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  Partner: UNT Libraries Government Documents Department
 Decade: 1930-1939
 Serial/Series Title: NACA Technical Notes
 Collection: Technical Report Archive and Image Library
Local instability of columns with I-, Z-, channel, and rectangular-tube sections

Local instability of columns with I-, Z-, channel, and rectangular-tube sections

Date: December 1, 1939
Creator: Stowell, Elbridge Z & Lundquist, Eugene E
Description: Charts are presented for the coefficients in the formulas for the critical compressive stress at which cross-sectional distortion begins in thin-wall columns of I-, Z-, channel, and rectangular-tube sections. The energy method of Timoshenko was used in the theoretical calculations required for the construction of the charts. The deflection equations were carefully selected to give good accuracy. The calculation of the critical compressive stress at stresses above the elastic range is briefly discussed in order to demonstrate the use of the formulas and the charts in engineering calculations. Two illustrative problems are included.
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Observations in flight of the region of stalled flow over the blades of an autogiro rotor

Observations in flight of the region of stalled flow over the blades of an autogiro rotor

Date: December 1, 1939
Creator: Bailey, F J , Jr & Gustafon, F B
Description: The flow over the inner halves of the rotor blades on a Kellet YG-1B autogiro was investigated in flight by making camera records of the motion of silk streamers attached to the upper surfaces of the blades. These records were analyzed to determine the boundaries of the region within which the flow over the blade sections was stalled for various tip-speed ratios. For the sake of comparison, corresponding theoretical boundaries were obtained. Both the size of the stalled area and its rate of growth with increasing tip-speed ratio were found to be larger than the theory predicted, although experiment agreed with theory with regard to shape and general location of the stalled area. The stalled region may be an important factor in both the rotor lift-drag ratio and the blade flapping motion at the higher tip-speed ratios. The method of study used in this paper should be useful in further studies of the problem, including the reduction of the size of the region.
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Pressure-distribution measurements on a rectangular wing with a partial-span split flap in curved flight

Pressure-distribution measurements on a rectangular wing with a partial-span split flap in curved flight

Date: December 1, 1939
Creator: Rokus, Frank G
Description: Pressure-distribution tests were made on the 32-foot whirling arm of the Daniel Guggenheim Airship Institute of a rectangular wing of NACA 23012 section to determine the rolling and the yawing moment due to angular velocity in yaw. The model was tested at 0 and 5 degree pitch; 0, +/- 5, and +/- 10 degrees yaw; and with no flap and with split flaps 25, 50 and 75 percent of the wing span and deflected 60 degrees. The results are given in the form of span load distributions and as calculated moment coefficients. The experimental values of rolling- and yawing-moment coefficients were in fairly close agreement with theory.
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A recurrence formula for shear-lag problems

A recurrence formula for shear-lag problems

Date: December 1, 1939
Creator: Kuhn, Paul
Description: The analysis of the bending action in box beams with appreciable shear deformation of the flanges becomes very difficult in the general case of variable cross section and loading. This paper presents a convenient method of solving the problem by the familiar method of dividing the beam into a number of bays that can be assumed to have constant cross section and loading. Application of formerly derived shear-lag formulas leads to a general equation closely analogous in form to the well-known three-moment equation. A numerical example and two comparisons between calculation and experimental results are included.
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Stress concentration around an open circular hole in a plate subjected to bending normal to the plane of the plate

Stress concentration around an open circular hole in a plate subjected to bending normal to the plane of the plate

Date: December 1, 1939
Creator: Dumont, C
Description: An aluminum-alloy plate containing an open circular hole of diameter large compared with the thickness of the plate was subjected to bending forces normal to the plane of the plate. Deflection and strain measurements were taken for two different loads. Stress concentrations occurred at the edge of the hole and the maximum stresses were tangential to the hole at the ends of the transverse diameter. The maximum stress at the edge of the hole was 1.59 times the computed stress on the net section and 1.85 times the computed stress in a solid plate of the same dimensions subjected to the same bending forces. The maximum deflections were about 20 percent greater than the corresponding deflection for a solid plate of the same size subjected to the same bending forces. The smallest edge distance was equal to 2-1/2 times the diameter of the hole and the stress concentration on this side of the hole was the same as on the side where the edge distance was about 4-1/2 diameters. A theoretical analysis of the problem shows that, for an aluminum plate of infinite width, the stress concentration at the edge of the hole would be 1.87 times the stress in ...
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Corrugated metal diaphragms for aircraft pressure-measuring instruments

Corrugated metal diaphragms for aircraft pressure-measuring instruments

Date: November 1, 1939
Creator: Goerke, V H & Wildhack, W A
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Photoelastic analysis of three-dimensional stress systems using scattered light

Photoelastic analysis of three-dimensional stress systems using scattered light

Date: November 1, 1939
Creator: Weller, R & Bussey, J K
Description: A method has been developed for making photoelastic analyses of three-dimensional stress systems by utilizing the polarization phenomena associated with the scattering of light. By this method, the maximum shear and the directions of the three principal stresses at any point within a model can be determined, and the two principal stresses at a free-bounding surface can be separately evaluated. Polarized light is projected into the model through a slit so that it illuminates a plane section. The light is continuously analyzed along its path by scattering and the state of stress in the illuminated section is obtained. By means of a series of such sections, the entire stress field may be explored. The method was used to analyze the stress system of a simple beam in bending. The results were found to be in good agreement with those expected from elementary theory.
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Pressure-distribution investigation of an N.A.C.A. 0009 airfoil with a 50-percent-chord plain flap and three tabs

Pressure-distribution investigation of an N.A.C.A. 0009 airfoil with a 50-percent-chord plain flap and three tabs

Date: November 1, 1939
Creator: Street, William G & Ames, Milton B
Description: Pressure-distribution tests of an N.A.C.A. 0009 airfoil with a 50-percent-chord plain flap and three plain tabs, having chords 10, 20, and 30 percent of the flap chord, were made in the N.A.C.A. 4- by 6- foot vertical tunnel. The tests supplied aerodynamic section data that may be applied to the design of horizontal and vertical tail surfaces. The results are presented as resultant-pressure diagrams for the airfoil with the flap and the 20-percent-chord tab. Plots are also given of increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs. The experimental results and values computed by analytical methods are in good agreement for small flap and tab deflections. The results of the tests indicated that the effectiveness of all three tab sizes in reducing flap hinge moments decreased with increasing flap deflection.
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Pressure-distribution measurements on a tapered wing with a partial-span split flap in curved flight

Pressure-distribution measurements on a tapered wing with a partial-span split flap in curved flight

Date: November 1, 1939
Creator: Troller, TH & Rokus, F
Description: Pressure-distribution tests were made on the 32-foot whirling arm of the Daniel Guggenheim Airship Institute of a tapered wing to determine the rolling and the yawing moments due to an angular velocity in yaw. The model was tested at 0 degree and 5 degree pitch; 0 degree, 5 degree, and 10 degree yaw; and with split flaps covering 25, 50, 75, and 100 percent of the wing span and deflected 60 degrees. The results are given in the form of load distributions and as calculated moment coefficients. The experimental values of rolling- and yawing- moment coefficients were in fairly close agreement with theory.
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Tidewater and weather-exposure tests on metals used in aircraft

Tidewater and weather-exposure tests on metals used in aircraft

Date: November 1, 1939
Creator: Mutchler, Willard & Galvin, W G
Description: Tidewater and weather-exposure tests on various aluminum alloys, magnesium alloys, and stainless steels are now being conducted by the National Bureau of Standards. Exposures were begun in June 1938 and, according to present plans, are to continue over a 3-year period. The methods of exposure and the materials being investigated are described and the more important results obtained up to the conclusion of the first year's exposure are reported.
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Experimental study of torsional column failure

Experimental study of torsional column failure

Date: October 1, 1939
Creator: Nile, Alfred S
Description: Thirty-three 24ST aluminum-alloy 2- by 2- by 0.10-inch channels, with lengths ranging from 10 to 90 inches were tested at Stanford University in compression to obtain an experimental verification of the theoretical formulas for torsional failure developed by Eugene E. Lundquist of the N.A.C.A. The observed critical loads and twist-axis locations were sufficiently close to the values obtained from the formulas to establish the substantial validity of the latter. The differences between observed and computed results were small enough to be accounted for by small and mostly unavoidable differences between actual test conditions and those assumed in deriving the formulas. Some data were obtained from the shorter specimens regarding the growth of the buckles that resulted in local buckling failure.
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Tests in the gust tunnel of a model of the XBM-1 airplane

Tests in the gust tunnel of a model of the XBM-1 airplane

Date: October 1, 1939
Creator: Donely, Philip & Shufflebarger, C C
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Combined beam-column stresses of aluminum-alloy channel sections

Combined beam-column stresses of aluminum-alloy channel sections

Date: September 1, 1939
Creator: Gottlieb, R; Thompson, T M & Witt, E C
Description: The results of a research program to obtain design data on the strength of open-channel aluminum-alloy sections subjected to combined column and beam action. The results of the tests of about 70 specimens were graphed for stresses due to axial load and stresses due to bending loading as functions of length to radius of gyration of the specimens. From these graphs a design chart was derived that is suitable for ready use.
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A flight investigation of the distribution of ice-inhibiting fluids on a propeller blade

A flight investigation of the distribution of ice-inhibiting fluids on a propeller blade

Date: September 1, 1939
Creator: Rodert, Lewis A
Description: None
Contributing Partner: UNT Libraries Government Documents Department
An instrument for estimating tautness of doped fabrics on aircraft

An instrument for estimating tautness of doped fabrics on aircraft

Date: September 1, 1939
Creator: Kline, Gordon M & Schiefer, Herbert F
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Wind-tunnel investigation of an N.A.C.A. 23021 airfoil with two arrangements of a 40-percent-chord slotted flap

Wind-tunnel investigation of an N.A.C.A. 23021 airfoil with two arrangements of a 40-percent-chord slotted flap

Date: September 1, 1939
Creator: Duschik, Frank
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Wind-tunnel investigation of effect of yawing on lateral-stability characteristics II : rectangular N.A.C.A. 23012 wing with a circular fuselage

Wind-tunnel investigation of effect of yawing on lateral-stability characteristics II : rectangular N.A.C.A. 23012 wing with a circular fuselage

Date: September 1, 1939
Creator: Bamber, M J & House, R G
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Adhesion of ice in its relation to the de-icing of airplanes

Adhesion of ice in its relation to the de-icing of airplanes

Date: August 1, 1939
Creator: Rothrick, A M & Selden, R
Description: The various possible means of preventing ice adhesion on airplane surfaces are critically reviewed. Results are presented of tests of the adhesives forces between ice and various solid and liquid forces. It is concluded that the de-icing of airplane wings by heat from engine exhaust shows sufficient promise to warrant full-scale tests. For propellers, at least, and possibly for certain small areas such as windshields, radio masts, etc. the use of de-icing or adhesion-preventing liquids will provide the best means of protection.
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Compression-ignition engine performance with undoped and doped fuel oils and alcohol mixtures

Compression-ignition engine performance with undoped and doped fuel oils and alcohol mixtures

Date: August 1, 1939
Creator: Moore, Charles S & Foster, Hampton H
Description: Several fuel oils, doped fuel oils, and mixtures of alcohol and fuel oil were tested in a high-speed, single-cylinder, compression-ignition engine to determine power output, fuel consumption, and ignition and combustion characteristics. Fuel oils or doped fuel oils of high octane number had shorter ignition lags, lower rates of pressure rise, and gave smoother engine operation than fuel oils or doped fuel oils of low octane number. Higher engine rotative speeds and boost pressures resulted in smoother engine operation and permitted the use of fuel oils of relatively low octane number. Although the addition of a dope to a fuel oil decreased the ignition lag and the rate of pressure rise, the ensuing rate of combustion was somewhat slower than for the undoped fuel oil so that the effectiveness of combustion was practically unchanged. Alcohol used as an auxiliary fuel, either as a mixture or by separate injection, increased the rates of pressure rise and induced roughness. In general, the power output decreased as the proportion of alcohol increased and, below maximum power, varied with the heating value of the total fuel charge.
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Compressive tests of a monocoque box

Compressive tests of a monocoque box

Date: August 1, 1939
Creator: Ramberg, Walter; Mcpherson, Albert E & Levy, Sam
Description: A monocoque box specimen of aluminum alloy was subjected to end compression and the strains in the stringers were measured up to loads at which permanent set became noticeable. The stringer strains at low loads agreed closely with those computed from the assumption of uniform stress distribution. Buckling of the 0.026-inch sheet between stringers and of the 0.075-inch shear web took place at stresses in accord with theoretical values. Permanent set became noticeable at a load of 115,200 pounds, corresponding to an average stringer stress of about 16,000 pounds per square inch. The measured average strain above the first buckling load was within 2 percent of the theoretical strain as calculated from the dimensions of the box and effective width formulas due to Marguerre and to Cox.
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The effects of surface waviness and of rib stitching on wing drag

The effects of surface waviness and of rib stitching on wing drag

Date: August 1, 1939
Creator: Hood, Manley J
Description: Surface waviness and rib stitching have been investigated as part of a series of tests to determine the effects on wing drag of common surface irregularities. The tests were made in the N.A.C.A. 8-foot high-speed wind tunnel at Reynolds Numbers up to 17,000,000. The results of the tests showed that the waviness common to airplane wings will cause no serious increase in drag unless the waviness exists on the forward part of the wing, where it may cause premature transition or premature compressibility effects. Waves 3 inches wide and 0.048 inch high, for example, increased the drag 1 percent when they covered the rear 67 percent of both surfaces and 10 percent when they covered the rear 92 percent. A single wave 3 inches wide and only 0.020 inch high at the 10.5-percent-chord point on the upper surface caused transition to occur on the wave and increased the drag 6 percent. Rib stitching increased the drag 7 percent when the rib spacing was 6 inches; the drag increment was proportional to the number of ribs for wider spacings. About one-third of the increase was due to premature transition at the forward ends of the stitching.
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Flight tests of N.A.C.A. nose-slot cowlings on the BFC-1 airplane

Flight tests of N.A.C.A. nose-slot cowlings on the BFC-1 airplane

Date: August 1, 1939
Creator: Stickle, George W
Description: The results of flight tests of four nose-slot cowling designs with several variations in each design are presented. The tests were made in the process of developing the nose-slot cowling. The results demonstrate that a nose-slot cowling may be successfully applied to an airplane and that it utilizes the increased slipstream velocity of low-speed operation to produce increased cooling pressure across the engine. A sample design calculation using results from wind-tunnel, flight, and ground tests is given in an appendix to illustrate the design procedure.
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Local instability of centrally loaded columns of channel section and Z-section

Local instability of centrally loaded columns of channel section and Z-section

Date: August 1, 1939
Creator: Lundquist, Eugene E
Description: Charts are presented for the coefficients in formulas for the critical compressive stress at which cross-sectional distortion begins in a thin-wall member with either a channel section or a Z-section with identical flanges. The energy method of Timoshenko was used in the theoretical calculations required for the construction of the charts. The deflection equations were carefully selected to give good accuracy. The calculation of the critical compressive stress at stresses beyond the elastic range is briefly discussed. In order to demonstrate the use of the formulas and the charts in engineering calculations, two illustrative problems are included.
Contributing Partner: UNT Libraries Government Documents Department
Tank tests to determine the effects of the chine flare of a flying-boat hull N.A.C.A. Model Series 62 and 69

Tank tests to determine the effects of the chine flare of a flying-boat hull N.A.C.A. Model Series 62 and 69

Date: August 1, 1939
Creator: Bell, Joe W & Olson, Roland E
Description: None
Contributing Partner: UNT Libraries Government Documents Department
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