Latest content added for Digital Library Collection: National Advisory Committee for Aeronautics (NACA)https://digital.library.unt.edu/explore/collections/NACA/browse/?fq=str_title_serial:NACA+Technical+Memorandums&fq=str_year:1947&fq=untl_decade:1940-1949&display=brief2011-11-17T22:13:23-06:00UNT LibrariesThis is a custom feed for browsing Digital Library Collection: National Advisory Committee for Aeronautics (NACA)Method of characteristics for three-dimensional axially symmetrical supersonic flows2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65412/<p><a href="https://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="https://digital.library.unt.edu/ark:/67531/metadc65412/small/"/></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 Fighters2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65408/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65408/"><img alt="A Ram-Jet Engine for Fighters" title="A Ram-Jet Engine for Fighters" src="https://digital.library.unt.edu/ark:/67531/metadc65408/small/"/></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 Flap2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65409/<p><a href="https://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="https://digital.library.unt.edu/ark:/67531/metadc65409/small/"/></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.</p>Equations for Adiabatic but Rotational Steady Gas Flows without Friction2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc64822/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc64822/"><img alt="Equations for Adiabatic but Rotational Steady Gas Flows without Friction" title="Equations for Adiabatic but Rotational Steady Gas Flows without Friction" src="https://digital.library.unt.edu/ark:/67531/metadc64822/small/"/></a></p><p>This paper makes the following assumptions: 1) The flowing gases are assumed to have uniform energy distribution. ("Isoenergetic gas flows," that is valid with the same constants for the the energy equation entire flow.) This is correct, for example, for gas flows issuing from a region of constant pressure, density, temperature, end velocity. This property is not destroyed by compression shocks because of the universal validity of the energy law. 2) The gas behaves adiabatically, not during the compression shock itself but both before and after the shock. However, the adiabatic equation (p/rho(sup kappa) = C) is not valid for the entire gas flow with the same constant C but rather with an appropriate individual constant for each portion of the gas. For steady flows, this means that the constant C of the adiabatic equation is a function of the stream function. Consequently, a gas that has been flowing "isentropically",that is, with the same constant C of the adiabatic equation throughout (for example, in origination from a region of constant density, temperature, and velocity) no longer remains isentropic after a compression shock if the compression shock is not extremely simple (wedge shaped in a two-dimensional flow or cone shaped in a rotationally symmetrical flow). The solution of nonisentropic flows is therefore an urgent necessity.</p>Determination of the Stress Concentration Factor of a Stepped Shaft Stressed in Torsion by Means of Precision Strain Gages2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc64818/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc64818/"><img alt="Determination of the Stress Concentration Factor of a Stepped Shaft Stressed in Torsion by Means of Precision Strain Gages" title="Determination of the Stress Concentration Factor of a Stepped Shaft Stressed in Torsion by Means of Precision Strain Gages" src="https://digital.library.unt.edu/ark:/67531/metadc64818/small/"/></a></p><p>The stress distribution in stepped shafts stressed in torsion is determined by means of the electric precision strain gage the stress concentration factor is ascertained from the measurements. It is shown that the test values always are slightly lower than the values resulting from an approximate formula.</p>Analytical Treatment of Normal Condensation Shock2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc64845/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc64845/"><img alt="Analytical Treatment of Normal Condensation Shock" title="Analytical Treatment of Normal Condensation Shock" src="https://digital.library.unt.edu/ark:/67531/metadc64845/small/"/></a></p><p>The condensation of water vapor in an air consequences: acquisition of heat (liberated heat vaporization; loss of mass on the part of the flowing gas (water vapor is converted to liquid); change in the specific gas constants and of the ratio k of the specific heats (caused by change of gas composition). A discontinuous change of state is therefore connected with the condensation; schlieren photographs of supersonic flows in two-dimensional Laval nozzles show two intersecting oblique shock fronts that in the case of high humidities may merge near the point of intersection into one normal shock front.</p>Fundamental Aerodynamic Investigations for Development of Arrow-Stabilized Projectiles2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc64846/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc64846/"><img alt="Fundamental Aerodynamic Investigations for Development of Arrow-Stabilized Projectiles" title="Fundamental Aerodynamic Investigations for Development of Arrow-Stabilized Projectiles" src="https://digital.library.unt.edu/ark:/67531/metadc64846/small/"/></a></p><p>The numerous patent applications on arrow-stabilized projectiles indicate that the idea of projectiles without spin is not new, but has appeared in various proposals throughout the last decades. As far as projectiles for subsonic speeds are concerned, suitable shapes have been developed for sometime, for example, numerous grenades. Most of the patent applications, though, are not practicable particularly for projectiles with supersonic speed. This is because the inventor usually does not have any knowledge of aerodynamic flow around the projectile nor any particular understanding of the practical solution. The lack of wind tunnels for the development of projectiles made it necessary to use firing tests for development. These are obviously extremely tedious or expensive and lead almost always to failures. The often expressed opinion that arrow-stabilized projectiles cannot fly supersonically can be traced to this condition. That this is not the case has been shown for the first time by Roechling on long projectiles with foldable fins. Since no aerodynamic investigations were made for the development of these projectiles, only tedious series of firing tests with systematic variation of the fins could lead to satisfactory results. These particular projectiles though have a disadvantage which lies in the nature cf foldable fins. They occasionally do not open uniformly in flight, thus causing unsymmetry in flow and greater scatter. The junctions of fins and body are very bad aerodynamically and increase the drag. It must be possible to develop high-performance arrow-stabilized projectiles based on the aerodynamic research conducted during the last few years at Peenemuende and new construction ideas. Thus the final shape, ready for operational use, could be developed in the wind tunnel without loss of expensive time in firing tests. The principle of arrow-stabilized performance has been applied to a large number of caliburs which were stabilized by various means Most promising was the development of a subcaliber wing-stabilized projectile with driving disc (Treibspiegel) where rigid control surfaces extend beyond the caliber of the projectile into the free stream. The stabilized projectiles of full-caliber, wing-stabilized projectiles with fins within the caliber is considerably more difficult. A completely satisfactory solution for the latter has not been found yet.</p>Wind-Tunnel Investigations on a Changed Mustang Profile with Nose Flap Force and Pressure-Distribution Measurements2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc64848/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc64848/"><img alt="Wind-Tunnel Investigations on a Changed Mustang Profile with Nose Flap Force and Pressure-Distribution Measurements" title="Wind-Tunnel Investigations on a Changed Mustang Profile with Nose Flap Force and Pressure-Distribution Measurements" src="https://digital.library.unt.edu/ark:/67531/metadc64848/small/"/></a></p><p>Measurements are described which were taken in the large wind tunnel of the AVA on a rectangular wing "Mustang 2" with nose flap of a chord of 10 percent. Besides force measurements the results of pressure-distribution measurements are given and compared with those on the same profile "without" nose flap.</p>Investigation of the Operating Properties of the Leakage Current Anemometer2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc64850/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc64850/"><img alt="Investigation of the Operating Properties of the Leakage Current Anemometer" title="Investigation of the Operating Properties of the Leakage Current Anemometer" src="https://digital.library.unt.edu/ark:/67531/metadc64850/small/"/></a></p><p>Freedom from inertia, erosion of electrodes, and reaction make the leakage current particularly appropriate for the measurement of flow velocities in gases. Apparatus previously described has now been improved by reducing the size of the electrodes by one -thousandth, as is necessary aerodynamically, and by increasing the magnitude of the current from 1000 to 10,000 times; the latter result was obtained.by use of mercury high-pressure lamps set up at the one focal point of an ellipsoidal reflector with the cathodes arranged at the other focal point or by use of suitable X-ray radiation. Families of calibration curves were taken with a number of vivid tests conditions of the greatest variety and the operating properties of the instrument were widely elucidated by calculation of the sensitivity to fluctuation; this was done at first for operation at stationary conditions only; due to the freedom from inertia the instationary conditions were thus also given. Accordingly, the leakage current anemometer ought to be appropriate for investigations of turbulence,.</p>The Distribution of Loads on Rivets Connecting a Plate to a Beam under Transverse Loads2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc64342/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc64342/"><img alt="The Distribution of Loads on Rivets Connecting a Plate to a Beam under Transverse Loads" title="The Distribution of Loads on Rivets Connecting a Plate to a Beam under Transverse Loads" src="https://digital.library.unt.edu/ark:/67531/metadc64342/small/"/></a></p><p>This report gives theoretical discussion of the distribution of leads on rivets connecting a plate to a beam under transverse leads. Two methods of solution are given which are applicable to loads up to the limit of proportionality; in the first the rivets are treated as discrete members, and in the second they are replaced by a continuous system of jointing. A method of solution is also given which is applicable to the case when nonlinear deformations occur in the rivets and the plate, but not in the beam. The methods are illustrated by numerical examples, and these show that the loads carried by the rivets and the plate are less than the values given by classical theory, which does not take into account the slip of the rivets, even below the limit of proportionality. The difference is considerably accentuated when nonlinear deformations occur in the restructure and the beam then carries the greater portion of the bending moment. If the material of the beam has a higher proportional limit and a higher ultimate strength than the material of the plate, there is thus a transfer of load from weaker to stronger material, and this is to the advantage of the structure. The methods given are of simple application and are recommended for use in the design of light-alloy structures when the design lead is likely to be above the proportional limit.</p>