Sunday, June 1, 2014

The Myth of Modularity


Payloads over Platforms. 

Ford pickups over Ferraris. 

Certain ideas get repeated so often that eventually discussion of their underlying validity (or lack thereof) gets bypassed and the discussion moves on to implementation.  Diversity is one example.  Despite absolutely no evidence that diversity offers any advantage, the national discussion bypassed the validity of diversity and moved straight into methods for achieving it.  Similarly, modularity has moved beyond discussion of its merits (or lack thereof) and straight into methods for achieving it.

CNO Greenert has been one of the biggest champions of modularity with numerous public statements espousing payloads over platforms but with little discussion of the actual merits.  Are modular payloads really the universal solution to all our tactical, technological, engineering, and budgetary challenges?  Navy leadership would assure that they are.  Are they, though?

Let’s consider a simple example.  We want to win a car race.  How do we do it given that we only have a pickup truck at our disposal?  Well, modularity would suggest we simply put a bigger engine (the module, in this case) in the truck.  Unfortunately, about half way through the first lap our truck would find its engine failing due to an inadequately sized exhaust system, its brakes overheating and failing because they aren’t properly sized for the power of the engine, the acceleration would be incapable of competing with the other true race cars because the gearing isn’t optimized for the engine, its tires would be shredding due to the high speeds, stress, and friction induced heat, and, worst, we’d crash because the steering and suspension couldn’t handle the high speed cornering.  In short, our modular pickup truck would get blown away by the specialized race cars whose every component was exquisitely optimized for racing.

What went wrong?  We had a modular approach and should have won, shouldn’t we?  The problem is that our module, the engine, was not tightly integrated with the rest of the truck (the platform) and to achieve maximum performance, it must be.

Now, if we want our modular truck to simply be as cost efficient as it can, we could add a more fuel efficient engine and we’d see improvement.  That’s an undemanding requirement that could be met by a module change.  Even there, we still wouldn’t achieve as good cost efficiency as a vehicle whose every component was designed for cost efficiency and tightly integrated to function together towards that end.

We see, then, that the weakness of modules is that, by their very definition, they are not tightly integrated with the carrying platform.  Lack of integration means, by definition, that performance must be sub-optimal.  That’s OK if the module’s task is undemanding.  Want to change a plane from a transport role to a cargo role by removing the modular seating?  No problem.  There’s no real penalty for the resulting cargo plane being a bit less efficient than a purpose designed cargo plane. 

However, when we start applying modularity to combat we run into the race car problem.  Asking an LCS to become an ASW platform by loading the ASW module (assuming it worked!) is asking a sub-optimal ASW vessel to go up against a dedicated, optimal submarine totally designed to kill ships.  Sub-optimal versus optimal.  The winner is going to be the submarine. 

In contrast to a generic, modular ASW platform, an optimal ASW platform should have quieting built into every component from the first rivet on up.  Every piece of machinery must be acoustically isolated.  The engines should be selected for acoustic and motive performance in the ASW operational speed range.  The sensors should be tightly integrated into the seaframe so that self-noise interference is absolutely minimized.  The hull, itself, should be sized and shaped to minimize self-noise and maximize maneuverability within the range of tactics that will be used.  That kind of integration and ultimate capability can’t be achieved simply by loading a module onto any old platform and, yet, that’s exactly what the Navy wants to do.  We’re intentionally developing a second tier fleet while our enemies are doing their best to develop optimized, focused, lethal platforms.

Modularity is fine for non-combat applications but has no place in combat.


  1. Good points. I think a valid counter example is the navy use of jdam. Originally intended as a 1000 lb gps guided bomb it has been modular enough to be adapted to 500 and 2000lb and using laser seekers. The Aussies have even expanded it by adding wings. Given that navy is migrating mostly to jdam, especially after jsow cancellation, I think modularity has its place.

    1. kreletor, modularity, as I'm describing it, involves the use of packages (the modules) on a carrying platform (the ship, in this case). It's the payloads and platforms concept wherein the payload can completely change the function of the platform. The JDAM example is more a case of scalability than a payload/platform situation. Still, it's a nice example of an adaptable item. Good comment. Thanks!

  2. The problem with your argument is the existence of Engineers. These interchangeable Mission Modules are not something thrown together by some farmer. Mission Modules they are designed to preform certain functions, while mounted on certain ship types. Yes, their equipment my have some physical shortcoming, such higher weight, difficult maintain, and may cost more than equipment not required to be installed and removed as needed.

    Against these "shortcoming" we have several advantages. missions modules can be upgrade without requiring a ship to be present. While high speed changes between Mission Modules may be out, even the slowest change require far less time than would be require to upgrade a hardwire frigate. Also there will be times when Mission Modules will not only not be required but will hurt the LCSs utility. For such time removing the Mission Modules would be a great advantage.

    1. GLof, let's assume that I know what an engineer is and what they do. Let's further assume that these engineers are the very best the world has to offer and would only build the very best modules possible (so, how do you account for the absolute failure of every LCS module and they continuing problems? but, I digress ...). So, we have the most perfect module possible. The module still isn't integrated with the carrying platform. I assume you read the post carefully. How do you rationalize the payload/platform shortcomings due to lack of integration, when applied to combat (the race car analogy)?

  3. I think modularity probably has its place. After all the VLS is effectively modules, slide in one box fits all containers with differing missiles plugged in and a common interface. We can reequip at sea and all of as sudden our AAW destroyer becomes land attack.
    Very nice invention, brilliantly thought out and well executed.
    But what the author is talking about here is 1 hull totally reequipping ( except for a modest deck gun ) into a whole new kind of “front line” warship. Let’s not mince words it’s the LCS again isn’t it ;)
    Now there are other notable examples such as the absalon class
    Heralded as the great new thing and basically where the idea for the LCS came from maybe. [ I don’t believe its battle tested ] . BUT ! it has a crucial difference. Its basically a reasonable equipped hull, with huge space for extra bolt on’s. A modest frigate, which transforms into Frigate PLUS some. It seems to work. Although by definition compromises have been made to accommodate modules. In basic mode it is about 2000 tonnes bigger than it needs to be.
    And this in fact I think is where we are going, From an engineering point of view, no matter which way you slice it, every combination of LCS will have parts on it that are redundant in this mode, because they are used in the other modes.
    Either weight, space or cost that is not useful in pure MCM capacity.
    The more modules the more of these dunsel’s
    If your on a real budget and cant afford loads of hulls ( sorry Denmark, but its true ) then it’s a great solution.
    BUT your just aren’t getting a 100% efficient ship by definition.
    If you have used the same technology and money in a pure variant IT WOULD HAVE BEEN BETTER.
    The question is how much better and could you afford to make all the variants in the numbers you need for the same price ?

    1. Beno, quite right. The VLS or the MEKO weapon "pits" represent a different and very limited type of modularity. They're modular in the sense that you can put something different into the slot but the choice of what you put in is very limited. You can only put a similar type "thing" in. A VLS can only accept a launched weapon of a certain size. It can be a slightly bigger or smaller weapon or it can be an anti-air weapon versus a land attack weapon but, ultimately, it has to be a missile. You can't drop a RHIB into a VLS to make it a boarding and search module. You can't drop a remote towed sonar into a VLS to make it an ASW module. You get the idea.

      My contention is less about inefficiency in terms of cost and more about inefficiency in terms of combat capability. In combat, you want a platform that is exquisitely optimized for its combat role not a generic carrying platform that can only offer a partial degree of capability. Modular combat platforms will lose to optimized combat platforms. That's the point. Modularity does not work in combat.

      You also make the very good point that countries that cannot afford a large navy may have no choice but to accept the lesser capability of a modular ship. Better to have some capability than none but if they come into conflict with an optimized enemy, they'll lose.

  4. Modular thinking can work if it is done for the right reasons, but modular done right, I can not see being cheap, nor can I see it making up for poor planning.

    In fact I would argue it requires even better planning and higher upfront costs.

    For example I see no reason why you can not build a ship where a gun module cannot accommodate a variety of different options, but if you want the option of installing a 8 inch main gun, it obviously will not work unless the ship is designed with this option in mind. This will bring higher upfront costs and you take the chance you may never utilize the option. The same principle would apply regardless of the type of module you are talking about.

    My point is if you design your modular ship with accommodate the various mission modules you intend to deploy in the beginning, you should be successful.

    Thus the conclusion I come to is this, if you design your mission modules first and then design a ship for them to fit into, I would argue you stand a good chance of success, the reverse I would expect to be problematic. Unfortunately which one happens in practice?


    Does it enable you to equip a ship for a role for which it was not intended, I would argue no.

    1. Mark, excellent comment. You summed it up nicely in your last paragraph. The LCS, if it wanted to be an ASW platform sometimes, should have had ultrasophisticated quieting built in to the ship from the keel up. It didn't. Thus, the ASW module results in an ASW platform that is inherently second rate. The LCS will be a better target than hunter.

      Your comment also implies the dilema of designing the modular capabilities in up front. What if the design characteristics of the anticipated modules are mutually exclusive? Consider the LCS in its ASuW role versus its ASW role. The ASuW role calls for giant and, therefore, loud engines to produce top end speed. The ASW role doesn't need speed and calls for ultra-quiet engines. I suppose you could build two entirely different engine trains side by side by no one could afford that and it would double the size of the ship.

    2. Totally agree, that is exactly what I mean by stressing the importance of planning. Some things are obviously not compatible.

      You could for example design a variety of engines to fit in a common modular block, same for radar's, electronic warfare and so on. So when ship x built as a ASW specialist you select the boxes that work with that role.

      That to me is the advantage here, it allows you to built a variety of specialist ships at a lower cost, by using a common hull design, built in higher volume to save cost.

      It is not about trying to built a one generalist ship that can do everything. If that is what you want, this is the wrong strategy.

      This is in my opinion where they went so wrong with the LCS.


  5. My question here is what counts as 'modular'? I mean, it seems like some weapons the Navy has had in the past were bolt on, self regulating modules that were deemed 'good'.

    I.E. to me the early sea sparrows, and IIRC, SUBROC's, ABL's, and Phalanx were boxes with their own sensors, or an ability to get Data from the ships sensors through a simple line, that were bolted on to older ships to give them new or better capability. To me these are 'modules'.

    We designed a weapons system that worked, and was able to be bolted on to ships. I think its a good idea to keep trying to do stuff like this. It allowed us to have older ship designs all of the sudden carry modern weapons. It wasn't perfect, but we didn't allow perfect to be the enemy of good enough. Especially when we wanted hulls in the water.

    But as you stated, it has a limit.

    ASW platforms need certain things that are required to do their jobs well.
    You can't bolt on Aegis and make a ship an air defense ship.

    I guess to me you have ships that are specialized in one area (Air defense, ASW, etc) but have the easily upgradable stuff there. Don't build the ship stupidly, but go for common connectors and enough excess in power at time of construction to be able to account for future growth.

    I think of a ship kind of like the Hubble Telescope. The Hubble will never be anything else other than a Telescope. And its fixed hardware (lense, mirror, etc.) aren't capable of being removed.

    But over the years they were able to get better performance because they were able to remove old computers and replace them with faster, better ones. They were able to take advantage of advances in image processing with faster computers to make the telescope better. They were able to bolt things on that fixed its initial spherical aberation.

    An Aegis will never be anything but an Aegis, but build it in such a way that it has more power than it needs, has common connectors that are industry standard, and when its initial computer becomes obsolete, buy a new one and plug it in and calibrate it. These new ones might be able to make the system better by being faster and more accurate.

    An old imaginary ASW Frigate might have a powerplant with older, obsolete quieting. Add on something like Prarie/Masker to enhance its ability, and plug in new computers that can take in the data the old Sonar is bringing in and parse it more quickly and more accurately.

    Viola! You've added two new 'modules' that make the ship better.

    This Jacknife ship concept doesn't make much sense to me unless you are forced into it.

  6. Excellent Analogy CNO.
    Obviously the Navy and any kind of procurement operations nowadays calls for extreme capabilities yet they are very reluctant to fund the extra stuff they want. Look at the job market, you want a college grad with years of experience and expect they can do everything from cleaning toilets to being rocket scientist, yet insist on paying them the minimum wage. :)

    I hate the LCS with a passion. We are on the same page here. The LCS has the capability of a patrol craft, or a coast guard cutter, at most. The idea of the mission modules sounds interesting, but as you said, there's only so much you can "modulize", such as a troop transport module, where bunks, A/C, bathrooms.etc are packed into a container and plugged and bolted onto the LCS. That would be a sensible module, with off the shelf components readily available. Or a medical module with operation ward, ICU units, again, such equipment and capability are readily off the shelf. That's the general idea. Obviously how well these would work on the LCS is a question, Transporting only a handful of troops with no heavy equipment going across the Pacific at 40+ knots, I believe a C-17 would definitely do a better job.

    As the ASW and ASuW for the LCS, For a start I don't even see how on earth can they shove a box into the hanger and suddenly give them the capability they so urgently needed. Take AsuW for example, that for the USN is Harpoons + 5" gun. I don't see how those could be fitting on with a "Module", and in a manner of speaking, Shouldn't the Harpoon be a relatively easy fit? Just bolt them on and fire and forget, yet the USN still haven't decided what they should do with the LCS, and yet still let these fighting ships run around with no mission and (Nearly) no weapons!

    ASW requires specialized platforms as you mentioned above. The most obvious would be the shape and size of the blades on the propellers , rudder and hull, Yet the LCS is basically a huge Speedboat, and it doesn't even have a Rudder or Propellers. Water jets are fast but noisy even at lower outputs. It is a complete wonder as to how the LCS will hear anything with their engines running. Same goes towards MCM missions, Any acoustic sea mine would easily take the LCS to the bottom.

  7. Fundamental physics of naval architecture: the ship will have to exhibit satisfactory intact and damaged stability for the MOST DEMANDING COMBINATION of mission modules it is envisioned to carry. The ship will have to be adequately sized, powered and manned to meet this requirement.

    It is likely that the ship would carry less than this total package for the greater part of its service life, therefore it will be oversized, overpowered and carry excess accommodations than is required.

    It will be hard for the Navy o justify this excess lifecycle cost.


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