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 Serial/Series Title: NACA Technical Reports
 Collection: National Advisory Committee for Aeronautics Collection
Ground simulator studies of the effects of valve friction, stick friction, flexibility, and backwash on power control system quality

Ground simulator studies of the effects of valve friction, stick friction, flexibility, and backwash on power control system quality

Date: January 1, 1958
Creator: Brown, B Porter
Description: Report presents results of tests made on a power control system by means of a ground simulator to determine the effects of various combinations of valve friction and stick friction on the ability of the pilot to control the system. Various friction conditions were simulated with a rigid control system, a flexible system, and a rigid system having some backlash. For the tests, the period and damping of the simulated airplane were held constant.
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Growth of disturbances in a flame-generated shear region

Growth of disturbances in a flame-generated shear region

Date: January 1, 1958
Creator: Blackshear, Perry L , Jr
Description: Results are presented of an experimental and theoretical investigation of the growth of transverse velocity disturbances in the shear region caused by a flame in a duct. In the theoretical stability analysis, a flow field arising from a flame in a duct was analyzed. The flow was neutrally stable to symmetric disturbances and unstable to antisymmetric ones. In the experimental part of the program disturbances of various frequencies were imposed on a flame stabilized in a duct, and the effects were measured by shadow photography and photomultiplier-probe surveys.
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Incompressible flutter characteristics of representative aircraft wings

Incompressible flutter characteristics of representative aircraft wings

Date: January 1, 1958
Creator: Wilts, C H
Description: This report gives the results of a detailed study of the flutter characteristics of four representative aircraft wings. This study was made using the electric-analog computer at the California Institute of Technology. During the course of this investigation eight important parameters of each wing were varied and, in addition, the effects of mass, inertia, pitching spring, and location of a concentrated mass were investigated for all four wings and at several sweepback angles.
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Investigation of a nonlinear control system

Investigation of a nonlinear control system

Date: January 1, 1958
Creator: Flugge-Lotz, I
Description: A discontinuous variation of coefficients of the differential equation describing the linear control system before nonlinear elements are added is studied in detail. The nonlinear feedback is applied to a second-order system. Simulation techniques are used to study performance of the nonlinear control system and to compare it with the linear system for a wide variety of inputs. A detailed quantitative study of the influence of relay delays and of a transport delay is presented.
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Investigation of separated flows in supersonic and subsonic streams with emphasis on the effect of transition

Investigation of separated flows in supersonic and subsonic streams with emphasis on the effect of transition

Date: January 1, 1958
Creator: Chapman, Dean R
Description: Report presents the results of experimental and theoretical research conducted on flow separation associated with steps, bases, compression corners, curved surfaces, shock-wave boundary-layer reflections, and configurations producing leading-edge separation. Results were obtained from pressure-distribution measurements, shadowgraph observations, high-speed motion pictures, and oil-film studies. The maximum scope of measurement encompassed Mach numbers between 0.4 and 3.6, and length Reynolds numbers between 4,000 and 5,000,000.
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Investigation of some wake vortex characteristics of an inclined ogive-cylinder body at Mach number 2

Investigation of some wake vortex characteristics of an inclined ogive-cylinder body at Mach number 2

Date: January 1, 1958
Creator: Jorgensen, Leland H
Description: For a body consisting of a fineness-ratio-3 ogival nose tangent to a cylindrical afterbody 7.3 diameters long, pitot-pressure distributions in the flow field, pressure distributions over the body, and downwash distributions along a line through the vortex centers have been measured for angles of attack to 20 degrees. The Reynolds numbers, based on body diameter, were 0.15 x 10 to the 6th power and 0.44 x 10 to the 6th power. Comparisons of computed and measured vortex paths and downwash distributions are made. (author).
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Investigation of the drag of various axially symmetric nose shapes of fineness ratio 3 for Mach numbers from 1.24 to 7.4

Investigation of the drag of various axially symmetric nose shapes of fineness ratio 3 for Mach numbers from 1.24 to 7.4

Date: January 1, 1958
Creator: Perkins, Edward W
Description: Experimental drag measurements at zero angle of attack for various theoretical minimum drag nose shapes, hemispherically blunted cones, and other more common profiles of fineness ratios of about 3 are compared with theoretical results for a Mach number and Reynolds number range of 1.24 to 7.4 and 1.0 x 10 to the 6th power to 7.5 x 10 to the 6th power (based on body length), respectively. The results of experimental pressure-distribution measurements are used for the development of an empirical expression for predicting the pressure drag of hemispherically blunted cones.
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A low-speed experimental investigation of the effect of a sandpaper type of roughness on boundary-layer transition

A low-speed experimental investigation of the effect of a sandpaper type of roughness on boundary-layer transition

Date: January 1, 1958
Creator: Von Doenhoff, Albert E
Description: An investigation was made in the Langley low-turbulence pressure tunnel to determine the effect of size and location of a sandpaper type of roughness on the Reynolds number for transition. Transition was observed by means of a hot-wire anemometer located at various chordwise stations for each position of the roughness. These observations indicated that when the roughness is sufficiently submerged in the boundary layer to provide a substantially linear variation of boundary-layer velocity with distance from the surface up to the top of the roughness, turbulent "spots" begin to appear immediately behind the roughness when the Reynolds number based on the velocity at the top of the roughness height exceeds a value of approximately 600. At Reynolds numbers even slightly below the critical value (value for transition), the sandpaper type of roughness introduced no measurable disturbances into the laminar layer downstream of the roughness. The extent of the roughness area does not appear to have an important effect on the critical value of the roughness Reynolds number.
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A low-speed experimental investigation of the effect of a sandpaper type of roughness on boundary-layer transition

A low-speed experimental investigation of the effect of a sandpaper type of roughness on boundary-layer transition

Date: January 1, 1958
Creator: Horton, E. A. & Vondoenhoff, A. E.
Description: None
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Measurement of static pressure on aircraft

Measurement of static pressure on aircraft

Date: January 1, 1958
Creator: Gracey, William
Description: Existing data on the errors involved in the measurement of static pressure by means of static-pressure tubes and fuselage vents are presented. The errors associated with the various design features of static-pressure tubes are discussed for the condition of zero angle of attack and for the case where the tube is inclined to flow. Errors which result from variations in the configuration of static-pressure vents are also presented. Errors due to the position of a static-pressure tube in the flow field of the airplane are given for locations ahead of the fuselage nose, ahead of the wing tip, and ahead of the vertical tail fin. The errors of static-pressure vents on the fuselage of an airplane are also presented. Various methods of calibrating static-pressure installations in flight are briefly discussed.
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