Technical Report Archive & Image Library (TRAIL) - 116 Matching Results
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- The Knock-Limited Performance of Fuel Blends Containing Spiropentane, Methylenecyclobutane, Di-Tert-Butyl Ether, Methyl Tert-Butyl Ether, and Triptane
- Tests show that at inlet-air temperatures of 250 deg F and 100 deg F the knock-limited performance of the base fuel of blends, leaded with 4 ml TEL per gallon and containing 20 percent spiropentane, was reduced at fuel/air ratios below 0.085. The 20 percent methylenecyclobutane reduced the knock-limited power of the base fuel at fuel/air ratios below 0.112. Di-tert-butyl ether, methyl-tert-butyl ether, and triptane increased the knock-limited power of the base fuel at all fuel/air ratios and at both temperatures.
- Effects of Fuel-Vapor Loss on Knock-Limited Performance and Inspection Properties of Aviation Fuels
- Report discussing the results of testing to discover the effects of fuel-vapor loss on F-3 and F-4 knock-limited performance ratings and inspection properties of two aviation fuels, 28-R and 33-R. The percentage of loss at several temperatures, ability to meet Army-Navy fuel specifications, and antiknock rating change is described.
- 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).
- 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."
- Lead Susceptibility of Several Fuels as Determined in an Air-Cooled Aircraft-Engine Cylinder
- "In order to determine the lead susceptibility of several fuels, leaded and unleaded fuels from the same stock were blended and tested in a full-scale air-cooled aircraft-engine cylinder. The fuels were S-4 reference fuel, virgin-base stock, aviation alkylate, neohexane, and blends of 25-percent benzene with 75-percent virgin-base stock and 25-percent toluene with 75-percent virgin-base stock" (p. 1).
- Static-Pressure Error of an Airspeed Installation on an Airplane in High-Speed Dives and Pullouts
- "Tests were made in high-speed dives and pull-outs to determine, by combined radar-optical tracking equipment, the static-pressure error of an airspeed-head installation on a P-51B airplane." The equipment used and testing procedure are described. The variation of static-pressure error is provided for several ranges of airplane lift coefficient.
- Variation of Hydrodynamic Impact Loads With Flight-Path Angle for a Prismatic Float at 6 Degrees and 9 Degrees Trim and a 22-1/2 Degree Angle of Dead Rise
- Report discusses the results of testing "to determine the relationship between impact normal acceleration and flight-path angle for seaplanes landing in smooth water" (from Summary). The tests were done at high and low forward speeds and trims at 6 degrees and 9 degrees, a 22.5 degree angle of dead rise, and a gross weight of 1100 pounds. Information about the forces acting on the aircraft and maximum depth of immersion and trim is provided.
- Variation of Hydrodynamic Impact Loads With Flight-Path Angle for a Prismatic Float at 12 Degree Trim and With a 22-1/2 Degree Angle of Dead Rise
- Report discusses the results of testing "to determine the relationship between impact normal acceleration and flight-path angle for seaplanes landing on smooth water" (from Summary). The tests were performed at 12 degrees trim, 22.5 degree angle of dead rise, and a total weight of 1100 pounds. The effect on the maximum impact normal acceleration and the effects of immersion on acceleration are described.
- A Method for the Determination of Aromatics in Hydrocarbon Mixtures
- Bulletin discusses a method to estimate aromatic hydrocarbons in hydrocarbon mixtures, which is important for determining the percentage of aromatics in fuel blends. The method was tested with nine base stocks at several levels of aromatics concentration and the maximum level of error was found to be about 0.5 percent. The speed and simplicity of the testing is emphasized.
- The Knock-Limited Performance of S Reference Fuel Plus 2 Milliliters of Triethylthallium Per Gallon
- Report discusses the results of testing of thallium as an antiknock agent in an internal-combustion engine. From Introduction: "On a weight basis, the thallium vapors were found to have several times the antiknock value of tetraethyl lead, which was added to the fuel. The amount of thallium vapor necessary to raise the antiknock properties of a gasoline up to exact equivalence with a benzol-gasoline mixture was determined in these engine tests."
- Use of Variable-Ratio Geared Tabs to Improve Stick-Force Characteristics in Turning Flight
- Report discussing the use of variable-ratio geared tabs with an experimental elevator to improve stick-force characteristics in turning flight. The stick forces with the tabs were found to be satisfactory for a variety of center-of-gravity ranges. The ability of pilots to use the controls is also described.
- 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).
- 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.
- 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.
- 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.
- Effect of Variation in Diameter and Pitch of Rivets on Compressive Strength of Panels With Z-Section Stiffeners 1 - Panels With Close Stiffener Spacing That Fail by Local Buckling
- An experimental investigation is being conducted to determine the effect of varying the rivet diameter and pitch on the compressive strength of 24S-T aluminum-alloy panels with longitudinal Z-section stiffeners. The average stress at failing load for each rivet diameter, depth of countersink, and pitch of rivet is provided
- 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).
- Pressure Lag in Tubing Used in Flight Research
- "Tests described in this report were undertaken to obtain a quantitative measure of the pressure lag in typical pressure-tubing systems used by the Ames Aeronautical Laboratory in flight research investigations. Lag measurements were made with both single-direction and oscillating pressure changes. Single-direction pressure changes were investigated to determine if the lag in orifice-pressure lines and in the research airspeed and altitude measuring systems of pursuit-type airplane undergoing flight tests was sufficient to cause an appreciable error in the record of a sudden pressure change" (p. 1).
- Tables and Charts for the Evaluation of Profile Drag From Wake Surveys at High Subsonic Speeds
- Report presents tables and charts for the evaluation of profile drag from wake surveys at high supersonic speeds. Two methods of evaluation are presented: an exact method that can be used on a wake of any shape and a simple approximate method that can be used when the variation of total-pressure loss across the wave has a typical form.
- Theoretical and Experimental Dynamic Loads for a Prismatic Float Having an Angle of Dead Rise of 22-1/2 Degrees
- Report discusses the maximum load, time to reach maximum load, and variation of load with time for prismatic floats in order to improve understanding of hydrodynamic theory for the landing impact of seaplane floats. Comparison of theoretical and experimental results and their applicability to flight impact are provided.
- 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).
- Fuel-Evaporation Loss as Determined by the Change in the Specific Gravity of the Fuel in an Aircraft Fuel Tank
- Report discusses the results of an investigation to determine the feasibility of using the change in the specific gravity of fuels in aircraft fuel tanks to measure fuel-vaporization loss. Six fuels were tested via fuel-distillation tests and simulated-flight tests. An equation based on the specific gravity of the fuel is also described.
- Investigation of Methods of Supporting Single-Thickness Specimens in a Fixture for Determination of Compressive Stress-Strain Curves
- "An investigation was made of the methods of supporting single-thickness specimens of aluminum-alloy sheet material in a fixture for determination of compressive stress-strain curves. The specimens were supported in the fixture by rollers, offset-grooved plates, opposite-grooved plates, flat brass plates, or flat wooden plates. The investigation also showed that the compression fixture, the specimen support, and the single-thickness specimens must be accurately made in order to obtain accurate stress-strain curves consistently" (p. 1).
- Effects of Compressibility and Large Angles of Yaw on Pressure Indicated by a Total-Pressure Tube
- Report discusses the effects of compressibility and angle of yaw on the pressure measured by a round-nose and a flat-nose total-pressure tube. The error incurred in the pressure measurements and factors affecting the total-pressure area are described.
- 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.
- A Preignition Indicator for Aircraft Engines
- Report describes an electrical-relay circuit that uses cylinder thermocouples for indicating preignition or misfiring in an aircraft engine. The potential dangers of preignition and the importance of an easy-to-use, practical preignition indicator are provided. The operating principles of the indicator and a description of its functioning, calibration, and installation procedures are also included.
- The Use of Geared Spring Tabs for Elevator Control
- Report discussing the use of two types of geared spring tabs for elevator control: ordinary (or ungeared) spring tabs and geared spring tabs. Their use in airplanes of various sizes and in comparison to conventional control systems is described.
- Variation of Hydrodynamic Impact Loads With Flight-Path Angle for a Prismatic Float at 3 Degree Trim and With a 22 1/2 Degree Angle of Dead Rise
- Report discusses the results of testing "to determine the relationship between impact normal acceleration and flight-path angle for seaplanes landing on smooth water" (from Summary). The testing was done with a model at high and low forward speeds at 3 degrees trim, a dead-angle rise of 22.5 degrees, and consistent weight.
- XC-35 Gust Research Project Characteristics of Vertical Drafts and Associated Vertical Gust Velocities Within Convective Type Clouds
- Report discusses the results of measurements made via an XC-35 airplane to determine the relation between the velocities of vertical drafts and associated gusts within convective-type clouds. Information about vertical-draft velocity and maximum vertical true gust velocity is included.
- Material Properties of Two Types of Plastic-Bonded Glass Cloth
- Report discusses the results of tensile and compressive tests of two types of plastic-bonded glass cloth and their potential use in aircraft construction. The ultimate tensile stress and compressive yield stresses for the different materials are provided.
- Effect of Lateral Shift of Center of Gravity on Rudder Deflection Required for Trim
- 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.
- An Estimation of the Internal-Cooling Requirements of an Aircraft-Engine Cylinder When Using Oxygen Boost
- Report discusses a method developed to estimate the quantities of internal coolants required to prevent overheating of the aircraft cylinder when oxygen boost is applied. The formula and calculations related to inlet-air pressure, added oxygen, added water, added nitrogen, and total fluid weight are detailed.
- Flight Investigation at High Mach Numbers of Several Methods of Measuring Static Pressure on an Airplane Wing
- Report discusses an investigation into static pressures in subsonic and supersonic flow over an airplane wing as measured by static-pressure tubes, a static-pressure belt, and orifices flush with the wing surface. The results obtained from the three types of measuring devices and a comparison to theoretical calculations are presented.
- The Knock-Limited Performance of Several Fuels Blended With S-2 Reference Fuel
- Report discussing the results of testing conducted to determine the knock-limited performance of fuel blends containing 80 percent of S-2 reference fuel and 20 percent of several exploratory fuels. Butyl acetate, sec-butyl acetate, isopropyl acetate, sec-butyl alcohol, tert-butyl alcohol, isopropyl alcohol, cyclohexanol, methylcyclohexanol, isobutylcarbinol, sec-butylcarbinol, triethyl borate, and dimethylfuran were examined.
- Preliminary Investigation of the Relation of the Compressive Strength of Sheet-Stiffener Panels to the Diameter of Rivet Used for Attaching Stiffeners to Sheet
- Report discusses the results of compressive testing of 24S-T aluminum-alloy sheet-stiffener panels with five ratios of stiffener thickness to sheet thickness. For each ratio, rivets of five different diameters were used to attach the stiffeners to the sheets. The compressive strengths were found to increase with an increase in the diameter of the rivets until the ratio of rivet diameter to over-all thickness reached a certain point.
- 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."
- Relative Effects of Cylinder-Head and Inlet-Mixture Temperatures Upon Knock Limits of Fuels
- Report discusses an investigation into the relation between the effects of cylinder-head temperature and inlet-mixture temperature on the knock limits of fuels. The tests were run at a constant fuel-air ratio and the decrease in cylinder-head temperature required to offset the effect of increasing the inlet-mixture temperature on knock-limited power was determined. The apparatus and testing procedure are described and the effect of changes in cylinder-head temperature on the knock limit of any fuel are plotted.
- Spinning of Large Airplanes
- Report discusses the problem of large airplanes spinning and the fact that they should not be intentionally spun because they are not designed for the loads and speeds that may be encountered in spin and recovery. Stall and spin characteristics for large airplanes are described. Recommended piloting procedures in case of a large airplane spinning event are also provided.
- Early Detection of Cracks Resulting From Fatigue Stressing
- Report discusses an apparatus that may be used for indicating the formation of fatigue cracks or for following the progress of cracks. Details of the experiment and discussion of the way in which the deflection-crack area relationship may be used to monitor fatigue cracks are included.
- The Effect of Angle of Bend Between Plate Elements on the Local Instability of Formed Z-Sections
- "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).
- End-zone water injection as a means of suppressing knock in a spark-ignition engine
- Report discusses the results of an investigation into the effectiveness of water injection into the combustion end zone of a spark-ignition engine cylinder for the suppression of knock. The injection angle was found to be very important for obtaining maximum results. The results of various angles and amounts of water were examined.
- A Positive-Replica Technique for Examining Finished Metal Surfaces and Its Application to Aircraft Engine Cylinders
- Report discusses a method of replica creation and testing of the surface-finish variation of aircraft engine parts subject to wear. In this report, a positive replica is created, the surface is treated, the replica is tested to make sure the fidelity is high enough, and a series of ring-sticking tests are conducted on the replicas. A summary of the results of the testing is also included.
- 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."
- An Electronic Indicator for Angular Velocity and Acceleration
- "An electronic circuit for instantaneously indicating angular velocity and acceleration, both positive and negative, of rotating masses is described; readings are taken on electrical indicating meters. The indicator is described in terms of general application. A circuit diagram, calibration curves, and a mathematical analysis of the differentiation circuit are included" (p. 1).
- Notes on Unusual V-G Records From Transport Airplanes
- Report discusses some unusual velocity-acceleration records on transport airplanes, which the report defines as "records of accelerations experienced in flight that resulted from causes other than atmospheric gusts" (from Summary). The analysis of the records, which is required for determining proper classification, is described, and the sorting of the records into gust- or maneuver-related is described. The report also discusses the importance of receiving this data from flight operators in addition to the routine information they provide.
- Use of Water Injection to Decrease Gasoline Consumption in an Aircraft Engine Cruising at High Power
- Report discusses the results of testing water injection on a multicylinder aircraft engine and the potential fuel savings from the procedure. The speeds at which water injection for engine cooling is beneficial are illustrated and information about the manifold pressures and average rear spark-plug-gasket temperatures are also included.
- Method of Mounting Cylinder Blocks of in-Line Engines on CUE Crankcases
- Report describes the installation of six-cylinder blocks from two in-line aircraft engines on CUE crankcases, which permits the separate operation of any cylinder as part of a single-cylinder test engine. Using multicylinder-engine blocks for single-cylinder tests is advantageous because there is greater availability of standard engine parts and there is less temperature gradient. Modifications of the crankcase, camshaft-drive mechanism, and operation of the cylinder are described.
- 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).
- 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).
- An Investigation of the Characteristics of a Propeller Alcohol Feed Ring
- Report discusses the results of an investigation to compare the discharge characteristics of an alcohol feed ring and a standard alcohol discharge nozzle when utilized to supply anti-icing alcohol to the propeller-blade feed shoes on a Curtiss-Wright C-46 cargo airplane. The equipment used, testing practices, and results of the alcohol flow distribution are described.