oe” 24 Blast and Shock Phenomena from Underwate: S-ots. Seven projects investigated free-field blast and shock phenom-na c:. uncervator shots ‘iahoo and Umbrelle. Their primary objective was to obtain the free-field input data needed for determinetion of safe delivery and critical damage rances for submarincs, aircraft, and surface vessels cperating in the vicinity of underwater nucleezr detonations. In general, there was a rath>> thorough amount of informetion available on free-field blast and sheck phenomena from HE tests. basic questions unanswered. The tlast ana in nuclear underwater tests, Crossrcads Piier in’ The only two -igwom, however, had left many s:cck projects therefore were gen- QO erally aimed et confir:sing and exvandin: cr esrecds ioker and Vigwam results, providing a tie-in between data from nucle?tr and Ne tests, providing inpat data to ship's damege projects, ind .«*+r7li: increasing knowledge of underwater explosion effects. Deep Water Shot — “Jahoo. Underwater Pressures. Two orgarizatioz-, ths vaval Ordnance Laboratory (NCL) and the Naval Slectronic Labor-tory “IDL,, colLlaborave? in measuring underwater pressures, Their main tecnnical .**.ctivas were to confirm ‘igwam results on scaling for isovelocity condition. and to study the effects of refraction. Pressure data vere o tained pressures ranged from 100 to 130C rs., » 5 to 9 stations instrumented; peak ‘fF 4 targ-t thip stations, an adequate number of pressure-time histories (at vwericvus derths to 1850') were obtained at the EC-2 (2346') and DD-593 (3387'). “cily 2 few peak pressures were re= corded at the DD-474 while at DD-592 no dace was obtained. confirmed “‘igwam results. The data generally Therr..l gradi... se snowed consideratle effect on the pressure field -t 3887' range and also influenced peak pressures at depths less than 300' at the range of the =C-2. [he oressure-time data will be thoroughly analyzed, primarily by NEL, for refraction effects using the shot time underwater temperature field provided by CNR - Hydrographic Office wo-r PCE FF yy