Report presenting two low-drag airfoils, the NACA 747A315 and the NACA 747A415, which are designed to have reduced pitching moments about the quarter-chord point and moderately high values of the design lift coefficient and are tested in the tow-dimensional low-turbulence pressure tunnel.

From Introduction: "The purpose of this analysis was to investigate the use of function of intake-manifold temperature and pressure, exhaust back pressure, and engine speed in place of a ventri as a means of measuring engine air consumption and to determine if this function is suitable for automatic mixture control."

From Introduction: "The purpose of this analysis was to investigate the use of a function of intake-manifold pressure, exhaust back pressure, intake manifold temperature, and engine speed in place of a venturi as a means of measuring engine air consumption and to determine if this function is suitable for automatic mixture control."

Report presenting 10 practical-construction models of sections of helicopter rotor blades tested in the NACA two-dimensional low-turbulence pressure tunnel at atmospheric pressure. Lift, drag, and pitching-moment characteristics of blades representing the present method of construction of the YR-4A helicopter were determined.

From Introduction: "The lift increments of different flap arrangements were determined by the method of reference 1 with a simple chord correction factor being applied. This procedure is somewhat similar in basic principles to the method of reference 2. The accuracy of the present method was determined by calculating by means of this method the lift and moment increments of flaps on 10 different finite wing-flap combinations for which wind-tunnel data were available."

Note presenting an investigation of the effect of artificial aging on the strengths of driven rivets of the alloys used commercially for rivets: specifically, A17S-T, 17S-T, and 24S-T. The change in shear strength for each type of rivet after being exposed to artificial aging treatment of 10 hours at 375 degrees Fahrenheit applied to the driven rivets is described.

A theoretical and experimental investigation has been made of the behavior of a cantilever beam in transverse motion when its root is suddenly brought to rest. Equations are given for determining the stresses, the deflections, and the accelerations that arise in the beam as a result of the impact. The theoretical equations, which have been confirmed experimentally, reveal that, at a given percentage of the distance from root to tip, the bending stresses for a particular mode are independent of the length of the beam, whereas the shear stresses vary inversely with the length.

Transmitted herewith are three charts showing the temperatures attained at various points of the slugs in a typical tube of a flat ended pile. These charts are based on the latest information available to us on September 15, 1944. They are valid for any power load when the water rate is 21.0 gpm, whatever may be the inlet temperature of the cooling water. A simple method is provided for correcting the curves for deviations in water rate from 21 gpm. There is appended a detailed explanation of their derivation and of the evaluation of the constants involved in their construction. The current discovery that the pile will be self-poisoned by transient fission products means that the true temperature curves will be somewhat flatter than those here presented.

Report presenting a description of a short method of estimating propeller efficiency for a given operating condition. The efficiency is determined for any design condition by evaluating separately from charts the induced losses and the profile-drag losses. The report covers single-rotating propellers of two, three, four, six, and eight blades and includes charts showing the rotational-energy loss for the given operating condition.

Describes the organization, training, and operations of the Chemical Decontamination Company.

Report presenting results of compression tests of six paper-base plastic panels with outward-acting normal pressure. All panels failed by separation of the skin, either from the rib or from the stiffeners. Results regarding the introduction of air pressure and types of failures encountered are provided.

Report detailing values of x-ray lives and limits for trans-uranic elements. Formulas and methods are detailed throughout the report.

Report presenting flight data, which shows that the absolute minimum or limit pressure coefficient on an airfoil is a function mainly of the Mach number for Mach numbers above about 0.3 and for usual flight values of the Reynolds number. The curve of limit pressure coefficient as a function of Mach number is established.

Report presenting some principles for designing the optimum hull for a large long-range flying boat in order to suit the requirements of minimum drag, seaworthiness, and ability to take off and land at all operational gross weights. The principles include the use of moderate gross-load coefficients, ample forebody lengths, and deep steps and the close adherence of the form to that of a streamline body of revolution with a moderate fineness ratio.

Report discusses an apparatus that may be used for indicating the formation of fatigue cracks or for following the progress of cracks. Details of the experiment and discussion of the way in which the deflection-crack area relationship may be used to monitor fatigue cracks are included.

Report presenting a convenient technical method to evaluate changes in the airfoil characteristics resulting from an extension of the chord at the trailing edge of a propeller blade section. The method determines the change in the angle of zero lift, the ideal angle of attack, and the difference in these angles as a function of the angle and length of the trailing-edge extension.

"Thirty-nine Z-sections formed from 24S-T aluminum-alloy sheet with the angle of bend between the flanges and the web varying from 5 degrees to 120 degrees were tested as columns. Angles of bend from 30 degrees to 120 degrees had little or no effect on the critical stress or on the average stress at maximum load for local instability of the columns. The lengths of the columns were such that at angles of bend below 30 degrees they failed by Euler buckling" (p. 1).

Report presenting an investigation to determine the effect of fuel volatility on engine power and economy as influenced by mixture distribution. Tests of four fuels of different volatility were conducted on a Wright R-2600-8 engine at desired cruising power, maximum cruising power, normal rated power, and takeoff power.

Report presenting a study to determine the effect of several methods of increasing the knock-limited power on critical cylinder temperatures. The knock-limited indicated horsepower and cylinder temperatures were determined for a Wright R-2600-8 cylinder under specified operating conditions. The most satisfactory method of increasing knock limited power was found to be internal cooling with water and the least satisfacotry was increasing the engine speed.

Report presenting an investigation conducted to determine the effect of water injection on the knock-limited performance of a V-type 12-cylinder liquid-cooled engine. The knock-limited performance tests were made at an engine speed of 3000 rpm with carburetor-air temperatures of 158, 101, and 50 degrees Fahrenheit at water-fuel ratios of 0, 0.2, 0.4, and 0.6.

Report presenting an analysis of the available data on the effects of trailing-edge modifications on the pitching-moment characteristics of airfoils. Some of the variables explored include the location of the airfoil aerodynamic center and variation of pitching-moment coefficient with control-surface deflection are provided.

Report discusses the results of an investigation into the effectiveness of water injection into the combustion end zone of a spark-ignition engine cylinder for the suppression of knock. The injection angle was found to be very important for obtaining maximum results. The results of various angles and amounts of water were examined.

Effect of aquadag coating on noise reduction in polyethylene coaxial cable was tested. A satisfactory combination of coaxial cables and connectors interconnecting sources of small ion currents or ionizing impulses with the measuring device is described.

Report presenting the fatigue data obtained at the Aluminum Research Laboratories from tests of various types of 17S-T and 53S-T specimens. The specimens were large enough to represent actual service conditions, but the repetition of loading was more rapid than would occur in ordinary service.