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  Partner: UNT Libraries Government Documents Department
 Decade: 1930-1939
 Year: 1933
 Serial/Series Title: NACA Technical Notes
 Collection: Technical Report Archive and Image Library
The aerodynamic characteristics of airfoils as affected by surface roughness

The aerodynamic characteristics of airfoils as affected by surface roughness

Date: April 1, 1933
Creator: HOCKER RAY W
Description: The effect on airfoil characteristics of surface roughness of varying degrees and types at different locations on an airfoil was investigated at high values of the Reynolds number in a variable density wind tunnel. Tests were made on a number of National Advisory Committee for Aeronautics (NACA) 0012 airfoil models on which the nature of the surface was varied from a rough to a very smooth finish. The effect on the airfoil characteristics of varying the location of a rough area in the region of the leading edge was also investigated. Airfoils with surfaces simulating lap joints were also tested. Measurable adverse effects were found to be caused by small irregularities in airfoil surfaces which might ordinarily be overlooked. The flow is sensitive to small irregularities of approximately 0.0002c in depth near the leading edge. The tests made on the surfaces simulating lap joints indicated that such surfaces cause small adverse effects. Additional data from earlier tests of another symmetrical airfoil are also included to indicate the variation of the maximum lift coefficient with the Reynolds number for an airfoil with a polished surface and with a very rough one.
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The aerodynamic effect of a retractable landing gear

The aerodynamic effect of a retractable landing gear

Date: March 1, 1933
Creator: Defrance, Smith J
Description: Tests were conducted in the N.A.C.A. full scale wind tunnel at the request of the Army Air Corps to determine the effect of retractable landing gear openings in the bottom surface of a wing upon the characteristics of a Lockheed Altair airplane. The tests were extended to include the determination of the lift and drag characteristics throughout the angle-of-attack range with the landing gear both retracted and extended. Covering the wheel openings in the wing with sheet metal when the wheels were extended reduced the drag only 2 percent at a lift coefficient of 1.0, which was assumed for the take-off condition. Therefore, the wheel openings in the bottom side of the wing have a negligible effect upon the take-off of the airplane. Retracting the landing gear reduced the minimum drag of the complete airplane 50 percent.
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Aerodynamic tests of a low aspect ratio tapered wing with an auxiliary airfoil for use on tailless airplanes

Aerodynamic tests of a low aspect ratio tapered wing with an auxiliary airfoil for use on tailless airplanes

Date: November 1, 1933
Creator: Sanders, Robert
Description: None
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Aerodynamic tests of a low aspect ratio tapered wing with various flaps, for use on tailless airplanes

Aerodynamic tests of a low aspect ratio tapered wing with various flaps, for use on tailless airplanes

Date: June 1, 1933
Creator: Weick, Fred E
Description: Wind tunnel tests were made of a model wing having an aspect ratio of 3 and a tapered plan form with a straight trailing edge. The model had the Clark Y airfoil section throughout it's entire span and had no washout, depending on a trailing-edge flap for longitudinal balance and control. The flap had a constant chord and was divided into four equal portions along the span. The tests were made with the entire flap deflected to obtain longitudinal control and balance, and also with the inner portions deflected alone, and with the outer portions deflected alone. It was found that the simple wing with no washout or change of basic section along the span has aerodynamic characteristics well suited for use on tailless airplanes. A higher lift coefficient was obtained with the full-span flap deflected as a unit to give longitudinal balance than was obtained with either the inner or the outer portions of the flap deflected.
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Charts for determining the pitching moment of tapered wings with sweepback and twist

Charts for determining the pitching moment of tapered wings with sweepback and twist

Date: December 1, 1933
Creator: Anderson, Raymond F
Description: This report presents a convenient method for calculating the pitching-moment characteristics of tapered wings with sweepback and twist. The method is based on the fact that the pitching-moment characteristics of a wing may be specified by giving the value of the pitching moment at zero lift and the location of the axis about which the axis is constant. Data for calculating these characteristics are presented by curves which apply to wings having a linear distribution of twist along the span and which cover a large range of aspect ratios. The curves are given for wings having straight taper and distorted elliptical plan forms. The characteristics of wings of other shapes may be determined by interpolation.
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Comparison of three methods for calculating the compressive strength of flat and slightly curved sheet and stiffener combinations

Comparison of three methods for calculating the compressive strength of flat and slightly curved sheet and stiffener combinations

Date: March 1, 1933
Creator: Lundquist, Eugene E
Description: This report gives a comparison of the accuracy of the three methods for calculating the compressive strength of flat sheet and stiffener combinations such as occur in stressed-skin or monocoque structures for aircraft. Of the three methods based upon various assumptions with regard to the interaction of sheet and stiffener, the method based upon mutual action of the stiffener and an effective width as a column gave the best agreement with the results of the tests. An investigation of the effect of small curvature resulted in the conclusion that the compressive strength of the curved panels is, for all practical purposes, equal to the strength of flat panels except for thick sheet where non-uniform curvature throughout the length may cause the strength of the curved panel to be 10 to 15 percent less than that of a corresponding flat panel.
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A Complete Tank Test of a Model of a Flying-Boat Hull - N.A.C.A. Model No.11

A Complete Tank Test of a Model of a Flying-Boat Hull - N.A.C.A. Model No.11

Date: July 1, 1933
Creator: Shoemaker, James M.
Description: This note discusses the limitations of the conventional tank test of a seaplane model. The advantages of a complete test, giving the characteristics of the model at all speeds, loads, and trim angles in the useful range are pointed out. The data on N.A.C.A. Model No.11, obtained from a complete test, are presented and discussed. The results are analyzed to determine the best trim angle for each speed and load. The data for the best angles are reduced to non-dimensional form for ease of comparison and application. A practical problem using the characteristics of model no.11 is presented to show the method of calculating the take-off time and run of a seaplane from these data.
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A complete tank test of a model of a flying-boat hull-N.A.C.A. Model No.11

A complete tank test of a model of a flying-boat hull-N.A.C.A. Model No.11

Date: July 1, 1933
Creator: Shoemaker, James M
Description: This note discusses the limitations of the conventional tank test of a seaplane model. The advantages of a complete test, giving the characteristics of the model at all speeds, loads, and trim angles in the useful range are pointed out. The data on N.A.C.A. Model No.11, obtained from a complete test, are presented and discussed. The results are analyzed to determine the best trim angle for each speed and load. The data for the best angles are reduced to non-dimensional form for ease of comparison and application. A practical problem using the characteristics of model no.11 is presented to show the method of calculating the take-off time and run of a seaplane from these data.
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A complete tank test of a model of a flying-boat Hull - N.A.C.A. model no.11-A

A complete tank test of a model of a flying-boat Hull - N.A.C.A. model no.11-A

Date: September 1, 1933
Creator: Parkinson, John B
Description: Model No. 11-A was designed as an improvement over N.A.C.A. Model No. 11, a complete test of which is described in N.A.C.A. Technical Note No. 464. In contrast with the longitudinal upward curvature in the planing bottom forward of the main step on Model 11-A was made as flat as practicable. Otherwise, the two models have very nearly the same form. The results of towing tests made on Model 11-A in the N.A.C.A. tank over a wide range of speed, load on the water, and trim angle are presented, both as original test data and as non dimensional coefficients. A comparison is made with similar results from the test of Model No. 11. The practical significance of the improvement obtained is demonstrated by applying the data from the new form to the illustrative design problem use in the note on Model NO. 11.
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A complete tank test of a model of flying-boat Hull - N.A.C.A. Model 16

A complete tank test of a model of flying-boat Hull - N.A.C.A. Model 16

Date: September 1, 1933
Creator: Shoemaker, James H
Description: A model of a 2-step flying-boat hull, of the type generally used in England, was tested according to the complete method described in the N.A.C.A. Technical Note No. 464. The lines of this model were taken from offsets given by Mr. William Munro in Flight, May 29, 1931. The data cover the range of loads, speeds, and trim angles that may be of use in applying the hull form to the design of any seaplane. The results are reduced to nondimensional form to aid application to design problems and facilitate comparison with the performance of other hulls. The water characteristics of Model 16 are compared with those of Model 11-A, which is representative of current American practice. The results show that when the two forms are applied to a given seaplane design under optimum conditions for each, the performance of Model 16 will be somewhat inferior to that of Model 11-A.
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