Report discussing an investigation into the ability of human pilots to control short-period yawing oscillations using a yaw simulating device. The ability to control the oscillations was determined to be a function of period, control effectiveness, and inherent damping. Pilot control effectiveness was found to improve with practice.
Report discussing about 400 references pertaining to the hydrodynamic design of seaplanes have been compiled, and the information is presented in the form of abstracts classified under six main headings.
Qualitative investigations have shown that use of the NACA injection impeller with the R-3350 engine increases the inertia of the fuel-injection system and, when the standard fuel-metering system is used, this increase in inertia results in poor engine acceleration characteristics. This investigation was therefore undertaken to determine whether satisfactory acceleration characteristics of the engine equipped with the injection impeller could be obtained by simple modifications to the fuel-monitoring system. The engine was operated with two types of carburetor; namely, a hydraulic-metering carburetor incorporating a vacuum-operated accelerating pump and a direct-metering carburetor having a throttle-actuated accelerating pump. The vacuum-operated accelerating pump of the hydraulic-metering carburetor was modified to produce satisfactory accelerations by supplementing the standard air chamber with an additional 75-cubic spring. The throttle-actuated accelerating pump of the direct-metering carburetor was modified to produce satisfactory accelerations by replacing the standard 0.028-inch-diameter bleed in the load-compensator balance line with a smaller bleed of 0.0225-inch diameter. The results of this investigation indicated that both carburetors can be easily modified to produce satisfactory acceleration characteristics of the engine and no definite choice between the types of carburetor and accelerating pump can be made. Use of the direct-metering carburetor, however, probably resulted in better fuel distribution to the cylinders during the acceleration period and reduced the backfire hazard because all the fuel is introduced through the injection impeller.
Tests of a 1/7 size model of the Grumman XJR2F-1 amphibian were made in Langley tank no.1 to examine the landing behavior in rough water and to measure the normal and angular accelerations experienced by the model during these landings. All landings were made normal to the direction of wave advance, a condition assumed to produce the greatest accelerations. Wave heights of 4.4 and 8.0 inches (2.5 and 4.7 ft, full size) were used in the tests and the wave lengths were varied between 10 and 50 feet (70 and 350 ft, full size). Maximum normal accelerations of about 6.5g were obtained in 4.4 inch waves and 8.5g were obtained in 8.0 inch waves. A maximum angular acceleration corresponding to 16 radians per second per second, full size, was obtained in the higher waves. The data indicate that the airplane will experience its greatest accelerations when landing in waves of about 20 feet (140 ft, full size) in length.
A 1/5.5-size powered dynamic model of the Columbia XJL-1 amphibian was landed in Langley tank no. 1 in smooth water and in oncoming waves of heights from 2.1 feet to 6.4 feet (full-size) and lengths from 50 feet to 264 feet (full-size). The motions and the vertical accelerations of the model were continuously recorded. The greatest vertical acceleration measured during the smooth-water landings was 3.1g. During landings in rough water the greatest vertical acceleration measured was 15.4g, for a landing in 6.4-foot by 165-foot waves. The impact accelerations increased with increase in wave height and, in general, decreased with increase in wave length. During the landings in waves the model bounced into the air at stalled attitudes at speeds below flying speed. The model trimmed up to the mechanical trim stop (20 deg) during landings in waves of heights greater than 2.0 feet. Solid water came over the bow and damaged the propeller during one landing in 6.4-foot waves. The vertical acceleration coefficients at first impact from the tank tests of a 1/5.5-size model were in fair agreement with data obtained at the Langley impact basin during tests of a 1/2-size model of the hull.
An analytical investigation was made to determine from component performance characteristics the effect of air bleed at the compressor outlet on the acceleration characteristics of a typical high-pressure-ratio single-spool turbojet engine. Consideration of several operating lines on the compressor performance map with two turbine-inlet temperatures showed that for a minimum acceleration time the turbine-inlet temperature should be the maximum allowable, and the operating line on the compressor map should be as close to the surge region as possible throughout the speed range. Operation along such a line would require a continuously varying bleed area. A relatively simple two-step area bleed gives only a small increase in acceleration time over a corresponding variable-area bleed. For the modes of operation considered, over 84 percent of the total acceleration time was required to accelerate through the low-speed range ; therefore, better low-speed compressor performance (higher pressure ratios and efficiencies) would give a significant reduction in acceleration time.
An equation for quenching distance based on the destruction of chain carriers by the surface is derived. The equation expresses the quenching distance in terms of the diffusion coefficients and partial pressures of the chain carriers and gas phase molecules, the efficiency of the surface as a chain breaker, the total pressure of the mixture, and a constant which depends on the geometry of the quenching surface. Quenching distances measured by flashback for propane-air flames are shown to be consistent with the mechanism. The derived equation is used with the lean inflammability limit and a rate constant calculated from burning velocity data to estimate quenching distances for propane-air (hydrocarbon lean) flames satisfactorily.
A cascade impactor, an instrument for obtaining: the size distribution of droplets borne in a low-velocity air stream, was adapted for flight cloud droplet-size studies. The air containing the droplets was slowed down from flight speed by a diffuser to the inlet-air velocity of the impactor. The droplets that enter the impactor impinge on four slides coated with magnesium oxide. Each slide catches a different size range. The relation between the size of droplet impressions and the droplet size was evaluated so that the droplet-size distributions may be found from these slides. The magnesium oxide coating provides a permanent record. of the droplet impression that is not affected by droplet evaporation after the. droplets have impinged.
The report summarizes source material on combustion for flight-propulsion engineers. First, several chapters review fundamental processes such as fuel-air mixture preparation, gas flow and mixing, flammability and ignition, flame propagation in both homogenous and heterogenous media, flame stabilization, combustion oscillations, and smoke and carbon formation. The practical significance and the relation of these processes to theory are presented. A second series of chapters describes the observed performance and design problems of engine combustors of the principal types. An attempt is made to interpret performance in terms of the fundamental processes and theories previously reviewed. Third, the design of high-speed combustion systems is discussed. Combustor design principles that can be established from basic considerations and from experience with actual combustors are described. Finally, future requirements for aircraft engine combustion systems are examined.
This volume continues the NACA study of combustion principles for aircraft propulsion. The various aspects of combustion pertinent to jet engines are organized and interpreted with quite extensive information, particularly for basic or fundamental. subject matter. The report concerns only air-breathing engines and hydrocarbon fuels, and not rocket engines and high-energy fuels. Since the references have been selected to illustrate important points, the bibliographies, while thorough, are not complete. This volumes describes the observed performance and design problems of engine combustors of the principal types. These include combustor-inlet conditions; starting, acceleration, combustion limits, combustion efficiency, coke deposits, and smoke formation in turbojets; ram-jet performance; and afterburner performance and design.
From Summary: "About 500 additional references pertaining to hydrodynamic design of seaplanes have been compiled, and the information is presented in the form of abstracts classified under six main headings:GENERAL INFORMATION, HYDROSTATICS, HYDRODYNAMICS, AERODYNAMICS, OPERATION, and RESEARCH. The compilation is an extension of NACA RM No. L6I13, entitled "Abstracts Pertaining to Seaplanes," by Jerold M. Bidwell and Douglas A. King. An author index and a subject index are included."
From Introduction: "This report makes further comparisons of the theoretical computing method with available experimental results, showing effects of wing plan-form changes, and the effect of an airfoil-section change on a wing of given plan form."
From Introduction: "Reported herein are results of the additional direct-stress fatigue tests on: (1) a plate-type specimen with cored centrally located hole and (2) 0.300-inch-diameter round polished specimens with various degrees of porosity."
From Introduction: "The purpose of the present paper is to present results obtained recently relating to the characteristics of a full-span sharp-edge spoiler with an 0.02-chord projection above the wing surface at several chordwise positions and also to the relative effectiveness of the sharp-edge spoiler and a wedge-type spoiler located at the 80-percent-chord line."
From Introduction: "The results of an investigation of the low-speed static stability of a simplified model of such an arrangement having one of the airfoils placed vertically on top of the body and the other two as wing panels having negative dihedral are presented in reference 1. In order to provide information for predicting the effects of changes in the basic configuration on the low-speed stability characteristics presented in reference 1, additional measurements have been made."
Report discussing an aerodynamic control effectiveness study using free-flight, rocket-propelled test vehicles. Information about the effects of wing sweepback, aspect ratio, taper ratio, and section thickness ratio on the rolling effectiveness of full-span, sealed ailerons is provided.
From Introduction: "Presented in this report are the basic data obtained from investigation. The data are presented with limited analysis in order to expedite their availability to those concerned with jet-exit-afterbody design."
Additional results on the static longitudinal and lateral stability characteristics of a 0.05-scale model of the Convair F2Y-1 water-based fighter airplane were obtained in the Langley high-speed 7- by 10-foot tunnel over a Mach number range of 0.50 to 0.92. The maximum angle-of-attack range (obtained at the lower Mach numbers) was from -2 degrees to 25 degrees. The sideslip-angle range investigated was from -4 degrees to 12 degrees. The investigation included effects of various arrangements of wing fences, leading-edge chord-extensions, and leading-edge notches. Various fuselage fences, spoilers, and a dive brake also were investigated. From overall considerations of lift, drag, and pitching moments, it appears that there were two modifications somewhat superior to any of the others investigated: One was a configuration that employed a full-chord fence and a partial-chord fence located at 0.63 semispan and 0.55 semispan, respectively. The second was a leading-edge chord-extension that extended from 0.68 semispan to 0.85 semispan in combination with a leading-edge notch located at 0.68 semispan. With plus or minus 10 degrees aileron, the estimated wing-tip helix angle was reduced from 0.125 at a Mach number of 0.50 to 0.088 at a Mach number of 0.92, with corresponding rates of roll of 4.0 and 5.2 radians per second. The upper aft fuselage dive brake, when deflected 30 degrees and 60 degrees, reduced the rudder effectiveness about 10 to 20 percent and about 35 to 50 percent, respectively.
Report discussing the results of an investigation to determine the stability and control characteristics of a flying model of an unswept-wing vertically rising airplane. Information about stabilization, maneuverability, rolling motions, and landings is provided.
The adhesive and protective characteristics of National Bureau of Standards Coating A-417 were investigated, as well as the effect of the coating on the life of forged Refractaloy 26 and cast Stellite 21 turbine blades. Coated and uncoated blades were run in a full-scale J33-9 engine and were subjected to simulated service operations consisting of consecutive 20-minute cycles (15 min at rated speed and approximately 5 min at idle). The ceramic coating adhered well to Refractaloy 26 and Stellite 21 turbine blades operated at 1500 degrees F. The coating also prevented corrosion of the Refractaloy 26, a corrosion-sensitive nickel-base alloy, and of the Stellite 21, a relatively corrosion-resistant cobalt-base alloy. Although the coating prevented corrosion of both alloys, it had no apparent effect on blade life.
From Introduction: "In the present investigation, lift, drag, and pitching moment were determined over a Mach number range 0.6 to 1.42. Smooth-water takeoff and landing stability and resistance were investigated. A brief check of the rough-water spray and behavior was also made."
From Introduction: "The configuration described in this paper represents one approach to such an airplane and the results of the wind-tunnel and tank evaluations are presented. In the present investigation, the aerodynamic longitudinal characteristics over a Mach number range from 0.6 to 1.97 were obtained."
This report details a study that was conducted by the U.S. Naval Air Development Center to "determine the feasibility of several airborne magnetic mine-sweeping methods. The advantages of a satisfactory airborne method are greater safety and speed than are possible with existing surface methods." The configurations and results of the double Q-sweep, the modified double-catenary sweep, and the M-sweep are examined.
Report discussing an investigation into the lateral-control characteristics and the pitching-moment characteristics of a scale model of the X-1 wing-fuselage configuration. Information about the estimated variation of rolling effectiveness and wing-fuselage pitching-moment coefficient is described in detail.
From Introduction: "The investigation reported herein was initiated to define further the effects on the aerodynamic characteristics and load distribution of a thin, sweptback wing of a low-pressure blowing system and also to provide information on which to base a more thorough study of a complete airplane configuration."
Report discussing testing to determine the aerodynamic characteristics of two semispan delta-wing configurations. Information about the lift characteristics, drag characteristics, pitching-moment characteristics, and comparison with other results is provided.
Report discussing testing to determine the supersonic aerodynamic characteristics of four sweptback wings and wing-body configurations at several angles. Information about basic wing data, modifications to the 60 degree wing, the effects of sweep, and effects of fuselage are included.
Report discussing an investigation to determine the aerodynamic characteristics of hypersonic missile configurations with cruciform trailing-edge flaps with all-movable control surfaces. The all-movable controls were found to produce much larger values of trim lift and normal acceleration than the trailing-edge-flap configuration.
From Introduction: "The airfoil sections tested, which differ only in thickness ratio, were the NACA 64-006, 64-008, 64-010, and 641-012. Lift, drag, and pitching-moment data were obtained for Mach numbers of 0.3 to that for tunnel choke at angles of attack of -2^o to 31^o. The results of this investigation are reported herein."
An investigation has been made in the Langley low-turbulence pressure tunnel of the aerodynamic characteristics of the NACA 0012, 64(sub 2)-015, and 64(sub 3)-018 airfoil sections. Data were obtained at Mach numbers from 0.3 to that for tunnel choke, at angles of attack from -2deg to 30deg, and with the surface. of each airfoil smooth-and with roughness applied at the leading edge.The Reynolds numbers of the tests ranged from 0.8 x 10(exp 6) to 4.4 x 10(exp 6). The results are presented as variations of lift, drag, and quarter-chord pitching-moment coefficients with Mach number.
From Introduction: "The aerodynamic characteristics of a series of 10-foot-diameter propellers are being investigated in the Langley 16-foot high-speed tunnel in a comprehensive propeller research program. Using high-critical-speed NACA 16-series airfoil sections (reference 1), these propellers are designed to have Betz minimum induced-energy loss loading (reference 2) for a blade angle of 45^o at the 0.7 radius, when used as a four-blade propeller operating at an advance ratio of approximately 2.1 The ultimate purpose of the program is to determine the influence upon propeller design factors and of compressiblity; the propeller tests reported herein form part of the investigation of the effects of blade-section thickness ratio."
From Introduction: "The single purpose of this paper is to make available the data obtained from tests of these two Clark Y section propellers as quickly as possible with no attempt being made to analyze the results or to compare them with other high-speed-propeller test results."
Tests of two 10-foot-diameter two-blade propellers which differed only in shank design have been made in the Langley 16-foot high-speed tunnel. The propellers are designated by their blade design numbers, NACA 10-(5)(08)-03, which had aerodynamically efficient airfoil shank sections, and NACA l0-(5)(08)-03R which had thick cylindrical shank sections typical of conventiona1 blades, The propellers mere tested on a 2000-horsepower dynamometer through a range of blade-angles from 20deg to 55deg at various rotational speeds and at airspeeds up to 496 miles per hour. The resultant tip speeds obtained simulate actual flight conditions, and the variation of air-stream Mach number with advance ratio is within the range of full-scale constant-speed propeller operation. Both propellers were very efficient, the maximum envelope efficiency being approximately 0,95 for the NACA 10-(5)(08)-03 propeller and about 5 percent less for the NACA 10-(5)(08)-03R propeller. Based on constant power and rotational speed, the efficiency of the NACA 10-(05)(08)-03 propeller was from 2.8 to 12 percent higher than that of the NACA 10-(5)(08)-03R propeller over a range of airspeeds from 225 to 450 miles per hour. The loss in maximum efficiency at the design blade angle for the NACA 10-(5)(08)-03 and 10-(5)(08)-03R propellers vas about 22 and 25 percent, respectively, for an increase in helical tip Mach number from 0.70 to 1.14.
From Introduction: "The present paper contains the results of the investigation of the aerodynamic characteristics at Mach number of 2.01 of the two cruciform wing missiles equipped with larger canard controls and compares the result with that obtained previously with a smaller control."
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