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Aerodynamic characteristics at high speeds of related full-scale propellers having different blade-section cambers

Description: Wind-tunnel tests of a full-scale two-blade NACA 10-(10)(08)-03 (high camber) propeller have been made for a range of blade angles from 20 degrees to 55 degrees at airspeeds up to 500 miles per hour. The results of these tests have been compared with results from previous tests of the NACA 10-(3) (08)-03 (low camber) and NACA 10-(5)(08)-03 (medium camber) propellers to evaluate the effects of blade-section camber on propeller aerodynamic characteristics.
Date: 1957?
Creator: Maynard, Julian D & Salters, Leland B , Jr
Item Type: Report
Partner: UNT Libraries Government Documents Department

An analysis of the effects of aeroelasticity on static longitudinal stability and control of a swept-wing airplane

Description: A theoretical analysis has been made of the effects of aeroelasticity on the static longitudinal stability and elevator angle required for balance of an airplane. The analysis is based on the familiar stability equation expressing the contribution of wing and tail to longitudinal stability. Effects of wing, tail, and fuselage flexibility are considered. Calculated effects are shown for a swept-wing bomber of relatively high flexibility.
Date: 1957?~
Creator: Skoog, Richard B
Item Type: Report
Partner: UNT Libraries Government Documents Department

Approximate analysis of effects of large deflections and initial twist on torsional stiffness of a cantilever plate subjected to thermal stresses

Description: An approximate analysis of the nonlinear effects of initial twist and large deflections on the torsional stiffness of a cantilever plate subjected to a nonuniform temperature distribution is presented. The Von Karman large-deflection equations are satisfied through the use of a variational principle. The results show that initial twist and applied moments can have significant effects on the changes in stiffness produced by nonuniform heating, particularly in the region of the buckling temperature difference. Results calculated by this approximate analysis are in satisfactory agreement with measured torsional deformations and changes in natural frequency. (author).
Date: May 15, 1957
Creator: Heldenfels, Richard R & Vosteen, Louis F
Item Type: Report
Partner: UNT Libraries Government Documents Department

Attenuation in a shock tube due to unsteady-boundary-layer action

Description: A method is presented for obtaining the attenuation of a shock wave in a shock tube due to the unsteady boundary layer along the shock-tube walls. It is assumed that the boundary layer is thin relative to the tube diameter and induces one-dimensional longitudinal pressure waves whose strength is proportional to the vertical velocity at the edge of the boundary layer. The contributions of the various regions in a shock tube to shock attenuation are indicated. The method is shown to be in reasonably good agreement with existing experimental data.
Date: 1957
Creator: Mirels, Harold
Item Type: Report
Partner: UNT Libraries Government Documents Department

Basic considerations in the combustion of hydrocarbon fuels with air

Description: Basic combustion research is collected, collated, and interpreted as it applies to flight propulsion. The following fundamental processes are treated in separate chapters: atomization and evaporation of liquid fuels, flow and mixing processes in combustion chambers, ignition and flammability of hydrocarbon fuels, laminar flame propagation, turbulent flames, flame stabilization, diffusion flames, oscillations in combustors, and smoke and coke formation in the combustion of hydrocarbon-air mixtures. Theoretical background, basic experimental data, and practical significance to flight propulsion are presented.
Date: January 1, 1957
Creator: Barnett, Henry C & Hibbard, Robert R
Item Type: Report
Partner: UNT Libraries Government Documents Department

Bodies of revolution having minimum drag at high supersonic airspeeds

Description: Approximate shapes of nonlifting bodies having minimum pressure foredrag at high supersonic airspeeds are calculated. With the aid of Newton's law of resistance, the investigation is carried out for various combinations of the conditions of given body length, base diameter, surface area, and volume. In general, it is found that when body length is fixed, the body has a blunt nose; whereas, when the length is not fixed, the body has a sharp nose. The additional effect of curvature of the flow over the surface is investigated to determine its influence on the shapes for minimum drag. The effect is to increase the bluntness of the shapes in the region of the nose and the curvature in the region downstream of the nose. These shape modifications have, according to calculation, only a slight tendency to reduce drag. Several bodies of revolution of fineness ratios 3 and 5, including the calculated shapes of minimum drag for given length and base diameter and for given base diameter and surface area, were tested at Mach numbers from 2.73 to 6.28. A comparison of theoretical and experimental foredrag coefficients indicates that the calculated minimum-drag bodies are reasonable approximations to the correct shape.
Date: January 1, 1957
Creator: Eggers, A J , Jr; Resnikoff, Meyer M & Dennis, David H
Item Type: Report
Partner: UNT Libraries Government Documents Department

Cloud-droplet ingestion in engine inlets with inlet velocity ratios of 1.0 and 0.7

Description: The paths of cloud droplets into two engine inlets have been calculated for a wide range of meteorological and flight conditions. The amount of water in droplet form ingested by the inlets and the amount and distribution of water impinging on the inlet walls are obtained from these droplet-trajectory calculations. In both types of inlet, a prolate ellipsoid of revolution represents either part or all of the forebody at the center of an annular inlet to an engine. The configurations can also represent a fuselage of an airplane with side ram-scoop inlets. The studies were made at an angle of attack of 0 degree. The principal difference between the two inlets studied is that the inlet-air velocity of one is 0.7 that of the other. The studies of the two velocity ratios lead to some important general concepts of water ingestion in inlets.
Date: January 1, 1957
Creator: Brun, Rinaldo J
Item Type: Report
Partner: UNT Libraries Government Documents Department

Comparison of several methods for obtaining the time response of linear systems to either a unit impulse or arbitrary input from frequency-response data

Description: Several methods of obtaining the time response of Linear systems to either a unit impulse or an arbitrary input from frequency-response data are described and compared. Comparisons indicate that all the methods give good accuracy when applied to a second-order system; the main difference is the required computing time. The methods generally classified as inverse Laplace transform methods were found to be most effective in determining the response to a unit impulse from frequency-response data of higher order systems. Some discussion and examples are given of the use of such methods as flight-data-analysis techniques in predicting loads and motions of a flexible aircraft on the basis of simple calculations when the aircraft frequency response is known.
Date: January 1, 1957
Creator: Donegan, James J & Huss, Carl R
Item Type: Report
Partner: UNT Libraries Government Documents Department

Correlation, evaluation, and extension of linearized theories for tire motion and wheel shimmy

Description: An evaluation is made of the existing theories of a linearized tire motion and wheel shimmy. It is demonstrated that most of the previously published theories represent varying degrees of approximation to a summary theory developed in this report which is a minor modification of the basic theory of Von Schlippe and Dietrich. In most cases where strong differences exist between the previously published theories and summary theory, the previously published theories are shown to possess certain deficiencies. A series of systematic approximations to the summary theory is developed for the treatment of problems too simple to merit the use of the complete summary theory, and procedures are discussed for applying the summary theory and its systematic approximations to the shimmy of more complex landing-gear structures than have previously been considered. Comparisons of the existing experimental data with the predictions of the summary theory and the systematic approximations provide a fair substantiation of the more detailed approximate theories.
Date: January 1, 1957
Creator: Smiley, Robert F
Item Type: Report
Partner: UNT Libraries Government Documents Department

Determination of longitudinal stability and control characteristics from free-flight model tests with results at transonic speeds for three airplane configurations

Description: A test technique and data analysis method has been developed for determining the longitudinal aerodynamic characteristics from free-flight tests of rocket-propelled models. The technique makes use of accelerometers and an angle-of-attack indicator to permit instantaneous measurements of lift, drag, and pitching moments. The data, obtained during transient oscillations resulting from control-surface disturbances, are analyzed by essentially nonlinear direct methods (such as cross plots of the variation of lift coefficient with angle of attack) and by linear indirect methods by using the equations of motion for a transient oscillation. The analysis procedure has been set forth in some detail and the feasibility of the method has been demonstrated by data measured through the transonic speed range on several airplane configurations. It was shown that the flight conditions and dynamic similitude factors for the tests described were reasonably close to typical full-scale airplane conditions.
Date: January 1, 1957
Creator: Gillis, Clarence L & Mitchell, Jesse L
Item Type: Report
Partner: UNT Libraries Government Documents Department

Determination of vortex paths by series expansion technique with application to cruciform wings

Description: 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.
Date: January 1, 1957
Creator: Alksne, Alberta Y
Item Type: Report
Partner: UNT Libraries Government Documents Department

An evaluation of four experimental methods for measuring mean properties of a supersonic turbulent boundary layer

Description: Surveys were made through a turbulent boundary layer on a flat plate by means of a pitot probe, an x-ray densitometer, and hot-wire and cold-wire probes. Results from these surveys were analyzed to determine (a) the reliability of the basic data and hence the methods by which they were obtained, and (b) how well the actual distributions of properties in the boundary layer compare with those commonly assumed in semiempirical and theoretical analyses. All surveys were made at the same longitudinal station on the flat plate. The tests were conducted in a an 8- by 8-inch supersonic nozzle. The free-stream Mach number was 3.03 and the Reynolds number was approximately 210,000 based on boundary-layer thickness.
Date: January 1, 1957
Creator: Nothwang, George J
Item Type: Report
Partner: UNT Libraries Government Documents Department

Experimental and predicted longitudinal and lateral-directional response characteristics of a large flexible 35 degree swept-wing airplane at an altitude of 35,000 feet

Description: Measured and predicted dynamic response characteristics of a large flexible swept-wing airplane to control surface inputs are presented for flight conditions of 0.6 to 0.85 Mach number at an altitude of 35,000 feet. The report is divided into two parts. The first part deals with the response of the airplane to elevator control inputs with principal responses contained in a band of frequencies including the longitudinal short-period mode and several symmetrical structural modes. The second part deals with the response of the airplane to aileron and rudder control inputs with principal responses contained in a band of frequencies including the dutch roll mode, the rolling mode, and three antisymmetrical structural modes.
Date: January 1, 1957
Creator: Cole, Henry A , Jr; Brown, Stuart C & Holleman, Euclid C
Item Type: Report
Partner: UNT Libraries Government Documents Department

Exploratory investigation of boundary-layer transition on a hollow cylinder at a Mach number of 6.9

Description: The Reynolds number for transition on the outside of a hollow cylinder with heat transfer from the boundary layer to the wall has been investigated at a Mach number of 6.9 in the Langley 11-inch hypersonic tunnel. The type of boundary layer was determined from impact-pressure surveys and optical viewing. From a correlation of results obtained from various sources at lower Mach numbers (in the range 2.0 to 4.5) and data from the present tests with variable Reynolds number per inch, leading-edge thickness and free-stream Reynolds number per inch appear to be important considerations in flat-plate transition results. At a given Mach number, it appears that the Reynolds number based on leading-edge thickness is an important parameter that must be considered in comparisons of flat-plate transition data from various installations.
Date: January 1, 1957
Creator: Bertram, Mitchel H
Item Type: Report
Partner: UNT Libraries Government Documents Department

Far Noise Field of Air Jets and Jet Engines

Description: An experimental investigation was conducted to study and compare the acoustic radiation of air jets and jet engines. A number of different nozzle-exit shapes were studied with air jets to determine the effect of exit shape on noise generation. Circular, square, rectangular, and elliptical convergent nozzles and convergent-divergent and plug nozzles were investigated. The spectral distributions of the sound power for the engine and the air jet were in good agreement for the case where the engine data were not greatly affected by reflection or jet interference effects. Such power spectra for a subsonic or slightly choked engine or air jet show that the peaks of the spectra occur at a Strouhal number of 0.3.
Date: January 1, 1957
Creator: Callaghan, Edmund E & Coles, Willard D
Item Type: Report
Partner: UNT Libraries Government Documents Department

Flight and analytical methods for determining the coupled vibration response of tandem helicopters

Description: Chapter one presents a discussion of flight-test and analysis methods for some selected helicopter vibration studies. The use of a mechanical shaker in flight to determine the structural response is reported. A method for the analytical determination of the natural coupled frequencies and mode shapes of vibrations in the vertical plane of tandem helicopters is presented in Chapter two. The coupled mode shapes and frequencies are then used to calculate the response of the helicopter to applied oscillating forces.
Date: January 1, 1957
Creator: Yeates, John E , Jr; Brooks, George W & Houbolt, John C
Item Type: Report
Partner: UNT Libraries Government Documents Department

Flight investigation of the effectiveness of an automatic aileron trim control device for personal airplanes

Description: A flight investigation to determine the effectiveness of an automatic aileron trim control device installed in a personal airplane to augment the apparent spiral stability has been conducted. The device utilizes a rate-gyro sensing element in order to switch an on-off type of control that operates the ailerons at a fixed rate through control centering springs. An analytical study using phase-plane and analog-computer methods has been carried out to determine a desirable method of operation for the automatic trim control.
Date: January 1, 1957
Creator: Phillips, William H; Kuehnel, Helmut A & Whitten, James B
Item Type: Report
Partner: UNT Libraries Government Documents Department

Induced velocities near a lifting rotor with nonuniform disk loading

Description: A method is given for converting known uniformly loaded rotor induced velocities to correspond with arbitrary axisymmetric nonuniform disk load distributions. Numerical results for two specific distributions are given in chart form. Symmetry relations and relations between radial disk loading and wake velocities are developed. Experimental flow measurements are presented and compared with theory. Reasonable agreement is shown in the forward part of the flow when nonuniform loading is assumed, but far behind the rotor the flow is more like that of a wing.
Date: January 1, 1957
Creator: Heyson, Harry H & Katzoff, S
Item Type: Report
Partner: UNT Libraries Government Documents Department

Influence of Alloying upon Grain-Boundary Creep

Description: Grain-boundary displacement, occurring in bicrystals during creep at elevated temperature (350 degrees c), has been measured as a function of the copper content (0.1 to 3 percent) in a series of aluminum-rich aluminum-copper solid-solution alloys. The minimums in stress and temperature, below which grain-boundary motion does not occur, increase regularly with the copper content as would be expected if recovery is necessary for movement. Otherwise, the effects, if any, of the copper solute upon grain-boundary displacement and its rate are too small for identification by the experimental technique employed. It was shown, additionally, that grain-boundary displacement appears regular and proceeds at a constant rate if observed parallel to the stress axis, whereas the motion is seen to occur in a sequence of surges and the rate to diminish with time if the observations are made perpendicular to the stress axis.
Date: January 1, 1957
Creator: Rhines, F N; Bond, W E & Kissel, M A
Item Type: Report
Partner: UNT Libraries Government Documents Department

Influence of Hot-Working Conditions on High-Temperature Properties of a Heat-Resistant Alloy

Description: The relationships between conditions of hot-working and properties at high temperatures and the influence of the hot-working on response to heat treatment were investigated for an alloy containing nominally 20 percent molybdenum, 2 percent tungsten, and 1 percent columbium. Commercially produced bar stock was solution-treated at 2,200 degrees F. to minimize prior-history effects and then rolled at temperatures of 2,200 degrees, 2,100 degrees, 2,000 degrees, 1,800 degrees, and 1,600 degrees F. Working was carried out at constant temperature and with incremental decreases in temperature simulating a falling temperature during hot-working. In addition, a few special repeated cyclic conditions involving a small reduction at high temperature followed by a small reduction at a low temperature were used to study the possibility of inducing very low strengths by the extensive precipitation accompanying such properties. Most of the rolling was done in open passes with a few check tests being made with closed passes. Heat treatments at both 2,050 degrees and 2,200 degrees F. subsequent to working were used to study the influence on response to heat treatment.
Date: January 1, 1957
Creator: Ewing, John F & Freeman, J W
Item Type: Report
Partner: UNT Libraries Government Documents Department

Investigation of downwash, sidewash, and Mach number distribution behind a rectangular wing at a Mach number of 2.41

Description: An investigation of the nature of the flow field behind a rectangular wing of circular arc cross section has been conducted in the Langley 9-inch supersonic tunnel. Pitot- and static-pressure surveys covering a region of flow behind the wing have been made together with detailed pitot surveys throughout the region of the wake. In addition, the flow direction has been measured by means of a weathercocking vane. Theoretical calculations have been made to obtain the variation of both downwash and sidewash with angle of attack by using the superposition method of Lagerstrom, Graham, and Grosslight. In addition, the effect of wing thickness on the sidewash with the wing at 0 degree angle of attack has been evaluated.
Date: January 1, 1957
Creator: Adamson, David & Boatright, William B
Item Type: Report
Partner: UNT Libraries Government Documents Department

An investigation of four wings of square plan form at a Mach number of 6.9 in the Langley 11-inch hypersonic tunnel

Description: The results of pressure-distribution and force tests of four wings at a Mach number of about 6.9 and a Reynolds number of 0.98 x 10(6) in the Langley 11-inch hypersonic tunnel are presented. The wings had a square plan form, a 5-percent-chord maximum thickness, and diamond, half-diamond, wedge, and half-circular sections.
Date: January 1, 1957
Creator: Mclellan, Charles H; Bertram, Mitchel H & Moore, John A
Item Type: Report
Partner: UNT Libraries Government Documents Department

An investigation of single- and dual-rotation propellers at positive and negative thrust, and in combination with an NACA 1-series D-type cowling at Mach numbers up to 0.84

Description: An investigation has been made to determine the aerodynamic characteristics of the NACA 4-(5)(05)-041 four-blade, single-relation propeller and the NACA 4-(5)(05)-037 six- and eight-blade, dual-rotation propellers in combination with various spinners and NACA d-type spinner-cowling combinations at Mach numbers up to 0.84. Propeller force characteristics, local velocity distributions in the propeller planes, inlet pressure recoveries, and static-pressure distributions on the cowling surfaces were measured for a wide range of blade angles, advance ratios, and inlet-velocity ratios. Included are data showing: (a) the effect of extended cylindrical spinners on the characteristics of the single-rotation propeller, (b) the effect of variation of the difference in blade angle setting between the front and rear components of the dual-rotation propellers, (c) the negative- and static-thrust characteristics of the propellers with 1 series spinners, and (d) the effects of ideal- and platform-type propeller-spinner junctures on the pressure-recovery characteristics of the single-rotation propeller-spinner-cowling combination.
Date: January 1, 1957
Creator: Reynolds, Robert M; Samonds, Robert I & Walker, John H
Item Type: Report
Partner: UNT Libraries Government Documents Department

Investigation of the compressive strength and creep lifetime of 2024-T3 aluminum-alloy plates at elevated temperatures

Description: 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.
Date: January 1, 1957
Creator: Mathauser, Eldon E & Deveikis, William D
Item Type: Report
Partner: UNT Libraries Government Documents Department