Keying Initiated 



Keying Completed 



Figure 6. Keying position for sediment fluke. 



The Naval Ordnance Station, Indian Head, Mary- 

 land, determined that standard Navy pyrotechnic 

 propellant would provide acceptable performance 

 over a broad depth range. With the propellant type 

 and the characteristics of the gun assembly known, 

 CEL could determine, using an NOS-developed 

 interior ballistics computer simulation, the most suit- 

 able grain configuration and charge weights for the 

 various anchor projectiles and water depths. The 

 result of the effort indicated that PYRO with a 

 0.08-inch web thickness (material thickness between 

 perforations) would yield a balance between the per- 

 formance of the small and large projectiles. During 

 the anchor test program a more readily available 

 PYRO, 0.074-inch web thickness (typically used in 

 the Navy 6-inch gun), was used. It would be suitable 

 for most anchor applications; performance actually 

 differs only slightly from the 0.08-inch web PYRO. 



The performance of each anchor projectile using 

 the 0.074-inch web PYRO is illustrated in Figure 12. 



The maximum charge weight that can be used is 

 limited by either a 35,000-psi gun barrel pressure or 

 3.75 pounds (cartridge limit). Peak performance for 

 these projectiles with 0.074-inch web PYRO is 

 obtained by using these limiting criteria to determine 

 necessary charge weights; these data are summarized 

 in Figure 13. 



Firing Mechanism. The finng mechanism (Figure 

 14) consists of a weighted touchdown rod, a power 

 supply, and a safe-and-arm (S/A) device. The touch- 

 down rod extends 26 inches below the fluke top and 

 is weighted in such away that it will slide relative to 

 the fluke when its 1-1/2-inch-square base contacts 

 1/4-psi shear strength soil or greater. It will not move 

 in the water column up to lowering velocities of 17 

 ft/sec, which is a reasonable safety margin above its 

 intended maximum of 2 ft/sec. 



