529 



The peak pressure p^ and impulse I were calculated using the eiiQ)irical 

 expressions 



1.14 

 .1/3^ 



p„ = 20,400 



(r 



w 

 I = 1.50 - 



,2/3 



lb -sec/in.' 



lb/in. 



(3) 



where W (lb) is the weight of TNT and R (ft) is the charge-to-gauge distance. 

 The relation between p^ and I is assvimed to be given by 



1 = %*^ (5) 



so that the time constant £ may be calculated from the following expression 



= 73.5W°'29 RO.l^^sec, (6) 



which will be used later. 



The above expressions for the explosion parameters Pj^ and I were 

 determined by piezoelectric measurements of explosions from full-scale 

 chargesiH' Although some error may be introduced in sceiling these 

 values down to small charges, it is felt that they are probably more 

 reliable than those obtained with small charges where instrumentation 

 difficulties made it necesssiry to apply considerable corrections to 

 apparent values. 



Although somewhat outside the scope of this report, it is interesting 

 to note the effect on the theoretical damage-weight ciirve if theoreti- 

 cal shock-wave parameters are substituted for the empirical values. 

 Table III lists the scaled empirical values with those predicted theoreticeuL- 

 lyii/ for small THT charges of density 1.59 gjn/caP. 



Table III. Comparison of theoretical and experimental explosion parameters 



(Distance from charge 4 feet) 



10/ "Underwater Explosions", Princeton University Press pg 242 by R.H. Cole. 

 11/ Kirkwood, Brinkley, and Richardson, OSRD No. 2022, p.22, Nov. 1943. 



