From Summary: "Trajectories of water droplets about an ellipsoid of revolution with a fineness ratio of 5 (which often approximates the shape of an aircraft fuselage or missile) were computed with the aid of a differential analyzer. Analyses of these trajectories indicate that the local concentration of liquid water at various points about an ellipsoid in flight through a droplet field varies considerably and under some conditions may be several times the free-stream concentration."

"A photomicrographic technique for investigating seupercooled water droplets has been devised and. used. to determine the spontaneous freezing temperatures of seupercooled water droplets of the size ordinarily found. in the atmosphere. The freezing temperatures of 4527 droplets ranging from 8.75 to 1000 microns in diameter supported on a platinum surface and 571 droplets supported on copper were obtained. The average spontaneous freezing temperature decreased with decrease in the size of the droplets" (p. 1).

"A study is made of the effect of variation in diameter and pitch of A17S-T4 aluminum-alloy flat-head rivets on the average stress at maximum load for 24S-T3 and 75S-T6 aluminum-alloy, flat, Z-stiffened panels that fail by local instability. A curve is presented for determining the diameter and pitch required to insure the development of a given average stress for local instability" (p. 1).

Report presenting a prediction of the magnitude of temperature variation in order to detect the places of highest temperature and to determine the operating temperatures admissible for the material of which the heat exchanger is composed. Results regarding the temperature distribution in triangular passages, temperature distribution in rectangular passages, influence of velocity field on temperature field, and a comparison of Prandtl number 1 solution are provided.

Report presenting experiments conducted to obtain information on heat transfer in turbulent, mixed-free- and -forced-convection flow. The investigation revealed that the total flow regime as characterized by its Reynolds and Grashof numbers can be subdivided into a forced-flow regime, a free-flow regime, and a mixed-free- and -force-convection regime.

Report presenting an investigation to determine the effects of leading-edge radius and profile thickness on the oscillatory lateral stability derivatives for a series of delta wings with 60 degrees of leading-edge sweep. The wings were oscillated in yaw about their vertical axes. Results indicated that there were noticeable decreases in all the derivatives due to increase in leading-edge radius at angles of attack above approximately 12 degrees.

Report presenting testing in the high-speed 7- by 10-foot tunnel to investigate the high-subsonic static longitudinal stability characteristics and lift-drag ratios of several wing-body models designed to provide high lift-drag ratios at Mach number 1.4. The basic configuration had a thin highly swept wing of aspect ratio 2.91 with NACA 65-A series airfoil sections. Results regarding longitudinal stability, lift, drag, and lift-drag ratio are provided.

Note presenting an investigation of the influence of systematic variations of chemical composition on rupture properties at 1500 degrees Fahrenheit for 62 modifications of a basic alloy. All of the elements in the alloy can be varied individually between quite wide limits without significantly changing the rupture properties. Results regarding carbon, nitrogen, manganese, silicon, chromium, nickel, cobalt, molybdenum, tungsten, and columbium are provided.

Note presenting an investigation of the effect of phosphate coatings on the temperature of metal specimens placed in a flame. Small cylindrical specimens of mild steel and S-816 alloy were placed in a natural-gas-air flame at specific temperatures. Special attention is given to the fact that temperature drop was noted in certain specimens and the potential reasons for this reaction are explored.

"The various factors governing buckling of flat plates are critically reviewed and the results are summarized in a comprehensive series of charts and tables. Numerical values are presented for buckling coefficients of flat plates with various boundary conditions and applied loadings. The effects of plasticity are incorporated in non dimensional buckling charts utilizing the three-parameter description of stress-strain curves" (p. 1).

The preliminary selection of a propeller on the basis of cruising and take-off performance for application to transport airplanes at flight Mach numbers up to 0.8 can be accomplished by the use of charts and methods presented. The charts are of sufficient scope to permit a fairly rapid evaluation of the propeller performance for engine power ratings of 1,000 to 10,000 horsepower. The method is presented primarily in the interest of propeller-noise abatement.

Report presenting an investigation to determine the induced effect of sweep on an axial-flow compressor blade. Results regarding the blade-section pressure distributions, matching pressure distributions, comparison of turning angles in compressor and cascade, corrected turning angles, and normal-force coefficients are provided.

Report presenting flight tests to determine the lateral and directional stability and control characteristics of an F-47D-30 airplane. Results regarding the physical characteristics, static directional and lateral stability and control characteristics, dynamic directional stability and control characteristics, directional and lateral trim characteristics, and aileron control characteristics are provided.

"The effect of modifying the gas passage of hollow metal airfoils by the addition of internal fins and partitions was experimentally investigated and comparisons were made among a basic unfinned airfoil section and two airfoil designs having metal fins attached at the leading edge of the internal gas passage. An analysis considering the effects of heat conduction in the airfoil metal was made to determine the internal modification effectiveness that may be obtained in gas-heated components, such as turbojet-inlet guide vanes, support struts, hollow propeller blades, and thin wings" (p. 1).

Thermodynamic and transport properties of high temperature air, and the reaction rates for the important chemical processes which occur in air, are reviewed. Semiempirical, analytic expressions are presented for thermodynamic and transport properties of air. Examples are given illustrating the use of these properties to evaluate (1) equilibrium conditions following shock waves, (2) stagnation region heat flux to a blunt high-speed body, and (3) some chemical relaxation lengths in stagnation region flow.

Report presenting theoretical results for the lateral force and yawing moment due to combined angle of attack and roll. The thin wings are tapered and have leading and trailing edges which are each swept at a constant angle; the tips are parallel to the center section.

From Introduction: "Early in 1951 the National Advisory Committee for Aeronautics published, as Technical Note 2276 (ref. 1), a report by the Aluminum Research Laboratories of the Aluminum Company of America on the results of static and fatigue tests of high-strength aluminum alloy monobloc specimens and bolted joints. In view of special interest shown by several aircraft companies, certain expansions of the test program were undertaken by the Aluminum Research Laboratories and are reported herein."

"The minimization of wave drag for thin aerodynamic shapes carrying no lift is studied for conditions under which either base area or volume is specified. When volume alone is given, the analysis is limited to shapes with straight trailing edges normal to the stream direction. The problem of minimization is reduced to one of finding a two-dimensional harmonic function with known boundary conditions" (p. 1).

Report presenting the derivation of the integral equations for transonic flow around slender wings and bodies of revolution, with special attention paid to conditions resulting from the presence of shock waves and to the reduction of the relations to the special forms necessary for the discussion of sonic flow.

Efficient temperature ranges are indicated for two high-strength aluminum alloys, two titanium alloys, and three steels for some short-time compression-loading applications at elevated temperatures. Only the effects of constant temperatures and short exposure to temperature are considered, and creep is assumed not to be a factor. The structural efficiency analysis is based upon preliminary results of short-time elevated-temperature compressive stress-strain tests of the materials. The analysis covers strength under uniaxial compression, elastic stiffness, column buckling, and the buckling of long plates in compression or in shear.

Results are presented of tests to determine the effect of heating at uniform temperature rates from 0.2 degrees to 100 degrees F per second on the tensile properties of 7075-T6 d(75s-T6) and 2024-T3 (24s-T3) aluminum-alloy sheet under constant-load conditions. Yield and rupture stresses, obtained under rapid-heating conditions, are compared with results of elevated-temperature stress-strain tests for 1/2-hour exposure. Master yield-and-rupture-stress curves based on linear temperature-rate parameter are presented. Yield and rupture stresses and temperatures may be predicted by means of master curves and the parameter.

From Summary: "Results are presented of rapid-heating tests to determine the tensile strength of Inconel and RS-120 titanium-alloy sheet heated to failure at uniform temperature rates from 0.2 degrees Fahrenheit to 100 degrees Fahrenheit per second under constant load conditions. Yield and rupture stresses, obtained by rapid heating, are compared with yield and ultimate stresses from elevated-temperature tensile stress-strain tests for 1/2-hour exposure. The applicability of master curves and temperature-rate parameters to the prediction of yield and rupture stresses and temperatures under rapid-heating conditions was investigated."

A flight investigation of two Nike-Deacon (DAN) two-stage solid-propellant rocket vehicles indicated satisfactory performance may be expected from the DAN meteorological sounding rocket. Peak altitudes of 356,000 and 350,000 feet, respectively, were recorded for the two flight tests when both vehicles were launched from sea level at an elevation angle of 75 degrees. Performance calculations based on flight-test results show that altitudes between 358,000 feet and 487,000 feet may be attained with payloads varying between 60 pounds and 10 pounds.

A discussion of the acoustic fatigue problem of aircraft structures along with data pertaining to the acoustic inputs from some power plants in common use. Comparisons are given for results of fatigue tests of flat panels and cantilever beams exposed to random- and discrete-type inputs. Both the stress level of the test and type of model are significant, so no generalizations can be made at this time.