Report presenting an investigation of spontaneous ignition temperatures from 1 to 9 atmospheres in the air for n-heptane, isooctane, benzene, JP-4, and JP-5 fuels. Time lags before ignition were measured at each pressure for all fuels. Results regarding the effect of pressure, general comparisons of all fuels, and ignition-lag experiments are provided.

Report presenting a wind-tunnel investigation to provide data for the study of the effects of operating propellers on the longitudinal characteristics of a four-engine tractor airplane configuration with a wing of 40 degrees of sweepback and an aspect ratio of 10. Coefficients of lift, longitudinal force, pitching moment, propeller thrust, and propeller power are presented in tabular form for various values of advance ratio at constant angles of attack.

"The results of an experimental investigation of the strength of multiweb beams with corrugated webs are reported. Included in the investigation were two types of connection between the web and the skin. A comparison between the structural efficiency of corrugated-web and channel-web multiweb beams is presented, and it is shown that, for a considerable range of the structural index, corrugated-web beams can be built which are structurally more efficient than channel-web beams" (p. 1).

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.

Report presenting mass-flow tables for ratios of specific heats for the entire range of critical velocity ratio. The tables enable a quick and accurate determination of the integrated average specific mass flow across a region where the end-point velocities are known. A numerical example using the tables is also provided.

From Summary: "Solutions of mainstream flow patterns for three-dimensional, laminar, incompressible thin-boundary-layer flows (over flat or slightly curved surfaces) having similarity with respect to stationary polar coordinates in the plane of the surface are derived. The solutions are summarized in a table."

Report presenting an application of airfoil design methods to a series of related turbine-blade profiles to satisfy the conditions of inlet flow angle and turning angle encountered in the usual range of turbine operation. Satisfactory flow conditions were obtained in all of the blade passages tested. Results regarding the turning angles, wake losses, surface pressure distributions, critical Mach numbers, application of compressibility corrections to low-speed tests, and selection of design camber are provided.

Linear-theory values of the supersonic pressure field and wave drag of nonlifting bumped and indented bodies of revolution are presented and compared with the corresponding properties of a smooth body. The comparisons indicate that relatively small surface irregularities cause large pressure disturbances and changes in wave drag. The interference drag produced by bumps and indentations is discussed and a correction for the curvature of the characteristics is applied.

Note presenting laminar burning velocity measured at pressures of 1 atmosphere and below and critical boundary velocity gradient for flashback at pressures below 1 atmosphere over a range of compositions for hydrogen-air burner flames. Pressure exponents of 0.23 for burning velocity and 1.35 for flashback velocity gradient was found. Results regarding blowoff and general stability loop, burning velocity, relations among various combustion properties, and reaction order from pressure exponents are provided.

Note presenting a description of a new class of frequency-selective shock absorbers called band-pass shock absorbers, which were conceived as a means of overcoming some of the limitations of conventional shock absorbers. The shock absorbers may be designed to isolate two bodies from each other over certain ranges of exciting frequencies or rates of load application while coupling them over the remainder of the frequency spectrum.

Note presenting an investigation to determine the effects of wing position on the low-speed static longitudinal and static lateral stability of airplane models with fuselages of square and rectangular cross sections and unswept and 45 degree sweptback surfaces. The results of the investigation indicated that at low angles of attack, the complete unswept models with the wing in the high position were more stable or least longitudinally unstable. The results also showed that wing-fuselage interference causes an increase in effective dihedral angle when the wing is moved to the high position.

Report presenting three modifications to the leading-edge region of the NACA 64A010 airfoil section, which were designed and tested two-dimensionally at both low and high subsonic speeds. The modifications increased the low-speed maximum lift coefficient of the symmetrical reference section, largely by increasing the angle of attack at which stall occurred.

The interaction of bearing and tensile loads on the creep behavior of joints was studied. A specimen was designed for this study which possessed some of the general features of pin and rivet joint connections and an apparatus was constructed to apply both bearing and tensile loads to the joint model. Deformation measurements were made by use of a photogrid printed on the joint model.

Report presenting an investigation of jet flaps in the 300 mph 7- by 10-foot tunnel on an unswept, untapered wing with an aspect ratio of 8.4 and a thickness of 16.7 percent. Results regarding jet flap, jet-augmented trim flap, jet-augmented plain flap, and estimated thrust required for steady flight of an airplane with the jet-flap system are provided.

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 generalized expressions and charts which depend on the shock Mach number, initial state of the gas, and an enthalpy parameter for the temperature, pressure, density, and flow velocity behind a shock wave.

Results are presented of an investigation made to determine the internal friction and fatigue strength of commercially pure 1100 aluminum under repeated stressing in torsion at various temperatures and stress levels in an effort to find if there exists any correlation between internal friction and fatigue characteristics.

From Summary: "Experimental measurements have been made of the zero-lift drag rise at transonic speeds of a family of triangular plan form wings of varying thickness and aspect ratio mounted on a cylindrical body. Together with the transonic similarity parameters, the results of the tests are used to define the range of applicability of the transonic area rule for wings of triangular plan form. The significance of the test results is discussed."

Report discussing a flight investigation of rocket-powered models of a tailless triangular-wing airplane configuration was made through the transonic and low supersonic speed range at the Langley Pilotless Aircraft Research Station at Wallops Island, Va. An analysis of the aerodynamic coefficients, stability derivatives, and flying qualities based on the results obtained from the successful flight tests of three models is presented.

Report presenting an investigation in the low-turbulence pressure tunnel to determine the effect of size and location of a sandpaper type of roughness on the Reynolds number for transition. Transition was observed by means of a hot-wire anemometer at various chordwise stations for each position of roughness.

A simple method for calculating the characteristics of the Dutch roll motion of an airplane is obtained by arranging the lateral equations of motion in such form and order that an iterative process is quickly convergent. Primary effects of variation of the important stability derivatives on the period and damping can be seen more clearly from the iterative method than from the fourth-order characteristic equation.

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 a wind-tunnel investigation at low speeds to determine the effect of aspect ratio and end plates on the aerodynamic characteristics of an unswept and untapered wing equipped with jet flaps deflected 85 degrees and operating with momentum coefficients as high as 17.5.

Report presenting calculations of the correlation functions and power spectra of the rolling and yawing moments on an airplane wing due to the three components of continuous random turbulence. Specific numerical calculations are made for a pair of correlation functions given by simple analytic expressions which fit available experimental data.