Operation Dominic, Shot Sword Fish, Project Officer's Report - Project 1.1, Underwater Pressures (June 25, 1968) (Deleted)

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OPERATION DOMINIC, SHOT SWORD FISH Robert S. Price, Project Officer U.S. Naval Ordnance Laboratory This is an extract of POR-2000, Operation DOMINIC, Shot Sword Fish, Project 1.1. Approved for public release; distribution is unlimited. Extracted version prepared for DEFENSE NUCLEAR AGENCY

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Destroy this report when it is no longer needed. Do not return PLEASE NOTIFY THE DEFENSE NUCLEAR AGENCY, ATTN: STTI, WASHINGTON, DC 20305-1000, IF YOUR ADDRESS IS INCORRECT, IF YOU WISH IT DELETED FROM THE DISTRIBUTION LIST, OR IF THE ADDRESSEE IS NO LONGER EMPLOYED BY YOUR ORGANIZATION.

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SECURITY CLASSIFICATION OF THIS PaGe" REPORT DOCUMENTATION PAGE ta. REPORT SECURITY CLASSIFICATION UNCLASSIFIED 1 b. RESTRICTIVE MARKINGS 21. SECURITY CLASSIFICATION AUTHORITY Approved for public release; distribution is 4. PERFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING ORGANIZATION REPORT NUMBER(S) &.. NAME OF PERFORMING ORGANIZATION U.S. Naval Ordnance Laboratory 7a. NAME OF MONITORING ORGANIZATION Defense Atomic Support Agency 6c. ADDRESS (City. Stitto, and ZIP Code) 7b. ADDRESS (City, Stati, and ZIP Code) Ba. NAME OF FUNDING /SPONSORING 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER Sc. ADDRESS (City, State, and ZIPCode) 10. SOURCE OF FUNDING NUMBERS 1. title {include stcumy cta.ssificatio^OPERATION DOMINIC, SHOT SWORD FISH, PROJECT OFFICERS REPORT - 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month, Day) 16. supplementary notation this report l'las had sensitive mil itary in?ormatlon removed in order to provide an unclassified version for unlimited distribution. The work was performed by the 18. SUBJECT TERMS (Continue on if MC.SUI)' and identify by block number) Dominic Hydrodynamic Yield Sword Fish Depth of Burst Underwater Explosions Dynamic Pressure 19. ABSTRACT {ConUnue on revelfe if neceSSlty and identify by block number) The objectives of this project were to: (1) determine the Sword Fish hydrodynamic yield, depth of burst, time of burst, and surface zero position; (2) determine the effect of reflection and refraction on the dynamic pressures; and (3) deduce the Sword Fish burst bubble history. These were accomplished by making underwater dynamic pressure measurements 20. DISTRIBUTION / AVAILABILITY OF ABSTRACT 21. ABSTRACT SECURITY CLASSIFICATION DD FORM 1473.84MAR 83 APR edition may N used until exhausted. All other editions are obsolem. SECURITY CLASSIFICATION OF TH)f PAGE

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SHOT SWORD FISH Robert S. Price, Project Officer Silver Spring, Maryland 20910 This document Is the author(s) report to the Director, Defense Atomic Support Agency, of the resultsr of experimentation sponsored by that agency during nuclear weapons effects testing. Accordingly, reference to this ma terial must credit the author(s). This report is the property of the Department of Defense and, as such, may be reclassified or with drawn from circulation as appropriate by the Defense Atomic Support Agency.

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Project objectives were to: (l) determine the Sword Fish hydrodynamic yield, depth of hurst, time of hurst, and surface zero position; (2) determine the effects of reflec tion and refraction on the dynamic pressures; and (3) deduce the Sword Fish hurst bubble history. Measurements of the underwater dynamic pressures, using were made at five stations at horizontal ranges from 3,100 to 20,250 feet. Gage depths varied from 20 to 2,000 feet. Ball crusher peak-pressure gages were used as backups at three close-in stations at gage depths from 25 to 1,000 feet. Time-of-arrival data was recorded at one station at a range of 23,800 feet. Ninety-four percent of the tape records and ninety-one percent of the ball crusher records yielded usable The results of the shot, fired under the particular conditions of Sword Fish, were as follows: 1. Ike hydrodynamic yield was found to be equivalent bo The depth of burst was 690 ± 10 feet. 11 May 1962, about 39*809 seconds after the launch (zero) time. Geographical surface zero position was not determined by the project.

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2. Refraction effects were detected in electronic pres sure measurements at ranges of over 1*,000 feet. Mechanical gages showed refraction effects even as close in as 3#120 feet. 3. No bubble pulse was detected. 4. The bottom reflection, at ranges over 6,400 feet, was stronger than the direct wave. Computer codes especially developed for this situation were employed in the analysis} they are adaptable for the analysis of future test results.

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Shot Sword Fish ms an undermter weapon effects test conducted In the Pacific Ocean off the southwest coast of the United States in May 1962 as part of Operation Dominic. Sword Fish ms the first fully operational test of the Savy's antisubmarine rocket (ASROC) weapon system in which a nuclear war reserve weapon ms expended. Weapon effects information of importance to the advancement of surface ship capability to conduct nuclear antisubmarine warfare ms obtained. An overall description of the test efforts and a summary of preliminary results my be found in the Sword Fish Scientific Director's Summary Report, which includes general information such as location and time of burst and a guide to Sword Fish

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2.2.5 The Playback System ---------------------------------------- 35 2.2.8 Mechanical Support and Rigging----------------------------------- 39 2.6 Computations of Shock Arrival Times------------------------------------- 45 3.1.1 Event Time on EPT Records----------------------------------------- 67 3.1.3 Pressure Measurements, Electronically 3.1.5 Impulse and Energy Flux Measurements----------- 72 3.2 Data From Other Projects--------------------------------------------------- 73 3.2.2 Shock Wave Arrival Times------------------------------------------- 73

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APPENDIX MECHANICAL SHOCK MEASUREMENTS................................... 140 2.1 Instrumentation Data for Each Instrumented Point------------------- 51 2.2 Calibration Data for Tourmaline Gages- --------------------------------- 53 2.3 Hydrophone Calibrations at Station 4------------------------------------- 54 2.5 Comparison of Data Reduction Systems----------------------------------- gg 3.1 Summary of Sword Fish Recordings-------------------------------------- 75 3.2 Times of Arrival of Pulses at Piezoelectric Gages------------------- 11 3.3 Ball Measurements and Pressure Values for Ball Crusher Gages at Station 1------------------------------------------------- 79 3.4 Ball Measurements and Pressure Values for Ball Crusher Gages at Station 2------------------------------------------------- 87 3.5 Ball Measurements and Pressure Values for Ball Crusher Gages at Station 3--------------------------------------------------- 92 3.6 Pressure Measurements, Electronically Recorded------------------- 97 3.7 Time Constant, 9, and Extrapolated Peak Pressure----------------- gg 3.8 Impulse, I, and Energy Flux, E------------------------------------------- 99 3.9 Location of Gage Strings Relative to Surface Zero at Time of Burst From Photographic Measurements-----------------100 3.10 Time of Arrival of Shock Wave at Project 3.1 3.11 Depth Versus Computed Sound Velocity-------------------------------------102 4.1 Depths of Burst Calculated by Matching Various 4.2 Depth of Burst Determination From Averages---------------------------424

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4.3 Depth of Burst Determination, Final Computations--------------------- 125 4.4 Yield From Ball Crusher Peak Pressures---------------------------------- 4.5 Yield Based on Shock Wave Parameters (Hand Measurements and Machine Computations)------------------------------- 130 4.6 Yield Based on Shock Wave Parameters (Machine 4.7 Bottom Depths Postulated on Basis of Bottom 2.1 Planned locations of pressure-measuring stations------------------- 57 2.2 Actual deduced locations of pressure-measuring 2.3 Dynamic force coefficients, copper balls------------------------------- 59 2.4 Initial ball deformation and the hydrostatic pressure correction term, copper balls----------------------------------------------- 60 2.5 Dynamic calibration shock waves---------------------------- 61 2.6 Schematic of calibration and data signals during 2.7 Comparison of manual and mechanical record 2.8 Instrument container at Stations 1 and 2--------------------------- 04 3.3 Sound velocity versus depth at test site--------------- - -----------------105 4.1 Results of depth of burst calculations--------------------------------------- 134 4.2 Ball crusher peak pressures versus depth--------------------------------- 135 4.5 Intensity factor versus depth at three stations--------------- 133

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The objectives of Project 1.1 vere to: (l) determine the Sward Fish hydrodynamic yield, depth of burst, time of burst, and surface zero position ; (2) determine the effect of reflection and refraction on the dynamic pressures; and (3) deduce the Sword Fish burst bubble history. These were to be accomplished by making underwater dynamic pressure 1.2 BACKGROUND AND THEORY Data from two previous underwater nuclear explosions in deep water are available. Operation Wigwam (References 1, 2, and 3) provided basic information for comparing nuclear and higi explosives under water. Refraction effects on the shock wave, evidence of a condensing bubble (Reference 2), bottom reflections of the shock wave, and cavitation closure pulses were reported. Wigwam data was the only deep water information available for establishing operational conditions for the application of nuclear weapons. Because of the

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complexity of the various explosion effects and their inter actions vith the hull and equipment of ships, Shot Wahoo ms fired during Operation Eardtack to verify predicted effects upon target vessels. Test conditions were arranged to facili tate measurement of bottom reflection, cavitation closure, and primary shock vave effects on ship targets. The selected site ms over a sloping bottom, and the weapon ms suspended at a preset depth. Many of the desired records of undermter pressure (References k and 5) were not obtained from Shot Wshoo because of malfunctioning equipment and operational losses. Records were not obtained at enough locations to permit more refined refraction predictions or to improve understanding of the cavitation closure phenomena. No bubble pulse ms detected on idle records; however, since the bubble would have migrated to a position very close to the ocean's surface before emitting the pulse, the pulse, if it did occur, might have been masked by surface cutoff (reflection as a negative pressure wave from a tree surface). The importance of the primary shock wave after reflection from the ocean bottom, especially if focusing has occurred, ms brought out during Operation Wigwam. Shot Wahoo ms fired under conditions of bottom depth and contour that produced reflection effects on target vessels; however, the conditions were unfavorable for producing significant focusing effects, and none were

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Sword Fish ms intended to provide results for compari son with Wigwam free-field measurements, provide a full-scale refraction effect for comparison with laboratory and theoreti cal work, permit further study of bulk-cavitation closure, and provide bottom-reflected shock vave characteristics. The Sword Fish bubble pulse was expected to be difficult to measure because, as for Wahoo, the bubble would have migrated to a shallow depth before completing its first oscillation. For Wigwam the approximate time of maximum contraction was indicated by a sharp-fronted wave imposed upon the normal rounded bubble pulse. The sharp-fronted wave was attributed to the impact of the top and bottom of the bubble during the beginning of vortical motion. A similar sharp wave or perhaps multiple sharp waves were expected from the Sword Fish bubble. In the absence of such waves, source location and perhaps even detection of the rounded pulse would be impossible, and this result would be taken as evidence that the bubble had not collapsed as expected.

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Figure 2.1 shows the planned locations, relative to the target float, of the five stations at which underwater pres sure measurements were to he made. Figure 2.2 shows the actual location of surface zero and the instrument stations at shot time, ?.s deduced from aerial photographs, shocfc wave arrival times, and radar plots. Table 2.1 lists the planned gage depth, type, and size for each of the six stations. The data from the electronic pressure-time (EFT) gages at five stations was recorded on magnetic tape in recorders •sdiich were originally built for Hardtack and extensively modified for use on Sword Fish. The recorder at Station 6 was a Sony Sterecorder, Model kSW), One recorder was located at each station. For all stations, generally uniform spacing of gages was decided upon, since the effects of refraction and any unexpected phenomena could be detected better than if lump placement of gages at two or three depths had been used. The latter arrangement would only have checked the accuracy of the gage and recording system and assured data from one specific point in case of

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failure of a single gage. More closely spaced gages at shal low depths vere used when store information in that region Data from Stations 1 and 2 vere to he used primarily in determining the depth of hurst, yield, huhhle period, and huhhle migration. Secondarily, they would provide information on the hulls cavitation closure and the hottoo reflection. It was Judged that the value of data would rapidly degenerate for the primary purposes as the horizontal range increased, the two stations vere mutual backups to allow for normal dispersion in projection placement of weapons. Station 1 would he better if the hurst were more remote than expected; Station 2 should have recorded and survived if the hurst were near enough to Just sink Station 1. the deep gages would produce records least distorted by surface cutoff and refrac tion effects and, with the shallow gages, would provide long Data from Station 3 ms primarily to provide exact free-field pressure input to the towed target vessel for shock and damage evaluation. Information on refraction would also be obtained. Station h ms to provide data on refraction effects and the bottom reflection as well as shock input data to the towing vessel. Station 5 was to provide shock input data to the delivery vessel, or, if a change in delivery vessel ms

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tire to the explosion. Station 6 ms to provide arrival-time data at a rather remote location. Most recording instruiaentatlon used for Sword Fish had heen used for Operation Hardtack except that, where time permitted, modifications were made to improve reliability and to facilitate use in the field. Replacement and new parts selected for use on Sword Fish are described below; equipment not altered or redesigned is mentioned for identi fication, and further description can be found in Reference 5. 2.2.1 Ball Crusher Gages. Ball crusher (BC) gages have been used for many years to measure the peak pressure from underwater explosions. Pressure, transmitted through a pis ton, presses a soft copper ball against an anvil, causing a permanent deformation of the ball. The amount of deformation is a function of the hydrostatic pressure at the gage loca tion, the shock wave peak pressure, the time constant of the subsequent pressure decay, the area of the piston, the mss of the piston, the mss of .the gage, and the particular prop erties of the copper sphere that was used. Qie design of the 1C gage vith O-ring seals as used on Sword Fish is described in detail in Reference 5*

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Instead of using four gages per block as described in Reference 5> three gages were mounted on a block, and the fourth mounting hole ms used for attaching either a piezo electric gage bracket or a bracket to hold the electric cables. Blocks were placed at 25-foot spacing at depths from 25 to 1,000 feet at Stations 1, 2, and 3. Two sizes of ball were used: 3/8-inch diameter for expected pressures over TOO psi and 5/32-inch diameter tar expected pressures from 300 to 1,500 psi. Station 2 was expected to be in the region of overlap between 700 and 1,500 psi,so both ball sizes were used there. Blocks carrying gages with 3/8-inchdlaoeter balls were alternated on the support cable with blocks carrying gages with 5/32-inch-diameter balls. Balls are usually calibrated by dropping weights on them and also by slowly loading them with a known force to deter mine calibration constants for conversion of deformation readings to pressure. Thus, two separate calibrations are made for each group (or lot) of balls. One equation for converting deformation readings to shock wave pressure (assuming that the time constant of the shock wave is very long compared to the reaction time of the

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Where: P * the shock pressure, psi « the final, measured deformation, inches A » the area of the piston, square inches (0.196 for Sword Fish gages) …