THE EVOLUTION OF THE SHIP'S INERTIAL NAVIGATION SYSTEM FOR THE FLEET BALLISTIC MISSILE PROGRAM

B. McKelvie and H. Galt, Jr.

Peer Reviewed

Abstract:	On 15 November 1960, the nuclear powered submarine, USS GEORGE WASHINGTON, carrying 16 Polaris A-l 1200-nautical mile missiles, departed Charleston, South Carolina on the first 60-day operational patrol of this nation’s Fleet Ballistic Missile submarines. On board the submarine was an inertial navigator, the MK 2 MOD 0 Ships Inertial Navigation System, known by the acronym, SINS. The SINS was self-contained. It was the heart of a new navigation subsystem that provided precise navigational data without the need for continuous external position references or reliance on the standard dead reckon- ing techniques of plotting ship’s position. The SINS enabled the USS GEORGE WASHINGTON to take advantage of its nuclear propulsion and remain submerged for extended periods of time, minimizing its probability of detection, while remaining in a constant state of readiness to fire its Polaris missiles. The nation’s newest strategic deterrent force, the Fleet Ballistic Missile and the FBM submarine, were on station. To have a ballistic missile hit its target thousands of miles away, the location of the launch point as well as the target must be precisely known. In this case, the launch point is a moving platform, the FBM submarine (Fig. 1). The task of the SINS is to provide the precise instantaneous location of that moving launch point to the missile fire control subsystem which then uses that information, together with the pre-set target locations, to solve the ballistic equations. The SINS must also provide continuous ship’s attitude and instantaneous velocity data so that the missile’s guidance system can be rapidly and accurately erected and aligned just prior to missile launch. Eight key parameters are provided by the SINS (Fig. 2). SINS latitude and longitude outputs are used to compute the missile’s instantaneous azimuth angle and range angle to target. SINS roll and pitch outputs are differentiated by fire control to obtain pitch and roll rates required for moment arm correction of ship velocity. Ship’s heading information is required by fire control to train the missile to the proper bearing for the selected target. SINS velocity is used to correct the computed missile initial velocity to account for ship’s motion.
Published in:	NAVIGATION: Journal of the Institute of Navigation, Volume 25, Number 3
Pages:	310 - 322
Cite this article:	McKelvie, B., Galt, H., Jr.,, "THE EVOLUTION OF THE SHIP'S INERTIAL NAVIGATION SYSTEM FOR THE FLEET BALLISTIC MISSILE PROGRAM", NAVIGATION: Journal of The Institute of Navigation, Vol. 25, No. 3, Fall 1978, pp. 310-322.
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