In this report a method is presented for the calculation of the profile drag of airfoil sections. The method requlres only a knowledge of the theoretical velocity distribution and can be applied readily once this dlstribution is ascertained. Comparison of calculated and experimental drag characteristics for several airfoils shows a satisfactory agreement. Sample calculatlons are included.

Report issued by the U.S. Bureau of Mines on the documented explosives testing during 1943. Properties of explosives tested are presented. This report includes tables, graphs, and illustrations.

Abstract. A review of all work on uranium hydride published in the CC, CT, CN and CE reports to January 1, 1944, is presented. Some additional information not yet published has been included, so this report includes all data known from the above sources and at Ames to the above date. This report supersedes all previous report on uranium hydride coming out of the Ames laboratory.

Technical report describing a gasometrical method for the determination of H2 in extruded U rods.

Technical Report: A generalized review of the chemical problems and researches related principally to the heavy water homogeneous pile is presented herewith. The report covers researches performed principally by the Columbia Group who initiated the study. This report contains a chronological outline of the development, a discussion of some special topics whose significance is paramount in any slurry pile discussion, and finally an outline of important research problems remaining, roughly graded in order of their importance. No attempt has been made to be either complete or detailed in the discussion. The emphasis has been principally on furnishing a broad guide to those who may t some future date take up this work.

Six structural materials (aluminum 2S, aluminum 72S, copper, iron, steel, lead and bismuth) were irradiated for about 100 kilowatt hours in the center of the Argonne pile. The alpha and gamma decays were then followed for 130 days on Geiger counters and are presented here graphically as number of rays per minute per gram per kilowatt hour vs. time of decay. A quantitative interpretation of the gamma-ray decay curves gave fair agreement with the chemical analysis of impurities found in the materials.

The temperature coefficient of eta has been measured with the thermal column of the Argonne pile using uranium foils of different isotopic ratios. The temperature change was effected by filtering neutrons through silver. The measured fractional change per degree centigrade is [formula].

From introduction: "You will find enclosed the specifications for the freezing point method for determination of the amount of HF in UF₆. The specification for cleaning new shipping containers is also included."

Report re-examining known procedures for handling general resistance testing on flying-boat hull models, with particular attention paid to saving test time and improving the usefulness of the results to designers. While specific testing will likely always be needed, the procedures given in the report for condensing resistance data should make data analysis easier to apply to design.

Report presenting wind-tunnel testing in two-dimensional flow to investigate the aerodynamic characteristics of a flap balanced by a large overhang linked to deflect more slowly than the flap. Three lengths of blunt-nose overhang were tested linked to a 0.30-airfoil-chord straight-contour flap on an NACA 66-009 airfoil. Results regarding lift, hinge moment, drag, pitching moment, and practical considerations are provided.

Report presenting measurements in the full-scale tunnel of the pressure distribution over the horizontal tail surface of a typical pursuit airplane in order to determine the effects of propeller operation and angle of yaw on the tail load distribution. Most of the tests were made with the propeller operating to simulate climb conditions, high-speed dives, and pull-ups to various normal accelerations for a range of angles of yaw. Results regarding chordwise pressure distributions, spanwise distributions of normal-force coefficient, airflow measurements, and tail-load asymmetry are provided.

"The relation between the elevator hinge-moment parameters and the control forces for changes in forward speed and in maneuvers is shown for several values of static stability and elevator mass balance" (p. 1). Factors affecting stability positively and negatively are presented and potential modifications to the elevator control system are provided. The amount of solid friction present was found to be one of the greatest predictors of instability.

Report presenting compression testing on several series of flat panels with Z-section stiffeners with varying relative dimensions. The data presented show the effect of dimension ratio on the buckling stress for the sheet and on average stress at maximum load.

Report discusses an investigation that was conducted to compare the strength and tightness of machine-countersunk flush-riveted joints assembled with NACA flush rivets and a type of commercial flush rivet. A comparison was also generated between the strength and tightness of counterpunched flush-riveted joints assembled with the same types of rivet. NACA's flush-riveted joints tended to be stronger and tighter than the commercial joints.

Report presenting testing made on a Wright 1820-G single-cylinder engine to determine the effect of operating variables and the effect of shape and size of the exhaust stack on the visibility of exhaust gases for individual-stack installations. Flame damping was improved by decrease in nozzle-exit area, increase in stack length, and reduction in hydraulic diameter of the exhaust jets. Results regarding the characteristics of exhaust flames and damping of exhaust flames are provided.

"A procedure which takes into account the aerodynamic span effect is given for the determination of the torsional-divergence velocities of monoplanes. The explicit solutions obtained in several cases indicate that the aerodynamic span effect may increase the divergence velocities found by means of the section-force theory by as much as 17 to 40 percent. It is found that the magnitude of the effect increases with increasing degree of stiffness taper and decreases with increasing degree of chord taper" (p. 1).

Report presenting an investigation of the effectiveness of suction slots as a means of extending the laminar boundary layer in flight at high Reynolds numbers on an NACA 35-215 airfoil. The results showed that, with a slot spacing of about 5 percent of the chord, the laminar boundary layer could be maintained to or slightly beyond 45 percent of the chord.

Note presenting a least-squares procedure adapted to numerical calculation for the approximate solution of the Prandtl lifting-line equation. Sufficient data are tabulated to permit a solution of the equation by purely numerical methods for an arbitrary symmetrical variation of the chord and the angle of attack.

Report presenting an investigation of the shape of stress-strain curve for a material, especially when the material is subjected to compression, which may cause materials to become unstable at stresses beyond the elastic range. The ratio of stresses to effective modulus is explored in equation form.

Note presenting an effective value of Poisson's ratio for 18:8 Cr-Ni steel computed from values of tensile and torsional moduli of elasticity obtianed in earlier investigations by use of an appropriate formula.

From Summary: "The various types of hydrodynamic instability - including porpoising, skipping, and yawing - that may be encountered during take-off or landing of a flying boat are described and the piloting technique required for efficient take-offs and landings is discussed. Suggestions are made for assisting a pilot to become familiar with the take-off and landing qualities of a flying boat that is new to him."

An analysis has been made of the drag losses in airplane flight of cross-flow plate and tubular intercoolers to determine the cooling-air weight flow and pressure drop that give a minimum drag loss for any given cooling effectiveness and, thus, a maximum power-plant net gain due to charge-air cooling. The drag losses considered in this analysis are those due to (1) the extra drag imposed on the airplane by the weight of the intercooler, its duct, and its supports and (2) the drag sustained by the cooling air in flowing through the intercooler and its duct. The investigation covers a range of conditions of altitude, airspeed, lift-drag ratio, supercharger-pressure ratio, and supercharger adiabatic efficiency. The optimum values of cooling air pressure drop and weight flow ratio are tabulated. Curves are presented to illustrate the results of the analysis.

The effect of internal cooling on the knock-limited performance of an-f-28 fuel was investigated in a CFR engine, and the following internal coolants were used: (1) water, (2), methyl alcohol-water mixture, (3) ammonia-methyl alcohol-water mixture, (4) monomethylamine-water mixture, (5) dimethylamine-water mixture, and (6) trimethylamine-water mixture. Tests were run at inlet-air temperatures of 150 degrees and 250 degrees F. to indicate the temperature sensitivity of the internal-coolant solutions.

Report presenting the effect of internal cooling on the knock-limited performance of AN-F-28 fuel in a CFR engine with the following internal coolants: water, methyl alcohol-water mixture, ammonia-methyl alcohol-water mixture, monomethyllamine-water mixture, dimethylamine-water mixture, and trimethylamine-water mixture.