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  Partner: UNT Libraries Government Documents Department
 Decade: 1930-1939
 Collection: National Advisory Committee for Aeronautics Collection
Experiments with an airfoil model on which the boundary layers are controlled without the use of supplementary equipment

Experiments with an airfoil model on which the boundary layers are controlled without the use of supplementary equipment

Date: April 1, 1931
Creator: Abbott, I H
Description: This report describes test made in the Variable Density Wind Tunnel of the NACA to determine the possibility of controlling the boundary layer on the upper surface of an airfoil by use of the low pressure existing near the leading edge. The low pressure was used to induce flow through slots in the upper surface of the wing. The tests showed that the angle of attack for maximum lift was increased at the expense of a reduction in the maximum lift coefficient and an increase in the drag coefficient.
Contributing Partner: UNT Libraries Government Documents Department
Airship model tests in the variable density wind tunnel

Airship model tests in the variable density wind tunnel

Date: January 1, 1932
Creator: Abbott, Ira H
Description: This report presents the results of wind tunnel tests conducted to determine the aerodynamic characteristics of airship models. Eight Goodyear-Zeppelin airship models were tested in the original closed-throat tunnel. After the tunnel was rebuilt with an open throat a new model was tested, and one of the Goodyear-Zeppelin models was retested. The results indicate that much may be done to determine the drag of airships from evaluations of the pressure and skin-frictional drags on models tested at large Reynolds number.
Contributing Partner: UNT Libraries Government Documents Department
The drag of two streamline bodies as affected by protuberances and appendages

The drag of two streamline bodies as affected by protuberances and appendages

Date: January 1, 1934
Creator: Abbott, Ira H
Description: This report presents the results of wind tunnel tests of two airship models conducted to determine the drag coefficients at zero pitch, and the effect of fins and cars and of flat and streamlined protuberances located at various positions along the hull. During the investigation the stern of one model was rounded off to produce a blunter shape. The extreme range of the Reynolds number based on the over-all length of the models was from 1,300,000 to 33,000,000. At large values of the Reynolds number the streamlined protuberance affected the drag very little, and the additional drag caused by the flat protuberance was less than the calculated drag by the protuberance alone. The fins and cars together increased the bare-hull drag about 20 per cent.
Contributing Partner: UNT Libraries Government Documents Department
Flow observations with tufts and lampblack of the stalling of four typical airfoil sections in the NACA variable-density tunnel

Flow observations with tufts and lampblack of the stalling of four typical airfoil sections in the NACA variable-density tunnel

Date: October 1, 1938
Creator: Abbott, Ira H
Description: A preliminary investigation of the stalling processes of four typical airfoil sections was made over the critical range of the Reynolds Number. Motion pictures were taken of the movements of small silk tufts on the airfoil surface as the angle of attack increased through a range of angles including the stall. The boundary-layer flow also at certain angles of attack was indicated by the patterns formed by a suspension of lampblack in oil brushed onto the airfoil surface. These observations were analyzed together with corresponding force-test measurements to derive a picture of the stalling processes of airfoils.
Contributing Partner: UNT Libraries Government Documents Department
Fuselage-drag tests in the variable-density wind tunnel: streamline bodies of revolution, fineness ratio of 5

Fuselage-drag tests in the variable-density wind tunnel: streamline bodies of revolution, fineness ratio of 5

Date: September 1, 1937
Creator: Abbott, Ira H
Description: Results are presented of the drag tests of six bodies of revolution with systematically varying shapes and with a fineness ratio of 5. The forms were derived from source-sink distributions, and formulas are presented for the calculation of the pressure distribution of the forms. The tests were made in the N.A.C.A. variable-density tunnel over a range of values of Reynolds number from about 1,500,000 to 25,000,000. The results show that the bodies with the sharper noses and tails have the lowest drag coefficients, even when the drag coefficients are based on the two-thirds power of the volume. The data shows the most important single characteristic of the body form to be the tail angle, which must be fine to obtain low drag.
Contributing Partner: UNT Libraries Government Documents Department
Tests in the variable-density wind tunnel of the NACA 23012 airfoil with plain and split flaps

Tests in the variable-density wind tunnel of the NACA 23012 airfoil with plain and split flaps

Date: January 1, 1939
Creator: Abbott, Ira H
Description: Section characteristics for use in wing design are presented for the NACA 23012 airfoil with plain and split flaps of 20 percent wing chord at a value of the effective Reynolds number of about 8,000,000. The flap deflections covered a range from 60 degrees upward to 75 degrees downward for the plain flap and from neutral to 90 degrees downward for the split flap. The split flap was aerodynamically superior to the plain flap in producing high maximum lift coefficients and in having lower profile-drag coefficients at high lift coefficients.
Contributing Partner: UNT Libraries Government Documents Department
High-speed wind tunnels

High-speed wind tunnels

Date: November 1, 1936
Creator: Ackeret, J
Description: Wind tunnel construction and design is discussed especially in relation to subsonic and supersonic speeds. Reynolds Numbers and the theory of compressible flows are also taken into consideration in designing new tunnels.
Contributing Partner: UNT Libraries Government Documents Department
The Magnus effect in theory and in reality

The Magnus effect in theory and in reality

Date: May 1, 1930
Creator: Ahlborn, F
Description: A discussion of the Flettner rotor is presented from a nautical and economic viewpoint, and although it was a failure, the experimental and theoretical inventions cannot be disregarded. The following critical and experimental investigation will show the relations and applicability of the theories and practical applications. The Magnus effect is described in detail and a discussion and critical review of the Magnus effect is included.
Contributing Partner: UNT Libraries Government Documents Department
Turbulence and mechanism of resistance on spheres and cylinders

Turbulence and mechanism of resistance on spheres and cylinders

Date: January 1, 1932
Creator: Ahlborn, FR
Description: The nature of turbulent flow through pipes and around obstacles is analyzed and illustrated by photographs of turbulence on screens and straighteners. It is shown that the reversal of flow and of the resistance law on spheres is not explainable by Prandtl's turbulence in the boundary layer. The investigation of the analogous phenomena on the cylinder yields a reversal of the total field of flow. The very pronounced changes in pressure distribution connected with it were affirmed by manometric measurements on spheres by Professor O. Krell. The reversal in a homogenous nonvortical flow is brought about by the advance of the stable arrangement of Karman's dead air vortices toward the test object and by the substitution of an alternatingly one-sided or rotating but stable vortex formation in place of the initially symmetrical formation. This also explains the marked variations of the models.
Contributing Partner: UNT Libraries Government Documents Department
The pack method for compressive tests of thin specimens of materials used in thin-wall structures

The pack method for compressive tests of thin specimens of materials used in thin-wall structures

Date: January 1, 1939
Creator: Aitchison, C S
Description: The strength of modern lightweight thin-wall structures is generally limited by the strength of the compression members. An adequate design of these members requires a knowledge of the compressive stress-strain graph of the thin-wall material. The "pack" method was developed at the National Bureau of Standards with the support of the National Advisory Committee for Aeronautics to make possible a determination of compressive stress-strain graphs for such material. In the pack test an odd number of specimens are assembled into a relatively stable pack, like a "pack of cards." Additional lateral stability is obtained from lateral supports between the external sheet faces of the pack and outside reactions. The tests seems adequate for many problems in structural research.
Contributing Partner: UNT Libraries Government Documents Department
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