National Advisory Committee for Aeronautics (NACA) - 21 Matching Results

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The aerodynamic aspect of wing-fuselage fillets

Description: Report discussing model tests prove the feasibility of enhancing the aerodynamic qualities of wing-fuselage fillets by appropriate design of fuselage and wing roots. Abrupt changes from maximum fuselage height to wing chord must be avoided and every longitudinal section of fuselage and wing roots must be so faired and arranged as to preserve the original lift distribution of the continuous wing. Adapting the fuselage to the curvilinear circulation of the wing affords further improvement. The polars of such arrangements are almost the same as those of the "wing alone," thus voiding the superiority of the high-wing type airplane known with conventional design.
Date: February 1935
Creator: Muttray, H
Partner: UNT Libraries Government Documents Department

The Denis-Gruson six-component wind-tunnel balance

Description: The 6.C.1 balance is the first fully automatic balance assuring a continuous and simultaneous record of the aerodynamic characteristics of an airfoil in a wind tunnel. Because of the rapidity of the measurements a complete polar (six components) requires only about three minutes of wind, that is to say, of motive power, which is of interest for wind tunnels with high efficiency factors and may lead to the economical design of large size wind tunnels.
Date: July 1, 1935
Partner: UNT Libraries Government Documents Department

A discussion of the several types of two-stroke-cycle engines

Description: This report discusses different types of two-stroke engines as well as the three most important design factors: volume of scavenge and charge delivery, scavenging process (scavenging result), and result of charge. Some of the types of engines discussed include: single cylinder with crank-chamber scavenge pump and auxiliary suction piston linked to working connecting rod; and two cylinder engines with a rotary scavenge pump arrangement. Three and four cylinder engines are also discussed in various designs.
Date: September 1, 1935
Creator: Venediger, Herbert J
Partner: UNT Libraries Government Documents Department

Effect of aerodynamic design on glider performance

Description: The performance of a glider is determined by means of the velocity polar, which represents the connection between horizontal and sinking speed. The mean sinking speed for a given speed range can be determined on the basis of the velocity polar. These data form the basis for the most propitious design of a performance-type glider with a view to long-distance flight.
Date: January 1935
Creator: Lippisch, A.
Partner: UNT Libraries Government Documents Department

Experiments with Suction-Type Wings

Description: The present report collects the investigations of the past years which, while not as yet intended for use in construction, show different possibilities for the building of a suction-type wing and at the same time present some basic explanations concerning the problem of suction. Experiments and results with a thick wing profile are detailed as well as boundary layer removal by suction and sink action. Experiments with flap profiles are also included.
Date: August 1, 1935
Creator: Schrenk, O.
Partner: UNT Libraries Government Documents Department

Gliding in convection currents

Description: A survey of the possibilities of gliding in convection currents reveals that heretofore only the most simple kind of ascending convection currents, that is, the "thermic" of insolation, has been utilized to any extent. With the increasing experience in gliding, the utilization of the peculiar nature of the "wind thermic" and increased glider speed promises further advances. Evening, ocean, and height "thermic" are still in the exploration stage, and therefore not amenable to survey in their effects.
Date: January 1, 1935
Creator: Georgii, W
Partner: UNT Libraries Government Documents Department

The heat transfer of cooling fins on moving air

Description: The present report is a comparison of the experimentally defined temperature and heat output of cooling fins in the air stream with theory. The agreement is close on the basis of a mean coefficient of heat transfer with respect to the total surface. A relationship is established between the mean coefficient of heat transfer, the dimensions of the fin arrangement, and the air velocity.
Date: January 1, 1935
Creator: Doetsch, Hans
Partner: UNT Libraries Government Documents Department

Hydrodynamic tests of models of seaplane floats

Description: This report contains the results of tank tests carried out at free trim on seventeen hulls and floats of various types. The data as to the weight on water, trim, and relative resistance for each model are plotted nondimensionally and are referenced both to the total weight and to the weight on water. Despite the fact that the experiments were not made systematically, a study of the models and of the test data permits nevertheless some general deductions regarding the forms of floats and their resistance. One specific conclusion is that the best models have a maximum relative resistance not exceeding 20 percent of the total weight.
Date: May 1, 1935
Creator: Eula, Antonio
Partner: UNT Libraries Government Documents Department

The interdependence of profile drag and lift with Joukowski type and related airfoils

Description: On the basis of a systematic investigation of Gottingen wind-tunnel data on Joukowski type and related airfoils, it is shown in what manner the profile drag coefficient is dependent on the lift coefficient. The individual factors for the construction of the profile drag polars are given. They afford a more accurate calculation of the performance coefficients of airplane designs than otherwise attainable with the conventional assumption of constant drag coefficient.
Date: March 1, 1935
Creator: Muttray, H
Partner: UNT Libraries Government Documents Department

Method for the determination of the spanwise lift distribution

Description: The method for determination of the spanwise lift distribution is based on the Fourier series for the representation of the lift distribution. The lift distribution, as well as the angle of attack, is split up in four elementary distributions. The insertion of the angle-of-attack distribution in the Fourier series for the lift distribution gives a compound third series which is of particular advantage for the determination of the lift distribution. The method is illustrated in an example and supplemented by a graphical method. Lastly, the results of several comparative calculations with other methods are reported.
Date: October 1935
Creator: Lippisch, A.
Partner: UNT Libraries Government Documents Department

Modification of wing-section shape to assure a predetermined change in pressure distribution

Description: In order to find an airfoil for a predetermined pressure distribution, the problem must be posed so that the pressure distribution creates no drag. Another fundamental difficulty is that it is impossible to specify a pressure distribution without first knowing the place where these pressures are to be applied, i.e., the wing-section shape. This difficulty may be avoided by directing the pressure distribution along the contour of the wing section. Then it becomes possible to define the change in wing-section shape which effects a certain modification of the wing-section shape. The limitations underlying the required pressure distribution are discussed and it is found that the sole essential limitation is zero drag. The method is illustrated with an example.
Date: March 1935
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department

Reduction of Lift of a Wing Due to Its Drag

Description: This analysis computes for a predetermined airfoil and given Reynolds Number the course of the "displacement thickness," i.e., the course of the layer by which the streamlines of the potential flow are pushed away from the wing through the frictional layer. The result is, to a certain extent, a new wing contour.
Date: November 1935
Creator: Stüper, J.
Partner: UNT Libraries Government Documents Department

Tension fields in originally curved, thin sheets during shearing stresses

Description: The analysis of the stresses in the sheet and stiffeners is predicated upon the direction of the wrinkles, particularly the tensile stresses (principal stresses). This analysis and the calculation of stresses after buckling form the subject of the present article. It includes: 1) metal cylinders with closely spaced longitudinal stiffeners; 2) metal cylinders with closely spaced transverse rings.
Date: August 1935
Creator: Wagner, H. & Ballerstedt, W.
Partner: UNT Libraries Government Documents Department

Tests of spheres with reference to Reynolds number, turbulence, and surface roughness

Description: The behavior of the Reynolds Number of the sphere is explained (in known manner) with the aid of the boundary-layer theory. Rear spindles may falsify, under certain conditions, the supercritical sphere drag, while suspension wires in the space behind the sphere leave no traceable influence. The critical Reynolds Number of the sphere was arrived at by an unconventional method; that is, by determining the critical wind speed at which the static pressure at the back of the sphere is the same as that of the undisturbed flow. The method makes it possible to interpret the critical Reynolds Number with only one test station.
Date: October 1, 1935
Creator: Hoerner, S
Partner: UNT Libraries Government Documents Department

Total-head meter with small sensitivity to yaw

Description: The total-head meter is essentially a venturi, housing a pitot tube for obtaining the total head. In yaw the flow within the nozzle is deflected, depending upon the degree of yaw, to a greater or lesser extent into the axial direction of the nozzle. After experimenting with several nozzle forms as to their suitability, the best design was finally adopted. When, with the chosen nozzle form, the total head is 0.5 entrance section diameter downstream, the instrument supplies the genuine total head at low Reynolds Numbers up to 43 degrees yaw.
Date: August 1, 1935
Creator: Kiel, G
Partner: UNT Libraries Government Documents Department

Weldability of high-tensile steels from experience in airplane construction, with special reference to welding crack susceptibility

Description: The concept of welding crack tendency is explained and illustrated with practical examples. All pertinent causes are enumerated, and experimental measures are given through which the secondary effects can be removed and the principal causes analyzed: 1) welding stresses; and 2) material defects. The variations in length and stresses incident to welding a small bar as free weld, with restrained elongation and restrained elongation and contraction, are explored in three fundamental experiments.
Date: November 1, 1935
Creator: Muller, J
Partner: UNT Libraries Government Documents Department