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The 5- by 7-meter wind tunnel of the DVL
The report contains a description of the DVL wind tunnel. According to the cones fixed, an elliptical stream with axes 5 by 7 meters and length 9 meters, or a stream 6 by 8 meters in cross section and 11 meters in length is available. The top speed with the smaller cone is 65 meters per second. The testing equipment consists of an automatic six-component balance and a test rig for propellers and engines up to 650 horsepower.
Air flow in the boundary layer near a plate
From Summary: "The published data on the distribution of speed near a thin flat plate with sharp leading edge placed parallel to the flow (skin friction plate) are reviewed and the results of some additional measurements are described. The purpose of the experiments was to study the basic phenomena of boundary-layer flow under simple conditions."
Aircraft Accidents: Methods of Analysis
This report is a revision of NACA-TR-357. It was prepared by the Committee on Aircraft Accidents. The purpose of this report is to provide a basis for the classification and comparison of aircraft accidents, both civil and military.
Altitude-pressure tables based on the United States standard atmosphere
This report is a revision of the altitude pressure tables of the United States standard atmosphere given in Technical Report No. 246 and the altitude range has been extended from 50,000 to 80,000 feet.
Analysis and Model Tests of Autogiro Jump Take-Off
From Introduction: "The possibilities of the jump take-off have been established by some full-scale experiments. It is the purpose of this paper to study the factors that govern the jump take-off in its simplest form and to present the results of model tests in which the effect of differences in the rotor parameters was determined."
An Analysis of Lateral Stability in Power-Off Flight With Charts for Use in Design
"The aerodynamic and mass factors governing lateral stability are discussed and formulas are given for their estimation. Relatively simple relationships between the governing factors and the resulting stability characteristics are presented. A series of charts is included with which approximate stability characteristics may be rapidly estimated" (p. 1).
Analysis of the Three Lowest Bending Frequencies of a Rotating Propeller
From Summary: "The present report is a survey of the existing data for computing the bending frequency and a check on the dependability of the calculating methods."
Annual Report of the National Advisory Committee for Aeronautics (21st). Administrative Report Including Technical Report Nos. 508 to 541
Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, Congressional report, summaries of the committee's activities and research accomplished, bibliographies, and financial report.
An Approximate Spin Design Criterion for Monoplanes
"An approximate empirical criterion, based on the projected side area and the mass distribution of the airplane, was formulated. The British results were analyzed and applied to American designs. A simpler design criterion, based solely on the type and the dimensions of the tail, was developed; it is useful in a rapid estimation of whether a new design is likely to comply with the minimum requirements for safety in spinning" (p. 1).
Automatic Stabilization
This report lays more stress on the principles underlying automatic piloting than on the means of applications. Mechanical details of servomotors and the mechanical release device necessary to assure instantaneous return of the controls to the pilot in case of malfunction are not included. Descriptions are provided of various commercial systems.
Automatic Stabilization
This report concerns the study of automatic stabilizers and extends it to include the control of the three-control system of the airplane instead of just altitude control. Some of the topics discussed include lateral disturbed motion, static stability, the mathematical theory of lateral motion, and large angles of incidence. Various mechanisms and stabilizers are also discussed.
The Avro "Anson" General-Purpose Airplane (British): A Two-Engine Low-Wing Cantilever Monoplane
Circular describing the Avro Anson, which is a two-engine low-wing cantilever monoplane of the general-purpose type. Details regarding the wing, landing gear, controls, fuselage, pilot's equipment, power plant, armament, characteristics, performance, drawings, and photographs are provided.
Behavior of Turbulent Boundary Layers on Curved Convex Walls
The system of linear differential equations which indicated the approach of separation and the so-called "boundary-layer thickness" by Gruschwitz is extended in this report to include the case where the friction layer is subject to centrifugal forces. Evaluation of the data yields a strong functional dependence of the momentum change and wall drag on the boundary-layer thickness radius of curvature ratio for the wall. It is further shown that the transition from laminar to turbulent flow occurs at somewhat higher Reynolds Numbers at the convex wall than at the flat plate, due to the stabilizing effect of the centrifugal forces.
Bending of Beams of Thin Sections
The tendency toward economy of material and lightness of structure has long since led to the increased application of beams having large ratios of moment of area W to cross-sectional area F. This paper tries to provide an answer to how thin the beams can be.
Blower Cooling of Finned Cylinders
"Several electrically heated finned steel cylinders enclosed in jackets were cooled by air from a blower. The effect of the air conditions and fin dimensions on the average surface heat-transfer coefficient q and the power required to force the air around the cylinders were determined. Tests were conducted at air velocities between the fins from 10 to 130 miles per hour and at specific weights of the air varying from 0.046 to 0.074 pound per cubic foot. The fin dimensions of the cylinders covered a range in pitches from 0.057 to 0.25 inch average fin thicknesses from 0.035 to 0.04 inch, and fin widths from 0.67 to 1.22 inches" (p. 269).
Boosted Performance of a Compression-Ignition Engine With a Displaced Piston
From Summary: "Performance tests were made using a rectangular displacer arranged so that the combustion air was forced through equal passages at either end of the displacer into the vertical-disk combustion chamber of a single-cylinder, four-stroke-cycle compression-ignition test engine. After making tests to determine optimum displacer height, shape, and fuel-spray arrangement, engine-performance tests were made at 1,500 and 2,000 r.p.m. for a range of boost pressures from 0 to 20 inches of mercury and for maximum cylinder pressures up to 1,150 pounds per square inch. The engine operation for boosted conditions was very smooth, there being no combustion shock even at the highest maximum cylinder pressures. Indicated mean effective pressures of 240 pounds per square inch for fuel consumptions of 0.39 pound per horsepower-hour have been readily reproduced during routine testing at 2,000 r.p.m. at a boost pressure of 20 inches of mercury."
Calculated and measured pressure distributions over the midspan section of the NACA 4412 airfoil
Pressures were simultaneously measured in the variable-density tunnel at 54 orifices distributed over the midspan section of 5 by 30 inch rectangular model of the NACA 4412 airfoil at 17 angles of attack ranging from -20 degrees to 30 degrees at a Reynolds number of approximately 3,000,000. Accurate data were thus obtained for studying the deviations of the results of potential-flow theory from measured results. The results of the analysis and a discussion of the experimental technique are presented.
Calculated Effect of Various Types of Flap on Take-Off Over Obstacles
"In order to determine whether or not flaps could be expected to have any beneficial effect on take-off performance, the distances required to take off and climb to an altitude of 50 feet were calculated for hypothetical airplanes, corresponding to relatively high-speed types and equipped with several types of flap. The types considered are the Fowler wing, the Hall wing, the split flap, the balanced split flap, the plain flap, and the external-airfoil flap. The results indicate that substantial reductions in take-off distance are possible through the use of flaps, provided that the proper flap angle corresponding to a given set of conditions is used" (p. 1).
Carbon-monoxide indicators for aircraft
Several improvements that have been made on commercially available carbon-monoxide indicators to make them more suitable for aircraft use are described. These improvements include an automatic flow regulator, which permits the use of a simplified instrument on aircraft where a source of suction is available, and a more reliable alarm attachment. A field method for testing instruments on standard samples of carbon monoxide is described. Performance data and instructions in operation and maintenance are given.
The Cetene Scale and the Induction Period Preceding the Spontaneous Ignition of Diesel Fuels in Bombs
In the present report a comparison is made between the scale obtained with mixtures of cetane and l-methyl naphthalene in a bomb, and that obtained with the same fuels in a Waukesha engine. The tests were conducted in a metal bomb heated by a Nichrome spiral. The fuel was injected into the bomb from a Bosch jet by means of a specially constructed plunger pump. The instant injection and the pressure curve in the bomb were registered by a beam of light which was reflected from a mirror connected to the needle of the jet and to a membrane indicator.
Characteristics of six propellers including the high-speed range
This investigation is part of an extensive experimental study that has been carried out at full scale in the NACA 20-foot tunnel, the purpose of which has been to furnish information in regard to the functioning of the propeller-cowling-nacelle unit under all conditions of take-off, climbing, and normal flight. This report presents the results of tests of six propellers in the normal and high-speed flight range and also includes a study of the take-off characteristics.
Charts for Calculating the Performance of Airplanes Having Constant-Speed Propellers
"Charts are presented for determining the performance of airplanes having variable-pitch propellers, the pitch of which is assumed to be adjusted to maintain constant speed for all rates of flight. The charts are based on the general performance equations developed by Oswald in reference 1, and are used in a similar manner. Examples applying the charts to airplanes having both supercharged and unsupercharged engines are included" (p. 1).
Charts for Checking the Stability of Compression Members in Trusses
"The present report contains a set of charts developed for computing the fixity effect on a compression member in a truss through its adjacent members, the amount of fixity being considered variable with the particular total truss load. The use of the charts is illustrated on two- and three-bay systems, as well as on a triangular truss" (p. 1).
Chief Characteristics and Advantages of Tailless Airplanes
This study will be concerned with the critical examination of two main questions, mainly, susceptibility of centering and more generally, the conditions of static stability, longitudinal equilibrium, and the question of dynamic stability, or at least the damping of longitudinal vibrations about a position of equilibrium that may result from a small variation in the angle of attack.
Circular Motion of Bodies of Revolution
The circular motion for airship-like bodies has thus far been calculated only for a prolate ellipsoid of revolution (reference 1, p.133 and reference 2). In this paper, however, the circular motion of elongated bodies of revolution more nearly resembling airships will be investigated. The results will give the effect of rotation on the pressure distribution and thus yield some information as to the stresses set up in an airship in circular flight.
Combustion-engine temperatures by the sodium line-reversal method
The sodium line-reversal method has been used in some preliminary measurements of flame temperature. Improvements in the method involving a photographic recorder and a means of correcting for the dirtiness of the windows are described. The temperatures so obtained are compared with those calculated from pressure diagrams.
A Comparison of Corrosion-Resistant Steel (18 Percent Chromium - 8 Percent Nickel) and Aluminum Alloy (24st)
"In the selection of materials for aircraft application, it is not enough to make the selection on a strength-weight basis alone. A strength-weight comparison is significant but other factors must be considered, for while a material with a high ratio of strength to weight may be perfectly satisfactory for one use, it may be totally unfitted for another. It is essential, among other things, that the probable nature, magnitude, and direction of the principal stresses be given special consideration" (p. 1).
Considerations of the Take-Off Problem
Many technical papers on the various phases of airplane take-off have been published. Frequently, however, there appear new ideas which affect only particular scattered phases of the subject and which do not receive individual publication. It is the purpose of this paper to present several ideas of this nature which may be of considerable aid in calculating take-off performance and one idea which should correct what appears to be a popular misconception of the importance of static propeller thrust.
Contribution to the problem of airfoils spanning a free jet
After a brief discussion of the work done up to now on an unwarped wing of constant chord spanning a free jet, the computation of the circulation and lift distribution for different forms of warped wings spanning rectangular and circular jets was carried out. The computed values are compared with test values and the agreement is found to be good. The effect of placing the wing eccentrically is slight and may be applied as a correction factor to the data obtained for wing placed in middle of jet.
Cooling of airplane engines at low air speeds
Report presents the results of a comprehensive experimental study carried out at full scale in the NACA 20-foot wind tunnel, the general purpose of which is to furnish information in regard to the functioning of the power plant and propeller unit under different conditions. This report deals particularly with the problem of the cooling of an airplane engines on the ground. The influence of different nose forms, skirts, flaps, propellers, spinners, and special blowers has been investigated.
Cooling tests of a single-row radial engine with several NACA cowlings
The cooling of a single-row radial air-cooled engine using several cowling arrangements has been studied in the NACA 20-foot wind tunnel. The results show the effect of the propeller and several cowling arrangements on cooling for various values of the indicated horsepower in the climb condition. A table giving comparative performance of the various cowling arrangements is presented. The dependence of temperature on indicated horsepower and pressure drop across the baffles is shown by charts. Other charts show the limiting indicated horsepower against the pressure drop across the engine and the heat dissipated at various values of the indicated horsepower.
Correction of Downwash in Wind Tunnels of Circular and Elliptic Sections
The downwash velocity distribution behind the wing was determined for the free jet and for the closed tunnel of both circular and elliptic cross sections. The wing was placed at the center of the tunnel. The theory makes it possible to determine the downwash at any point in the jet. The computations were performed for points in the plane determined by the jet axis and the center-of-pressure line of the wing.
Details of the Construction and Production of Fuel Pumps and Fuel Nozzles for the Airplane Diesel Engine
This report presents investigations into the design and construction of fuel pumps for diesel engines. The results of the pump tests on the engines showed that, with a good cut-off, accurate injection, assured by the proper adjustment of the pump elements, there is a decrease in the consumption of fuel and hence an increase in the rated power of the engine. Some of the aspects investigated include: cam profile, coefficient of discharge, and characteristics of the injection system.
Effect of changes in tail arrangement upon the spinning of a low-wing monoplane model
"A series of tests was made in the N.A.C.A. free spinning tunnel to find the effect upon spinning characteristics of systematic changes in tail arrangement. The tests were made with a 1/16-scale made of a low-wing monoplane of modern design. The changes consisted of: (1) variation of the fuselage length; (2) variation of the fore-and-aft location of the vertical surfaces; and (3) variation of the vertical location of the horizontal surfaces. The spinning characteristics of the model, including the number of turns required for recovery, were found to vary systematically and regularly with systematic changes in the tail arrangement" (p. 1).
The effect of lateral controls in producing motion of an airplane as computed from wind-tunnel data
This report presents the results of an analytical study of the lateral controllability of an airplane in which both the static rolling and yawing moments supplied by the controls and the reactions due to the inherent stability of the airplane have been taken into account. The investigation was undertaken partly for the purpose of coordinating the results of a long series of wind-tunnel investigations with phenomena observed in flight tests; for this reason a hypothetical average airplane, embodying the essential characteristics of both wind-tunnel models and the full-size test airplanes, was assumed for the study.
Effect of nozzle design on fuel spray and flame formation in a high-speed compression-ignition engine
"Fuel was injected from different type of injection nozzles into the combustion chamber of the NACA combustion apparatus, operated as a compression-ignition engine. High speed motion pictures were taken of the fuel sprays and combustion. Single-orifice nozzles of 0.008, 0.020, and 0.040 inch diameter, and multiorifice nozzles having 2, 6, and 16 orifices were tested. Nozzles having impinging jets and slit orifices were also included" (p. 327).
Effect of Several Factors on the Cooling of a Radial Engine in Flight
"Flight tests of a Grumman Scout (XSF-2) airplane fitted with a Pratt & Whitney 1535 supercharged engine were conducted to determine the effect of engine power, mass flow of the cooling air, and atmospheric temperature on cylinder temperature. The tests indicated that the difference in temperature between the cylinder wall and the cooling air varied as the 0.38 power of the brake horsepower for a constant mass flow of cooling air, cooling-air temperature, engine speed, and brake fuel consumption. The difference in temperature was also found to vary inversely as the 0.39 power of the mass flow for points on the head and the 0.35 power for points on the barrel, provided that engine power, engine speed, brake fuel consumption, and cooling-air temperature were kept constant" (p. 1).
Electrical thermometers for aircraft
Electrical thermometers commonly used on aircraft are the thermoelectric type for measuring engine-cylinder temperatures, the resistance type for measuring air temperatures, and the superheat meters of thermoelectric and resistance types for use on airships. These instruments are described and their advantages and disadvantages enumerated. Methods of testing these instruments and the performance to be expected from each are discussed. The field testing of engine-cylinder thermometers is treated in detail.
Estimation of moments of inertia of airplanes from design data
"A method of determining the moments of inertia of an airplane from design data pertaining to the weights and locations of the component parts is described. The computations required to ascertain the center-of-gravity position are incorporated with the calculations of moments of inertia. A complete set of data and calculations for a modern airplane is given to illustrate the procedure. From a comparison between calculated values and measured values it is believed that the moments of inertia can be estimated within 10 percent by the use of this method" (p. 1).
Experimental Studies of the Effective Width of Buckled Sheets
The object of the present experiments is a more exact determination of the effective width for the case of pure compression and of the sheet clamped at the angle section. From the experimental data of the effective width the calculation of the buckling load of an angle joined to a thin sheet is then deduced. The test material consisted of spring-hardened brass sheet.
Flight measurements of the dynamic longitudinal stability of several airplanes and a correlation of the measurements with pilots' observations of handling characteristics
The dynamic longitudinal stability characteristics of eight airplanes as defined by the period and damping of the longitudinal oscillations were measured in flight to determine the degree of stability that may be expected in conventional airplanes. An attempt was made to correlate the measured stability with pilots' opinions of the general handling characteristics of the airplanes in order to obtain an indication of the most desirable degree of dynamic stability. The results of the measurements show that the period of oscillation increases with speed. At low speeds a range of periods from 11 to 23 seconds was recorded for the different airplanes. At high speeds the periods ranged from 23 to 64 seconds. The damping showed no definite trend with speed.
Flow Phenomena on Plates and Airfoils of Short Span
"Investigations on the flow phenomena at plates and cambered models were carried out with the aid of force measurements, some pressure distribution measurements, and photographic observation. The experimental methods are described and the results given. Section III of this work gives a comprehensive account of the results and enables us to see how nearly the lift line and lift surface theories agree with the experimental results" (p. 1).
The Forces and Moments Acting on Parts of the XN2Y-1 Airplane During Spins
"The magnitudes of the yawing moments produced by various parts of an airplane during spins have previously been found to be of major importance in determining the nature of the spin. Discrepancies in resultant yawing moments determined from model and full-scale tests, however, have indicated the probable importance of scale effect on the model. In order to obtain data for a more detailed comparison between full-scale and model results, flight tests were made to determine the yawing moments contributed by various parts of an airplane in spins. The inertia moment was determined by the usual measurement of the spinning motion, and the aerodynamic yawing moments on the fuselage, fin, and rudder were determined by pressure-distribution measurements over these parts of the airplane" (p. 305).
The Forces and Moments on Airplane Engine Mounts
"A resume of the equations and formulas for the forces and moments on an aircraft-engine mount is presented. In addition, available experimental data have been included to permit the computation of these forces and moments. A sample calculation is made and compared with present design conditions for engine mounts" (p. 1).
The Formation of Ice on Airplanes
"The present report examines the problem of ice formation from the point of view of the pilot and the meteorologist. Their experiences prove the ice deposit to be first and foremost a navigational problem and only secondarily a question of de-icing devices. With correct utilization of the meteorological information by the flyer, ice hazard can in many cases be minimized or avoided. Ice formation and the different types of ice deposits are listed and discussed" (p. 1).
Friction of compression-ignition engines
"The cost in mean effective pressure of generating air flow in the combustion chambers of single-cylinder compression-ignition engines was determined for the prechamber and the displaced-piston types of combustion chamber. For each type a wide range of air-flow quantities, speeds, and boost pressures was investigated. Supplementary tests were made to determine the effect of lubricating-oil temperature, cooling-water temperature, and compression ratio on the friction mean effective pressure of the single-cylinder test engine" (p. 1).
Fuel spray and flame formation in a compression-ignition engine employing air flow
"The effects of air flow on fuel spray and flame formation in a high-speed compression-ignition engine have been investigated by means of the NACA combustion apparatus. The process was studied by examining high-speed motion pictures taken at the rate of 2,200 frames a second. The combustion chamber was of the flat-disk type used in previous experiments with this apparatus. The air flow was produced by a rectangular displacer mounted on top of the engine piston. Three fuel-injection nozzles were tested: a 0.020-inch single-orifice nozzle, a 6-orifice nozzle, and a slit nozzle" (p. 281).
Full-scale tests of NACA cowlings
A comprehensive investigation has been carried on with full-scale models in the NACA 20-foot wind tunnel, the general purpose of which is to furnish information in regard to the physical functioning of the composite propeller-nacelle unit under all conditions of take-off, taxiing, and normal flight. This report deals exclusively with the cowling characteristics under condition of normal flight and includes the results of tests of numerous combinations of more than a dozen nose cowlings, about a dozen skirts, two propellers, two sizes of nacelle, as well as various types of spinners and other devices.
Full-scale wind-tunnel and flight tests of a Fairchild 22 airplane equipped with a Fowler flap
"Full-scale wind-tunnel and flight tests were made of a Fairchild 22 airplane equipped with a Fowler flap to determine the effect of the flap on the performance and control characteristics of the airplane. In the wind-tunnel tests of the airplane with the horizontal tail surfaces removed, the flap was found to increase the maximum lift coefficient from 1.27 to 2.41. In the flight test, the flap was found to decrease the minimum speed from 58.8 to 44.4 miles per hour" (p. 1).
Full-scale wind-tunnel to determine a satisfactory location for a service Pitot-static tube on a low-wing monoplane
Surveys of the air flow over the upper surface of four different airfoils were made in the full-scale wind tunnel to determine a satisfactory location for a fixed Pitot-static tube on a low-wing monoplane. The selection was based on small interference errors, less than 5 percent, and on a consideration of structural and ground handling problems. The most satisfactory location on the airfoils without flaps that were investigated was 10 percent of the chord aft and 25 percent of the chord above the trailing edge of a section approximately 40 percent of the semispan inboard of the wing tip. No satisfactory location was found near the wing when the flaps were deflected.
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