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Preliminary Transient Performance Data on the J73 Turbojet Engine, 3, Altitude, 45,000 Feet

Description: A program was undertaken to determine the J73 turbojet engine compressor stall and surge characteristics and combustor blow-out limits encountered during transient engine operation. Data were obtained in the form of oscillograph traces showing the time history of several engine parameters with changes in engine fuel flow. The data presented in this report are for step and ramp changes in fuel flow at an altitude of 45,000 feet and flight Mach numbers of 0 and 0.8.
Date: June 30, 1953
Creator: McAulay, John E. & Wallner, Lewis E.
Partner: UNT Libraries Government Documents Department

Preliminary Transient Performance Data on the J73 Turbojet Engine. II - Altitude, 35,000 Feet

Description: A program was undertaken to determine the J73 turbojet engine compressor stall and surge characteristics and combustor blow-out limits encountered during transient engine operation. Data were obtained in the form of oscillograph traces showing the time history of several engine performance parameters with changes in engine fuel flow. The data presented in this report are for step changes in fuel flow at an altitude of 35,000 feet, at flight Mach numbers of 0.3, 0.8, and 1.2, and at several engine-inlet temperatures,.
Date: June 29, 1953
Creator: Lubick, Robert J. & Sobolewski, Adam E.
Partner: UNT Libraries Government Documents Department

Preliminary Wind-Tunnel and Flight Tests of a Balanced Split Flap, Special Report

Description: One disadvantage that has been apparent in the operation of split flaps as used to date is the time and effort required to operate them. In this communication an investigation is being made of possible means for balancing them aerodynamically to make their operation easier. Several arrangements have been tested in the 7 by 210 foot wind tunnel, and the results of the wind-tunnel tests as well as preliminary flight tests on one of the more promising forms are given in this paper.
Date: August 1, 1934
Creator: Weick, Fred E. & Thompson, Floyd L.
Partner: UNT Libraries Government Documents Department

Preliminary wind-tunnel investigation of an NACA 23012 airfoil with various arrangements of venetian-blind flaps

Description: Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a large-chord NACA 23012 airfoil with several arrangements of venetian-blind flaps to determine the aerodynamic section characteristics as affected by the over-all flap chord, the chords of the slats used to form the flap, the slat spacing, the number of slats and the position of the flap with respect to the wing. Complete section data are given in the form of graphs for all the combinations tested.
Date: January 1, 1940
Creator: Wenzinger, Carl J. & Harris, Thomas A.
Partner: UNT Libraries Government Documents Department

Preliminary Wind-Tunnel Investigation of the Performance of Republic F-105 Wing-Root Inlet Configurations at Various Angles of Attack and a Mach Number of 2.01

Description: A 1/13-scale model of the forebody of the Republic F-105 with twin-duct wing-root inlets was tested in the Langley 4- by 4-foot supersonic pressure tunnel through a range of angle of attack from -4 deg to 15 deg at a Mach number of 2.01 and a Reynolds number of approximately 3.4 x 10(exp 6) per foot. The tests were made with four configurations which incorporated varying amounts of sweep and stagger of the inlet leading edges, modifications to the areas of the boundary-layer diverter floor plate, and modifications to the area of the boundary-layer diverter bleed slots. The highest overall pressure recovery at an angle of attack of 0 deg (average total-pressure recovery, 0.84 mass-flow ratio, 0.98) was achieved with configuration having an inlet leading-edge sweep angle of 58 deg with no leading-edge stagger. Stagger was found to improve the angle-of- attack performance, but at a sacrifice in inlet efficiency for an angle of attack of 0 deg. The boundary-layer diverter floor height, of the order of one boundary-layer thickness, was satisfactory for bypassing the fuselage boundary layer. The boundary-layer diverter-plate bleed slots were effective in increasing the total-pressure recovery of the inlet. The total-pressure-recovery contour plots, taken at the compressor-face station, indicate the existence of high-velocity "cores" throughout the inlet operating range.
Date: January 15, 1957
Creator: Kouyoumjian, W. L.
Partner: UNT Libraries Government Documents Department

Preliminary Wind-Tunnel Tests of the Effect of Nacelles on the Characteristics of a Twin-Engine Bomber Model with Low-Drag Wing, Special Report

Description: Tests were made in the NACA 19-foot pressure tunnel of a simplified twin-engine bomber model with an NACA low-drag wing primarily to obtain an indication of the effects of engine nacelles on the characteristics of the model both with and without simple split trailing-edge flaps. Nacelles with conventional-type cowlings representative of those used on an existing high-performance airplane and with NACA high-speed type E cowlings were tested. The tests were made without propeller slipstream. The aerodynamic effects of adding the nacelles to the low-drag wing were similar to the effects commonly obtained by adding similar nacelles to conventional wings. The maximum lift coefficient without flaps was slightly increased, but the increment in maximum lift due to deflecting the flaps was somewhat decreased. The stalling characteristics were improved by the presence of the nacelles. Addition of the nacelles had a destabilizing effect on the pitching moments, as is usual for nacelles that project forward of the wing. The drag increments due to the nacelles were of the usual order of magnitude, with the increment due to the nacelles with NACA type E cowlings approximately one-third less than that of the nacelles with conventional cowlings with built-in air scoops.
Date: July 1, 1942
Creator: Wenzinger, Carl J. & Sivells, James C.
Partner: UNT Libraries Government Documents Department

Preliminary wind-tunnel tests of triangular and rectangular wings in steady roll at Mach numbers of 1.62 and 1.92

Description: Damping-in-roll coefficients for a series of triangular plan-form wings and two rectangular plan-form wings have been obtained from supersonic-tunnel tests. The wings were mounted on a body of revolution and tested at Mach numbers of 1.62 and 1.92.
Date: June 1, 1956
Creator: Brown, Clinton E & Heinke, Harry S , R
Partner: UNT Libraries Government Documents Department

Preliminary wing model tests in the variable density wind tunnel of the National Advisory Committee for Aeronautics

Description: This report contains the results of a series of tests with three wing models. By changing the section of one of the models and painting the surface of another, the number of models tested was increased to five. The tests were made in order to obtain some general information on the air forces on wing sections at a high Reynolds number and in particular to make sure that the Reynolds number is really the important factor, and not other things like the roughness of the surface and the sharpness of the trailing edge. The few tests described in this report seem to indicate that the air forces at a high Reynolds number are not equivalent to respective air forces at a low Reynolds number (as in an ordinary atmospheric wind tunnel). The drag appears smaller at a high Reynolds number and the maximum lift is increased in some cases. The roughness of the surface and the sharpness of the trailing edge do not materially change the results, so that we feel confident that tests with systematic series of different wing sections will bring consistent results, important and highly useful to the designer.
Date: January 1, 1926
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department

The Preparation and Properties of Mammalian Ribonucleic Acids

Description: "A method for the preparation of mammalian ribonucleic acids employing high concentrations of guanidine hydrochloride in the fractionation procedure is reported in this paper. Aside from the facility of preparation the method has the advantage of avoiding conditions of acidity and alkalinity which might degrade tissue ribonucleic acids and, by virtue of the protein denaturant action of guanidine salts, of minimizing the possibility for enzymatic degradation" (p. 3).
Date: October 12, 1950
Creator: Volkin, E. & Carter, C. E.
Partner: UNT Libraries Government Documents Department

Preparation and Uses of Tar and its Simple Crude Derivatives

Description: Technical paper issued by the Bureau of Mines over studies of coal tars. As stated in the introduction, "this paper discusses the uses to which some of the various tars are put and shows briefly the usual methods of working up tar into some of its simple or easily prepared derivatives, for which a market can generally be found" (p. 5). This paper includes tables, illustrations, and photographs.
Date: February 1922
Creator: Odell, W. W.
Partner: UNT Libraries Government Documents Department

Preparation Characteristics of Illinois Coals

Description: Report issued by the Bureau of Mines discussing the mechanical coal-preparation characteristics. As stated in the introduction, "this second publication reports the washability and screen analyses of the important Illinois coal beds, showing the quality of product that would result when the raw coal is subjected to preparatory treatment" (p. 1). This report includes tables, maps, and illustrations.
Date: 1949
Creator: Crentz, William L. & Fraser, Thomas
Partner: UNT Libraries Government Documents Department

Preparation Characteristics of Pennsylvania Anthracite from the Bottom Red Ash Bed, Northern Field

Description: Report issued by the Bureau of Mines on the anthracite coal in the Bottom Red Ash Bed in Pennsylvania. The coal samples were analyzed for thickness and geologic structure. The amount of recoverable coal was also estimated. This report includes tables, maps, and illustrations.
Date: July 1967
Creator: Sanner, William S.
Partner: UNT Libraries Government Documents Department