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.
- A General Method of Selecting Foam Inhibitors
- Note presenting a criterion for selecting foam inhibitors from insoluble liquids that form emulsions with the foaming liquid. By determining the surface tensions of the foaming liquid and of the additive saturated with that liquid and the interfacial tension between them, spreading and entering coefficients may be calculated. A mechanism of foam inhibition is also described.
- Boundary-Induced Upwash for Yawed and Swept-Back Wings in Closed Circular Wind Tunnels
- 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.
- Experimental and calculated characteristics of several NACA 44-series wings with aspect ratios of 8, 10, and 12 and taper ratios of 2.5 and 3.5
- 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.
- Interference of Wing and Fuselage From Tests of 30 Combinations With Triangular and Elliptical Fuselages in the NACA Variable-Density Tunnel
- 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.
- A Lifting-Surface-Theory Solution and Tests of an Elliptic Tail Surface of Aspect Ratio 3 with a 0.5-Chord 0.85-Span Elevator
- Note presenting an electromagnetic-analogy model of the vortex load, estimated from lifting-line theory with an arbitrary fairing near the elevator tip, on a thin elliptic horizontal tail surface of aspect ratio 3 with a 0.5-chord 0.85-span plain elevator was constructed and tested. A comparison of the aspect-ratio corrections for the partial-span elevators was made with those previously presented for full-span elevators. Wind-tunnel results for a tail surface of the some plan form are presented.
- Measurements of the Pressure Distribution on the Horizontal Tail Surface of a Typical Propeller-Driven Pursuit Airplane in Flight 2: The Effect of Angle of Sideslip and Propeller Operation
- Report presenting measurements in sideslipping flight of the pressure distribution over the horizontal tail surface of a tractor-propeller-driven pursuit airplane to determine the effects of angle of sideslip and propeller operation on the tail-load distribution. Results regarding the reduction of data, effect of sideslip and power on tail loads, effect of sideslip and power on tail moments, and a comparison of the calculated loading with experimental results.
- Flight investigation of the effects on airplane static longitudinal stability of a bungee and engine-tilt modifications
- 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.
- 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).
- Some Notes on the Effects of Jet-Exit Design on Static Longitudinal Stability
- Report discussing several types of jet-exit designs, including normal, beveled, and unsymmetrical shapes, and their effect on the stability characteristics of the aircraft. No deviation of the jet center line from its exposed path is likely to be obtained if a jet exist is used that is normal to the flow. Having a tilted or asymmetrical exit was found to adversely affect the stability of the aircraft.
- An Analytical Investigation of the Effects of Elevator-Fabric Distortion on the Longitudinal Stability and Control of an Airplane
- From Summary: "The results of an analytical investigation to determine the qualitative effects of elevator-fabric distortion on the stick-force characteristics of an airplane are presented. These results indicate that serious alteration of intended stick-force characteristics can be produced by elevator-fabric distortion."
- Prediction of Motions of an Airplane Resulting from Abrupt Movement of Lateral or Directional Controls
- Report presenting a procedure for determining the motions of an airplane resulting from the deflection of the lateral or directional controls for the case of non-linear derivatives. A simple computation table is presented to illustrate the application of the procedure.
- Shear Tests on DuPont Explosive Rivets With the Countersunk Head Milled Flush After Expansion
- Report discusses the results of shear testing in which the heads of Du Pont explosive countersunk rivets were allowed to protrude above the skin surface before expansion and the protruding portions were removed after expansion. As the height of the rivet head above the skin increases, the tightness of the rivet was found to increase. The report concludes that it may be desirable to investigating filling an entire shank with an explosive charge in order to permit greater tolerances in the drilled hole diameter and still have consistently tight rivets.
- Formulas for propellers in yaw and charts of the side-force derivative
- Report presenting formulas for propellers for the rate of change of side-force coefficient with angle of yaw and for the rate of change of pitching-moment coefficient with angle of yaw. Charts of side-force derivatives are given for two propellers of different plan forms.
- Effect of Oil Flow to Piston on Piston-Ring Sticking and Oil Consumption in a Single-Cylinder Engine
- Report presenting an investigation to determine the effect of the amount of oil flow to the piston on the ring-sticking characteristics of a piston and ring assembly and on the engine oil consumption. Results regarding the blow-by, lubrication, oil consumption, and method of supplying oil are provided.
- Tests of the Jet-Motor Air-Intake Duct System on a 1/4-Scale Stub-Wing Model of a Pursuit-Type Airplane
- Report discussing the characteristics of the jet-motor air-intake duct system for a pursuit-type airplane with modifications to the duct system. Details of its effects on the Mach number, high pressure recovery, drag, and simplicity of the system are provided. Problems regarding the flow condition through the ducts and some potential modifications to prevent further issues are also described.
- Some Lift and Drag Measurements of a Representative Bomber Nacelle on a Low-Drag Wing
- Report presenting testing of a representative bomber nacelle on a low-drag wing in the NACA two-dimensional tunnel. The adverse or interference effects of the nacelle on the low-drag wing were small.
- High-speed tests of radial-engine nacelles on a thick low-drag wing
- Report presenting testing in the high-speed wind tunnel to determine the drag characteristics of several types of radial-engine nacelle on a low-drag airfoil. The drag coefficients of nacelles incorporating cowling-nose shapes shown by previous tests to be efficient and afterbodies of adequate length were about the same magnitude as commonly obtained for comparable installations on conventional wings. Results regarding the reduction of data, effect of nacelles on lift, and pressures at wing-nacelle juncture are provided.
- A proposed method of measuring engine charge air flow in flight
- From Summary: "A method is outlined for determining in flight the weight rate of air flow to the engine equipped with a Bendix-Stromberg injection-type carburetor. The method has the advantage that no additional equipment need be inserted in the charge-air system and only a few simple measurements are necessary. The analysis of an air-box calibration of the carburetor to be used in interpreting the flight measurements is shown by an example."
- Effect of inlet-air velocity distribution on the metering pressure of an injection-type aircraft carburetor
- Report presenting tests of a three-barrel pressure carburetor to determine the effect of nonuniformity of the air flow in the intake duct on the metering of the carburetor. Measurements were made in the air side of the metering system and in the carburetor barrels for a variety of flow distributions. Results regarding the metering pressure, altitude compensation, effect of throttle on the metering characteristics, and flow of air around the bends are provided
- Hydraulic Characteristics of the NACA Injection Impeller
- Report discussing a mock-up injection impeller created to investigate the hydraulic characteristics and limitations of the NACA injection impeller currently in use. Information about the form and magnitude of critical factors of fuel-transfer leakage and peripheral fuel distribution is provided as well as the effects of design variations of components on hydraulic characteristics. Several revisions in portions of the impeller are suggested to improve its fuel-transfer, fuel-pumping, and fuel-equalizing characteristics.
- Method of Calculating Performance of Dual-Rotating Propellers From Airfoil Characteristics
- "A method is developed for calculating the performance of a dual-rotating propeller from the section characteristics of the blade elements. The method is applied to an eight-blade dual-rotating propeller and the computed results are compared with low-speed wind-tunnel tests of the same propeller in both the tractor and pusher positions. The computations are found to agree within the experimental accuracy of the measurements" (p. 1).
- 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.
- Appreciation and determination of the hydrodynamic qualities of seaplanes
- 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.
- Biaxial Fatigue Strength of 24S-T Aluminum Alloy
- Note presenting an investigation to determine the fatigue-strength values for 24S-T aluminum alloy when subjected to various ratios of biaxial stresses. The stresses considered were both tensile. The results indicated that uniaxial fatigue-strength values in the longitudinal direction cannot be used to predict the fatigue strength, and that biaxial fatigue strength may be as low as 50 percent of the uniaxial fatigue strength.
- Collection and analysis of wind-tunnel data on the characteristics of isolated tail surfaces with and without end plates
- 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.
- Tests of the NACA 64(SUB 1)A212 airfoil section with a slat, a double slotted flap, and boundary-layer control by suction
- Report presenting an investigation of the NACA 64(sub 1)A212 airfoil section equipped with a leading-edge slat, a double slotted flap, and a boundary-layer-control suction slot at 0.40 chord to determine the maximum lift coefficients attainable with the high-lift devices alone and in conjunction with one another. Results regarding the effect of suction-slot location on the characteristics of a plain airfoil, plain airfoil characteristics, effect of irregularities caused by slat installation, characteristics of the airfoil with slat extended, characteristics of the airfoil with double slotted flap, characteristics of the airfoil with leading-edge slat and double slotted flap, and a comparison of maximum lift coefficients obtained with various high-lift devices are provided.
- An Electrical Computer for the Solution of Shear-Lag and Bolted-Joint Problems
- "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).
- Critical Shear Stress of Curved Rectangular Panels
- "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).
- 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).
- Bending Stresses Due to Torsion in a Tapered Box Beam
- 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.
- Effect of spoiler-type lateral-control devices on the twisting moments of NACA 230-Series airfoil sections
- 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.
- Effects of Mach Number and Reynolds Number on the Maximum Lift Coefficient of a Wing of NACA 230-Series Airfoil Sections
- 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.