Technical Report Archive and Image Library (TRAIL) - 1,424 Matching Results

Search Results

Aeronautic instruments. Section VI : aerial navigation and navigating instruments

Description: This report outlines briefly the methods of aerial navigation which have been developed during the past few years, with a description of the different instruments used. Dead reckoning, the most universal method of aerial navigation, is first discussed. Then follows an outline of the principles of navigation by astronomical observation; a discussion of the practical use of natural horizons, such as sea, land, and cloud, in making extant observations; the use of artificial horizons, including the bubble, pendulum, and gyroscopic types. A description is given of the recent development of the radio direction finder and its application to navigation.
Date: 1923?~
Creator: Eaton, H. N.
Partner: UNT Libraries Government Documents Department

Aeronautic instruments. Section VI : oxygen instruments

Description: This report contains statements as to amount of oxygen required at different altitudes and the methods of storing oxygen. The two types of control apparatus - the compressed oxygen type and the liquid oxygen type - are described. Ten different instruments of the compressed type are described, as well as the foreign instruments of the liquid types. The performance and specifications and the results of laboratory tests on all representative types conclude this report.
Date: 1923?~
Creator: Hunt, F. L.
Partner: UNT Libraries Government Documents Department

Aeronautic instruments. Section VIII : recent developments and outstanding problems

Description: This report is section VIII of a series of reports on aeronautic instruments. The preceding reports in this series have discussed in detail the various types of aeronautic instruments which have reached a state of practical development such that they have already found extensive use. It is the purpose of this paper to discuss briefly some of the more recent developments in the field of aeronautic instrument design and to suggest some of the outstanding problems awaiting solution.
Date: 1923
Creator: Hunt, F. L.
Partner: UNT Libraries Government Documents Department

The altitude effect on air speed indicators II

Description: In an investigation described in NACA Technical Report 110, it was shown that under certain conditions, particularly for the relatively low-speed flight of airships, the data obtained were not sufficiently accurate. This report describes an investigation in which the data obtained were sufficiently accurate and complete to enable the viscosity correction to be deduced quantitatively for a number of the air-speed pressure nozzles in common use. The report opens with a discussion of the theory of the performance of air-speed nozzles and of the calibration of the indicators, from which the theory of the altitude correction is developed. Then follows the determination of the performance characteristics of the nozzles and calibration constants used for the indicators. In the latter half of the report, the viscosity correction is computed for the Zahm Pitot-venturi nozzles.
Date: 1923?~
Creator: Eaton, H. N. & Macnair, W. A.
Partner: UNT Libraries Government Documents Department

Applications of Modern Hydrodynamics to Aeronautics

Description: The report gives, rather briefly, in part one an introduction to hydrodynamics which is designed to give those who have not yet been actively concerned with this science such a grasp of the theoretical underlying principles that they can follow the subsequent developments. In part two there follows a separate discussion of the different questions to be considered, in which the theory of aerofoils claims the greatest portion of the space. The last part is devoted to the application of the aerofoil theory to screw propellers. A table giving the most important quantities is at the end of the report. A short reference list of the literature on the subject and also a table of contents are added.
Date: 1923
Creator: Prandtl, L.
Partner: UNT Libraries Government Documents Department

Bending moments, envelope, and cable stresses in non-rigid airships

Description: This report describes the theory of calculating the principal stresses in the envelope of a nonrigid airship used by the Bureau of Aeronautics, United States Navy. The principal stresses are due to the gas pressure and the unequal distribution of weight and buoyancy, and the concentrated loads from the car suspension cables. The second part of the report deals with the variations of tensions in the car suspension cables of any type of airship, with special reference to the rigid type, due to the propeller thrust or the inclination of the airship longitudinally.
Date: January 1923
Creator: Burgess, C. P.
Partner: UNT Libraries Government Documents Department

Control in circling flight

Description: This investigation was undertaken for the purpose of developing instruments that would record the forces and positions of all three controls, and to obtain data on the behavior of an airplane in turns. All the work was done on a standard rigged JN4H (airplane no. 2 of National Advisory Committee for Aeronautics, report no. 70). It was found that the airplane was longitudinally unstable and nose heavy; that it was laterally unstable, probably due to too little dihedral; and that it was directionally unstable, due to insufficient fin area, this last being very serious, for in case of a loss of rudder control the airplane immediately whips into a spin from which there is no way of getting it out. On the other hand, it was found possible to fly quite satisfactorily with the rudder locked, and safely, though not so well, with the ailerons locked.
Date: January 1, 1923
Creator: Norton, F. H. & Allen, E. T.
Partner: UNT Libraries Government Documents Department

Controllability and maneuverability of airplanes

Description: This investigation was conducted for the purpose of studying the behavior of the JN4H airplane in free flight under the action of its controls and from this to arrive at satisfactory definitions and coefficients for controllability and maneuverability. The method consisted in recording the angular velocity about the three axes, together with the air speed, control positions, and acceleration. (author).
Date: January 1, 1923
Creator: Norton, F. H. & Brown, W. G.
Partner: UNT Libraries Government Documents Department

Damping coefficients due to tail surfaces in aircraft

Description: The object of the investigation described in this report was to compare the damping coefficients of an airfoil as calculated from a knowledge of the static characteristics of the section with those obtained experimentally with an oscillation. The damping coefficients as obtained, according to the conventional notation, can be considered either as due to pitching or as due to yawing, the oscillation in these experiments being so arranged that the surfaces oscillate about a vertical axis. This is in reality the case when the influence is yawing about the standard Z-axis, but it can also be considered as a pitching motion when the model is so rigged that its standard Y-axis becomes vertical. The horizontal oscillation has the advantage of eliminating the gravity action and avoiding the use of counterweights, whose presence in the wind tunnel is undesirable because of their interference with the air flow. The real point of the investigation was to separate the damping due to rotation from that due to translation. By varying the distance between the center of pressure and the center of rotation on the oscillator, the variation of damping moment can be observed and the rotational and translational effects can be separated.
Date: January 1, 1923
Creator: Chu, Lynn
Partner: UNT Libraries Government Documents Department

The decay of a simple eddy

Description: The principal result obtained in this report is a generalization of Taylor's formula for a simple eddy. The discussion of the properties of the eddy indicates that there is a slight analogy between the theory of eddies in a viscous fluid and the quantum theory of radiation. Another exact solution of the equations of motion of viscous fluid yields a result which reminds one of the well-known condition for instability in the case of a horizontally stratified atmosphere.
Date: January 1, 1923
Creator: Bateman, H
Partner: UNT Libraries Government Documents Department

The drag of C class airship hull with varying length of cylindric midships

Description: A model of the C class airship hull, when severed at its major section and provided with a cylindric mid-body of variable length, had its air resistance increased about in proportion to the length of the mid-body up to 3 diameters, and in about the manner to be expected from the increase of skin friction on this variable length. For greater length the drag increased less and less rapidly.
Date: January 1, 1923
Creator: Zahm, A. F.; Smith, R. H. & Hill, G. C.
Partner: UNT Libraries Government Documents Department

The drag of Zeppelin airships

Description: This report is a discussion of the results of tests with Zeppelin airships, in which the propellers were stopped as quickly as possible while the airship was in full flight. In this paper the author refers to the theory involved in these tests and calls attention to one scientifically interesting fact which can be derived from the tests and which has not yet been noted. The most important question concerning the tests is, of course: does the negative acceleration of an airship with stopped propellers supply proper data for determining the drag of the airship when in uniform flight? This can not be absolutely answered, however, except that in this particular case the agreement is sufficient and that the data obtained from the test are the true quantities, or, at least, the approximate quantities wanted.
Date: January 1, 1923
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department

Experimental research on air propellers, 5

Description: In previous reports on experimental research on air propellers, by W. F. Durand and E. P. Lesley, as contained in the National Advisory Committee for Aeronautics reports nos. 14, 30, and 64, the investigations were made progressively and each without reference to results given in preceding reports and covering only information relating to forms perhaps adjacent in geometrical form and proportion. This report is a review of the entire series of results of the preceding reports with a view of examining through graphical and other appropriate means the nature of the history of the characteristics of operation as related to the systematic variations in characteristics of forms, etc., through the series of such characteristics.
Date: 1923
Creator: Durand, W. F. & Lesley, E. P.
Partner: UNT Libraries Government Documents Department

General biplane theory

Description: This report deals with the air forces on biplane cellule. The first part of the report deals with the two-dimensional problem neglecting viscosity. The variation of the section, chord, gap, stagger, and decalage are investigated, a great number of examples are calculated, and all numerical results are given in tables. For the biplane without stagger it is found that the loss of lift in consequence of the mutual influence of the two wing sections is only half as much if the lift is produced by the curvature of the section as it is when the lift is produced by the inclination of the chord to the direction of motion. The second part deals with the influence of the lateral dimensions. It is found that the loss of lift due to induction is almost unchanged, whether the biplane is staggered or not. In the third part conclusions from previous investigations are drawn, viscosity and experimental experience are brought in, and the method is simplified for practical application. Simple formulas give the drag, lift, and moment. In order to make use of the simple formulas more convenient, tables for the dynamical pressure, induced drag, and angle of attack are added so that practically no computation is needed for the application of the results.
Date: January 1, 1923
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department

General theory of thin wing sections

Description: This report contains a new, simple method of calculating the air forces to which thin wings are subjected at small angles of attack, if their curvature is not too great. Two simple integrals are the result. They contain only the coordinates of the wing section. The first integral gives the angle of attack at which the lift of the wing is zero, the second integral gives the moment experienced by the wing when its angle is zero. The two constants thus obtained are sufficient to determine the lift and moment for any other angle of attack. This with the theory of the aerodynamical induction, and with our empirical knowledge of the drag due to friction, the results are valuable for actual wings also. A particular result obtained is the calculation of the elevator effect. (author).
Date: January 1, 1923
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department

Internal stresses in laminated construction

Description: This report reviews the procedure employed in an investigation of the sources and influence of internal stresses in laminated construction, and discusses the influence of shrinkage and swelling stresses caused by atmospheric conditions upon the tensile strength across grain in laminated construction with special reference to airplane propellers. The investigation covered three sources of internal stress, namely, the combination of plain-sawed and quarter-sawed material in the same construction, the gluing together of laminations of different moisture contents, and the gluing together of laminations of different densities. Glued specimens and free specimens, made up under various manufacturing conditions, were subjected to various climatic changes inducing internal stresses and then were tested.
Date: January 1, 1923
Creator: Heim, A L; Knauss, A C & Seutter, Louis
Partner: UNT Libraries Government Documents Department

Lift and drag effects of wing-tip rake

Description: This report deals with a description and report of tests carried out at the Washington Navy Yard on models of the RAF-6, albatross and Slone airfoils to determine the effectiveness of the conventional wing-trailing edge being always longer than the leading edge. The results are compared with the values computed by standard formulae in use at the time the tests were conducted.
Date: January 1, 1923
Creator: Zahm, A. F.; Bear, R. M. & Hill, G. C.
Partner: UNT Libraries Government Documents Department

Mathematical equations for heat conduction in the fins of air-cooled engines

Description: The problem considered in this report is that of reducing actual geometrical area of fin-cooling surface, which is, of course, not uniform in temperature, to equivalent cooling area at one definite temperature, namely, that prevailing on the cylinder wall at the point of attachment of the fin. This makes it possible to treat all the cooling surface as if it were part of the cylinder wall and 100 per cent effective. The quantities involved in the equations are the geometrical dimensions of the fin, thermal conductivity of the material composing it, and the coefficient of surface heat dissipation between the fin and the air streams.
Date: January 1, 1923
Creator: Harper, R R & Brown, W B
Partner: UNT Libraries Government Documents Department

The Minimum Induced Drag of Aerofoils

Description: This report helps explain the phenomenon of flight. It contains some theorems concerning the arrangement of airplane wings which are of considerable practical interest. In particular, it shows the theoretical reasons for the decrease of drag which accompanies all increase in the aspect ratio or lateral extension of a wing. The efficiency of a given arrangement of wings may be calculated from the formulae derived in this paper.
Date: January 1, 1923
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department

Nomenclature for aeronautics

Description: This nomenclature for aeronautics was prepared by a special conference on aeronautical nomenclature, composed of representatives of the Army and Navy Air Services, the Air Mail Service, the Bureau of Standards, the National Advisory Committee for Aeronautics, and private life. This report supersedes all previous publications of the committee on this subject. It is published with the intention of securing greater uniformity and accuracy in official documents of the government, and, as far as possible, in technical and other commercial publications. (author).
Date: January 1, 1923
Partner: UNT Libraries Government Documents Department

Performance of B. M. W. 185-Horsepower Airplane Engine

Description: This report deals with the results of a test made upon a B. M. W. Engine in the altitude chamber of the Bureau of Standards, where controlled conditions of temperature and pressure can be made to simulate those of the desired altitude. A remarkably low value of fuel consumption - 041 per B. H. P. hour - is obtained at 1,200 revolutions per minute at an air density of 0.064 pound per cubic foot and a brake thermal efficiency of 33 per cent and an indicated efficiency of 37 per cent at the above speed and density. In spite of the fact that the carburetor adjustment does not permit the air-fuel ratio of maximum economy to be obtained at air densities lower than 0.064, the economy is superior to most engines tested thus far, even at a density lower than 0.064, the economies superior to most engines tested thus far, even at a density (0.03) corresponding to an altitude of 25,000 feet. The brake mean effective pressure even at full throttle is rather low. Since the weight of much of the engine is governed more by its piston displacement than by the power developed, a decreased mean effective pressure usually necessitates increased weight per horsepower. The altitude performance of the engine is, in general, excellent, and its low fuel consumption is the outstanding feature of merit.
Date: January 1, 1923
Creator: Sparrow, S W
Partner: UNT Libraries Government Documents Department

Performance of Maybach 300-horsepower airplane engine

Description: This report contains the results of a test made upon a Maybach Engine in the altitude chamber of the Bureau of Standards, where controlled conditions of temperature and pressure can be made the same as those of the desired altitude. The results of this test lead to the following conclusions: from the standpoint of thermal efficiency the full-load performance of the engine is excellent at densities corresponding to altitudes up to and including 15,000 feet. The brake mean effective pressure is rather low even at wide-open throttle. This tends to give a high weight per horsepower, in as much as the weight of many engine parts is governed by the size rather than the power of the engine. At part load the thermal efficiency of the engine is low. Judged on a basis of performance the engine's chief claim to interest would appear to lie in the carburetor design, which is largely responsible excellent full-load efficiency and for its poor part-load efficiency.
Date: January 1, 1923
Creator: Sparrow, S W
Partner: UNT Libraries Government Documents Department

Point drag and total drag of navy struts no. 1 modified

Description: This report deals with the results of tests on struts conducted at Washington Navy Yard. Two models of the modified Navy strut, no. 1, were tested in the 8 by 8 foot wind tunnel. The tests were made to determine the total resistance end effect and the pressure distribution at various wind-tunnel speeds with the length of the strut transverse to the current. Only the measurements made at zero pitch and yaw are given in this report.
Date: January 1, 1923
Creator: Zahm, A. F.; Smith, R. H. & Hill, G. C.
Partner: UNT Libraries Government Documents Department