Abstract: One form of the method includes disposing a silver contact pad on only a portion of a metal body. The joint between the silver contact pad and the metal body includes a metal which is metallurgically compatible with the silver contact pad and with the metal body. Heat and pressure are applied to the joint through welding electrodes. This joins the contact pad to the metal body and forms a metallurgical bond therebetween. In one embodiment, the metal body comprises copper and the compatible metal comprises tin. The welding electrodes may include shaping surfaces thereon so that the contact pad can be joined to the metal body while substantially simultaneously shaping the combination of the contact pad and the metal body. The resultant contact pad is arc-resistant,i.e., resistant to erosion, and has a typical thickness in the range of from about 0.0005" to about 0.010".

Abstract: A thermally and electrically conductive strain buffer for a semiconductor device is made by a method that comprises the steps of (a) providing a plurality of straight, equal-length strands of copper, with the strands aligned such that their lengths are substantially parallel and their ends define a pair of opposing surfaces and (b) closing packing the strands together. Then, layers of highly conductive metal are deposited on said opposing surfaces, and the deposited metal layers provide sufficient structural integrity to hold the strands together so that the resulting strain buffer can be manipulated with substantially no break-up thereof and with substantially no loss of individual ones of the strands.

Abstract: A turbine shroud includes a ceramic sealing layer secured to a metal substrate. In one form, the metal substrate includes a plurality of pegs extending therefrom. Intermediate bonding layers are disposed on the peg-metal substrate structure. A ceramic sealing layer of zirconium oxide with about 20 weight percentage magnesium oxide is disposed, e.g., plasma sprayed, on the intermediate bonding layers. The ceramic sealing layer includes an ordered pattern of very fine cracks therein which reduce the thermal stress in the ceramic sealing layer. A method of constructing a turbine shroud structure is also disclosed.

Abstract: The apparatus includes a pair of rotatable headstocks which are spaced apart. A side beam extends along at least a portion of the distance between the headstocks with the side beam being substantially parallel to a line connecting the centers of rotation of the headstock. The headstocks are respectively of a configuration to securely receive an end of a first one of a plurality of cylindrical workpieces. Support means is provided for rotatably supporting the plurality of cylindrical workpieces in end-to-end manner with the longitudinal axes thereof being substantially coincident. Controllable welding means and controllable cutting means are coupled to the side beam and are capable of linear translation therealong. Controllable drive means is provided for: rotating the headstocks so that the cylindrical workpiece secured thereto is caused to rotate about its longitudinal axis; causing the welding means to translate along the side beam; and causing the cutting means to translate along the side beam.

Abstract: A method for constructing a turbine shroud structure includes providing a metal substrate with a plurality of pegs extending therefrom. A ceramic sealing layer of zirconium oxide with about 20 weight percentage magnesium is applied to the peg-metal substrate structure. Intermediate bonding layers may be applied between the ceramic sealing layer and the peg-metal substrate structure. The ceramic sealing layer is then heat treated to a temperature of 1100.degree. C. to increase the rub wear of the ceramic sealing layer and to reduce the thermal stress therein.

Abstract: A simplified fail-fixed electrohydraulic servovalve for operating with a source of fluid under pressure, and a piston translatably disposed within a bore. The piston has a rod side face area which is less than its head side face area and translates in a first direction for electrical input signals above a first predetermined percent of a maximum rated input signal. At a second percent of the rated input signal, determined by the ratio of the piston rod side face area to the piston head side face area, the piston position is fixed. For electrical input signals greater than the second percent of the rated input signal the piston translates in the second direction. Any input signal below the first percent causes the piston to be fixed in place.

Abstract: A gas turbine engine control system is provided. In a preferred control system for use in combination with a helicopter, input signals respectively representative of power turbine speed error, power turbine shaft torque, and compressor shaft speed are employed. From these input signals, five intermediate signals are developed. One of the intermediate signals represents the main rotor speed error. Each of the five intermediate signals is provided with a separate predetermined gain and coupled to summation means. The predetermined gains are selected to be of values which reduce the effects of resonances provided by the mail and tail rotors of the helicopter. The output of the summation means represents a control signal and may be employed to operate a fuel control valve.

Abstract: The angle of the variable blocker door vanes in the bypass duct of a turbofan engine is varied in response to the angle of the variable compressor vanes of the engine. A cam and linkage assembly interconnect the blocker doors with the actuation system of the variable stator vanes such that as the angle of the stator vanes is modulated through a first predetermined range, the angle of the blocker doors is modulated through a second predetermined range.

Abstract: Gas turbine engine thrust is controlled by automatically adjusting compressor rotational speed with novel functions of engine inlet temperature to hold thrust to rated values for varying engine inlet temperature conditions. Furthermore, compressor rotational speed is automatically adjusted as a function of inlet pressure to provide a thrust rating schedule which varies with altitude. Compressor corrected rotational speed is limited through a novel function of engine inlet temerature to protect against turbine overtemperature when the engine inlet temperature exceeds the flat thrust rating point.

Abstract: An integrated control system for a gas turbine engine is provided wherein the system includes fuel control means for metering the flow of fuel to the engine, position signal generating means for providing a position signal to control the fuel control means and biasing means for providing a signal to bias the position signal during a normal mode of operation. An interfacing means is provided to automatically limit the rate of change of the position signal in order to limit the rate at which the flow of fuel to the engine may be changed during a failed mode of operation when the biasing means is inoperative. A rate limiter means is also included within the control system to automatically limit the rate of change of the position signal in order to limit the rate at which the flow of fuel to the engine may be reduced during engine deceleration.

Abstract: The inspection apparatus self-adjusts for inspecting bolt-holes of a predetermined size range between a minimum inspection diameter and a maximum inspection diameter. A probe shaft is coupled through a ramp portion to a pear-shaped probe head. The probe head includes a sensor element at the perimeter thereof. An axial slot extends through the shaft and the probe head, dividing the probe head into two probe head sections. A first spring couples the probe head sections and normally urges the sections away from each other and toward the maximum inspection diameter. A cup is slidably positioned around the ramp portion such that, as the cup slides along the ramp portion toward the probe head, the two probe head sections are urged together and the minimum inspection diameter is approached. A second spring is positioned about the shaft to normally urge the cup to an extreme position along the ramp portion, resulting in the minimum inspection diameter.

Abstract: A method and apparatus for optimally controlling a gas turbine engine utilizes feedback signals each of which is a function of a plurality of output variables. Control signals are generated and transmitted to actuators which vary engine control variables to provide a desired level of engine performance. Signals representative of rated values of a plurality of engine output variables for the selected level of engine performance are generated and are compared with signals representative of actual values of the corresponding output variables to produce difference signals. One or more of the difference signals may also be integrated. The difference signals may also be weighted relative to each other as a function of ambient conditions and/or the selected level of engine performance. A plurality of the difference signals are then utilized to generate an individual feedback signal for each of the control variables. The feedback signals are tailored to modify the corresponding control variables.

Abstract: A static instantaneous overcurrent relay with reduced transient overreach is provided for use in protecting an a-c power line from overcurrents. The relay operates on an input signal representative of the magnitude of the current in the a-c power line and develops a relay output signal when the magnitude of the current reaches a predetermined magnitude. In a preferred embodiment, the relay includes a level detector circuit for receiving the input signal which is in the form of a pulsating waveform having the same frequency as the a-c power line. The level detector circuit develops a discrete level detector output signal in response to each pulse of the waveform which attains a magnitude representative of the predetermined magnitude. Output circuit means is coupled to receive the discrete level detector output signals and includes temporary inhibit means for inhibiting the development of the relay output signal until the output circuit has received two of the discrete level detector signals.

Abstract: An improved gas turbine engine control system maintains a selected level of engine performance despite the failure or abnormal operation of one or more engine parameter sensors. The control system employs a continuously updated engine model which simulates engine performance and generates signals representing real time estimates of the engine parameter sensor signals. The estimate signals are transmitted to a control computational unit which utilizes them in lieu of the actual engine parameter sensor signals to control the operation of the engine. The estimate signals are also compared with the corresponding actual engine parameter sensor signals and the resulting difference signals are utilized to update the engine model. If a particular difference signal exceeds specific tolerance limits, the difference signal is inhibited from updating the model and a sensor failure indication is provided to the engine operator.

Abstract: A removable instrumentation probe comprising a hollow member, preferably generally cylindrical, which extends through an opening in a wall. The member includes a band which projects outwardly from the member and is comprised of a plurality of circumferentially spaced apart tapered or curved segments which engage the interior of the wall opening to facilitate assembly and removal of the probe.

Abstract: An improved instrumentation probe is disclosed for use within a turbomachine, including an airfoil, such as of a vane, having a portion of its airfoil leading edge removed. The probe is disposed adjacent to the airfoil to replace the removed airfoil leading edge portion and to aerodynamically form the leading edge of the airfoil.

Abstract: A method and apparatus for suppressing internally generated gas turbine engine low frequency noise is disclosed. The apparatus is comprised of means for structuring the cross-sectional area of the gas flow path into one or more open elements of a predetermined size. The method involves a way of determining the size of each of the elements and the total number of elements.

Abstract: An integrated control system for a gas turbine engine of the turbofan type receives signals from a plurality of engine sensors and from the engine operator and generates control signals therefrom. A first control signal regulates the fan exhaust nozzle area in order to control inlet throat Mach number to maintain a low level of engine noise. Additional control signals regulate fuel flow to control engine thrust and fan pitch to control fan speed. A plurality of schedules are utilized to maintain a predetermined relationship between the controlled parameters and a number of fixed and calculated limits can override the control signals to prevent unsatisfactory engine performance.

Abstract: A timing valve is responsive to certain hydraulic rotor speed input signals so as to schedule increased temperatures of air to a turbine shroud support in accordance with the thermal time constants of the rotor. Clearance between the rotor and the shroud is thereby minimized during both transient and steady-state operating conditions. Temperatures are incrementally increased by selectively combining air from the compressor fifth and ninth stage bleed manifolds. Under certain operating conditions, the timing valve is pre-empted and air is provided at a predetermined temperature level as a function of rotor speed only.

Abstract: Cooling airflow to the shroud support apparatus is varied in response to both rotor speed and elapsed time above a predetermined level by the selective use and mixture of two air sources at different temperatures. For steady-state operation, each of four different operating modes has its prescribed cooling air delivery mode such that, generally, as the engine speed and cycle temperatures increase, so does that of the cooling air. For transient operation, a timer is employed to sequence the desired cooling air delivery modes in such a manner as to maintain optimum rotor-to-shroud clearances during the transient period.