were used. The horizontal assembling seemed easier. About one-half 

 hour was required to assemble the anchor when the unit was partially 

 preassembled. One hour was required when all components were 

 disassembled. 



Land testing provided a severe test of the structural design of 

 the launch vehicle. Upon firing the launch vehicle reacted upwards, 

 breaking the wood cross-beam and rising to a height of up to 90 feet. 

 Reaction height was dependent on the charge weight. Accelerations 

 during land firing are nearly equal to those expected in water; however, 

 impact of the launch vehicle with the ground after firing exceeds what 

 the launch vehicle has to withstand in water since the reaction height 

 in air exceeds that in water and hydrodynamic drag greatly reduces 

 impact velocity. No failures of major structural components occurred, 

 and in general the ruggedness of the design was confirmed. Two problems 

 were noted. The shear pin links were slammed up-and-out and against 

 the launch vehicle body by the blow-down of the gases in the gun barrel 

 after the piston exited. Each test caused an additional amount of 

 bending of the bars on the launch vehicle that the links were attached 

 to, but after six tests, little difficulty was found in using the links 

 for the seventh test. No effort was made to straighten the links 

 between tests. At least one bolt used to hold the cover body to the 

 bearing plate on the gun barrel was broken during every test when the 

 launch vehicle hit the ground. The launch vehicle usually hit the 

 ground with its axis oriented horizontally. Consequently, the gun 

 barrel was cantilevered from the top plate of the cover body at impact 

 with only four 5/8- inch bolts to restrain it. The bolts were not de- 

 signed for this situation. The bolts were easily replaced between 

 tests. Both of these problems occurred during land testing; neither 

 was serious, and both will be alleviated in water. Neither affects 

 anchor performance. 



Ballistic performance for charge weights from 2.25 pounds to 3.50 

 pounds was in satisfactory agreement with predicted performance. Test 

 results are summarized in Table No. 2. The data have been given sub- 

 scripts to indicate whether the data came from videotape (V) , high 

 speed movies (M) , electronic accelerometer (A) , electronic pressure 

 gage (P) , or copper crush gage (C) . Another subscript indicates 

 whether the quantity is a direct measurement (D) or an indirect measure 

 (ID). Electronic instrumentation data were difficult to gather because 

 of "ringing" as the piston slid out of the gun barrel and because of 

 high stresses on the transducers and cables during acceleration. This 

 was in spite of considerable effort made in transducer selection and 

 layout to avoid these problems. As a result, after the fourth test 

 electronic instrumentation was not used, and copper crush gages were 

 substituted to measure peak pressure. High speed movies provided a 

 direct means to determine the time span of a firing and the displace- 

 ment-time curve for the projectile movement relative to the launch 

 vehicle. Differentiating this displacement- time curve once gave a 

 velocity-time curve, and differentiating again gave an acceleration- time 



10 



