Joe Buff is a novelist with several submarine-related books to his credit. He is a frequent contributor to these pages. His first article in THE SUBMARINE REVIEW was a look at submarine warfare in the foreseeable future using a novelist ‘s method of forecasting from unclassified sources.
Part I of his discussion of modern submarine vulnerability appeared in the July 2003 issue of THE SUBMARINE REVIEW (page 91).
Part I of this article began to consider solutions for the Undersea Warfare community if some hypothetical future technology somehow rendered the oceans genuinely transparent for purposes of anti-submarine warfare. For brevity, that unknown technological breakthrough was given the label MAGIC.
Part II will consider active means to neutralize MAGIC, should something that robs submarines of their stealth, in the conventional sense, ever in fact emerge. And since information on a submarine’s exact whereabouts is not necessarily useful if that submarine possesses superior weaponry for attack and defense, we will show that existing trends and plans in naval submarine development are consistent with coping fully in a world where MAGIC exists.
Hull-Forms and Weapons: Present and Future Directions
The discussion now leads to considering the actual field of battle at sea. Some general but relevant points will be made which apply as much in a future with MAGIC as they do apply today, or historically. Cumulatively, these points will demonstrate how to assure water superiority, come what may.
- Speed and precision are decisive: The detection of an enemy vessel, including a submarine, is never enough by itself to guarantee victory, either in the immediate tactical-combat sense or in the broader strategic sense of an entire war. To win a naval battle, destructive warheads must be delivered quickly and accurately onto high-value targets, which themselves will take strong measures in real time to defend themselves. One of the most effective forms of defense is to attack and destroy one’s attacker.
- The atmosphere versus the sea: War at sea in modern times occurs in three dimensions, each with their own physical characteristics: the atmosphere, the surface of the sea, and underwater within the sea. Crucial to future employment of submarines in a conjectural world with MAGIC are key differences in the properties of water and air, and also certain asymmetric properties of their interface.
- Hull (or fuselage)ยท forms: Because air provides less flow resistance than water, in general the fastest moving platforms are airborne ones. Submarines, faced with much greater flow resistance, cannot move at the same high speeds. However, by adopting a streamlined teardrop hull shape, the submarine can optimize its speed for a given amount of propulsion power. Furthermore, by diving deeper, increased water pressure can reduce or eliminate propulsor cavitation, enhancing efficient use of power to gain speed. Surface ships, floating on the air/ocean interface, are at a disadvantage compared both to aircraft and to submarines: They waste propulsion power through unavoidable wave-making, and their screws cavitate heavily because they tum at shallow depth. (Solutions such as hovercraft, hydrofoils, and water-jet propulsion cannot yet accommodate major warships weighing many thousands or tens of thousands of tons.) Thus, a nuclear powered fast-attack submarine might be by a significant margin the fastest type of big hull in any navy. This remains true completely apart from the question of stealth. Indeed, were acoustic stealth rendered irrelevant by MAGIC, submariners would be much more free to use flank speed.
- Modern blue-water amphibians: As has been discussed extensively in the open submarine literature, great advances are being made or planned for bridging the communication barrier presented by the air/ocean interface. Gradually, communications -including covert and high-baud-rate data links-between submerged submarines and surface ships, aircraft, satellites, or land bases, will become greatly enhanced. This will aid the full participation of submarines in total network-centric warfare; in the language of cyberspace, submarines become virtual amphibians. This, in tum, will be crucial to defense against any MAGIC that might emerge.
- The true all-weather warship: One factor that remains significant and yet uncontrollable during combat is weather. Weather at sea can affect a naval battle in several ways. Clouds, fog, mist, icebergs, and rain impair many sensors, including visual, radar, lidar, and infrared. In addition, surface storms create added background noise that degrades the performance of passive sonars-wind, rain, grinding ice cap edges, and breaking waves all make underwater sound. Perhaps most importantly, major surface storms can impede both the routing and speed of advance of fleets and convoys, and can badly impair the performance of their aircraft (both fixed wing and rotary wing), their sensors, and their weapons systems. A severe sea-state, especially if wind and waves come from an unfavorable direction, can present major problems. Only a submarine is able to maneuver with complete freedom under the most extreme surface storm, with no reduction in speed or physical discomfort for the crew. (In contrast, even a super carrier weighing l 00,000 tons and over l 000 feet long can find flight operations impossible and the ship herself barely habitable.) In the future, therefore, surface weather and ice caps may become a more significant factor in undersea warfare and undersea warfare more valuable in extreme-weather or under-ice operations–if submarines do somehow become much more easily detectable.
- Submarine adjutant vehicles: Submarine-carried ancillary vehicles, including ASDS SEAL-delivery mini subs, unmanned undersea vehicles with mission-reconfigurable sensors, armed unmanned undersea vehicles such as Manta, and unmanned aerial vehicles launched from submarines, add greatly to the all-weather advantage of a submarine in both attack and defense, and also significantly enhance that host sub’s safety in a wide spectrum of warlike scenarios. The Ocean Interface hull module of USS nMMY CARTER sets yet another precedent for greater vehicle and weapon capacity and variety, as does the modification of USS OHIO and some of her sisters into SSGNs.
- Undersea anti-aircraft weapons: Anti-aircraft weapons launchable from a torpedo tube, such as the Polyp hem missile, enable a submarine to destroy enemy aircraft seeking to detect or attack the submarine. This makes the submarine substantially more survivable-and thus potential loss of stealth is less dangerous to the submarine and her crew.
- Other active close-in defenses: Several devices are under development to intercept and destroy inbound enemy torpedoes. One such device is an anti-torpedo underwater rocket. Another is an ultra-high-speed dart: A U.S. Navy weapons lab recently announced that it succeeded in firing such a dart underwater at a speed greater than that of sound in water. (The speed of sound in water is approximately five times what it is in air.) One advantage of such a dart is that, by being supersonic in the medium in which the engagement occurs, it cannot be detected acoustically by an inbound torpedo until too late! Yet another means of active defense against torpedoes is a pressure-wave pulse generator array, mounted on the submarine’s hull. Such an array would presumably require a large amount of electricity to smash an inbound torpedo with a focused pressure wave; having this power available is one advantage of an all-electric submarine. In the future submarines will be able to actively engage and pulverize a type of weapon-the ASW torpedo-which up to now has required more passive defense combined with emergency escape-and-evasion techniques.
To pull together the points established so far, protection of submarines against MAGIC involves a layered defense enabled by network-centric warfare. MAGIC is less threatening if its sensor platforms can be identified and destroyed-this applies even to space based platforms, for which anti-satellite weapons would be essential. MAGIC is also useless if its data, though accurate, cannot be disseminated to command nodes or to survivable anti-submarine attack platforms with viable weapons. Information warfare assets can be used to target MAGIC’s download links. Joint war fighting formations, including active defenses by the submarines themselves and by armed escort, adjuvant vehicles, can help guarantee that detection does not spell doom.
Advantage Submarine; the Ocean as Armor
In future naval combat, special properties of the air/sea interface demand full exploitation.
- Hybrid propulsion, hybrid weapons: Supposing that the seas truly became completely transparent, submarines could restore parity or superiority against surface and airborne platforms if equipped with the proper weapons. Versions of such weapons exist today, or have existed in the recent past but were pulled from operational status because they appeared unneeded in world conditions prevailing at the time. The issue comes down to the speed with which an object can move through the water as opposed to through the atmosphere. Adaptations of SubRoc, and employment of super cavitating underwater weapons, level the playing field between platforms operating in the different mediums of air and seawater. An aircraft (or fixed or mobile littoral land site) can launch a missile armed with a plunging warhead that serves as a depth charge against a submarine, from far away. An aircraft can also cover a large distance rapidly to drop an ASW torpedma self-propelled weapon that attempts to home on the submarine. A surface ship can similarly fire a missile, such as an Updated AsRoc, which delivers an ASW torpedo very rapidly to a distant submarine target. But a super cavitating undersea weapon might move as fast or faster than an ASW helicopter or maritime patrol aircraft. If equipped somehow with a terminal stage bouncing betty anti-aircraft warhead, that plane or helo would be in for a nasty surprise. And a missile launched from a submarine can quickly leave the sea and make great speed through the air-which was one point of developing SubRoc. The future contest then becomes one of good fire control, adequate weapons capacity, and teamwork and data-sharing with friendly platforms. But with the proper weapons loadout, a submarine and its consorts might even defeat incoming super-sonic ASW cruise missiles. or ballistic missile barrages. R&D on submarine-launched supersonic anti-aircraft and anti-missile missiles, and theater ballistic missile defense. become even more potent force multipliers in a world containing MAGIC.
- The sea/air boundary is asymmetric: It is important to note that for purposes of engineering and design, there is much less stress on a weapon making a high-speed transition from the ocean to the atmosphere, than on one going the other way to make a hard, high-G-force impact with the water’s surface tension. In any head-to-head battle with surface or air opposition forces, this gives an advantage to a submarine equipped with the proper weapons. In addition. as mentioned above. the speed of sound in water is approximately the equivalent of Mach 5 in air. Any weapon or weapons platform approaching the submarine at less that Mach 5 will give advance warning of its approach, as its engine sounds pierce the water and then propagate on ahead to be detected by the submarine’s passive sonars. Furthermore, the viscosity of water is significantly greater than that of air; resistance (friction) to a moving body is much less in air than in water. This presents another asymmetry in a battle between a submarine firing a cruise missile, and a surface ship or aircraft firing a missile-weapon at the submarine. In the terminal targeting and impact stage, a missile attacking a surface ship will smash home with tremendous velocity. Last minute close-in defenses have notoriously short periods during which to react effectively. In contrast, the terminal target homing and impact stage of an ASW weapon faces a sudden drop in speed once it enters the water; even if the ASW warhead is itself super cavitating, its speed will drop to some 200 knots after an airborne transit speed of possibly 2000 knots. This gives the submarine a substantially longer reaction time during which to take active measures to defeat the incoming warhead; once again, advantage submarine. This line of reasoning also suggests that greater diving depth can give a submarine important extra protection, by increasing the distance an inbound air-deployed warhead needs to traverse. Thus, we may conclude that the ocean is much more than just a cloak of invisibility for a submersible ship deprived of large reserve buoyancy. For a submarine the ocean is armor. What’s more, that armor comes free of any weight or space penalty! Equipped with the proper offensive and defensive weapons, a submarine robbed of its stealth by MAGIC would nevertheless be able to stand and fight against opposition forces, with every expectation of winning.
- Going nuclear: Limited tactical nuclear war at sea is one type of potential conflict recognized by the Pentagon. Although all platforms, including submarines, are vulnerable to nearby nuclear blasts, submarines by being submerged gain considerable protection from air bursts such as might result from nuclear-armed cruise missiles. A nuclear air burst does not transfer much of its energy into the sea. That same air burst can be devastating to surface ships and aircraft at the same distance from the epicenter. Furthermore, the seawater surrounding a submarine gives it protection from electro-magnetic pulse (EMPra secondary effect of nuclear detonations that can wreak havoc with surface and airborne platforms. The same advantage to submarines would apply in the case of non-nuclear EMP weapons now in existence or under development, and also would apply to chemical and biological weapons. (Again, for a submarine the ocean is armor.) In addition, even hydrogen bombs exploding underwater have only limited range against a submarine; the lethal radius of a one:-megaton underwater blast, against a robust nuclear submarine, is approximately ten miles.
The Special Case of SSBNs
Up until now, and for the foreseeable future, the deterrent power of America’s SSBN boomers is founded in large part on their stealth. They cannot be detected, generally speaking, until they launch their salvo of ballistic missil each one armed with multiple thermo nuclear warheads. This is a very powerful deterrent indeed. What would happen to this deterrent in a world where MAGIC existed?
Were the boomers easy to locate, they could be attacked, and their weaponry neutralized at its source. The counterargument to MAGIC rendering our FBM subs useless is a combination of points made above, and points made in the open literature about strategic anti-submarine warfare. First, we have sought to establish in this two-part article that even if easily found, future American submarines would be by no means helpless. Potential countermeasures to MAGIC might assure that it would be impossible to locate-let alone destroy-all at-sea SSBNs with enough rapidity and assurance to preclude a devastating counter strike at the enemy. Even one surviving Trident sub would carry 24 missiles, each MIRVed with several warheads, each with a yield of hundreds of kilotons. This would seem to quite effectively discourage any sane individual or group, with the imagined capacity to drive home fatal attacks on multiple boomers, from ever actually doing so.
The same reasoning appears to urge keeping as many boomers as possible in commission and at sea If an enemy can obtain MAGIC, before the long-standing program that studies methods to assure the security of our boomer fleet can find effective counters, there will definitely be safety in numbers. This is something to think about for anyone considering reducing the now-planned Fourteen for Freedom, or anyone participating in arms-control discussions regarding the number of warheads allowed on each sub-launched ballistic missile.
High Speed, and Conventional Stealth. Remain Essential
Enemy MAGIC’s effectiveness could be limited and of short duration if the proper steps were taken by friendly forces. This suggests that. consistent as always with budgets and other national policy, a high tactical speed and high flank speed, and superb conventional (as opposed to anti-MAGIC) acoustic and non-acoustic stealth remain as important as ever, or perhaps become even more important. in a scenario in which MAGIC exists.
If MAGIC at first. or intermittently, reveals the positions of friendly submarines, those submarines need excellent speed and stealth to make the best use of time frames during which MAGIC has been jammed, decoyed, or disabled. In other words, it is vital to be able to restore the mystery as to a submarine’s whereabouts as quickly and as thoroughly as possible,’ once MAGIC has been blinded or neutralized.
Even if MAGIC is working, speed and stealth are key to helping evade fire-and-forget weapons, whose original firing solution was accurate based on MAGIC data but which grew stale during the weapon’s transit time. (If the weapons are designed for mid-course targeting updates via radio or guidance wire, priority should be given to breaking those links; the weapons then revert to fire-and-forget.) Conventional stealth would also help defeat the terminal homing of warheads originally dispatched by MAGIC, but reliant on conventional sensors to precisely strike the defending submarine. These two needs, speed and stealth, appear entirely consistent with present undersea warfare development and acquisition plans.
Conclusion
The actual fielding of an effective MAGIC technology would present a revolution in military affairs. But evolving joint network-centric warfare paradigms, improving connectivity between submarines and other platforms, and emerging extra-capable submarine-launched weaponry and probes, represent a non-hypothetical revolution in military affairs probably more than powerful enough to counter any hypothesized MAGIC.
