"This document contains reproductions of technical papers on some of the most recent research results on aircraft loads, flutter, and structures from the NACA laboratories. These papers were presented by members of the staff of the NACA laboratories at the Conference held at the Langley Aeronautical Laboratory March 5, 6, and 7, 1957. The primary purpose of this Conference was to convey to contractors of the military services and others concerned with the design of aircraft these recent research results and to provide those attending an opportunity to discuss the results" (p. 6).

"Comparisons are made of experimental and theoretical zero-lift wave drag for several nose shapes, wing-body combinations, and models of current airplanes at Mach numbers up to 1.0. The experimental data were obtained from tests in the Ames 6- by 6-foot supersonic wind tunnel and at the NACA Wallops Island facility. The theoretical drag was found by use of linear theory utilizing model area distributions" (p. 1).

Report presenting results from pitot-static and hot-wire anemometer surveys at low speed of the flow over a thin, sharp-edge airfoil which simulated a flat plate. The primary purpose was to obtain detailed measurements of the flow associated with the so-called thin-airfoil type of stall. Results regarding the preliminary tests, pressure distributions, mean flow measurements, velocity fluctuation measurements, and observations and measurements of the flow in the immediate vicinity of the leading edge are provided.

Report presenting an investigation in the high-speed hydrodynamics facility to determine whether planing lift coefficient of a flat-bottom planing surface remains constant with increasing speed at the high towing speeds obtainable. The generally accepted assumption that there is no effect of speed on the lift coefficient of positive-pressure lifting surfaces is valid at least up to 170 fps.

Report presenting an investigation at Mach number 2.40 to determine the aerodynamic characteristics of plain overhang balances on flap-type controls. Testing was performed on a two-dimensional wing with three trailing-edge flaps with balance lengths of 38, 60, and 82 percent of the flap chord. The effect of wing-flap gap size were investigated for the flap with 38 percent balance.

Report presenting an experimental investigation in the flutter research tunnel on the oscillating forces and moments on a two-dimensional wing equipped with an oscillating circular-arc spoiler.

From Summary: "A simple inelastic collision model of meteor-atmosphere interaction is used and analytic relations for velocity, deceleration, size, and relative luminous magnitude of meteors are derived and expressed in dimensionless parametric form. The analysis is compared with available quantitative observations of meteor behavior and it is indicated that a large fraction of the atmospheric bombardment energy is used in eroding meteor material. The erosion from large, high-speed vehicles as they traverse the high-altitude, free-molecule portion of the atmosphere is calculated, on the assumption that the vaporization process is similar to that which occurs for meteors."

Note presenting an investigation of the vacuum and hydrogen brazing of four heat-resistant alloys with two types of high-temperature brazing alloy. The effect of time at two brazing temperatures on the 1200 degrees Fahrenheit shear strength of joints and on the base-metal properties was studied. Shear specimens of all four base alloys brazed in hydrogen with box types of brazing alloy exhibited erratic joint coverage by the brazing alloys.

An investigation of the stability and control of a high-wing transport vertical-take-off airplane with four engines during constant-altitude transitions from hovering to normal forward flight was conducted with a remotely controlled free-flight model. The model had four propellers distributed along the wing with the thrust axes in the wing chord plane. The wing could be rotated to 90 degrees incidence so that the propeller thrust axes were vertical for hovering flight. An air jet at the rear of the fuselage provided pitch and yaw control for hovering and low-speed flight.

Note presenting the impact properties of titanium carbide base cermets, some high-temperature alloys, and the intermetallic NiAl, obtained at room and elevated temperatures up to 1750 degrees Fahrenheit. The impact energies of cermets were found to increase with increased amounts of metallic binder. Results regarding the variables of drop test, impact resistance of cermets, high-temperature alloys, and comparison of cermets and alloys are provided.

From Summary: "The low-speed stalling characteristics of a large number of airfoil sections have been correlated with Reynolds number and a single airfoil ordinate near the leading edge as the correlation parameters. The correlation is appropriate only to airfoils without high-lift devices in flows of very low turbulence and with aerodynamically smooth surfaces."

Note presenting a study of the fluctuating lift of a rigid wing in turbulent flow and the power spectra of the lift and turbulent fluctuations. Using these measurements, the aerodynamic admittance of the wing was obtained. Results regarding the infinite wing and aspect-ratio effect are provided.

Report presenting experimental and theoretical research on flow separation associated with steps, bases, compression corners, curved surfaces, shock-wave boundary-layer reflections, and configurations producing leading-edge separation. Results were obtained from pressure-distribution measurements, shadowgraph observations, high-speed motion pictures, and oil-film studies.

Report presenting comparative low-speed cascade tests of the National Gas Turbine Establishment of Great Britain axial-flow compressor blade sections at a range of air-inlet angles and a solidity of 1.0 using the porous wall technique. Results regarding a comparison of performance characteristics of the NGTE and NACA axial-flow compressor blade sections and a comparison of NGTE and NACA low-speed cascade tests of the NGTE 10C4/30C50 section are provided.

Temperature - fuel-flow and temperature-area feedback control systems were investigated as means of controlling tailpipe gas temperature of a turbojet engine during transient operation in the high-speed region. Proportional-plus-integral control was used in both systems, but in the temperature-area control system it was necessary to add nonlinear components to the basic proportional-plus-integral control to provide satisfactory transient response to a desired step increase in temperature. Time integral of temperature-error functions were used as criteria for determining optimum transient response.

A summary is given of the background and present status of pure-planing theory. Data for models having sharp chines have been obtained for a rectangular flat plate and two V-bottom surfaces having constant angles of dead rise of 20 degrees and 40 degrees and also for rectangular-flat-plate surfaces having very slightly rounded chines. The theory presented in NACA Technical Note 3233 for a rectangular flat plate is revised and extended to include triangular flat plates planing with base forward and V-shaped prismatic surfaces having a constant angle of dead rise, horizontal chine flare, or vertical chine strips. The agreement between the results calculated by the proposed theory and the experimental data is satisfactory for engineering calculations of lift and center-of-pressure location.

Report presenting an investigation of the spray formed by two impinging liquid jets over a range of jet velocities in order to determine the characteristics of that particular method of atomization. Results regarding the spray patterns, velocity range, effect of fluid properties on spray pattern, effects of jet velocity and geometry on fully developed sprays, and discussions of the single-jet characteristics are provided.

Report presenting an experimental investigation at three Mach numbers of a series of tail combinations consisting of a triangular vertical tail attached symmetrically to a triangular horizontal tail to determine the lateral force, yawing moment, and rolling moment due to sideslip. The results indicated that the lateral-force derivative and yawing-moment derivative were predicted satisfactorily with the method used with the exception of when leading edges approach a sonic condition.

An investigation has been conducted to compare the performance of NACA 65-series compressor blades in two-dimensional cascade with that in an axial flow compressor. Blade pressure distributions were obtained by the use of a mercury-seal pressure-transfer device. The comparison indicated that cascade data accurately predicted the turning angle and blade pressure distribution obtained in the compressor at design conditions.

Optimum proportional-plus-integral control settings for speed - fuel-flow control, determined by minimization of integral criteria, correlated well with analytically predicted optimum settings. Engine response data are given for a range of control settings around the optimum. An inherent nonlinearity in the speed-area loop necessitated the use of nonlinear controls. Response data for two such nonlinear control schemes are presented.

Report discussing an investigation to determine the effect of spin on the aerodynamic characteristics of the Army Ordnance Corps 60-millimeter T-24 mortar shell with several tail-fin configurations. Tests were performed at several airspeeds, speeds of rotation, and angles of attack. Under all test conditions, the models were statistically stable and the yawing moment increased with speed of rotation at higher angles of attack.

Wedge and scoop air inlet performance and thrust minus drag comparisons at free stream in supersonic wind tunnel test.

Memorandum presenting a single J33 combustor and an experimental tubular combustor incorporating a fuel vaporizer as operated with gaseous hydrogen at temperatures slightly above the boiling point of the fuel. Data were obtained to explore possible effects of the fuel temperature on combustor performance and on the control and measurement of fuel flow.

Memorandum presenting the performance of a scoop-type inlet on the bottom of a body of revolution at several Mach numbers and angles of attack. The investigation included a study of the effects of altering the approach surface ahead of the inlet, extending the boundary-layer splitter plate, and bleeding air at the throat and exit of the diffuser.