National Advisory Committee for Aeronautics (NACA) - 300 Matching Results

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Speed and deceleration trials of U.S.S. Los Angeles
From Summary: "The trials reported in this report were instigated by the Bureau of Aeronautics of the Navy Department for the purpose of determining accurately the speed and resistance of the U. S. S. "Los Angeles" with and without water recovery apparatus, and to clear up the apparent discrepancies between the speed attained in service and in the original trials in Germany. The trials proved very conclusively that the water recovery apparatus increases the resistance about 20 per cent, which is serious, and shows the importance of developing a type of recovery having less resistance. Between the American and the German speed trials without water recovery there remains an unexplained discrepancy of nearly 6 per cent in speed at a given rate of engine revolutions."
Spray penetration with a simple fuel injection nozzle
The purpose of the tests covered by this report was to obtain specific information on the rate of penetration of the spray from a simple injection nozzle, having a single orifice with a diameter of 0.015 inch when injecting into compressed gases. The results have shown that the effects of both chamber and fuel pressures on penetration are so marked that the study of sprays by means of high-speed photography or its equivalent is necessary if the effects are to be appreciated sufficiently to enable rational analysis. It was found for these tests that the negative acceleration of the spray tip is approximately proportional to the 1.5 power of the instantaneous velocity of the spray tip.
Stability Equations for Airship Hulls
In the text are derived simple formulae for determining, directly from the data of wind tunnel tests of a model of an airship hull, what shall be the approximate character of oscillation, in pitch or yaw, of the full-scale airship when slightly disturbed from steady forward motion. (author).
Stability of the Parachute and Helicopter
This report deals with an extension of the theory of stability in oscillation to the case of aircraft following a vertical trajectory, and particularly to the oscillations of parachutes.
Standard Atmosphere
This report was prepared at the request of the National Advisory Committee for Aeronautics and discusses the need of a standard set of values of pressure, temperature and density at various altitudes and points out the desirability of adopting such values as are most in accord with actual average conditions, in order that corrections in individual cases may be as small as possible. To meet this need, so far as the united states is concerned, all free-air observations obtained by means of kites and balloons at several stations in this country near latitude 40 degrees N., have been used, and average values of pressure, temperature, and density, based upon those observations, have been determined for summer, winter, and the year, and for all altitudes up to 20,000 meters (65,000 feet).
Standard atmosphere - tables and data
Detailed tables of pressures and densities are given for altitudes up to 20,000 meters and to 65,000 feet. In addition to the tables the various data pertaining to the standard atmosphere have been compiled in convenient form for ready reference. This report is an extension of NACA-TR-147.
Standardization tests of NACA No. 1 wind tunnel
"The tests described in this report were made in the 5-foot atmospheric wind tunnel of the National Advisory Committee for Aeronautics, at Langley Field. The primary objective of collecting data on the characteristics of this tunnel for comparison with those of others throughout the world, in order that, in the future, the results of tests made in all the principle laboratories may be interpreted, compared, and coordinated on a basis of scientifically established relationships, a process hitherto impossible due to the lack of comparable data. The work includes tests of a disk, spheres, cylinders, and airfoils, explorations of the test section for static pressure and velocity distribution, and determination of the variations of air flow direction throughout the operating range of the tunnel" (p. 207).
Statical Longitudinal Stability of Airplanes
This report, which is a continuation of the "Preliminary report on free flight testing" (report no. NACA-TR-70), presents a detailed theoretical analysis of statical stability with free and locked controls and also the results of many free flight test on several types of airplanes. In developing the theory of stability with locked controls an expression for pitching moment is derived in simple terms by considering the total moment as the sum of the moments due to wings and tail surface. This expression, when differentiated with respect to angle of incidence, enables an analysis to be made of the factors contributing to the pitching moment.
The Strength of One-Piece Solid, Build-Up and Laminated Wood Airplane Wing Beams
The purpose of this report is to summarize the results of all wood airplane wing beams tested to date in the Bureau of Standards Laboratory in order that the various kinds of wood and methods of construction may be compared. All beams tested were of an I section and the majority were somewhat similar in size and cross section to the front wing beam of the Curtiss JN-4 machine. Construction methods may be classed as (1) solid beams cut from solid stock; (2) three-piece beams, built up of three pieces, web and flanges glued together by a tongue-and-groove joint and (3) laminated beams built up of thin laminations of wood glued together.
The Structure of Airplane Fabrics
This report prepared by the Bureau of Standards for the National Advisory Committee for Aeronautics supplies the necessary information regarding the apparatus and methods of testing and inspecting airplane fabrics.
A Study of Airplane Engine Tests
This report is a study of the results obtained from a large number of test of an Hispano-Suiza airplane engine in the altitude laboratory of the Bureau of Standards. It was originally undertaken to determine the heat distribution in such an engine, but many other factors are also considered as bearing on this matter.
A Study of Airplane Maneuvers With Special Reference to Angular Velocities
"This investigation was undertaken by the National Advisory Committee for Aeronautics for the purpose of increasing our knowledge on the behavior of the airplane during various maneuvers and to obtain values of the maximum angular velocities and accelerations in flight. The method consisted in flying a JN4H airplane through various maneuvers while records were being taken of the control position, the air speed, the angular velocity and the acceleration along the Z axis. The results showed that the maximum angular velocity about the X axis of radians per second in a barrel roll" (p. 563).
A Study of Airplane Ranges and Useful Loads
This report is an analysis of the maximum flight radii of typical large airplanes and a discussion of the way in which the possible length of flight is affected by the change of weight by consumption of fuel during the flight.
A Study of Longitudinal Dynamic Stability in Flight
"This investigation was carried out by the aerodynamic staff of the National Advisory Committee for Aeronautics for the purpose of studying experimentally the longitudinal dynamic stability of airplanes in flight. The airplanes selected for this purpose were a standard rigged VE-7 advanced-training airplane and a JN4H with special tail surfaces. The airplanes were caused to oscillate by means of the elevator, then the longitudinal control was either locked or kept free while the oscillation died out" (p. 231).
A study of taking off and landing an airplane
"This report covers the results of an investigation carried on at the Langley Memorial Aeronautical Laboratory of the National Advisory Committee for Aeronautics for the purpose of discussing the various methods of effecting the take-off and the landing of an airplane, and to make a direct analysis of the control movements, the accelerations, and air speeds during these the maneuvers. The recording instruments developed at the laboratory were used in this test and the records obtained by them were made the basis for a comparative study of the two extreme methods of taking off (the tail-high and tail-low methods) and of various types of landings. The records should be of considerable value to a student pilot in enabling him to visualize the movements of the controls and the consequent effect upon the air speed and acceleration" (p. 555)
A study of the effect of a diving start on airplane speed
Equations for instantaneous velocity and distance flown are derived for an airplane which crosses the starting line of a speed course at a speed higher than that which can normally be maintained in horizontal flight. A specific case is assumed and calculations made for five initial velocities. Curves of velocity, average velocity, and distance flown are plotted against time for each case and analyzed. It is shown that the increase in average velocity due to a diving start may be very large for short-speed courses.
A Study of Wing Flutter
"Part I describes vibration tests, in a wind tunnel, of simple airfoils and of the tail plane of an M0-1 airplane model; it also describes the air flow about this model. From these tests are drawn inferences as to the cause and cure of aerodynamic wing vibrations. Part II derives stability criteria for wing vibrations in pitch and roll, and gives design rules to obviate instability. Part III shows how to design spars to flex equally under a given wing loading and thereby economically minimize the twisting in pitch that permits cumulative flutter" (p. 109).
The Subsidiary Gap as a Means for Improving Ignition
This report presents the results of an investigation into the utility, action, and design of the auxiliary spark gap as a means for insuring freedom from spark plug failure due to fouling, and also to enable the restarting of fouled plugs. A brief account is given of the use of this gap up to the present time and also of the statements concerning it which have gained some currency, most of which are shown to be erroneous. The simple theory of the action of the series gap is discussed and a detailed account given of the effect upon the sparking ability of the plug produced by changes in the values of the electrical resistance of the fouling and of the capacities in parallel with the plug and with the magneto or coil.
Supplies and Production of Aircraft Woods
The purpose of this report is to present in brief form such information as is available regarding the supplies of the kinds of wood that have been used or seem likely to become important in the construction of airplanes, and the amount of lumber of each species normally put on the market each year. A general statement is given of the uses to which each kind of wood is or may be put.
Synopsis of Aeronautic Radiator Investigations for Years 1917 and 1918
Extensive series of experiments have been conducted at the Bureau of Standards to determine the properties of cooling radiator cores manufactured for airplanes and to develop improvements in design. The analysis of the problem on which this work was based, and consequently the experimental method employed, is different from that commonly used. Instead of attempting to test complete radiators, either full size or in model, uniform sections representing different types of core construction have been tested and an analysis of the results made with a view to determining independently the various factors which influence its performance. This report describes referenced method of analysis in predicting the performance of radiators designed for aeronautic use.
Tables for calibrating altimeters and computing altitudes based on the standard atmosphere
From Summary: "During 1925 the assumption of an isothermal atmosphere which was in general use as the standard for the calibration of altimeters in the United States was replaced by a standard atmosphere which assumes an altitude-temperature relation closely corresponding to the average of upper air observations at latitude 40 degrees in this country. The same standard atmosphere had already been adopted somewhat earlier in the United States as the aircraft performance standard. National Advisory Committee for Aeronautics Technical Reports nos. 147 and 218 give necessary constants, tables, and information. However, neither of these reports includes all of the tables required for the computation of actual altitudes nor those readily suitable for use in calibrating altimeters, since the altitude intervals for which data are given are not sufficiently small."
Tables for pressure of air on coming to rest from various speeds
From Summary: "In Technical Report no. 247 of the National Advisory Committee for Aeronautics theoretical formulas are given from which was computed a table for the pressure of air on coming to rest from various speeds, such as those of aircraft and propeller blades. In that report, the table gave incompressible and adiabatic stop pressures of air for even-speed intervals in miles per hour and for some even-speed intervals in knots per hour. Table II of the present report extends the above-mentioned table by including the stop pressures of air for even-speed intervals in miles per hour, feet per-second, knots per hour, kilometers per hour, and meters per second."
The Tail Plane
This report deals with the calculation of the equilibrium, statistical stability, and damping of the tail plane. The author has simplified the present theory of longitudinal stability for the particular purpose of obtaining one definite coefficient characteristics of the effect of the tail plane. This coefficient is obtained by substituting certain aerodynamic characteristics and some dimensions of the airplane in a comparatively simple mathematical expression.
Testing Balloon Gas
Report describes a simple, portable apparatus for testing hydrogen, with special reference to its use in balloons. "In the generation, storage, and use of hydrogen for balloon purposes it is necessary to be able to determine, first, its lifting power, and, secondly, its purity. The lifting power may be determined directly from the specific gravity. Contamination by other gases may be determined by analysis for oxygen, carbon dioxide, etc., by the usual methods of gas analysis" (p. 469).
The Testing of Balloon Fabrics
Report describes methods and materials used in waterproofing and fireproofing airplane fabrics using dopes. The determination of the probable life of a balloon fabric in service by experimental means is of great value in choosing the most suitable fabrics for a given purpose and in pointing the way to improvements in compounding and construction. The usefulness of exposure to the weather for this purpose has been amply demonstrated.
Tests of large airfoils in the propeller research tunnel, including two with corrugated surfaces
This report gives the results of the tests of seven 2 by 12 foot airfoils (Clark Y, smooth and corrugated, Gottingen 398, N.A.C.A. M-6, and N.A.C.A. 84). The tests were made in the propeller research tunnel of the National Advisory Committee for Aeronautics at Reynolds numbers up to 2,000,000. The Clark Y airfoil was tested with three degrees of surface smoothness. Corrugating the surface causes a flattening of the lift curve at the burble point and an increase in drag at small flying angles.
Tests on Air Propellers in Yaw
This report contains the results of tests to determine the thrust (pull) and torque characteristics of air propellers in movement relative to the air in a line oblique to the line of the shaft, and specifically when such angle of obliquity is large, as in the case of helicopter flight with the propeller serving for both sustentation and traction.
Tests on airplane fuselages, floats and hulls
This report is a compilation of test data on airplane fuselages, nacelles, airship cars, seaplane floats, and seaplane hulls, prepared by the Bureau of Aeronautics, at the requests of the National Advisory Committee for Aeronautics. The discussion of the data includes the derivation of a scale correction curve to be used in obtaining the full scale drag. Composite curves of drag and L/D for floats and hulls are also given. (author).
Tests on Models of Three British Airplanes in the Variable Density Wind Tunnel
"This report contains the results of tests made in the National Advisory Committee for Aeronautics variable density wind tunnel on three airplane models supplied by the British Aeronautical Research Committee. These models, the BE-2E with R.A.F. 19 wings, the British Fighter with R.A.F. 15 wings, and the Bristol Fighter with R.A.F. 30 wings, were tested over a wide range in Reynolds numbers in order to supply data desired by the Aeronautical Research Committee for scale effect studies. The maximum lifts obtained in these tests are in excellent agreement with the published results of British tests, both model and full scale" (p. 451).
Tests on thirteen navy type model propellers
From Summary: "The tests on these model propellers were undertaken for the purpose of determining the performance coefficients and characteristics for certain selected series of propellers of form and type as commonly used in recent navy designs. The first series includes seven propellers of pitch ratio varying by 0.10 to 1.10, the area, form of blade, thickness, etc., representing an arbitrary standard propeller which had shown good results. The second series covers changes in thickness of blade section, other things equal, and the third series, changes in blade area, other things equal. These models are all of 36-inch diameter. Propellers A to G form the series on pitch ratio, C, N. I. J the series on thickness of section, and K, M, C, L the series on area."
Theories of flow similitude
The laws of comparison of dynamically similar fluid motions are derived by three different methods based on the same principle and yielding the same or equivalent formulas. This report outlines the three current methods of comparing dynamically similar motions, more especially of fluids, initiated respectively by Newton, Stokes (or Helmholtz), and Rayleigh. These three methods, viz., the integral, the differential, and the dimensional, are enough alike to be studied profitably together. They are treated in succession then compared. (author).
Three methods of calculating range and endurance of airplanes
This report develops new equations which give the range and endurance of airplanes with an accuracy equal to that obtained from a step-by-step integration of the flight. A method of obtaining equally satisfactory results from Brequet's equations is also given in detail. A third method of calculating range and endurance, derived by the writer for use in routine estimating in the Bureau of Aeronautics, is also given in full. The reports contains tables and curves arranged for convenient use and illustrates the three methods by comparative estimates.
Torsion of wing trusses at diving speeds
The purpose of this report is to indicate what effect the distortion of a typical loaded wing truss will have upon the load distribution. The case of high angle of incidence may be dismissed immediately from consideration as the loads on the front and rear trusses are balanced, and consequently there will be little angular distortion. A given angular distortion will have the maximum effect upon load distribution in the region of the angle of no-lift, because the slope of the lift curve is highest here, and it is here that the greatest angular distortion will occur, because the load on the front truss acts downward while the load on the rear truss acts upward.
The torsional strength of wings
This report describes a simple method for calculating the position of the elastic axis of a wing structure having any number of spars. It is shown that strong drag bracing near the top and bottom of a wing greatly increases the torsional strength. An analytical procedure for finding the contribution of the drag bracing to the torsional strength and stiffness is described, based upon the principle of least work, and involving only one unknown quantity. A coefficient for comparing the torsional rigidity of different wings is derived in this report.
Turbulence in the Air Tubes of Radiators for Aircraft Engines
This report describes an investigation of the characteristics of flow in the air passages of aircraft radiators. The work was done by the National Bureau of Standards for the National Advisory Committee for Aeronautics.
The twenty-foot propeller research tunnel of the National Advisory Committee for Aeronautics
This report describes in detail the new propeller research tunnel of the National Advisory Committee for Aeronautics at Langley Field, Va. This tunnel has an open jet air stream 20 feet in diameter in which velocities up to 110 M. P. H. Are obtained. Although the tunnel was built primarily to make possible accurate full-scale tests on aircraft propellers, it may also be used for making aerodynamic tests on full-size fuselages, landing gears, tail surfaces, and other aircraft parts, and on model wings of large size. (author).
Two practical methods for the calculation of the horizontal tail area necessary for a statically stable airplane
From Summary: "This report is concerned with the problem of calculation of the horizontal tail area necessary to give a statically stable airplane. Two entirely different methods are developed, and reduced to simple formulas easily applied to any design combination. Detailed instructions are given for use of the formulas, and all calculations are illustrated by examples. The relative importance of the factors influencing stability is also shown."
The Variable Density Wind Tunnel of the National Advisory Committee for Aeronautics
This report contains an exact description of the new wind tunnel of the National Advisory Committee for Aeronautics. This is the first american type wind tunnel. It differs from ordinary wind tunnels by its being surrounded by a strong steel shell, 35 feet long and 15 feet in diameter. A compressor system is provided to fill this shell - and hence the entire wind tunnel - with air compressed to a density up to 25 times the ordinary atmospheric density.
The Variation in Engine Power With Altitude Determined From Measurements in Flight With a Hub Dynamometer
"The rate of change in power of aircraft engines with altitude has been the subject of considerable discussion. Only a small amount of data from direct measurements of the power delivered by airplane engines during flight, however, has been published. This report presents the results of direct measurements of the power delivered by a Liberty 12 airplane engine taken with a hub dynamometer at standard altitudes from zero to 13,000 feet. Six flights were made with the engine installed in a modified DH-4 airplane" (p. 323).
The variation of aerofoil lift and drag coefficients with changes in size and speed
This report contains the results of an investigation into the effect of changes in size and speed upon aerofoil lift and drag coefficients. Certain empirical limitations to the interchangeability of v and l in the general equation of fluid resistance are pointed out and the existing methods of correcting for scale are criticized. New methods of correcting for scale by means of simple formulae are derived and checked by comparison with test results.
The vertical, longitudinal, and lateral accelerations experienced by an S. E. 5a airplane while maneuvering
"This investigation was carried out by the Langley Field Laboratory of the National Advisory Committee for Aeronautics for the purpose of measuring the accelerations along the three principal axes of an airplane while it was maneuvering. The airplane selected for this purpose was the fairly maneuverable SE-5A and the instruments used were the NACA three component accelerometer and the NACA recording airspeed meter. The results showed that the normal accelerations did not exceed 4.000 G. While the lateral and longitudinal accelerations did not exceed 0.60 G" (p.135).
Water Model Tests for Semirigid Airships
The design of complicated structures often presents problems of extreme difficulty which are frequently insoluble. In many cases, however, the solution can be obtained by tests on suitable models. These model tests are becoming so important a part of the design of new engineering structures that their theory has become a necessary part of an engineer's knowledge. For balloons and airships water models are used. These are models about 1/30 the size of the airship hung upside down and filled with water under pressure.
Water pressure distribution on a flying boat hull
This is the third in a series of investigations of the water pressures on seaplane floats and hulls, and completes the present program. It consisted of determining the water pressures and accelerations on a Curtiss H-16 flying boat during landing and taxiing maneuvers in smooth and rough water.
Water pressure distribution on a twin-float seaplane
This is the second of a series of investigations to determine water pressure distribution on various types of seaplane floats and hulls, and was conducted on a twin-float seaplane. It consisted of measuring water pressures and accelerations on a TS-1 seaplane during numerous landing and taxiing maneuvers at various speeds and angles. The results show that water pressures as great as 10 lbs. per sq. in.may occur at the step in various maneuvers and that pressures of approximately the same magnitude occur at the stern and near the bow in hard pancake landings with the stern way down. At the other parts of the float the pressures are less and are usually zero or slightly negative for some distance abaft the step. A maximum negative pressure of 0.87 lb. Per square inch was measured immediately abaft the step. The maximum positive pressures have a duration of approximately one-twentieth to one-hundredth second at any given location and are distributed over a very limited area at any particular instant.
Water-pressure distribution on seaplane float
The investigation presented in this report was conducted for the purpose of determining the distribution and magnitude of water pressures likely to be experienced on seaplane hulls in service. It consisted of the development and construction of apparatus for recording water pressures lasting one one-hundredth second or longer and of flight tests to determine the water pressures on a UO-1 seaplane float under various conditions of taxiing, taking off, and landing. The apparatus developed was found to operate with satisfactory accuracy and is suitable for flight tests on other seaplanes. The tests on the UO-1 showed that maximum pressures of about 6.5 pounds per square inch occur at the step for the full width of the float bottom. Proceeding forward from the step the maximum pressures decrease in magnitude uniformly toward the bow, and the region of highest pressures narrows toward the keel. Immediately abaft the step the maximum pressures are very small, but increase in magnitude toward the stern and there once reached a value of about 5 pounds per square inch. (author).
Wind Tunnel Balances
Report embodies a description of the balance designed and constructed for the use of the National Advisory Committee for Aeronautics at Langley Field, and also deals with the theory of sensitivity of balances and with the errors to which wind tunnel balances of various types are subject.
Wind Tunnel Studies in Aerodynamic Phenomena at High Speed
A great amount of research and experimental work has been done and fair success obtained in an effort to place airplane and propeller design upon an empirical basis. However, one can not fail to be impressed by the apparent lack of data available toward establishing flow phenomena upon a rational basis, such that they may be interpreted in terms of the laws of physics. With this end in view it was the object of the authors to design a wind tunnel differing from the usual type especially in regard to large power and speed of flow.
Wind Tunnel Tests on Autorotation and The "Flat Spin"
"This report deals with the autorotational characteristics of certain differing wing systems as determined from wind tunnel tests made at the Langley Memorial Aeronautical Laboratory. The investigation was confined to autorotation about a fixed axis in the plane of symmetry and parallel to the wind direction. Analysis of the tests leads to the following conclusions: autorotation below 30 degree angle of attack is governed chiefly by wing profile, and above that angle by wing arrangement" (p. 343).
Wing Spar Stress Charts and Wing Truss Proportions
"In order to simplify the calculation of beams continuous over three supports, a series of charts have been calculated giving the bending moments at all the critical points and the reactions at all supports for such members. Using these charts as a basis, calculations of equivalent bending moments, representing the total stresses acting in two bay-wing trusses of proportions varying over a wide range, have been determined, both with and without allowance for column effect. This leads finally to the determination of the best proportions for any particular truss or the best strut locations in any particular airplane" (p. 137).
Working Charts for the Selection of Aluminum Alloy Propellers of a Standard Form to Operate With Various Aircraft Engines and Bodies
"Working charts are given for the convenient selection of aluminum alloy propellers of a standard form, to operate in connection with six different engine-fuselage combinations. The charts have been prepared from full-scale test data obtained in the 20-foot propeller research tunnel of the National Advisory Committee for Aeronautics. An example is also given showing the use of the charts" (p. 3).
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