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The Macabees' Guides on Armored Warfare and Technology

A place to put national factbooks, embassy exchanges, and other information regarding the nations of the world. [In character]
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The Macabees
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The Macabees' Guides on Armored Warfare and Technology

Postby The Macabees » Thu Mar 16, 2017 11:44 am

Several years ago, I wrote a series of guides on tank technology and related topics for the NationStates Draftroom. I wanted to put them all in one place here, on the NationStates forums.

N.B. A lot of the commentary around contemporary tank programs is outdated. For example, the FCS program has since then been discontinued and replaced.

Table of Contents
Last edited by The Macabees on Sat Mar 18, 2017 12:24 pm, edited 2 times in total.

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Postby The Macabees » Thu Mar 16, 2017 11:45 am

Problems Encountered with Higher Caliber Tank Guns


According to estimations from the mid-80s, the future soviet tank (FST-3) had enough armor to defeat anti-tank ammunition fired from a current 120mm powder gun. Future NATO tank guns would have to produce 18MJ worth of energy at the muzzle, for the penetrator of an armor piercing fin-stabilized discarding sabot (APFSDS) – double the energy produced by the Rheinmetall 120mm L/44 gun mounted on the Leopard 2 and M1A1 Abrams (produced in the United States as the M256).1 A number of solutions were proposed, including the use of a 140mm solid propellant gun. There were a number of more extravagant solutions, including electromagnetic acceleration and electrothermal-chemical ignition and control. Despite the wide array of options in regards to enhancing vehicle lethality, the easiest and fastest solution remains the adoption of a 140mm powder (solid propellant) tank gun. In fact, most tank-producing nations have developed a number of 140mm cannons for use in future tanks and 140mm guns have been fitted into existing turrets; however, no nation has seriously considered the use of a 140mm gun. Since the late 70s tank enthusiasts have been predicting the introduction of larger caliber weapons. Yet, no Israeli Merkava tank has been seen with a 140mm tank gun2 and no Russian tank has been seriously developed with a 152mm piece.3 On the other hand, development continues with electrothermal-chemical technology for use in tank guns, and some still see electromagnetic propulsion as the future in tank armament.

Nevertheless, calibers larger than 120mm are still enticing and see extensive use in NationStates. Especially popular are either the 152mm or 155mm calibers. The use of both these calibers has been popular ever since the publication of multiple articles giving estimations on the armament of the Black Eagle – a T-80U turret upgrade – and the future T-95.4 It should be noted that the Black Eagle turret mounts a solid propellant 125mm tank gun, probably the 2A46M-4 tank gun adopted on the T-80UE.5 The T-95s armament, admittedly, remains a mystery, along with the rest of the tank. There have been actual attempts to mount a larger caliber tank gun into existing tank turrets, although very few details are published about these projects. The Swiss mounted a NATO 140mm gun into a Panzer 876 and the Russians have recently introduced a long 152mm cannon into a T-80, with some turret extensions in the front and a bustle in the rear. It’s possible that there have been prototypes of a 140mm armed main battle tank in the United States of America, although the main battle tank program was canceled in 1995.7

Image
A Newsweek article with concept art of the FST-2


The lack of information on the development and testing of tank guns of a caliber between 130mm and 160mm admittedly makes it difficult to understand the consequences of implementing a gun of this caliber. These negative side effects of increasing lethality through increasing caliber only accumulate as the caliber gets larger – i.e. the effects of using a 155mm gun are much greater than those of using a 140mm gun. Consequently, oftentimes the use of these heavy cannons in tank designs in NationStates doesn’t accurately portray the negative side effects. Although this isn’t necessarily the author’s fault, it’s a mistake that should be corrected. This informative is an attempt to explain the advantages, as well as the various disadvantages, of larger caliber tank armaments. These disadvantages include increased turret volume, potential increase in hull volume and increase in weight. The informative’s argument is that these increases in volume and weight do not justify the increased lethality, especially given that there are many alternative options in tank gun technology.

140mm+ caliber lethality
The original goal, as stated above, was to achieve muzzle energy of 18MJ. In tank armor penetration by kinetic energy (armor piercing fin stabilized discarding sabot – APFSDS) the principle (and the simplest) factors which effect penetration are velocity and mass.8 Therefore, the simplest equation which can given an idea of a round’s penetration is KE = ½m •v2. With an increase in muzzle energy you can either increase mass or velocity of the round. With a decrease in mass there is an increase in velocity, and the same is true vice versa. This greater muzzle energy is established through the use of larger propellant charges – larger barrels can withstand larger charges because the created pressure during gas expansion is distributed along a greater surface area. The idea is the same in high-pressure guns, except that special materials are used to withstand higher pressure in the breech and barrel.9 Although the common goal is 18MJ, there is nothing that suggests that the muzzle energy produced by a 140mm caliber tank gun is and always will be 18MJ. The performance of a 140mm gun, and any gun, is based only upon the construction quality of the barrel, breech and round and the quality and volume of the propellant. In fact, a 140mm gun may produce only 16 or 17MJ of energy.10

According to Rheinmetall, a 140mm tank gun produces energy of 23MJ at the muzzle. However, only 14MJ are relevant to the penetrator itself.11 Fired from a NATO 140mm gun, a tungsten heavy alloy (WHA) penetrator with a length to diameter (L:d) ratio of will penetrate roughly 830mm of rolled homogenous steel after penetrating a 400mm ceramic module (the ceramic is not necessarily encased in steel).12 Due to the considerable power achieved by the 140mm powder gun and the availability of the technology, it was thought as early as 1989 that the 140mm would be used as a stop-gap solution.13 The amount of technology demonstrators of this caliber make it apparent that at one point in time it was a real solution. The U.S. XM291 solid propellant gun showcased a breech which could fit both a long 120mm cannon and a 140mm cannon if it was necessary in the future.14 However, today the 140mm gun is no longer considered a real option by any NATO tank-producing country.15 Instead, the Germans introduced the new 55-caliber long 120mm tube and the DM53 APFSDS in the KWS I upgrade of the Leopard 2A5 (the 2A4 to 2A5 upgrade is the KWS II, which increases the depth of the front armor array).16 The XM291 120mm tube is also longer than the current M256 (a copy of the Rheinmetall 120mm L/44), but was never implemented and there is still no gun modernization program in sight.17,18

Image
British advanced tank armament mounted on a Centurion chassis.


Although the 140mm tank gun, and any caliber above 120mm, offers better ballistics than existing 120mm solid propellant guns against current and future armored threats, the large-caliber gun was a solution based on the lack of time.19 Prior to the fall of the Soviet Union the FST-2 and FST-3 were considered threats beyond the capabilities of NATO tanks of that time, including the M1A1 and Leopard 2. The M1A1HA (heavy armor) upgrade was introduced at a cost of around $1 billion due to the threat posed by the theoretical FST-2.20 Beginning in 1988, there were 1,328 M1A1HA tanks manufactured and another 834 with increased armor protection (M1A!HA+).21 However, the Soviet Union fell in 1991 without producing either the FST-2 or the FST-3. Thankfully, the fall of the Soviet Union has allowed us to take a closer look at the advantages of a 140mm gun. The pace of development has decreased, along with decreased budgets for research and design work on advanced tank armaments. Instead, work has been put into upgrading the lethality of light armored fighting vehicles for deployment in peace keeping operations. This has given Western nations a chance to develop next-generation armaments in the 120mm caliber. However, if NATO wants to design a future tank with MLC 60 or 50 as its weight limit, tank designers will have to look for a smaller caliber solution.

Disadvantages
Even with a decrease in the ammunition held, the volume of thirty 140mm rounds would be roughly 3.05m3. An individual 140mm APFSDS could weigh as high as 40kg, while a 120mm APFSDS weighs between 19 and 23k. This means that thirty 140mm rounds would weigh roughly 1,200kg as compared to the 830kg of a forty round 120mm ammunition load. 22 Rheinmetall’s 120mm L/44 weighs 1,190kg, while the L/55 version increases the weight to 1,347kg. GIAT’s (now Nexter) 120mm F1 weighs 2,800kg and the M256 weighs 1,901kg. The high-pressure MG251 weighs roughly 3,300kg.23 However, let’s take Rheinmetall’s L/55 and the XM291 as the more recent in solid propellant technology (the XM291 saves about 600kg worth of weigh as compared to the M256). In comparison, a 140mm gun (including the trunnions) would weigh over 3,200kg. It would also require a breaking force of up to 1,200KN.24 In gun weight and ammunition weight alone the increase in weigh would be about 1.5 metric tons. The necessary increase in turret volume to allow a depression of the main gun to anywhere between 7º and 10º could cost another 5 to 6 metric tones in weight. The increase in gun caliber would also result in an increase in the size of the mantlet, resulting in another increase in armor volume and weight. In fact, a total weight increase due to the larger turret armor volume could amount to up to over 10 metric tons.25 Insofar, the total weight increase amounts to closer to 15 metric tones. Taking the weight of the Leopard 2E of around 63,000kg26, it would mean that based on what we have figured out a 140mm tank with the same proportions of mobility, protection and lethality would weigh almost 78,000kg. In order to keep within the maximum acceptable ground pressure of 9N/cm2 the chassis would also have to be enlarged in both width and length. The increase in weight of a 140mm gun, with a proportional increase in protection and mobility, would be a far greater difference to existing main battle tanks than is the difference between the M60 (52,000kg27) and the M1A2 (roughly 64,000 to 65,000kg28).

The maximum width of the vehicle is dictated by what is allowed by a nation’s rail system. The amounts of distance between any given points in the majority of nations in NationStates make travel by tank track improbable. NATO armies, and their allies, have always used rails, while the Soviets have always had the philosophy that a tank should be prepared to travel great distances on its own tracks. But, the Soviets have traded other aspects of their tanks for increased engine life. In terms of track life, the AMX-30’s tracks could travel an average of 5,000km. 29 Track life of current tracks is most likely similar, as no major innovations with track durability have really been made. Fuel considerations make travel by truck over long distances as improbable as travel by one’s own track. Currently, Spain’s truck transport can fit a single Leopard 2E or two Pizarro infantry combat vehicles. Assuming that a truck was made to carry a much larger main battle tank it would still only be able to carry one. Taking into consideration tank fleets in NationStates, let alone distance to travel, the amount of trucks required to transport armor material across the country would exceed a country’s capability. The width of a nation’s highway lane also plays apart in the allowable width of a tank. The use of multi-lane highways solves the problem to a certain degree, but doesn’t get rid of it. The costs of constructing a multi-lane highway network across a country the size of the Soviet Union would not allow a nation to procure an expensive main battle tank! On a more serious note, it’s not realistic to assume that a nation can change the width of its railroad tracks to accommodate a larger main battle tank. Therefore, there exists a physical limit on the width of any main battle tank.

Battlefield mobility of a tank is dictated by the relationship between the length of the track touching the ground and the width between the centerlines of each track. Ratios of over 1.5 will disallow a tank from making quick turns, and may even cause a crew to damage or break the tank’s transmission. Given the maximum allowable gun pressure we know that there is a maximum allowable weight per width. Width is hard to increase due to road and rail constraints. Consequently, one could say that there is a maximum weight limit of a tank. Taking into consideration Western rail gauge, this limit seems to be MLC 70 (roughly 64,000kg). Therefore, a 78,000kg tank would find it hard to strategically deploy long distances, not to mention the ability to deploy overseas!

Even so, 78,000kg doesn’t take into consideration several more weight augmentations. An increased weight requires increased engine volume and fuel volume. Fuel tanks, within themselves, constitute a substantial increase in weight due to protection requirements. It would be nearly impossible for a human loader to load 40kg ammunition in the ideal loading time of 5 to 7 seconds, and therefore an automatic loader would be necessary. Nevertheless, the weight of the ammunition would require a loading system of at least 600kg, so there are no weight savings in that area. And, we are assuming an armor protection equal to current tanks. Ideally, a 140mm armed tank would also have an increase in armor protection. That constitutes a large increase in weight. 35 metric tons of the Abram’s weight is armor,30 meaning we’re looking at a weight increase of armor by a factor of at least ten metric tons. In terms of aerial density armor protection can weigh up to 4 metric tones per meter.31 Therefore, if current lethality and protection patterns are kept the 140mm armed tank could weigh well over 80,000kg.

Image
A comparison chart, offered by Rheinmetall, with three different Rheinmetall tank armaments.


Taking weight into consideration, one should also figure in logistics. The cost of logistics can be related to as the eighth power of the tank’s weight (for a tank of the weight we’re discussing).32 Therefore, the logistics slice of a 80 ton tank would be roughly 5 times greater than an existing 63 ton tank! And this fails to mention the cost of construction of each individual tank. The cost considerations in manpower, man hours and logistics resources are exponentially greater than those in a modern real-life main battle tank. The use of advanced technologies, such as computerized active hydropneumatic suspensions and computerized transmissions will add to the cost of the tank, but this fact remains the same in all tank design.

Unconventional Solutions
If weight is the principle cause of the problem, any user of a large caliber tank gun should look into solutions which reduce weight. Nominally, this means unconventional turret designs. As an example, Jordan’s King Abdullah Development and Design Bureau (Kaddb) revealed the new Falcon turret at Idex 2001. The turret is designed to reduce he frontal profile as much as possible (although, it should be known that the smaller the frontal profile of the turret, the larger the sides will be33), as well as weight, and is an upgrade option for Arab M60 Patton tanks and Jordan’s own Challengers (Al Husseins). The two man turret crew (the driver is still in the hull) is seated in the turret basket, reducing the required amount of protection in the front. By reducing the front turret profile and moving the position of the crew Kaddb radically decreased the armored volume of the turret reducing weight just as dramatically. However, moving the crew into the turret basket results in disallowing the tank commander from a good panoramic view – in essence, he’s commanding the tank based on computers. Furthermore, the Falcon turret’s autoloader only holds eleven rounds (with plans to increase to sixteen), compared to the forty rounds held by the M1 Abrams34 – the Falcon turret is wedded to Ruag’s 120mm compact tank gun (CTG), which weighs 2,600kg.35

Reducing turret volume, as shown by the Falcon turret upgrade, is always an option and may result in a hefty reduction of weight, given the reduction in armored value. As a reference, assuming full nuclear, biological and chemical (NBC) protection each crew member will require about .4m3 and the loader .8m3 to achieve the fastest loading rate possible (as close to 5 seconds as possible)36 and to this we add another 10% for crew comfort and freedom of movement. So we can come to the conclusion that a conventional four man crew requires just about 2.5m3 in terms of volume. This is even larger for tanks which attempt to move the driver into the turret, since that driver now needs to counter-rotate meaning his required volume will be based on the spine of his seat and not on his center of mass, effectively doubling the required volume. A three man crew, however, requires less than 2m3 plus the required volume for the tank autolading system. In terms of turret volume, however, we’re talking about a volume reduction of a little bit over 1m3. Jordan pays the price in the weight of its gun (heavier breech) and the relatively small ammunition hold, and the inability to replenish the autoloader’s ammunition under armor (instead, the crew has to replenish from the outside). One can also reduce the crew from four or three to two, reducing fighting compartment volume from 10m3 to around 3m3. 37 There are, as always, important considerations including the requirement to train multiple crews per tank – a two-man crew will not be able to successfully guard the tank at night, or maintain the tank on their own. Furthermore, each crew member now has a larger share of the tasks.38

Other turret options include the cleft turret and the externally mounted gun. The former reduces turret volume, and the latter almost gets rid of it completely (you only have to armor the breech against small arms). Both have huge ballistic weaknesses, although if you can guarantee the first-round and the necessary lethality of that first-round then ballistic weaknesses are almost irrelevant.

However, it’s questionable whether a 140mm solid propellant gun or even a 155mm solid propellant gun can penetrate the armor of a NationStates tank on the first hit. Let’s say that a M829A3 APFSDS scaled up to be fired from a 140mm gun (larger mass) has a penetration of roughly 1,200mm of RHAe (rolled homogenous armor equivalent); this is still insufficient to penetrate a large number of tanks with over 2,000mm RHAe along the front 60º arc. Always hitting the side armor is unlikely, as that’s what the Israelis did during the Six Day War yet close to 35% of the hits are registered to hit the tank front 60º. During the Yom Kippur War near 55% of the hits were registered on the front 60º and during the Second World War (the most ‘copied’ war of NationStates) this percentage increases up to the 70% mark! 39 This doesn’t even begin to take into consideration the armor protection between the 60º and 90º protection arc in main battle tanks, or up to the 120º degree arc! The Black Eagle, for example, has explosive reactive armor integrated into the front 120º arc of the turret.40 One source claims a turret armor protection of up to 880mm for the Black Eagle, although if an improvement in side turret front armor over the T-80U is assumed then we’re looking at more than 400mm worth of protection against kinetic energy (KE) threats in terms of conventional armor.41 If Kontakt-5 provides 300mm worth of equivalent armor against APFSDS,42 then it’s possible that the Black Eagle has a side turret front protection level of over 700mm RHAe, and possibly up to 800mm RHAe. That means that the Black Eagle may have a side turret front armor protection level close to the front protection level of current generation main battle tanks. Improvement in passive armor thickness and mass efficiency, as well as improvements in explosive reactive armor, might mean an even higher level of protection. Although the Black Eagle is not going to be adopted by the Russian Army, it serves as an example as what future tanks can achieve (like the T-95).

Image
A comparison between the T-95 and the M1 Abrams in size.


For example, with a weight increase of just 1.5 to 2.5 metric tons43 the M1A2 SEP can adopt a heavy explosive reactive armor suite increasing protection by about 300mm RHAe. This would increase effective protection along the front 60º arc to over 1,200mm RHAe and the side turret front armor to about 650mm RHAe. 44 The most important consideration to take into consideration is that Kontakt-5 explosive reactive armor proved to completely stop the M289 APFSDS.45 Although the new M289A3 APFSD was specifically designed to defeat Russian explosive reactive armor, new reactive armor concepts may prove more difficult to puncture. For example, Ukraine’s Nozh explosive reactive armor uses a series of explosively formed penetrators to literally cut the APFSDS into several pieces. However, Nozh suffers from the disadvantage of relying on a dramatic impact angle. Regardless, the point remains that the efficiency of explosive reactive armor shouldn’t be measured in RHAe as opposed to its ability to break the incoming APFSDS.

This takes us back to turret design. If one can reduce armor volume to reduce weight, one can rearrange previous armor in order to increase the thickness of the surface area left. In other words, a tank with a narrow mantlet turret can have an increased thickness in armor for no penalty in weight (you just don’t lose the weight). So, if by maximizing line of sight thickness of the armor, like the Leopard 2A5, a future tank can achieve armor protection of around 1,500mm RHAe then a 140mm gun is incapable of penetrating the frontal arc of that tank. Of course, an electrothermal-chemical gun might be incapable as well, but it doesn’t have the added weight penalties!

Technological solutions
There are advances in tank technology which may allow for weight savings. The German MTU 880 series of diesel engines produce around 215kW/m3, a substantial improvement over prior diesels – it is 35% smaller in volume and 14% lighter in weight.46 In other words, the MTU 880 produces 288hp/m3, which means that to provide a hp/t ratio of at least 20:1 the engine bay would require at least 5.6m3 (based on a 80,000kg tank). This would produce 1,600hp, while a 2,000hp engine would require about another 2m3 worth of volume. MTU claims that the MTU 890 series engine is 50% smaller than the MTU 880 series in terms of volume47, which to me says that the MTU 890 can produce 430kW/m3, or that a 1,600hp engine bay would require a volume of about 2.8m3. There are claims that the MTU 890 produces 1.2MW/m3, 48 but these are highly suspect – nevertheless, the lack of an alternate source disallows me from discarding the figure. Nevertheless, use this latter figure as carefully as possible; else we might have another buckyball trend! Regardless, new diesel engines provide a heavy savings in weight, forgive the pun.

There are also weight savings in the areas of future transmission systems, and the use of certain materials in vehicle and armor construction.49 Alternate armor could be a consideration, or even the reduction of armor protection to save mobility. This concept was the guideline for the French AMX-3050 and the German Leopard 1,51 and may have been the guideline for the U.S. future main battle tank (FMBT) which aimed for a combat weight of 20 metric tons.52 Of course, the problem isn’t as severe as it is for a twenty ton tank with the goals of a sixty ton tank, but there are similarities. While technological breakthroughs may save some weight, any heavy NS tank design that scales up with current technology will have to rely more on ingenuity than on technology. Cost should also be taken into consideration when using high technology. Currently, more than 60% of a tank’s cost is the high technology and electronics used. 53 If a M1A2 costs $5.4 million to produce54 then $3.24 million is applied to electronics. That said, any future tank with the most advanced in terms of electronics and high technology to save weight or enhance features that now have to support greater weight may cost over $10 million. These systems include electric transmission, active hydropneumatic suspension and advanced remote controlled weapon stations. There’s also a high cost in the technology provided to manufacture certain parts of the future tank (like advanced armor).

Alternatives
There are great deals of alternatives to 140mm guns in smaller calibers which can be explored.55 This includes the more well known electrothermal-chemical technology, which will provide the necessary energy to match the muzzle energy of a 140mm gun. Unfortunately, this comes with the added costs. Technologies which may be applied to the future, assuming advances in energy storage and efficiencies, are electromagnetic propulsion systems – for example, rail guns and coil guns. However, these are not solutions to be considered for a long while. Simpler alternatives are improved solid propellant guns. The 120mm L/55 firing the DM63 can penetrate as much as 900mm of rolled homogenous steel, 56 while the penetration of the same gun firing the M289A3 may exceed 1,000mm of penetration! Advanced solid propellants might also offer short-term improvements in lethality, with smoother burn patterns and higher amounts of energy per volume. The alternatives are out there, they just require some researching!

Image
Swiss Pz87 with a 140mm gun.


On the other hand, advances are in the form of the ammunition. Rounds like the XM943 can engage tanks at long ranges and defeat them by engaging the roof armor with an explosively formed penetrator57 – in other words, a gun-launched long-range anti-tank missile. Rounds like SADARM58 can drop multiple submunitions on a target, increasing chances of penetration. This type of guided ammunition greatly increases the engagement ranges of tanks and questions the requirement of heavy armor. For example, a 155mm howitzer can knock out one or more tanks using submunitions while those tanks can’t even respond. The introduction of indirect fire munitions may merge the roles of heavy armor and self-propelled artillery, although the former could never provide the necessities for occupation (the lack of heavy protection) while the latter is simply too expensive to replace the artillery vehicle. Indirect fire munitions may also argue in support of large guns – the larger the gun, the larger the round the more submunitions it can hold. However, it also argues for the use of smaller caliber guns. A tank designed with a 105mm high velocity gun has superior mobility than larger variants, may have an equal level of protection and can engage enemy tanks at non-line of sight (NLOS) ranges. Its armor protection would be enough to protect it against infantry armaments such as light anti-tank rockets or top-attack missiles through the use of explosive reactive armor and an active protection system. It would also be cheaper and a nation could deploy more for the same costs.

In the end, the use of alternatives is up to the creator. There are always design specifications and operational requirements to take into consideration. Each creator might also have different opinions and perspectives. It’s all part of the game. However, it’s important to always take into consideration the advantages and disadvantages of any given piece of equipment – including large caliber tank guns.





Notes



1. Orgorkiewicz, R.M., Future Tank Guns, Part I: solid and liquid propellant guns, Janes International Defense Review, 12/1990, p. 1377
2. Eshel, David, The Merkava Mk. 3 Defies Its Critics, ARMOR Magazine, 1 May 2000, p. 17.
3. Warford, Jim, The Resurrection of Russian Armor: Surprises from Siberia, ARMOR Magazine, 1 September 1998, p. 32.
4. Ibid. pp. 32-33.
5. Baryatinskiy, Mikhail, Main Battle Tank T-80 (Russian Armor), Ian Allen Publishing, 2007, p. 93
6. Panzer 87 refers to the name of Swiss produced Leopard 2A4s.
7. Acquisition of the Advanced Tank Armament System, Department of Defense, 28 February 2001
8. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 90.
9. http://www.rheinmetall-defence.com/index.p...47&lang=3&pdb=1
10. Diamond, P., Electro Thermal Chemical Gun Technology Study, MITRE, March 1999, p. 5.
11. Kruse, Dr. Josef and Weise, Dr. Thomas, Studies on Germany’s Future 140mm Tank Gun Systems – Conventional and ETC -, 34th Gun & Ammunition Symposium & Exhibition, 26 April 1999, p. 12.
12. Horst, Albert W., et. al., Recent advances in anti-armor technology, American Institute of Aeronautics and Astronautics, Inc., January 1997, p. 18.
13. Pengelley, Rupert, A new era in tank man armament: the options multiply, Janes International Defense Review,11/1989, p. 1522.
14. Ibid.
15. Sharoni, Asher H. and Bacon, Lwarence D., The Future Combat System, Part Two: Armament, ARMOR Magazine, September 1997, p. 29.
16. Schnellbacher, U. and Jerchel, M., Leopard 2 Main Battle Tank 1979-1998, Osprey Publishing, pp. 24-36.
17. Hilmes, Rolf, Arming Future MBTs – Some Considerations, Military Technology, December 2004, p. 76.
18. It should be considered that there exists plans to integrate the XM291 or XM36 tank guns into existing armoured vehicles, and the XM36 will be used in the future combat system line-of-sight gun vehicle. This technology may be spiralled down to the M1 Abrams in a M1A3 upgrade. Dyvik, Jahn, et. al., Recent Activities in Electrothermal Chemical Launcher Technologies at BAE Systems, IEEE Transactions on Magnetics, January 2007.
19. Sauerwein, Brigitte, Rheinmetall’s NPzK, Janes International Defense Review, 2/1990
20. Warford, Jim, The Resurrection of Russian Armor: Surprises from Siberia, ARMOR Magazine, 1 September 1998, p. 32.
21. Green, Michael, M1 Abrams at War, Zenith Press, 2005, pp. 25-28.
22. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
23. Maxwell, David, New Tanks For Old, Part II: Tank Top Upgrades, Armada International, June 2002, p. 82.
24. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
25. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 137.
26. The Osprey book only gives the weight of the Leopard 2A4. The Leopard 2E is, in any case, more or less the same as the Leopard 2A6M and the Swedish Strv. 121 (the Swedish vehicle doesn’t offer the L/55 main gun, however). Candil, Antonio J., Leopard 2 daneses en Córdoba, Fuerzas Terrestres, Vol. 3º, N.º 36, Año III, p. 62.
27. Lathrop, R., and McDonald, J., M60 Main Battle Tank 1960-91, Osprey Publishing, 2003, p. 28.
28. Green, Michael, M1 Abrams at War, Zenith Press, 2005, p. 31.
29. Ogorkiewicz, R.M., AMX-30 Battle Tank, Profile Publications Limited, December 1973, p. 12.
30. Zahn, Brian R., The Future Combat System: Minimizing Risk While Maximizing Capability, USAWC Strategy Research Project, p. 24.
31. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
32. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 103.
33. Ibid., p. 141.
34. Huntiller, Mark, New Turret a New Tank Make?, Armada International, March 2004, p. 22. Information on Falcon turret is from this article.
35. Maxwell, David, New Tanks For Old, Part II: Tank Top Upgrades, Armada International, June 2002, p. 82.
36. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 133.
37. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
38. Sharoni, Asher H. and Bacon, Lwarence D., The Future Combat System, Part Three: Powering the new system, ARMOR Magazine, January 1998, p. 37.
39. Held, Manfred, Warhead Hit Distribution on Main Battle Tanks in the Gulf War, Journal of Battlefield Technology, March 2000, p. 7.
40. Baryatinskiy, Mikhail, Main Battle Tank T-80 (Russian Armor), Ian Allen Publishing, 2007, p. 93
41. Lakowski, Paul, Armor Technology.
42. Robb McLeod, Modern Explosive Reactive Armours, Russianarmor.info, 1998.
43. http://www.drdo.org/pub/techfocus/feb04/explosive.htm
44. M1A2 armor estimates taken from: Lakowski, Paul, Armor Technology.
45. Warford, Jim, The Resurrection of Russian Armor: Surprises from Siberia, ARMOR Magazine, 1 September 1998, p. 31.
46. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
47. http://www.mtu-online.com/en/appl/applmili/applmilicomb/
48. Compact Power Plants, DaimlerChrysler High Tech Report, February 2004.
49. Armor will be discussed in a future Informative.
50. Ogorkiewicz, R.M., AMX-30 Battle Tank, Profile Publications Limited, December 1973, p. 6.
51. Jerchel, Michael, Leopard 1 Main Battle Tank 1965-1995, Osprey Publishing, 1995, p. 3.
52. Zahn, Brian R., The Future Combat System: Minimizing Risk While Maximizing Capability, USAWC Strategy Research Project, p. 13.
53. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 192.
54. Joseph, Mallika, Arjun: India’s Main Battle Tank, Institute of Peace and Conflict Studies, June 2006, p. 2.
55. To be explained in greater detail in future Informatives.
56. http://63.99.108.76/forums/index.php?showtopic=18511
57. Held, Bruce J., Tomorrow’s Smart Tank Munitions, ARMOR Magazine, March 1995, p. 22.
58. http://www.globalsecurity.org/military/sys...ions/sadarm.htm
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Postby The Macabees » Thu Mar 16, 2017 11:46 am

Large Caliber Tank Guns for Lightweight Platforms


The gun versus armor dilemma regarding the evolution of tank design has catalyzed a trend to increase gun caliber in order to enhance lethality. Tank technology has witnessed this trend since the beginning of tank warfare during the First World War, but truly began to take-off in the late-1930s. For example, during the Spanish Civil War national Panzer Is, supplied to Franco’s forces by Hitler’s Third Reich, found themselves outgunned by the Soviet Union’s larger T-26s. Although during the opening armor clashes of the war during the Battle of Madrid Panzer Is found it suitable to use 7.92mm armor-piercing ammunition at a maximum of 150m range, Republican T-26s responded by engaging at longer ranges, up to 1,000m. The Panzer I’s light 7.92mm MG13 machine gun was not capable of penetrating the T-26’s steel armor plating at long-.ranges, while the T-26 could easily engage and defeat the Panzer I at almost a kilometer using their 45mm high velocity artillery cannons. Consequently, the National Front attempted to exchange the armament with an Italian 20mm model 35 anti-aircraft gun, which could penetrate 40mm of steel at 250m range. There were even attempts to fit a Panzer I with 37mm and 45mm anti-tank guns, although these failed at the drawing board. 1 The process of increasing lethality continued during the 1930s, to the point where Germany’s Panzer IIIs were armed with 37mm tank guns. During the Second World War, the process of increasing gun caliber escalated and six years of war saw the evolution of the tank gun from 37mm to up to 128mm! 2

The end of the war saw the division of the world into two separate camps, led by the United States and by the Soviet Union. The West consolidated unto one caliber – the 90mm gun which was mounted on the Pershing tank and early modernizations thereof (M46, M47 and M48, for example). The Soviet Union left the war with the 122mm gun on the Stalin tank series, and the 85mm gun on their T-34/85s. Although some prototypes of the T-44 were armed with 100mm guns (and others with 122mm guns), the first series mass production of a 100mm armed tank began with the T-54 in 1947. 3 NATO’s L7 rifled 105mm gun, of British design, was adopted due to a first-hand glimpse of the tank when a Hungarian rebel drove a T-54 onto Budapest’s British embassy. 4 The cold war saw a slower pace of gun evolution, but the Soviets quickly introduced the 115mm tank-gun on early versions of the T-64, when an Iranian M60 defected to the Soviet Union, and then a 125mm gun thereafter. NATO continued to use the 105mm gun until the late 1970s when the Leopard 2 began series production with Rheinmetall’s 120mm L/44 tank gun. It should be noted that there were heavy tank designs in both the Soviet Union and the West with 122mm and 120mm tank-guns, but these are a different class of vehicles and were not produces on the same scale as medium tanks. Although the United Kingdom decided to go with the L11 rifled 120mm gun on the Challenger main battle tank (the same gun which was fielded on their Chieftain), the 120mm caliber in general took over the 105mm in all NATO tank-producing countries (United Kingdom, Germany, Italy and the United States) by the mid-1980s. Since then, there has been no enlarging of caliber and instead nations are focusing on improving the 120mm tank gun with revolutionary technologies.5,6No nation has employed the mythical 135mm and 140mm tank-guns in a series-production vehicle to date.

The fall of the Soviet Union in 1991 marked the beginning of new defense policies in NATO. Large and heavy main battle tanks were no longer considered relevant for national defense, and with the demise of the colossal Soviet Army large tank fleets became hard to justify given the required costs of maintenance and procurement. As a direct consequence, several future tank programs were cancelled – such as the Leopard 3 and the Block III Abrams. Instead, nations have begun to focus more on the development of air mobile resources to quickly deploy to trouble spots. These requirements have been magnified with recent operations in Bosnia, Kosovo, Lebanon, Afghanistan and Iraq. Although nations like the United States still perform large-scale invasions (Iraq 1991 and Iraq 2003), most armies no longer require the shock effect of heavy tanks and instead have to focus on easily deployed, yet still powerful airmobile vehicles. The problem is that infantry combat vehicles such as Spain’s Pizarro or Sweden’s CV90-30 don’t have the firepower for direct infantry support, like a tank does. This problem is much more evident in nations that have chosen to completely replace their tank fleet, like Belgium. As a consequence, nations have begun to develop light airmobile tanks based on infantry combat vehicle chassis.

Although such vehicles may never completely replace the main battle tank, they are much more favorable for procurement. To give a rough idea, it costs roughly five to six million euros to purchase a Leopard 2A6 in bulk, while it costs over eight million to purchase a tank which has been produced in lesser quantities (such as the Italian Ariete or the French Leclerc). 7 A future tank will cost at the very least double of what it currently costs. 8 At an early production rate, for example, the non-line of sight cannon (NLOS) will cost over twenty-five million U.S. dollars per vehicle! 9 Although, currently, a state-of-the-art light tank will cost just as much (or possibly more) than main battle tanks from the 1980s,10 they are considerably cheaper than main battle tanks of the same generation. Furthermore, their costs are more easily justified given that a light tank is designed with the ability to fit in a specified tactical transport (in Europe’s case the A400M and in the U. S.’ case the C-130 Hercules), while a main battle tank has only limited aerial transport capabilities in heavy strategic transport aircraft (such as the C-5 Galaxy).

They don’t necessarily need to be considered replacements for the main battle tank, although Belgium has replaced her Leopard 1s with wheeled Piranha armored fighting vehicles and at one point Canada was contemplating the replacement of her Leopard 1C2s with the LAV Stryker mobile gun system. Nations like the United States will mix ‘light brigades’ with ‘heavy brigades’, using them for different missions. Nations like Spain, Denmark or Germany are interested in heavy tanks like their Leopard 2A6s for national defense and for unmatched ground support in the field of survivability, but they’re also looking for lighter alternatives for quick reaction forces to quickly deploy contingents to trouble spots like Afghanistan, Bosnia or Kosovo. In that sense, the two can work in the same army. The United States has deployed mobile gun systems for direct infantry support, to work alongside wheeled armored personnel carriers. The Italian’s have procured large numbers of their Centauro armored fighting vehicles, in the twenty-four ton class, in order to perform cavalry missions and area security missions during peacekeeping operations.22 Their preference is exhibited by the large amounts of orders various nations have placed for these types of vehicles and the amount of money and time spent on further developments and upgrades.

In that sense, in the past seven years defense businesses have worked ‘night-and-day’ to provide lethality improvement options for existing and future armored fighting vehicles. One of the most important areas being developed upon is lethality, and recently several new large-caliber tank guns have been advertised for integration into lightweight armored fighting vehicles between eighteen and thirty tons. These new armaments allow light armored fighting vehicles the same lethality as a main battle tank in the sixty ton class. Understandably, large caliber high velocity cannons produce high recoil forces and the increase in recoil is exponential as gun caliber increases. Consequently, the major areas of improvement remain reducing recoil mass and force and reducing the unbalance of the gun and vehicle during firing.

105mm low-recoil tank guns
Some of the better known 105mm tank-guns are Rheinmetall’s Rh-105-20 and Rh-105-30 series, based on the British L7A3 which had been accepted for service on the Leopard 1. However, these new Rheinmetall 105mm guns have exchanged the rifling of the L7 for the smoothbore of Rheinmetall’s 120mm guns. This, in combination with the use of chromo lining along the inner walls of the barrel, allows the gun to withstand bore pressures of 680MPa, up from 525MPa. The system’s weight has been decreased to 1,550kg through the use of innovative changes in the breech design. Most importantly, the recoil force felt by the vehicle has been reduced to 150kN, allowing the gun to be mounted on armored fighting vehicles of eighteen tons or more. The reduction in recoil has been established by allowing an extended recoil mechanism length of 750mm and by adopting a Rheinmetall specific advanced pepperbox muzzle break. The muzzle break reportedly does no damage to fin-stabilized projectiles by harming the fins and reduces the noise produced through lateral gas venting. The new 105mm series of guns by Rheinmetall can fire new German 105mm APFSDS at a muzzle velocity of 1,700m/s and these rounds can penetrate up to 560mm of rolled homogenous steel (RHA) at 1km, allowing the gun to defeat the T-72’s frontal arc.12,13

The LAV Stryker mobile gun system (MGS) is currently armed with the M68A1 105mm rifled gun, based on the British L7, which have been recycled from earlier use on M1 Abrams. Early models of the gun featured a pepperbox muzzle break, but high noise production threatened the safety of dismounted infantry and as a consequence deployed Stryker mobile gun systems don’t feature a muzzle break on their M68 105mm guns. In that sense, Rheinmetall’s new smoothbore 105mm guns might present an option for a future improvement program. United Defense, now owned by BAE Systems, developed the M35 low-recoil gun for the M8 armored gun system, now defunct.14 The aluminum turret means that the recoil force imparted by the gun had to be low enough to not damage the structure. As mentioned, the M8 program was canceled in the mid-90s and has not successfully been exported. Currently, the program continues within the Lightning Bolt II and a low-recoil 120mm gun.

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Perhaps one of the most interesting new 105mm gun options is Cockerill’s 105mm CV tank gun. The new gun is bedded to a new CMI turret, weighing only 4.5 tons. At 52 calibers in length, the gun keeps the same bore geometry as the British L7 and therefore is compatible with all existing 105mm ammunition for rifled guns. Recoil is reduced through a very efficient muzzle break (70% efficiency) and an extended recoil length of 580mm. That said, the recoil force is the same as Rheinmetall’s 105mm options – 150kN. Furthermore, the new turret is designed to fit inside of a C-130.15 Fired from the 105mm CV the new Mecar 105mm M1060 APFSDS has a muzzle velocity of 1,520-1,560m/s and at 2km can penetrate 510mm of rolled homogenous armor at 60º obliquity (460mm at 0º obliquity).16 The new turret may replace the 90mm gun turret currently on Belgium’s MOWAG Piranha IIIC, which replaced their Leopard 1BEs. On the Piranha the 105mm gun turret can carry sixteen 105mm rounds at ready, and the autoloader can load six to eight rounds per minute. Very importantly, the gun can elevate up to 42º in the new turret.17

Other 105mm guns have been developed around the world. The South African company Denel offers the GT3 105mm gun, weighing roughly 2,900kg. India’s Ordnance Factory Kanpur offers a 1,287kg 105mm gun to upgrade T-54s and T-55s. This new gun is based on the British L7 and is rifled, and has an effective range of 4km. BAE systems itself is offering a new improvement of the L7, now 6.66m in length and weighing only 1,334kg.18

120mm low-recoil designs
Rheinmetall, apart from their new series of 105mm guns, offer the 120mm L/47 lightweight low-recoil (LLR) tank gun. The system is designed to fit on vehicles of the twenty-five ton class and keep compatibility with A400M transportation.19 France’s Nexter has introduced their new 120mm L/52 FER (Faible Effect du Recul) low-recoil tank-gun designed to be adopted by vehicles of the twenty-five ton class, such as the future French EBRC armored car. The 120 FER has a twin-chamber muzzle brake and features a 550mm recoil length. These two guns are similar to Italy’s 120mm L/45 low-recoil tank gun designed by Oto Melara. The new pepperbox muzzle break and 550mm recoil length has reduced recoil mass to twenty-five tons, and the weapon is currently being offered for export on the Centauro 8x8 armored fighting vehicle on a new HITFIST turret. Denel offers the GT12 120mm gun for South Africa’s Rooikat wheeled armored fighting vehicle, which is currently armed with a 76mm gun. Israel will soon offer a low-recoil 120mm gun based on Slavin Land System’s MG253 for the Sabra main battle tank.20

One of the most successful low-recoil tank guns to date is Ruag’s 120mm compact tank gun (CTG). This gun is fifty calibers in length and has been improved with a muzzle break, having an efficiency of roughly 40%, and an increased extended recoil length – from 410mm to 500mm. Recoil mass has been decreased from 50 tons to 26 tons.21 Currently, Ruag’s 120mm CTG is being used to arm Jordan’s Falcon turret for their Al Hussein turret upgrade for the M60. The gun is matted to an unmanned (the crew is below the turret ring) narrow mantlet turret and a new autoloader which carries eleven rounds.22 It should be noted that the compact breech comes at a price of gained weight. Ruag’s gun system weighs 2,600kg compared to the 1,901kg of the M256 and the 1,100kg of Rheinmetall’s L/44. The same can be seen with Israel’s compact gun systems for their Sabra M60 upgrade – the M253, based on the M251 of the Merkava III, weighs 3,300kg. Currently, Norinco’s 120mm guns for possible T-55 upgrades weigh 2,600kg and France’s F1, used on the Leclerc, weighs 2,800kg.23 The Ruag 120mm CTG, originally designed for an indigenous Swedish main battle tank (ultimately canceled in favor of the Leopard 2A5), has also been chosen to arm the upcoming CV90120-T light tank, based on the CV9030 infantry combat vehicle. The system carries twelve ready-rounds and a further thirty-three can be stowed at the rear of the chassis.24

The United States is currently testing the XM291 lightweight low-recoil tank gun, originally developed in the late 1980s. Originally, the XM291 was composed of a dual-caliber breech which accepted both 120mm and 140mm ammunition. If NATO decided to accept a 140mm gun the gun tube could be exchanged for one of the 140mm diameter, making the transition cheaper. The XM291 was simply an interim solution that increased the lethality of the existing M256 by increasing the length of the gun tube and made possible the transition to a 140mm caliber.25 At some point in the late 1990s the XM291 was turned into a technology demonstrator for an electrothermal-chemical tank gun. In late 1999 the XM291 demonstrator showed that it was coming close to achieving its goal of 16MJ at the muzzle using a M289A2 APFSDS.26 Despite this enormous power, the XM291 can be mounted on the 18.7 ton Lightning Bolt II light tank, based on the M8 chassis.27 The XM36, which will see prototypes delivered by 2009, is supposed to surpass the abilities of the XM291 and will be mounted on the twenty-five ton non-line of sight cannon future combat system.28 The recent developments on the XM291 has been discussed in other Informatives.29

Image


Some considerations on large caliber guns for lightweight vehicles
Light-caliber guns have their own limitations based on the different requirements of any given armored fighting vehicle. These requirements include weight, volume, operational area, et cetera. While there may be a multitude of arrangements for a low-recoil tank gun, including high-lengths, low weights or compactness of the breech, not all of these may be useful on a certain design, depending on the criteria. If the light tank is designed to provide infantry support in an urban environment – such as Iraq – or a forested or mountainous environment – like Afghanistan – then long guns may be a detriment to the design. Longer guns limit the ability for a vehicle to turn into a narrow street, or even ride through one, given that the length of the gun might make it impossible to traverse the turret given the threat of the gun tube hitting a building. On the other hand, light armored vehicles designed to provide a nation a light anti-tank platform, like the Italian Centauro or Belgium’s Piranha IIIC, might require longer guns to allow for higher muzzle velocities and muzzle energies in order to kill enemy tanks in a one on one basis. Therefore, the length of the gun tube should be based entirely on the design requirements of the vehicle, not just to enhance lethality.

Compact tank breeches pay the price in weight, and although they’re great for lower volume turrets they can weigh two to three times the weight of a standard 120mm gun breech. It’s true that a lower volume turret will save weight in the lost armored volume, so a designer must look at all the aspects and wisely juxtapose the possible losses in armored weight and the gained gun weight. You might be surprised to find out that although you did lose weight in armor you gained it all back, or more, through the use of a 3,000kg+ tank gun. 2,000kg is what it would weigh to add appliqué MEXAS to Spain’s Pizarro infantry combat vehicle to increase protection from 14.5mm API to 30mm APFSDS, just as a reference.

In regards to recoil reduction methods, there are trade-offs. Extra room has to be made to allow for the increase in extended recoil length by 100 to 300mm, meaning that if turret roof height is kept the same in relation to the height between the turret roof and the top of the gun breech then the ability to depress will be traded-off. There has to be enough room between the end of the breech and the roof to allow for the recoil mechanism to fully extend, or else the recoil mechanism is going to end up hitting the roof itself and will damage both the gun and the tank. Muzzle breaks have a tendency to damage the fins of fin s stabilized projectiles, so they should be used with caution. The minor damage done can induce yaw on the round, decrease muzzle velocity and muzzle energy. It’s difficult to design a fire control system that takes into consideration these aspects because they can be completely random. After the round has been fired there’s no way for the fire control system to correct the path of the round, and so when yaw has been induced it can’t be fixed. However, new muzzle break technology has allowed to reduce the damage on fins, and according to Rheinmetall – as related above – the new generation of pepperbox muzzle breaks used by Rheinmetall’s current generation low-recoil guns have little to no effect on fin-stabilized ammunition. Muzzle breaks also produce high amounts of noise, which can damage the eardrums of nearby infantrymen, and so this must be taken into account when designing a fire support vehicle. As told above, the Stryker mobile gun system had its muzzle break removed due to this problem.

In other words, the real world advancements in low recoil tank guns have made it possible to play with these technologies on NationStates. But, it shouldn’t be forgotten that there are always trade-offs and prices to pay.

Limitation of light armored fighting vehicles against main battle tanks
While speaking about the comparative lethality of a light armored fighting vehicle armed with a large-caliber gun one can conclude that on the level of firepower the main battle tank has been compromised. This is somewhat true, of course, but the technology applied to these guns can be applied to main battle tanks, as well. If a 120mm gun that originally produced 50 tons worth of recoil has been improved to reduce recoil, then that recoil force can be augmented through the use of larger propellant masses – as if to achieve hypervelocity, although ideally once the maximum effective velocity is reached energy should be translated more into mass of the round. Of course, such a gun is bound to weigh more than the original given that the barrel has to be strengthened to withstand higher bore pressures from large propellants. Nevertheless, the power concepts for a similar technology smoothbore gun for a sixty ton chassis are interesting. Alternatively, low-recoil guns will allow weight decreases in main battle tanks through the adoption of better armor materials and through a smarter distribution of armored mass.

Image


More importantly (and perhaps more realistically) light armored fighting vehicles can’t compete on the level of armor protection. Most modern infantry combat vehicles are designed to withstand hits from 30mm APFSDS, while a main battle tank’s frontal armor array is designed to withstand fire from 105mm or 120mm ammunition. All the while, modern tanks are designated hunter-killers – they have been forged as dedicated tank killing machines – and the role of the large-caliber lightweight armored vehicle doesn’t prioritize this over more pertinent missions such as infantry support. Consequently, the digital architecture of a lightweight armored gun system will be radically different from that of an advanced tank such as the Leopard 2A6 or the M1A2 SEP. In this sense, lightweight armored fighting vehicles can’t hope of taking on enemy tanks on a one-on-one basis with any semblance of parity. So, generally speaking a vehicle like the Centauro will not replace the tank in the short term. The only hopes of this will come through revolutionary technologies, such as extremely lightweight armor which will make possible armor protection levels superior to that of current sixty-ton beasts on a twenty-ton vehicle. Unfortunately, all of this also comes with increased cost penalties.

But then one can ask, what about Belgium? Belgium was the first country to procure the Leopard 1 and the first Leopard 1BEs were delivered in 1968.30 It’s possible that German defense companies were no longer able to supply spare parts to the Leopard 1, or the decreased demand as more and more nations replaced old Leopard tanks with newer Leopard 2s made it uneconomical to continue mass production of spare parts. A similar problem catalyzed Canada’s decision to purchase ex-Dutch Leopard 2A4s and Leopard 2A6s to replace their ageing Leopard 1C2s. For a country like Belgium, with little fears of getting into a war where a heavy main battle tank would be justified, Leopard 2s are too expensive to purchase and too expensive to maintain. Consequently, a light tank force makes much more sense as Belgium operates almost exclusively in peacekeeping operations. That said, these are cheaper and therefore offer a solution to nations with no interests in maintaining a large heavy tank fleet. They are also more versatile for a nation like Belgium, which requires lightweight air mobile units to deploy across large distances – not to mention, lighter vehicles which can fly on tactical aircraft like the C-130 or the A400M make more sense for the independence to deploy when wanted instead of having to use allied strategic heavy lifters.

There are probably dozens of different advantages of lightweight heavily armed armored fighting vehicles. It just requires imagination and understanding of the differences between this and a main battle tank.

Conclusions
The need for lightweight firepower has led to the development of a number of lightweight, low-recoil guns in the real world. These can provide a basis for gun development in NationStates, both for lightweight vehicles and for main battle tanks. Furthermore, it’s increasingly likely that we will see a much larger population of low-recoil guns to study from in the future.






Notes

1. Franco, Lucas Molina, Panzer I: El Inicio de Una Saga, AF Editores, 2005, pp. 47-50.
2. Referring to the 128mm tank-gun on the German Jagdtiger.
3. Zaloga, Steven J., T-54 and T-55 Main Battle Tanks 1944-2004, Osprey Publishing, 2004, p. 6.
4. Ibid., p. 39.
5. Problems Encountered with Higher Caliber Tank Guns
6. Problems Encountered with Higher Caliber Tank Guns
7. Mallika, Joseph, Arjun: India’s Main Battle Tank (MBT) From T-80 to Next-Generation, Institute of Peace and Conflict Studies, p. 2.
8. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, June 1999.
9. U.S. Army to Buy 18 NLOS Cannons Separately From FCS, Defense News
10. Greece’s BMPs were around 5 million per unit according to: [insert link]
11. Fiorentino, Sergio (Col.), Light Armor Units: An Italian Perspective, ARMOR Magazine, July 1995, p. 31.
12. Hilmes, Rolf, Development Trends in Tank Armament, Military Technology, March 2007, p. 89.
13. 105 mm Tank Guns - Rh 105-20 / Rh 105-30
14. Kemp, Ian, Big Guns, Small Platforms, Armada International, June 2006, pp. 8-9.
15. Hilmes, Rolf, Arming Future MBTs – Some Considerations, Military Technology, December 2004, p. 78.
16. Foss, Christopher F., Mecar displays 105mm rounds, Janes Defense Weekly, 9 June 2004, p. 29.
17. Kemp, Ian, Big Guns, Small Platforms, Armada International, June 2006, p. 12.
18. Maxwell, David, New Tanks for Old, Part II: Tank Top Upgrades, Armada International, June 2002, p. 82.
19. Hilmes, Rolf, Development Trends in Tank Armament, Military Technology, March 2007, p. 89.
20. Hilmes, Rolf, Arming Future MBTs – Some Considerations, Military Technology, December 2004, p. 78.
21. Ibid.
22. Huntiller, Mark, Does a New Turret a New Tank Make, Armada International, June 2004, p. 22.
23. Maxwell, David, New Tanks for Old, Part II: Tank Top Upgrades, Armada International, June 2002, p. 82.
24. Kemp, Ian, Big Guns, Small Platforms, Armada International, June 2006, p. 12.
25. Pengelley, Rupert, A new era in tank armament: the options multiply, Janes International Defense News, November 1989, p. 1522.
26. Diamond, P., Electro Thermal Chemical Gun Technology Study, MITRE, March 1999, p. 5.
27. Hilmes, Rolf, Development Trends in Tank Armament, Military Technology, March 2007, p. 89.
28. Kemp, Ian, Big Guns, Small Platforms, Armada International, June 2006, p. 9.
29. Electrothermal-Chemical Technology for Tank Gun Propulsion
30. Jerchel, Michael, Leopard 1 Main Battle Tank 1965-1995, Osprey Publishing, 1995, p. 19.
Last edited by The Macabees on Thu Mar 16, 2017 11:49 am, edited 1 time in total.

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Postby The Macabees » Thu Mar 16, 2017 11:47 am

Electrothermal-Chemical Technology for Tank Gun Propulsion


Although the NATO 120mm gun is deemed sufficient to defeat current tank threats, and was considered powerful enough to defeat the Future Soviet Tank One (FST-1) – or the T-72B and the T-80U1 -, according to studies researched in Switzerland, and various other countries, the future tank will require a gun producing 18MJ of muzzle energy to defeat the future threat.2 Starting in the late 1980s, various armament companies began to research into a number of alternative designs to enhance the lethality of the future tank. The easiest improvement was in the shape of the 140mm tank gun, but to keep a proportional amount of ammunition and equipment as in existing main battle tanks the turret had to be enlarged. Consequently, research into more advanced propulsion systems continued and the 140mm tank gun was considered as an interim solution. Fortunately, the fall of the Soviet Union in 1991 allowed Western nations to slow down their research and allowed them to completely discard the 140mm as an option. Since then, research on future lethality programs has slowed down as nations find it harder and harder as nations find it difficult to justify given the lack of an existing threat.3 In fact, nations have found it difficult to justify the continuation of their own tank production plants given the questioning of the raison d’etre of the main battle tank – for example, the Challenger 2 production line has ended given poor export potential, and the United Kingdom’s Ministry of Defense has recently decided to adopt Rheinmetall’s 120mm L/55 tank gun and end production of the indigenous L30 line of 120mm rifled guns.4 Instead, development has been centered on the improved lethality of light armored fighting vehicles, and includes the introduction of a number of low-recoil 105mm and 120mm guns.5 Defense companies have also found it far more profitable to design new lightweight and compact tank guns to modernize the tens of thousands6 of obsolete tanks fielded by third-world nations (although many of these nations are soon to become very powerful first world nations – BRIC [Brazil, Russia, India and China]).7

Although development of future tank guns is now continuing with a slow pace, already results are being seen. The electrothermal-chemical (ETC) gun looks like the most rewarding alternate propulsion system, and the fastest to see application. In fact, Nexter’s 120 FER 120mm L/52 low-recoil gun – a modification of the existing F1 120mm gun mounted on the Leclerc main battle tank8 - (meant for vehicles in the twenty-five metric ton class) is compatible with electrothermal-chemical ammunition.9 In other words, electrothermal-chemical technology can be applied to lightweight armored fighting vehicle, so that in the event of the loss of interest in main battle tanks the technology can be applied to the wide array of existing tank-destroyers. It should be noted that the XM36/360 next-generation 120 mm guns, which is electrothermal-chemical capable, is intended to be mounted in the twenty-five ton Mounted Combat System (MCS), which will replace the M1 main battle tank.10 This technology may be spiraled down to the M1 in order to extend the service life of the seventy ton main battle tank, especially if the MCS fails to meet expectations. Two XM36 prototypes will be delivered by 2009, with firing trials expected between 2010 and 2011.11 It should be pointed out that previous light airmobile vehicles were eventual canceled, and these vehicles had much less expectations to meet than the systems of the Future Combat System (FCS), of which the MCS forms part of.12

Image
XM291 solid propellant dual-caliber gun mounted on M1A1 Abrams.


The Hows and Whys
The electrothermal-chemical (ETC) gun is born from the concept of the electrothermal (ET) gun. ET technology began to be researched in the mid-80s by the United States, Germany and France. Unfortunately, ET technology requires a large amount of energy to initiate the combustion process of the propellant. Assuming 30% electrical efficiency, a gun producing 20MJ worth of muzzle energy will require a 70MJ power pack for each round.13 On the other hand, in 1995 Rheinmetall set up a laboratory with an ET 105mm gun and successfully fired 2kg rounds at a velocity of 2,393m/s (5.4MJ of muzzle energy) with an electrical efficiency of 80%! However, the gun required a 30MJ power pack and had a system efficiency of only 18.1% at full power.14 In fact, system efficiency decreased as electrical energy required increased. As a consequence, electrothermal-chemical technology was introduced and preferred since it required very little electrical power and had a superior electrical efficiency.15 For example, BAE’s XM291 demonstrator requires less than 100kJ of energy per round, as opposed to the 30MJ required for an ET gun.16

Image
Concept art of an ETC gun done by Mekugi.


Theoretically, electrothermal-chemical gun propulsion is a simple process. ETC uses a plasma-producing cartridge to ignite a high-density propellant in a ‘controlled manner’.17 In other words, the energy of the propellant – in real world cases it should be assumed that the propellant is a high-density solid propellant – is released through a methodical combustion process catalyzed by the use of a plasma device. The principle goal remains to match the ballistics of a 140mm solid-propellant gun, and ultimately to surpass it. In real-world ETC guns plasma initiation is normally provided by a flashboard large area emitter (FLARE), which work by vaporizing and ionizing short gaps between metal diamonds (such as copper) over long strings. A return conductor drives the created plasma towards a vacuum, which is ideally towards the propellant of the round. The solid propellant is catalyzed by a mix of the plasma and heat radiation, convection and conduction. FLAREs have largely replaced triple coaxial plasma igniters (TCPI) since the latter are not volume efficient and are hard to pack around the propellant, and it has a history of damaging stabilization fins for ammunition designed for smoothbore guns.18 It’s entirely possible that FLARE igniters have been replaced recently, or that the coming XM36 will have a new plasma emitter. As a consequence, FLAREs shouldn’t be used as the end-all be-all for plasma technology in ETC application. To be completely honest, information on the emitter technology can be considered superfluous of the design and the lack of understanding about it makes it improper to describe in a write-up, since the author of the write-up would simply be trying to justify the superiority of the design. In other words, an author which uses FLARE and tries to describe it might be describing an entirely antiquated piece of technology.

ETC technology also relies on more efficient solid propellants which can deliver more energy per square gram of volume. These include temperature-independent propellants, like the propellant used by Germany’s new DM63 120mm APFSDS. Modern gun tubes are designed to tolerate the pressure generated by a given propellant for the round in use at 50º C, meaning the higher the temperature the more efficient than expansion of the propellant. Therefore, one can conclude that at lower temperatures produce lower propellant gas expansion pressures, and so the propellant doesn’t expand to its maximum potential. Surface Coated Double Base (SCDB) propellants produce a constant pressure, regardless of the ambient temperature, improving accuracy (fire control system no longer needs an accurate read on ambient temperature inside the gun chamber and barrel) and reduces barrel wear.19 In the late 90s there was a lot work done one modular propellants, including the modular charge and the unicharge. The former works by using propellant sticks or granular charges held within combustible nitrocellulose cases which could be joined together to create a charge of the desired volume. The latter is a more advanced version of the former, with each module being exactly the same and being completely independent of other charges, even if multiple charges are attached together. Low vulnerability (LOVA) propellants are designed to decrease the chances of an explosive chain-reaction if the propellant is breached.20

Image
Red is the DM53's propellant and blue is the SCDB powders used by the DM64.


LOVA propellants exchange classical ingredients for more modern chemical compositions. For example, the use of RDX allows for a much smoother rate of gas expansion and has a suitable flame temperature (ca. 3,100 K). Exchanging materials like Di-Octyl Phthalate (DOP) with Glycidyl Azide Polymer (GAP) increases thermal stability, burn rate and decreases temperature sensibility.21 Used is a conventional solid propellant smoothbore gun, a LOVA propellant could increase muzzle velocity by anywhere between 50 to 100 m/s!22 Problems persist, however, with gun barrel erosion due to higher barrel pressures and the high flame temperature.23 Ideally, controlled burning of the propellant can decrease harm done to the barrel by a LOVA propellant.

There are more ambitious ETC improvement programs, including the Electromagnetic-Chemical (EMC) concept. The concept uses a magnetic flux compression generator (MFCG) which is a fancy description of an electric generator that creates the electricity required to propel a round down the tube through a magnetic field. The use of parallel rails is avoided, and instead the actual round only touches a number of parallel insulators and the current is conducted through two wide busbars which have no contact with the projectile. Propellant reactions along the way provide gas pressure to move the projectile down the barrel, with the electrical current, and through a magnetic flux the chemical energy is converted into electric energy. The ultimate idea is to decrease the amount of energy required at input to create an appropriate level of muzzle energy – ideally, a fraction of the muzzle energy would be required in electrical energy. Apart from tank guns, the technology has also been proposed for space launch, artillery and missile defense. One of the most interesting proposals is inter-continental nuclear artillery through the use of this technology and unguided shells. It’s clear, however, that this technology is currently not appropriately developed for realistic use within the coming decade, or perhaps even decades.24

On the other hand, ETC technology is near ready to be used on next-generation tank armaments and artillery howitzers. Advanced ETC guns in the large-caliber spectrum have seen heavy development in the past two decades.

Electrothermal-Chemical Development around the World
The South Koreas are one of the East Asian nations experimenting with ETC technology, and have tested a number of weapons incorporating the technology in the medium-caliber range. In late-2000 and early-2001 the South Koreans conducted a number of tests with a 30mm electrothermal-chemical gun. The ammunition used is based on existing 30mm projectiles, and incorporates a copper wire in an arc through the propellant of the round. The discharge of the capacitors of the gun system give an electric impulse which forms a plasma around the copper wire, consequently igniting the propellant. At the time, the system required electrical pulses of 400kJ and required forty-eight 50kJ capacitors. Thereafter, the South Koreans have been testing pulsed power systems to deliver 100kJ of energy to a new projectile. South Korean scientists have hopes of the creation of a larger-caliber ETC gun in the tank-gun range.25

Image
German 120mm ETC prototype.


The Germans have developed a number of plasma ignition systems. The Plasma Jet Ignition system uses a ‘plasmaburner’ located in the chamber of the gun to provide a plasma jet through an electrical impulse which ignites and controls the ammunition’s propellant. The Plasma Surface Ignition system, instead, is set-up around the ammunition’s propellant itself and so is contained by the ammunition cartridge, allowing for high loading densities of solid propellants. Plasma Channel Ignition is set-up in a similar fashion, but is catalyzed by both electricity and the interaction between separate plasma channels around the propellant stick. German scientists have tested these ignition processes with new propellant formulations (NENA), including LOVA propellants. During tests with a 105mm ETC gun conducted in the early 21st century, the Germans managed to fire 4.2kg projectiles at 1,800m/s and these required high energy input. Using LOVA propellants the same projectile was later fired at 1,900m/s. Tests with a 120mm L/55 gun have also been done using 8.4kg projectiles. The 8.4kg round was fired with a muzzle energy of 14MJ and required only 39kJ worth of electrical energy. Increasing electrical energy to about 101kJ increased muzzle velocity to 1,839m/s, with a muzzle energy of 14.1MJ.26 Improvements led to muzzle energy increases to 15MJ by 2003 and the creation of high density discharge capacitors (2 MJ/m3).27

The United States has had a fruitful investigation of ETC technology, led by BAE systems. Most recently, BAE systems tested several 120mm guns (XM291, XM36 and M256) on a Lightning Bolt II platform. In 2004 an ETC M256 120mm tank-gun fired eleven consecutive M829A2 ETI rounds using a pulsed power supply with a capacitors which store up to 2.2 J/c3, designed by General Atomics. Reducing the volume of the capacitor is important given that the capacitors form 24% of the volume of current portable pulsed power supplies (ETIPPS 1) and 27% of the weight. ETIPPS 1 also uses a high voltage charger with the ability to fire an ETI shot every five seconds (ETI refers to an ETC ignition system of 100kJ and under). The development of ETIPPS II simply splits ETIPPS 1 into two separate parts for integration into a combat vehicle (in this case, a Lightning Bolt II). The Lightning Bolt II is a modified M8 armored gun system with a 120mm ETC gun, and in 2004 it fired seven consecutive ETI rounds using ETIPPS II.28

Image
Lightning Bolt II with XM291 120mm ETC gun.


The United States has had a number of successes with ETC technologies over the years. In 2001 there was an increase of 30% in muzzle energy for a 35mm ETC gun and has even tested ETI cased telescoping ammunition (CTA) out of a 105mm ETC gun. Testing with the Thunder Bolt II vehicle in California in 2004 showed that the vehicle could fire at-least twelve consecutive rounds, and the vehicle also fired thirteen conventional rounds.29 In the late-1990s the XM291 ETC program had a goal to establish a muzzle energy of 17MJ using a 10.2kg projectile by the year 2000. According to information from 1999 the program was close to achieving that goal.30 This was before the integration of new propellants, such as LOVA, into American gun systems in 2002.31 It should be noted that ETC guns are not incompatible with low-weight vehicles. The Thunder Bolt II weighs 18.7 metric tons and the XM36 is being designed to be integrated into the lightweight line of sight (LOS) weapons platform for the future combat system (FCS) series.32 Two XM36 prototypes are scheduled to be delivered to the U.S. Army by 2009 for testing.

Areas of improvement
There are certain areas that will continue to receive improvement up to the series production of an ETC weapon, and even after. These areas include the subject of compact pulsed power supplies, superior plasma injectors and the reduction of the required electrical energy. There is at least one concept which exists to entirely solve the latter requirement – the electrothermal-chemical gun without a power supply. The concept replaces the electrical plasma igniter with an explosive plasma igniter arranged in the casing of the ammunition itself. A small high-explosive (HE) is arranged in a cylinder along with helium. The explosive shock-waves ionize the fluid helium creating a high-temperature plasma. Although the plasma injector will be larger than that of a conventional ETC gun, it theoretically would provide higher conversion efficiency and higher ballistic efficiency and would not require a pulsed power supply, saving volume and weight. Given the short life of the created plasma the expansion of the gas can’t be controlled, and so the propellant ballistics is inferior to that of a conventional ETC gun. It’s proposed that to provide superior ballistics the gun should use a large number of plasma igniters in the chamber, which will catalyze in a chain-reaction of sorts. The idea is entirely theoretical and hasn’t been actively tested.33 If such a system was ever tested to work in actual and physical application then it would save the troubles of developing a compact pulsed power supply. However, it’s entirely possible that the system will open up a new Pandora’s Box of questions without solutions.

Image
ETIPPS.


Electrothermal-chemical tank gun application
How can this technology be used? ETC gun propulsion has more uses than just on main battle tanks, and development efforts today continue to be based on the improvement of lightweight, air-transportable gun systems. Although armored gun vehicle requirements will vary from country to country and from war to war, lightweight airmobile armored vehicles are paramount for quick reaction forces which can be deployed anywhere at anytime. Main battle tanks of sixty tons do not fulfill these specifications, while light tanks based on infantry combat vehicle (ICV) chassis do34 and emerging ETC technology allows the application of extremely lethal armaments to lightweight vehicles. A prime example is the XM291’s mounting on the 18.7 ton Lightning Bolt II. ETC technology can also be applied to artillery systems on land and sea, infantry fighting vehicle autocannon systems and even aircraft ground attack gun systems (like the A-10s). Power requirements make it difficult to integrate ETC technology into small arms, and powerless concepts are too dangerous for such a small weapon. Propellant developments will allow improvements in assault rifle ballistics without jeopardizing the weapon’s weight by such a dramatic margin.

ETC can also make a powerful appearance in short-range air defense (SHORAD) in both ground vehicle application and as naval close-in weapon systems. Any system with an enhanced effective range will increase the available reaction time – even one or two extra seconds are important, considering that the system is designed to react and kill under two seconds.

It’s a matter of imagination and some research when it comes to integrating ETC technology into different weapon systems. Sanity is suggested and ETC grenades, turbines and missiles aren’t probably the best ideas!





Notes


1. Warford, James, The Resurrection of Russian Armor: Surprises from Siberia, ARMOR Magazine, September 1998, p. 30.
2. Zahn, Brian R. (Col.), The Future Combat System: Minimizing Risk While Maximizing Capability, USAWC Strategy Research Project, May 2000, p. 16.
3. Hilmes, Rolf, Development Trends in Tank Armament, Military Technology, March 2007, p. 88.
4. http://www.janes.com/news/defence/systems/...70525_1_n.shtml
5. Hilmes, Rolf, Arming Future MBTs – Some Considerations, Military Technology, December 2004, p. 75.
6. Rolf Hilmes, in Aspects of Future MBT Conception (Military Technology, 30 June 1999), estimates 45,000 earlier-generation tanks are fielded around the world.
7. Maxwell, David, Try on a 120mm For Size, Armada International, February 2003, p. 10-16.
8. Kemp, Ian, Big Guns, Small Platforms, Armada International, June 2006, p. 8.
9. I have to find that source!
10. Kemp, Ian, Big Guns, Small Platforms, Armada International, June 2006, p. 9.
11. Hilmes, Rolf, Development Trends in Tank Armament, Military Technology, March 2007, p. 89.
12. See: Thompson, Burdett K. (Maj.), Where’s the Light Armor? Enhancing the Firepower of Early Entry Forces, School of Advanced Military Studies, United States Command and General Staff College, Fort Leavenworth, Kansas, 1996.
13. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, June 1999.
14. Weise, Th.H.G.G., et. al., Setup and Performance of a 105mm Electrothermal Gun, IEEE Transaction on Magnetics, Vol. 33, No. 1, January 1997, pp. 345-347.
15. Sharoni, Asher H., and Bacon, Lawrence D., The Future Combat System (FCS), Part Two: Armament, ARMOR Magazine, September 1997, p. 29.
16. Dyvik, Jahn, et al., Recent Activities in Electrothermal Chemical Launch at BAE Systems, IEEE Transactions on Magnetics, Vol. 43, No. 1, January 2007, p. 304.
17. Diamond, P., Electro Thermal Chemical Gun Technology Study, MITRE, March 1999, p. 1.
18. Diamond, P., Electro Thermal Chemical Gun Technology Study, MITRE, March 1999, pp. 11-13.
19. Hilmes, Rolf, Development Trends in Tank Armament, Military Technology, March 2007, p. 93.
20. Maag, H.J., Gun Propulsion Concepts, Part II : Solid and Liquid Propellants, Propellants, Explosives and Pyrotechnics, Vol. 27, 1996, pp. 1-3.
21. Damse, Ramdas S. and Singh, Amarjit, High Energy Propellants for Advanced Gun Ammunition Based on RDX, GAP and TAGN Compositions, Propellants, Explosives and Pyrotechnics, Vol. 32, 2007, pp. 52-57.
22. Klingenberg, G., Gun Propulsion Concepts, Part I: Fundamentals, Propellants, Explosives and Pyrotechnics, Vol. 20, 1995, p- 307.
23. Maag, H.J., Gun Propulsion Concepts, Part II : Solid and Liquid Propellants, Propellants, Explosives and Pyrotechnics, Vol. 27, 1996, p- 3.
24. Dreizen, Yuri A., The electromagnetic chemical propulsion concept, IEEE Transaction on Magnetics, Vol. 31, No. 1, January 1995.
25. Jung, Jaewon, et. al., Overview of ETC Program in Korea, IEEE Transaction on Magnetics, Vol. 37, No. 1, January 2001.
26. Weise, Thomas H.G.G., et. al., Status and Results of the German R&D Program on ETC Technologies, IEEE Transaction on Magnetics, Vol. 37, No. 1, January 2001.
27. Weise, Thomas H.G.G., et. al., National Overview of the German ETC Programm, IEEE Transaction on Magnetics, Vol. 39, No. 1, January 2003.
28. Dyvik, Jahn, et al., Recent Activities in Electrothermal Chemical Launch at BAE Systems, IEEE Transactions on Magnetics, Vol. 43, No. 1, January 2007, p. 304.
29. Goodell, Brad., Electrothermal Chemical (ETC) Armament System Integration Into an Combat Vehicle , IEEE Transactions on Magnetics, Vol. 43, No. 1, January 2007.
30. Diamond, P., Electro Thermal Chemical Gun Technology Study, MITRE, March 1999, p. 5.
31. Goodell, Brad., Electrothermal Chemical (ETC) Armament System Integration Into an Combat Vehicle , IEEE Transactions on Magnetics, Vol. 43, No. 1, January 2007, p. 457.
32. Hilmes, Rolf, Arming Future MBTs – Some Considerations, Military Technology, December 2004, p. 78.
33. Yangmeng, Tian, et. al., A Novel Concept of Electrothermal Chemical Gun without Power Supply.
34. Lightweight and low-recoil gun systems for light tanks is the topic to a future Informative.
Last edited by The Macabees on Thu Mar 16, 2017 11:48 am, edited 1 time in total.

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Postby The Macabees » Thu Mar 16, 2017 11:48 am

Improvised Explosive Devices & Mine Resistant Vehicles


The occupation of Iraq will be known as the war of improvised explosive devices, now that these have caused at least 50% of the combat casualties in Iraq by 20061 and perhaps 70% of all combat casualties up until December 2007.2 In Afghanistan, improvised explosive devices have claimed up to 30% of all combat casualties of United States forces,3 and in Lebanon an improvised explosive device claimed three Spanish soldiers in a BMR six-wheeled armored fighting vehicle.4 Iraq is claimed to be one of the ‘most heavily mined nations in the world’, with over ‘ten million mines in the ground’.5 Booby trap improvised mines, in Iraq, have been used since Saddam Hussein’s regime and has increased since the beginning of the Coalition’s occupation in 2003 – 40 to 60% of all attacks begin with an improvised explosive device going off.6 During Israel’s 2006 summer war in Lebanon, five Merkava main battle tanks were knocked-out as a result of the explosion of huge improvised explosive devices under the tank’s belly7 and it seems as if the Palestinians have begun to employ similar tactics in the Gaza Strip and the West Bank.8 The threat of improvised explosive devices is not unique to United States forces, as the drive to acquire mine protected vehicles has been shown by many of the nations currently operating in Afghanistan, Lebanon, Bosnia or Iraq. According to Al Qaeda, ‘Explosives are the safest weapon for the Mujahidin. Explosives allow us to escape from enemy personnel and avoid arrest. In addition, explosives hit the enemy with absolute terror and shock.’9

Image
[U.S. M1114 up-armored HMMMWV knocked-out by an IED.]


Improvised explosive devices have taken many forms, but one of the most well-known is the explosively formed penetrator (EFP). Regarding shaped charges, the explosively formed penetrator is the part of the liner mass which flows in the opposite direction of the cone at a much lesser velocity. The remnants of shaped charge penetrations into armor are normally the explosively formed penetrator, given that these are made up of the majority of the liner’s mass.10 However, in the case of explosive formed penetrators used in improvised explosive devices in Iraq and in submunitions around the world the penetrator is purposely forged. Explosively formed penetrators normally have wide diameters, a low length to diameter ratio and have velocities of around 1.3 kilometers per second.11 The formation process of the explosively formed penetrator is complex and difficult to explain, and it requires high pressure and high temperature, and is influenced by a large number of factors – there are few papers which describe this process.12 Although explosively formed penetrators do not offer as high penetration as their shaped charge counterparts, or kinetic energy long-rod penetrators, they can perforate the thin roof and belly armor of armored fighting vehicles.13 It can be expected that the penetration of an improvised explosive device will depend on the quality of construction of the bomb, but they have proved to be lethal enough in Iraq given the previously noted percentage of U.S. casualties in Iraq and Afghanistan. To give an idea, about 5% of all explosive devices used against U.S. personnel in Iraq are explosively formed penetrators, yet they have provided for a third of the fatalities and over 10% of the injuries.14 A vehicle’s crew can be killed or wounded indirectly, as well, as the blast of an improvised explosive device can launch components of the vehicle into the crew cabin and the bomb’s pressure waves can kill a man.

Most improvised explosive devices are probably crudely manufactured and do not dispose of the quality to guarantee a kill. For example, some improvised explosive devices include roadside vehicle-borne bombs15 and others may not be powerful enough. Between January and September 2007 there were twenty-five thousand recorded IED attacks in Iraq, of a total of eighty-one thousand.16 Many of these target Iraqi civilian targets and other attack Coalition personnel, but those relevant to this paper are specifically those designed to defeat Coalition armored fighting vehicles. This threat has led to the recent decision, of the Pentagon, to procure up to 22,000 mine-resistance ambush-protected (MRAP) vehicles, belonging to three different categories.17 To give an idea of the industrial mobilization effort, Force Protection increased production to thirty vehicles per month in mid-2006 and by July 2007 ramped up production up to two hundred per month to fulfill large orders from various clients, including the US Armed Forces and the Iraqi Army. The company’s work force has expanded from 200 people to almost 1,000! The MRAP market has gone from being worth a few hundred million dollars annually to as much as $10 billion a year.18 One of Force Protection’s 16-ton Cougar transport truck was struck by a ninety kilogram bomb, which threw the vehicle’s engine over thirty meters away from the chassis and almost destroy the vehicle in its entirety. Even though MRAP equipment is tested against twelve to twenty kilogram charges, the Cougar’s crew survived the ninety kilogram mammoth improvised explosive device! In mid-January, 2008, one of Navistar’s MaxxPro trucks, crewed by four soldiers, was hit by a ‘very large’ improvised explosive device which sent the vehicle airborne – three of the four passengers survived the attack.19 Navistar is currently supplying the U.S. Armed Forces with 1,900 of its MaxxPro trucks – a deal in May 2007 for 1,200 and a follow-up order in July for another 700 – for a total of $1 billion. Arguably, Navistar’s success is due to the limits of Force Protection’s production capabilities.20

The United States is not the only country beginning to acquire MRAP vehicles. Spain is looking to replace its existing armored fighting vehicle fleet deployed in Afghanistan and Lebanon, with urgency. In late 2007, the Spanish Ministry of Defense decided to acquire forty Light Multirole Vehicles (LMVs) from Iveco, an Italian automotive company, for a total of €14.4 million.21 In January 2008 a decision was made to procure a further forty LMVs, at the risk of slowing down the acquisition of larger MRAP vehicles, for €12.4 million. Furthermore, a third order will be put in soon for another forty vehicles, for the same price tag.22 These vehicles will replace Spain’s indigenous URO VAMTAC, and Spain is looking to acquire a number of Category II MPRA vehicles, as well – either South Africa’s BAE Land Systems OMC’s RG-31 Mk 5, Force Protection’s 16-ton Cougar or Rafael’s Golan.23 Due to the loss of a BMR in Lebanon, and the deaths of three of its passengers, the Spanish Army will also purchase a number of brand-new 8x8 vehicles – to be produced in Spain – and the Ministry of Defense is currently choosing between the Swiss MOWAG Piranha V and the French VBIC.24 Although hardly comparable to the money invested by the United States, Spain is looking at spending between 100 and 140 million euros for 150 urgently required mine protected vehicles, and ultimately procuring around €1 billion worth up to the year 2012.25 However, to better understand the scope and the ambition of the program it should be taken into consideration that the Spanish government has not yet ended production of Spain’s 219 Leopard 2E main battle tanks, considered the most expensive Leopard to be produced to date.26 The program originally cost the Ministry of Defense €1.950 billion for 219 Leopard 2Es and 16 Buffalo armored recovery vehicles (ARVs),27 but costs have spiraled with recent program delays due to the mismanagement of Santa Bárbara Sistemas.28 The Spanish Army is also beginning to accept new Tiger attack helicopters and Pizarro infantry combat vehicles, while the Spanish Air Force is still being issued new Eurofighter Typhoon air superiority fighters. Therefore, the €1 billion should be seen within the context of Spain’s recent military spending in order to understand the urgency of the issue.

Image
[Cut-out image of an IED.]


Other countries are also spending money to acquire state-of-the-art mine-resistant vehicles. Perhaps one of the most interesting is Canada’s recent acquisition of twenty Leopard 2A6M mine-protected main battle tanks from the German Bundeswher, while they await the arrival of forty Dutch Leopard 2A6 and forty Leopard 2A4 – the 2A6Ms will replace Canadian Leopard 1C2s in Afghanistan, and at least nineteen will be returned to Germany after their tour is complete.29 In Afghanistan, the Canadians have experienced around 100 casualties in their light wheeled armored fighting vehicles and twenty-four in new MRAP vehicles. Despite the addition of MEXAS non-explosive reactive armor to the hull of the Leopard 1C2, they were found to be antiquated and insufficient in front of the threat posed by mines in Afghanistan. The Leopard 2A6Ms introduces a new auxiliary power unit (APU), an air conditioning system and a number of increases in armor protection, especially against mines.30 The United Kingdom’s FRES program may be affected by the new drive to purchase MRAP vehicles, given rumors that the Ministry of Defense may tap into the FRES budget in order to acquire a larger number of armored trucks. In August 2006 the British Army placed an order for 108 of Force Protection’s Cougar transport trucks, and the Ministry of Defense is looking to spend between $40 and $400 million for up to 180 Medium Protected Patrol Vehicles (MPPV).31 Furthermore, despite the lightweight requirements for Britain’s FRES program, some fear that the IED threat will force vehicles to increase weight in order to counter the threat.32 Australia, which has deployed troops to Afghanistan, has also invested in the purchase of a number of Bushmaster mine-protected trucks.33 The improvised explosive device threat is certainly big enough to force nations to put aside existing procurement efforts in order to acquire the best mine-protected light wheeled armored trucks on the market.

Aside from the Leopard 2A6M, most tank producing nations have introduced new urban fighting kits with increased protection versus anti-tank mines and improvised explosive devices. Krauss-Maffei Wegmann (KMW) showcased the new Leopard 2 PSO (Peace Support Operation), with add-on turret and hull armor, a secondary remote weapon station near the loader’s hatch, an auxiliary power unit, panoramic 360º coverage by cameras embedded in the vehicle’s hull, an external radio, a searchlight and a dozer blade. Also shown at the Eurosatory 2006 exhibition was France’s AZUR (Action en Zone Urbaine), for Nexter’s Leclerc main battle tank. In the kit, a remote weapon station replaces the commander’s pintle-mounted machine gun, new appliqué composite panels for the side skirts, and added armor to the engine bay, as well as the application of slat armor to protect the entire rear of the vehicle. Perhaps one of the better urban warfare kits is Israel’s new Merkava LIC, which boasts of added all-around protection and increased hull bottom armor thickness. Furthermore, to protect sensitive items against debris, shrapnel and rocks all air intakes, exhausts and electronics are protected by steel mesh, similar to the Leopard 2 PSO. The commander’s cupola is replaced by a new cupola, which allows the commander greater visibility from a higher position and the remote controlled 12.7mm gun is repositioned above the main gun. Interestingly, a new hatch has been introduced in the rear door, to allow snipers to protect the vehicle’s rear. These may equip Israeli Merkava Mk 3s, while the Mk 4 may receive a separate upgrade. This includes two-axis stabilization of the commander’s panoramic sights, with new-generation FLIR and TV channels.34 The Merkava was designed, originally, with a v-shaped hull which was hollow between the bottom of the ‘crest’ and the thinner floor plates above – in the first two models this space was filled with fuel, but in the Mk 3 and Mk4 the fuel tank has been eliminated and instead it’s spaced simply with air.35 On the other hand, some sources indicate that fuel will actually suppress a shaped charge jet (or an explosively formed penetrator) if the fuel tank is self-sealing.36 Perhaps the most well-known urban kit for a main battle tank is the Abram’s TUSK modification package (tank urban survivability kit), which includes a new thermal sight for the loader, a remote weapon station for the tank commander, explosive reactive armor on the side skirts, a rear protecting unit composed of slat armor, a gun shield for the loader and an infantry phone in the rear. It’s possible that these new reactive armor tiles are similar to the Blazer reactive armor tiles applied to the Bradley infantry fighting vehicles and M60A1 main battle tanks in the early 90s.37

Image
[Merkava Mk. 3 LIC; note the sniper hatch in the rear door.]


However, apart from the Merkava, these modifications are only of limited use against improvised explosive devices. As noticed, most increase protection of the tank on the side armor and the rear, prioritizing protection against rocket propelled grenades. However, only the Merkava has effective armor protection on the tank’s belly, with the v-shaped hull, and even this has failed the tank in Lebanon, where it experienced charges of up to 100kg.38 Furthermore, although the additional floor armor on the Leopard 2A6M might be able to stop the penetration of an explosively formed penetrator, it does not protect the crew from the blast and shock effects – the same is true for Nexter’s anti-TMRP-6 Kpam protection kit for armored fighting vehicles.39 This is more evident in the recent up-armor attempts on the M1114 HMMWV, which began in 1997. The M1114 features add-on blast deflectors and armor designed to absorb the energy of an explosion, and therefore is tested to survive threats of up to 8kg in size.40 However, the appearance of larger threats, such as the ninety kilogram charge that destroyed a Cougar in Iraq, makes even the M1114 obsolete and has driven the Congress to approve a massive replacement program for all front-line HMMWV vehicles. Perhaps the most important arguments in the sale of new MRAP vehicles is Doug Coffey’s – vice president of communicates at BAE – comment, ‘These are new designs, not spin-offs.’41 New vehicles hitting the market designed specifically for anti-mine and asymmetrical warfare are introducing new armor technologies and other indirect protection methods for the vehicle’s crew and passengers. Due to design limitations of already existent vehicles, these new technologies and methods are best applied to brand-new vehicles, and it isn’t a surprise that these are proving to be the most effective in combat.

Hull Bottom Shape & Protection
All new mine resistant ambush protected vehicles have at least one thing in common – a v-shaped hull.42 The v-shaped hull found its first widespread use by South African43 and Namibian44 vehicles operating in Rhodesia, or what is now Zimbabwe. A v-shaped hull refers specifically to the inclination of the floor plates to bulge towards the floor, creating what can be called a wedge (and, is in fact, similar to the ‘wedge armor’ used on the Leopard 2A5, in regards to the inclination of the armored plates). The inclined plates don’t give an anti-tank mine or an improvised explosive device a target with a flat surface area, and so the explosion will follow the path of least resistance and will be deflected away from the vehicle. Naturally, the more inclined the plates the more the blast and the subsequent shockwaves will be deflected and the lesser the impact on the crew of the armored vehicle. The volume between the two inclined plates and the floor plates of the vehicle is normally hollow, or used as a gas tank – such on the Merkava tank (as read above). Generally, due to safety concerns MRAP vehicles leave the volume empty, as the potential protection capability of diesel fuel is arguable. It’s important to note that the inclination of the hull bottom will also result in taller vehicles, and therefore the angle at which the plates are inclined should be juxtaposed against the tactical necessities of the specific vehicle being built. Furthermore, v-shaped hulls will increase the weight of the vehicle and therefore highly inclined plates are difficult to adopt on main battle tanks, or other vehicles with specific weight limits, due to the fact that these are normally already built to the edge of said imposed weight limit and height limit. Normally, this will result in a larger RADAR signature. Finally, another important consideration is that vehicles designed from scratch, with v-shaped hulls, will normally also limit the amount of usable internal volume for passengers and cargo, given the already mentioned limits on weight and height.45

Image
[A line-drawing of the Bushmaster's V-shaped hull.]


The hull bottom’s armor protection can also be designed to maximize the vehicle’s survivability against explosively formed penetrators and shaped charges. Perhaps one of the most important is the elimination of all hatches in the vehicle’s belly. A similar decision was made to eliminate the loader’s hatch on the Merkava Mk 4, to increase protection against top-attack threats – the Merkava Mk 4 is the first modern tank to eliminate the loader’s hatch (with a four-man crew).46 Although these are two different areas of the tank, the reason behind the elimination of the hatch on the turret roof is the same as that to eliminate the hatches on the hull floor – hatches represent weak points in the armor. Furthermore, the elimination of ammunition stored near the hull bottom also increases a vehicle’s survivability – even if the ammunition is stored in fireproof cases (this comment assumes that the ammunition stored on the floor is single-piece and uses a solid propellant47). Apart from these indirect forms of protecting the crew, increasing armor thickness by adding floor plates will help in either stopping the explosively formed penetrator or slowing it down, as to reduce damage inside the tank. Furthermore, in regards to the armoring of the steel pieces that form the v-shaped wedge under the hull, the welding point should be hardened – in fact, the Merkava’s v-shaped bottom plate is a single, bent, layer of steel, instead of two pieces being welded.48 This is possible for more shallow wedges, but in regards to highly inclined plates the best solution is to simply harden the welding points.

Due to the importance of the integrity of the steel plating, low-carbon steels are preferred over harder steels. Therefore, generally, unhardened steel plates are typically superior for these roles, over armored steels with a hardness value of around 40 HRc (Rockwell Hardness Level). Usually, hardened steels don’t retain structural integrity during penetration or when undergoing impact loads.49 The secondary floor plates, or the plating which provides the floor for the passengers above, is now normally being designed as a multi-layer composite armor – using both steel and an energy absorption layer, such as rubber or even ceramic. Much of the technology being developed for lightweight vehicle armors to defeat armor piercing hard-core small-arms ammunition can be applied to anti-mine protection. Due to the importance of transfer of energy, in regards to the transfer of energy of the mine to the crew, energy absorption layers are extremely important. For example, a simple floor armor could be composed of two spaced steel plates, with a layer of another material to absorb impulsive loads. Since impulsive loads normally occur over short periods of time and are characterized as single events when regarding an anti-tank mine (the mine will explode once; secondary waves put aside), the filler layer can stop or slow pressure waves which have transferred through the bottom steel plate.50 Recently, aluminum foam has been suggested for use as the inter-layer material.51 Closed-cell aluminum foam has been found to be superior to rubber since it doesn’t degrade the structural stiffness of the armor and this material also stops or attenuates stress waves moving through the armor.52 Since the performance of ceramics backed by aluminum foam has been found to degrade, as compared to steel, closed-cell aluminum foam refers to the confinement of aluminum foam behind a steel backing-plate for the ceramic.53 In regards to floor armor for an armored fighting vehicle, this might not be relevant given that the chances are that the two confining plates will be composed of steel.

Image
[Knocked-out Cougar - all the occupants survived.]


Given weight considerations on some vehicles, especially tanks,54 the thickness of the armor arrayed to defeat an explosively formed penetrator is limited. Therefore, lightweight composites are preferred over thicker steel plates. For what it’s worth, two spaced steel plates with an inner layer of aluminum foam will have a superior performance of a homogenous steel plate of equal thickness, especially in regards to wave propagation. Ceramics may be used, but ceramic-metal armors will require higher thicknesses, given that the layer of rubber or aluminum foam will still be needed to attenuate impulse loadings and shock waves. Although certain ceramics perform better when impacted at lower velocities, the perforation of ceramics concerning anti-tank mines is complicated. Although explosively formed penetrators will impact at relatively low velocities (between 1,100 and 1,500m/sec, usually), high speed shockwaves will collapse more brittle ceramics. Therefore, due to its ductility and ability to perform better at higher velocities, aluminum nitride may be a superior ceramic to others as floor armor.55 The density of aluminum nitride (AIN) is around 3.25 g/cm3,56 as compared to a density of 7.85 g/cm3 for armored steel57 and 4.5 g /cm3 for titanium di-boride.58 As a result, aluminum nitride is also relatively light, although not as light as boron carbide.59 But the use of ceramics should be limited, given weight limitations and the fact that although ceramics absorb the energy of the impact, they do not react well to pressure waves. From these conclusions, perhaps titanium-diboride, boron carbide or silicon carbide may be superior to aluminum nitride in regards to stopping explosively formed penetrators. This should be weighed against the possibility of being targeted by an anti-tank mine with a high-velocity shaped charge and the material’s response to impulse loading induced shock.

These materials are just some out of many, and therefore this paper shouldn’t be approached as an exact guide to decide on armor materials. Nonetheless, the information offers a basic picture at what armor designers attempt to achieve when designing lightweight armor which can serve as protection against explosively formed penetrators or shaped charges originating from anti-tank mines or improvised explosive devices. Finally, armor for ballistic protection is likely to spall, which means that the requirement for spall liners along the vehicle’s floor is augmented.

Other Forms of Survivability & Conclusions
A major threat to the crew itself is the shock of the explosive, which may move body parts – such as the neck – in non-ideal ways, which can result in the neck snapping or broken body parts. Therefore, new armored fighting vehicles are introducing new seats, suspending from the hull floor, which better serve to keep a crew member or a passenger fixed in his position in case of an explosion. These seats should have safety belts with at least four to five harness points and the use of suspended foot-rests is advisable to avoid broken ankles.60 Vehicles such as IVECO’s Light Multirole Vehicle (LMV), currently in service with the British Army (as the Panther), Spanish and Italian Armies (as the Lince) and Norwegian army, offer enhanced survivability by separating the crew from the chassis through an armored ‘crew cell’. Wheels, suspension components and the engines are arrayed in such a way that during the blast these fragments will fly in other directions, while the large wheels themselves absorb the energy of the blast, and deflectors installed along the wheel’s arc deflect the blast away from the vehicle.61 These components may increase weight, but the increase in weight is seen as a justified expense given the drastic improvement in survivability. In terms of economic cost, a HMMWV-replacement can cost anywhere between $300,000 and $450,000, while replacements for soldiers will cost anywhere between $200,000 and $1,000,000 (this includes soldiers wounded to the point where they are no longer eligible for combat). The increased price per vehicle is well justified, in other words.

In the future, new technologies will be implemented to increase survivability further, and will help to reduce weight. Such a technology, still in the beginning stages of development, is electric armor. Passive electromagnetic armor – electric armor – is simply two steel plates (or electrodes) spaced apart and attached to an electric battery or generator. When the threat perforates the first plate and touches the second plate a circuit will be completed and the electricity will deform the projectile. This novel armor’s greatest advantage is against long and thin shaped charge jets, as opposed to the thicker improvised explosive devices.62 This armor is bulky and heavy compared to the thinner armor layer composite armors suggested above and requires substantial electric power, to the point where such armor may not be adequate until the advent of a fully electric ground vehicle.63 Nevertheless, it’s an idea of what there is to come in the future.

Image
[New suspended seats introduced in the German Marder 1A5.]


Fortunately, the rather unfortunate fact that improvised explosive devices are one of the most lethal weapons for an insurgent on the modern asymmetrical battlefield will speed up the development of armors to defend against explosively formed penetrators and shaped charges from the ground. Methods of indirect survivability will also evolve and be introduced into new vehicles, given that the development of these technologies is economical due to the spur in national interests to spend multiple billions of dollars on the emergency procurement of mine-resistant armored fighting vehicles. The vehicles will save lives overseas and will reduce the efficiency of insurgencies in countries currently occupied and in future peacekeeping operations. The natural response will be to increase the size of the threat, but even then today’s vehicles have proven themselves adept to still remain superior to the threat. MRAP-related developments will take precedence over future heavy armored fighting vehicle programs since today’s heavy vehicles will remain tactically viable for at least the next two decades, if warfare continues along contemporaneous trends.





Notes


1. Wilson, Clay, Improvised Explosive Devices (IEDs) in Iraq and Afghanistan: Effects and Countermeasures, CRS Report for Congress, 25 September 2006, p. 1.
2. Martínez, Rafael Treviño, Evolución del fenómeno IED y los vehículos protegidos (Parte 1), Fuerza Terrestre, Año III, Vol. 3, Nº 49, p. 10.
3. Wilson, Clay, Improvised Explosive Devices (IEDs) in Iraq and Afghanistan: Effects and Countermeasures, CRS Report for Congress, 25 September 2006, p. 1.
4. Lebanon blast kills UN soldiers, http://news.bbc.co.uk/2/hi/middle_east/6235224.stm
5. Improvised Explosive Devices (IEDs) – Iraq, http://www.globalsecurity.org/military/intro/ied.htm.
6. Ibid.
7. Eshel, David, Lebanon 2006: did Merkava challenge its match?, http://www.encyclopedia.com/doc/1G1-159390665.html
8. Anti-Armor IEDs are Becoming More Sophisticated, http://www.defense-update.com/features/du-3-07/mrap_at05.htm
9. Martínez, Rafael Treviño, Evolución del fenómeno IED y los vehículos protegidos (Parte 1), Fuerza Terrestre, Año III, Vol. 3, Nº 49, p. 8.
10. Ferrari, Giorgio, The ‘Hows’ and Whys’ of Armour Penetration, Military Technology, October 1988, pp. 52-55.
11. Chuan, Yu, et. al., Applied Research of Shaped Charge Technology, International Journal of Impact Engineering, Volume 23, 1999, pp. 985-988.
12. Wu, Chun, et. al., Experimental and Numerical Study on the Flight and Penetration Properties of Explosively Formed Penetrators, International Journal of Impact Engineering, Volume 34, 2007, pp. 1147-1162.
13. Horst, Albert W., et. al., Recent Advances in Anti-Armor Technology, American Institute of Aeronautics and Astronautics, 1997, p. 10.
14. Axe, David, Next Step for MRAP, Defense Technology International, November 2007, p. 24.
15. Vehicle Borne IEDs (VBIEDs), http://www.globalsecurity.org/military/intro/ied-vehicle.htm
16. Martínez, Rafael Treviño, Evolución del fenómeno IED y los vehículos protegidos (Parte 1), Fuerza Terrestre, Año III, Vol. 3, Nº 49, p. 11.
17. Candil, Antonio J., Actualidad desde los Estados Unidos: El US Army se equipa con urgencia con nuevos vehículos acorazados, Fuerza Terrestres, Año III, Vol. 3, Nº 47, p. 76.
18. Axe, David, Ramping Up, Defense Technology International, July 2007, p. 23.
19. These two examples are from: Hopes for NY Times Reporting Questioned After MRAP Story, http://www.defenseindustrydaily.com/hopes-...ap-story-04673/.
20. Axe, David, Home Run, Defense Technology International, September 2007, p. 22.
21. Iveco LMV Para el Ejército de Tierra, Fuerzas Militares del Mundo, Año VI, Nº 65, Enero 2008, p. 22.
22. Más Blindados MLV, Fuerzas Militares del Mundo, Año VI, Nº 66, Febrero 2008, p. 74.
23. Ibid.
24. Vehículos Blindados con Carácter Urgente, Fuerzas Militares del Mundo, Año VI, Nº 64, Diciembre 2007, p. 73.
25. Inteligencia Terrestre, Fuerzas Terrestres, Año III, Vol. 3, Nº 47, p. 6.
26. Candil, Antonio J., Un entorno industrial plagada de dificultades: La fabricación del Carro de Combate Leopard 2E en España (I), Fuerzas Terrestres, Año III, Vol. 3, Nº 49, pp. 38-49.
27. Candil, Antonio J., Leopard 2E MBT Delivery Begins, Military Technology, March 2004, p. 73.
28. Candil, Antonio J., Un entorno industrial plagada de dificultades: La fabricación del Carro de Combate Leopard 2E en España (I), Fuerzas Terrestres, Año III, Vol. 3, Nº 49, pp. 38-49.
29. KMW delivers first LEOPARD 2 A6M to Canada, http://www.epicos.com/epicos/portal/media-...&showfull=false
30. El regreso del carro de combate, Fuerzas Terrestres, Año III, Vol. 3, Nº 47, pp. 15-17.
31. Chuter, Andrew, UK Seeks Lighter Armored Patrol Vehicle, Defense News.
32. Sharman, Alan, Armored Fighting Vehicles Development – A UK Perspective, Military Technology, December 2006, p. 60.
33. ADF to acquire another 250 Bushmasters, http://www.smh.com.au/news/National/ADF-to...6857818096.html
34. Eshel, David, Armor for Urban Combat, Military Technology, February 2007, pp. 69-72.
35. Gelbart, Marsh, New Vanguard 93: Modern Israeli Tanks and Infantry Carriers 1985-2004, Osprey Publishing, 2004, p. 35.
36. Simpkin, Richard, Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 116.
37. Green, Michael and Stewart, Greg, M1 Abrams at War, Zenith Press, 2005, pp. 106-107.
38. The news Israel wishes we didn't hear, https://www.indymedia.ie/article/65082
39. Huntiller, Mark, Asymmetrical Warfare- Armor, Armada International, June 2004, pp. 38-39.
40. Bianchi, Fulvio, Mine Protection for AFVs, Military Technology, February 2005, p. 39.
41. Toensmeier, Pat, Special Delivery: Marines fast-track new armored vehicles to counter roadside bombs, Defense Technology International, March 2007, p. 26.
42. Axe, David, Breaking the Mold: Diversity adds depth to MRAP, Defense Technology International, October 2007, p. 46.
43. Sparks, Mike, A Crisis of Confidence in Armor?, ARMOR Magazine, March-April 1998, p. 22.
44. Axe, David, One That Got Away: Trade rule bars popular Namibian armored truck from MRAP competition, Defense Technology International, October 2007, p. 20.
45. Bianchi, Fulvio, Mine Protection for AFVs, Military Technology, February 2006, p. 38.
46. Gelbart, Marsh, New Vanguard 93: Modern Israeli Tanks and Infantry Carriers 1985-2004, Osprey Publishing, 2004, p. 39.
47. For example, Soviet/Russian ammunition is two-piece, meaning the propellant is stored in a semi-combustible cartridge apart from the actual ‘warhead’ or round. In Russian tanks, where most of the ammunition is stored in a carousel around the turret ring, it’s irrelevant since the two pieces are stored together – the explosion of the propellant in Iraqi T-72s during the Second Persian Gulf War (1991) and Russian T-80BVs and T-72s in Chechnya is what caused the loss of the turret. Furthermore, in tanks such as the Lince, where the ammunition is stored vertically in a carousel, the ammunition may be inert given the fact that the propellant is stored in the turret. In regards to the loss of the turret, the upward force of an explosion from an improvised explosive device has also caused the loss of a M1 Abrams turret in Iraq, during the occupation.
48. Gelbart, Marsh, New Vanguard 93: Modern Israeli Tanks and Infantry Carriers 1985-2004, Osprey Publishing, 2004, p. 35.
49. Prifti, Joseph, et. al., Improved Rolled Homogenous Armor (IRHA) Steel Through Higher Hardness, Army Research Laboratory, April 1997, p. 1.
50. Nemat-Nasser, S., et. al., Experimental Investigation of energy-absorption characteristics of components of sandwich structures, International Journal of Impact Engineering, Vol. 34, 2007, p. 1120.
51. Hogg, Paul J., Composites for Ballistic Application, Department of Materials, Queen Mary, University of London, p. 10.
52. Gama, Bazle A., et. al., Aluminum foam integral armor: a new dimension in armor design, Composite Structures, Vol. 52, 2001, p. 383.
53. Ibid.
54. http://z4.invisionfree.com/NSDraftroom/ind...?showtopic=1514
55. Reaugh, J.E., et. al., Impact Studies of Five Ceramic Materials and Pyrex, Journal of Impact Engineering, Vol. 23, 1999, p. 779.
56. Orphal, D.L., et. al., Penetration of Confined Aluminum Nitride Targets by Tungsten Long Rods at 1.5-4.5km/s, Journal of Impact Engineering, Vol. 18, No. 4, 1996, p. 357.
57. Leavy, Brian R., Improved Rolled Homogenous Armor, Army Research Laboratory, March 1996, p. 4.
58. Hazell, Paul J., The Development of Armor Materials, Military Technology, April 2004, p. 59.
59. Ibid.
60. Bianchi, Fulvio, Mine Protection for AFVs, Military Technology, February 2006, p. 37.
61. Iveco LMV Para el Ejército de Tierra, Fuerzas Militares del Mundo, Año III, Nº 65, 2008, p. 26.
62. Ping, Zheng, et. al., Research on Passive Electromagnetic Armor, IEEE Transactions on Magnetics, Vol. 41, No. 1, January 2005, p. 456.
63. Huntiller, Mark, Asymmetrical Warfare – Armor, Armada International, June 2004, pp. 41-42.


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