NSWC/WOL TR 7 7-9 



Response to the second pulse at all depths was calculated 

 both by the method of Reference 1 (square steps) and by the impulsive 

 loading approximation described in Section 3.4. As described in 

 Section 3.4, the method giving the smallest value for Z = X + Y was 

 then selected to represent the response to the second pulse, 



4. RESULTS 



4.1 GENERAL OBSERVATIONS . The final column of Table 3,5.1 lists 

 the kill probabilities corresponding to the calculated fish damage 

 parameter Z for the representative 1000-lb and 64,000-lb test 

 conditions selected for this study. Relative to the uncertainties 

 inherent to this study, the variation of kill probability with fish 

 size is not great. This factor of two variation at the two 

 shallowest locations for the 1000-lb test geometry is largely due 



to the variable response of the different sized swimbladders to 

 impulsive loading by the second pressure pulse. 



One would expect the longer duration pressure pulses of the 

 64,000-lb test geometry to cause larger kill probabilities at 

 corresponding scaled locations. Except for the marginal case of the 

 shallowest gage location this does not occur, since the effect of 

 4 times greater depth at corresponding scaled locations on the 

 64,000-lb test more than offsets the effect of longer pulse durations. 

 This generally lesser kill probability at corresponding locations 

 of the 64,000-lb test geometry is a direct result of increased 

 hydrostatic pressure suppressing the amplitude of swimbladder 

 oscillation. 



4.2 KILL PROBABILITY CONTOURS . To give meaning to these kill 

 probability results we compare them to similar calculations for 

 underwater explosions. Figures 4.2.1 and 4.2.2 show contours of 

 constant kill probability calculated for charge weights of 0.57 and 

 32 kg pentolite respectively, exploded at a depth of 9 meters.* 



*H-6 is more energetic than pentolite. It probably takes about 1.1 to 1,2 times 



as much pentolite on a weight basis to produce roughly equivalent underwater 



pressure fields in the air-burst and underwater-burst configurations considered 



oRr.o^J^§r-^ffi?J'-^«S2»-l'^^"i'^3lsrit weight" corrections were made in doing the compari- 

 ouiio lUL L.nis rcpo L L • 



18 



