To understand the difficulties with extensible flukes it is necessary 

 to examine how they function. The flukes are aligned in a vertical 

 position during the penetration phase of the placement procedure. After 

 attaining the maximum embedment as a result of the kinetic energy imparted 

 to them, they are pulled back up toward the seafloor-water interface to 

 get the flukes to extend outward. The distance required for the flukes 

 to open can vary from at least 1 to more than 1-1/2 times the length of 

 the flukes. Much of the effectiveness of penetrating into the denser 

 lower levels of the seafloor is lost during the fluke-opening process. 

 The large-sized flukes intended for use in mud proved to be too awkward 

 and bulky to be practical. Also, tests indicated the potential gain in 

 holding capac ity dnp to f luke size is offset b y the lesser penetration 

 attainable and the large vertical distance required to "key' the flukes 

 tn t-hp outw ard position. 



The ability to fire the fluked anchor-projectiles without incurring 

 damage is significant. In early designs not associated with this program, 

 anchor-projectiles with extensible flukes and having rated capacities 

 greater than 10,000 pounds nearly always sheared off or were severely 

 damaged during firing and penetrating. 



Though the design technique of the notched webs, Figure 10, 

 to lessen stress on the pins was successful in eliminating damage 

 while propelling large-sized flukes at high accelerations, the 

 reliability of functioning is low due to the generally excessive 

 resistance to penetration of sand seafloors and the large upward movement 

 needed to get the flukes to extend outward. Such penetrations and holding 

 capacities are examined theoretically in Appendices A and B. Thus, 

 further work is needed to improve the fluked anchor-projectile design to 

 obtain greater penetration and a more efficient keying action that 

 minimizes uplift displacement. Preliminary investigation indicates 

 that such design improvements can be attained. 



Ordnance System 



The modified safe and arm device did not leak and proved workable 

 with both an electrical cable and the touchdown delay mechanism. 

 However, it is unduly complex and expensive to be an expendable item, 

 employs electric initiators which must be shielded from hazard by 

 electro-magnetic radiation, and employs mild detonating fuze (MDF) 

 leads to fire the cartridge. The MDF leads are awkward and time- 

 consuming to install. After they are in place they are highly 

 susceptible to being pulled apart or otherwise separated prior to 

 firing the propellent. 



The electrical firing cable devised by the contractor worked well 

 in the shallow depths of the tests. However, it constitutes a third 

 line to be handled and at depths beyond 200 feet, problems of entangle- 

 ment and damage increase drastically. 



10 



