National Advisory Committee for Aeronautics (NACA) - 1,437 Matching Results

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Analytical methods for computing the polar curves of airplanes

Description: This report presents a method of calculating polar curves which is at least as precise as graphical methods, but it more rapid. Knowing the wind tunnel test of a wing and the performances of an airplane of the same profile, it is easy to verify the characteristic coefficients and, at the same time, the methods determining induced resistances.
Date: March 1921
Creator: Le Sueur
Partner: UNT Libraries Government Documents Department

Air forces and air-force moments at large angles of attack and how they are affected by the shape of the wing

Description: 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."
Date: July 1930
Creator: Fuchs, Richard & Schmidt, Wilhelm
Partner: UNT Libraries Government Documents Department

Air reactions to objects moving at rates above the velocity of sound with application to the air propeller

Description: From Discussion: "To meet these unusual conditions three sets of ball-bearings were employed and arranged in tandem, thereby reducing their speeds by the ratio of the number of sets used, as shown in Fig.3. This proved to be a complete success. The results obtained in experiments with a two-blade, 4 foot propeller of series 2, are given in Fig. 9."
Date: November 1922
Creator: Reed, S. Albert
Partner: UNT Libraries Government Documents Department

Combined pitching and yawing motion of airplanes

Description: This report treats the following problems: The beginning of the investigated motions is always a setting of the lateral controls, i.e., the rudder or the ailerons. Now, the first interesting question is how the motion would proceed if these settings were kept unchanged for some time; and particularly, what upward motion would set in, how soon, and for how long, since therein lie the dangers of yawing. Two different motions ensue with a high rate of turn and a steep down slope of flight path in both but a marked difference in angle of attack and consequently different character in the resultant aerodynamic forces: one, the "corkscrew" dive at normal angle, and the other, the "spin" at high angle.
Date: May 1931
Creator: Baranoff, A. V. & Hopf, L.
Partner: UNT Libraries Government Documents Department

Analytical theory of the Campini propulsion system

Description: From Summary: "The present report deals exclusively with the particular jet-propulsion system mentioned in the cited reports. The discussion is limited, for the present, to the analytical study of the efficiency and the consumption for the case of application to aircraft and to the plotting of the practical operating curves secured theoretically by the use of suitable experimental factors."
Date: March 1942
Creator: Campini, S
Partner: UNT Libraries Government Documents Department

The apparent width of the plate in compression

Description: This report discusses an investigation that treats the load capacity of a rectangular plate stressed in compression on one direction (x) beyond the buckling limit and the plate is rotatable (i.e., free from moments) supported at all four sides by bending-resistant beams.
Date: July 1937
Creator: Marguerre, Karl
Partner: UNT Libraries Government Documents Department

Aerodynamic computation of gliders

Description: From Introduction: "In the following discussion, a knowledge of the theoretical principles of airplane construction is assumed, as presented in detail by Vogt and Lippisch in Nos. 7 and 10-19 of the 1919 volume of this publication. A few quantities will however be otherwise designated, in accordance with the Gottingen symbols."
Date: September 1922
Creator: Schrenk, M
Partner: UNT Libraries Government Documents Department

Behavior of vortex systems

Description: Progressive application of the Kutta-Joukowsky theorem to the relationship between airfoil lift and circulation affords a number of formulas concerning the conduct of vortex systems. The application of this line of reasoning to several problems of airfoil theory yields an insight into many hitherto little observed relations. This report is confined to plane flow, hence all vortex filaments are straight and mutually parallel (perpendicular to the plane of flow).
Date: June 1933
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department

Apparatus for measurements of time and space correlation

Description: The report describes a brief review is made of improvements to an experimental apparatus for time and space correlation designed for study of turbulence. Included is a description of the control of the measurements and a few particular applications.
Date: April 1955
Creator: Favre, Alexandre; Gaviglio, J & Dumas, R
Partner: UNT Libraries Government Documents Department

Experiments on a tail-wheel shimmy

Description: Model tests on the "running belt" and tests with a full-scale tail wheel were made on a rotating drum as well as on a runway in order to investigate the causes of the undesirable shimmy phenomena frequently occurring on airplane tail wheels, and the means of avoiding them. The small model (scale 1:10) permitted simulation of the mass, moments of inertia, and fuselage stiffness of the airplane and determination of their influence on the shimmy, whereas by means of the larger model with pneumatic tires (scale 1:2) more accurate investigations were made on the tail wheel itself. The results of drum and road tests show good agreement with one another and with model values. Detailed investigations were made regarding the dependence of the shimmy tendency on trail, rolling speed, load, size of tires, ground friction,and inclination of the swivel axis; furthermore, regarding the influence of devices with restoring effect on the tail wheel, and the friction damping required for prevention of shimmy. Finally observations from slow-motion pictures are reported and conclusions drawn concerning the influence of tire deformation.
Date: October 1954
Creator: Dietz, O. & Harling, R.
Partner: UNT Libraries Government Documents Department

Experiments with an airfoil from which the boundary layer is removed by suction

Description: Our attempts to improve the properties of airfoils by removing the boundary layer by suction, go back to 1922. The object of the suction is chiefly to prevent the detachment of the boundary layer from the surface of the airfoil. At large angles of attack, such detachment prevents the attainment of the great lift promised by the theory, besides greatly increasing the drag, especially of thick airfoils. This report gives results of those experiments.
Date: August 1926
Creator: Ackeret, J.; Betz, A. & Schrenk, O.
Partner: UNT Libraries Government Documents Department

Experiments on a slotted wing

Description: The results of pressure distribution measurements that were made on a model wing section of a Fieseler F 5 R type airplane are presented. Comparison of those model tests with the corresponding flight tests indicates the limitations and also the advantages of wind tunnel investigations, the advantages being particularly that through the variety of measuring methods employed the more complicated flow conditions may also be clarified. A fact brought out in these tests is that even in the case of "well rounded" slots it is possible for a vortex to be set up at the slot entrance and this vortex is responsible for certain irregularities in the pressure distribution and in the efficiency of the slot.
Date: March 1939
Creator: Ruden, P.
Partner: UNT Libraries Government Documents Department

Experiments on airfoils with aileron and slot

Description: The present report contains the results of a few experiments on three airfoils to which the rear portions, having chords respectively 1/4, 1/3, and 2/5 of the total chords, are hinged so as to form ailerons, especial attention being given to the shape of the slot between the aileron and the main portion of the aileron.
Date: November 1927
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department

Experimental study of flow past turbine blades

Description: From Introduction: "The requirements on gas turbines for aircraft power units, namely, adequate efficiency, operation at high gas temperatures, low weight, and small dimensions, must be taken into consideration during the design of the blading. To secure good efficiency, it is necessary that the gas flow past the blades as smoothly as possible without separation. This is relatively easily obtainable in the accelerated flow of turbine blading, if the blade spacing is chosen small enough. A small blade spacing, however, is detrimental to the other requirements outlined above. Operation at high gas temperatures usually calls for blade cooling. This cooling is associated with a power input that lowers the turbine efficiency. Since the amount of heat that must be carried off for coding a blade can be influenced rather little, the gross power input for a turbine stage can be reduced by keeping the number of blades to a minimum, that is, with blades of high spacing ratio. But here also a limit is imposed, the exceeding of which is followed by separation of flow. Hence the requirement of finding blade forms on which the flow separates at rather high spacing ratios."
Date: June 1949
Creator: Eckert, E. & Vietinghoff-Scheel, K. V.
Partner: UNT Libraries Government Documents Department

The Heat Transfer to a Plate in Flow at High Speed

Description: From Summary: "The heat transfer in the laminar boundary layer of a heated plate in flow at high speed can be obtained by integration of the conventional differential equations of the boundary layer, so long as the material values can be regarded as constant. This premise is fairly well satisfied at speeds up to about twice the sonic speed and at not excessive temperature rise of the heated plate. The general solution of the equation includes Pohlhausen's specific cases of heat transfer to a plate at low speeds and of the plate thermometer. The solution shows that the heat transfer coefficient at high speed must be computed with the same equation as at low speed, when it is referred to the difference of the wall temperature of the heated plate in respect to its "natural temperature." Since this fact follows from the linear structure of the differential equation describing the temperature field, it is equally applicable to the heat transfer in the turbulent boundary layer."
Date: May 1943
Creator: Eckert, E. & Drewitz, O.
Partner: UNT Libraries Government Documents Department

The 5- by 7-meter wind tunnel of the DVL

Description: The report contains a description of the DVL wind tunnel. According to the cones fixed, an elliptical stream with axes 5 by 7 meters and length 9 meters, or a stream 6 by 8 meters in cross section and 11 meters in length is available. The top speed with the smaller cone is 65 meters per second. The testing equipment consists of an automatic six-component balance and a test rig for propellers and engines up to 650 horsepower.
Date: March 1936
Creator: Kramer, M.
Partner: UNT Libraries Government Documents Department

Systematic airfoil tests in the large wind tunnel of the DVL

Description: The present report is a description of systematic tests at maximum lift on airfoils with and without split flap and of profile drag at low lift. In order to obtain an opinion as to the suitability of the airfoils with flaps, the maximum-lift measurements were repeated on airfoils with split flaps. The profile drag at low lift was arrived at by direct weighing and momentum measurements and, since the profiles were of unusual depth, extended to large Reynolds numbers.
Date: March 1938
Creator: Doetsch, H. & Kramer, M.
Partner: UNT Libraries Government Documents Department

Tests for the determination of the stress condition in tension fields

Description: The present experiments treat the stress of actual tension fields within the elastic range. They give the magnitude of the flexural stresses due to wrinkling. They also disclose, particularly by slightly exceeded buckling load, the marked unloading - as compared with the tension-field theory - of the uprights as a result of the flexural stiffness of the web plate. The test sheets were clamped at the edges and brought to buckling through shearing and compressive stresses applied in the direction of the long sides.
Date: November 1936
Creator: Lahde, R. & Wagner, H.
Partner: UNT Libraries Government Documents Department

Statistical analysis of the time and fatigue strength of aircraft wing structures

Description: The results from stress measurements in flight operation afford data for analyzing the frequency of appearance of certain parts of the static breaking strength during a specified number of operating hours. Appropriate frequency evaluations furnish data for the prediction of the required strength under repeated stress in the wing structures of aircraft of the different stress categories for the specified number of operating hours demanded during the life of a component.
Date: October 1941
Creator: Kaul, Hans W.
Partner: UNT Libraries Government Documents Department