National Advisory Committee for Aeronautics (NACA) - 119 Matching Results

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Activation of hydrocarbons and the octane number

Description: This report presents an examination of the history of research on engine knocking and the various types of fuels used in the investigations of this phenomenon. According to this report, the spontaneous ignition of hydrocarbons doped with oxygen follows the logarithmic law within a certain temperature range, but not above 920 degrees K. Having extended the scope of investigations to prove hydrocarbons, the curves of the mixtures burned by air should then be established by progressive replacement of pure iso-octane with heptane. Pentane was also examined in this report.
Date: October 1939
Creator: Peschard, Marcel
Partner: UNT Libraries Government Documents Department

Attaining a steady air stream in wind tunnels

Description: Many experimental arrangements of varying kind involve the problems of assuring a large, steady air stream both as to volume and to time. For this reason a separate discussion of the methods by which this is achieved should prove of particular interest. Motors and blades receive special attention and a review of existent wind tunnels is also provided.
Date: October 1933
Creator: Prandtl, L.
Partner: UNT Libraries Government Documents Department

The behavior under shearing stress of duralumin strip with round, flanged holes

Description: This report presents the results of an investigation to determine the behavior of dural strip with flanged holes in the center when subjected to shear stresses. They buckle under a certain load just as a flat sheet. There is one optimum hole spacing and a corresponding buckling load in shear for each sheet width, sheet thickness, and flange form. Comparison with non-flanged sheets revealed a marked increase of buckling load in shear due to the flanging and a slightly greater displacement. Strips were clamped between two stationary end rails and one sliding center rail at which the shear is applied. The force was measured with a tension stirrup up to 20 tons and a compression dynamometer up to 10 tons. The displacement was recorded with the Zeiss dial gauge. The following were investigated: 1) effect of strip width; 2) strip thickness; 3) diameter of flanging; 4) depth of flanging; 5) and hole distance.
Date: October 1, 1934
Creator: Schussler, Karl
Partner: UNT Libraries Government Documents Department

The Behm acoustic sounder for airplanes with reference to its accuracy

Description: Relative altimetry is of great importance for increasing the safety in aerial transportation, because it makes possible safe flying at night, by poor visibility, and when landing. Among the instruments of this type is the Behm sounder, which operates on an acoustic principle. Acoustic altimetry in general and the Behn sounder, in particular, are covered in this report.
Date: October 1, 1930
Creator: Schreiber, Ernest
Partner: UNT Libraries Government Documents Department

Buckling tests on eccentrically loaded beam columns

Description: Formulas are obtained for computing the buckling load of rods eccentrically loaded at each end, the computation being extended in particular to the inelastic range. The test results are graphically presented on three sets of curves. Two of these, at least for the elastic range, are independent of the material tested. The third set, which is independent of the material, possesses greater clearness and is therefore used for comparing the test results with the theoretical.
Date: October 1941
Creator: Cassens, J.
Partner: UNT Libraries Government Documents Department

Calibration Tunnel for High Speed

Description: For the investigation of measuring instruments at higher speeds up to a Mach number 0.7 a tunnel with closed test section was built in 1942 which was as simple and cheap as possible. The blower was a radial blower with straight sheet vanes of 800-millimeter diameter the tips of which were bent backward a little. The blower sucks the air through a honeycomb of diameter 1.2 meter with wide meshes. The air is then accelerated in a short cone with smooth transition to the test section. The cylindrical test section of 200-millimeter diameter has two windows (which are displaced 180 deg from each other. The instruments may be introduced and observed through and observed through these windows. The cross section is then enlarged by a straight diffuser 3.5 meters long and reaches the ninefold cross section. The air flows back into the room through a disk diffuser of 2-meter diameter. The maximum speed in the jet is 250 m/s for a drive power of 35 kT., if there are no installations in the jet. The velocity is determined by pressure holed along the test section.
Date: October 1946
Creator: Pretsch, J.
Partner: UNT Libraries Government Documents Department

The cause of welding cracks in aircraft steels

Description: The discussion in this article refers to gas welding of thin-walled parts of up to about 3 mm thickness. It was proven that by restricting the sulphur, carbon, and phosphorous content, and by electric-furnace production of the steel, it was possible in a short time to remove this defect. Weld hardness - i.e., martensite formation and hardness of the overheated zone - has no connection with the tendency to weld-crack development. Si, Cr, Mo, or V content has no appreciable effect, while increased manganese content tends to reduce the crack susceptibility.
Date: October 1, 1940
Creator: Muller, J
Partner: UNT Libraries Government Documents Department

A Class of De Laval Nozzles

Description: A study is made herein of the irrotational adiabatic motion of a gas in the transition from subsonic to supersonic velocities. A shape of the de Laval nozzle is given, which transforms a homogeneous plane-parallel flow at large subsonic velocity into a supersonic flow without any shockwaves beyond the transition line from the subsonic to the supersonic regions of flow. The method of solution is based on integration near the transition line of the gas equations of motion in the form investigated by S. A. Christianovich.
Date: October 1, 1949
Creator: Falkovich, S. V.
Partner: UNT Libraries Government Documents Department

Combustion of liquid fuels in diesel engine

Description: Hitherto, definite specifications have always been made for fuel oils and they have been classified as more or less good or non-utilizable. The present aim, however, is to build Diesel engines capable of using even the poorest liquid fuels and especially the waste products of the oil industry, without special chemical or physical preparation.
Date: October 1, 1924
Creator: Alt, Otto
Partner: UNT Libraries Government Documents Department

The Compressible Potential Flow Past Elliptic Symmetrical Cylinders at Zero Angle of Attack and with No Circulation

Description: For the tunnel corrections of compressible flows those profiles are of interest for which at least the second approximation of the Janzen-Rayleigh method can be applied in closed form. One such case is presented by certain elliptical symmetrical cylinders located in the center of a tunnel with fixed walls and whose maximum velocity, incompressible, is twice the velocity of flow. In the numerical solution the maximum velocity at the profile and the tunnel wall as well as the entry of sonic velocity is computed. The velocity distribution past the contour and in the minimum cross section at various Mach numbers is illustrated on a worked out-example.
Date: October 1, 1942
Creator: Hantzsche, W. & Wendt, H.
Partner: UNT Libraries Government Documents Department

Computative examination of bending strength of girders originally curved and subjected to longitudinal compression

Description: This report examines the stipulation contained in the 1918 BLV, that a girder subjected to longitudinal compression under the influence of half of the specified breaking load, along with Euler bending safety with an initial deflection of 1/200 of the length of the girder can, at most, be subjected to half the stipulated breaking strength.
Date: October 1922
Creator: Hoff, Wilhelm
Partner: UNT Libraries Government Documents Department

Concerning the flow about ring-shaped cowlings XII : two new classes of circular cowls

Description: For application in practice for annular radiator fairings and similar arrangements, two new classes of circular cowls are developed by theoretical method, and investigated in a systematic test series regarding their behavior under various working conditions.
Date: October 1, 1953
Creator: Kuchemann, Dietrich & Weber, Johanna
Partner: UNT Libraries Government Documents Department

Concrete airship sheds at Orly, France. Part I

Description: This report details the contest to design and build concrete airship hangers. The difficulty lies in the magnitude of the absolute dimensions. An airship shed must withstand two principal types of stresses: those resulting from its own weight and those due to the wind. This report discusses both problems in detail.
Date: October 1925
Creator: FREYSSINET
Partner: UNT Libraries Government Documents Department

Concrete airship sheds at Orly, France. Part II

Description: This report deals mainly with the methods of construction employed when after the plan had been approved. The foundation, side walls, doors and roof are all discussed and the economic savings resulting from this method of construction.
Date: October 1925
Creator: FREYSSINET
Partner: UNT Libraries Government Documents Department

Contribution to the aerodynamics of rotating-wing aircraft. Part II

Description: The interrelations established in an earlier report (NACA-TM-921) are used to study the best assumptions for hovering and horizontal flight. The effect of the twisted and tapered blade on the rotor efficiency is analyzed and the gliding coefficient at different stages (from autogyro to helicopter) of horizontal flight compared. To the extent that model or full-scale test data are available, they are included in the comparison.
Date: October 1, 1941
Creator: Sissingh, G
Partner: UNT Libraries Government Documents Department

Contribution to the Design of Plywood Shells

Description: The writer sets out to prove by calculation and experiment that by extensive utilization of the skin to carry axial load (reduction of stringer spacing) the stringer sections can be made small enough to afford a substantial saving in structural weight. This saving ranges from 5 to about 40 percent.
Date: October 1, 1942
Creator: Blumrich, S.
Partner: UNT Libraries Government Documents Department

Cooling of air-cooled engines by forced circulation of air

Description: This report presents the results of experiments on aerodynamic fuselages in which an air current is forced into the nose of the fuselage by the action of several fans revolving with the propeller. The air is then guided by special deflectors which cause it to flow along the exhaust pipes and cylinders and then, after having been utilized, pass out through annular ports. This system of cooling worked perfectly at all speeds.
Date: October 1, 1926
Partner: UNT Libraries Government Documents Department

Corrections on the thermometer reading in an air stream

Description: A method is described for checking a correction formula, based partly on theoretical considerations, for adiabatic compression and friction in flight tests and determining the value of the constant. It is necessary to apply a threefold correction to each thermometer reading. They are a correction for adiabatic compression, friction and for time lag.
Date: October 1, 1940
Creator: Van Der Maas, H J & Wynia, S
Partner: UNT Libraries Government Documents Department