waterproof instrumentation cables (Figures 76 and 77) that were not overly 

 sensitive to hydrostatic pressure. Oversensitivity would unduly influence the 

 strain readings recorded by the externally located balancing and recording 

 unit. Even though care was taken in selection of cables, the recorded strain 

 data may include some of the effect of hydrostatic pressure on the instru- 

 mentation cables. Tests conducted on the instrumentation cables have 

 shown that although the effect of pressure on the cables was generally less 

 than 1 x 1 0" 6 in. /in. ( 1 /xin./in.) on the strain recording, a few of the 

 cables were overly sensitive and increased the strain reading by as much 

 as 100 juin./in. 



Figure 72. Typical test setup for measuring the change in volume of 

 15-inch-diameter model. 



112 



