United States of America (1975)

Anti-Submarine Warfare Aircraft; 188 built, 160 upgraded to S-3B

The Lockheed S-3 Viking was an anti-submarine warfare aircraft designed to replace the aging S-2 Tracker, later becoming one of the most important components of the US Navy’s anti-submarine strategy during the late Cold War. Designed in anticipation of modern Soviet Nuclear submarines, the Viking could boast of a host of cutting edge sensors and computerization that put it well above the curve, and all wrapped up in an airframe that was reliable and versatile. Its exceptional anti-submarine capabilities were augmented even further during its mid-life improvements which lead to the introduction of the improved S-3B. After the Cold War, the aircraft transitioned away from its traditional anti-submarine duties to surface surveillance, signals intelligence, and aerial tanker duties. A thoroughly reliable and advanced aircraft, the Viking easily ranked among the most important and versatile aircraft to ever serve aboard US carriers.

The Modern Submarine

The submarine of the Second World War was little more than a long range torpedo boat with the ability to submerge itself for short periods of time to avoid detection. Its offensive capabilities were rather modest, and apart from some outlying, but considerable, success against warships, it was typically seen as a tool for disrupting overseas shipping. Their comparatively low speed coupled with the need to transit on the surface for long periods, which snorkels could not entirely eliminate, would see them become a supporting vessel of most navies. However, advancements near the end of the war would transform the submarine from a raider and reconnaissance vessel, to one of naval warfare’s principal combatants.

Owing to the extreme desperation of the German U-boat force, a submarine built along new, revolutionary lines was designed. As the surface proved an exceptionally dangerous place to be, due to long range Allied patrol aircraft, the new boat would be designed to operate almost entirely submerged for the duration of its patrols. The new Type XXI was designed around the most modern features of any submarine thus built, featuring a much improved pressure hull construction, partially-automatic torpedo loading, a powerful sonar array, and a massive battery capacity which, combined with a hydrodynamically clean hull, allowed it to travel at double the speed of a conventional Type VIIC with over three times the range.

The Type XXI only completed a single wartime patrol, but its effects on naval engineering and submarine design were dramatic. In effect, every submarine built before it was obsolete, effectively restarting a new naval arms race. In the context of the then brewing Cold War, this was the cause of no shortage of anxiety for Western Navies. While the Soviet Union’s shipbuilding capabilities were relatively meager, and greatly damaged during the war, their experience with the new German submarine could very well allow them to leap up to the position of the world’s most prominent navies, if only in the field of submarine design.

In addition to the new submarine’s capabilities, the Type XXI also demonstrated that submarines could also be built at an unheard of rate thanks to its modular construction. Submarine sections could be constructed at secondary factories before being shipped to main construction yards, where they would be assembled into completed boats. Initially, an intelligence survey estimated that the Soviet Union could have as many as 2000 modern diesel-electric submarines in 1960. However, a much more reasonable secondary survey noted that they were likely restricted to 400 boats, owing to available dockyard space, fuel, and bottlenecks in battery maintenance and production. Regardless, the US Navy began work on a modernized anti-submarine strategy to counter a potential flood of Soviet boats which could threaten intercontinental supply lines in a potential war.

The first of the new Soviet boats was the Project 613 ‘Whiskey’, a somewhat shrunken derivative of the German Type XXI. It had more modest performance than the German boat in regards to speed, range, and endurance, but once it received a snorkel on later models, it had the same ability to remain underwater for long periods. The Whiskey was thus the most advanced submarine the Soviet Union had yet built. In countering these submarines, the US Navy would employ a modified version of the same strategy it had used in the Second World War. The primary anti-submarine weapon was to remain the airplane, in the form of long range patrol aircraft, like the P-2 Neptune, and carrier based planes, like the new models of TBM-3 Avenger. Their primary means of locating submarines were radar, which could detect snorkeling submarines, magnetic anomaly detectors, which were set off by a submarine’s magnetic signature, and sonobuoys, which determine the position of a transiting submarine if dropped close enough. Radar was the main means of detecting a submarine at range, with the other two systems being used to ‘fix’ its location before attacking with torpedoes and depth charges.

Unlike their land based counterparts, early carrier based ASW aircraft lacked the ability to carry both the sensors and weapons needed for the task and were thus placed in a pair of cooperating aircraft. The first such pair were the TBM-3W ‘warning’, for detection, and TBM-3S ‘strike’, for carrying out attacks on marked submarines. These hunter-killer teams operated aboard modified escort carriers and later switched to fleet carriers, when it became clear the small escort carriers could not reliably launch and recover the larger hunter-killers. In the early 50s, it was recognized that the entire system was extremely clumsy and would not provide adequate anti-submarine support.

The CVS program was thus introduced, which brought several mothballed WWII era-fleet carriers back into service as dedicated anti-submarine warfare ships. The CVS’s, which were introduced in 1952, were soon joined by the S-2 Tracker two years after. The Tracker was large enough to carry both the sensors and the weapons, and the clumsy hunter-killers were finally dispensed with. The S-2 was an excellent ASW aircraft which would go on to serve in a number of roles, though by the mid 60s, the growing capabilities of Soviet submarines and operational troubles with operating a piston engined aircraft on increasingly jet dominated carriers began to highlight the need for a replacement.

The Soviet Nuclear Submarine

Through the 50s and early sixties, the existing strategies for sub hunting were predicated on the need for submarines to recharge their batteries, and that said batteries could be discharged during a drawn out search, thus rendering the submarine helpless. Advancements in Soviet nuclear engineering would end up negating most of these existing strategies. General Secretary Iosif Stalin would formally sign off on the program to build the first Soviet nuclear submarine in 1952. The boat was to be a delivery platform for a gigantic nuclear torpedo for use against harbors. It was completely impractical, and due to the extreme secrecy surrounding it, was rejected by Soviet Admiral Kuzntetsov upon learning of it. The Project 672 Kit (NATO reporting sign November) was then given a conventional torpedo armament and went out to sea in 1958. It was a fast boat, with a given maximum speed of 28 kts, but its turbines proved unreliable and its reactor developed leaks after 800 hours. Less concerning was its noisiness, a factor Soviet submarine designers felt was less important than top speed, and a design choice that would plague Soviet nuclear submarines into the 1970s.

The nuclear submarine was a far more capable and deadly opponent compared to its diesel electric counterparts. Without needing to rely on electric power for underwater propulsion, a nuclear submarine was not restricted to a small patrol area, nor did it need to expose itself to detection to recharge. Furthermore, it was fast. As loud as the Novembers were, they were nearly twice as fast as contemporary diesel electric submarines. Lastly, their larger size enabled them to carry larger, more sensitive sonar systems and greater complements of weapons. In short, it was a faster, more alert, and better armed threat than anything the US Navy ever had to contend with.

The Novembers proved to be a wake up call to the US Navy, but their operational restrictions kept them from being perceived as a massive threat. For instance, they were not deployed to the Caribbean during the Cuban missile crisis, as the distance was deemed a hazard. The turbines aboard these boats were unreliable, and there was no wish to have their most advanced submarine being seen under tow. Subsequent developments would however be a more considerable concern to the US surface fleet. General Secretary Nikita Kruschev’s plan for the Soviet Navy was to be one that was capable of defending its own coasts using light warships armed with anti-ship missiles, and submarines which could stalk shipping lanes for enemy vessels. As opposed to Stalin’s views, Kruschev’s plan heavily favored the development of cruise missiles and submarines over a balanced fleet, and largely handicapped the development of larger warships.

The immediate products of this philosophy were the Echo class nuclear submarines, and to a lesser extent, the conventional Juliet class. These new boats carried heavy, anti-ship cruise missiles and were initially considered a serious threat to US carriers. They were not, however, without serious limitations. They required cooperating patrol planes to share radar data for over the horizon targets, and needed to stay on the surface for up to thirty minutes before carrying out the attack with their long range missiles. They were accordingly extremely vulnerable when operating in areas without a substantial Soviet air presence. The more advanced Charlie class materialized after Kruschev’s fall, and was capable of submerged launches, but of slower and short ranged missiles. With Kruschev gone, the Soviet Navy largely abandoned any plans of Atlantic convoy raiding to pursue building better defenses against American Polaris missile subs, and later to focus on denying potential enemies access to bastions where their own SSBNs patrolled. Largely under Admiral of the Fleet Sergei Gorshkov’s direction, the Soviet fleet would try to right itself to become a more balanced force, so that it might better assist Soviet foreign policy, and to build up a defense against wartime incursions from enemy aircraft carriers and modern nuclear submarines.

In spite of the limitations of the Soviet nuclear submarine fleet of the sixties, their growing capabilities would prompt the US into developing their anti-submarine forces even further. Throughout the sixties, new aircraft ASW tactics were employed to replace the old snorkel-chasing methods. A greater focus was placed on the use of sonobuoys, which could be used to survey larger patrol areas, and the newer versions of which were growing ever more sensitive and sophisticated. Greater coordination with surface vessels was also employed, with newer destroyers and frigates mounting considerably more powerful sonar systems. Overall, US nuclear subs would take up an ever more important role in anti-submarine warfare, massive new hydrophone lines were laid in strategically important areas, and the aircraft carrier was soon to take a primary position in anti-submarine strategy.

Viking

In the world of the nuclear submarine and the jet carrier air group, the S-2 Tracker was becoming an ever more inconvenient asset. As carriers began to carry an ever greater number of jet aircraft, there was some frustration with having to still carry stores of aviation gasoline for the S-2s. The situation was not improved by the retirement of the WWII era converted CVS, which would be entirely out of service by the early 1970s. As a result, the entire surface ASW framework was to be restructured. Among the earliest moves was to announce a competition for the S-2 replacement in 1964, under the designation VSX. The new plane was required to have at least twice the speed, twice the range, and twice the ceiling of the aging Tracker. Lockheed was among the most promising entrants due to their previous history in designing maritime patrol aircraft, though their lack of experience with carrier based aircraft saw them partner with LTV Aviation, and the new ASW gear was to be designed by Univac Federal Systems.

Lockheed’s Viking was a robust, high wing aircraft which featured a pair of turbofan engines for their power and fuel economy. The plane also carried nearly every modern airborne submarine detection system of the time. Its four crewmen operated the aircraft’s systems in coordination with a central, general purpose digital computer, which greatly aided the crew in processing the information gathered by the aircraft’s sensors. Further crew integration was accomplished through the use of multi-purpose displays that could show information from any of the aircraft’s crew positions. In addition to the MAD, radar, and sonobuoy systems, the plane was equipped with a FLIR system mounted to an extendable turret which was capable of detecting snorkeling, or near surface submarines and sea mines. To complement its sensors, the aircraft had a maximum speed of approximately 429 kts, a ceiling of 40,000 ft, and a maximum endurance of over six hours. Of the entries from Grumman, General Dynamics, and Convair, Lockheed’s design won out.

They were formally awarded the contract in 1969. The first of eight YS-3A prototype and pre production aircraft flew only three years after the contract was finalized in 1972, with the aircraft entering service two years later. This program was also the first to have a formalized set of milestones to ensure costs were kept low and technical risks were reduced. All program milestones were met ahead of schedule, and the plane was prototyped, built, and delivered in quantity in only five years. Their carriers too were modified to better suit ASW operations. In 1971, the USS Saratoga was the first to receive an ASW analysis center and support shops for ASW gear and weapons. All carriers but the older, smaller Midway class were able to receive the improvements. Prior to the introduction of the Viking, carriers operated S-2’s, with the introduction of the new aircraft vastly improving the anti-submarine capabilities of US carrier battle groups. The plane could perform an ASW search quickly at 35,000 feet at a speed of over 300 kts, a massive improvement over the S-2’s 135 kts at 10,000 ft. Even before considering the massive improvements in sensors and the centralized computer integration, the Viking could patrol truly massive stretches of ocean for a plane of its size. With a payload of four lightweight torpedoes and 60 sonobuoys, the Viking could fly out 826 nmi from its carrier, and conduct a two hour search before having to return. The use of external stores and airborne tankers could push this already phenomenal range out even further.

VS-21, the first S-3A squadron, was deployed aboard the USS John Fitzgerald Kennedy in the summer of 1975. During its Mediterranean deployment, the Kennedy was able to truly demonstrate the universal carrier concept. Previously, carriers were divided between the CVS, sub hunting carriers, and the CVA’s, which hunted everything else. The introduction of the Viking enabled the consolidation of all US carriers into CV’s, the new concept seeing carriers equipped for every conceivable mission. However, the S-3A was not the only newcomer to the ASW mission. The year prior to its first deployment saw the introduction of the Kaman Sh-2F Seasprite. This light anti-submarine helicopter would soon be found aboard most US warships, extending both their maximum search and offensive ranges. In short, the US surface fleet’s ASW capabilities had been thoroughly improved through the adoption of these two aircraft, well in advance of the predicted improvements in Soviet nuclear submarines.

In service, the S-3A was primarily a screening element for the carrier group and any surface groups it might be supporting. A US carrier group is typically deployed alongside independent surface action groups and nuclear submarines, these often being the outermost defenses for the carrier group. The carrier’s offensive range and ability to survey thousands of miles of ocean make it the center of naval operations, and the most well defended asset. It was the job of the outer forces to screen the path and potential approaches to the carrier from enemy submarines, and to a lesser extent surface ships, though those more often fell under the purview of other aircraft and vessels.

Given the distance between these forces, gaps inevitably form, and these areas are typically patrolled by aircraft. In wartime, the Viking could quickly fly out to these locations and deploy a grid of sonobuoys, which it could maintain for several hours before being relieved by other aircraft. In addition to screening the path of the carrier, the S-3A could also be tasked to patrol the open ocean to search for older cruise missile submarines, which had to surface for long periods to fire their weapons. The S-3 would eventually receive Harpoons for this role, but initially, it would carry Hydra 2.75 inch rockets or unguided bombs. By the late 70s, these submarine ‘Shaddock’ missiles were easily defeated by the new EW systems and defensive weapons added to destroyers, cruisers, and carriers, but they still posed a threat to lighter warships and shipping. In addition to open ocean patrols and barrier searches, the Vikings could be quickly dispatched to support patrolling frigates and destroyers which were tracking submarines.

Though the Soviet fleet consisted of a large number of these older submarine classes, new models of Soviet nuclear submarines would pose a greater challenge. A change in design philosophy would see a shift in focus away from achieving the best possible speed, to a balanced approach which placed greater importance on lower acoustic emissions. When commissioned in 1974, K-387, a Project 617RT ‘Victor II’, was the first Soviet nuclear submarine to incorporate rafted equipment. With its turbines suspended on vibration dampening mounts and its hull clad in anechoic rubber tiles, it was remarkably quieter than its forebearers. Further improvements to this class resulted in the Project 617RTM ‘Victor III’, with the first boat being commissioned in 1978. However, sound reduction was only marginally improved, with much of the focus being placed on new sensors, with the main mission for the sub being ASW. With 48 total Victors of all classes being produced, it represented the modern workhorse of the Soviet submarine force. More concerning to the carrier, however, were the successors to the Echo and Charlie class SSGN. The Project 949 ‘Oscar’ was a massive vessel which carried 24 P-700 ‘Shipwreck’ missiles, three times as many missiles as the Echo. Capable of submerged launches and engaging surface targets at long range, the Oscar lacked the handicaps of the earlier boats, and its state-of-the-art missiles boasted high speed and countermeasure resistance. A single Oscar could put the air defenses of a carrier battle group to the test, and thus long range anti-submarine screening became key for naval planners. The character of the Soviet submarine force of the eighties was rather peculiar, being composed mostly of obsolete to somewhat up to date vessels, but with a small and growing pool of cutting edge submarines.

These ever-advanced models of Soviet submarines were anticipated and largely matched by the US Navy’s efforts to build a defense against them. All new warships possessed powerful new sonar systems and light ASW helicopters, and the carrier based S-3A sat at the center of fleet-wide anti-submarine strategy.

Into the 80s

While the S-3A proved an incredible new addition to the fleet, it soon encountered an unexpected challenge. As a result of the post-Vietnam defense cuts, the spare parts program for the Viking was among the worst affected. Stocks of replacement parts began to grow tight by 1977, though they would not pose a serious issue until the turn of the decade. As a result of stricter rationing of components, the mission readiness level of the Viking squadrons often fell to below 40% in 1981. However, the problem was soon identified and the procurement of more replacement parts began the following year, along with a new series of maintenance programs to increase readiness. Thanks to these efforts, the mission readiness of these squadrons climbed to 60% in 1983 and rose to 80% in the coming years, the highest in the fleet.

While the Navy was procuring additional parts, they also initiated a program to drastically improve the offensive and sensor capabilities of the aircraft. The Weapon Systems Improvement Program would seek to prepare the S-3 Viking for its service into the new millennium. Most of these improvements were focused around the aircraft’s sensor systems, most notably its new inverse synthetic aperture radar, which boasted a much higher capability in regards to periscope and snorkel detection, and its acoustic sensor suite. The acoustic data processor was improved through the use of a standardized naval signal processor which ran on a software shared among new naval maritime patrol aircraft, a new sonobuoy receiver boosted the available channels from 31 to 99, and it received a new, more reliable tape recorder for storing gathered acoustic data.

In addition to its sensor improvements, the Viking received the new ALE-39 countermeasure system, and its electronic support measures were improved to allow better classification of contacts by their radar and radio emissions. Lastly, it finally received the capability to utilize the AGM-84 Harpoon missile, with the pair of missiles being mounted on the outer hardpoints. With a range of approximately 75 nmi’s, the sea skimming Harpoon could prove very difficult to detect and shoot down. As more effective air defenses against sea skimming missiles would not become widespread for almost a decade, the inclusion of this weapon would make the Viking a considerable anti-surface asset, along with its already impressive anti-submarine capabilities.

The sum of these upgrades would end up seeing the modified aircraft identified as S-3B’s, as squadrons began to receive the improvements in 1984. In addition to these upgrades and after the parts shortage, the scope of duties for the aircraft began to grow over the years. Among the first new tasks assigned to the Viking was to act as an airborne tanker. The long endurance of the aircraft, coupled with its incredibly fuel efficient turbofan engines, made it extremely capable in the new role. Carrying ‘buddy stores’, the S-3 could increase the range and endurance of cooperating carrier-borne aircraft in a much more efficient manner than the Ka-6d tanker, or a fighter or strike aircraft carrying the fuel tank and drogue system.

As the 1980s drew on, the Navy began to push the operational limits of the aircraft out ever further, and to great success. The S-3 took on the aerial mining mission, and during the Northern Wedding and United Effort exercises of 1982 and 1983, the operational search range of the Viking was pushed out to 1000 nmi with the use of airborne tankers. Even more noteworthy, they were able to detect and track submarines at that range during the exercise. While the S-3 Viking was initially introduced to serve a single, and very specialized purpose, the aircraft would end up proving extremely versatile and provided a number of new services to the carrier fleet, far beyond the expectations of its designers.

Operation Desert Storm and Late Career

As the Cold War came to a close, events in the Middle East soon culminated in the largest armed conflict since the end of the Vietnam war. As Iraq invaded the neighboring country of Kuwait over oil disputes, a coalition was built among Arab and Western militaries to oust Iraqi forces from Kuwait and deal a serious blow to Saddam’s forces. Along with a massive USAF contingent, the US Navy would deploy six aircraft carriers in order to dislodge the Iraqi army from Kuwait. Of the force, USS Kennedy, Saratoga, America, Ranger, and Roosevelt carried embarked squadrons of S-3B’s. USS Midway lacked a squadron of Vikings, as it did not possess an ASW analysis center.

A total of 43 Vikings would be active across these carriers by February 1991, where they would serve in a number of roles. Ironically, due to Iraq’s lack of a submarine force, ASW was not a role they performed during this conflict. These aircraft flew a total of 1,674 sorties between January 17 and February 28, 1991. The majority, with 1043 flights, were aerial refueling missions supporting other coalition aircraft. However, they also flew a number of reconnaissance, electronic warfare, and several surface air combat patrol sorties, these numbering 263, 101, and 20, respectively. The rest of their flights were categorized as unspecified support missions, or ‘other’.

Apart from aerial tanker duties, these Vikings flew most of their patrols to survey the Persian gulf, in order to track what few warships Iraq had, and to mark the location of mines. Some Vikings were also involved in the search for Iraq’s short range Scud ballistic missiles, a great fear at the time being that some of them may have carried chemical weapons payloads. They also performed a number of unorthodox tasks. For instance, the US carrier air groups could not electronically receive their daily air tasking orders from the coalition headquarters in Riyadh, Saudi Arabia. Their solution was to dispatch an S-3B to pick them up on a near daily basis. Among the most imaginative uses of the aircraft was in delivering photos from carrier based reconnaissance services to units fighting on the ground. This was done by placing the photos in an empty sonobuoy tube and parachuting them to units. One Viking also sank an unidentified class of Iraqi patrol ship on February 20, 1991, after dropping three unguided mk82 bombs on it. Offensive patrols were comparatively restricted and were conducted in areas with limited anti-aircraft threats.

After the end of the war in the Gulf, the S-3B was used for continued surveillance of the area and to uphold the sanctions on Iraq during Operation Desert Shield. It likewise performed similar support roles in the numerous NATO air operations over the former Yugoslavia. Their roles during those conflicts were almost entirely restricted to airborne tanker duties, though a number of Vikings, including a specialized ELINT model, performed signals intelligence missions.

As a result of the collapse of the USSR, the global submarine threat to the US Navy declined to almost nothing, and thus the Viking squadrons transitioned from anti-submarine, to surface control units to better represent their more multipurpose role. They would eventually discard their ASW equipment, with the anti-submarine mission being made the purview of the US submarine fleet and long range maritime patrol squadrons. Several new upgrades were initiated during the turn of the millennium, mostly in regards to new avionics and improvements to carrier landing aids. They would also include the Maverick Plus upgrade, which would enable the S-3B to use IR guided models of the AGM 65 missile, and the AGM-84H family of ground attack missiles. However, after the KA-6D left the service in the late 90s, the Viking would become the fleet’s primary aerial tanker.

The last major operation where the Vikings saw use was during the later invasion of Iraq, during which they primarily acted as tankers. There were, however, some strikes carried out by S-3Bs using the new Maverick Plus system, but these were comparatively rare. As the 2000’s came to a close and the US carrier force wished to divest itself of all but the most essential airframes, the Viking had fully left the service by 2010. The fleet was thus without a dedicated aerial tanker, and instead employed F/A-18s carrying ‘buddy stores’ to refuel other fighters.

Perhaps its later most publicized use was in delivering President George H.W. Bush aboard the carrier USS Abraham Lincoln after the invasion of Iraq. There, he delivered an address to the nation regarding the end of Operation Iraqi Freedom, in front of the long derided banner which simply read ‘Mission Accomplished’.

NASA

While the Viking’s military career came to a close, a number of aircraft were transferred to NASA as test aircraft in 2004. One of these planes was further developed into a dedicated testing platform in 2006 and was subsequently demilitarized. Most of the existing avionics were replaced with more contemporary civilian equipment and provisions for adding experimental equipment were installed. The Viking was given the civil air registration code N601NA and would see heavy use by the administration for the next 15 years, with the remaining Vikings being used for ground testing.

The plane was used for a variety of missions regarding aeronautic safety, aerodynamic studies, and Earth studies. Operating out of the Glenn research center, the plane tested engine icing under harsh conditions, flew communication equipment tests over much of the US to determine FAA guidelines for unmanned aircraft, and flew over the Great Lakes to study algal blooms. This Viking was the last airworthy example of the entire line, and was finally retired in July of 2021. NASA has since donated the plane to the San Diego Air and Space Museum.

Operating Characteristics

The high and broad wings of the Viking presented good low speed flight characteristics and high maneuverability. This was also aided by the lateral control system of the aircraft, which consisted of a set of small outboard ailerons, a pair of spoilers above the wing and one on the underside, and a leading edge flap. Pilots in both the Navy and NASA test programs praised the responsiveness and stability these systems provided. This ability was well valued during low altitude MAD searches and during low level communications testing for NASA and the FAA. However, at higher speeds, pilots needed to be aware of a degree of oversensitivity, as the aircraft did not possess a fly by wire system.

The Viking had an extremely high carrier boarding rating thanks to its dynamic lift system, which in combination with the spoilers, gave the pilot a high degree of control during their final approach. The slow descent of the aircraft also permitted both the pilot and the LSO considerable time to make alterations. This is not to say this was a simple affair, as the aircraft was fairly sensitive to the air disturbance that forms immediately behind the moving carrier, and thus the pilot is still required to make the approach with caution. The engines had to be practically idled on the glide slope, and still often felt overpowered. The DLC system was essential, though the flaps were not, with many recoveries being flap up. Getting off the carrier was a far easier affair, as the aircraft only had a speed requirement of 120 kts under a normal load. Off wind catapult launches were made easily and some pilot and ground crew would remark that the Viking seemed like it could just fly off on its own. In both launching and recovery, the aircraft was remarked to handle well under poor conditions.

The addition of an APU in this aircraft greatly simplified and accelerated the start up procedure, as it did not require the pilot to request external power from the deck crew. A relatively simple start up enabled the aircraft to be ready some 15 to 20 minutes before its scheduled launch, and helped in speeding up the turn-over in deck operations. The only inconvenience the aircraft presented was that its low mounted engines were considerably quieter than most other embarked aircraft, meaning ground crew needed to pay particular attention to these aircraft as they moved across the deck. In short, the S-3 was very well suited to carrier operations.

A high level of crew cooperation was possible on the Viking thanks to the centralized nature of its avionics, sensors, and weapon systems. In managing all of these functions through its central computer, most crew functions were visible across all stations and, in some cases, could actually be managed between them. This was primarily achieved through the multipurpose displays at each station, which allowed crewmembers to share information. This made the SENSO and TACCO stations far more capable than they were on other aircraft, allowing for some division and management of the workload. The TACCO position likewise possessed a high degree of integration with the pilot and copilot, and in certain autopilot modes, could guide the aircraft to the weapon release point. All stations effectively had a high degree of situational awareness outside the aircraft, as the multipurpose displays could be set to show various airborne, surface, and subsurface contacts relative to their positions from the aircraft. The computer system itself proved fairly easy to manage, and designed with self-maintenance in mind. In the event of a system error, the computer could run a diagnostic and be reset in flight. Thanks to this level of digital integration, the Viking was viewed as being as capable as a number of patrol aircraft with significantly larger crews.

In the submarine hunting role, the Viking was in no shortage of equipment. The primary means of conducting an anti-submarine search were its sonobuoys. The aircraft carried a variety of these devices, which allowed for passive listening, or actively sending out an echolocating ping which revealed the positions of nearby submarines. These were often arrayed out in a grid like pattern in an aircraft’s patrol area to allow for the surveillance of a much larger area. They were typically dropped in line-like, or triangular patterns when used to try and get an accurate fix on the submarine’s location. Through acoustic analysis, the Viking was able classify submarine contacts by comparing them to existing sound profiles and was capable of gathering new profiles on vessels which had not yet had one compiled. Sonobuoys were usually dropped from the aircraft’s cruising altitude of 35,000 ft, though often from lower altitudes when a contact had been found and a finer pattern of the devices needed to be sown. The sonobuoy system was the first of its kind capable of accurately pinpointing the position of each device.

Sonobuoys provided a screen through which a transiting submarine could be detected, though they were not used for basic open ocean searches. The limited effective range of the individual devices meant that they were used for screening areas ahead of surface groups, filling gaps between other patrol areas, and investigating contacts that were beyond the range of other warships. The aircraft could hand off its sonobuoys to other aircraft from a shared channel, and could receive information from other, off-aircraft sensor sources through their datalink. Thus, in the submarine hunting role, the aircraft could either be a proactive tool, in performing its own searches, or reactive, in responding to suspicious or identified subsurface contacts from other aircraft and vessels. In concert with more modern anti-submarine assets, like the Spruance class destroyer or underwater hydrophone lines, the Viking could prove an incredible asset well beyond the limitations of its own sensors. The Viking was one of, if not the, best equipped ASW aircraft of the entire Cold War. Designed primarily around countering the threat of nuclear submarines, it would of course prove even more capable against diesel-electric submarines which presented more opportunities for detection.

In conjunction with sonobuoys, the aircraft possessed its radar, FLIR optics, and a magnetic anomaly detector. The radar of the aircraft was designed to detect periscopes and snorkels deployed by near surface submarines. The key was to look for contacts that either appeared or disappeared from the scope without explanation, and was otherwise a very straight forward system. The FLIR sensor was used to detect heat sources, and in the submarine hunting mission, was used to spot submarines at a shallow depth, and the extended snorkel and exhaust of diesel-electric submarines recharging their batteries. Last was the MAD, which detected the magnetic field of a submarine, which caused slight disruptions in measurements of the earth’s magnetic field, hence the anomaly. This was the only sensor which required the aircraft to fly low, and the limited range of the sensor also meant a contact was typically only revealed if it was overflown. The radar and infrared systems were also important tools in conducting long range surface reconnaissance for the entire fleet. These systems were also necessary in providing targeting data for the Harpoon anti-ship missile.

In employing weapons, the majority of the work was done through the TACCO position. This crewmember assigned weapons to targets, and in coordination with the pilot and copilot/COTAC, delivered them. Originally, this meant he would deploy the Mk.46 lightweight torpedoes and depth charges, with the plane being capable of deploying nuclear models as well. Unguided munitions, typically Zuni rockets, Mk 82 iron bombs, or Mk 20 Rockeye cluster bombs, were the responsibility of the pilot and would have been used against surfaced guided missile submarines, or damaged warships. Later in the aircraft’s career, the TACCO would deploy mines, launch AGM 84 Harpoons, and later operate a variety of air to ground missiles with the introduction of the Maverick Plus upgrade.

The aircraft later excelled as an airborne tanker, where its ability to operate for long periods and at range from the carrier were crucial. The task was relatively simple enough, fly straight ahead while offloading fuel onto another aircraft through a hose and basket fuel transfer line. The asymmetric load of the fuel tank and drogue mount required constant trimming, which grew worse as the tank was drained, but this was a largely simple job the plane was well suited for.

Construction

The S-3 was a high wing, twin engine, carrier based anti-submarine aircraft. It possessed a very durable semi-monocoque airframe with three folding flight surfaces, being the wings and the vertical stabilizer. The fuselage was wide enough to permit the fitting of a considerable set of ASW gear, and an internal weapons bay. The general construction of the aircraft was fairly conventional in comparison to other carrier based aircraft. Lockheed was the primary contractor for the aircraft,  with LTV building the wings, engine pods, tail assembly, and landing gear, while Univac provided the digital computer and some of the avionics.

The nose of the aircraft contained the radar, followed by the cockpit which seated the pilot and copilot, behind them were the weapons and sensor operators. Aft of the crew sat the forward avionics bay, which itself was over the internal weapons bay, and to the rear of it all was the MAD boom and rear avionics bay. On the underside of the aircraft were the sonobuoy shoots, which in addition to the 48 outer slots, held additional internal stores for 12 more devices. All critical systems had redundancy built in.

The landing gear, and catapult launch bar, were derived from those of the LTV F-8 Crusader and A-7 Crusader II. These consisted of a forward, upward retracting gear and two rear landing gear which retracted inward toward the fuselage. These are hydraulically actuated, though in an emergency, they could be extended by bypassing the hydraulics and letting gravity, and a leaf spring to force the gears into the extended position.

The wings of the aircraft were designed to permit a high degree of control and stability at both low and high speeds at low engine power, up to the maximum permitted speed of 429 kts. These were mounted high on the fuselage and possessed a high aspect ratio of 7.73 and a rearward sweep of 15 degrees. The wings consisted of an outer panel, which could fold inward, and an inner panel, roughly a third the length of the outer panel, which contained a fuel tank, and supported an engine nacelle and a pylon which could fit external fuel or weapons. The tall vertical stabilizer also folded down and to the port side to permit the aircraft to fit the carrier’s hangar doors. The extendable airborne refuel probe was stored just ahead of the wings.

The Viking possessed an unusual flight control system which combined six large spoilers with a set of small ailerons and a leading edge flap. Lateral control was greatly aided by the inclusion of the spoilers in combination with the leading edge flap, which permitted effective control at very low speeds with low engine power settings. All control surfaces on the aircraft were deflected using hydraulically actuated servos, with an artificial feel system designed to give the pilot an idea of the extent of control surface deflection. These controls did however prove to be somewhat oversensitive at high speed. Overall, the control surfaces were very effective on patrols at low speed, though they could prove rather clumsy in a carrier landing pattern. This was largely due to the overpowered engines, which gave the aircraft a somewhat unorthodox glide slope and its large wings increased its sensitivity to the ‘burble’ air disruption behind the carrier. To compensate for this, the Viking was equipped with a dynamic lift control system which provided 12 degrees of speed brake extension and retraction through the upper spoilers.

The S-3 was powered by a pair of either General Electric T34-GE-2 or T34-GE-400A high bypass turbofan engines. These both produced 9,275 pounds of thrust at sea level, and the former was used only on pre-production aircraft. These engines used a dual-rotor, single stage, front-fan configuration with a bypass ratio of 6.23 to 1. These were divided into four major sections, being the fan, compressor, combustor, and turbine. The fan was driven by the low pressure turbine and produced 85 percent of the engine’s total thrust. The compressor was composed of 14 stages which compressed air prior to the combustion section, and provided the air for the pneumatic systems aboard the aircraft. The combustor section was where the compressed air was mixed with a fuel air mixture and ignited. The resultant flow drove the high and low pressure turbines within their own section, the high pressure turbine being responsible for driving the compressor, and the low, the fan. The air flow continues out the back of the low-pressure turbine to comprise the remainder of the engine’s thrust.

The aircraft was fitted with a number of surface and subsurface sensors. The Viking originally possessed an AN/APS-116 search radar, which was primarily designed to detect the masts of submarines near the surface, but doubled as a general purpose surface search radar. This was replaced on the S-3B with the APS-137 inverse synthetic aperture radar which was more than twice as effective at detecting low RCS masts and had improved surface search capability. Specifically, it gained the ability to identify surface vessels at long range by comparing radar returns to existing 2D profiles of vessels. The aircraft also carried an AN/ASQ-81 magnetic anomaly detector fitted to an extendable boom at the rear of the aircraft often called the ‘Stinger’. The boom allowed the sensor to be placed farther away from ferrous objects on the aircraft, which might interfere with any measurements taken. They also carried the OR-89 FLIR sensor, it being mounted in an extendable turret on the forward, starboard side of the aircraft. The sensor would display surface and near surface contacts, making it extremely useful in detecting mines, submarines at a shallow depth, and the exhaust of diesel-electric submarines charging their batteries.

What could be considered the primary anti-submarine sensor were the aircraft’s sonobuoys. Up to 60 could be carried in the chutes that sat flush with the outside of the aircraft and internal stowage. The aircraft communicated with minimal signal emissions and was capable of displaying their exact positions. Data from the devices was processed using an OL-82/AYS data processor and, coupled with its original receiver, was initially capable of monitoring 31 buoys. When upgraded, the acoustic data processor incorporated a new standardized UYS-1 signal process which had improved reliability and had parts and software commonality with other ASW platforms. A more advanced sonobuoy reference system, AN/ARS-2, would also boost the number of usable sonobuoy channels from 31 to 99 and an automatic channel scanning capability to search for available RF channels. The last upgrade to this system saw the analogue tape recorder switched from AN/ASH-27 to the AQH-4(V)2, which was both smaller, more reliable, and was compatible with the new UYS-1 signal processor.

The aircraft’s countermeasures initially came in the form of the AN/ALR-47, a passive sensor which displayed radar emissions from search and track radars. This was later supplemented with the ALE-39, which included countermeasure dispensers. It also received electronic support measures, which allowed it to detect a wider variety of radar emissions to allow it to classify their emitters. In the event of being shot down, the aircraft was equipped with ejection seats. These could be used on the ground while the aircraft was still, and had a preset ejection sequence to prevent any collisions in air.

All of these systems were managed through a single Univac AN/AYK-10 digital computer. The system allowed for a much higher ability to process information compared to the isolated systems in use on virtually all other maritime patrol craft. Additionally, and perhaps much more importantly, it allowed the crewmembers to display information from their own stations to one another through a set of multipurpose display screens at every station. This allowed for the sharing of most sensor data across all four positions, though it was more limited in the case of sonobuoy readouts, as they were half displayed on a secondary screen at the SENSO station. These displays would give crews the ability to coordinate during surface and subsurface searches, and improve planning when preparing to attack. This was particularly valuable to the copilot/COTAC, whose job was to essentially direct the aircraft in achieving its mission. The addition of this system essentially gave them access to every senor and allowed them to work closer with the TACCO when it came time to deploy weapons.

Initially, the Viking could be armed with up to four Mk 46 torpedoes, being either the Mod 1 or Mod 5 NEARTIP during the 1980s. Both types measured 8.5 ft long with a diameter of 12.75 inches, and both carried a 95 lb warhead. The Mod 1 possessed a maximum speed of 45 kts,with the NEARTIP being considerably faster. The NEARTIP provided better tracking of faster targets and better countermeasure rejection, having incorporated a new sonar transducer, control and guidance group, and a new engine which switched from solid propellant to liquid monopropellant. The Viking would also receive the new electric Mk 50 torpedo in the early nineties, but it would shortly after transition away from the ASW mission. There were provisions for mounting up to four torpedoes internally from hardpoints rated up to 600 lbs each. The bomb bay could also carry up to four mines and depth charges, or two B57 nuclear depth charges.

The pair of external hard points could carry a combination of weapons, external fuel tanks, and airborne refueling systems. Initially, this was restricted only to unguided weapons and fuel tanks. Each hardpoint had a mounting capacity of 2,500 lbs and could carry up to three bombs through the use of the TER-7 bomb mount. The S-3B upgrade would allow the aircraft to use the AGM 84 Harpoon and was able to carry two of these sea skimming missiles. The last major upgrade package, which was installed around 2002, included a variety of avionics improvements, and the Maverick Plus system. This allowed the Viking to mount the AGM 65 Maverick, one per hardpoint, and the AGM-84E SLAM. The Maverick was to be used mostly against light shipping, with the SLAM providing stand off capability against ground targets. The SLAM could be guided manually after launch if a guidance pod was installed on one of the outer hardpoints. Both missiles were otherwise supported and targeted through a common display.

The S-3B could use any of the AGM-84’s in the Navy’s arsenal by the time of its introduction. The first of these was the Block 1B introduced in 1982, which had improved radar guidance allowing it to fly at lower altitudes. The subsequent 1C entered service in 1984 and incorporated a denser fuel, which increased its range by five nautical miles out to 80 nmi when launched from sea level, and added an alternate pop-up attack mode. The 1D entered service in 1992, with the lengthened missile possessing a range of 150 nmi and re-engagement capability, which allowed the missile to circle back to its target if it was deceived by chaff or electronic countermeasures on its first pass.

These sea skimming, turbojet powered missiles were exceptionally difficult to detect and intercept during the Cold War and flew at a constant Mach .85. These utilized active radar terminal homing, carried a 510 lb high explosive warhead, and had a flight reliability of over 93 percent.

Conclusion

With the exception of the parts shortage, the Viking can be said to be among the most reliable and versatile tools the US Navy has ever possessed. The aircraft proved a phenomenally capable anti-submarine aircraft, which entered service long before high capability threats entered service in the Soviet Navy. When that particular threat had gone, the plane continued to serve ably, as a tanker, a reconnaissance aircraft, and limited strike aircraft. Finally, the venerable aircraft ended its career as a research aircraft.

S-3A Viking	Specification
Engine	T34-GE-400A
Maximum Continuous Engine Output (Maximum)	6,690 lbs (7,365 lbs for 5 minutes)
Combat weight at catapult	44,947 lbs
Gross Weight	36,574 lbs
Empty weight	26,581 lbs
Range [4x Mk.46 60xSonobuoys]	2,506 nmi
Combat radius [4x Mk.46 60xSonobuoys]	826 nmi for 6.9 hours at 346 kts
Maximum speed	429 kts at sea level
Crew	Pilot, Copilot/COTAC, TACCO, SENSO
Length (Folded)	53.33 ft (49.42 ft)
Height (Folded)	22.75 ft (15.25 ft)
Wingspan (Folded)	68.67 ft (29.50 ft)
Wing Area	598 sq.ft

S-3 variant	General Description	Number built/converted
YS-3A	Prototype/Preproduction	8 built
S-3A	ASW Aircraft	180 built
S-3B	ASW/ASuW Aircraft	160 converted from S-3A
US-3A	Cargo Aircraft	4 converted from YS-3A
KS-3A	Airborne Tanker	1 converted from YS-3A
ES-3A	ELINT Aircraft	16 converted from S-3A

​

Viking Squadrons
VS-21 ‘Fighting Redtails’		VS-31 ‘Topcats’
VS-22 ‘Checkmates’		VS-32 ‘Maulers’
VS-24 ‘Scouts’		VS-33 ‘Screwbirds’
VS-27 ‘Grim Watchdogs’		VS-35 ‘Blue Wolves’
VS-28 ‘Gamblers’		VS-37 ‘Sawbucks’
VS-29 ‘Dragonfires’		VS-38 ‘Red Griffins’
VS-30 ‘Diamondcutters’		VS-41 ‘Shamrocks’

(wikimedia, popular patch)

Credits

• Article written by Henry H.
• Edited by  Henry H. and Stan L.
• Ported by Henry H.
• Illustrated by Hansclaw

Illustrations

Gallery

 

Sources

Primary

Standard Aircraft Characteristics Navy Model S-3A Aircraft. Commander of the Naval Air Systems Command. NAVAIR 00-110AS3-1. January 1973.

NATOPS Flight Manual Navy Model S-3B Aircraft. Commander of the Naval Air Systems Command. NAVAIR 01-S3AAB-1. September 2000.

NATOPS Weapon System Manual Navy Model S-3B Aircraft. Commander of the Naval Air Systems Command. NAVAIR 01-S3AAB-1.1. December 2002.

Fiscal year 1976 and July-September 1976 transition period authorization for military procurement, research and development, and active duty, selected reserve, and civilian personnel strengths : hearing before the Committee on Armed Services, United States Senate, Ninety-fourth Congress, first session, on S. 920

NASA fiscal year 2010 budget request : hearing before the Subcommittee on Science and Space of the Committee on Commerce, Science, and Transportation, United States Senate, One Hundred Eleventh Congress, first session, May 21, 2009.

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Department of Defense appropriations for 1984 hearings before a subcommittee of the Committee on Appropriations, House of Representatives, Ninety-eighth Congress, first session / Subcommittee on the Department of Defense.

NASA’s aeronautics R & D program : status and issues : hearing before the Subcommittee on Space and Aeronautics, Committee on Science and Technology, House of Representatives, One Hundred Tenth Congress, second session, May 1, 2008.

Department of Defense authorization for appropriations for fiscal years 1988 and 1989 : hearings before the Committee on Armed Services, United States Senate, One hundredth Congress, first session on S. 1174.

Department of Defense appropriations for 1985 hearings before a subcommittee of the Committee on Appropriations, House of Representatives, Ninety-eighth Congress, second session / Subcommittee on the Department of Defense.

Department of Defense authorization for appropriations for fiscal year 1983 : hearings before the Committee on Armed Services, United States Senate, Ninety-seventh Congress, second session, on S. 2248.

Secondary

Chambers, Joseph R.. Partners in freedom: contributions of the Langley Research Center to U.S. military aircraft of the 1990’s.

Brown, Ronald J. Humanitarian operations in northern Iraq, 1991: with marines in Operation Provide Comfort.

Knaak, Jerry. A Hunting We Will Go. Naval Aviation News. March-April 1997.

Vikings Sweep the Seas & Viking. Naval Aviation News February 1983.

LSO School and the Paddles’s Profession. Naval Aviation News V70, November-December.

Benjamin, Dick. A Sea Rover for ASW. Naval Aviation News January 1972.

Richman, John P. The Viking at Home in the Fleet. Approach, July 1975.

Francillon, Rene J. Lockheed Aircraft Since 1913. Naval Institute Press. 1987.

Polmar, Norman & Moore, Kenneth J. Cold war Submarines The Design and Construction of U.S. and Soviet Submarines. Potomac Books. 2004.

Polmar, Norman. Aircraft Carriers a History of Carrier Aviation and its Influence on World Events Volume II 1946-2005. Potomac Books. 2007.