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e same cruel sea that hurled the bow of ' c USS Remey (DD-688) upward is still *lt there waiting to pound and pummel, "npair a warship’s speed and naneuverability, to impede the operation
er weapons and sensors, and to hinder ^ efficiency of her crew. One of many *dl forms now thought to be capable of u’arting rough seas is a sort of tin can stilts—the hydrofoil—which can brave a>nPaging seas with little degradation of they speed or seakeeping ability.
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JL he primary elements of a warship are a hull to provide form and structure and to contain and support all other components of the ship; propulsion machinery for mobility; a combat system consisting of weapons, sensors, and data-handling devices to provide fighting capability; and people to operate the ship. These basic categories provide the framework for discussion of technological trends in U.S. warship design. Let us begin with hull forms.
Displacement-type: Three current lines of development are particularly important. The first is in the direction of reducing the resistance a ship encounters to her movement through the water. Resistance increases as the speed of the ship increases, and consequently more horsepower is required to overcome it. The problem is that, as speed increases, each increment of speed becomes more and more costly in terms of additional horsepower required. For a typical surface combatant to gain a 10% increase in speed at 20 knots requires roughly a 30% increase in horsepower. At 30 knots, a 10% increase in speed requires roughly 50% more horsepower. At 40 knots, a 10% increase in speed requires an increase of more than 100%.
Although some minor improvements are anticipated through advanced work in ship hydrodynamics, the displacement-type hull is clearly up against natural barriers because of its physical characteristics. Thus, it seems equally clear that future ships requiring speeds in excess of 40 knots will not have displacement-type hulls. This lack of highspeed capability is actually less of a penalty than it might seem, however, since it appears that the value of speed has actually decreased for many naval missions in recent years. This has come about as the result of the current sophistication, smartness, agility, and increasing range of weapon systems and the increasing potential of surveillance and worldwide communication systems. The displacement-type hull offers other natural advantages as well, so we may be assured that it will continue to dominate our warship fleet.
The second important line of development for displacement-type hulls is aimed at reducing the motions induced on the ship by ocean waves, i.e., improving the seakeeping capabilities. Rough-sea conditions impair not only the operational capabilities of
the ship—speed and maneuverability, the operation of weapons and sensors, and the efficiency of the crew—but they can also lead to damage of the ship and her weapons and equipments. Sheer size is one way to promote good seakeeping ability, but most naval missions do not require the large-size ships that are really effective in this regard. Limited benefits can be obtained by incorporating devices such as anti-roll tanks or underwater fins to reduce the roll component of the ship’s motion. The greatest potential for improved seakeeping seems to lie with a radical departure from the conventional hull forms such as provided by the small waterplane area, twin hull (SWATH) ship (Figure 1).
The SWATH is a rather unconventional type of displacement ship, basically a development of the catamaran. Below the surface of the water is a pair of submarine-like hulls. They support a box-like structure above the water by means of long, slender struts. The parts of the ship that provide her buoyancy are below the waves while the part that contains most of the equipment, personnel, and armament is held high above the surface, thus allowing the SWATH to proceed in heavy seas with almost undiminished speed. Compromises must be made, however, and the SWATH’s seakeeping excellence is obtained at the cost of a larger investment in steel and propulsion machinery to carry a specified payload. (Of course, if the ship’s payload—aircraft, for example—can be useful only when ship motions are moderate, the SWATH may well be the least expensive solution to the design problem.) The speed of the SWATH ship is roughly the same as that of conventional ships (20-40 knots), but she can maintain this speed into much higher sea states. Consequently, a 3,000-ton SWATH-type frigate would have seakeeping capabilities equal to those of a 6,000- or 7,000-ton conventional-hull frigate.
Hydrofoils: Although the value of ship speed has decreased for many naval missions in recent years, there is still a variety of special missions for which speed seems to have an increased tactical significance. As a result, the Navy has been studying possible solutions which attempt to move beyond the displacement-type hull in order to overcome the natural barriers to speed on the oceans. One answer might be the hydrofoil which provides a high-speed capability into rough seas with little degradation of either speed or seakeeping ability. A 50-knot speed is considered typical, but current U.S. Navy developments employing variable-geometry foil features indicate that 70 knots can be achieved in a militarized vessel.
Over the last 15 years, the Navy has designed and constructed, with industry support, a series of engineering-prototype hydrofoils. Starting with purely experimental craft and progressing through operational evaluations of a pair of militarized hydrofoils off South Vietnam in 1969, steady development has resulted in the design and construction of the USS Pegasus (PHM-1) class. The PHMs, six of which are to be acquired through 1982, each carry eight Harpoon surface-to-surface missiles, a 76-mm. gun, and integrated fire control systems. While today’s 250-ton hydrofoil boats have limited endurance and thus require a “mother ship” for extended open-ocean operations, current Navy studies include designs in the 1,400- to 2,400-ton range. These larger craft would be capable of 30-day missions and foil-borne ranges of 2,500 to 3,600 nautical miles. All on-board maintenance would be done by each ship’s crew.
Power Static-Lift Types: A relatively new and promising class of naval craft is characterized by its technique for vertical support. Instead of being held up by static buoyancy, as conventional displacement ships are, or by dynamic forces produced by submerged foils, the vessel sits upon a cushion of air generated by powerful fans thrusting downward and contained at least in part by a flexible skirt surrounding the lower hull. These craft fit into two basic categories, commonly referred to as air cushion vehicles (ACVs) and surface effect ships (SESs).
ACVs are relatively small (up to roughly 200 tons) and relatively unsuited to open-ocean operations, especially of any lengthy duration. Their applications will be those requiring either an actual amphibious capability—such as landing craft for assaults over the beach—or those requiring operation in shallot
ATH-type ship provides a stable platform for aircraft operations
Waters. The Navy currently has a program to develop a tlass of air cushion landing craft, and two pro- t(|types have been recently constructed. They have speeds of about 50 knots, but as much as 100 knots tan be expected in the future.
A deep-ocean naval role is foreseen for the surface effect ship. The Navy’s current SES program focuses °n the design, development, construction, and com- Ptt'hensive testing of all aspects of a ship of about 3'000 tons. The operational concept of an SES frigate ls to sprint out well ahead of the convoy at regular jftervals, stop, and then with helicopter assistance, lsten for submarines. The high speed, coupled with ^e increased effectiveness of the helicopter and ship S()nar when operating clear of the convoy, will enable SEs/helicopter team to detect and destroy the Submarines long before they have an opportunity to kc't close to the convoy.
The 3,000 -ton SES was designed by Rohr Indus- *ries- She will be 266 feet long with a beam of 108 <'tt and have a longitudinally-framed aluminum- ‘dloy hull. Power will be provided by six General t'ctric LM 2500 gas turbines, two driving lift fans to raise the ship on her cushion, and the other four driv- ln& water-jet propulsion units for forward movement at speeds of up to 80 knots. This armed devel- °prnental prototype, scheduled for completion dur- ln& 1982, will undergo approximately two years of avy testing, including fleet operations simulating anticipated ship capabilities in a realistic environment. Future development efforts include the planning and preliminary design studies for surface effect guided-missile frigates (FFSG) and for much larger ships incorporating antiair warfare, surface warfare, and amphibious assault capabilities.
Hybrids: The idea of combining different hullsupporting mechanisms in a single craft has led to the theoretical development of hybrid forms, samples of which are shown in Figure 2. One major advantage of these hybrid concepts is that they add variables so the designer can better accommodate to specific requirements and constraints. By the last decade of this century, technology will enable the production of such hybrids without significant problems.
Whether these hybrids, hydrofoils, and SESs will be built in significant numbers for the U.S. Navy will depend on whether the added complexity will be offset by economic value and/or performance gains. Possibly the most important consideration will be the value that the Navy of the future attaches to high speed. SWATH ships are much less a departure from the conventional displacement hull than the other types. It is expected that.they will be built as large as 30,000 tons for V/STOL (vertical or short takeoff and landing) carrier purposes, primarily because their excellent motion characteristics in rough seas are so important for aircraft operations.
Hull Structure: Within the last 30 years, the changes in percentage of displacement devoted to conventional surface ship structure have been of secondary nature despite the emergence of a more scientific basis for their design and great advances in materials. Some modest gains in efficiency and economy of ship structure seem possible within the next decade or two by improving predictions of seaway loads and the ship’s response to them. Also, design will increasingly be integrated with production. The choice of materials for ship structure is likely to remain dominated by economic factors, but prospects exist for possible competitors to the mild and high tensile strength steels now used in warships.
In a study just completed, a hypothetical frigate was designed using an all-aluminum hull. The aluminum-hull ship design was competitive in price with the steel design. Future advanced surface ships might need the weight saving achieved with an aluminum hull to better meet their performance requirements. The Navy is preparing for this possibility by testing an 85-foot aluminum-hull ship model at the David W. Taylor Naval Ship Research and Development Center under simulated life-cycle loading conditions. The results of this effort will provide data on fatigue performance of welded aluminum ship structures and procedures for best methods and the frequency of inspection of aluminum ships in the fleet during the period they are in service. Obviously, all the high-performance craft mentioned above must use aluminum hulls to obtain a feasible design. Consequently, the Navy has built and successfully operated aluminum-hulled hydrofoils, air cushion vehicles, surface effect ships, and fast patrol
Figure 2 Hybrid Surface Ship Forms boats up to 350-ton displacements. Contract design plans are being prepared for an aluminum-hulled 3,000-ton SES.
Advanced composites, such as glass, graphite, or boron, in a resinous matrix have produced structural elements of high strength and high stiffness-to- weight ratios. Their utility has been demonstrated by their use as aircraft structures with weight savings up to 68%. Because of the high weight-reduction potential, the major thrust of the current surface ship ex" ploratory program is to develop and certify a variety of advanced composites. However, the use of these materials appears to be limited to special applications in a ship’s structure. They are not expected to take over any significant portion of the structure of a displacement ship.
The extent of application of these and other new materials is hard to predict since economic considerations will be a governing factor. Further developments of materials and fabrication methods are subject to significant changes. As a result, they have the potential of greatly affecting the structural weight of future warships.1 The structural weight of 1 Structural weight is one of a number of components contributing to the total displacement of a warship. A ship's structure comprises the hull, decks, bulkheads, etc., that constitute the empty ship. The other components of displacement are propulsion machinery, electrical systems, electronics, auxiliary systems, outfits and furnishings, armament, and loads (such as fuel, water, and ammunition).
TABLE 1
HYBRID SURFACE SHIP FORMS
HYBRID TYPE
SMALL WATERPLANE AREA SINGLE HULL (SWASH) SHIP
HYDROFOIL SMALL WATERPLANE AREA SHIP (HYSWAS)
LARGE HYDROFOIL HYBRID SHIP (LAHHS)
HYDROFOIL AIR CUSHION SHIP (HYACS)
SMALL WATERPLANE AREA AIR CUSHION SHIP (SWAACS)
SOURCES OF SUPPORT
BUOYANCY (85%) FROM SINGLE SUBMERGED SLENDER HULL AND STRUT AND DYNAMIC LIFT (15%) FROM SURFACE-PIERCING FOIL SYSTEM.
BUOYANCY (70%) FROM SINGLE SUBMERGED HULL AND SINGLE STRUT AND DYNAMIC LIFT (30%) FROM FULLY-SUBMERGED FOILS.
BUOYANCY (70%) FROM SINGLE SUBMERGED HULL AND DYNAMIC LIFT (30%) FROM FULLY-SUBMERGED FOILS (MULTIPLE STRUTS ARE EMPLOYED TO JOIN UPPER AND LOWER HULLS).
POWERED STATIC LIFT (70%) FROM HIGH LENGTH TO-BEAM AIR CUSHION/RIGID SIDEHULL SYSTEM AND DYNAMIC LIFT (30%) FROM A FULLY SUBMERGED FOIL SYSTEM.
POWERED STATIC LIFT (70%) FROM HIGH LENGTH TO-BEAM AIR CUSHION/RIGID SIDEHULL SYSTEM AND BUOYANT LIFT (30%) FROM A SINGLE SUBMERGED SLENDER HULL AND SINGLE STRUT.
rhe Oliver Hazard Perry (FFG-7), for example, constitutes 30% of her displacement while that of an all- uluminum warship could be as low as 20%. The result of using aluminum would be the building of smaller ships, or more capacity would be left for Payload weight, including added fuel for endurance. It appears that if we are willing to accept 3,000-ton, aluminum-hull surface effect ships, then we should also be willing to accept conventional displacement- type hulls of the same size made of aluminum, once *t is proven that they can withstand the loads imposed by the sea.
Propulsion: The selection of a propulsion-plant type ls made from among those currently in use: steam (generated by fossil fuel or nuclear reactor), gas turbine, and diesel. The predominant propulsion plant type in the Navy’s warship fleet today is steam. Over several decades, the conventional steam plant’s pressure and temperature were raised, greatly increasing the amount of energy that could be carried by a fdven amount of steam (300 pounds per square inch UP to 1935, 600 psi up to 1947, and 1,200 psi since then). This increase correspondingly decreased the Physical size of the propulsion plant needed to produce a given amount of horsepower. Another effect the improved efficiency with which fuel could be converted into power. However, this pattern of deceased size effecting greater efficiency is not likely to c°ntinue since each increase in pressure and temperature brings more complexity and places greater demands on the materials composing the plant. Even though the higher temperature and pressure result in a more efficient power plant, a point of diminishing mturns is reached which will prevent further increase beyond today’s 1,200 psi, 950° F. steam conditions. In spite of the fact that the steam plant is expected to be useful for a variety of applications in future warships, the workhorse of the fleet by the 21st century will be the gas turbine, either alone or in combination with another type of prime mover.
Since the design of the Spruance (DD-963)-class destroyers in 1970, only gas turbine propulsion plants have been selected for our new-design surface combatants. As a result, the number of gas turbine- driven warships in the fleet will climb from the current 13 to more than 100 in less than ten years, even if no more new designs are committed to this type of power plant. The gas turbine’s greatest virtue is that it can produce a relatively large amount of power for its size and weight. In the case of the hydrofoils and surface effect ships, they would not even be feasible without gas turbines.
Specific fuel consumption of gas turbines has been steadily reduced over the last 20 years, as shown in Figure 3. Engines such as the FT-9 and LM 5000 which incorporate the latest developments are not yet in service but are expected to be available for introduction into naval ships in the 1980s. These advances have come about through the use of improved materials which can withstand higher temperatures and by employing new techniques to cool the gas turbine blades in the first and second rows adjacent to the combustion chamber. In the future, new blade materials such as ceramics may offer the potential for even further increased inlet gas temperatures and the attendant significant improvement in fuel consumption. Further improvements in thermodynamic efficiencies will be achieved through the use of combined plants such as combined gas and steam
(COGAS) shown in Figure 4.
In typical naval application, a COGAS plant for the Spruance would cost about $140 for each horsepower, and annual overhaul costs would be about $236,000. These compare with the $ 116 per horsepower acquisition cost and $200,000 overhaul cost for the presently installed gas turbine power plant. However, the cost penalties in these two categories would be substantially overshadowed by savings in fuel cost resulting from the differential of specific fuel consumption from .40 to .33 of a pound per horsepower hour for the COGAS plant.
Unfortunately, non-fossil fuel, nonnuclear solutions to warship propulsion must be dismissed, at least for the moment. All indications are that other sources such as solar energy, ocean thermal energy converters, or the wind will not be practical for warship propulsion even by the early part of the 21st century. For example, to collect 50 kilowatts of energy for a warship from solar energy, the entire topside of the ship would have to be devoted to solar energy collection; yet 50 kilowatts represent only a fraction of 1% of the power needed for such a ship. However, there are some dramatic advances in store in transmission systems. The change will be brought about by the availability of a new kind of electrical machinery (generators and motors) having weight and volume characteristics only 20-25% as large as currently available.
The development of superconducting machinery will affect not only the propulsion system but will also produce major changes in warship configuration.2 For example, the reduction gear, most of the propeller shafting, the need for controllable- and reversible-pitch propellers, and a significant portion of the air intake and uptake ductwork will be eliminated. The main propulsion gas turbines will no longer have to be in line with the propeller, thus introducing a degree of flexibility heretofore unattainable for high-powered warships. The whole power plant will probably be moved to the stern of the warship, freeing the amidships region—the most valuable space in the ship. Two typical installations, one for single-screw and another for twin-screw ship are shown in Figure 5. Flexibility of power distribution from one prime mover to more than one propeller will be another benefit leading to improved gas
2 Superconducting technology, even though known as a phenomenon 60 years ago, is just now coming into practical application. Certain metals, when cooled to very low temperatures, enter a new state of matter, and electrical resistance becomes zero. There were, however, a number of practical problems which needed to be solved. For example, it took 30 years until the now-used material Niobium became available to carry the required density of direct current in a large magnetic field without loss.
Detail design and construction of a 3,000-horsepower motor for laboratory and shipboard experimental evaluation by the Navy are now under way. This motor is a prototype intended to demonstrate the materials, design considerations, fabrication, and assembly approaches required for a full-size, 40,000-horsepower system. For the first time, it appears that electrical transmission systems will be attractive compared to the current mechanical reduction gears or state-of-the-art electrical machinery. A reduction gear for 40,000 horsepower per shaft weighs about 280,000 pounds, and an equivalent, state-of-the-art electric generator set is about 375,000 pounds. With superconducting technology applied to the generator and motor, the unit will weigh about 85,000 pounds, thus providing radically different ship configuration options.
Figure 3 Marine Gas Turbine Fuel Consumption Improvements
Figure 4 COGAS Propulsion Plant Configuration
turbine performance at cruise speeds and cutting down fuel consumption. The total gains from these changes will permit a significant reduction in ship s'2e for the same payload, speed, and endurance.
Manning!Automation: Since warships have a limited amount of space and habitability standards have increased substantially since World War II, every added man costs much more in increased ship size. Attempts to arrest the trend of increased manning have been successful in recent designs, but the number of cubic feet devoted per man has continued t0 grow. In addition to the effect of manning on ship acquisition cost, the need to reduce ship manning levels has been forced by rising manpower costs and decreased availability of qualified personnel. Nearly dO cents of every defense dollar are now spent for Payroll and related personnel expenses. Thus, the ,ssue is how to get people off warships and reduce the effect on ship-acquisition cost of those who must regain on board. The instinctive first reaction is to automate. One hears predictions of unmanned ships controlled by satellites. Some speak of peacetime versus wartime crew's or “maintenance by replacement, the opposite of repair on board. Unfortunately, there does not appear to be a simple solution.
Unmanned machinery spaces already exist in the U.S. Navy as well as in commercial ships and ships °f foreign navies. Automatically firing guns responsive to certain incoming target characteristics are also realized today by the Vulcan/Phalanx close-in-weap- °n system. In some cases, a ship’s bridge can be operated by one man. However, much of this outward aPpearance of automation is not truly automation. It provides more adequate information, allowing reroute and centralized activation capability which helps reduce manning but does not eliminate it.
The repair-by-replacement concept removed a few People from the recently commissioned Oliver Hazard ^errJ• but it was done at the cost of having to store ruuch larger, more expensive whole units on board either the ship or the tender. It also put penalties on ship size to assure that adequate room exists for removal of the larger units on board the ship, as compared with smaller parts necessary w'hen the repair- ln-place concept is practiced. The overall result can h<-‘ a higher fleet cost. As an example, imagine that uvery time your car had a major carburetor problem, che garage mechanic replaced the entire engine rather than just the carburetor. The mechanic would then Se°d the whole engine out to a special repair shop which would take the carburetor off and fix it.
To further complicate the problem of manning, "'atships are designed to withstand a certain amount
of damage in combat. This capability is possible because of the trained damage control parties which are stationed in key locations throughout the ship during general quarters. Unmanned ships would not be able to control such damage. The housekeeping chores on board a warship which is at sea for extended periods and subjected to the degrading effects of saltwater, ship motions, and vibrations also compound the warship manning problem.
However, under the circumstances just discussed, there is a certain validity to the argument, “Why invest in automation if it does not get people off the ship?” If cost and size reductions are to be achieved, radical new operating concepts need to be devised. One might be the use of crew members who don’t reside on board the warship but come aboard from support ships for the day by helicopter. These new methods would treat labor much like other consumable commodities that a warship requires. Without such radical new operating concepts, further major reduction in manning levels is not likely, no matter
how much automation is incorporated.
Combat System: Although the ship’s hull, propulsion plant, and manning are very important parts of a warship’s design, they are not the driving criteria for the ship’s existence. A ship is designed to put a particular collection of weapons and weapon-related systems out on the ocean where they are needed. To accomplish her mission, a warship must be able to detect ships, planes, and weapons and verify that they are indeed enemy targets. She must also be able to launch or fire appropriate weapons of her own at enemy targets and direct those weapons accurately.
The basic antisubmarine warfare (ASW) weapons are an acoustic torpedo, launched from either a ship or a helicopter, and a standoff antisubmarine rocket (ASROC) which can carry either a homing torpedo or a nuclear depth charge with a range of about 5 miles. In the newest surface warship, the Oliver Hazard Perry, the standoff rocket has been discarded in favor of helicopter delivery, providing greater range but at the cost of some loss of bad-weather capability.
However, the weapons are only the visible part of the ASW system. Much depends upon the sensors which, in the U.S. Navy, are predominantly very powerful active sonars. Recently, the Navy has begun to experiment with large towed passive arrays which will have even better performance—especially against noisy Soviet submarines. In addition, the helicopters flown from many ASW ships can sow fields of sonobuoys which can greatly extend the effective range of shipboard ASW sensors.
The Soviets appear to have applied their cruise missile technology to ASW weapon delivery in the SS-N-14, whereas the U.S. ASROC and submarine rockets (SUBROC) are ballistic weapons whose courses cannot be changed during flight. In the West, the Australian Ikara and the French Malafon use cruise missile technology to deliver a homing torpedo. Presumably, the Harpoon basic antiship missile offers the United States similar possibilities should a command-and-control link be developed.
U.S. naval antiair missile development began late in World War II and produced three major series: a large, long-range ramjet, Talos; a long-range, two- stage rocket, Terrier; and a short-to-medium-range, single-stage rocket, Tartar. Rocket fuel development has now brought Tartar well beyond the capabilities of early Terriers; in fact, the two programs have merged under the designation Standard. Future antiair missile ship construction is likely to be based on Standard-2, the missile component of the new Aegis system.
The new Aegis system attempts to overcome saturation attacks without requiring an enormous ship to carry it. Current missile-equipped ships are limited in the number of targets they can engage simultaneously because each missile requires the full attention of a guidance radar from launch to explosion. However, the newest missiles, Standard-2 and the airborne Phoenix, have autopilots. This means that they can be fired into the target area and only then need to be guided by a dedicated radar.
Such systems require tracking radars capable of following many missiles simultaneously so that the guidance signals can be directed properly at the right moment; a fast computer is required to choose that moment. These requirements are met by the Aegis system’s lightweight, phased-array radar SPY-1 and a computer which can fit into relatively small ships, thanks mainly to recent advances in solid-state electronics. These radars are expected to enter service with the DDG-47 class of destroyers in the early eighties and can be expected to remain in production through the late nineties.
As far as antisurface capabilities are concerned, the U.S. Navy has been relatively backward because of a lack of suitable targets, i.e., no serious potential enemy surface fleet. However, U.S. forces are beginning to receive Harpoon, an autonomous antiship weapon launchable from ships, submarines, and aircraft, with a range exceeding 40 miles. Harpoon has limited dimensions because it was designed for compatibility with existing launching systems, but the Navy is developing the much bigger, longer-ranged Tomahawk (more than 350 miles, 21-inch diameter) which will also be compatible with submarine torpedo tubes. The Tomahawk will also be built in a strategic version (cruise missile) with a thermonuclear warhead, a range of about 1,700 miles, and a high-precision, radar-mapping guidance system. If mounted on surface ships, the Tomahawk would force the Soviets to conduct the equivalent of anticarrier operations against all U.S. surface ships— possibly against all NATO surface ships. The Tomahawk missile and its successors will add a tremendous offensive capability to our future warships.
When it comes to defense against aircraft at long distances or against large antiship missiles launched from long-range, land-based aircraft such as the “Backfire,” the missile has no rival. Such effectiveness naturally assures its place on future warships. The question remains as to what means of missile stowing and launching will be provided in our future ships. In addition to the Mk 26/Mk 13 rail-type launchers on board current ships, recent and nearterm developments will provide additional means for launching the variety of missiles not in our current
H- S. inventory. The various types of launchers are shown in Figure 6.
The best launcher mix for future warships will depend on the ship class. On a PHM hydrofoil boat displacing 150 tons, the canister launcher is the only S('lution because of weight and space limitations. On tlle 3,500-ton FFG-7, other alternatives become possible. In general, ships with vertical launchers for Medium- to long-range missiles and above-deck launchers for short-range self-defense missiles offer an efficient mix that maximizes rate-of-fire, minimizes height and cost, and provides adequate redundancy. However, the most cost-effective solution may not create a fierce-looking ship.
To make a U.S. naval ship appear more warlike than she does would require that "the fierce-look factor be more heavily weighed than cost and effectiveness factors. Consequently, Soviet ships are expected to continue to appear heavily armed with many weapons of different types, while U.S. ships "*11 appear to have only a limited number of "eapons, creating the impression of lesser warfighting capability even though their potency will be substantially increased over that of warships in the fleet today.
An important visible and versatile warship weapon is the gun. Since before World War I, the traditional r<)le of the gun has been in long-range shooting against other ships and in ship-to-shore bombardment. After World War II, an increasing proportion
gunnery and gun fire control development was dieted toward antiaircraft defense. All three roles arc- expected to continue but with substantial improvements incorporated. Today’s inventory of modern naval guns consists of the 5-inch/54 and the 76-mm. variety. Two new developments are nearing completion, one larger caliber and one smaller—the 8'inch and the 20-mm. Vulcan/Phalanx. The small- caliber gun is designed as a last-ditch defense at ranges of one mile or less. This gun is tied to a Sophisticated radar which uses adaptive prediction Procedures to keep its lock on the incoming missile °r plane. In this role, the gun is expected to be on future warships unless high-energy lasers with rapid retargeting ability and virtually zero flight time prove to be so much more effective that they replace it.
Ongoing Navy and Department of Defense reSearch and development programs continue to pro- v‘de strong evidence that high-energy laser technol- °gy can be effectively employed as part of warship combat systems. Based on the results obtained from rhese programs, there are a number of laser and Pointer/tracker system options that are candidates for the development of an operational weapon configuration for the ship self-defense mission. Many people- considered larger caliber guns for warship use a thing of the past. Had the "smart ordnance” concept not been put into practice, they may well have been correct. However, borrowing from the technology of air-dropped guided munitions and missiles, the Navy adapted terminal guidance to the 8-inch projectile, thereby securing the gun’s future. Because the semiactive laser seeker was adapted from the Paveway bomb, the guided projectile has also become known as the Paveway. The resulting projectile program currently under way is expected to increase the effective range of the gun as much as 40% over that of the ballistic ammunition of today against both air and surface targets. Today, an even newer program has been started to further extend the range of the 8-inch guided projectile and eventually replace the Paveway. This new 8-inch round is expected to exhibit a fivefold increase in accuracy over the Paveway. Since the cost of such a sophisticated projectile will be only a fraction of the cost of a missile, and because we can talk about hundreds of reloads in one- ship instead of tens for missiles, it is expected that guns of large caliber up to 8-inch will be mounted on future warships and possibly even on smaller frigate-size warships.
VERTICAL CANISTER
In the past, most naval strategists preferred to place their faith in hard-kill weapon systems and looked upon electronic warfare with skepticism. Its importance was not fully appreciated. Since electronic countermeasures are designed to thwart and deceive the enemy, it is not possible to provide tangible evidence of their effectiveness except through the simulation of enemy missile attacks or during a real conflict. However, since the 1973 Mideast War, most navies have realized the degree of the current and future threat and have begun procuring electronic warfare systems to retrofit their ships. The U.S. Navy has been in the forefront in procuring the systems. Much of this effort has been put into the development of electronic surveillance systems. A typical advanced system includes equipment for the reception, analysis, and identification of radar signals and for the classification of threats on a priority basis. Other electronic warfare equipment which will definitely be on U.S. warships includes jamming devices and decoys.
Another feature of future surface warships will be organic air capability. Through the use of aircraft, a ship’s sphere of influence will be greatly expanded by an over-the-horizon target detection, classification, and engagement capability. The current air capability, which reached the fleet six years ago, is the light airborne multipurpose system (LAMPS) helicopter. LAMPS aircraft assist in screening operations, and they redetect, classify, and attack submerged submarines whose presence in the tactical area had initially been determined by some other means. With the availability of V/STOL aircraft within the next decade, it is expected that even more space and weight will be devoted to air capability on our future surface warships. It is also expected that, with the advent of remotely piloted vehicles, unmanned aircraft will be an integral feature as well.
Another expected change affecting the design of
Figure 7 XJnder 10,000-ton Warship of Early 21st Century
surface warships relates to their economical reconfiguration stemming from the need to keep up with technological advances of their weapon systems. To keep pace with this changing technology, a warship must go through periodic modernization efforts. Each of these efforts requires from 18 to 30 months to complete, and each warship is modernized several times during her lifetime. As a result, a ship is not available to carry out her mission for a significant percentage of her time in commission. This practice requires a larger number of ships just to keep the required size fleet available, not to mention the major tax dollar expenditures for labor and materials invested in the modernization task.
To cut these expenses, warship designs in the future are expected to allow for uncoupling the payload from the ship to facilitate rapid payload change by:
► Using standard-sized and configured weapon system stations on ships to allow for rapid exchange of weapon systems modules
► Sizing the distributive systems such as cables, pipes, and ducts and space for the generation components such as pumps, chillers, generators, and fans for future potential
► Extensive use of microprocessors as an integral part of the weapon module in lieu of the currently used centralized computer complex. A recent Navy laboratory study concluded that if all functions which relate only to a given subsystem could be physically located with that equipment (guns, missile launcher, radar, sonar, etc.), the reprogramming impact on a central computer at the time of conversion would be drastically reduced. With microprocessors, it is expected that this goal will be achieved.
► Another recent technological development which further enhances the objective of quick weapon changeover is provided by multiplexing, which allows multiple messages to be carried on the same cable by the use of either time or frequency division.
Figure 8 2,000-3,000-ton Warship of Early 21st Century
As a result of higher and higher demands on transmission capacity of data or voice communications and development of fiber optics, it is anticipated that the next step after multiplexing using coaxial cables will be the switch to fiber optics cabling systems. A simple pair of fibers is capable of carrying 2,000 simultaneous phone calls, a function which current state-of-the-art technology provides via a 3-inch diameter cable composed of many twisted pairs of copper wires.
The trend toward standard warship hulls capable °f reconfiguration can be seen already, even without 'rnplementation of the new technologies. The DD-963 has been redesigned as the DDG-47, the DD-963(AC), and the Iranian DD-993. All of these ships have a common basic ship configuration with only the Weapon/sensor suites changed substantially.
Summary: The potential future of hydrofoil, SES, and hybrid hull types was discussed earlier. Their application is expected to be mostly for special niissions where high speed on the ocean surface will be judged of great importance. The application of sWath is projected in the role of air-capable platforms and frigate-size combatants. Most of the adVances in individual subsystem technologies discussed will influence the characteristics of all these new ship types. These advances will also influence che characteristics of the conventional displacement Warship. In spite of her very limited future improvement potential from speed and seakeeping viewpoints, the conventional displacement warship will probably still dominate the surface warship scene ln the early 21st century (Figures 7 and 8). But tnajor improvements and radical departures from current practices are expected in most of the elements which provide the ship’s propulsion and combat
capabilities.
Compared with the DD-963 and the FFG-7, even the °utward appearances of the warships of the near future are expected to be different. Some of the features which will probably make the most difference:
^ A greater portion of the ship will be dedicated to av>ation capability.
^ The propulsion system will not occupy prime aruidships space but will be placed much farther aft. Instead of the usual series arrangement of propulsion Prime movers with the propellers, they will be vertically stacked and moved toward the stern.
^ The conventional stacks of fossil-fuel ships will disappear. Intakes and exhausts will be much shorter and will not interfere with the topside antenna arrangements.
^ No significant reductions are expected in the weight now devoted to a ship’s structure unless aluminum proves to be an economically and militarily viable hull material for warships.
\ The typical rail launchers will make room for more visible, single-purpose missile launchers as well as for the less visible vertical launcher/magazines.
► Close-in weapon systems will be installed, including the high-energy-laser gun and the Vulcan/ Phalanx systems.
► Three-dimensional, stationary-face, phased-array radars will take over the functions of the typical rotating antennas.
► The combat information center and other key combatant functions will be moved down into the hull from the superstructure.
► More true automation will be introduced, along with possible radical changes in the use of the people component of warships.
► Electronic warfare will take on increased significance and more cost, space, and weight will be devoted to it.
► Large-caliber guns (8-inch) will not disappear. Instead they will be introduced into even smaller warships than before.
► We will build two or three standard basic ship configurations and be able to reconfigure them for different missions within a couple of months instead of a year or two.
In spite of the fact that this article focuses on technological advances, we must remember that the mere existence of advanced technology is by no means assurance that it will be incorporated into new warships. The problem of adopting innovations by large bureaucracies such as the Navy is a complex one. Thus, which innovations will be adopted into future surface warships will be as much a bureaucratic/sociological issue as a technological one.
a Dr. Leopold is technical director for ship design at the Naval Ship Engineering Center. In this senior civilian position, he is responsible for the design of all surface ships and submarines for the U.S. Navy. Before beginning work for the Navy, he had a ten-year career in private industry. His last such position was director of ship engineering for Litton Industries. In this role he was in charge of the designs of the Spruance (DD-963)-class destroyer and the Tarawa (LHA-l)-class amphibious assault ship (general purpose). He holds four degrees from M.I.T., including a Ph.D. in ocean engineering. He also has an M.B.A. from George Washington University. Dr. Leopold has published numerous technical articles for journals in the United States and abroad and is the editor and a principal author of a forthcoming book titled Naval Surface Ship Design, to be published this year. He has written a number of articles for the Proceedings. His most recent was "Designing the Next Aircraft Carriers” in December 1977.