curve. The velocity data derived this way are reasonably accurate, but 

 the acceleration data are suitable only as a rough check of accelera- 

 tion data from other sources. 



Comparisons of ballistics data to predicted values are presented 

 in Figures 10 and 11. Figure 10 shows the final velocity of the pro- 

 jectile relative to the launch vehicle for different charge weights. 

 All final velo cities were derived from high speed movie data by differ- 

 entiating the displacement-time curves. These data show that derived 

 values of final velocity were in very close agreement with predicted 

 values; not deviating by more than five percent. Figure 11 shows the 

 peak gun barrel pressure versus charge weight. Predicted peak pres- 

 sures are compared to data measured directly with either an electronic 

 pressure transducer or a copper crush gage. Measured values did not 

 vary from predicted values by more than nine percent. 



Update 



The first at-sea tests of the anchor were recently completed at 

 the NCEL shallow water test site in 110 feet of water. The anchor was 

 fired twice using the sand fluke and reduced charges of 2.75 and 3.25 

 pounds. Short-term holding capacities developed with the fluke were 

 42,000 pounds with 9% feet of penetration and 48,000 pounds with about 

 13 feet of penetration. Reduced charges (maximum is 3.75 pounds) were 

 used to ensure that the flukes could be recovered before the breaking 

 strength of the cable (60,000 pounds) was reached. Even with this 

 approach, care had to be taken to gradually increase the load to mini- 

 mize the effects of ship heave. Suction beneath the fluke could have 

 caused the load to exceed 60,000 pounds before pullout. 



These results were encouraging because the soil conditions at the 

 test site were among the most difficult that will be encountered in 

 the deep sea. The sediment profile/consist of two to three feet of 

 dense sand and then sandy silt. The sand attenuates projectile energy 

 and, therefore, reduced the penetration and hence the holding capacity 

 to be expected in a uniform silt deposit. The anchor will continue to 

 be tested in various water depths and seafloors. 



EVALUATION OF PERFORMANCE 



The land testing demonstrated that the structural design of the 

 launch vehicle is sound. The main components and connections resisted 

 acceleration-induced forces without suffering structural deformation 

 or failure. Attaching the launch vehicle components to the gun barrel 

 was accomplished easily with the gun barrel standing vertically on its 

 muzzle end. Assembling the anchor proved to be a relatively simple 

 process requiring about one hour when all components were initially 

 disassembled. About one-half hour was required when the launch vehicle 

 was left assembled from a previous firing. Assembling the fluke to the 

 launch vehicle with the launch vehicle laying down seems to be the most 



11 



