National Advisory Committee for Aeronautics (NACA) - 337 Matching Results
Search Results
- A method for studying the hunting oscillations of and airplane with a simple type of automatic control
- Report presenting a method for predicting the amplitude and frequency, under certain simplifying conditions, of the hunting oscillations of an automatically controlled aircraft with lag in the control system or in response of the aircraft to the controls. Formulas are given expressing the response to a variation of signal in terms of response to a unit signal.
- The effect of compressibility on two-dimensional tunnel-wall interference for a symmetrical airfoil
- Summary: The effective change in the velocity of flow past a wing section, caused by the presence of wind-tunnel walls, is known for potential flow. This theory is extended by investigation of the two-dimensional compressible flow past a thin Rankine Oval. It is shown that for a symmetrical section at zero angle of attack the velocity increment due to the tunnel walls in the incompressible case must be multiplied by the factor 1/1-M^2 to take account of compressibility effects. The Mach number, M, corresponds to conditions in the wind-tunnel test section with the model removed (p. 1.).
- Emergency Measures for Increasing the Range of Fighter Airplanes
- "An analysis was made to show the relative effectiveness of streamline external fuel tanks, a fuel tank in the form of a wing mounted in a biplane position, and auxiliary wing panels attached at the wing tips to increase the span as temporary means for increasing the range of a fighter-type airplane. Figures and charts for the various devices considered show the results of calculations of range, duration of flight, and take-off distance for both land-base and carrier operation. The results indicated that the wing-tip extensions were the most promising of the devices considered" (p. 1).
- Fuel-Evaporation Loss as Determined by the Change in the Specific Gravity of the Fuel in an Aircraft Fuel Tank
- Report discusses the results of an investigation to determine the feasibility of using the change in the specific gravity of fuels in aircraft fuel tanks to measure fuel-vaporization loss. Six fuels were tested via fuel-distillation tests and simulated-flight tests. An equation based on the specific gravity of the fuel is also described.
- Profile-Drag Coefficients of Conventional and Low-Drag Airfoils as Obtained in Flight
- "The results of flight investigations of the profile drag of several carefully finished conventional and low-drag airfoils are presented. The results indicated that in all cases lower profile-drag coefficients were obtained with the low-drag than with the conventional airfoils over the range of lift coefficient tested and that, for comparable conditions of lift coefficient and Reynolds number, the low-drag airfoils may have profile-drag coefficients which are at least 27 percent lower than the profile-drag coefficients of the conventional airfoils" (p.1).
- An Experimental Investigation of Rectangular Exhaust-Gas Ejectors Applicable for Engine Cooling
- Report presenting an experimental investigation of rectangular exhaust-gas ejector pump to provide data that would serve as a guide to the design of ejector applications for aircraft engines with marginal cooling. With a decrease in the quantity of air pumped and an increase in the length of an ejector, the ejector pressure rise increases to optimum values. Results regarding straight ejectors, diffuser ejectors, curved ejectors, ejector aspect ratio, divided ejectors, multistage ejectors, and nozzle-exit effects are provided.
- An Investigation of a Thermal Ice-Prevention System for a C-46 Cargo Airplane 5: Effect of Thermal System on Airplane Cruise Performance
- Report presenting flight tests conducted to evaluate the effect of a thermal ice prevention system on the aerodynamic performance of a C-46 cargo airplane. The installation of the thermal ice-prevention system was found to reduce the indicated airspeed by about 6 miles per hour. Results regarding the overall performance change resulting from the installation of the thermal system, reduction of power attributed to heat-exchanger exhaust-gas back pressure, reduction of power attributed to the internal and external drag of the thermal system, and the additional airplane gross weight attributed to the thermal system are provided.
- An Investigation of a Thermal Ice-Prevention System for a C-46 Cargo Airplane 6: Dry-Air Performance of Thermal System at Several Twin- and Single-Engine Operating Conditions at Various Altitudes
- Report presenting flight tests to establish the dry-air-performance characteristics of a thermal ice-prevention system at various operating conditions and altitudes. Results regarding twin-engine tests and single-engine tests of characteristics such as skin temperatures and location of heating are provided.
- Spin Tests of Two Models of a Low-Wing Monoplane to Investigate Scale Effect in the Model Test Range
- Note presenting testing performed on scale models of a modern low-wing monoplane in the 15-foot free-spinning wind tunnel. Results are presented in the form of charts that afford a direct comparison between the spins of the two models for a number of different conditions. The results indicate that, within the range of Reynolds numbers used in the present investigation, such factors as difficulty of ballasting and testing are more important in determining proper model size than the changes in scale effect likely to result from the use of different sizes of models.
- Least-Work Analysis of the Problem of Shear Lag in Box Beams
- The distribution of stress in the cover sheets of thin-wall box beams is analyzed, with regard to the effect of shear deformation in the cover sheets, by the method of least work. Explicit results are obtained for a number of representative cases that show the influence of the following factors on the stress patterns. General conclusions are drawn from the results obtained. Among them the most important one appears to be the fact that the shear-lag effect depends primarily on several tow qualities.
- Wind-tunnel investigation of an NACA 23012 airfoil with several arrangements of slotted flaps with extended lips
- "An investigation was made in the NACA 7- by 10-foot wind tunnel to determine the effect of slot-lip location on the aerodynamic section characteristics of an NACA 23012 airfoil with a 30-percent-chord slotted flap. Tests were made with slot lips located at 90 and 100 percent of the airfoil chord and with two different flap shapes. The results are compared with a slotted flap previously developed by the National advisory Committee for Aeronautics with a slot lip located at 83 percent of the airfoil chord. The extension of the slot lip to the rear increased the section lift and pitching-moment coefficients" (p. 1).
- Properties of low-aspect-ratio pointed wings at speeds below and above the speed of sound
- "Low-aspect-ratio wings having pointed plan forms are treated on the assumption that the flow potentials in planes at right angles to the long axis of the airfoils are similar to the corresponding two-dimensional potentials. For the limiting case of small angles of attack and low aspect ratios the theory brings out the following significant properties: (1) The lift of a slender, pointed airfoil moving in the direction of its long axis depends on the increase in width of the sections in a downstream direction. Sections behind the section of maximum width develop no lift. (2) The spanwise loading of such an airfoil is independent of the plan form and approaches the distribution giving a minimum induced drag. (3) The lift distribution of a pointed airfoil travelling point-foremost is relatively unaffected by the compressibility of the air below or above the speed of sound. A best of a triangular airfoil at a Mach number of 1.75 verified the theoretical values of lift and center of pressure" (p. 1).
- Square Plate With Clamped Edges Under Normal Pressure Producing Large Deflections
- "A theoretical analysis is given for the stresses and deflections of a square plate with clamped edges under normal pressure producing large deflections. Values of the bending stress and membrane stress at the center of the plate and at the midpoint of the edge are given for center deflections up to 1.9 times the plate thickness. The shape of the deflected surface is given for low pressures and for the highest pressure considered" (p. 1).
- Current Status of Longitudinal Stability
- The problems of static and dynamic longitudinal stability both at high speeds and at low speeds are discussed and data are presented which indicate recent progress made in the solution of these problems.
- A Restricted List of Aircraft Materials Research Projects
- This report contains a selected list of Government sponsored research projects on related aircraft materials in effect during the calendar year 1947. Information is contained on titles, description, sponsoring and conducting agencies.
- Factors Affecting Lateral Stability and Controllability
- The effects on dynamic lateral stability and controllability of some of the important aerodynamic and mass characteristics are discussed and methods are presented for estimating the various stability parameters to be used in the calculation of the dynamic lateral stability of airplanes with swept and low-aspect-ratio wings.
- Investigation of a Systematic Group of NACA 1-Series Cowling With and Without Spinners
- Report presenting an investigation to study cowling-spinner combinations based on the NACA 1-series nose inlets and to obtain systemic data for one family of approximately ellipsoidal spinners. 11 of the spinners were also tested in various combinations with 9 NACA open-nose cowlings, which were also tested without spinners. Results regarding flow over spinners, internal flow, external flow over cowling, critical Mach number characteristics, envelope values, and cowling section are provided.
- An exploratory investigation of the relative merits of split and chord-extension flaps on a 45 degrees swept-back wing
- Report presenting a wind-tunnel investigation to explore the merits of split and chord-extension flaps on a 45 degree sweptback wing. Testing occurred at low speed on a semispan model equipped with split flaps of 60 and 90-percent span and a full-span chord-extension flap. Results regarding split flaps, chord-extension flap, and resultant lift coefficients after balancing pitching-moment coefficients are provided.
- Ice protection of turbojet engines by inertia separation of water 1: alternate-duct system
- Aerodynamic and icing investigations of internal water-inertia separation inlets designed to prevent automatically entrance of large quantities of water into a turbojet engine in icing conditions was conducted on a one-half scale model. A simplified analytical approach to the design of internal water-inertia separation inlets is included. Results show that in order to be effective in preventing screen and guide-vane icing for an inlet of this type, a ram-pressure recovery of 75 percent was attained at design inlet-velocity ratio in an icing condition. For nonicing operation, ram-pressure recovery is comparable to direct-ram inlet.
- Free-Flight Investigation of the Rolling Effectiveness of a Wing-Spoiler Arrangement at High Subsonic, Transonic, and Supersonic Speeds
- Report presenting an investigation of the rolling effectiveness of a wing-spoiler arrangement using a rocket-propelled test vehicle in free flight. The configuration investigated in the report is likely not optimum and indicates a need for further exploration.
- An Investigation of the Downwash Behind a High-Aspect-Ratio Wing With Various Amounts of Sweep in the Langley 8-Foot High-Speed Tunnel
- Report presenting measurements of downwash angles at points at two vertical positions at the probable tail location behind a high-aspect-ratio wing with an NACA 65-210 section with no sweep and 30 degrees and 45 degrees of sweepback and sweepforward in conjunction with a fuselage.
- Current Status of Longitudinal Stability
- Report presenting an investigation of the problems of static and dynamic longitudinal stability both at high speeds and low speeds as well as information about progress that has been made to solve these problems. The incorporation of large amounts of sweepback on both the wing and horizontal tail can improve the rate of trim changes and stability. Longitudinal stability has been attained for configurations with a sweep angle of 45 degrees with stall-control devices, but experimental proof is needed for these devices.
- Theoretical performance of some rocket propellants containing hydrogen, nitrogen, and oxygen
- From Summary: "Theoretical performance data including nozzle-exit temperature, specific impulse, volume specific impulse and composition, temperature, and mean molecular weight of reaction products based on frozen equilibrium and isentropic expansion are presented for 13 propellant combinations at reaction pressure of 300 pounds per square inch absolute and expansion ratio of 20.4. On basis of maximum specific impulse alone, five fuels had the following order for any given oxidant: liquid hydrogen, hydrazine, liquid ammonia, and either hydrazine hydrate or hydroxylamine. Three oxidants with a given fuel had the following order: liquid ozone, liquid oxygen, and 100-percent hydrogen peroxide."
- Visual Observations of the Shock Wave in Flight
- "This report presents the results of pilot observations and photographs of the compression shock wave on the wing of an airplane in flight. A detailed description of the test conditions necessary and the procedure to be following in producing the visible shock are presented. The pilot's observations of the occurrence of an oscillating shock wave and its possible relationship with the airplane buffeting are also presented" (p. 1).
- Preliminary Investigation at a Mach Number of 1.9 and a Reynolds Number of 2,200,000 of Three Ailerons Applicable to the Bell XS-2 Airplane Design
- Report presenting testing of a 42.7 degree sweptback tapered wing with three types of ailerons tested at a Mach number of 1.9 and a Reynolds number of 2,200,000; the wing geometry was similar to that of an XS-2 airplane. The purpose of the investigation was to determine the effectiveness of ailerons at these specified flight characteristics. Results regarding the aerodynamic characteristics of the wing are also provided.
- Preliminary Survey of the Aircraft Fire Problem
- Memorandum presenting a review of information relating to aircraft fires to determine what new or further research might lead to a substantial reduction of the aircraft fire hazard in flight and following crashes. An examination of fuels, lubricants, and hydraulic fluids as inflammable liquids is presented, together with possible sources of ignition under the general categories of hot surfaces, electric sparks and arcs, flames, and hot gases.
- Qualitative Measurements of Relative Flap Effectiveness at Transonic Speeds on a Series of Five Thin Airfoils With 25-Percent-Chord Flaps and Various Amounts of Sweepback
- Report presenting testing on a series of five flat plate models of aspect ratio 2.0 with 25-percent-mean-aerodynamic-chord flaps at a range of Mach numbers in order to investigate the effect of sweepback on flap effectiveness.
- Free-flight investigation of 16-inch diameter supersonic ram-jet unit
- Report presenting an investigation of a series of 16-inch-diameter ramjet engine in free flight in order to determine the performance of ramjet units in flight at supersonic speeds and to study methods for improving the performance. Results regarding the telemeter data recorded by ground stations, static pressures, variation of altitude with time after release, variation of flight velocities, and fuel-air ratio are provided. Partial failure of the measuring equipment prevented a complete evaluation of engine performance.
- Charts of Thermodynamic Properties of Fluids Encountered in Calculations of Internal Combustion Engine Cycles
- "A single chart has been prepared that simplifies the calculation of the thermodynamic properties of air, various octene-air mixtures, and mixtures of those with their products of combustion at all temperatures below which chemical dissociation becomes unimportant. The chart is based on the use of 1 pound mol of mixture, and examples of its use are given in the form of the calculation of a turbocompressor power plant and a supercharged Otto engine cycle" (p. 1).
- Ground Effect on Downwash Angles and Wake Location
- "A theoretical study has been made of the reduction in downwash and upward displacement of the wake in the presence of the ground, and some verification of the theory has been obtained by means of air-flow measurements made with a ground-board and image-wing combination. Methods are given for estimating the effects and numerous examples are included to illustrate the nature of these effects and to show their order of magnitude" (p. 1).
- Pressure available for cooling with cowling flaps
- Report presents the results of a full-scale investigation conducted in the NACA 20-foot tunnel to determine the pressure difference available for cooling with cowling flaps. The flaps were applied to an exit slot of smooth contour at 0 degree flap angle. Flap angles of 0 degree, 15 degrees, and 30 degrees were tested. Two propellers were used; propeller c which has conventional round blade shanks and propeller f which has airfoil sections extending closer to the hub. The pressure available for cooling is shown to be a direct function of the thrust disk-loading coefficient of the propeller.
- Pressure distribution over NACA 23012 airfoil with a slotted and a split flap
- A pressure-distribution investigation has been conducted in the NACA 4 by 6-foot vertical wind tunnel to determine the air loads on an NACA 23012 airfoil in combination with a 25.66-percent-chord slotted flap and a 20-percent-chord split flap. Pressures were measured on both the upper and the lower surfaces of the main airfoil and the flaps for several angles of attack and at several flap settings. The data, presented as pressure diagrams and as graphs of the section coefficients for the flap alone and for the airfoil-flap combinations, are applicable to rib and flap design for a combination of a thick airfoil and a slotted or a split flap. The results of previous tests of a NACA 23012 airfoil with a slotted flap are compared with the present results.
- Fatigue strength and related characteristics of joints in 24S-T Alclad sheet
- Report includes tension fatigue test results on the following types of samples of 0.040-inch alclad 24s-t: (1) monoblock sheet samples as received and after a post-aging heat treatment, (2) "sheet efficiency" samples (two equally stressed sheets joined by a single transverse row of spot welds) both as received and after post-aging, (3) spot-welded lap-joint samples as received and after post-aging, and (4) roll-welded lap-joint samples. (author).
- The Effect of Internal Pressure on the Buckling Stress of Thin-Walled Circular Cylinders Under Torsion
- "The results of a series of tests to determine the effect of internal pressure on the buckling load of a thin cylinder under an applied torque indicated that internal pressure raises the shear buckling stress. The experimental results were analyzed with the aid of previously developed theory and a simple interaction formula was derived" (p. 1).
- Torsion Tests of Stiffened Circular Cylinders
- "The design of curved sheet panels to resist shear involves a consideration of several factors: the buckling resistance of the sheet, the stress at which buckling becomes permanent, and the strength which may be developed beyond the buckling limit by tension-field action. Although some experimental as well as theoretical work has been done on the buckling and tension-field phases of this problem, neither of these types of action appears to be very well understood. This report presents the results of the first series of torsion tests of stiffened circular cylinders to be completed in connection with this study at Aluminum Research Laboratories" (p. 1).
- Flutter and oscillating air-force calculations for an airfoil in two-dimensional supersonic flow
- A connected account is given of the Possio theory of non-stationary flow for small disturbances in a two-dimensional supersonic flow and of its application to the determination of the aerodynamic forces on an oscillating airfoil. Further application is made to the problem of wing flutter in the degrees of freedom - torsion, bending, and aileron rotations. Numerical tables for flutter calculations are provided for various values of the Mach number greater than unity. Results for bending-torsion wing flutter are shown in figures and are discussed. The static instabilities of divergence and aileron reversal are examined as is a one-degree-of-freedom case of torsional oscillatory instability.
- Thin Oblique Airfoils at Supersonic Speed
- "The well-known methods of thin-airfoil theory have been extended to oblique or sweptback airfoils of finite aspect ratio moving at supersonic speeds. The cases considered thus far are symmetrical airfoils at zero lift having plan forms bounded by straight lines. Because of the conical form of the elementary flow fields, the results are comparable in simplicity to the results of the two-dimensional thin-airfoil theory for subsonic speeds" (p. 267).
- The numerical solution of compressible fluid flow problems
- Numerical methods have been developed for obtaining the steady, adiabatic flow field of a frictionless, perfect gas about arbitrary two-dimensional bodies. The solutions include the subsonic velocity regions, the supersonic velocity regions, and the transition compression shocks, if required. Furthermore, the rotational motion and entropy changes following shocks are taken into account. Extensive use is made of the relaxation method. In this report the details of the methods of solution are emphasized so as to permit others to solve similar problems. Solutions already obtained are mentioned only by way of illustrating the possibilities of the methods described. The methods can be applied directly to wind tunnel and free air tests of arbitrary airfoil shapes at subsonic, sonic, and supersonic speeds.
- Two-Dimensional Irrotational Mixed Subsonic and Supersonic Flow of a Compressible Fluid and the Upper Critical Mach Number
- Note presenting the use of the hodograph method to investigate the problem of flow of a compressible fluid past a body with subsonic flow at infinity. Explicit formulas for numerical calculations are given for the flow about a body, such as an elliptical cylinder, and for the periodic flow such as would exist over a wavy surface.
- The theoretical flow of a frictionless, adiabatic, perfect gas inside of a two-dimensional hyperbolic nozzle
- Report presenting a study of the two-dimensional flow of a frictionless, adiabatic, perfect gas inside of a two-dimensional hyperbolic nozzle by using numerical methods.
- Maximum Rates of Control Motion Obtained From Ground Tests
- Report discusses the results of testing to determine the maximum rates of control stick (elevator) motion and corresponding maximum stick forces that could be exerted based on experiments with several pilots. The main topics explored were the comparison of the maximum rates of push and pull, maximum rates of push and pull when a mental restriction was placed on the pilot, and maximum rates at which the pilot though he would apply the elevator control forces versus the actual application of forces. Information about experimental procedures and the rig the testing occurred on is included.
- Analysis of Available Data on Control Surfaces Having Plain-Overhang and Frise Balances
- From Introduction: "The present paper deals with control surfaces having plain-overhang and Frise balances."
- An Automatically Variable Control Linkage and Its Effect on the Lateral-Control Characteristics of a High-Speed Fighter Airplane
- Report discusses an analysis and preliminary design of a control linkage that varies automatically with dynamic pressure. The advantages of the device, including greater lateral control than a fixed control linkage without additional aerodynamic balance, are detailed. The effect of variable linkage on lateral-control characteristics is also described.
- Full-scale tunnel investigation of the pressure distribution over the tail of the P-47B airplane
- Report presenting measurements made of the pressures of the tail surfaces of the Republic Aviation Corporation P-47B airplane in the full-scale tunnel. Pressures were measured over the horizontal and vertical tail surfaces for several angles of attack and angles of yaw with numerous control-surface deflections to provide a check on the design loads. Results regarding the normal-force coefficients and predictions of forces on horizontal tail surfaces are provided.
- Analysis of available data on the effectiveness of ailerons without exposed overhang balance
- From Introduction: "As a part of the general lateral-control investigation by the NACA, the large amount of two- and three-dimensional data on the rolling effectiveness of ailerons without exposed overhang balance is collected and analyzed in the present paper."
- Flight Tests of Dive-Recovery Flaps on an XP-51 Airplane
- Report presenting a flight investigation made to determine the effectiveness of dive-recovery flaps installed on the XP-51 airplane as a safety device for recovery from contemplated terminal-velocity dives. The flap installation is described and results are presented of measurements obtained during stick-free pull-ups and pull-outs made by deflecting the dive-recovery flaps to two selected values of flap angle .
- Estimation of Pressures on Cockpit Canopies, Gun Turrets, Blisters, and Similar Protuberances
- Report presenting methods for estimating pressure distributions over protuberances such as cockpit canopies, gun turrets, blisters, scoops, and sighting domes. The methods are applied to the estimation of the pressure distributions over spherical segment and faired gun turrets and over the protuberances on the Brewster SB2A-1 airplane. The effects of compressibility, interference, and flow separation are discussed.
- The Porpoising Characteristics of a Planing Surface Representing the Forebody of a Flying-Boat Hull
- Porpoising characteristics were observed on V-body fitted with tail surfaces for different combinations of load, speed, moment of inertia, location of pivot, elevator setting, and tail area. A critical trim was found which was unaltered by elevator setting or tail area. Critical trim was lowered by moving pivot either forward or down or increasing radius or gyration. Increase in mass and moment of inertia increased amplitude of oscillations. Complete results are tabulated and shown graphically.
- A flight investigation of internally balanced sealed ailerons in the presence of a balanced split flap
- Report presenting flight tests made with a modified Ryan ST airplane to determine the effect on aileron characteristics of various arrangements of balanced split flaps covering that portion of the wing span occupied by the ailerons. With the flaps fully extended, the aileron effectiveness was reduced by approximately 18 percent of the effectiveness measured with ailerons alone.
- Effect of Changes in Aileron Rigging on the Stick Forces of a High-Speed Fighter Airplane
- "The effects of changes in aileron rigging between 2 deg up and 2 deg down on the stick forces were determined from wind-tunnel data for a finite-span wing model. These effects were investigated for ailerons deflecting equally in both directions and linearly with stick deflection. Data were analyzed for a Frise, a sealed internally balanced, and a beveled-trailing-edge aileron" (p. 1).