Operation Redwing, a Preliminary Report of () (Mohawk) (Deleted)

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Submitted by Task Group 7.1 .orized person is proh Ro _ OF ~ COPIES, SERIES A

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Observed Weather at Shot Time ................. Water Wave Studies . Fallout Location and Delineation by Aerial Analysis of Fallout and Ease Surge ....... Thermal Flux and Albedo

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!deaponEffects on Mssile Structures and Accurate Location of Electromagnetic Pulse Determination of Characteristics of Airborne Analysis of the Electromagnetic Pulse Produced bya Nuclear Explosion. ............. 55 Project 16.3 - Electromagnetic Investigations .......... 58 Project 21.4 - External Neutron Flux Measurements ........ 64 Project 23.3 and 23.4 - Time Interval and Time and Pressure

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Observed Weather at Shot Time Eniwetok Atoll Map Scientific Statiors and Zero Point

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ENIWETOK OBSERVED WEATHER FOR 3 JULY 1956 AT DETONATION TIME 0606M Sea Level Pressure 1010.2 mbs Free Air Surface Temperature 79.60F Wet Bulb Temperature 74.90F Dew Point Temperature 73.00F Surface Wind 100o 16 Knots stratocumulus; based at 4,800 ft.? tops unkno~. altostratus; measured bases al E,5~0 ft. (all opaque), tops at Intermittent light rain and overcast skies. AREA WXATHER SUMNARY FROM AIRCRAFT: 0555M; Entered clouds at 1,600 ft. Solid to 30,000 ft. 32 miles NNE 0644??: 40 to 50 miles to southwest of Eniwetok, reported moderate rime icing at 15,000 ft. 0700M : Scattered to broken cumulus based at 1,000-1,200 ft., tops 8,000 ft. Entered solid overcast at 9-10,000 ft. and ‘broke outn at U,ooo ft. Occasional rain in spots. Light to mcderate icing 17-24,000 outn at 14,000 ft. to the east. STATE OF SEA: Ocean Side: Wave heights 6 feet, period 7 seconds, direction 11OO. Lagoon Side: Wave heights approximately l+ feet.

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Program 1 - Blast and Shock Measurements Program 2 - Nuclear Radiation and Effects Program 4 - Biomedical Kffects Program 6 - Tests of Service Equipment and Program 9 - General Support

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To obtain blast pressure-distance information by means of direct shock Hiph speed photography was accomplished from the lJmckphoto tower. The photography was successful, and to satisfy the objectives of this shot. to EOL for analysis. enough information will he obtained ‘Ikeprocessed film has been returned

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To measure the physical characteristics of the crater produced by the low scaled heiCht of burst on this shot, and to correlate this informationwith past crater results. Stereoptic aerial photography was used to obtain crater data. successful. The film has been transmitted to ERDL for analysis.

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OBJECTIVES AND INSTRUMENTATION Studies of water wa-~eaction generated by the detonation of large yield ‘= nuclear devices are made at relatively close ranges and island stations by Project 1.9. Four shore recording wave (of the l&rkVIII type) were active in Bikini Lagoon for shot. In eddition, Project 1.? constructed end installed period wave recor6ers on Eni-tietok,Ailinginae, Wakej and These recorders are designed to document long period, low aqlitude deep ocean wsves of the tsunami type. The recorders operate continuously but G.nlyreceive si~nificant signals fron the large shots. In addition to the above instmentation, a tide ~a~e was active at Ailinginae }.toll,and Zzndia Corporation microbaro~r2#lic stations were operated by Project 1.9 at Make and Johnston. The le.goonand deep water long period recorders did not d?.tectwater wave

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Project 2.64- Fallout Location and Delineation by Aerial Sprvey - Participation in this shot was scheduled to obtain data which could be used to validate altitude absorption calculations. These air absorption factors are used to compensate aircraft dose rate readin~s to an equivalent This additional project participation was requested and app oved in June 1956, and was based on non-interference with the major (Navajo) operations scheduled soon after this shot. D+l: One project aircraft ’was requested for 0900 arrival at Eniwetok. After installation of the project equipment an aerial survey was scheduled (to include one pass over the islands in the atoll, lagoon, and an area search over the open sea out to D+2: The aircraft was scheduled to rendezvous three passes over the at Eniwetok and repeat the open sea survey if warranted by the results All plotting and flight planning was to ke on the previous day. done in the aircraft by two project passengers. The flight plotting, rather than a centr~ plot control was possible since close correlation ketween more than one aircraft and also between aircraft and ship elements was not required. A helicopter wzs scheduled for 13t2to perform sumeys over two islanc?s and open water at varying flight altitudes between 25 and 1,000 feet. A g=mna spectmm analyzer and specisl survey meters were to be installed for these measurements of altitude absorption coefficients.

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The flight altitude end operational plans were coordinated with the AOC (TG 7.4) and this organization assumed primary guard and SAR responsibility for the mission. The atoll and lagoon (Phase A and B) were surveyed immediately after take-off (1130 to 1230) and concluded with ~titude correlation pesses over Engebi at 100, 200, 300 and 500 feet. The area out to sea was surveyed from 123~ to 1500, and the mission terminated at Eniwetok. Based on the survey results, the aircraft was released for return to PATRON ONE at Kwajalein and the D+2 survey cencelled. The project equipment was installed, checked, end calibrated in the helicopter from 1015 throuph 1230 on M2. The mission then left ?arry and proceeded to Aonon. Altitude runs were made across the bunker. The helicopter was hovered for one minute at 500 and 800 feet altitudes to obtain gamma spectral data. The pilot could not hover at less than 500 feet, so that lower altitude data was not obtained. Rojoa was selected to provide intensity data over en area with a lower density of contamination. l.ltitudepasses were run over the air strip from levels of water The open water runs were czncelled due to the extremely low survey over the islzr.dsof the Eniwetok Atoll have been correlated to surface intensities. Examination of tkis data shows little or no fallout except the northeastern islands. Pzrry and Eniwetok were not surveyed, however, fallout intensity measured at the surfece reeched a peak No contamination could be detected in the legoon or at sea, ero~d t~e

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The altitude data is keing correlated to However, no early conclusions are available. based on an effective camma energy of 0.5 mev the theoretical calcuktions. The calculations have been on the basis bf the gamma spectrometer runs at 500 end 8?0 feet. This fiEure appears to be a reasonable

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project 2.65 - Analysis of Fallout and Ease Surge - M. Morgenthau To survey the close-in residual contamination field restitinS from the For this event the project had only limited participation, consisting of an aerial survey on 1<,N+lj end M+2 dfiys. The surrey was made of the portion of Eniwetok Atoll contaminated to a sipificent amount by this event. This included the islands ketween EnCebi and Aomn. Particular attention wzs paid to the residual contamination on Rujoru, Eberiru, and Aonon. The measurements were taken by meens of a probe on a long cable suspended below a hovering helicopter. The pozition of the probe W2S 2etermined by reference to ckarts and aerisl photographs. Aerial survey readings teken on three successive days were corrected for meter calibration end corrected to H+l hour values as shown in Table 2.65-1 by using tl.edecay exponent of -1.10. This decay exponent was determined from a plot of field dose rate readings vs time for three of the islands surveyed as shown in Fig. 2.65-1. These particular islands were chosen for this plot because of their low background prior to the shot. H+l hour efirapo~~ted readin~s for Eberim Island are skown in Fig. 2.65-2.

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Island Point shot (hrs) RujorU 1 9.97 1700 These readings were not (horth) 2 31.8 2700 extrapolated to H+l hr due to 3 55.9 3000 uncertainty of residti contamination fron Inca shot. not considered in the avera~e due to its obvious complete lack of a~reement with the other data.

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TIME (HRS. AFTER BURST) Aerial Survey Readings at 3 Ft. Level n on Thra

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The primary objective of this project is to obtain information on the requirements for protection of the eyes against chorioretinel burns from atomic detonations of various yields; ‘–— Corollary technical objectives at the same yield are to: Determine whether blink reflexes will prevent ckorio-etinal burns. Ascertain which portions of the time-intensity pulse can produce injury to the retina and choroid of the eye. Det~rmine the time required for blink reflex (Bl?T)in rabbits and exposed to the extreme light intensity of the atomic detonation. Explore the feasibility of ocular protection by means of fixed Test, under field conditions, protective shutter devices which are in the developmental stege end which me designed to close much more rapidly The basic instrumentation for this shot was identical to t!at used for previous shots. In addition instrumentation on loan from project 2*65 (~mY CherricalCenter) was employed for measuring the thermal radiation dosage received at exposure sites on Japtan (David) and !lunit(Yvonne). This instrument gives no information on pulse shape. Chorioretinal burns were produced in 19 of 92 rabbits and 8 of 8 monkeys participating in this shot. All cf the tins were produced at the Runit site. .

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Failure to produce burns at Japtan sust&ined the decision to move the mein exposure fgcility from its former location to Runit. Tkledisperity betxeen the reasured end predicted or calculat~d dosage &t this locztion is attributed to instrument&tion operating &t its Plink Reflex Studies Animals were allowed to tection. Blink reflex times view the flash ad libitum without eny prowill he determined Et the 21 by evaluation of high speed Fhotogrephy accomplished during the flesh interval. This exposwe series protuc=;dchoricretinal burns in 6 of 8 rakbit.s.sndE!of 8 monkeys at Runit. .:.vo ng the r~bbits the burns were moderate to severe and all were wzs observed in only one instance. It is czlcu2zte5 thzt equivalent lesions would have been produced in m,anEt a distance of about 5.1 tiles. Among the monkeys both eyes received bums. In one cese finer henorrha:ir.gin one eye and in another instsnce central her:orrhagingof both eyes wzs o%served. The two rerzining animals had lesions the size of cor.p5reblEto those which were encountered at 3 to 5 miles distEnce froc ‘he

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A note of special interest is thet some indication of the fireball size as a function of yield is found in B comparison of the ERT data of the present shot f l’d.d. were produced by exposure to the At essentially the same distance, much smaller lesions averaping only l/4 produced at Japtan by the ne= At this distance the small difference of 1/2 rrdlehas a ne~ligible effect upon the size of the image of These shutters were open increasing by 10 msec through the fireball upon the retina. at zero time and closed in pairs at intervals 100 msec. The remainder of this series, also open at zero time, closed in pairs at 120~ 250~ and lCOO msec. The exact time of closing will be determined at a later date from evaluation of the high speed photography ecconplished during the flssh interval. The time for the minirum following tliefirst pulse is calculated at 50 t 2 msec. It is of interest that 4 of 15 rabbits received burns during this period. In fact, 2 animals appear to have sustained retinal damage as early as the first 10 msec of the flash. At comp~,r~bledistances the incidence of ) 1s about 25 percent for both shots. All of the lesions from the first wave of the power pulse were mild and small, ranging from pin-point to about 1/3 d.d. in size. No burns were produced behind shutters open in the range between O to 60 ~d O to 250 msec except in one case at the latter limit where a small double burn occurred. This apparent inconsistency in the data is unexplained at the

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These shutters were closed at zero time but subsequently were opened for a pre-selected time interval during the power pulse. Four of 16 rabbits su=tained burns in this series. The interval of 10 to 250 msec produced a lesion in 1 of 2 animals exposed. In 2 of 2 rabbits the increment of 10 to 1000 msec produced burns essentially the same size and severity as those observed in the ERT study. The interval of 500 to 600 msec c~used a s~l mild burn in 1 of 2 animals. Although this animal was exposed only about one-third of his blink reflex time, the dose rate was near the maximm for this shot. The time of the maximum is calculated at about 600 f 20 rsec. No burns were produced after the first second of the flash, No burns were sustained by the 2 rabbits exposed behind these shutters. Unfortunately the electronic recordin~ system for these devices was inoperative at,the time of the shot. The restits of this Fortion of the study are Only 2 burns were produced in 27 exposures behind the fixed density optical filters. These lesions were both l/2 d.d. in size and were moderate severity. Unexplainably, neither burn was produced behind least protective filters. The blink reflex time for man and enimals is not fas egainst the flash from an atoric detonation An air bu-st of this size on a clear day (90 percent trans~ission/mile) is sufficient to cause large chorioretinal burns in rabbits and monkeys at 7.6 statute miles and in mm at 5.1 statute dies. Additional data are neede? in order to este?lish the limjtinE distance for burns

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w other yields. The results of the test indicate that burns could be encountered by man at distances greater than 5.1 miles but not as far as 11.5 miles, except where atmospheric transmission is greater than 90 percent per mile. Note is made that this condition is met at high altitudes and in geographical areas such as the Nevada Test Site.

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The objective of this project is to measure the effects of a nuclear detonation on an in-flight B-47 blast, gust and thermal afrcraft. With the recorded data, the criteria and method used in the >47 Weapon Delivery Handbook may be verified or corrected. In addition, the project will provide kasic research data for the design criteria of future USAF aircraft. Two hundred and seventy-three data channels were available on this shot including seventeen new channels at station 1044.0 of the fuselage to measure bending, shear and torsion from side loads. The remaining ch~- nels recorded bending, shear and torsion in the wing and horizontal stabilizer, thermal inputs to the aircraft, thermally induced strain, temperature measurements and overpressure. Prior to shot participation 9’7%of these channels were operating satisfactorily. The B-47 aircraft was The aircraft was flying at of 40,000 feet, a speed of positioned for side-loads effects in this event. an absolute altitude of 37,000 feet, an offset Yach 0.75 and on a heading of 0210 at both To and shock arrival. At ‘TOthe shot was ahead and to the left of the aircraft such that the horizontal range was 32,000 feet short of a point directly abeam of ground abeam of ground zero and zero. At shock arrival the aircraft was directly exactly tangential to the impinging shock wave.

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Thermal: The temperature rise was insignificant …