' . i ORMERLY RESTRICTED DA TA on Sls HANDLESECTION AS RESTRICTED DATA INENERGy FOREIGNNCREMINATION 1448, ATOMIC This material contains infermacon affecting the national defense of the Usted States w.thin the CHAPTER 1 tyes é Aes ; | : INTRO DU CT l ON 1.1 ve ; fo oo -‘ Le. : ” . “ot f ' : i i i i : , meaning of the ecr'cnz re ‘aws, Title 18, U.S.A, . Secs. 793 ad 724, tha tro-3m.s3.on or revelation Of which in any ranner to an unauthorized Person Is prohibited by jaw. OBJECTIVES Since measurementsof blast overpressures at and near the surface of the ground are subject to various boundary-layer effects that are difficult to predict theoretically, it was considered desirable to supplement the surface-pressure measurements in Operation Ivy with measurements made at altitudes far above the range of infruence of boundary-layer irregularities. Previous tests, Operation Tumbler-Snapper in particular, were considered to have confirmed current methods of taking into account the effect of the varying ambient conditions of the atmosphere with altitude; therefore it was thought that overpressure measuremc ts at high altitudes, when suitably corrected for such effects, would provide a significant test of the extension to extremely large detonations of the scaling law relating peak overpressure to bomb yield. Another objective was the measurementof the intensity of thermal radiation received over a wide range of altitudes 2nd distances. Whereas the instrumentation and operating procedures for the measurementof blast overpressures by means of parachute-borne telemetering gauges had been brought to a state of comparatively high reliability in previous tests, the thermalmeasurement phase was added at a late date and must be regarded primarily as a test of in~ strumentation rather than as a definitive test of thermal scaling at very high yields. 1.2 HISTORICAL The military requirements for an experimentaltest of the Fuchs theory of the effect of : , varying ambient atmospheric conditions on peak blast overpressure were brought to the attention of the Terrestrial Sciences Laboratory early in 1950. At thit time a proposal was prepared for participation in Operation Greenhouse. However, there was insufficient tiie for the preparation of such an extensive project, and no action was taken. , / Lo 7 In December 1950 the proposal was reinstated under Operation Windstorm, and in February 1951 the project was officially included. After Operation Windstorm was cancelled, the project was tentatively included in Operation Buster, but, because cf conflicting radio-frequency requirements, the project was diverted to Operation Jangle. Corclusions from the results of this operation were considered tentative since the actual positions attained by the air-borne instrumentation differed greatly from the intended positions and did not ; rovide a clear-cut test of the Fuchs altitude correction. There was justification, however, for concluding that the data obtained supported the Fuchs theory within the probable accuracy of the observations out to overpressures of about 0.1 psi. Project plans were included in Operation Tumbler-Snapper. The operation consisted in the measurementof peak blast overpressures by deploying 16 parachute-borne canisters from 9 resemrcrescocers QRRBBEIR- SECURITY INFORMATION EEE AP AERe Pt ee eS AMRMELL nth 8 I Ahn weEaNLA SBaEARYNileRLTREAGIOSFIN t fe] ot f alee ee Loe Ra ny Mane delat eee te Coob CncteRMRRRNA RAL SN ALS Oe tantARN Ae Aten oe ee ee ee 4 :