Report presenting tunnel-wall corrections for an airfoil of finite thickness and camber in a two-dimensional-flow wind tunnel. The theory takes account of the effects of the wake of the airfoil and of the compressibility of the fluid and is based on the assumption that the chord of the airfoil is small in comparison with the height of the tunnel. The theoretical results are compared with the small amount of low-speed experimental data available and agreement is seen to be satisfactory, even for relatively large values of the chord-height ratio.
Report discusses the variation of surface-ignition temperature with charge density, fuel-air ratio, and surface-ignition advance. Tests on several fuels were conducted on a supercharged CFR engine to determine surface-ignition temperature as a function of the three variables. It was concluded that surface-ignition temperature is not a satisfactory criterion for differentiating between preignition characteristics of different fuels.
Report presenting the knock-limited performance of nine fuels comprising isolated members of four classes of hydrocarbons in the form of three-dimensional plots of fuel-air ratio, compression temperature, and compression-air density.
Report presenting tests in the 4- by 6-foot vertical wind tunnel of an NACA 0009 airfoil with a 30-percent-chord flap with a small amount of aerodynamic balance. In the investigation, the effect of balance nose shape and gap at the nose of the flap has been determined. The results indicate that, in general, the lift effectiveness of the flap was unaffected by the addition of a small amount of aerodynamic overhang, and the balance effectiveness of the flap was increased.
Report presenting tests made in the 4- by 6-foot vertical wind tunnel of an NACA 0009 airfoil with a 30-percent-chord flap with a medium amount of aerodynamic overhanging balance. In this investigation, the effects of the shape of the flap-nose overhang and the gap at the nose of the flap have been determined. The results indicate that, generally, the lift effectiveness of the aerodynamically balanced flap was increased slightly over that of a plain flap when a blunt or medium flap nose was used on the balanced flap.
Report presenting direct-reading tables and charts for determining the drag or thrust coefficients from wake-survey measurements in the subsonic speed range. Additionally, numerical examples are provided using information from the tables.
Report presenting results from a series of flight tests of the maximum speed and cooling characteristics in full-throttle level flight of the XP-42 airplane equipped with a short-nose high-inlet velocity cowling. The results of the tests indicated a maximum speed of 336 miles per hour at 960 horsepower at 25,000 feet. Results regarding maximum speed and pressure and temperatures are provided.
Report presenting data on the rolling accelerations of airplanes of different types and sizes in abrupt aileron rolls in connection with a number of maneuverability and flying qualities investigations. An analysis was made to determine the relation between the torque applied to the aileron system by the pilot, the motion of the system, and the subsequent rolling motion of the airplane in abrupt aileron roll.
Report presenting the results of a series of flight tests of the maximum speed and cooling characteristics in high-speed level flight and in climb of the XP-42 airplane equipped with a long-nose high-inlet-velocity cowling. The results indicated that a maximum speed of 338 miles per hour at 870 horsepower at 17,000 feet was achievable, which is above the engine critical altitude. Pressure measurements in the entrances in the cylinder baffles showed a uniform distribution of pressure on the front of the engine in high-speed level flight and a fairly uniform distribution in full-power climb.
Report presenting computations made to determine the effect of changes in wing aspect ratio, additional side area, flight-path angle, and normal acceleration on the relation between the fin area and the dihedral angle required for spiral and for oscillatory lateral stability for a hypothetical airplane of the pursuit or fighter categories. The diagrams indicate that the effect of wing aspect ratio on lateral stability is small.
"General relationships for the lead susceptibilities of paraffins, cycloparaffins, and olefins are presented. Methods are described by which the lead response may be estimated for these hydrocarbon classes, whether the lead response is indicated by octane number, critical compression ratio, or indicated mean effective pressure as limited by knock" (p. 1).
Report presenting an investigation made on a supercharged CFR engine to determine a method for estimating lead susceptibilities of pure or blended paraffinic fuels. As a result of these studies, a chart consisting of a series of straight lines passing through the origin was developed to represent the lead susceptibilities of pure and blended paraffinic fuels in terms of knock-limited indicated mean effective pressures and octane numbers.
"The effect on the propulsive efficiency of locking or windmilling one propeller of a six-blade dual-rotating propeller installation was determined in the Langley propeller-research tunnel. Tests were made of both pusher and tractor configurations, with the unpowered propeller both leading and following the powered propeller, which was set at a blade angle of 40 degrees. The maximum propulsive efficiency of the powered propeller in combination with the locked or windmilling propeller was, in all cases, lower than that of the powered propeller operating alone" (p. 1).
An investigation was conducted to determine and compare the tensile strength of NACA and conventional machine-countersunk flush rivets of several rivet-head angles and varying countersunk depth. The results of the investigation are presented in the form of curves that show the variation of the tensile strength of the rivet with the ratio of the sheet thickness to the rivet diameter. For the same rivet-head angle and for a given angle of c/d, the NACA rivets developed higher tensile strength than the conventional rivets.
Report presenting an exact solution and a closely concurring approximate energy solution for the buckling of an infinitely long flat plate under combined shear and transverse direct stress with edges elastically restrained against rotation. An appreciable fraction of the critical stress in pure shear may be applied to the plate without any reduction in the transverse compressive stress necessary to produce buckling.
Report presenting a theoretical investigation of the buckling of an infinitely long flat plate with edges elastically restrained against rotation under combinations of longitudinal and transverse direct stress. Interaction curves are presented that give the critical combinations of stress for several different degrees of elastic edge restraint, including simple support and complete fixity.
"This report describes tests in the Langley 16-foot high-speed tunnel to determine whether these failures could be attributed to changes in the aerodynamic characteristics of the ailerons at high speeds" (p. 1).
Report presenting an investigation of the possibility of using internal cooling instead of fuel enrichment to suppress knock and to estimate the fuel savings that will result. Data from four different sources was examined and an analysis of the fuel consumption was conducted. Four different types of coolants were explored.
Report presenting an axial flow fan tested with 5, 9, 12, 18, and 24 blades and with two different blade sections. The range of contravane angle and blade angle without contravanes was extended past results published for the same fan previously.
Report presenting an investigation of the characteristics of air scoops in the NACA propeller-research tunnel. The investigation showed that, at inlet-velocity ratios equal to or greater than 0.3, scoops in a forward position on the fuselage gave total pressures in the inlet nearly equal to free-stream total pressure.
Report presenting a dual-rotation axial-flow fan composed of two oppositely rotating 24-blade rotors. The fan was tested with various combinations of front and rear blade angles and with two combinations of front and rear solidities. For quantity coefficients above 0.3 the greatest pressure rise was obtained from 24 blades in each rotor with the blades adjusted to absorb equal torque at maximum pressure.
Report presenting a series of models of flying-boat hulls tested to determine the effects of the angle of dead rise and the angle of afterbody keel on resistance and spray characteristics. Three angles of dead rise and three angles of afterbody keel were investigated. The results are expressed in nondimensional coefficients.
Report presenting an investigation of the effect of changes in the length-beam ratio of flying-boat hulls on resistance and spray. A family of three models of hulls of different length-beam ratios was used and, in order to maintain comparable hull sizes, the plan-form areas of the hulls were made approximately equal by keeping equal products of length and beam. Results regarding resistance, spray, and take-off performance are provided.
Report presenting an investigation to determine the knock-limited power obtainable by injecting water solutions of monomethylamine and dimethylamine as internal coolants into a CFR engine using AN-F-28, Amendment-2, fuel.
Report presenting an investigation to develop an instrument for the determination of rain densities in this range in flight. The major requirements for the instrument are ease of operation, minimum weight and bulk, rapid response, and simplicity of installation.
Report presenting testing to determine the influence of propeller rotation and vertical-tail design on the trim characteristics of a model of a twin-engine airplane with one engine inoperative. The tests showed that the effect of mode of propeller rotation on the directional trim characteristics of the model operating with asymmetric power was considerable. Results regarding the effect of mode of propeller rotation and effect of vertical-tail design are provided.
Report presenting an investigation to determine the nature and extent of the reversal of flow, which occurs at the inlet of centrifugal superchargers over a considerable portion of the operating range. Results regarding lampback patterns, tuft studies, backflow surveys, and effect of impeller tip speed on backflow are provided.
Porpoising characteristics were observed on V-body fitted with tail surfaces for different combinations of load, speed, moment of inertia, location of pivot, elevator setting, and tail area. A critical trim was found which was unaltered by elevator setting or tail area. Critical trim was lowered by moving pivot either forward or down or increasing radius or gyration. Increase in mass and moment of inertia increased amplitude of oscillations. Complete results are tabulated and shown graphically.
Report presenting methods and charts for computing stability derivatives of a longitudinally straight V-bottom planing surface representing the forebody of a seaplane float or a flying-boat hull without chine flare. The charts for computing hydrodynamic derivatives were used in calculating the trim limit of stability for angles of dead rise of 10, 20, and 30 degrees.
"Tank tests were made of a flying-boat model having various types of fairing with and without ventilation ducts behind the main step to investigate the hydrodynamic characteristics of the model. All the types were designed to reduce significantly the air drag chargeable to the main step. The configuration that combined the best stability with a good aerodynamic form consisted of a shallow step and an adjoining ventilation aperture having an area about 7 percent of the square of the beam" (p. 1).
Report presenting porpoising tests of three rudimentary models composed of two V-bottom planing surfaces in tandem and fitted with a tail plane. The upper and lower branches of the upper trim limit of stability were determined for three angles of dead rise and two depths of step.
Report presenting data pertaining to forces and moments developed by V-bottom planing surfaces of different angles of dead rise in order to compute the effect of dead rise on the lower trim limit of stability on a seaplane. Increase of angle of dead rise in the range of 10 degrees to 30 degrees causes an important increase in the lower limit of stability.
Report presents and discusses the improvements in hydrodynamic and aerodynamic performance of a seaplane with a retractable planing flap instead of a conventional main step. A type of flap that could be used is described and tested for hydrodynamic stability. Results regarding the trim limits of stability, limiting positions of the center of gravity, and skipping are provided.
"As part of an investigation of the cooling characteristics of liquid-cooled engines, tests were conducted with an electrically heated single-tube heat exchanger to determine the heat-transfer characteristics of AN-E-2 ethylene glycol and other ethylene glycol-water mixtures. Similar tests were conducted with water and commercial butanol (n-butyl alcohol) for check purposes. The results of tests conducted at an approximately constant liquid-flow rate of 0.67 pound per second (Reynolds number, 14,500 to 112,500) indicate that at an average liquid temperature 200 degrees f, the heat-transfer coefficients obtained using water, nominal (by volume) 30 percent-70 percent and 70 percent-30 percent glycol-water mixtures are approximately 3.8, 2.8, and 1.4 times higher, respectively, than the heat-transfer coefficients obtained using an-e-2 ethylene glycol.
Report presenting testing of models of three flying-boat hulls with a length-beam ratio of 10.5. Testing occurred at two depths of step and two angles of dead rise. Results regarding resistance, trimming-moment, and wetted-length data for general fixed-trim and free-to-trim tests at load coefficients up to 4.0 are provided.
Report presenting tests to study the effectiveness of small pressure differences in removing the dust boundary layer through slots in the duct wall of airplane ducts and reducing separation losses. Two-dimensional diffusers of 15 and 30 degrees included angles and some 90 degree bends were tested. The 30 degree diffuser was tested with and without an intercooler.
"The results are given of an investigation of some of the limitations that now prevent increases in the temperature level of engine cylinder heads, and a review of previous work in the field is included to supplement these results. Attention was given, in particular, to the effects of fuel knock and surface ignition on cylinder temperatures and the effects of cylinder temperatures on performance. Data were obtained from a Wright C9GC air-cooled cylinder and from a Lycoming O-1230 liquid-cooled cylinder" (p. 1).
Report presenting testing to determine the effect of special baffles on the temperatures and cooling-air requirements of the Wright 1820 G200 and R-2600-8 cylinders. Nine baffles were tested with the 18020 cylinder and two were tested with the R-2600-8 cylinder. Results indicated that the internal cylinder surfaces with good thermal connection with the external-cooling means respond to changes in external cooling.
Report presenting testing at two engine speeds on six representative fuels rated at 100-octane number by the C.F.R. aviation method. Blends of the fuels with benzene, toluene, xylene, and isopropyl comprise nine other fuels, leading to testing on 15 fuels. Results regarding the tests at 2000 rpm and 250 degrees Fahrenheit inlet-air temperature, at 3100 rpm and 250 degrees Fahrenheit inlet-air temperature, 2000 rpm and 150 degrees Fahrenheit inlet-air temperature, and 3100 rpm and 150 degrees Fahrenheit inlet-air temperature, effect of speed on knock rating, effect of inlet-air temperature on knock rating, and effect of spark advance on knock rating are provided.
Problem of improving thrust at low speeds is primarily one of reducing angle of attack of operation of sections to improve L/D or reducing blade helix angle. An analysis, based on recent propeller data, is presented for determining improvements in thrust or efficiency which could be obtained by increased number of blades, increased blade width, increased diameter, dual rotation, and two-speed gearing. All methods were found very effective, particularly two-speed gearing.
Tests of 10-ft. diameter, eight-blade, single - and dual - rotating propellers were conducted in 20-ft propeller research tunnel. Propellers were mounted at front end of a streamline body in spinners that covered hubs and parts of shanks. Effect of a symmetrical wing mounted in slipstream was investigated. Blade-angle settings ranged from 20 Degrees to 65 Degrees. Results indicated that dual rotation resulted in gains of from 1 to 8 percent in efficiency over single rotation for eight-blade propellers, but presence of a wing reduced gain about one-half. Greater power absorption caused by dual rotation over flight range and higher efficiency or thrust for range of take-off and climb was indicated.
Report presenting tests of 10-foot diameter, single- and dual-rotating tractor propellers with two to eight blades conducted in the 20-foot propeller-research tunnel. The blades were 50 percent wider than those used in previous investigations. Results regarding the effect of dual rotation and effect of solidity are provided.
Report presenting the application of transient theory to the rational determination of dynamic loads on airplane structures during initial landing impact. Simplified procedures are described by which the distribution of the maximum attainable value of the dynamic stresses in the structure may be obtained.
Report discusses an investigation into the tensile strength of cast-iron piston rings, NACA microtensile specimens, and bar specimens. Photographs showing the relation between graphite-flake size and tensile strength and radiographs showing the shrinkage cavities in the piston rings are provided. Piston rings tend to be one of the first parts of an aircraft engine to fail, so discovering the ideal material composition and foundry treatment is very important.
Report presenting a consideration of the performance of sliding surfaces, such as piston rings, cylinders, journals, and bearings in aircraft engines with reference to the surface characteristics that they possess before and after running-in, prior to service operation. The phenomena accompanying the running-in process are analyzed.
"The lubrication of a piston ring is treated as though the ring were a rigid slider of finite width. An expression is obtained for pressure distribution which takes into account the effect of oil leakage from the ends of the ring and which has the convenient form of an end correction to the pressure-distribution formula for an infinite slider. The important formulas are summarized for convenience and two examples are included of their use in finding the pressure pattern over wide sliders" (p. 1).
Report presenting an investigation which found that the absolute viscosity of exhaust gases from a gasoline engine was measured at a range of temperatures and compositions. Results regarding preliminary runs, calibration runs at room temperature, check runs at medium temperatures, and exhaust gas measurements are provided.
Report presenting a determination of the mean effective emissivity as a function of temperature for the surfaces of several metals and insulating materials. A description and discussion of the measuring technique is presented. The results are plotted on a variety of graphs.
Report presenting an analysis of the thermopile radiometer as used in the measurement of irradiation and radiant power interchange is given. The theory of the instrument when used to measure irradiation and net radiant power interchange is developed, and the precautions to be observed when using it for these measurements are presented.
Report presenting performance data on a small exhaust gas and air heat exchanger. The heat transfer rates were measured using about 8000 pounds per hour of exhaust gas and 4300 pounds per hour of ventilating air. The thermal performance of heater no. 2 can be estimated to 3 to 17 percent by use of the method described in the report.
This dialog allows you to filter your current search.
Each of the Serial/Series Titles listed note their name and the number of records that will be limited down to if you choose that option.
This dialog allows you to filter your current search.
Each of the World Regions listed note their name and the number of records that will be limited down to if you choose that option.
This dialog allows you to filter your current search.
Each of the Countries listed note their name and the number of records that will be limited down to if you choose that option.
This dialog allows you to filter your current search.
Each of the U.S. States listed note their name and the number of records that will be limited down to if you choose that option.
This dialog allows you to filter your current search.
Each of the Counties listed note their name and the number of records that will be limited down to if you choose that option.
This dialog allows you to filter your current search.
Each of the Years listed note their name and the number of records that will be limited down to if you choose that option.
The list can be sorted by name or the count.
This dialog allows you to filter your current search.
Each of the Months listed note their name and the number of records that will be limited down to if you choose that option.
The list can be sorted by name or the count.
This dialog allows you to filter your current search.
Each of the Days listed note their name and the number of records that will be limited down to if you choose that option.