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Wind-Tunnel Research Comparing Lateral Control Devices, Particularly at High Angles of Attack 1: Ordinary Ailerons on Rectangular Wings
"This report is the first in a series in which it is intended to compare the relative merits of all ordinary and some special forms of ailerons and other lateral control devices in regard to their effect on lateral controllability, lateral stability, and airplane performance. The comparisons are based on wind-tunnel test data, all the control devices being fitted to model wings having the same span, area, and airfoil section, and being subjected to the same series of force and rotation tests. The results are given for five different aileron movements: one with equal up-and-down deflection, one with average and one with extreme differential motion, one with upward deflection only, and one with the ailerons arranged to float with respect to the wing" (p. 357).
Coal-Mine Fatalities in November, 1930
Report issued by the U.S. Bureau of Mines on the fatalities of coal miners in November, 1930. The common causes of death, and the location of the mines that the fatalities occurred in are listed. This report includes tables.
Development of a Non-Autorotative Airplane Capable of Steep Landing
In the following we develop a non-autorotating monoplane wing. The conditions imposed on such a wing, aside from its freedom from autorotation,with respect to its polars and its construction, are taken into account as far as possible. It is indicated that the autorotation characteristics of a wing are dependent upon the speed of air flow as well as on the angle of yaw. This report postulates the knowledge of the behavior of certain conventional wings of different chords and cambers with respect to their air loads at large angles of attack.
The effectiveness of a double-stem injection valve in controlling combustion in a compression-ignition engine
An investigation was made to determine to what extent the rates of combustion in a compression-ignition engine can be controlled by varying the rates of fuel injection. The tests showed that the double-stem valve operated satisfactorily under all normal injection conditions; the rate of injection has a definite effect on the rate of combustion; the engine performance with the double-stem valve was inferior to that obtained with a single-stem valve; and the control of injection rates permitted by an injection valve of two stages of discharge is not sufficient to effect the desired rates of combustion.
Factors Influencing Flow of Natural Gas Through High-Pressure Transmission Lines
Report issued by the U.S. Bureau of Mines on the effects of different operating conditions on high-pressure natural gas pipelines. Analysis of past and current studies on natural gas transmission are presented. This report includes tables, graphs, and an illustration.
Goldstein's Solution of the Problem of the Aircraft Propeller With a Finite Number of Blades
This report examines the Betz theory on frictionless, lightly loaded propellers and Prandtl's addendum extended to moderately loaded propellers. The author then goes on to extend the discussion to Goldstein's solution for propellers with a finite number of blades.
The interference effects on an airfoil of a flat plate at mid-span position
"This report gives the results of an investigation of the mutual interference of an airfoil and a flat plate inserted at mid-span position. The tests were conducted in the Variable-Density Wind Tunnel of the National Advisory Committee for Aeronautics at a high value of the Reynolds Number. The interference effects of this combination were found to be small. Supplementary tests indicated that the use of fillets decreases both the lift and drag slightly. A bibliography of publication dealing with interference between wings and bodies, and with the effects of cut-outs and fillets is included" (p. 1).
Liquid Cooling of Aircraft Engines
This report presents a method for solving the problem of liquid cooling at high temperatures, which is an intermediate method between water and air cooling, by experiments on a test-stand and on an airplane. A utilizable cooling medium was found in ethylene glycol, which has only one disadvantage, namely, that of combustibility. The danger, however is very slight. It has one decided advantage, that it simultaneously serves as protection against freezing.
Mammals of New Mexico
Summary of the species of mammals native to New Mexico, including a map of the life zones, descriptions of the physiographic features, and lists of characteristic zone-marking plants, birds, mammals.
Method of Determining the Weights of the Most Important Simple Girders
"This paper presents a series of tables for the simple and more common types of girders, similar to the tables given in handbooks under the heading "Strength of Materials," for determining the moments, deflections, etc., of simple beams. Instead of the uniform cross section there assumed, the formulas given here apply only to girders of "uniform strength," i.e., it is assumed that a girder is so dimensioned that a given load subjects it to a uniform stress throughout its whole length. This principle is particularly applicable to very strong structures" (p. 1).
The Supermarine S.6.B. Racing Seaplane (British): A Low-Wing Twin-Float Monoplane
Circular presenting a description of the Supermarine S.6.B. racing seaplane, which was the winner of a seaplane contest. Information regarding the oil system, water system, fuel system, floats, and controls are provided.
Tests of N.A.C.A. airfoils in the variable density wind tunnel Series 44 and 64
This note is one of a series covering an investigation of a number of related airfoils. It presents the results obtained from tests in the N.A.C.A. Variable Density Wind Tunnel of two groups of six airfoils each. One group, the 44 series, has a maximum mean camber of 4 percent of the chord at a position 0.4 of the chord behind the leading edge and the other group, the 64 series, has a maximum mean camber of 6 percent of the chord at the same position. The members within each group differ only in maximum thickness, the maximum thickness/chord ratios being: 0.06, 0.09, 0.12, 0.15, 0.18, and 0.21. The results are analyzed with a view to indicating the variation of the aerodynamic characteristics with profile thickness for airfoils having a certain mean camber line form.
Wind Tunnel of the Bucharest Polytechnic Institute
This report describes the Bucharest wind tunnel and presents numerous photographs and diagrams. The wind tunnel is of the closed- circuit type, the return being symmetrical with respect t o the longitudinal axis of the tunnel. Th e tunnel is of the horizontal type with a diameter of 3. 2 m (10. 5-ft.) a t the beginning of the entrance cone, and 1.5 m ( 4,92 ft.) at the entrance to the test chamber. The latter, 2 m (6.56 ft.) long, may be either of the open-jet type or enclosed in a cylindrical housing.
The effect on airplane performance of the factors that must be considered in applying low-drag cowling to radial engines
From Summary: "This report presents the results of flight tests with three different airplanes using several types of low-drag cowling for radial air-cooled engines. The greater part of the tests were made with a Curtiss XF7Cc-1 (Sea Hawk) with a 410 horsepower. Wasp engine, using three fuselage nose shapes and six types of outer cowling. The six cowlings were: a narrow ring, a wide ring, a wide cowling similar in the original NACA cowling, a thick ring incorporating an exhaust collector, a single-surface cowling shaped like the outer surface of the exhaust-collector cowling, and polygon-ring cowling, of which the angle of the straight sections with the thrust line could be varied over a wide range."
Tests of nacelle-propeller combinations in various positions with reference to wings. Part I : thick wing-N.A.C.A. cowled nacelle-tractor propeller
This report gives the results in the 20-foot propeller research tunnel of the National Advisory Committee for Aeronautics on the interference drag and propulsive efficiency of a nacelle-propeller combination located in 21 positions with reference to a thick wing. The lift, drag, and propulsive efficiency were obtained at several angles of attack for each of the 21 locations. A net efficiency was derived for determining the over-all effectiveness of each nacelle location. Best results were obtained with the propeller about 25 per cent of the chord directly ahead of the leading edge. A location immediately above or below the wing near the leading edge was very poor.
Zinc and its alloys
A report on zinc and its alloys.
Zinc and Its Alloys
Report issued by the Bureau of Standards discussing world production of zinc and zinc alloys. History, metallurgy, and structural properties of zinc are presented. This report includes tables, illustrations, and photographs.
Accident Experience and Cost of Accidents in Washington Coal Mines
Report containing tables detailing cost of mining accidents in Washington state in comparison with other states.
Advantages of Oxide Films as Bases for Aluminum Pigmented Surface Coatings for Aluminum Alloys
Report discussing both laboratory and weather-exposure corrosion tests showed conclusively that the protection afforded by aluminum pigmented spar varnish coatings applied to previously anodized aluminum surfaces was greatly superior to that afforded by the same coatings applied to surfaces which had simply been cleaned free from grease and not anodized.
The aerodynamic characteristics of six commonly used Airfoils over a large range of positive and negative angles of attack
From Summary: "This paper presents the results of tests of six commonly used airfoils: the CYH, the N-22, the C-72, the Boeing 106, and the Gottingen 398. The lifts, drags, and pitching moments of the airfoils were measured through a large range of positive and negative angles of attack. The tests were made in the variable density wind tunnel of the National Advisory Committee for Aeronautics at a large Boeing 106, and the Gottingen 398 airfoils, the negative maximum lift coefficients were found to be approximately half the positive; but for the M-6 and the CYH, which have less effective values were, respectively, 0.8 and 0.6 of the positive values."
The effect of slots and flaps on the lift and drag of the McDonnell Airplanes determined in flight
This note contains the results of flight test conducted by the National Advisory Committee for Aeronautics on a low-wing monoplane equipped with leading-edge slots extending over the entire wing and flaps extending only to the ailerons, to find their effect on the lift and drag characteristics of the airplane. Curves are given showing the lift and drag characteristics of the airplane for the following conditions of the slots and flaps neutral; slots closed and flaps down; and slots open and flaps down. In addition, the high and low speed in level flight and the climbing characteristics are given. The results show that the slots used alone increase the maximum lift coefficient 54 per cent; the flaps alone increase it 38 per cent; and the slots and flaps in combination decrease the landing speed from 60 to 43 m.p.h.; increase the speed range of the airplane 40 per cent; and increase the glide angle at landing speed 4.2 degrees.
The Guilleman J.G. 10 (French) : A Two-Place Touring Low-Wing Monoplane
Circular describing the Guillemin J.G. 10, which is a two-place touring low-wing monoplane. Details of the wing, fuselage, engine, characteristics, drawings, and photographs are provided.
Measurement of Visibility From the Pilot's Cockpit on Different Airplane Types
A process for the measurement of the visibility of airplanes from the pilot's cockpit is developed. The apparatus necessary for the measurements was suitably constructed and measurements of the fields of vision were made with it. The visibilities of six airplanes of different types of construction and use were measured, as well as the visibility of an automobile for comparison. An attempt was made to establish minimum visibility requirements and to express the excellence of visibility by means of a numerical coefficient.
Measurements of Vertical Air Currents in the Atmosphere
To summarize, the experiments with balloons, sailplanes and light airplanes conducted thus far, reveal the vertical velocities of the air to be primarily dependent on the vertical temperature distribution. Stable stratifications result in up-and-down currents forced by the contour of the ground, which are readily recognized in flight and, if need be, may be avoided.
Relations Between Ship Design and Seaplane Design
This report examines various aspects of seaplane construction; namely, stability, propulsion, water-tight bulkheads, fire protection, and construction.
Some characteristics of fuel sprays at low-injection pressures
"This report presents the results of tests conducted at the Langley Memorial Aeronautical Laboratory, Langley Field, Va., to determine some of the characteristics of the fuel sprays obtained from an 0.008-inch and a 0.020-inch open nozzle when injection pressures from 100 to 500 pounds per square inch were used. Fuel oil and gasoline were injected into air at densities of atmospheric land 0.325 pound per cubic foot. It was found that the penetration rate at these low pressures was about the same as the rate obtained with higher pressures. Spray cone-angles were small and individual oil drops were visible in all the sprays. Gasoline and fuel oil sprays had similar characteristics" (p. 1).
Spatial Buckling of Various Types of Airplane Strut Systems
Equations are presented for two and three dimensional strut systems along with tables of equations.
The 7 by 10 Foot Wind Tunnel of the National Advisory Committee for Aeronautics
This report presents a description of the 7 by 10 foot wind tunnel and associated apparatus of the National Advisory Committee for Aeronautics. Included also are calibration test results and characteristic test data of both static force tests and autorotation tests made in the tunnel.
Pressure distribution tests on a series of Clark Y biplane cellules with special reference to stability
"The pressure distribution data discussed in this report represents the results of part of an investigation conducted on the factors affecting the aerodynamic safety of airplanes. The present tests were made on semispan, circular-tipped Clark Y airfoil models mounted in the conventional manner on a separation plane. Pressure readings were made simultaneously at all test orifices at each of 20 angles of attack between -8 degrees and +90 degrees. The results of the tests on each wing arrangement are compared on the bases of maximum normal force coefficient, lateral stability at a low rate of roll, and relative longitudinal stability. Tabular data are also presented giving the center of pressure location of each wing" (p. 315).
The Elimination of Fire Hazard Due to Back Fires
"A critical study was made of the operation of a type of back-fire arrester used to reduce the fire hazard of aircraft engines. A flame arrester consisting of a pack or plug of alternate flat and corrugated plates of thin metal was installed in the intake pipe of a gasoline engines; an auxiliary spark plug inserted in the intake manifold permitted the production of artificial back fires at will. It was found possible to design a plug which prevented all back fires from reaching the carburetor" (p. 211).
The Theory of Wind-Tunnel Wall Interference
This report outlines the development of a general theory for the calculation of the effect of the boundaries of the air stream on the flow past an airfoil. Analytical treatments are given for tunnels with horizontal boundaries only, with vertical boundaries only, and with a bottom boundary only. Formulas are developed for the tunnel wall interference in each case for an airfoil located at the center of the tunnel. The correction is given as a function of the width to height ratio of the tunnel.
Flutter in Propeller Blades
This report considers two different explanations for propeller breaks caused by propeller flutter. The two possibilities are combined vibrations of the blade, similar to those of the wings, which develop by absorbing energy from the air stream and converting it into vibrations without the aid of any periodic external disturbance. The other possibility examined is forced vibrations, which are produced in every structure by periodically variable impulses. Such vibrations are especially dangerous when the disturbing impulses which cause them have a frequency equal to the natural frequency of the system.
Laboratory Testing of the Inflammability of Coal and other Dusts Conducted by the Bureau of Mines
From Introduction: "This paper endeavors to collect and describe all of the work in proper order, as briefly as is consistent with a good understanding thereof, and attempts to evaluate it in the light of present-day knowledge derived from large and small scale experiments in the United States and foreign countries."
Lift Distribution and Longitudinal Stability of an Airplane
The preliminary calculation of the airplane polar and hence of the flight performances and characteristics rests on the assumption of an elliptical lift distribution at all altitudes. For large angles of attack below C(sub a (sub max)), this method of calculation yields no satisfactory agreement with measurements made in flight. An attempt is made to eliminate the errors in the preliminary calculation by the assumption of a disturbance of the lift distribution in this angle-of-attack range, which is so important for the constructor. An explanation is also given of the great differences found in flight with and without propeller slipstream.
Load Assumptions for the Landing Impact of Seaplanes
The formula for the impact of floats must include the enlargement factor itself as well as the type of enlargement. The latter is preferably characterized by the change in surface loading. It is shown that the enlargement of a small seaplane generally results in a changed float (or boat) loading as well as wing loading. The conditions of starting stipulate the retention of the float loading when changing from single-float (boat) to twin-float arrangement. This contingency is followed by an increased impact factor in the twin-float type against the otherwise equivalent single-float type.
The New "Charlestop" Remote Brake Transmission and Control
This report presents a description, diagrams and photographs of the Charlestop remote brake system. A description of the brake system and diagrams showing the individual components are provided.
On Atomization in Carburetors
The outstanding quantity of the whole atomization problem is the characteristic K, and therefore the ratio of the static pressure of the air stream with respect to the liquid to the surface tension of the liquid. The higher its value, the better the atomization. The shape of the Venturi tube plays a secondary role. The increase of section beyond the throat had best not be too abrupt.
Penetration and Duration of Fuel Sprays From a Pump Injection System
"High-speed motion pictures were taken of individual fuel sprays from a pump injection system. The changes in the spray-tip penetration with changes in the pump speed, injection-valve opening and closing pressures, discharge-orifice area, injection-tube length and diameter, and pump throttle setting were measured. In addition, the effects of the variables on the time lag and duration of injection can be controlled by the dimensions of the injection tube, the area of the discharge orifice, and the injection-valve opening and closing pressures" (p. 1).
Performance of a compression-ignition engine with a precombustion chamber having high-velocity air flow
Presented here are the results of performance tests made with a single-cylinder, four stroke cycle, compression-ignition engine. These tests were made on a precombustion chamber type of cylinder head designed to have air velocity and tangential air flow in both the chamber and cylinder. The performance was investigated for variable load and engine speed, type of fuel spray, valve opening pressure, injection period and, for the spherical chamber, position of the injection spray relative to the air flow. The pressure variations between the pear-shaped precombustion chamber and the cylinder for motoring and full load conditions were determined with a Farnboro electric indicator. The combustion chamber designs tested gave good mixing of a single compact fuel spray with the air, but did not control the ensuing combustion sufficiently. Relative to each other, the velocity of air flow was too high, the spray dispersion by injection too great, and the metering effect of the cylinder head passage insufficient. The correct relation of these factors is of the utmost importance for engine performance.
The prevention of ice formation on gasoline tank vents
"This investigation was conducted in the refrigerated wind tunnel at the Langley Memorial Aeronautical Laboratory, Langley Field, Va., to determine a suitable method for preventing the formation of ice on the vents of airplane gasoline tanks. Tests were made on a variety of vent forms arranged in a number of different orientations relative to the direction of the air stream. Both the size of the tube and its orientation were found to be of great importance. Small tubes, under equal circumstances, were found to freeze over far more rapidly than large ones" (p. 1).
Breguet Military Airplane, Type 33: A Two-Place Long-Distance Sesquiplane for Observation and Bombing
Circular presenting a description of the Breguet military airplane, Type 33, which is a two-place long-distance sesquiplane made for observation and bombing. Details of the components, bomb dropping, flying qualities, design, flying qualities and performances, drawings, and photographs are provided.
The Dangerous Sideslip of a Stalled Airplane and Its Prevention
This investigation covers only that phase of airplane accidents which are the result of sideslip. We examine the circumstances under which this occurs, study the behavior of present-day airplane types (monoplane, conventional and staggered biplane) therein and endeavor to find a solution whereby this danger may be avoided.
The development, design and construction of gliders and sailplanes
This report explains and details the history of glider design and construction through the impetus of the Rhon Sailplane contests. Some of the topics considered include: whether the longitudinal stability (dynamic and static) is sufficient in the tailless typo and a consideration that the structural weight of sweptback wings would be greater than that of a corresponding normal wing.
Experiments With Airplane Brakes
This report begins by examining the forces on the brake shoes. For the determination of the load distribution over the shoes it was assumed that the brake linings follow Hooke's law, are neatly fitted and bedded in by wear. The assumption of Hooke's law, that is, the proportionality between compression of the lining and the absorption of force, is fulfilled to a certain extent for the loading, as becomes apparent from the load tests described further on. But there is a material discrepancy at unloading.
An Investigation of Cotton for Parachute Cloth
"This is a resume of the work of the Bureau of Standards on a cotton parachute cloth for use as a substitute for silk in the event of an emergency curtailing the supply. Cotton yarn of high strength in proportion to its weight and otherwise specially suitable for parachute cloth was developed. Cloth woven from this yarn in the bureau mill was equal or superior to parachute silk in strength and tear resistance, met the requirements with respect to air permeability, and weighed only a few tenths of an ounce per square yard more than the silk cloth" (p. 1).
A method for reducing the temperature of exhaust manifolds
From Summary: "This report describes tests conducted at the Langley Memorial Aeronautical Laboratory on an "air-inducting" exhaust manifold for aircraft engines. The exhaust gases from each cylinder port are discharged into the throat of an exhaust pipe which has a frontal bellmouth. Cooling air is drawn into the pipe, where it surrounds and mixes with the exhaust gases. Temperatures of the manifold shell and of the exhaust gases were obtained in flight for both a conventional manifold and the air-inducting manifold."
The N.A.C.A. Apparatus for Studying the Formation and Combustion of Fuel Sprays and the Results From Preliminary Tests
Described here is an apparatus for studying the formation and combustion of fuel sprays under conditions closely simulating those in a high speed compression-ignition engine. The apparatus consists of a single-cylinder modified test engine, a fuel injection system so designed that a single charge of fuel can be injected into the combustion chamber, an electric driving motor, and a high-speed photographic apparatus. When the fuel is injected into the combustion chamber, motion pictures at the rate of 2000 per second are taken of the spray formation by means of spark discharges.
On Floats and Float Tests
The principal source of information on float resistance is the model test. In view of the insuperable difficulties opposing any attempt at theoretical treatment of the resistance problem, particularly at attitudes which tend toward satisfactory take-off, such as the transitory stage to planing, the towing test is and will remain the primary method for some time.
Potez 37R2 Military Airplane: A Two-Place Long-Distance Observation Monoplane
Circular presenting a description of the Potez 37R2 military airplane, which is a two-place long-distance observation monoplane. Details of the design, construction, components, characteristics, drawings, and photographs are provided.
Tests of N.A.C.A. airfoils in the variable-density wind tunnel Series 43 and 63
This note is one of a series covering an investigation of a family of related airfoils. It gives in preliminary form the results obtained from tests in the N.A.C.A. Variable-Density Wind Tunnel of two groups of six airfoils each. One group, the 43 series, has a maximum mean camber of 4 per cent of the chord at a position 0.3 of the chord from the leading edge; the other group, the 63 series, has a maximum mean camber of 6 per cent of the chord at the same position. The members within each group differ only in maximum thickness, the maximum thickness/chord ratios being:0.06, 0.09, 0.12, 0.15, 0.18, and 0.21. The results are analyzed with a view to indicating the variation of the aerodynamic characteristics with profile thickness for airfoils having a certain mean camber line.
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