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Causes of Roof-Fall Fatalities in Anthracite and Bituminous-Coal Mines, 1955 and 1956

Description: Report issued by the U.S. Bureau of Mines discussing coal mining roof-fall accidents during 1955 and 1956. As stated in the summary, "the study includes an analysis of individual accident reports, sets forth the measurable factors, and compares such factors with a representative sample of average data from 39 anthracite mines and 117 bituminous mines" (p. 1).
Date: 1958
Creator: Joseph, R. D.
Partner: UNT Libraries Government Documents Department

Characteristics of the Langley 8-foot transonic tunnel with slotted test section

Description: A large wind tunnel, approximately 8 feet in diameter, has been converted to transonic operation by means of slots in the boundary extending in the direction of flow. The usefulness of such a slotted wind tunnel, already known with respect to the reduction of the subsonic blockage interference and the production of continuously variable supersonic flows, has been augmented by devising a slot shape with which a supersonic test region with excellent flow quality could be produced. Experimental locations of detached shock waves ahead of axially symmetric bodies at low supersonic speeds in the slotted test section agreed satisfactorily with predictions obtained by use of existing approximate methods.
Date: January 1, 1958
Creator: Wright, Ray H; Ritchie, Virgil S & Pearson, Albin O
Partner: UNT Libraries Government Documents Department

A comparative analysis of the performance of long-range hypervelocity vehicles

Description: Long-range hypervelocity vehicles are studied in terms of their motion in powered flight. Powered flight is analyzed for an idealized propulsion system which approximates rocket motors. Unpowered flight is characterized by a return to earth along a ballistic, skip, or glide trajectory. Only those trajectories are treated which yield the maximum range for a given velocity at the end of powered flight. Aerodynamic heating is treated in a manner similar to that employed previously by the senior authors in studying ballistic missiles (NACA rep. 1381), with the exception that radiant as well as convective heat transfer is considered in connection with glide and skip vehicles. As a final performance consideration, it is shown that on the basis of equal ratios of mass at take-off to mass at the end of powered flight, the hypervelocity vehicle compares favorably with the supersonic airplane for ranges in the neighborhood of and greater than one half the circumference of the earth. In the light of this and previous findings, it is concluded that the ballistic and glide vehicles have, in addition to the advantages usually ascribed to great speed, the attractive possibility of providing relatively efficient long-range flight.
Date: January 1, 1958
Creator: Eggers, Alfred J , Jr; Allen, H Julian & Neice, Stanford E
Partner: UNT Libraries Government Documents Department

Compressible laminar boundary layer over a yawed infinite cylinder with heat transfer and arbitrary Prandtl number

Description: The equations are presented for the development of the compressible laminar boundary layer over a yawed infinite cylinder. For compressible flow with a pressure gradient the chordwise and spanwise flows are not independent. Using the Stewartson transformation and a linear viscosity-temperature relation yields a set of three simultaneous ordinary differential equations in a form yielding similar solutions. These equations are solved for stagnation-line flow for surface temperatures from zero to twice the free-stream stagnation temperature and for a wide range of yaw angle and free-stream Mach number. The results indicate that the effect of yaw on the heat-transfer coefficient at the stagnation line depends markedly on the free-stream Mach number. An unusual result of the solutions is that for large yaw angles and stream Mach numbers the chordwise velocity within the boundary layer exceeds the local external chordwise velocity, even for a highly cooled wall.
Date: January 1, 1958
Creator: Reshotko, Eli & Beckwith, Ivan E
Partner: UNT Libraries Government Documents Department

A correlation of results of flight investigation with results of an analytical study of effects of wing flexibility on wing strains due to gusts

Description: An analytical study of the effects of wing flexibility on wing strains due to gusts has been made for four spanwise stations of a four-engine bomber airplane, and the results have been correlated with results of a previous flight investigation.
Date: January 1, 1958
Creator: Shufflebarger, C C; Payne, Chester B & Cahen, George L
Partner: UNT Libraries Government Documents Department

Differential equations of motion for combined flapwise bending, chordwise bending, and torsion of twisted nonuniform rotor blades

Description: The differential equations of motion for the lateral and torsional deformations of twisted rotating beams are developed for application to helicopter rotor and propeller blades. No assumption is made regarding the coincidence of the neutral, elastic, and mass axes, and the generality is such that previous theories involving various simplifications are contained as subcases to the theory presented in this paper. Special attention is given the terms which are not included in previous theories. These terms are largely coupling-type terms associated with the centrifugal forces. Methods of solution of the equations of motion are indicated by selected examples.
Date: January 1, 1958
Creator: Houbolt, John C & Brooks, George W
Partner: UNT Libraries Government Documents Department

Ditching investigations of dynamic models and effects of design parameters on ditching characteristics

Description: Data from ditching investigations conducted at the Langley Aeronautical Laboratory with dynamic scale models of various airplanes are presented in the form of tables. The effects of design parameters on the ditching characteristics of airplanes, based on scale-model investigations and on reports of full-scale ditchings, are discussed. Various ditching aids are also discussed as a means of improving ditching behavior.
Date: January 1, 1958
Creator: Fisher, Lloyd J & Hoffman, Edward L
Partner: UNT Libraries Government Documents Department

Drag minimization for wings and bodies in supersonic flow

Description: The minimization of inviscid fluid drag is studied for aerodynamic shapes satisfying the conditions of linearized theory, and subject to imposed constraints on lift, pitching moment, base area, or volume. The problem is transformed to one of determining two-dimensional potential flows satisfying either Laplace's or Poisson's equations with boundary values fixed by the imposed conditions. A general method for determining integral relations between perturbation velocity components is developed. This analysis is not restricted in application to optimum cases; it may be used for any supersonic wing problem.
Date: January 1, 1958
Creator: Heaslet, Max A & Fuller, Franklyn B
Partner: UNT Libraries Government Documents Department

Effect of chord size on weight and cooling characteristics of air-cooled turbine blades

Description: An analysis has been made to determine the effect of chord size on the weight and cooling characteristics of shell-supported, air-cooled gas-turbine blades. In uncooled turbines with solid blades, the general practice has been to design turbines with high aspect ratio (small blade chord) to achieve substantial turbine weight reduction. With air-cooled blades, this study shows that turbine blade weight is affected to a much smaller degree by the size of the blade chord.
Date: January 1, 1958
Creator: Esgar, Jack B; Schum, Eugene F & Curren, Arthur N
Partner: UNT Libraries Government Documents Department

Effect of fuel variables on carbon formation in turbojet-engine combustors

Description: Report presents the results of an investigation of the effects of fuel properties and of a number of fuel additives on combustion-chamber carbon deposition and exhaust-gas smoke formation in a single tubular turbojet-engine combustor. Limited tests were conducted with a number of the fuels in several full-scale turbojet engines to verify single-combustor data.
Date: January 1, 1958
Creator: Jonash, Edmund R; Wear, Jerrold D & Cook, William P
Partner: UNT Libraries Government Documents Department

Effects of airplane flexibility on wing strains in rough air at 35,000 feet as determined by a flight investigation of a large swept-wing airplane

Description: A flight investigation was made on a large sweptback-wing bomber airplane and the results are compared with data previously obtained at low altitude (5,000 feet). The effects of wing flexibility on the wing strains were, on the average, about 20 percent larger at the higher altitude.
Date: January 1, 1958
Creator: Rhyne, Richard H
Partner: UNT Libraries Government Documents Department

Elliptic cones alone and with wings at supersonic speed

Description: To help fill the gap in the knowledge of aerodynamics of shapes intermediate between bodies of revolution and flat triangular wings, force and moment characteristics for elliptic cones have been experimentally determined for Mach numbers of 1.97 and 2.94. Elliptic cones having cross-sectional axis ratios from 1 through 6 and with lengths and base areas equal to circular cones of fineness ratios 3.67 and 5 have been studied for angles of bank of 0 degree and 90 degrees. Elliptic and circular cones in combination with triangular wings of aspect ratios 1 and 1.5 also have been considered. The angle-of-attack range was from 0 degree to about 16 degrees, and the Reynolds number was 8 x 10(6), based on model length. In addition to the forces and moments at angle of attack, pressure distributions for elliptic cones at zero angle of attack have been determined. The results of this investigation indicate that there are distinct aerodynamic advantages to the use of elliptic cones.
Date: January 1, 1958
Creator: Jorgensen, Leland H
Partner: UNT Libraries Government Documents Department

Experimental determination of effects of frequency and amplitude on the lateral stability derivatives for a delta, a swept, and unswept wing oscillating in yaw

Description: Three wing models were oscillated in yaw about their vertical axes to determine the effects of systematic variations of frequency and amplitude of oscillation on the in-phase and out-of-phase combination lateral stability derivatives resulting from this motion. The tests were made at low speeds for a 60 degree delta wing, a 45 degree swept wing, and an unswept wing; the swept and unswept wings had aspect ratios of 4. The results indicate that large changes in the magnitude of the stability derivatives due to the variation of frequency occur at high angles of attack, particularly for the delta wing. The greatest variations of the derivatives with frequency take place for the lowest frequencies of oscillation; at the higher frequencies, the effects of frequency are smaller and the derivatives become more linear with angle of attack. Effects of amplitude of oscillation on the stability derivatives for delta wings were evident for certain high angles of attack and for the lowest frequencies of oscillation. As the frequency became high, the amplitude effects tended to disappear.
Date: January 1, 1958
Creator: Fisher, Lewis R
Partner: UNT Libraries Government Documents Department