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Aerodynamic characteristics of horizontal tail surfaces
From Summary: "Collected data are presented on the aerodynamic characteristics of 17 horizontal tail surfaces including several with balanced elevators and two with end plates. Curves are given for coefficients of normal force, drag, and elevator hinge moment. A limited analysis of the results has been made. The normal-force coefficients are in better agreement with the lifting-surface theory of Prandtl and Blenk for airfoils of low aspect ratio than with the usual lifting-line theory. Only partial agreement exists between the elevator hinge-moment coefficients and those predicted by Glauert's thin-airfoil theory."
Aerodynamic heating and the deflection of drops by an obstacle in an air stream in relation to aircraft icing
From Summary: "Two topics of interest to persons attempting to apply the heat method of preventing ice formation on aircraft are considered. Surfaces moving through air at high speed are shown, both theoretically and experimentally, to be subject to important aerodynamic heating effects that will materially reduce the heat required to prevent ice. Numerical calculations of the path of water drops in an air stream around a circular cylinder are given. From these calculations, information is obtained on the percentage of the swept area cleared of drops."
Aerodynamics of rotating-wing aircraft with blade-pitch control
From Introduction: "In the present report, with the aid of the usual computation methods, a rotor is investigated the pitch of whose blades is capable of being controlled in such a manner that it varies linearly with the flapping angle. To test the effect of this linkage on the aircraft performance, the theory is applied to an illustrative example."
The aileron as an aid to recovery from the spin
From Introduction: "In order to afford a means of comparison and to obtain a clear understanding of the results, a study of the effects of normal angular deflections of the ailerons, with and against the spin, was included in the investigation. Ailerons deflected with the spin means that the ailerons are deflected with right aileron up and left aileron down in a right spin. The results of the investigation are discussed in this paper."
Alfalfa varieties in the United States.
Describes the different types of alfalfa grown in the United States.
Analysis of cylinder-pressure-indicator diagrams showing effects of mixture strength and spark timing
An investigation was made to determine the effect of mixture strength and of normal as well as optimum spark timing on the combustion, on the cylinder temperature, and on the performance characteristics of an engine. A single-cylinder test unit utilizing an air-cooled cylinder and a carburetor and operating with gasoline having an octane rating of 92 was used. The investigation covered a range of fuel-air ratios from 0.053 to 0.118. Indicator diagrams and engine-performance data were taken for each change in engine conditions. Examination of the indicator shows that for fuel-air ratios less than and greater than 0.082 the rate and the amount of effective fuel burned decreased. For a fuel-air ratio of 0.118 the combustion efficiency was only 58 percent. Advancing the spark timing increased the rate of pressure rise. This effect was more pronounced with leaner mixtures.
An analysis of the stability of an airplane with free controls
Report presents the results of an investigation made of the essentials to the stability of an airplane with free control surfaces.
Analysis of wind-tunnel data on directional stability and control
From Summary: "This paper does not attempt to establish criterions for directional stability and control; rather, the emphasis is placed on providing some basis for design to specified criterions. An example applying the design methods has been included."
Annual report of the National Advisory Committee for Aeronautics (25th).administrative report including Technical Report nos. 645 to 680
Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, summaries of the committee's activities and research accomplished, bibliographies, and financial report.
Apple blotch.
Describes the disease of apple blotch, how it spreads, and ways to control it.
Apple growing east of the Mississippi River.
Describes the various factors that should be taken into consideration when developing and maintaining apple orchards, including: types of soil, climate conditions, the selecting and handling of young trees, the use of fertilizers, methods of pruning and spraying, and methods of repelling pests.
Apple-orchard renovation.
Describes various methods for maximizing the quality and output of apple orchards.
Application of the methods of gas dynamics to water flows with free surface I : flows with no energy dissipation
The application is treated in sufficient detail to facilitate as much as possible its application by the engineer who is less familiar with the subject. The present work was undertaken with two objects in view. In the first place, it is considered as a contribution to the water analogy of gas flows, and secondly, a large portion is devoted to the general theory of the two-dimensional supersonic flows.
Application of the methods of gas dynamics to water flows with free surface II : flows with momentum discontinuities (hydraulic jumps)
In this paper an introduction to shock polar diagrams is given which then leads into an examination of water depths in hydraulic jumps. Energy loss during these jumps is considered along with an extended look at elementary solutions of flow. An experimental test set-up is described and the results presented.
An Approximate Method of Calculation of Relative Humidity Required to Prevent Frosting on Inside of Aircraft Pressure Cabin Windows, Special Report
This report has been prepare in response to a request for information from an aircraft company. A typical example was selected for the presentation of an approximate method of calculation of the relative humidity required to prevent frosting on the inside of a plastic window in a pressure type cabin on a high speed airplane. The results of the study are reviewed.
An Autunite Deposit in the Rosamond Hills, Kern County, California
From introduction: An autunite deposit in the SW 1/4 sec. 25, T. 10 N., R. 13 W. San Bernardino meridian, was visited by F. M. Chace on May 6 and 15, 1950. The deposit is about 100 yards west of a north-south country road and is at an altitude of approximately 2,775 feet. The autunite-bearing tuffaceous sandstone strikes N. 35-40 W. and dips 20 -25 SW. It has been traced about 40 feet along the strike at the base of the outcrop and for about 20 feet up the dip. Insufficient work was done to give an accurate idea of the size of the deposit or to determine if other autunite-bearing beds are present.
Bean growing in northern Idaho, eastern Washington, and eastern Oregon.
Describes best practices for profitable bean-growing in the northwestern United States.
Biology of the seed-corn maggot in the coastal plain of the South Atlantic states
Describes the seed-corn maggot of the south Atlantic states at different stages of life, its history, and its habits.
Black walnut for timber and nuts.
A guide to growing black walnut trees for timber, nut crops, or ornamental use.
Blackleg : its nature, cause, and prevention.
Describes blackleg, a livestock disease. Explains how to recognize, treat, and prevent it.
Discusses aspects of blueberry production in the United States from planting through harvesting and marketing, and examines different types of blueberries.
Boundary-Layer Transition on the N.A.C.A. 0012 and 23012 Airfoils in the 8-Foot High-Speed Wind Tunnel
No Description Available.
Boundary-Layer Transition on the N.A.C.A. 0012 and 23012 Airfoils in the 8-Foot High-Speed Wind Tunnel, Special Report
Determinations of boundary-layer transition on the NACA 0012 and 2301 airfoils were made in the 8-foot high-speed wind tunnel over a range of Reynolds Numbers from 1,600,000 to 16,800,000. The results are of particular significance as compared with flight tests and tests in wind tunnels of appreciable turbulence because of the extremely low turbulence in the high-speed tunnel. A comparison of the results obtained on NACA 0012 airfoils of 2-foot and 5-foot chord at the same Reynolds Number permitted an evaluation of the effect of compressibility on transition. The local skin friction along the surface of the NACA 0012 airfoil was measured at a Reynolds Number of 10,000,000. For all the lift coefficient at which tests were made, transition occurred in the region of estimated laminar separation at the low Reynolds Numbers and approach the point of minimum static pressure as a forward limit at the high Reynolds Numbers. The effect of compressibility on transition was slight. None of the usual parameters describing the local conditions in the boundary layer near the transition point served as an index for locating the transition point. As a consequence of the lower turbulence in the 8-foot high-speed tunnel, the transition points occurred consistently farther back along the chord than those measured in the NACA full-scale tunnel. An empirical relation for estimating the location of the transition point for conventional airfoils on the basis of static-pressure distribution and Reynolds Number is presented.
Breaking and training colts.
Describes methods training horses for farm use. Includes training or control methods for driving, riding, shoeing, and throwing.
Buckling tests with a spar-rib grill
The present report deals with a comparison of mathematically and experimentally defined buckling loads of a spar-rib grill, on the assumption of constant spar section, and infinitely closely spaced ribs with rigidity symmetrical to the grill center. The loads are applied as equal bending moments at both spar ends, as compression in the line connecting the joints, and in the spar center line as the assumedly uniformly distributed spar weight.
Business records for poultry keepers.
Describes business methods to help poultry keepers with their production and marketing issues, discusses record-keeping methods, and includes suggestions to improve efficiency of a farmer's poultry business.
The calculated effect of various hydrodynamic and aerodynamic factors on the take-off of a large flying boat
Report presents the results of an investigation made to determine the influence of various factors on the take-off performance of a hypothetical large flying boat by means of take-off calculations. The factors varied in the calculations were size of hull (load coefficient), wing setting, trim, deflection of flap, wing loading, aspect ratio, and parasite drag. The take-off times and distances were calculated to the stalling speeds and the performance above these speeds was separately studied to determine piloting technique for optimum take-off.
Care and management of farm work horses.
Describes how to successfully manage and care for work horses on the farm to maximize serviceability and profitability.
Care and repair of mowers and binders.
A guide to repairing and maintaining farm mowers and binders.
Cattle-Fever Ticks and Methods of Eradication
Revised edition. This bulletin discusses the cattle-fever tick and methods for controlling it. Possible methods include dipping, pasture rotation, and arsenical dips. The life history of the tick is also discussed and instructions for constructing a concrete vat are given.
The cause of welding cracks in aircraft steels
The discussion in this article refers to gas welding of thin-walled parts of up to about 3 mm thickness. It was proven that by restricting the sulphur, carbon, and phosphorous content, and by electric-furnace production of the steel, it was possible in a short time to remove this defect. Weld hardness - i.e., martensite formation and hardness of the overheated zone - has no connection with the tendency to weld-crack development. Si, Cr, Mo, or V content has no appreciable effect, while increased manganese content tends to reduce the crack susceptibility.
Celery growing.
A guide to commercial celery-growing, with brief instructions for growing celery in home gardens. Includes descriptions of celery diseases and insect pests.
Chart for critical compressive stress of flat rectangular plates
No Description Available.
Chordwise load distribution of a simple rectangular wing
The chordwise distribution theory was taken over from the theory of the infinite wing. Since in this work a series expansion in b/t was used, the computation converges only for large aspect ratios. In this paper a useful approximate solution will be found also for wings with large chord - i.e., small aspect ratio.
Clothes moths.
Describes the life cycle and characteristics of clothes moths, and methods for their control.
Coal-Mine Accidents in the United States, 1937
Report compiled by the U.S. Bureau of Mines including statistics on fatal and non-fatal accidents in coal mines located in the United States as well as data regarding the various operations (e.g., number of miners employed and average production). The information is organized into tables for comparison and the text draws some overall conclusions in the summary.
Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report
Adjustable cowling flaps, an adjustable-length cowling skirt, and a bottom opening with adjustable flap were tested as means of controlling the rate of cooling-air flow through an air-cooled radial-engine cowling. The devices were tested in the NACA 20-foot tunnel on a model wing-nacelle-propeller combination, through an airspeed range of 20 to 80 miles per hour, and with the propeller blade angle set 23 degrees at 0.75 of the tip radius. The resistance of the engine to air flow through the cowling was simulated by a perforated plate. The results indicated that the adjustable cowling flap and the bottom opening with adjustable flap were about equally effective on the basis of pressure drop obtainable and that both were more effective means of increasing the pressure drop through the cowling than the adjustable-length skirt. At conditions of equal cooling-air flow, the net efficiency obtained with the adjustable cowling flaps and the adjustable-length cowling skirt was about 1% greater than the net efficiency obtained with the bottom opening with adjustable flap.
Consideration of auxiliary jet propulsion for assisting take-off
Report presenting an analysis and simple method to help solve the problem of assisting the take-off of an airplane by means of auxiliary jet propulsion by determining the jet thrust and weight of jet fuel required to provide a desired reduction in take-off distance or increase in pay load or fuel load for a fixed take-off distance. The use of previous experimental work to verify the analysis is also provided.
Constant-pressure blowers
The conventional axial blowers operate on the high-pressure principle. One drawback of this type of blower is the relatively low pressure head, which one attempts to overcome with axial blowers producing very high pressure at a given circumferential speed. The Schicht constant-pressure blower affords pressure ratios considerably higher than those of axial blowers of conventional design with approximately the same efficiency.
Construction of chimneys and fireplaces.
Describes the principles of chimney and fireplace construction. Provides schematics.
Corn culture.
A general guide to growing corn crops in the United States, including selection, land preparation, planting, culture, and insect and disease control.
Corrections on the thermometer reading in an air stream
A method is described for checking a correction formula, based partly on theoretical considerations, for adiabatic compression and friction in flight tests and determining the value of the constant. It is necessary to apply a threefold correction to each thermometer reading. They are a correction for adiabatic compression, friction and for time lag.
Correlation Index to Aid in Interpreting Crude-Oil Analyses
Report issued by the Bureau of Mines discussing the correlation index used for analyses of crude oils. The correlation index is presented and described in detail. This report includes tables, and illustrations.
Correlation of cooling data from an air-cooled cylinder and several multicylinder engines
The theory of engine-cylinder cooling developed in a previous report was further substantiated by data obtained on a cylinder from a Wright r-1820-g engine. Equations are presented for the average head and barrel temperatures of this cylinder as functions of the engine and the cooling conditions. These equations are utilized to calculate the variation in cylinder temperature with altitude for level flight and climb. A method is presented for correlating average head and barrel temperatures and temperatures at individual points on the head and the barrel obtained on the test stand and in flight. The method is applied to the correlation and the comparison of data obtained on a number of service engines. Data are presented showing the variation of cylinder temperature with time when the power and the cooling pressure drop are suddenly changed.
Correlation of knocking characteristics of fuels in an engine having a hemispherical combustion chamber
From Summary: "Data are presented to show the effects of inlet-air pressure, inlet-air temperature, and compression ratio on the maximum permissible performance obtained with having a hemispherical-dome combustion chamber. The five aircraft-engine fuels used have octane numbers varying from 90 to 100 plus 2 ml of tetraethyl lead per gallon. The data were obtained on a 5 1/4-inch by 4 3/4-inch liquid-cooled engine operating at 2,500 r.p.m. The compression ratio was varied from 6.0 to 8.9. The inlet-air temperature was varied from 110 to 310 F. For each set of conditions, the inlet-air pressure was increased until audible knock occurred and then reduced 2 inches of mercury before data were recorded."
No Description Available.
Cottonseed treatment.
Describes the methods of treating cottonseed to prevent disease or decay.
Creep strength of stabilized wrought-aluminum alloys
Rohn-type equipment has been mounted on rubber blocks, for the purpose of damping the vibrations of the ground and of rendering the plastic yielding of the test bars less subject to outside interferences. New equipment also included three shockproof creep-testing machines with the Martens mirror instruments for recording the strain curve of the fatigue-tested specimens.
Cyclic stress-strain studies of metals in torsion
Report presenting cyclic torsion tests made to determine the effects of varying amounts of torsional overstrain on the shape of the shearing stress-strain diagrams of aluminum alloy 17ST, mild steel, wrought iron, copper, brass, and magnesium alloy AX57S. Results regarding the tensile, compressive, and shear properties are provided.
Damping formulas and experimental values of damping in flutter models
The problem of determining values of structural damping for use in flutter calculations is discussed. The concept of equivalent viscous damping is reviewed and its relation to the structural damping coefficient g introduced in NACA Technical Report No. 685 is shown. The theory of normal modes is reviewed and a number of methods are described for separating the motions associated with different modes. Equations are developed for use in evaluating the damping parameters from experimental data. Experimental results of measurements of damping in several flutter models are presented.