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TE A POT.SNEVADA TEST SITE

SFebruary -May 1955

CID Project 8.1MEASUREMENT OF DIRECT AND GROUND--

REFLECTED THERMAL RADIATION AT ALTITUDE

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This document consists of 54 Pages,No. 14 5 of 210 ooples, Series A.

'WT-1i43 // i ~ '

OPERATION TEXOT-PAWECT 8.1

Report to the Test Director

MEASUREMENT OF DIRECT AND GROUND-REFLECTED THERMAL RADIATION AT ALTITUDE CaV

A. lCviljor(I/ iNaval Air Material CenterPhiladelphia, Pensylvana

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ABSTRACT

The purpose of this project was to perform measurements of the thermal energyreceived by aircraft positioned at various distances from nuclear detonations. Measure-ments were to be made to study the contribution of thermal radiation reflected from theearth' s surface to the total radiation received by the aircraft. Ninety-degree-field-of-view calorimeters and radiometers were used to record the thermal radiation under twoconditions: (1) calorimeters and radiometers oriented to include radiation received di-rectly from the fireball and (2) calorimc.ters and radiometers oriented to receive ground-reflected radiation from the earth's surface directly below the test aircraft. Total spec-trum and broad-band spectral measurements were made in each cae. An ancillary phase,of this project was to obtain the temperature rise and decay from thermal radiation in air-craft skin specimens both exposed to and shielded against the effects of aerodynamic cool-ing.

Recorded total thermal energy data for the two situations above based on 12 aircrafttest positions are reported herein, together with an experimental check on existing theo-retical treatments. Also reported are thermal energies recorded under broad-band filtersand related temperalQre data of aircraft skin samples exposed to and shielded against thefree airstream. - L

It is concluded that: 4) the theoretical values for the reflected radiation are compa-rable within 10 percent to the-exper'mental values; the contribution of atmospheric scat-tered radiation cannot be neglected and in the case where fine particles of matter (likedust) exist in the vicinity of the explosion, the contribution of the scattered radiation in-creases; 0) random satter in ground-reflected energy measurements under broad bandfilters prevent the establishment of a ground-reflected to drect-enerr spectral distri-bution ratio; and 4 aerodynamic cooling had no appreciable effect on the temperature inexposed skin specimens at indicated airspeeds of 175 knots insofar as reducing the maxi-mum temperature rise of 175 degrees Fahrenheit attained by similar specimens shieldedfrom the airstream.

It is recommendr that: (1) analytical data for predicting the ratio of ground-reflectedto direct radiation be c*Rsidered valid provided proper allowance is made for atmosphericattenuation and scattering; (2) an experimental check of analytical data be made for weaponsexceeding 43-kiloton total yield to further evaluate ground and atmospheric reflection, at-tenuation, and scattering effects; (3) a further evaluation be made of the effects of surfacecoating damage to aircraft skin temperatures when thermal field pulse inputs reportedherein are utilized in lieu of rectangular pulses.

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FOREWORD

This is one of the reports presenting the results of the 56 projects participating inthe Military Effects Tests Program of Operation TEAPOT, which inoluded 14 test detona-tions. For readers interested In other pertinent test information, reference Is made toWT-1153, "Summary Report of the Technical Director," Military Effects Program.This summary report includes the following information of possible general interest:(1) an overall description of each detonation, including yield, height of burst, groundzero location, time of detonation, ambient atmospheric conditions at detonation, etc.,for the 14 shots; (2) discussion of all project results; (3) a summary of each project, in-cluding objectives and results; and (4) a complete listing of all reports covering theMilitary Effects Tests Program.

PREFACE

The test program reported herein was successfully accomplished through the com-bined efforts of many individuals, both military and civilian, representing many differ-ent agencies. Although individual acknowledgments oannot be made here, the followingis a list of the organizations who contributed to the success of this program: Bureau ofAeronautics of the Navy; Directorate of Weapons Effocts Tests, Armed Forces SpeoialWeapons Project; Naval Air Special Weapons Facility; Naval Air Missle Test Center,Naval Radiological Defense Laboratory; Douglas Aircraft Company, Inc., El SegundoDivision; Naval Ordnance Test Station; Air Force Cambridge Research Center; WrightAir Development Center; and Air Force Opecial Weapons Center.

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CONTENTS

ABSTRACT . . . . . . . . . . . . . 3

FOREWORD . . . . . . . . . . . . . . 4

PREFACE . . . . . . . . . . . . . . . 4

CHAPTER 1 INTRODUCTION. . . . . . . . . . . 9

1.1 General . . . . . . . . . . . . . 91.2 Project Objectives 10

CHAPTER 2 EXPERIMENT DESIGN . . . . . . . . . 11

2.1 Background and Theory . . . . . . . . . . 112.1.1 Thermal Radiation . . . . . . . . 112.1.2 Temperature Rise in Aircraft Skin Panels. . . . . . 142.1.3 Spectral Composition of Direct and Reflected Radiation 14

2.2 Test Procedures and Condition. . . 142.3 Instrumentation . . . . . . . . . . . . 17

2.3.1 General Arrangement . . . . . . . . . . 172.3.2 Instrumentation Equipment . 17

CHAPTER 3 RESULTS . . . . . . . . . . . . is

3.1 Calorimeter Data . . . . . . . . . . . 13.2 Radiometer Data . . . . . . . . . . . 183.3 Skin Sample Temperature Data . . . . . . . . . 18

CHAPTER 4 DISCUSSION . . . . . . . 23

4.1 Experimental Check on Analytical Data . . . . . . 234.1.1 General . . . . . . . . . . . . . 234.1.2 Data Reduction Procedure . . 234.1.3 Correlation of Data . . . . . . . . . . 37

4.2 Recorded Thermal Data . . 74.3 Spectral Energ Distribution . . . . . . . . . 374.4 Temperature Data . . . . . . . . . . . 38

CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS . . . . 50

5.1 Conclusions . . .g.. . . .. 505.1.1 Experimental Check on AnaJtcal Data . • 05.1.2 Spectral Enera Distribution . . . . . . . . 505.1.3 Temperature Data . . . . . . . . . . 505.1.4 Operational Success . . . . . . . . . . 50

5.2 Reoommendtions . . . . . . . . . . . so

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5.2.1 Thermal Data 50

5.2.2 Temperature Data 50

APPENDIX 51

REFERENCES . . . . . . .52

FIGURES

2.1 Ratio of Reflected to Direct Radiation 122.2 Ratio of Reflected to Direct Radiation 132.3 AD-4B, AD-6, and AD-5 Test Aircraft . 152.4 Pilot's Protective Thermal Hood . 152.5 Modified APS-19 Radar Nacelle with Instrumentation Installed 163.1 Energy-versus-Time Curve, Shot 12, AD-5 . 203.2 Irradiance-versus-Time Curves, Shot 12, AD-5 . 203.3 Skin Temperature Time Histories, Shot 12, AD-5, Direct 213.4 Skin Temperature Time Histories, Shot 12, AD-5, Ground-Reflected 224.1 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 4, AD-6 254.2 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 4, AD-4B 264.3 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 6, AD-5 274.4 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 6, AD-6 284.5 Airplane Position and Theoretical Ratios of Ground-Reflcted

to Direct Radiation, Shot 8, AD-5 294.6 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 8, AD-4B . . . . . . . . 304.7 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 8, AD-6 314.8 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 12, AD-6 324.9 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, 8hot 12, AD-5 334.10 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 12, AD-4B. . . . . . . . 344.11 Airplane Position and Theoretical Ratios of Ground-Reflectd

to Direct Radiation, Shot 13, AD-4B . 354.12 Airplane Position and Theoretical Ratios of Ground-Reflected

to Direct Radiation, Shot 13, AD-5 . 364.13 Measured versus Calculated Direct Energy Data . . 384.14 Measured versus Calculated Indirect Energy Data . . . 394.15 Energy per Kiloton versus Sant Ree . . . . . . 394.16 Normalized Irradianoe and Generalized Field Pulse versus Time, Shot 4 404.17 Normalized Irradiance and Generalized Field Pulse versus Time, Sbot 6 414.18 Normalized Irradiance and Generalized Field Pulse versus Time, Shot 8 424.19 Normalized Irradianoe and Generalized Field Pulse versus Time, hot 12 434.20 Normalized Irradianoe and Generalized Field Pulse versus Time, Shot 13 444.21 Energy versus Skin Temperature Curves (Quartz Filter) . . . 45

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4.22 Energy versus Skin Temperature Curves (No Filter) 464.23 Temperature Rise versus Energy Curves . . . 474.24 Temperature Rise times Slant Range versus Total Yield Curves

(Quartz Filter) . 484.25 Temperature Rise times Slant Range versus Total Yield Curves

(No Filter) . 49

TABLES

3.1 Summary of Direct and Ground-Reflected Data. 194.1 Percent of Total Direct and Ground-Reflected Filtered Energies 37A.1 Summary of Direct Energy Data Computations. 51A.2 Summary of Ground-Reflected Energy Data Computations . . . 51

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SECRETChapter I

INTRODUCTION

1.1 GENERAL

Thermal radiation is one of the primary effects produced by a nuclear detonation.Thermal radiation becomes the prime consideration for some aircraft weapon systemsin the determination of criteria for safe delivery of nuclear weapons when the yield ex-ceeds about 30 kilotons, and definitely becomes a more Important factor for high yieldweapons. Therefore, it is necessary to determine the various factors which constitutethe spatial and temporal variation of thermal radiation and the mechanism by which thethermal radiation produces a resultant temperature Increase in aircraft components.

The basic factors are: (1) the quantity of thermal radiation produced as a functionof yield, (2) the time dependence of thermal emission, (3) spectral distribution, (4) thescattered and reflected radiation which augments the direct radiation, and (5) the atmos-pheric attenuation of the radiation. To date much data has been accumulated in References1 and 2 The total thermal energy produced for an air burst is given by Y (cal) =0.44 10 1"W" where W is the total yield in kilotons. The radiant power consists of twomaxima where the time to the second tmax = 0.032 WOA where tmax i in seconds when Wis expressed in kilotons. For surface bursts and near surface bursts the quantity andtime-picture is incomplete until an air burst in the megaton range is performed for com-parative purposes. In Reference 3, the effect of the distorted fireball on thermal yieldis discussed. However, more knowledge of the spectral and spatial distributions, particu-larly in the infrared region during the second pulse for all conditions of burst, was ne-oessary. This information was required to determine (1) the reflection coefficient of theground surface, since this coefficient has a spectral dependence, and (2) the absorptioncoefficient of the aircraft skin surface. Much data has been available on the spectral dis-tribution of direct radiation; however, no data was available on the reflected radiation.Some data had been accumulated on the scattered radiation and attenuation (see Reference4 and its bibliography), but considerable work still remained. No complete experimentalprogram had been executed on reflected radiation from a nuclear detonation. To limitthe effort and fill the largest gap, this program was undertaken.

The only extensive theoretical predictions for reflected radiation for a homogeneousabsorbing but nonscattering atmosphere were available in Reference 5; however, recentcalculations with greater numerical accuracy have been performed at the National Bureauof Standards, using the S. E. A. C. computer under Armed Forces pecial Weapons Projectsponsorship, and at the Douglas Aircraft Corporation on the IBM MK-701 oomputer. Thelatter two are self-consistent. In all Instances a point source was assumed along with aninfinite reflecting plane obeying Lambert's law. These particular calculations were forthe case of a 2w steradian receiver oriented parallel to the reflecting plane. Additionalcalculations were also performed by the Douglas Aircraft Corporation for the speoiflocases of interest here. These were: (1) 90-degree-feld-of-view receiver oriented to-ward the fireball and (2) 90-degree-field-of-view receiver with surface of the sensing ele-ment parallel to the earth's surface. These calculations were required to determine thedegree of validity of the theoretical predictions.

SECRETRESTRICTED DATA

1.2 PROJECT OBJECTIVES

The specific objectives of this project were:1. To study the direct and ground-reflected components of thermal radiation by

measuring that radiation received at different points in space relative to the burst by meansof 90-degree-feld-of-view calorimeters aimed directly at the fireball and ground directlybelow the test aircraft. These measurements were required as an experimental check onthe analytical data contained in Reference 5. These analytical data have been used as oneof the bases for establishing effects envelopes for the safety of atomic weapon delivery tac-tics employed by the Fleet. These criteria are contained in Reference 6.

2. Since the reflected radiation may have a spectral dependence different from thedirect radiation as a consequence of selective absorption by the reflection plane, measure-

ments on the spectral composition of both the direct and reflected components as re-corded by 90-degree-field-of-view calorimeters aimed directly at the fireball and theground below the test aircraft were performed.

3. To obtain time-histories of the temperature rise and decay in aircraft skin speci-mens, exposed to and shielded against the effects of aerodynamic cooling. These dataare required to supplement similar data obtained by Project 5.1 during OperationUPSHOT-KNOTHOLE.

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Chapter 2

EXPERIMENT DESIGN

2.1 BACKGROUND AND THEORY

2.1.1 Thermal Radiation. Aircraft flying in the vicinity of an atomic explosion aresubjected to the following major weapon effects: gamma radiation, thermal radiation,gust loading, and shock overpressure. These effects are of primary significance in theestablishment of techniques and procedures to be utilized in the delivery of atomic

weapons.The test result obtained by Project 5.1 during UPSHOT-KNOTHOLE (Reference 7)

clearly demonstrated that as much as 40 percent of the total thermal radiation receivedby aircraft in flight was due to ground reflection of the incident radiation. Similar daiahave also been obtained during other experimental tests (Reference 2). In order to es-tablish reliable thermal effects criteria, the amount of reflected thermal radiation to bereceived at various points in space about the burst center under different conditions mustbe predictable within reasonable limits. Analytical procedures and methods for accom-

plishing this have already been developed (Reference 5). The data have been utilized asone of the bases for establishing the thermal radiation effects criteria as included in the

present U. S. Navy Effects Handbook (Reference 6). All the effects criteria and guidesgoverning the safety of atomic weapon delivery tactics employed by the fleet are con-

tained in this handbook.As presented in Reference 6, the radiant energy (direct and reflected) received in

space, assuming a nonscattering homogeneous atmosphere, is given by the expression:

Wth [ + Ezr/Ezd] cos i (e - a R )

E = - (2.1)

Where: E = total energy in cal/cm'

Wth = thermal source in calories

cos'i = cosine of angle between radius vector for source toreceiver and the normal to the receiver

a = atmospheric attenuation coefficientR = slant range distance in centimeters

= ground reflected energy from an infinite planeREzr = direct energy normal to receiving surfaceREd

The bracketed expression represents the increase to the direct radiation due to re-

flection, provided the appropriate value for Ezr/Ezd, which is a function of the orienta-tion of the receiver, is available. In the event that the receiver is parallel to the groundand has a 2-steradian field of view, generalized curves are available in Reference 5which permit the determination of the theoretical values of #-I(Ezr/Ed), where 0 is thesurface reflection coefficient for all spatial locations of interest. For the particularburst heights employed here, namely 300 and 500 feet, the individual curves are shownin Figures 2.1 and 2.2. The ratio Ezr/Ed to then obtained directly by multiplying by the

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appropriate value of 3 for the particular reflecting surface under consideration. Sometypical values of 0 are given in Reference 6, pages 3-16 and 3-17. The reader is re-ferred to Reference 5 for the theoretical development of reflected radiation received bya receiver parallel to an infinite reflecting plane and also when normal to the radius vec-tor through the source.

2.1.2 Temperature Rise in Aircraft Skin Panels. Measurements of the maximumtemperature rise attained to date in the metal skin of the test aircraft were made by Pro-juct 5.1 during UPSHOT-KNOTHOLE. The majority of such measurements were madeusing passive type thermal indicators (temperature tapes). A limited number of time-histories of the temperature rise in skin specimens were obtained using temperaturegages. The data obtained from these measurements are contained in Reference 7. Ingeneral, the application of temperature tapes exhibited definite limitations, and the dataobtained could not be consistently correlated with measured thermal inputs and visiblethermal damage. Additional skin panel temperature-time data are required to supple-ment the data previously obtained before a complete evaluation and correlation of all datacan be made.

As presented in Reference 6, the maximum temperature rise in aircraft metal skinexposed to thermal radiation, without cooling, is given by:

(TM - TA) = pE (2.2)pCpt

Where: TM = maximum allowable skin temperature (°F)TA = ambient air temperature (OF)

E = thermal input as defined by Equation 2.1p = specific density of materialCp = specific heat of materialt = thickness of material (ft.)y = thermal absorption coefficient (non-

dimensional)

Considering the effects of aerodynamic cooling the maximum temperature rise isgiven by:

(TM - TA) = FVE (2.3)pCpt

where F is the convective cooling factor dependent upon air speed, altitude and time ofirradance of the receiver. (See Reference 6 for a complete discussion).

2.1.3 Spectral Composition of Direct and Reflected Radiation. Information is re-quired concerning the spectral composition of the reflected component of thermal radia-tion to ascertain which (if any) wave lengths of bands of the spectrum are absorbed by thereflecting surface. By comparison with the spectral composition of the direct radiation,certain portions of the spectrum may be shown to have a direct relationship to the thermaldamage experienced by different type surface finishes.

2.2 TEST PROCEDURES AND CONDITIONS

Three instrumented model AD type aircraft, Figure 2.3, participated in Shots 4, 6,8, 12, and 13 of Operation TEAPOT. One of the three AD aircraft served primarily as astandby aircraft, except during Shots 8 and 12 when records were obtained with all three

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Figure 2.3 AD-4B, AD-6, and AD-5 Teat Aircraft.

Figure 2.4 Pilot'Is Protective Thermnal Hood.

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A".

Figure 2.5 Modified APS-19 Radar Nacelle with Instrumentation Installed.

aircraft. During each shot, test aircraft were flown at approximately 175 knots indicatedair speed (AS) In counter-clockwise orbits about ground zero, initiating standard-ratebreak-away turns after detonations. Utilizing a thermal hood over the cockpit, Figure2.4, and special goggles for pilot's protection against thermal radiation, one or two testaircraft were monitored by MBQ-I ground radar control and Instrument flight rules.Since MQ-l control was only available for one or two aircraft, when two or three testaircraft participated, the third and at times the second aircraft flew formation on themomitored aircraft with visual flight rules except for the period of the initial flash duringwhich time the thermal hood was in place and instrument flight rules prevailed. Eachaircraft was assigned to fly at a different altitude and horizontal range (radius of orbit)from ground zero. At T-20 seconds the instrumentation recording equipment in eachaircraft was turned on by the pilot. At approximately T + 2 seconds the pilot executed astandard rate turn to the outaide of the orbit In order to receive the subsequent shookwave in a near "tail-on" position. Each aircraft was instrumented to measure and re-cord the following data at time zero: (1) the direct and reflected components of thermalradiation received at the aircraft position in space, (2) the time-history of the tempera-ture rise in eposed aircraft skin specimens, and (3) the spectral composition of thedirect and reflected components of thermal radiation.

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The aircraft test positions for each of the shots are shown in Figure 2.2. Test po-sitions were selected which would give the maximum possible distribution of data pointswith respect to the burst center. From such data experimental check Ezr/Ezd curvessimilar to those shown on Figures 2.1 and 2.2 could be made.

2.3 INSTRUMENTATION

2.3.1 General Arrangement. Each test aircraft was equipped to carry a modifiedAPS-19 radar nacelle which was mounted on the underside of the port wing on the wingbomb rack, as shown in Figure 2.5. All radar gear was removed from the nacelle. The

nacelle, or tank, was modified to carry all the instrumentation measuring and recordingequipment. During tests, all equipment was turned on by means of a switch in the cock-pit of the aircraft. The instrumented nacelles could be readily installed or removed fromthe test aircraft for maintenance, servicing, or repair of test equipment.

Essentially, two similar sets or banks of measuring instruments were carried ineach tank. Each set or bank of instruments consisted of four Naval Radiological Defense

Laboratory (NRDL) disc-type calorimeters and one NRDL foil-type radiometer, six air-craft skin-panel temperature specimens, and two 16-mm gun-sight-aiming-point (GaAP)gun cameras. Each bank of instruments was mounted in the tank in such a manner that,as the test aircraft flew in a circular orbit (counterclockwise) about ground zero, one

bank looked at the burst point and the other bank looked at the ground immediately belowthe test aircraft. The position of each bank of instruments in the tank could be adjustedon the ground to maintain the above reference, depending upon the planned position of theaircraft for the particular test.

2.3.2 Instrumentation Equipment. NRDL disk-type calorimeters and foil-typeradiometers having a 90-degree field of view were used for measuring thermal radiation.Quartz filters, having a transmissivity of 92 percent, were used on two calorimeters andone radiometer of each bank of instruments for measurements of total radiation. Yellow,and red filters having a transmissivity of 90 and 88 percent, respectively, were used onthe other two calorimeters for spectral measurements. Sixteen-millimeter OSAP guncameras were also used to photograph and check the alignment and field of view of thecalorimeters during the test and to provide a basis for correcting calorimeter datareadings which were "off target."

Thermocouples attached to the aft side of aluminum skin specimens (1%-inchdiameter specimens, 0.016 inch thick, having various surface finishes) were used forobtaining temperature-time histories. On some tests the surfaces of these specimenswere exposed to the airstream; on some other tests, quartz filters were used to shieldthe specimens against airstream cooling effects.

A further description of the instrumentation is presented in Reference B.

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Chapter 3RESULTS

Direct and ground-reflected calorimeter, radiometer, and skin sample temperature

time-history recordings were obtained for 12 different test positions during OperationTEAPOT. A summary of peak recordings with aircraft test positions during Shots 4, 6,8, 12, and 13 is presented in Table 3.1. Typical time-history plots for each of the aboveparameters are presented in Figures 3.1 to 3.4. All direct and ground-reflected record-ings were incident on sensing elements of 90-degree-field-of-view calorimeters and ra-diometers. Aircraft positioning data shown in Table 3.1 were determined from MBQ-1radar plot board data.

3.1 CALORIMETER DATA

Calorimeter data were read directly from oscillograph records by means of a tele-

reader. Proper thermal and electric calibration constants, calorimeter disk heat lossand filter transmissivity corrections were applied. Gun camera records of fireball and

ground directly below test aircraft showed that aiming corrections to recorded valueswas unnecessary. Calorimeter data recorded by oscillograph Channels 4 and 7 repre-sent total direct and ground-reflected energies under clear quartz filter, while data re-corded by Channels 5 and 8 represent energies under yellow (3-69) and red (2-58)Corning filters. Respective spectral ranges for these filters were 2,200-45,000;

5,300-25,000; and 6,400-25,000 A as shown in Reference 2.

3.2 RADIOMETER DATA

Radiometer data were reduced by the same method applied to calorimeter data,

except no heat loss correction was applied. Oscillograph Channel 6 recorded irradlanceunder clear quartz filter. Peak values and time to second maximum are presented inTable 3.1.

3.3 SKIN SAMPLE TEMPERATURE DATA

Skin sample temperature data were reduced by the same method applied to radiom-

eter data. Oscillograph Channels 1, 2, and 3 recorded temperatures of bare, white,

and blue painted 1/ 4-Inch-diameter, 0.016-inch-thick aluminum akin samples eosedto the airstream. Channels 10, 11, and 12 recorded temperatures of the same snsamples, respectively, but shielded against the airstream by clear quartz filters. Maxi-mum recorded temperatures in all skin samples (both exposed to and shielded agait thefree airstream) are shown in Table 3.1 for all test conditions. Typical time-histories oftemperature rise and decay in exposed and shielded skin samples are shown in Figures3.3 and 3.4.

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TABLE 3.1 SUMMANT OF IXZC AND OaOtuiD REFLECTED DATA

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19

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x Ch~~e 4 (Quart:)£ * 7(overtg)

Os .6(2-541

w

t

t

Time ,scorift

Figure 3.1 Energy-versus-Timo Curve, Shot 12, AD-5.

0

0

91 0.4 @4 GO . I 1 5 0 t

Time ,seconids

Figure 8.2 Irradianoe-veru-Time Curves, Shot 12, AD-S.

20

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ISO

X - Channel I Bare SkinID is 2 White

ISOA z i 3 Blue aI + so 10 Bore a

ala IlI WhiteII 12 " lBlueI No Filter

140 I Quartz Filter

20

06

0

0 4 1 10 1oTime, seconds

FW=r 38 In TeMPeratur Tim HiatOrlsSo 12, A".S DireCt.

21

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'so

X Channel I Bore Skin

60o 0 is 2 White i

so 3 Blue 1+ If 10 Bare if

- (3 so I I White0 to 12 Blue

140- No Filter140-----Quartz Filter

120-

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0.@1

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Time, secondsFigur M. Mmn Temperatr Time Histories, &At 12, AD-5, Ground-Reflected.

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Chapter 4

DISCUSSION

4.1 EXPERIMENTAL CHECK ON ANALYTICAL DATA

4.1.1 General. The analytical approach to the problem of the quantity of reflectedradiation received by a detector considered a nonscattering, nonabsorbing atmospherewhere the reflecting plane was infinite in extent. The experiment conducted here ob-viously did not satisfy this ideal model and therefore the reduction of the data entailedconsiderable analysis. Specifically, the reflected radiation received by the instrumen-tation installed to observe direct radiation had to be subtracted, and conversely, the so-called indirect instrumentation at times received direct radiation. In either case, onlyfinite areas of the reflecting plane were observed. Also, the observations were made ina real atmosphere where attenuation and scattering existed, thus requiring suitable or-rections for these factors. The method of data reduction and results are presented below.

4.1.2 Data Reduction Procedure. The total energy received by an airborne receiv-er with a solid angle larger than the solid angle subtended by the fireball will consist ofdirect, reflected, and scattered radiation, where the contribution of each to the totalwill differ with spatial location and aiming direction. Here the aiming directions wereeither (1)through air zero (direct) or (2) normal to ground (indirect). Each case will nowbe considered.

1. Direct Radiation. The radiation measured on the direct calorimeter, Edm, canbe defined by the expression:

Eft = Ed* I+ d K + (4.1)

Where: Ed* = contribution of the radiation emitted by thefireball proper

Er = total reflected radiationE e = scattered radiationEd = direct radiation in vacuo defined by Wth/4R 2

R = slant rangeK = attenuation correction to the reflected radiation

The value of P for the Nevada Proving Grounds has been determined to be 0.40. Thevalue for i has been approximated in the folo.ng fashion. The atmospheric transmis-sivity for the participating shots were given as 95 percent per nautical mile, and the av-erage ratio of length of the path trmnsversed by the rays of the reflected to the directradiation is approximately 1.5, hence:

Er (0 .9 5)1" n Er Er- K (4.2)

Ed (0:9 5)n Ed Ed

23

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where n is the slant range in miles. Replacing K by its value in Equation (4.2), we canwrite (4.1) as rEr E~Edm = Ed* 1 + 0.40 d 10.95) 'n + E* (4.3)

To determine Ed*, the computed values of Er/Ed were employed where

Er Ezr Err- = - cos i + z- sin1 (4.4)

Ed EJd Ed

The numerical values of Ezr/Ed and Err/Ed for each shot are given In Figures 4.1 to 4.12.Ezr and Err are the vertical and horizontal reflected energy components, respectively,and "i" the angle of incidence of the direct radiation to Indirect calorimeter. (See dia-grams).

Direct Calorimeter Indirect CalorimeterErr

Ed iE Ed Ez IEzd Ed Cos i

The values for Es/Ed* are computed in Reference 9 for a 41 receiver and single scatter-ing. However, field-of-view meamurements d:rling the past several operations indicatethat all but 10 percent of the total energy is received by a 90-degree-feld-of-view do-tector. With this correction, the values of Es/3d* for slant ranges considered are 0.05to 0.07. To simplify the data reduotion, a fixed value of 0.05 was taken. On substitutionof the appropriate values into the bracketed expression, the value of e* was obtained,and on dividing 3d* by the direct transmissivity (0.95) n the in vacuo value of the directradiation E was obtained.

2. Indirect Radiation. In a similar manner the radiation illuminating the indirectcalorimeter can be expressed as: Ear+ -*.]

Ed-Ed* coi+L o(.95)'" +- - (4.5)I'd ZdJ

The above symbols have been defined previously. To determine find, the values of E*found above were employed and the analytical values of Ear/d in FIgums 4.1 to 4.12.For close-in stations where the indirect calorimeter Included the fireball, a fixed valueof Es/Zd* = 0.05 was taken. For the further-out station where V decreased, the valueof 34/3d* became largr, since g was umes ted. Finally, when the indirect calorim-etar did not include the fireball and the direct radiation was large, the contributions fromscattering would tend to increase the frations. Considerable scattering in dust-laden airat the quite low aircraft altitudes spparently was received by the calorimeter. In thisinstanoe the value of Zs/d*m 0.15 & 0.05. For this analysis a fed value of 0.15 wasassumed. The coo i term was dropped, since the normal component of direct radiationreceived by the indirect calorimeter was onsidered nil.

24

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130-

0

0

View of' Direct \ View of VerticalCalorimeter \ Calorimeter

50 40 30 20 10 1 o3Horiz. Distance 103O ft

Vert. Reflected

/Direct 9.3

30[g Reflteted z 0.787

PLAN VIEW

7 Airplane Position9010'Altitude

1I0

SIDE VIEW wrtical

f Direct Calorimeter ~ fK)lrm rez e 500"fAt

5 40 30 20 10 10 t0 30Horiz. Distance, 103 ft

Figure 4.1 Airplane Position and Theoretival Ratios ofGround-Refleated to Wodir Radiation, Shot 4, AD-G.

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C'.

20 Vr e l c e

soE so0 R0e30.c/Od

HoHon1

Difltottostace 13 f 1 09

20

P A VIE -~t

" 110 A d .

260

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N0030,N0

N CS 0-

View of Directcalorimeter View of Vertical0 1 ~corimeter

50 40 10 t0 10 /10 20Horiz. Distance , 103 f t/

3 / Vert. Ref lected 0.91000, ~ Direct 8.9

-L Vert. Reflected 0.1to0 Direct

.00, - Hori . Reflected 0.0.0Direct 0.6

PLAN VIEW

20

- Airplane Position

t Direct Calorimeter verticalSIDE VIEW W, alrimeter

so 40 0 20 10 to goHoriz. Distance, 103 f t

Figure 4.3 Airplane Poeition and Theoretical Ratios ofOround-Reflacted to Direct Radiation, lot 6, AD-B.

27

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0

Vie 2 WO f VerticOl

.00, Calorimeter

/ View of Oirect . gcalorimeter -

140 30 20 101 2

Horiz. Distance, 103 ft 1/ 2

PLANVIEWVert. Reflected -1.330

DirectHori., Ref22lece 0.779

20- Airplane Position

1\, 755' Altitude

.1 ~ qverticalSIDE VIEW 7. 10 q, Clrmte

- tDirect Calorimeter

40 30 g0 10 10 goHoriz. Distance, 103 f t

Figure 4.4 Airplan PoSition and Theoretiosi Ratios ofGround-Reflected to Direct Radiation, hot 6, AD-6.

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m30-

20

Vier~ ofDiec View of Vertical-- o CalorimeterCalorimetero -

a)

.Mort. eflecte1 i I I I I I I a50 40 30 20 10 10, 20/ 30

Horiz. Distance, 103 ft " ///

0,20 Direct 0.790

//- 0 .00. Vert. Reflected

.01 Direct

00 PLAN VIEW oriz. Reflected ,0.69Direct

S200)Airplane Position2 12,190' Altitude

.Vo ical" P vertical

t o Calorimeter

SIDE VIEW Direct CaorimeterGza • 00ftt

p I I I I I I I I Iso 40 10 to 10 0 20 50

Horiz. Distance, 103 ft

Figure 4.5 Ai'plw Position and Theoretioal Ratios ofGrovd-befloted to Direot RadiaUon, iowt 6, AD-5.

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NC0 -

0 %% View of Vertical

View of DirectCaoierCalorimeter

50 40 so t0 10 10 1 3t 30Horiz. Distance ,103 ft/

10 /

Vert.BhIIISLt. 569Direct

20

Vert. Reflected 3.4-Direct z.4

PLAN ViEW000 -0 30- oriz. Ref lected '0.699

Direct

20- Airplane Position0 11,690' Altitude

-0

SIDE VIEW If $ 4 > verticalDirect C/retrCOle rivter

eZ* goof tN,.;j 150 4 30 to5 0 t 0

Moriz. Distance , 103 ft

Figure 4.6 Airplane Position awl Theoretical Rtios ofGround-Refleoted to Dirct Radiation, Mot 8, AD-431.

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S30

020 View of Vertical

20 Calorimeter

View of Direct 0Calorimeter

0

-j

s0 40 30 20 1010go 3Horiz. Distance, 103 ft

t0 Vert. Rflected0

.. Olt3tisid = 20.961PLAN VIEW ,3 Direct

.kI2ert. Refleut, 0 . 21Direct

.~ 20Airplane Position

S\ ,690 Altitude

7----------

-"" et R ef /ce/ o

SIDE VIEW 10 - Dir et et Direct CH/er/meter ",

oz e Soo"tI I I I I aI I i I ,I

50 40 30 20 10 I0 20 10Horiz. Distance, 103 ft

Figure 4.7 Airplane Position man Theorltal Rtio ofGround-Refieoted to Direot Padition, bot 8, AD.

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0

C 20-

" View of Verticalis -. Calorimeter

Vie w of Direct t0 \Calorimeter

so 40 30 20 lo102Horiz. Distance, 103 ft

Direct

PLAN VIEW Vert. Reflected :1.174Direct

MorizLARflected z0.873

20-Airplane Positiono0 12,425' Altitude

0f - verticalSIDE VIEW . 4Colorimeler

(DOirectelorlmeel.

6Z dv 400ft

so 40 30 20 10 10 g0Horiz. Distance, 103 ft

Figure 4.6 Airplane Position and Theoretical Ratios ofGround-Reflected to Direct Radiation, S1hot 12, AD46.

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0

0

- - 5.Viw Of Vert.000inete

/ View of Direct

GZ-\

01 0s 40 30 20 10 10Horiz. Distance, 103 ft/

10/

- ' - o Direct

V tert. Ref lected l.. .3.7,PLAN VIEW Direct

Hon:z. Reflected 8.6Direct .. 6

t0

~-Airplane Positionio NJ 1,925' Altitude

SIDE~t VE 'EverticelSIDEVIEWCalorimeter

SDirect CalerimeterOz Is A- -t

eo 30 40 30 t0 10 10 toHoriz. Distance , 103 f t

Figure 4.9 Airplane Position &Wd 7beoretical Ratios ofGroi-Reflooted to Direct Radiation, Obot 12, AD-5.

33

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40-

N 30-0

0-

AA View of VerticalView of Direct calorimeter

Calorimeter

-j

40 30 20 10 0230 4Horiz. Distance, 103 ft

10-

/ Vrt. ReflectedD

20-

PLAN VIEW X Vert. Reflected 20.551Direct

0, o Horli. Refled, .0664-00 Direct

020Airplane Position

--f .... 12S25' Altitude

SIDE VIEW 10 Voricel

afDiect Calorimeter

OZ e 400t40 10 20 10 10 20 30 40

Horiz. Distance, 103 ft

F7gure 4.10 Airplane Position sad Theoretical Rhtios of

Ground-Meflooted to Direct Radiation, Mot 12, AD-Ul.

SECRET

~30-

\0 20-4-

View of DirectCalorimeter

.2 \0 view Of vertical0 calorimeter

so 40 30 20 10 1i3

Horiz. Distance , 103 ft

/ Hongr. Reflected 30.727r

PLAN VIEW Direct 0.2

0

SIDE VIEW a 0: Airplane Position**% 5705' Altitude

Direct calorimeter VrticolGZ ~Colorimfeter

GO 40 30 go 10 10 go toHoriz. Distance, 103 ft

Figure 4.11 Airplane Position and Theoretical Ratios ofGround-Refleced to Direot hdafton. Sot 13, AD-411.

SECRET

N0-N ~0

220-

View of Direct N. iwofVhio

-ooieo Calorimfeter

-

50 40 30 to 10 10 1 0 30Horiz. Distance, 103 ft

/ Vert. Reflected s.7Direct 0.0

4.. Vert. Rflected uO.770

30 Horis. Reflected x 0.908

PLAN VIEW

up' Arpl51 Position11, 765 Altitude

SIDE VIEW o TgVrilt Direct CalorimeterCloier

50 5000f

Horiz. Distance, 103 ft

Figr 4.12 Airplane Position and Theoretical Ratios ofGround-Beflected to Direct Radiation, Rhct 13, AD-S.

SE CRET

4.1.3 Correlation of Data. With the method outlined in 4.1.2 for direct radiation,the values of Ed* corrected for attenuation were determined and compared with the valueof Wth/41R in Figure 4.13. In view of the good overall agreement and the small effectof scattered radiation, it is reasonable to conclude that the analytical approach to deter-mine the contribution of reflected radiation yields values accurate to about *10 percent.By the method outlined in 4.1.2 for indirect radiation, the calculated indirect energ,En d , expected at receivers was determined and compared with the measured Indirectenergy, Erm, values in Figure 4.14. A summary of data used to derive Figures 4.13and 4.14 is presented in the Appendix. If the above conclusion Is correct concerning re-flected radiation, then it follows that in the case where the reflected contribution is small,a good approximation for the scattered radiation is obtained. It should be noted that inReference 9 a similar analysis of thermal data obtained during Operation CASTLE hasgiven good correlation between predicted and measured values.

4.2 RECORDED THERMAL DATA

Figure 4.15 presents a comparison of recorded data with data of Reference 2. Ex-cept for Shot 12, Item Numbers 8 and 9, Table 3.1, where fireball distortion may haveappeared, data agreement is fairly good. Some error in slant range distance may be

TABLE 4.1 PERCENT OF TOTAL DIRECT AND GROUND-REIECTED FILTERED ENEROIES

Percent of Total Em rp11bat4 mot 6 JI 0 ~ 1 01109 13

Filter spectral Rane AD-$ AD-$ AD-5 AD- AD-41Type of AD-421 AD-S AD- [ AD-S AD-5

Tranmiss ion AD-6 AD4() Dir W Dir W Dir mefn Dir PR Dir hi

Q-o 3,200 - 45,000 100 100 100 100 100 100 100 100 100 100

3-69 5.300 -25.000 73 910 84 1000 67 75 SO 78 73 WY78 V7 64 &1 73 1; 67 74 of 1040

69 75 72 70*

-58 6,400 - 2 .000 62 91' 82 9" 1 74 a 47 3i o osas 63 - 8 6 741 7 63 75'

- 70 - __1* _*Horsohislly distant test positions (15 percent atmospheric scattring).

present. MSQ controlled and formation aircraft are estimated to be within 3 300 feetand * 800 feet horizontal distance from fireball, respectively. Figures 4.16 to 4.20 pro-sent normalized irradianoe curves for all test conditions based on recorded radiometertime histories. Purely for Information purposes, these curves from eah shot are oom-pared with a normalized field pulse of Reference 1.

4.3 SPECTRAL ENERGY DISTRIBUTION

Spectral oer measurement for the twelve test positions reported herein showedconsiderable random scatter in reflooted-onergy data. This Is apparent in Table 4.1,where measured ground-reflectad and direct energies uder full speotrum clear Corningquartz filters are assumed " 100 percent. Relative to the 100 percent tranemisivityfor clear quarts, the ground-refloated energies for the same Intensities under broadbead 3-69 and 2-58 Corning filters were 100 to 70 percent and 90 to 38 percent, respea-tively. Similarly, direct energies were 64 to 64 percent and 63 to 47 percent, respec-

37

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Ero

U Measured: Calculoteda+

4 110//

''7/ +

+ 10%0 a Error ~ /

t2t

+4 3 %o, 15%rrro10 Error

a'/ 12

WW

- 6/

Calculated Direct Energy, E d(invocuo): -4, ,cl/

Figure 4.131 Measured versus Calculted Dirct Energy Data.

tUvely. The indicated lare random satter in reflected-energy" values prevent the estab-lisdhment of a iground-refleoted to direct energy spectral distribution rtio. Prviouslydisussed phenomena related to atmospheric sttering and the effects of 90-dogre-field-of-view calorimeter recordings of ground-rfleted energies from finite areas atvarious test stations may suggest a contributing factor to this random satter.

4.4 TEMPERATURE DATA

Figulrs 4.21 and 4.22 present plot of peak bar, white, and blue skin sample tem-peratures from Table &I. Approimately the same linear variation for silded &nd un-sibelded temperatur daft In Figure 4.21 and 4.22, rspectively, exist when lotted ver-sus radiant energies. Surface finishes were undamaged up to maximum temperature•recrdeld. Checking thene dat against Figurae 4.23i shows appro at absorbtivity 0o-effioints for bare, white, and blue painted aluminum skin amples "u 0.19, 0.14, and0.45, rspectively. This corrsponds to 0.40, 0.20, and 0.60 In RefereOnce 6. b a checkon temperature rise times slant range verss total yield (Figlurs 4.24 ad 4.25), a i/nearrelationship also exist for bar, white, and blue paintedl alumihun skin samples, shieldedand ushldd. As In Figre 4.15, and perhaps due to firball ditrtion, Shot 12 pointsdo not lOotde with fird curves.

8

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49I

80SECRE

Chapter 5

CONCLUSIONS AND RECOMMENDATIONS

5.1 CONCLUSIONS

5.1.1 Experimental Check on Analytical Data. The theoretical values for the re-flected radiation are, within 10 percent, comparable to the experimental values.

The contribution of atmospheric scattered radiation cannot be neglected and, in thecase where fine particulate matter (like dust) exists in the vicinity of the explosion, thecontribution of the scattered radiation increases.

5.1.2 Spectral Energy Distribution. Random scatter in grv-und-reflected energymeasurements under broad-band filters (perhaps due to variation in the finite areas sub-tended by 90-degree-field-of-view indirect calorimeters at various test stations and re-lated atmospheric scattering) prevents the establishment of a ground-reflected to directenergy spectral distribution ratio.

5.1.3 Temperature Data. Absorptivity coefficients from recorded data and data ofReference 6 show fair agreement for bare, white, and blue painted aluminum skin samples.Skin samples, exposed to and shielded against the airstreams show insignificant reductionin skin temperatures due to aerodynamic cooling. A maximum temperature rise of 175degrees Fahrenheit was recorded at approximately 175 knots 1AS. No apparent surfacecoating damages were observed.

5.1.4 Operational Success. All recording equipment performed in a satisfactorymanner. Operational procedures and utilization of a thermal hood for pilot's protectionagainst thermal radiation proved very satisfactory.

5.2 RECOMMENDATIONS

5.2.1 Thermal Data. It is recommended that analytical data for predicting ground-reflected thermal energy contributions to direct radiation be considered valid as a basisfor use in the establishment of thermal effects envelopes for nuclear weapons. This re-commendation is based on the assumption that proper allowance is made for ground-reflected and direct atmospheric attenuated and scattered energies.

It is further recommended that an experimental check of analytical data be made forweapons exceeding 43-kiloton total yield to further evaluate ground and atmospheric re-flection, attenuation, and scattering effects. Utilization of 10-degree -field-of-viewcalorimeters and radiometers should be considered in this connection.

5.2.2 Temperature Data. It is recommended that a laboratory study be made of

the effects of surface coating damage on the temperature rise and decay in aircraft skinsamples utilizing field pulse inputs presented in this report in lieu of current rectangu-lar pulse inputs.

50

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Appendix

TABLE A.1 IUMMAXY OF DIRECT iNEBOY DATA COMPUTAT2GMU

UrOT TAB/., 3.1 Zd I E eIWtbNO. ITEM NO. Idd ie ld* 05) ltn au I

4 1 4.19 1 + 0.329 4 0.05 = 1.334 3.14 0.833 3.77 3.03.54 3.65 3.10

2 3.07 1 * 0.527 + 0.u = 1.57? 2.52 0.20 3.04 3.403.01 2.43 3.03

5 3 2.13 1 * 0.423 + 0.05 - 1.473 1.45 0.8? 1.02 2.102.07 1.41 1.5?

4 1.35 1 * 0.57 * 0.0 - 1.62 0.772 0.065 0.090 0.41.12 0.601 0.613

0 5 2.24 1 + 0.40 + 0.05 = 1.54 .46 0.653 1.71 1.771.86 1.50 1.41

6 2.06 1 * 0.47 * 0.05 - 1.52 1.36 0.836 1.63 1.852.13 1.40 1.0

7 1.0? 1 * 0.40 4 0.05 - 1.53 0.70 0.018 0.635 1.111.10 0.72 0.0

i1 6 5.40 1 + 0.644 4 0.05 - 1.502 3.40 0.052 3.34 3.24.00 3.06 3.57

5 6.01 1 * 0.535 + 0.05 - 1.565 3.50 0.56 4.3 3.405.00 3.20 3.6

10 1.71 1 + 0.445 + 0.05 - 1.495 1.14 0.002 1.42 1.41.91 1.28 1.60

13 11 4.40 1 - 0.303 + 0.05 - 1.352 3.25 0.671 3.72 4.64.16 3.08 2.54

10 3.34 1 * 0.433 + 0.05 - 1.4083 1.07 0.032 2.37 2.66

TABLE A.2 SJ3IMAEV Of OWLD-REWL1CTZD lNERGY DATA COMPUTATIh

IM TABLE 3.1 i A Ear .i.1NO. ITEM NO. d4. Iked Em

4 1 3.14 0 4 00060 + 0.15 0.1580 05 0.332.65 0.42 0.33

2 2 52 0.776 + 0410 * 0.05 - 1.236 3.12 3.152.42 3.00 2.70

6 3 1.45 0 + 00340 4 0 15 - 0.1648 0.27 0.531.41 0.36 0.34

4 0.772 0648 + 0.40 4 005 - 1.308 1.07 0830.631 0.90 1.00

a 5 1.46 0.710 + 0.38 4 005 - 1146 1.68 1.411.20 1.36 1.31

O 1.30 0.694 + 0.21 4 0.05 - 0.954 1.30 1.441.40 1.34 1.31

7 0.70 0.736 4 0.222 - 0.05 - 1.002 0.70 0.760.72 0.72 0.63

12 1 3.40 0.765 + 0,430 + 0.05 - 1.264 4.30 3.35

3.00 3.0 3.729 3.60 0.772 4 0.415 4 0.05 - 1.37 4.70 4.27

3.20 3.94 3.7010 1.14 0 4 0.00751 4 0.15 - 0.1575 0.13 0.28

1.28 0.20 0.3913 11 3.25 0 + 0.0101 4 0.15 - 0.16 0.52 0.46

3.08 0.43 0.5712 1.37 0 4 0.035 4 0.15 - 01735 0.35 0.06

1.63 0.38 0.55

51

SECRET

REFERENCES

1. Basic Characteristics of Thermal Radiation from an Atomic Detonation;AFSWP-503, November 1953; SECRET-RESTRICTED DATA.

2. Thermal Radiation from a Nuclear Detonation; Operation TUMBLER-SNAPPER,Project 8.3, WT-543, March 1953; SECRET-RESTRICTED DATA.

3. Preliminary Report on the Attenuation of Thermal Radiation from an Atomic orThermonuclear Weapon; Air Force Cambridge Research Center, TN-54-25, November1954;

3. Chapman, R. M., and Seavey, M. H.; Preliminary Report on the Attenuation ofThermal Radiation from an Atomic or Thermonuclear Weapon; Air Force CambridgeResearch Center, Cambridge, Massachusetts, TN-54-25, November 1954; SECRET-RESTRICTED DATA.

4. Coulbert, C. D., and O'Brien, P. F.; Atmospheric Transmission of ThermalRadiation from Nuclear Weapons to Aircraft; Wright Air Development Center, Dayton,Ohio, TR 53-212, September 1953; SECRET-RESTRICTED DATA.

5. Reflection of Radiation from an Infinite Plane; Navy Department, Bureau of Aer-onautics, Research Division Report Number DR-1434 (Part I) Revised June 1955; UN-CLASSIFIED.

6. Guide to the Effects of Atomic Weapons on Naval Aircraft; Navy Department,Bureau of Aeronautics, Report NAVAER 00-25-536, July 1954; SECRET-RESTRICTEDDATA.

7. Atomic Weapon Effects on AD Type Aircraft in Flight; Armed Forces SeolalWeapons Project, Operation UPSHOT-KNOTHOLE, Project 5.1, Report WT-748, March-June 1953; UNCLASSIFIED.

8. Instrumentation for Thermal Radiation Survey; Naval Air Materiel Center,Philadelphia, Pennsylvania, Report Number NAMC ASL 1006, to be Issued; CONFIDEN-TIAL.

9. Zirkind, R.; Analysis of Thermal Radis'ton Emitted by a Nuclear Detonation;NAVAER Report Number DR-1740, to be published; SECRET-RESTRICTED DATA.

52

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ABM ACTIVITIES 44 Commanding Officer, Yrankford Arsenal, Philadelphia37, Pa. ATTN: Col. Teves Kundal

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2 Chief of Reaearch and Development, fl/A, Washington 25, lgical laboratory, Army' Chemical Center, Md. ATTN:D.C. ATT: Atomic Division Tech. Library

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54

S ECRETAMC 70910WI 16IU 0veUNMRESTRICTED DATA