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  Partner: UNT Libraries Government Documents Department
 Decade: 1920-1929
 Year: 1924
 Collection: National Advisory Committee for Aeronautics Collection
The testing of aviation engines

The testing of aviation engines

Date: December 1, 1924
Creator: Dubois, R N
Description: None
Contributing Partner: UNT Libraries Government Documents Department
The influence of the form of a wooden beam on its stiffness and strength II : form factors of beams subjected to transverse loading only

The influence of the form of a wooden beam on its stiffness and strength II : form factors of beams subjected to transverse loading only

Date: January 1, 1924
Creator: Newlin, J A & Trayer, G W
Description: The general aim of the investigation described in this report is the achievement of efficient design in wing beams. The purpose of the tests was to determine factors to apply to the usual beam formula in order that the properties of wood based on tests of rectangular sections might be used as a basis of design for beams of any sections and if practical to develop formulas for determining such factors and to verify them by experiment. Such factors for various sections have been determined from test by comparing properties of the beam in question to similar properties of matched beams 2 by 2 inches in section. Furthermore, formulas were worked out, more or less empirical in character, which check all of these test values remarkably well.
Contributing Partner: UNT Libraries Government Documents Department
The influence of the form of a wooden beam on its stiffness and strength I : deflection of beams with special reference to shear deformations

The influence of the form of a wooden beam on its stiffness and strength I : deflection of beams with special reference to shear deformations

Date: January 1, 1924
Creator: Newlin, J A & Trayer, G W
Description: The purpose of this investigation was to determine to what extent ordinary deflection formulas, which neglect shear deformations, are in error when applied to beams of various sections, and to develop reasonably accurate yet comparatively simple formulas which take into account such deformations. A great many tests were made to determine the amount of shear deformation for beams of various sections tested over many different spans. As the span over which the beam is tested is increased the error introduced by neglecting shear deformations becomes less, and the values obtained by substituting measured deflections in the ordinary formulas approach more nearly the modulus of elasticity in tension and compression. For short spans the error is considerable and increases rapidly as the span is reduced. Two formulas were developed for estimating the magnitude of shear deformations, both of which have been verified by tests. The first assumes the parabolic distribution of shear on a cross section of a beam and, starting with a differential volume, the distortion due to shear is determined by the ordinary methods of summarizing the work. The second assumes that the deflections due to shear in any two beams of the same length, height, and moment of ...
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The effect of slipstream obstructions on air propellers

The effect of slipstream obstructions on air propellers

Date: January 1, 1924
Creator: Lesley, E P & Woods, B M
Description: The screw propeller on airplanes is usually placed near other objects, and hence its performance may be modified by them. Results of tests on propellers free from slip stream obstructions, both fore and aft, are therefore subject to correction, for the effect of such obstructions and the purpose of the investigation was to determine the effect upon the thrust and torque coefficients and efficiency, for previously tested air propellers, of obstructions placed in the slip stream, it being realized that such previous tests had been conducted under somewhat ideal conditions that are impracticable of realization in flight. Simple geometrical forms were used for the initial investigation. Such forms offered the advantage of easy, exact reproduction at another time or in other laboratories, and it was believed that the effects of obstructions usually encountered might be deduced or surmise from those chosen.
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The Inertial Coefficients of an Airship in a Frictionless Fluid

The Inertial Coefficients of an Airship in a Frictionless Fluid

Date: January 1, 1924
Creator: Bateman, H
Description: This report deals with the investigation of the apparent inertia of an airship hull. The exact solution of the aerodynamical problem has been studied for hulls of various shapes and special attention has been given to the case of an ellipsoidal hull. In order that the results for this last case may be readily adapted to other cases, they are expressed in terms of the area and perimeter of the largest cross section perpendicular to the direction motion by means of a formula involving a coefficient K which varies only slowly when the shape of the hull is changed, being 0.637 for a circular or elliptic disk, 0.5 for a sphere, and about 0.25 for a spheroid of fineness ratio 7. For rough purposes it is sufficient to employ the coefficients, originally found for ellipsoids, for hulls otherwise shaped. When more exact values of the inertia are needed, estimates may be based on a study of the way in which K varies with different characteristics and for such a study the new coefficient possesses some advantage over one which is defined with reference to the volume of fluid displaced. The case of rotation of an airship hull has been investigated ...
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The resistance of spheres in wind tunnels and in air

The resistance of spheres in wind tunnels and in air

Date: January 1, 1924
Creator: Bacon, D L & Reid, E G
Description: To supplement the standardization tests now in progress at several laboratories, a broad investigation of the resistance of spheres in wind tunnels and free air has been carried out by the National Advisory Committee for Aeronautics. The subject has been classed in aerodynamic research, and in consequence there is available a great mass of data from previous investigations. This material was given careful consideration in laying out the research, and explanation of practically all the disagreement between former experiments has resulted. A satisfactory confirmation of Reynolds law has been accomplished, the effect of means of support determined, the range of experiment greatly extended by work in the new variable density wind tunnel, and the effects of turbulence investigated by work in the tunnels and by towing and dropping tests in free air. It is concluded that the erratic nature of most of the previous work is due to support interference and differing turbulence conditions. While the question of support has been investigated thoroughly, a systematic and comprehensive study of the effects of scale and quality of turbulence will be necessary to complete the problem, as this phase was given only general treatment.
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Complete study of longitudinal oscillation of a VE-7 airplane

Complete study of longitudinal oscillation of a VE-7 airplane

Date: January 1, 1924
Creator: Norton, F H & Brown, W G
Description: This investigation was carried out by the National Advisory Committee for Aeronautics at Langley Field in order to study as closely as possible the behavior of an airplane when it was making a longitudinal oscillation. The airspeed, the altitude, the angle with the horizon and the angle of attack were all recorded simultaneously and the resulting curves plotted to the same time scale. The results show that all the curves are very close to damped sine curves, with the curves for height and angle of attack in phase, that for angle with the horizon leading them by 18 per cent and that for path angle leading them by 25 per cent.
Contributing Partner: UNT Libraries Government Documents Department
The effect of airfoil thickness and plan form on lateral control

The effect of airfoil thickness and plan form on lateral control

Date: January 1, 1924
Creator: Hoot, H I
Description: This investigation was carried out for the purpose of determining the effectiveness of ailerons and tests were made on six model airfoils in the no. 1 wind tunnel of the National Advisory Committee for Aeronautics. The method consisted in measuring the rolling moments and aileron moments in the ordinary way. In addition to this the wing was allowed to spin freely about an axis in the direction of the air flow and the angular velocity measured. The results show that the thickness of the airfoil has very little effect on either the rolling moment or the hinge moment, although the resulting efficiency is somewhat higher for the tapered wings. The airfoil tapered in plan form, however, shows practically no falling off in the rolling moment at the critical angle of attack, whereas the wings of rectangular plan form show a marked dropping off in the rolling moment at this point. This indicates that it is possible to obtain good lateral control with small ailerons at low speed if the plan form is tapered. The rotational speed of the different airfoils is practically the same for all of the sections tested.
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Tests of rotating cylinders

Tests of rotating cylinders

Date: December 1, 1924
Creator: Reid, Elliott G
Description: Tests were made in the no. 1 wind tunnel at Langley Memorial Aeronautical Laboratory to determine the air forces acting on rotating cylinders with axes perpendicular to the direction of motion. One cylinder had a circular cross-section, the other that of a greek cross.
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The vertical, longitudinal, and lateral accelerations experienced by an S. E. 5a airplane while maneuvering

The vertical, longitudinal, and lateral accelerations experienced by an S. E. 5a airplane while maneuvering

Date: January 1, 1924
Creator: Norton, F H & Carroll, T
Description: This investigation was carried out by the Langley Field Laboratory of the National Advisory Committee for Aeronautics for the purpose of measuring the accelerations along the three principal axes of an airplane while it was maneuvering. The airplane selected for this purpose was the fairly maneuverable SE-5A and the instruments used were the NACA three component accelerometer and the NACA recording airspeed meter. The results showed that the normal accelerations did not exceed 4.000 G. While the lateral and longitudinal accelerations did not exceed 0.60 G.
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A study of static stability of airships

A study of static stability of airships

Date: September 1, 1924
Creator: Rizzo, Frank
Description: The first section deals with the theoretical side of statical stability of airships in general. The second section deals with preliminary tests of the model and experiments for the determination of effects due to change of tail area, aspect ratio, tail form, and tail thickness.
Contributing Partner: UNT Libraries Government Documents Department
The distribution of lift over wing tips and ailerons

The distribution of lift over wing tips and ailerons

Date: January 1, 1924
Creator: Bacon, David L
Description: This investigation was carried out in the 5-foot wind tunnel of the Langley Memorial Aeronautical Laboratory for the purpose of obtaining more complete information on the distribution of lift between the ends of wing spars, the stresses in ailerons, and the general subject of airflow near the tip of a wing. It includes one series of tests on four models without ailerons, having square, elliptical, and raked tips respectively, and a second series of positively and negatively raked wings with ailerons adjusted to different settings. The results show that negatively raked tips give a more uniform distribution of air pressure than any of the other three arrangements, because the tip vortex does not disturb the flow at the trailing edge. Aileron loads are found to be less severe on wings with negative application to the calculation of aileron and wing stresses and also to facilitate the proper distribution of load in sand testing. Contour charts show in great detail the complex distribution lift over the wing.
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The small angular oscillations of airplanes in steady flight

The small angular oscillations of airplanes in steady flight

Date: January 1, 1924
Creator: Norton, F H
Description: This investigation was carried out by the National Advisory Committee for Aeronautics at the request of the Army Air Service to provide data concerning the small angular oscillations of several types of airplanes in steady flight under various atmospheric conditions. The data are of use in the design of bomb sights and other aircraft instruments. The method used consisted in flying the airplane steadily in one direction for at least one minute, while recording the angle of the airplane with the sun by means of a kymograph. The results show that the oscillations differ but little for airplanes of various types, but that the condition of the atmosphere is an important factor. The average angular excursion from the mean in smooth air is 0.8 degrees in pitch, 1.4 degrees in roll, and 0.9 degrees in yaw, without special instruments to aid the pilot in holding steady conditions. In bumpy air the values given above are increased about 50 per cent. (author).
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Dynamic stability as affected by the longitudinal moment of inertia

Dynamic stability as affected by the longitudinal moment of inertia

Date: January 1, 1924
Creator: Wilson, Edwin B.
Description: In a recent Technical Note (NACA-TN-115, October, 1922), Norton and Carrol have reported experiments showing that a relatively large (15 per cent) increase in longitudinal moment of inertia made no noticeable difference in the stability of a standard SE-5A airplane. They point out that G. P. Thomson, "Applied Aeronautics," page 208, stated that an increase in longitudinal moment of inertia would decrease the stability. Neither he nor they make any theoretical forecast of the amount of decrease. Although it is difficult, on account of the complications of the theory of stability of the airplane, to make any accurate forecast, it is the purpose of this report to attempt a discussion of the matter theoretically with reference to finding a rough quantitative estimate.
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High altitude flying

High altitude flying

Date: May 1, 1924
Creator: King, Paul B & Carroll, Thomas
Description: This note investigates the effect of high altitude or low atmospheric pressure upon the operation of an engine and the effect of the low pressure and lack of oxygen and of the very low temperatures upon the pilot and upon the performance of the airplane itself.
Contributing Partner: UNT Libraries Government Documents Department
Increasing the compression pressure in an engine by using a long intake pipe

Increasing the compression pressure in an engine by using a long intake pipe

Date: February 1, 1924
Creator: Mathews, Robertson & Gardiner, Arthur W
Description: During some tests of a one-cylinder engine, using gas oil (diesel engine oil, specific gravity 0.86 at 60 F) with solid injection and compression ignition, it was found to be necessary to increase either the jacket water temperature or the compression pressure in order to start the engine. It was found that a sufficient increase in compression pressure could be obtained simply by attaching a long pipe to the inlet flange of the cylinder. However, since no data were available giving the values of the increase in compression pressure that might be expected from such a step-up, an investigation was made covering some engine speeds between 500 r.p.m. and 1800 r.p.m. The data obtained are included here in the form of curves. Although this data is not strictly applicable to another engine, it should give indications of what might be expected with such a set-up on an engine operating at similar speeds. The engine used was a single cylinder Liberty, 5-inch bore and 7-inch stroke, having standard cylinder, cams, valves, and valve timing and operating on a four-stroke cycle.
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The influence of inlet air temperature and jacket water temperature on initiating combustion in a high speed compression ignition engine

The influence of inlet air temperature and jacket water temperature on initiating combustion in a high speed compression ignition engine

Date: March 1, 1924
Creator: Matthews, Robertson & Gardiner, Arthur W
Description: None
Contributing Partner: UNT Libraries Government Documents Department
The measurement of the damping in roll on a JN4h in flight

The measurement of the damping in roll on a JN4h in flight

Date: January 1, 1924
Creator: Norton, F H
Description: This investigation was carried out by the National Advisory Committee for Aeronautics for the purpose of measuring the value of L sub P in flight. The method consisted in flying with heavy weights on each wing tip, suddenly releasing one of them, and allowing the airplane to roll up to 90 degrees with controls held in neutral while a record was being taken of the airspeed, and angular velocity about the X axis. The results are of interest as they show that the damping found in the wind tunnel by the method of small oscillations is in general 40 per cent higher than the damping in flight. At 50 M. P. H. The flight curve of L sub P has a high peak, which is not indicated in the model results. It is also shown that at this speed the lateral maneuverability is low.
Contributing Partner: UNT Libraries Government Documents Department
A study of longitudinal dynamic stability in flight

A study of longitudinal dynamic stability in flight

Date: January 1, 1924
Creator: Norton, F H
Description: This investigation was carried out by the aerodynamic staff of the National Advisory Committee for Aeronautics for the purpose of studying experimentally the longitudinal dynamic stability of airplanes in flight. The airplanes selected for this purpose were a standard rigged VE-7 advanced-training airplane and a JN4H with special tail surfaces. The airplanes were caused to oscillate by means of the elevator, then the longitudinal control was either locked or kept free while the oscillation died out. The magnitude of the oscillation was recorded either by a kymograph or an airspeed meter. The results show that the engine speed has as much effect on the period and damping as the airspeed, and that, contrary to theory as developed for small oscillations, the damping decreased at the higher airspeeds with closed throttle.
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The vector ruling protractor

The vector ruling protractor

Date: March 1, 1924
Creator: Zahm, A F
Description: The theory, structure and working of a vector slide rule is presented in this report. This instrument is used for determining a vector in magnitude and position when given its components and its moment about a point in their plane.
Contributing Partner: UNT Libraries Government Documents Department
Ultra-light alloys and their utilization on aircraft

Ultra-light alloys and their utilization on aircraft

Date: May 1, 1924
Creator: Defleury, R & Portevin, A M
Description: We will arbitrarily call alloys having a specific gravity of less than 2 "ultra-light", in order to distinguish them from "light" alloys with a specific gravity of 2 to 3. Thus far it has been possible to make ultra-light alloys only by employing a large proportion of magnesium.
Contributing Partner: UNT Libraries Government Documents Department
Device for measuring sound in airplane engines

Device for measuring sound in airplane engines

Date: June 1, 1924
Creator: Robrovsky, T
Description: I will here call attention to a device, constructed according to the system of Gati with which it is possible to measure the sound of an engine and test the effect of a silencer.
Contributing Partner: UNT Libraries Government Documents Department
Effect of changing the mean camber of an airfoil section

Effect of changing the mean camber of an airfoil section

Date: March 1, 1924
Creator: Toussaint, A
Description: Methodical experiments with the series of airfoil sections of the same relative thickness and of variable relative cambers can be utilized for determining the effect of the camber on the aerodynamic properties of airfoil sections.
Contributing Partner: UNT Libraries Government Documents Department
Loss of the Dixmude

Loss of the Dixmude

Date: April 1, 1924
Creator: Eckener, Hugo
Description: The causes of the destruction of the Dixmude are discussed and some conclusions are drawn. The author believes a gasoline fire instead of a lightning strike was probably responsible, but the public believes otherwise.
Contributing Partner: UNT Libraries Government Documents Department
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