Report presenting an investigation of two large-scale, semispan, wing-fuselage models with the 0.25-chord line swept back 45 degrees to determine and compare the effects of partial-span, double-slotted flaps on the characteristics of a 45 degree sweptback wing with and without camber and twist. A secondary investigation was also conducted to determine the effects of various full-span, leading-edge modifications on the characteristics of the models with and without the flaps.

Report presenting testing of several turbojet engines with both constant- and variable-area nozzles to extend full-scale nozzle performance to higher exhaust-nozzle pressure ratios and to investigate the effects of constant- and variable-area nozzles on turbojet-engine operation. Results regarding the different types of nozzles are provided.

"An instrument for recording and indicating the frequency and intensity of aircraft icing conditions encountered in flight has been developed by the NACA Lewis Laboratory to obtain statistical icing data over world-wide air routes during routine airline operations. The operation of the instrument is based on the creation of a differential pressure between an ice-free total-pressure system and a total-pressure system in which small total-pressure holes vented to static pressure are allowed to plug with ice accretion. The simplicity of this operating principle permits automatic operation, and provides relative freedom from maintenance and operating problems" (p. 1).

Report discusses a procedure for estimating the wing lift coefficient for and spanwise location of the first occurrence of section stall on a swept wing. It has been modified from a method used to calculate the same information for unswept wings. The effects of split flaps, leading-edge modifications, and fences are described.

Report presenting a pilot-opinion survey conducted with a conventional fighter airplane fitted with special servo devices for varying in flight the dihedral effect, static directional stability, and directional damping. Results showing the boundaries that define satisfactory and tolerable lateral oscillatory characteristics are presented.

Memorandum presenting an investigation conducted in the 20-foot free-spinning tunnel on a 1/20-scale model of the McDonnell F2H-3 airplane. The effects of control settings and movement on the erect spin and recovery characteristics of the model were determined for the take-off condition and for the condition with full wing-tip fuel tanks installed.

"Charts giving the compressive-buckling stress coefficients for sheet panels of a shape occurring in swept-wing plan forms are presented. The panels are assumed to be a part of a continuous flat sheet divided by nondeflecting supports into parallelogram-shaped areas. The stability analysis was performed by the energy method and the results show that, over a wide range of panel aspect ratio, such panels are decidedly more stable than equivalent rectangular panels of the same area" (p. 1).

Report presenting an analysis of two x-ray absorption methods for determining small air-density gradients. One method uses a Geiger-Mueller counter for detection and the other uses photographic film for detection. Both of the methods are found to have some advantages and disadvantages.

Report presenting an investigation of the validity of the reduced-mass method of representing wing-lift effects in free-fall drop tests of landing gears by means of tests of a small landing gear in the impact basin. The free-fall drop tests with full weight produced excessive values of load factor, impact period, strut stroke, mass travel, and impact energy.

Report presenting an investigation to determine the vaporization rates of pure liquid drops vaporizing under conditions similar to those encountered in aircraft combustion systems using a heat-balance equation. Results regarding the analysis and experimental results are provided.

Note presenting an investigation of the instability of flow from two ducts that join into a common duct and of the influence of the various parameters on the phenomenon. A two-dimensional potential analysis was carried out under the assumption that the two ducts discharge into a region of constant pressure.

Note presenting experimental results that verify an analysis of errors occurring when thermocouples are used to measure the temperature of surfaces exposed at temperatures different from that of the surface. The data indicate that the electrical insulation of the wires is not effective in reducing the errors involved when the thermocouples are placed normal to the surface and exposed to the ambient fluids.

"In the analytical investigation reported herein, which was conducted in the NACA Lewis laboratory, both velocity and temperature distribution are obtained for fully developed laminar flow in tubes of gases and of liquid metals with variable fluid properties" (p. 1).

Report presenting a theoretical study of the response to gusts and stability and control characteristics of an airplane equipped with systems in which wing flaps and elevators are operated to reduce accelerations in rough air. The surfaces are actuated by an automatic control system in response to indications of an angle-of-attack vane or accelerometer.

"A summary of methods for making dynamic lateral stability and response calculations and for estimating the aerodynamic stability derivatives required for use in these calculations is presented. The processes of performing calculations of the time histories of lateral motions, of the period and damping of these motions, and of the lateral stability boundaries are presented as a series of simple straightforward steps. Existing methods for estimating the stability derivatives are summarized and, in some cases, simple new empirical formulas are presented" (p. 1).

Memorandum presenting system analyses and autopilot design procedure for a supersonic pilotless aircraft with twin jet engines. The autopilots investigated were a gyro-actuated control, a gyro-actuated control with a rate-sensing device, and an electronic-hydraulic autopilot. Results regarding the airframe and gyro-actuated control system; airframe, gyro-actuated control, and rate servo; airframe and electronic-hydraulic autopilot; and contribution of method of analysis to system design are provided.

"When porcelain enamels or vitreous-type ceramic coatings are applied to ferrous metals, there is believed to be an evolution of hydrogen gas both during and after the firing operation. At elevated temperatures rapid evolution may result in blistering while if hydrogen becomes trapped in the steel during the rapid cooling following the firing operation gas pressures may be generated at the coating-metal interface and flakes of the coating literally blown off the metal. To determine experimentally the relative importance of the principal sources of the hydrogen causing the defects, a procedure was devised in which heavy hydrogen (deuterium) was substituted in turn for regular hydrogen in each of five possible hydrogen-producing operations in the coating process" (p. 269).

"The methods of characteristics has been linearized by assuming that the flow field can be represented as a basic flow field determined by nonlinearized methods and a linearized superposed flow field that accounts for small changes of boundary conditions. The method has been applied to two-dimensional rotational flow where the basic flow is potential flow and to axially symmetric problems where conical flows have been used as the basic flows. In both cases the method allows the determination of the flow field to be simplified and the numerical work to be reduced to a few calculations. The calculations of axially symmetric flow can be simplified if tabulated values of some coefficients of the conical flow are obtained" (p. 933).

"A general method of design is developed for two-dimensional unbranched channels with prescribed velocities as a function of arc length along the channel walls. The method is developed for both compressible and incompressible, irrotational, nonviscous flow and applies to the design of elbows, diffusers, nozzles, and so forth. In part I solutions are obtained by relaxation methods; in part II solutions are obtained by a Green's function. Five numerical examples are given in part I including three elbow designs with the same prescribed velocity as a function of arc length along the channel walls but with incompressible, linearized compressible, and compressible flow" (p. 153).

In solving two-dimensional problems using Airy's stress function for multiply connected regions, the form of the function depends on the dislocations and boundary forces present. The structure of Airy's function is shown to consist of a part expressible in terms of boundary forces and a part expressible in the manner of Poincare. Meanings of the constants occurring in Poincare's expression are discussed.

"This report is a first attempt to devise a calculation method for representing the buckling behavior of cylindrical shells of variable curvature. The problem occurs, for instance, in dimensioning wing noses, the stability of which is decisively influenced by the variability of curvature. The calculation is made possible by simplifying the stability equations (permissible for the shell of small curvature) and by assuming that the curvature 1/R as a function of the arc lengths can be represented by a very few Fourier terms" (p. 1).

"A supplementary investigation has been conducted in the Langley 20-foot free-spinning tunnel of a 1/30 -scale model of the Grumman XF10F-1 airplane to determine what effect full-span slats would have on the spin-recovery characteristics of the swept-wing version of the XF10F-1 airplane, which had previously been indicated as possessing undesirable spin-recovery characteristics without slats. The effects of extended nose-wheel doors and of fairing the air-duct inlets were also determined" (p. 1).

Note presenting static and fatigue tests made on 355-T6 sand-cast plate-type aluminum-alloy specimens incorporating holes, bosses, and ribs. In the static tests, the tensile strength of the plain plate-type specimen agreed within 3 percent with the strength of separately cast test bars. Of the design details studied, the unreinforced hole was the most effective stress-raiser for fatigue lives from 10,000 to 25,000,000 cycles.

From Introduction: "The auxiliary apparatus described in this paper was constructed to meet this need and has been developed to a point where satisfactory measurements of relative drag can be obtained. In this paper, the apparatus is described and some comparisons are made between the results obtained with this apparatus and the measurements of free-fall, rocket, and supersonic-tunnel techniques."