Report presenting initial flight tests of two simplified flutter vehicles. Test results were in agreement with the results of the freely-falling-body test in that the wing failures in the transonic range occurred at velocities greater than the flutter velocity calculated from the two-dimensional theory.

"The NACA is investigating a series of J-33 turbojet-engine compressors to determine the over-all and component performances and to improve theories of flow through large centrifugal compressors, The production model J-33-A-21 was operated over a range of inlet temperatures from 80 to -40 F and inlet pressures from 14 to 5 inches mercury absolute for equivalent impeller speeds from 6000 to 13,400 rpm. At the equivalent design speed of 11,500 rpm, the compressor had a peak pressure ratio of 3.98 at an equivalent weight flow of 73.4 pounds per second and an adiabatic temperature-rise , efficiency of 0.701" (p. 1).

"About 500 additional references pertaining to hydrodynamic design of seaplanes have been compiled, and the information is presented in the form of abstracts classified under six main headings:GENERAL INFORMATION, HYDROSTATICS, HYDRODYNAMICS, AERODYNAMICS, OPERATION, and RESEARCH. The compilation is an extension of NACA RM No. L6I13, entitled "Abstracts Pertaining to Seaplanes," by Jerold M. Bidwell and Douglas A. King. An author index and a subject index are included" (p. 1).

"Theoretical and experimental investigations were made of the distribution of strains in a plywood sheet-stringer combination used as the chord member of a box beam acted upon by bending loads. The theoretical solution was obtained with the help of the principle of minimum potential energy and certain simplifying assumptions. Strain measurements were made on a build-up box beam by means of electrical-resistance strain gages connected with strain indicators" (p. 1).

The following report describes the use of two experimental facilities used to evaluate the Schenectady Pile. The facilities are divided into nuclear physics and chemistry experiments, and testing of pile components and materials under pile conditions. This document discusses the experiments taken place in these facilities to evaluate the pile.

A solution is presented for the problem of the buckling of a column on equally spaced deflectional and rotational springs. Useful charts, which relate deflectional spring stiffness, rotational spring stiffness, and buckling load, are given for columns having two, three, four, and infinite number of spans.

From Summary: "A thermodynamic relation is derived and simplified for use as a temperature-limiting control equation involving measurement of gas temperature before combustion and gas pressures before and after combustion. For critical flow in the turbine nozzles of gas-turbine engines, the control equation is further simplified to require only measurements upstream of the burner. Hypothetical control systems are discussed to illustrate application of the control equations."

Note presenting an application of the method of superposition of linearized conical flows to the calculatin of the aerodynamic properties of thin, flat, swept-back wings at an angle of attack. Various cases are distinguished, depending on the sweep of the leading and trailing edges relative to their respective Mach lines. The results of the calculations emphasize the indications of the theory that the determining factor in the aerodynamic performance of wings is the disposition of area relative to the Mach lines.

Report presenting an evaluation to approximate engine-jacket conditions in a laboratory setting in order to determine their cooling properties using water and methanol. Results regarding the heat balance, tube-wall temperature distribution, nonboiling data, local boiling without air, entrained air without local boiling, entrained air with local boiling, and application to engine cooling are provided.

"An extended analysis was made of the previously reported performance investigation of the original compressor from the XJ-41-V turbojet engine and a similar compressor revised a to obtain a 33-percent increase in the geometric passage area at the vaned-collector entrance. This analysis was based on the concept of the vaned-collector entrance as the throat section of a nozzle. Because of nonuniform air distribution at the vaned-collector entrance, approximately 90 percent of the available flow area was utilized in the original compressor and 94 percent in the revised compressor" (p. 1).

A theoretical analysis is presented for obtaining, by use of Theodorsen's propeller theory, the load distribution along a propeller radius to give the optimum propeller efficiency for any design condition. The efficiencies realized by designing for the optimum load distribution are given in graphs, and the optimum efficiency for any design condition may be read directly from the graph without any laborious calculations. Examples are included to illustrate the method of obtaining the optimum load distributions for both single-rotating and dual-rotating propellers.

Report presenting an investigation to obtain the pressure distribution over a sharp-nose body of revolution with a circular-arc profile and fineness ratio 6 at transonic speeds using the NACA wing-flow method. Results regarding the variation of pressure coefficient with Mach number, pressure distributions along the body axis, pressure drag, and effects of interference and horizontal gradient are provided.

Report issued by the Bureau of Mines on the Coso mercury deposits of Inyo County, and development of the bucket drill for obtaining samples. Descriptions of the physical features of the deposits are listed. This report includes tables, maps, photographs, and illustrations.

"The ditching characteristics of the Army B-36 airplane were determined by testing 1/20- and 1/30-scale dynamic models in calm water in Langley tank no. 2 and at the outdoor catapult. The scope of the tests consisted of ditching the models at various conditions of simulated damage, landing attitudes, and speeds, with various flap settings using several degrees of restraint of the flap hinges. The ditching behavior was evaluated from recordings of deceleration, length of run, and motions of the models" (p. 1).

Report presenting the use of known conical-flow solutions of the linearized equation for the velocity potential in supersonic flow as applied to the calculation of the characteristics of control surfaces. Solutions for the pressure distributions are obtained for control surfaces with hinge lines swept ahead or behind the Mach line when the control-surface trialing edge is swept ahead of the Mach line.

Memorandum presenting measurements of gust and draft velocities within cumulus clouds at a certain army air field using an AT-6 airplane. The measurements were made to supplement the at a obtained with P-61C airplanes. The data are summarized in tables.

The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from August 16, 1947 to August 20, 1947 are presented.

Report presenting testing of three different types of afterbodies on a powerful dynamic model of a flying boat with a basic length-beam ratio of 10.0. The three afterbodies tested were one with constant dead rise, one with warped dead rise, and one of extended length with warped dead rise. Results regarding aerodynamic characteristics and hydrodynamic characteristics are provided.

Monthly report of the U.S. Geological Survey's trace element investigations including an outline of field work, laboratory work, and staff activities that have been completed or are in process.

The Atomic Energy Commission informally requested the Geological Survey to collect samples of concentrates from Idaho placer operations that might be useful for experimental study of monazite recovery.

Two illustrations showing locations of Trace Elements Offices in the United States and an index map of part of the Colorado Plateau produced for a Febuary 1948 report of the U.S. Geological Survey's trace element investigations.

Report presenting results for a test program on 24S-T aluminum-alloy flat compression panels with longitudinal hat-section stiffeners. The results for panels in which the thicknesses of the stiffener material are 0.39 and 1.25 times the skin thickness are presented and incorporated with previously provided results. These results are presented in tabular and graphical form and show the effect of the relative dimensions of a panel on the buckling stress and the average stress at failure.

Report presenting a strain-energy theory for the calculation of the buckling load in general instability of circular reinforced monocoque cylinders with a side cutout and subjected to pure bending.

Note presenting data on the tensile strength, fatigue strength, creep properties, and thermal expansion of forged aluminum alloys XB18S, 18S, 24S, and 32S, which are pertinent to the application of these alloys in the temperature range from 70 to 800 degrees Fahrenheit. The paper also includes a critical discussion of the data and its application to design of aircraft engines.