Abstract: A reflectance modulator (10) includes a reflective plate (16) with a plurality of slots (18) forming a slot matrix of square portions (20). Side wall plates (22) are each slidingly received within a slot (18) forming a plurality of black body cavities (24) facing incoming radiation. Actuators (28) support the reflective plate (16) with respect to an object surface (12) and are energizable to modify the spacing of plate (16) from the surface (12) changing depth of the cavities (24) and reflectance of radiation.

Abstract: An antenna (10) is provided by a metal layer (12) deposited on a dielectric substrate (16) which is etched to form a pair of symmetrical slot sections (20,22) having facing edges which increasingly curve away from each other to a maximum spacing point which is the antenna aperture (26). A linking slot (32) interconnects the slot sections (20,22) at a feed point (30) spaced from the aperture (26). High frequency electrical voltage applied at the feed point (30) achieves launch of an electromagnetic wave from the aperture (26). An alternative feed network uses a 180.degree. hybrid (60) providing simultaneous horizontal and vertical polarization operation.

Abstract: Restraining and tensioning apparatus (10) for a cargo tie-down belt (12) has a chassis (26) with a fluted spindle (98) onto which the belt is wound, ratchet gears (120,122), tensioning lever (28), and two pairs of locking pawls (136, 138, 148, 150), each locking pawl being engaged by an individual spring urging the pawl into contact with a ratchet gear.

Abstract: A method and an apparatus for active structural acoustic control (ASAC) of sound radiation from and noise transmission through a structure. The method derives acoustic far-field information, corresponding to a `virtual` planar array of microphones, from a vibrational field induced on the structure. The far-field information is used to compute error signals which are provided to an adaptive controller which controls actuators mounted on or embedded in the structure so as to suppress the flexural modes of structure vibration generating acoustic energy. The method is generally applicable to any structure and set of environment boundary conditions. An implementation of the method includes an array of accelerometers mounted on one face of a planar panel, an array of piezoceramic actuators mounted on an opposite panel face, and a frequency-domain adaptive controller utilizing a set of wavenumber-space algorithms.

Abstract: A coating having resistance to chemical warfare agents, comprising a cured mixture of (a) a polysiloxane having unsaturated groups available for cross-linking, (b) a polysiloxane containing reactive Si-H groups and (c) an unsaturated compound such as ethyl acrylate to prevent formation of bubbles in the coating due to the liberation of hydrogen from such Si-H groups during curing, and to provide a smooth bubble-free coating. A platinum siloxane catalyst is also employed in the mixture. A representative coating composition is a mixture of compounds (a) polydimethylsiloxane, vinyl dimethylterminated; (b) polymethylhydrosiloxane, and (c) ethyl acrylate; and platinum-divinyltetramethyldisiloxane complex catalyst. The coating composition cures at room temperature and in a relatively short period of time.

Abstract: A tool for fabricating fiber reinforced resin matrix composite structures having molded outside surfaces with intermittent molded inside surfaces e.g. aircraft skin with internal stiffeners. The tool employs a hybrid vacuum bag with soft portions in combination with rigid portions to produce the internal stiffeners. The stiffeners are supported and shaped during curing by pressurized elastomeric tubes, in lieu of mandrels, which can be easily removed when collapsed. The stiffeners and skin can be made from wet lay-ups or prepregs, formed in place or preformed, and in combinations where one part is precured or both parts are co-cured.

Abstract: A notch antenna (10) has a metallic notch element (20) deposited on a dielectric substrate (12), which element has a smooth continuously curved edge located adjacent a substrate edge (18). A metallic ground plane (28) is located adjacent the substrate edge (18) spaced very closely to element 20 at one end and at a gradually increased spacing moving away from the one end. An electromagnetic field transmitting coaxial cable (30) with ferrite beads (44) received over its outer conductor for reducing spurious radiation is located on the opposite side of substrate (12,14). The cable center conductor (34) is connected to a metallic strip (38) that is located on the same side of substrate (12,14) as the coaxial cable and tracks the same path as the notch element (20) on the opposite side of substrate (12). The antenna (10) is fed by electromagnetic energy at the closely spaced region of the element (20) and ground plane (28).

Abstract: Each of two risers is composed of a number of braided cords that are woven together. Each cord of one of the risers has a slit located where the two risers converge. Each slit provides communication with a concentric cavity in that cord. Each opposing cord for the other riser is inserted through the slit and has a section which lies in the cavity. When tension is applied, the braided cord enclosing the cavity radially constricts and the friction of the cavity walls holds the enclosed cord section in the cavity. The cords enclosing cavities continue on to become suspension lines connected to the parachute canopy. In one embodiment, each cord lying inside another terminates inside the cavity. Alternatively, the cord lying inside the cavity exits the cavity through a second slit and continues on to become another extension line. To connect the risers to an article to be decelerated by the parachute, the cords for both risers have slits near their ends. Each slit communicates with a concentric cavity.

Abstract: An adjustable phase shifter is formed of an RF transmission line having an internal cavity, in which the phase shift produced is determined in part by a mound of flowable dielectric material in the internal cavity. An inlet tube defines a chute for dispensing the dielectric material into the internal cavity and a capped outlet tube connected to a bottom end of the internal cavity defines another gravity chute through which the dielectric material is removed to lower the height of the mound, when the cap is removed from the tube. The electrical length of the phase shifter is increased with addition of dielectric material and decreased with removal thereby varying the effective length of the RF transmission line and the phase shift produced on the RF that propagates therethrough.

Abstract: A dual-mode high speed rotorcraft is disclosed which combines the efficiency of a helicopter with the high-speed capability of a fixed wing aircraft. The rotorcraft includes a rotor for propulsion during low-speed flight and hover, which is stopped and locked to function as a fixed wing during a high-speed flight. Also included are a canard and a high-lift tail, which together function to provide substantially all of the lift for the rotorcraft during the transition between low and high-speed flight, so that the rotor may be unloaded while starting and stopping.

Abstract: A secure fiber optic communication that is based on physical properties of light propagating through a Sagnac interferometer in combination with optical power alarms. These alarms are then used to alert users to intrusion and to shut down communications to avoid compromising data.

Abstract: An electro-optical contact assembly provides a connection between an electrical system and a fiber optic system for transmission of a signal therethrough. The assembly includes a converter for converting the signal between electrical and optical forms. The assembly also includes a receptacle with a retention mechanism mounted thereon which allows secure retention of an optical fiber terminus in the receptacle. The retention mechanism allows manual release of its clip from engagement with the optical fiber terminus in order to allow removal of the terminus from the receptacle, thereby allowing optical connection and disconnection of the assembly from the electrical system as well as other systems by simply plugging and unplugging fiber optic termini into and out of the contact assembly. The assembly includes a conductor surrounding the receptacle and terminus to provide EMI and RFI shielding of the terminus.

Abstract: A method and apparatus for a fiber optic measuring system is disclosed which works on the speed of propagation principle. The device can be utilized to determine the position of a disturbance or electronic source along the length of an optical path.

Abstract: An optical seeker (10) has an objective lens group (12) with a wide field of view (e.g., up to about 180 degrees). Light energy from objects within a field of regard is focused by the objective lens group (12) onto the end of a congruous overlay rod (24) and on exiting the rod it is acted upon by a two-dimensional matrix shutter (46) to selectively pass only one small zone (50) while suppressing passage of the remainder of the light energy. A light sensing array 22 is of such size as to merely accommodate one zone (50) at a time.

Abstract: A radar target generator is disclosed which is not merely a simulator, generating video information for viewing by an operator, but is designed to be used in conjunction with an operating radar system, actually producing high fidelity radar targets, rather than targets that merely look like radar targets. Thus, it may be used for training of radar operators, as well as for calibrating, maintaining, and evaluating multiple types of radar systems. The system includes a first tap for sampling a portion of the radar signal traveling through a transmission line and redirecting that sample into the radar target generator. There, a central processor applies a target signature component to the sampled radar signal portion, following which a second tap returns the modified radar signal portion to a return radar signal traveling thorough a second transmission line.

Abstract: A closed loop fully self-contained actuation system for converting a mechanical input motion into a mechanical output motion, which actuates a device such as a flight control surface on an aircraft, comprises an input actuator including a first fluid pressurizing means responsive to the mechanical input motion, and an output actuator including a second fluid pressurizing means, as well as a flexible fluid line extending between the first and second fluid pressurizing means to provide fluid communication therebetween. The second fluid pressurizing means is responsive to fluid flow through the fluid line, thereby initialing the output motion. The system is advantageous because it requires no hydraulic pumps, no accumulators, no reservoirs, and no dynamic seals or mechanical joints, permitting great reliability. The actuation system may be easily folded in conjunction with the apparatus on which it is employed, for compact storage.

Abstract: A nozzle is adapted to receive an ultrasonic transducer. The nozzle includes a cylindrical plenum chamber. An annular passageway circumscribes the plenum chamber. A porous material forms the annular walls of the plenum chamber and separates the plenum chamber from the passageway. The plenum chamber fluidly communicates with the passageway through the porous material. The passageway fluidly communicates with a supply line that, in turn, fluidly communicates with a pump that supplies water. The plenum chamber has a circular exhaust orifice for the exhaust of water from the nozzle. The plenum chamber contains an unobstructed forming space to facilitate the forming of ultrasonic waves. The diameter of the plenum chamber divided by the diameter of the exhaust orifice is a quotient of at least three.

Abstract: An integral overwrap protective system for a vehicle, e.g., a missile. Includes a filament wound fiber reinforced rubber matrix over a fiber-reinforced composite laminate which forms the vehicle inner skin and a final elastomeric outer coating. The integral overwrap avoids the bonding between vehicle skin and the protective system as in the present systems.

Abstract: Sagnac interferometer based secure communications systems are integrated into high speed data transfer rate networks using a smaller number of separate fiber optic cables than would be required if networks were constructed from pluralities of point-to-point systems. Redundancy can be provided in the networks to enable the network to operate even if multiple failures occur in the network.

Abstract: A system is disclosed for mounting a vibration producing device onto a spacecraft structure and also for isolating the vibration forces thereof from the structure. The system includes a mount on which the device is securely mounted and inner and outer rings. The rings and mount are concentrically positioned. The system includes a base (secured to the structure) and a set of links which are interconnected by a set of torsion bars which allow and resist relative rotational movement therebetween. The set of links are also rotatably connected to a set of brackets which are rigidly connected to the outer ring. Damped leaf springs interconnect the inner and outer rings and the mount allow relative translational movement therebetween in X and Y directions.