National Advisory Committee for Aeronautics (NACA) - 64 Matching Results

Search Results

The shock-absorbed system of the airplane landing gear

Description: A discussion is given of the behavior of the shock-absorbing system, consisting of elastic struts and tires, under landing, take-off, and taxying conditions, and a general formula derived for obtaining the minimum stroke required to satisfy the conditions imposed on the landing gear. Finally, the operation of some typical shock-absorbing systems are examined and the necessity brought out for taking into account, in dynamic landing-gear tests, the effect of the wing lift at the instant of contact with the ground.
Date: March 1, 1940
Creator: Callerio, Pietro
Partner: UNT Libraries Government Documents Department

The elliptic wing based on the potential theory

Description: This article is intended as a contribution to the theory of the lifting surface. The aerodynamics of the elliptic wing in straight and oblique flow are explored on the basis of potential theory. The foundation of the calculation is the linearized theory of the acceleration potential in which all small quantities of higher order are disregarded.
Date: March 1, 1941
Creator: Krienes, Klaus
Partner: UNT Libraries Government Documents Department

Experimental investigations on freely exposed ducted radiators

Description: This report deals with the relation between the open areas, the drag, and the air flow as observed on freely exposed, ducted radiators - the air conductivity being modified from zero to one unit. In conjunction with theoretical results, the individual components of the drag of ducted radiators are discussed and general rules established for low-loss ducts. The influence of the wall thickness of the ducts, of the length ratio of the exit, and the effects of sonic velocity on diffusers are dealt with by special measurement.
Date: March 1, 1941
Creator: Linke, W
Partner: UNT Libraries Government Documents Department

Tests of round and flat spoilers on a tapered wing in the NACA 19-foot pressure wind tunnel

Description: Several arrangements of round and flat spanwise spoilers attached to the upper surface of a tapered wing were tested in the NACA 19-foot pressure wind tunnel to determine the most effective type, location, and size of spoiler necessary to reduce greatly the lift on the wings of large flying boats when moored. The effect of the various spoilers on the lift, the drag, and the pitching-moment characteristics of the tapered wing was measured over a range of angles of attack from zero to maximum lift. The most effective type of spoiler was found to be the flat type with no space between it and the wing surface. The chordwise location of such a spoiler was not critical within the range investigated, from 5 to 20 percent of the wing chord from the leading edge.
Date: March 1, 1941
Creator: Wenzinger, Carl J. & Bowen, John D.
Partner: UNT Libraries Government Documents Department

Tests on stiffened circular cylinders

Description: Compressive tests were made of two series of stiffened circular cylindrical shells under axial load. All the shells were 16 inches in diameter by 24 inches in length and were made of aluminum-alloy sheet curved to the proper radius and welded with one longitudinal weld. The ratios of diameter to thickness of shell wall in the two series of specimens were 258 and 572. Strains were measured with Huggenberger tensometers at a number of gage lines on the stiffeners and shell. The results of these tests indicate that a spacing of circumferential stiffeners equal to 0.67 times the radius is too great to strengthen the shell wall appreciably. The results are not inclusive enough to show the optimum in stiffeners. Plain cylinders without stiffeners developed ultimate strengths approximately half as great as the buckling strengths computed by the equation resulting from the classical theory and slightly greater than those computed by Donnell's large deflection theory.
Date: March 1, 1941
Creator: Holt, Marshall
Partner: UNT Libraries Government Documents Department

Use of charts for flow discharge calculations

Description: Various problems in connection with engine design involve flow-discharge calculations which are rendered difficult both on account of the large number of external variables that enter into the computation - i.e., changes in discharge area during the process, change in volume of the cylinder, pressure, etc., and changes in the thermal constants themselves of the flow medium. A fairly accurate solution that does not involve an excessive amount of labor can be obtained only through the extensive use of i-s tables. In the present report, a solution is offered in the form of a different method making use of the I-S table of Lutz and Wolf.
Date: March 1, 1941
Creator: Lutz, O
Partner: UNT Libraries Government Documents Department

Electrical equipment for the experimental study of the dynamics of fluids

Description: This report contains the description of electric anemometers and their application to the study of turbulent fluid flows, of electric tanks for the realization of the analogies between electrology and aerodynamics and their application to the study of varied technical problems, and lastly of the electric condenser type dynamometer and its application to the prediction of the aerodynamic forces on wing and airplane models in wind-tunnel tests and in controlled and spontaneous rotations.
Date: March 1, 1942
Creator: Ferrari, Carlo
Partner: UNT Libraries Government Documents Department

Investigation of the forces acting on gliders in automobile-pulley-winch and airplane towed flight

Description: The magnitude, the direction, and the fluctuation of towing forces exerted upon gliders by towing them aloft behind an automobile, by means of a winch, and by airplane were measured under a variety of conditions covering a range from gentle to severe types of operation. For these tests the towing forces did not exceed 92 percent of the gross weight of the glider. The results indicate that in pulley and winch towing the towing forces are of about the same magnitude as in automobile towing. Speed increases in the accelerated phases of the towing jerks encountered in airplane towing can readily become critical as speeds in excess of placard speeds can be attained. Passage through the slipstream of the towing airplane can be equivalent to a severe gust that, at high speed, may impose high wing loads and require large control moments.
Date: March 1, 1942
Creator: Klemperer, W B
Partner: UNT Libraries Government Documents Department

Turbulent flow between rotating cylinders

Description: The turbulent air flow between rotating cylinders was investigated. The distributions of mean speed and of turbulence were measured in the gap between a rotating inner and a stationary outer cylinder. The measurements led to the conclusion that the turbulent flow in the gap cannot be considered two dimensional, but that a particular type of secondary motion takes place. It is shown that the experimentally found velocity distribution can be fully understood under the assumption that this secondary motion consists of three-dimensional ring-shape vortices. The vortices occur only in pairs, and their number and size depend on the speed of the rotating cylinder; the number was found to decrease with increasing speed. The secondary motion has an essential part in the transmission of the moment of momentum. In regions where the secondary motion is negligible, the momentum transfer follows the laws known for homologous turbulence. Ring-shape vortices are known to occur in the laminar flow between rotating cylinders, but it was hitherto unknown that they exist even at speeds that are several hundred times the critical limit.
Date: March 1, 1943
Creator: Shih-I, Pai
Partner: UNT Libraries Government Documents Department

The Theory of a Free Jet of a Compressible Gas

Description: In the present report the theory of free turbulence propagation and the boundary layer theory are developed for a plane-parallel free stream of a compressible fluid. In constructing the theory use was made of the turbulence hypothesis by Taylor (transport of vorticity) which gives best agreement with test results for problems involving heat transfer in free jets.
Date: March 1, 1944
Creator: Abramovich, G. N.
Partner: UNT Libraries Government Documents Department

The Minimum Energy Loss Propeller

Description: Various cases are presented of the solution of the problem ot the most efficient propeller, more general cases being considered than the one by Betz in 1919: namely, that of a propeller under a limiting light load, The problem is solved directly and also with the aid of the Ritz method which became readily applicable after the author proposed a method for the solution of the propeller problem, in general, with the aid of trigonometric series. The design of a propeller with the aid of this method is given and an analysis is made of the effect of the fuselage and of the viscosity coefficient mu on the character of the solution of the variational problem.
Date: March 1, 1945
Creator: Poliakhov, N.
Partner: UNT Libraries Government Documents Department