Grumman S-2 Tracker (S2F)
Anti-Submarine Warfare (ASW) Aircraft
The Grumman S-2 Tracker was specifically designed and produced for the US Navy to help combat enemy submarines.
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The Grumman S-2 Tracker was designed, developed and produced for the United States Navy at a time when carriers had taken the mantle from battleships as the spearhead of naval operations and national symbol of firepower at sea. The carrier came of age in World War 2 (1939-1945) and allowed massed airpower to be brought to bear against foes anywhere in the world - this proven through the exploits of the United States Navy in the conflict, allowing its forces to meet the Empire of Japan head-on and ultimately claim air superiority for the duration of the war. Carrier warfare proved critical to the Japanese surrender in August of 1945. By the end of the conflict, technology was beginning a boom of massive proportions, giving rise to developments such as the turbojet, sophisticated radar and sensory equipment and all-new aircraft.
While carrier fighter and strike aircraft certainly allowed the required offensive reach, ever-growing storage space on newer carriers allowed other specialized platforms to emerge. In late 1945, Grumman flew its first AF Guardian, the USN's first "purpose-built" Anti-Submarine Warfare (ASW) aircraft. This proved a rather gangly-looking attempt, crewed by three or four personnel and powered by a single Pratt & Whitney radial piston engine (essentially looking the part of a heavily-modified torpedo bomber). The Guardian was actually devised a two-aircraft "system" consisting of a submarine detection platform and a reactionary attack-minded platform - utilizing a "hunter-killer" approach. Some 389 Guardian aircraft were ultimately produced and these served into August of 1955.
Grumman began work on a successor to the Guardian line though this time with the intent of producing a single-airframe solution for the USN. The concern developed the "Model G-89" prototype, a rather conventional straight-winged airframe utilizing a crew of four with a twin-engine layout and the requisite carrier-friendly installments (reinforced undercarriage, high-mounted monoplane wings, arrestor hook, folding wings etc...). Prototypes of the USN were granted the designation of "XS2F-1" and two were completed for testing. The initial XS2F-1 prototype first took to the air on December 4th, 1952 and proved the design sound. Fifteen evaluation-quality aircraft (YS2F-1) were on order and the first of these was delivered to squadron VS-26 in February of 1954.
Outwardly, the S-2F Tracker utilized a centralized fuselage with the cockpit held well-forward in the design, just aft of a short nose cone assembly. Vision was through two forward panes and side ports as well as overhead windows. The fuselage was slab-sided and mounted short wingroots with streamlined engine nacelles underslung. Each wing offered three hardpoints outboard of the engine. The aircraft made use of a powered tricycle undercarriage consisting of two main legs and a double-wheeled nose leg (when at rest, this arrangement gave the S-2 a pronounced "nose-up" appearance). The empennage was traditional in that it exhibited a single vertical tail fin and a pair of applicable horizontal tailplanes. The aircraft was crewed by four personnel which was made up of two pilots and two systems officers.
Power for the type (S-2F) was supplied through 2 x Wright R-1820-82WA air-cooled radial piston engines, each delivering up to 1,525 horsepower and powering three-bladed propeller assemblies. This provided the airframe with a top speed of 280 miles per hour and a cruise speed of 150 miles per hour. Range was out to 1,350 miles with a service ceiling maxing at 22,000 feet. All told, the S-2 could operate for some nine hours, providing consistent hunting prowess against enemy submarines. During the Cold War, this would principally be those of the Soviet Navy.
As the S-2 was designed from the outset to be a complete anti-submarine solution, the USN and Grumman engineers ensured that the airframe would carry its own munitions load. The aircraft was designed for up to 4,800lbs of internal and external ordnance which included a single large internal bomb bay along the underside of the fuselage as well as six underwing hardpoints. The S-2 was, therefore, cleared to carry two internal torpedoes or, in their place, naval mines or depth charges. Rockets could be outfitted under each wing as required, this serving to engage service vessels at range.
Initial production models were recognized as the "S2F-1" Tracker of which 740 examples were ultimately produced. This then spawned the S2F-1T trainer variant as well as the S2F-1 utility platform. Specialized equipment (JULIE/JEZEBEL detection systems) greeted the S2F-1S and S2F-1S1 conversion models. The S2F-1 was then followed into service through the the "S2F-2" which added an elongated port-side bomb bay section and revised tail surfaces. Some 77 of this type were produced. As in the S2F-1, the S2F-2 airframe begat other operational models in the S2F-2P photo-reconnaissance platform and the S2F-2U utility airframe. With a revised forward fuselage, larger tail surfaces and increased internal volume for additional fuel stores, the series was reborn in the "S2F-3" of which 100 were produced. Specialized equipment produced the S2F-3S and these saw 252 examples completed.
In 1962, the United States military underwent a restructuring which completely rewrote the designation process of all of its aircraft (through the "1962 United States Tri-Service Aircraft Designation System") in an attempt to unify the designation system across all three major branches. This led to the S2F series being redesignated under the "S-2F" marker and all previous variants were updated as such. The S2F-1 became the S-2A while the S2F-1T became the TS-2A and so on. The S2F-1S was the S-2B and the S2F-2 was the S-2C. Reconnaissance models were noted for their use of "R" (RS-2C) and utility versions were given "U" (US-2C). The S2F-3 became the S-2D, the S2F-3S was now the S-2E and the S2F-1S1 was the S-2F. Canadian production models (by de Havilland Canada) were designated with a "C" before each model in the usual way. The "Turbo Tracker" line was developed in later years and these introduced turboprop engines to the family. Some of this type continue to see modern usage.
The S-2 went on to become a commercial success for Grumman for it saw use in many of the World's navies of the era. This included Argentina, Australia, Brazil, Canada, Italy, Japan, Netherlands, Peru, South Korea, Taiwan, Thailand, Turkey, Uruguay and Venezuela. Many went on to see a second life of sorts in their post-military careers as fire-fighting platforms as was the case in Canada, France and the United States. To date, S-2 operator numbers continue to dwindle - the Taiwanese Navy maintains as many as 26 in inventory (2012) though these are slated to be formally replaced by the modern P-3C Orion platform. Argentina and Brazil are two other current S-2 operators.
In total, 1,284 S-2 Trackers were produced for all listed navies. The United States Navy operated the type until 1976. The Grumman C-1 Trader and E-1 Tracer were offshoot developments of the S-2 airframe for the USN, the former once in use as a Carrier On-board Delivery (COD) transport aircraft and the latter seeing service as the USN's first, purpose-built Airborne Early Warning (AEW) platform - both have since been retired. The S-2 Tracker series was, itself, replaced in USN service by the all-modern, twin-engine, jet-powered Lockheed S-2 "Viking" in 1974. However, even these have now seen cessation of carrier operations thanks to broadening capabilities of aircraft such as the F/A-18 Super Hornet and P-3C Orion as well as the Sikorsky SH-60 Seahawk naval helicopter. Only 188 Vikings were produced.