The implementation of advanced technology into submarine systems is making the submarines of many nations more effective in fulfilling national objectives. Conversely, the emergence of technologies not initially directed toward submarine applications is dramatically increasing the range of objectives which may be assigned to submarines. It is now being recognized, even in the less developed nations, that the characteristics of modem submarines and their ability to exploit emerging technologies allow them to contribute to many aspects of a nation’s defense, including those not traditionally considered within the purview of navies.
Technology has removed the earlier constraints of speed and submerged endurance. Thus, the submarine, today, can outperform virtually all surface warships. In the Falkland Islands conflict, the speed and endurance of the nuclear attack submarine allowed the United Kingdom to achieve an initial presence in the adjacent ocean areas more than a week before the first surface detachment of the British Expeditionary Forces arrived.
The development of ballistic missiles and their incorporation into the nuclear submarine changed the contribution of the submarine to national policy during peacetime. There are other technologies now available that will similarly improve military capabilities when incorporated into the submarine. These technologies can further enhance the peacetime role of the submarine as well as its contribution to limited and large scale conflicts, to strategic defense and even to responses to terrorism. The emergence of low probability of intercept data exchange links, remote sensors, miniaturized electronics, improved missile fuels, and dramatic improvements in munitions offer a new level of mission opportunities for the submarine. Further, the development of several closed-cycle power options has put many new submarine capabilities within the grasp of nations which do not have the resources or infrastructure necessary to support nuclear powered submarines.
Technology Generated Threats
As in all aspects of warfare, technology can represent the double-edged sword of measure and countermeasure. Just as new technology has improved the submarine’s capability, there are technologies which have improved the capability of ASW forces. The level of stealth achieved by post World War ll submarines is becoming inadequate today. While steady improvements have made the submarine more capable, it is important to recognize that with little further improvements these submarines will become extremely vulnerable. The challenge is to ensure that we and our allies avoid the danger of believing a submarine’s detection is virtually impossible and that we can stay ahead of countermeasures by continuing to “quiet” submarines.
Since technology is dynamic, it would be wrong to allow oneself to think only in terms of an acoustic advantage. What, for example, is the implication of a magnetic advantage? Why, in fact, reduce the magnetic signature of a submarine? Also, why do Soviet submarines have vortex annihilators on their after decks and around their appendages? Are the dispersal of vortices and the reduction of wake intensity and other hydrodynamic signatures becoming as important as sound quieting? If so, then who has the hydrodynamic advantage? These questions must be asked frequently and answered objectively.
Recent research efforts in the United States have been described as being directed more toward reducing technical risk than toward the dramatic innovation displayed in the two decades following World War IT. Nuclear power, the ALBACORE shark-shape hull form, high-yield strength hull materials, cruise missiles, ballistic missiles, inertial navigation, and revolutionary improvements in sonar were among the innovations in submarine systems during that period. New technologies, such as advanced hull materials, drag reduction techniques, coating systems, and new propulsors were examined, but in a desultory fashion. This has not been the case in other countries such as the Soviet Union, the United Kingdom, and France. Thus, to benefit from the latest technologies we must look at the capabilities developed by other nations.
Inherent and Technological Limitations Selecting performance parameters for a new submarine class creates a series of dilemmas. For a given displacement, parameters such as speed, sound quieting, and diving depth each compete for weight allocation. Thus, an increase in speed may be achieved at the cost of diving depth; or sound quieting may be achieved only by increasing displacement.
Those constraints or limitations, which applied to older nonnuclear submarines, are often perceived as manifestations of the laws of physics and therefore as inviolate. But this is not the case. These constraints merely are reflective of the limitations of the technology being employed. There are technologies which can increase speed without demands on volume or without increasing noise. Similarly, there are sound quieting techniques that do not require the mass and volume associated with more traditional methods.
To suggest that a submarine “is inherently noisy and blind when using speed” is to suggest that increased speed is necessarily related to increased self-generated noise. In the past, the underwater speed of fleet submarines was increased by improving propeller design and reducing drag. Such increases in efficiency not only increased speed, but decreased noise. Certainly, today’s submarines are not “blind” when they cruise at speeds more than double that of World War II submarines.
The challenge is to identify technologies which can simultaneously enhance the performance parameters. For example: there are technologies that can simultaneously suppress radiated noise, reduce drag, and enhance explosive resistance. It is stated in foreign literature that a submarine which employs polyfunctional technologies can achieve greater levels of performance for a given displacement — and it may be less costly. Such sets of technologies that can satisfy the established performance goals simultaneously are those which are most worthy of pursuit. The challenge to the submarine R&D community is to identify and develop those technologies that can eliminate some of the performance and cost tradeoffs which now constrain the design of submarines.
The Technical Challenges of Stealth, Toughness and Flexibility.
Stealth must not be taken for granted. It is achieved only through careful operation and constant incorporation of emerging technologies. Submarine signatures not even recognized in the 1940s have been subsequently widely exploited. The submarines of nations which did not incorporate emerging quieting technologies have proved highly vulnerable. Moreover, new vulnerabilities can be avoided by maintaining a constant awareness of new developments in sensors and signal processing.
Relative to aircraft and high performance surface ships, a submarine is basically a tough structure. Its pressure hull and buoyancy tanks provide a stalwart structure which, when coupled with new blast-defense technologies, provide it with protection not available to other, similar-sized naval platforms.
Cumbersome is not an appropriate descriptor for a vessel that can maneuver in three dimensions in an environment that traditionally has been limited to two-dimensional movement. Submarines with multiple propulsors have been as agile as any surface vessel, and now boundary layer control technologies can increase that agility. The speed and ability to bring heavy firepower to bear on a wide array of targets contributes to the “flexibility” of submarines. Thus, new technologies must be developed and incorporated into future designs to ensure the continued stealth, toughness, and flexibility of the submarine.
Being aware of what is going on, below and above the surface, offers similar challenges. In World War II that requirement could be described in terms of kilometers. Broader area coverage was provided by intelligence or other sources and relayed by HF radio broadcast to the submarine. Today, because of the submarine’s speed and extended sensor and weapon ranges, the radius of coverage has been greatly increased. In World War II, collecting data on the enemy required extended periods near the surface. That is no longer the case. Still, the requirements will become more demanding as the area the submarine can affect and the number and type of potential targets continue to increase.
While today’s submarines cruise at speeds never achieved by World War II submarines, they “see” at ranges far beyond those conceived as possible during that period. Increasing “tactical” or maximum “quiet speed” has been a continuous objective of submarine designers over the last several decades. Maximum speed and submerged endurance will continue to increase. This increase will be available even to those nations which cannot invest in emerging nuclear power technologies. The introduction of diesel-hybrid (battery/nuclear) power sources, fuel-cells and closed-cycle engines while still much less capable than contemporary nuclear power plants, opens up a new regime of submerged endurance for non-nuclear submarines. With that increase, ancillary technologies which suppress power generation, propulsor, and flow noises, will have to be developed. Without long term and continuous attention to this performance parameter, the potential of high underwater speeds cannot be realized without compromising “stealth.”
The remaining performance parameter relates to “combat means.” The ability of submarines to participate in extended melees and to reengage escaping targets has improved significantly over the last decade and will see even more dramatic improvements over the coming decade. More and diverse types of weapons in their launchers ready for firing allow a submarine to simultaneously engage a variety of targets. It is the submarine, now equipped with an array of missiles and torpedoes, that can press a determined attack. Attack is always accompanied by risk, but today’s submarines and those in the near future can be equipped with the means to reduce that risk. The maximizing of the covert qualities of weapons is equally as important as the stealth built into the submarine itself. Quiet, electric or closed cycle driven torpedoes, without wakes, with low self-noise from reduction of skin cavitation, with covert homing systems (the Soviets have indicated an interest in laser and IR homing systems) in addition to passive acoustic, wake-homing etc. are being developed in a number of countries.
Making Submarines Affordable
As with all the previous issues raised, affordability deserves constant attention. Evolutionary improvements tend to increase costs. Revolutions in technology however £ru1 reduce costs. The potential to reduce production and materials costs must be &iven hi&h value in selecting technolollY priorities. Cost affects force levels; if not of the submarines themselves, then of the support systems and expendables they require to be effective. Promising advances in new materials and low cost, highly reliable production techniques need to be pursued to ensure the submarine force has the number of submarines and weapons necessary to assist in carrying out national policy.
Submarine leaders are looking for an “edge” to give their fighting men an advantage through technical developments. A technical advantage can be enhanced if new capabilities are unrecognized by an enemy until they are put into use. In fact, “technological surprise” can be as important as operationaltactical surprise. The achievement of technological surprise moreover requires both an awareness of a potential enemy’s technology and the secret development of one’s own technologies. From the literature, we know that “surprise” is an integral part of Soviet naval art. It has been recognized that the ALFA’s speed is 50% greater than initially estimated, and it was initially credited with a titanium hull. And, the noise level of the AKULA was observed to have achieved a quieting level not expected until near the turn of the century while the “abandoned” Soviet SS-NX-13 , a homing ballistic missile for use against carriers, might have proved an unexpected weapon.
The Soviet Union has been successful in developing Western basic research. U.S. Navy laboratories produced: the first work on gasification for drag reduction; the first work in bionics as a tool to gain insight into improving underwater performance; the first work in coatings to reduce drag on underwater vehicles; and the first proposition for magnetohydrodynamics for submarine propulsion. While these programs have received only desultory interest in the United States, they spawned major research efforts in the Soviet Union. It is apparent that technologies considered unfit for U.S. needs and those of her allies may be responsive to the needs of navies with different strategies/objectives.
Emerging technologies are increasing the potential for submarines to contribute to more aspects of national policy of many countries than was possible in the recent past. Similarly, a dynamic national policy can be a stimulant for advances in submarine technology regardless of the size of the host country. Counter-terrorism, low intensity conflicts, and local wars, as welJ as global conflict situations demand more advanced submarine technical capabilities. While the demands of policy foster new submarine technology, emerging technologies also can increase the breadth of policy options. Innovation and imagination are necessary to continue this process and to ensure that the full potential of the submarine is realized. The dynamics of technology demand that warfare systems continue to improve if they are to remain viable. Long tenn basic research programs are the “seed corn” of future warfare systems and hence must be aggressively supported at national levels. The improvements in submarine speed, depth, and stealth, which are discussed in foreign literature as being currently attainable, are the result of many years of intense and continued efforts. Since countries can have unique requirements, it is apparent that all must be involved to some degree in research to ensure that specific needs are satisfied. At the very least, the submarine consumer must investigate the offerings of multiple suppliers since no one country has the edge in every aspect of emerging submarine technology.
K. J. Moore