236 SHOCK WAVE MEASUREMENTS 



plosive, presumably because of the symmetry and lack of booster ma- 

 terial. 



A series of measurements (23) have been made for 51 and 80 pound 

 charges at a number of distances from 12 to 100 feet, which can be com- 



7000 



6000 



^^ 5000 



CD 



4000 



3000 



2000 



1000 



100 



200 



300 



400 



500 



REDUCED TIME t/w^(|JSec/lb^ 



Fig. 7.3 Shock wave pressure-time curves for spherical pentolite charges, 

 plotted against reduced time t/W^'^. 



pared with data for 3.8 pound charges at a distance of 5 feet. The 

 pressure-time curve for the small charges should, if similarity holds, 

 superimpose on the curve for 51 pound charges at a distance of 

 (51/3.8)1/3.5 _ 11 9 fegt^ ^^d the curve for 80 pound charges at 14 



Table. 7.1. Experimental verification of geometrical similarity for shock waves from 

 spherical charges of pentolite (50/50 PETN-TNT) . 



feet, provided that the curves are plotted against a reduced time t/W^'^. 

 Averages of individual gauge measiu'cmcnts are plotted in Fig. 7.3, the 

 solid curve being the average of 4 records for 51 and 80 pound charges 

 and the dashed curve the average of 14 records for 3.8 pound charges. 



