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Calculations of Intake-Air Cooling Resulting From Water Injection and of Water Recovery From Exhaust Gas

Description: Report discussing some calculations made for the effects of water in cooling the inlet air of aircraft-engine cylinders. From Summary: "The estimates indicate that the cooling effect of the water on the inlet air can be more extensive than the cooling now obtained with the intercoolers or aftercoolers in the air-induction system. In connection with water recovery from the exhaust gas, the estimates indicate that sufficient water can be recovered from 50 percent of the exhaust gas to provide an … more
Date: August 1944
Creator: Rothrock, Addison M.
open access

Comparative Fatigue Tests of Riveted Joints of Alclad 24S-T, Alclad 24S-T81, Alclad 24S-RT, Alclad 24S-T86 and Alclad 75S-T Sheet

Description: Report discusses testing performed to determine the fatigue strength of various types of riveted and spot-welded joints in the following aluminum alloys: Alclad 24S-T, 24S-RT, 758-T, 24S-T81, and 24S-T86. Details of the experiment, tensile properties, and information about failure are provided.
Date: August 1945
Creator: Moore, R. L. & Hill, H. N.
open access

Comparative Tests of the Strength and Tightness of Commercial Flush Rivets of One Type and NACA Flush Rivets in Machine-Countersunk and Counterpunched Joints

Description: Report discusses an investigation that was conducted to compare the strength and tightness of machine-countersunk flush-riveted joints assembled with NACA flush rivets and a type of commercial flush rivet. A comparison was also generated between the strength and tightness of counterpunched flush-riveted joints assembled with the same types of rivet. NACA's flush-riveted joints tended to be stronger and tighter than the commercial joints.
Date: February 1, 1944
Creator: Mandel, Merven W.
open access

Comparison of Structural Efficiencies of Diagonal-Tension Webs and Truss Webs of 24S-T Aluminum Alloy

Description: "A comparison is made of the structural efficiencies of truss webs of 24S-T aluminum alloy with previously published values of the structural efficiencies of diagonal-tension webs of 24S-T aluminum alloy on the basis of identical allowable stresses. It is concluded that the diagonal-tension beam (web and flanges) can usually be built to be a more efficient beam than the truss beam, even though over a small range the web of a Warren truss beam is slightly more efficient than the web of a diagona… more
Date: July 1945
Creator: Ochiltree, David W.
open access

Comparison of tightness of 78 degrees machine-countersunk rivets driven in holes prepared with 78 degrees and 82 degrees countersinking tools

Description: Report presenting an investigation to determine whether the use of a 78 degree countersinking tool instead of a 82 degree countersinking tool for riveting would substantially alter the conclusion reached in a previous paper regarding the placement of rivets for maximum strength.
Date: September 1942
Creator: Gottlieb, Robert & Mandel, Merven W.
open access

Computation of the Mean Tangential Velocity of the Air Leaving the Blade Tips of a Centrifugal Supercharger

Description: Report discusses the differences between the mean tangential velocity of the air leaving the blade tips of a centrifugal supercharger calculated by the conventional turbine equation and by an equation that uses the isentropic increase in total enthalpy. The velocities are compared to experimental values observed with three diffusers.
Date: August 1945
Creator: Brown, W. Byron
open access

Critical Compressive Stress for Curved Sheet Supported Along All Edges and Elastically Restrained Against Rotation Along the Unloaded Edges

Description: "A formula is given for the critical compressive stress for slightly curved sheet with equal elastic restraints against rotation along the unloaded edges. The theory of small deflections is used and the formula reduces to that given by Timoshenko for the case of simply-supported edges. For larger curvatures, a modification of Redshaw's formula to include the effect of edge restraint is suggested" (p. 1).
Date: September 1943
Creator: Stowell, Elbridge Z.
open access

Cylinder-Head Cooling by Means of a Shield in the Exhaust Passage

Description: "Tests were run on a single-cylinder, air-cooled engine with a Wright C9GC cylinder to determine the improvement in cylinder-head cooling that can be obtained by building into the exhaust passage an insulating shield designed to protect the valve-guide boss and the exhaust-passage walls from the exhaust gas. The test results showed an appreciable improvement in cooling of the exhaust-valve-guide boss, of the guide bushing, and of the valve seat" (p. 1).
Date: June 1944
Creator: Wilsted, H. D. & Mulcahy, B. A.
open access

A Description of the Ju 88 Airplane Anti-Icing Equipment

Description: Bulletin presenting an examination of a part of the anti-icing equipment for a Ju 88 airplane, including exhaust-air heat exchangers, control valves, air duct system, and air-heated wing panels. Testing was performed on the components and indicated that the thermal ice-prevention equipment can maintain the outer-wing panel free from ice.
Date: September 1942
Creator: Rodert, Lewis A. & Jackson, Richard
open access

Determination From Flight Tests of Thrust Coefficients for 10 Full-Scale Airplanes in the Gliding Condition With Engine Idling

Description: "Typical thrust and torque coefficients and increments, due to the propeller, in the ratio of the dynamic pressure at the tail to the free-stream dynamic pressure are presented for 10 full-scale airplanes. Calculations indicate that an error of about 2 percent mean aerodynamic chord appears possible in determining the neutral point from wind-tunnel tests or a model in the gliding condition if the propeller is operated at zero thrust rather than at the values of thrust coefficient indicated by t… more
Date: June 1945
Creator: Talmage, Donald B.
open access

Determination of desirable lengths of Z- and channel-section columns for local-instability tests

Description: From Summary: "Local-instability tests of 24S-T aluminum-alloy formed Z- and channel-section columns were made in order to determine a length of test specimen that would avoid the increased strength associated with short lengths and also permit the occurrence of a convenient buckling pattern. The effect of column length on the critical compressive stress, on the average stress at maximum load, and on the number of half-waves of the buckling pattern is shown."
Date: October 1944
Creator: Heimerl, George J. & Roy, J. Albert
open access

Determination of Iron Contamination of Used Lubricating Oil for Use in Measuring Rates of Wear in Aircraft Engines

Description: Report discusses methods of determining the iron contamination of used lubricating oil in order to study wear rates of piston rings and cylinder barrels of aircraft engines. Two methods of separating iron from used lubricating oil are presented. The results of the analyses of the oil are presented and the methods are evaluated.
Date: March 1944
Creator: Tischler, Adelbert O.
open access

Dilution of Exhaust-Gas Samples From a Multicylinder Engine Equipped With an Exhaust-Gas Collector

Description: Report discusses the results of an investigation to determine the effect of a collector ring on exhaust-gas sampling. The results of tests to determine the percentage by volume of exhaust gas from the collector ring are presented for several engine powers and speeds. The danger of air dilution from the breathing action of the engine is almost entirely eliminated by the use of a collector ring.
Date: February 1945
Creator: Butze, Helmut F.
open access

The Effect of Angle of Bend Between Plate Elements on the Local Instability of Formed Z-Sections

Description: "Thirty-nine Z-sections formed from 24S-T aluminum-alloy sheet with the angle of bend between the flanges and the web varying from 5 degrees to 120 degrees were tested as columns. Angles of bend from 30 degrees to 120 degrees had little or no effect on the critical stress or on the average stress at maximum load for local instability of the columns. The lengths of the columns were such that at angles of bend below 30 degrees they failed by Euler buckling" (p. 1).
Date: September 1944
Creator: Roy, J. Albert & Schuette, Evan H.
open access

The Effect of Artificial Aging on the Tensile Properties of Alclad 24S-T and 24S-T Aluminum Alloy

Description: "An experimental study was made to determine the effect of artificial aging on the tensile properties of alclad 24S-T and 24S-T aluminum-alloy sheet material. The results of the tests show that certain combinations of aging time and temperature cause a marked increase in the yield strength and a small increase in the ultimate strength; these increases are accompanied by a very large decrease in elongation. A curve is presented that shows the maximum yield strengths that can be obtained by aging… more
Date: August 1943
Creator: Kotanchik, Joseph N.; Woods, Walter & Zender, George W.
open access

Effect of Changes in Aileron Rigging on the Stick Forces of a High-Speed Fighter Airplane

Description: "The effects of changes in aileron rigging between 2 deg up and 2 deg down on the stick forces were determined from wind-tunnel data for a finite-span wing model. These effects were investigated for ailerons deflecting equally in both directions and linearly with stick deflection. Data were analyzed for a Frise, a sealed internally balanced, and a beveled-trailing-edge aileron" (p. 1).
Date: May 1944
Creator: Murray, Harry E. & Warren, S. Anne
open access

Effect of Countersunk Depth on the Tightness of Two Types of Machine-Countersunk Rivet

Description: Bulletin presenting an investigation conducted to determine the effect of countersunk depth on the tightness of two types of machine-countersunk flush rivet. The specimens tested in the study were simple lap joints made by two different riveting methods. The results indicated that roundheaded rivets inserted from the back of the joint with the countersunk heads formed int he driving of the rivets produce tighter joints over a large range of depths than ordinary flush rivets.
Date: October 1942
Creator: Gottlieb, Robert
open access

Effect of Inlet-Air Temperature and Cylinder Displacement on Charge Temperature of Internal Combustion Engines

Description: Report discussing the effect of inlet-air temperature and cylinder displacement on the charge temperature of an internal-combustion engine at the end of the induction stroke. The experiment to test various types of cylinders and their results on the air temperature and pressure is described.
Date: January 1944
Creator: Sanders, Newell D. & Bolz, Ray E.
open access

Effect of Lateral Shift of Center of Gravity on Rudder Deflection Required for Trim

Description: Report discusses the results of testing of rudder deflection for trim at low speeds in the critical wave-off condition. Depending on the lateral center-of-gravity location on the airplane, the useful load in the wings will change and the ability of the rudder to trim the airplane may be greatly improved.
Date: November 1944
Creator: Phillips, W. H.; Crane, H. L. & Hunter, P. A.
open access

Effect of Normal Pressure on the Critical Compressive Stress of Curved Sheet

Description: Results are presented of tests of two specimens tested to study the effect of normal pressure on the critical compressive stress for thin curved sheets. These specimens are designated by their respective rib spacings of 10 inches and 30 inches. The relationship between compressive stress and normal pressure at which buckles disappeared is independent of whether the buckles were made to disappear by increase of normal pressure or decrease of compressive stress. (author).
Date: August 25, 1942
Creator: Rafel, Norman
open access

Effect of Normal Pressure on the Critical Shear Stress of Curved Sheet

Description: "In order to determine the critical stresses caused by an outward acting pressure on the upper surface of a wing due to the difference in internal and external pressures, torsional tests were made on two curved-sheet specimens subjected to an outward acting normal pressure. Results show that an outward acting normal pressure appreciable raises the critical shear stress for an unstiffened curved sheet; the absolute increase in critical shear stress is slightly greater for a 30 in. rib spacing th… more
Date: January 1943
Creator: Rafel, Norman
open access

The Effect of Oil Consumption and Piston Cooling on Knock-Limited Aircraft-Engine Performance

Description: Report discusses the "effects of oil introduced into the combustion chamber and of oil-spray piston cooling on the knock-limited performance of aircraft engines" (from Summary). A CFR engine and Allison V-1710 cylinder were used to test the rate of oil consumption, knock, and knock-limited brake mean effective pressure.
Date: May 1944
Creator: Huppert, Merle C.; Imming, Harry S. & Richard, Paul H.
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