The big warships being built by the Soviets indicate an intent to contest control of those seas vital to U.S. interests. The Soviet Navy can no longer be considered a sea denial one. It should now be recognized as having a fleet which can move out into the major sea lanes of the worldand temporarily wrest control of vital sea areas from the navies of the West- and use them for Soviet benefit.
With this thrust, a Soviet surface fleet of 250 big warships, 600 auxiliaries and 1700 merchant ships become certain targets, if a major war at sea is generated. That places a need for a large number of antiship torpedoes for submarine use. The stockpile of MK 48 torpedoes is far too small to permit their being wasted on most surface ships. Moreover, to use the very costly, highly complex MK 48 for a relatively simple firing situation –such as is presented by a surface ship– is certainly not a cost effective way to conduct a war at sea. An antiship torpedo of far simpler design at a fraction of the cost– and more tactically reliable than the MK 48, is thus indicated. Remember that the British submarine Conquerer’s skipper– with Tigerfish torpedoes aboard (like the Mk 48, grossly overpriced and overdesigned for the job)– preferred to use the simpler, MK VIII torpedo to sink the Argentine cruiser Belgrano. He realized that in war, his Tigerfish ASW torpedo was not the best weapon for this surface ship. Other possible targets, those of particularly high speed, like SES, hydrofoils or wing-in-ground warships would also be inappropriate targets to shoot at, and their destruction should be relegated to missiles. Thus, an antiship torpedo need not be designed for all surface target situations. To do so, would probably make the cost of the antiship torpedo prohibitive.
In considering a new antis hip torpedo, two things should be remembered, historically. In the gestation of the MK 48 torpedo– in the 60’s– it was planned to be a surface ship’s ASW weapon. It was not planned to be a submarine ASW weapon! That was a fall out. Nor was it considered as an antiship weapon. The Soviet surface fleet in the 60’s presented no great threat to U.S. ships on the broad oceans of the world, hence there seemed little need for an antiship torpedo. But u.s. surface ships badly needed a replacement for the MK 44 torpedo to meet the rapidly growing threat of the Soviet’s submarine force. So the MK 48 was designed by U.S. surface ASW people to be basically used from surface ships against submarines– not for submarines against submarines. Since surface ships were noisy, their antisubmarine attacks were overt. The MK 4H was thus more importantly a fast torpedo, even if noisy. Because of its speed, it could successfully close and hit even alerted subs under surface ship attack. Therein lies the genesis of the MK 48’s anti-surface ship problems which stem from the jury-rigged wire guidance system, the preoccupation with giving it even higher speeds regardless of the additional noise generated, and its badly impaired passive capability at its high operating speed.
It would thus appear that a new antiship torpedo might avoid the pitfalls of faulty past torpedo philosophy. That is, some basic principles inherent to a good submarine antiship torpedo need not be violated in the name of economy, duality of purpose, need to use new R&D, immediacy, incompatability with weapon loading, etc.– all the excuses mustered to justify a less than optimum weapon.
Some of the principles behind good antiship torpedoes are herein addressed. Some are not obvious to non weapon-oriented planners– who also see little chance that such a weapon would be used in war in “our time.” But to the submariner who feels he is likely to have to employ a new antiship torpedo against a resolute and competent enemy, such principles should have meaning and urgency.
This weapon must be designed primarily to be used in ~· As such, it should not specifically be designed for exercise shots for peacetime training. It should particularly be designed for expendable use in conflict. Large numbers of ship-targets call for antiship torpedo stockpiles of considerable size. Hence. the cost of the antiship torpedo should be reasonably low. This means that to adapt a warshot torpedo for exercise use may be too costly a matter. Special exercise torpedoes which simulate the warshot may be the practical solution. (To use a MK 48 as an exercise antiship training weapon– with its possibility of being lost– inhibits the exercise situation and reduces the training achieved.)
A new antiship torpedo must similarly be designed for the environment expected in ~· This implies both the geographical and tactical environment in which the torpedo will be used. On the one hand, lessons from World War II would indicate that the blue waters of the ocean are not used exclusively by surface ships. In fact, shallow waters were used by surface ships– particularly merchantmen– to reduce the enemy submarine threat posed. In shallow waters, today’s submarines should be less of a threat due to their greatly reduced passive detection capabilities against surface ships– lacking convergence zones , little or no reliable bottom bounce paths, and reduced direct-path detectability due to frequently high sea noises. (In the Falklands War the high biologic noises and the shallow sea areas out beyond the Islands markedly reduced the British nuclear submarines’ detection capability.) On the other hand, World War II experience showed that torpedo attack on surface ships usually resulted in their initiating some countermeasures. On sighting the wake of a torpedo, a merchant ship frequently tooted a two-blast whistle signal meaning “I am being attacked to port.” or a one-blast signal meaning “to starboard”. This greatly localized the area from which the torpedoes were launched and generated rapid counter actions by other ships in the group. Noisemakers were dropped off ships (usually depth charges), courses were altered, and ASW escorts whether surface or air, hurried to the general locale of the submarine. If a warship was put under attack, the WW II steam torpedoes used produced such solid noise spokes on the enemy 1 s sonar scopes as to result in a frantic broadcast, “Incoming torpedoes on bearing- True.” This was transmitted over a primary tactical circuit to all ASW units in company. Then, an ASW aircraft would sometimes wing its way over the attacking submarine and drop a bomb nearby. Surface ship “foxers” were often activated, false bubble targets were put in the water, active sonars were keyed to create additional noise in the ocean. (One thing that can be counted on today is that if an incoming torpedo is detected by a Soviet warship, the warship will, as one possible example, launch a massive decoy bubble-target astern and then swing away to escape the attacking torpedo. This puts the false target between the warship and the torpedo, while an ejected noise maker would drown out the warship 1 s screw noises preventing passive acquisition by the U.S. torpedo.) A detected torpedo gets tactical response from a competent enemy!
Thus, an antiship torpedo should be wakeless. Its necessarily shallow use in shallow waters prevent a wake-making torpedo from being run deep to mask its bubbles. Torpedo wakes cause accurate and timely countermeasures as well as providing a good localizing of the firing submarine.
Similarly, a torpedo should be quiet and covert in its launch and in its attack. A torpedo is a slow weapon which allows-8 possible defensive response measured in minutes rather than a few seconds– as with the mach-speed homing weapons of today. Even at 60 knots, it takes five minutes for a torpedo to close a target from 10,000 yards. A target has more than enough time to activate an effective bag of countermeasures. Surprise is the essence of successful submarine attack with torpedoes. A noisy torpedo only compromises this essential element for success. Strangely, submariners today seem satisfied with torpedoes which tend to alert their targets early in an attack. Yet, their nuclear submarines which shoot torpedoes combine a high degree of mobility with great stealth. Understandably, noisy torpedoes require high speed in any firings, to chase down an evading target, because it was quickly alerted. But no significant penalties accrue in peacetime as a result of using a torpedo which is lacking in the element of surprise. In wartime, however, a noisy torpedo is likely to cause trouble on all sides and even overhead while targets will use countermeasures to prevent the torpedo from hitting. Such countermeasures are likely to be too costly and in too short supply to be used in peacetime exercises. Hence no experience as to their effects is gained.
So, importantly, a torpedo should be designed without a wake and with little noise, in order to minimize the probability of its being countered. It is not enough to build counter-countermeasures into a torpedo. The enemy has too many options for introducing new counters which might be unrecognized by a programmed torpedo.
The range of the antiship torpedo need not be great.The high mobility and covertness of today’s submarines makes possible a nearly optimum positioning for torpedo firing with a high element of surprise. (The British nuclear submarine Conqueror moved into just such a position for the firing of its old MK VIlis against the Belgrano despite her being escorted by two Argentine destroyers. Two DD’s were, traditionally, a good protective force for a single cruiser– until the advent of the nuclear submarine. Against more efficient ASW surface forces, however, greater firing ranges than the 1000 yards used by the Conqueror, may be required. But the ranges will Still not be considerable.) With the expected good airborne ocean surveillance systems in operation, the approximate positioning of high value ships in groupings of ships should be generally known well in advance of torpedo attack. This makes for simplified, reliable submarine tactics which minimize the chances of being detected while making an approach on a group of targets. Use of torpedoes at well beyond 20,000 yards may seem attractive for the reduced risk entailed. But the chances of hitting with a noisy weapon should be low, and the likelihood of counter attack great. Cross bearings taken on torpedo noise could lead the enemy back to the submarine’s firing position making very long range shots even more hazardous. At ranges of 40,000 yards, for example, it would seem more practical to use missiles against high value, well protected warship targets.
The speed of a covert antiship torpedo need be no more than about 10 knots more than that of its potential targets. With this differential of speed, a weapon attacking with a high element of surprise should close even those targets which are defensively manuevering wildly at their highest speed. Again a very few ships may have sufficiently high speed to make a 10-knot differential impractical. But to design a torpedo for this unique situation would probably make the antiship torpedo too costly.
The warhead of an antiship torpedo should be as large as is feasible within the constraints of submarine torpedo tube use, the torpedo range required, and its necessary speed. Although the Conqueror could effectively use non-homing straight running torpedo in a war situation, something better in the way of trajectory control of the torpedo and its ability to home on a target seems indicated for the torpedo of future years.
It should be recognized that the fire control solution for a surface target will normally be far more accurate than for a submarine target. The surface target makes far greater noise and is more likely to be locked into a pat tern of movement which simplifies its being tracked. Broad ocean surveillance is also likely to reveal patterns of ship movements and patterns of ship formations. Thus, a quiet torpedoe’ s passive homing device should readily acquire a surface ship’s noise both because of its consistent loudness and because the torpedo is run at a depth where it searches only in azimuth to detect the surface ship’s noise. Running the torpedo at a speed below cavitation of its propellers and skin reduces the need for an active homing capability in the torpedo. With a good fire control solution, a homing torpedo can be launched to intercept a target with the passive homing device keeping the torpedo on a course for interception- but with a slight bias to insure hitting forward of the screws. The active homing capability should only be activated when the passive homer is countermeasured– which may happen in the last few hundred yards of its attack. Since active homing compromises the element of surprise, it should be only a fall-back system of no more than a few hundred yards in range capability. Similarly, wire guidance is not recommended for the antiship torpedo– to keep cost low. For those tactical situations where wire guidance appears necessary– and they should be few– the MK 48 with wire guidance seems to be a cost effective solution.
While still being cons is tent with the principles involved in a good antiship torpedo, the cost of such a torpedo can be held to only a fraction of that for an ASW torpedo. This appears to be achievable within the framework of today’ s torpedo technology. A 43-knot, non-cavitating, battery driven, 21″ torpedo, of 20,000 yards range and with a 1000-pound warhead, with a greatly simplified passive and active homing capability is indicated. Such a weapon can be developed today and should cost in the several hundred thousands range rather than well over a million– as estimated for today’s highly complex ASW torpedo.
Keep it quiet, keep it wakeless, keep it simple as a warshot, and give it a k!& bang. Then the submarine will have a weapon which can be skillfully used with reduced risk against the best of enemy ASW opposition.
