1441 
This formula agrees with the one derived by Dr. Penney (Ref. 9) 
who gives 
@ - a2 ir 
crvé 
( 7 in psi) 
For higher pressures, O can be derived directly for 
each pressure from (13) in using the data given in Table 1. The 
results which were obtained that way are summarized in Table 2; 
o 
W (at) 500 1000 2000 3000 5000 7500 10000 
° 
Os tiy p SUG 20 pude ebay u2042 . 62,0505 S5ceueD 
TABLE 2; Critical angle OES as function of shock pressure. 
These results are plotted in Fig. 3 and can be compared 
with the approximation (14). The curves show that the approxima- 
' 
tion is adequate (5% difference) up to 500 at. 
13 
