"Slender-body theory is used in conjunction with late theory to analyze the static aeroelastic-divergence behavior of low-aspect-ratio rectangular wings of constant thickness when chordwise deformations are considered. In the analysis, the spanwise variation of the deflection is restricted to a parabola but the chordwise variation is allowed complete freedom. Results show the variation of the divergence speed and mode shape with the aspect ratio" (p. 1).

Report presenting a method for calculating the expected number of maxima or minima of a random process with non-Gaussian frequency distribution from the statistical moments of the process and its first two derivatives. The effects of skewness and kurtosis can also be calculated provided the required moments are known.

From Summary: "Three-dimensional views are presented of the first three natural vibration mode shapes of ten cantilever-wing models. A table of normalized deflections at six spanwise and five chordwise stations is included for each mode. These mode shapes were measured by a rather unique experimental technique using grains of sand as accelerometers."

Report presenting a wind-tunnel investigation at low speed to determine the effects of fuselage nose length and a canopy on the static longitudinal and lateral stability characteristics of a complete model with a fuselage with square cross sections, a 45 degree sweptback wing, and a 45 degree sweptback horizontal tail.

A number of nozzles which use the mixing interference of adjacent jets for noise suppression were investigated. Reductions in sound power of nearly 70 percent (5 db) with thrust losses of 1 percent were achieved. A method of calculating the limiting frequency affected by this type of suppression nozzle, that is , multiple-slot nozzles, is presented. Data are shown which indicate that further large reductions in sound power are not likely with mixing-interference nozzles.

The effect of spanwise variations in gust intensity on the power spectrum directly due to atmospheric turbulence is calculated for several analytic approximations to the correlation function or power spectra of atmospheric turbulence, for several spanwise weighing functions (span loadings), and for various angles of sweepback.

Report presenting cross-grain specimens made of 7075-T6 aluminum-alloy extrusion were subjected to repeated axial loads until fatigue cracks of various lengths were formed. The specimens were subjected to static tests to determine the residual static strength.

Report presenting an investigation to determine the effect of heat transfer on the peak pressure rise associated with the separation of a turbulent boundary layer on a body of revolution at Mach number 1.61. The results indicated that little or no effect of heat transfer on the shock angles associated with separation on the peak pressure rise required to separate a turbulent boundary layer.

Note presenting tests on a power control system by means of a ground simulator to determine the effects of various combinations of valve friction and stick friction on the ability of the pilot to control the system. The results show that, when valve friction was present in a rigid system, the introduction of stick friction was beneficial in that it restored some of the quality lost because of the valve friction. Results regarding the rigid control system, flexible control system, and control system with backlash are provided.

Note presenting equilibrium temperatures and heat-transfer rates for 0.00015- and 0.00030-inch diameter tungsten wires normal to the flow throughout a range of Mach numbers and Reynolds numbers. For the range of variables, equilibrium temperature of the hot wire is characterized by constant recovery factor for subsonic Mach numbers but constant equilibrium to total temperature ratio for supersonic Mach numbers. Results regarding the equilibrium temperature tests and heat-transfer tests are provided.

The 100-hour rupture strengths of Inconel X, Inconel 700, Incoloy 901, Refractaloy 26, and R-235 at 1200 and 1350 F. in both the annealed and heat-treated conditions were determined. Inconel 700 had the highest rupture strength at both temperatures; Incoloy 901 was second strongest at 1200 F, and R-235 second strongest at 1350 F. With the exception of Incoloy 901, ductility was low. Photomicrographs show that fractures are through the grain boundaries. Results are compared with published data for other sheet alloys and bar stock.

"Stability limits for laminar and turbulent hydrogen-air burner flames were measured as a function of pressure, burner diameter, and composition. On the basis of a simple flame model, turbulent flashback involved a smaller effective penetration distance than laminar flashback. No current theoretical treatment predicts the observed pressure and diameter dependence of laminar and turbulent blowoff" (p. 1).

A double set of turning vanes was carried inside the jet tailpipe. To produce reverse thrust, the tailpipe opens into two side sections and the turning vanes move outward to form a V-shaped cascade, which deflects the exhaust-gas flow. Forward and reverse net thrust were measured over a range of engine speeds with the airplane stationary. Taxi tests were made to determine the comparative stopping distances using wheel braking and reverse thrust separately, and a combination of both. The effect of turning-vane spacing on thrust-reverser performance was determined by scale-model tests using unheated air.

Report presenting methods for determining the linearized subsonic flow about symmetrical, nonlifting wing-body combinations. A comparison of theory and experiment is made for two 45 degree sweptback wings in combination with basic Sears-Haack bodies of revolution and in combination with basic bodies indented according to the transonic area rule.

The sound pressures radiating from the exhaust streams of two convergent-divergent and one convergent nozzle were measured. Exit diameters were 1.206 in. for the expanded nozzle and 0.625 in. for the convergent nozzle. The results are presented in a series of contour maps of overall and fine 1/3-octave-band sound pressures. The location of the source of the noise in each 1/3-octave band in the frequency range of 30 to 16,000 cps and the total power radiated were determined and compared with those of subsonic jets.

From Summary: "A semivaneless turbine stator designed to eliminate blade wakes and secondary-flow accumulations of boundary-layer air was built and tested. Performance of this stator was evaluated with static pressures measured in the vaneless section and surveys of total pressure and flow angle made at the stator exit. Results are presented in terms of theoretical and experimental velocities and flow angles, boundary-layer parameters, and contours of total-pressure loss across the stator."

Results from an experiment indicated that the ignition of hydrogen-oxygen gas mixtures at a pressure of 1 atmosphere in a 2-foot-diameter duct resulted in detonation combustion. The use of a duct for the rocket exhaust may permit a reduction of the noise output and allow for the cooling and chemical treatment of the exhaust gases. The use of water jets and water sprays distributed through the duct did not prevent a detonation but did reduce peak pressure.

Note presenting the results of a detailed study of the flutter characteristics of four representative aircraft wings. During the investigation, eight important parameters of each wing were varied and the effects of mass, inertia, pitching spring, and location of a concentrated mass for all four wings and several sweepback angles.

Note presenting testing of geometrically related structural joints representing typical skin-stringer cross sections under radiant heating to simulate the effects of aerodynamic heating. The presence of an interface was found to have a significant effect on the temperature distribution in all geometries tested and thus must be considered in temperature calculations. Interface conductance values were computed for each of the 15 fabricated specimens.

A discontinuous variation of coefficients of the differential equation describing the linear control system before nonlinear elements are added is studied in detail. The nonlinear feedback is applied to a second-order system. Simulation techniques are used to study performance of the nonlinear control system and to compare it with the linear system for a wide variety of inputs. A detailed quantitative study of the influence of relay delays and of a transport delay is presented.

Note presenting an analysis and comparison of atmospheric turbulence as experienced by rocket-powered models and temperature lapse-rate data obtained from rawinsonde soundings in 38 cases by using an assumed temperature lapse-rate stability boundary as a basis for comparison. A limited correlation has been obtained which indicates that atmospheric conditions classified as being unstable will generally be turbulent, but a marginal or stable classification does not necessarily indicate smooth air.

Report presenting the zero-lift damping-in-roll derivative as experimentally determined through high subsonic, transonic, and low supersonic speeds by a torque-nozzle forced-roll technique utilizing rocket-propelled models. Data from the the investigations is used to show the effects of wing plan form and airfoil section and the effects of aeroelasticity. Results regarding sweepback, aspect ratio, taper ratio, thickness ratio, airfoil-section shape, delta wings, increase in number of semispan wings from three to four, aeroelastic effects, and comparisons with theory are provided.

Note presenting tables of Mach number functions for a range of specific-heat ratios compiled for use at the Lewis laboratory for solving fluid-flow problems.

The proximity of the ground to an annular nozzle can result in thrust augmentation of up to 50 percent. The magnitude of thrust augmentation was a function of ground-to-nozzle distance, nozzle configuration, and nozzle pressure ratio. With a conventional circular nozzle a thrust reduction of 15 to 40 percent due to ground effect was obtained. The degree of thrust reduction was primarily a function of nozzle pressure ratio and ground-to-nozzle distance.