Abstract: Herein described is a drift cancellation circuit for signal amplifiers used in multiplexed data monitoring systems. The effect of analog drift is essentially cancelled and the need for an initial or periodic zero adjustment is eliminated. The elimination of the need for drift adjustment is accomplished at the analog to digital A/D converter of the mutiplexer. The A/D converter is encircuited to measure the difference between the measured input channel and a referenced voltage obtained from a sample-hold circuit. Input to the sample-hold circuit is taken from the output to the signal amplifier chain used in processing incoming channel data.

Abstract: Apparatus is disclosed for the noncontact measurement of the clearance between the blade tips of a rotating turbine and the surrounding housing. Blade tip clearance is measured by placing a capacitance probe in the housing wall. The probe consists of two metallic conductors insulated one from the other and arranged to form the plates of a capacitor. Passing of a blade tip in close proximity to the two plates of the probe changes its capacitance. Electronic circuitry measures the change in capacitance and hence the clearance between blade tip and probe. Use of a balanced type input avoids the need for a ground return path and enables the use of a long sensor cable without degradation of results.

Abstract: A mobile cart-mounted unit for cleaning and preserving turbine engines comprises pressurized reservoirs for holding the solvent, cleaner, preservative and water. Pressurization is achieved by use of an integrally mounted air compressor driven by an internal combustion engine. The engine also powers an alternator which is used to charge a storage battery. The storage battery serves as an energy source to crank the turbine to approximately 10 percent rated speed during the cleaning and preservation servicing sequence. A control console provides the operator with the needed valves, gages and meters with which to operate the unit.

Abstract: Disclosed is an improvement in aircraft engines of the opposed piston type comprising cylinders arranged side by side. Cooling efficiency is improved and both average and hot zone temperatures are decreased by an improved air distributor comprising channel and divider members. The channel member is so proportioned and arranged as to admit air in an open mouth near the unfinned portions of adjacent cylinder barrels and to divert some of the barrel zone cooling air to the heads. The divider penetrates substantially into the zone between heads and is offset so that the larger portion of diverted air goes to the hotter head zone.

Abstract: The high power (10-1000 W) modulated carrier of a noisy transmitter is attenuated and amplitude limited and is used to control a power oscillator which regenerates the carrier and modulations without the loss of power. The power oscillator is slaved in frequency to the amplitude limited and attenuated signal, and it follows any phase or frequency modulation present thereon. Noise components appearing on the original carrier fall outside of the information passband of the power oscillator loop and therefore are not reproduced. The noise free output from the power oscillator is then A.M. modulated prior to power amplication and transmission. The oscillator operates at relatively high power (1 watt) and is automatically digitally coarse tuned and analog fine tuned.

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: 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: A storm window consisting of a rectangular window pane supported in a metallic frame is mounted over a window in a building by means of U-shaped channels mounted on the building and surrounding three sides of the building window. The storm window is slipped into channels and maintained in place by a friction or spring fit. The fourth side is closed by means of a U-shaped channel which is snapped or bonded onto the storm window frame.

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 tobacco smoke filter for use with a cigarette comprising a tube having a conical disc at its upstream end adjacent the tobacco. A capillary orifice through the apex of the conical disc permits discharge of tobacco smoke from the cigarette at high velocity into a downstream chamber for sublimation of alkaloids and other harmful matter to solid particles by rapid expansion. A parabolic disc is positioned in line with the high velocity jet to trap the solid particles and reverse flow to promote turbulence. The disc has a periphery closely adjacent the inner wall of the tube to promote a high speed flow around its edge. The resulting turbulence causes additional deposition of solids on the disc's downstream face. A tube integral with the disc extends to a circular opening in the downstream end of the tube for discharge of filtered smoke.

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: 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: 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: A radio frequency FM repeater system receives and retransmits at the same frequency, the retransmitted signal having the same deviation as the received signal. To accomplish this the IF filter is notched at its center frequency and the receiver feedback loop is inhibited when the received IF is within the notch, i.e., at the IF center frequency. In addition, the system is stabilized and the deviations of the received and retransmitted signals are kept equal by using positive feedback within the FM receiver, the feedback loop having a gain of 0.5.

Abstract: A gas turbine engine air inlet having an improved separator for particulate matter is described. Liner means define an annular flow passage which curves inwardly to the entrance of the engine's compressor. Hollow struts extend radially through the curved portion of the air passage. A V-shaped trap provides particle receiving pocket portions which span adjacent struts and open into first chambers in the struts. A plate extends downstream of the upstream edge of the inner trap leg to define a narrow entrance to the pocket portions. The upstream edge of the inner trap leg is spaced inwardly of the inner liner means at the entrance portion to capture most, if not all, of the particulate matter entrained in the inner portion of the air stream. The outer liner means comprise first and second liners, with the latter having its upstream edge radially inward of the upstream edge of the outer trap leg and intermediate its length.

Abstract: Apparatus is disclosed for pumping gases laden with abrasive particles. The pump comprises a cylindrical outer housing within which there are three axially adjacent sections, namely; an inertial bypass inlet; a powered rotor midsection; and an annular exhaust diffuser. The inertial bypass inlet consists of an axially symmetric cone which diverts the heavier sand and dust particles toward the outer walls. Behind the conical deflector is an axially symmetric circular shroud. A rotor within the shroud draws in and accelerates partially clean air from the lee side of the cone while the majority of the sand and dust laden air passes between the shroud and the outside wall. Recombination of the entire airstream occurs at an ejector nozzle serving as an output of the powered rotor midsection. Contaminated air from the ejector nozzle experiences a pressure rise in the annular exhaust diffuser.

Abstract: A miniature flat spray nozzle is disclosed which delivers a fan-shaped mist of fuel to a gas turbine combustor from a narrow slot. The slot is formed by making a transverse cut in a fuel-carrying conduit at a location near its end. A specially formed part is inserted into the end of the conduit which, in addition to capping off the conduit, divides the space adjacent thereto into three small chambers. One chamber is immediately below the transverse slot. Four orifices in the bottom wall of this first chamber connect it with the other two chambers. Each of the lower chambers opens into the conduit at its upstream end. Fuel delivered down the conduit divides in two parts, passes through the orifices between the lower and upper chambers, undergoes turbulent mixing in the chamber adjacent the transverse slot, and issues forth from the slot as an atomized mist.

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.