Figure 4. CEL 20K anchor in position for on-deck assembly. 



Gun Assembly. Included in the gun assembly are 

 the reaction vessel, gun, and cartridge assembly. The 

 reaction vessel is composed of a threaded 2-1/2-inch- 

 thick steel plate that is welded to a 20-inch-diameter 

 schedule 120 steel pipe. A used surplus Army 90-mm 

 M41 gun tube that has been shortened and smooth- 

 bored is used to reduce system cost and to allow 

 system expendability if required. The reaction vessel 

 is attached to the gun tube by threading it on the 

 existing gun tube threads. A breechblock machined 

 from 160 ksi 4340 steel was designed to match the 

 existing gun threads. Recoil height of the basic 

 system was not considered a critical problem; there- 

 fore, a large drag area was not employed. However, 

 this is easily rectified if shallow water use is needed. 

 A 3-foot-diameter, 1/2-inch-thick ASH steel plate 

 was placed on the reaction vessel for tests recendy 

 performed in 45 feet of water (Figure 9). Reaction 

 distance was reduced from about 30 feet to 12 to 15 

 feet. 



The cartridge assembly (Figure 10) consists of the 

 following: 



Army M108B1 cartridge case . . Shortened 



to 10 in. 



M58 primer Shortened 



& reduced 

 charge 



Navy smokeless propellant . . . PYRO 



Obturator plug Polyethylene 



disk 



Wadding Styrofoam 



The obturator plug holds the propellant in place and 

 also seals the gas behind the piston, which extends 

 into the tapered cartridge chamber of the M41 gun 

 tube. Figure 11 shows the gun and cartridge 

 assembled for use. 



