Knox-class frigate

Knox-class frigate USS Robert E. Peary (FF-1073) and the skyline of San Francisco in the background
Class overview
Builders:	Todd Shipyard, Seattle and San Pedro Lockheed Shipbuilding and Construction Company Avondale Shipyard
Operators:	United States Navy  Republic of China Navy  Egyptian Navy  Hellenic Navy  Mexican Navy  Royal Thai Navy  Turkish Navy
Preceded by:	Garcia-class frigate / Brooke-class frigate
Succeeded by:	Oliver Hazard Perry-class frigate
Built:	1965–1974
In commission:	1969–1994 (USN)
Completed:	46
Retired:	46 (USN)
General characteristics
Type:	Frigate
Displacement:	4,260 tons (full load)
Length:	438 ft (134 m)
Beam:	46 ft 9 in (14.25 m)
Draft:	24 ft 9 in (7.54 m)
Propulsion:	1 shaft, one Westinghouse steam turbine, 2 V2M boilers. total 35,000 shp (maximum)
Speed:	over 27 knots (50 km/h)
Complement:	17 officers, 240 enlisted
Sensors and processing systems:	AN/SPS-10 Surface Search Radar AN/SPS-40 Air Search Radar AN/SPS-67 Surface Search Radar AN/SQS-26 Sonar AN/SQR-18 Towed array sonar system AN/SPG-53 Mk68 Gun Fire Control System
Armament:	one Mk-16 8 cell missile launcher for ASROC and Harpoon missiles one Mk-42 5-inch/54 caliber gun Mark 46 torpedoes from two dual tube launchers) RIM-7 Sea Sparrow (BPDMS) or Phalanx CIWS
Aircraft carried:	One SH-2 Seasprite (LAMPS I) helicopter

Knox-class frigates were United States Navy warships, originally laid down as ocean escorts (formerly called destroyer escorts), but were all redesignated as frigates on 30 June 1975 in the USN 1975 ship reclassification and their hull designation changed from DE to FF.

A sub-class of the Knox class was built, commonly referred to as the Hewes class. The primary differences were slightly different arrangement of the "Officer's Country" staterooms with additional staterooms in the 01 level instead of the open deck between the boat decks. The stateroom on the port side under the bridge was designated as a "flag" stateroom, with the additional staterooms for flag staff when serving as a flagship.

History

The 46 ships of the Knox class were the largest, last and most numerous of the US Navy’s second-generation ASW escorts. The lead ship of the class was the USS Knox (FF-1052), laid down 5 October 1965 and commissioned 12 April 1969, at Todd Shipyards in Seattle. Planned as the follow-on to the twin 5-inch gun armed Garcia-class frigates and the Tartar missile-equipped Brooke-class frigates, their initial design incorporated the prior classes’ pressure-fired boilers (the design later was changed to conventional 1,200 psi (8,300 kPa) boilers) in a similar-sized hull designed around the massive bow-mounted AN/SQS-26 sonar.

Ten ships were authorized in FY 1964, sixteen in 1965 and ten each for FYs 1966, ’67 and ’68; six were canceled in 1968 and four more in 1969. They were built in four different shipyards and were originally commissioned as destroyer escorts (DEs) 1052–1097 in 1969–1974, they were redesignated as frigates (FF) on 30 June 1975.

In February 1972, after encountering a severe Nor'Easter off Cape Hatteras, the U.S.S. Trippe (1075) suffered major damage to its ASROC missile launcher, which was ripped off its mounts. The Bureau of Ships ordered all of the Knox class to have a retrofit "hurricane bow" which heighted the bow section to prevent burrowing into on-coming seas and to protect the forecastle armament.

The Knox class was the Navy’s last destroyer-type design with a steam turbine powerplant.

Due to their unequal comparison to destroyers then in service (large size with low speed and a single screw and 5 inch gun), they became known to a generation of destroyermen as “McNamara’s Folly.”^[1]

These ships were retired from the US Navy at the end of the Cold War due to a declining need for an advanced ASW capability. By 1994 all ships of this class had been retired from the US Navy, although some remain in service with foreign nations such as Egypt, Taiwan, Thailand, and Mexico.

Description

Aerial view of Knox-class frigate USS McCandless (FF-1084)

Overhead view of Knox-class frigate USS Fanning (FF-1076)

These ships were designed primarily as antisubmarine warfare (ASW) platforms. They each had AN/SQS-26 hull-mounted sonar manufactured by General Electric and capable of active echo ranging in the 3.2 kHz range. The active modes of operation included omni-directional, phased directional, bottom bounce, and convergence zone. The battle displays included A and B scans. There was also a "Unit 31" chart readout display capable of long-distance passive detection, often well beyond the ranges capable of the surface search radar. The frigates were also equipped with an AN/AQS-35V Independent Variable Depth Sonar (IVDS) manufactured by EDO Corporation of College Point, NY, operating actively in the 13 kHz range with dual Planned Position Indicator (PPI) battle displays. The IVDS' sonar transducers were packaged within a 2 ton fiberglass-enclosed "fish" containing the sonar array and a gyro-compass/sensor package launched by the massive 13V Hoist from a stern compartment, located just beneath the main deck, to depths of up to 600 feet (180 m). The IVDS could take advantage of water layer temperature conditions in close-range (less than 20,000 yards (18,290 m) submarine detection, tracking and fire-control.

At 4,200 metric tons (4,130 tons), with a length of 438 feet (133.5 metres) and a beam of 47 feet (14.3 m), they are driven by a single screw geared turbine developing 35,000 shaft horsepower (26 MW), giving them a speed of 27 knots (50 km/h). The steam plant for these ships consists of two Combustion Engineering or Babcock & Wilcox "D" type boilers, each equipped with a high-pressure (supercharger) forced draught air supply system, allowing a plant working pressure of 1,200 psi and 1000 °F superheat.^[2]

The Knox Class ships were severely hampered by their single screw design and excessive displacement, and were not effective ASW platforms. Whilst their Towed Array Sonar was capable of submarine detection at certain depths and ranges, the ships themselves were basically incapable of combating a modern submarine target, which would be considerably more maneuverable than the single screw Knox. Their inabilities in this department were well known throughout the upper echelons of the United States Navy, and almost all of its contemporaries, leading eventually to the withdrawal of the entire class. In exercises the British VDS equipped 'Leander Class' frigates, (of 2000 tonnes less displacement and 4 knots more speed, plus twin screw maneuverability) frequently out-performed Knox Class ships, on both detection and successful prosecution of ASW targets.

They were equipped with one 5 in (127 mm) 54 caliber Mark 42 gun forward, an ASROC abaft the gun and forward of the bridge. Since they were single purpose platforms their surface defense capability was nominal; however they did mount Harpoon missiles and Mk-44/46 torpedoes. The aft weapons point was originally outfitted with Mk 25 basic point defense missile systems (BPDMS) for launching Sea Sparrow missiles. These were eventually refitted with a 20 millimetre Phalanx CIWS. They were equipped with a helicopter hangar aft.

Baleares class

Five modified ships were built in Spain for the Spanish Navy as the Baleares class frigates.

Chi Yang class

Chi Yang class FFG-932

In the 1990s the US agreed to transfer 8 Knox class frigates to the Republic of China Navy (ROCN). The ROCN planned to upgrade these ships with new air defense, anti-submarine, and electronic warfare capabilities, including new radar, towed active sonar, CIWS guns, VL air defense missiles, active/passive electronic warfare systems, etc. However, due to budget considerations and the acquisition of newer ships, only a few upgrades were implemented. These frigates were renamed the Chi Yang class and assigned to the ROCN 168 Patrol Squadron.^[3]

By 2005 the ROCN had removed several systems from the retired Gearing class upgraded World War II-vintage destroyers and transferred them to the Chi Yang class FFG. These systems include SM-1MR Standard missile in box launchers, H-930 modular combat system, and DA-08 air/surface search radar. Each Chi Yang class frigate has 10 SM-1 missiles installed in two forward twin box launchers on top of the helicopter hangar, and two triple box launchers installed between the stack and the hangar, pointing to port and starboard.^[4]

The anti-submarine capability of the Chi Yang class FFG is provided by its SQS-26 bow-mounted sonar, SQS-35(v) VDS, SQR-18(v)1 passive TAS, MD500 ASW helicopter, Mk-16 8-cell Harpoon/ASROC box launcher, and 4 x Mk46 324 mm torpedoes. While on ASW patrol, the frigate will carry 2 x Harpoon SSMs and 6 x ASROCs in its Mk-16 box launcher.^[5]

These ships will be upgraded with Hsiung Feng III missiles.^[6]

Units

References

• Prézelin, Bernard and A.D. Baker III (editors). The Naval Institute Guide to Combat Fleets of the World 1990/91:Their Ships, Aircraft and Armament. Annapolis, Maryland, USA:Naval Institute Press, 1990. ISBN 0-8721-250-8.

External links

Wikimedia Commons has media related to Knox class frigates.

• Knox-class frigates at Destroyer History Foundation
• Global Security
• Federation of American Scientists
• USS Brewton FF-1086 Home Page

v t e Knox-class frigates  United States Navy Knox Roark Gray Hepburn Connole Rathburne Meyerkord W. S. Sims Lang Patterson Whipple Reasoner Lockwood Stein Marvin Shields Francis Hammond Vreeland Bagley Downes Badger Blakely Robert E. Peary Harold E. Holt Trippe Fanning Ouellet Joseph Hewes Bowen Paul Aylwin Elmer Montgomery Cook McCandless Donald B. Beary Brewton Kirk Barbey Jesse L. Brown Ainsworth Miller Thomas C. Hart Capodanno Pharris Truett Valdez Moinester   Other operators  Republic of China Navy Chih Yang Fen Yang Fong Yang Hai Yang Hwai Yang Ki Yang Lan Yang Ni Yang  Egyptian Navy Damiyat Rasheed  Hellenic Navy Ipiros Μacedonia Thraki  Mexican Navy Ignacio Allande Guadalupe Victoria Mariano Abasolo Almirante Francisco Javier Mina  Royal Thai Navy Phuttaloetla Naphalai Phutthayotfa Chulalok  Turkish Navy Adatepe Akdeniz Ege Karadeniz Kocatepe Mauvenet Trakya Zafer Preceded by: Garcia class Followed by: Oliver Hazard Perry class List of frigates of the United States Navy