National Advisory Committee for Aeronautics (NACA) - 380 Matching Results

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Coefficients of Flow of Standard Nozzles: We first undertook experiments with air, devoted principally to the investigation of the disturbances due to the differences in the nature of the flow to the nozzle. The difficulty of measuring the air, however, caused us to experiment with water. Due to the possibility of measuring the capacity of the container, this method was much more accurate than measuring with Pitot tobes.
Combating Airplane Fires: This report provides a summary of the important steps to be taken in combating airplane fires. Some considerations and ways of preventing fires from developing are provided.
Contribution to the Study of Normal Burning in Gaseous Carbureted Mixtures: Part 1: In the present study it is proposed to provide an equipment permitting the study of the propagation of the region of reaction in mixtures of air and carbureted gases enclosed within a cylinder. Ignition is produced at the end of compression by an electric spark. With this apparatus it is proposed to determine: 1) the influence of the richness of the explosive mixture on the rate of flame propagation; 2) the influence of the degree of volumetric compression on one of the hydrocarbons; 3) the influence of the variation of initial temperature of the mixture before compression; 4) the influence of tetraethyl-lead on the propagation - notably on the formation of the explosive wave.
Contribution to the Study of Normal Burning in Gaseous Carbureted Mixtures: Part 2: Memorandum presenting the experimental results of tests to confirm the contribution to the study of normal burning in gaseous carbureted mixtures.
Structural Details of the Giant Dornier Seaplane "Do X.": Memorandum presenting a description of the Dornier seaplane Do X. Details of the general description, materials, details of the main wing and upper wing, details of the hull and of the wing stubs, tail surfaces and control lines, power plant, and launching car and floating dock are provided.
Experimental Investigations Concerning the Limits of Detonation in Gaseous Mixtures: Part 1: Memorandum presenting an investigation to determine quantitatively the limits of detonation in gaseous mixtures for the conditions imposed and for a number of given gaseous explosive mixtures.
Experimental Investigations Concerning the Limits of Detonation in Gaseous Mixtures: Part 2: Memorandum presenting an investigation concerning the limits of detonation in gaseous mixtures. In regards to the results, by progressive dilution of the explosive, the course of the chemical reaction becomes slower and slower until finally the transformation within the reaction zone becomes so slow that it is not there completed.
Relation Between the Stability Characteristics and the Controllability of German Airplanes: This survey is intended to give a general approximate idea of the stability and controllability of German airplanes. Both flight characteristics, including the behavior of the airplane under the action of deflected controls and external disturbances, and flight performance, which refers to climbing, speed, take-off, and landing qualities.
The Relation Between the Tensile Strength and the Hardness of Metals: This report presents methods determining the hardness and tensile strength of metals by showing the effect and dependence of the hardness numbers on the strain-hardening. Relations between the hardness numbers and the ordinary stress-strain diagrams and tensile strength are given. Procedures for finding the Brinell strength are also presented.
The Boundary Layer as a Means of Controlling the Flow of Liquids and Gases: According to one of the main propositions of the boundary layer theory the scarcely noticeable boundary layer may, under certain conditions, have a decisive influence on the form of the external flow by causing it to separate from the wing surface. These phenomena are known to be caused by a kind of stagnation of the boundary layer at the point of separation. The present report deals with similar phenomena. It is important to note that usually the cause (external interference) directly affects only the layer close to the wall, while its indirect effect extends to a large portion of the external flow.
The Electrodynamometric Balance of the Small Wind Tunnel of the French Service of Aeronautical Research: This investigation shows the attempt to improve the electrodynamomoter designed by Mr. Villey. The force to be measured acts on a flexible steel plate which is placed in front of a fixed plate. The deformation varies the original thickness of the layer of air between the two plates, thus causing a more rapid variation in the coefficient of electrostatic attraction of the two plates than in the capacity of the condenser formed by the dynamometer.
Measurement of Profile Drag on an Airplane in Flight by the Momentum Method: Part 1: The present report contains the results thus far obtained and is intended to form the basis of further tests on using the momentum method. The method of testing is presented in detail and the photographs taken during these tests are interpreted.
Measurement of Profile Drag on an Airplane in Flight by the Momentum Method: Part 2: The purpose of this section is to survey the present status of scientific knowledge of the causes which produce drag, in order, if possible, to establish the relation between the individual results and the actual phenomena which demonstrate the fundamental importance of surface conditions. A discussion of the boundary layer is followed by: relations between frictional and form drag, application to profile-drag measurements, and different kinds of roughness. High-pressure wind tunnel tests are discussed along with roughness and maximum lift.
The 1929 Rhon soaring-flight contest: The limitation of the 1929 contest to performance gliders necessitated the establishment of a formula which would make it possible to distinguish between performance gliders and school and training gliders. The sinking speed was therefore adopted as the basis for such a distinction, and the requirement was made that the sinking speed of a performance glider should not exceed 0.8 m/s. The rest of the report details the different entries with regard to design and performance.
Experimental Investigation of Aircraft Propellers Exposed to Oblique Air Currents: "Two screw propellers, a normal airplane propeller with a pitch/diameter ratio H/D = 0.5 and a helicopter propeller H/D = 0.2 were tested in the large wind tunnel of the Gottigen Aerodynamic Institute. With both propellers the angle between the propeller axis and the direction of the wind was varied from 0 to 90 degrees. In addition to the three force and the three moment components in a wind-fast coordinate system, the corresponding components in a propeller-fast coordinate system, a total of six force and six moment components, together with the propulsive efficiency, were measured or calculated from measurements" (p. 1).
Improving the Performance of Multi-Engined Airplanes by Means of Idling Propellers: The "Free-Wheel" Propeller: In order to demonstrate the importance of free-wheeling propellers, this report considers the braking effect of a propeller on a stopped engine when the propeller is rigidly connected with the engine shaft and also when mounted on a free-wheel hub. The cases of propellers of asymmetric and symmetric section are discussed. The author describes the mechanism of the free-wheel propeller as constructed for this test. The results obtained with the device mounted on a 1,000 horsepower two-engine airplane are given.
Ratier Metal Propeller With Pitch Variable in Flight: One of the serious sources of difficulties in variable pitch propellers is the turning moment or torque due to the centrifugal force which tends to bring the mean plane of the blades into the plane of rotation. This moment, which is found elsewhere only in propellers with removable blades, is so great that the aerodynamic forces, as regards their effect on the torsion, become entirely negligible in comparison with it. This report presents the Ratier Company's solution to changing the pitch of airplane propellers.
Balanced and Servo Control Surfaces: "Many reports on various control systems are available, but the results cannot be generally applied since the effect of particular changes of surface-form and mounting are subject to variations depending upon airfoil section and influences of airplane layout. This report presents a simple analysis of several control systems in more general use. Elevators, ailerons, and rudders are all discussed" (p. 1).
Development of the Junkers-Diesel Aircraft Engine: The working process of the Junkers engine has resulted from a series of attempts to attain high performance and to control the necessarily rapid and complete combustion at extremely high speeds. The two main problems of Diesel engines in aircraft are addressed; namely, incomplete combustion and the greater weight of Diesel engine parts compared to gasoline engines.
Experimental Research on the Friction of Pivots: In horology the friction between solids is of the greatest importance; one limited, however, to the application of the laws of Coulomb which, do not at all correspond with reality. This report presents a review of the subject and some general conclusions. The choice of lubricant is discussed as well as the pressure between frictional surfaces. The gears in a watch are used extensively as examples.
The Magnus Effect in Theory and in Reality: A discussion of the Flettner rotor is presented from a nautical and economic viewpoint, and although it was a failure, the experimental and theoretical inventions cannot be disregarded. The following critical and experimental investigation will show the relations and applicability of the theories and practical applications. The Magnus effect is described in detail and a discussion and critical review of the Magnus effect is included.
Recent Tests of Tailless Airplanes: This report details the advantages and construction of tailless airplanes. Both a glider and a powered model were built and the specifications of both airplanes are listed.
Contribution to the Theory of Propeller Vibrations: This report presents a calculation of the torsional frequencies of revolving bars with allowance for the air forces. Calculation of the flexural or bonding frequencies of revolving straight or tapered bars in terms of the angular velocity of revolution. Calculation on the basis of Rayleigh's principle of variation. There is also a discussion of error estimation and the accuracy of results. The author then provides an application of the theory to screw propellers for airplanes and the discusses the liability of propellers to damage through vibrations due to lack of uniform loading.
"Gloster" Metal Construction: This report details the methods of construction employed by the Gloster Company in their fabrication of metal aircraft parts. Ribs, spars, wings, and metal treatments to prevent oxidation are all discussed.
A Possible Method for Preventing the Autorotation of Airplane Wings: "At the suggestion of Professor Betz, the following device was tested with the object of reducing the autorotational speed of airplane wings. The model of a normal wing with the Gottigen profile 420, 1 meter span and 0.2 meter chord was provided with a pair of symmetrical slots on the suction side, connected with each other inside the wing. The arrangement of the testing equipment and models are given and the effect of the slots can be seen in the experimental curves that are included" (p. 1).
Propulsion by Reaction: This report concerns propulsion by means of rockets. The author concerns himself mainly with efficiency of propulsion and he defines and mathematically expresses those efficiencies.
Air forces and air-force moments at large angles of attack and how they are affected by the shape of the wing: From Summary: "The present report is, in the first place, a compilation of the test results now available from wing tests up to angles of attack 90^o. Reports are also given of tests with monoplane and auxiliary wings in the Gottingen wind tunnel for the purpose of plotting a steadily rising curve of the normal force as a foundation of the angle of attack."
Calculation of Pressure Distribution on Airship Hulls: These calculations were based on the shape of the ZR III, with the following simplifications: cars, fins, and rudders removed; all cross sections replaced by equivalent circular cross sections. Under these assumptions the pressure distribution was calculated for the following cases: symmetrical case, or flow parallel to the axis; unsymmetrical case, or flow at an angle to the axis. In both cases the simple potential flow first forms the basis for the determination of the pressure distribution.
Impact Tests on Rubber Compression Springs for Airplane Landing Gears: The present report gives the results of tests which were made for the purpose of solving the problem of whether diagrams obtained from pressure tests could be conclusive for the determination of the safe impact coefficients. It is first established that the rubber rings adhere firmly to the compression surfaces during deformation. Suggestions are thus obtained for a constructive simplification of the rubber rings. The hysteresis phenomenon is ascribed to external and internal friction forces. A device for falling tests is then described with which the process of shock absorption with rubber rings was tested.
Investigation of the Variations in the Velocity of the Air Flow About a Wing Profile: Memorandum presenting an investigation to determine the variations in the velocity of the air when it was obliged to flow about a wing profile. Special interest was paid to the determination of velocity as compared with that of the undisturbed flow and of the velocity drop in successive planes perpendicular to the flow direction at increasing distances from the wing profile.
The Vortex Theory and Its Significance in Aviation: This report will present ideas closely related to the vortex conception and illustrate them in the simplest possible terms. In addition to these general considerations, this report will attempt to show the application of the vortex theory in connection with the wing theory.
Calculation of Tapered Monoplane Wings: The tapered wing shape increases the lift in the middle of the wing and thus reduces the bending moment of the lifting forces in the plane of symmetry. Since this portion of the wing is the thickest, the stresses of the wing material are reduced and desirable space is provided for stowing the loads in the wing. This statically excellent form of construction, however, has aerodynamic disadvantages which must be carefully weighed, if failures are to be avoided. This treatise is devoted to the consideration of these problems.
Determination of the Best Cross Section for a Box Beam Subjected to Bending Stresses: Previous investigations on the strength characteristics and structure of wood in construction are analyzed and a method of representation is developed suitable for the use of designers.
Structural Details of German Light Airplanes: This report presents a review of German light airplane construction. Some of the topics discussed include: engines, fuselages, wings, landing gear, and other mechanical parts.
Theory of the Landing Impact of Seaplanes: The present investigation is an endeavor to express the jolting stresses, designated as landing impacts, undergone by seaplanes in landing and taking off from rough water, as functions of specific factors, in order to enable the evaluation of empirically obtained results and thus acquire theoretical data for the construction of seaplane floats and hulls.
Determination of the Maximum Control Forces and Attainable Quickness in the Operation of Airplane Controls: "This report is intended to furnish bases for load assumptions in the designing of airplane controls. The maximum control forces and quickness of operation are determined. The maximum forces for a strong pilot with normal arrangement of the controls is taken as 1.25 times the mean value obtained from tests with twelve persons. Tests with a number of persons were expected to show the maximum forces that a man of average strength can exert on the control stick in operating the elevator and ailerons and also on the rudder bar" (p. 1).
Effects of the End Fixation of Airplane Struts: The main purpose of this report is to give references to literature on the subject of end fixation of airplane struts and also to furnish the constructor with a general survey of the simplest methods for estimating the end-fixation effect.
Flight Tests for the Determination of Static Longitudinal Stability: The accuracy of the instruments used for flight test measurements has been inadequate so a new series of tests were commissioned with the development of an accurate elevator setting recorder.
Load Assumptions for Calculating the Strength of Airplanes: "The following load assumptions shall be taken as the basis of the strength calculations. Certain definite load conditions (e.g. of flight, control, landing and transport) shall be assumed. The loads shall be assumed to be safe loads, constant or only slowly variable, and the inertia forces due to elastic deformation are accordingly disregarded. The external forces, the force of gravity and the inertia forces on the whole airplane shall produce a condition of equilibrium" (p. 1).
The Behm Acoustic Sounder for Airplanes With Reference to Its Accuracy: Relative altimetry is of great importance for increasing the safety in aerial transportation, because it makes possible safe flying at night, by poor visibility, and when landing. Among the instruments of this type is the Behm sounder, which operates on an acoustic principle. Acoustic altimetry in general and the Behn sounder, in particular, are covered in this report.
Counter-Propeller: A counter-propeller is a fixed propeller smaller than the main propeller, mounted either fore or aft of the latter and performing the function of changing the direction of motion of the fluid filaments, which naturally tend to adopt a helicoidal form. This paper presents a consideration of the real advantage of counter-propellers on aircraft and the best shape of the blades. First, the author determines the possible energy absorption by the tangential increments. This process will be facilitated by the examination of the polygons of the relative velocities fore and aft of the generic section, of radius r, of one of the blades of the propeller.
Diesel-Engine Investigations: Ignition-Chamber Engines: This report presents a thorough investigation of the functioning process and injection and combustion characteristics of ignition-chamber engines.
Göttingen Six-Component Scale Measurements on a Junkers A 35 Airplane Model: The suggestion for the measurements collected in this report was prompted by the results of spinning experiments. For the theoretical spinning investigations there was a lack of data on lateral force, yawing, and rolling moment of airplanes.
Velocity Distribution in the Boundary Layer of a Submerged Plate: This report deals with the measurement of the velocity distribution of the air in the velocity of a plate placed parallel to the air flow. The measurements took place in a small wind tunnel where the diameter of the entrance cone is 30 cm and the length of the free jet between the entrance and exit cones is about 2.5 m. The measurements were made in the free jet where the static pressure was constant, which was essential for the method of measurement used.
Mathematical treatise on the recovery from a flat spin: In this mathematical investigation, made in collaboration with Dr. Wilhelm Schmidt, we interpret the temporary change (due to some disturbance) in the quantities which define the position of the airplane while in a flat spin. We further examine the effect of this change, of the means resorted to to produce the disturbance, and thus reveal the expedients available for recovering from a flat spin.
Metal Covering of Airplanes: This paper presents a relative determination of the wrinkling of a plate wall beam with variable number of supports and methods of attachment. The discussion is based entirely on tests with extensometer readings and number of wrinkles, with complete web and with cutout sections. The author notes that the number of corrugations increase with added stress, keeping constant edge spacing.
Practical Tests With The "Auto Control Slot" Part 1: Lecture: "The effect of a slotted wing depends essentially on the fact that a secondary flow branches off from the main flow and passes to the suction side of the profile. It is thus possible to delay the separation greatly and increase the lift. The practical aspect of the slotted wing is less known in Germany, especially the results obtained during the last three years since the introduction of the 'auto control slot'" (p. 1).
Practical Tests With The "Auto Control Slot" Part 2: Discussion: "For some time the D.V.L. has been investigating the question of applicability of Handley Page slotted wings to German airplanes. Comparitive gliding tests were made with open and closed slots on an Albatros L 75 airplane equipped with the Handley Page "auto control slots." This investigation served to determine the effect of the auto control slot on the properties and performances of airplanes at large angles of attack. The most important problems were whether the angle of glide at small angles of attack can be increased by the adoption of the auto control slot and, in particular, as to whether the flight characteristics at large angles of attack are improved thereby and equilibrium in gliding flight is guaranteed even at larger than ordinary angles of attack" (p. 1).
Riveted Joints in Thin Plates: The method of riveting by forming the closing head under increasing pressure or by a series of hammer blows is investigated. The question as to the best edge distance, i.e. that distance from the rivet center to the plate edge below which it is unadvisable to go and, at the same time useless to go beyond, was examined. The slippage of plates which occurs under the effect of a certain stress, does not completely disappear on unloading.
English Airplane Construction: English airplane construction is presented with a particular emphasis on metal construction techniques. Steel rib and fuselage construction are discussed as well as the use of duralumin in construction.

National Advisory Committee for Aeronautics (NACA) - 380 Matching Results

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