Partners in Freedom

		Lockheed S-3 Viking


Specifications Manufacturer Lockheed Date in service February 1974 Type Antisubmarine warfare, antisurface warfare, electronic warfare, and antimine warfare Crew Four Engine General Electric TF34-GE-400 Users U.S. Navy Dimensions Wingspan . . . . . . . . . . . .68.7 ft Length . . . . . . . . . . . . . . 53.3 ft Height . . . . . . . . . . . . . . 22.8 ft Wing area . . . . . . . . . . 598 sq ft Weight Empty . . . . . . . . . . . .26,864 lb Max takeoff . . . . . . . .52,539 lb Performance Max speed . . . . . . . . . 450 knot Range . . . . . . . . . . . .2,300 n mi

		Highlights of Research by Langley for the S-3 Flutter clearance was obtained for the S-3 during tests in the Langley 16-Foot Transonic Dynamics Tunnel. Spin and spin recovery characteristics of the S-3 were evaluated and found to be satisfactory during tests in the Langley 20-Foot Vertical Spin Tunnel. Lockheed (now Lockheed Martin) S-3 Viking aircraft are tasked by carrier battle group commanders to provide antisubmarine warfare (ASW), antisurface warfare (ASUW), surface surveillance and intelligence collection, electronic warfare, mine warfare, coordinated search and rescue, and fleet support missions such as airborne refueling. The S-3B aircraft carries surface and subsurface search equipment with integrated target acquisition and sensor coordinating systems that can collect, process, interpret, and store ASW and ASUW sensor data. It has a direct attack capability with a variety of armament, including the Harpoon missile. During operation Desert Storm, the versatility of the S-3 enabled it to serve a variety of roles. It flew hundreds of sea surveillance missions to enforce the economic blockade of Iraq and secure the seas surrounding the battle groups. Mine detection was an especially critical mission in the Persian Gulf, and the S-3 also served as the primary logistic transport for carriers. The S-3 had a direct combat role in which it electronically monitored active missile sites prior to air strikes. It also participated in the hunt for Scud missiles. Perhaps the most important contribution of the S-3 during the conflict was its airborne tanking capability. In this role, it employed a hose-and-drogue refueling system that resulted in more efficient refueling operations and more U.S. aircraft getting to their targets. In recognition of its broad applications, the designation of the S-3 Viking squadrons has been changed from Air Antisubmarine Squadron to Sea Control Squadron. At the request of the Navy, Langley conducted wind-tunnel tests to provide flutter clearance and spin recovery evaluations for the S-3 prior to flight tests. The phenomenon of aileron “buzz” was encountered in the flutter test and eliminated, and flutter clearance was successful. Results of the spin tests indicated satisfactory characteristics, and no major modifications were made to the aircraft. Based on the data from the Langley tests, Lockheed and the Navy were able to proceed into flight-test development of the S-3 with increased confidence. Langley facilities used in support of the development of the S-3 were the Langley 16-Foot Transonic Dynamics Tunnel and the Langley 20-Foot Vertical Spin Tunnel.

		Langley Contributions to the S-3

Background		In 1964, the Navy announced a requirement for a new carrier-based antisubmarine warfare aircraft (designated VSX) to replace the aging Grumman S-2 Tracker. The new aircraft was to have twice the speed, range, and altitude capability of the S-2. Development of the S-3 Viking began in 1969 when Lockheed was awarded the VSX contract. Remarkably, only five years elapsed from the time of contract award until the first aircraft was delivered to a fleet squadron in 1974. With the decline of the Soviet Union, and a subsequent reduction in the submarine threat to the U.S. fleet, the S-3 took on many new missions, including antisurface warfare, electronic surveillance, and airborne refueling.
Spin Tunnel Tests		In 1972, spin and spin recovery evaluations of the S-3 configuration were conducted in the Langley 20-Foot Vertical Spin Tunnel by Henry A. Lee and W. Louis White. Results of the tests indicated satisfactory characteristics would be expected of the S-3, and no modifications to the basic design were recommended. Although numerous stalling tests of the S-3 were conducted during the full-scale flight-test development program, intentional spins were not deemed necessary and were not attempted. Operationally, the S-3 has not experienced stall-departure or spin problems. S-3 model launched into the vertically rising airstream in the Langley Spin Tunnel.
Flutter Tests		Langley researchers Jean Gilman, Moses G. Farmer, and Charles L. Ruhlin conducted flutter tests of the S-3 in the Langley 16-Foot Transonic Dynamics Tunnel in late 1970 and early 1971. During the tests, the condition known as aileron “buzz” was encountered in which the S-3 ailerons exhibited very high frequency undamped oscillations. The problem was solved with a design modification to balance the ailerons, and flutter clearance for the complete configuration was demonstrated in mid-1971. S-3 flutter model in the Langley 16-Foot Transonic Dynamics Tunnel.

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October 17, 2003