ALBERT

Description: This work covers the literatme published from January 1, 1920, to December 31, 1921, and continues the work of the Smithsonian Institution issued as Volume 55 of the Smithsonian Miscellaneous Collections, which covered the material published prior to June 30, 1909, and the work of Lhe National Advisory Committee for Aeronautics as published in the Bibliography of Aeronautics for the years 1909 to 1916 and 1917 to 1919. As in the Smithsonian volume and in the Bibliography of Aeronautics for the years 1909 to 1916 and 1917 to 1919, citations of the publications of all nations have been included in the languages in which these publications originally appeared. The arrangement is in dictionary form with author and subject entry and one alphabetical arrangement. Detail in the matter of subject reference has been omitted on account of the cost of presentation, but an attempt has been made to give sufficient cross reference for research in special lines. The National Advisory Committee for Aeronautics will next present a bibliography for the year 1922.

Description: The purpose of this treatise is, first of all, the determination of the effect of variously loaded spars on one another, since the neglect of this effect would present an economically very unfavorable computation method. The system of spars and cross-bars alone (whether solid or built-up) does not matter at first, the original assumption being that the spars are rigidly braced by the cross-bars.

Description: In this article, the phenomena of the upward component in the case of flat surfaces will be referred to as the "Lilienthal effect." The Lilienthal effect will be distinguished from the Knoller-Betz effect which is explained by means of vertical wind oscillations, at the basis of which, however, there lie air motions which the Lilienthal effect could not produce. It will be shown that the same cause, which can produce the Lilienthal effect on flat airfoils, considerably strengthens the thrust due to the Knoller-Betz effect.

Description: This report presents the results of various experiments carried out at the Gottingen Aerodynamic Institute. These include: experiments with Joukowski wing profiles; experiments on an airplane model with a built-in motor and functioning propeller; and the rotating cylinder (Magnus Effect).

Description: The "Bulletin Technique", of March, 1919, gave the results of tests and studies made up to that date in connection with airplane parachutes. This work has been continued.

Description: This report presents various methods for increasing the power of engines such as supercharging and turbocharging.

Description: Commander Le Prieur, whose flight experience in a low-speed seaplane we related in our number of September 27, 1924, invented, four years ago, an instrument destined to render very great service to aviators, namely, the "navigraph", designed to correct errors of orientation due to the effect of the winds during flight.

Description: The object of this article is to set forth the particular properties of swiftly-moving air, how these affect the installation of a wind tunnel, the experimental results already obtained, the possible applications of such a tunnel, and what can be easily accomplished at the present time.

Description: The following pages present a review of the air transportation activities of England, France, Germany and Holland, based on an inspection trip during the summer of 1924.

Description: We are undertaking the task of computing the air forces on a slightly cambered airfoil in the absence of friction and with an infinite aspect ratio. We also assume in advance that the leading edge is very sharp and that its tangent lies in the direction of motion.

Description: During the months of June to September, 1924, I personally visited the principal airports of Europe and traveled as a passenger some 6500 air miles on English, French, Romanian, Polish, German and Dutch air lines in order to investigate the development of commercial aviation abroad. The results of the investigation are embodied in a series of reports, of which a summary of the general findings is given below.

Description: Any measuring device, which immediately indicates the rate of fuel consumption in the desired units, has the advantage of saving considerable time and fuel, besides facilitating the adjustment of the carburetor. The Schiske "Konsummeter" (made by the "PS-Vergaser and Apparatebau A. G.") was designed from the above viewpoint.

Description: Attempts by other countries to develop patents for alloys similar to duralumin are presented. Duralumin is aluminum alloyed with 3.5-4.5% copper, 0.5% magnesium, and 0.25-1% of manganese.

Description: This article is based on the experience of the Schute-Lanz Airship Company in light construction. The object is to stimulate the employment of these methods in other fields of industry.

Description: This report begins with a review and analysis of the work being done to develop light airplanes in the U.S. and abroad. A technical discussion of the construction and innovations in light airplanes is then presented.

Description: The phenomenon of the Magnus effect consists in the fact that a revolving body moving relatively to the surrounding fluid (air) is subjected not only to drag (i.e., a force acting in a direction opposite to that of the direction of motion), but also to a lift.

Description: It has frequently been stated and written that in order to popularize light aircraft the first essential is the production of a reliable engine capable of being easily maintained and having a long life, at the same time selling at a low figure. It is desired to point out the difficulties in the way of realizing this ideal before remarking on the claims of the various types for adoption.

Description: Into the leading edge of a wing with arbitrary cross-section, there is introduced a cylinder, which can be rotated by an electric motor by means of a cord. Observations were made in the wind tunnel on how the lift at different wind velocities was affected by rotating this cylinder.

Description: This report details the procedure followed in establishing a general formula enabling the calculation of the maximum altitude attainable statically.

Description: The proof of the validity of the Reynolds law of similitude for the surface resistance of planes has been developed with an accuracy hitherto unattained and for a large range of lengths and speeds. It has been shown that, in addition to the form resistance, the resistance of the longitudinal edges must be taken into account.

Description: Suggestions are presented for the establishment of lecture courses on aviation.

Description: The calculation of wing spars of constant cross-section and load has been thoroughly treated by a large number of authors. Such is not the case,however, regarding the calculation of wing spars whose section and linear load diminish toward the ends, as in wings of trapezoidal contour and decreasing section.

Description: The economic costs and benefits of speed on airship traffic are calculated and different factors are considered.

Description: Descriptions of different models of airplanes that took part in the "Tour of France" cross-country race are listed.

Description: On the occasion of the formulation of the rules for testing the efficiency of ventilators and compressors, experiments were instituted by the subcommittee on ventilators for the production of suitable tubes for velocity and pressure measurements.

Description: The method of determining the pressure distribution on the fuselage is described, with special attention to how it is affected by the presence of the wings.

Description: Two series of experiments were tried, in order to determine the ignition point at any desired pressure, the first series at constant and the second at varying pressure. The results differ greatly and indicate that testing under pressure, in the investigation of liquid fuels, can be done best in the laboratory and that the determination of the ignition points in an open vessel furnishes no certain indication of the behavior of the fuel in the engine.

Description: This report gives the results of a recent series of experiments performed on a wing designed for a cantilever monoplane. Both wings were trapezial in their ground plan, with their tips rounded elliptically. These wing sections combine all known devices for increasing the lift, namely, the slot, the increased camber and angle of attack by means of an aileron running the whole length of the span. The last advance included in the wing section was an increase in wing area by means of an auxiliary wing adjusted by a sort of rectangular joint.

Description: For several kinds of wire gauze the difference in static, dynamic and total or absolute pressure in front of and behind the gauze were determined for comparison with the pressure drop caused by an airplane radiator, such gauze being used on airplane models to represent the radiator.

Description: In reality, the principle of similitude is not applicable to the hulls, the designing of which increases in difficulty with increasing size of the seaplanes. In order to formulate, at least in a general way, the basic principles of calculation, we must first summarize the essential characteristics of a hull with reference to its gradual enlargement. In this study, we will disregard hulls with wing stubs, as being inapplicable to large seaplanes.

Description: This report deals with an experimental investigation of the aerodynamical characteristics of airfoils at high speeds. Lift, drag, and center of pressure measurements were made on six airfoils of the type used by the air service in propeller design, at speeds ranging from 550 to 1,000 feet per second. The results show a definite limit to the speed at which airfoils may efficiently be used to produce lift, the lift coefficient decreasing and the drag coefficient increasing as the speed approaches the speed of sound. The change in lift coefficient is large for thick airfoil sections (camber ratio 0.14 to 0.20) and for high angles of attack. The change is not marked for thin sections (camber ratio 0.10) at low angles of attack, for the speed range employed. At high speeds the center of pressure moves back toward the trailing edge of the airfoil as the speed increases. The results indicate that the use of tip speeds approaching the speed of sound for propellers of customary design involves a serious loss in efficiency.

Description: 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.

Description: These experiments were made at the request of the Bureau of Aeronautics, Navy Department, to investigate the velocity of the air in the slipstream in horizontal and climbing flight to determine the form of expression giving the slipstream velocity in terms of the airspeed of the airplane. The method used consisted in flying the airplane both on a level course and in climb at full throttle and measuring the slipstream velocity at seven points in the slipstream for the whole speed range of the airplane in both conditions. In general the results show that for both condition, horizontal and climbing flights, the slipstream velocity v subscript 3 and airspeed v can be represented by straight lines and consequently the equations are of the form: v subscript s = mv+b where m and b are constant. (author)

Description: This report contains those results of the theory of wings and of wing sections which are of immediate practical value. They are proved and demonstrated by the use of the simple conceptions of "kinetic energy" and "momentum" only, familiar to every engineer; and not by introducing "isogonal transformations" and "vortices," which latter mathematical methods are not essential to the theory and better are used only in papers intended for mathematicians and special experts.

Description: The general purpose in this study was to determine the stresses in a wooden member subjected to combined beam and column action. What may be considered the specific purpose, as it relates more directly to the problem of design, was to determine the particular stress that obtains at maximum load which, for combined loading, does not occur simultaneously with maximum stress.

Description: In this report, the induced yawing moment, due to the rolling moment produced by the ailerons, is computed. This induced yawing moment is the greatest part of the entire yawing moment encountered by the wings.

Description: The purpose of the investigation covered by this report was the examination of the degree of approach which may be anticipated between laboratory tests on model airplane propellers and results computed by the airfoil theory, based on tests of airfoils representative of successive blade sections. It is known that the corrections of angles of attack and for aspect ratio, speed, and interference rest either on experimental data or on somewhat uncertain theoretical assumptions. The general situation as regards these four sets of corrections is far from satisfactory, and while it is recognized that occasion exists for the consideration of such corrections, their determination in any given case is a matter of considerable uncertainty. There exists at the present time no theory generally accepted and sufficiently comprehensive to indicate the amount of such corrections, and the application to individual cases of the experimental data available is, at best, uncertain. While the results of this first phase of the investigation are less positive than had been hoped might be the case, the establishment of the general degree of approach between the two sets of results which might be anticipated on the basis of this simpler mode of application seems to have been desirable.

Description: 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. (author)

Description: This report discusses the relation between the temperature of the air at the entrance to the carburetor and the power developed by the engine. Its scope is limited to a consideration of the range of temperatures likely to result from changes of season, locality, or altitude, since its primary aim is the finding of a satisfactory basis for correcting power measurements to a standard temperature. The tests upon which this report is based were made upon aviation engines in the Altitude Laboratory of the Bureau of Standards. From the results of over 1,600 tests it is concluded that if calculations be based on the assumption that the indicated horsepower of an engine varies inversely as the square root of the absolute temperature of the carburetor air the values obtained will check closely experimental measurements. The extent to which this relationship would be expected from theoretical considerations is discussed and some suggestions are given relative to the use of this relationship in correcting horsepower measurements. (author)

Description: The average velocity of helicopter blades relative to the air is greater than that of airplane wings. The helicopter may turn out to be more economical than the airplane wing for extreme velocities of horizontal flight, the airplane then requiring a very great speed range.

Description: Three groups of airfoils have been tested in the variable density wind tunnel. The first group contains three airfoils. The second group is a systematic series of twenty-seven airfoils. The third group consists of several frequently used wing sections.

Description: Following a curved path increases the distance to be flown, and a type of radio navigation that forces the adoption of such a path is therefore less efficient than one that marks out a definite straight line between the point of departure and the intended destination, and holds the airplane to that line. To determine the loss of efficiency resulting from curvature of the path, calculations were made for two particular cases by the method of step-by-step integration. The calculations were based on the assumption that the pilot makes straightforward use of his radio for navigation and makes no allowance for drift. Results are given in tabular form for two airplanes flying 200 miles at 100 mph, one with a cross wind of 50 mph wind across course, and the other with a 20 mph wind across course. It is shown that the following of the curved path increases the time of flight and the air distance flown by 17 percent and 2.5 percent in the two cases.

Description: Calculations of the magnitude of the correction factors and the range of their variations for wind tunnel models used in making aircraft performance predictions were made for 23 wind tunnel models. Calculated performances were compared with those actually determined for such airplanes as have been built and put through flight test. Except as otherwise noted, all the models have interplane struts and diagonal struts formed to streamwise shape. Wires were omitted in all cases. All the models were about 18 inches in span and were tested in a 4-foot wind tunnel. Results are given in tabular form.

Description: The following contains information on the air forces on a wing produced by it's pitching at a finite rate of angular velocity. The condition of smooth flow at the region of the trailing edge is maintained. The wing then experiences the same lift as if moving with the momentary velocity of the rear edge.

Description: A formula for the computation of the vertical velocity component on all sides of an airplane is deduced and discussed. The formation is of value for the interpretation of such free flight tests where two airplanes fly alongside each other to facilitate observation.

Description: The reduction of drag of an airfoil when the air stream is oscillating is called the Katzmayr effect. The purpose here is to offer a simple explanation of the cause of the Katzmayr effect.

Description: Discussed here are some discharge characteristics of a fuel injection system intended primarily for high speed service. The system consisted of a cam actuated fuel pump, a spring loaded automatic injection valve, and a connecting tube.

Description: 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.

Description: The design and construction of an altitude chamber, in which both pressure and temperature can be varied independently, was carried out by the NACA at the Langley Memorial Aeronautical Laboratory for the purpose of studying the effects of temperature and pressure on aeronautical research instruments. Temperatures from +20c to -50c are obtained by the expansion of CO2from standard containers. The chamber can be used for the calibration of research instruments under altitude conditions simulating those up to 45,000 feet. Results obtained with this chamber have a direct application in the design and calibration of instruments used in free flight research.

Description: In this paper the fundamental principles of the Flettner rotor ship (Reference I) are discussed in the light of the Kutta-Joukowski theory and available experimental information on the subject. A brief exposition of the Kutta-Joukowski theory is given and the speed of the rotor ship Buckau computed, first by using effective propulsive force obtained by the above theory, and then by direct application of wind tunnel data.

Description: The following note, prepared for the NACA, contains several remarks on the possible improvement of the experimental determination of the aerodynamic properties of wing sections. It shows how errors of observation can subsequently be partially eliminated, and how the computation of the maxima or minima of aerodynamic characteristics can be much improved.

Description: The tests described herein were made in 1918, in the old four-foot wind tunnel at the Massachusetts Institute of Technology and at the request of the Engineering Division of the U.S. Army Air Service. The results were given circulation only in official circles at that time. The interest of the work appears sufficient to justify its wider distribution even at this very late date.

Description: This note shows that the main part of the discrepancy between full flight propeller performance and the performance of models in a wind tunnel is due to a scale effect, and that a minor part is caused by body interference. Analyses are made of propeller performances on several standard airplanes, and the actual brake horsepower compared with the power as calculated from model test data. The calculated power is based on that absorbed by a wind tunnel propeller model which is geometrically similar to the full scale propeller and is operating under the same ratio of V/nD.

Description: In recent tests on the pressures occurring on the envelope and control surfaces of the naval airship C-7, it was noted that the pressures on the nose of the airship, while flying in level circling flight, were symmetrically distributed. Such a condition can only occur when the nose of the airship is pointed directly into the wind, and to accomplish this in circling flight, the axis of the airship must then be parallel to the direction of the motion of the nose. The question was raised as to whether the same conditions occur generally on all airships in circling flight. It appears that airships flying in a constant, level, circling flight path will generally head very closely into the wind, and any deviation will be so slight that the distribution of pressure over the nose will be but slightly, if at all, changed from a symmetrical distribution.

Description: Flight tests to determine lift and drag characteristics are discussed. A review is given of the fundamental principles on which the tests are based and on the forces acting on an airplane in the various conditions of steady flight. Glide with and without propeller thrust and the relation between angle of attack and the indicated airspeed for different conditions of steady flight are discussed. The glide test procedure and the problem of the propeller are discussed.

Description: The technical staff of the NACA at Langley Field, has made a series of free flight tests with a JN4h airplane in order to find the best place for an instrument for measuring the angle of attack. A "neutral zone" was found where the air remains either at rest relative to the undisturbed air beyond the influence of the airplane, or is set in motion parallel to the motion of the airplane. This zone is about midway between the two wings and slightly in front of, or at the vertical plane through the leading edges of the wings but the exact position as well as the outlines of the zone varies considerably as the conditions of flight change.

Description: This report is based upon engine tests made at the Bureau of Standards during 1920, 1921, 1922, and 1923. The majority of these tests were of aviation engines and were made in the Altitude Laboratory. For a small portion of the work a single cylinder experimental engine was used. This, however, was operated only at sea-level pressures. The report shows that an increase in break horsepower and a decrease in the pounds of fuel used per brake horsepower hour usually results from an increase in compression ratio. This holds true at least up to the highest ratio investigated, 14 to 1, provided there is no serious preignition or detonation at any ratio. To avoid preignition and detonation when employing high-compression ratios, it is often necessary to use some fuel other than gasoline. It has been found that the consumption of some of these fuels in pounds per brake horsepower hour is so much greater than the consumption of gasoline that it offsets the decrease derived from the use of the high-compression ratio. The changes in indicated thermal efficiency with changes in compression ratio are in close agreement with what would be anticipated from a consideration of the air cycle efficiencies at the various ratios. In so far as these tests are concerned there is no evidence that a change in compression ratio produces an appreciable, consistent change in friction horsepower, volumetric efficiency, or in the range of fuel-air ratios over which the engine can operate. The ratio between the heat loss to the jacket water and the heat converted into brake horsepower or indicated horsepower decreases with increase in compression ratio. (author)

Description: In connection with the standardization of instruments used in the wind tunnel, this investigation was undertaken to determine the nature and magnitude of the errors inherent in the measurement of air speed by a pitot tube when the instrument is mounted close to some other body. The mounting of the instrument in proximity to some other body is so frequent in flight and in wind tunnel research that it seemed advisable to investigate thoroughly the magnitude of the possible errors caused by such proximity. The results of this investigation will facilitate comparisons of the errors due to interference which have been reduced to percentages of the air-speed readings obtained under conditions of no interference.

Description: This investigation was carried out to determine the distribution of load over the wings of a high speed airplane under all conditions of flight. In particular it was desired to find the pressure distribution during level flight, over the portions of the wings in the slipstream and, during violent maneuvers, over the entire wing surface. The method used consisted in connecting a number of holes in the surface of the wings to recording multiple manometers mounted in the fuselage of the airplane. In this way simultaneous records could be taken on all of the holes for any desired length of time. (author)

Description: This report describes a series of experiments undertaken to determine whether or not the electrical characteristics of the igniting spark have any effect on the rapidity of flame spread in the explosive gas mixtures which it ignites. The results show very clearly that no such effect exists. The flame velocity in carbon-monoxide oxygen, acetylene oxygen, and gasoline-air mixtures was found to be unaffected by changes in spark intensity from sparks which were barely able to ignite the mixture up to intense condenser discharge sparks having fifty time this energy. (author)

Description: This report is a study of a test data on a family of Durand's propellers (nos. 3, 7, 11, 82, 113, 139), which is fairly representative of conventional design. The test data are so plotted that the proper pitch and diameters for any given set of conditions are readily obtained. The same data are plotted in other forms which may be used for calculating performance when the ratio of pitch to diameter is known. These new plots supply a means for calculating the performance, at any altitude, of airplanes equipped with normal or supercharged engines. The coefficients used and the methods of plotting adopted in this report coordinate the results of a few tests into complete families of curves covering the entire range of p/d ordinarily used. This method of analyzing test data enables an investigator to plan tests systematically and leads to useful application of test data.

Description: At the request of the Bureau of Aeronautics, Navy Department, the National Advisory Committee for Aeronautics at Langley Field is investigating the get-away characteristics of an N-9H, a DT-2, and an F-5l, as representing, respectively, a single float, a double float, and a boat type of seaplane. This report covers the investigation conducted on the N-9H. The results show that a single float seaplane trims aft in taking off. Until a planing condition is reached the angle of attack is about 15 degrees and is only slightly affected by controls. When planing it seeks a lower angle, but is controllable through a widening range, until at the take-off it is possible to obtain angles of 8 degrees to 15 degrees with corresponding speeds of 53 to 41 M. P. H. or about 40 per cent of the speed range. The point of greatest resistance occurs at about the highest angle of a pontoon planing angle of 9 1/2 degrees and at a water speed of 24 M. P. H.

Description: 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.

Description: Tests have recently been made at Langley Memorial Aeronautical Laboratory to ascertain whether the aerodynamic characteristics of an airfoil might be substantially improved by imposing certain limitations upon the air flow about its tips. All of the modified forms were slightly inferior to the plain airfoil at small lift coefficients: however, by mounting thin plates, in planes perpendicular to the span, at the wing tips, the characteristics were improved throughout the range above three-tenths of the maximum lift coefficient. With this form of limitation the detrimental effect was slight; at the higher lift coefficients there resulted a considerable reduction of induced drag and consequently, of power required for sustentation. The slope of the curve of lift versus angle of attack was increased.

Description: This report, the second of a series of reports relating to the general subject of instrument diaphragms. The first report of the series was published as Technical Report no. 165, "diaphragms for aeronautic instruments," and comprised an outline of historical developments and theoretical principles. The present report relates entirely to nonmetallic diaphragms, the use of which in certain types of pressure elements has been increasing for some time. Little, if any, information has been available to aid the designer of instruments using this form of pressure element. It was to attempt to meet the need for such information that the investigation reported in this paper was undertaken. The report describes the various materials which have been used as nonmetallic diaphragms, discusses the factors which affect the performance of the diaphragms and gives the results of tests made for the purpose of investigating the effect produced by these factors.

Description: The astronomical method of determining position is universally used in marine navigation and may also be of service in aerial navigation. The practical application of the method, however, must be modified and adapted to conform to the requirements of aviation. Much of this work of adaptation has already been accomplished, but being scattered through various technical journals in a number of languages, is not readily available. This report is for the purpose of collecting under one cover such previous work as appears to be of value to the aerial navigator, comparing instruments and methods, indicating the best practice, and suggesting future developments. The various methods of determining position and their application and value are outlined, and a brief resume of the theory of the astronomical method is given. Observation instruments are described in detail. A complete discussion of the reduction of observations follows, including a rapid method of finding position from the altitudes of two stars. Maps and map cases are briefly considered. A bibliography of the subject is appended.

Description: This report contains a series of charts which were developed in order to simplify the estimation of airplane performance. Charts are given for estimating propeller diameter and efficiency, maximum speed, initial rate of climb, absolute ceiling, service ceiling, climb in 10 minutes, time to climb to any altitude, maximum speed at any altitude, and endurance. A majority of these charts are based on the equations given in NACA Technical Report no. 173. Plots of pressure and density against altitude in standard air are also given for convenience. It must be understood that the charts giving propeller diameter, maximum speed, initial rate of climb, absolute ceiling, and speeds at altitudes are approximations subject to considerable error under certain conditions. These particular charts should not be used as a substitute for detailed calculations when accuracy is required, as, for example, in military proposals. (author)

Description: The tests upon which this report is based were made at the Bureau of Standards between October 1919 and May 1923. From these it is concluded that: (1) with gasoline as a fuel, maximum power is obtained with fuel-air mixtures of from 0.07 to 0.08 pound of fuel per pound of air; (2) maximum power is obtained with approximately the same ratio over the range of air pressures and temperatures encountered in flight; (3) nearly minimum specific fuel consumption is secured by decreasing the fuel content of the charge until the power is 95 per cent of its maximum value. Presumably this information is of most direct value to the carburetor engineer. A carburetor should supply the engine with a suitable mixture. This report discusses what mixtures have been found suitable for various engines. It also furnishes the engine designer with a basis for estimating how much greater piston displacement an engine operating with a maximum economy mixture should have than one operating with a maximum power mixture in order for both to be capable of the same power development.

Description: Report includes the National Advisory Committee for Aeronautics letter of submittal to the president, congressional report, summaries of the committee's activities and research accomplished, bibliographies, and financial report.

Description: This investigation was carried out by the National Advisory Committee at Langley Field for the purpose of determining the adaptability of the camera obscura to the securing of turning characteristics of airships, and also of obtaining some of those characteristics of the C-7 airship. The method consisted in flying the airship in circling flight over a camera obscura and photographing it at known time intervals. The results show that the method used is highly satisfactory and that for the particular maneuver employed the turning diameter is 1,240 feet, corresponding to a turning coefficient of 6.4, and that the position of zero angle of yaw is at the nose of the airship.

Description: In this report it is shown that determining the instantaneous angle of pitch, the acceleration of the gust is as important as its maximum velocity or yaw. Hitherto it has been assumed that the conditions encountered in gusts could be approximately represented by considering the airship to be at an instantaneous angle of yaw or pitch (according to whether the gust is horizontal or vertical), the instantaneous angle being tan to the (-1) power (v/v), where v is the component of the velocity of the gust at right angles to the longitudinal axis of the ship, and v is the speed of the ship. An expression is derived for this instantaneous angle in terms of the speed and certain aerodynamic characteristics of the airship, and of the maximum velocity and the acceleration of the gust, and the application of the expression to the determination of the forces on the ship is illustrated by numerical examples.

Description: This work on accelerometry was done at McCook Field for the purpose of continuing the work done by other investigators and obtaining the accelerations which occur when a high-speed pursuit airplane is subjected to the more common maneuvers. The accelerations obtained in suddenly pulling out of a dive with well-balanced elevators are shown to be within 3 or 4 per cent of the theoretically possible accelerations. The maximum acceleration which a pilot can withstand depends upon the length of time the acceleration is continued. It is shown that he experiences no difficulty under the instantaneous accelerations as high as 7.8 G., but when under accelerations in excess of 4.5 G., continued for several seconds, he quickly loses his faculties.

Description: In the first article, in connection with a lecture on the hydrodynamic basis of flight and the potential flow about a Joukowski wing, the pressure distribution on several wings is computed and plotted. The diagrams of the pressure distributions are presented accompanied with a qualitative discussion of the pressure distribution. In the second article, the the cross-sectional outline (or profile) a Joukowski wing are plotted.

Description: Every strength calculation, including those on airplanes, must be preceded by a determination of the forces to be taken into account. In the following discussion, it will be assumed that the magnitudes of these forces are known and that it is only a question of how, on the basis of these known forces, to meet the prescribed conditions on the one hand and the practical requirements on the other.

Description: Economic and design characteristics are examined in the design of airplanes and airships.

Description: The designing of an airplane requires an accurate knowledge of the aerodynamic properties of its wings, as expressed in the polar diagram. It is important to continue the theoretical researches on the aerodynamic phenomena of wings, in order to determine by calculation, their fundamental characteristics and to increase and formulate our knowledge in this field.

Description: The extensive applicability of the hydrodynamic theory to the problems of engine construction is clearly shown in the following attempt to determine by exact methods the nature of the flow in valves under variously restricted conditions. Observation shows that two principal kinds of flow occur in simple flat-seated valves. For small valve lifts, the flow is along the horizontal wall and is therefore deflected 90 degrees, but for greater valve lifts the flow separates and forms a free stream, whose angle of deflection naturally increases with increasing lift. Both these kinds of flow can, in fact, be theoretically explained

Description: The elimination of the rigid supports for models and their replacement by wires constitute a great improvement by rendering negligible the interactions of support. There are disadvantages to wire, namely, the aerodynamic resistance is very large and their use is rather difficult because the whole suspension lacks rigidity and easily becomes distorted. We will here investigate the nature of these distortions, evaluate the errors they entail and describe the methods for taking account of or avoiding them.

Description: In order that the method may be more easily understood, we will first consider the simpler case when there is no lift, but only drag, and when the streamlines at the measuring point behind the obstacle are nearly parallel. Moreover, the flow is assumed not to deviate much from the two-dimensional flow.

Description: The stressing of an airship depends on three nonuniformly distributed forces: air forces; the distribution of acceleration forces; and how the air pressure is distributed on the hull. This report examines the stresses and comes to conclusions on the size of airships.

Description: Before attempting to construct a human-powered aircraft, the aviator will first try to post himself theoretically on the possible method of operating the flapping wings. This report will present a graphic and mathematical method, which renders it possible to determine the power required, so far as it can be done on the basis of the wing dimensions. We will first consider the form of the flight path through the air. The simplest form is probably the curve of ordinary wave motion. After finding the flight curve, we must next determine the change in the angle of attack while passing through the different phases of the wave.

Description: This report details the contest to design and build concrete airship hangers. The difficulty lies in the magnitude of the absolute dimensions. An airship shed must withstand two principal types of stresses: those resulting from its own weight and those due to the wind. This report discusses both problems in detail.

Description: This report deals mainly with the methods of construction employed when after the plan had been approved. The foundation, side walls, doors and roof are all discussed and the economic savings resulting from this method of construction.

Description: In the present treatise we will consider chiefly the problem of solid injection in comparison with air injection. On leaving the valve or nozzle through one or more small openings, the fuel is split up into innumerable fine drops, which penetrate the combustion chamber in divergent directions in the form of a conical jet. The efficiency of this jet is judged from the following three viewpoints: 1) with respect to the fineness of atomization; 2) with respect to the direction or distribution of sprayed particles; 3) with respect to the penetration of the particles.

Description: This report briefly recounts the history of British commercial aviation and then goes on to look at the equipment, governmental relations, operations, and air traffic.

Description: T.M. 311 gave a short outline of modern theoretical aerodynamics as applied to light airplane design. This discussion may have been somewhat obscure to the nontechnical reader. A series of charts or curves should serve to clear up such obscurity as well as to more definitely emphasize those quantities most important for each flight characteristic.

Description: This article presents the observations of the authors on an inspection trip of the Latecoere Air Lines routes from Southern France into North Africa.

Description: This report provides a critical discussion of the results of the experiments conducted in the previous NACA-TM's 329 and 330. The main object of this investigation was to determine the size of the drops in mechanical atomization.

Description: This report describes the design and operation of a nozzle to inject fuel into an engine. The design of the nozzle is open, without any compulsory or automatic stop-valve. The fuel injection is regulated simply by the pressure and the adjustment of the fuel pump.

Description: It is the object of this report to review briefly the aerodynamic and construction data already available and to set forth the difficulties which must be met.

Description: Torsional creep and creep recovery behavior of organic liquids