On each plot, curves representing performance with different charge 

 weights for each projectile were drawn. In addition, a curve represent- 

 ing the limiting gun barrel pressure relative to the water pressure 

 (35,000 psi) was drawn for each projectile. An example of such a plot 

 is shown in Figure B-1. 



The ideal situation would have been to find a single web thickness 

 and a single charge weight that would give acceptable performance over 

 the depth range of interest for both projectiles. Such was not the 

 case. Examination of the performance curves indicated that at least 

 three separate charge weights would be required to approach uniform 

 performance with depth. The scheme to select charge weights for a given 

 web thickness was to find the charge weight that gave a 35,000 psi gun 

 barrel pressure at a water depth of 20,000 feet with the 490-pound pro- 

 jectile. A second charge weight was then found such that at some depth 

 (usually around 10,000 feet) a shift to this second charge weight would 

 again give a 35,000 psi gun barrel pressure. This second charge would 

 be used from the shift-depth to the minimum operating water depth. 

 This second charge was then used with the 300-pound projectile at 20,000 

 feet so long as the gun barrel pressure would not exceed 35,000 psi; if 

 so, the second charge weight was adjusted down. The same performance 

 balancing procedure used with the 490-pound projectile was then applied 

 to the 300-pound projectile. Another shift-depth was found and a third 

 charge weight selected. The result of this process was that one charge 

 weight, the second, was common to both projectiles. 



It was determined that the .07-, .08-, and .09-inch web sizes could 

 satisfy the requirements. The .06- inch web could not give acceptable 

 velocities to the 490-pound projectile, gun barrel pressure being the 

 limiting factor. The .10-inch web was not suitable, as performance with 

 the 300-pound projectile started to fall off rapidly, the limiting 

 factor being the amount of propellant that could be loaded. In selecting 

 between .07-, .08-, and .09-inch web thickness it was noted that thicker 

 web increased the performance of the 490-pound projectile but decreased 

 the performance of the 300-pound projectile, and the thinner web pro- 

 duced the reverse effect. It appeared that the .08-inch web was the 

 best for all-around performance with the two projectiles. For the 300- 

 pound projectile a 3.5-pound charge is used down to 10,000 feet and a 

 2.95-pound charge in water depths between 10,000 and 20,000 feet. For 

 the 490-pound projectile the 2.95-pound charge is used to a water depth 

 of 10,000 feet and a 2.6-pound charge is used between 10,000 feet and 

 20,000 feet. Figure B-2 shows the charge weight and resulting perform^-, 

 ance. Minimum performance for the 300-pound projectile is about 325 

 feet per second, and minimum performance of the 490-pound projectile is 

 about 245 feet per second. Both of these values exceed the established 

 goals of 275 and 225 feet per second, respectively. 



An important factor in designing particular installations with the 

 deep water anchor is that performance can be optimized to higher veloc- 

 ities as required. The performance of the 300-pound projectile can be 

 up-graded to about 400 feet per second at water depths to several 



36 



