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Some Effects of Compressibility on the Flow Through Fans and Turbines

Description: "The laws of conservation of mass, momentum, and energy are applied to the compressible flow through a two-dimensional cascade of airfoils. A fundamental relation between the ultimate upstream and downstream flow angles, the inlet Mach number, and the pressure ratio across the cascade is derived. Comparison with the corresponding relation for incompressible flow shows large differences. The fundamental relation reveals two ranges of flow angles and inlet Mach numbers, for which no ideal pressure ratio exists" (p. 123).
Date: August 1, 1945
Creator: Perl, W. & Epstein, H. T.
Partner: UNT Libraries Government Documents Department

Relation between spark-ignition engine knock, detonation waves, and autoignition as shown by high-speed photography

Description: "A critical review of literature bearing on the autoignition and detonation-wave theories of spark-ignition engine knock and on the nature of gas vibrations associated with combustion and knock results in the conclusion that neither the autoignition theory nor the detonation-wave theory is an adequate explanation of spark-ignition engine knock. A knock theory is proposed, combining the autoignition and detonation-wave theories, which introduces the idea that the detonation wave develops in autoignited or after-burning gases, and ascribes comparatively low-pitched heavy knocks to autoignition but high-pitched pinging knocks to detonation waves with the possibility of combinations of the two types of knocks" (p. 317).
Date: December 5, 1945
Creator: Miller, Cearcy D.
Partner: UNT Libraries Government Documents Department

Estimation of F-3 and F-4 knock-limited performance ratings for ternary and quaternary blends containing triptane or other high-antiknock aviation-fuel blending agents

Description: Charts are presented that permit the estimation of F-3 and F-4 knock-limited performance ratings for certain ternary and quaternary fuel blends. Ratings for various ternary and quaternary blends estimated from these charts compare favorably with experimental F-3 and F-4 ratings. Because of the unusual behavior of some of the aromatic blends in the F-3 engine, the charts for aromatic-paraffinic blends are probably less accurate than the charts for purely paraffinic blends.
Date: January 20, 1945
Creator: Barnett, Henry C.
Partner: UNT Libraries Government Documents Department

A systematic investigation of pressure distributions at high speeds over five representative NACA low-drag and conventional airfoil sections

Description: From Summary: "Pressure distributions determined from high-speed wind-tunnel tests are presented for five NACA airfoil sections representative of both low-drag and conventional types. Section characteristics of lift, drag, and quarter-chord pitching moment are presented along with the measured pressure distributions for the NACA 65sub2-215 (a=0.5), 66sub2-215 (a=0.6), 0015, 23015, and 4415 airfoils for Mach numbers up to approximately 0.85. A critical study is made of the airfoil pressure distributions in an attempt to formulate a set of general criteria for defining the character of high speed flows over typical airfoil shapes. Comparisons are made of the relative characteristics of the low-drag and conventional airfoils investigated insofar as they would influence the high-speed performance and the high-speed stability and control characteristics of airplanes employing these wing sections."
Date: 1945
Creator: Graham, Donald J.; Nitzberg, Gerald E. & Olson, Robert N.
Partner: UNT Libraries Government Documents Department

A visual photographic study of cylinder lubrication

Description: From Summary: "A V-type engine provided with a glass cylinder was used to study visually the lubrication characteristics of an aircraft-type piston. Photographs and data were obtained with the engine motored at engine speeds up to 1000 r.p.m. and constant cylinder-head pressures of 0 and 50 pounds per square inch. A study was made of the orientation of the piston under various operating conditions, which indicated that the piston was inclined with the crown nearest the major-thrust cylinder face throughout the greater part of the cycle. The piston moved laterally in the cylinder under the influence of piston side thrust."
Date: August 1, 1945
Creator: Shaw, Milton C. & Nussdorfer, Theodore
Partner: UNT Libraries Government Documents Department

Comparison of several methods of predicting the pressure loss at altitude across a baffled aircraft-engine cylinder

Description: Several methods of predicting the compressible-flow pressure loss across a baffled aircraft-engine cylinder were analytically related and were experimentally investigated on a typical air-cooled aircraft-engine cylinder. Tests with and without heat transfer covered a wide range of cooling-air flows and simulated altitudes from sea level to 40,000 feet. Both the analysis and the test results showed that the method based on the density determined by the static pressure and the stagnation temperature at the baffle exit gave results comparable with those obtained from methods derived by one-dimensional-flow theory. The method based on a characteristic Mach number, although related analytically to one-dimensional-flow theory, was found impractical in the present tests because of the difficulty encountered in defining the proper characteristic state of the cooling air. Accurate predictions of altitude pressure loss can apparently be made by these methods, provided that they are based on the results of sea-level tests with heat transfer.
Date: October 9, 1945
Creator: Neustein, Joseph & Schafer, Louis J., Jr.
Partner: UNT Libraries Government Documents Department

A general representation for axial-flow fans and turbines

Description: A general representation of fan and turbine arrangements on a single classification chart is presented that is made possible by a particular definition of the stage of an axial-flow fan or turbine. Several unconventional fan and turbine arrangements are indicated and the applications of these arrangements are discussed.
Date: May 4, 1945
Creator: Perl, W. & Tucker, M.
Partner: UNT Libraries Government Documents Department

General theory of airfoil sections having arbitrary shape or pressure distribution

Description: In this report a theory of thin airfoils of small camber is developed which permits either the velocity distribution corresponding to a given airfoil shape, or the airfoil shape corresponding to a given velocity distribution to be calculated. The procedures to be employed in these calculations are outlined and illustrated with suitable examples.
Date: 1945
Creator: Allen, H. Julian
Partner: UNT Libraries Government Documents Department

Summary of Airfoil Data

Description: From Summary: "The historical development of NACA airfoils is briefly reviewed. New data are presented that permit the rapid calculation of the approximate pressure distributions for the older NACA four-digit and five-digit airfoils by the same methods used for the NACA 6-series airfoils. The general methods used to derive the basic thickness forms for NACA 6 and 7-series airfoils together with their corresponding pressure distributions are presented. Detail data necessary for the application of the airfoils to wing design are presented in supplementary figures placed at the end of the paper. The report includes an analysis of the lift, drag, pitching-moment, and critical-speed characteristics of the airfoils, together with a discussion of the effects of surface conditions. Available data on high-lift devices are presented. Problems associated with lateral-control devices, leading-edge air intakes, and interference are briefly discussed, together with aerodynamic problems of application."
Date: 1945
Creator: Abbott, Ira H.; von Doenhoff, Albert E. & Stivers, Louis S., Jr.
Partner: UNT Libraries Government Documents Department

A method for determining the rate of heat transfer from a wing or streamline body

Description: A method for calculating the rate of heat transfer from the surface of an airfoil or streamline body is presented. A comparison with the results of an experimental investigation indicates that the accuracy of the method is good. This method may be used to calculate the heat supply necessary for heat de-icing or in ascertaining the heat loss from the fuselage of an aircraft operating at great altitude. To illustrate the method, the total rate of heat transfer from an airfoil is calculated and compared with the experimental results.
Date: 1945
Creator: Frick, Charles W. & McCullough, George B.
Partner: UNT Libraries Government Documents Department

Method of Matching Performance of Compressor Systems with that of Aircraft Power Sections

Description: "A method is developed of easily determining the performance of a compressor system relative to that of the power section for a given altitude. Because compressors, reciprocating engines, and turbines are essentially flow devices, the performance of each of these power-plant components is presented in terms of similar dimensionless ratios. The pressure and temperature changes resulting from restrictions of the charge-air flow and from heat transfer in the ducts connecting the components of the power plant are also expressed by the same dimensionless ratios and the losses are included in the performance of the compressor" (p. 119).
Date: November 15, 1945
Creator: Bullock, Robert O.; Keetch, Robert C. & Moses, Jason J.
Partner: UNT Libraries Government Documents Department

The NACA high-speed motion-picture camera optical compensation at 40,000 photographs per second

Description: The principle of operation of the NACA high-speed camera is completely explained. This camera, operating at the rate of 40,000 photographs per second, took the photographs presented in numerous NACA reports concerning combustion, preignition, and knock in the spark-ignition engine. Many design details are presented and discussed, details of an entirely conventional nature are omitted. The inherent aberrations of the camera are discussed and partly evaluated. The focal-plane-shutter effect of the camera is explained. Photographs of the camera are presented. Some high-speed motion pictures of familiar objects -- photoflash bulb, firecrackers, camera shutter -- are reproduced as an illustration of the quality of the photographs taken by the camera.
Date: November 6, 1945
Creator: Miller, Cearcy D.
Partner: UNT Libraries Government Documents Department

An analysis of life expectancy of airplane wings in normal cruising flight

Description: From Summary: "In order to provide a basis for judging the relative importance of wing failure by fatigue and by single intense gusts, an analysis of wing life for normal cruising flight was made based on data on the frequency of atmospheric gusts. The independent variables considered in the analysis included stress-concentration factor, stress-load relation, wing loading, design and cruising speeds, design gust velocity, and airplane size. Several methods for estimating fatigue life from gust frequencies are discussed."
Date: May 28, 1945
Creator: Putnam, Abbott A.
Partner: UNT Libraries Government Documents Department

Comparative drag measurements at transonic speeds of rectangular sweptback NACA 65-009 airfoils mounted on a freely falling body

Description: From Summary: "Directly comparable drag measurements have been made of an airfoil with a conventional rectangular plan form and an airfoil with a sweptback plan form mounted on freely falling bodies. Both airfoils had NACA 65-009 sections and were identical in span, frontal area, and chord perpendicular to the leading edge. The sweptback plan form incorporated a sweepback angle of 45 degrees. The data obtained have been used to establish the relation between the airfoil drag coefficients and the free-stream Mach number over a range of Mach numbers from 0.90 to 1.27. The results of the measurements indicate that the drag of the sweptback plan form is less than 0.3 that of the rectangular plan form at a Mach number of 1.00 and is less than 0.4 that at a Mach number of 1.20."
Date: August 9, 1945
Creator: Mathews, Charles W. & Thompson, Jim Rogers
Partner: UNT Libraries Government Documents Department

Analysis and modification of theory for impact of seaplanes on water

Description: From Summary: "An analysis of available theory on seaplane impact and a proposed modification thereto are presented. In previous methods the overall momentum of the float and virtual mass has been assumed to remain constant during the impact but the present analysis shows that this assumption is rigorously correct only when the resultant velocity of the float is normal to the keel."
Date: August 20, 1945
Creator: Mayo, Wilbur L.
Partner: UNT Libraries Government Documents Department

Summary report on the high-speed characteristics of six model wings having NACA 65(sub1)-series sections

Description: A summary of the results of wind-tunnel tests to determine the high-speed aerodynamic characteristics of six model wings having NACA 65sub1-series sections is presented in this report. The 8-percent-thick wings were superior to the 10-percent and 12-percent-thick wings from the standpoint of power economy during level flight for Mach numbers above 0.76. However, airplanes that are to fly at Mach numbers below 0.76 will gain aerodynamically if the percentage thickness of the wing and the aspect ratio are both increased. The lift-curve slopes for the 8-percent-thick wings at 0.85 Mach number were roughly twice their low-speed values.
Date: October 19, 1945
Creator: Hamilton, William T. & Nelson, Warren H.
Partner: UNT Libraries Government Documents Department

Principles of Moment Distribution Applied to Stability of Structures Composed of Bars or Plates

Description: "The principles of the cross method of moment distribution, which have previously been applied to the stability of structures composed of bars under axial load, are applied to the stability of structures composed of long plates under longitudinal load. A brief theoretical treatment of the subject, as applied to structures composed of either bars or plates, is included, together with an illustrative example for each of these two types of structure. An appendix presents the derivation of the formulas for the various stiffnesses and carry-over factors used in solving problems in the stability of structures composed of long plates" (p. 57).
Date: 1945
Creator: Lundquist, Eugene E.; Stowell, Elbridge Z. & Schuette, Evan H.
Partner: UNT Libraries Government Documents Department

Charts for the Minimum-Weight Design of 24S-T Aluminum-Alloy Flat Compression Panels With Longitudinal Z-Section Stiffeners

Description: "Design charts are developed for 24S-T aluminum-alloy flat compression panels with longitudinal z-section stiffeners. These charts make possible the design of the lightest panels of this type for a wide range of design requirements. Examples of the use of the charts are given and it is pointed out on the basis of these examples that, over a wide range of design conditions, the maintenance of buckle-free surfaces does not conflict with the achievement of high structural efficiency" (p. 553).
Date: July 9, 1945
Creator: Schuette, Evan H.
Partner: UNT Libraries Government Documents Department

Correlation of Exhaust-Valve Temperatures With Engine Operating Conditions and Valve Design in an Air-Cooled Cylinder

Description: "A semiempirical equation correlating exhaust-valve temperatures with engine operating conditions and exhaust-valve design has been developed. The correlation is based on the theory correlating engine and cooling variables developed in a previous NACA report. In addition to the parameters ordinarily used in the correlating equation, a term is included in the equation that is a measure of the resistance of the complex heat-flow paths between the crown of the exhaust valve and a point on the outside surface of the cylinder head" (p. 103).
Date: October 1945
Creator: Zipkin, M. A. & Sanders, J. C.
Partner: UNT Libraries Government Documents Department

Effect of NACA Injection Impeller on Mixture Distribution of Double-Row Radial Aircraft Engine

Description: "The NACA injection impeller was developed to improve the mixture distribution of aircraft engines by discharging the fuel from a centrifugal supercharger impeller and thus to promote a thorough mixing of fuel and charge air. Experiments with a double-row radial aircraft engine indicated that for the normal range of engine power the NACA injection impeller provided marked improvement in mixture distribution over the standard spray-bar injection system used in the same engine. The mixture distribution at cruising conditions was excellent; at 1200, 1500, and 1700 brake horsepower, the differences between the fuel-air ratios of the richest and the leanest cylinders were reduced to approximately one-third their former values" (p. 217).
Date: November 14, 1945
Creator: Marble, Frank E.; Ritter, William K. & Miller, Mahlon A.
Partner: UNT Libraries Government Documents Department

An Analysis of the Dissipation of Heat in Conditions of Icing From a Section of the Wing of the C-46 Airplane

Description: From Introduction: "The performance of the heated wing of the C-46 airplane (reference 1), in conditions of icing, has been analyzed. The method of calculating the dissipation of heat, both by convection and by evaporation, from a heated surface exposed to conditions of icing is given in reference 2."
Date: 1945?~
Creator: Hardy, J. K.
Partner: UNT Libraries Government Documents Department

Calculations of Economy of 18-Cylinder Radial Aircraft Engine With Exhaust-Gas Turbine Geared to the Crankshaft

Description: Calculations based on dynamometer test-stand data obtained on an 18-cylinder radial engine were made to determine the improvement in fuel consumption that can be obtained at various altitudes by gearing an exhaust-gas turbine to the engine crankshaft in order to increase the engine-shaft work.
Date: January 1, 1945
Creator: Hannum, Richard W. & Zimmerman, Richard H.
Partner: UNT Libraries Government Documents Department

An Investigation of Backflow Phenomenon in Centrifugal Compressors

Description: Report presents the results of an investigation conducted to determine the nature and the extent of the reversal of flow, which occurs at the inlet of centrifugal compressors over a considerable portion of the operating range. Qualitative studies of this flow reversal were made by lampblack patterns taken on a mixed-flow-type impeller and by tuft studies made on a conventional centrifugal compressor. Quantitative studies were made on a compressor specially designed to enable survey of angularity of flow, static and total pressures, and temperatures to be taken very close to the impeller front housing.
Date: 1945
Creator: Benser, William A. & Moses, Jason J.
Partner: UNT Libraries Government Documents Department

Investigation of the NACA 4-(5)(08)-03 and NACA 4-(10)(08)-03 two-blade propellers at forward Mach numbers to 0.725 to determine the effects of camber and compressibility on performance

Description: As part of a general investigation of propellers at high forward speeds, tests of two-blade propellers having the NACA 4-(5)(08)-03 and NACA 4-(10)(08)-03 blade designs were made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 60 degrees for forward Mach numbers from 0.165 to 0.70 to determine the effect of camber and compressibility on propeller characteristics. Results previously reported for similar tests of a two-blade propeller having the NACA 4-(3)(08)-03 blade design are included for comparison.
Date: May 7, 1945
Creator: Delano, James B.
Partner: UNT Libraries Government Documents Department