SAM-N-8 Zeus

SAM-N-8 Zeus, also known as Zeus I, was a project by the Naval Ordnance Laboratory of the United States Navy to develop a guided anti-aircraft artillery shell for launch from 8-inch (200 mm) guns. Tested in the late 1940s, it was overtaken by advances in guided missile technology.

SAM-N-8 Zeus
Zeus I
TypeGuided anti-aircraft artillery shell
Place of originUnited States
Service history
Used byUnited States Navy
Production history
ManufacturerNaval Ordnance Laboratory
Specifications (XSAM-N-8 Zeus I)
Mass72 lb (33 kg)
Diameter4 in (100 mm)
WarheadHigh explosive
proximity fuse

EngineCourse-correction solid-propellant rocket
15,000 yd (14,000 m) effective
Speed3,150 ft/s (960 m/s) muzzle velocity
Radio command guidance
ReferencesParsch 2003[1]

Design and development

Development of the Gun Launched Guided Projectile - Arrow Shell was initiated by the U.S. Navy's Naval ordnance Laboratory (NOL) in June 1947,[2] with the intent of developing a guided subcaliber projectile capable of being fired from the Mark 16 8"/55 caliber (203mm) guns mounted in the Des Moines-class heavy cruisers. In 1948, the project was officially classed as a guided missile, the designation XSAM-N-8 and name Zeus I being applied to the project.[1]

Zeus consisted of a 4-inch (100 mm) shell, weighing 72 pounds (33 kg),[2] launched using a sabot in the 8-inch gun;[3] the shell was fitted with stabilizing fins and a small course-correction rocket; the guidance system involved a radio command being sent to trigger the deflection charge.[3] Muzzle velocity was expected to be in the vicinity of 3,150 feet per second (960 m/s) with the use of standard powder charges in the Mark 16 gun,[1] and a single-shot probability of kill (SSPK) of 0.3 at 5,000 yards (4,600 m) was anticipated, with 0.025 SSPK, the value of a conventional 5-inch (130 mm) AA round at 5,000 yards, being achievable at 15,000 yards (14,000 m).[2]

Operational history

Test firings of the XSAM-N-8 begun in 1948; by early 1950, when the project was transferred from the Navy's missile development office to a purely gun-development project and the XSAM-N-8 designation cancelled,[2] 115 test shells had been fired. An improved Zeus II variant, with full guidance and a sustainer rocket motor, was projected,[2] and there were proposals to complete the unfinished battleship USS Kentucky as an anti-aircraft ship with quadruple turrets of 8" (203mm) guns firing Zeus.[4] However ordinary guided missiles were proving increasingly satisfactory, and when the U.S. Navy's missile programs were rationalized later that year the Zeus project was cancelled.[1]



  1. Parsch 2003
  2. Friedman 1982, p. 72.
  3. Bulletin 1949, p. 21.
  4. Friedman 2013, p. 309.


  • "Zeus I Launched From 8-Inch Gun" (PDF). Naval Aviation Confidential Bulletin. Washington, D.C.: Office of the Chief of Naval Operations and Bureau of Aeronautics. January 1949. Retrieved 2017-12-21.
  • Friedman, Norman (1982). U.S. Naval Weapons: every gun, missile, mine, and torpedo used by the U.S. Navy from 1883 to the present day. Annapolis, MD: Naval Institute Press. ISBN 978-0-87021-735-7.
  • Friedman, Norman (2013). Naval Anti-Aircraft Guns and Gunnery. South Yorkshire, England: Seaforth Publishing. ISBN 978-1-61251-957-9.
  • Parsch, Andreas (22 January 2003). "Naval Ordnance Lab SAM-N-8 Zeus". Directory of U.S. Military Rockets and Missiles, Appendix 1: Early Missiles and Drones. Designation-Systems. Retrieved 2017-12-21.
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