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The Fast Task Force Escorts

The Genesis of the Farragut Class Guided Missile Frigates

Reprinted by permission from Norman Friedman, U.S. Destroyers: An Illustrated Design History, copyright 1982 (Naval Institute Press: Annapolis, MD)

The Fast Task Force Escorts

The Initial Concept

From the middle of World War II onward, the fast carrier task force has been the principal offensive arm of the U. S. Navy, and screening such forces has been a principal theme of destroyer operation and development. Generally, the threat to the carrier task force was air attack, which explains the emphasis on air defense in the Mitscher and Forrest Sherman designs. Fast task force air defense was the primary task of one of the three categories the Schindler Committee proposed for future development in May 1954. The new ship would be a logical development of the Mitscher concept, and like the earlier ship, would probably be designated DL (“Destroyer Leader”). In June, the SCB (Ship Characteristics Board) proposed instead the term “frigate,” which was adopted. The new fast escorts would be comparable to the frigates of the eighteenth century or, perhaps, to the French contretorpilleurs of the twentieth. They were not intended individually to lead lesser ships in a screen, since they would constitute the screen itself. The Schindler Committee envisaged them primarily as AAW (Anti-Aircraft Warfare) ships “to provide limited defense against submarine and surface attack…to provide air control facilities…(and, in every fourth unit) to provide command facilities for screen commander and staff.”

Thus began the construction of a series of specialized fast task force escorts, all armed with anti-aircraft missiles (and thus designated DLG rather than DL) and all comparable in size to the light cruisers of former days. The U. S. Navy, indeed, was nearly unique in designating such ships as frigates; in most navies the Royal Navy’s World War II revival of the frigate category for large ASW (Anti-Submarine Warfare) ships (comparable to destroyer escorts) was the rule. Thus for many years there was the anomaly of Soviet “cruisers” substantially smaller than U. S. DL-“frigates” and of foreign “frigates” by no means comparable to their U. S. counterparts. Finally, on 30 June 1975 the U. S. categories were revised to reflect foreign practice. The DLs were redesignated as missile cruisers (CG or CGN, depending upon their power plants) or missile destroyers (DDG, for the smaller ones). The former “ocean escorts” or “destroyer escorts” were redesignated frigates (FF, FFG).

Given the need for a heavy anti-aircraft screen to protect the fast attack carriers, the only important issue was the pace at which guns would give way to the missile systems already under crash development. At first the latter appeared to require cruiser hulls, such as the Boston, to support them; for example, it was only in March 1955 that the operational requirement for Terrier was formally revised to include suitability for mounting aboard destroyers and frigates. Reportedly the key figure in the very rapid transformation of the fleet in the direction of surface-to-air missiles was Chief of Naval Operations Arleigh Burke, under whose tenure it occurred. Unlike his predecessors, he had a strong surface (destroyer) background and well understood the needs and potentials of the destroyer force. He also had the benefit of long experience within BuOrd (Bureau of Ordnance), where the new missile technology was being developed, and he had the advantage of a relatively long tenure during which he could put his concept into practice. Although Admiral Burke is best known for his support of the Polaris system developments, the introduction of surface-to-air missiles on a very large scale seems, in retrospect, to have been a major achievement. It was, moreover, conducted very largely on faith, as systems moved from the drawing board almost directly into mass production. This was particularly true of Tartar. Such procedures were not indications of irresponsibility, but rather of the magnitude of the air threat as it was perceived in the late 1950s.

The missile program involved very large numbers of new ships. For example, as of September 1956, the FY 56-62 plan for missile ship construction included two CG(N)s in FY 57 and one more in FY 60; a total of 51 DLGs (6 in FY 56, 5 in FY 57, 8 in FY 58, 9 in FY 59, 8 each in FY 60 and 61, 7 in FY 62); and 50 DDGs (8 each in FY 57 and 58, 10 in FY 60 and 61, 14 in FY 62) plus missile conversions: 8 CLGs (1 in FY 56, 5 in FY 57, 2 in FY 58) and four CAGs (3 in FY 58, 1 in FY 59). Other objectives included the construction of one nuclear carrier annually from FY 58 onward and a program of missile submarine construction. Beyond the experimental Gyatt, no destroyer missile conversions were envisaged: fast task force escort duty needed something far more potent than a Gearing. Admiral Burke was well aware of what all of this construction would cost, but he was also well aware of the emerging air threat his fleet faced, and of the need to maintain the very powerful carrier strike forces that existed. In the fall of 1956 there was, as yet, no Polaris program to drain funds from what would later be perceived as the “general purpose” arm of the Navy: the fast carriers were still the strategic as well as the limited-war striking force.

In 1954 the missiles still seemed far in the future, and the Schindler Committee asked for four 5-in/54s on a Mitscher hull, controlled by two directors. ASW capability was to be minimal, consisting only of Mk 32 lightweight torpedoes or their equivalent. Weapon A and even Hedgehog were specifically excluded. On the other hand, the new ship was to have excellent submarine detection equipment with which to warn the task force to evade: SQS-4 with dual MCC (Maintenance of Close Contact). A powerful air search radar (SPS-12) and the height finder (SPS-8) required for fighter control were also specified. “Hemispherical Air Search,” which would have been important only for a ship operating near land, was specifically excluded, but effective picket duties with the task force required the new ship to have terminal facilities for airborne early warning aircraft. To keep up with its charges, the escort was to have “maximum seakeeping qualities,” a trial speed of 34 knots, and an endurance of 5,500 nm at 20 knots.

Speed was particularly important, and compromises such as those accepted in the design of the Forrest Shermans had to be avoided. For example, a June 1954 conference on frigate design decreed that it must be at least 2 knots faster than the new CVA: “we must wait for final approval of CVA characteristics before setting the speed for this ship.” Rear Admiral Mendenhall, chairman of the SCB, wanted to know what it would take to attain 38 knots; on a quick-and-dirty basis the BuShips (Bureau of Ships) representatives thought a 530-foot, 80,000-shp ship or a 490-foot, 100,000-shp ship would do-and new studies of both cases were ordered. The admiral also wanted to require a radius of 1,300 nm at 35 knots, which suggests a desire for the fast task force to be able to operate at top speed for extended periods. In fact, of course, as in previous fast-destroyer designs, more modest goals had to be adopted in the end.

The first tentative characteristics (17 May 1954) asked even more: a trial speed of 35 knots, a pair of quadruple 40-mm AA guns (which would soon be twin 3-in/50s), as well as an ASW torpedo launching system with six Mk 32 torpedoes, a depth-charge rack (12 charges), and six depth-charge throwers. A quintuple bank of antiship torpedo tubes would be a useful means of discouraging surface attack on the task force; Samar was still well remembered after a decade. By August the thrust of the design, now designated SCB 129, had been formalized: “A predominantly anti-aircraft ship with radar picket capabilities is desired. The capability of sinking submarines is subordinate to the stressed features.” The AA role was taken to require “an exposed air defense control station on a level above the Pilot House. Particular attention shall be given in the design to as near hemispherical visibility as practicable…”

The torpedo pendulum swung towards long-range ASW homing torpedoes, and the quintuple mount was to be capable of launching them. There were to be no reloads, but 44 depth charges were specified. By September the side depth-charge throwers had been displaced by two fixed Hedgehogs with two sets of charges each in ready stowage and eight more (each) in a magazine. This was beginning to be a serious ASW battery.

This was a lot to cram into a 3,600-ton destroyer hull. A footnote, “by installing SQS-4 long-range detection sonar on a CLAA Class [6,000 tons plus] will give similar capabilities,” suggests that the framers of these draft characteristics knew that they were pushing towards a cruiser. The single rapid-fire 5-in/54 was more than equal in firepower to a twin 5-in/38; and in weight, four of the former were equal to more than five of the latter. If electrical loads-including those required for the radar-were added in, it would seem that the main battery of a World War II AA cruiser, twelve 5-in/38s, was being demanded on a hull half the size.

The ship grew as preliminary studies progressed. In August she was described as 5,000 tons fully loaded, 480 feet long; in September the length was 495 feet; and in October 510 feet (and 5,300 tons). Efforts were already being made to prune back weight by eliminating the superfiring feature of No. 2 and 3 guns, and a weight study was made of eight fixed tubes as a substitute for the quintuple rotating mount. The former had the disadvantage of greater weight and length required (56 feet vs. 25) but on the other hand a fixed tube, Mk 25, was already in existence whereas a trainable one would require considerable design time. Other points in favor of the fixed tubes were that they could accommodate reloads and that torpedoes in them (and thus inside a deckhouse) could be serviced and heated-the latter particularly desirable in the cold North Atlantic. However, the tubes were-at best-secondary in an AAW ship, and the quintuple arrangement, which had lower impact on the design as a whole, prevailed.

At the end of September 1954, a BuShips comparison sheet showed that the characteristics, including quintuple torpedo tubes, could be achieved on a light displacement of 3,569 tons (vice 3,384 for DL 2; 4,761 tons on trial vice 4,441; 5,101 full load vice 4,726; length would be increased to 495 feet from the 476 feet of DL 2). If both the torpedo tubes and the two twin 3-in/50s were sacrificed, the main armament could be accommodated on a DL hull (which really says something about the weights of Weapon A and the 3-in/70) on a light displacement of 3,435 tons (4,516 on trial, 4,832 full load). In both cases the endurance at 20 knots was to be increased from 4,500 to 5,000 miles, and the trial speed maintained above 35 knots. As compared to a first cost of $51.5 million for DL 2 ($39 million for follow-on ships), the full SCB 129 was expected to cost $54.5 ($42) million and the restricted version $53 ($40.5) million. These are remarkably low figures in view of the spectacular combination of armament and performance demanded. They were practical partly because of improvements in machinery weight (80,000 shp in SCB 129 was to cost [wet] 1,275 tons, where 75,000 had cost [in CL 51, 1938] 1,335, and in fact DL 2 cost 1,114), and because destroyer rather than cruiser practice in hull construction was adopted. A new structural feature was the use of HY 80 steel in place of the STS (Special Treatment Steel) formerly used over the amidships sections of destroyers and DLs. The newer steel was regarded as considerably tougher than STS, nearly as splinter-proof, and very weldable; it was “highly desirable for the high speed rough water service for which the vessel is intended.”

The ship continued to grow. A June 1955 report on the Preliminary Design listed a full load displacement of 5,249 tons and a power requirement of 85,000 shp for a speed slightly over 35 knots. The designers reported that growth resulted from “increased armament space requirements, increased fuel for endurance, and the use of machinery more conservative than the DL 2 class.” To the quintuple TT had been added provisions for two reloads-but now the pendulum was swinging against the long ASW torpedo, and only anti-surface ship weapons (Mk 16) were to be carried.

A paradoxical element of the design was the great attention paid to sonar performance in a ship specifically not intended for submarine-killings. The hull lines were redrawn to allow for a deeper draft and a lower prismatic coefficient than in DL 2 (almost as low, in fact, as DL 1). Sonar performance in the Mitschers had been considered unsatisfactory, not least because of interference between the scanning sonar (QHBa) and the attack sonar SQG-1, which were mounted in tandem in separate domes. The advent of Dual MCC (introduced in DD 931, see Chapter 11) permitted the use of a single dome, which could be mounted further forward so as to avoid bubbles entrained by the stem. A more radical solution would be a bow dome. Lines with such a dome were worked out, and the final recommendation of Preliminary Design was that one ship be built with a bow dome and the others with more conventional installations to provide comparative data. Model tests suggested that whereas the conventional dome added about 4.7 percent to bare hull resistance at 20 knots and 1.3 percent at 35, the bow dome, acting as a small bulbous bow, reduced resistance by 10 and 5 percent at these speeds. There were also acoustic advantages. Bubbling, a serious source of noise in conventional domes at 20 knots-and it must be kept in mind that the fast escort would do her listening at high speed-would be abolished, although there would be more splash noise. There was some fear that the problem of the sonar emerging in rough weather would be aggravated; but on the other hand the bottom of the new dome would be rounded to take the impact of slamming back into the water.

A more conventional installation was also considered, a special rounded shape being adopted to reduce flow separation and vorticity on the after part of the dome; these effects were responsible for severe panting stresses on conventional domes. The dome dimensions suggest just what a “large” sonar meant in 1955 – 100 inches long, 5 ft. 4 in. deep. By way of contrast, SQS-23, which became standard on many FRAM destroyers only four years later, was the size of a small motor boat.

Ultimately SCB 129 and its close relative, SCB 142, had hull-mounted sonars; the bow mounting was first incorporated in the frigates of FY 58 program (SCB 172, DLG 16 class).

The Terrier Missile

Even though Terrier was not officially suitable for destroyer installation, it was expected almost from the first that it would supplant the rapid-fire gun on the fast task force escort. In preparation for DLG installation, Terrier was tested at sea aboard a specially modified Gearing Class destroyer, the USS Gyatt, converted at the Boston Naval Shipyard under the FY 56 program. Conversion entailed the replacement of the No. 3 5-inch gun mount and the after 40-mm guns by a twin Terrier launcher with 14 missiles; guidance was furnished by a modified Mk 25 radar in the gun fire control system, and automatic Denny-Brown stabilizers were fitted. At the same time the remaining 40-mm guns were replaced by 3-in/50s, and the quintuple torpedo tubes landed as weight compensation. This austere conversion, first proposed in the spring of 1954, was not intended as a prototype for further efforts. However, it inspired the destroyer force to demand Terrier rather than the new (and shorter-range) Tartar that was under development to replace the standard twin 5-in/38 or single 5-in/54 mount, and for a time repeat Gyatts were proposed in the Shipbuilding Plan. The Gyatt herself became DDG 1, reverting to her old destroyer designation in 1962 when the missiles were removed and she became a test ship with the Operational Test and Evaluation Force.

Given the availability of Terrier, some proposed that SCB 129 include missiles; instead, a new gun-and-missile frigate was designed in parallel, as SCB 142. Characteristics were issued in January 1955. She would duplicate the SCB 129 as far as possible, except for armament.

Some members of the SCB were desirous of installing guided missile launching systems forward and aft on the DLG, but two systems of the size contemplated could not be accommodated on the DL hull. In addition, the full Board was not prepared to recommend an all-missile ship and the half Terrier-half gun armament was accepted. [Design report, July, 1955]

A wide variety of schemes were prepared. For example, it appeared that a twin Terrier launcher could replace either the No. 3 or No. 4 5-in/54 gun mount, with a magazine for 24 Terriers nearby; missile guidance would be rudimentary, via a modified fire control radar on a Mk 68 director. An alternative “maximum Terrier installation” called for the removal of all guns, even the two twin 3-in/50s. Twin launchers fore and aft would be served by 48-missile magazines, and fire control would be via big SPQ-5 radars - one atop the bridge and one abaft the SPS-8 height finder required for fighter control. The quintuple anti-surface-ship torpedo tubes and the ASW battery were to be retained in any case.

The reality was more complex. In order to handle two simultaneous intercepts, the missile frigate required a pair of SPQ-5 which, with one twin launcher, replaced both after 5-inch guns, as well as the space formerly reserved for the big stabilized height-finder; however, the air control role was retained in the characteristics. Moreover, missile operation required a three-dimensional radar to intermediate between the long-range search set (SPS-37) and the guidance radars. In the new frigate this was the SPS-39, the first of the frequency-scanned pencil-beam sets, mounted on the foremast; a quadrupod lattice main mast carried SPS-37 and the TACAN required for effective fighter control.

The missiles were carried in a 40-round Mk 10 launching system, consisting of two horizontal rotating rings from which rounds were carried to a “finning” space whence they were rammed onto the twin arms of the launcher proper. Excluding missiles and fluids, the Mk 10 Mod 0 of the new missile frigate weighed 123.2 tons; with forty 3,000-lb Terriers and associated fluids, this figure rose to 178.7 tons. By way of comparison, a single 5-in/54 without ammunition weighed about 57.6 tons, so that two guns would weigh only about 115.2. Their 1,200 rounds of 5-inch ammunition would add about 54 tons, comparable to the net weight of the missiles. However, the slightly heavier missile system would involve more weight very high in the ship, and in addition the missile system required considerable electrical power, not least to operate the elaborate magazine system.

The missile system included a weapons control center forward on the 02 level below the CIC; a missile plotting room combined with the after IC and gyro room on the second platform deck aft. Missile transfer at sea and strikedown areas were provided near the missile magazine on the 01 level aft. The main deckhouse was extended 14 feet farther aft than in the original all-gun design, but 56 feet of its length was taken up with the missile-handling area, including the finning space. Thus there was a general shortage of internal volume: SCB 142 was among the first of the modern “volume critical” ships. Habitability standards had to be relaxed, as compared with those of the DL, and even so the torpedo work shop and internal stowage of two reload torpedoes had to be eliminated in favor of a mess space. The two reloads (later eliminated when the long torpedo tubes were given up) were to be stowed outboard of the deckhouse with checkout access openings and heat circulating from within the deckhouse. Forward, the superstructure generally followed that of the DL except for the weapons control space.

Radars and the missiles high in the ship both increased weight and decreased stability. Some Preliminary Design figures (July 1955) give an idea of the evolution of the frigates (figures in parentheses are metacentric heights):

Condition Light Trials Full Load
SCB 5, 1948 3,377 (3.03) 3,814 (2.98) 3,893 (2.67)
SCB 129 4,472 (4.39) 4,905 (5.16) 4,970 (4.81)
SCB 142 4,758 (4.88) 5,249 (5.89) 5,314 (5.53)

These are all design figures, hence not entirely representative of the ships as built. SCB 5, which became DD 927/DL 2, has been included to give some feeling for the growth of the frigates into the small cruiser category. Later additions to the DLG increased her displacement further: DLG 9 was completed at a light displacement of 4,186 tons, and a full load of 5,605.0.

For FY 56 the Navy was given six frigates; Admiral Carney, the CNO, personally decided that three (DLG 9-11) would be half-gun SCB 142s. Three SCB 129s (DL 6-8) were insurance against the possible failure of the Terrier; but the missile was accepted for fleet use, and all were switched to the missile design during 1956. Four more of this Farragut class were authorized under the FY 57 program.

Anti-Submarine Warfare

Meanwhile major changes were made in the ASW battery. During 1956 the torpedo pendulum swung violently away from the long-range types. For many years, BuOrd had been trying to adapt the very powerful Mk 16 submarine torpedo for surface use; indeed, the quintuple tube had been included in the new DLs with this weapon in mind. Finally the bureau had to admit its failures (memo, Chief of BuOrd to CNO, 17 July 1956); worse, the new tube it had developed was too short to take the Mk 15 torpedo standard within the destroyer fleet. The Mk 37 ASW torpedo, which would fit the new tube, was considered worthless as an antiship weapon; and

…the advent of such high-priority programs as ASROC and Lulu [a nuclear depth charge], the urgent necessity to develop suitable armament for modern submarines, and the continuing heavy emphasis upon guided missiles have made it impossible to budget adequately for an effective long-range surface-to-surface torpedo.

In any case,

…in the light of current tactics it is felt that the use of long-range anti-surface ship torpedoes will be remote…in view of the extreme submarine threat existing, it is considered that the A/S phase should be emphasized.

A short-range ASW torpedo in conjunction with a standoff weapon such as RAT or ASROC would be better; BuOrd suggested the former for the new DLG. It would require a special launcher.

The lightweight Mk 32 torpedo, which had been intended for launching from simple dropping gear, was itself discarded in favor of the more effective Mk 43, which required a special (Mk 32) triple launcher. The short torpedo tubes now (1957) replaced dropping gear and also the fixed Hedgehogs originally specified.

Thus far, considerable development in ASW weapons had little impact on the primarily AAW character of SCB 142. ASROC was another matter, as it required for its control the very large new SQS-23 sonar. The size of this device was a direct consequence of the need to pass to lower frequencies in order to achieve “a detection range of at least 10,000 yards.” The SCB began to consider the deployment of ASROC in March, 1957. Quite clearly, all the destroyers and frigates of FY 58 (SCB 155 and SCB 172-see below) should have ASROC. What of DLG 6? The units of this class might be completed before ASROC and SQS-23 were available in any numbers; moreover, to buy ASROC for these ships would mean the sacrifice of the No. 2 5-inch gun forward-and a retreat from the predominantly AAW character of the frigate.

The advantages of ASROC, even compared to RAT, were such that there could be little question of its adoption. Indeed, it was suggested that without ASROC the fleet would have very little chance of killing fast submarines in the numbers the Soviets would soon have; moreover, it was precisely those fast submarines that would threaten the fast carrier task force. The cost of the back-fit would be a single 5-inch gun and the adoption of the new (and massive) SQS-23 sonar, at a cost of about $2 million per ship. A hull dome rather than a bow dome was chosen because it would permit the program to proceed much faster, as BuShips was already familiar with ship characteristics with hull-mounted sonars, whereas the bow dome presented entirely new problems due to the large bulge on the bow that was expected greatly to affect shiphandling characteristics. A similar decision was taken with respect to the DDGs then under construction; FY 60 and 61 DDGs, however, incorporated a bow sonar. ASROC also required additional electrical power and the substitution of a new Mk 111 fire control system for the Mk 105 associated with the earlier underwater weapons. The increased electrical load in turn increased fuel consumption, and thus somewhat reduced endurance-a reduction more than balanced, in the case of some of the DDGs, by improved hull performance due to the bow bulge of their sonars. The DLGs derived no such benefit, however.

Delays in the ASROC program are reflected in the completion of the first few frigates with neither gun nor ASROC in the No. 2 position; however, all did receive the ASROC “pepperbox” there in the end.

Photo of a nest of newly commissioned DLGs. Note that the USS Coontz (DLG 9) has not yet had her ASROC launcher installed. Courtesy of Brian N. Kroenung II (www.navsource.org) One might reasonably argue that the 1956/57 decision to mount ASROC in the missile frigates-the later SCB 172 project included it from the first-constituted an admission that fast nuclear submarines would ultimately be able to attack the fast task forces; certainly, American experience of the period suggested as much. Although air/missile attack was clearly still the dominant threat, something beyond mere warning of the presence of a submarine was needed. Another factor must have been the inability of the DDEs to keep up with the postwar carriers, which in 1956 were only beginning to enter service-but would dominate the carrier force by the late sixties when the new frigates would be in service.

Reprinted by permission from Norman Friedman, U.S. Destroyers: An Illustrated Design History, copyright 1982 (Naval Institute Press: Annapolis, MD)