Adjustment of Stick Force by a Nonlinear Aileron-Stick Linkage (open access)

Adjustment of Stick Force by a Nonlinear Aileron-Stick Linkage

Report presenting an application of the principle of aileron-stick forces and mechanical advantage to an aileron installation in which the stick forces are small over the low-deflection range and excessively large at full deflection.
Date: November 1942
Creator: Lowry, John G.
System: The UNT Digital Library
Aerodynamic Characteristics of Four NACA Airfoil Sections Designed for Helicopter Rotor Blades (open access)

Aerodynamic Characteristics of Four NACA Airfoil Sections Designed for Helicopter Rotor Blades

"The purpose of the present work is to extend the previous investigation and to derive additional airfoil sections designed to minimize the undesirable characteristics of the previously tested airfoils. The tests of these additional airfoils were made in the Langley two-dimensional low-turbulence tunnel (LTT)" (p. 2).
Date: February 1946
Creator: Stivers, Louis S., Jr. & Rice, Fred J., Jr.
System: The UNT Digital Library
An analysis of the fatigue life of an airplane wing structure under overload conditions (open access)

An analysis of the fatigue life of an airplane wing structure under overload conditions

From Introduction: "Fatigue life expectancy in normal transport operations was investigated in reference 1 and was found to be of equal importance with single-gust life. The effect of overload operation of transport airplanes on the probability of encountering single critical gusts was investigated in reference 2 and the frequency of critical gusts was found to increase rapidly with overload. The effect of overload operation on fatigue strength, however, has not heretofore been evaluated, hence the investigations of references 1 and 2 are combined herein to permit such evaluation and to determine the relative importance of fatigue and single-gust failures under conditions of overload operation."
Date: February 1946
Creator: Putnam, Abbott A. & Reisert, Thomas D.
System: The UNT Digital Library
Application of Balancing Tabs to Ailerons (open access)

Application of Balancing Tabs to Ailerons

Analysis was made to determine characteristics required of a balancing-tab system for ailerons in order to reduce aileron stick forces to any desired magnitude. Series of calculations based on section data were made to determine balancing-tab systems of various chord tabs and ailerons that will give, for a particular airplane, zero rate of aileron hinge moment with aileron deflection and yet will produce same maximum rate of roll as a plain unbalanced 15-percent chord aileron of same span. Effects of rolling velocity and of forces in tab link on aileron hinge moments have been included.
Date: June 1942
Creator: Sears, Richard I.
System: The UNT Digital Library
An Approximate Determination of the Power Required to Move Control Surfaces as Related to Control-Booster Design (open access)

An Approximate Determination of the Power Required to Move Control Surfaces as Related to Control-Booster Design

"As a part of a general investigation of control boosters, preliminary calculations were made to indicate the sizes of control boosters necessary to move the controls of airplanes of various sizes. The analysis was based on the assumption that the controls were moved with a rapidity and amplitude equal to that measured with a fighter airplane in simulated combat. A corollary purpose consisted in determining the effect on reducing booster-power unit size of incorporating an energy accumulator in the booster system" (p. 1).
Date: September 1945
Creator: Johnson, Harold I.
System: The UNT Digital Library
An Approximate Method of Shear-Lag Analysis for Beams Loaded at Right Angles to the Plane of Symmetry of the Cross Section (open access)

An Approximate Method of Shear-Lag Analysis for Beams Loaded at Right Angles to the Plane of Symmetry of the Cross Section

Report discussing strain measurements made on a box beam of triangular cross section and on two beams of D-section under transverse bending. Information about the arrangement of the beams and experimental and calculated stresses for different boxes.
Date: September 1943
Creator: Kuhn, Paul & Brilmyer, Harold G.
System: The UNT Digital Library
An Automatically Variable Control Linkage and Its Effect on the Lateral-Control Characteristics of a High-Speed Fighter Airplane (open access)

An Automatically Variable Control Linkage and Its Effect on the Lateral-Control Characteristics of a High-Speed Fighter Airplane

Report discusses an analysis and preliminary design of a control linkage that varies automatically with dynamic pressure. The advantages of the device, including greater lateral control than a fixed control linkage without additional aerodynamic balance, are detailed. The effect of variable linkage on lateral-control characteristics is also described.
Date: May 1944
Creator: Gillis, Clarence L.
System: The UNT Digital Library
The belt method for measuring pressure distribution (open access)

The belt method for measuring pressure distribution

"The measurement of pressure distribution may be accomplished rapidly for any number of locations deemed necessary in model or full-scale investigations by use of the 'belt' method. Reasonable accuracy may be obtained by careful use of this method" (p. 1).
Date: February 1943
Creator: Corson, Blake W., Jr.
System: The UNT Digital Library
Calculation of Stick Forces for an Elevator With a Spring Tab (open access)

Calculation of Stick Forces for an Elevator With a Spring Tab

"Formulas for the calculation of hinge-moment characteristics of an elevator with a spring tab have been developed in terms of basic aerodynamic parameters, spring stiffness, and airspeed. The formulas have been used in a study of the stick-force gradients on a pursuit airplane equipped with an elevator with a spring tab. Charts are presented showing the variation of stick-force gradient in accelerated flight over a large range of speed and the complete range of spring stiffness for various center-of-gravity locations, altitudes, and airplane sizes" (p. 1).
Date: June 1944
Creator: Greenberg, Harry
System: The UNT Digital Library
Calculation of tab characteristics for flight conditions from wind-tunnel data (open access)

Calculation of tab characteristics for flight conditions from wind-tunnel data

Report presenting tail-surface characteristics calculated from wind-tunnel data, which have been reported to not correspond with flight-test measurements. The primary problem under consideration is the calculation of the effect of tab deflection on the free-floating angle of the elevator, as in a servocontrol.
Date: April 1942
Creator: Sears, Richard I.
System: The UNT Digital Library
Calculations of Intake-Air Cooling Resulting From Water Injection and of Water Recovery From Exhaust Gas (open access)

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

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 inducted water-fuel ratio of 0.5."
Date: August 1944
Creator: Rothrock, Addison M.
System: The UNT Digital Library
Comparative Fatigue Tests of Riveted Joints of Alclad 24S-T, Alclad 24S-T81, Alclad 24S-RT, Alclad 24S-T86 and Alclad 75S-T Sheet (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

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.
System: The UNT Digital Library
Comparative Tests of the Strength and Tightness of Commercial Flush Rivets of One Type and NACA Flush Rivets in Machine-Countersunk and Counterpunched Joints (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

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.
System: The UNT Digital Library
A Comparison of Data Obtained by Two Flight Techniques for Determining the Sideslip Characteristics of a Fighter Airplane (open access)

A Comparison of Data Obtained by Two Flight Techniques for Determining the Sideslip Characteristics of a Fighter Airplane

Report discusses data obtained from measuring sideslip characteristics via the continuous-record method and the steady-record method. The situations in which each recording method is preferred are presented.
Date: August 1945
Creator: Johnson, Harold I.
System: The UNT Digital Library
Comparison of Structural Efficiencies of Diagonal-Tension Webs and Truss Webs of 24S-T Aluminum Alloy (open access)

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

"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 diagonal-tension beam" (p. 1).
Date: July 1945
Creator: Ochiltree, David W.
System: The UNT Digital Library
Comparison of tightness of 78 degrees machine-countersunk rivets driven in holes prepared with 78 degrees and 82 degrees countersinking tools (open access)

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

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.
System: The UNT Digital Library
Computation of the Mean Tangential Velocity of the Air Leaving the Blade Tips of a Centrifugal Supercharger (open access)

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

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
System: The UNT Digital Library
Critical Compressive Stress for Curved Sheet Supported Along All Edges and Elastically Restrained Against Rotation Along the Unloaded Edges (open access)

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

"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.
System: The UNT Digital Library
Cylinder-Head Cooling by Means of a Shield in the Exhaust Passage (open access)

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

"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.
System: The UNT Digital Library
A Description of the Ju 88 Airplane Anti-Icing Equipment (open access)

A Description of the Ju 88 Airplane Anti-Icing Equipment

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
System: The UNT Digital Library
Determination From Flight Tests of Thrust Coefficients for 10 Full-Scale Airplanes in the Gliding Condition With Engine Idling (open access)

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

"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 the flight tests" (p. 1).
Date: June 1945
Creator: Talmage, Donald B.
System: The UNT Digital Library
Determination of desirable lengths of Z- and channel-section columns for local-instability tests (open access)

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

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
System: The UNT Digital Library
Determination of Iron Contamination of Used Lubricating Oil for Use in Measuring Rates of Wear in Aircraft Engines (open access)

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

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.
System: The UNT Digital Library
Dilution of Exhaust-Gas Samples From a Multicylinder Engine Equipped With an Exhaust-Gas Collector (open access)

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

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.
System: The UNT Digital Library