A switching criterion for optimum performance of a third-order contractor acceleration control system having complex roots is presented. Analytical and analog-computer methods are utilized to determine this criterion. The resulting optimum transient responses are presented and compared with those of an equivalent linear system.

Note presenting the particular integrals of the second-order and third-order Prandtl-Busemann iteration equations for the flow of a compressible fluid that have been obtained by means of the method in which the complex conjugate variables are utilized as the independent variables of the analysis. The forms of the particular integrals, derived for subsonic flow, are readily adapted to supersonic flows with only a change in sign of one of the parameters of the problem.

Note presenting a general integral form of the boundary-layer equation that is derived from the Prandtl partial-differential boundary-layer equation. The general integral equation, valid for either laminar or turbulent incompressible boundary-layer flow, contains the Von Karman momentum equation, the kinetic-energy equation, and the Loitsianskii equation as special cases.

From Introduction: "Experimental results for flow in a rectangular channel with injection through a porous wall are given in reference 1. As part of the study to guide future experiments, laminar flow in a semiporous channel is investigated herein. In the present investigation, a third-order perturbation solution for laminar incompressible flow in a semiporous channel is presented."

Report presenting a comparison of wind-tunnel and flight-measured values of stability and control characteristics. Generally, wind tunnels were found to predict all trends of characteristics reasonably well, but there are differences in parameters for certain values.

Report presenting flight experiments with a freely falling model to observe the effects of steady rolling on the pitching and yawing motions of a body-tail combination. Steady rolling introduces yawing moments into the pitch oscillations and pitching motions into the yaw oscillations. Results regarding the experimental effects of steady-roll on no-roll natural frequencies, comparison of measured and experimental effects of steady rolling on the no-roll natural frequencies, and effects of roll as applied to the design of missiles are provided.

Report presenting a method for estimating the effect of blade-thickness taper on the inlet axial-velocity distribution of an entrance rotor-blade row with an axial inlet, and the influence of this velocity distribution on the alignment of the rotor blade for zero effective angle of attack. The method is developed for compressible and incompressible nonviscous fluids, and results are presented for incompressible flow into a plane, two dimensional cascade and for compressible flow into an entrance rotor-blade row with tapered blades.

Report presenting flight test data obtained from a large swept-wing bomber airplane in flight through rough air at 5,000 feet to determine the effects of vertical translation and pitching motions on the angles of attack of the wing and tail. The results indicate that the motions, particularly the pitching motions, significantly amplify the angles of attack of the wing and tail for the test airplane.

Note presenting heat-transfer rates at the stagnation point of 1.0-inch-diameter glass spherical models in shock-tube flows in air which correspond to free-flight conditions between Mach numbers of 6.4 and 13.9 with stagnation temperatures up to 7900 degrees R. The heat-transfer rates were determined from measurements of the surface-temperature change with time of a thin-film-platinum resistance thermometer.

Note presenting a model with an inverted-V transverse shape and a dead-rise angle of -20 degrees as part of a study of hydrodynamic impact loads on chine-immersed bodies. A series of fixed-trim impacts of the inverted-V model were made in smooth water over a wide range of trim and initial flight-path angles at a beam-loading coefficient of 19.15 with a few impacts at beam-loading coefficients of 27.90 and 36.07. The data are presented in tables and in figures as variations of loads and motions (in coefficient form) with time, trim angle, and flight-path angle.

Report presenting a comparison of two different methods of calculating transient temperatures for thick walls with arbitrary variation of heat-transfer coefficient and adiabatic-wall temperature.

Report presenting three compressor rotors with low-cambered 6-percent-thick NACA 65-series blade sections tested at low speeds. The tests were made at three solidities, without guide vanes or stators, over ranges of blade-setting angles and quantity-flow rates. Results regarding the efficiency and pressure-rise coefficients, variation of section turning angle with angle of attack, comparison between low-speed rotor and cascade turning angles, and carpet pots are provided.

Note presenting tables of thermal properties of stream that have been prepared in an NBS-NACA series. They include, for real gas, the compressibility factor, the density, the specific heat at constant pressure, the enthalpy, the entropy, the free-energy function, the viscosity, and the thermal conductivity.

The problem of the finite displacement and buckling, of a shallow spherical dome is investigated both theoretically and experimentally. Experimental results seem to indicate that the classical criterion of buckling is applicable to very shallow spherical domes for which the theoretical calculation was made. A transition to energy criterion for higher domes is also indicated.

From Introduction: "In the present paper, an analysis of the power-off landing maneuver is presented in which an attempt is made to consider both the aerodynamic characteristics of the airplane and the human capabilities of the pilot. In this paper, the type of pilot judgment considered is that of a pilot with previous flight experience, although not necessarily flight experience in any particular airplane under discussion."

From Summary: "This report describes a theoretical and experimental investigation of the aerodynamic mixing by a standing sound wave downstream from a continuous line source of heat."

Report presenting a comparison of studies relating to the use of Freon-12 as a substitute medium for air in aerodynamic testing and methods for predicting the aerodynamic characteristics of bodies in air. The Freon charging and recovery system for the Langley low-turbulence pressure tunnel is described.

Note presenting an investigation at low speed of the performances of circular and annular 90 degree bends of simple shapes conducted for configurations for which the cross-sectional area was constant, expanding, and contracting. Two series of transition bends were included, in which the transition occurred upstream of the bend, within the bend, and downstream from the bend. Results regarding the inlet velocity profiles, exit velocity and total-pressure profiles, and mean total-pressure-loss coefficients and exit total-pressure distortions are provided.

Report presenting a description of a pyrometer that is self-balancing and is able to replace the two conventional manual operations of the line-reversal method. A description of the operation of the pyrometer and the performance and results are provided.

Report presenting linearized-theory calculations of the drag reduction achieved by applying the first three terms of a power series for twist to flat delta wings. For the family of wings investigated, the maximum drag reduction is 2 percent in the medium sweepback range with a steady diminution in both directions. Results for the delta and arrow wings and the optimum settings are provided.

Report presenting experimental studies to evaluate some of the effects of parameters such as jet velocity, density, and turbulence level as well as jet size, on the noise generated by subsonic jets. Results regarding model jets, comparison of model and engine data, and general considerations are provided.

Report presenting a study of the wear and sliding friction properties of a number of nickel alloys operating against hardened SAE 52100 steel. The alloys included L nickel, wrought monel, cast monel, cast modified H monel, cast S monel, Invar, Ni-Resist 3, and Nichrome V.

Report presenting a study of wear and sliding friction properties of a number of nickel alloys operating against hardened SAE 52100 steel. The alloys were cast beryllium nickel, heat-treated beryllium nickel, cast Inconel, Nimonic 80, Inconel X, Refractalloy 26, and Discaloy. Results regarding the wear of unlubricated surfaces, friction of lubricated surfaces, x-ray diffraction study of wear debris, and the practical significance are provided.

Note presenting several approximate methods for calculating lift distributions at subsonic speeds, which are combined and extended to form a simple step-by-step procedure for calculating symmetric and antisymmetric lift distributions for arbitrary angle-of-attack conditions on swept and unswept wings. The results obtained by the method compare favorably with those obtained by more time-consuming theories.