National Advisory Committee for Aeronautics (NACA) - 365 Matching Results

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The Compressive Yield Strength of Extruded Shapes of 24st Aluminum Alloy

Description: The following report discusses an investigation that was made to determine the tensile and the compressive properties of a large number of 24ST extruded shapes selected at random from commercial production in order to investigate the interrelation of these properties.
Date: January 1, 1941
Creator: Templin, R. L.; Howell, F. M. & Hartmann, E. C.
Partner: UNT Libraries Government Documents Department

Notes on the Stability and Control of Tailless Airplanes

Description: Problems involved in the stability and control of tailless airplanes are discussed. Such factors as the location of the aerodynamic center and its effect on the longitudinal stability, longitudinal trim with high-lift devices, the effects of various changes in the shape of the wing on lateral stability, and the effects of nacelles are covered. It appears that sufficient stability and controllability can be secured without sweepback. With sweepback, a flap over the center section of the wing may be used to serve the dual purpose of elevator control and high-lift device. Sweepback introduces undesirable stalling characteristics, however, and may require auxiliary devices to prevent stalling of the tips.
Date: January 1, 1941
Creator: Jones, Robert
Partner: UNT Libraries Government Documents Department

Comparison of Vee-Type and Conventional Tail Surfaces in Combination with Fuselage and Wing in the Variable-Density Tunnel

Description: Report discussing the pitching and yawing of a vee-type tail and a conventional tail surface and the method used to calculate the yawing-moment to pitching-moment ratio. From Summary: "The pitching and the yawing moments of a vee-type and a conventional type of tail surface were measured. The tests were made in the presence of a fuselage and a wing-fuselage combination in such a way as to determine the moments contributed by the tail surfaces."
Date: July 1, 1941
Creator: Greenberg, Harry
Partner: UNT Libraries Government Documents Department

Development of Cowling for Long-Nose Air-Cooled Engine in the NACA Full-Scale Wind Tunnel

Description: An investigation of cowlings for long-nose radial engines was made on the Curtiss XP-42 fighter in the NACA full-scale wind tunnel. The unsatisfactory aerodynamic characteristics of all the cowlings with scoop inlets tested led to the development of the annular high-velocity inlet cowlings. Tests showed that ratio of cooling-air velocity at cowling inlet to stream velocity should not be less than 0.5 for this type of cowling and that critical compressibility speed can be extended to more than 500 mph at 20,000 ft altitude.
Date: October 1, 1941
Creator: Guryansky, Eugene R. & Silverstein, Abe
Partner: UNT Libraries Government Documents Department

Flight Investigation of Wing-Gun Fairings on a Fighter Type Airplane

Description: Description is given of flight tests conducted on gun fairings, designed to correct the detrimental effects of the projecting and submerged wing guns on an F4F-3 fighter. It was found that the installation of unfaired guns on a clean wing resulted in a premature stall that increased the stalling speed in the carrier-approach and landing conditions of flight by suitably fairing the guns, it was possible to reduce the stalling speeds to values approaching very nearly the clean-wing values.
Date: October 1, 1941
Creator: White, M. D.
Partner: UNT Libraries Government Documents Department

Column Strength of Magnesium Alloy AM-57S

Description: Tests were made to determine the column strength of extruded magnesium alloy AM-57S. Column specimens were tested with round ends and with flat ends. It was found that the compressive properties should be used in computations for column strengths rather than the tensile properties because the compressive yield strength was approximately one-half the tensile yield strength. A formula for the column strength of magnesium alloy AM-57S is given.
Date: July 1, 1942
Creator: Holt, M.
Partner: UNT Libraries Government Documents Department

Two-Dimensional Potential Flow Past an Ordinary Thick Wing Profile

Description: This report deals with the development of a method which gives a lucid and convenient solution of the flow conditions in the vicinity of a common, thick airfoil section wherein the thickness of the profile is taken into account. The method consists in making the airfoil the streamline in a parallel flow by disposing on its mean line certain source and vortex distributions the fields of which are superposed on the parallel flow. These distributions of singularities are secured for the generalized Karman-Trefftz profile by means of conformal transformation from the flow about a circle. Five different distribution functions are afforded for the density of superposition, which combine in a specified manner to the necessary distributions of singularity and represent a generalized Karman-Trefftz profile in parallel flow. For these profiles the speed for each of the five distributions is then computed independently of the angle of attack.
Date: July 1, 1942
Creator: Keune, F.
Partner: UNT Libraries Government Documents Department

The Formation of Ice on Aircraft

Description: The phenomenon accompanying the formation of ice on aircraft has been frequently discussed. The consequences of ice formation have been briefly analyzed in an article , but a definite physical solution of the problem has not been reached up to the present. Most of the authors agree that subcooled water droplets play a prominent part, but they fail to specify the exact manner in which this occurs.
Date: August 1, 1942
Creator: Bleeker, W.
Partner: UNT Libraries Government Documents Department

The Icing of Aircraft

Description: This technical memorandum presents a theoretical study of the processes accompanying the formation of ice on solid bodies. It discusses vapor pressure and sublimation in two air masses separated by a boundary area.
Date: September 1, 1942
Creator: Robitzsch, M.
Partner: UNT Libraries Government Documents Department

The Navier-Stokes Stress Principle for Viscous Fluids

Description: The Navier-Stokes stress principle is checked in the light of Maxwell's mechanism of friction and in connection herewith the possibility of another theorem is indicated. The Navier-Stokes stress principle is in general predicated upon the conception of the plastic body. Hence the process is a purely phenomenological one, which Newton himself followed with his special theorem for one-dimensional flows. It remained for Maxwell to discover the physical mechanism by which the shear inflow direction is developed: According to it, this shear is only 'fictitious' as it merely represents the substitute for a certain transport on macroscopic motion quantity, as conditioned by Brown's moiecular motion and the diffusion, respectively. It is clear that this mechanism is not bound to the special case of the one-dimensioilal flows, but holds for any flow as expression of the diffusion, by which a fluid differs sharply from a plastic body. If it is remembered, on the other hand, that the cause of the stresses on the plastic body lies in a certain cohesion of the molecules, it appears by no means self evident that this difference in the mechanism of friction between fluid and plastic body should not prevail in the stress principle as well, although it certainly is desirable in any case, at least subsequently, to establish the general theorem in the sense of Maxwell. Actually, a different theorem is suggested which, in contrast to that by Navier-Stokes, has the form of an unsymmetrical matrix. Without anticipating a final decision several reasons are advanced by way of a special flow which seem to affirm this new theorem. To make it clear that the problem involved here still awaits its final solution, is the real purpose behind the present article.
Date: September 1, 1942
Creator: Mohr, Ernst
Partner: UNT Libraries Government Documents Department

The Compressible Potential Flow Past Elliptic Symmetrical Cylinders at Zero Angle of Attack and with No Circulation

Description: For the tunnel corrections of compressible flows those profiles are of interest for which at least the second approximation of the Janzen-Rayleigh method can be applied in closed form. One such case is presented by certain elliptical symmetrical cylinders located in the center of a tunnel with fixed walls and whose maximum velocity, incompressible, is twice the velocity of flow. In the numerical solution the maximum velocity at the profile and the tunnel wall as well as the entry of sonic velocity is computed. The velocity distribution past the contour and in the minimum cross section at various Mach numbers is illustrated on a worked out-example.
Date: October 1, 1942
Creator: Hantzsche, W. & Wendt, H.
Partner: UNT Libraries Government Documents Department

Contribution to the Design of Plywood Shells

Description: The writer sets out to prove by calculation and experiment that by extensive utilization of the skin to carry axial load (reduction of stringer spacing) the stringer sections can be made small enough to afford a substantial saving in structural weight. This saving ranges from 5 to about 40 percent.
Date: October 1, 1942
Creator: Blumrich, S.
Partner: UNT Libraries Government Documents Department

Heat Transfer in the Turbulent Boundary Layer of a Compressible Gas at High Speeds

Description: The Reynolds law of heat transfer from a wall to a turbulent stream is extended to the case of flow of a compressible gas at high speeds. The analysis is based on the modern theory of the turbulent boundary layer with laminar sublayer. The investigation is carried out for the case of a plate situated in a parallel stream. The results are obtained independently of the velocity distribution in the turbulent boundar layer.
Date: October 1, 1942
Creator: Frankl, F.
Partner: UNT Libraries Government Documents Department

Control of Torsional Vibrations by Pendulum Masses

Description: Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain vibrations. Unexplained, so far, remains the problem of behavior of pendulum masses in other critical zones to which they are not tuned, their dynamic behavior at some tuning other than in resonance, and their effect within a compound vibration system and at simultaneous application of several differently tuned pendulous masses. These problems are analyzed in the present report. The results constitute an enlargement of the scope of application of pendulum masses, especially for in-line engines. Among other things it is found that the natural frequency of a system can be raised by means of a correspondingly tuned pendulum mass. The formulas necessary for the design of any practical version are developed, and a pendulum mass having two different natural frequencies simultaneously is described.
Date: November 1, 1942
Creator: Stieglitz, Albert
Partner: UNT Libraries Government Documents Department

The Longitudinal Stability of Flying Boats as Determined by Tests of Models in the NACA Tank II : Effect of Variations in Form of Hull on Longitudinal Stability

Description: Data taken from tests at constant speed to establish trim limits of stability, tests at accelerated speeds to determine stable limits of center of gravity shift, and tests at decelerated speeds to obtain landing characteristics of several model hull forms were used to establish hull design effect on longitudinal stability of porpoising. Results show a reduction of dead rise angle as being the only investigated factor reducing low trim limit. Various methods of reducing afterbody interference increased upper trim limit.
Date: November 1, 1942
Creator: Olson, Roland E. & Truscott, Starr
Partner: UNT Libraries Government Documents Department

Wind-Tunnel Investigations of Diving Brakes

Description: Unduly high diving speeds can be effectively controlled by diving brakes but their employment involves at the same time a number of disagreeable features: namely, rotation of zero lift direction, variation of diviving moment, and, the creation of a potent dead air region.
Date: November 1, 1942
Creator: Fucha, D.
Partner: UNT Libraries Government Documents Department