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Aerodynamic characteristics of NACA 23012 and 23021 airfoils with 20-percent-chord external-airfoil flaps of NACA 23012 section

Description: Report presents the results of an investigation of the general aerodynamic characteristics of the NACA 23012 and 23021 airfoils, each equipped with a 0.20c external flap of NACA 23012 section. The tests were made in the NACA 7 by 10-foot and variable-density wind tunnels and covered a range of Reynolds numbers that included values corresponding to those for landing conditions of a wide range of airplanes. Besides a determination of the variation of lift and drag characteristics with position of the flap relative to the main airfoil, complete aerodynamic characteristics of the airfoil-flap combination with a flap hinge axis selected to give small hinge moments were measured in the two tunnels. Some measurements of air loads on the flap itself in the presence of the wing were made in the 7 by 10-foot wind tunnel.
Date: 1937~
Creator: Platt, Robert C & Abbott, Ira H

The aerodynamic characteristics of six full-scale propellers having different airfoil sections

Description: Wind-tunnel tests are reported of six 3-blade 10-foot propellers operated in front of a liquid-cooled engine nacelle. The propellers were identical except for blade airfoil sections, which were: Clark y, R.A.F. 6, NACA 4400, NACA 2400-34, NACA 2rsub200, and NACA 6400. The range of blade angles investigated extended for 15 degrees to 40 degrees for all propellers except the Clark y, for which it extended to 45 degrees. The results showed that the range in maximum efficiency between the highest and lowest values was about 3 percent. The highest efficiencies were for the low-camber sections.
Date: 1939
Creator: Biermann, David & Hartman, Edwin P

Aerodynamic characteristics of twenty-four airfoils at high speeds

Description: The aerodynamic characteristics of 24 airfoils are given for speeds of 0.5, 0.65, 0.8, 0.95, and 1.08 times the speed of sound, as measured in an open-jet air stream 2 inches in diameter, using models of 1-inch chord. The 24 airfoils belong to four general groups. The first is the standard R. A. F. family in general use by the Army and Navy for propeller design, the members of the family differing only in thickness. This family is represented by nine members ranging in thickness from 0.04 to 0.20 inch. The second group consists of five members of the Clark Y family, the members of the family again differing only in thickness. The third group, comprising six members, is a second R. A. F. Family in which the position of the maximum ordinate is varied. Combined with two members of the first R.A.F. family, this group represents a variation of maximum ordinate position from 30 to 60 percent of the chord in two camber ratios, 0.08 and 0.16. The fourth group consists of three geometrical forms, a flat plate, a wedge, and a segment of a right circular cylinder. In addition one section used in the reed metal propeller was included. These measurements form a part of a general program outlined at a Conference on Propeller Research organized by the National Advisory Committee for Aeronautics and the work was carried out with the financial assistance of the committee (author).
Date: 1930~
Creator: Brigg, L. J. & Dryden, H. L.

Aerodynamic characteristics of wings with cambered external airfoil flaps, including lateral control, with a full-span flap

Description: The results of a wind-tunnel investigation of the NACA 23012, the NACA 23021, and the Clark Y airfoils, each equipped with a cambered external-airfoil flap, are presented in this report. The purpose of the research was to determine the relative merit of the various airfoils in combination with the cambered flap and to investigate the use of the flap as a combined lateral-control and high-lift device.
Date: 1935
Creator: Platt, Robert C

The aerodynamic effects of wing cut-outs

Description: In connection with the interference program being conducted in the NACA variable-density wind tunnel, an analysis was made of available material with the object of presenting a qualitative discussion on wing characteristics as affected by cut-outs and of determining means for their quantitative calculation.
Date: 1934
Creator: Sherman, Albert

The aerodynamic forces and moments exerted on a spinning model of the NY-1 airplane as measured by the spinning balance

Description: A preliminary investigation of the effects of changes in the elevator and rudder settings and of small changes in attitude upon the aerodynamic forces and moments exerted upon a spinning airplane was undertaken with the spinning balance in the 5-foot vertical tunnel of the National Advisory Committee for Aeronautics. The tests were made on a 1/12-scale model of the ny-1 airplane. Data by which to fix the attitude, the radius of spin, and the rotational and air velocities were taken from recorded spins of the full-scale airplane. Two spinning conditions were investigated. All six components of the aerodynamic reaction were measured and are presented in coefficient form refereed to airplane axes. The results indicate that the change in yawing moment produced by the rudder with the elevator up was the only component of force or moment produced by the elevator and rudder that could not have been balanced in an actual spin by small changes in attitude and angular velocity.
Date: February 7, 1933
Creator: Bamber, M J & Zimmerm, N, C h

Air conditions close to the ground and the effect on airplane landings

Description: This report presents the results of an investigation undertaken to determine the feasibility of making glide landings in gusty air. Wind velocities were measured at several stations between the ground and a height of 51 feet, and flight tests were made to determine the actual influence of gusts on an airplane gliding close to the ground.
Date: April 3, 1934
Creator: Thompson, F L; Peck, W C & Beard, A P

Air flow around finned cylinders

Description: Report presents the results of a study made to determine the air-flow characteristics around finned cylinders. Air-flow distribution is given for a smooth cylinder, for a finned cylinder having several fin spacings and fin widths, and for a cylinder with several types of baffle with various entrance and exit shapes. The results of these tests show: that flow characteristics around a cylinder are not so critical to changes in fin width as they are to fin spacing; that the entrance of the baffle has a marked influence on its efficiency; that properly designed baffles increase the air flow over the rear of the cylinder; and that these tests check those of heat-transfer tests in the choice of the best baffle.
Date: November 7, 1935
Creator: Brevoort, M J & Rollin, Vern G

Air flow in a separating laminar boundary layer

Description: The speed distribution in a laminar boundary layer on the surface of an elliptic cylinder, of major and minor axes 11.78 and 3.98 inches, respectively, has been determined by means of a hot-wire anemometer. The direction of the impinging air stream was parallel to the major axis. Special attention was given to the region of separation and to the exact location of the point of separation. An approximate method, developed by K. Pohlhausen for computing the speed distribution, the thickness of the layer, and the point of separation, is described in detail; and speed-distribution curves calculated by this method are presented for comparison with experiment.
Date: December 1, 1934
Creator: Schubauer, G. B.

Air flow in the boundary layer near a plate

Description: The published data on the distribution of speed near a thin flat plate with sharp leading edge placed parallel to the flow (skin friction plate) are reviewed and the results of some additional measurements are described. The purpose of the experiments was to study the basic phenomena of boundary-layer flow under simple conditions.
Date: March 1936
Creator: Dryden, Hugh L.

Air flow in the boundary layer of an elliptic cylinder

Description: The boundary layer of an elliptic cylinder of major and minor axis 11.78 and 3.98 inches, respectively, was investigated in air stream in which the turbulence could be varied. Conditions were arranged so that the flow was two-dimensional with the major axis of the ellipse parallel to the undisturbed stream. Speed distributions across the boundary layer were determined with a hot-wire anemometer at a number of positions about the surface for the lowest and highest intensities of turbulence, with the air speed in both cases sufficiently high to produce a turbulent boundary layer over the downstream part of the surface. The magnitude and the frequency of the speed fluctuations in the boundary layer were also measured by the use of the conventional type of hot-wire turbulence apparatus. Stream turbulence was found to affect both the nature of transition from laminar to turbulent flow in the layer and the position on the surface at which transition occurred. Transition was then investigated in detail with stream turbulence of several different scales and intensities.
Date: August 6, 1938
Creator: Schubauer, G B

Air propellers in yaw

Description: Report presents the results of tests conducted at Stanford University of a 3-foot model propeller at four pitch settings and at 0 degree, 10 degrees, 20 degrees, and 30 degrees yaw. In addition to the usual propeller coefficients, cross-wind and vertical forces and yawing, pitching, and rolling moments were determined about axes having their origin at the intersection of the blade axis and the axis of rotation. The tests showed that the maximum efficiency was reduced only slightly for angles of yaw up to 10 degrees but that at 30 degrees yaw the loss in efficiency was about 10 percent. In all cases the cross-wind force was found to be greater than the cross-wind component of the axial thrust. With a yawed propeller an appreciable thrust was found for v/nd for zero thrust at zero yaw. Yawing a propeller was found to induce a pitching moment that increased in magnitude with yaw.
Date: January 1, 1937
Creator: Lesley, E P; Worley, George F & Moy, Stanley

Aircraft accidents : method of analysis

Description: The revised report includes the chart for the analysis of aircraft accidents, combining consideration of the immediate causes, underlying causes, and results of accidents, as prepared by the special committee, with a number of the definitions clarified. A brief statement of the organization and work of the special committee and of the Committee on Aircraft Accidents; and statistical tables giving a comparison of the types of accidents and causes of accidents in the military services on the one hand and in civil aviation on the other, together with explanations of some of the important differences noted in these tables.
Date: January 1, 1931

Aircraft compass characteristics

Description: A description of the test methods used at the National Bureau of Standards for determining the characteristics of aircraft compasses is given. The methods described are particularly applicable to compasses in which mineral oil is used as the damping liquid. Data on the viscosity and density of certain mineral oils used in United States Navy aircraft compasses are presented. Characteristics of Navy aircraft compasses IV to IX and some other compasses are shown for the range of temperatures experienced in flight. Results of flight tests are presented. These results indicate that the characteristic most desired in a steering compass is a short period and, in a check compass, a low overswing.
Date: January 1, 1937
Creator: Peterson, John B. & Smith, Clyde W.

Aircraft power-plant instruments

Description: This report supersedes NACA-TR-129 which is now obsolete. Aircraft power-plant instruments include tachometers, engine thermometers, pressure gages, fuel-quantity gages, fuel flow meters and indicators, and manifold pressure gages. The report includes a description of the commonly used types and some others, the underlying principle utilized in the design, and some design data. The inherent errors of the instrument, the methods of making laboratory tests, descriptions of the test apparatus, and data in considerable detail in the performance of commonly used instruments are presented. Standard instruments and, in cases where it appears to be of interest, those used as secondary standards are described. A bibliography of important articles is included.
Date: January 1, 1934
Creator: Sontag, Harcourt & Brombacher, W. G.

Aircraft rate-of-climb indicators

Description: The theory of the rate-of-climb indicator is developed in a form adapted for application to the instrument in its present-day form. Compensations for altitude, temperature, and rate of change of temperature are discussed from the designer's standpoint on the basis of this theory. Certain dynamic effects, including instrument lag, and the use of the rate-of-climb indicator as a statoscope are also considered. Modern instruments are described. A laboratory test procedure is outlined and test results are given.
Date: January 1, 1939
Creator: Johnson, Daniel P.

Aircraft speed instruments

Description: This report presents a concise survey of the measurement of air speed and ground speed on board aircraft. Special attention is paid to the pitot-static air-speed meter which is the standard in the United States for airplanes. Air-speed meters of the rotating vane type are also discussed in considerable detail on account of their value as flight test instruments and as service instruments for airships. Methods of ground-speed measurement are treated briefly, with reference to the more important instruments. A bibliography on air-speed measurement concludes the report.
Date: January 1, 1933
Creator: Beij, K Hilding

Aircraft woods: their properties, selection, and characteristics

Description: Strength values of various woods for aircraft design for a 15 per cent moisture condition of material and a 3-second duration of stress are presented, and also a discussion of the various factors affecting the values. The toughness-test method of selecting wood is discussed, and a table of acceptance values for several species is given.
Date: January 1, 1931
Creator: Markwardt, L J

Airfoil pressure distribution investigation in the variable density wind tunnel

Description: Report presents the results of wind tunnel tests of pressure distribution measurements over one section each of six airfoils. Pressure distribution diagrams, as well as the integrated characteristics of the airfoils, are given for both a high and a low dynamic scale or, Reynolds number VL/V, for comparison with flight and other wind-tunnel tests, respectively. It is concluded that the scale effect is very important only at angles of attack near the burble. The distribution of pressure over an airfoil having a Joukowski section is compared with the theoretically derived distribution. A further study of the distribution of pressure over all of the airfoils resulted in the development of an approximate method of predicting the pressure distribution along the chord of any normal airfoil for all attitudes within the working range if the distribution at one attitude is known.
Date: January 1, 1931
Creator: Jacobs, Eastman N.; Stack, John & Pinkerton, Robert M

Airfoil section characteristics as affected by protuberances

Description: The drag and interference caused by protuberance from the surface of an airfoil have been determined in the NACA variable-density wind tunnel at a Reynolds number approximately 3,100,000. The effects of variations of the fore-and-aft position, height, and shape of the protuberance were measured by determining how the airfoil section characteristics were affected by the addition of the various protuberances extending along the entire span of the airfoil. The results provide fundamental data on which to base the prediction of the effects of actual short-span protuberances. The data may also be applied to the design of air brakes and spoilers.
Date: July 11, 1932
Creator: Jacobs, Eastman N.

Airfoil section characteristics as affected by variations of the Reynolds number

Description: Report presents the results of an investigation of a systematically chosen representative group of related airfoils conducted in the NACA variable-density wind tunnel over a wide range of Reynolds number extending well into the flight range. The tests were made to provide information from which the variations of airfoil section characteristics with changes in the Reynolds number could be inferred and methods of allowing for these variations in practice could be determined. This work is one phase of an extensive and general airfoil investigation being conducted in the variable-density tunnel and extends the previously published researches concerning airfoil characteristics as affected by variations in airfoil profile determined at a single value of the Reynolds number.
Date: 1939
Creator: Jacobs, Eastman N. & Sherman, Albert

Airfoil section characteristics as applied to the prediction of air forces and their distribution on wings

Description: The results of previous reports dealing with airfoil section characteristics and span load distribution data are coordinated into a method for determining the air forces and their distribution on airplane wings. Formulas are given from which the resultant force distribution may be combined to find the wing aerodynamic center and pitching moment. The force distribution may also be resolved to determine the distribution of chord and beam components. The forces are resolved in such a manner that it is unnecessary to take the induced drag into account. An illustration of the method is given for a monoplane and a biplane for the conditions of steady flight and a sharp-edge gust. The force determination is completed by outlining a procedure for finding the distribution of load along the chord of airfoil sections.
Date: 1938
Creator: Jacobs, Eastman N. & Rhode, R. V.

Airfoil section data obtained in the NACA variable-density tunnel as affected by support interference and other corrections

Description: The results of an investigation of the effect of support interference on airfoil drag data obtained in the variable-density tunnel are presented. As a result of the support interference, previously published airfoil data from the variable-density tunnel have shown too large drag coefficients and too large a rate of increase of drag coefficients and too large a rate increase of drag coefficients with airfoil thickness. The practical effect of the corrections on the choice of the optimum section is briefly considered and corrected data for a selected list of airfoils are presented as a convenience to the designer. Methods of correcting published data for other airfoils are presented.
Date: 1939
Creator: Jacobs, Eastman N. & Abbott, Ira H.