Acoustic Showdown for the SSNs

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Arleigh Burke Essay Contest—Second Honorable Mention

Acoustic Showdown for

the SSNs

By Lieutenant P. Kevin Peppe, U. S. Navy

The U. S. submarine force no longer holds any sig­nificant acoustic advantage over a growing number _t of frontline Soviet nuclear-powered attack subma- ^ltles (SSNs). Further, the funding necessary to regain any ₍,^ast advantage is simply not available. These are realities C_Q^{at (}he United States must come to grips with today, be­_e^re tomorrow’s war finds us fighting with yesterday’s ^tt'Pment and tactics.

to

he sagebrush has given way to sealife, the ^■shooters to Mk-48s, but like the old ^^est’s showdowns, future SSN fights— governed by acoustic parity—may come °^wn to quick draws at close range.

Acoustic advantage, like nuclear superiority, is not easy ₄ quantify. It involves complex measures of broadband- j/^{1 s}pectral-radiated noise levels, the ability to process i ^e^^e signals (at machine and human levels), and increas- one’s ability to exploit the sonar environment, he future gains in all these areas are almost a certainty, _c^e 'oirnutable laws of physics will eventually lead to a ^°ndition where it is impossible to distinguish a target _p§nal f_{rom t}h_{e na}mral background noise of the ocean ⁿ^ro_nment.

While we have not yet reached this limit, we face an- _ei ^{Cr s}°rt of physical barrier. As target-radiated noise lev- tJ* decrease, dependence on that end of the acoustic spec­. ^11,11 least affected by natural propagation losses ^Cfeases. This very low frequency (acoustic) [VLF(A)]

regime, while suffering least from losses incurred during travel from target to sensor, unfortunately requires ex­tremely long-range sonars to yield directional information. Thus, while submarine sensors are capable of detecting these VLF(A) signals at moderate to long ranges, they yield few clues as to the target’s location. This disconcert­ing situation exists until higher frequency signals become available. Herein lies the crux of the acoustic dilemma. These higher frequency signals may not be available until either the target is inside minimum effective weapons’ range or the Soviet submarine has first counter-detected own ship. In fact, as both U. S. and Soviet quieting efforts have led to decreased detection ranges, the issue of acous­tic advantage generally becomes academic.

For example, with an expected detection range of 20,000 yards, a 10% acoustic advantage translates into a 2,000-yard standoff capability. Compare this manageable situation with one where initial detection ranges are re­duced to inside 2,000 yards. This same acoustic advantage now yields a mere 200-yard standoff. Given the uncertain­ties associated with the sonar environment, it becomes a toss-up as to which sub gains the critical initial detection.

The conditions that have led to this state of affairs are many and varied, ranging from better Soviet submarine housekeeping practices to the legal acquisition of critical Western technologies to espionage. While the cause of acoustic parity is not the issue, the fine line that separates acoustic advantage from acoustic parity is worth thought­ful delineation.

Present acoustic realities require that the submarine force critically appraise not only its tactical methods, but also its attitudes regarding Soviet SSNs. While some fac­ets of the military can be accused of portraying the Soviets as ten feet tall and next to invincible, the submarine force

probably could be found guilty of underestimating its So­viet counterpart. It has for so long been a race between the U. S. Corvettes and Soviet Edsels that operational superi­ority has, until recently, been considered axiomatic. As this superiority is called into question, so too must the organizational perceptions it has helped to create.

It is an understatement to say that the members of to­day’s submarine force are very self-assured regarding their ability to successfully engage the enemy. Far from detri­mental, World War II submarine commanders would prob­ably attest that such cockiness is absolutely necessary for success. Yet, the foundation of this attitude deserves atten­tion. The basis of our perceived superiority must be bom of confidence in our own abilities, not in the questionable hopes of an enemy’s inabilities.

Few familiar with SSN operations would find fault in the readiness level of the force. The ships are training, day in and day out, under conditions that we expect to find in wartime. Those anticipated wartime conditions, however, must be questioned. If the percentage of relatively long- range, controlled attacks is expected to be small, it would seem such exercise scenarios should be infrequent. W are not. If coordinated dual SSN operations are required^tl' affect a favorable exchange ratio, the force should be pr^ai ticing with such conditions daily, not just paying lip sd vice to the difficulties such operations entail.

The SSN has been, and will undoubtably continue ^1,1 be, a principal offensive arm of the striking fleet. Acousd parity will not alter this. However, the manner in whU the Navy employs this weapon system requires mud thought. Consider the principal mission of U. S. SSN^s offensive antisubmarine warfare (ASW). The tactics cur­rently employed in ASW are really one-on-one, SSN versus-SSN tactics, where the implicit assumption is tW¹ the United States will control the engagement and, whC ready, fire the first shot. Thus the problem becomes one^(l! gaining a favorable firing aspect, making weapons read}¹' and, anticipating counterfire, making ready to evade Acoustic parity is forcing tacticians to rethink this sce­nario. The submarine force is now beginning to turn d- attention more toward the melee or close-in engagement-'' the rules of which are completely different. Here, at di^s'

tances often inside minimum weapons’ range, detection and counterdetection are made almost instantaneously-^ longer does an SSN have the luxury of refining its i^,r control solution or “polishing the cannonball.’’ No long is it a simple matter of when to shoot and how to evad • Perhaps a lesson can be learned in the Navy’s o backyard from those whose lives hinge daily on close^ in battle performance—namely, the fleet’s F-14 a F/A-18 aviators. When they talk about checking their si or about their disdain for flying solo missions, su

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partners had better listen. Acoustic parity and Soviet •^0rce levels demand that, at worst, an engagement result ^{ln a} one-for-one exchange. While SSN consort operations ^Cannot guarantee even this, it could go a long way toward Sizing that end.

The problems of working two or more SSNs together ^ar.^{e w}ell known. These problems are inevitably the result inflicting requirements: to remain covert while at the time, communicating required information between ^r'endly platforms. Until now, that problem has been ^^rgely neglected because of the perceived ability of a • S- SSN to overwhelm its adversary in the SSN-versus- N scenario. It is time to address this thorny issue of dual , N command, control, and communication (C³) and to ^e^elop a working solution.

further, acoustic parity does not appear to be a problem ^at readily lends itself to passive tracking and engage- ^ent techniques. Given a close encounter, U. S. SSNs _Qj.^Ust be able to rapidly switch from passive to active mode operation, to gain a position abaft the target’s beam, ^ere the target can neither effectively search nor engage,

$U h° ^nia'^nta'ⁿ that position until the target is neutralized, tact' ^c*^ose~*ⁿ active engagements require both aggressive are '^{CS an<}^ ^exP^ert shiphandlers—and here rapid advances d_a Possible. The submarine force is gifted with an abun- _at)^^Ce °f expert tacticians, capable of quickly developing Th ^lrtlP'^ementing the necessary operational guidelines. _tQ(j^{C s}bipdriving expertise is resident, by the very nature of Co ^ ^S 0P^erati°^nat requirements, in every submarine _ne^^manding officer. The need, then, is to subject this operating environment to careful analysis, generate the required guidance, and begin to develop fleet-wide tactical operating experience.

A simple reality of acoustic parity is this: U. S subs are going to get jumped by Soviet submarines, and proba­bly more often than the force cares to admit. Of necessity, the target ship will immediately assume a defensive pos­ture. There are two keys to handling this situation effec­tively. First, the submarine must successfully evade the incoming weapons. This is purely defensive. Second, the submarine should rapidly switch to the aggressive, offen­sive operations discussed previously. Only in this way can the submarine force ensure the exchange ratios necessary to defeat a numerically superior opponent.

The ability of U. S. submarines to adequately defend themselves and quickly regain the offensive initiative must be improved. Several areas require attention:

• Countermeasures: The history of acoustic countermea­sures is like that of their electromagnetic counterparts. A device is developed to be applied in a specific threat envi­ronment. Soon after entering the fleet, the threat changes in response to the countermeasure. A new countermeasure program gets under way, and the cycle continues. This is not an unbreakable chain. Instead, the submarine force could leam from the rest of the Navy and develop a close- in point-defense weapon system.

The development of a hard-kill countermeasure will serve two immediate purposes: First, it will slow this cat- and-mouse game of countermeasure/counter-countermea- sure; second, and perhaps more importantly, an effective hard-kill system will allow the SSN commanding officer to quickly transition into an effective offensive posture. This is not to say that the commander will devote less attention to the incoming fire. In a successful acoustic countermeasure deployment, the chances are high that the decoyed weapon will shift from a search mode to a termi­nal homing mode. Whether you are on the sending or re­ceiving end of a sub-on-sub exercise torpedo attack, termi­nal homing is terminal homing, and without the benefit of sight it is at times nearly impossible to decide on which target the torpedo is homing. The luxury of assuming that own ship is out of danger is simply not available. The result is that evasive actions take lots of time.

Hard-kill countermeasures should change that. Either the incoming torpedoes are destroyed or they are not. The commander, basing his reaction on this straightforward indicator, will more rapidly be able to train his sights on the target at hand. This rapid reengagement is the key to a successful outcome.

To acquire a hard-kill capability will be expensive. It will require substantial funding and a concerted research and development effort. While this is at odds with current fiscal burdens, it is a realizable goal. The question is whether the Navy is willing to sacrifice a unit of force level for the expected gains such a system will bring about in SSN-versus-SSN exchange ratios. It is a difficult deci­sion, both tactically and politically. While additional plat­forms remain attractive, the quantitative gains possible through this and other upgrades favor vertical cuts.

• Burst Acceleration: The ability to evade an incoming torpedo is heavily dependent upon the submarine’s ability

to rapidly accelerate to maximum speed. While powered by the most sophisticated and reliable nuclear propulsion plants in the world, the submarine force’s ability to quickly “get up on the step” needs to be improved. A variety of methods, most notably polymer boundary layer injection, have been proposed. Tomorrow’s engagements require that this process be moved out of the labs and into the boats.

► Reengagement: Generally speaking, today’s SSN tac­tics will not result in a rapid switch from a defensive to an offensive posture. Such a transition is directly affected by countermeasure employment, burst acceleration capabil­ity, and fleet tactics. While some measures currently taken during torpedo evasion may appear offensive, all are, in fact, defensive. This is a logical modus-operandi given the premise that a majority of engagements will occur under conditions that are controlled by the engaging submarine. Thus, for those rare encounters when the submarine is placed on the defensive, simple survival is adequate to ensure favorable long-term exchange rates. When that premise is found wanting, as it is under conditions of acoustic parity, such purely defensive posturing becomes unacceptable. Submarine force tactics must provide rapid and active reacquisition, track, and destruction of the shooter. Good words, but ones that must be translated into action through aggressive tactics, required to maintain the upper hand.

Beyond the expected changes acoustic parity will bring to the SSN-versus-SSN tactical arena is the impact it will have on the U. S. Maritime Strategy. To begin with, the stand-alone SSN is no longer the ultimate ASW platform. Constraints limiting the physical size of on-board detec­tors have resulted in effective acoustic sweep widths smaller than that required for efficient search in most open-ocean areas. While submarine systems are being developed to close the gap, the advent of very large aper­ture arrays, deployed and operated by surface ships, has ushered in a new era in ASW search.

The ramifications of this are many. Perhaps most di­rectly, the SSN’s role in carrier battle group (CVBG) di­rect support needs to be reexamined. While required to fulfill many necessary tasks in the CVBG direct-support role, it is perhaps asking too much to expect the SSNs to effectively sanitize their assigned sectors. If this is a task beyond the capability of the SSN as currently equipped, then a suitable substitute must be found, one which is not limited by a similar physical constraint. This asset, a sort of subsurface AWACS (airborne warning and control sys­tem), has as its beginnings the SQR-19 sonar system. If the additional capabilities of the new ocean surveillance ships (T-AGOSs) are taken into account and the C³ capa­bilities of the Ticonderoga (CG-47)-class cruiser are folded in, the off-the-shelf ASW capability required of such a surface platform is in existence today. This frees the SSN for the CVBG direct-support task to which it is best suited: namely localization, track, and if necessary, attack.

Another vital aspect of the Maritime Strategy is the SSN’s role north of the Greenland-Iceland-United King­dom (G-I-UK) Gap in the early stages of conflict. If the

submarine force’s mission is to sweep the Norwegian S of the submarine threat prior to CVBG operations, SSNs are going to need some help. Discounting moo sonar sensor assets as early targets during a hot war, CVBG is dependent upon surface and air ASW supp° The following problems become immediately ap]

• Unfavorable weather might preclude any type of se" platform from operating except for submarines
• Non-CVBG surface or airborne assets will be forced deal with attacks by Soviet naval aircraft
• Air assets will become less and less effective in a se" role as target source level decreases In other words, the conditions that led to acoustic parity the SSN-versus-SSN arena have likewise affected airbo acoustic capability. How then can CVBGs sail into tb contested area and survive?

In peacetime, U. S. prepositioning of moored and oth ASW search assets should reflect a fairly accurate asse' ment of Soviet Northern Fleet submarine dispositio Suppose, for clarity of argument, that only two pre" dispositions are available to the Soviet force command In the first case all Soviet SSNs would he either in nnft

locally deployed to the Barents operating areas. This cO¹¹ dition, referred to as a compact disposition, would coh^e spond to a non-alerted initiation of hostilities. This cof¹ pact disposition, coupled with the geographical constrain¹ of the region, should make a predeployed, high-densi¹' U. S. nuclear attack submarine barrier an effective thr®*¹ to Soviet SSNs.

Given a compact prewar disposition then, the U- ^ fleet commander should consider an increase in forwa^f“ deployed SSNs. The SSN screen should ensure that CVBGs can immediately move into the Norwegian S^ei' allowing rapid forward support of NATO’s North^¹' Flank. The numbers of U. S. SSNs required to effective^' contain a Soviet SSN breakout would be high because ⁰ the SSNs’ limited acoustic sweep width. Only the g^e° graphical constraints of the area make such a screen poss' ble. However, being possible and practical are not nece⁵' sarily the same thing. The key to effective offensive ope^f3 tions would be an upgraded SSN C³ capability.

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