967 
es Ne = Se Te (II-50) 
bass Hit) 
Ne = Te (II-51) 
x] 
Nog es (11-52) 
*5 
A op gas (II-53) 
x3 - x, 
Combining Eqs. (II-50), (II-51), (II-52), (II-53) with Eq. (II-49) results in an 
equation which reduces to 
TAX5 ~ X5V5 AGS + XS | XG¥. - XY, - KZ 
= k (11-54) 
585 - 35° + 9175 - 5" X1X3 - HX, + V3 
where k is a constant for a given grid line intersection. Eq. (II-54) is combined 
with 
ae + ys = (0Q)% = (oR)? (11-55) 
to obtain values for x5 and ys5, the extraneous roots being discarded. 
d CR ~ dz0 
Z wre = tan“) (11-56) 
tt cr. “RO 
and 
emer | 
Zorg «= ten RQ RO (II-57) 
1+ “pq “Ro 
Combining 
¥. 2 
Aes cea eae (11-58) 
X5 - xy 
and Eqs. (II-50), (II-51), (11-52), (11-53), with Eqs. (11-56) and (II-57) results 
in the following equations: 
Zwree = tan“) (-k) (11-59) 
co Naa, Nas fib f (11-60) 
Finally, 
y « sn 6 we » (Snell's law), « (II-62) 
and the corresponding pressure is then obtained from Table VII. 
After calculations have been made for several grid line intersections, the peak 
pressure is determined by the method described in Section 1 of the Appendix; namely 
by plotting the calculated pressures against corresponding distances of the mid-point 
of RQ from the shock front, and extrapolating to zero distance from the shock front. 
Attention is again called to the fact that the apparent intersection of the shock 
wave and grid on the photograph is the projection on the grid of a cone with its apex 
at the camera lens and tangent to the shock wave sphere, and the shock wave radius must 
be calculated accordingly. 
8&6 15518 
