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A Short Method of Calculating Torsional Stresses in an Airplane Fuselage
"This report deals with an investigation carried out in the Civil Engineering Laboratory of the University of California, to determine the accuracy of existing methods of computing the stresses in an airplane fuselage when subjected to torsion, and to derive a simple approximate formula for the rapid calculation of these stresses. The formula is derived by using the customary least work equation and considering each bay separately" (p. 1).
The Short S.7 "Mussel": A Training Seaplane With 65 Hp. "Cirrus" Engine
Circular presenting a description of the Short "Mussel" S.7, which is designed for use as a light training airplane of robust and simple construction. Information regarding the design, blueprints, and photographs are provided.
Shortening the Landing Run
Methods for shortening the landing run are discussed as well as the need for more emergency landing fields that will, by necessity, have to be short fields.
Shorter Contributions to General Geology, 1928
From introduction: The district discussed in this report embraces the entire northern peninsula of Michigan and the parts of northern Wisconsin and northeastern Minnesota that were covered by a re-advance of the Superior lobe of the Labrador ice sheet late in the Wisconsin stage of glaciation.
Significance of the expression CL³/CD²
Report presenting an analysis of the title coefficient as used in Kahn's formula for the ceiling.
The Sikorsky Twin Engined Amphibian, Type S-38, Model 1928
The S-38, model 28 is a nine passenger Sesquiplane powered by two Pratt and Whitney Wasp 410 HP engines and is intended for routes where the ability to take off and land from both land and water is essential. A description of the weight, construction, power plant, fuel system, landing gear, hull and floats, dimensions, flight characteristics, blueprints, and photographs are provided.
Similitude tests on wing sections
Report presenting an exploration of the application of model test results to full size construction, which assumes that either the resistance varies as the square of the speed within, the range of speeds in question or that the mechanical similarity law is fulfilled by the model test. The latter requires that the relation of airflow to the model be exactly like that for the large machine.
Simple formula for estimating airplane ceilings
From Summary: "The aeronautical engineer often has occasion to estimate the absolute ceiling of an airplane for which a detailed performance calculation is out of the question. In such cases it is customary to use either empirical performance charts or formulae. The performance charts given in several of the recent works on aeronautics are satisfactory so long as the airplane under consideration does not depart too far from the average in its characteristics. The formulae, with one exception, are no better. Given here is that exception, with indications of which terms of the formula may be neglected without seriously affecting the results, thus simplifying the task."
Simple Means for Saving Fuel on Traffic Flights
Report presenting a discussion of ways to save fuel on traffic flights, including some calculations that can be used for determining fuel efficiency. The primary ways of lessening fuel consumption include flying with a throttled engine and diminished speed.
Simplified Propeller Design for Low-Powered Airplanes
"The object of this report is to furnish the designer and builder of small airplanes a simple system for designing the propeller and making the drawing. An empirical design method is used, based on tests of model propellers in a wind tunnel and full scale tests of propellers in flight. The actual designing is accomplished by means of charts and involves very little calculation" (p. 1).
Simplified theory of the magneto
From Summary: "This paper contains part of the results of ignition investigations being made for the National Advisory Committee for Aeronautics at the Bureau of Standards, and describes a type of circuit which has been found useful for representing the action of high-tension magneto. While this equivalent circuit is relatively simple, and consequently can be used as a basis for deriving definite mathematical formulas for induced voltages and similar quantities, it has been found experimentally to correspond quite closely in its performance with the highly complicated electrical circuits of an actual magneto. In the paper formulas are given for the voltage induced in the secondary under various conditions of operation, and a number of numerical examples are worked out showing the application of the equations to a variety of practical problems."
The Simplifying Assumptions, Reducing the Strict Application of Classical Hydrodynamics to Practical Aeronautical Computations
Note presenting a general method followed to simplify the numerical work in hydrodynamics, which consists of neglecting quantities of a lower order of magnitude. Four of the solutions covered in this report include the theory of the lateral air forces on airship hulls, theory of wing sections in a two-dimensional flow, theory of wings with a finite span, and propeller theory.
The six-component wind balance
Dr. Zahm's report is a description of the six-component wind-tunnel balance in use at the Aerodynamic Laboratory, Washington Navy Yard. The description of the balance gives the mechanical details and the method of operation, and is accompanied by line drawings showing the construction of the balance. The balance is of particular interest, as it allows the model to be set up quickly and accurately in roll, pitch, and yaw, without stopping the wind. It is possible to measure automatically, directly, and independently the drag, cross-wind force, and lift; also the rolling, pitching, and yawing moments. It is also possible to make the balance self-recording.
Sixth Meeting of the Members of the German Scientific Association for Aeronautics
Report presenting a description of a meeting of the German Scientific Association for Aeronautics. The topics that were discussed are described.
Skin frictional resistance of plane surfaces in air: Abstract of recent German tests, with notes
Given here is the most recent research on skin frictional resistance of plane surfaces in air that was conducted by Dr. Wieselsberger under the direction of Dr. Prandtl of Gottingen University. In all, 16 models were tested. These were divided into four groups, as follows: 1) cloth, in the original condition; 2) cloth, with the nap singed off; 3) cloth, with three coats of dope; and 4) cloth, with six coats of dope. Each group consisted of four models of uniform width, 1 meter, and of lengths of 0.5, 1.0, 1.5, and 2.0 meters.
Slip-Stream Corrections in Performance Computation
This report is an analysis of experiments performed by Eiffel on the air velocity in slip stream of a propeller, and also includes a theoretical discussion of the magnitude of the velocity in different propellers.
Slip Stream Effect
"The horizontal tail surfaces of a new airplane usually are proportional so that the curve of moment about the center of gravity, combined with a similar curve for the wings alone, gives a composite curve which provides a certain specified degree of static stability. With the application of power three additional factors must be considered in calculations: the moment of the propeller thrust; the change in the velocity of the air over the tail due to the slipstream; and the change in direction of the air over the tail due to the slipstream. The last two factors are considered in this report" (p. 1).
Slotted-Wing Airplanes
Different applications of the slotted-wing principle are discussed as well as the advantages of using them. Slotted-wings are provided as a promising solution to the problem of needing to increase flight speed for aircraft while also decreasing landing speed.
The Small Angular Oscillations of Airplanes in Steady Flight
"This investigation was carried out by the National Advisory Committee for Aeronautics at the request of the Army Air Service to provide data concerning the small angular oscillations of several types of airplanes in steady flight under various atmospheric conditions. The data are of use in the design of bomb sights and other aircraft instruments. The method used consisted in flying the airplane steadily in one direction for at least one minute, while recording the angle of the airplane with the sun by means of a kymograph" (p. 283).
The Small Diesel Engine as an Automotive Engine
Essential principles for building small diesel engines and also structural details so far as feasibility are presented.
Soaring flight and the Rhön contests
Explanation of soaring flight. Static and dynamic soaring flight. Results of the Rhon contest. Description of the most important gliders. Notes on Soaring Flight Contests in France and England.
Soaring Flight in Guinea
Report discusses information obtained from studying large birds that fly by soaring, which involves using the wind without moving their wings. An Egyptian vulture and African white-backed vulture were observed and their relative air speed, upward air velocity, lift, and drag were noted. The experimental methods for measuring these values are described.
Soaring Without Rising Currents
Memorandum describing the main problem of soaring flight, which is that it is difficult to maintain altitude and to engage in indefinite continuation of flight without dependence on rising currents from any source. The best chance of success involves utilizing energy stored in the air when the wind speed is constantly and rapidly varying.
Some Aspects of the Comparison of Model and Full-Scale Tests
This paper was delivered before the Royal Aeronautical Society as the 1925 Wilbur Wright Memorial lecture. It treats the subject of scale effect from the standpoint of the engineer rather than the physicist, in that it shows what compromises are necessary to secure satisfactory engineering model test data and how these test data compare with full scale or with theoretical values. The paper consists essentially of three parts: (1) a brief exposition of the theory of dynamic similarity, (2) application of the theory to airplane model tests, illustrated by test data on airfoils from the National Advisory Committee for Aeronautics variable-density wind tunnel, and (3) application of the theory to propeller testing, illustrated by comparisons of model and full-scale results.
Some effects of air flow on the penetration and distribution of oil sprays
Tests were made to determine the effects of air flow on the characteristics of fuel sprays from fuel injection valves. Curves and photographs are presented showing the airflow throughout the chamber and the effects of the air flow on the fuel spray characteristics. It was found that the moving air had little effect on the spray penetration except with the 0.006 inch orifice. The moving air did, however, affect the oil particles on the outside of the spray cone. After spray cut-off, the air flow rapidly distributed the atomized fuel throughout the spray chamber.
Some Experiments on Autorotation of an Airfoil
"These experiments show that the rate of auto rotation of a monoplane airfoil is reduced by sweepback, ceasing entirely when the sweepback is 30 degrees. In addition a very serious increase in rate and range of auto rotation with yaw is shown" (p. 1).
Some factors affecting the reproducibility of penetration and the cut-off of oil sprays for fuel-injection engines
This investigation was undertaken at the Langley Memorial Aeronautical Laboratory in connection with a general research on fuel-injection for aircraft. The purpose of the investigation was to determine the factors controlling the reproducibility of spray penetration and secondary discharges after cut-off. The development of single sprays from automatic injection valves was recorded by means of special high-speed photographic apparatus capable of taking 25 consecutive pictures of the moving spray at a rate of 4,000 per second. The effect of two types of injection valves, injection-valve tube length, initial pressure in the injection-valve tube, speed of the injection control mechanism, and time of spray cut-off, on the reproducibility of spray penetration, and on secondary discharges were investigated. It was found that neither type of injection valve materially affected spray reproducibility. The initial pressure in the injection-valve tube controlled the reproducibility of spray penetrations. An increase in the initial pressure or in the length of the injection-valve tube slightly increased the spray penetration within the limits of this investigation. The speed of the injection-control mechanism did not affect the penetration. Analysis of the results indicates that secondary discharges were caused in this apparatus by pressure waves initiated by the rapid opening of the cut-off valve. The secondary discharges were eliminated in this investigation by increasing the length of the injection-valve tube. (author).
Some Factors of Airplane Engine Performance
This report is based upon an analysis of a large number of airplane-engine tests. It contains the results of a search for fundamental relations between many variables of engine operation. The data used came from over 100 groups of tests made upon several engines, primarily for military information. The types of engines were the Liberty 12 and three models of the Hispano-Suiza. The tests were made in the altitude chamber, where conditions simulated altitudes up to about 30,000 feet, with engine speeds ranging from 1,200 to 2,200 r.p.m.
Some German Gliders of 1920-1923
Memorandum presenting a review of some of the German gliders produced from 1920-1923. The designs, flight characteristics, and descriptions of successful flights are provided.
Some Impressions of the Paris Aero Show
Memorandum presenting a description of the Paris Aero Show and some of the aircraft that the author observed there. A specific description of some of the designs is provided, as well as some technical drawings of particular elements of these aircraft.
Some New Aerodynamical Relations
This report contains three new relations extending the modern theory of aeronautics. The first part contains a relation between the power absorbed by an aerofoil and the power absorbed by a propeller. In the second part the exactness of the ordinary formula for the induced drag of an aerofoil is examined and the error is determined. In the third part the author shows that for the calculation of the air forces on bodies of considerable volume the imaginary sources and sinks equivalent to the flow around the body can be used in the same way as vortices are used for the calculation of lift and induced drag of wings.
Some New Tests at the Gottingen Laboratory
The tests at the Gottingen laboratory included: friction tests on a surface treated with emaillite, verification tests on the M.V.A. 356 wing, and comparative tests of wing no. 36 at the Eiffel laboratory. The examination of all these experiments leads to the belief that, at large incidences, the speeds registered by the suction manometer of the testing chamber of the Eiffel laboratory wind tunnel are, owing to pressure drop, greater than the actual speeds. Therefore, the values of k(sub x) and k(sub y) measured at the Eiffel laboratory at large incidences are too low.
Some Notes on Gasoline-Engine Development
Experiments were carried out using a special engine with small glass windows and a stroboscope to record various aspects of engine performance. Valve position, supercharging, and torque recoil were all investigated with this experimental apparatus.
Some Principles Governing the Establishment of Meteorological Stations Along Air Routes
The organization of a meteorological service for an air route involves the solution of two distinct problems: distribution and grouping of meteorological stations and communications. Experience gained in the establishment of two lines, Paris-Warsaw and Constantinople-Bucharest enables us to establish certain principles, which may be of interest to note here.
Some Principles Governing the Production of Oil Wells
From Introduction: "The report discusses some of the fundamental factors governing oil production, taking up first the conditions affecting the amount of oil in the oil sand, then those factors that control the rate of production of oil wells, and then discusses several related problems, most of which deal particularly with the effect of the production of one well on that of another."
Some Problems on the Lift and Rolling Moment of Airplane Wings
This report deals with the application of the airfoil and twisted wing theory to the calculation of the lift and rolling moment of airplane wings. Most of the results arrived at are strictly true only for wings of elliptic plan form. The investigation aims to give some indications of the accuracy with which the results can be applied to the wing forms in actual use.
Some Remarks Concerning Soaring Flight
The publication of the following details is due to the desire of the editor to have the problems of soaring flight treated on the occasion of the Rhone Soaring Flight Contest. Soaring flight is defined as motorless flight without loss of height. Some calculations are provided in order to maximize the potential effects of wind and air currents.
Some Studies on the Aerodynamic Effect of the Gap Between Airplane Wings and Fuselages
"The general result indicated by this study is that if desirable from any viewpoint the gap between wing and fuselage may be closed without detrimental aerodynamic effects, and with a given monoplane there is less drag if the wing is directly on top of the fuselage than if it is parasol" (p. 1).
Some Tables of the Factor of Apparent Additional Mass
"This note, prepared for publication by the National Advisory Committee for Aeronautics, is a collection of the tables of the factor of apparent mass that have been published up to now. The theory of the motion of solids in a perfect fluid is of the greatest value for the study of most aerodynamic problems, and the additional apparent mass of an immersed solid is the most important characteristic for such theoretical numerical computations. It will therefore be helpful to have the most important values of the apparent mass - for some elementary cases - collected in a convenient form" (p. 1).
Sources of Limestone, Gypsum, and Anhydrite for Dusting Coal Mines to Prevent Explosions
From Preface: "The writer began testing the rock-dusting method for the Bureau of Mines at the Pittsburgh gallery in 1909, and later continued such testing in the bureau's experimental mine, with favorable results. Beginning in 1911 the bureau issued reports recommending rock dusting as alternative to watering."
The Spacing of Orifices for the Measure of Pressure Distributions
"The following report has been prepared for publication by the NACA. Suitable locations of orifices for the measurement of pressure distributions have been discussed. Tables are given for quickly laying out these locations and for quickly and easily computing the resultant air forces from the result of the measurements" (p. 1).
The Span as a Fundamental Factor in Airplane Design
Previous theoretical investigations of steady curvilinear flight did not afford a suitable criterion of "maneuverability," which is very important for judging combat, sport and stunt-flying airplanes. The idea of rolling ability, i.e., of the speed of rotation of the airplane about its X axis in rectilinear flight at constant speed and for a constant, suddenly produced deflection of the ailerons, is introduced and tested under simplified assumptions for the air-force distribution over the span. This leads to the following conclusions: the effect of the moment of inertia about the X axis is negligibly small, since the speed of rotation very quickly reaches a uniform value.
Spark Plug Defects and Tests
The successful operation of the spark plug depends to a large extent on the gas tightness of the plug. Part 1 of this report describes the method used for measuring the gas tightness of aviation spark plugs. Part 2 describes the methods used in testing the electrical conductivity of the insulation material when hot. Part 3 describes the testing of the cold dielectric strength of the insulation material, the resistance to mechanical shock, and the final engine test.
The sparking voltage of spark plugs
This report has been prepared in order to collect and correlate into convenient and useful form the available data on this subject. The importance of the subject lies in the fact that it forms the common meeting ground for studies of the performance of spark generators and spark plugs on the one hand and of the internal combustion engines on the other hand. While much of the data presented was obtained from various earlier publications, numerous places were found where necessary data were lacking, and these have been provided by experiments in gasoline engines at the Bureau of Standards.
Special Propeller Protractor
A special protractor was designed and built with a view towards supplying a simple, inexpensive, practical, portable instrument for making measurements to detect propeller warpage under practically all conditions, without the use of auxiliary equipment, and without having to remove the propeller from the airplane. A detailed description is given of the protractor. Techniques for measuring are described. Directions are given on how to use the protractor to set detachable blade-type propellers on an airplane.
Specializing for Record-Breaking
This report seeks to determine what constitutes airplane performance and what line should be followed in seeking to break records if the designer is given a free hand. Some of the considerations for designers include the ratio of engine power to wing area, minor refinements, low wing loading, and duration.
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."
Speed Limits of Aircraft
This paper is restricted to the question of attainable speed limits and attacks the problem from different angles. Theoretical limits due to air resistance are presented along with design factors which may affect speed such as wing loads, wing areas, wing section shifting, landing speeds, drag-lift ratios, and power coefficients.
Speed Measurements Made by Division "A" of the Airplane Directorate (Flugzeugmeisterei), Subdivision for Flight Experiments
"The various speeds of an airplane can only be measured in horizontal flight, since there are no means for measuring the angle of ascent or descent. The measurements must be corrected for the density of the air. This is obtained by simultaneous pressure and temperature measurements during flight" (p. 1).
Sphere Drag Tests in the Variable Density Wind Tunnel
The air forces on a twenty-centimeter sphere were measured after it had been rebuilt as an open throat type. The results from tests made at widely different densities and airspeeds and also on a smaller sphere are given. The conclusions are that approximately the same drag coefficient is obtained at a given value of the Reynolds number irrespective of what combination of the variables is used to obtain that value and that the turbulence of the air stream at the test section, as measured by the critical Reynolds number of a sphere, is less for the new tunnel than for the old one.
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