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In something I'm working on, where surface attack craft (The question says tank but I suppose this could apply to other vehicles) are designed so the same vehicle could be fitted with different weaponry depending on the mission- on the assumption that, for example, missile launchers may be be suited for some operations while an energy or particle cannon (or flame projector, you get the idea) might be preferable for others.

Does this sound like a lot of work for nothing, or does it make some tactical sense?

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I can see how sending in the right kind of weapon is tactically sound, but not why those weapons need to be modular additions to a base vehicle. Perhaps there is some fiscal sense there, what level of tactics are you asking about? – Samuel Feb 23 at 23:18
Modern tanks can shoot several kinds of shells through the main cannon (armour piercing, anti infantry...). – Davidmh Feb 24 at 8:36
Tanks are already modular. Artillery is mounted on tank chassis' for mobility. The turret is often replaced with a different gun. AntiTank guns are mounted without a turret for a lower cost infantry support vehicle. This has been done since WWII – Oldcat Feb 25 at 0:13

While modularity is desirable from certain points of view (for example, the carrier vehicle is the same across many units, so parts and supply is eased), there has to be a careful look at the cost/benefit ratio of what you are doing.

Generally speaking, modularity comes at the price of having extra "structure" on the host vehicle for mounting points, couplers to power and utility services and data connections to sensors, the fire control system or whatever other system the module is hooked into (power, life support, even modular crew pods will need some sort of data system to communicate in and out). Below a certain size, the costs of the extra "structure" will outweigh the benefits of modularity.

There is also an inherent reduction in flexibility to the module itself; it must be designed to fit inside the "structure", so upgrading in mid life to carry larger guns, missiles or torpedoes might be difficult to impossible. Should that happen then the entire fleet of vehicles and modules become obsolete. In order to lessen the chances of that happening, designers must make a conscious effort to leave room for expansion. This is often going to be fought on cost cutting grounds, so there will be a lot of tension during the design and validation phases.

Modularity has come down a lot in both cost and minimum size. Remote Weapons Stations (RWS) can fit on a wide variety of vehicles ranging from jeeps to Infantry Fighting Vehicles and are essentially "drop in" units so long as the vehicle can accommodate the turret ring and has room somewhere inside for the operator. Modular turrets for a wide variety of vehicles also exist. Modularity is also theoretically much easier on ships, due to the great size of the ship and lower structural costs of having modularity, the ultimate example would be to build weapons mounts like VLS missile systems into ISO containers and outfit a battle group of container ships to carry your arsenal (a warship like a frigate or destroyer can supply the targeting information and control the launchers remotely). The Lockheed "Sea Slice" ( and the Littoral Combat Ship are designed around carrying purpose built modules for various war fighting functions, for example. Sea Slice

For a tank, modularity could be a good thing with today's state of the art. The IDF's Merkava and Namer are built using many of the same basic components, and the Russian T-14 Armata is a very modular system, with a wide variety of AFV's scheduled to be built using the platform as the basis (the T-15 IFV is the first, but expect engineering vehicles, air defense systems and other types of AFV to appear in the future). The main downside is that everything in both the Merkava/Namer and T-14 Armata family are scaled around the tank, so there is a certain minimum size and weight associated with these systems. Depending on you strategic situation, this might not even be a bad thing. Merkava Namer

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+1 Good answer. As for tanks: I'd like to notice that the germans made modulary tanks as soon as the late 30s / early 40s. The Panzer IV could hold a variety of guns and even different turrets for Anti-Tank, Anti-Infantry and Anti-Air Combat. – Bounce Feb 24 at 9:09
@Bounce, that's not a true modular tank but rather successive upgrades. First as a tank, and then when larger guns were no longer possible in a proper tank turret it became a tank destroyer. – o.m. Feb 24 at 16:39
@o.m. Well, no, the Chassis of the Pz.IV was used for the JagdPanzer IV, but it was also modular. The standard version of Ausführung H could be mounted with a 7,5cm anti-tank cannon or a 10,5cm anti-Infantrie Howitzer. Also the whole turret could be changed for an AA version (Wirbelwind) or for an bridge-building version (StegPanzer IV) for example. There were also some prototype Configurations for Artillerie that didn't made it in serial production. I think that fits very well in the concept of modular. – Bounce Feb 25 at 7:42

This is a perfectly viable option. It's even being deployed by certain modern militaries. For example, the Georgian army uses a vehicle called the Lazika where the "universal fighting module allows the mounting of different types of armament such as MLRS, SAMs and ATGMs."

Feel free to expand on this idea and make your platform even more versatile.

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Not to mention the US's vehicle the Stryker which now has a minimum of 9 variants from medical vehicle, mortar, remote machine gun, antitank missile, mobile gun, command, infantry carrier, etc. – Jim2B Feb 23 at 23:46

The Stryker is the best extant example in a current military, but it doesn't qualify as a "tank", or barely as "armor". An actual tank will continue to be specialized because of the need for high mobility, high armor, and high firepower. This combination is very difficult to achieve in a modular/flexible design (looking at the inside of a tank shows you that there is no room for extraneous equipment).

In general, almost every weapons platform is going modular, from the DDG-1000 to the F-35 to the Littoral Combat Ship. Most likely, automation (i.e.: drones, autonomous vehicles) will make the majority of near-to-medium future weapons systems highly modular. Even now, the F-22 cannot continue as a credible platform.

Even the replacement for the venerable M1 Abrams was envisioned as a modular platform: the FCS Manned Ground Vehicle.

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I think there are two different concepts to consider:

  • A family of vehicles has different vehicles based on the same chassis. Many spare parts and maintenance skills are interchangeable, but the vehicles are not. You cannot turn a Bradley into an MLRS.
  • A modular vehicle can be modified from one mission to the other. The Boxer can switch different modules on the same vehicle.

For the latter, keep in mind that tanks are usually defined as a direct fire vehicle which is armored to stand up to similar direct fire attacks. That means the armor is concentrated in the front. The armor package on missile carriers pays more attention to indirect fire strikes.

It would be conceivable to put different direct fire weapons onto a modular tank. A railgun today, a laser tomorrow, a particle accelerator the day after that. The problem with that is geometry. The turret has some of the strongest armor on the tank -- do you really want to make the firing ports larger than necessary to accomodate different weapons? And what is the shape of the ammo feed system?

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Most modern weapon systems are modular to some extent for ease of maintenance. Its not just about weapons though.

A modular powerpack means a faulty unit could be swapped out with nothing more than a crane and put the weapon system back in order. With a hybrid/semi hybrid design for a power plant, you might swap out a powerplant with one more suitable for another role.

Having a single, multirole platform also means spares commonality (Your tank killer's transmission broken? Grab spares from your AA platform that's got balky fire control).

That said there's a certain lack of flexibility. Some platforms tend to do ok for purposes they were never designed for. The m113, while designed as your standard can of infantry is a good example of that. That said, it has barely any armour, and wouldn't do as well as say, a MBT.

You could turn a MBT into a APC though which might be a decent idea. Have a standard base design - have the APC as the base model - have large, standard compartments for Motorised infantry, communications or ammunition. Have different turrets for tank, AT missile or SAM pods.Significant commonality in parts, better logistics.

Problems? You can't 'simply' swap out turrets as needed. You will need to retrain your crews, or cross train them. Some roles may be swappable (drivers) others may not.

You'd also not have vehicles perfect for every situation. Need a light tank that will fit into a airplane? Having a MBT wouldn't help. Need something tough? A light tank or a thin shelled APC base would not help.

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