Latest content added for UNT Digital Library Collection: National Advisory Committee for Aeronautics (NACA)http://digital.library.unt.edu/explore/collections/NACA/browse/?fq=str_year:1947&fq=untl_decade:1940-19492015-02-26T16:50:55-06:00UNT LibrariesThis is a custom feed for browsing UNT Digital Library Collection: National Advisory Committee for Aeronautics (NACA)Some Recent Contributions to the Study of Transition and Turbulent Boundary Layers2015-02-26T16:50:55-06:00http://digital.library.unt.edu/ark:/67531/metadc172454/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc172454/"><img alt="Some Recent Contributions to the Study of Transition and Turbulent Boundary Layers" title="Some Recent Contributions to the Study of Transition and Turbulent Boundary Layers" src="http://digital.library.unt.edu/ark:/67531/metadc172454/thumbnail/"/></a></p><p>None</p>Considerations of the Total Drag of Supersonic Airfoil Sections2015-02-26T16:50:55-06:00http://digital.library.unt.edu/ark:/67531/metadc172466/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc172466/"><img alt="Considerations of the Total Drag of Supersonic Airfoil Sections" title="Considerations of the Total Drag of Supersonic Airfoil Sections" src="http://digital.library.unt.edu/ark:/67531/metadc172466/thumbnail/"/></a></p><p>The results of calculations of the viscous and pressure drags of some two-dimensional supersonic airfoils at zero lift are presented. The results indicate that inclusion of viscous drag alters many previous results regarding the desirability of certain airfoil shapes for securing low drags at supersonic speeds. At certain Reynolds and Mach numbers, for instance, a circular-arc airfoil may theoretically have less drag than the previously advocated symmetrical wedge-shape profile; although under different conditions, the circular-arc airfoil may have a higher drag.</p>Summary of lateral-control research2011-11-17T22:13:23-06:00http://digital.library.unt.edu/ark:/67531/metadc65469/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc65469/"><img alt="Summary of lateral-control research" title="Summary of lateral-control research" src="http://digital.library.unt.edu/ark:/67531/metadc65469/thumbnail/"/></a></p><p>A summary has been made of the available information on lateral control. A discussion is given of the criterions used in lateral-control specifications, of the factors involved in obtaining satisfactory lateral control, and of the methods employed in making lateral-control investigations in flight and in wind tunnels. The available data on conventional flap-type ailerons having various types of aerodynamic balance are presented in a form convenient for use in design. The characteristics of spoiler devices and booster mechanisms are discussed. The effects of Mach number, boundary layer, and distortion of the wing or of the lateral-control system are considered insofar as the available information permits. An example is included to illustrate the use of the design data. The limitations of the available information and some of the lateral-control problems that remain to be solved are indicated.</p>Investigation of the dynamic response of airplane wings to gusts2011-11-17T22:13:23-06:00http://digital.library.unt.edu/ark:/67531/metadc65006/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc65006/"><img alt="Investigation of the dynamic response of airplane wings to gusts" title="Investigation of the dynamic response of airplane wings to gusts" src="http://digital.library.unt.edu/ark:/67531/metadc65006/thumbnail/"/></a></p><p>None</p>Theoretical study of air forces on an oscillating or steady thin wing in a supersonic main stream2011-11-17T22:13:23-06:00http://digital.library.unt.edu/ark:/67531/metadc65470/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc65470/"><img alt="Theoretical study of air forces on an oscillating or steady thin wing in a supersonic main stream" title="Theoretical study of air forces on an oscillating or steady thin wing in a supersonic main stream" src="http://digital.library.unt.edu/ark:/67531/metadc65470/thumbnail/"/></a></p><p>A theoretical study, based on the linearized equations of motion for small disturbance, is made of the air forces on wings of general plan forms moving forward at a constant supersonic speed. The boundary problem is set up for both the harmonically oscillating and the steady conditions. Two types of boundary conditions are distinguished, which are designated "purely supersonic" and "mixed supersonic." the method is illustrated by applications to a number of examples for both the steady and the oscillating conditions. The purely supersonic case involves independence of action of the upper and lower surfaces of the airfoil and present analysis is mainly concerned with this case. A discussion is first given of the fundamental or elementary solution corresponding to a moving source. The solutions for the velocity potential are then synthesized by means of integration of the fundamental solution for the moving source. The method is illustrated by applications to a number of examples for both the steady and the oscillating cases and for various plan forms, including swept wings and rectangular and triangular plan forms. The special results of a number of authors are shown to be included in the analysis.</p>The stability of the laminar boundary layer in a compressible fluid2011-11-17T22:13:23-06:00http://digital.library.unt.edu/ark:/67531/metadc65683/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc65683/"><img alt="The stability of the laminar boundary layer in a compressible fluid" title="The stability of the laminar boundary layer in a compressible fluid" src="http://digital.library.unt.edu/ark:/67531/metadc65683/thumbnail/"/></a></p><p>Report is a continuation of a theoretical investigation of the stability of the laminar boundary layer in a compressible fluid. An approximate estimate for the minimum critical Reynolds number, or stability limit, is obtained in terms of the distribution of the kinematic viscosity and the product of the mean density and mean vorticity across the boundary layer. The extension of the results of the stability analysis to laminar boundary-layer gas flows with a pressure gradient in the direction of the free stream is discussed. (author).</p>Method of characteristics for three-dimensional axially symmetrical supersonic flows.2011-11-17T22:13:23-06:00http://digital.library.unt.edu/ark:/67531/metadc65412/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc65412/"><img alt="Method of characteristics for three-dimensional axially symmetrical supersonic flows." title="Method of characteristics for three-dimensional axially symmetrical supersonic flows." src="http://digital.library.unt.edu/ark:/67531/metadc65412/thumbnail/"/></a></p><p>An approximation method for three-dimensional axially symmetrical supersonic flows is developed; it is based on the characteristics theory (represented partly graphically, partly analytically). Thereafter this method is applied to the construction of rotationally symmetrical nozzles. (author).</p>A Ram-Jet Engine for Fighters2011-11-17T22:13:23-06:00http://digital.library.unt.edu/ark:/67531/metadc65408/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc65408/"><img alt="A Ram-Jet Engine for Fighters" title="A Ram-Jet Engine for Fighters" src="http://digital.library.unt.edu/ark:/67531/metadc65408/thumbnail/"/></a></p><p>Simple and accurate calculations are made of the flow process in a continuous compressorless Lorin jet-propulsion unit. Experimental confirmation is given from towing tests on an airplane at flying speeds up to 200 miles per second. An analysis is made of the performance of a fighter-type airplane designed for utilization of this propulsion system.</p>Force and pressure-distribution measurements on a rectangular wing with a slotted droop nose and with either plain and split flaps in combination or a slotted flap.2011-11-17T22:13:23-06:00http://digital.library.unt.edu/ark:/67531/metadc65409/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc65409/"><img alt="Force and pressure-distribution measurements on a rectangular wing with a slotted droop nose and with either plain and split flaps in combination or a slotted flap." title="Force and pressure-distribution measurements on a rectangular wing with a slotted droop nose and with either plain and split flaps in combination or a slotted flap." src="http://digital.library.unt.edu/ark:/67531/metadc65409/thumbnail/"/></a></p><p>Force measurements and pressure distribution measurements on the midsection were made on a rectangular wing with slotted droop nose and end plates, on which could be placed a choice of either a plain flap-split flap combination or a slotted flap. (author).</p>Effects of a Fuselage on the Aerodynamic Characteristics of a 42 Degree Sweptback Wing at Reynolds Numbers to 8,000,0002011-11-17T22:13:23-06:00http://digital.library.unt.edu/ark:/67531/metadc64565/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc64565/"><img alt="Effects of a Fuselage on the Aerodynamic Characteristics of a 42 Degree Sweptback Wing at Reynolds Numbers to 8,000,000" title="Effects of a Fuselage on the Aerodynamic Characteristics of a 42 Degree Sweptback Wing at Reynolds Numbers to 8,000,000" src="http://digital.library.unt.edu/ark:/67531/metadc64565/thumbnail/"/></a></p><p>Wind-tunnel investigations were made in pitch and yaw with and without split flaps. Presence of the fuselage had negligible effect on values of maximum lift coefficient and slope of lift curve, but caused a destabilizing shift in the rate of change of pitching moment with lift. Effects of fuselage position on drag characteristics were small for wings without flaps, but were appreciable when split flaps were on.</p>