The Navy’s vertical launch system (VLS) has long been the backbone of the Navy’s offensive and defensive missile systems.
The basic VLS module is currently available in two lengths: Strike and Tactical. The smaller Self-Defense module is no longer available since it can’t accommodate the ESSM Block 2. The Strike module is 25 ft (7.6 m) tall and can house all variants of the Standard missile, Tomahawk, and ESSM. The Tactical module is 22 ft (6.7 m) tall and can house ESSM and non-BMD Standard missiles.
The Mk57 VLS is 26 ft tall and can accommodate an 18 in longer missile and about 3 in greater diameter.
Here’s a quick comparison.
|Max Canister Length, ft||21.4||23.6|
We can see then, that the Mk57 is slightly bigger than the Mk41-Strike but not by much.
I really don’t understand the benefit of the Mk57. Consider,
- There is no missile in the naval inventory or in development, that I’m aware of, that can’t fit in the Mk41 but could fit in the Mk57
- The Mk57 is non-standard and creates a new parts, maintenance, and training requirement.
- The Mk57 takes up more deck space and ship’s internal volume – not by a lot but it adds up when we look at a hundred modules or so. In other words we can’t fit as many Mk57 cells as we can Mk41.
I could understand if the Mk57 were significantly bigger and could house, say, short/intermediate range ballistic missiles but, as I said, there is no such naval missile in inventory or development.
One of the rationales put forth to explain the benefit of the Mk57 is the distributed nature of the cells around the periphery of the ship. This is claimed to offer survivability benefits. However, to the best of my knowledge, the Navy has not claimed this benefit and logical analysis does not support the claim. While a hit on a Mk57 equipped ship would not hit a centralized cluster of cells, as could happen with the Mk41, a missile would have a much higher probability of hitting some cells, as opposed to the less likely chance of hitting a Mk41 cluster. The Mk57 is claimed to disperse the explosive impact of an exploding cell outward, away from the ship. Again, this is not a claim the Navy has made, to the best of my knowledge, and seems unlikely to be significantly true. An incoming missile hit would penetrate the Mk57 peripheral cell and continue inward, creating an opening into the ship’s hull for the exploding contents of the cell (its missile and subsequent blast wave) to follow. Yes, some amount of the energy would be directed outward, as with any explosion, but large amounts would be directed inward. The degree of armor protection, if any, between the cell and interior hull is unknown. I have seen no Navy claim that the cells are individually armored.
The Mk41 cell clusters are, supposedly, encased in an armored “box” within the hull to contain explosive effects. Again, the degree of armoring and its effectiveness is unknown.
Thus, the claims of enhanced survivability seem like an after-the-fact justification conjured by observers rather than an actual characteristic claimed by the Navy. Logic suggests that a peripheral VLS system would offer little, if any, survivability benefit. Further, if every peripheral cell is armored, the total weight of armor would, likely, be much greater than the armor surrounding the Mk41 box. A ship would pay a penalty for such a system. Of course, if the armoring were sufficient to greatly mitigate damage, the penalty might well be worth it.
The peripheral nature of the Mk57 is unique to the Zumwalt class due to the tumblehome shape of the hull. Conventional hulls cannot accommodate peripheral cells. They would have to be located some distance inboard due to the length of the cells relative to the outward cant of the hull. So, the peripheral feature is not a general characteristic of the Mk57.
Finally, if the Mk57 offers significant benefits, whatever those may be, why aren’t they being incorporated into the latest Burkes?
I’m at a loss to understand why this VLS module has been put into service.