National Advisory Committee for Aeronautics (NACA) - 13,786 Matching Results
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- Analysis of Meteorological Data Obtained During Flight in a Supercooled Stratiform Cloud of High Liquid-Water Content
- "Flight icing-rate data obtained in a dense and abnormally deep supercooled stratiform cloud system indicated the existence of liquid-water contents generally exceeding values in amount and extent previously reported over the midwestern sections of the United States. Additional information obtained during descent through a part of the cloud system indicated liquid-water contents that significantly exceeded theoretical values, especially near the middle of the cloud layer. The growth of cloud droplets to sizes that resulted in sedimentation from the upper portions of the cloud is considered to be a possible cause of the high water contents near the center of the cloud layer" (p. 1).
- Statistical Study of Aircraft Icing Probabilities at the 700- and 500- Millibar Levels over Ocean Areas in the Northern Hemisphere
- From Summary: "A statistical study is made of icing data reported from weather reconnaissance aircraft flown by Air Weather Service (USAF). The weather missions studied were flown at fixed flight levels of 500 millibars (18,000 ft) and 700 millibars (10,000 ft) over wide areas of the Pacific, Atlantic, and Arctic Oceans. This report is presented as part of a program conducted by the NACA to obtain extensive icing statistics relevant to aircraft design and operation. The thousands of in-flight observations recorded over a 2- to 4-year period provide reliable statistics on icing encounters for the specific areas, altitudes, and seasons included in the data."
- Statistical Explanation of Spontaneous Freezing of Water Droplets
- Note presenting a statistical theory based on the presence of small crystallization nuclei suspended in water developed to explain experimental results showing that, on average, small droplets can be supercooled to lower temperatures than large ones. The average behavior of supercooled droplets is reproduced on the basis of probability theory with an assumed distribution of crystallization nuclei with respect to the temperatures at which the nuclei cause freezing.
- Photomicrographic Investigation of Spontaneous Freezing Temperatures of Supercooled Water Droplets
- "A photomicrographic technique for investigating seupercooled water droplets has been devised and. used. to determine the spontaneous freezing temperatures of seupercooled water droplets of the size ordinarily found. in the atmosphere. The freezing temperatures of 4527 droplets ranging from 8.75 to 1000 microns in diameter supported on a platinum surface and 571 droplets supported on copper were obtained. The average spontaneous freezing temperature decreased with decrease in the size of the droplets" (p. 1).
- Experimental Values of the Surface Tension of Supercooled Water
- "The results of surface-tension measurements for supercooled water are presented. A total of 702 individual measurements of surface tension of triple-distilled water were made in the temperature range, 27 to -22.2 C, with 404 of these measurements at temperatures below 0 C. The increase in magnitude of surface tension with decreasing temperature, as indicated by measurements above 0 C, continues to -22.2 C. The inflection point in the surface-tension - temperature relation in the vicinity of 0 C, as indicated by the International Critical Table values for temperatures down to -8 C, is substantiated by the measurements in the temperature range, 0 to -22.2 C" (p. 1).
- A Photographic Study of Freezing of Water Droplets Falling Freely in Air
- From Summary: "A photographic technique for investigating water droplets of diameter less than 200 microns falling freely in air at temperatures between 0 C and -50 C has been devised and used to determine: (1) The shape of frozen droplets, (2) The occurrence of collisions of partly frozen or of frozen and liquid droplets, and (3) The statistics on the freezing temperatures of individual free-falling droplets."
- The Oehmichen Peugeot Helicopter
- The first flights of the Oehmichen helicopter are detailed as well as various aspects of the construction.
- The Coupling of Engines
- This report examines the idea of coupling numerous engines together to turn a single propeller, which the author feels would free aircraft design from the problems of multi-engine and propeller design.
- Commercial Aviation in Germany: Past and Future
- This review of commercial aviation includes postal delivery, package transport, and passenger transport. Both airplanes and airships are covered in this review.
- The Art of Writing Scientific Reports
- As the purpose of the report is to transmit as smoothly and as easily as possible, certain facts and ideas, to the average person likely to read it, it should be written in a full and simple enough manner to be comprehended by the least tutored, and still not be boring to the more learned readers.
- Development of Aeronautical Engines by the Army and Navy
- Different aircraft engines are categorized as being of interest to only the Army or Navy or to both armed services. A listing of the different engines is presented along with some statistics, namely, horsepower.
- The Rumpler Passenger Airplane
- This report details the Rumpler Limousine which was a further development of the well known type 5 A 2. The fuselage, engine, cabin, wings, controls, and landing gear are all discussed.
- Variable Pitch Propellers
- In this report are described four different types of propellers which appeared at widely separated dates, but which were exhibited together at the last Salon de l'Aeronautique. The four propellers are the Chaviere variable pitch propeller, the variable pitch propeller used on the Clement Bayard dirigible, the variable pitch propeller used on Italian dirigibles, and the Levasseur variable pitch propeller.
- Recent Developments in Light Alloys
- This report is intended to cover the progress that has been made in both the manufacture and utility of light alloys in the United States since the first part of 1919. Duralumin is extensively discussed both as to manufacture and durability.
- Resume of the Theory of Naval and Aerial Propulsive Propellers and of Airplanes in the Rectilinear Flight
- Though dissimilar, these two subjects have been united because they have some points in common. The computation of the movement of an airplane can only be correctly established if we are in a position to know exactly the thrust and resisting torque of the propeller for the various values of slip, which may vary greatly according to circumstance. The first part of the work concerns propellers and introduces as a fundamental variable, the true slip (delta) with respect to the effective pitch, which is the advance per revolution of the propeller corresponding to no thrust. The second part deals with characteristic curves of an airplane.
- Abstracts from the German Technical Press: Rates for Flights Organized by the State
- Report presenting tariffs that are written for all aircraft manufacturing companies to follow regarding aircraft orders.
- The Technical Development of the Transport airplane: Report of the Aero-Technical Conference of the Scientific Association for Aeronautics, March 5, 1919
- The abolition of military qualifications gives free scope to new technical possibilities in the development of transport airplanes. This report notes the various considerations that must be made when designing aircraft to meet the needs of commercial passengers. Comfort and safety must be emphasized.
- 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.
- Study of the Resistance Offered by Propellers Rotating on an Airstream
- This report presents a series of tests conducted to verify the formula for thrust P = q(exp 2) D(exp 2) V(exp 2), where P represents thrust, V the velocity of the airstream, D the diameter of the propeller, and q the lifting quality of a comparative propeller which is called the conjugate propeller.
- Extracts from the German Technical Process. Transport Airplanes.
- Report presenting a description of the transition stage of airplanes and how it will change with new developments in aircraft design. The details of the debate between centralized or decentralized installation are also provided, including some of the pros and cons of each.
- British Certificates of Airworthiness
- This report details the rules and regulations for obtaining a British airworthiness certificate. Aircraft loading and construction are especially important.
- Observations on the Method of Determining the Velocity of Airships
- To obtain the absolute velocity of an airship by knowing the speed at which two routes are covered, we have only to determine the geographical direction of the routes which we locate from a map, and the angles of routes as given by the compass, after correcting for the variation (the algebraical sum of the local magnetic declination and the deviation).
- The Dynamometer Hub and the Flywheel of the Engine
- Report presenting a description of the interaction between the dynamometer hub and the flywheel of the engine in aircraft. The negative rotary moments in propellers generally allow for the cessation of one cylinder without any lifting on the part of the propeller, and without depriving the engine of its flywheel.
- 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.
- Flexibility of Bearing Surfaces and Stress on Fabrics
- Report presenting an investigation of the flexibility of bearing surfaces and stress on fabrics used in wings. Equations are given for calculating some of these loading factors.
- Abacus for the Reduction of English Measures to the Metric System and Vice Versa
- This report presents a description of an abacus with three scales: one for English measures, one for metric measures, and one with the "points of reduction", as well as construction details. There is also a detailed description on how to use the abacus.
- Applications of Modern Hydrodynamics to Aeronautics Part 1: Fundamental Concepts and the Most Important Theorems. Part 2: Applications
- A discussion of the principles of hydrodynamics of nonviscous fluids in the case of motion of solid bodies in a fluid is presented. Formulae are derived to demonstrate the transition from the fluid surface to a corresponding 'control surface'. The external forces are compounded of the fluid pressures on the control surface and the forces which are exercised on the fluid by any solid bodies which may be inside of the control surfaces.
- Pressure Distribution on Joukowski Wings
- The hydrodynamics and mathematical models as applied to the potential flow about a Joukowski wing are presented.
- Graphic Construction of Joukowski Wings
- Memorandum presenting a description and formulas that can be used to plot the cross-sectional outline of a Joukowski wing.
- The Minimum Induced Drag of Aerofoils
- Equations are derived to demonstrate which distribution of lifting elements result in a minimum amount of aerodynamic drag. The lifting elements were arranged (1) in one line, (2) parallel lying in a transverse plane, and (3) in any direction in a transverse plane. It was shown that the distribution of lift which causes the least drag is reduced to the solution of the problem for systems of airfoils which are situated in a plane perpendicular to the direction of flight.
- The Aerodynamic Forces on Airship Hulls
- The new method for making computations in connection with the study of rigid airships, which was used in the investigation of Navy's ZR-1 by the special subcommittee of the National Advisory Committee for Aeronautics appointed for this purpose is presented. The general theory of the air forces on airship hulls of the type mentioned is described and an attempt was made to develop the results from the very fundamentals of mechanics.
- Elements of the Wing Section Theory and of the Wing Theory
- Results are presented of the theory of wings and of wing sections which are of immediate practical value. They are proven and demonstrated by the use of the simple conceptions of kinetic energy and momentum only.
- The Inertia Coefficients of an Airship in a Frictionless Fluid
- The apparent inertia of an airship hull is examined. The exact solution of the aerodynamical problem is studied for hulls of various shapes with special attention given to the case of an ellipsoidal hull. So that the results for the ellipsoidal hull may be readily adapted to other cases, they are expressed in terms of the area and perimeter of the largest cross section perpendicular to the direction of motion by means of a formula involving a coefficient kappa which varies only slowly when the shape of the hull is changed, being 0.637 for a circular or elliptic disk, 0.5 for a sphere, and about 0.25 for a spheroid of fineness ratio.
- Flow and Drag Formulas for Simple Quadrics
- The pressure distribution and resistance found by theory and experiment for simple quadrics fixed in an infinite uniform stream of practically incompressible fluid are calculated. The experimental values pertain to air and some liquids, especially water; the theoretical refer sometimes to perfect, again to viscid fluids. Formulas for the velocity at all points of the flow field are given. Pressure and pressure drag are discussed for a sphere, a round cylinder, the elliptic cylinder, the prolate and oblate spheroid, and the circular disk. The velocity and pressure in an oblique flow are examined.
- Flow and Force Equations for a Body Revolving in a Fluid
- A general method for finding the steady flow velocity relative to a body in plane curvilinear motion, whence the pressure is found by Bernoulli's energy principle is described. Integration of the pressure supplies basic formulas for the zonal forces and moments on the revolving body. The application of the steady flow method for calculating the velocity and pressure at all points of the flow inside and outside an ellipsoid and some of its limiting forms is presented and graphs those quantities for the latter forms.
- General Potential Theory of Arbitrary Wing Sections
- The problem of determining the two dimensional potential flow around wing sections of any shape is examined. The problem is condensed into the compact form of an integral equation capable of yielding numerical solutions by a direct process. An attempt is made to analyze and coordinate the results of earlier studies relating to properties of wing sections. The existing approximate theory of thin wing sections and the Joukowski theory with its numerous generalizations are reduced to special cases of the general theory of arbitrary sections, permitting a clearer perspective of the entire field. The method which permits the determination of the velocity at any point of an arbitrary section and the associated lift and moments is described. The method is also discussed in terms for developing new shapes of preassigned aerodynamical properties.
- NACA Conference on Aerodynamic Problems of Transonic Airplane Design
- Compilation of the papers presented at a NACA conference on transonic airplane design, including stability and control and configurations with extreme sweep. From Introduction: "The purpose of this conference was to convey to those involved in the study of the aerodynamic problems of transonic aircraft these recent research results and to provide those attending an opportunity for discussion of the results."
- NACA: University Conference on Aerodynamics: A Compilation of the Papers Presented
- This document contains reproductions of the technical papers presented at the NACA - University Conference on Aerodynamics held at the Langley Aeronautical Laboratory on June 21, 22, and 23, 1948. The conference was held in recognition of the difficulties, imposed by security restrictions, in keeping abreast of the rapid advances in aerodynamics. The papers were prepared to review the status of a number of fields of interest, to summarize the more important wartime advances that are no longer classified, and to orient reference material for further study.
- Annual Report of the National Advisory Committee for Aeronautics (42nd): Administrative Report without Technical Reports
- Report consisting of a summary and papers covering the activities occurring during the year 1956 in the National Advisory Committee for Aeronautics. The paper is broken up into letter of transmittal, letter of submittal, the technical activities, committee organization and membership, and the financial report.
- Preliminary Investigation of a Technique for Stability Studies of a Self-Propelled Model of a Submerged Submarine
- Report presenting the initial development of a technique for the qualitative study of the stability and control characteristics of a free, self-propelled, dynamic submarine model. Two types of control systems were evaluated. Results regarding the qualitative analysis of the control system, dive paths, equations of motion, and comparison with experimental paths are provided.
- Establishment of Aviation Schools
- Report presenting a discussion of the creation of a suitable aviation school and some of the characteristics that should be considered in terms of hiring personnel, creating a curriculum, and obtaining equipment.
- Extracts From the Belgian Regulations for Government Assistance to Air Transport Companies
- Report presenting information regarding the usage of commercial and passenger service air routes and the fees and penalties involved in operating an air line.
- Aeronautic Instruction in Germany
- This report contains a list of the courses relating to aeronautics announced in Germany, both in the technical high schools and in the universities.
- The danger of stalled flight and an analysis of the factors which govern it
- A definition of "stalled fight" is presented as well as a detailed discussion on the how and why it occurs. Some suggestions are made to prevent its occurrence such as carrying an air speed instrument in the airplane.
- Traffic Airships With Special Reference to Economy
- The first part of this report details the efficiency and economy of airship travel, while the second part presents methods of economic efficiency with regards to construction, cost of upkeep and operation, and the establishment of airship lines.
- Dependence of Propeller Efficiency on Angle of Attack of Propeller Blade
- In order to determine the maximum and the most favorable pitch for a propeller, it was found desirable to investigate the dependence of propeller efficiency on the angle of attack of the propeller blade. The results of a few experiments are given to show that propeller blades conduct themselves just like airplane wings with reference to the dependence of their efficiency on their angle of attack.
- Recent Progress in the Theory of Air Flow as Applied to Aeronautics
- In summing up it may be said that the hydrodynamic theories are best confirmed by experimental results for bodies with small resistance or drag and can accordingly be used in place of experimental tests.
- Vibrations of Aviation Engines
- Different causes of airplane engine vibration are given as well as devices to measure vibration.
- Aerial navigation : on the problem of guiding aircraft in a fog or by night when there is no visibility
- Report discussing the use of magnetic fields and wire to navigate aircraft in conditions of poor visibility is presented. This field may be considered to be derived from a double lemniscate, considered in the particular case where the origin is a double point formed from the magnetic field of the slack wire, from the field produced by the return currents and from the field due to the currents induced in the conducting mass. These fields are dephased in two ways, one in the direction of the wire, the other in a direction perpendicular to it.
- Pressure Measurements During Flight
- The general idea was to record the air pressure on the spot, that is, without intervening tubes, by some simple automatic registering device. This was therefore made in such small dimensions that it could be inserted into the wing between the ribs and stand in direct connection with the pressure openings. The results of different experiments are presented along with the best locations for locating the instruments for recording the pressure.