Heavy Cavalry Redux

“Drive me closer! I want to hit them with my sword!”

no-one with a tank, ever

This is a recreation/reformulation/retcon of the original description of the Empire’s heavy cavalry legions, in light of both criticism received – and assistance to resolve it – and rethinking of my own. It should be considered as a replacement for the original post here, et. seq.

Let us proceed.

Making up the remaining one of every sixteen legions (i.e., one per three light cavalry or heavy infantry, and one per nine light infantry), we have the heavy cavalry. Direct-fire death on very large treads, which is to say, main battle tanks. The biggest of all the big sticks. Putting the “brute” into “brute force”.

For additional flexibility, the majority of Imperial MBTs are built off a common base platform, with a selection of swappable modules to provide specific functionality for specific cases. (Unlike many modular vehicle systems in this ‘verse, however, these aren’t hot-swappable; the need to remove and replace and integrate large and complex chunks of armor plate, etc., when doing it means that this requires some pretty major machine-shop type facilities. It’s not something you can do in the field, and indeed something only seen at the most well-developed remote operating bases.) Due to these functionality differences, MBTs are usually classified by the module.

So first we’ll talk about the capabilities of the base platform, and then we’ll talk about some of the more commonly seen modules:

Base Platform

The base platform of the Imperial MBT is a low-slung vehicle with all-around glacis design, designed to minimize its target profile and give it a low center of gravity. In dimensions, it is approximately 12 m (39 ft) long, 4 m (13 ft) wide, and 3 m (10 ft) high; its total mass (varying, of course, by module), however, is of the order of 60 short tons, due to the extensive use of lightweight composites.

8 m of the length and 3.5 m of the width at the front is the module socket; height of modules varies, but none take it much above the basic 3 m height. At the rear of the platform, an externally-opening compartment can be used to hold resupply, infantry needing transport, or a “hot soup” fuel pod to increase vehicle endurance.


The armament of the base platform (effectively the secondary weapons systems common to all tank classes) is fitted in four altazimuth ball mounts, located on either side of the vehicle, towards the front and rear.

These mounts’ field of fire extends 180 degrees vertically, and approximately 160 degrees horizontally at zero vertical, i.e., limited only by the occlusion of that side’s other mount. In effect, they maintain full coverage to the side, front, and rear of the tank, with only a small gap in coverage to the front for the rear mounts, and to the rear for the front mounts.

The front mounts include coaxial ortillery target designators and heavy (72 mm) mass drivers/micromissile launchers; the rear mounts only include medium (36 mm) mass drivers.

(While the latter do spend much of their time firing forward and to the flank, their special purpose in being mounted where they are is to give you something to pop the drone lining up to shoot you in the ass with so you don’t have to stop engaging your main target while you do it. In their battlefield environment, micro-AKVs are cheap and plentiful, so this happens a lot. If you had to slew the main gun around every time, you’d be taking your eye off the ball way too much – even if you could get it to reliably track something that small and fast-moving.)

See also Point Defense, below.


The armor of Imperial MBTs is relatively standard for Imperial armored units; there’s just a lot of it. The core structural frame is honeycomb-patterned diamondoid composite, covered with multiple slabs of interlinked refractory cerametal (i.e., a ceramic-metal composite formulated for both great physical strength and resistance to heat), electrical and thermal superconductor meshes, more cerametal, reactive-armor sections, and an outer anti-energetic ablative coating to sprayed on top of it all. Additional side plating shields the rollagons. A nanopaste-based self-healing system runs through channels in the armor, keeping damage patched up in the field.

The survivability specifications on all this armor is that the vehicle should be able to survive a near-miss with a tactical-range nuclear weapon or equivalent orbital kinetic strike.

Command and Control

An Imperial MBT nominally crews three: semi-specialized commander, driver, and gunner positions; in practice, this is rendered a mite fuzzy inasmuch as they’re both ably assisted by the vehicle’s internal synnoetic (i.e., designed to function integrated with another sophont mind) AI, and linked to each other by internal conflux hardware (i.e., functioning as a loose, mesh-topology temporary group mind for maximal efficiency, enabling coordination and multitasking by splitting off semi-autonomous agents).

Primary control is routed through the AI and direct neural links – the vehicle seats are virtuality chairs, connecting to the crew’s implanted laser-ports – but auxiliary/backup manual controls are also available.

Core sensors and communications include all the standard options: radio and whisker laser communications, access to the OTP-encrypted tactical mesh, threat identification systems, teamware and C3I systems integration, thermal imaging, remote sensor access, and all-around local sensors including pulsed-usage radar and lidar, T-ray high frequency snoopers, ground-penetrating radar, target-painter detection – and, of course, plain old electronic visual and sound transmission, since the interior of the MBT is fully sealed and includes no direct visual paths.

The MBT also includes a battle computer capable of functioning as a major node in the tactical mesh, and a full ECM suite.


As with all other units of the Imperial Legions, the heavy cavalry too has its drone accompaniments, with each MBT having a pair of WMH-12 Skyorca drones attached to it for close air support, along with a pair of heavy ground drones matching its own tactical function.

Internal Environment

To the delight of those legionaries who like a little comfort in their soldiering, the internal spaces of an Imperial MBT are a comfortable – albeit confined – shirt-sleeve environment. (Climate control, leather seats, the works…)

This is partially because given the expense of building one of these anyway, throwing in a few civilized comforts is barely a blip on the budget, and partially because – well, anything that successfully penetrates the armor tends to leave the crew as a hundred-yard-long red/blue/silver-white/etc. smear on the ground behind the exit hole anyway, so there’s no point in having them sit around in full combat armor. A padded jacket and helmet are sufficient to prevent accidents from concussion and rough terrain.

The interior is also a fully sealed and controlled life support environment for NBCN protection and exotic atmosphere/vacuum use. This also renders all tanks amphibious tanks by default: once you’ve covered all the various atmospheric compositions and pressures you might need to operate in and discarded thereby air-breathing engines and other systems, you’ve built a vehicle that can shrug off submergence, too.You could drive a modern Imperial MBT from continent to continent across the ocean floor, given a case of rat bars and a good reason to try it.

Point Defense

The MBT is equipped, as all else is, with a military-grade kinetic barrier system.

For active point defense, the base platform is equipped with a mix of mini-autocannons (in altazimuth ball mounts) and laser emitters, laid out to ensure all-around coverage, and capable of independently and automatically targeting all incoming fire and close-in soft units, subject to target identification and prioritization routines set by the crew.


It seems a little inappropriate to say that the MBT is also powered by a micro-fission “hot soup” reactor, inasmuch as, well, it ain’t that micro. It is “mini”, perhaps, compared to standard-sized fission reactors, but it’s as large as the thorium molten-salt kind gets. The bigger ones all tend to be the safer “pebble-bed” design.

Naturally, this is buffered through a large set of superconducting-loop accumulators to handle immediate power draws and provide backup power in the event that you lose the power reactor – enough to make a fighting withdraw, anyway, although not enough to continue an engagement with.


The Imperial MBT moves on neither wheels nor treads; rather, it sits atop eight semi-squishy rollagons, near-spheres of a “smart fluid” rotated electromagnetically from within the sealed main hull, enabling it to move with equal facility in any direction, at speeds of up to 150 mph on a good, flat roadbed. Note that this is not a drivetrain developed specifically for military purposes: modern civilian ground-cars use similar technology.

The propulsion system also has considerable electromagnetic control over the shape of the rollagons; while they don’t have them normally, if you need spiked wheels or some other shape-variation to cross some tricky terrain, it can provide them on demand; if need be, they can even form “paddle-propellers” for amphibious operation.

A limited vector-control/impeller system permits the tank to apply vertical thrust to itself; this is used primarily downwards on light-gravity worlds to keep ground pressure high enough for the rollagons to be effective, occasionally upwards to reduce ground pressure where the ground is soft, and even more occasionally to lessen the severity of falls, ground collapses, or deliberate drops from low-flying transport aircraft.

(It would theoretically be possible, on light-gravity worlds, to use it to make “skips” over obstacles or other short vertical jumps, but this is generally considered an excellent way to become skeet.)

Stealth and Masquerade

The Imperial MBT, much like the heavy infantry, supports only the most basic chameleonic coating and signature reduction features; the nature of the battlefield environment of the time is such that any heavy unit has a signature (in terms of heat, reactor neutrinos, and the EM pulse accompanying weapons firing) that can’t be baffled worth a damn. As such, designers concentrated on designing a vehicle that could “tank” (sic) incoming fire in the process of executing shock and awesome.

It should however be noted that this does not preclude the use of external decoys, or the use of signature modification systems to confuse terminal guidance of incoming weapons, or indeed to masquerade as something else — but these systems have to work with the platform’s high signature, not try to conceal it.

Module: Tactical Assault Tank (HV-10 Basher-class)

As close as it comes to a “standard” MBT design, the HV-10 Basher-class module loadout is similar to the V40 Ralihú IFV, scaled up; the Basher-class comes with a turreted super-heavy (144 mm) mass driver, but substitutes a bilateral quadbarrels with limited independent training for the Ralihú’s single coaxial quadbarrel.

(The heavy mass driver is also designed to function as a heavy micromissile launcher, if required, and as such is entirely capable of delivering large-diameter canister shot for anti-infantry work.)

Module: Long-Range Assault Tank (HV-12 Stormfall-class; also HV-12i Longeye-class)

The HV-12 Stormfall-class LRAT module is equipped with a turreted super-heavy (144 mm) mass driver intended to be capable of long-range indirect as well as direct fire, but substitutes the quadbarrels for bilateral “pop-out” missile pods, each capable of doing a simultaneous launch of up to 16 minimissiles, reloadable with a short cycle time from internal magazines. Just perfect for those days when you want to fight in the shade.

By changing the minimissile loadout of the Stormfall, it can also serve as an active air-defense platform.

Rarely seen is the HV-12i Longeye variant, which trades in both super-heavy mass driver and missile pods for a graser installation, suitable for direct fire only but capable of punching out even more heavily protected targets. Also, notably, the Longeye graser is often capable of penetrating the atmosphere and reaching targets in low planetary orbit.

Module: Drone Tank (HVC-14h Thunderbolt-class; also HVC-14l Stinger-class)

A drone tank, in legionary parlance, is the land-based miniature equivalent of an aircraft carrier. The HVC-14h Thunderbolt module contains nanoslurry and miniature drone components, which it uses to construct and deploy ad-hoc micro-AKVs to suit the requirements of the current battlespace, launching them into action as a centrally coordinated wing, for defense, reconnaissance, attack, or other functions.

(Or, to put it another way, it’s a self-propelled field factory that spews out custom drones and minimissiles on demand, simplifying your logistics and multiplying your options.)

The HVC-14l Stinger functions similarly, but substitutes swarm hives for the micro-AKV factory, and is thus able to saturate the local battlespace with microbot/nanobot swarms, be they the standard eyeballs, shrikes, gremlins, or balefire, or more specialized models.

Module: Tactical Arsonier (HV-10a Flammifer-class)

Used for cleaning up or eliminating nanoswarms (highly vulnerable to thermal overloading), area denial, reducing bunkers and dug-outs, and spreading pure terror, the Flammifer-class replaces the heavy mass driver of the Basher-class with a scaled-up nuclear-thermal flamer, while retaining the quadbarrels as-is.

Module: Command Tank (HV-10c Strategos-class)

The Strategos-class is a specialized vehicle for coordinating tank-squadron activities and close air support. The Strategos module doesn’t add any weapons systems; rather, it adds two more crew positions for squadron command, a specialized tactical/logistics C3I AI, and a nodal communications suite and its antennae.

A pair or triplet of Strategoi are usually assigned to a tank squadron made up of other classes for command/control functions.

Module: Pummel (HV-11 Pugnacious-class)

The pummel tank is a highly specialized variant, designed to rip apart buildings and fortifications. It carries sappers in its rear compartment, and is equipped with specialized demolitions equipment up front.

Module: Wrecker (HV-10w Trison-class)

Another highly specialized variant, the HW-10W Trison and other wreckers are logistics units, used to recover wrecked tanks and other heavy equipment off the battlefield for repair or for scrap.


The Flapjack-class cavalry dropship was made specifically for this; apart from that, they mostly drive to wherever they’re needed, because only the biggest transport aircraft can carry them in useful numbers.

Not Yo’ Mama’s Wormholes

Or, the Difficult Worldbuilding Compromises that Result when You Didn’t Design Everything at the Same Time.

It has been (entirely correctly) pointed out over on Google+ that this is not how wormholes, as we understand them today, would work.

(Because they’d work like this.)

This is one of those cases, though, where I end up invoking “firmish SF” – and one in which I’m trying hard to deprecate the term “wormhole”1 to refer to the kind of FTL there just to avoid confusion…

Having done my reading on said-hypothetically possible wormholes, I did my damnedest to use them properly. (Long-term readers of mine may, for example, remember some older references to wormholes as continuously existing Visser-type structures embedded in exotic matter frames, now quietly retconned out of canon – which indeed worked exactly as they should with regard to local conservation; having traversers’ mass and momentum added to the mouth they enter and subtracted from the mouth they exit.)

This would probably have worked a lot better for me if I’d not had an existing background/setting, because while I’ve rewritten a lot of things a lot of times to fit with hard-scientific plausibiity, after wrestling with it for a lengthy period – well, I came to the conclusion that while it offered me some very interesting options for how things would play out, there was pretty much no way I could reconcile it with what I had short of throwing out the setting and writing a new one from scratch. And, well, ouch.

So given the choice between that, badly mangling real science, or constructing some con-science to fit – in just this case, um, space magic? 🙂

1. Suggestions for alternative terminology gratefully accepted, since I really don’t want to keep calling these things wormholes when they don’t behave like wormholes. Especially since, arguably, there’s no reason that wormholes-which-are-wormholes couldn’t also exist there.