After World War II, the U.S. Navy began the development of specialized carrier-based aircraft for antisubmarine warfare. Previously, standard fighters and bombers were employed for that role.
The Navy’s first aircraft designed specifically for the ASW role were the so-called “Guardian Twins,” the Grumman AF, which came in two “flavors”—the W-suffix aircraft with the large AN/APS-20 radar for detecting submarine masts and periscopes, and the S-suffix with a limited detection capability but a large weapons bay and wing pylons for weapons.1 These search-and-attack capabilities were first combined in the Grumman S2F (later S-2) Tracker, whose initial flight was in December 1952.
By the mid-1960s the Navy was seeking a more advanced carrier ASW aircraft—given the development designation VSX. Updated sensors were available, and a faster and longer-range aircraft would be more effective in reaching potential targets. Also significant, with the demise of the specialized ASW carriers—designated CVS—the airborne subhunters would operate from attack carriers that carried only turbine-powered aircraft. Handling piston-engine fuels for just the Tracker would be a burden.
When the VSX requirement appeared, Grumman Aircraft, later Grumman Aerospace Corporation, was the favored competitor, having produced far more carrier aircraft—among them the Guardian and Tracker ASW planes—than any other firm. But Lockheed had been in the ASW business longer, albeit with land-based aircraft, beginning with the PBO Hudson in the late 1930s through the P-3 Orion that entered service in 1962. To compensate for its limited experience in carrier-based aircraft, Lockheed teamed with Ling-Temco-Vought, which had several outstanding carrier planes to its credit, and firms with ASW-systems experience.
Lockheed was named VSX winner in August 1969, with an initial batch of eight flight-test aircraft (YS-3A) being ordered by the Navy. The first Viking took to the air on 21 January 1972. The flight tests were successful, with initial carrier trials on board the USS Forrestal (CVA-59) in November 1973. Even before flight trials had been completed, the Navy ordered the Viking into production as the S-3A.2
The plane had a snub nose and a high wing carrying two General Electric high-bypass turbofan engines, mounted in underwing nacelles, just inboard of the wing-fold points. The early operational aircraft were fitted with a Univac AN/AYK-10 digital computer to support a host of sensors including AN/APS-116 radar, OR-89 forward-looking infrared (FLIR), AQS-81 magnetic anomaly detector (MAD), ALR-47 electronic countermeasures (ECM) system, and 60 sonobuoy chutes.
For the “killer” side of the mission the Viking had an internal weapons bay for up to 2,000 pounds of depth bombs, mines, and torpedoes, plus stores on two wing pylons. Each pylon could carry a Harpoon or Bullpup antiship missile or a 300-gallon drop tank. A retractable in-flight refueling probe was provided.
The flight crew consisted of two pilots, a tactical coordinator, and a sensor operator. Each had an ejection seat that could work at any speed/altitude combination.
The first fleet squadron to fly the Viking was Antisubmarine Squadron (VS) 21, which went aboard the John F. Kennedy (CVA-67) in 1975. With 187 ASW aircraft produced—including the eight YS-3A prototypes—the Navy formed 12 Viking squadrons plus a readiness/replacement squadron. Thus, almost every carrier air wing was provided with an eight-plane S-3 squadron, which shared the ship-based ASW role with an SH-3 Sea King helicopter squadron (HS).
The Viking proved to be a reliable, safe, and relatively effective ASW aircraft. The only significant problem encountered was the plane’s stall characteristics, which were rectified by the addition of minor stall strips.
Similar to the evolution of its predecessor—the S-2 Tracker—into the C-1 Trader for carrier-on-board (COD) cargo and passenger delivery, the seventh YS-3A was modified to a COD prototype. In that role—with ASW gear removed—it could carry six passengers or 5,750 pounds of cargo internally and another 1,000 pounds in two wing pods. Range and speed were superior to the Trader. The first of the modified planes flew in 1976 as the US-3A. Three additional YS-3A/US-3A conversions followed. Lockheed also proposed a larger variant with a side door and a 70-inch fuselage extension, or “plug,” that would provide an 8,000-pound cargo capacity. The Navy, however, declined production. Instead it bought the C-2 Greyhound, derived from Grumman’s E-2 Hawkeye electronic-warfare aircraft.
Similarly, Lockheed converted the fifth YS-3A to an aerial tanker, fitting it with a drogue-and-reel system. The tanker could carry 16,000 pounds of fuel, of which 11,000 pounds could be transferred to another aircraft. Refueling trials were successful, but again the Navy opted for a Grumman aircraft—the KA-6D, modified from A-6A airframes. Yet another Viking variant was a an electronic intelligence (ELINT) collection aircraft, the ES-3A Shadow. Sixteen were produced and served on board several carriers in small detachments. However, the aircraft was considered too expensive to maintain and was discarded in 1999.
Lockheed also proposed variants of an airborne early warning (AEW) configuration to succeed the turboprop Hawkeye. The principal version had a fixed, triangular radome atop the wing and fuselage, which was to house a high-power, angle-beam, L-band phased-array (electronically scanned) radar. It would retain a limited weapons capability as well as the in-flight refueling probe. That proposal, too, was rejected.
Including the eight preproduction Vikings and the 16 Shadows, the Navy procured a total of 203 of these aircraft. The last S-3A was delivered in August 1978 and the last ES-3A in September 1993. The ASW variants were periodically upgraded, with improved sensors and acoustic data-processing capacity; these aircraft were designated S-3B, with the first of about 160 upgrades joining the Fleet in December 1987.
With the demise of the Soviet Union in late 1991 and the subsequent reduction of the Soviet submarine threat, as of 1993 the S-3B was considered a “sea control” rather than ASW aircraft, and in the mid-1990s the ASW equipment and operators were removed. Thus configured, they were employed in ocean surveillance, antishipping (with Harpoon and Maverick missiles), and aerial tanking (with external drogue and fuel tanks). The last role was critical because of the demise of the KA-6D Intruder tankers and the relatively short range of the F/A-18 Hornet strike fighters.
Discarding the Viking from the ASW role initially left the carrier force with only the specialized SH-60F Seahawk helicopters for the assignment. However, even that limited capability is being diluted with their replacement by a smaller number of multimission MH-60R Seahawks.
In the post–Cold War era, the cost of operating and maintaining an S-3B force for the “sea control” mission was considered extravagant, and the surviving Vikings were rapidly retired. The last carrier VS/S-3B squadron went ashore in January 2009.
Five S-3B aircraft have been retained for research and development. The rest of the Vikings—a fine aircraft that served in an important role during the Cold War—have been retired.
1. See N. Polmar, “The Navy’s Guardian,” Naval History (June 2006), pp. 14–15.
2. The principal reference for the S-3 is René J. Francillon, Lockheed Aircraft Since 1913 (Annapolis, MD: Naval Institute Press, 1987). The most comprehensive journal article on the aircraft is Jay Miller, ed., “Lockheed S-3A Viking,” Aerophile (February 1979), pp. 308–41.