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Acoustic, thrust, and drag characteristics of several full-scale noise suppressors for turbojet engines
From Introduction: " Considerable analytical and experimental research has been done to find means of reducing the noise levels of the turbojet transports. Noise levels can be decreased by engine redesign to reduce the jet-exit velocity (ref. 1), proper flight-climb techniques (ref. 2), and the use of noise-suppression exhaust nozzles (refs. 3 to 5). The present report is concerned with the last method."
Date:
April 1958
Creator:
Ciepluch, Carl C.; North, Warren J.; Coles, Willard D. & Antl, Robert J.
System:
The UNT Digital Library
Analysis of harmonic forces produced at hub by imbalances in helicopter rotor blades
From Introduction: "First, an analysis of loads transmitted to the hub by balanced blades will be given. In the second section, the additional loads transmitted to the hub in a direction normal to the plane of rotation of the blades by imbalances in a rotor are derived. In the entire analysis, the results are given in terms of the forces transmitted to the hub by a single rotating helicopter blade in flight, and these are regarded as known or given."
Date:
April 1958
Creator:
Morduchow, M. & Muzyka, A.
System:
The UNT Digital Library
Analysis of Turbulent Flow and Heat Transfer on a Flat Plate at High Mach Numbers With Variable Fluid Properties
From Introduction: "In the turbulent case, however, the results of the various analyses disagree markedly because of the different assumptions made by various authors. These analyses are reviewed in references 1 to 3. The analysis is extended to flow and heat transfer in a boundary layer at high Mach numbers in this paper. (Some preliminary results were presented in ref. 11.)"
Date:
April 1958
Creator:
Deissler, R. G. & Loeffler, A. L., Jr.
System:
The UNT Digital Library
An Approximate Method for Design or Analysis of Two-Dimensional Subsonic-Flow Passages
Note presenting a method for the design and analysis of two-dimensional subsonic-flow passages with isentropic nonviscous flow. The method is based on the relation between the pressure change across a stream tube and the centrifugal force resulting from the curvature of the flow. In an example, the method was applied to the design of an expanding elbow at each of two Mach numbers.
Date:
April 1958
Creator:
Valentine, E. Floyd
System:
The UNT Digital Library
Central Automatic Data Processing System
A series of papers describing a system that will automatically record as many as 300 pressures, 200 voltages, and 24 frequencies in as little as 30 seconds to an accuracy of 0.15 percent or better of full-scale range. The information is able to be used in any high-speed, general-purpose digital computer. The computer will accept the encoded data produced by the recording system and automatically calibrates it, takes averages, forms ratios, and does terminal calculations such as mass flow, momentum, distortion numbers, drag coefficients, thrust, specific fuel consumption, and efficiency.
Date:
April 1958
Creator:
Staff of the Lewis Laboratory
System:
The UNT Digital Library
Composition and thermodynamic properties of air in chemical equilibrium
"Charts have been prepared relating the thermodynamic properties of air in chemical equilibrium for temperatures to 15,000 degrees k and for pressures 10(-5) to 10 (plus 4) atmospheres. Also included are charts showing the composition of air, the isentropic exponent, and the speed of sound. These charts are based on thermodynamic data calculated by the National Bureau of Standards" (p. 1).
Date:
April 1958
Creator:
Moeckel, W. E. & Weston, Kenneth C.
System:
The UNT Digital Library
Discharge coefficients for combustor-liner air-entry holes 2: flush rectangular holes, step louvers, and scoops
Experimental discharge coefficients for various types of combustor-liner air-entry holes are presented as a function of a dimensionless flow parameter. In general, scoops and step louvers have higher discharge coefficients and wider flow ranges than flush holes. The effects of size or shape of a given type of hole are small. The proximity of multiple flush holes or the wall inclination of a convergent duct has a negligible effect on discharge coefficient.
Date:
April 1958
Creator:
Dittrich, Ralph T.
System:
The UNT Digital Library
Effect of prior air force over temperature operation on life of J47 buckets evaluated in a sea-level cyclic engine test
Report presenting an evaluation of buckets of S-816 alloy removed from two J47 engines overtemperatured in service operation. Engine results indicated that the overtemperatured buckets did not fracture in abnormally short operating times. Cracking, particularly on the leading edge, was the principal mode of failure of the buckets.
Date:
April 1958
Creator:
Signorelli, Robert A.; Johnston, James R. & Garrett, Floyd B.
System:
The UNT Digital Library
Effects of fixing boundary-layer transition for an unswept-wing model and an evaluation of porous tunnel-wall interference for Mach numbers from 0.60 to 1.40
Report presenting an investigation in the 2- by 2-foot transonic wind tunnel to determine the aerodynamic effects of fixing boundary-layer transition in a forward location on two unswept-wing models differing only in size and with unswept wings of aspect ratio 3.09 with sharp leading edges. Results regarding effects of fixing transition and wall effects in the Ames 2- by 2-foot transonic wind tunnel for an unswept-wing-body model are provided.
Date:
April 1958
Creator:
Stivers, Louis S., Jr. & Lippmann, Garth W.
System:
The UNT Digital Library
Effects of Mach Number and Wall-Temperature Ratio on Turbulent Heat Transfer at Mach Numbers From 3 to 5
Note presenting heat-transfer data evaluated from temperature time histories on a cooled cylindrical model with a cone-shaped nose and with turbulent flow at Mach numbers 3.00, 3.44, 4.08, 4.56, and 5.04. The experimental data were compared with calculated values using a modified Reynolds analogy between skin friction and heat transfer. Results regarding the air flow and temperature-distribution results and heat-transfer results are provided.
Date:
April 1958
Creator:
Tendeland, Thorval
System:
The UNT Digital Library
Experimental investigation of the drag of flat plates and cylinders in the slipstream of a hovering rotor
Report presenting an experimental study of the drag of flat plates and cylinders in the slipstream of a hovering rotor. The dynamic pressure profile of the slipstream for stations close to the rotor was characterized by low or slightly negative values in the center, a rise to a peak near the edge of the slipstream, and a rapid decrease to small negative values farther from the center. Results regarding the drag-to-thrust ratio, ratio of percent thrust loss to percent blocked area, and drag coefficients are provided.
Date:
April 1958
Creator:
McKee, John W. & Naeseth, Rodger L.
System:
The UNT Digital Library
Experimental study of the equivalence of transonic flow about slender cone-cylinders of circular and elliptic cross section
Report presenting an experimental investigation of the equivalence relationship and the related theory for lifting forces proposed by transonic slender-body theory. Two different models with different dimensions are tested over a range of Mach numbers. Results regarding flow equivalence at sonic speed, Mach number range of equivalence, and lifting pressures at transonic speeds are provided.
Date:
April 1958
Creator:
Page, William A.
System:
The UNT Digital Library
A Flight Evaluation and Analysis of the Effect of Icing Conditions on the ZPG-2 Airship
"A series of test flights was conducted by the U. S. Navy over a 3- year period to evaluate the effects of icing on the operation of the ZPG-2 airship. In supercooled. clouds, ice formed only on the forward edges of small protuberances and wires and presented no serious hazard to operation. Ice accretions of the glaze type which occurred in conditions described as freezing drizzle adversely affected various components to a somewhat greater extent" (p. 1).
Date:
April 1958
Creator:
Lewis, William & Perkins, Porter J., Jr.
System:
The UNT Digital Library
Ground reflection of jet noise
Report presenting the effect of a reflecting plane on the propagation of jet noise investigated theoretically and experimentally. The primary focus of the study is to determine the free-field spectrum of subsonic-jet noise from measurements made in the presence of a ground plane.
Date:
April 1958
Creator:
Howes, Walton L.
System:
The UNT Digital Library
Maximum theoretical tangential velocity component possible from straight-back converging and converging-diverging stators at supercritical pressure ratios
Report presenting an investigation of the maximum theoretical tangential velocity component possible by expansion about straight-back stator blade trailing edges made by the method of characteristics for converging and converging-diverging stators. Results regarding an approximate method of determining maximum stator exit whirl and comparison of approximate method with method of characteristics are provided.
Date:
April 1958
Creator:
Moffitt, Thomas P.
System:
The UNT Digital Library
Observations of turbulent-burst geometry and growth in supersonic flow
Report presenting a study of the shape, growth, and formation rate of turbulent bursts in supersonic boundary layers using spark shadowgraphs of small gun-launched models in free flight through still air. The model shapes include cones, ogive-cylinders, and hollow cylinders aligned with the stream. Results regarding the burst thickness profiles, burst plan form and transverse growth, three-dimensional burst shape, burst upstream-edge velocity, burst longitudinal growth rate, burst downstream-edge velocity, burst formation rate, and observations from the shadowgraphs are provided.
Date:
April 1958
Creator:
James, Carlton S.
System:
The UNT Digital Library
Relation of Journal Bearing Performance to Minimum Oil-Film Thickness
Note presenting the minimum thickness of the oil film as used as a basic variable in performance curves of plain journal bearings under steady load. The load capacity and the predicted film thickness at the hook point of the friction curves are shown to correlate with the peak-to-valley values of surface roughness when misalignment is absent.
Date:
April 1958
Creator:
Ocvirk, F. W. & DuBois, G. B.
System:
The UNT Digital Library
Stagnation-point heat transfer to blunt shapes in hypersonic flight, including effects of yaw
An approximate theory is developed for predicting the rate of heat transfer to the stagnation region of blunt bodies in hypersonic flight. Attention is focused on the case where wall temperature is small compared to stagnation temperature. The theoretical heat-transfer rate at the stagnation point of a hemispherical body is found to agree with available experimental data. The effect of yaw on heat transfer to a cylindrical stagnation region is treated at some length, and it is predicted that large yaw should cause sizable reductions in heat-transfer rate.
Date:
April 1958
Creator:
Eggers, A. J., Jr.; Hansen, C. Frederick & Cunningham, Bernard E.
System:
The UNT Digital Library
A theoretical analysis of the effect of engine angular momentum on longitudinal and directional stability in steady rolling maneuvers
From Summary: "The effect of engine momentum on the longitudinal and directional stability of aircraft in steady rolling maneuvers has been investigated. The results presented indicate that the gyroscopic moments produced on the aircraft by a rotating engine in rolling maneuvers can have an appreciable effect on the range of rolling velocities for which longitudinal or directional instability might occur."
Date:
April 1958
Creator:
Gates, Ordway B., Jr. & Woodling, C. H.
System:
The UNT Digital Library
Transonic drag of several jet-noise suppressors
Investigation of the aerodynamic drag of several jet noise suppressors over a range of Mach numbers and several nozzle pressure ratios. The least drag was caused by lobe-type suppressors. The eight-lobe nozzle with ejector caused the greatest amount of drag.
Date:
April 1958
Creator:
North, Warren J.
System:
The UNT Digital Library
Turbulent Shearing Stress in the Boundary Layer of Yawed Flat Plates
Note presenting hot-wire anemometer measurements of the turbulent shearing stress in a turbulent boundary layer on a yawed flat plate. The measured velocity profiles are used to calculate the shear distribution and the result is compared with the result of experimental shear measurements.
Date:
April 1958
Creator:
Ashkenas, Harry
System:
The UNT Digital Library
Analysis of Static Aeroelastic Behavior of Low-Aspect-Ratio Rectangular Wings
"Slender-body theory is used in conjunction with late theory to analyze the static aeroelastic-divergence behavior of low-aspect-ratio rectangular wings of constant thickness when chordwise deformations are considered. In the analysis, the spanwise variation of the deflection is restricted to a parabola but the chordwise variation is allowed complete freedom. Results show the variation of the divergence speed and mode shape with the aspect ratio" (p. 1).
Date:
April 1957
Creator:
Hedgepeth, John M. & Waner, Paul G., Jr.
System:
The UNT Digital Library
Bursting Strength of Unstiffened Pressure Cylinders with Slits
Note presenting internal-pressure tests made on aluminum-alloy unstiffened cylinders with precut slits to study the effect of slit length and curvature on the hoop stress developed at the bursting pressure. The results are predicted with good accuracy by applying a curvature correction to the method presented in a previous report for computing the strength of flat plates with cracks.
Date:
April 1957
Creator:
Peters, Roger W. & Kuhn, Paul
System:
The UNT Digital Library
A collection of data for zero-lift damping in roll of wing-body combinations as determined with rocket-powered models equipped with roll-torque nozzles
Report presenting the zero-lift damping-in-roll derivative as experimentally determined through high subsonic, transonic, and low supersonic speeds by a torque-nozzle forced-roll technique utilizing rocket-propelled models. Data from the the investigations is used to show the effects of wing plan form and airfoil section and the effects of aeroelasticity. Results regarding sweepback, aspect ratio, taper ratio, thickness ratio, airfoil-section shape, delta wings, increase in number of semispan wings from three to four, aeroelastic effects, and comparisons with theory are provided.
Date:
April 1957
Creator:
Stone, David G.
System:
The UNT Digital Library