868 research outputs found
The NACA CYH Airfoil Section
The NACA CYH airfoil section is described and its aerodynamic characteristics are given as tested in the NACA variable density wind tunnel at twenty atmosphere pressure. This section has a low drag, a high maximum lift, and a small travel of center of pressure
A study of the pitching moments and the stability characteristics of monoplanes
This note presents a study of the pitching moments and the stability characteristics of monoplanes. Expressions for the pitching-moment coefficient and the Diehl stability coefficient for the monoplane are developed, suitable for the use of airplane designers. The effective difference between the high-wing and low-wing types is portrayed and discussed. Comparisons between experimental and computed values are made. Charts for use in the solution of numerical values of the pitching-moment and stability coefficients are presented
Whirl and Stall Flutter Simulation Using CFD
This paper presents recent research on numerical methods for whirl and stall flutter using computational
fluid dynamics. The method involves coupling of the HMB3 CFD solver of the University of
Glasgow and a NASTRAN derived structural model. Based upon a literature survey, a significant amount
of research has been conducted on the numerical investigation of tiltrotors, with a focus on the XV-15
and V-22 aircraft. Within this paper, the coupling procedure is presented along with a steady CFD computation
to highlight the accuracy of the high-fidelity method. In addition to this, a simple method is used
to investigate the whirl flutter boundary of a standard propeller and the XV-15 blade
The Comparison of Well-known and New Wing Sections Tested in the Variable Density Wind Tunnel
Three groups of airfoils have been tested in the variable density wind tunnel. The first group contains three airfoils. The second group is a systematic series of twenty-seven airfoils. The third group consists of several frequently used wing sections
The characteristics of the NACA M-12 airfoil section
The data obtained on the NACA M-12 airfoil, tested at twenty atmosphere density in the NACA variable density wind tunnel, have been extended by additional tests at one and at twenty atmospheres under improved conditions. The results of these tests are given. Considerable scale effect was found
The Characteristics of the N.A.C.A 97, Clark Y, and N.A.C.A. M6 Airfoils with Particular Reference to the Angle of Attack
No abstract availabl
The Effect of the Walls in Closed Type Wind Tunnels
A series of tests has been conducted during the period 1925-1927 by the National Advisory Committee for Aeronautics in the variable-density wind tunnel on several airfoil models of different sizes and sections to determine the effect of tunnel-wall interference and to determine a correction which can be applied to reduce the error caused thereby. The use of several empirical corrections was attempted with little success. The Prandtl theoretical corrections give the best results, and their use is recommended for correcting closed wind tunnel results to the conditions of free air. An appendix is attached wherein the experimentally determined effect of the walls on the tunnel velocity very close to their surface is given. This is of special interest because a "scale effect" was found in the boundary layer with a change in the density of the tunnel air
The prediction of airfoil characteristics
This report describes and develops methods by which the aerodynamic characteristics of an airfoil may be calculated with sufficient accuracy for use in airplane design. These methods for prediction are based on the present aerodynamic theory and on empirical formulas derived from data obtained in the N. A. C. A. variable density wind tunnel at a Reynolds number corresponding approximately to full scale. (author
The effect of tip shields on a horizontal tail surface
A series of experiments made in the wind tunnel of the Daniel Guggenheim School of Aeronautics, New York University, on the effect of tip shields on a horizontal tail surface are described and discussed. It was found that some aerodynamic gain can be obtained by the use of tip shields though it is considered doubtful whether their use would be practical
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