Report presenting an experimental investigation of the effect of oil viscosity on bearing operation characteristics using a 75-millimeter-bore cylindrical-roller inner-race-riding cage-type bearing. Results regarding DN value, oil flow, viscosity, the combination of DN and oil flow, oil inlet temperature, and improvements to cooling correlation theory are provided.

Note presenting a theoretical solution obtained for the problem of the compressive buckling of flat rectangular Metalite type sandwich plates with simply supported loaded edges and clamped unloaded edges. The solution is based on the general small-deflection theory for flat sandwich plates developed in a previous NACA report. Results regarding the stability criterion and buckling curves, correction for plasticity, and a comparison with theoretical results are provided.

From Summary: "Results of an analytical and a sea-level experimental investigation of a turbojet engine with proportional speed control are presented."

Report presenting the use of the similarity law for steady hypersonic flow about slender shapes as extended to nonsteady flows. The aerodynamic forces and moments are correlated for related shapes by means of this law. The motions of related bodies in free flight could be correlated using the hypersonic similarity parameters and additional parameters relating the inertial properties of the bodies and air densities.

"The corrosion resistance of unprotected magnesium-zinc-zirconium alloy ZK60A was determined in a marine atmosphere and in tidewater. The unprotected alloy was so rapidly attacked in tidewater that it would be of no practical value in applications subject to wetting by sea water. In the marine atmosphere the rate of corrosion was much less and the alloy should give good service if adequately protected" (p. 1).

Report presenting some preliminary calculations for airplanes of current design in order to determine the proper angles of sideslip in order to design ideal vertical tails. Existing simplified calculations for determining these values are not generally applicable to airplanes of current design, but a new solution is proposed. Results for two different airplanes are provided and suggestions for adjusting calculated sideslip values are provided.

Report presenting transient data from approximate step and sinusoidal disturbances of fuel flow on a turbojet engine operated at one constant simulated altitude and flight condition. Results regarding coefficients of differential equations, Fourier representation, frequency response, transient analysis, and a comparison of the various analytical methods are provided.

Report presenting results of axial-load fatigue tests on notched specimens of three sheet materials: 24S-T3 and 75S-T6 aluminum alloys and normalized SAE 4130 steel. Tests were run at four levels of nominal mean stress.

"Several common methods for curve fitting a set of data by least squares are described and evaluated. The methods are evaluated by applying them to an example taken from aerodynamics: the problem of calculating the stability parameters of an airplane from flight data. There are other points considered: application of the methods to minimization problems other than curve fitting and the question of convergence to a mere stationary point as opposed to convergence to a minimum" (p. 1).

Report presenting supersonic profiles of minimum pressure drag for a given thickness ratio and a given area created by using non-linear pressure relation and compared with minimum-drag profiles found by linearized theory. The parameters determining the airfoil shape for a given thickness ratio found by linear and nonlinear theory are presented in graphs as a function of the base pressure coefficient.

Report presenting flame speeds for methane-air, propane-air, and ethylene-air mixtures at -73 degrees Celsius and for ethylene-air mixtures at -132 degrees Celsius. The data extend the curves of maximum flame speed against initial mixture temperature previously established for the range from room temperature to 344 degrees Celsius. Results regarding velocity profile of the nozzle, flame speeds based on the outer edge of shadow, and a comparison of experimental and theoretical data are provided.

"The report presenting information on the stress problems in the analysis of pressurized cabins of high-altitude aircraft not met with in other fields of stress analysis related to aircraft. The material may be roughly divided into shell problems and plate problems, the former being concerned with the curved walls of the cabin or pressure vessel and the latter being concerned with small rectangular panels of its walls, framed by stiffeners, but not necessarily plane" (p. 1).

Note presenting a determination of the reciprocal equations relating the lift and moment acting on an airfoil due to harmonic oscillations in compressible flow to the indicial lift and moment functions for a pitching airfoil. Two functions are required to completely describe the lift or moment on the airfoil: one is used for describing the effects due to angular position of the airfoil while the other is used for describing the effects due to pitching velocity.

Report presenting an investigation in the free-spinning tunnel to study the behavior in descent of hemispherical and quasi-conical parachutes, some with symmetrical canopy modifications and all with a right circular cylinder suspended by one end below the parachute. Results indicated that a lateral flight component during descent could be obtained by using a circular cutout in the side of the canopy of a hemispherical parachute and a large slit between two panels of a quasi-conical parachute.

"Reverse flow theorems in aerodynamics are shown to be based on the same general concepts involved in many reciprocity theorems in the physical sciences. Reciprocal theorems for both steady and unsteady motion are found as a logical consequence of this approach. No restrictions on wing plan form or flight Mach number are made beyond those required in linearized compressible-flow analysis" (p. 253).

A low-speed wind-tunnel investigation was made to determine the lateral control characteristics of a series of untapered low-aspect-ratio wings. Sealed flap ailerons of various spans and spanwise locations were investigated on unswept wings of aspect ratios 1.13, 1.13, 4.13, and 6.13; and various projections of 0.60-semispan retractable ailerons were investigated on the unsweptback wings of aspect ratios 1.13, 2.13, and 4.13 and on a 45 degree sweptback wing. The retractable ailerons investigated on the unswept wings spanned the outboard stations of each wing; whereas the plain and stepped retractable ailerons investigated on the sweptback wing were located at various spanwise stations. Design charts based on experimental results are presented for estimating the flap aileron effectiveness for low-aspect-ratio, untapered, unswept.

A review of existing publications on wind-tunnel corrections is followed by an approximate method for determining the corrections due to model and wake displacement and to lift. Relations are investigated for fuselages and wings of various spans in closed circular tunnels. A comparison is made between the computations and the tests in the DVL high-speed wind tunnel.

"Graphs and formulas are given with the aid of which all the aerodynamic coefficients required for computing the lateral dynamic stability can be determined. A number of numerical examples are given for obtaining the stability derivatives and solving the characteristic-stability equation. Approximate formulas are derived with the aid of which rapid preliminary computations may be made and the stability coefficients corrected for certain modifications of the airplane" (p. 1).

The dynamic characteristics of turbojet engine with variable exhaust nozzle area were investigated over a range of altitudes and flight Mach numbers. These characteristics generalize to standard static level condition. Data resulting from approximate step disturbances in either manipulated variable suggested functional relationships from which functions can be derived. The constants of the transfer functions are listed for five combinations of engine speed and exhaust nozzle area. The minimum data needed to completely define the transfer functions were: experimentally determined dynamic characteristics, such as engine time constant and initial rise ratio, resulting from either manipulated variable; static characteristics determined from steady-state performance curves.

A study of two 20 degrees half-angle, low mass-flow ratio conical supersonic inlets with cone boundary-layer bleed was made on a 16-inch ram-jet engine in the Lewis 8- by 6-foot supersonic wind tunnel. A greater stable subcritical range of operation was obtained with the bleed inlets than with the corresponding inlet without boundary-layer bleed. The drag added by the bleed system was small.

The performance of MIL-F-5624A fuels, grades JP-3 and JP-4, was investigated in an axial-flow turbojet engine over a range of altitude conditions of 10,000 to 55,000 feet. Examination of the fuel flow, combustion efficiency, and net thrust specific fuel consumption showed the grade JP-4 fuel to be slightly inferior to the grade JP-3 fuel, although the altitude ignition limits were essentially equal for the two fuels over a range of flight Mach numbers and fuel-inlet temperatures.

Some general properties of isoenergetic rotational conical fields are determined. For such fields, provided the physical parameters of the fluid flow are known on a conical reference surface, it being understood that they satisfy certain imposed conditions, it is shown how to construct the hodographs in the various meridional semiplanes, as the envelope of either the tangents to the hodographs or of the osculatory circles.

The dependence of the maximum incremental velocities and air forces on a circular cowling on the mass flow and the angle of attack of the oblique flow is determined with the aid of pressure-distribution measurements. The particular cowling tested had been partially investigated in NACA TM 1327.

"The measurements of part V (reference 1) of this series of reports, which concerned comparatively long ring profiles, are supplemented by measurements on shorter rings as they are used for shrouded propellers and cowlings of ring-shaped radiators. Mass-flow coefficients and profile drags are given. Furthermore, it has to be determined how far the potential theory describes the flow phenomenon with sufficient accuracy and whether the present theory for the calculation of thin annular profile yields useful profile forms and is suitable for determination of the mass flow for thick profiles" (p. 1).