Report presenting an investigation of finite span wing-cooling ducts that has been extended to include a study of the effects of slipstream on the duct characteristics. The results indicated that the propeller slipstream is effective in generating a flow of air through the ducts of the ground condition.

The drag characteristics of eight radial-engine cowlings have been determined over a wide speed range in the N.A.C.A. 8-foot high-speed wind tunnel. The pressure distribution over all cowlings was measured, to and above the speed of the compressibility burble, as an aid in interpreting the force tests. One-fifth-scale models of radial-engine cowlings on a wing-nacelle combination mere used in the tests.

"A recent investigation of numerous related airfoils indicated that positions of camber forward of the usual location resulted in an increase of the maximum lift. As an extension of this investigation, a series of forward-camber airfoils has been developed, the members of which show airfoil characteristics superior to those of the airfoils previously investigated. The primary object of this report is to present fully corrected results for airfoils in the useful range of shapes. With the data thus made available, an airplane designer may intelligently choose the best possible airfoil-section shape for a given application and may predict to a reasonable degree the aerodynamic characteristics to be expected in flight from the section shape chosen" (p. 1).

Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, summaries of the committee's activities and research accomplished, bibliographies, and financial report.

Report presents the results of an investigation of a systematically chosen representative group of related airfoils conducted in the NACA variable-density wind tunnel over a wide range of Reynolds number extending well into the flight range. The tests were made to provide information from which the variations of airfoil section characteristics with changes in the Reynolds number could be inferred and methods of allowing for these variations in practice could be determined. This work is one phase of an extensive and general airfoil investigation being conducted in the variable-density tunnel and extends the previously published researches concerning airfoil characteristics as affected by variations in airfoil profile determined at a single value of the Reynolds number.

"An investigation was conducted in the NACA full-scale wind tunnel to determine the aerodynamic characteristics of the NACA 0009, 0012, and 0018 airfoils, with the ultimate purpose of providing data to be used as a basis for comparison with other wind-tunnel data, mainly in the study of scale and turbulence effects. Three symmetrical 6 by 36-foot rectangular airfoils were used. The Reynolds number range for minimum drag was form 1,800,000 to 7,000,000 and for maximum lift, from 1,700,000 to 4,500,000" (p. 1).

From Summary: "Wind-tunnel tests are reported of six 3-blade 10-foot propellers operated in front of a liquid-cooled engine nacelle. The propellers were identical except for blade airfoil sections, which were: Clark y, R.A.F. 6, NACA 4400, NACA 2400-34, NACA 2rsub200, and NACA 6400. The range of blade angles investigated extended for 15 degrees to 40 degrees for all propellers except the Clark y, for which it extended to 45 degrees. The results showed that the range in maximum efficiency between the highest and lowest values was about 3 percent. The highest efficiencies were for the low-camber sections."

Report presenting an approximate method of computing the induced efficiency of heavily loaded propellers in suitable form for extension to finite number of blades and a comparison of results obtained using the method with the data of the Betz-Helmbold theory for heavily loaded propellers.

Report from Sugarland Industries discussing income and expenses. The profit for each period is also shown for 1936 through 1938.

Corporate income and excess-profits tax return of 1938 for Texas Cotton Industries. The return includes all necessary schedules. The franchise tax return and capital stock tax returns are also attached with their respective schedules and financial statements.

Minutes, committee assignments, and financial statements of the Stillwater Chamber of Commerce, including news articles of activities and meetings for the year 1939.

The report provides data and information about communicable and reportable diseases in Texas (chicken pox, diphtheria, dysentery, influenza, malaria, measles, meningitis, pellagra, pneumonia, poliomyelitis, scarlet fever, smallpox, tuberculosis, tularemia, typhoid fever, undulant fever, whooping cough) during 1938.

Annual report submitted by the Boy Scouts of America to Congress describing highlights from 1938, activities, service reports, honors, finance, organizational leadership, and other information about scouting programs.

Data complied regarding wells and other water resources, including water quality analysis, measurements, and other relevant information.

Annual report of the Texas Comptroller of Public Accounts documenting financial records including disbursements and transactions made by the office during fiscal year 1939.

A selection of Russian papers on the geochemical prospecting for ores