Lockheed S-3 Viking

The Lockheed S-3 Viking is a 4-crew, twin-engine turbofan-powered jet aircraft that was used by the U.S. Navy primarily for anti-submarine warfare.

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.

On 21 January 1972, the first prototype performed its maiden flight in the hands of military test pilot John Christiansen.

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.

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.

Entry is via a hatch/ladder folding down out of the lower starboard side of the fuselage behind the cockpit, in between the rear and front seats on the starboard side.

When the aircraft’s anti-submarine warfare (ASW) role ended in the late 1990s, the enlisted SENSOs were removed from the crew.

In tanker crew configuration, the S-3B typically flew with a pilot and co-pilot/COTAC.

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 seat 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 callipers 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.

Variants

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

The ES-3A Shadow was designed as a carrier-based, subsonic, all-weather, long-range, electronic reconnaissance (ELINT) aircraft. 16 aircraft were modified, replacing the EA-3B Skywarrior, and 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 450 KTAS to 405 KTAS 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.

KS-3B

Proposed air tanker based on S-3B and utilizing the buddy refuelling system, not built.

US-3A

S-3A modified for carrier onboard delivery, capacity for six passengers or 4,680 lb (2,120 kg) of cargo, retired in 1998.

Aladdin Viking

Conversion of six aircraft for overland surveillance and Elint missions.

May have dropped ground sensors in the Bosnian War.

Beartrap Viking

S-3Bs fitted with still-classified modifications.

Calypso Viking

Proposed anti-smuggling variant, not built.

Gray Wolf Viking

One aircraft fitted with AN/APG-76 radar in a modified cargo pod under the wing.

Also dubbed Seastars in reference to E-8 Joint STARS.

Orca Viking

Avionics testbed.

Outlaw Viking

One S-3B fitted with Over-the-horizon Airborne Sensor Information System (OASIS III), returned to regular S-3B in 1998.

NASA Viking

One aircraft was transformed into a state-of-the-art NASA research aircraft.

The Navy’s Fleet Readiness Centre, Southeast and a Boeing facility in Florida enhanced the plane by adding commercial satellite communications, global positioning navigation and weather radar systems.

They installed research equipment racks in what was once the plane’s bomb bay.

NASA’s S-3B Viking is equipped to conduct science and aeronautics missions, such as environmental monitoring, satellite communications testing and aviation safety research.

Specifications

Crew

4 

Length

53 ft 4 in (16.26 m)

Wingspan

68 ft 8 in (20.93 m)

Width

29 ft 6 in (8.99 m) folded

Height

22 ft 9 in (6.93 m)

Height tail folded

15 ft 3 in (5 m)

Wing area

598 sq ft (55.6 m2)

Aspect ratio

7.73

Airfoil

Root

NACA 0016.3-1.03 32.7/100 mod

Tip

NACA 0012-1.10 40/1.00 mod

Empty weight

26,581 lb (12,057 kg)

Gross weight

38,192 lb (17,324 kg)

Max take-off weight

52,539 lb (23,831 kg)

Fuel capacity

Internal fuel capacity

1,933 US gal (1,610 imp gal; 7,320 L) of JP-5 fuel

External fuel capacity

2 × 300 US gal (250 imp gal; 1,100 L) drop tanks

Powerplant

2 × General Electric TF34-GE-2 turbofan engines,

9,275 lbf (41.26 kN) thrust each

Performance

Maximum speed

429 kn (494 mph, 795 km/h) at sea level

Maximum speed

Mach 0.79

Cruise speed

350 kn (400 mph, 650 km/h)

Stall speed

97 kn (112 mph, 180 km/h)

Range

2,765 nmi (3,182 mi, 5,121 km)

Combat range

460.5 nmi (529.9 mi, 852.8 km)

Ferry range

3,368 nmi (3,876 mi, 6,238 km)

Service ceiling

40,900 ft (12,500 m)

Rate of climb

5,120 ft/min (26.0 m/s)

Wing loading

68.5 lb/sq ft (334 kg/m2)

Thrust/weight

0.353

Armament

Up to 4,900 lb (2,220 kg) on 4 internal

&

2 external hard points, including:

10 × 500 lb (227 kg) Mark 82 bombs

2 × 1000 lb (454 kg) Mark 83 bombs

2 × 2000 lb (908 kg) Mark 84 bombs

6 × CBU-100 cluster bombs

2 × Mark 50 torpedoes

4 × Mark 46 torpedoes

6 × mines

Or

Depth charges

2 × B57 nuclear bombs (depth charges)

2 × AGM-65E/F Maverick missiles

2 × AGM-84D Harpoon missiles

1 × AGM-84H/K SLAM-ER missile

The underwing hardpoints can also be fitted with unguided rocket pods

Or

300 US gal (1,136 L) fuel tanks.

Avionics

AN/APS-116 sea search radar, maximum range 150 nmi (173 mi, 278 km)

Upgraded on S-3B to AN/APS-137 Inverse Synthetic Aperture Radar (ISAR)

OR-89 forward looking infrared (FLIR) camera with 3× zoom

AN/ARS-2 sonobuoy receiver with 13 blade antennas on the airframe for precise buoy location (Sonobuoy Reference System)

AN/ASQ-81 magnetic anomaly detector (MAD)

AN/ALR-47 Electronic Support Measures (ESM) emitter-location system, with boxy receiver pods fitted to the wingtips, to locate adversary communications and radar transmitters

AN/ASN-92 Inertial navigation system (INS) with doppler radar navigation and TACAN

Up to 60 sonobuoys (59 tactical, 1 Search and Rescue).