DEPENDENCE ON CLASS 



401 



BEAM 



BEAM 



STERN 

 Figure 15. Target strength asymmetry. Target strength in decibels. 



metrical with respect to all three planes in Figure 1. 

 This approximation was the basis of the theoretical 

 predictions described in Section 20.5. If now the 

 conning tower is added to the submarine immedi- 

 ately above its center, the submarine loses its sym- 

 metry about the horizontal (xz) plane. This asym- 

 metry about the xz plane is largely responsible for 

 the asymmetry in target strength-altitude angle plots 

 for positive and negative altitude angles. In addi- 

 tion, the shape of fuel and ballast tanks are fre- 

 quently not symmetrical about the horizontal plane. 

 Since the shape of the bow of a submarine generally 

 differs from the shape of its stern, perfect symmetry 

 about the yz plane is also absent. However, the port 



and starboard side of a submarine are, usually, nearly 

 identical, with only very minor differences, to a first 

 approximation, and therefore symmetry with respect 

 to the xy plane may be expected. In other words, 

 plots of target strengths as a function of aspect 

 should be sjonmetrical about the longitudinal axis of 

 the submarine. 



In the theoretical calculations of the target 

 strength of the U570 as a function of aspect angle, 

 symmetry about the xy plane was assumed, since the 

 submarine was approximated by an eUipsoid of 

 revolution. 



A lack of symmetry about the xy plane has been 

 observed in both direct and indirect target strength 



