Memorandum presenting the use of the modified slender-body method to predict the lift and moment interference of triangular wing-body combinations adapted to combinations with other than triangular wings. The methods are applied to the prediction of the lit-curve slopes of nearly 100 triangular, rectangular, and trapezoidal wing-body configurations.

"Investigations have been made in flight and in wind tunnels to determine which components of turbojet installations are most critical in icing conditions, and to evaluate several methods of icing protection. From these studies, the requirements necessary for adequate icing protection and the consequent penalties on engine performance can be estimated. Because investigations have indicated that the compressor-inlet screen constitutes the greatest icing hazard and is difficult to protect, complete removal or retraction of the screen upon encountering an icing condition is recommended" (p. 1).

From Summary: "A Bragg X-ray spectrometer equipped with a volume-sensitive Geiger counter and Soller slits and employing filtered molybdenum Ka radiation was used to obtain a set of diffracted intensity curves as a Punction of angle for supercooled water. Diffracted intensity curves in the temperature region of 21 to -16 C were obtained. The minimum between the two main diffraction peaks deepened continuously with lowering temperature, indicating a gradual change in the internal structure of the water. No discontinuity in this trend was noted at the melting point. The internal structure of supercooled water was concluded to become progressively more ice-like as the temperature is lowered."

From Summary: "Icing and drag investigations were conducted in the NACA Lewis icing research tunnel employing a combination thermal-pneumatic de-icer mounted on a 42-inch-chord NACA 0018 airfoil. The de-icer consisted of a 3-inch-wide electrically heated strip symmetrically located about the leading edge with inflatable tubes on the upper and lower airfoil surfaces aft of the heated area. The entire de-icer extended to approximately 25 percent of chord. A maximum power density of 9.25 watts per square inch was required for marginal ice protection on the airfoil leading edge at an air temperature of 00 F and an airspeed of 300 miles per hour."

Memorandum presenting an analysis made to estimate the performance of a direct-air nuclear turbojet-powered airplane using a split-flow reactor and a separated-type shield. The analysis was for flight Mach numbers of 0.9 and 1.5 and covered a range of altitudes, reactor-wall temperatures, turbine-inlet temperatures, compressor pressure ratios, and airplane lift-drag ratios.

"An empirical method for the determination of the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The procedure represents an initial step toward the development of a method which is generally applicable in the design of thermal ice-prevention equipment for airplane wing and tail surfaces. Results given by the proposed empirical method are expected to be sufficiently accurate for the purpose of heated-wing design, and can be obtained from a few numerical computations once the velocity distribution over the airfoil has been determined" (p. 1).

"A principle formerly used in an instrument for cloud detection was further investigated to provide a simple and rapid means for measuring the liquid-water content of clouds at temperatures above and below freezing. The instrument consists of a small cylindrical element so operated at high surface temperatures that the impingement of cloud droplets creates a significant drop in the surface temperature. The instrument is sensitive to a wide range of liquid-water content and was calibrated at one set of fixed conditions against rotating multicylinder measurements. The limited conditions of the calibration Included an air temperature of 20 F, an air velocity of 175 miles per hour, and a surface temperature in clear air of 475 F" (p. 1).

Memorandum presenting an instrument for recording and indicating the frequency and intensity of aircraft icing conditions to obtain statistical icing data over worldwide air routes during routine airline operations. Data of this type is needed to provide pertinent meteorological information necessary for the optimum design of ice-protection systems. The features that make this particular instrument desirable include the simplicity of operation, freedom from maintenance and operating problems, automatic operation upon encountering an icing condition, visual indications of icing intensity available to the pilot, total weight of 18 pounds, and continuous recorded data.

From Summary: "A flight instrument that uses electric means for measuring the droplet-size distribution in above-freezing clouds has been devised and given preliminary evaluation in flight. An electric charge is placed on the droplets and they are separated aerodynamically according to their mass. Because the charge placed on the droplets is a. function of the droplet size, the size spectrum can 'be determined by measurement of the charge deposited on cylinders of several different sizes placed to intercept the charged droplets. An expression for the rate of charge acquisition by a water droplet in a field of coronal discharge is derived."

"A cascade impactor, an instrument for obtaining the size distribution of droplets borne in a low-velocity air stream, was adapted for flight cloud droplet-size studies. The air containing the droplets was slowed down from flight speed by a diffuser to the inlet-air velocity of the impactor" (p. 1).

"An investigation of the heat transfer from an airfoil in clear air and in simulated icing conditions was conducted in the NACA Lewis 6- by 9-foot icing-research tunnel in order to determine the validity of heat-transfer data as obtained in the tunnel. This investigation was made on the same model NACA 65,2-016 airfoil section used in a previous flight study, under similar heating, icing, and operating conditions. The effect of tunnel turbulence, in clear air and in icing was indicated by the forward movement of transition from laminar to turbulent heat transfer" (p. 1).

"An experimental investigation was conducted to determine the temperature profile downstream of a heated-air jet directed perpendicularly to an air stream. The profiles were determined at several positions downstream of the jet as functions of jet density, jet velocity, free-stream density, free-stream velocity, jet temperature, and orifice flow coefficient. A method is presented which yields a good approximation of the temperature profile in terms of dimensionless parameters of the flow and geometric conditions" (p. 1).

From Summary: "The general characteristics of the flow field in a submerged air inlet are investigated by theoretical, wind-tunnel, and visual-flow studies. Equations are developed for calculating the laminar and turbulent boundary-layer growth along the ramp floor for parallel, divergent, and convergent ramp walls, and a general equation is derived relating the boundary-layer pressure losses to the boundary-layer thickness. It is demonstrated that the growth of the boundary layer on the floor of the divergent-ramp inlet is retarded and that a vortex pair is generated in such an inlet."

Note presenting data from various sources on the observed values of meteorological variables, liquid-water content, mean-effective droplet size, and temperature, which are pertinent to aircraft icing. A method is proposed for the selection of design criterions for ice-protection equipment. The data are divided into two broad cloud types, stratiform and cumuliform clouds, because the icing conditions are very different for the two types.

"Liquid-water content, droplet size, and temperature data measured during 22 flights in predominately stratiform clouds through the 1948-49 and the 1949-50 winters are presented. Several icing encounters were of greater severity than those previously measured over the same geographical area, but were within the limits of similar measurements obtained over different terrain within the United States. An analysis of meteorological conditions existing during the 74 flights conducted for four winters indicated an inverse relation of liquid-water concentration to maximum horizontal extent of icing clouds" (p. 1).

"Flight icing-rate data obtained in a dense and abnormally deep supercooled stratiform cloud system indicated the existence of liquid-water contents generally exceeding values in amount and extent previously reported over the midwestern sections of the United States. Additional information obtained during descent through a part of the cloud system indicated liquid-water contents that significantly exceeded theoretical values, especially near the middle of the cloud layer. The growth of cloud droplets to sizes that resulted in sedimentation from the upper portions of the cloud is considered to be a possible cause of the high water contents near the center of the cloud layer" (p. 1).

"The results of surface-tension measurements for supercooled water are presented. A total of 702 individual measurements of surface tension of triple-distilled water were made in the temperature range, 27 to -22.2 C, with 404 of these measurements at temperatures below 0 C. The increase in magnitude of surface tension with decreasing temperature, as indicated by measurements above 0 C, continues to -22.2 C. The inflection point in the surface-tension - temperature relation in the vicinity of 0 C, as indicated by the International Critical Table values for temperatures down to -8 C, is substantiated by the measurements in the temperature range, 0 to -22.2 C" (p. 1).

"The achievement of more compact and efficient power plants for aircraft is dependent, among other factors, on the perfection of heat-resisting materials that are superior to those in current use. Molybdenum is one of the high-melting metals (melting point, 4750 F). It is fairly abundant and also can be worked into many of the shapes required in modern power plants. To permit its widespread use at elevated temperatures, however, some means must first be found to prevent its rapid oxidation" (p. 1).

"An experimental investigation was conducted to determine the cooling effectiveness of a wide variety of air-cooled turbine-blade configurations. The blades, which were tested in the turbine of a - commercial turbojet engine that was modified for this investigation by replacing two of the original blades with air-cooled blades located diametrically opposite each other, are untwisted, have no aerodynamic taper, and have essentially the same external profile. The cooling-passage configuration is different for each blade, however" (p. 1).

From Summary: "Research was conducted to determine the effect of the electrode parameters of spacing, configuration, and material' on the energy required for ignition of a flowing propane-air mixture. In addition, the data were used to indicate the energy distribution along the spark length and to confirm previous observations concerning the effect of spark duration on ignition energy requirements. The data were obtained with a mixture at a fuel-air ratio of 0.0835 (by weight), a pressure of 3 inches of mercury absolute, a temperature of 80 F, and a mixture velocity of 5 feet per second."

"An investigation has been conducted in the Langley 20-foot free spinning tunnel to study the relative behavior in descent of a number of homogeneous balsa bodies of revolution simulating anti-personnel bombs with a small cylindrical exploding device suspended approximately 10 feet below the bomb. The bodies of revolution included hemispherical, near-hemispherical, and near-paraboloid shapes. The ordinates of one near-paraboloid shape were specified by the Office of the Chief of Ordnance, U. S. Army" (p. 1).

Report presenting an investigation of the low-speed, power-off stability and control characteristics of a model of the McDonnell XF3H-1 airplane. Flight testing occurred in the clean and slat- and flaps-extended conditions over a range of lift coefficients.

Memorandum presenting an investigation of aileron effectiveness and dihedral effect for a wing-body combination with a variable-incidence triangular wing with modified half-delta controls at the wing tips. The tests were conducted at a Mach number of 1.52 at a Reynolds number of 0.82 million. The experimental value of aileron effectiveness at 0 degrees angle of attack was approximately 78 percent of the value predicted by linear theory, and the effectiveness decreased with increasing wing angle of attack.

Memorandum presenting an analysis of a system consisting of a mercury turbine-driven air compressor a mercury condenser wherein heat was added to the compressed air. The heat addition to the mercury is accomplished in an intermediate heat exchanger (mercury boiler) which has a liquid metal, other than mercury, circulating through the opposite side and through a nuclear reactor. Results regarding the turbine-exhaust pressure, turbine-inlet pressure, condenser-inlet Mach number, effect of nacelle drag, and some general data are provided.