Thursday, July 10, 2014

Modularity Versus Weapon Modules

Today’s post involves a simple conceptual clarification concerning the difference between modularity and weapon modules.  Too often, the two terms are used interchangeably when, in fact, they are completely separate concepts.

ComNavOps has gone on record numerous times about the fallacy of modularity (see, "Payloads Over Platforms" or "The Myth of Modularity").  However, a friend reminded ComNavOps about the concept of weapon modules.  In this context, perhaps a better word than “module” is “pit”.  A weapon pit is a standardized and designated space for a single weapon system that is built into the design of a ship at the outset.  During the course of the ship’s lifetime the weapons that fit that pit can be changed as weapons are upgraded or as weapon requirements change.  The pit, then, is limited to weapons.  Of course, there’s no inherent reason why a pit couldn’t be devoted to some other function – a sensor pit, for example.

The modular pit is typified by the Spruance class which was designed with pits that could be upgraded throughout the life of the class.  The MEKO family is another example.

ComNavOps is fully supportive of the modular pit concept although there is nothing that inherently requires such an approach.  While the ability to swap out what’s in the pit is an attractive capability on paper, the reality is that ships very rarely do so.  In fact, off the top of my head, I can’t recall an instance of any warship from any nation actually doing so.  There probably is an example somewhere but the frequency of occurrence is clearly very low.  In the USN, at least, the combination of early retirements and diversion of funding to new construction effectively precludes pit level upgrades.  Thus, pits are pointless.  On the other hand, they cost little to include in the design and have no significant impact on design, hence, my support or, at least, lack of objection.

In contrast, modularity, as the term is used now, refers to the ability to completely change the function of the carrying platform by changing the module.  The LCS is the obvious example of this in the USN.  This topic has been thoroughly covered so I won’t rehash it.

As I said, just a simple exercise in clarification of terminology. 


  1. Speaking of the modularity of combat systems ..... for those of you who have been following the progress of my concept for a notional Capital Seaframe Warship, the latest update to the concept is now available, dated 15 April 2014. The latest illustrations are here:

    The five illustrations are:

    CSW21-U06-I02 Rev A: Design Comments for CSW-21 Flights I, II, and III

    CSW21-U06-I03 Rev A: Bow and Stern Profile Views of CSW-21 Flights I, II, and III

    CSW21-U06-I04 Rev A: Flights I-A and I-B Design Comparison Chart

    CSW21-U06-I05 Rev A: Flights II-A, II-B, & II-C Design Comparison Chart

    CSW21-U06-I06 Rev A: Flights III-A & III-B-C Design Comparison Chart

    Compared with last year's version of Concept CSW-21, the ship flight designators and the ship names have been realigned to fit within a three-flight, seven hull scheme as follows:

    Flight I: 780-feet; 35,000 tons:
    -- Flight I-A: CSW-12, USS Lakota Nation (nuclear)
    -- Flight I-B: CSW-13, USS Navajo Nation (nuclear)

    Flight II: 880 feet; 45,000 tons:
    -- Flight II-A: CSW-22, USS Seneca Nation (conventional)
    -- Flight II-B: CSW-23, USS Iroquois Nation (nuclear)
    -- Flight II-C: CSW-24, USS Cherokee Nation (nuclear)

    Flight III: 1200 feet; 100,000 tons:
    -- Flight III-A: CSW-32, USS Comanche Nation (conventional)
    -- Flight III-B: CSW-33, USS Yakama Nation (nuclear)

    Once again for the record, and saying what has been said previously in years past, the goal of Concept CSW-21 is to become a catalyst in spawning further informed debate over future trends in warfighting doctrine, in weapons technology, and in the methods and means we employ for acquiring large expensive combat systems.

    My next major effort related to Concept CSW-21 will be to author a paper to be entitled “The Capital Seaframe Warship – An Exercise in Risk Management.” With any luck, I’ll get it done by the end of summer. (Summer 2014, that is.)

  2. What about StanFlex?

    Benefits and drawbacks

    Unused modules can be stored in controlled conditions, reducing the need for preventative maintenance.
    Ships do not need to be taken out of service when equipment requires maintenance, and vice versa.
    New weapons and systems can be installed on the vessels by fitting them to a module, instead of refitting the entire ship.[1]
    When a ship or class is removed from service, the modules can be reused by other vessels. Similarly, as they do not have to be built into the ship, modular weapons and systems do not have to be factored into the purchase cost of a new vessel: in 2006, a proposed 6,000-ton frigate design for the KDM was predicted to cost DKK 1.6 billion per ship, while similar projects in other European nations were slated to cost between DKK 2.6 billion and DKK 6.3 billion.
    The multi-role ships are slightly less efficient than a dedicated ship in a particular role, but the ability to be quickly reequipped for other roles more than makes up for this. (taken from wiki)

    Also Thales iMast

    I would use these technologies combined with modular combat system software to drive down the cost and time taken to produce ships and upgrade them.

    Maybe a LCS concept could been produced a lot cheaper. Speedboat hull design not to your liking? Produce another hull!

    Might not be appropriate for your top-of-the-range war fighting vessels, but there are a lot of ships that this technology could be used on.

    1. Dave, check the June archive and read the post, "The Myth of Modularity".

    2. I have done. My point stands.

      The Danish navy have kept costs of new vessels down by using 'gun pits' as you term it.

      I suggest using these gun pits with i Masts and a modular combat system to remove a lot of the guessing and complexity associated with new ship construction.

      Simply put, taking the Danish model and expanding the scope to include the ships mast and combat system.

      I do not suggest swapping out modules for different missions.

  3. Poignant topic right now. The new type 26 Frigate will have a “Flex Deck” and I’m watching carefully.
    I don’t think you can reroll a ship in this manner. Not without massively over designing at the outset.
    ASW need a quiet hull form, Littoral need shallow draft and Armour. AAW need a high superstructure and amazing radar. Some features are simply going to be mutually exclusive.
    It becomes an expensive academic exercise in compromise just to prove you can.
    But I do think you can enhance an already multirole vessel to take on a more serious level of that duty.
    Embarking containerised living quarters for additional marines and a medium helicopter + chinook maybe.
    Or 3 11 meter RHibs extra to your usual compliment.
    Containerising control systems for 3 fixed wing and 1 rotary wing UAV for shore bombardment or ASuW as a targeting complement to your existing naval gun and Anti-Ship capabilities.
    The same in terms of underwater unmanned vessels for allowing SOME Mine Warfare capability enhancing your current mine countermeasure ships in the landing phase. If required.
    Suddenly swapping your ASuW helicopter of 2 ASW helicopters or even a Apache. Enhancing your roll.
    You do have to design for this broadly. Wide passageways for Assault troops, weapons handling for Air Assets. But I THINK do able.
    Ill let you know in 2020.

  4. I'm pro pits for reasons I'd expect you to approve of, combat, and serviceability

    If your in a fight, and some of your ships are damaged, the more thats swappable and the faster it can be swapped, the faster you can get some ships back in to action.
    If ship A takes a direct hit to its bridge, server room and engine room, its a write off, but, if its guns, radar, missile batteries are all hot swappable, they can be salvaged quickly and used to return ships that have suffered other damage to the fight.

    Serviceability is a trickier issue.
    Without pits, if a system fails, the ship either deploys short, or doesnt deploy. If you can pop out the broken system and replace it in a few hours, thats a huge bonus, but it relies on having a supply of spare systems.

    1. TrT, as I said, I have no objections to weapon pits though I see little benefit to them. You do, however, bring up an interesting point about the repairability of a pit item. Of course, as you mention, that requires a ready supply of replacement items. It's one thing to have a shelf full of spare valves or pumps and another to have a warehouse full of spare 5" gun modules, complete radar assemblies, VLS modules, etc. That adds significant cost to the overall operating costs of the ship(s). Still, it might be worth it in the event of sustained combat. Interesting.

      Regarding servicability, I assume you mean routine, peacetime service issues such as mechanical failure and whatnot. In order to make that work, of course, you'd need a supply of spare pit items, as mentioned above, and they'd have to be on hand. That means you'd have to have spares at every homeport the navy uses. The US has dozens of home ports both in the continental US and abroad. The cost to maintain spare 5" guns, radars, VLS modules, etc. in dozens of locations would be somewhere between significant and prohibitive. Again, interesting but someone would need to carefully calculate the costs versus the penalties for a delayed deployment. Also, I think you may be underestimating the time required for swapping an item. I suspect the time is on the order of days not hours from initiation of request to casting off from the repair facility. Simply pulling such an item out of storage would be a major effort. A forklift doesn't just scoop up a complete 5" gun and feed mechanism and run it down to the dock in 10 minutes! Any of those kinds of pit items are giant, immensely heavy items that require specialized machinery to transport and a great deal of care and planning. Still, interesting.

  5. Not sure where you got the idea that the Spruance class had "pits" but it is completely wrong. The ship was built with reserve displacement, but construction was just like every other ship of it's era. For instance,
    - to add CIWS, the empty spaces reserved for it were ran with chill water, elecricity, etc. Everything was fabricated on the ship.
    - To add Harpoon, same thing. There was nothing but a big flat space. Run all new cables, install entirely new combat systems, etc.
    - MK23 TAS? Same thing.
    - VLS launcher? Tear out the ASROC Launcher, remove bulkheads and decks completely and replace with newly fabricated ones. Totally rewire, replumb, and install entirely new equipment. Lots of existing equipment got relocated as well. Every console in CIC was changed.
    The same was true with the SLQ-32 installs, SQR-19 tail installs, the SQQ-89 ASW suite installs, LAMPS MKIII, and every other upgrade the ships went through in there life.

    No Pits, Not modular. Simply weight allowance for growth.

    1. USNVO, you might want to read Electronic Greyhounds which describes the entire history of the design, procurement, and construction of the class and discusses the modularity and the weapons, such as the VLS, that were anticipated to be added. Wiki makes mention of it without, of course, going into any detail.

    2. I served aboard the class and went through several major upgrades including SQQ-89/VLS. Also, we studied the class in my Naval Architecture design class and discussed it with NAVSEA guys who actually worked on the design. Sorry, they are not modular, at least in the sense that a LCS is Modular. The VLS is a good example. The ASROC launcher was removed, equipment was relocated, an entirely new combat system was installed for the Tomahawk including new radios (which required a total re-arrangement of Radio Central and an entirely new space to be fabricated under the launcher including revised access), and entirely new structure was fabricated and installed. In fact, they had to be very careful to reinforce the hull when the ASROC launcher was removed until the new structure was installed. HArdly plug and play. Sorry, that is not "modular", it is pretty much what they did for the FRAM upgrades (or every other upgrade). The ships were built in modules that were welded together (in and of itself nothing new, so were Liberty and Victory ships), and they had greater than normal weight margins, but that is a whole different thing. Sorry, no pits. Not now, not ever.


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