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Tank investigation of a powered dynamic model of a large long-range flying boat

Description: Principles for designing the optimum hull for a large long-range flying boat to meet the requirements of seaworthiness, minimum drag, and ability to take off and land at all operational gross loads were incorporated in a 1/12-size powered dynamic model of a four-engine transport flying boat having a design gross load of 165,000 pounds. These design principles included the selection of a moderate beam loading, ample forebody length, sufficient depth of step, and close adherence to the form of a streamline body. The aerodynamic and hydrodynamic characteristics of the model were investigated in Langley tank no. 1. Tests were made to determine the minimum allowable depth of step for adequate landing stability, the suitability of the fore-and-aft location of the step, the take-off performance, the spray characteristics, and the effects of simple spray-control devices. The application of the design criterions used and test results should be useful in the preliminary design of similar large flying boats.
Date: January 1, 1947
Creator: Parkinson, John B; Olson, Roland E & Harr, Marvin I
Partner: UNT Libraries Government Documents Department

Tank tests of NACA model 40 series of hulls for small flying boats and amphibians

Description: The NACA model 40 series of flying-boat hull models consists of 2 forebodies and 3 afterbodies combined to provide several forms suitable for use in small marine aircraft. One forebody is the usual form with hollow bow sections and the other has a bottom surface that is completely developable from bow to step. The afterbodies include a short pointed afterbody with an extension for the tail surfaces, a long afterbody similar to that of a seaplane float but long enough to carry the tail surfaces, and a third obtained by fitting a second step in the latter afterbody. The various combinations were tested in the NACA Tank by the general method over a suitable range of loadings. Fixed-trim tests were made for all speeds likely to be used and free-to-trim tests were made at low speeds to slightly beyond the hump speed. The characteristics of the hulls at best trim angles have been deduced from the data of the tests at fixed trim angles and are given in the form of nondimensional coefficients applicable to any size hull.
Date: January 1, 1937
Creator: Parkinson, John B & Dawson, John R
Partner: UNT Libraries Government Documents Department

Test of single-stage axial-flow fan

Description: A single-stage axial fan was built and tested in the shop of the propeller-research tunnel of the NACA. The fan comprised a simple 24-blade rotor having a diameter of 21 inches and a solidity of 0.86 and a set of 37 contravanes having a solidity of 1.33. The rotor was driven by a 25-horsepower motor capable of rotating at a speed of 3600 r.p.m. The fan was tested for volume, pressure, and efficiency over a range of delivery pressures and volumes for a wide range of contravane and blade-angle settings. The test results are presented in chart form in terms of nondimensional units in order that similar fans may be accurately designed with a minimum effort. The maximum efficiency (88 percent) was obtained by the fan at a blade angle of 30 degrees and a contravane angle of 70 degrees. An efficiency of 80 percent was obtained by the fan with the contravanes removed.
Date: January 1, 1942
Creator: Bell, E Barton
Partner: UNT Libraries Government Documents Department

Tests in the variable-density wind tunnel of the NACA 23012 airfoil with plain and split flaps

Description: Section characteristics for use in wing design are presented for the NACA 23012 airfoil with plain and split flaps of 20 percent wing chord at a value of the effective Reynolds number of about 8,000,000. The flap deflections covered a range from 60 degrees upward to 75 degrees downward for the plain flap and from neutral to 90 degrees downward for the split flap. The split flap was aerodynamically superior to the plain flap in producing high maximum lift coefficients and in having lower profile-drag coefficients at high lift coefficients.
Date: January 1, 1939
Creator: Abbott, Ira H & Greenberg, Harry
Partner: UNT Libraries Government Documents Department

Tests of 16 related airfoils at high speed

Description: In order to provide information that might lead to the development of better propeller section, 13 related symmetrical airfoils were tested in the NACA high-speed wind tunnel for a study of the effect of thickness form on the aerodynamic characteristics. The thickness-form variables studies were the value of the maximum thickness, the position along the chord at which the maximum thickness occurs, and the value of the leading-edge radius. The tests were conducted through the low angle-of-attack range for speeds extending from 35 percent of that of sound to slightly in excess of the speed at which a compressibility burble, or breakdown of flow, occurs. The corresponding Reynolds number range is 350,000 to 750,000.
Date: January 1, 1935
Creator: Stack, John & Von Doenhoff, Albert E
Partner: UNT Libraries Government Documents Department

A theoretical analysis of the effect of time lag in an automatic stabilization system on the lateral oscillatory stability of an airplane

Description: A method is presented for determining the effect of time lag in an automatic stabilization system on the lateral oscillatory stability of an airplane. The method is based on an analytical-graphical procedure. The critical time lag of the airplane-autopilot system is readily determined from the frequency-response analysis. The method is applied to a typical present-day airplane equipped with an automatic pilot sensitive to yawing acceleration and geared to the rudder so that rudder control is applied in proportion to the yawing acceleration. The results calculated for this airplane-autopilot system by this method are compared with the airplane motions calculated by a step-by-step procedure.
Date: January 1, 1951
Creator: Sternfield, Leonard & Gates, Ordway B , Jr
Partner: UNT Libraries Government Documents Department

A theoretical analysis of the effects of fuel motion on airplane dynamics

Description: The general equations of motion for an airplane with a number of spherical fuel tanks are derived. The motion of the fuel is approximated by the motion of solid pendulums. The same type of derivation and equations are shown to apply to any type of fuel tank where the motion of the fuel may be represented in terms of undamped harmonic oscillators. Motions are calculated for a present-day high-speed airplane and a free-flying airplane model with two spherical tanks in the symmetry plane.
Date: January 1, 1952
Creator: Schy, Albert A
Partner: UNT Libraries Government Documents Department

Theoretical and analog studies of the effects of nonlinear stability derivatives on the longitudinal motions of an aircraft in response to step control deflections and to the influence of proportional automatic control

Description: Through theoretical and analog results the effects of two nonlinear stability derivatives on the longitudinal motions of an aircraft have been investigated. Nonlinear functions of pitching-moment and lift coefficients with angle of attack were considered. Analog results of aircraft motions in response to step elevator deflections and to the action of the proportional control systems are presented. The occurrence of continuous hunting oscillations was predicted and demonstrated for the attitude stabilization system with proportional control for certain nonlinear pitching-moment variations and autopilot adjustments.
Date: January 1, 1955
Creator: Curfman, Howard J , Jr
Partner: UNT Libraries Government Documents Department

Theoretical and experimental analysis of low-drag supersonic inlets having a circular cross section and a central body at Mach numbers 3.30, 2.75, and 2.45

Description: Contains theoretical and experimental analysis of circular inlets having a central body at Mach numbers of 3.30, 2.75, and 2.45. The inlets have been designed in order to have low drag and high pressure recovery. The pressure recoveries obtained are of the same order of magnitude as those previously obtained by inlets having very large external drag.
Date: January 1, 1954
Creator: Ferri, Antonio & Nucci, Louis M
Partner: UNT Libraries Government Documents Department

Investigation of full-scale split trailing-edge wing flaps with various chords and hinge locations

Description: This report gives the results of an investigation conducted in the NACA full-scale wind tunnel on a small parasol monoplane equipped with three different split trailing-edge wing flaps. The object of the investigation was to determine and correlate data on the characteristics of the airplane and flaps as affected by variation in flap chord, flap deflection, and flap location along the wing chord. The results give the lift, the drag, and the pitching moment characteristics of the airplane, and the flap forces and moments, the pressure distribution over the flaps and wing at one section, and the downwash characteristics of the flap and wing combinations.
Date: January 1, 1936
Creator: Wallace, Rudolf
Partner: UNT Libraries Government Documents Department

The calculated performance of airplanes equipped with supercharging engines

Description: In part one of this report are presented the theoretical performance curves of an airplane engine equipped with a supercharging compressor. In predicting the gross power of a supercharging engine, the writer uses temperature and pressure correction factors based on experiments made at the Bureau of Standards (NACA report nos. 45 and 46). Means for estimating the temperature rise in the compressor are outlined. Part two of this report presents an estimation of the performance curves of an airplane fitted with a supercharging engine. A supercharging installation suitable for commercial use is described, and it is shown that with the use of the compressor a great saving in fuel and a considerable increase in carrying capacity can be effected simultaneously. In an appendix the writer derives a theoretical formula for the correction of the thrust coefficient of an airscrew to offset the added resistance of the airplane due to the slip-stream effect.
Date: January 1, 1921
Creator: Kemble, E C
Partner: UNT Libraries Government Documents Department

An investigation of the aerodynamic characteristics of an airplane equipped with several different sets of wings

Description: This investigation was conducted by the National Advisory Committee for Aeronautics at Langley Field, Va., at the request of the Army Air Corps, for the purpose of comparing the full scale lift and drag characteristics of an airplane equipped with several sets of wings of commonly used airfoil sections. A Sperry Messenger Airplane with wings of R.A.F.-15, U.S.A.-5, U.S.A.-27, and Gottingen 387 airfoil sections was flown and the lift and drag characteristics of the airplane with each set of wings were determined by means of glide tests. The results are presented in tabular and curve form. (author).
Date: January 1, 1929
Creator: Crowley, J W , Jr & Green, M W
Partner: UNT Libraries Government Documents Department

Dynamic stability as affected by the longitudinal moment of inertia

Description: In a recent Technical Note (NACA-TN-115, October, 1922), Norton and Carrol have reported experiments showing that a relatively large (15 per cent) increase in longitudinal moment of inertia made no noticeable difference in the stability of a standard SE-5A airplane. They point out that G. P. Thomson, "Applied Aeronautics," page 208, stated that an increase in longitudinal moment of inertia would decrease the stability. Neither he nor they make any theoretical forecast of the amount of decrease. Although it is difficult, on account of the complications of the theory of stability of the airplane, to make any accurate forecast, it is the purpose of this report to attempt a discussion of the matter theoretically with reference to finding a rough quantitative estimate.
Date: January 1, 1924
Creator: Wilson, Edwin B.
Partner: UNT Libraries Government Documents Department

An investigation of the coefficient of discharge of liquids through small round orifices

Description: The work covered by this report was undertaken in connection with a general investigation of fuel injection engine principles as applied to engines for aircraft propulsion, the specific purpose being to obtain information on the coefficient of discharge of small round orifices suitable for use as fuel injection nozzles. Values for the coefficient were determined for the more important conditions of engine service such as discharge under pressures up to 8,000 pounds per square inch, at temperatures between 80 degrees and 180 degrees F. And into air compressed to pressures up to 1,000 pounds per square inch. The results show that the coefficient ranges between 0.62 and 0.88 for the different test conditions between 1,000 and 8,000 pounds per square inch hydraulic pressure. At lower pressures the coefficient increases materially. It is concluded that within the range of these tests and for hydraulic pressures above 1,000 pound per square inch the coefficient does not change materially with pressure or temperature; that it depends considerably upon the liquid, decreases with increase in orifice size, and increases in the case of discharge into compressed air until the compressed-air pressure equals approximately three-tenths of the hydraulic pressure, beyond which pressure ratio it remains practically constant.
Date: January 1, 1926
Creator: Joachim, W F
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
Partner: UNT Libraries Government Documents Department

Investigation of the diaphragm-type pressure cell

Description: This report relates to various improvements in the process of manufacture of the NACA standard pressure cell. Like most pressure recording devices employing thin diaphragms, they would in general show considerable change in calibration with temperature and also some change of calibration with time or aging effect. The required diaphragm thickness and the desirable rate of mechanical magnification have been determined on the basis of several hundred tests.
Date: January 1, 1932
Creator: Theodorsen, Theodore
Partner: UNT Libraries Government Documents Department

Scale effect on Clark Y airfoil characteristics from NACA full-scale wind-tunnel tests

Description: This report presents the results of wind tunnel tests conducted to determine the aerodynamic characteristics of the Clark Y airfoil over a large range of Reynolds numbers. Three airfoils of aspect ratio 6 and with 4, 6, and 8 foot chords were tested at velocities between 25 and 118 miles per hour, and the characteristics were obtained for Reynolds numbers (based on the airfoil chord) in the range between 1,000,000 and 9,000,000 at the low angles of attack, and between 1,000,000 and 6,000,000 at maximum lift. With increasing Reynolds number the airfoil characteristics are affected in the following manner: the drag at zero lift decreases, the maximum lift increases, the slope of the lift curve increases, the angle of zero lift occurs at smaller negative angles, and the pitching moment at zero lift does not change appreciably.
Date: January 1, 1935
Creator: Silverstein, Abe
Partner: UNT Libraries Government Documents Department

Shear lag in box beams methods of analysis and experimental investigations

Description: The bending stresses in the covers of box beams or wide-flange beams differ appreciably from the stresses predicted by the ordinary bending theory on account of shear deformation of the flanges. The problem of predicting these differences has become known as the shear-lag problem. The first part of this paper deals with methods of shear-lag analysis suitable for practical use. The second part of the paper describes strain-gage tests made by the NACA to verify the theory. Three tests published by other investigators are also analyzed by the proposed method. The third part of the paper gives numerical examples illustrating the methods of analysis. An appendix gives comparisons with other methods, particularly with the method of Ebner and Koller.
Date: January 1, 1942
Creator: Kuhn, Paul & Chiarito, Patrick T
Partner: UNT Libraries Government Documents Department

A simplified application of the method of operators to the calculation of disturbed motions of an airplane

Description: A simplified treatment of the application of Heaviside's operational methods to problems of airplane dynamics is given. Certain graphical methods and logarithmic formulas that lessen the amount of computation involved are explained. The problem representing a gust disturbance or control manipulation is taken up and it is pointed out that in certain cases arbitrary control manipulations may be dealt with as though they imposed specific constraints on the airplane, thus avoiding the necessity of any integration. The application of the calculations described in the text is illustrated by several examples chosen to show the use of the methods and the practicability of the graphical and logarithmic computations described.
Date: January 1, 1937
Creator: Jones, Robert T
Partner: UNT Libraries Government Documents Department

Some effects of frequency on the contribution of a vertical tail to the free aerodynamic damping of a model oscillating in yaw

Description: The damping in yaw and the directional stability of a model freely oscillating in yaw were measured tail-off and tail-on and compared with the values obtained by theoretical consideration of the unsteady lift associated with an oscillating vertical tail. A range of low frequencies comparable to those of the lateral motions of airplanes was covered. The analysis includes the effects of vertical-tail aspect ratio and the two-dimensional effects of compressibility.
Date: January 1, 1953
Creator: Bird, John D; Fisher, Lewis R & Hubbard, Sadie M
Partner: UNT Libraries Government Documents Department

Some effects of nonlinear variation in the directional-stability and damping-in-yawing derivatives on the lateral stability of an airplane

Description: A theoretical investigation has been made to determine the effect of nonlinear stability derivatives on the lateral stability of an airplane. Motions were calculated on the assumption that the directional-stability and the damping-in-yawing derivatives are functions of the angle of sideslip. The application of the Laplace transform to the calculation of an airplane motion when certain types of nonlinear derivatives are present is described in detail. The types of nonlinearities assumed correspond to the condition in which the values of the directional-stability and damping-in-yawing derivatives are zero for small angle of sideslip.
Date: January 1, 1951
Creator: Sternfield, Leonard
Partner: UNT Libraries Government Documents Department

Some theoretical low-speed span loading characteristics of swept wings in roll and sideslip

Description: The Weissinger method for determining additional span loading for incompressible flow is used to find the damping in roll, the lateral center of pressure of the rolling for wing plan forms of various aspect ratios, taper ratios, and sweep angles. In addition, the applicability of the method to the determination of certain other aerodynamic derivatives is investigated, and corrections for the first-order effects of compressibility are indicated. The agreement obtained between experimentally and theoretically determined values for the aerodynamic coefficients indicates that the method of Weissinger is well suited to the calculation of such resulting aerodynamic derivatives of wings as do not involve considerations of tip suction.
Date: January 1, 1950
Creator: Bird, John D
Partner: UNT Libraries Government Documents Department

Sound-level measurements of a light airplane modified to reduce noise reaching the ground

Description: An Army liaison-type airplane, representative of personal airplanes in the 150 to 200 horsepower class, has been modified to reduce propeller and engine noise according to known principles of airplane-noise reduction. Noise-level measurements demonstrate that, with reference to an observer on the ground, a noisy airplane of this class can be made quiet -- perhaps more quiet than necessary. In order to avoid extreme and unnecessary modifications, acceptable noise levels must be determined.
Date: January 1, 1949
Creator: Vogeley, A W
Partner: UNT Libraries Government Documents Department

Sound from a two-blade propeller at supersonic tip speeds

Description: Report presents the results of sound measurements at static conditions made for a two-blade 47-inch-diameter propeller in the tip Mach number range 0.75 to 1.30. For comparison, spectrums have been obtained at both subsonic and supersonic tip speeds. In addition, the measured data are compared with calculations by the theory of Gutin which has previously been found adequate for predicting the sound at subsonic tip speeds. Curves are presented from which the maximum over-all noise levels in free space may be estimated if the power, tip Mach number, and distance are known.
Date: January 1, 1952
Creator: Hubbard, Harvey H & Lassiter, Leslie W
Partner: UNT Libraries Government Documents Department