956 
(IRI, ) | z 
Paax Il & 2 ) 
———- * (II-22) 
Prax (IRI 2) RT, x 
where wl is a function of the kind of explosive, then 
P rot 
SB Een (i)! = ( 2 F (11-23) 
Pop, (7) TRI 
where the relation |R) -r = ct.exists, in which c is assumed to be a constant, 
ca.0.0645 in./ sec, for the pressures studied. 
Elimination of p (t) and p 
(r) among Eqs. (II-20), (II-21) and 
(II-22) and rearrangibe leads to De “ 
a 
1 trl 
a* pfte 4 
The value of r in Po (r) is taken for a given point which resulted in a 
given @, as r' - D, Be that point. The value of & is obtained from piezo- 
electric measurements at various values of |Ri and W (weight of explosive), 
that ts, from a peak-pressure similarity curve for a given explosive. It can 
be taken as unity with little resulting error in 6. It is found by solving 
Eq. (II-23) for @, that the dependence of @p on r for a given 6; is not great. 
© 
co 
n 
ole 
(II-24) 
An alternative method of deriving an equation to convert 8, into 04 which 
is in essential numerical agreement with Eq. (II-24) has been suggested by 
Professor J. G. Kirkwood. Here @, and @ are defined only at the shock front as 
1 = (22¢ for r = [RI (11-25) 
8, r t 
and ) 
i nae (4e2) for r = [RI at t = 0. (I-26) 
r 
If the logarithmic peak pressure vs. distance curve has a derivative @ 108 Puex , 
then, exactly, aR 
eee Prax < 910 + a log p \ 
a {RI r 6 > t (1II-27) 
r 
r= )RI r= [RI 
where c is the shock-front velocity at peak pressure Pyax. By using Eqs. 
(II-25) and (II-26) and rearranging, Eq. (II-27) becomes 
iv A pee Mee See Bot ps 
= 4 ETE (11-28) 
@,. a IRI 
For a given weight of explosive, 
Pax” SE (11-29) 
where P is a constant depending on the weight and kind of explosive. Then, 
15 155i8 
