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The NACA three component accelerometer

Description: A new instrument known as the NACA three component accelerometer is described in this note. This instrument was designed by the technical staff of the NACA for recording accelerations along three mutually perpendicular axes, and is of the same type as the NACA single component accelerometer with the addition of two springs and a few minor improvements such as a pump for filling the dash-pots and a convenient method for aligning the springs. This note includes a few records as well as photographs of the instrument itself.
Date: October 1, 1922
Creator: Reid, H. J. E.
Partner: UNT Libraries Government Documents Department

Syphon diaphragms : a method for predicting their performance for purposes of instrument design

Description: Here, the purpose is to show that the characteristic performance of a syphon diaphragm can be predicted from a knowledge of its stiffness and of its dimensions. The proof is based on a mathematical analysis of this type of diaphragm, together with enough experimental data to prove the validity of the assumptions and the sufficiency of the analysis. Equations are developed for the performance of syphons under various conditions of loading, both for concentrated loads and for hydrostatic pressure.
Date: January 1, 1922
Creator: Eaton, H N & Keulegan, G H
Partner: UNT Libraries Government Documents Department

Surface area coefficients for airship envelopes

Description: In naval architecture, it is customary to determine the wetted surface of a ship by means of some formula which involves the principal dimensions of the design and suitable constants. These formulas of naval architecture may be extended and applied to the calculation of the surface area of airship envelopes by the use of new values of the constants determined for this purpose. Surface area coefficients were calculated from the actual dimensions, surfaces, and volumes of 52 streamline bodies, which form a series covering the entire range of shapes used in the present aeronautical practice.
Date: February 1, 1922
Creator: Diehl, W S
Partner: UNT Libraries Government Documents Department

Tests of oil scraper piston ring and piston fitted with oil drain holes

Description: Tests were conducted to determine whether or not a properly located and properly designed oil scraper piston ring, installed on a piston provided with oil drain holes of sufficient area, would prevent the excessive oiling of the Liberty engine, particularly with the engine running at idling speed with full oil pressure. Results showed that excessive oiling was in fact prevented. It is strongly recommended that scraper rings and pistons be adopted for aircraft engines.
Date: August 1, 1922
Creator: Mcdewell, H S
Partner: UNT Libraries Government Documents Department

Air force and three moments for F-5-L Seaplane

Description: A model of the F-5-L seaplane was made, verified, and tested at 40 miles an hour in the 8' x 8' tunnel for lift and drag, also for pitching, yawing and rolling moments. Subsequently, the yawing moment test was repeated with a modified fin. The results are reported without VL scale correction.
Date: February 1922
Partner: UNT Libraries Government Documents Department

Hydrostatic tests of an airship model

Description: An airship model made by the Goodyear Rubber Company was filled with water and suspended from a beam. The deformations of the envelope were studied under the following conditions: 1) both ballonets empty; 2) forward ballonets filled with air; 3) rear ballonets filled with air; and 4) both ballonets filled with air. Photographs were taken to record the deflections under each of these conditions, and a study was made to determine the minimum head of water necessary to maintain the longitudinal axis of the envelope under these conditions. It was concluded that any pressure sufficient to keep the airship full may be used. It appears that a pressure of one inch of water would provide a suitable factor of safety, and therefore it is the pressure that is recommended.
Date: March 1, 1922
Partner: UNT Libraries Government Documents Department

The effect on rudder control of slip stream body, and ground interference

Description: This investigation was undertaken to determine the relative effects of those factors which may interfere with the rudder control of an airplane, with especial reference to the process of landing. It shows that ground interference is negligible, but that the effects of a large rounded body and of the slip stream may combine to interfere seriously with rudder control at low flying speeds and when taxiing.
Date: September 1, 1922
Creator: Hood, H I & Bacon, D L
Partner: UNT Libraries Government Documents Department

Notes on the standard atmosphere

Description: This report contains the derivation of a series of relations between temperature, pressure, density, and altitude in a standard atmosphere which assumes a uniform decrease of temperature with altitude.
Date: June 1, 1922
Creator: Diehl, Walter S
Partner: UNT Libraries Government Documents Department

Notes on the design of latticed columns subject to lateral loads

Description: No rational column formula has yet been developed which gives results which are sufficiently precise for the design of airplane members, and consequently it is necessary to fall back upon experimental testing. In order to derive the maximum benefit from experiments, however, it is necessary that the experiments be guided by theory. It is the object here to modify existing formulae that may be obtained with a minimum number of tests. A discussion is given that is limited to the case of a simple column supported at both ends and subjected to uniformly distributed loads perpendicular to its axis and to end loads either axially or eccentrically applied. Discussed here are forces in the bracing of latticed columns, the application of theory to practical columns, loads in lattice members, and the strength of individual lattices.
Date: May 1, 1922
Creator: Mccarthy, Charles J
Partner: UNT Libraries Government Documents Department

The synchronization of NACA flight records

Description: A method is described for synchronizing the different instrument records taken during flight testing. This method has been in use for sometime at the Langley Memorial Aeronautical Laboratory and has proved very valuable in connection with the study of controllability and other complicated problems of flight.
Date: October 1, 1922
Creator: Brown, W G
Partner: UNT Libraries Government Documents Department

Comparative performance with direct and geared engines

Description: Comprehensive tests were made to compare the performance of the F-5-L Boat Seaplane fitted with direct drive and Liberty engines. Details are given on the test conditions. The conclusions of the comparison tests follow. 1) An F-5-L with geared engines takes off in approximately 90 percent of the time required for the same airplane with standard direct drive engines. An F-5-L with geared engines climbs in 20 minutes to an altitude approximately 20 percent greater than that obtained with the standard direct drive on the same airplane. 3) There is a large difference between the climbs of the two airplanes of the same type. This difference will always be more pronounced when the climb is normally slow. In the case of the F-5-L airplanes under construction, it is of the order of a 10 percent difference in altitude on a 20 minute climb. 4) The maximum speed of an F-5-L with geared engines is about 3.5 percent greater than the maximum speed of the same airplane with standard direct drive engines (at the same engine r.p.m.). 5) The fuel consumption is probably less effected by the type of drive than by inherent differences in the performance of different airplanes.
Date: October 1, 1922
Creator: Diehl, W S
Partner: UNT Libraries Government Documents Department

Impact tests for woods

Description: Although it is well known that the strength of wood depends greatly upon the time the wood is under the load, little consideration has been given to this fact in testing materials for airplanes. Here, results are given of impact tests on clear, straight grained spruce. Transverse tests were conducted for comparison. Both Izod and Charpy impact tests were conducted. Results are given primarily in tabular and graphical form.
Date: February 1922
Partner: UNT Libraries Government Documents Department

The dead weight of the airship and the number of passengers that can be carried

Description: In order to determine an approximate formula giving the weight of a dead load as a function of the volume (V) of the envelope and of the maximum velocity (v), we will take the relative weight of the various parts of the airship (P(sub v), M, V, A, T(sup 34)), adopting a mean value of the coefficients determined. This formula may be adopted both for semi-rigid airships with suspended nacelle and non-rigid envelope, with or without internal suspensions. It may also be adapted to airships with rigid longitudinal beam, with power units on external supports or in nacelles, and with non-rigid envelopes, with or without internal bracing cables.
Date: January 1, 1922
Creator: CROCCO
Partner: UNT Libraries Government Documents Department

Effect of aerofoil aspect ratio on the slope of the lift curve

Description: On of the most important characteristics of an airfoil is the rate of change of lift with angle of attack, (sup dC)L/d alpha. This factor determines the effectiveness of a tail plane in securing static longitudinal stability. The application of the Gottingen formulas given here for calculating the variation of (sup Dc)L/d alpha with aspect ratio should be of interest to many aeronautical engineers. For the convenience of the engineer, a set of curves calculated by the method set forth here are given in graphical form. Also, the observed values of (sup dC)L/d alpha for the same airfoil at various aspect ratios follow the calculated curves closely.
Date: January 1, 1922
Creator: Diehl, Walter S
Partner: UNT Libraries Government Documents Department

The use of multiplied pressures for automatic altitude adjustments

Description: The efficient performance of an airplane requires that certain adjustments be made as the density of the air through which the airplane passes changes. The safety of the over-dimensioned aircraft engine depends upon careful manipulation of spark advance and throttle opening and a proper control of a variable pitch propeller, if the maximum performance of the supercharged engine is to be obtained. It is evident that there is a real need for satisfactory devices to make such adjustments automatically. Discussed here is a method of automatic compensation which deserves consideration in the design of such devices. Existing schemes for automatic compensation all depend upon some contrivance which functions primarily because of changes in atmospheric pressure. In these devices a leak in the supposedly tight chamber means utter failure. The elimination of this source of danger is one of the aims of the method of altitude compensation described here. The change suggested is to make the source of operation the difference between atmospheric pressure and some multiple of atmospheric pressure instead of the difference between the atmospheric pressure and that of the gas confined in a tight chamber. The design of a device based on this method of altitude compensation is given.
Date: January 1, 1922
Creator: Sparrow, Stanwood S
Partner: UNT Libraries Government Documents Department

The theory of the screw propeller

Description: Given here is a brief review of the fundamental principles of the propeller slip-stream theory and its further development through later researches, which demonstrate the connection between the propeller slip-stream theory and Frounde's so-called 'propeller blade theory.' The propeller slip-stream theory, especially in its improved form, now gives us the basis for determining the mutual influence of the parts of the blade, so that, in calculating the shape of the blade, we can get along with certain section characteristics, which have been determined once and for all. It is argued that new theories present the possibility of investigating the phenomena in the vicinity of the propeller, allowing us to calculate its action on the basis of fewer experimental values.
Date: February 1, 1922
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department