National Advisory Committee for Aeronautics (NACA) - 118 Matching Results

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Tests of rotating cylinders

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.
Date: December 1, 1924
Creator: Reid, Elliott G
Partner: UNT Libraries Government Documents Department

Micarta propellers III : general description of the design

Description: The design of propellers made of Micarta is discussed. The advantages of the material are noted, especially as compared with wood. The design changes necessitated by the use of Micarta are discussed with reference to the hub boss, the narrowing of the blade tips, the thinning of the blades, the angles of the leading and trailing edges, and the adjustment of the pitch. Results of flight tests show that the Micarta propeller gave a top speed of 2 miles per hour more than the wooden propeller while turning about 120 r.p.m slower, with about the same rate of climb. At top speed, the Micarta propeller shows an improvement of about 7 percent in fuel economy, although the plane is flying 2 miles per hour faster.
Date: August 1, 1924
Creator: Caldwell, F W & Clay, N S
Partner: UNT Libraries Government Documents Department

Micarta propellers IV : technical methods of design

Description: A description is given of the methods used in design of Micarta propellers. The most direct method for working out the design of a Micarta propeller is to start with the diameter and blade angles of a wooden propeller suited for a particular installation and then to apply one of the plan forms suitable for Micarta propellers. This allows one to obtain the corresponding blade widths and to then use these angles and blade widths for an aerodynamic analysis.
Date: September 1, 1924
Creator: Caldwell, F W & Clay, N S
Partner: UNT Libraries Government Documents Department

High altitude flying

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.
Date: May 1, 1924
Creator: King, Paul B & Carroll, Thomas
Partner: UNT Libraries Government Documents Department

Dynamic stability as affected by the longitudinal moment of inertia

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.
Date: January 1, 1924
Creator: Wilson, Edwin B.
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

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.
Date: January 1, 1924
Creator: Newlin, J A & Trayer, G W
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

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 inertia, which are similarly loaded, are proportional to the summations of the shear stresses on their respective vertical sections. Both formulas check experimental results very closely when the calculations are made with great refinement.
Date: January 1, 1924
Creator: Newlin, J A & Trayer, G W
Partner: UNT Libraries Government Documents Department

The Inertial Coefficients of an Airship in a Frictionless Fluid

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 also and a coefficient has been defined with the same advantages as the corresponding coefficient for rectilinear motion.
Date: January 1, 1924
Creator: Bateman, H
Partner: UNT Libraries Government Documents Department

The effect of slipstream obstructions on air propellers

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.
Date: January 1, 1924
Creator: Lesley, E P & Woods, B M
Partner: UNT Libraries Government Documents Department

Tests on a model of the D.F.W. airplane T-29 of the "Deutsche Flugzeug derke" (German airplane works)

Description: Experiments similar to those carried out with the A.E.G (Allgemeine Elektrizitats-Gesellschaft) were made in the small wind tunnel of the Gottingen laboratory on a model of the D.F.W. airplane T-29. Three series of tests were carried out on the model with a velocity head (or dynamic pressure) of 5 kg/sq m (1.02 lb/sq ft), during which one of the movable surfaces was deflected at various angles, while both the others were retained in their central positions. Of special interest among the results of the tests is the different run of the elevating moments. The curves for the A.E.G. model, rising to the right, denote stability with the elevator locked, while the slight inclination to the left with the D.F.W model denotes a slight instability. For the maximum C(sub L) values, the stability of A.E.G. model continues to increase and the instability of the D.F.W. model is converted into stability. The rolling moments shown when the angular deflection of the ailerons is 0 degrees are due, in both series of tests, to the unequal distribution of the air velocity over the cross section of the wind tunnel, rather than to a lack of symmetry in the model.
Date: January 1, 1924
Creator: Molthan, Wilhelm
Partner: UNT Libraries Government Documents Department

Torsional strength of nickel steel and duralumin tubing as affected by the ratio of diameter to gage thickness

Description: This investigation was made at the request of the Bureau of Aeronautics. Since the ordinary torsion formula is based on elastic resistance to deformation, it is inaccurate for determination of ultimate stresses in thin wall tubing subjected to torsional loads. It has been found that the torsional modulus of rupture varies with the ratio of diameter to gage thickness and the object of these tests was to determine the extent of these variations for subject materials. This is somewhat of a prorogation of work done by the Army Air Service at McCook Field.
Date: April 1, 1924
Creator: Otey, N S
Partner: UNT Libraries Government Documents Department

Practical method for balancing airplane moments

Description: The present contribution is the sequel to a paper written by Messrs. R. Fuchs, L. Hopf, and H. Hamburger, and proposes to show that the methods therein contained can be practically utilized in computations. Furthermore, the calculations leading up to the diagram of moments for three airplanes, whose performance in war service gave reason for complaint, are analyzed. Finally, it is shown what conclusions can be drawn from the diagram of moments with regard to the defects in these planes and what steps may be taken to remedy them.
Date: February 1, 1924
Creator: Hamburger, H
Partner: UNT Libraries Government Documents Department

Triplane tests

Description: These experiments were carried out to determine the aerodynamic characteristics of various triplanes, which differed in the relative positions of the wings and, more especially, in the stagger, and in the shape of the wing sections. The tests were restricted to such dispositions as appeared constructively adapted to the plan form considered. Four different sets of wings were used in these tests, three of which had the same cross-section but differed in aspect ratio and in area. The tests were made at an air velocity of about 30 m.p.s. (98.4 ft/sec.) in the large wind tunnel. Results are given in tabular and graphical form.
Date: February 1, 1924
Creator: Wieselsberger, C
Partner: UNT Libraries Government Documents Department

Micarta propellers I : materials

Description: Here, values for tension, compression edgewise of laminations, and transverse flatwise of laminations are given for Micarta made with various kinds of sheet material. The corresponding values for white oak are given for comparison. It was found by destructive and service tests that Micarta made with a good grade of cotton duck will give satisfactory service with most designs. In propellers having detachable blades, it is desirable that the root of the blade be of a small cross section to decrease the weight of the metal hub. Here the use of the special fabric or wood veneer offers advantages due to greater tensile strength. These materials, especially the wood veneer, produce stiffer blades than duck. This is also a value in controllable and reversible pitch designs where it is desirable that the plan form of the blades be symmetrical.
Date: August 1, 1924
Creator: Caldwell, F W & Clay, N S
Partner: UNT Libraries Government Documents Department

The induction factor used for computing the rolling moment due to the ailerons

Description: In the following note, prepared for the National Advisory Committee for Aeronautics, this induction factor is determined from the result of a model test, and compared with a formula recently developed by the author. The two results are found to be in substantial agreement.
Date: April 1, 1924
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department

Duralumin, its properties and uses

Description: A historical sketch of duralumin is presented, especially in regards to its manufacture by various countries. The properties of duralumin are discussed and strength characteristics listed. Increasing the hardness of duralumin by tempering is discussed as well as the uses of the metal.
Date: October 1, 1924
Creator: Beck, R
Partner: UNT Libraries Government Documents Department