Memo to Test Director, Subject: Military Effects Group Event Grable Operational Report (Upshot/Knothole Operation)

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Location ML MILITARY EFFECTS GROUP SUBJECT; Military Effects Group Shot GRABLE Operational 1. This report presents a preliminary review of the results of the Military Effects Group participation in Shot No, 10 of UP3K0TKNCTHOIE, commonly called KNOTHOLE No, 2. As you know, this was the second principal effects test in Frenchman Flat for the Military Effects Group, Consequently, the participation was very extensive and it is only possible to present at this time a very cursory summary of the results. The post shot review meetings were held on D/2 day. The reports presented herein are as of that time and they are brief, in view of the fact that the preliminary technical reports will be forthcoming at an early date. -2-r From previous experience it was expected that this weapon would produce marked precursor phenomena because of the height of burst. However, there has been little previous experience with the effects of such pressure waves on test targets. The damage effects in Frenchman Flat were very startling indeed. In many instances the damage was considerably more severe than had been anticipated. The principal damage criterion heretofore, for a number of reasons, has been peak pressure. It had been recognised that many drag targets would be more sensitive to the particle velocity behind the pressure front than to the overpressure. However, for conventional shock waves the relation between pressure and particle velocity is well established. It appears that the drag, or particle velocity, increases markedly when the test conditions are arranged to produce a strong precursor effect. This effect can result from both an increase in the particle velocity for a given pressure and the fact that the precursor signal may have a vertical velocity component. In any event the visible damage out to a pressure level of from 6 to 8 psi was very startling on this test. It will be some time before the :rvations can be understood. In the meana very logical choice.

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3* Only those projects actually participating in this shot are reported below: Project 1.1a - On 49 channels connected 40 records were obtained. One surface level gage was damaged by the blast to the extent that no record resulted, while 8 of the 10* gage towers were knocked over. In general, the records obtained were good. A clear precursor existed Jfcom 67? ft. to 2700 ft. The records are somewhat similar to those of TUMBLER The maximum pressures recorded were reasonably close to predictions. Under the smoke line (black smoke) the precursor pressures were greatly accentuated, perhaps as much as two or three times those which existed along the main blast line. Six mechanical pressure-time gages were tested with apparently good Project 1.1b - On 65 channels connected 54 records were obtained. One oscillograph recorder failed due to a paper break at minus 2 seconds, after it had been running for 13 seconds. In addition, cable breaks were sustained on 15 additional channels due to gage tower failures. The 50 foot blast gage towers at nominal ground ranges of 1000, 1500 and 2000 feet were blown over. This tower damage was considerably greater than had been anticipated. For instance, towers were knocked out at maximum pressures under 10 psi, but these same towers withstood maximum pressures of 25 psi bn Shot 9* The same precursor phenomena was reported as described under Project 1.1a. Project l.ld - On 40 channels installed, 12 complete records were obtained while 22 partial records were obtained due to structure failure of one kind or another at the time of blast arrival. Six channels failed due to zero time transients. The "q11 measurements in the’ strong damage region will probably not be of major value. Project 1.2 - All 13 rockets fired satisfactorily. The cameras ran arti. it is presumed that suitable blast photography .and rocket blast measurements will be obtained upon further analysis. project 1.4a - On 15 channels connected 15 records were obtained. Records have not yet been examined. project 1.4b - On 24 channels connected at a nominal ground range of 1250 feet 23 records were obtained. The records have not yet Project 2.2a - project officer reports a satisfactory experiment Project 2.2b - Readings were made on shot day and on d/1 day. Some intermittent instrument trouble may have been encountered. project 2.3 - The project officer reports a satisfactory experiment, but the results are not expected to be available until the end of the week*

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Project 3.1 -.Except for the physical daraage suffered by cubicle 3«ls, which was in the extremely strong pressure and drag region, performance seemed to be satisfactory. Of course, performance is coupletely dependent on the results of the structures instrumentation groups in projects under 3.28. Project 3*3 - Same as 3.1 with no damage effects. Project 3«U - The drag effects on the bridge sections appeared to be considerably larger than expected. The large truss bridge section failed conpletely. It is believed, however, that much useful informa tion was learned. Some missile damage was sustained due to the tre-- mendous amount of flying debris of other test targets. Project 3«6 - Project officer reports a very successful experiment. As he stated, they expected damage and they sustained damage. Many of the box cars were very heavily damaged. The two tank cars were blown distances of 2000 to 3000 feet, which will give some idea of the tremendous drag effects of this shot. The locomotive sustained no significant damage and continued to run throughout the Project 3*7 - On this target the pressures obtained were more than twice those expected and most of the instrumentation records were lost. The structure was damaged, which had not been expected. The very good results of Shot No. 9 make the results of this test of relatively minor importance. project 3.8 - The pressure obtained was about optimum for this experiment. The instrument records appear to be good and the permanent deflections are about as expected by the project officer. Project 3.9 - Excellent results were obtained on the passive thermal indicators. No examination of the field fortifications has been made because of radiation levels. It is expected that they were de molished because of their proximity to ground zero. Project 3.13a - The earth cover was removed from this building for this test. Minor cracking damage was sustained. A flying missile, a 6x6 transfer case, penetrated the building, leaving a very large hole. Project 3.13c - Eight channels were connected and the recorder Project 3.1U - The roof of this structure failed. No further observations can yet be detailed. Project 3.15 - Approximately 31 of the earth cover was removed from this target for this test. Very little damage was sustained.

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project 3«l8 - The project officer reports a very successful experiment. Approximately $00 of the 1300 live-mines installed were detonated by the blast effects. Project 3*19 - All instruments worked satisfactorily. No trees were broken in the forest stand or forest line. This test, of course, was designed for Shot No. 9 and no serious damage was expected on this shot. The front row of the stand showed deflections of approxi mately one-half of those obtained on Shot No. 9* It appears that the drag forces may have been larger than would have been predicted on the basis of peak pressure, when compared to the effects of Shot No. 9* At this distance the precursor had disappeared and the pressure-time record looked conventional. There remains the possibility that even for a conventional pressure-time curve the particle velocity may be abnormally high because of an earlier precursor. Project 3*20 - The radial pole line e;ctending from ground zero was knocked down out to a distance of 3000 feet and suffered moderate damage but to liOOO feet. This is in marked contrast to the negligible damage sustained from the relatively strong pressures on Shot No. 9* Other pole installations and equipment were severely damaged. The project officer reported a successful experiment. Project 3*21 - To say that the vehicles were seriously damaged would be a masterpiece of understatement. The lethal radius for jeeps and trucks is estimated at approximately 2300 ft., or to a pressure region far below where only minor damage was sustained on Shot No. 9* The project officer stated that damage was much worse than had been expected, A preliminary opinion has been offered that probability curves for damage to these targets cannot be drawn in terms of maximum pressures. The flying parts of demolished vehicles were thrown at tremendous velocities to distances of several thousand feet. The extent of damage and the potential missile hazard, as a consideration of equip ment exposed to such a shot, can only be appreciated upon an examination of the test area. Project 3*22 - The Bailey bridge was mounted on slides and 6 feet of sliding was predicted. The bridge appears to have slid for approximately five feet along the skids before it was lifted and thrown for a distance of approximately hS feet beyond the bridge piers. No damage was sustained by the bridge piers. Once again the damage was markedly greater tthan had been anticipated foil wing the results of Shot No. 9* The bridge at liiiOO ft. had been welded to the piers and no visible effects were reported. Project 3*2li - More damage was sustained than had been expected. The LVT at 1150 ft. was turned over and burned and the one at 1360 ft. was very severely damaged. Moderate damage was sustained at I63O ft. and 1870 ft., while only light damage was suffered at 2500 ft. and 2600 ft.

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Project 3.26.1, 3.26.2 and 3.26.3 - Because of the lack of strong damage effects on the POL installations on Shot No. 9 a few additional installations were made for all three projects on Shot No. Very severe damage was obtained. Oil drums and gasoline cans were thrown to distances of 900 to 2600 feet. The collapsible tanks were completely destroyed except for one 3000 gallon tank at a distance of 1700 feet. Some relatively small fires were obtained* The principal POL installations were made at nominal distances of 900, 1200 and 1700 feet. Severe damage was sustained to complement the minor damage sustained on Shot No. 9. Project 3.28.1 - On 331 channels connected 3Q5> records wereobtained. The 26 channels lost were due to various failures, including project 3.28.2 - On 103> channels connected 72 records were obtained. Many records were lost due to structure damage. For instance, the concrete cubicle of 3.1s was thrown over by the blast wave, negating the principal usefulness of this experiment. The underground blast baffle structure, 3.7, was subjected to more than two times the anticipated pressure causing severe damage and gross instrument failure. Project 3.28,3 - On 72 channels 72 records were obtained. The wave forms recorded were conventional. These instruments were installed on the 3.1 targets at a nominal ground range of L900 feet, where the side-on pressure measured was approximately 3*3 psi. and 20 self-recording peak pressure gages were installed. Only partial recovery has been made due to contamination. It is believed that good results were obtained. Pressure-time gages designed to be started by the burning of a nylon string and by the operation of an alarm clock Project U.2 - Seven hundred rats and 66 dogs were exposed at a distance from 9U0 ft. to 1600 ft. from the intended ground zero. The blast damage to the installations was far in excess of that anticipated, although the installations had previously been tested under strong pressure conditions. The pressures were increased appreciably because of the position error* practically all animals were killed. Autopsies will be performed on some of the dead dogs. Project officer states that preliminary examination does not show extensive lung hemorrhage and that no satisfactory explanation has yet been offered for the cause of death. Project U.7 - The project officer reports a successful experiment It appears that there is very little beta hazard. Project U.8 - The project officer reports a successful experiment with recovery of nearly all animals* It is possible that considerable

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interesting neutron injury was suffered by the mice, with a number of animals being expected to die within the next few days. Aircraft: Three aircraft participated, two of which reported successful measurements, but the other airplane measurements are doubtful due to a confusion in the countdown signal. Project 6,3 - Twelve B-36 aircraft were scheduled to participate. However, someone became confused about the scheduled shot time on FDT ani the aircraft arrived one hour late. Project 6,7 - The project officer reports a reasonably Project 6,8 - Operations were normal with the maximum pene project 6,10 - A satisfactory aerial survey was conducted project 6,12 - On the flash ranging two out of three Blue Boxes failed. The one remaining instrument measured the correct azimuth within one mil. The remote Bhangmeter gave a reading of about 20, which is in relatively good agreement with others. The seismic and sound ranging were reported as successful. Project 6,13 - Good operation was obtained on the fireball although immediately following the test many moving objects, presumed to be missiles, were reported on the screen. It is not expected that the radar tracking of the projectile was satisfactory, program 7 - Reported as a very successful experiment for the Project 8,1 - On 116 channels 109 records were obtained. Four additional instruments operated satisfactory until shock arrival. The parked aircraft at nominal distances of li>60, 1850 and 2100 feet were thoroughly demolished, while a similar aircraft at a nominal distance of 2300 feet showed only minor damage. It is possible that the aircraft at 2100 feet sustained some damage from a flying tank car and motor ■vehicle parts. Upon a casual examination there appears to be a very shaip barrier between the region of severe and light damage for the kind of pressure signals developed by this shot. Project 8,2 - Data were obtained from both stations but the . records have not yet been studied. The project officer states that he has been devoting his principal effort to finding an explanation for the $0% discrepancy between his measurements and those of other agencies.

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Project B.li - The wind conditions at the time of the test were somewhat erratic, particularly in direction. However, it was decided to proceed with the smoke experiment and a successful test can be reported. The wind velocity was \x-$ miles per hour. "White smoke: Because of the inability to operate the white smoke on Shot No. 9 a small experiment was added to Shot No. 10. The station of white smoke was located at 2166 feet from the intended ground zero. AH smoke fired satisfactorily and a good screen was obtained. The records were all recovered and the preliminary records indicated an attenuation of greater than 99%, It is possible that • some black smoke intercepted the thermal path of the white smoke. The Technical photography will answer this question. It is estimated that …