From Summary: "Tests of a 1/7 size model of the Grumman XJR2F-1 amphibian were made in Langley tank no.1 to examine the landing behavior in rough water and to measure the normal and angular accelerations experienced by the model during these landings. All landings were made normal to the direction of wave advance, a condition assumed to produce the greatest accelerations. Wave heights of 4.4 and 8.0 inches (2.5 and 4.7 ft, full size) were used in the tests and the wave lengths were varied between 10 and 50 feet (70 and 350 ft, full size)."
Report discussing testing on a 42 degree swept-back wing to determine its low-speed aerodynamic characteristics in pitch and yaw at high Reynolds numbers. The main effect of increasing the Reynolds number was delayed wing stalling to higher angles of attack. Roughness on the wing leading edge also had a large adverse effect on lift, drag, and pitching-moment characteristics at higher Reynolds numbers.
A Douglas C-74 airplane, during a test dive at about 0.525 Mach number, experienced uncontrollable longitudinal oscillations sufficient to cause shedding of the outer wing panels and the subsequent crash of the airplane. Tests of a section of the horizontal tail plane from a C-74 airplane were conducted in the Ames 16-foot high-speed wind tunnel to investigate the possibility of the tail as a contributing factor to the accident. The results of the investigations of fabric-covered elevators in various conditions of surface deformation are presented in this report.
Report presenting testing of a standard turbojet engine by water injection at the inlet of the axial-flow compressor in the altitude wind tunnel. Engine performance at 7600 rpm was obtained over a wide range of water-air-pressure ratios and ram-pressure ratios. Results regarding the engine-component performance are also provided.
Report presenting a summary of the hydrodynamic qualities of interest in the normal operation of a seaplane, established over a period of years by model testing and by some knowledge of full-size operation. Results regarding longitudinal stability and control, landing stability, seaworthiness, performances, and lateral stability and control are provided.
Note presenting a method for the calculation of bending stresses due to torsion in a tapered box beam. A special taper was assumed in which all flanges, if extended, would meet at a point. The results obtained by this method were compared with experimental data obtained from tests performed on a tapered box beam.
Report presenting a determination of the tunnel-induced velocities for yawed and swept-back airfoils in a closed circular wind tunnel. Calculations were performed for elemental horseshoe vortices with one tip of the bound vortex on the tunnel axis for a range of yaw angles and bound-vortex lengths.
Report presenting calculations of the supersonic wave drag at zero lift for a series of wings with thin symmetrical biconvex sections with untapered plan forms and various angles of sweepback and aspect ratios.
Report presenting charts with coefficients for the stress analysis of a reinforced circular cylinder. They allow for the rapid determination of sheer flows and direct stresses in the sheet of a cylinder as well as the shear forces, axial forces, and bending moments in the rings. Separate charts are also given for three basic ring loadings.
Report presenting the aerodynamic characteristics of 19 isolated tail surfaces, which have been determined by wind tunnel tests. Testing was also made of rectangular airfoils of various aspect ratios with and without double end plates of various shapes. The analysis indicated that the slope of the lift curve could be predicted within 10 percent for all models by use of lifting-surface-theory equations.
A compilation of free-spinning-airplane model data on the spin and recovery characteristics of 111 airplanes is presented. These data were previously published in separate memorandum reports and were obtained from free-spinning tests in the Langley 15-foot and the Langley 20-foot free-spinning tunnels. The model test data presented include the steady-spin and recovery characteristics of each model for various combinations of aileron and elevator deflections and for various loadings and dimensional configurations. Dimensional data, mass data, and a three-view drawing of the corresponding free-spinning tunnel model are also presented for each airplane. The data presented should be of value to designers and should facilitate the design of airplanes incorporating satisfactory spin-recovery characteristics.
From Summary: "An investigation was conducted to determine the coolant-flow distribution, the cylinder temperatures, and the heat rejections of the V-1650-7 engine . The tests were run a t several power levels varying from minimum fuel consumption to war emergency power and at each power level the coolant flows corresponded to the extremes of those likely to be encountered in typical airplane installations, A mixture of 30-percent ethylene glycol and 70-percent water was used as the coolant. The temperature of each cylinder was measured between the exhaust valves, between the intake valves, in the center of the head, on the exhaust-valve guide, at the top of the barrel on the exhaust side, and on each exhaust spark-plug gasket."
A theoretical analysis of the cross-sectional temperature distribution of a water-cooled turbine blade was made using the relaxation method to solve the differential equation derived from the analysis. The analysis was applied to specific turbine blade and the studies icluded investigations of the accuracy of simple methods to determine the temperature distribution along the mean line of the rear part of the blade, of the possible effect of varying the perimetric distribution of the hot gas-to -metal heat transfer coefficient, and of the effect of changing the thermal conductivity of the blade metal for a constant cross sectional area blade with two quarter inch diameter coolant passages.
Note presenting the rolling moments of one tapered wing and two geometrically similar wings in rolling flow with the wing stationary and in straight flow with forced rotation of the wing to obtain a correlation between the two methods of testing and to determine the rolling characteristics of the wings. The results showed that for unswept wings the rolling characteristics obtained by rotation of the air agreed with those obtained by forced rotation of the wing.
"A solution based upon small-deflection theory is presented for the critical shear stress of curved rectangular panels with simply supported edges. Computed curves which cover a wide range of panel dimensions are presented; these curves are found to be in good agreement with test results. Estimated curves are also given for panels with clamped edges" (p. 1).
Report presenting a method for the calculation of elastic stresses in symmetrical disks typical of those of a high-temperature gas turbine. Illustrative examples are presented to demonstrate how to treat solid disks, disks with central holes, and disks constructed of a single material or two or more welded materials.
Report presenting an analytical treatment of the problem of determining the distribution of reaction forces among multiple plain bearings supporting a shaft subjected to rotating loads. An investigation conducted on a straight shaft operating in a seven-bearing crankcase of an aircraft engine is presented to show the importance of the hydrodynamic effect of the oil film.
Report discussing an investigation on the effect of engine skew on the directional and lateral control characteristics of a single-engine airplane with a single-rotating propeller. The estimated and test results showed an advantage to skewing the propeller, as it assists with overcoming inadequate rudder control in power-on flight and aileron control, especially with flaps deflected.
Report presenting an investigation of the effects of several spoiler arrangements on the spanwise variation of section twisting moments of a wing of NACA 230-series airfoil sections. Both plain and perforated spoilers were tested at a designated Mach and Reynolds number and force and moment measurements as well as chordwise pressure-distribution measurements at six spanwise stations were obtained.
"An analysis has been made of the lift control effectiveness of a 20-percent-chord plain trailing-edge flap on the NACA 65-210 airfoil section from section lift-coefficient data obtained at Mach numbers from 0.3 to 0.875. In addition, the effectiveness of the plain flap as a lift-control device has been compared with the corresponding effectiveness of both a spoiler and a dive-recovery flap on the NACA 65-210 airfoil section. The analysis indicates that the plain trailing-edge flap employed on the 10-percent-thick airfoil at Mach numbers as high as 0.875 retains at least 50-percent of its low-speed lift-control effectiveness, and is sufficiently effective in lateral control application, assuming a rigid wing, to provide adequate airplane rolling characteristics" (p. 1).
An analysis has been made of the lift-control effectiveness of a 20-percent-chord plain trailing-edge flap on the NACA 65-210 airfoil section from section lift-coefficient data obtained at Mach numbers from 0.3 to 0.875. In addition, the effectiveness of the plain flap as a lift-control device has been compared with the corresponding effectiveness of both a spoiler and a dive-recovery flag on the INCA 65-210 airfoil section.
Report presenting wind-tunnel testing to determine the low-speed lift, drag, and pitching-moment characteristics of a 40 degree sweptback wing with high-lift and stall-control flaps and a fuselage with a fineness ratio of 10.2 to 1. Low, medium, and high-wing-fuselage combinations were tested at high Reynolds numbers. Results regarding the high-lift and stall-control flaps and wing-fuselage combinations are provided.
Wing was tested with full-span, partial-span, or split flaps deflected 60 Degrees and without flaps. Chordwise pressure-distribution measurements were made for all flap configurations.. Peak values of maximum lift coefficient were obtained at relatively low free-stream Mach numbers and, before critical Mach number was reached, were almost entirely dependent on Reynolds Number. Lift coefficient increased by increasing Mach number or deflecting flaps while critical pressure coefficient was reached at lower free-stream Mach numbers.
"The analogy between the distribution of stresses in flat stiffened panels and the distribution of electric current in a ladder-type resistance network is used as the theoretical basis of an electrical computer for the rapid solution of shear-lag problems. The computer, consisting of variable resistors and multiple-current sources, is described; and typical examples are given of its use. The analogy is extended to include bolted-joint problems, and an example is given also" (p. 1).
The aerodynamic characteristics of seven unswept tapered wings were determined by calculation from two-dimensional data and by wind-tunnel tests in order to demonstrate the accuracy of the calculations and to show some of the effects of aspect ratio, taper ratio, and root thickness-chord ratio. The characteristics were calculated by the usual application of the lifting-line theory which assumes linear section lift curves and also by an application of the theory which allows the use of nonlinear lift curves. A correction to the lift for the effect of chord was made by using the Jones edge-velocity factor. The wings had aspect ratios of 8, 10, and 12, taper ratios of 2.5 and 3.5, and NACA 44-series airfoils.
Report presenting tests to determine the damping in roll and aileron rolling effectiveness of three wings with different degrees of sweepback. The results showed that the values of damping in roll decreased with increasing sweepback. The rolling effectiveness of the aileron of the sweptback wing was found to be predicted with fair accuracy from static aileron-rolling-moment tests and wing-damping tests.
Sinusoidal waves excited by random disturbances have been observed in the laminar boundary layer of a rotating disk at Reynolds numbers in a narrow range below the Reynolds number of transition. Their frequency was found to be approximately a constant times the velocity of the disk. The velocity of the waves at the radius of 11 inches was determined and found to be 0.2 linear velocity of the disk in a downstream direction, making an angle of approximately 14 degrees with the outward drawn radius vector.
Report presenting flight tests to evaluate an elevator stick-force bungee and engine tilt as methods of improving the longitudinal-control characteristics of an existing airplane. The stick-force bungee was found to be the simplest and most effective modification.
Report presenting testing of a double-hinged horizontal tail on a small low-speed airplane to determine the longitudinal stability and control characteristics. The flying characteristics of the airplane equipped with the double-hinged horizontal tail surface were generally satisfactory. The primary effect of removal of the elevator seal was a decrease in the elevator effectiveness.
Report presenting power-off flight tests in the free-flight tunnel to determine the dynamic stability characteristics of an airplane model with a 42 degree sweptback wing of aspect ratio 5.9 and taper ratio 0.5. The static-stability and wing-stall characteristics of the model were also determined. Results regarding force tests, flow surveys, and flight tests are provided.
Report presenting a flight investigation in the free-flight tunnel to determine the severity of the dynamic stability and control problems associated with 62 degrees sweepback. In addition to the flight tests, force tests and tuft tests were made to determine the static-stability and wing-stall characteristics, and calculations were made to determine the boundary of zero damping of the lateral oscillation.
Report presenting part of the results obtained to determine the effects of compressibility at high Mach numbers on a model of the Bell XS-1 transonic research airplane. General trends that can be qualitatively analyzed for level-flight Mach numbers up to 0.93 are given. Results regarding force characteristics and a comparison of results with wing-flow investigation are also provided.
Report discusses the development and testing of a rocket-propelled test vehicle to investigate aerodynamic control effectiveness at high subsonic, transonic, and supersonic speeds. Modifications to the section thickness and wing sweepback to improve performance are also described. A description of the vehicle, instrumentation, accuracy, and evaluation of testing results is included.
In accordance with a request of the Bureau of Aeronautics, Navy Department, tests were performed in the Langley 20-foot free-spinning tunnel to determine the spin and recovery characteristics of a 1/24 scale model of the Grumman XTB3F-1 airplane. The airplane is a two-place, midwing torpedo bomber equipped with a tractor propeller and an auxiliary jet engine. The effect of control setting and movement on the erect and inverted spin and recovery characteristics of the model were determined for the normal loading. Brief tests with mass extended slightly along the fuselage were also made, however, in order to determine the effect of such a mass variation on elevator effectiveness. Tests were performed to determine the size of emergency spin-recovery tail and wing-tip parachutes required for satisfactory recovery by parachute action alone. The investigation also included emergency pilot-escape tests and tests to determine the rudder pedal and elevator stick forces necessary to move the rudder and elevator for recovery.
Note presenting a determination of friction coefficients for three constant-area vaneless diffusers, used in conjunction with a centrifugal impeller, from static- and total-pressure surveys taken at several radii and from the usual overall measurements of temperature, pressure, and air flow. The average value of the friction coefficient through the entire diffuser was approximately 50 percent higher than that for fully developed turbulent flow in smooth pipes.
Report presenting an investigation of the forward-flight performance characteristics of a typical single-rotor helicopter equipped with main and tail rotors. Testing occurred over a range of tip-speed ratios and thrust coefficients. Results regarding the fuselage effects and rotor characteristics are provided.
"The basic principles of the control of TL engines are developed on the basis of a quantitative investigation of the behavior of these behavior under various operating conditions with particular consideration of the simplifications permissible in each case. Various possible means of control of jet engines are suggested and are illustrated by schematic designs" (p. 1).
Report presenting tests of an NACA 4-(5)(08)-03 two-blade propeller in the 8-foot high-speed tunnel for blade angles of 45 and 60 degrees extending the Mach number range from that of previous tests of the propeller up to Mach number 0.913. When the forward speed was increased from a low value to a forward Mach number of 0.90, the loss in peak efficiency was found to be not more than 47 percent.
Report presenting a set of equations based on the first mode of wing bending for determining the dynamic responses of an airplane wing structure as induced by gusts. The representation of the airplane is such that the aerodynamic damping of the vibratory motion of the wing is separate from that of the vertical motion of the airplane as a whole.
Report presenting the results of testing in the transonic range of four flutter airfoils attached to a freely falling body. Failures of the airfoils were metered and recorded in order to determine the Mach numbers and altitudes of failure.
Note presenting tests of 12 wing-fuselage combinations employing triangular and 18 employing elliptical fuselages made in the NACA variable-density tunnel as part of a program to investigate at large values of Reynolds number the aerodynamic effects of wing-fuselage interference. The parameters of combination covered in the investigation were the vertical position of the wing with respect to the fuselage axis, wing shape, and wing-fuselage juncture shape.
Report presenting an investigation made in the 300 mph 7- by 10-foot tunnel to determine at low speed in the longitudinal stability characteristics of a 60 degree sweptback, tapered, low-drag wing of aspect ratio 2.55. The results show undesirably large changes in the longitudinal stability characteristics of the 60 degree sweptback wings.
From Summary: "An investigation has been conducted to determine whether three-dimensional flows may be utilized in axial-flow fan and compressor rotors so that the spanwise load distribution may be varied to obtain high pressure rise. Two rotors, one with approximately uniform and one with solid-body downstream tangential-velocity distributions, were designed and tested at the design blade angle."
Note presenting a wind-tunnel investigation of the effect of span, spanwise location, and chordwise location of spoilers on the lateral control characteristics of an unflapped semispan wing equipped with a simple spoiler with a projection 5 percent of the chord. The chordwise investigation involved moving a 50-percent-semispan spoiler from the 50-percent-chord station to the 80-percent-chord station. Results regarding the plain-wing characteristics, spanwise investigation, and chordwise investigation are provided.
Note presenting an investigation to determine the stability and control characteristics of an airplane model with a skewed wing in the free-flight tunnel. Flight tests, force tests, and damping-in-roll tests were made on the model with the wing set at angles of skew from 0 to 60 degrees. The investigation was of an exploratory nature and was intended to provide only a preliminary and qualitative indication of whether such a design could be flown.
Note presenting an investigation of three centrifugal impellers, the same except for angular blade curvature, to determine the effect of the distribution of blade loading on impeller performance. Results regarding impeller efficiency, energy addition and pressure ratio, flow characteristics, and operating range are provided.
Report presenting data for alloys that can resist temperatures up to 1350 degrees Fahrenheit so that they can be used in gas turbines. The chromium-base alloys currently have certain severe limitations in their present state of development. However, considerable progress has been made in overcoming these difficulties and further improvement seems possible.
Note presenting an application of the iterative interference method to three problems concerning the design of cascades. The three problems considered include the determination of the shape and setting of thin blades with a prescribed type of vortex distribution, determination of the shape and setting of thin blades with certain prescribed types of pressure distributions, and determination of the blade setting for a cascade of given airfoil shape and solidity.
Powered models of three different flying boats were landed in oncoming wave of various heights and lengths. The resulting motions and acceleration were recorded to survey the effects of varying the trim at landing, the deceleration after landing, and the size of the waves. One of the models had an unusually long afterbody. The data for landing with normal rates of deceleration indicated that the most severe motions and accelerations were likely to occur at some period of the landing run subsequent to the initial impact.
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