National Advisory Committee for Aeronautics (NACA) - 34 Matching Results

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Aerodynamic characteristics of a wing with quarter-chord line swept back 45 degrees, aspect ratio 6, taper ratio 0.6, and NACA 65A006 airfoil section

Description: Report discussing a wing-alone and wing-fuselage configuration with particular characteristics as part of a series of tests of wings using the transonic-bump test technique. Lift, drag, pitching moment, and root bending moment were obtained for the configurations. The effective downwash angles and dynamic-pressure characteristics in the tail region are also described.
Date: November 1, 1949
Creator: Goodson, Kenneth W. & Few, Albert G., Jr.
Partner: UNT Libraries Government Documents Department

Reduction of profile drag at supersonic velocities by the use of airfoil sections having a blunt trailing edge

Description: Report presenting a preliminary theoretical and experimental investigation of the supersonic characteristics of blunt-trailing-edge airfoils. Results regarding the drag measurements at zero lift, measurements at angle of attack, and a general discussion of the theoretical and experimental results is provided.
Date: November 1, 1949
Creator: Chapman, Dean R.
Partner: UNT Libraries Government Documents Department

Characteristics of a Sealed Internally Balanced Aileron from Tests of a 1/4-Scale Partial-Span Model of the Republic XF-12 Airplane in the Langley 19-Foot Pressure Tunnel

Description: This paper presents the results of the aileron investigation and includes rolling-moment, yawing-moment, and aileron hinge-moment coefficients and pressure coefficients across the aileron-balance seal through a range of angle of attack, tab deflection, and aileron deflection with flaps neutral and deflected 20 degrees and 55 degrees. Some of the effects of wing roughness and balance seal leakage on the aileron and tab characteristics are also presented.
Date: November 1, 1946
Creator: Graham, Robert R.; Martina, Albert P. & Salmi, Reino J.
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

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

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

The Wall Interference of a Wind Tunnel of Elliptic Cross Section

Description: The wall interference is obtained for a wind tunnel of elliptic section for the two cases of closed and open working sections. The approximate and exact methods used gave results in practically good agreement. Corresponding to the result given by Glauert for the case of the closed rectangular section, the interference is found to be a minimum for a ratio of minor to major axis of 1:square root of 6 This, however, is true only for the case where the span of the airfoil is small in comparison with the width of the tunnel. For a longer airfoil the favorable ellipse is flatter. In the case of the open working section the circular shape gives the minimum interference.
Date: November 1, 1944
Creator: Tani, Itiro & Sanuki, Matao
Partner: UNT Libraries Government Documents Department

Measurement of Oil-Film Pressures in Journal Bearings under Constant and Variable Loads

Description: In a study of journal bearings, the measurement of the oil-film strength produces some significant information. A new instrument is described by means of which the pressure of the oil film in bearings (under constant or alternating load) can be measured and recorded. With this device, the pressure distribution in the lubricating film of a bearing bushing was measured (under different operating conditions on a journal bearing) in the pulsator-bearing-testing machine. These tests are described and discussed in the present report.
Date: November 1, 1949
Creator: Buske, A. & Rolli, W.
Partner: UNT Libraries Government Documents Department

On the Motions of an Oscillating System Under the Influence of Flip-Flop Controls

Description: So-called flip-flop controls (also called "on-off-course controls") are frequently preferred to continuous controls because of their simple construction. Thus they are used also for the steering control of airplanes. Such a body possesses-even if one thinks, for instance, only of the symmetric longitudinal motion - three degrees of freedom so that a study of its motions under the influence of an intermittent control is at least lengthy. Thus, it is suggested that an investigation of the basic effect of such a control first be made on a system with one degree of freedom. Furthermore, we limit ourselves in the resent report to the investigation of an "ideal" control where the control surface immediately obeys the command given by the "steering control function". Thus the oscillation properties of the control surface and the defects in linkage, sensing element, and mixing device are, at first, neglected. As long as the deviations from the "ideal" control may be neglected in practice, also the motion of the control surface takes place at the heat of the motion of the principal system. The aim of our investigation is to obtain a survey of the influence of the system and control coefficients on the damping behavior which is to be attained.
Date: November 1, 1949
Creator: Fluegge-Lotz, I. & Klotter, K.
Partner: UNT Libraries Government Documents Department

Two-dimensional compressible flow in turbomachines with conic flow surfaces

Description: A general method of analysis is developed for two-dimensional, steady, compressible flow in stators or rotors of radial and mixed flow turbomachines with conic flow surfaces (surfaces of right circular cones generated by center line of flow passage in the axial-radial plane). The variables taken into account are: (1) tip speed of the rotor, (2) flow rate, (3) blade shape, (4) variation in passage height with radius, (5) number of blades, and (6) cone angle of the flow surface. Relaxation methods are used to solve the nonlinear differential equation for the stream function. Two numerical examples are presented; one for compressible and the other for incompressible flow in a centrifugal compressor with thin, straight blades. The results of these examples are given by plots of the streamlines, constant velocity-ratio lines, and constant pressure-ratio line.
Date: November 1, 1948
Creator: Stanitz, John D.
Partner: UNT Libraries Government Documents Department

Effects of Compressibility on the Maximum Lift Characteristics and Spanwise Load Distribution of a 12-Foot-Span Fighter-Type Wing of NACA 230-Series Airfoil Sections

Description: Lift characteristics and pressure distribution for a NACA 230 wing were investigated for an angle of attack range of from -10 to +24 degrees and Mach range of from 0.2 to 0.7. Maximum lift coefficient increased up to a Mach number of 0.3, decreased rapidly to a Mach number of 0.55, and then decreased moderately. At high speeds, maximum lift coefficient was reached at from 10 to 12 degrees beyond the stalling angle. In high-speed stalls, resultant load underwent a moderate shift outward.
Date: November 1, 1945
Creator: West, F E
Partner: UNT Libraries Government Documents Department

Effect of threaded and serrated holes on the limited time and fatigue strength of flat light-alloy strips

Description: The investigation was made for the purpose of ascertaining the notch sensitivity of flat strips of light alloy with cylindrical holes under initial tension stress, with special attention to the change in notch-effect factors with the number of load cycles. Then the studies were extended to similar flat strips with pin-loaded holes (tension lugs). This report deals with fatigue tests under initial tension load on flat test specimens of 3116.5 duralumin and AZM 3510.1 electron with plain unloaded and pin-loaded holes (tension lugs) of different forms.
Date: November 1, 1941
Creator: Burnheim, H
Partner: UNT Libraries Government Documents Department