NSWC/WOL TR 77-90 



The three kill probabilities calculated at each air burst test 

 geometry-- 1000-lb and 64,000-lb --are also shown (enclosed by solid 

 circles) on Figures 4.2.1 and 4.2.2. In the following paragraphs 

 we will use these plots to make order-of-magnitude estimates of the 

 fish-killing potential of these four explosion test geometries. 



The computed kill probability data for the underwater explosions 

 is more complete than that for the air bursts. For the purposes of 

 this report the author has sketched in (dashed curves, Figures 4.2.1 

 and 4.2.2) possible extrapolations to the 50% and 10% kill contours. 

 These extrapolations are made in lieu of further computations 

 because they do not affect the order-of-magnitude conclusions of this 

 report. (Were it required, the author does not foresee any difficulty 

 in extending these contours by further computations to shallower 

 depths and also to the region directly beneath the charge.) 



For the air burst tests our data is meager. About the best we 

 can do is a crude estimate for a single kill probability contour for 

 each test configuration. For the 1000-lb air burst test (Figure 

 4.2.1) we take as an estimate for the region of greater than 50% kill 

 the shaded area--a cylinder of water 20 meters in radius and 25 

 meters deep. 



In order to estimate the lower boundary for 50% kill on the 

 1000-lb air burst test we needed more than the three kill probabili- 

 ties listed inside the solid circles (Figure 4.2.1). Thus, in order 

 to estimate the falloff of the kill probability with increasing depth 

 we calculated what is probably an upper bound by using the pressure- 

 time signature measured at the deepest gage (Figure 3.1.1) and 

 calculating the kill probability corresponding to this signature as 

 a function of hydrostatic pressure (different fish depths) . The 

 kill probabilities listed inside the dashed circles of Figure 4.2.1 

 were obtained this way. (Table 4.2.1 gives the complete results of 

 these calculations where only the fishes' depth was varied.) 



For the 64,000-lb air burst test we take as an estimate for the 

 region of greater than 10% kill a cylinder of water 70 meters in 

 radius and 50 meters deep (shaded area, Figure 4.2.2). 



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