yo 2-13 and equipment response from underwater bursts, and three projects were con~ cerned with land structures response to air blast, Preliminary to Operation HARDTACK a sories of tests were run employing high-explosive tapered charges against the destroyer DD 592 off Santa Cruz Island, California in January 1958. A series of four large, special shaped (tapered) H. E, charges weighing from 1400 to 4400 pounds wes planned to sin ulate underwater nuclear attack against the DD 592. The series of tests wes carried up to the threshold of shock damege, but stopped after detonation of the third charge to avoid the probability of serious damage to the DD 592 prior to the later main HARDTACK full-seale nuclear tests. The results in- dicated thet the shock wave pressure satisfactorily simulated the initial shock waves from a nuclear detonation, - Four unmanned major target ships, 3 destroyers, and an SC-2 merchant ship, were instrumented and exposed to the “lahoo and Umbrella underwater detonations. In addition, three manned fleet operating ships, submarine SSK 3 and destroyers DD 728 and DD ‘826, had a minor amount of instrumentation aboard and were also exposed to Wahoo. ‘The SSK 3, unmanned, and a 4/5 scale submarine model, SQUAI] 29, were also exposed in Umbrella, The shock res- ponse of equipment, as well as equipment foundations which included hulls, bulitheads, decks and superstructures were documented by the use of a total of 325 velocity time meters and self-recording shock-spectrum gages and 40 high- speed motion-picture cameras. t The follovring tentative conclusions with re- spect to damage to machinery and equipment may be made. pELETED COPIED/DOE LANL RG ThcRe wee wc PCE SH