Grumman S-2 Tracker (Aircraft)

S-2 Tracker

An S-2E from VS-41 ready for launching from the USS Bennington (CV-20)
Role	ASW aircraft
Manufacturer	Grumman
First flight	4 December 1952
Introduction	February 1954
Retired	1976, USN
Status	Active service in Argentine Naval Aviation
Primary users	United States Navy (historical) Royal Canadian Navy (historical) Royal Australian Navy (historical) Japan Maritime Self-Defense Force (historical)
Number built	1,284
Variants	Grumman C-1 Trader Grumman E-1 Tracer Conair Firecat

The Grumman S-2 Tracker (previously S2F prior to 1962) was the first purpose-built, single airframe anti-submarine warfare (ASW) aircraft to enter service with the US Navy. The Tracker was of conventional design with twin engines, a high wing and tricycle undercarriage. The type was exported to a number of navies around the world. Introduced in 1952 the Tracker saw service in the USN until the mid-1970s with a few aircraft remaining in service with other air arms into the 21st century.

Design and development

Intended as a replacement for its predecessor, Grumman's AF-2 Guardian which was the first purpose-built aircraft system for ASW, using two airframes, one with the detection gear, and the other with the weapon systems, the Tracker combined both functions in one aircraft. Grumman's design (model G-89) was for a large high-wing monoplane with twin Wright Cyclone R-1820 nine cylinder radial engines, a yoke type arrestor hook and a crew of four. Both the two prototypes XS2F-1 and 15 production aircraft, S2F-1 were ordered at the same time, on 30 June 1950. The first flight was conducted on 4 December 1952, and production aircraft entered service with VS-26, in February 1954.
Follow-on versions included the WF Tracer and TF Trader, which became the Grumman E-1 Tracer and Grumman C-1 Trader in the tri-service designation standardization of 1962. The S-2 carried the nickname "Stoof" (S-two-F) throughout its military career; and the E-1 Tracer variant with the large overhead radome was colloquially called the "stoof with a roof.".^[1]
Grumman produced 1,185 Trackers. Another 99 aircraft carrying the CS2F designation were manufactured in Canada under license by de Havilland Canada. U.S.-built versions of the Tracker were sold to various nations, including Australia, Japan, Turkey and Taiwan.

[edit] Sensors and armament

The Tracker carried an internal torpedo bay capable of carrying two light weight torpedoes or one nuclear depth charge. There were six underwing hard points for rocket pods and conventional depth charges or up to four additional torpedoes. A ventrally mounted retractable radome and a Magnetic Anomaly Detector (MAD) mounted on an extendable rear mounted boom were also fitted. Early model Trackers had an Electronic Surveillance Measures (ESM) pod mounted dorsally just aft of the front seat overhead hatches and were also fitted with a smoke particle detector or sniffer. Later S-2s had the sniffer removed and had the ESM antennae moved to four rounded extensions on the wingtips. The engine nacelles carried JEZEBEL sonobouys in the rear (16 in early marks, 32 in the S-2E/G). Early Trackers also carried 60 explosive charges dispensed ventrally from the rear of the fuselage used for active sonar (JULIE) with the AN/AQA-3 and later AQA-4 detection sets, whereas the introduction of active sonobouys and AN/AQA-7 with the S-2G conversion saw these removed. Smoke dispensers were mounted on the port ventral surface of the nacelles in groups of three each.

[edit] Operational history

US Navy S-2 Tracker on the port catapult of USS Lexington (CVS-16) ready for take-off, 22 January 1963

The Tracker was eventually superseded for U.S. military use by the Lockheed S-3 Viking, the last USN Tracker squadron (VS-37 with S-2G models) was disestablished in 1976. The last Navy S-2 was withdrawn from service on 29 August 1976.^[2] A number live on as firefighting aircraft, however. Trackers continued to provide excellent service with the naval forces of other countries for years after the U.S. discontinued them. For example, the Royal Australian Navy continued to use Trackers as front line ASW assets until the mid 1980s.

[edit] Argentina

Argentine S-2T Turbo Tracker

The Argentine Naval Aviation received seven S-2A in 1962, six S-2E in 1978 and three S-2G in 1990s. They were used from both aircraft carriers, the ARA Independencia and the ARA 25 de Mayo and used in the COD (US-2A conversions ^[3]), Maritime Patrol and ASW roles. They were extensively used in the 1982 Falklands War, first from the 25 de Mayo, from where they detected the British Task Force and then from the mainland ^[4] when the carrier returned to port after the sinking of the ARA General Belgrano cruiser. In the 1990s, six remaining airframes where refurbished by Israel Aerospace Industries with turboprop engines as S-2T Turbo Trackers. As of 2010, with the retirement of Argentina's only aircraft carrier, the Trackers are annually deployed on board Brazilian Navy NAe São Paulo during joint exercises ARAEX and TEMPEREX ^[5] and with US Navy's aircraft carriers during Gringo-Gaucho maneuvers.^[6]

[edit] Australia

Australian Tracker 845 "in the chocks" prepares to launch from HMAS Melbourne, 1979

Between 1967 and 1984 the Royal Australian Navy operated two Squadrons of S-2E and S-2G variants, based at NAS Nowra (HMAS Albatross).^[7] These were VS-816 front line squadron, which embarked in the Majestic class aircraft carrier HMAS Melbourne, as part of the 21st Carrier Air Group whenever that ship was deployed; and VC-851 training squadron.^[7]
During approximately 17 years of operation of the Tracker, the RAN lost only one S-2 during aircraft operations due to an accident at sea on 10 February 1975.^[7] However, on 4 December 1976 a deliberately lit fire in a hangar at Nowra destroyed or badly damaged a large proportion of the RAN's complement of Trackers.^[7] These were subsequently replaced with ex-USN aircraft.^[7] The replacement aircraft were all S-2Gs,^[7] including the original aircraft modified by the USN to that status.^{[citation needed]} This saw the introduction of AQA-7 acoustic gear into RAN service and all RAN operational Trackers were subsequently modified to this standard.

[edit] Brazil

The Brazilian Air Force used Trackers. They operated from the aircraft carrier NAeL Minas Gerais. Both S-2A and S-2E were used (respectively as P-16A and P-16E) at the end of its service in Brazilian Air Force, one S-2T was used as a possible upgrade, but due the high costs it was canceled.

[edit] Canada

Canadian Forces CP-121 Tracker from VU-33 folds its wings while taxiing at CFB Moose Jaw in 1982

In 1954, de Havilland Canada entered into a contract to build Trackers under license to replace the outmoded TBM-3E Avengers being used by the Royal Canadian Navy. A total of 99 Canadian-built Trackers would enter service starting in 1956. From 1957 onwards, these aircraft operated from the newly-deployed aircraft carrier HMCS Bonaventure and various shore bases. All the Canadian Trackers were built to the earlier "A" model airframe design with a length of 42 feet (12.80 m) ^[8] (c.f. 43' 6" for later model Trackers) in order to fit in the Bonnie's hangar.^[9] In 1960, 17 active duty CS2F-1 aircraft were transferred to the Royal Netherlands Navy. In 1964, a pair of CS2F-1 aircraft were stripped of armament and ASW electronics, converted to transports, and subsequently used for carrier onboard delivery. The CS2F-1, -2, and -3 were redesignated as the CP-121 Mk.1, Mk. 2, and Mk. 3 respectively following the unification of Canadian forces in 1968.
After Bonaventure was decommissioned in 1970, all remaining Canadian Trackers were transferred to shore bases. This limited their usefulness for ASW patrols, and between 1974 and 1981, all but 20 were gradually placed in storage and the remainder were stripped of their ASW gear. The remaining active-duty Trackers served until 1990 doing fisheries protection and maritime patrol duties. A handful of Trackers were kept in flying condition until the late 1990s but were no longer used for active service.^[10]^[11]
A single Grumman-built S2F-1, serial number X-500, was sold to the RCN before Canadian production commenced. It was initially used for quality control purposes during Canadian production, and was later given a new RCN serial number, upgraded to CS2F-1 standards, and used to train RCN ground and maintenance personnel. This aircraft was placed in storage in 1972 and was undergoing restoration in March 2008.

[edit] Japan

Japan Maritime Self-Defense Force S2F-1 at Kanoya Air Base.

The Japan Maritime Self-Defense Force received 50 S2F-1 in 1957 from US, and operated until 1984. After being received, six S2F-1 were reconfigured into four S2F-U and two S2F-C variants. The S2F-1 is nicknamed Aotaka(あおたか, Blue Hawk).

[edit] Netherlands

Dutch Grumman S-2 Tracker

The Royal Netherlands Navy, (Netherlands Naval Aviation Service) received in 1960 17 CS2F-1 aircraft formerly used by the Royal Canadian Navy. These aircraft were operated from land bases as well as from the light carrier Karel Doorman until a fire in 1968 took that ship out of Dutch service.

[edit] Peru

Peruvian Navy S-2E Trackers

The Peruvian Navy operated with S-2E and S-2G from 1975 until 1989, they were assigned to Naval Aviation Squadron N°12 (Escuadron Aeronaval N°12). A total of 12 S-2Es were bought from the US Navy in 1975 and 4 S-2G in 1983.

[edit] Taiwan

Grumman received a contract for the conversion of 32 S-2T Trackers (from 25 S-2Es and 7 S-2Gs) in service with the Republic of China Air Force in late 1980s. Only 27 were ultimately converted due to a shortage of parts supplied by Grumman resulting in the use of remaining conversion kits as spare parts. The 27 S-2Ts were transferred to the ROC Navy Aviation Command on 1 July 1999 and while the ROCN continues to operate the type, less than half of the fleet is in operational condition, will be replaced by 12 rebuilt P-3C from US Navy.
The conversion involved: two Garrett/Honeywell TPE-331-15AW turboprop engines, each rated at 1,227 kW (1,645 shp), with four-blade propellers. The upgrade also included new mission equipment of AN/AQS-92F digital sonobuoy processor, A/NARR-84 99-channel sonobuoy receiver, Litton AN/APS-504 radar, AN/ASQ-504 MAD and AN/AAS-40 FLIR. The new turboprop engines resulted in a payload increase of 500 kg. Usually carries depth charges, Mk. 44, and Mk 46 lightweight ASW homing torpedoes.^[12]

[edit] Turkey

This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (February 2011)

The Turkish Navy received a number of S-2A Trackers under the MAP program and operated them from the Cengiz Topel Naval Air Base starting in the 1960s. These were later retired and replaced with S-2Es, which remained in service until 1994. Turkish Trackers were retired after a series of accidents caused by the advanced age and fatigue of the airframes.

[edit] Uruguay

The Uruguayan Navy received the first three S-2A Trackers on 10 April 1965 at the Capitan Curbelo Navy Base. On 15 September 1982, one S-2G arrived. On 2 February 1983, another two S-2Gs arrived. By September 2004, the remaining Uruguayan Trackers were not in flight condition.^[13]

[edit] Civilian use

In the late 1980s and early '90s Conair Aviation of Abbotsford, British Columbia, Canada took possession of retired U.S. and Canadian Trackers and converted them into Firecats, with a retardant tank replacing the torpedo bay. The Firecats were made in two variants, a piston engine Firecat and a turboprop-powered Turbo Firecat.

[edit] Variants

XS2F-1: Two prototype anti-submarine warfare aircraft powered by 1,450 hp R-1820-76WA engines.
YS2F-1: Designation of the first 15 production aircraft used for development, redesignated YS-2A in 1962.
S2F-1: Initial production variant with two 1,525 hp R-1820-82WA engines, re-designated S-2A in 1962, 740 built.
S2F-1T: Trainer conversion of S2F-1, redesignated TS-2A in 1962.
S2F-1U: Utility conversion of S2F-1, redesignated US-2A in 1962.
S2F-1S: S2F-1 conversion with Julie/Jezebel detection equipment, redesignated S-2B in 1962. Survivors converted to US-2B after removal of ASW gear.
S2F-1S1: S2F-1S fitted with updated Julie/Jezebel equipment, redesignated S-2F in 1962.
S2F-2: As S2F-1 with asymmetrical (port-side) extension of bomb bay, slightly enlarged tail surfaces, 77 built, most redesignated S-2C in 1962.
S2F-2P: Photo reconnaissance conversion of S2F-2, redesignated RS-2C in 1962.
S2F-2U: Utility conversion of S2F-2/S-2C, redesignated US-2C in 1962. Some were used as target tugs.
S2F-3: Enlarged forward fuselage, enlarged tail surfaces, additional fuel capacity, and enlarged engine nacelles bays for 32 sonobouoys, redesignated S-2D in 1962, 100 built.
S2F-3S: As S2F-3 but with Julie/Jezebel equipment, redesignated S-2E in 1962, 252 built.
YS-2A: YS2F-1 redesignated in 1962.
S-2A: S2F-1 redesignated in 1962.
TS-2A: S2F-1T training version redesignated in 1962 and 207 conversion from S-2A.
US-2A: S-2A converted as light transports/target tugs, 51 conversions.
S-2B: S2F-1S redesignated in 1962.
US-2B: Utility and target tug conversions of S-2A and S-2B; most S-2Bs were converted and 66 S-2As.
S-2C: S2F-2 redesignated in 1962.
RS-2C: S2F-2P photo-reconnaissance version redesignated in 1962.
US-2C: S2F-2U utility version redesignated in 1962.
S-2D: S2F-3 redesignated in 1962.
YAS-2D/AS-2D: Proposed self-contained night attack aircraft to be developed under Operation Shed Light; none produced.
ES-2D: Electronic trainer conversion of the S-2D.
US-2S: Utility conversion of the S-2D.
S-2E: S2F-3S redesignated in 1962.
S-2F: S2F-1S1 redesignated in 1962.
US-2F: Transport conversion of S-2F.
S-2G: S-2E conversions with updated electronics (primarily AN/AQA-7 DIFAR sonobuoy processor and AN/ARR-75 sonobuoy receiver)
CS2F-1: Initial production run of anti-submarine warfare aircraft for Canada based on S2F-1. A total of 42 built by De Havilland Canada.^[10]
CS2F-2: Improved version of CS2F-1 with Litton Industries tactical navigation equipment. A total of 57 were built by De Havilland Canada.^[10]
CS2F-3: New designation given to 43 CS2F-2 aircraft upgraded with additional electronics.
CP-121: New designation given to all CS2F-1, -2, and -3 aircraft following unification of Canadian military in 1968.
Military S-2T Turbo Tracker For Argentina: 6 upgraded S-2E turboprop engines conversion by IAI in 1990s for the Argentine Navy.
Military S-2T Turbo Tracker For Taiwan: 27 out of 32 upgraded S-2E and S-2G turboprop engines conversion by Northrop Grumman in 1990s for then Taiwan/ROC Air Force, now operates by Taiwan/ROC Navy aviation.
S-2T Turbo Tracker: Civil conversion
S-2AT: Civil firefighter conversion.
S-2ET

CDF S-2F3AT Turbine Tracker landing at Fox Field, Lancaster, California, while fighting the North Fire.

Civil conversion.
Marsh S-2F3AT Turbo Tracker: Turboprop conversion, powered by two Garrett TPE331 engines;^[14] A total of 22 are operated by the CDF.
Conair Firecat or Turbo Firecat: Civil conversion as a single-seat firefighting aircraft.

For the crew trainer/transport version based on the Tracker refer to Grumman C-1 Trader
For the Airborne Early Warning version based on the Trader refer to Grumman E-1 Tracer

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