Lockheed S-3 Viking

In the mid-1960s, the United States Navy (USN) formulated the VSX (Heavier-than-air, Anti-submarine, Experimental) requirement, which sought a dedicated anti-submarine aircraft capable of flying off of its aircraft carriers as a replacement for its existing inventory of piston-engined Grumman S-2 Trackers. The service issued a request for proposals to industry. During August 1968, a team led by Lockheed, as well as a rival team comprising Convair and Grumman, were requested to further develop their proposals to meet this requirement. At this stage, Lockheed recognised that it had little experience in designing carrier based aircraft, thus the company reached out to the industrial conglomerate Ling-Temco-Vought (LTV), which joined the team. LTV assumed responsibility for the design of various elements of the airframe, such as the folding wings and tail, the engine nacelles, and the landing gear, some of which had been derived from the earlier LTV A-7 Corsair II and Vought F-8 Crusader. Sperry Univac Federal Systems was assigned the task of developing the aircraft's onboard computers which integrated input from sensors and sonobuoys. On 4 August 1969, Lockheed's design was selected as the winner of the VSX contest; an order for eight prototypes, designated YS-3A, was promptly received by the company. Flight testing proceeded quickly with no major issues; two years later, the S-3 entered operational service with the U.S. Navy. During the type's production run, which ran from 1974 to 1978, a total of 186 S-3As were constructed. The majority of the surviving S-3As were later upgraded to the improved S-3B variant, while 16 aircraft were also converted into ES-3A Shadow electronic intelligence (ELINT) collection aircraft. ==Design==

The Lockheed S-3 Viking is a conventional monoplane with a cantilever shoulder wing, very slightly swept with a leading edge angle of 15° and an almost straight trailing edge. Its twin GE TF-34 high-bypass turbofan engines mounted in nacelles under the wings provide excellent fuel efficiency, providing the Viking with the required long range and endurance, while also maintaining relatively docile engine-out characteristics. The aircraft can seat four crew members (three officers and one enlisted) with pilot and copilot/tactical coordinator (COTAC) in the front of the cockpit and the tactical coordinator (TACCO) and sensor operator (SENSO) in the back. The wing is fitted with leading edge and Fowler flaps. Spoilers are fitted to both the upper and the lower surfaces of the wings. All control surfaces are actuated by dual hydraulically boosted irreversible systems. In the event of dual hydraulic failures, an Emergency Flight Control System (EFCS) permits manual control with greatly increased stick forces and reduced control authority. Unlike many tactical jets which required ground service equipment, the S-3 was equipped with an auxiliary power unit (APU) and capable of unassisted starts. The aircraft's original APU could provide only minimal electric power and pressurized air for both aircraft cooling and for the engines' pneumatic starters. A newer, more powerful APU could provide full electrical service to the aircraft. The APU itself was started from a hydraulic accumulator by pulling a handle in the cockpit. The APU accumulator was fed from the primary hydraulic system, but could also be pumped up manually (with much effort) from the cockpit. All crew members sit on forward-facing, upward-firing Douglas Escapac zero-zero ejection seats. In "group eject" mode, initiating ejection from either of the front seats ejects the entire crew in sequence, with the back seats ejecting 0.5 seconds before the front in order to provide safe separation (this was to prevent the pilots, who were more aware of what was happening outside the aircraft from ejecting without the rest of the crew, or being forced to delay ejection to order the crew to eject in an emergency; ejection from either rear seat would not eject the pilots, who had to initiate their own ejections, to prevent loss of the aircraft if a rear crewmember ejected prematurely. If a pilot ejected prematurely, the plane was lost anyway, and automatic ejection prevented the crew from crashing with a pilot-less aircraft before they were aware of what had happened). The rear seats are capable of self ejection and the ejection sequence includes a pyrotechnic charge that stows the rear keyboard trays out of the occupants' way immediately before ejection. Safe ejection requires the seats to be weighted in pairs, and when flying with a single crewman in the back the unoccupied seat is fitted with ballast. At the time it entered the fleet, the S-3 introduced an unprecedented level of systems integration. Previous ASW aircraft like the Lockheed P-3 Orion and S-3's predecessor, the Grumman S-2 Tracker, featured separate instrumentation and controls for each sensor system. Sensor operators often monitored paper traces, using mechanical calipers to make precise measurements and annotating data by writing on the scrolling paper. Beginning with the S-3, all sensor systems were integrated through a single General Purpose Digital Computer (GPDC). Each crew station had its own display, the co-pilot/COTAC, TACCO and SENSO displays were Multi-Purpose Displays (MPD) capable of displaying data from any of a number of systems. This new level of integration allowed the crew to consult with each other by examining the same data at multiple stations simultaneously, to manage workload by assigning responsibility for a given sensor from one station to another and to easily combine clues from each sensor to classify faint targets. As a consequence of this integration, the four-crew S-3 was considered roughly equivalent in terms of capability to the much larger P-3, operated by a crew of 12. The aircraft has two underwing hardpoints that can be used to carry fuel tanks, general purpose and cluster bombs, missiles, rockets, and storage pods. It also has four internal bomb bay stations that can be used to carry general-purpose bombs, aerial torpedoes, and special stores (B57 and B61 nuclear weapons). Fifty-nine sonobuoys are carried, as well as a dedicated Search and Rescue (SAR) chute. The S-3 is fitted with the ALE-39 countermeasure system and can carry up to 90 rounds of chaff, flares, and expendable jammers (or a combination of all) in three dispensers. A retractable magnetic anomaly detector (MAD) Boom is fitted in the tail. In the late 1990s, the S-3B's role was changed from anti-submarine warfare (ASW) to anti-surface warfare (ASuW). As a consequence of this role change, the MAD Boom was removed, along with several hundred pounds of submarine detection electronics. As there was no remaining sonobuoy processing capability, most of the sonobuoy chutes were faired over with a blanking plate. ==Operational history==

in 1975 On 20 February 1974, the S-3A officially became operational with the Air Antisubmarine Squadron FORTY-ONE (VS-41), the "Shamrocks," at NAS North Island, California, which served as the initial S-3 Fleet Replacement Squadron (FRS) for both the Atlantic and Pacific Fleets until a separate Atlantic Fleet FRS, VS-27, was established in the 1980s. The first operational cruise of the S-3A took place in 1975 with the VS-21 "Fighting Redtails" aboard . Starting in 1987, the majority of S-3As were progressively upgraded to the improved S-3B standard; this involved the addition of several new sensors, avionics, and weapons systems, which included the capability to launch the AGM-84 Harpoon anti-ship missile. As a consequence of the collapse of the Soviet Union and the breakup of the Warsaw Pact in the early 1990s, the Soviet-Russian submarine threat was perceived as much reduced, and the Vikings had the majority of their antisubmarine warfare equipment removed. The aircraft's mission subsequently changed to sea surface search, sea and ground attack, over-the-horizon targeting, and aircraft refueling. It was commonly deployed to hunt for Scud missile launcher. The Vikings also identified and targeted numerous Iraqi naval vessels, and even destroyed anti-aircraft gun emplacements and coastal radars. Final years and retirement 's S-3B, callsign "Bloodhound 700", in 2010. from 2009 to 2021. A proposed airframe known as the Common Support Aircraft was advanced as a successor to the S-3, E-2, and C-2, but this initiative failed to materialize. In 1998, the U.S. Navy awarded a $40 million contract for Lockheed Martin to perform a full-scale Fatigue testing of the existing S-3s; these tests, which commenced in June 2001, were aimed at extending the viable service life of each remaining aircraft, which had originally been certified for a structural life of 13,000 flight-hours. It was hoped that this could be extended to as much as 17,750 hours. The final carrier-based S-3B squadron, VS-22, was decommissioned at NAS Jacksonville on 29 January 2009. Sea Control Wing Atlantic was decommissioned the following day, along with the last S-3s in frontline fleet service. These S-3Bs are flown by Air Test and Evaluation Squadron Thirty (VX-30) based out of NAS Point Mugu, California. By late 2015, the U.S. Navy were operating a total of three Vikings in support roles. One was relocated to The Boneyard in November 2015, while the final two were retired, one being stored and the other transferred to NASA, on 11 January 2016, officially retiring the S-3 from Navy service. During 2004, NASA acquired four of the withdrawn S-3Bs for use at its Glenn Research Center. In 2009, one of these aircraft (USN BuNo 160607) was given the civil registration N601NA, it was involved in numerous tests conducted by the agency. For over a decade, this aircraft was flying almost every day in support for various research programs; However, a lack of spare parts and increasing difficulty supporting the type meant their use could not continue in the long term. The last of the NASA's S-3Bs, which were the final working members of the type in existence with any operator at that point, were retired on 13 July 2021. Potential revival and proposals In October 2013, the Republic of Korea Navy expressed its interest in acquiring up to 18 ex-USN S-3s to augment their fleet of 16 Lockheed P-3 Orion aircraft. In August 2015, a military program review group approved a proposal to incorporate 12 mothballed S-3s to perform ASW duties; the Viking plan was sent onto the Defense Acquisition Program Administration for further assessment before final approval decision by the national defense system committee. Although the planes are relatively old, being in storage has supposedly kept them serviceable, and using them is an affordable means of fulfilling short-range airborne ASW capabilities that were vacated by the retirement of the S-2 Tracker. Refurbished S-3s could have been returned to use by 2019. During April 2014, Lockheed Martin announced that they would offer refurbished and remanufactured S-3s, dubbed the C-3, as a replacement for the Northrop Grumman C-2A Greyhound for carrier onboard delivery. The requirement for 35 aircraft would be met from the 91 S-3s currently in storage. In February 2015, the Navy announced that the Bell Boeing V-22 Osprey had been selected to replace the C-2 for the COD mission. A SV-22 was a proposed anti-submarine warfare variant the U.S. Navy studied in the 1980s to replace S-3 Viking and late model SH-2 Seasprite ASW helicopters. ==Variants==

in 1987 ;S-3A :First production version, 187 built. ;S-3B :Upgraded avionics, AN/APS-137 inverse synthetic aperture radar, Joint Tactical Information Distribution System, AGM-84 Harpoon launch capability, first flight 13 September 1984, 119 converted from S-3As. ;ES-3A Shadow :Designed as a carrier-based, subsonic, all-weather, long-range, electronic reconnaissance (ELINT) aircraft. 16 aircraft were modified to replace the EA-3B Skywarrior, entering fleet service in 1993. The ES-3A carried an extensive suite of electronic sensors and communications gear, replacing the S-3's submarine detection, armament, and maritime surveillance equipment with avionics racks accommodating the ES-3A's sensors. These modifications had minor impact on airspeed, reducing its top rated speed from but had no noticeable impact on the aircraft's range and actually increased its rated loiter time. Because these aircraft were standoff indications and warnings platforms and were never intended to be part of an ingress strike package, this new speed limitation was considered insignificant. ;KS-3A :Proposed dedicated air tanker with fuel capacity of 4,382 US gal (16,600 L), one converted from YS-3A, later converted to US-3A. ==Operators==

; • United States Navy (former) • VS-21 Red Tails (1975-2005) • VS-22 Checkmates (1976-2009) • VS-24 Scouts (1977-2007) • VS-27 Seawolves/Grim Watchdogs (1987-1994) • VS-28 Hukkers/Gamblers (1976-1992) • VS-29 Dragonfires (1976-2004) • VS-30 Diamond Cutters (1977-2007) • VS-31 Topcats (1977-2008) • VS-33 Screwbirds (1977-2006) • VS-35 Boomerangers/Blue Wolves (1986-88/1991-2005) • VS-37 Sawbucks (1978-1995) • VS-38 Red Griffins (1978-2004) • VS-41 Shamrocks (1974-2006) • VQ-5 Sea Shadows (1991-1999) • VQ-6 Black Ravens (1991-1999) • VX-1 Pioneers (Unknown) • NASA (former) ==Aircraft on display==

;YS-3A • 157993 – NAS Jacksonville Aircraft Heritage Park, NAS Jacksonville, Jacksonville, Florida. ;S-3A • 159417 – Celebrity Row, Davis-Monthan AFB (North Side), Tucson, Arizona. ;ES-3A • 159404 – Celebrity Row, Davis-Monthan AFB (North Side), Tucson, Arizona. ;S-3B • 159387 – Navy One National Naval Aviation Museum, NAS Pensacola, Pensacola, Florida. • 159412 – NAS North Island, San Diego, California. • 159731 – at the Patriot's Point Naval and Maritime Museum, Charleston, South Carolina. • 159743 – Aviation History & Technology Center, Dobbins ARB (formerly Atlanta NAS), Marietta, Georgia. • 159755 – NAS Pensacola, Pensacola, Florida. • 159766 – at San Diego, California. • 159770 – Patuxent River Naval Air Museum, Lexington Park, Maryland. • 160123 – Air Zoo at Kalamazoo, Michigan. • 160599 – at the former NAS Alameda, Alameda, California. • 160604 – Pima Air and Space Museum (adjacent to Davis-Monthan AFB), Tucson, Arizona. • N601NA (160607) - NASA Viking San Diego Air & Space Museum, San Diego, California. ==Specifications (S-3A)==