NationStates Jolt Archive

[OOC: RP of purchase is mandated; "I want X" will not suffice. Funding checks shall be made, as well, using ThirdGeek; for any given NS year, it is assumed that 20% of your defense budget is allotted for procurement, unless specifically stated within the RP of purchase that you are undertaking some form of enlargement in which full defense budget will be considered for purchasing power. Nations with no ThirdGeek defense budget will be assumed as having defense spending equal to 1% of GDP.]

http://www.globalsecurity.org/military/world/israel/images/merkava001.jpg

JBT-31 Centurion Alternate Battle Tank
Manufacturer: Himou Defense Labs and Minaduki Arms
Inspiration: None
Type: Alternate battle tank
Dimensions(L*W*H): 9.5*3.5*2.95m
Weight: 62 tons
Crew: 4 + 5(driver, gunner, loader, commander, and five passengers)
Engine: 1300hp Khevron Drives K4 Bloc rotary diesel/electric hybrid
Maximum Range: 645km
Maximum Speed(on-road/off-road): 90kph/75mph
Armament: One turret-mounted Avenger smoothbore 120mm cannon, two MAPEN hardpoints, two MOSWES hardpoints
Ammunition: 48x120mm, various others according to MAPEN/MOSWES configuration
Armor(AvRHA, front/sides/rear): 1550mm/850mm/450mm

Five years ago, the Department of Defense and the Juumanistran Army came to the conclusion that the JBT-14A4 ABT was rapidly reaching the end of its service life; there were too many new, heavier tanks on the battlefield for the A4 frame to maintain its presence and that serious work would be required in order to keep the JBT-14 a force on the modern battlefield. So, that left the Defense Department with three options; procurement of a new, off-the-shelf vehicle to fill the JBT-14's role, the development of an A5 upgrade package, or the development of an entirely new vehicle. When preliminary estimates came back from Himou Defense Labs that an A5 series would require extensive reworking of the JBT-14's armor and internal systems at a development price tag equal to half of what the Army estimated development of an entirely new vehicle would cost, the A5 project was dropped and the green light given fore the development of a new medium-weight, all-purpose main combat vehicle under the rubric of the alternate battle tank that sought to incorporate the successes of the JBT-14 as well as remedy some of its more notable flaws, in-particular relatively weak all-terrain performance and the problematic Driller gunnery system.

The vehicle that resulted from the project to replace the JBT-14 was a co-op between Himou Defense Labs, the original manufacturer of the JBT-14, and Minaduki Arms, the firm responsible for the production of Juumanistra’s principle MBT, the JBT-24. Dubbed the JBT-31 Centurion, it has entered full-scale service within the Juumanistran service and has acquired the Congress’s and Defense Department’s seal of approval for export, in hopes of reaffirming Juumanistra’s image as a producer of quality defense systems.

Weapons

The JBT-31's main weapon is a single 120mm smoothbore, high-velocity 44-caliber Avenger cannon. Capable of attaining a muzzle velocity of 1.75km/s from stock APFSDS rounds, the Minaduki Arms standard cannon replaces the somewhat temperamental HDL/Fujisaki Consortium co-op 120mm smoothbore 52-caliber Driller with a stout and rugged system renowned for its capacity to fire under even the worst of conditions. The weapon boasted on the JBT-31, however, is a much shorter version of the Avenger that is featured on the JBT-24, down to 44 calibers from the JBT-24's 58. This shortening of the main gun’s barrel from 58 calibers down to 44 instead of, say the 52 calibers found on the JBT-14, comes in response to complaints from tank commanders that the gun was cumbersome in urban environments. The loss of over a meter of barrel length has been met with pleasant feedback from Juumanistran commanders thus far, though there has been some murmuring among older salts about the loss of effective killing range; the maximum kill range for the Driller was 8.6km, whilst the shortened Avenger tips the scales at 5.8km. The turret is capable of storing up to 48 120mm rounds at any given time, without taking up room allotted for other munitions or systems.

The JBT-31 gets rid of the uniquely Juumanistran Multiple Integrated Recoilless Rifle System(MIRRS) supplemental weapons system in favor of Modular Supplemental Weapons System(MOSWES). The conventional loadout for MOSWES in the Juumanistran Army is the MIRRS configuration of four 112mm recoilless rifles armed with Ironhorn ATGMs, though most other 112mm rockets are supported(anti-personnel cluster munitions are another favorite of Juumanistran tankers). The internal MIRRS loading points to facilitate the use of internal stowed rounds have been retained and have been supplemented by a pair of 80mm upward loading points, one on each side of the turret, to facilitate the use of MOSWES mortars. MOSWES, in the end, boasts the capability to a modular version of MIRRS, two mortars with breeches of up to 80mm, two tube-launched intermediate range surface-to-air missiles, two quad-cells of shorter range surface-to-air missiles, or two quad-cells of heavy ATGMs with no difficulty, with internal reloading capacity on MIRRS and mortars. Juumanistra has also run tests mounting six-barrel 30mm Vulcan guns on one of the MOSWES ports and the results have been encouraging, though some hardpoint renovation is required in order to successfully bear the additional weight and make it possible for the gun to be belt-fed from within the tank.

Rounding out the JBT-31's weapon systems are a pair of Modular Anti-Personnel Gun(MAPEN) mounts on the commander’s and driver’s sides of the turret. Each MAPEN mount is capable of bearing of a gun in the world of up to 20 millimeters in breech diameter, though HDL has succeeded in mounting heavier guns(in one of the funnier moments of development, HDL designers actually succeeded in mounting a stripped down version of one of the Vulcans used in MOSWES testing onto a MAPEN mount and got it to fire, though the recoil sheered it off after the third shot), so a weight rating of 45kg would probably be a better gauge of mounting capabilities. Each MAPEN mount boasts co-axial movement capabilities and are fully electric, so as to allow their aiming and firing from within the tank so as the minimize crew risks.

Armor

The designers at HDL and Minaduki Arms were posed with a rather daunting task. How were they supposed to provide improvements to average RHA, the Juumanistran favored means of measuring armor, in-excess of 25% over the JBT-14 while incorporating MOSWES and new sensors into the armor scheme, all without producing anything beyond “marginal” weight gains? The answer would come by turning Juumanistran armor production methodology on its head.

Juumanistra has, for decades, maintained two distinct armor schemes: Aegis, a composite-heavy mix for lighter vehicles and Defender, a metal-heavy mix used for heavier vehicles. Aegis offered designers the best AvRHA per kilogram, but the system was very inefficient with space, as dead space was one of the major means the system used in order to keep price and weight down. Defender, however, offered much better space efficiency and overall protection, as it was designed to protect against the modern battlefield. The question that had perplexed designers for years were how to combine the multilayered and thick-skinned Defender scheme with the lightweight Aegis scheme. Designers found their answer the emergent Juumanistran biosteel industry. Biosteel offered a lightweight, high-tensile strength composite that could be replace the wholesale use of ballistics titanium, depleted uranium, and tungsten and return them to their previously intended roles as specialized materials used to stop specific threats.

The JBT-31 utilizes an armor scheme dubbed Aegis III. The system constitutes of alternating layers and weaves of steel, biosteel, heavier reinforced or boronated carbon composites, ballistics titanium, tungsten, depleted uranium, and dead space to generate substantially greater protection over previous armor schemes whilst producing very minor gains in weight and space consumed over the previous JBT-14.

In addition to massive improvements to the tank’s inner armor layer, Aegis III is also the first Juumanistran armor scheme to fully incorporate reactionary armor into its design. JuRA, as it has been dubbed, is a body integrated multilayer system of non-explosive reactionary armor designed to provide improved protection against chemical energy and kinetic energy weapons through the use of thousands of articulated composite plates designed to interest plasma/molten metal streams of chemical energy weapons and induce trajectory changes and deformities within penetrator rods. Additional protection is provided by the Three Speed threat detection and analysis system, which is used to make JuRA “smart” in as it computers the best course of action and angles the JuRA tiles to achieve the maximum of protection based on known data about the incoming threat.

AvRHA:
Front(hull): 1,815mm(1,674mm CE/1,956mm KE)
Front(turret): 1,744mm(1,598mm CE/1,890mm KE)
Sides(hull): 943mm(914mm CE/972mm KE)
Sides(turret): 882mm(841mm CE/923mm KE)
Rear(hull): 556mm(715mm CE/397mm KE)
Rear(turret): 504mm(642mm CE/366mm KE)
Top: 172mm(344mm CE/0mm KE)
Underbelly: 99mm(188mm CE/0mm KE)

Engine and Drive Train

One of the single biggest complaints lodged against the JBT-14 was that its performance in cross-country environments lagged behind those of other tanks in the Juumanistran arsenal. To remedy this, the designers at HDL and Minaduki Arms went to the designers of Khevron Drives, legendary in Juumanistra for their capability to design transmissions that are powerful and efficient. What resulted was, in typical Khevronian fashion, considered miraculous. The new drive train produced 220% more torque than the JBT-14, as well as better treads for improved off-road performance and the addition of a sixth road wheel for improved all-around performance.

The Khevron Drives K4 Bloc supercharged 1300hp rotary diesel-electric engine remains essentially the same as the one found in the JBT-14, with most of changes coming from the hybrid side of the equation. Thanks to quantum leaps in automotive battery technology, the JBT-31 can make it twice as on its internal batteries as the JBT-14 could, with the reworking of the entire transmission granting another 40km more range on essentially the same fuel tanks.

The treads have also received an almost complete makeover, as well. Jasper TreadWell, Khevron Drives's in-house tread design team, introduces to the world the JXT-48-N9, a tread more than 33% wider than the JXT-48-N4 found on the JBT-14 and giving the vehicle significantly better acceleration and handling in cross-country arenas than its predecessor. The N9 also boasts significant strengthening of each tread's internal framework to provide for better survivability when confronted with landmines and road-side bombs.

Maximum Speed, Road: 88km/h
Maximum Speed, Cross-Country: 76km/h
Cruising Speed, Road: 70km/h
Cruising Speed, Cross-Country: 60km/h
Maximum Range: 645km

Subsystems

Computers

Juumanistra has made the cultivation of computer technology important to the success of its armed forces. This has lead to development of the Juumanistran Land Warfare Operations Architecture(JULWOA) and its implementation throughout the whole of the Juumanistran Army. JULWOA is parallel-processing Linux derivative that stresses flexibility and ease-of-use in combat as well as speeding the discrimination of important information to those in the field and between commanders in the field. The JBT-31 boasts eight 3.2GHz processors optimized for the JULWOA OS, to provide adequate load-sharing and redundancy capacity.

Optics

Arguably the most important sensor to the tanker is the Mark I Eyeball. In the past, periscopes were the name of the game in order to see outside. But, in the age of digital photography, the periscope seems hopelessly obsolescent. The JBT-31 employs the Kisaragi Optics Suite II.a, which consists twenty-two 7.2 megapixel digital cameras embedded in various locations throughout the hull and turret in order to view the outside world, with feeds from one or multiple cameras capable of being viewed on one of the numerous LCD screens within vehicle. Each camera boasts full Oracle infrared/thermal/nightvision capability, up to 4x optical zoom for use at the tank commander’s discretion and the ability to retract into the hull should that be required. Traditional periscopes are retained for emergency use and for the sake of redundancy.

Sensors

In addition to the Kisaragi Optics Suite, the JBT-31 boasts several more advanced means of target acquisition. First and foremost is the scaled down JR-441 Little Wonder millimeter radar, embedded in the rear of the turret. The JBT-31 also boasts LiDAR capability, with various emission nodes embedded in the hull and turret. The Hellhound acquisition system handles optical means of target acquisition in addition to RADAR/LiDAR, cycling through idle cameras with sweeps in both IR and thermal imaging modes. The Three Speed threat detection and analysis system is responsible for the crew and vehicle side of the equation, using data acquired through sweeps similar in nature to Hellhound.

Fire Control

FireFox, the overall ballistics architecture, takes into account RADAR/LiDAR/Oracle targeting feeds, as well as laser-ranging, known weather conditions, and relevant GPS coordinates if applicable and synthesizes the necessary firing solution and provides guidance or guidance assistance for all munitions that require it.

Communications

The JBT-31 boasts full encrypt/decrypt capacity, largely a result of Juumanistran encouragement of the flow of information. Similarly, it also boasts full radio and satellite streaming capability and an integrated GPS positioning system. Partial soundproofing of the turret also eases communications through external and internal channels by alleviating most of the noise pollution from the cockpit.

Defenses

JuRA’s first layer is what the JBT-31 utilizes for anti-laser detection, in that the outer layer’s composites were designed in-part to absorb large amounts of light so as to minimize the usefulness of laser rangefinders. RADAR absorbent paint was used in the vehicle’s construction. The designers wanted to minimize the JBT-31's heat signature, but then, upon further consideration, to achieve any kind of meaningful decrease in its thermal image would require gross violations of their design parameters. The Three Speed threat detection and analysis system, as previously discussed, manages the articulation of JuRA’s tiles and the operation of the Hustler anti-artillery focused microwave emissions system fills the role of the furthest line of defense, attempting to induce premature detonations of shells or dud upon impact by frying their fuses and internal circuitry. The front end of the JBT-31 can also mount the Juumanistran standard bull-dozing assembly found on the CE-9 Strongarm combat earthmover, as well as the Big and Little Boi obstacle clearance and combat engineering packages for use in adverse terrain.

Cargo

What makes the JBT-31 truly unique is that it comes from the same school of thought that has kept the Merkava and its various adherents in service in Israel and the rest of the world. The JBT-31 is capable of bringing five fully armed infantrymen into the fray, with easy loading/unloading through a lockable rear cargo door. A sixth man could be squeezed in there if everyone held the breath, but that is not recommended. It can also be used to store additional ammunition or supplies, or if necessary transport the wounded out of harm’s way.

Miscellaneous Stats of Some Import:
Gun Elevation: -11 to 42 degrees
Maximum Fording Depth(Without Preparation): 2.5m
Maximum Fording Depth(With Preparation): 6.1m

Price:
$7,400,000 USD per unit

[OOC: I understand that it's a massive dump and that I got a little...liberal with the application of NS materials science in places. Open to feedback, criticism, requests for explanations, and the like.]

Bump for exposure.

We shall take 2000!

14.8 billion dollars to be payed over 3 NS years (3 days)

Snow Camo Please

It is with great sadness that we must decline Velkrya's order, as both development partners consider Velkrya a "bad risk" and have considerable doubts about its capability to pay for the requested number of units. Whilst the interest in the JBT-31 is greatly appreciated, they suggest purchasing a number more within your means, such as enough to do a one-to-one phase out of the aging M60 Patton from its armed forces.

OOC Very very similar to my BV-17... even down to the number of embedded digital cameras. I see we both have the same attitude towards armoured warfare =)

I'm wondering how you manage to get that muzzel velocity without either using a ETC firing system or a massive magnum charge, especially given the very short barrel.

The accurate range seems a bit long, considering the best tanks can do now is about 3km.

Side and rear armour protection are... high compared to the front. You can't slope the flanks or rear as well as the bow, or afford the weight of the armour, given the relatively low weight of the tank.

[OOC: It's worth noting, first and foremost, that I am not a weapons designer, at least not in the prolific sense that you are, VA. I tackled the problems posed in the foreward with the eyes of a game designer, not a physicist; in a world where buckeyball armor and functional tank-based 120mm+ ETC guns are (semi-)normal, 2.1-2.4km/s on KE projectiles could be written off within the suspension of disbelief to improvements in powder rought by miracles of NS Science, at least from my vantage point. Of course, I would not be adverse to adding the key "subcaliber" noun before APFSDS; that is estalished, by your work IIRC, that ~2.1km/s is easily attainable by a 105mm subcaliber APFSDS round; a 75mm penetrator rod should be able to attain even higher velocities. It's worth noting that I used the phrase "maximum kill range" for a reason; it's not different than certain nations claiming than their tank's guns can kill at a range of 15km. They can, if you score a direct hit, but that assumes your target stays still. The actual effective range is in the 2.25-2.5km; she wasn't built as an open field gun fighter. This problem is further compounded as, given increased muzzle velocity, I always envisioned recoil starting to be a problem. Firing at flank speed whilst on the run over uneven terrain could well even up with the beast flipping over.

With regards to the armor scheme, two things worth noting. Firstly, I used AvRHA instead individual CE and KE RHA precisely because I've got the collective mathematical skills of a room full of chimps banging on calculators. I envisioned most of the actual protection coming from reactive armor, with the main inner being there as a cushion for whatever got through the outer layers; that, I'm fairly sure, runs contrary to modern armor design but, as I said, I'm not really into it as means of mobilizes my massive wells of knowledge of RL systems and physics. Secondly, I saw it an actual scheme, with increased thickness on the flanks and rear where gimmicks like sharp angular sloping don't work. I suppose it doesn't really answer the question, beyond falling back on being within the realm of acceptable suspension of disbelief; The Macabee's Panzerkampfwaggen XI and Crookfur's T-7 Gilgamesh represent some of the most lethal armor values in excess of 3000mm RHA on their fronts at 80 tons; I seem to remember an MBT or IFV that managed to crack 4000mm. Given that the former two pass as "modern" on NS, I consider this well within the lands of acceptable. If you disagree, I'll gladly start pruning the numbers; 100/50/25 is probably the best format, but as said, I'm striving for balance and acceptance, not adherance to the bounds of modern deisgn.

It's worth noting that, as a balancing issue at least for my military for which this was at least in half part motivated by, the ABT-31 costs roughly 1.8 times more per unit than what it's replacing, which given the JBT-14 means greater levels of expensive upkeep and (re)training.

Sorry I'm not a grand defender of what I design with wonderful numbers and element names(though I've been tempted to do a joke design with Cesium-based armor just to see the responses) and links and acronyms. I've had a hard enough time getting my head around enough to sound intelligible, if not correct, on design matters. And, to further complicate matters, I treat the design process as part of the game and thus to a fair degree liberated from real-life and thus NS Science rears its ugly head. Even I think it's a lame justification, and I'm the one using it.

And I think it contrats with the Reiter rather poorly, mainly in that the JBT-14 and JBT-31 constitute the mainstay of Juumanistran tank forces, they're demanded to do anything and everything and so their designs are intended to be flexible, so they suffer from jack-of-all-trades disease and are thus not main battle tanks. Whilst the Reiter may be thinner skinned, the fact is that a 105mm subcaliber ETC sabot will slice through a JBT-31 like swiss cheese. About the only advantage the JBT-31 has is that it was built from the ground up as a joint arms vehicle and that battlefield integration has long been a Juumanistran priority. ]

A final bump for the night.

OOC Hey, no need to get defencive, just trying to be helpful =)

In NS, generally you can't get above 2.2km/s without ETC... and ALL APDS shells are subcaliber. I believe a 120mm gun fires a 40mm rod, generally. And my mistake, I thought you were claiming an effective maximum range of 7km. Having the penetrator travel that far is perfectly reasonable... just don't expect to hit anything with it. While recoil will be a bit of an issue, I imagine it'll still be able to fire while moving. It won't be fun for the crew, but I imagine it could be done.

If you intend the tank to carry infantry, you may wish to rethink the reliance on ERA. While extremely effective against HEAT rounds, it also has a tendency to shred accompanying infantry. It is also only marginally effective against long-rod penetrators, though that is improving, and there wouldn't be any real problem with claimng that your reactive armour chops up APDS rounds rather nicely. The problem is, ERA works best when it approaches the projectile obliquely, which makes it most effective on the turret and bow, where sloping is effective. If you really want all-round armouring, it might be best to either increase the mass, or decrease the armour all around. Currently, it would be a bit hefty. One of the reasons the bow can be so much more heavily armoured is because there is very little surface area, compared to the sides and rear. You'll need about 5-6 times the weight of the bow armour on each side of the tank... I think. Though the fact that you haven't seperated the kinetic and chemical resistance makes it hard to judge.

Yes, there truely are some monsters out there, but I try not to decend to their level =) And if someone sends 80 ton tanks at me... well, I'll weaken my bridges and dig pit traps for them =)

Don't worry about it... I think you've actually done quite a good job here, which is one of the reasons why I posted. And I like the fact that we've got similar attitudes towards armoured warfare... keep the infantry close!

The Reiter (ooh, I'm flattered that you even recognised my tank!=) actually is our main battle tank, and is fielded by all our armoured and mechanized divisions, though we're actually working on a cheaper version because the Reiter, for all it's effectiveness (in my opinion, at least), is a bit complex and heavy. We want a smaller, lighter version... and would seriously consider buying a somewhat stripped down version of the centurion or some of your obsolete tanks... unfortunately, because of part incompatibility, I think we're going to have to go with a domestic tank.

[OOC: Oh, didn't mean to sound bristling or defensive. But my mindset was basically this: "He's asking me technical questions. For which I have no answers. Crap!" And, if that leaked into my tone, it was not intentional.

With regards to the issue of muzzle velocity, would it not be possible to increase muzzle velocity by decreasing the diameter and according mass of the penetrator rod? This, of course, does nothing to increase actual usefulness and probably does just the opposite; just in an exercise in revving up the muzzle velocity. I'm curious as that is an in-character way of dealing with having an above-average muzzle velocity for a powder gun with a short barrel, as Juumanistra's army has an...odd neurosis with odd-caliber weapons(for some bizarre reason, they adore the .55/.60-cal machine gun(not sure which), largely because when I was doing light vehicle write-ups I confused the 14.5mm HMG for the 12.7mm HMG. ^^).

With regards to the ERA/armor scheme, that was merely conceptualization from what my own brain foresaw and thus strictly OOC. I tried to be vague as possible without resorting "yeah, it works because it's just so awesome" type statements in the write-up so that the means of determining "how it works" lies with the player. If they want to work out the science(and the improbability of all this!) bully for them; if they want to believe that the tank is protected by the Juju Spirits of Modern Composites, then that works, too. As it stands now, I've went back and adopted a 100/55/30 armor split and will be juggling the CE/KE break down for a while; thinking, as it stands, of dropping the electric portion entirely from the RA and giving the main body armor fair CE defense capacity, so that the front and sides of the are oriented towrds KE defense with the rear, where crew would load/unload, being geared against CE rounds as that would be the first spot I'd aim for if I were in an urban environment with a shoulder-fired anti-tank rifle/launcher.

The whole "size is betterer" bit on NS can get a bit old, to be sure. The sheer size and firepower of some of what is considered modern is frightening, though it makes me glad I went through the pains of writing up my own engineering gear, as combat engineers for obstacles and light armor to rape the beast's supply lines are, really, what I'd think are the best way to deal with them without building an 80 ton beast myself. Hell, I did work out a 74 ton beast that proved too much of a burden my logistical base and it had been designed more along the lines of Abrams+, a land warfare superiority system, not a super tank.

Parts incompatibility really wouldn't be an issue, I'd think, which is rather shocking given that Juumanistra tends to build everything in it's military weird so as to prevent reverse-engineering and battlefield salvaging. Armored vehicles are designed like that, as well, but can work just as well with things salvaged off of most American and American-derived systems. So, if you've got at least some hardware that can trace itself back to an American system, spare parts won't be as big a problem as you. Even if you don't, the damn thing was built as modular as possible to help support domestic conversions and cater to export customers, so again, its got a wider parts tolerance than you'd think. And the fact that it's been Juumanistran practice to streamline parts usage for ease of maintenance does make our older tanks appealing, as the JBT-14 and its bigger cousin at ~65 tons, the JBT-24 MBT(which is going to be officially phased out of service as soon as I write a dump similar to this) share 85% of the same parts.]

Badda-bump.

OOC: Wow... this is really detailed. Then again, I'm trying to do something similar, though much briefer with my new naval designs.

This might give me ideas for my army storefront (though I will note that I will NOT take anyone's intellectual property.)

[OOC: Heh. One of the funnest parts of doing the write-up was the series of mini-RPs I did with myself to get a handle on the development cycle. It's one of the reasons why I go through the hassle of maintaining quite a few distinct defense contractors with fingers in the Juumanistran land warfare pie(Minaduki Arms, Fujisaki Consortium, Rynar Motor Company, Ijuin Armory, Makihara Munitions, Tachibana Land Systems, Aoyama Defense, Himou Defense Labs -- eight, with Khevron Drives going to be nine when it rolls out the JCV-7). Gives the vehicle a bit of depth, when the producing firm subconracts out production of parts to either subsidiaries or other firms; at least more depth than I think is found in vehicles produced by state arms industries/storefronts.

Sarzonia, it's really not as complex as you'd think. You'll probably find me as a customer with regards to your naval gear, as I'm content to be rather Roman with regards to fleets.

I find it rather ironic that I've spent as many words as I have explaining and fleshing out a vehicle and the thinking behind it that, thus far, has gotten virtually no IC response. Perhaps I should include a sign saying "WILL SELL 2 T3H DICTATA AND FREE N00KS WITH EVERY PURCHASE!!11111!!1".]

OOC:
It is unfortunately part of NS life that stuff with serious effort put in tends to get ignored.
Your details are fantastic but unfortunatly big screeds of text can work agaisnt decent sales as msot people out side of weapons design gang are too lazy to read them (and the tech heads all have thier own versions or are working on them).
Try going for a breif stats summary and a quick "sales pitch" paragraph before moving onto the nitty gritty (a good example of where to work from can be found in the battletech technical readouts).

Oh and cheers for remebering my Gilgamesh however i must point out that it massed a meassly 71tons and only had 1500mm effective RHA on the front, the low weight was due to the fact it was little more than a turreted gun, an engine and two over worked crew hiding in a cramped armoured pod.


I'll let you get on with things.
Once again very nice.

OOC: No problem =)

Decreasing the mass and diameter of the penitrator will indeed improve muzzel velocity, but it will also make the projectile more prone to deformation and shattering. Heavier, thicker projectiles penitrate better... an example would be LOSAT, which is very heavy and has a relatively low velocity. It is a sledgehammer to a APDS stilleto.

The armour's ok now, though usually CE protection is higher than KE... but your fellows may have taken an alternate design route. Also, you may want to check out NERA and NxRA, which are non-explosive reactive armours that are much safer to deal with and almost as effective against HEAT.

Parts incompatability would, unfortunately, be a problem. My heavy armoured vehicle line all share at least 40% of their parts with each other, with congruance between some far higher. This makes logistics way easier, and I'm afraid to bugger it up with some foreign vehicles. But still... very very nice vehicle =)

[OOC: Oh, LOSAT's all-sorts of fun, though I've been mulling over if it's possible to generate a MOSWES system that'll generate relatively high velocities on a relatively large penetrator. The KEM and CKEM have got the gears a tunin', though I'm not entirely sure where it'll end. Have considered just mass-producing rocket-powered penetrators like the LOSAT and making MOSWES mounts for them for when I get in particularly pissy anti-armor moods. Tri-cells on each side of the turret...yeah, space starts becoming an issue, but it's still an interesting idea, being able to put six of those things on a target.

I'll take a look into NxRA and NERA, though it might be a while before they see incorporation into a design. It's taken me months of active resistence before I finally broke down and gave into the new wave of modular supplemental weapons. No telling how long it'll take me to come to appreciate voodoo non-explosive reactive armor. ;)

A shame domestic logistics prevents you from acquiring a few, but I know the feeling, as I do believe we've been here before. At any rate, I'd suggest picking up a few for OPFOR training, but given that there's been no international demand, it's not like they'd simulate something that your troops would ever see in combat.

Strathdonia, heh, it's been a long while since I dealt with the Gilgamesh. All I remember is that it had a 155mm ETC main gun and that it achieved an ungodly number were exported. I know what you mean about long text dumps, which is why I think most of my stuff tends to go unnoticed. But I'll keep plugging and, hopefully, get some resposnes sooner or later. I'll work on that stat dump. Needs to be done, anyway.]

[OOC: Well, since this probably isn't going to get any attention, might as well do some brainstorming to disguise a bump. Would it not theoretically be possible to fuse the concept of rocket-powered heavy penetrators with much small powder-powered tank rounds? A rocket-assisted tank round could deliver much larger payloads(I'd think upwards into the 80mm ballpark) than convention APFSDS rounds at velocities exceeding those of the LOSAT KEM(~1.5km/s, if my math is right). The concept of using rocket-assisted artillery is sound and has been in use for over decade with 155mm shells and, whilst tricky, it should be possible to devise a rocket assembly small enough to replace the existing fin assembly in most APFSDS designs and with the power to propel a penetrator rod of greater diameter than 40mm downrage 2-3km for a terminal velocity in the ballpark of muzzle velocities for contemporary powder guns(~1.8-2.2km/s). If, allowing for the same kind of investment as to make ETC guns viable, rocket-assisted terminal velocities of 2.5-2.8km/s are not out of the question as far as feasibility goes. I think.

Just wanted to bounce it off the couple of readers who've shown an interest in this sort of thing to see if it's either a) remotely possible or b) been done and I've missed the memo on it.]

Maximum Speed(on-road/off-road): 90kph/75mph

?

It makes 1300 hp as well.

A bit too fast.

[OOC: It's worth noting maximum speed is a rather tricky thing. Several wheeled fighting vehicles on NS have top speeds of excess of 100km/h, but can only attain such speeds on well-kept roads and only for a short time. The same applies here; the fastest Juumanistra has managed to clock the ABT-31 at on a straight stretch of road has been 88km/h; rounded off for the stat block whose sole purpose was to generate interest so to encourage scrolling down. The maximum sustained speed has been somewhere in the ballpark of 75km/h, with 66 km/h off-road. Cross-country top speeds, of course, are based entirely on the assumption that one is in good terrain.

I won't deny she's a bit of gazelle, but her size is also an issue. She's ten tons under the median MBT weight and twenty under the emerging heavy tank designation. It should be faster than some of what's out there; it's certainly not as if it's capable of cross-country speeds in excess of 100km/h or anything totally egrigious.]

ooc: reasonable enough then.

OOC: LOSTAT is a couple of meters long... not gun fireable

Rocket propelled SABOT... If I were doing it, I'd put the rocket assembly on the sabot, not the penetrator, and that would let you increase the range of the weapion. Unfortunately, velocity wouldn't increase, I don't think, and the limitations of tank rounds isn't so much the range as the accuracy. It takes a shell from an abrams 2 seconds to reach a target 3km away. In NS, range might effectively be 5km with the higher velocity, giving the target only two seconds manouvering time from firing to impact.

[OOC: Thoughts are appreciated, VA. With regards to the LOSATs, it's worth noting that I was referring to hanging them off the sides of the tank and using box/tube launchers on the modular weapons hardpoints, not gun-firing them. If you're referring to the concept of marrying heavy penetrators with tank rounds, yeah, I understand actually trying to fire a LOSAT out of a tank gun is impossible. If I recall correctly, isn't the penetrator itself about the size of a normal 120mm gun's breech? The fact that it weights almost 200 pounds also doesn't make it viable for firing from a tank gun, even if you could manage to squeeze it into the breech.

Your point is well taken, but I think we're on different wavelengths. At this point, I'm just bouncing ideas around to try and at least close the power gap a bit between ETC guns and their powder cousins in that, as has been increasingly the case with stuff on NS, systems have been designed to defend against ETC guns, which makes powder guns increasingly irrelevant. I'm envisioning what is essentially an unguided missile with a 60mm or 75mm penetrator that uses the tank's cannon as a substitute first-stage booster and then uses a rocket to provide downrange killing power. Assuming that it could accelerate up to 1.8-2.2km/s, it would have substantially more killing power within 3km than a conventional SABOT round; even if velocities comprable to SABOT rounds can't be achieved, provided relatively high velocities can be attained, it should still impact with kinetic energy comprable to a SABOT round with the improved resistence to deflection and deformation brought on by a larger rod.

I think.

The major difficultires in such a round, I would think, would stem from increased complexity and cost, as well finding the proper balance between powder-based and rocket-based acceleration. Just an idea, but it's something I think that's worth mulling over a bit more.]

OOC-

Very, very nice tank. I especially love the rotary engine... That's an excellent idea for a tank, mounds and mounds of torque and horsepower out of a smaller package than what you would get with a conventional piston diesel, especially if you have dynamic turbocharging or twin scroll turbocharging. And since its diesel, you don't get the problems which face modern gasoline rotary engines (burning oil), since the diesel is the lubrication and fuel (I assume). How many rotors does it have? Four? Five? Six? More?


However, they're not good with fuel economy and consume a lot more fuel due to the shape and size of the combustion chamber and the low compression ratio... That is, of course, unless you modified it with a lean burn system (such as a system which Mazda developed).


Anyways, yes, I must congratulate you, very nice tank indeed, very nice.

OOC:

Ah. I'm generally not in favour of mounting LOSAT on tanks, on the basis that LOSAT and the main gun do exactly the same job. LOSAT is a tank destroyer weapon, not a tank weapon.

Hmm... I really don't think you can get the KE out of a gun launched rocket. SInce the missile would need to be the same size as a standard round... I just don't think it's big enough.

There are ways around the ETC problem. For one, KE weapons become ineffective at about 2.5-2.6km/s, they start acting a bit like HEAT rounds, apparently. And you can get close to that simply by using a magnium powder charge....

[OOC: My knowledge of engines and moving parts is even worse than my knowledge of the existing bounds on weapons design. I went with the rotary engine because I was given to understand that it can provide you with the performance of a piston-based engine whilst cutting the weight and size in half and, since there is only one moving part, simplying the whole process of engine maintenance exponentially. I'd envision a five rotor system, with engine efficiency bolstered by both a lean-burn system and the hybrid nature of the engine. But, as said previously, I barely know how to change my oil, let alone design an entire non-mainstream power plant.

And VA, I've heard much of these magnum charges; I think I get the basic idea, in which an undersized shell is seated atop the powder charge for a conventional round. Or am I missing something? Any links to readings on the subject would be most appreciated or an explanation should I have the concept wrong.]

Another bump whilst I go look for food.

[OOC: A magnum charge is simply a larger charge than that of a conventional round. Either by means of hotloading (adding more powder to the same case length) which is not really a military action as it can be dangerous as the case and chamber can only take a certain amount of pressure before bursting. The other method is extending the case which is sort of the planned hotloading which has the same effect without the dangers of adding more pressure without more case strength. The final method is 'knecking down' which is where you use the case from a larger round (say 125mm case firing a 120 or 105mm round) which means the case is more robust but dosent offer any more advantages other than possibly haveing larger muzzle flash due to excess unspent propellant exiting the barrel. But all these methods are essentially worthless in a short barreled gun as the longer the barrel, the longer the propellant gas can accelerate the round (to a point.)

As for sales; I wouldnt worry about it. Get the design to a point that you have a use for it or are proud of it then stick by your guns... if they dont buy it , it simply means any advantages of the system has are now mostly yours. Sales do not define the quality of a product, and they certianly dont make them the most effective. In fact highly sold tanks of dubious armament simple cancel themselves out as the chance of the vehicle engageing itself is relatively high.

Rotary engines are WONDERFUL things.. and my plans for the original cougar called for me to use a similar (known as a flexible vein turbine) but im still goign through the process of reseach on the engine so I decided to use it in my next design.

Well theres a little helpful rant that I meant to post earlier but the forums prevented me from doing so. ^_^]

OOC: Quite, I use necked down shells with slow burning propellent and relatively long barrels (60 calibers). Unfortunately, I'm no help when it comes to propulsion... I simply uise a hybrid deisel electric turbine =)

[OOC: So, in essence, my understanding of magnum shells was correct. But, as Mekugi pointed out, they're more or less wasted on a short-barreled gun like that found on the JBT-31. Which begs the question, what are the merits of the short-barreled gun? I would think it would be trading downrange killing power for decreased profie and greater ease of use when in restricted terrain. Am I fundamentally wrong in that assumption? I'd say the tradeoff is an acceptable one for this vehicle, as it was designed to operate in any and all environments, meaning that the old conventional wisdom about longer barrels being better gets chucked in the trash can, given that they make it harder to operate in an urban environment.

So that means that, in order to handle open-field threats, something has to be done to work around the limitations of the short barrel. One, as has already been discussed, has been devising a round that gets more of its stopping power from an external source, like a rocket, and not the powder of round so as to make the barrel size largely irrelevent. Another would be to simply relegate the main gun to dealing with targets within 2km and using ATGMs for further ranges and develop operational doctrine around that. A third way that I've been bouncing around has been the development of a system of hydraulic or electrical barrel extenders, capable of extending or retracting a barrel extension capable of adjusting barrel length between a long, open-field length of 60 calibers and a shorter, lower profile length of 44-48 calibers. Major problem, I would think, is added weight to the barrel which would play havoc with gun balance. Or, alternately, development of a barrel extension that can be crew installed and caliberated in under ten minutes. I think that the concept of a barrel extender, be it automated or modular, would probably be the best solution, as it alleviates existing open-field problems and makes the use of more exotic magnum rounds as has been suggested by VA without having to fall back on the crutch of NS Science. Similarly, it also does not mandate the development of a somewhat contentious hybrid round, though I'm still going to look into it, as it's piqued my interest and, let's be honest, at least it's as bad as the scramjets people are mounting on their tank rounds. This, at the very least, could be feasible, though it probably won't go anywhere, but that's half the fun of this is, isn't it?

Oooh. Gotta love using my babbling to pose more questions AND bump. Gogo me.]

OOC: The major problem is that the tank is ill conceived for urban operation. In an urban 3 dimensional enviroment it is FAR too easy to outflank the behemouth in a constricted enviroment. Likewise a second or third story window would allow even the most inept rebel to put a a RPG-2/7/16/etc directly into the weakened top of the turret or bustle with usually lethal consequences... likewise you certianly wont be fighting other tanks in the urban enviroment (very few commanders will send a Main battle tank into an urban enviroment, unless its covered to the brim in slat armor, a dozer blade and other things to enhance the survivability in such close quarters combat.

In a sense a MBT is a land battleship (not quite, but bare with the analogy for a moment) its main gun is designed for destroying an equally powerful foe (and anything less powerful) with very few shots and at range so as to strike with impunity. It was not designed for close range combat other wise it would be closer to an IFV with an automatic cannon (multiple or otherwise) to lay down suppressive foire in an urban enviroment. A tank just dosent have the slew rate to engage multiple rocketeers popping out from windows in a random fashion.

Likewise an APFSDS round is not a good round for attacking urban targets... perfect holes dont take out enough material for any practical purpose, and most IFV's can be more cheaply, and easily dealt with by man pad anti-armor missiles. Urban Enviroment + Tank= potential death trap; Infantry are just more mobile, and effective in an urban enviroment.

As for extending the barrel... will just slapping on an external extension will just allow the high pressure gas to zoom past the round unless you use a enxtendable baffle (as in the same comcept as a silencer which temporarliy captures and compresses the atmosphere infront of the round) inorder to gain a 'freebore effect' boost but since thats simply an end baffle the gain would be minimal maybe 1-5% increase in velocity... at absolute best...

The only other way to get a decent velocity from a shorter barrel is to go all out with a Enhanced Freebore Pnuematic Effect Cannon... but the DPRM is the only country with any kind of research background into the field, and Im not about to just give up that research.

OOC: I'd disagree with the statement that tanks shouldn't be used in urban enviroments. Tanks are one of the most powerful peices of military equipment around, if they can't be used, they ought to be changed, or the tactics ought to be changed. For example, close infantry support and active defence systeme, pluss putting an thermobaric shell into the upper story window of any building you approach, can make tanks rather effective in urban situations. Despite their vulnerabilities, the ability to move a massive armoured artillery peice with mounted machineguns that can also act like a bulldozer is really useful.

Advantages of short barrels: cheaper, lighter, less strain on turret, faster training speed, greater elevation.

[OOC: They are being changed to suit this role, but its a slow process as unlike NS the usual development isnt actually implemented until the end of the vehicles service life... so the number of new MBT's each year and even each decade are rather slim...

For the record I never stated they were useless, just that they are in a comprimising position. Infantry can outmanuver, out flank, and are more flexible than a rolling steel box. Now its a given that tanks are heavily armored, and they do have the ability to carry quite a bit of armament but not all tranks are equipped with thermobaric rounds. Likewise resupplying a tank to change its primary armament from APFSDS to HEAT, Thermobaric, and Canister rounds is a logisitical nightmare. To add all of them at the start is going to make it a jack of all trades with limited abilities in all of those roles.

Putting a tank caliber thermobaric round into every window or building you pass will eliminate to possibility of forward infantry support (the best method or use of tanks in urban enviroments as the most vulnerable positions will already be covered.) and be highly expensive.

Its doable, but its expensive, and lower velocity high elevation things like 120 mm gun/mortars are the best urban tank armamant with the best cost to effect ratio.

Personally Im all for keeping the infantry close (hell I wouldnt be useing a primarily motorized/mechanized force if I didnt, but in all honesty I dont think the risk of puttigna vehicle thats about the same width as the road its traveling on with almost no traversable rotation to begin with is the best choice... it opens up what chould be a costly and humiliating problem.

500 dollars worth of explosives in an IED to take out a 6-9 million dollar vehicle is one thing I would not want to explain to an oversight commitee...

APC's/IFV's/MICV's are all cheaper alternatives that with armor advancements are getting stronger and more capable every day, likewise even light tanks have a place in urban enviroments, that again can provide short range fire support, but what has to be remebered is the MBT's need Line of sight to make any kind of effect and in an urban enviroment thats a rare oppurtunity.

OOC: Mekugi, you are correct on the points about the merits of the MBT, but the fundamental problem is that this isn't an MBT. I've invoked the ABT designation precisely because it was never built as an MBT and had a different set of operational goals as such. One of the big ones is to provide heavy armor support in restricted terrain, which includes urban areas. Whilst Juumanistran commanders have really optimized ABT strategy for suburban combat, they're confident enough in their vehicles and doctrine that they're generally willing to take on the risks of full urban warfare. Also, from what I've heard, the 1st Armored Calvary of the US Army has been actively pushing for a retooling of American urban warfare doctrine in light of experiences in Iraq, with most of the focus on reevaluating the need for heavy armor in urban environments, in the direction of rating heavy armor as both important and necessary.

I understand that SABOTs are rather pathetic in urban environs and hence why all discussion of them has been in the context of dealing with the system's relatively weak performance in open environs that are considerable to be tank-friendly. Sorry if I've been confusing in that regard, but since this is a sort of brainstorming and learning thread for me, I'd hope that my rambling could be excused.

If the barrel were designed to mount a crew installed external extender and ensure that the extender properly sealed so as to create a seamless barrel with a length 60 calibers, would it not be possible then for the gun to achieve the velocities of a 60 caliber weapon? I understand that it may not be particularly feasible, but I'm just curious if the idea is plausible, as we do differ just a bit on what are our standards on the influence and extent of RL materials science and engineering in our designs.

VA, thanks for the clarification on short barrels. Helps keep the ol' wheels-a-turnin' in the old noggin.

OOC: Well that does clear up a few things then. Im still not a fan of putting heavy vehicles in an urban enviroment, but that is up to your doctrine and certianly not anything I can argue with (as its varies so heavily from one nation to another.)

As for the barrel extension, Im not sure... in theory yes, in practice.. *shrug* dunno. I dont really have any example to base it off of. But certian rounds are optimised for certian barrel lengths, and a round optimised for a 50 caliber barrel will have a different characterisitics than one for a 60 caliber barrel in MOA, muzzle drop, recoil etc. the FCS will ahve to be programmed to compensate for this difference and youd most likely have to stock both types of rounds.

Bump for additional comments/insights on the vehicle and topics discussed in the thread discussed thus far.

Did some retooling of the armor scheme, after spending a bit of time checking into NERA/NxRA, for any and all who are interested.