Report presenting flutter of propellers at high angles of attack and flutter data obtained in connection with tests of models of large wind-tunnel propellers. The stall flutter speed was found to be much lower than the calculated classical flutter speed. That flutter speed is only obtainable if the propeller operates at the ideal angle of zero twist.

"Design charts are developed for 24S-T aluminum-alloy flat compression panels with longitudinal z-section stiffeners. These charts make possible the design of the lightest panels of this type for a wide range of design requirements. Examples of the use of the charts are given and it is pointed out on the basis of these examples that, over a wide range of design conditions, the maintenance of buckle-free surfaces does not conflict with the achievement of high structural efficiency" (p. 553).

These studies were aimed at elucidating affects of radiation in inducing hemolysis independent of inhibition of erythropoiesis. Research studies were conducted both on human patients and dogs. Phosphorus-32 in mc amounts were administered either intravenously or orally to patients suffering Polycythemia rubra vera. Dogs were treated with either P-32 or x-radiation. Hemoglobin metabolism was monitored in all test subjects by hematology, blood chemistry, and fecal excretion of hemoglobin catabolites.

Report discussing testing to determine the longitudinal stability and control and stalling characteristics of a DeHavilland Mosquito F-8. Special focus is given to the control forces, elevator control, trim changes, and stick fixed and stick free characteristics of the aircraft.

"The purpose of this report is to provide designers of airplanes with information that will be helpful in obtaining good ditching characteristics in new designs. The results from a number of model tests and report of actual ditchings are used as a basis for which to draw conclusions as to the effect on ditching performance of general arrangement, interior arrangement, fuselage shape, and other design parameters. The characteristics of several types of ditching aids that could be incorporated in a design are also discussed" (p. 1).

"Increments in structural loads due to atmospheric turbulence can be accurately expressed in terms of flight speed and effective gust velocities (reference 4). Data from which the effective gust velocities could be computed were also obtained during the flights of the XC-35 airplane. These data have been used to determine the significance of the fluctuations in the pilot's indicated-airspeed readings in relation to structural loads to due to atmospheric turbulence" (p. 3).

Report discussing flight tests on a low-drag wing pursuit airplane to determine the effects of Mach and Reynolds numbers on the maximum lift coefficient obtainable in gradual and abrupt stalls. The obtainable maximum lift coefficient was found to be greatly affected by the Mach and Reynolds numbers in gradual stall. In abrupt stalls, the maximum lift coefficient was affected by the Mach number, but not the Reynolds number.

Report discusses the results of bending tests on an open box beam designed to fail on the highly cambered tension side. Results in the elastic range and ultimate-strength test are provided. The stringer stresses near the root were in fair agreement with stresses calculated by shear-lag theory and the ultimate tensile strength developed by the beam was only a little higher than the tensile yield stress of the material.

Report presents tables and charts for the evaluation of profile drag from wake surveys at high supersonic speeds. Two methods of evaluation are presented: an exact method that can be used on a wake of any shape and a simple approximate method that can be used when the variation of total-pressure loss across the wave has a typical form.

"Tests were made of a model representative of a single-engine tractor-type airplane for the purpose of determining the stability and control effects of a propeller used as an aerodynamic brake. The tests were made with single-and dual-rotation propellers to show the effect of type of propeller rotation, and with positive thrust to provide basic data with which to compare the effects of negative thrust. Four configurations of the model were used to give the effects of tilting the propeller thrust axis down 5 deg., raising the horizontal tail, and combining both tilt and raised tail" (p. 1).

Report presenting an analysis of cylinder-to-cylinder temperature and mixture distributions of four different aircraft engines to determine the possible economy of automatically supply water or additional fuel to only those cylinders having excessive temperatures. The cooling problem as distinguished from the fuel-knock problem was studied and an analysis limited to those cases in which additional cooling is ordinarily obtained by carburetor enrichment was made.

Report discusses the results of testing conducted to determine the performance of automatic, internal-coolant valves actuated by cylinder temperatures.The performance of the valves with respect to temperature sensitivity, rapidity of response, and hunting characteristics is described. The relative effects on cylinder performance obtained by internally supplying water and additional fuel were also examined.

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Uranium was successfully cast at temperatures as high as 1900 to 2000 deg C in crucibles made from CeS, CeS/sub 1.38/, ThS, ThS/sub 1.75/, and ThU/sub 0.7/S/sub 2/ with the sulfur pickup in all cases less than 0.15 wt.%, in some cases at low temperatures being less than 0.005%. A summary of actual sulfur absorption for different experimental temperatures and crucible types is given. The effect of the molten mixture of U and UBr/sub 3/(Br/U =2) upon some sulfide refractories was investigated. The results indicate that only ThS/sub 2/ and divalent sulfides like ThUS/sub 2/, US, ThS, etc., would withstand the U--UBr/sub 3/ mixture. Uranium may be separated from metal salt mixtures (CaCl/sub 2/, SrBr/ sub 2/, BaI/sub 2/, etc.) by distillation of the salt and fusion of the U in a sulfide crucible. (auth)

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Abstract: Procedures are presented in detail of two methods for the determination of very small percentages of uranium (down to 0.002%). The methods are applicable to a wide variety of materials. Notes on the methods and confirmatory experiments are also given.

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A memorandum prepared by the Technical Department discussing the technical considerations involved in raising Pile power above the present level of 280 M.W. was discussed. A meeting attended by W. O. Simon, B. H. Mackey, L. Squires, H. Worthington, C. N. Gross, W. E. Jordan and M. H. Smith. The details of this memorandum were reviewed and the plan proposed for operation of the piles subsequent to August 1, 1945 is discussed in this report.

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This memo discusses the effects of advancing to higher power levels of the 105 Piles (D-Pile). It is concluded that there is no technical reason against a cautious advance to higher powers; the units can be run at higher levels than their rating of 250 MW, or the additional reactivity that they will gain with time may be taken entirely in the form of lower peak temperatures and radiation levels. The decision as to what course to follow between these extremes involves such issues as the best use of uranium and the most effective separation of adequate amounts of product of proper quality.

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