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Effect of Periodic Changes of Angle of Attack on Behavior of Airfoils

Description: This report presents the results of a series of experiments, which gave some quantitative results on the effect of periodic changes in the direction of the relative air flow against airfoils. The first series of experiments concerned how the angle of attack of the wing model was changed by causing the latter to oscillate about an axis parallel to the span and at right angles to the air flow. The second series embraced all the experiments in which the direction of the air flow itself was periodically changed.
Date: October 1922
Creator: Katzmayr, R.
Partner: UNT Libraries Government Documents Department

A method for increasing the effectiveness of stabilizing surfaces at high supersonic Mach numbers

Description: Report presenting the use of wedge-shaped airfoil sections to obtain large increases in lift-curve slope at low angles of attack at high supersonic Mach numbers. The use of such sections on the tail surfaces operating at low angles of attack on airplanes or missiles traveling at these speeds can greatly decrease the stabilizing-surface area required.
Date: August 3, 1954
Creator: McLellan, Charles H.
Partner: UNT Libraries Government Documents Department

Airfoil-Contour Modifications Based on (Epsilon)-Curve Method of Calculating Pressure Distribution

Description: From Introduction: "Certain alternations of a qualitative nature may be performed in spite of the fact that a pressure change cannot be prescribed. It is the purpose of this paper to indicate a method by which qualitative alternation may be performed. It will be noted that the present method of contour modification will serve the intended purpose of the inverse method."
Date: July 1944
Creator: Theodorsen, Theodore
Partner: UNT Libraries Government Documents Department

Profile-Drag Coefficients of Conventional and Low-Drag Airfoils as Obtained in Flight

Description: "The results of flight investigations of the profile drag of several carefully finished conventional and low-drag airfoils are presented. The results indicated that in all cases lower profile-drag coefficients were obtained with the low-drag than with the conventional airfoils over the range of lift coefficient tested and that, for comparable conditions of lift coefficient and Reynolds number, the low-drag airfoils may have profile-drag coefficients which are at least 27 percent lower than the profile-drag coefficients of the conventional airfoils" (p.1).
Date: May 1944
Creator: Zalovcik, John A.
Partner: UNT Libraries Government Documents Department

Aerodynamic Characteristics of Airfoils 5: Continuation of Reports Nos. 93, 124, 182, and 244

Description: "This collection of data on airfoils has been made from published reports of a number of the leading aerodynamic laboratories of this country and Europe. The information which was originally expressed according to the different customs of the several laboratories is here presented in a uniform series of charts and tables suitable for the use of designing engineers and for purposes of general reference. The authority for the results here presented is given as the name of the laboratory at which the experiments were conducted, with the size of the model, wind velocity, and year of tests" (p. 139).
Date: April 1928
Partner: UNT Libraries Government Documents Department

Aerodynamic Characteristics of Airfoils 3: Continuation of Reports Nos. 93 and 124

Description: "This collection of data on airfoils has been made from the published reports of a number of the leading aerodynamic laboratories of this country and Europe. The information which was originally expressed according to the different customs of the several laboratories is here presented in a uniform series of charts and tables suitable for the use of designing engineers and for purposes of general reference. The absolute system of coefficients has been used, since it is thought by the National Advisory Committee for Aeronautics that this is the one most suited for international use and yet is one for which a desired transformation can be easily made" (p. 397).
Date: 1924~
Partner: UNT Libraries Government Documents Department

Aerodynamic Characteristics of Airfoils 4: Continuation of Reports Nos. 93, 124, and 182

Description: This collection of data on airfoils has been made from the published reports of a number of the leading Aerodynamic Laboratories of this country and Europe. The information which was originally expressed according to the different customs of the several laboratories is here presented in a uniform series of charts and tables suitable for the use of designing engineers and for purposes of general reference. The authority for the results here presented is given as the name of the laboratory at which the experiments were conducted, with the size of the model, wind velocity, and year of test.
Date: September 1926
Partner: UNT Libraries Government Documents Department

Aerodynamic Characteristics of Airfoils 6: Continuation of Reports Nos. 93, 124, 182, 244, and 286

Description: "This collection of data on airfoils has been made from the published reports of a number of the leading aerodynamic laboratories of this country and Europe. The information which was originally expressed according to the different customs of the several laboratories is here presented in a uniform series of charts and tables suitable for use of designing engineers and for purposes of general reference. The authority for the results here presented is given as the name of the laboratory at which the experiments were conducted, with the size of the model, wind velocity, and year of test" (p. 213).
Date: 1930~
Partner: UNT Libraries Government Documents Department

General Airfoil Theory

Description: "On the assumption of infinitely small disturbances the author develops a generalized integral equation of airfoil theory which is applicable to any motion and compressible fluid. Successive specializations yield various simpler integral equations, such as Possio's, Birnbaum's, and Prandtl's integral equations, as well as new ones for the wing of infinite span with periodic downwash distribution and for the oscillating wing with high aspect ratio. Lastly, several solutions and methods for solving these integral equations are give" (p. 1).
Date: June 1941
Creator: K├╝ssner, H. G.
Partner: UNT Libraries Government Documents Department

Vorticism in Aeronautics

Description: Since the war there has been a considerable advance in knowledge on the subject of the airfoil and its behavior. The theory is now sufficiently advanced to make it possible to predict and to calculate certain results which previously could only be attained by direct experiment. The vortex theory receives special attention.
Date: August 1923
Creator: Sayers, W. H.
Partner: UNT Libraries Government Documents Department

Notes on the Effect of Surface Distortions on the Drag and Critical Mach Number of Airfoils

Description: "The effect of two-dimensional bumps and surface waviness on the pressure distribution over airfoils is considered. It is shown that the results of the analysis may be useful in evaluating the effects of accidental or intended surface distortions on the drag and critical Mach number of airfoils" (p. 1).
Date: September 1943
Creator: Allen, H. Julian
Partner: UNT Libraries Government Documents Department

Absolute Coefficients and the Graphical Representation of Airfoil Characteristics

Description: It is argued that there should be an agreement as to what conventions to use in determining absolute coefficients used in aeronautics and in how to plot those coefficients. Of particular importance are the absolute coefficients of lift and drag. The author argues for the use of the German method over the kind in common use in the United States and England, and for the Continental over the usual American and British method of graphically representing the characteristics of an airfoil.
Date: June 1921
Creator: Munk, Max
Partner: UNT Libraries Government Documents Department

The Effectiveness at High Speeds of a 20-Percent-Chord Plain Trailing-Edge Flap on the NACA 65-210 Airfoil

Description: "An analysis has been made of the lift control effectiveness of a 20-percent-chord plain trailing-edge flap on the NACA 65-210 airfoil section from section lift-coefficient data obtained at Mach numbers from 0.3 to 0.875. In addition, the effectiveness of the plain flap as a lift-control device has been compared with the corresponding effectiveness of both a spoiler and a dive-recovery flap on the NACA 65-210 airfoil section. The analysis indicates that the plain trailing-edge flap employed on the 10-percent-thick airfoil at Mach numbers as high as 0.875 retains at least 50-percent of its low-speed lift-control effectiveness, and is sufficiently effective in lateral control application, assuming a rigid wing, to provide adequate airplane rolling characteristics" (p. 1).
Date: May 6, 1947
Creator: Stivers, Louis S., Jr.
Partner: UNT Libraries Government Documents Department

The effects of shielding the tips of airfoils

Description: "Tests have recently been made at Langley Memorial Aeronautical Laboratory to ascertain whether the aerodynamic characteristics of an airfoil might be substantially improved by imposing certain limitations upon the air flow about its tips. All of the modified forms were slightly inferior to the plain airfoil at small lift coefficients: however, by mounting thin plates, in planes perpendicular to the span, at the wing tips, the characteristics were improved throughout the range above three-tenths of the maximum lift coefficient. With this form of limitation the detrimental effect was slight; at the higher lift coefficients there resulted a considerable reduction of induced drag and consequently, of power required for sustentation. The slope of the curve of lift versus angle of attack was increased" (p. 347).
Date: 1925
Creator: Reid, Elliott G.
Partner: UNT Libraries Government Documents Department

Airfoil lift with changing angle of attack

Description: From Summary: "Tests have been made in the atmospheric wind tunnel of the National Advisory Committee for Aeronautics to determine the effects of pitching oscillations upon the lift of an airfoil. It has been found that the lift of an airfoil, while pitching, is usually less than that which would exist at the same angle of attack in the stationary condition, although exceptions may occur when the lift is small or if the angle of attack is being rapidly reduced. It is also shown that the behavior of a pitching airfoil may be qualitatively explained on the basis of accepted aerodynamic theory."
Date: September 1927
Creator: Reid, Elliott G.
Partner: UNT Libraries Government Documents Department

Aerodynamic characteristics of NACA 0012 airfoil section at angles of attack from 0 degrees to 180 degrees

Description: Report presenting the aerodynamic characteristics of the NACA 0012 airfoil section at a range of angles of attack from 0 to 180 degrees. Data were obtained at two different Reynolds numbers depending on whether the airfoil surfaces were smooth or had roughness applied at the leading and trailing edges. After the stall with the rounded edge of the airfoil foremost, a second lift-coefficient peak was obtained at an angle of attack of about 45 degrees.
Date: January 1955
Creator: Critzos, Chris C.; Heyson, Harry H. & Boswinkle, Robert W., Jr.
Partner: UNT Libraries Government Documents Department

Aerodynamic Characteristics at High and Low Subsonic Mach Numbers of the NACA 0012, 64(sub 2)-015, and 64(sub 3)-018 Airfoil Sections at Angles of Attack from -2 Degrees to 30 Degrees

Description: An investigation has been made in the Langley low-turbulence pressure tunnel of the aerodynamic characteristics of the NACA 0012, 64(sub 2)-015, and 64(sub 3)-018 airfoil sections. Data were obtained at Mach numbers from 0.3 to that for tunnel choke, at angles of attack from -2deg to 30deg, and with the surface. of each airfoil smooth-and with roughness applied at the leading edge.The Reynolds numbers of the tests ranged from 0.8 x 10(exp 6) to 4.4 x 10(exp 6). The results are presented as variations of lift, drag, and quarter-chord pitching-moment coefficients with Mach number.
Date: July 23, 1954
Creator: Critzos, Chris C.
Partner: UNT Libraries Government Documents Department

Air forces on airfoils moving faster than sound

Description: We are undertaking the task of computing the air forces on a slightly cambered airfoil in the absence of friction and with an infinite aspect ratio. We also assume in advance that the leading edge is very sharp and that its tangent lies in the direction of motion.
Date: June 1925
Creator: Ackeret, J.
Partner: UNT Libraries Government Documents Department

Experimental investigation of lift, drag, and pitching moment of five annular airfoils

Description: From Summary: "An investigation was carried out in the Langley stability tunnel to determine the lift, drag, and pitching-moment characteristics of a family of annular airfoils. The five annular airfoils had equal projected areas but had varying chords and diameters which covered aspect ratios of 1/3, 2/3, 1.0, 1.5, and 3.0. The results showed that the effects of aspect ratio on the aerodynamic-center location were similar for annular and unswept airfoils and that annular airfoils had larger maximum lift-drag ratios below an aspect ratio of 2.4 than did plane rectangular airfoils with faired tips."
Date: October 1957
Creator: Fletcher, Herman S.
Partner: UNT Libraries Government Documents Department

Effects of leading-edge radius and maximum thickness-chord ratio on the variation with Mach number of the aerodynamic characteristics of several thin NACA airfoil sections

Description: Report presenting a wind-tunnel investigation to determine the effects of leading-edge radius and maximum thickness-chord ratio on the variation with Mach number of the aerodynamic characteristics of several thin symmetrical NACA 4-digit-series airfoil sections. The variations with Mach number of the lift, drag, and pitching moment for a 4-percent-chord-thick airfoil section are not significantly affected by a change of leading-edge radius from 0.18 to 0.53 percent of the chord. Results regarding the leading-edge radius effects and maximum thickness-chord ratio are provided.
Date: July 3, 1950
Creator: Berggren, Robert E. & Graham, Donald J.
Partner: UNT Libraries Government Documents Department

Effects of leading-edge radius and maximum thickness-chord ratio on the variation with Mach number of the aerodynamic characteristics of several thin NACA airfoil sections

Description: Report presenting a wind-tunnel investigation to determine the effects of leading-edge radius and maximum thickness-chord ratio on the variation with Mach number of the aerodynamic characteristics of several thin symmetrical NACA 4-digit-series airfoil sections. The variations with Mach number of the lift, drag, and pitching moment for a 4-percent-chord-thick airfoil section are not significantly affected by a change of leading-edge radius from 0.18 to 0.53 percent of the chord.
Date: April 14, 1954
Creator: Berggren, Robert E. & Graham, Donald J.
Partner: UNT Libraries Government Documents Department

Effects of systematic changes of trailing-edge angle and leading-edge radius on the variation with Mach number of the aerodynamic characteristics of a 10-percent-chord-thick NACA airfoil section

Description: Report presenting the results of a wind-tunnel investigation of the effects of variation of trailing-edge angle and leading-edge radius on the aerodynamic characteristics of a 10-percent-chord-thick airfoil section at a range of Mach numbers.
Date: September 26, 1949
Creator: Summers, James L. & Graham, Donald J.
Partner: UNT Libraries Government Documents Department

Compilation of information on the transonic attachment of flows at the leading edges of airfoils

Description: Schlieren photographs have been compiled of the two-dimensional flow at transonic speeds past 37 airfoils. These airfoils have variously shaped profiles, and some are related in thickness and camber. The data for these airfoils were analyzed to provide basic information on the flow changes involved and to determine factors affecting transonic-flow attachment, which is a transition from separated to unseparated flow at the leading edges of two-dimensional airfoils at fixed angles as the subsonic Mach number is increased.
Date: February 1958
Creator: Lindsey, Walter F. & Landrum, Emma Jean
Partner: UNT Libraries Government Documents Department