S-2 Tracker

The Tracker was conceived as a replacement for the Grumman AF Guardian, which employed a two-aircraft "hunter-killer" approach for anti-submarine warfare. The Tracker aimed to combine these functions into a single airframe. Grumman's design, designated model G-89, featured a large high-wing monoplane with twin Wright Cyclone R-1820 radial engines, a yoke-type arrestor hook, and a four-person crew. The U.S. Navy ordered both the two XS2F-1 prototypes and 15 S2F-1 production aircraft simultaneously on June 30, 1950. The first flight took place on December 4, 1952, and the aircraft entered service with VS-26 in February 1954.

Design

The Tracker was of conventional design, featuring a high wing that could be folded for storage and tricycle undercarriage. Power was provided by twin Wright Cyclone R-1820 nine cylinder radial engines. The aircraft's internal torpedo bay could carry two lightweight aerial torpedoes or one nuclear depth charge. There were also six underwing hard points for rocket pods and conventional depth charges or up to four additional torpedoes. Overall, the aircraft could carry up to 4,800 lb (2,200 kg) of payload.

For submarine detection, a ventrally-mounted retractable radome housed the AN/APS-38 radar, complemented by a Magnetic Anomaly Detector (MAD) AN/ASQ-8 mounted on an extendable rear boom. Early models featured an Electronic Support Measures (ESM) pod dorsally just aft of the front seat overhead hatches, along with a "sniffer" to detect exhaust particles from diesel-electric submarines running on snorkel. Later models had the sniffer removed and the ESM antennae relocated to rounded extensions on the wingtips. A 70-million-candlepower searchlight was mounted on the starboard wing for nighttime operations. The engine nacelles carried JEZEBEL sonobuoys in the rear, with early marks carrying 16 and later S-2E/G models carrying 32. Early Trackers used 60 explosive charges, dispensed ventrally to create sound pulses for semi-active sonar (JULIE), though these were later replaced by active sonobuoys and the AN/AQA-7 detection set in the S-2G conversion. Smoke dispensers were mounted on the port ventral surface of the nacelles, grouped in threes.

Grumman produced 1,185 Trackers, and an additional 99 were manufactured in Canada under license by de Havilland Canada, designated as CS2F aircraft. The S-2 was nicknamed "Stoof", while the E-1 Tracer variant with its prominent overhead radome was colloquially known as the "stoof with a roof."

Operational History

The Tracker entered U.S. Navy service in 1954, eventually being superseded by the Lockheed S-3 Viking, with the last USN Tracker operational squadron disestablished in 1976 and the last Navy S-2 withdrawn from service on 29 August 1976. Prior to that, the TS-2A version was used by U.S. Navy training units for Student Naval Aviator training. A number of Trackers were later converted into firefighting aircraft. U.S.-built versions were exported to countries including Australia, Japan, Turkey, and Taiwan. The naval forces of other countries operated the design for years after the U.S. retired them. The Royal Australian Navy used Trackers as front line ASW assets until the mid-1980s. Argentine Naval Aviation operated Trackers from both aircraft carriers, ARA Independencia and ARA Veinticinco de Mayo, utilizing them in carrier onboard delivery, maritime patrol, and ASW roles, including operations during the 1982 Falklands War. The Brazilian Air Force flew Trackers from the aircraft carrier NAeL Minas Gerais, while the Royal Netherlands Navy operated the aircraft from Valkenburg Naval Air Base as well as from the light aircraft carrier Karel Doorman. The Republic of China Air Force initially operated the S-2A in 1967 and later converted several S-2E/Gs to the S-2T configuration. The Turkish Navy operated ex-U.S. Navy S-2E Trackers, supplemented by retired S-2A airframes from the Netherlands, until their retirement in 1994.

Variants

Main Variants:

• S2F-1: This was the initial production variant, equipped with two 1,525 hp R-1820-82WA engines, and was later redesignated as S-2A in 1962.

• S2F-1S: This was an S2F-1 conversion featuring Julie/Jezebel detection equipment, which was later redesignated as S-2B in 1962.

• S2F-2: An improved version of the S2F-1 featuring an asymmetrical (port-side) extension of the bomb bay and slightly enlarged tail surfaces.

• S2F-3: This variant featured an enlarged forward fuselage, enlarged tail surfaces, additional fuel capacity, and enlarged engine nacelles bays to accommodate 32 sonobuoys; it was later redesignated as S-2D in 1962.

• S-2G: These were S-2E conversions incorporating updated electronics, primarily the AN/AQA-7 DIFAR sonobuoy processor and AN/ARR-75 sonobuoy receiver.