This monthly report details Physics Department 100 Area technical activities for the month of April 1947.

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From Introduction: "In the present report, the results for the wings and bodies of revolution alone are first analyzed in comparison with exiting theory."

From Introduction: "This paper presents the results of the investigation of the wing-alone and wing-fuselage configurations employing a wing with the quarter-chord line swept back 45^o, aspect ratio 4, taper ratio 0.3, and an NACA 65A006 airfoil section parallel to the stream."

"Performance characteristics of the turbine in the 19B-8 jet propulsion engine were determined from an investigation of the complete engine in the Cleveland altitude wind tunnel. The investigation covered a range of simulated altitudes from 5000 to 30,000 feet and flight Mach numbers from 0.05 to 0.46 for various tail-cone positions over the entire operable range of engine speeds. The characteristics of the turbine are presented as functions of the total-pressure ratio across the turbine and the turbine speed and the gas flow corrected to NACA standard atmospheric conditions at sea level" (p. 1).

From Summary: "An analysis of available theory on seaplane impact and a proposed modification thereto are presented. In previous methods the overall momentum of the float and virtual mass has been assumed to remain constant during the impact but the present analysis shows that this assumption is rigorously correct only when the resultant velocity of the float is normal to the keel."

Abstract. Methods of analysis for thorium, calcium, and nitric acid in solutions from thorium extraction purification columns are described and the results and errors are outlined. A brief description of methods of analysis that were not successful is included.

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The following document describes some studies of the radioactive isotopes of cerium and lanthanum lying on the light or neutron-deficient side of stability.

From introduction: "The fact that tetravalent uranium either in the form of solutions of its salts or, in some cases, in the dry state is readily oxidized by gaseous oxygen, has been observed by various investigators. A quantitative study of this reaction appeared to be desirable as a means of learning more about the nature of the ionic species present in uranous solutions. It was also of potential value in determining the importance of autoxidation as an undesirable side reaction involved in the handling of uranous solutions, and, if necessary, in developing procedures for minimizing the reaction."

Technical report abstract. The present state of knowledge concerning the effect of pile radiation on a variety of solid materials is reviewed. Radiation corrosion will not be a serious hazard for aluminum or stainless steel but it can be for iron or lead if either are exposed to water. Apart from corrosion the principal uncertainty is in regard to the Wigner effect on the behavior of metals. There is at present no ground for optimism regarding the behavior of tuballoy. The effect on aluminum or a bonding material while less severe must also be considered serious. The expectation in regard to graphite is that its behavior will not cause trouble during the first 100 days of operation although serious troubles will probably arise within two years of operation. Organic materials can be used safely only in regions of limited exposure.

Report presenting calculations to determine the effect of several operating conditions on the performance of condensers for steam-turbine power plants. The analysis covered a range of turbine-inlet pressures and turbine-outlet pressures for various condenser cooling-air pressure drops, flight speeds, and altitudes. Results regarding steam-cycle performance, effect of turbine-outlet pressure on condenser performance, effect of cooling-air pressure drop on condenser performance, effect of turbine-inlet temperature on condenser performance, and power-plant-weight estimates are provided.

From introductory paragraph: "The study of the counting techniques of gamma-emitting radioisotopes is of a great deal of interest to workers in the field of radiochemistry. Of particular interest to the long-lived gamma emitting isotope of yttrium which is commonly prepared by a deuteron bombardment of strontium and is reported to decay by K-capture. This isotope, which is of interest in the fields of biochemistry and metallurgy was tentatively assigned to mass 86. Since a 2.0 hour activity was observed from a neutron irradiation of yttrium, the assignment was considered fixed. Subsequent work indicated a possibility of a long-lived gamma emitting activity arising in the fast neutron irradiation of yttrium. The published data did not agree with theoretical calculations as to the possibility of these two activities being isomers. This work was undertaken to study the characteristics of the radiations from the isotopes; to have data available on the long-lived activity; and, to attempt to fix the mass assignment."

An analysis of rim cooling, which cools the blade by condition alone, was conducted. Gas temperatures ranged from 1300 degrees to 1900 degrees F and rim temperatures from 0 degrees to 1000 degrees F below gas temperatures. Results show that gas temperature increases up to 200 degrees F are permissible provided that the blades are cooled by 400 degrees to 500 degrees F below the gas temperature. Relatively small amounts of blade cooling, at constant gas temperature, give large increases in blade life. Dependence of rim cooling on heat-transfer coefficient, blade dimensions, and thermal conductivity is determined by a single parameter.

Report presenting an analytical investigation to determine primarily the reduction in cooling-air requirement and the increase in effective gas temperature for the same quantity of cooling air resulting from the use of an insert in the cooling-air passage of a hollow air-cooled turbine blade.

From introduction: This report is concerned primarily with the coprecipitation phenomenon and its application to plant problems.

"As part of a program to study the correlation between molecular structure and physical properties of high-density hydrocarbons, the net heats of combustion, melting points, boiling points, densities, and kinematic viscosities of some hydrocarbons in the 2-n-alkylbiphenyl, 1,1-diphenylalkane, diphenylalkane, 1,1-dicyclohexylalkane, and dicyclohexylalkane series are presented" (p. 55).

Clipping of a newsletter discussing county libraries in Texas.

Empirical design curves are presented for the critical stress of thin-wall cylinders loaded in axial compression. These curves are plotted in terms of the nondimensional parameters of small-deflection theory and are compared with theoretical curves derived for the buckling of cylinders with simply supported and clamped edges. An empirical equation is given for the buckling of cylinders having a length-radius ratio greater than about 0.75.

The following report provides the analysis of a large number of unreported data--taken during a study described in report HW-15230--containing density values obtained for solutions of uranium and nitric acid in tributyl phosphate-carbon tetrachloride solutions.

"A solution is presented for the coupled modes and frequencies of swept wings mounted on a fuselage. The energy method is used in conjunction with power series to obtain the characteristic equations for both symmetrical and asymmetrical vibration. A numerical example which is susceptible to exact solution is presented, and the results for the exact solution and the solution presented in this paper show excellent agreement" (p. 1).

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"Tests of a 1/20-scale dynamically similar model of the Northrop B-35 airplane were made to study its ditching characteristics. The model was ditched in calm water at the Langley tank no. 2 monorail. Various landing attitudes, speeds,and conditions of damage were simulated during the investigation. The ditching characteristics were determined by visual observation and from motion-picture records and time-history acceleration records" (p. 1).

Report presenting the results of flight testing to determine the zero-lift drag of an NACA 65-009 airfoil at a specified aspect ratio. The results are compared to previous testing of unswept and swept-back arrangements. The swept-forward and swept-back airfoils were found to produce lower values of zero-drag lift than the unswept airfoil.