionary tank design and technology. According to some of the military researchers, the next generation armoured fighting vehicle may not be referred to as a modified MBT of today.Thus, the systems engineering procedures will change the entire picture of the Future Combat Systems, so that it may not appear as the present tanks. This is evident from the computerised model of the desired model as shown below-
Fig.25 Showing a computerized model of the proposed Future Combat System.
Scenario of the FCS assumes that it can be the major contributor to the modern digitized battlefield environment. Operational requirements dictate that the FCS should operate as a ‘combat system’, while functioning and communicating beyond the conventional rather narrow tactical level. The FCS will be an active node on the battlefield digitized network. This is, in essence, a dramatic departure from the conventional way, tanks have been operated and deployed, since their inception. There will be Reconaissance Modules, which will be fired to assist the commander and crews in obtaining real time digitized information on the close area battlefield. This information will be used by the local forces, but also will be conveyed to the Greater Area War Management Centre. Information on enemy targets, obtained from these modules, will be fed back to the FCSs, which are prioritized, and used to automatically direct, aim and fire the Electromagnetic Guns and high power Laser Guns and anti armour/air missiles at their potential targets. Thus the FCS will serve as the integral part of the modern battlefield and will serve as its eyes and ears. The FCS is also conceived of being equipped with a second generation Vetronics system, that will further advance digitized data control and distribution, electrical power generation and management, computer resources, crew control and display processes. The Vetronics system will be capable of accepting a variety of inputs and delivering outputs, related to power system control, communications, countermeasures, weapons control, sensor control, artificial intelligence, training, maintenance, diagnostics and prognostics. This architecture will provide the interface between the various functional modules, computers and power sources, thus ultimately leading to the concept of an Unmanned Fighting Vehicle or more precisely, a Robotic Vehicle. The layout of the conceived FCS is shown below.
Fig.26 Showing the scenario of the FCS.
8. CONCLUSION:
Prediction of the future is within the realms of astrology, and preparation for it is wisdom. To visualize the design requirements of the future MBT,by the turn of the century, requires a knowledge of the present state of the art in tank designing, and the correct visualization of the future battlefield. Also required would be a rough idea of the economic layout and ability to gauge the technological and management expertise, without exaggeration, so as to produce a high technology-intensive offensive weapons system in the next two decades or less.The position of the tank as the most powerful weapons system of the ground forces, will probably remain unchanged. No other system, in sight is able to fulfill its function, better than a tank. However the shape of the tank will change. Countries which have the need and resources to develop and produce their own tanks are all, as ever, faced with the same general problems. On the other hand, they all have to keep pace with new technologies to defeat tanks, by improving their protection and make progress in their mobility. In this process, the weight is likely to go up, because of the need to increase the protection of tanks of a given size and also because of the size of the armament they will need, to defeat improved armours. True engines and transmissions will get smaller and lighter for a given propulsive power, but apparently not small enough to compensate for expected increases in the weight of the protection and armament. Therefore, in order to achieve satisfactory tank weights from the mobility point of view, new tank concepts will have to be adopted.
It is sometimes better to think unconventionally, in order to break the shackles of conventional thinking. The drills and fighting techniques, ie, the tactics for tank fighting have been established over the years and cannot be changed immediately because of the inherent time lag to educate the troops and train them for a new methodology. The equipment or weapon designers should always stay a step ahead of the existing techniques, by resorting to revolutionary designs, which defeat the tactics. At all stages of the design effort, two factors are always to be kept in mind. Firstly, the proposals should be forward thinking but realistic and secondly, as far as possible, the recommendations should be capable of being implemented indigenously, within the stipulated time frame. The following quote puts across the basic thought, underlying this attitude:
“A good researcher and engineer must be the masters of two ends of the spectrum: Ideas at the highest level of abstraction and analysis and implementation at the most mundane levels of details.”