Abstract: Torsional oscillations of helicopter rotor blades are reduced with stall, otherwise leading to such torsional oscillations, precluded consistent with allowable high angle of attack, by sucking air from the boundary layer on the upper surface of the blade near the leading edge thereof at a radial location of 80-90% maximum radius thereof and pumping the sucked boundary layer air, utilizing the inherent centrifugal pumping capability of the blade by establishing an exhaust of the centrifugal pumping passage within the blade which allows adequate pumping for the torsional oscillation reduction purpose consistent with the required rate flow of air.

Abstract: A method is disclosed for firmly bonding together driving and driven gears. Bonding is accomplished by placing a thin layer of a thermal setting resin between the web faces of gears that are joined together by a multiplicity of spaced apart fasteners. The cured resin acts both as a load carrying joint and as a gasket.

Abstract: The invention is a missile fuze. A slider carries a detonator so that it is normally out of alignment with the firing train. The slider is locked in position by cylinders. The cylinders contain pistons which respond to centrifugal force to move radially outwardly, in each instance moving the center of gravity of each cylinder-piston combination outwardly. When the centrifugal force exerted on such combinations becomes sufficiently great the combinations move outwardly and unlock the slider, which then positions the detonator in alignment with the firing train. In order to be displaced radially outwardly the cylinders must overcome the force of retainer weights which are mounted and proportioned in such manner as to respond to centrifugal force and spin to increase the retaining thrusts.

Abstract: Herein disclosed is a crop harvesting machine for collecting stalk crops having seed pods near ground level. The harvester includes a relatively large horizontally disposed reel structure. As the reel rotates, bat-assemblies thereon successively sweep downward into the crop and urge the stalks against a cutter bar. These assemblies feature a combination of flexible flaps and pickup reel tines which conserve and prevent loss of crops.

Abstract: Three-dimensional impregnated filamentary materials and methods for making the same.

Abstract: A turbine nozzle has inner and outer shrouds structurally connected by hollow core members which together with nose and tail inserts retained in the shrouds form airfoil-shaped vanes. Openings in one of the shrouds supply cooling air to the hollow vane cores whose walls have orifices to impinge air upon the inserts. Spent air from the nose insert film cools the core. Air directed at the tail insert divides to flow through holes in the insert and to film cool the insert. Orifices and holes are cast or readily drilled into the parts prior to their assembly. For superior resistance to high temperatures, the inserts are preferably columnar-grained or monocrystalline superalloy castings which are brazed or welded into the shrouds and are replaceable to extend nozzle service life. Alternatively, ceramic or metal inserts are mechanically retained in the shrouds.

Abstract: Ceramic shell molds are removed from cast turbine blades by contacting the shell mold with a concentrated solution of HF whereby the binder of the shell is destroyed and the shell material falls away from the metal casting.

Abstract: Herein disclosed is the combination of an aerodynamic blade having a root formed with outwardly curved shoulders and a transverse curved indentation, a rotor disc formed with a blade root receiving slot having curved complementary retaining surfaces in contact with those shoulders and an elastic split metallic roll pin disposed between the indentation and disc to provide damping, the radii of the curved shoulders and retaining surfaces being generated from an axis below said indentation.

Abstract: Apparatus for suppressing infrared radiation emitted from hot metal parts at the aft end of a gas turbine engine and from the exhaust gas plume thereof is provided and such apparatus employs components which utilize an ejector principle to provide cooling action utilizing ambient air and such components may be provided with means for adjustment thereof to vary the amount of cooling ambient air.

Abstract: A gas turbine engine is described in which a compressor, combustor and turbine are arranged in series flow relationship. Pressurized air enters the combustion chamber with approximately the same swirl as imparted to it by the compressor rotor, through an annular inlet tangentially of and at the outer bounds of the combustion chamber which has a toroidal configuration. This creates a vortex which swirls annularly and in which combustion of fuel is maintained. Mixing action in this vortex is enhanced through the introduction of additional air through chutes formed in the combustion chamber liner. The hot gas stream is discharged from the combustion chamber through an exit also at the outer bounds and tangentially thereof. In one embodiment fuel is introduced by means of nozzles aligned with the discharge ends of the chutes. In another embodiment the combustion chamber inlet is in the form of a venturi passageway and fuel is introduced into the inlet air by ports at the venturi throat.

Abstract: A rotor blade configuration is disclosed which greatly reduces noise generated by the low pressure compressor, or fan, of a turbofan engine. The leading edge of the blade is swept forwardly from its hub up to a point of sweep reversal and then swept rearwardly to the tip of the blade. The slope of the curved leading edge line relative to the direction of airflow is gradually decreased from the hub to the tip to maintain the velocity component, of air relative to the blade leading edge, subsonic, while the relative velocity of the air to the blade is above a critical value and supersonic. This substantially eliminates noise producing, standing shock waves along the blade leading edges. Also described are methods for determining the configuration of such blades to obtain these ends with a minimum increase in blade weight and a minimum blade bending and blade attachment stresses.

Abstract: In a laser, a gaseous mixture is suitably heated to a first temperature and at a first pressure to provide a large energy content. The gaseous mixture comprises a polyatomic gas such as carbon dioxide having an upper level, ground state, and intermediate level. It also comprises at least one auxiliary gas such as nitrogen, having an energy level substantially resonant with one of the above-mentioned levels and a relaxation time operative to increase the ratio of the relaxation time of the upper level to that of the lower level. A chamber receives the mixture via a supersonic nozzle proportioned to provide a flow time short compared to the relaxation time of the upper level and long compared to the relaxation time of the lower level and the gas is throttled to a relative low second gas temperature and pressure, whereby population inversion exists in the chamber. An optical resonator defines a light path beam through the gaseous medium in the chamber.

Abstract: This invention is directed to the concept of providing fire protection for a caseless ammunition round by enveloping the round in an intumescent material. Means for stripping the intumescent material from the round, together with means for connecting a round to an adjacent round for forming a belt, are described.

Abstract: An apparatus for and method of suppressing infrared radiation emitted from hot metal parts at the aft end of a gas turbine engine and from the exhaust gas plume thereof is provided and such apparatus comprises a dual purpose ejector vane assembly operatively attached to the engine for introducing cooling ambient air into the hot engine exhaust gases and hiding the hot metal parts. The vane assembly has a duct structure for receiving and confining the engine exhaust gases and the assembly provides at least one stream of cooling ambient air across one full dimension of the duct structure and exhaust gases confined thereby with the stream of cooling ambient air mixing with the hot engine exhaust gases across the full dimension of the duct structure to assure optimum mixing thereof.

Abstract: Three-dimensional impregnated filamentary materials and methods for making the same.

Abstract: A procedure for providing bores or other internal passages in hot isostatically pressed powder metal articles, especially those formed of nickel- or cobalt-base superalloys in which the passage is defined by a thin walled metal tube filled with refractory oxide (MgO or SiO.sub.2), which is embedded in the metal powder. After hot isostatic pressing the refractory oxide core is removed by leaching, leaving a smooth bore in the finished article.

Abstract: The invention is directed to an apparatus and method of purifying contaminated water by means of a two-step freeze crystallization process. The method and apparatus overcomes the serious problem caused by the freezing of water on the screen of the wash column. The solution comprises means and method of reducing the temperature difference between the concentrate and the wash water in the wash column.

Abstract: Skywave propagation of quasi-sinusoidal signal sources generally results in multiple discrete Doppler shifts which can be associated with actual ionospheric modes in existence between the transmitter and receiver terminals at the operating frequency. The invention covers the application of monopulse direction finding techniques through the isolation of energy in each Doppler shifted mode through the use of high resolution spectrum analysis. More particularly, azimuth information is obtained by using the amplitude and/or phase responses of two antennae beams preferably in a monopulse configuration for each Doppler shifted mode.

Abstract: The invention is directed to the deposition of a coating on a substrate by reacting vaporized chemicals on contact with a heated surface to deposit a coating. According to the invention, the deposition surface is cleaned and coated in a single stage reactor. Means are also provided--where a boron deposit is wanted--to deposit an amorphous boron coating on the deposition surface.

Abstract: Lasing action is electrically induced in a supersonic flow of nitrogen gas, resulting in an increase in pulse repetition rate to a new order.