Tuesday, August 12, 2014

Warship "Survivability"



LCS-Inspired Frigate/Corvette Variants (Lockheed Martin)

     Much of the recent discussion of the current Littoral Combatant Ship (LCS) program and the proposed new frigate FF(G)X involves the “survivability” of both classes. Numerous senior civilian and uniformed officials have called for the FF(G)X to be “more survivable” than the current LCS. Casual observers may not know how much information goes into determining this feature of a warship design. Before the Second World War and for some time after, “survivability” was primarily concerned with how many “hits” of a certain size projectile a warship could sustain and still be mission capable. In the postwar era, the concept of survivability changed based on a new ethos in surface combatant design, the advent of nuclear weapons, and advances in detection, communication, weapons, and countermeasure technologies. In fact, a warship’s active and passive defenses against attack from aircraft, cruise missiles and underwater weapons have effectively replaced armor and other elements of physical resistance to damage, making a warship’s “survivability” more akin to a combat aircraft than past combatants.

      The current Navy "survivability" instruction promulgated in 2012 is relatively effective in measuring this new concept of “survivability”, but other so-called X factors can play significant roles. The geography of a theater of combat and the weather there can change the perception of a warship’s relative “survivability. Today’s reasonably “survivable” surface combatant can equally be tomorrow’s “iron coffin” if it sustains damage in a remote location or in a worsening sea state. Before moving forward with a design for a “survivable” successor to LCS, senior civilian and uniformed officers should specifically determine exactly what that concept means both for present classes of surface combatant, the projected FF(G)X and those designs that follow. The November 2012 instruction is a step in the right direction, but more must be done to accurately measure the survivability of current combatants. A first step would be upgrading the current Ship Self Defense Test Ship (currently the ex USS Paul F. Foster) to one of the current or former CG-47 class cruisers and conducting realistic weapon testing against its active and passive defensive systems. They are the heart of real warship survivability and ought to be rigorously evaluated against actual weapons.

     The present (November 2012) Navy instruction on warship survivability makes a significant change from its predecessor in that:

The previous version of this instruction, dated 23 September 1988, established the policy that “Survivability shall be considered a fundamental design requirement of no less significance than other inherent ship characteristics.” This basic premise has not changed although survivability is now considered in terms of capabilities vice characteristics.”

 Survival “capabilities” are divided into the categories of susceptibility, vulnerability and recoverability. While the physical structure of ships is still part of the survivability “triangle”, the ship’s capability to resist attack occupies a much larger part of its overall combat rating. This revision is a welcome change. Over the course of the Cold War and especially the last 20 years, weapons have grown more accurate and potentially lethal. A surface combatant’s survivability now rests more on active and passive systems to avoid or resist attack than physical structure or armor. This demand is reflected in the susceptibility component. The vulnerability and recoverability components still emphasize the ability of a ship to survive initial effects of attack, but the trend toward more powerful antiship weapons and more electronic rather than armor-laden warships makes avoiding attack the primary method of survival and continued mission accomplishment in a wartime setting.

HMS Sheffield
USS Stark
     Other factors that affect survivability are often omitted by experts. The geography and weather conditions of a naval battle can significantly impact survivability. The Oliver Hazard Perry class frigates are often cited by LCS opponents as more “survivable” as evidenced by recoverability of the USS Stark and USS Samuel B. Roberts after they sustained missile and mine damage. Both crews performed heroically in saving their respective ships, but the relatively calm waters of the Persian Gulf, and proximity to friendly bases significantly aided in the retrieval of both ships. Compare this with the experience of the British destroyer HMS Sheffield lost during the 1982 Falklands War. The ship’s firemain system was wrecked beyond immediate repair at sea as a result of battle damage, but remained upright and stable for 5 days until the weather deteriorated. The ship took on a severe list while under tow to South Georgia and sank soon after the weather worsened. Sheffield might have survived had she sustained the same damage in the Persian Gulf rather than the South Atlantic.

Ex-Japanese battleship Tosa

Ex USS Washington
     Tests conducted on incomplete modern battleships such as the ex-USS Washington (BB 45) and the ex-IJN Tosa in the 1920’s gave U.S. and Japanese naval leaders a good idea of the survivability of their capital ships. It is no longer useful however to merely fire weapons into dead hulks as a method of determining a warship’s ability to survive attack. That procedure was effective when a warship’s ability to resist attack was only resident in its physical construction and armor (if any). New methods must be used to assess a warship's active and passive defense capabilities. One example would involve replacing the present Ship Self Defense Test Ship (SSDTD) ex-USS Paul F. Foster with one of the retiring/refitting Ticonderoga class cruisers. The Defense Department Office of Test and Evaluation recommended the Navy build a new unmanned test ship in late 2013, but a retiring Ticonderoga would be a more accurate test platform. AEGIS cruisers  were designed to defeat saturation cruise missile attacks on carrier battle groups. Put an unmanned, fully armed AEGIS cruiser to the test. Take it to a deserted stretch of ocean and fire increasing numbers of antiship cruise missiles at the target until its defenses are saturated and overcome. Up to now this question has been one of dueling mathematical formulas. Salvo equations and estimates of single shot probability of kill (SSPK) go only so far in determining “survivability”. An accurate measurement of combat endurance would either build confidence in current U.S. warship performance or force significant change depending on what results were obtained in the test. This hypothetical test would be extremely expensive, dangerous, and violate a number of U.S. environmental statutes, but what is the price in determining the real “survivability” of a modern warship?  The overall goal remains deterring conflict if possible rather than actually going to war.  As several British admirals and American politicians have said over the course of the 20th century, “battleships are less expensive than battles.”
Ex-USS Paul F. Foster (SSDTS)

     Survivability is a loaded term with many possible definitions given the large numbers of potential variables used to determine this vital warship capability. Those seeking to use survivability as term of discussion should be careful in its employment. Furthermore, the U.S. Navy should be given the funds and legal latitude necessary to conduct the live fire testing needed to adequately measure this feature. While expensive and time-consuming, such testing is necessary in measuring the survival of equally expensive modern surface combatants. 

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