Much discussion has been caused by the Type 26 model shown at DSEI 2013, as this new model showed just 16 VLS Strike Length cells instead of the 24 shown earlier at Euronaval 2012. Reportedly, the main reason behind the difference is the fact that at Euronaval the model was fitted with the European SYLVER VLS system, while the DSEI model was fitted with the American MK41.
Why the very noticeable difference?
|In this photo by Navy Recognition, the Type 26 model seen at Euronaval 2012: there are 24 SYLVER A70 cells|
The MK41 vertical launch system was conceived in 1976 and first appeared on the cruiser USS Bunker Hill. The vertical launch system, conceived by FMC but produced by Martin-Marietta (now part of Lockheed Martin), was a major upgrade from the MK26 launcher, which employed a twin-arm ramp with an under-deck ammunition depot for 44 missiles. The same space occupied by a MK26 launcher, thanks to the MK41, became a 61-missiles silo, with all missiles constantly ready to be fired, against only 2 ready to fire on the arms of the MK26 ramp.
|Two graphics showing the complex MK26 twin-arm launcher that the MK41 replaced.Missiles were vertically struck down in the two conveyors, and vertically pushed up onto the launcher's two arms.|
The MK41 comes in modules which have 8 missile cells each, arranged in two rows of four aligned on the two sides of a vertical uptake used for venting hot gas. Originally, there was also a module with just 5 missile cells, with the space of the other three occupied by a fold-down crane for at sea reloading, as we’ll see.
Each module carriers its own launch sequencer, motor control panel and gas exhaust system. When a missile is fired, it exhausts downwards through the blowout bottom end of its canister; the hot gas goes down into the MK41’s plenum and then vents upwards through the uptake, which has its own hatch opening between the two rows of cells.
The plenum can withstand 7 launches from each cell, plus a restrained firing with full motor burn from any other cell. A deluge system is installed to provide flooding of missile cells to prevent warhead explosions.
|The uptake hatch between the two rows of four cells is very evident in this image, showing the launch of a Tomahawk. Notice the high pressure, high-temperature gas venting upwards from the hatch.|
Multiple MK41 8-cell modules can be assembled together in a silo: Ticonderoga class cruisers were built with two large silos, each containing seven 8-cell modules plus, originally, a 5-cell plus crane module, giving the ship a total of 122 missile cells.
|What looks like a 5+crane MK41 module is being lowered into the silo, to join three 8-cell modules already in position. Note the density of the installation. A further four 8-cell modules will follow, to form a 61 cell large silo.|
|A 61-cell silo, completed, with a caniser being lowered towards an empty cell. Note the 3-cell wide hatch of the crane, in the second module from the bottom, to the right of the image.|
On the DDG-51 Flight I and II, the MK41 modules were arranged in a silo with 29 cells on the bow (the equivalent of three cells taken up by the crane) and 61 on the stern.
The All-Up Round missiles used in the MK41 come in sealed canisters which are used for storage, transportation, handling and, ultimately, for launch. Once a canister is struck down into a VLS cell, it becomes an integral part of the launcher system. Each canister has a common external envelope to support system launcher module interfaces, while internal mechanical and electrical components are tailored to specific missile shapes and interface requirements. In other words, to each missile, its own canister:
MK13 canisters are for Standard SM-2 series missiles;
MK14 canisters are for Tomahawk
MK15 canisters are for ASROC
MK21 canisters are for SM-3 anti-ballistic missiles
MK22 canisters are for Sea Sparrow
MK25 is the special, quad-pack canister for ESSM
There are successive variants of the canisters. Today, the Tomahawk All-Up-Rounds come in MK14 Mod 2 canisters. Before it came the Mod 1, which had a launch security device for the control of Tomahawk employment, and by the Mod 0, which had a key-operated security device against unwanted launches, as it was meant to carry the now withdrawn nuclear-tipped Tomahawk.
The canister MK21 Mod 3, instead, is a slightly modified MK21 used with the new Standard SM-6 missile.
Canisters have a shell structure is a steel weldment with corrugated steel skins and cast steel end frames. They are fitted with a variety of vital equipment and characteristics, including: adjustable lateral restraint shoes, longitudinal shock isolators, an ablative coated steel baseplate structure, ablative blocks, deluge piping, nitrogen fill piping, cables, a code plug and a Canister Safe and Enable Switch. The Canisters also contain a telemetry antenna and monitoring connection.
The canisters are not simple boxes. They contain precious equipment, and the missile cannot do without its canister.
|Open MK41 cell hatches, showing the empty shafts. Without canisters, the MK41 is little more than a metallic frame.|
|An overview of the MK14 canister, employed by Tomahawk|
|The Tactical Lenght MK15 canister, containing the ASROC missile, and showing the MK18 canister adapter that allows the use of shorter canisters in the Strike Lenght cells|
|Inserting a canister down a MK41 cell|
MK41 comes in different lengths, which determine the size of the canisters that can be installed and, consequently, decide which weapons can be integrated.
The canisters have a square base, with a total diameter of 25 inches. Inner diameter of the space for the missile is around 22 inches. There are three canister sizes:
- 170 inches; for self-defense weapons only (Sea Sparrow, ESSM)
- 228 inches; add SM-2 and ASROC
- 264 inches; add Tomahawk, SM-3
These canisters fit into into different length MK41 launchers, obviously. This value refers, effectively, to the heights of the modules to be installed in the ships.
- Self Defense Launcher is 209 inches
- Tactical launcher is 266 inches
- Strike launcher is 303 inches
The Tactical Length canisters, however, can be and are fitted into Strike Length cells with the aid of the MK18 Canister Adapter, a steel weldment with appropriate dog-down connections that serves as a conduit for rocket motor exhaust vented to the plenum. Fitted to the bottom of the shorter canister, it allows it to fit easily down like it was a strike-length canister.
The deck area of a 8 cell module, instead, remains the same. The short side of the launcher is 81.75 inches, while the long side is 124.63 inches. Depending on their height, empty 8-cell launcher modules weight 26.800 lbs or 29.800 lbs or 32.000 lbs for the Strike Length launcher.
|The old 5-cell plus crane MK41 module. This is no longer produced or employed, as the crane never worked as well as hoped. It remains an impressive bit of kit, though.|
The fold-down crane for at-sea reloading of missile cells was contained under deck in a space equivalent to just 3 missile cells, and elevated outwards during reload operations. The requirement was for the replenishment of 10 VLS cells per hour, even in Sea State 5, with the missile canisters being transferred via RAS (UNREP for the Americans) rigs.
Reloading of missile canisters at sea, however, proved always difficult at best, and the ingenious crane, albeit fascinating, was never capable to deal with the larger and heavier canisters, such as the MK14 containing the Tomahawk. The failure of the VLS replenishment at sea is summarized as follows:
The original development of the MK 41 Vertical Launch System (VLS) for cruisers and destroyers in the late 1970’s included a requirement to replenish ten VLS canisters per hour, day or night in Sea State 5 conditions. The system actually installed consisted of the STREAM rig to transfer the VLS canister to the missile ship sliding padeye; then deck handling the canister to a position where a crane could tilt up the canister over an empty cell and then strike the canister down. The crane was a commercial Swedish folding crane. Three canister cells were combined to make stowage for the crane. An elevator raised or lowered the crane. The at sea VLS Unrep technical evaluation discussed in Miller (1992) identified that the crane did not have the capacity to lift Tomahawk VLS canisters; SM-2 VLS transfer rate was three per hour and the pendulum action of the crane limited Unrep to Sea State 3 conditions. The cranes are now in layup.
Eventually, the ambitions of at sea reloading of MK41 cells were abandoned, and the DDG51 of the Flight IIA were never fitted with the crane, instead getting 32 and 64 cells silos. The cranes were at times used during Desert Storm, to aid the correct placement of missile canisters. Desert Storm, in 1991, provided the US Navy with the first experience of wartime reloading of warships fitted with MK41: the USS John Paul Jones was the first warship to receive a wartime reload of Tomahawk missiles, but did so while pierside in Mina Jebel Ali, in the United Arab Emirates.
The closest thing to an at sea wartime reloading was the transfer of shipborne missiles from support vessels to warships in the lee of Masirah, Oman. The ships were motionless in the protected waters, but not moored to the bottom, as it was felt tactically advantageous to be able to move quickly in case of enemy attack.
Interest in at-sea reloading is not dead, and a solution might come in service in the future, since the impossibility to rearm a major warship without pulling it away from the fight and into enclosed, friendly waters is seen as a major limitation. The logistics of VLS reloading are complex, and require extensive material handling mechanical equipment, time and adequate portside or shipborne facilities. The new Upper Harbor rearming facility built by the Royal Navy at Portsmouth is a good example of structure thought specifically for the replenishment of VLS cells.
|The new, specialized rearming facility built for Royal Navy use, with the two cranes for VLS reloading.|
During war operations abroad, having at hand such a well-equipped facility could be a real problem, as US documents have underlined for decades.
"double-ended" VLS ships such as AEGIS cruisers and destroyers can be rearmed twice as fast if two cranes are available (a frequent bone of contention at stateside weapons stations). With both cranes swinging canisters and enough forklifts and pier-side handlers to keep up with them, a motivated AEGIS crew can completely reload the ship's VLS systems in one (long) day. Note the optimum requirements, though: a pier of sufficient length and with water alongside to accommodate ships up to 563 feet long and 32+ feet in draft; cranes, forklifts, trucks, and/or flatbed rail rolling stock; and contiguous or near-contiguous cargo ports or airfields. Such a facility is precisely the kind of "logistics node" that the JFMCC will be attempting either to defend or seize early in a regional conflict. When in friendly hands, such a facility is a prime TBM target in its own right, as seen at Jubayl, Saudi Arabia, on 16 February 1991, when an Iraqi Scud impacted within yards of an ammunition pier berthing seven ships, a supply barge, and the USS Tarawa.
An at-sea rearming technique and equipment is part of US Navy ambitions to modernize Underway Replenishment (UNREP) technology, effects and methods. The following describes one of the possible approaches:
The concept for replenishing 15 VLS per hour in Sea State 5, shown in Figures 9, 10, 11 and 12 centers around a transportable VLS rearming device that is stowed and maintained on the Combat Logistics Force (CLF) ship. When the combatant ship comes alongside for at-sea rearming or load adjustment, the rearming device is transported from the CLF ship by the new Heavy Unrep rig to the combatant ship sliding padeye along with a team to operate the rearming device. A swing arm at the base of the sliding padeye is used to position the rearming device onto three low profile rails permanently mounted atop the VLS launcher. A hydraulic power unit on the combatant ship powers the swing arm and also the rearming device after it is on the rails.The CLF ship will next transfer a loaded VLS canister to the sliding padeye. The canister will be lowered to the swing arm by the sliding padeye and then be released from the transfer rig. The canister will be swung around and be picked off from the swing arm by the rearming device two clamp rings. The canister will be moved by the rearming device to a position over an empty cell. The cell hatch will open and the rearming device will erect the canister to the vertical. The canister will be lowered by a wire rope hoist into the cell. The rig will be disconnected from the end of the canister, the cell hatch will close and the canister will be connected below decks to the VLS circuits. When the VLS rearming or VLS load adjustment is completed, the rearming device and team will be returned to the CLF ship.
The threat of Anti-Access and Area Denial strategies and the focus on the Pacific should both work as powerful budget and strategy drivers in the next few years to encourage the US Navy to bring work forwards on UNREP improvement. At sea logistics will be more important than ever, and we can expect to see big increases in capability.
It is worth noticing that the Heavy UNREP equipment envisaged and experimented by the US Navy appears to be very similar to the Heavy RAS equipment being experimented by the Royal Navy at HMS Raleigh in anticipation of adoption on the next generation Solid Support Ships. The wide loads being moved, in terms of bulk, and the weight mentioned (12.000 lbs) are roughly the same values indicated for the Rolls Royce H-RAS.
|The H-RAS facility at HMS Raleigh, in one photo from Dave Sheffield. According to the blog NavalMatters, we can expect an article on the H-RAS activities in november's edition of Navy News. The shuttle resembles that seen in the 12.000 pound mode of the Heavy UNREP kit for the US Navy, but no actual heavy load can be seen. Trials are still at an early stage|
A Mk14 Mod 2 Tomahawk canister comes at 6130 pounds. Both the H-RAS and H-UNREP kit would move possibly two canisters per each lift, with a rhythm as high as 25 lifts per hour. While at-sea rearming of Royal Navy VLS ships is not on the cards, the new Solid Support vessels seem set to have the RAS capability to keep the door open for future adoption of adequate kit and methods.
The European SYLVER vertical launch system follows the same principles of the MK41, but has been developed more recently, has never had any built-in at-sea reloading kit, and has made some different choices. Getting details on SYLVER is much more complex than getting adequate information on MK41, and it has taken me quite a while to collect information which is not yet as complete as I’d like.
SYLVER comes in three main sizes, in addition to the very small, self-defense for small ships A35 launcher. The main modules are the A43, A50 and A70. The number refers to the approximate length of the cells, which vary from 4.3 meters to 7 meters, roughly matching the MK41 Self Defense, Tactical and Strike lengths. The A43 launcher has a total height of 5.3 meters; the A70 is 7.6 meters tall.
DCNS, the maker of SYLVER, proudly notes that SYLVER is significantly lighter than MK41. Early claims were of 30 to 40% weight savings thanks to the use of more modern materials and composite, but this seems over-optimistic, as the declared weight of the 8-cell standard modules goes from 8 tons (A43) to 12 tons (A70).
SYLVER has a smaller deck area footprint, of 2.6 meters x 2.3 meters, while vaunting an exhaust duct which, according to DCNS, is 1.5 times larger than that of the MK41. The larger duct is meant to make the system even safer by expelling gas at lower pressure, allowing simultaneous salvo firing even while one missile has an inadverted restrained launch.
The significant difference in width of a 8-cell module (2.6 meters for SYLVER, against 3,17 meters for MK41) explains why the Euronaval 2012 model of the Type 26 had three 8-cell modules fitted abreast, while the DSEI model only had two MK41 modules sitting abreast. The first combination fits in some 7.8 meters, while the same number of MK41 modules arranged in the same way would require 9.51 meters.
The difference, however, comes at a price: the SYLVER’s cells are only 22 inches wide, 3 inches less than the MK41’s. The difference is very significant, as SYLVER of course needs its own canister, and even assuming that these are thinner, the internal diameter available for the actual missile will inexorably be less than 22 inches offered by the MK41 canisters.
Although DCNS shows Tomahawk as a possible payload for the A70 launcher in its brochure, it is entirely right to question whether it would be actually possible to integrate it in the European cells. The Tomahawk missile is around 20.5 to 21 inches in diameter, so the space available to fit it, complete with a proper canister, into a 22 inches cell is truly minimal.
Integration would be a challenging affair for physical reasons, as well as for politic, economic and combat system reasons. A wholly new canister would have to be designed, and the space available to do everything that needs to be done would be minimal.
Apparently, besides, A70 canisters are circular, not square like MK41’s.
|Loading a SYLVER A70 canister on a FREMM frigate of the french navy, in an image by DCNS. The canister is circular, not square, so more similar to Russian and Chinese systems than to the MK41!|
There is also an unanswered question coming to mind when observing the disposition of SYLVER launchers on warships. On each vessel, the 8-cells SYLVER launchers are always in contact at most only by the short side. This can be observed on Type 45, on the Horizon destroyers of Italy and France, on the FREMM frigates and on the Formidable-class frigates of Singapore. The long side of the launcher modules is never in contact: there is always an important space of deck between one launcher and another.
|SYLVER A50 modules on the Type 45: two rows of three modules each, touching by the short side, but well distanced when it comes to the long side.|
|On the italian aircraft carrier, Cavour, in a photo by Chinomar, from the website Mezzi Militari Italiani|
|On Singapore's FORMIDABLE frigates|
|On Charles De Gaulle|
This is not observed in MK41 silos, which show a very high density, with the separate modules in direct contact. One is left to wonder if the separation between modules is a choice made by all customers so far, or an unavoidable necessity.
Perhaps coming from the fact that the canisters themselves are thinner...?
If this is the case, the lower deck-area of SYLVER becomes much less of a truth: basically, fitting more SYLVER modules than MK41 ones, in the same deck area, is only possible so long as the modules are installed abreast, like on Type 26. In a large multi-module silo, or in any case when the long sides should touch, a lot of space ends up wasted, for some reason.
The right choice?
It is not easy to judge which system represents the right choice for the Royal Navy. I’ve already discussed in an earlier article about this complex topic, and much of the uncertainty is due to the fact that it is not clear yet what weaponry the RN hopes to fit into the VLS cells. Of course we can assume the Tomahawk in the short to medium term and the SPEAR Capability 5 (also known as UK-FR Future Cruise and Anti-Ship missile) in the longer term (not before 2030).
For the Tomahawk, its eventual successor (American design) and for other possible weapons (LRASM?), the MK41 would be the most appropriate, if not the only choice.
Going for commonality with the US Navy would be, in my opinion, more advantageous and more wise in a long-term analysis, despite the SPEAR 5 work with France. It is very hard to see how investment in SYLVER and in its weapons by UK and France (and eventually Italy) could ever match the level of support and attention that MK41 will receive from the US, Japan and other export customers. In terms of logistics and future-proofing, MK41 would make greater sense.
It is true that it is hard to see at the moment which American weapons, beyond Tomahawk, could ever be selected for the (british) Type 26. With CAMM covering the air defence role, with Sea Viper on Type 45 in the higher tier, it is hard to see british interest for any of the American SAMs for at least a few decades.
When the UK will eventually acquire an anti-ballistic missile capability (because I believe it is a matter of “when it becomes necessary”, more than a question of “if”), we can expect that the Type 45 will be the platform of choice, so being able to embark SM-3 is also not immediately relevant.
As for LRASM, the missile’s future isn’t even certain yet, and the UK will likely not procure it, unless the SPEAR 5 ambitions collapse.
However, there are logistic, support and future-proofing reasons to go MK41. Being tied to the US Navy is the most promising way to ensure that the weapon system is not without support, evolution paths, and new weapons.
I don’t see many reasons to go with the SYLVER. Certainly not Scalp Navale, which is a less performing, more expensive alternative to Tomahawk that the RN frankly does not need at all.
The main cause of interest is the SPEAR Capability 5 missile, but this is little more than a concept, and the few studies started so far are all aimed at a 2030 entry in service, which might easily slip further to the right. If the currently envisaged timelines are respected, the first Type 26 by then will be approaching the first 10 years of service life. Betting it all on a missile that might or might not come by then, does not seem the right way to go.
The main factor, at this point, is the number of VLS cells. Having 24 instead of 16 is obviously much better and preferable under many points of view. The smaller diameter of the cells, however, which already feels tight today, is a concern for the future.
It would be important to know if the Type 26 design can spare the additional under-deck space which would be needed to replace the banks of CAMM-only cells in the bow silo with an additional MK41 module or two. If these is the possibility to do so, as has been suggested to me (but not confirmed by sufficiently authoritative sources), then my suggestion is to go MK41. CAMM could just be quad-packed into some of the MK41 cells, instead of having its own single-purpose spaces.
Even if such space does not exist, I think adopting MK41 could be, in the end, the best choice, although less evidently so. MK41 promises greater certainties for the future: there’s a much larger and richer customer base investing on it, and it has the physical size advantage. You can be reasonably certain than any missile developed for the 22-inches wide SYLVER cell will fit into the 25-inches MK41, while the opposite simply is not true.
I suspect this is a reason behind MBDA’s decision to offer European missiles for the MK41. Of course, the main reason is the global diffusion of MK41, but I believe it is nonetheless indicative that MBDA has signed an agreement with Lockheed Martin to integrate European missiles in the MK41 cells, starting with the easier system to transfer, the very interesting Sea Ceptor / CAMM. The greater width of the MK41 cell has allowed Lockheed to develop the Extensible Launching System ExLS: a simple, yet ingenious “launcher within the launcher” which can be slid into MK41 cells (or used as a stand-alone system) to accommodate foreign missile systems, with their canisters and launch electronics. When it first appeared, it was associated with plans for quick MK41 integration of smaller weapons and even countermeasures: the NULKA active radar decoy, a quadpack of RAM Block 2 missiles or a pallet of NLOS surface-strike weapons were all shown as possible payloads.
After being demonstrated with NULKA, the ExLS has now come very much back in the spotlight for its instrumental part in allowing MBDA and Lockheed Martin to get to push-through tests with the CAMM missile in a MK41 cell in very short time. After agreeing to collaborate, in May 2013, the two companies have successfully cleared the first launch trials in September: a record for the slow world of defence technology. This success has been just as quickly rewarded by the selection of CAMM in MK41 cells for the upgrade of the ANZAC class frigates of New Zealand.
It is also worth remembering that the US Navy has already invested in a new generation of Vertical Launch System which share the same base principles but comes with longer, wider cells. The MK57 launcher comes in four-cell modules, and is so far only known for being employed by the sole DDG-1000 Zumwalth-class. These three unique ships will have 20 MK57 modules installed, not in dense silos like on Ticonderoga and Burkes, but in peripheral position along the sides of the hull.
The new launcher is fully compatible with existing MK41 weaponry and canisters, but offers cells which are 283 inches long and 28 inches wide, with a maximum mass of 9020 lbs. It is a very noticeable increase in all parameters from the MK41 Strike Length.
It is not yet evident which new weapons will require this big space, nor is it likely that the MK57 will replace the MK41 anytime soon. For now, it is tied to a new class of warships which has been cut down to just three hulls. It will be interesting to see if the MK57 becomes part of the requirement for the proposed Arleigh Burke Flight III, or for whatever ship comes next.
The US Navy’s belief, however, seem to be that larger missiles are likely, and while the MK57 is possibly too far ahead of the current requirements, the SYLVER might soon enough fall behind requirements.