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A Method of Estimating the Critical Buckling Load for Structural Members

Description: "The relations between load on the structure and rotation of a joint can be used to estimate the lowest critical load after the equation for neutral stability has been tested for three assumed critical loads, each of which is less than the lowest critical load. The solutions of six simple problems are included to illustrate the application of the method of estimating critical loads and to reveal certain characteristics of the method that should be known by the practical engineer using it. Four … more
Date: July 1939
Creator: Lundquist, Eugene E.
Partner: UNT Libraries Government Documents Department
open access

Experimental Study of Torsional Column Failure

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… more
Date: October 1939
Creator: Niles, Alfred S.
Partner: UNT Libraries Government Documents Department
open access

Local Instability of Symmetrical Rectangular Tubes Under Axial Compression

Description: "A chart is presented for the coefficient in the formula for the critical compressive stress at which cross sectional distortion begins in a thin-wall tube of rectangular section symmetrical about its two principal axes. The energy method of Timoshenko was used in the theoretical calculations required for the construction of the chart. The deflection equation used in this method was selected to give good accuracy" (p. 1).
Date: February 1939
Creator: Lundquist, Eugene E.
Partner: UNT Libraries Government Documents Department
open access

Flight Tests of N.A.C.A. Nose-Slot Cowlings on the BFC-1 Airplane

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" (p. 1).
Date: August 1939
Creator: Stickle, George W.
Partner: UNT Libraries Government Documents Department
open access

Pressure-Distribution Measurements on a Rectangular Wing With a Partial-Span Split Flap in Curved Flight

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 mome… more
Date: December 1939
Creator: Rokus, Frank G.
Partner: UNT Libraries Government Documents Department
open access

Loads Imposed on Intermediate Frames of Stiffened Shells

Description: "The loads imposed on intermediate frames by the curvature of the longitudinal and by the diagonal-tension effects are treated. A new empirical method is proposed for analyzing diagonal-tension effects. The basic formulas of the pure diagonal-tension theory are used, and the part of the total shear S carried by diagonal tension is assumed to be given the expression S (sub DT) = S (1-tau sub o/tau)(sup n) where tau (sub o) is the critical shear stress, tau the total (nominal shear stress), and n… more
Date: February 1939
Creator: Kuhn, Paul
Partner: UNT Libraries Government Documents Department
open access

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

Description: From Summary: "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 rang… more
Date: December 1939
Creator: Stowell, Elbridge Z. & Lundquist, Eugene E.
Partner: UNT Libraries Government Documents Department
open access

Compressive Tests of a Monocoque Box

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" (p. 1).
Date: August 1939
Creator: Ramberg, Walter; McPherson, Albert E. & Levy, Sam
Partner: UNT Libraries Government Documents Department
open access

Comparative Performance of Engines Using a Carburetor, Manifold Injection, and Cylinder Injection

Description: "The comparative performance was determined of engines using three methods of mixing the fuel and the air: the use of a carburetor, manifold injection, and cylinder injection. The tests were made of a single-cylinder engine with a Wright 1820-G air-cooled cylinder. Each method of mixing the fuel and the air was investigated over a range of fuel-air ratios from 0.10 to the limit of stable operation and at engine speeds of 1,500 and 1,900 r.p.m." (p. 1).
Date: February 1939
Creator: Schey, Oscar W. & Clark, J. Denny
Partner: UNT Libraries Government Documents Department
open access

Pressure-Distribution Investigation of an N.A.C.A. 0009 Airfoil With a 50-Percent-Chord Plain Flap and Three Tabs

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" (p. 1).
Date: November 1939
Creator: Street, William G. & Ames, Milton B., Jr.
Partner: UNT Libraries Government Documents Department
open access

The charging process in a high-speed, single-cylinder, four-stroke engine

Description: From Summary: "Experimental measurements and theoretical calculations were made on an aircraft-type, single cylinder engine, in order to determine the physical nature of the inlet process, especially at high piston speeds. The engine was run at speeds from 1,500 to 2,600 r.p.m. (mean piston speeds of 1,370 to 2,380 feet per minute). Measurements were made of the cylinder pressure during the inlet stroke and of the power output and volumetric efficiency. Measurements were also made, with the eng… more
Date: February 1939
Creator: Reynolds, Blake; Schecter, Harry & Taylor, E. S.
Partner: UNT Libraries Government Documents Department
open access

Pressure-Distribution Measurements on a Tapered Wing With a Partial-Span Split Flap in Curved Flight

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" … more
Date: November 1939
Creator: Troller, T. & Rokus, F.
Partner: UNT Libraries Government Documents Department
open access

Resistance of transparent plastics to impact

Description: From Summary: "The problem of developing a windshield for aircraft which will withstand the effect of bird impacts during flight is a difficult one, as an estimate of the striking energy will indicate. If the average speed of the airplane is considered to be about 200 miles per hour and that of the bird about 70 miles per hour, the speed of the bird relative to the airplane may be as great as 400 feet per second. If a 4-pound bird is involved, a maximum impact energy of approximately 10,000 foo… more
Date: July 1939
Creator: Axilrod, Benjamin M. & Kline, Gordon M.
Partner: UNT Libraries Government Documents Department
open access

Tidewater and Weather-Exposure Tests on Metals Used in Aircraft

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" (p. 1).
Date: November 1939
Creator: Mutchler, Willard & Galvin, W. G.
Partner: UNT Libraries Government Documents Department
open access

Photoelastic Analysis of Three-Dimensional Stress Systems Using Scattered Light

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" (p… more
Date: November 1939
Creator: Weller, R. & Bussey, J. K.
Partner: UNT Libraries Government Documents Department
open access

A Recurrence Formula for Shear-Lag Problems

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 th… more
Date: December 1939
Creator: Kuhn, Paul
Partner: UNT Libraries Government Documents Department
open access

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

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 … more
Date: December 1939
Creator: Dumont, C.
Partner: UNT Libraries Government Documents Department
open access

The effects of partial-span slotted flaps on the aerodynamic characteristics of a rectangular and a tapered N.A.C.A. 23012 wing

Description: An investigation was made in the N.A.C.A. 7- by 10-foot wind tunnel to determine the aerodynamic characteristics of tapered and rectangular wings with partial-span slotted flaps. Two N.A.C.A. 23012 airfoils equipped with center-section and tip-section flaps were tested. The results showed that the changes in lift and drag due to changes in flap span for both rectangular and tapered wings having partial-span slotted flaps were similar to those for corresponding wings having partial-span split or… more
Date: July 1939
Creator: House, Rufus O.
Partner: UNT Libraries Government Documents Department
open access

Observations in Flight of the Region of Stalled Flow Over the Blades of an Autogiro Rotor

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 gr… more
Date: December 1939
Creator: Bailey, F. J., Jr. & Gustafson, F. B.
Partner: UNT Libraries Government Documents Department
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A comparison of several tapered wings designed to avoid tip stalling

Description: From Summary: "Optimum proportions of tapered wings were investigated by a method that involved a comparison of wings designed to be aerodynamically equal. The conditions of aerodynamic equality were equality in stalling speed, in induced drag at a low speed, and in the total drag at cruising speed. After the wings were adjusted to aerodynamic equivalence, the weights of the wings were calculated as a convenient method of indicating the optimum wing. The aerodynamic characteristics were calcula… more
Date: June 1939
Creator: Anderson, Raymond F.
Partner: UNT Libraries Government Documents Department
open access

Pressure-Distribution Measurements on a Tapered Wing With a Full-Span Split Flap in Curved Flight

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 yawing moments due to an angular velocity in yaw. The model was tested at 0 degree and 5 degrees pitch, -1 degree and 5 degree yaw, and with a full-span flap deflected 60 degrees. The results are given in the form of span load distributions and in calculated moment coefficients" (p. 1).
Date: January 1939
Creator: Troller, T. & Rokus, F.
Partner: UNT Libraries Government Documents Department
open access

Flight Tests of Retractable Ailerons on a Highly Tapered Wing

Description: "A flight investigation was conducted to determine the lateral-control characteristics of retractable ailerons installed on a highly tapered wing. The effectiveness of the ailerons in producing roll was measured at various air speeds with full-span plain flaps both neutral and deflected 45 degrees. The direction of the yawing moment created by the ailerons was also noted. The lateral control provided by the retractable ailerons used in this investigation was approximately the same as that obtai… more
Date: June 1939
Creator: Wetmore, J. W.
Partner: UNT Libraries Government Documents Department
open access

Wind-Tunnel Investigation of Ground Effect on Wings With Flaps

Description: From Summary: "An investigation was conducted in the N.A.C.A. 7- by 10-foot wind tunnel to determine the effect of ground proximity on the aerodynamic characteristics of wings equipped with high-lift devices. A rectangular and a tapered wing were tested without flaps, with a split flap, and with a slotted flap. The ground was represented by a flat plate, completely spanning the tunnel and extending a considerable distance ahead and back of the model. The position of the plate was varied from on… more
Date: May 1939
Creator: Recant, Isidore G.
Partner: UNT Libraries Government Documents Department
open access

An Experimental Investigation of the Normal Acceleration of an Airplane Model in a Gust

Description: Note presenting an investigation in the gust tunnel to determine the influence of airplane wing loading, forward velocity, wing plan form, and the fuselage on the reaction of the airplane to a known gust. Tests were made for four values of gust velocity and for two gust gradients, specifically the sharp-edge gust and a gust rising linearly to full strength in a distance of several chord lengths.
Date: May 1939
Creator: Donely, Philip
Partner: UNT Libraries Government Documents Department
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