"A new mathematical technique, due to Milne-Thomson, is used to obtain an improved form of the method of Poggi for calculating the effect of compressibility on the subsonic flow past an obstacle. By means of this new method, the difficult surface integrals of the original Poggi method can be replaced by line integrals. These line integrals are then solved by the use of residue theory. In this way an equation is obtained giving the second-order effect of compressibility on the velocity of the fluid" (p. 39).

A chart is presented for the values of the coefficient in the formula for the critical compressive stress at which buckling may be expected to occur in flat rectangular plates supported along all edges and, in addition, elastically restrained against rotation along the unloaded edges. The mathematical derivations of the formulas required in the construction of the chart are given.

Report presenting an investigation to determine the performance of a conical-nose supersonic diffuser at angle of attack. The inlet had a pivoting cone which could be oriented to any of several angles independent of the angle of attack of the diffuser. Results regarding total-pressure recovery and mass-flow characteristics, cowl lip position, cone position relative to angle of attack, shadowgraphs, and contour maps are provided.

Report presenting a simplified limiting-blade-loading parameter for axial-flow-compressor blade elements derived from the application of a separation criterion used in two-dimensional boundary-layer theory to a typical suction-surface velocity distribution of a compressor blade element at design angle of attack. Results regarding two-dimensional cascade, compressor rotors, and compressor stators are provided.

Report presenting a flight investigation to study in detail the response of an airplane structure during buffeting. Measurements of acceleration on selected points were made during buffeting for two different conditions of lift coefficient and Mach number and the time histories of acceleration were studied using electrical frequency-analysis techniques. Results regarding the ground response measurements, response to buffeting excitation, verification of the measured results, and the pilot's observation of the buffeting are provided.

From Summary: "An analysis is presented of the effect of torsional flexibility on the rolling characteristics at supersonic speeds of tapered unswept wings with partial-span constant-percent-chord ailerons extending inboard from the wing tip. The geometric variables considered are aspect ratio, taper ratio, aileron span, and aileron chord. The shape of the wing-torsional-stiffness curve is assumed and the twisting moment is considered to result solely from the pressure distribution caused by aileron deflection, so that the necessity of using a successive-approximation method is avoided."

Report presenting information on landing gear applied drag loads and the nature of wheel spin-up in landing based on testing in the Langley impact basin. Particular attention is paid to the nature and variation of the coefficient of friction between the tire and runway during the wheel spin-up process. Results regarding the fundamentals of the process, comparison of maximum loads, variation of coefficient of friction, and effect of prerotation are provided.

Memorandum presenting an investigation in the supersonic blowdown tunnel to determine the effects of span and spanwise and chordwise location on the control characteristics of spoilers on a 6-percent-thick, 50 degrees sweptback wing of aspect ratio 2.5 and taper ratio of 0.625. The results of the investigation indicate that the inboard spoilers located at the rearward chordwise station produce the highest rolling-moment effectiveness.

From Summary: "An analysis of the nose-inlet shapes developed in previous investigations to represent the optimum from the standpoint of critical speed has shown that marked similarity exists between the nondimensional profiles of inlets which have widely different proportions and critical speeds. With the nondimensional similarity of such profiles established, the large differences in the critical speeds of these nose inlets must be a function of their proportions. An investigation was undertaken in the Langley 8-foot high-speed tunnel to establish the effects of nose-inlet proportions on critical Mach number to develop a rational method for the design of high-critical-speed nose inlets to meet desired requirements."

An exact solution and a closely concurring approximate energy solution are given for the buckling of an infinitely long flat plate under combined shear and transverse direct stress with edges elastically restrained against rotation. It was found that an appreciable fraction of the critical stress in pure shear may be applied to the plate without any reduction in the transverse compressive stress necessary to produce buckling. An interaction formula in general use was shown to be decidedly conservative for the range in which it is supposed to apply.

"Existing conical-flow solutions have been used to calculate the hinge-moments and effectiveness parameters of trailing-edge controls having leading and trailing edges swept ahead of the Mach lines and having streamwise root and tip chords. Equations and detailed charts are presented for the rapid estimation of these parameters. Also included is an approximate method by which these parameters may be corrected for airfoil-section thickness" (p. 937).

From Summary: "An empirically derived basis for predicting the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The concepts involved represent an initial step toward the development of a calculation technique which is generally applicable to the design of thermal ice-prevention equipment for airplane wing and tail surfaces. It is shown that sufficiently accurate estimates, for the purpose of heated-wing design, can be obtained by a few numerical computations once the velocity distribution over the airfoil has been determined. The calculation technique presented is based on results of extensive water-drop trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range."

Memorandum presenting the effect of magnesium particles of various equivalent diameters on the apparent viscosity, sedimentation ratio, and redispresibility of petroleum-stabilized magnesium-JP-4 slurries. Powders of the following equivalent diameters were investigated: 2.8, 3.8, 7.2, 9.3, 12.0, and 14.8 microns. An analysis of the experimental error and reproducibility of values of apparent viscosity, sedimentation ratio, and redispersibility of the slurries was also made.

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.

Report presenting an investigation to determine the effects of operating propellers on the longitudinal characteristics of a four-engine tractor airplane with a 40 degree swept wing with an aspect ratio of 10. Results regarding components of the lift changes due to operating propellers, components of the pitching-moment changes due to operating propellers, effect of configuration changes on the pitching-moment characteristics of the model, stick-fixed longitudinal stability of the model, reduction of adverse effects of propellers on longitudinal stability, and propulsive characteristics are provided.

"An investigation has been made to explore the possibilities of axial-flow compressors operating with supersonic velocities into the blade rows. Preliminary calculations showed that very high pressure ratios across a stage, together with somewhat increased mass flows, were apparently possible with compressors which decelerated air through the speed of sound in their blading. The first phase of the investigation was the development of efficient supersonic diffusers to decelerate air through the speed of sound" (p. 473).

Memorandum presenting an evaluation of the overall performance of a 20-inch-diameter five-stage compressor as the initial step in an investigation of the potential performance and problems associated with a high-stage-pressure ratio compressor. The overall performance was evaluated over a range of flows at equivalent tip speeds from 40 to 100 percent of design. Results regarding the overall performance, compressor-inlet conditions, compressor-discharge conditions, stagewise variation of static pressure, and performance evaluation are provided.

Report presents results of tests made 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. Various friction conditions were simulated with a rigid control system, a flexible system, and a rigid system having some backlash. For the tests, the period and damping of the simulated airplane were held constant.

The results of elevated-temperature compressive strength and creep tests of 2024-t3 (formerly 24s-t3) aluminum alloy plates supported in v-grooves are presented. The strength-test results indicate that a relation previously developed for predicting plate compressive strength for plates of all materials at room temperature is also satisfactory for determining elevated-temperature strength. Creep-lifetime results are presented for plates in the form of master creep-lifetime curves by using a time-temperature parameter that is convenient for summarizing tensile creep-rupture data. A comparison is made between tensile and compressive creep lifetime for the plates and a method that made use of isochronous stress-strain curves for predicting plate-creep failure stresses is investigated.

A series method of determining two-dimensional vortex paths is considered and applied to the computation of vortex positions behind a slender equal-span cruciform wing at any angle of bank as a function of the distance behind the trailing edge. Calculated paths are shown for four bank angles. For a bank angle of 45 degrees comparison is made with the results of a closed expression given in NACA-TN-2605. For other bank angles water-tank experiments provide qualitative comparison. Satisfactory agreement is found for a sufficient distance downstream to include most practical missile-tail positions. The interference forces on an equal-span cruciform wing are calculated for five angles of bank (including the trivial case of zero bank) from the vortex positions found by use of the series.

Report presenting an investigation of the pumping characteristics of eight conical ejectors mounted on a fuselage portion of a supersonic airplane. The diameter ratio, spacing ratio, nozzle pressure, and ejector weight flows were varied. Results regarding the ejector pumping characteristics, comparison with previous results, comparison of data for cold and hot primary flow, and ejector air-supply requirements are provided.

From Introduction: "The resulting losses in performance have been studied in a number of analyses such as that reported in reference 1."

Report presenting an analysis of the maximum power thrust-minus-drag performance of several turbojet-engine air-inlet combinations over a wide range of flight conditions. The primary objective of the analysis was to use the experimentally determined drag and total-pressure-recovery characteristics to show the range of satisfactory performance of each of several fixed-geometry inlet configurations. Results regarding the performance at 35,000 feet, inlet design considerations, speed range of efficient normal-shock inlet performance, effect of altitude on performance of the fixed-geometry system, and effect of nonstandard air on the performance of a fixed-geometry system are provided.

"Increasing demands for higher afterburner performance have required operation at progressively higher fuel-air ratios, which has increased the occurrence and intensity of screeching combustion. The onset of screech may be followed by rapid destruction of the combustor shell and other combustor parts. Because of its destructive characteristics, considerable effort has been expended to understand and eliminate screech. NACA work on the screeching combustion problem prior to 1954 is summarized herein" (p. 1195).