The Macabees
11-01-2009, 21:34
CB.125 125mm L/55 ‘Special’ Tank Gun
Program Details
The CB.125 is a further development of the AGS.250C, designed originally between Calzado y Bayo and Atmos for the Nakíl 1A3 main battle tank, to provide clients with what is considered the ultimate in tank gun technology besides electromagnetic acceleration – which is not considered currently feasible, given electricity storage issues. The Nakíl is a widely exported main battle tank, with close to ten million vehicles of all six known production models (1A1, 1A1GU, 1A1+, 1A2, 1A3 and 1A3HA) sold to date (not including modification packages to upgrade already-assembled tanks), and continues to be substantially popular on the export market, especially in its latest incarnations – the Nakíl 1A3 and the Nakíl 1A3HA. Therefore, it wasn’t a surprise to either Kriegzimmer or Sistemas Terrestres Segovia when new customers arrived, but without the intention of changing calibers - the first such customer was Cotland, with a contract for seventy-two thousand Nakíl main battle tanks. Although technically the change in caliber, from the perspective of retrofitting the 120mm gun, is economically feasible given that it’s part of the modification package, the change in ammunition and the redistribution of millions of shells might not be. Historically, this issue has played a major role in limiting the sale of the Nakíl to historical users of the 120mm caliber and only to those willing to change, and has not allowed the Nakíl to make a large impact in the mainstream 125mm market – where tank companies from nations such as Doomingsland, Soviet Bloc and Aequatio still remain supreme. Calzado y Bayo’s CB.125 not only opens the Nakíl to a much larger tank market, but also allows Calzado y Bayo to play a major role in foreign tank industries by marketing the tank gun for foreign indigenous tank programs.
In the latter’s regard, the Castillian defense company has already scored a major contract with Doomingsland Defense Industries for the sale of production rights to the CB.125 for the modification program of the country’s current main battle tank and the possibility of using the tank gun in a future tank. This not only affects sales to the Doomani military, but also any exports which the MAD.V may be able to contract abroad. In this case, the CB.125 is actually a separate development to that offered for the Nakíl 1A3, although the technology remains basically the same. The version of the gun offered on the general export market is the CB.125E (Exportación) and comes with a dual-caliber breech, but with the capability of fitting either a 120mm or 125mm cannon. This is largely meant to suggest an effort for the eventual conversion to 120mm for customers, even if some may never commit to it – it gives them the option to easily modify existing tanks, if they feel that they can handle the remanufacture of ammunition. The CB.125, offered for the Nakíl, on the other hand offers the dual-caliber breech for either a 125mm gun tube or a 140mm gun tube. In all actuality, this is not completely accurate as either breech can be offered, depending on the client nation’s chance of being able to receive the larger gun caliber in the future – for example, Cottish Nakíl 1A3Cs will receive the 125/140mm dual-caliber breech, foreseeing a possible future decision to modify all tanks in service to 1A3HA (heavy armor) standards (currently, Cottish forces operate 70,000 Nakíl 1A3Cs and 2,000 Nakíl 1A3HAs for elite forces). The decision to not offer this option on the CB.125E is for a number of reasons, including the fact that 140mm might not be the preferred ‘larger caliber’ of the client nation (as opposed to 135mm or 152mm, for example) and Calzado y Bayo is not readily willing to facilitate this modification, given that it will allow foreign designs to compete with the Nakíl 1A3HA at the same low cost.
In the Nakíl’s case, the modification of the gun comes with other challenges as well. The autoloading system, including the two FASTDRAW revolvers near the rear of the turret, is designed specifically for either 120mm ammunition or 140mm ammunition, and there is no major production line for a 125mm variant. Regardless, Calzado y Bayo currently works in conjunction with the Castillian defense company Cibeles Dynámica, which focuses on autoloading systems for different systems (including naval cannons), for the production of a 125mm version of the Nakíl’s autoloader. The cost is the depression of the revolvers and their slight increase in size, and the depression of the robotic autoloading system (RALS), which means there is less available volume in the turret basket. As a consequence, Sistemas Terrestres Segovia and Imperial Land Systems instead decided to decrease the amount of available spare ammunition in fireproof cases suspended near the turret basket’s floor. In terms of length and required volume, the breech is similar given that in the original version of the gun it’s designed also for a full long-rod penetrator of the 140mm caliber and in the E version it’s designed for an extended length long-rod of the 120mm caliber; in other words, in the latter’s case penetrator length is likely to be similar. The gun tube is similar in length, as well – a 120mm L/57 compared to a 125mm L/55. Consequently, no major changes in the internal volume of the Nakíl are necessary, while the breech is designed to easily replacing existing 125mm breeches. In other words, for the most part complicated turret remodeling is not necessary in this case.
The gun, in all variants, will be produced by a number of different companies. These include Calzado y Bayo, Sistemas Terrestres Segovia (which has a much more extensive industrial complex around the world), Kriegzimmer (which is a co-producer of the Nakíl tank) and Atmos. The CB.125E for Doomingsland will be manufactured by Sistemas Terrestres Segovia and by Kriegzimmer in a joint-assembly program, mostly due to the fact that the latter has much more extensive capabilities to produce the gun in large numbers. Both companies, however, will use exclusively factory grounds in Doomingsland, as the contract requires. The gun, when manufactured for exported Doomani tanks, will most likely be produced in Doomani territory as much as possible, although it’s likely that production will spill to ‘overseas’ factories if the demand for the MAD.V is high. Guns manufactured for the Nakíl 1A3C will be manufactured exclusively by Calzado y Bayo and will be shipped to Kriegzimmer assembly plants for final installation in the Nakíl 1A3C turret, before the tank as a whole is shipped to Cotland. Future, independent, sales will most likely be co-produced between the Castillian gun company and Atmos, its Macabee counterpart, depending on the amount of sales it receives. It’s entirely possible that production rights will be awarded to foreign companies to market the gun in other nations, arguing that the gun is completely indigenous (since it will be produced indigenously). Similar marketing strategies have been followed in nations such as Juumanistra to sell a wide array of technology to a country largely unwilling to adopt foreign weapon systems, especially in regards to tank technology (the Juumanistran Kyton main battle tank has cost the country anywhere between $25 and $35 million per vehicle, and costs have continued to spiral as indigenous companies continue to develop modification packages to upgrade the tank to international standards).
Propulsive Technology
Today’s armored threats require extremely high powered main guns to have any hopes in perforating their armor. This gun versus armor race has led to a speedy development of ‘next-generation’ technologies, although many of these are still not viable – such as electromagnetic acceleration. Originally, the goal was to reach previously unattainable velocities in order to engage the target faster and increase the accuracy of the projectile, but recently there instead has been a decision to increase projectile mass by increasing its diameter. Regardless of whether the goal is to increase projectile velocity or projectile mass, they both require one thing – increased muzzle energy. There are a multitude of ways that this can be accomplished, including increasing the volume of the propellant charge in a conventional powder (solid propellant) cannon. Normally, each barrel, in accordance with the internal surface area of the tube, has a specific pressure it can withstand from the expanding propellant and therefore it’s normal to see an increase in caliber when the propellant charge has been enlarged to such a degree that it is no longer viable to use in an existing diameter gun barrel. Consequently, it’s not rare to find tanks with larger caliber tank guns, which unfortunately also require larger volumes inside tank turrets. There are, of course, alternative technologies – as mentioned – and the CB.125 follows this such school of thought, preferring new technologies to having to increase barrel caliber. In accordance with this, Calzado y Bayo have decided to offer what they consider the most advanced tank gun propulsion technology currently technologically feasible or known in the CB.125 – for many, this will be the best tank cannon (in this caliber) available on the market and it will certainly give the Doomani MAD.V an edge over competitors that do not use this gun.
Perhaps the most outstanding feature is the fact that it uses electrothermal-chemical (ETC) augmentation. Ultimately, this can be achieved in several different ways, but in the CB.125 specifically the round is designed to have an electrothermal ignition (ETI) charge which requires less than 100kJ per shot (the power supply is not an issue with the gun and is up to the client to decide how to provide this power – in the Nakíl 1A3, for instance, there is a pulsed power supply to the rear of the turret, while in the Nakíl 1A3HA the power is provided by the batteries which form part of the electric transmission). Consequently, the round or combustion chamber is likely to have a series of copper wires with embedded diamonds, or any other material which will provide the same effect, which will discharge plasma due to the vaporization of the material if electrically charged. Specifically, this type of plasma emitter is known as a flashboard large area emitter (FLARE) or a variation thereof. Due to the propellant type used in the CB.125 (discussed below), the plasma emitter is located as part of a completely combustible modular cartridge that forms part of the round (in solid propellant guns, for the most part semi-combustible propellant cartridges are used), containing only the emitter. The plasma completes a number of important jobs, including decreasing the molecular volume of the propellant and therefore increasing muzzle energy. The plasma is also used to ignite the propellant, to catalyze its expansion, and to control the rate of expansion of the propellant to make it much more effective in regards to maximizing its potential. In a 120mm solid propellant gun, for example, electrothermal-chemical combustion is known to increase muzzle energy from 9mJ to 18mJ, which effectively doubles the energy of the gun (more accurately, it can increase muzzle energy anywhere from 15mJ to 18mJ, approximately – exact figures are difficult to come by).
As already mentioned, the CB.125 – like in most tank guns produced by either Atmos or Calzado y Bayo – uses a hydroxyl ammonium nitrate (HAN) based liquid propellant, instead of a solid propellant. Contrary to popular belief, although liquid propellants do increase the piezometric efficiency – that is, the advantage of having a higher mean to peak chamber pressure – and therefore may have an increase in muzzle velocity (perhaps around 10% higher), they do not have a higher ballistic efficiency as compared to solid propellants. Therefore, technically, in order to achieve the same muzzle energy a liquid propellant needs more mass than their solid propellant counterpart, but it is also true that a liquid propellant requires less volume – in this case, the amount of energy per gram of the propellant is similar to a solid propellants (a little over 5,000kj/g), but require only about 70% the volume. To give an idea on the volume advantages a solid propellant has, at best, a loading density of 1,000kg/m3, while this specific liquid propellant (based on the real-life LGP 1846) has a loading density of over 1,500 kg/m3. Further savings in space arise from the fact that a liquid propellant is stored in closed cells, in bulk, while solid propellants must be stored with their respective ammunition in charge modules or bags. Specifically, the CB.125 uses a regenerative liquid propellant gun (RLPG) which has the liquid propellant metered into the combustion chamber by means of an injection pump – it should be noted that liquid propellants are easier to manufacture than solid propellants and are also cheaper (30-50% so). Unfortunately, regenerative guns are mechanically complex, but trade complexity for increased control of the propellant – a worthwhile trade. Just like its 120mm brother, the CB.125 uses a high-breech pressure charge, which means that the charge volume is larger than what is necessary in order to increase muzzle energy. This is possible not only because of the burn efficiency of a liquid propellant, but also because the gun barrel is coated with chrome to allow for increased barrel pressures. There are certain safety concerns with liquid propellants, and these should be addressed. Since liquid propellants can be separated from their respective projectiles and stored in protected and closed cells inside the turret, they have an added advantage over solid propellants – as mentioned above. Therefore, they can be better protected by the turret’s armor and if the ammunition compartment is breached it means that the ammunition will not react violently, unlike in many solid propellant tank designs (especially designs with carousel autoloaders, or ammunition in the turret basket). Furthermore, bipropellants such as HAN-based propellants cannot react on their own and require both parts of the propellant to interact in order to allow the reaction (which is truly catalyzed through the electric discharge, regardless). Therefore, it can be considered stable and less vulnerable than their solid propellant competitors.
A recent addition to the union of liquid propellants and electrothermal chemical technology, also known as a liquid propellant electrothermal-chemical (LPETC) gun, is chemically augmented combustion (CAC). This is similar to electrothermal-chemical combustion, but less radical, and can be used to increase the potential of electrothermal-chemical reactions even further. Chemically augmented combustion has been a very recent addition to the Nakíl, and is only present in the AGS.250C and the AGS.300 (the 140mm version) – this technology is likely to be retrofitted into a future variant of the CB.54 103mm gun present on the carro de combate Lince, used by the Castillian Ejército de Tierra. Technically speaking, chemically augmented combustion is not either new or old, and was ‘developed’ around the same time as electrothermal-chemical technology – as said before, it’s simply a much less radical approach, although with many less benefits (if applied alone). This technology can be known under many other names including hydrogen augmented combustion (HAC) and propellant energizing technology (PET). When applied to an electrothermal-chemical gun is can also be known as hydrogen propellant electro-chemical (HYPEC) combustion. In essence, this behaves similar to electrothermal-chemical technology in one respect, in which that it can convert high molecular weights to low molecular weights through chemical means, which means in high produced muzzle velocities or energy. This technology is somewhat easy to apply given that the hydrogen can be produced by an electrothermal reaction in the combustion chamber, which forms part of the electrothermal-chemical process. Despite the less radical approach, this technology is relatively unheard of since it has not been widely marketed and this is one of the first times it has been applied to an actual field gun (the AGS.250C and the AGS.300, before the CB.125).
All of this technology integrated into the gun makes the CB.125 what is most likely the most powerful gun of this caliber, although it’s also true that it also makes the CB.125 very mechanically complex. However, it all has to do with a series of trade-offs which one country might see as justifiable and the other may not. The most mechanically complex portion of the gun is the regenerative liquid propellant, which unfortunately is currently difficult to solve using other liquid propellant combustion techniques due to control problems of bulk-loaded liquid propellant guns and the instability of most monopropellants. Alternatively, one can revert back to the solid propellant and use new solid propellant techniques, including new modular charges, but neither Calzado y Bayo nor Atmos see this a possibility in their own school of thought. Both see enhanced performance and increased survivability as enough justification for the continued use of the regenerative liquid propellant gun. In many ways, it is completely necessary due to the design of the tank – for example, the Lince’s survivability (which uses a carousel autoloader) depends on the fact that the propellant is stored separate from the ammunition. As a consequence, the procurement of the CB.125 should depend entirely on the nation’s or army’s perspective on the technologies in use, as opposed to simply looking at the CB.125 as a very powerful tank gun – it’s a similar issue as the decision to use depleted uranium for a tank’s kinetic energy ammunition or not.
[OOC: Electrothermal-Chemical Technology for Tank Guns (http://z4.invisionfree.com/NSDraftroom/index.php?showtopic=1644)]
Recoil
Lighter vehicle platforms have recently been fielded with larger guns, and it’s understood that the CB.125 may be a chosen main gun for one such vehicle. Similar usage of its 120mm and 122mm (Castilla’s indigenous caliber) has already taken place, and therefore Calzado y Bayo has taken precautions to make this a possibility for the CB.125 as well. Recoil dampening is done in two principle ways, including the elongation of the recoil mechanism and the use of a muzzle break. In both case there are important things to take into consideration and generally this is one of the ‘weak points’ in some of Calzado y Bayo’s gun designs – long recoil mechanisms. However, it allows powerful guns such as these to be mounted in light anti-tank vehicles, such as reconnaissance cavalry armored vehicles (whether tracked or wheeled), or in mobile gun systems. Therefore, it’s logistically simpler since the same gun is used in multiple systems, as opposed to having to use an all new gun system. Furthermore, as mentioned and alluded to, it provides very light vehicles with before unforeseen firepower. Although these vehicles can’t compete with a main battle tank on a one on one basic, given that they lack of the main battle tank’s protection, mobility and hunter-killer abilities, it still provides them with an edge that they did not dispose of before. Another advantage is that it makes the gun available to nations that have chosen not to acquire any main battle tank under the argument that these are obsolescent and should be replaced by lighter, airmobile platforms. Truth to this ideology is not relevant to this discussion, and the important fact is that it widens the gun’s export market even beyond the main battle tank.
Muzzle brakes are difficult to add to guns mounted on armored vehicles due to noise production issues. On a tank destined to fight in large tank formations, against other tank formations, this might not necessarily be a major problem and in fact there might not be a need for a muzzle break at all, given the weight of the platform (generally at least fifty-five tons in weight). Muzzle brakes become much more relevant in lighter vehicle platforms, where the recoil impulse on the vehicle’s structure can cause major and permanent damage – enough to force the vehicle out of action. However, the issue remains tricky because these vehicles are designed primarily to operate with nearby dismounted infantry and enhanced noise production due to the muzzle break can be harmful to the soldier. Therefore, many designs which have previously included muzzle brakes have opted to remove them for the sake of the infantryman operating near the vehicle. On the other hand, efficient muzzle breaks are a ‘must’ for low-recoil weapons. Therefore, Calzado y Bayo have reverted to one of Atmos’ multi-hole pepperbox muzzle breaks, designed to decrease recoil and to reduce the firing and noise signature produced. Apart from reducing the noise signature and having an efficiency of around 40%, this type of muzzle break also helps in reducing the firing signature by means of lateral venting of the escaping propellant gasses. Furthermore, this muzzle break has no impact on fin-stabilized ammunition due to the attenuation of produced shockwaves as the round passes through the muzzle. Like always, it’s a trade-off between higher recoil efficiency and the added benefits of reduced noise and firing signatures. For example, the single-chamber muzzle break used on the Nakíl 1A3HA’s 140mm AGS.300 gun tube has an efficiency level of 70%! However, this gun is not expected to be mounted on a lighter vehicle and therefore it’s a reasonable choice.
The gun’s recoil mechanism is also longer ‘than usual’, as has become commonplace in guns designed by the same manufacturers. Usually, a gun of this caliber will have an extended recoil length of around 400-420mm, designed for a vehicle of generally the fifty ton class. In the case of the CB.125 the recoil length has been extended to 540mm, which is comparable to other guns meant for the twenty-five ton class, although there are some guns with extended recoil lengths of up to 710mm! It should be noted that this doesn’t necessarily make the CB.125 adequate for a twenty-ton platform, as the fact that it produces a high muzzle energy should be taken into account – although basic, basic recoil force is the same as the force of the round and of the propellant gasses leaving the barrel (conservation of momentum). Therefore, although recoil is attenuated to a fairly high degree for the energy produced by the gun, it doesn’t make the gun capable of being mounted on any lightweight vehicle. The CB.125 and CB.125E are best mounted on the vehicles of at least thirty metric tons of weight, or no lower than twenty-seven tons. Alternate versions of the gun, of course, can be designed with even larger extended recoil lengths to bring down recoil force even further, if a client is looking to apply the gun to a very low weight platform (even lower than twenty metric tons). The hydropneumatic recoil mechanism is housed in a titanium cylinder, while the mechanism’s trails are also manufactured out of titanium – this has already been done in lightweight artillery systems. It must be taken into consideration that an extended recoil travel means that the gun will require much more space between the breech and the vehicle’s roof or the turret basket’s floor (or whatever blocks the elevation of the gun) because that volume has to take into consideration the length of the recoil mechanism fully extended (when it’s absorbing the recoil of a shot). Consequently, it will affect turret height or the ability to depress the main gun. In the Nakíl 1A3 this is ‘solved’ (although, again, it’s a trade-off) through the use of a hydropneumatic suspension which allows the rear suspension components of the vehicle to lift, and therefore increase the level of depression by moving the tank as a whole.
As alluded to beforehand, similar techniques have already been retrofitted into existing tank guns and both Calzado y Bayo and Atmos Incorporated have integrated these ‘technologies’ into past guns. For example, the original AGS.250, mounted on the Nakíl 1A1 could be mounted on a twenty ton vehicle, and these trains continued to present itself on each successive Nakíl model. Due to the carro de combate Lince’s low weight of forty-five tons (light considering the amount of armor on both the turret and the chassis) similar techniques were used to lower the recoil of the advanced 103mm high-breech pressure gun, which affords the Lince an extraordinary amount of lethality for the caliber of the gun. In terms of attenuating recoil, in the CB.125 it’s not a priority besides attenuating it enough to make it possible to mount the gun on a lighter chassis. As has been underscored continuously, gun design is all about a series of trade-offs and in this case (recoil specific) both Calzado y Bayo and Atmos have agreed to form some sort of balance between weight, recoil attenuation and breech volume. Because it’s impossible to fulfill all objectives this is seen as the best possible solution, although individual nations may have individual requirements, prerequisites or ideologies on the subject.
[OOC: Large Caliber Tank Guns for Lightweight Platforms (http://z4.invisionfree.com/NSDraftroom/index.php?showtopic=2071)]
Weight
Total weight of the gun system has always been a very important consideration, in all tank designs – regardless if the tank weighs forty-five tons or if it weighs sixty-five tons. Nations have spent millions of dollars on introducing new tracks which save much less than what a lightweight gun system can possibly save – for example, nations have willingly modified entire tank fleets to apply tracks such as MecániCas’ Type 640 lightweight tracks (which for a sixty-five ton tank will shed around six hundred kilograms worth of weight). In a gun system the weight savings are similar, or potentially even greater, and depend entirely on the engineering applied to the gun and how much one is willing to spend on said gun system. Due to the nature of where the weight is saved, these weight savings might also make the gun system lighter and more compact which are equally as important (especially in a breech which has a greater recoil length). Lighter guns are also more acceptable to mount on lighter platforms, such as thirty-ton vehicles. Furthermore, all vehicles, regardless of their weight, have weight limits and therefore small weight savings are imperative to keep vehicles under their maximum allowable weight. This is most true for a main battle tank, despite the fact that it remains one of the heaviest ground vehicles in any army. Many times governments have the idea that since it already weighs sixty-five tons five more won’t hurt, and this is a fallacy – all nations have specific bridging requirements, and even one ton can affect the mobility of the tank over rivers, especially as tank designer teams increase armored thickness in order to defeat the evolving gun threat. These limits have always played an impact in tank design in both Castilla y Belmonte (especially with a tank that weighs forty-five tons) and the Second Empire of the Golden Throne (although bridging laws had to take into account that the Nakíl’s predecessor weighed almost ninety metric tons), and have affected the tank gun industry.
The tube itself is lightweight and comparable to barrels of the same caliber and length. It should be remembered that larger diameter betters are normally built thinner, because the barrel pressure per given volume or mass of propellant will be less than in a smaller caliber barrel. This explains the willingness of armies to upgrade calibers, instead of simply increasing propellant mass. To a point, it is no longer viable to continue strengthening the barrel to withstand higher pressure since this will result in more expensive manufacturing techniques and there is the chance that thicker materials are more likely to fail and therefore the barrel will still have a much lesser lifespan than a larger caliber gun barrel would have. This was an issue during the development of the Lince, especially when Castilla y Belmonte entered the design consortium formed between Vault 10, Lyras, The People’s Freedom and Castilla y Belmonte. Originally, the first and last nation argued about the possibility of a 70mm gun firing a sub-caliber projectile meant for the 103mm caliber, with the same muzzle energy. The latter country discarded the idea as unrealistic, given the already stated parameters of gun design, and therefore opted to adopt the indigenous CB.54 103mm tank gun on its own Lince. Vault 10 still has not completed its own tank design and there is no news on whether it will opt for the Lince or it will continue on its own indigenous tank program (possibly even more radical than the Lince). Regardless, given the information provided it can be assumed that the gun barrel is lightweight and comparable to the weight of a 120mm L/55 gun barrel (estimated at 1,347kg). Indeed, the gun barrel has a weight of roughly 1,470kg (taking into account the added length and total surface area, due to the larger barrel diameter). This compares favorably to the 2,500kg of weight of older 125mm gun barrels (125mm L/50).
Much weight has been saved in the breech, however – specifically, around 700kg! This is garnered through the increased use of titanium (for example, the recoil cylinders) and also through the elimination of redundant parts in the breech and the gun’s mounting. The elimination of these parts also represents a decrease in the volume of both the breech and the mounting system in the turret basket, which opens volume for other necessary items, such as electronics systems and battery units (for example, for the electric turret traverse brushless servo motors). The fact that a regenerative liquid propellant follows the ‘traveling charge concept’ and therefore increases pressure further down the barrel, as opposed to a solid propellant (in powder guns greater barrel pressure is established nearer to the breech, since the energy of the propellant dissipates), this allows weight savings in the barrel, as well, since the barrel can be designed to be lighter in different sections – the barrel’s geometry can be specifically designed to maximize its weight and the distribution of liner thickness. All of this makes for a dramatically lighter design. Between the breech, the gun mount and the barrel the CB.125 tank gun system weighs 3,210kg. When taking in mind the weight of the entire gun system the role of the muzzle brake becomes doubly as important, as it reduces shock induced stresses on its construction due to the recoil impulse. It should be reminded that the recoil length will not decrease the impulse felt by the gun (or by the crew) due to the recoil, although it will decrease the impulse of the recoil felt by the vehicle as a whole.
In terms of weight the CB.125 is one of the lightest guns in its caliber, similar to how the AGS.250C, the AGS.300 and the CB.54 are also some of the lightest gun systems in their caliber class. The technologies used to reduce the weight of the gun system, however, are not necessarily unique and have been applied to other gun systems around the world. What is true, on the other hand, is that both Calzado y Bayo and Atmos Incorporated have united all aspects of weight savings in order to minimize the weight of their gun systems. Furthermore, as two of the leading artillery-sized gun manufacturers in the world their respective engineers are some of the most adept to take into consideration all these different factors to decrease weight, and the quality of their gun systems have been manifested time and time again by the amount of clients the Nakíl receives. There is no doubt that the CB.125, as a gun system, will receive a similar amount of international attention. Boasts and ego aside, the CB.125 is likely to become a standard around the world, and even if it’s not directly acquired by foreign states it’s likely to be used as an example for indigenous tank gun development. These characteristics are what make these two gun companies world class leaders in their fields.
Conclusions
Whatever the features of the CB.125 it must be remembered that tank cannon technology is not everything that dictates a tank’s lethality. Although velocity and energy may play large and important roles in what is the accuracy of the round, so will the tank’s electronics. For example, some companies have claimed an increase of 35% in first-round hit probability (accuracy) through the addition of current-generation image intensifiers (II) and thermal sights. The tank’s fire control system, in general, including the dozens of sensors which the tank may include to maximize accuracy by taking into consideration minute details such as the gun trunnion’s axle cant, barrel droop, atmospheric pressure, et cetera, will also have a very big impact on the gun’s eventual accuracy. The gunner’s training, of course, cannot be ignored or taken out of the picture, and crew training in general will perhaps be the single most important aspect in any tank battle – as history has proven. In any case, it comes as no surprise that 60%+ of a tank’s cost is attributed to electronics, given the role these play in the tank’s lethality, survivability and mobility. The fact remains that clients should not take the CB.125 as the manifestation of accurate gunnery as there are a wide amount of variables that play in this factor. Nevertheless, the CB.125 is certainly one of the best guns in its class that can take into account all of these other factors and deliver the best performance it possibly can itself. In other words, each system must be refined individually and the CB.125, as a gun system (not including the electronics), is possibly the best a client can choose to use. The number of sales of the Nakíl and already signed contracts with foreign tank developers for the use of the gun has provided enough evidence.
Any client also has the guarantee that Calzado y Bayo will continue the development of tank gun technology, as has already been witnessed in the evolution of Atmos’ AGS.250 on the Nakíl main battle tank. This means that the company will always be working to provide its client with the best possible in the field – both Atmos and Calzado y Bayo have already been continuously been presenting the best gun options for the tank programs that they have partaken in, whether this be the Nakíl, Lince or Doomani MAD.V. Therefore, future improvements in liquid propellants, solid propellants, plasma emitters or any other technologies which can be applied to the gun are likely to be introduced as soon as possible – as research and feasibility allows – always putting the gun one step ahead of that of its competitors. Both companies have production history on their side to show facts, as opposed to promises. These companies will always have a vested interest in providing these improvements, given that they are constantly working on developments for their nation’s indigenous tanks, whether it be the Nakíl or the Lynx, and have almost always been willing to offer these to the general public. Of course, exports can be considered limited by the political policies of the Second Empire and of Castilla, but the gun systems can be purchased through ‘third parties’, including Doomingsland Defense Industries (by procuring the MAD.V) and through Sistemas Terrestres Segovia Land Systems (STSLS) by acquiring the Nakíl 1A3/1A3HA. The gun is also likely to be made available once it’s chosen by other tank producers for their own indigenous main battle tanks. Atmos’ gun-technology found on the Nakíl 1A1/1A1GU/1A1+ has already found itself on tanks such as the Lariat and possibly a wider array of main battle tanks across the world. It’s this resumé which clients can trust.
Beyond ‘conventional’ (or relatively conventional) improvements in the gun system, future possibilities include electromagnetic acceleration. Calzado y Bayo has been researching electromagnetic-chemical acceleration as a possible merging between electrothermal-chemical and electromagnetic propulsion concepts, and although it requires a larger source of energy than current guns it may become possible as electric parts for main battle tanks become more widespread – including new engine types and so forth. The coming of the electric transmission has already foreshadowed this possible transition in the future and Calzado y Bayo is sure to follow evolutionary trends, given that it has been this that has guaranteed the company’s success around the world. Pure electromagnetic guns have also been explored and both Atmos and Calzado y Bayo have partaken in some of the largest and most extensive rail gun tests around the world, but currently it’s not seen as a viable alternative due to the excessively large energy requirements. Unlike electrothermal-chemical propulsion, electromagnetic propulsion requires more energy input than it will eventually give out! With current energy storage capabilities it’s not feasible to mount such a weapon system in a tank, where volume is an important factor – perhaps with advancements in compulsators it will one day become possible. The Castillian artillery cannon company has been working with Astiversal, an important naval contractor in the kingdom, on a 400mm electromagnetic coastal gun which uses fixed power plants to provide the required energy and this program will offer very important insights in rail gun innovation that may play a role in the future to integrate the technology into a combat vehicle.
What is certain is that Atmos Incorporated and Calzado y Bayo are always looking at the future.
Production rights: $100,000 per system (this does not allow you to export the tank with the weapon system; any exports with the gun must be passed through us first); orders must be of 1,000+.
Program Details
The CB.125 is a further development of the AGS.250C, designed originally between Calzado y Bayo and Atmos for the Nakíl 1A3 main battle tank, to provide clients with what is considered the ultimate in tank gun technology besides electromagnetic acceleration – which is not considered currently feasible, given electricity storage issues. The Nakíl is a widely exported main battle tank, with close to ten million vehicles of all six known production models (1A1, 1A1GU, 1A1+, 1A2, 1A3 and 1A3HA) sold to date (not including modification packages to upgrade already-assembled tanks), and continues to be substantially popular on the export market, especially in its latest incarnations – the Nakíl 1A3 and the Nakíl 1A3HA. Therefore, it wasn’t a surprise to either Kriegzimmer or Sistemas Terrestres Segovia when new customers arrived, but without the intention of changing calibers - the first such customer was Cotland, with a contract for seventy-two thousand Nakíl main battle tanks. Although technically the change in caliber, from the perspective of retrofitting the 120mm gun, is economically feasible given that it’s part of the modification package, the change in ammunition and the redistribution of millions of shells might not be. Historically, this issue has played a major role in limiting the sale of the Nakíl to historical users of the 120mm caliber and only to those willing to change, and has not allowed the Nakíl to make a large impact in the mainstream 125mm market – where tank companies from nations such as Doomingsland, Soviet Bloc and Aequatio still remain supreme. Calzado y Bayo’s CB.125 not only opens the Nakíl to a much larger tank market, but also allows Calzado y Bayo to play a major role in foreign tank industries by marketing the tank gun for foreign indigenous tank programs.
In the latter’s regard, the Castillian defense company has already scored a major contract with Doomingsland Defense Industries for the sale of production rights to the CB.125 for the modification program of the country’s current main battle tank and the possibility of using the tank gun in a future tank. This not only affects sales to the Doomani military, but also any exports which the MAD.V may be able to contract abroad. In this case, the CB.125 is actually a separate development to that offered for the Nakíl 1A3, although the technology remains basically the same. The version of the gun offered on the general export market is the CB.125E (Exportación) and comes with a dual-caliber breech, but with the capability of fitting either a 120mm or 125mm cannon. This is largely meant to suggest an effort for the eventual conversion to 120mm for customers, even if some may never commit to it – it gives them the option to easily modify existing tanks, if they feel that they can handle the remanufacture of ammunition. The CB.125, offered for the Nakíl, on the other hand offers the dual-caliber breech for either a 125mm gun tube or a 140mm gun tube. In all actuality, this is not completely accurate as either breech can be offered, depending on the client nation’s chance of being able to receive the larger gun caliber in the future – for example, Cottish Nakíl 1A3Cs will receive the 125/140mm dual-caliber breech, foreseeing a possible future decision to modify all tanks in service to 1A3HA (heavy armor) standards (currently, Cottish forces operate 70,000 Nakíl 1A3Cs and 2,000 Nakíl 1A3HAs for elite forces). The decision to not offer this option on the CB.125E is for a number of reasons, including the fact that 140mm might not be the preferred ‘larger caliber’ of the client nation (as opposed to 135mm or 152mm, for example) and Calzado y Bayo is not readily willing to facilitate this modification, given that it will allow foreign designs to compete with the Nakíl 1A3HA at the same low cost.
In the Nakíl’s case, the modification of the gun comes with other challenges as well. The autoloading system, including the two FASTDRAW revolvers near the rear of the turret, is designed specifically for either 120mm ammunition or 140mm ammunition, and there is no major production line for a 125mm variant. Regardless, Calzado y Bayo currently works in conjunction with the Castillian defense company Cibeles Dynámica, which focuses on autoloading systems for different systems (including naval cannons), for the production of a 125mm version of the Nakíl’s autoloader. The cost is the depression of the revolvers and their slight increase in size, and the depression of the robotic autoloading system (RALS), which means there is less available volume in the turret basket. As a consequence, Sistemas Terrestres Segovia and Imperial Land Systems instead decided to decrease the amount of available spare ammunition in fireproof cases suspended near the turret basket’s floor. In terms of length and required volume, the breech is similar given that in the original version of the gun it’s designed also for a full long-rod penetrator of the 140mm caliber and in the E version it’s designed for an extended length long-rod of the 120mm caliber; in other words, in the latter’s case penetrator length is likely to be similar. The gun tube is similar in length, as well – a 120mm L/57 compared to a 125mm L/55. Consequently, no major changes in the internal volume of the Nakíl are necessary, while the breech is designed to easily replacing existing 125mm breeches. In other words, for the most part complicated turret remodeling is not necessary in this case.
The gun, in all variants, will be produced by a number of different companies. These include Calzado y Bayo, Sistemas Terrestres Segovia (which has a much more extensive industrial complex around the world), Kriegzimmer (which is a co-producer of the Nakíl tank) and Atmos. The CB.125E for Doomingsland will be manufactured by Sistemas Terrestres Segovia and by Kriegzimmer in a joint-assembly program, mostly due to the fact that the latter has much more extensive capabilities to produce the gun in large numbers. Both companies, however, will use exclusively factory grounds in Doomingsland, as the contract requires. The gun, when manufactured for exported Doomani tanks, will most likely be produced in Doomani territory as much as possible, although it’s likely that production will spill to ‘overseas’ factories if the demand for the MAD.V is high. Guns manufactured for the Nakíl 1A3C will be manufactured exclusively by Calzado y Bayo and will be shipped to Kriegzimmer assembly plants for final installation in the Nakíl 1A3C turret, before the tank as a whole is shipped to Cotland. Future, independent, sales will most likely be co-produced between the Castillian gun company and Atmos, its Macabee counterpart, depending on the amount of sales it receives. It’s entirely possible that production rights will be awarded to foreign companies to market the gun in other nations, arguing that the gun is completely indigenous (since it will be produced indigenously). Similar marketing strategies have been followed in nations such as Juumanistra to sell a wide array of technology to a country largely unwilling to adopt foreign weapon systems, especially in regards to tank technology (the Juumanistran Kyton main battle tank has cost the country anywhere between $25 and $35 million per vehicle, and costs have continued to spiral as indigenous companies continue to develop modification packages to upgrade the tank to international standards).
Propulsive Technology
Today’s armored threats require extremely high powered main guns to have any hopes in perforating their armor. This gun versus armor race has led to a speedy development of ‘next-generation’ technologies, although many of these are still not viable – such as electromagnetic acceleration. Originally, the goal was to reach previously unattainable velocities in order to engage the target faster and increase the accuracy of the projectile, but recently there instead has been a decision to increase projectile mass by increasing its diameter. Regardless of whether the goal is to increase projectile velocity or projectile mass, they both require one thing – increased muzzle energy. There are a multitude of ways that this can be accomplished, including increasing the volume of the propellant charge in a conventional powder (solid propellant) cannon. Normally, each barrel, in accordance with the internal surface area of the tube, has a specific pressure it can withstand from the expanding propellant and therefore it’s normal to see an increase in caliber when the propellant charge has been enlarged to such a degree that it is no longer viable to use in an existing diameter gun barrel. Consequently, it’s not rare to find tanks with larger caliber tank guns, which unfortunately also require larger volumes inside tank turrets. There are, of course, alternative technologies – as mentioned – and the CB.125 follows this such school of thought, preferring new technologies to having to increase barrel caliber. In accordance with this, Calzado y Bayo have decided to offer what they consider the most advanced tank gun propulsion technology currently technologically feasible or known in the CB.125 – for many, this will be the best tank cannon (in this caliber) available on the market and it will certainly give the Doomani MAD.V an edge over competitors that do not use this gun.
Perhaps the most outstanding feature is the fact that it uses electrothermal-chemical (ETC) augmentation. Ultimately, this can be achieved in several different ways, but in the CB.125 specifically the round is designed to have an electrothermal ignition (ETI) charge which requires less than 100kJ per shot (the power supply is not an issue with the gun and is up to the client to decide how to provide this power – in the Nakíl 1A3, for instance, there is a pulsed power supply to the rear of the turret, while in the Nakíl 1A3HA the power is provided by the batteries which form part of the electric transmission). Consequently, the round or combustion chamber is likely to have a series of copper wires with embedded diamonds, or any other material which will provide the same effect, which will discharge plasma due to the vaporization of the material if electrically charged. Specifically, this type of plasma emitter is known as a flashboard large area emitter (FLARE) or a variation thereof. Due to the propellant type used in the CB.125 (discussed below), the plasma emitter is located as part of a completely combustible modular cartridge that forms part of the round (in solid propellant guns, for the most part semi-combustible propellant cartridges are used), containing only the emitter. The plasma completes a number of important jobs, including decreasing the molecular volume of the propellant and therefore increasing muzzle energy. The plasma is also used to ignite the propellant, to catalyze its expansion, and to control the rate of expansion of the propellant to make it much more effective in regards to maximizing its potential. In a 120mm solid propellant gun, for example, electrothermal-chemical combustion is known to increase muzzle energy from 9mJ to 18mJ, which effectively doubles the energy of the gun (more accurately, it can increase muzzle energy anywhere from 15mJ to 18mJ, approximately – exact figures are difficult to come by).
As already mentioned, the CB.125 – like in most tank guns produced by either Atmos or Calzado y Bayo – uses a hydroxyl ammonium nitrate (HAN) based liquid propellant, instead of a solid propellant. Contrary to popular belief, although liquid propellants do increase the piezometric efficiency – that is, the advantage of having a higher mean to peak chamber pressure – and therefore may have an increase in muzzle velocity (perhaps around 10% higher), they do not have a higher ballistic efficiency as compared to solid propellants. Therefore, technically, in order to achieve the same muzzle energy a liquid propellant needs more mass than their solid propellant counterpart, but it is also true that a liquid propellant requires less volume – in this case, the amount of energy per gram of the propellant is similar to a solid propellants (a little over 5,000kj/g), but require only about 70% the volume. To give an idea on the volume advantages a solid propellant has, at best, a loading density of 1,000kg/m3, while this specific liquid propellant (based on the real-life LGP 1846) has a loading density of over 1,500 kg/m3. Further savings in space arise from the fact that a liquid propellant is stored in closed cells, in bulk, while solid propellants must be stored with their respective ammunition in charge modules or bags. Specifically, the CB.125 uses a regenerative liquid propellant gun (RLPG) which has the liquid propellant metered into the combustion chamber by means of an injection pump – it should be noted that liquid propellants are easier to manufacture than solid propellants and are also cheaper (30-50% so). Unfortunately, regenerative guns are mechanically complex, but trade complexity for increased control of the propellant – a worthwhile trade. Just like its 120mm brother, the CB.125 uses a high-breech pressure charge, which means that the charge volume is larger than what is necessary in order to increase muzzle energy. This is possible not only because of the burn efficiency of a liquid propellant, but also because the gun barrel is coated with chrome to allow for increased barrel pressures. There are certain safety concerns with liquid propellants, and these should be addressed. Since liquid propellants can be separated from their respective projectiles and stored in protected and closed cells inside the turret, they have an added advantage over solid propellants – as mentioned above. Therefore, they can be better protected by the turret’s armor and if the ammunition compartment is breached it means that the ammunition will not react violently, unlike in many solid propellant tank designs (especially designs with carousel autoloaders, or ammunition in the turret basket). Furthermore, bipropellants such as HAN-based propellants cannot react on their own and require both parts of the propellant to interact in order to allow the reaction (which is truly catalyzed through the electric discharge, regardless). Therefore, it can be considered stable and less vulnerable than their solid propellant competitors.
A recent addition to the union of liquid propellants and electrothermal chemical technology, also known as a liquid propellant electrothermal-chemical (LPETC) gun, is chemically augmented combustion (CAC). This is similar to electrothermal-chemical combustion, but less radical, and can be used to increase the potential of electrothermal-chemical reactions even further. Chemically augmented combustion has been a very recent addition to the Nakíl, and is only present in the AGS.250C and the AGS.300 (the 140mm version) – this technology is likely to be retrofitted into a future variant of the CB.54 103mm gun present on the carro de combate Lince, used by the Castillian Ejército de Tierra. Technically speaking, chemically augmented combustion is not either new or old, and was ‘developed’ around the same time as electrothermal-chemical technology – as said before, it’s simply a much less radical approach, although with many less benefits (if applied alone). This technology can be known under many other names including hydrogen augmented combustion (HAC) and propellant energizing technology (PET). When applied to an electrothermal-chemical gun is can also be known as hydrogen propellant electro-chemical (HYPEC) combustion. In essence, this behaves similar to electrothermal-chemical technology in one respect, in which that it can convert high molecular weights to low molecular weights through chemical means, which means in high produced muzzle velocities or energy. This technology is somewhat easy to apply given that the hydrogen can be produced by an electrothermal reaction in the combustion chamber, which forms part of the electrothermal-chemical process. Despite the less radical approach, this technology is relatively unheard of since it has not been widely marketed and this is one of the first times it has been applied to an actual field gun (the AGS.250C and the AGS.300, before the CB.125).
All of this technology integrated into the gun makes the CB.125 what is most likely the most powerful gun of this caliber, although it’s also true that it also makes the CB.125 very mechanically complex. However, it all has to do with a series of trade-offs which one country might see as justifiable and the other may not. The most mechanically complex portion of the gun is the regenerative liquid propellant, which unfortunately is currently difficult to solve using other liquid propellant combustion techniques due to control problems of bulk-loaded liquid propellant guns and the instability of most monopropellants. Alternatively, one can revert back to the solid propellant and use new solid propellant techniques, including new modular charges, but neither Calzado y Bayo nor Atmos see this a possibility in their own school of thought. Both see enhanced performance and increased survivability as enough justification for the continued use of the regenerative liquid propellant gun. In many ways, it is completely necessary due to the design of the tank – for example, the Lince’s survivability (which uses a carousel autoloader) depends on the fact that the propellant is stored separate from the ammunition. As a consequence, the procurement of the CB.125 should depend entirely on the nation’s or army’s perspective on the technologies in use, as opposed to simply looking at the CB.125 as a very powerful tank gun – it’s a similar issue as the decision to use depleted uranium for a tank’s kinetic energy ammunition or not.
[OOC: Electrothermal-Chemical Technology for Tank Guns (http://z4.invisionfree.com/NSDraftroom/index.php?showtopic=1644)]
Recoil
Lighter vehicle platforms have recently been fielded with larger guns, and it’s understood that the CB.125 may be a chosen main gun for one such vehicle. Similar usage of its 120mm and 122mm (Castilla’s indigenous caliber) has already taken place, and therefore Calzado y Bayo has taken precautions to make this a possibility for the CB.125 as well. Recoil dampening is done in two principle ways, including the elongation of the recoil mechanism and the use of a muzzle break. In both case there are important things to take into consideration and generally this is one of the ‘weak points’ in some of Calzado y Bayo’s gun designs – long recoil mechanisms. However, it allows powerful guns such as these to be mounted in light anti-tank vehicles, such as reconnaissance cavalry armored vehicles (whether tracked or wheeled), or in mobile gun systems. Therefore, it’s logistically simpler since the same gun is used in multiple systems, as opposed to having to use an all new gun system. Furthermore, as mentioned and alluded to, it provides very light vehicles with before unforeseen firepower. Although these vehicles can’t compete with a main battle tank on a one on one basic, given that they lack of the main battle tank’s protection, mobility and hunter-killer abilities, it still provides them with an edge that they did not dispose of before. Another advantage is that it makes the gun available to nations that have chosen not to acquire any main battle tank under the argument that these are obsolescent and should be replaced by lighter, airmobile platforms. Truth to this ideology is not relevant to this discussion, and the important fact is that it widens the gun’s export market even beyond the main battle tank.
Muzzle brakes are difficult to add to guns mounted on armored vehicles due to noise production issues. On a tank destined to fight in large tank formations, against other tank formations, this might not necessarily be a major problem and in fact there might not be a need for a muzzle break at all, given the weight of the platform (generally at least fifty-five tons in weight). Muzzle brakes become much more relevant in lighter vehicle platforms, where the recoil impulse on the vehicle’s structure can cause major and permanent damage – enough to force the vehicle out of action. However, the issue remains tricky because these vehicles are designed primarily to operate with nearby dismounted infantry and enhanced noise production due to the muzzle break can be harmful to the soldier. Therefore, many designs which have previously included muzzle brakes have opted to remove them for the sake of the infantryman operating near the vehicle. On the other hand, efficient muzzle breaks are a ‘must’ for low-recoil weapons. Therefore, Calzado y Bayo have reverted to one of Atmos’ multi-hole pepperbox muzzle breaks, designed to decrease recoil and to reduce the firing and noise signature produced. Apart from reducing the noise signature and having an efficiency of around 40%, this type of muzzle break also helps in reducing the firing signature by means of lateral venting of the escaping propellant gasses. Furthermore, this muzzle break has no impact on fin-stabilized ammunition due to the attenuation of produced shockwaves as the round passes through the muzzle. Like always, it’s a trade-off between higher recoil efficiency and the added benefits of reduced noise and firing signatures. For example, the single-chamber muzzle break used on the Nakíl 1A3HA’s 140mm AGS.300 gun tube has an efficiency level of 70%! However, this gun is not expected to be mounted on a lighter vehicle and therefore it’s a reasonable choice.
The gun’s recoil mechanism is also longer ‘than usual’, as has become commonplace in guns designed by the same manufacturers. Usually, a gun of this caliber will have an extended recoil length of around 400-420mm, designed for a vehicle of generally the fifty ton class. In the case of the CB.125 the recoil length has been extended to 540mm, which is comparable to other guns meant for the twenty-five ton class, although there are some guns with extended recoil lengths of up to 710mm! It should be noted that this doesn’t necessarily make the CB.125 adequate for a twenty-ton platform, as the fact that it produces a high muzzle energy should be taken into account – although basic, basic recoil force is the same as the force of the round and of the propellant gasses leaving the barrel (conservation of momentum). Therefore, although recoil is attenuated to a fairly high degree for the energy produced by the gun, it doesn’t make the gun capable of being mounted on any lightweight vehicle. The CB.125 and CB.125E are best mounted on the vehicles of at least thirty metric tons of weight, or no lower than twenty-seven tons. Alternate versions of the gun, of course, can be designed with even larger extended recoil lengths to bring down recoil force even further, if a client is looking to apply the gun to a very low weight platform (even lower than twenty metric tons). The hydropneumatic recoil mechanism is housed in a titanium cylinder, while the mechanism’s trails are also manufactured out of titanium – this has already been done in lightweight artillery systems. It must be taken into consideration that an extended recoil travel means that the gun will require much more space between the breech and the vehicle’s roof or the turret basket’s floor (or whatever blocks the elevation of the gun) because that volume has to take into consideration the length of the recoil mechanism fully extended (when it’s absorbing the recoil of a shot). Consequently, it will affect turret height or the ability to depress the main gun. In the Nakíl 1A3 this is ‘solved’ (although, again, it’s a trade-off) through the use of a hydropneumatic suspension which allows the rear suspension components of the vehicle to lift, and therefore increase the level of depression by moving the tank as a whole.
As alluded to beforehand, similar techniques have already been retrofitted into existing tank guns and both Calzado y Bayo and Atmos Incorporated have integrated these ‘technologies’ into past guns. For example, the original AGS.250, mounted on the Nakíl 1A1 could be mounted on a twenty ton vehicle, and these trains continued to present itself on each successive Nakíl model. Due to the carro de combate Lince’s low weight of forty-five tons (light considering the amount of armor on both the turret and the chassis) similar techniques were used to lower the recoil of the advanced 103mm high-breech pressure gun, which affords the Lince an extraordinary amount of lethality for the caliber of the gun. In terms of attenuating recoil, in the CB.125 it’s not a priority besides attenuating it enough to make it possible to mount the gun on a lighter chassis. As has been underscored continuously, gun design is all about a series of trade-offs and in this case (recoil specific) both Calzado y Bayo and Atmos have agreed to form some sort of balance between weight, recoil attenuation and breech volume. Because it’s impossible to fulfill all objectives this is seen as the best possible solution, although individual nations may have individual requirements, prerequisites or ideologies on the subject.
[OOC: Large Caliber Tank Guns for Lightweight Platforms (http://z4.invisionfree.com/NSDraftroom/index.php?showtopic=2071)]
Weight
Total weight of the gun system has always been a very important consideration, in all tank designs – regardless if the tank weighs forty-five tons or if it weighs sixty-five tons. Nations have spent millions of dollars on introducing new tracks which save much less than what a lightweight gun system can possibly save – for example, nations have willingly modified entire tank fleets to apply tracks such as MecániCas’ Type 640 lightweight tracks (which for a sixty-five ton tank will shed around six hundred kilograms worth of weight). In a gun system the weight savings are similar, or potentially even greater, and depend entirely on the engineering applied to the gun and how much one is willing to spend on said gun system. Due to the nature of where the weight is saved, these weight savings might also make the gun system lighter and more compact which are equally as important (especially in a breech which has a greater recoil length). Lighter guns are also more acceptable to mount on lighter platforms, such as thirty-ton vehicles. Furthermore, all vehicles, regardless of their weight, have weight limits and therefore small weight savings are imperative to keep vehicles under their maximum allowable weight. This is most true for a main battle tank, despite the fact that it remains one of the heaviest ground vehicles in any army. Many times governments have the idea that since it already weighs sixty-five tons five more won’t hurt, and this is a fallacy – all nations have specific bridging requirements, and even one ton can affect the mobility of the tank over rivers, especially as tank designer teams increase armored thickness in order to defeat the evolving gun threat. These limits have always played an impact in tank design in both Castilla y Belmonte (especially with a tank that weighs forty-five tons) and the Second Empire of the Golden Throne (although bridging laws had to take into account that the Nakíl’s predecessor weighed almost ninety metric tons), and have affected the tank gun industry.
The tube itself is lightweight and comparable to barrels of the same caliber and length. It should be remembered that larger diameter betters are normally built thinner, because the barrel pressure per given volume or mass of propellant will be less than in a smaller caliber barrel. This explains the willingness of armies to upgrade calibers, instead of simply increasing propellant mass. To a point, it is no longer viable to continue strengthening the barrel to withstand higher pressure since this will result in more expensive manufacturing techniques and there is the chance that thicker materials are more likely to fail and therefore the barrel will still have a much lesser lifespan than a larger caliber gun barrel would have. This was an issue during the development of the Lince, especially when Castilla y Belmonte entered the design consortium formed between Vault 10, Lyras, The People’s Freedom and Castilla y Belmonte. Originally, the first and last nation argued about the possibility of a 70mm gun firing a sub-caliber projectile meant for the 103mm caliber, with the same muzzle energy. The latter country discarded the idea as unrealistic, given the already stated parameters of gun design, and therefore opted to adopt the indigenous CB.54 103mm tank gun on its own Lince. Vault 10 still has not completed its own tank design and there is no news on whether it will opt for the Lince or it will continue on its own indigenous tank program (possibly even more radical than the Lince). Regardless, given the information provided it can be assumed that the gun barrel is lightweight and comparable to the weight of a 120mm L/55 gun barrel (estimated at 1,347kg). Indeed, the gun barrel has a weight of roughly 1,470kg (taking into account the added length and total surface area, due to the larger barrel diameter). This compares favorably to the 2,500kg of weight of older 125mm gun barrels (125mm L/50).
Much weight has been saved in the breech, however – specifically, around 700kg! This is garnered through the increased use of titanium (for example, the recoil cylinders) and also through the elimination of redundant parts in the breech and the gun’s mounting. The elimination of these parts also represents a decrease in the volume of both the breech and the mounting system in the turret basket, which opens volume for other necessary items, such as electronics systems and battery units (for example, for the electric turret traverse brushless servo motors). The fact that a regenerative liquid propellant follows the ‘traveling charge concept’ and therefore increases pressure further down the barrel, as opposed to a solid propellant (in powder guns greater barrel pressure is established nearer to the breech, since the energy of the propellant dissipates), this allows weight savings in the barrel, as well, since the barrel can be designed to be lighter in different sections – the barrel’s geometry can be specifically designed to maximize its weight and the distribution of liner thickness. All of this makes for a dramatically lighter design. Between the breech, the gun mount and the barrel the CB.125 tank gun system weighs 3,210kg. When taking in mind the weight of the entire gun system the role of the muzzle brake becomes doubly as important, as it reduces shock induced stresses on its construction due to the recoil impulse. It should be reminded that the recoil length will not decrease the impulse felt by the gun (or by the crew) due to the recoil, although it will decrease the impulse of the recoil felt by the vehicle as a whole.
In terms of weight the CB.125 is one of the lightest guns in its caliber, similar to how the AGS.250C, the AGS.300 and the CB.54 are also some of the lightest gun systems in their caliber class. The technologies used to reduce the weight of the gun system, however, are not necessarily unique and have been applied to other gun systems around the world. What is true, on the other hand, is that both Calzado y Bayo and Atmos Incorporated have united all aspects of weight savings in order to minimize the weight of their gun systems. Furthermore, as two of the leading artillery-sized gun manufacturers in the world their respective engineers are some of the most adept to take into consideration all these different factors to decrease weight, and the quality of their gun systems have been manifested time and time again by the amount of clients the Nakíl receives. There is no doubt that the CB.125, as a gun system, will receive a similar amount of international attention. Boasts and ego aside, the CB.125 is likely to become a standard around the world, and even if it’s not directly acquired by foreign states it’s likely to be used as an example for indigenous tank gun development. These characteristics are what make these two gun companies world class leaders in their fields.
Conclusions
Whatever the features of the CB.125 it must be remembered that tank cannon technology is not everything that dictates a tank’s lethality. Although velocity and energy may play large and important roles in what is the accuracy of the round, so will the tank’s electronics. For example, some companies have claimed an increase of 35% in first-round hit probability (accuracy) through the addition of current-generation image intensifiers (II) and thermal sights. The tank’s fire control system, in general, including the dozens of sensors which the tank may include to maximize accuracy by taking into consideration minute details such as the gun trunnion’s axle cant, barrel droop, atmospheric pressure, et cetera, will also have a very big impact on the gun’s eventual accuracy. The gunner’s training, of course, cannot be ignored or taken out of the picture, and crew training in general will perhaps be the single most important aspect in any tank battle – as history has proven. In any case, it comes as no surprise that 60%+ of a tank’s cost is attributed to electronics, given the role these play in the tank’s lethality, survivability and mobility. The fact remains that clients should not take the CB.125 as the manifestation of accurate gunnery as there are a wide amount of variables that play in this factor. Nevertheless, the CB.125 is certainly one of the best guns in its class that can take into account all of these other factors and deliver the best performance it possibly can itself. In other words, each system must be refined individually and the CB.125, as a gun system (not including the electronics), is possibly the best a client can choose to use. The number of sales of the Nakíl and already signed contracts with foreign tank developers for the use of the gun has provided enough evidence.
Any client also has the guarantee that Calzado y Bayo will continue the development of tank gun technology, as has already been witnessed in the evolution of Atmos’ AGS.250 on the Nakíl main battle tank. This means that the company will always be working to provide its client with the best possible in the field – both Atmos and Calzado y Bayo have already been continuously been presenting the best gun options for the tank programs that they have partaken in, whether this be the Nakíl, Lince or Doomani MAD.V. Therefore, future improvements in liquid propellants, solid propellants, plasma emitters or any other technologies which can be applied to the gun are likely to be introduced as soon as possible – as research and feasibility allows – always putting the gun one step ahead of that of its competitors. Both companies have production history on their side to show facts, as opposed to promises. These companies will always have a vested interest in providing these improvements, given that they are constantly working on developments for their nation’s indigenous tanks, whether it be the Nakíl or the Lynx, and have almost always been willing to offer these to the general public. Of course, exports can be considered limited by the political policies of the Second Empire and of Castilla, but the gun systems can be purchased through ‘third parties’, including Doomingsland Defense Industries (by procuring the MAD.V) and through Sistemas Terrestres Segovia Land Systems (STSLS) by acquiring the Nakíl 1A3/1A3HA. The gun is also likely to be made available once it’s chosen by other tank producers for their own indigenous main battle tanks. Atmos’ gun-technology found on the Nakíl 1A1/1A1GU/1A1+ has already found itself on tanks such as the Lariat and possibly a wider array of main battle tanks across the world. It’s this resumé which clients can trust.
Beyond ‘conventional’ (or relatively conventional) improvements in the gun system, future possibilities include electromagnetic acceleration. Calzado y Bayo has been researching electromagnetic-chemical acceleration as a possible merging between electrothermal-chemical and electromagnetic propulsion concepts, and although it requires a larger source of energy than current guns it may become possible as electric parts for main battle tanks become more widespread – including new engine types and so forth. The coming of the electric transmission has already foreshadowed this possible transition in the future and Calzado y Bayo is sure to follow evolutionary trends, given that it has been this that has guaranteed the company’s success around the world. Pure electromagnetic guns have also been explored and both Atmos and Calzado y Bayo have partaken in some of the largest and most extensive rail gun tests around the world, but currently it’s not seen as a viable alternative due to the excessively large energy requirements. Unlike electrothermal-chemical propulsion, electromagnetic propulsion requires more energy input than it will eventually give out! With current energy storage capabilities it’s not feasible to mount such a weapon system in a tank, where volume is an important factor – perhaps with advancements in compulsators it will one day become possible. The Castillian artillery cannon company has been working with Astiversal, an important naval contractor in the kingdom, on a 400mm electromagnetic coastal gun which uses fixed power plants to provide the required energy and this program will offer very important insights in rail gun innovation that may play a role in the future to integrate the technology into a combat vehicle.
What is certain is that Atmos Incorporated and Calzado y Bayo are always looking at the future.
Production rights: $100,000 per system (this does not allow you to export the tank with the weapon system; any exports with the gun must be passed through us first); orders must be of 1,000+.