the reaction mass, but the magnitude of this effect is difficult to 

 assess. Previous embedment anchor designs (Smith, 1971; Smith et al, 

 19 70) have relied upon trapped water to provide a large portion of the 

 required reaction mass, but this procedure results in structural con- 

 figurations that are costly and difficult to fabricate. Trapping water 

 for a significant part of the reaction mass reduces the on-ship handling 

 mass. However, because the anchor is a light piece of equipment to 

 begin with, the less costly approach of using steel for the reaction 

 mass was chosen over trapping water. 



A downhaul cable 75-feet long is flaked on a board that is attached 

 to a launch vehicle. This length of cable will account for a maximum 

 50 feet of penetration in soft clay and a predicted 25 feet of launch 

 vehicle recoil at full charge. 



Launching System 



In design of the anchor launching system, it was decided to pursue 

 the use of existing ammunition components wherever possible in an 

 effort to reduce unit cost. Stockpiles of existing Army and Navy gun 

 tubes were surveyed in light of the following anchor launcher perform- 

 ance requirements : 



Muzzle Velocity 450 fps maximum; 200 fps minimum 



Projectile Weight 500 lbs. maximum; 300 lbs. minimum 



Projectile Acceleration 2000 g's maximum 



Gun Barrel Length 48 inches maximum 



Operable Water Depth 20,000 ft. maximum; 100 ft. minimum 



Based upon these requirements, a smooth-bore tube approximately three 

 to four feet long, with a four- inch inside diameter and usable existing 

 breech threads was desired. 



While no Navy barrels appeared to be readily adaptable to this 

 configuration, several Army tubes approached these requirements. The 

 90mm, M41 tank gun tubes were most plentiful, and a design effort to 

 utilize these tubes was undertaken. Unfortunately, the tapered chamber 

 portion of the tube comprises most of the length useful to this 

 application. 



Energy and propellant loading density requirements indicated that 

 a cartridge case about ten inches long could contain a sufficient 

 quantity of single-base gun propellant to achieve desired anchor 

 velocities. However, the chamber diameter ten inches from the breech 

 face is still greater than the desired smooth-bore diameter. Use of a 

 longer case would reduce this diameter while reducing remaining pro- 

 jectile travel. Either a longer barrel would then be necessary or the 

 anchor assembly would have to experience higher launching accelerations 

 to achieve the same velocity in a shorter distance. 



It was decided to circumvent this problem by utilizing the ten- 

 inch long cartridge case, smooth-boring the tube to a diameter of 4.25 



