A procedure proposed for use in the design of air-heated systems for the continuous prevention of ice formation on airplane components is set forth. Required heat-transfer and air-pressure-loss equations are presented, and methods of selecting appropriate meteorological conditions for flight over specified geographical areas and for the calculation of water-drop-impingement characteristics are suggested. In order to facilitate the design, a simple electrical analogue was devised which solves the complex heat-transfer relationships existing in the thermal-system analysis.

"The effects of primary and runback icing and frost formations on the drag of an 8-foot-chord NACA 651-212 airfoil section were investigated over a range of angles of attack from 20 to 80 and airspeeds up to 260 miles per hour for icing conditions with liquid-water contents ranging from 0.25 to 1.4 grams per cubic meter and datum air temperatures of -30 to 30 F. The results showed that glaze-ice formations, either primary or runback, on the upper surface near the leading edge of the airfoil caused large and rapid increases in drag, especially at datum air temperatures approaching 32 F and in the presence of high rates of water catch" (p. 1).

"Three multicylinder cloud meters, fundamentally similar but differing in important details, were compared in use at the Mount Washington Observatory. Determinations of liquid water content were found to agree within the limits of the probable error, but the two instruments designed by the National Advisory Committee for Aeronautics indicated larger drop sizes than did the Observatory's instrument, apparently because of spurious ice catch on the rather rough surface of the larger cylinders. Comparisons of drop-size distribution were largely indeterminate" (p. 1).

Report presenting an exploratory wind-tunnel investigation to determine the lift effects of blowing from nacelles over the upper surface of flaps on a model with a delta wing of aspect ratio 3. The results indicate that the values of jet-circulation lift coefficient larger than the jet reaction were produced with blowing over flaps fro nacelles mounted above the wing. Results regarding lift coefficients, pitching-moment coefficients, and drag coefficients are provided.

Note presenting a wind-tunnel investigation to determine the effects of jet-outlet cut-off angle on the directional and spreading characteristics of an unheated, subsonic air jet, and on the pitching moment of the body from which the jet issued. Results regarding the jet operating with the wind tunnel off, jet off with the wind tunnel operating, jet operating with the wind tunnel operating, and flow studies with the jet operating and the wind tunnel off are provided.

Report presenting practical methods for making the calculations required for the analysis of an autopilot and an autopilot-aircraft combination from frequency-response data. From Summary: "Equations are derived for determining the servo-system error voltage for both displacement input signal and displacement plus rate of displacement input signals, the autopilot frequency response for addition of rate of displacement input signal, the servo-system frequency response for a change of gain, and the relation between open-loop and closed-loop frequency responses for the servo system and the autopilot-aircraft combination."

Report presenting a method utilizing precalculated solutions graphically presented for calculating subsonic or supersonic ramjet performance parameters with the associated equations and graphs. By assuming constant values of specific-heat ratio and gas constant equal to those of standard air, the thrust-coefficient calculation has been reduced to a few simple operations.

From Summary: "A series of schileren photographs and pressure distributions are presented which show the effects of transition from an attached to a detached shock at the leading edge of a finite-span, 8.2 degree wedge as the angle of attack is increased. These data were obtained in the Langley 4- by 4-foot supersonic tunnel at a Mach number of 1.40."

Note presenting testing to determine whether lead compounds in the combustion products of high-octane fuel are a contributing factor in causing failures of the heat-resistant alloy parts in aircraft exhaust systems. To obtain answers for five heat-resistant alloys, a test was devised in which the alloy specimens in an uncoated condition, in a preoxidized condition, and with three different ceramic coatings were exposed for 6 hours to lead-containing vapors in an air atmosphere at 3 different temperatures.

Note presenting the effect of compressor-outlet air bleed on turbojet engine performance, which is calculated by the use of an analysis based on experimentally determined component characteristics of a centrifugal-flow turbojet engine with a constant-area jet nozzle. A range of engine speeds from 0.9 to 1.0 of rated engine speed and air-bleed rates fro 0 to 0.10 of compressor air flow are considered at a flight Mach number of 0.52 and an altitude of 24,000 feet. Results regarding the effect of air bleed on pumping characteristics and effect of air bleed on engine performance are provided.

Note presenting an analysis of the normal accelerations and operating conditions encountered by a single-rotor helicopter engaged in air-mail operations in the vicinity of Los Angeles and its suburbs over a period of 14 months. The results indicate that, for this type of operation, maneuver loads developed in routine flight are often greater than the largest gust loads.

Note presenting an investigation of the effect of open circular holes on the tensile strength and elongation of sheet specimens of magnesium alloy AM-C52S in both the annealed and hard-rolled condition. Tests were made to study the effect of variable ratio of hole diameter to total specimen width and the effect of spacing and arrangement of the holes.

Report presenting an evaluation of the performance of 14 commercial adhesives at a range of temperatures in lap shear specimens of clad 24S-T aluminum alloy to itself and that of 7 commercial adhesives at a range of temperatures in lap joints of cotton-fabric-phenolic laminate to itself, of glass-fabric-polyester laminate to itself, and in joints of each of these laminates to clad aluminum. Results regarding aluminum to aluminum joints and plastic to plastic and plastic to aluminum joints are provided.

Note presenting an investigation of the two-dimensional flow of a compressible, non-viscous fluid through blade systems of equidistant spacing, of identical shape, and of straight-line arrangement of position, for which the names of grid, cascade, deflector, and lattice systems are in use.

From Summary: "This reports presents of axial-load fatigue tests on notched specimens of three sheet materials: 24S-T3 and 75S-T6 aluminum alloys and normalized SAE 4130 steel. Each specimen was notched by edge notches designed to have a theoretical stress-concentration factor of 5.0. Tests were run at four levels of nominal mean, stress: 0, 10,000, 20,000, and 30,000 psi. Results of these tests extend information previously reported from tests on unnotched specimens and on specimens less severely notched."

From Summary: "The hydrocarbons - 2-cyclopropyl-1-butene, cis and trans 2-cyclopropyl-2-butene, and 2-cyclopropylbutane - were obtained from methylcyclopropyl ketone by reacting the ketone with ethylmagnesium bromide, dehydrating the resultant methylethylcyclopropylcarbinol to a mixture of olefins from which 2-cyclopropyl-1-butene and cis and trans 2-cyclopropyl-2-butene were isolated, and hydrogenating the olefins to 2-cyclopropylbutane. All four hydrocarbons were obtained in high purity for the first time; their physical constants and infrared spectra are presented."

Report presenting an investigation of the significance of tensile strength and ductility in the presence of defects and the strength-reducing effects of several types of defect were investigated for some rotating disks. Some of the defects investigated included laminar-type irregularities, eutectic melting, and shrink porosity.

From Introduction: "The results of one phase of this investigation, presented in reference 1, have indicated that hull drag can be reduced without causing large changes in aerodynamic stability and hydrodynamic performance by the use of high length-beam ratios. Another phase of the investigation, reference 2, indicated that hulls of the deep-step planning-tail type have much lower air drag than the conventional type of hull and about the same aerodynamic stability; tank tests, reference 3, have indicated that this type of hull also has hydrodynamic performance equal to and in some respects superior to the conventional type of hull. Unpublished tank tests have indicated that the hull models presented in the present paper (with the possible exception of the forebody alone for which data are not available) will have acceptable hydrodynamic performance."

Note presenting calculations of the ratios of the velocity increments at test bodies to those at the tunnel walls caused by the solid blocking of these bodies within the walls of a closed rectangular wind tunnel. The bodies treated include two-dimensional airfoils, small bodies of revolution, straight, untapered, finite-span wings of varying span, and swept, untapered, finite-span wings of varying span.

Report presenting an investigation of the flutter characteristics of a uniform, unswept, cantilever wing of high aspect ratio and under conditions of high mass coupling by means of a Rayleigh type analysis based on coupled modal functions. Results are compared with an experiment and the calculated results of NACA TN 1902.

"An analytical method based on successive approximations is presented for determining the loads and deflections throughout an indeterminate structure in which one or more of the members have been stressed beyond their proportional limits. Theoretical analyses of three structures are compared with tests and found to agree very closely. For the sake of simplicity and clarity, only coplanar pin-ended structures have been analyzed and tested" (p. 1).

Report presenting the effects of cyclic and continuous immersion in heptane, toluene, and SR-6, a test fuel, on the weight, dimensions, and flexural properties of 19 samples of laminated plastics. No one sample exhibited smaller changes than all other samples in all properties for all fuels and for both cyclic and continuous immersion. Results regarding weight and dimensional changes and changes in flexural properties are provided.

Report presenting a method to obtain a relatively quick approximate determination of the detailed subsonic flow of a nonviscous fluid past arbitrary turbomachine blades. The method is illustrated with examples of compressible flow in a turbine cascade and in a centrifugal compressor.

From Introduction: "The servo system considered in this report is in the latter category, due mainly to the fact its amplifier tends to saturate. An investigation of the longitudinal dynamic response of the stabilized airplane was made and the results were reported in reference 1. In this investigation it was found that when restricted to linear methods of analysis the performance of the autopilot-aircraft combination could be predicted for only the small range of operation where the elements of the autopilot operated within their linear range."