Abstract:
A method of making an expanded metal sandwich structure (42) includes cleaning the appropriate parts prior to each bonding step in the process to remove metal oxides and residues that would interfere with the bonding steps. The core sheets (44, 46) are placed face-to-face and a gas pressure line fitting (52) is inserted between one edge and is welded into place. The core sheets (44, 46) are pressed together and laser welded together into a core pack (45) along lines which will form junction lines between the core sheets (44, 46) when the core pack (45) is superplastically expanded. Two metal face sheets (48, 50) having superplastic characteristics are placed over and under the core pack (45). An envelope gas fitting (54) is placed between the face sheets and is welded in place while seal welding around the entire peripheral edges of the face sheets (48, 50) and the core pack (45) to produce a sealed envelope pack (47) enveloping the core pack (45).
Abstract:
A power distribution circuit is provided that isolates both power source and load faults. In one embodiment, the power distribution circuit includes two power MOSFETs connected with the channels of the power MOSFETs in series and having their gates electrically connected together. The body diode of one power MOSFET is aligned with the opposite polarity with respect to polarity of the body diode of the second power MOSFET. The power MOSFETs are adapted to be coupled between a first power source and a load. The power distribution circuit also includes a first sensor that detects when the power MOSFETs conduct too much current and switches the power MOSFETs off by discharging the gate voltage of both power MOSFETs during such overcurrent conditions. Accordingly, when both power MOSFETs are switched off, the opposing polarity of the body diodes in the power MOSFETs ensures that one of the body diodes will be reversed biased in case of a short circuit failure in either the load or the power source. Incorporating N such power circuits in a power distribution module for distributing power from N power sources to a single load provides a fault tolerant power distribution module that can tolerate up to N-1 power source faults.
Abstract:
Apparatus (1 or 301) for use in making a laminated article having a three-dimensional contoured shape, said apparatus (1) comprising: (a) lay-up tool means (31 or 308) for receiving plies of a laminating material, said lay-up tool means having a three-dimensional contoured surface; (b) support table means (34) for supporting said lay-up tool (31 or 308); (c) laser projection means (72) for marking the location of a ply by projecting an image defined by a three-dimensional data set (33) onto said lay-up tool (31 or 308); (d) compactor means (35) for compacting a ply of material laid on said surface of said lay-up tool (31 or 308); and (e) control means (47) for controlling said laser projection means (72) and said compactor means (35).
Abstract:
A glide slope antenna for receiving information transmitted from the ground, including elevation guidance for the final approach. The glide slope antenna is integrated with the aft nose wheel door and utilizes the inherent electrical properties associated with the graphite/epoxy composite door.
Abstract:
A cascade assembly (14) for use in a thrust reversing mechanism (16) of a jet engine (18) includes at least one group of substantially identically-shaped cascade elements (28) each in the shape of a predefined polygon. The cascade elements (28) are positioned in an array, wherein each cascade element (28) in the group may be interchanged in a location in the array with any other cascade element (28) in the group. In a first preferred embodiment, the predefined polygon is a regular polygon and each cascade element (28) is rotatable in its array position about an axis generally normal to the cascade element (28). The array substantially approximates sections of two intersecting spheres, wherein a central axis of the array is generally coincident with the longitudinal axis of the jet engine (18). The cascade elements (28) are supported in the cascade assembly (14) by a truss structure (30) having a framework defining openings (32) in the shape of the predefined regular polygon for receiving the cascade elements (28).
Abstract:
A thermal condition sensor system monitors equipment such as aircraft engines. The thermal condition sensor system includes a collector which collects radiation from the equipment and a detector assembly which detects collected radiation over a discriminating spectral band region in at least three spectral bands and generates signals representative of detected radiation in each spectral band. A processor receives the signals and generates a report of the thermal conditions of the equipment using interband comparison of the at least three spectral bands.
Abstract:
An optical position sensing system for sensing the position of a displaceable element. An electro-optical unit outputs a modulated optical signal and a chirped rf signal. The envelope of the modulated optical signal has a phase that has a known relation to the phase of the chirped rf signal. The electro-optical unit is coupled to a light guide element and receives and transmits the modulated optical signal along an optical path for reflection off a surface of the displaceable element in order to provide a position sensing optical signal. A reference reflecting element is disposed in the optical path upstream of the displaceable element for partially reflecting the transmitted modulated optical signal in order to provide a reference optical signal. A transducing unit receives the rf signal at one input and has another input optically coupled for receiving the position sensing optical signal and the reference optical signal which have, respectively, first and second time delays with respect to the chirped rf signal. The transducing unit produces a multi-frequency electrical signal which includes first and second frequencies corresponding to the first and second time delays, respectively. A position detecting unit coupled to the output of the transducing unit processes the multi-frequency signal in order to determine a difference frequency corresponding to the difference between the first and second frequencies and representing the position of the displaceable element.
Abstract:
A tail rotor (8) for a rotary wing aircraft is located in a laterally directed duct (9) located at the end of a tail cone (7) extending rearward from the aircraft cabin and at the base of an empennage (5) extending upward from the duct. The rotor includes a rotor shaft (50) driveably connected to a power source, a rotor hub (10) connected to the rotor shaft (50), a rotating control shaft (64), a stationary control shaft (124), and an actuator (132) connected to the stationary control shaft (124) for moving the rotating control shaft (64) axially. The rotor hub (10) includes rotor arms (12) each supporting a pitch shaft-blade spar (18, 16) assembly for pivotable movement about a pitch axis. A pitch beam (96) supports flexures (94), each connected to a pitch arm (80) offset laterally from the associated pitch axis. The flexures (94) driveably connect the pitch arms (80) to the pitch beam (96) and transmit pitch control motion to the blades (14) as the pitch beam (96) moves along the rotor axis. Pitch bearings (20, 22), on which the pitch shafts (18) turn about the pitch axes, are supported on a rotor hub shell (46) fixed to the rotor hub (10).
Abstract:
An LED having a broadband emission spectrum. In one embodiment, the LED comprises a layered semiconductor structure of length L, the structure including an active layer comprising multiple asymmetric quantum wells. A pair of stripe electrodes is formed on a surface of the structure, to thereby form at least one optical cavity having a pumped length less than L. Currents to the cavities are controlled as a function of temperature to produce broadband emission over a range of temperatures.
Abstract:
An optical sensor in which both analog and digital techniques are employed. The sensor comprises an encoder and a detector. The encoder includes a plurality of tracks extending along a sensing axis. Each track has a property that varies along the sensing axis, such that the property can have one of three or more distinguishable levels. The detector detects the levels of the tracks at a position along the sensing axis, and produces corresponding output signals. The levels vary in a manner such that the output signals encode the position of the encoder with respect to the detector. The levels may vary in steps or continuously. For stepwise variable tracks, preferably only one track changes its level at any given position, and all changes in level occur in single steps. Both optical and electrical implementations are described.