76. How do submarines navigate when submerged for weeks at 

 a time? 



When the nuclear submarine NAUTILUS made its famous voyage to 

 the North Pole under the Arctic ice in 1958, the navigator was making 

 use of Newton's second law of motion, F = MA (force equals mass times 

 acceleration). The navigation system, known as inertial navigation, uses 

 accelerometers to continuously sense changes in velocity with respect 

 to a known starting point. 



Three gyroscopes (one for each direction of movement) create a 

 platform which remains stabilized regardless of maneuvers of the sub- 

 marine. The system is entirely independent of magnetic influences; 

 this is an essential requirement in polar navigation. 



In addition to the inertial navigation system, submarines may rely on 

 acoustic positioning sources on the bottom of the ocean to locate known 

 points of reference, and they can make use of doppler sonar to deter- 

 mine accurate ground speed. The whole doppler-inertial navigation 

 system on a nuclear submarine is tied together by an electronic 

 computer. 



Caidin, Martin 



Hydrospace, E. P. Dutton and Company, 1964. 

 Sherwood, David A. 



"Acoustic Navigation Systems',' Undersea Technology, Vol. 5, No. 6, 



June 1964. 

 Tilson, Seymour 



"The New Navigation," International Science and Technology, 



July 1963. 



93 



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