This report contains the calculation of the number and spacing of poison columns required to hold a 105 pile in the following cases: (1) complete failure of horizontal rods, (2) complete failure of all rods. Using 10% Cd 90% Pb poison columns of 1.44 inch diameter, it is found that 17 poison columns are required to hold the pile in case of complete failure of horizontal rods, and 65 poison columns are required to hold the pile in case of complete failure of all rods.

The gas thermometer in the F Pile has been overhauled and re-calibrated. The readings are still in agreement with the readings from the graphite thermocouples. A similar overhaul of the gas thermometer in the D Pile will be made during June. The progress of further outward bowing of Tube 2496-D can not be followed satisfactorily even though readings are obtained from both inlet and outlet ends of the tube. Preliminary results obtained from the one-tube mock-up suggest the possibility that the graphite adjacent to the gun barrels in the upper part of the D Pile may fracture after an additional expansion of about 50%, and that this fracturing may distort the tube locally so that 1.44-inch diameter pieces can not be passed through the tube. There is definite indication that continued expansion of the graphite in the D Pile is causing an increase in both the frequency and severity of gun-barrel binding. The committee endorses the proposal that tubes in the top corners of the F Pile which have yet to be discharged for the first time should be left empty rather than re-loaded. This move would be in the direction of reducing the size of the pile in anticipation …

This report gives weekly progress in pile technology. An exposure of over 96 hours was made with the slug radiographing apparatus from May 22 to May 26. The three pieces subjected to the exposure included one of the special pieces designed for installation of a thermocouple. The thermocouple well in the special pieces showed up satisfactorily and for the first time it was possible to detect spots which could be due to small voids. Crushing and breaking strength measurements made on graphite pieces after an exposure of 1,465 MD/AT in a test hole show no significant changes in these properties as compared with pieces having an exposure of 1,215 MD/AT. Thermal and electrical conductivity measurements have been made on unexposed samples of coke base and lampblack base graphite recently supplied by National Carbon Co. A calculation has been made of the contribution of Sm{sup 149} to the graphite temperature coefficient of reactivity. Corrosion tube 2480-P was discharged. The tube contained 2 unblistered, 24 slightly blistered, 9 moderately blistered, and no extensively blistered pieces. The rear Van Stone flanges of twenty-nine tubes distributed in the B Pile were inspected. Qualitative results showed conclusively that the worst attack occurs in the fringe …

In order to further understand the nature of changes which occur in the fingers of persons occupationally exposed to radiation a series of experiments were performed on human subjects generally using x-rays at 130 KV potential, 20 ma and at a distance of 10 cm. Doses ranged from 200-600 r. Fourteen subjects were patients being treated by x-rays or radium for other purposes. The other subject was a staff member who occasionally prepared radium plaques containing 130 mgm of radium. Counts were made of the number of vessels in the terminal row of a measured area of the nail fold. In no case was there any detectable change in the nail fold area within 15 minutes of treatment. Observations were continued for up to 56 days and changes observed included hyperemia, pigmentation, erythemia, and some transitory changes in vascular structure of the affected area. A recommendation for continued studies is made.

A group of radiologists were studied for evidences of radiation damage to the skin of their hands. The technics used were the same as those used for routine hand studies of Argonne National Laboratory personnel and consist of examination of wax impressions of the finger ridges and examination of photographs of the vessels and Papillae in the nail fold. Of the 323 radiologists examined by the first method 48% were found to have ridge abnormalities. The incidence of abnormality increased with years of exposure to radiation up to 100% after 35 years. The irregular use of lead gloves does not give adequate protection against damage of the ridges by radiations. Photographs of the nail fold of 152 radiologists were studied and compared to similar photographs of 101 laboratory workers and of 41 persons over 63 years of age. Some of the abnormalities occurred in all 3 groups. All of the changes which were found among the radiologists were found also in the aged. The incidence of abnormality among the radiologists increased with years of exposure to radiation and exceeded the incidence of abnormality in the aged. No radiologist had normal findings after 30 years of exposure. It is concluded that …

A major problem encountered in the Manhattan Project was the protection of workers against damage resulting from acute or chronic exposure to external radiation. The problem of how to detect evidence of damage following exposure to total body radiation led to this study. These studies were conducted between January, 1942 and November, 1945. Three groups of persons were employed in this study. The first group of eight individuals harboring incurable neoplasms which was not extensive enough to influence general health, these patients were treated with 400 KV x-radiation while sitting in a wooden chair, doses were 27, 60, and 120r. Three persons having generalized illnesses chronic in nature were given total body radiation using 200 KV X-rays in multiple exposures totaling 100, 300, and 500r. A third group of normal volunteers from personnel of the Metallurgical Laboratory were treated with 200 KV x-rays in three divided doses totaling 21 r. Changes in peripheral blood in the fourteen individuals is reported. In group 1 the most persistent abnormality noted was a diminution in the number of lymphocytes after completion of the treatment. In group 2 a depression in the lymphocytes was also the most marked single change. In group 3 no …

Note presenting an investigation of the effect of varying the design of supersonic biplanes to determine the configuration required for optimum aerodynamic performance. The investigation was mainly concerned with biplanes with lower and upper airfoils of equal chord length and of triangular cross section.

"A detailed table of the standard equilibrium velocity and standard equilibrium time is presented for bodies falling in the standard atmosphere. This table gives the velocity at various altitudes and the time of fall from sea level to -4000 feet and from 80,000 feet to sea level. In addition to this standard table, there are given short tables and charts of an open-parachute descent and free-falls; the terminal velocity at sea level, and the variation of the weight-to-drag ratio (2w/cds)1/2 for various weight jumpers from 90 to 30 feet in open-parachute descent; and estimations of drag coefficients of silk and nylon parachutes" (p. 1).

Report presenting a wind-tunnel investigation to determine the effect of length-beam ratio on the aerodynamic characteristics of a family of flying-boat hulls in the presence of a wing. The hulls were designed to have approximately the same hydrodynamic performance with respect to spray and resistance characteristics. Results regarding the two-dimensional and three-dimensional mounting setups, drag reduction, and aerodynamic refinement effects are provided.

Report presenting an investigation in the free-spinning tunnel to determine the effect of horizontal-tail position on rudder hinge moments in simulated spinning conditions. Hinge-moment measurements were made on an unbalanced rudder on a rectangular vertical tail at six positions on the horizontal tail. Results regarding rudder hinge moments, tuft tests, and application of the hinge-moment data are provided.

Note presenting a theoretical solution for the critical stress of thin-walled cylinders loaded in torsion. The results are presented in terms of simple formulas and curves which are applicable to a wide range of cylinder dimensions. The theoretical results are found to be in fairly good agreement with experimental results.

"A theoretical solution is presented for the buckling stress of long plates with transverse curvature loaded in shear. The results are given in the form of curves and formulas for plates with simply supported or clamped edges for a wide range of plate dimensions. Comparisons are made with theoretical solutions obtained in previous investigations" (p. 1).

"A theoretical solution is presented for the determination of the combinations of direct axial stress and torsion which cause thin-walled cylinders with either simply supported or clamped edges to buckle. This theoretical solution is used in conjunction with available test data to develop empirical curves and formulas for use in design. Comparisons are made with theoretical and empirical solutions obtained in other investigations" (p. 1).

Note presenting a theoretical solution for the buckling stresses of long plates with transverse curvature loaded in shear and longitudinal direct stress. The theoretical critical-stress combinations for plates with either simply supported or clamped edges are given in figures and tables and a comparison is made with previous theoretical solutions. Results regarding the theoretical results, empirical results and design curves, and some interaction formulas are provided.

Report presenting an investigation to develop theoretical methods of treating the motions of hydrofoil systems and to determine some important parameters. Variations in the parameters include three distributions of area between the hydrofoils, two rates of change of downwash angle with angle of attack, three depths of immersion, two dihedral angles, two rates of change of lift with immersion, three longitudinal hydrofoil spacings, two radii of gyration in pitching, and various horizontal and vertical locations of the center of gravity.

Report presenting a method for estimating the control forces of spring-tab ailerons from nonlinear wind-tunnel data. Two principal arrangements of the ailerons and spring unit were used, one with the ailerons interconnected and a central spring unit and an arrangement with no interconnection between the ailerons with individual preloaded spring units for each aileron.

Report presenting a method for calculating the local buckling strength of lipped Z-columns with a small lip width. Some experimental data are presented to show agreement between theoretical and experimental results.

Report presenting a method for the calculation of the buckling stress of a multiweb wing in bending as well as design charts based on this method for the minimum-weight design of 24S-T aluminum alloy sheets, extruded 75S-T aluminum alloy, and extruded 0-1HTA magnesium alloy. An example of the use of the charts is also provided.

Report presenting a review of literature to determine the frequency of sound of a given source strength that is loudest at various distances from the source. Frequencies in the range from 500 to 1000 cycles per second were found to be the easiest to hear, even at a distance of several miles. Sound data obtained from a light trainer airplane showed good agreement with predictions.

Note presenting an investigation to determine the reduction in drag that could be obtained for a conventional-type flying-boat hull by means of aerodynamic refinements. For comparisons, tests were made on a streamline body simulating the fuselage of a modern transport airplane.

Report presenting flutter tests of two wind-tunnel-fan models, one with conventional Clark Y airfoil sections and one with high-camber blade sections. The results indicated that higher flutter speeds were present for high lift coefficients for high-camber blades. Results regarding lift coefficients, blade-tip twisting, power loading, critical Mach numbers, flutter point, vibrational frequencies, and stall-flutter tip Mach number are provided.

Note presenting a description of the improvements in the design of equipment associated with the hot-wire anemometer for the measurement of fluctuating-air flow quantities. An improved technique and an electronic circuit for the frequency compensation of a hot wire are presented.

Report presenting testing to determine the effects of wing-tip fuel tanks on the rolling characteristics of unswept wings. The investigation included determination of the damping in roll, aileron effectiveness, and lateral maneuverability of a tapered and of a rectangular wing. Results regarding the effect of wing-tip fuel tanks on the damping-moment coefficient in roll and origin of the effect of wing-tip fuel tanks are also provided.

Note presenting tests of three types of boundary-layer-control suction slots in a two-dimensional diffuser to investigate design criterions and to evaluate the practical minimum total-pressure losses. Testing occurred at a velocity of about 100 feet per second with a boundary layer with a displacement thickness of 0.85 inch and a shape parameter of about 1.8.