Abstract: Thermal actuation of riblets is described herein. One disclosed example apparatus includes a riblet defining an aerodynamic surface of a vehicle. The disclosed example apparatus also includes a thermal expansion element within or operatively coupled to the riblet, wherein the thermal expansion element changes shape in response to a surrounding temperature, to displace a movable portion of the riblet relative to the aerodynamic surface to alter an aerodynamic characteristic of the vehicle.

Abstract: A thermoplastic composite structure is produced by extruding a bead of composite material to a desired cross sectional shape. An extruder extrudes the polymer bead containing reinforcing fibers, using a low compression first extruder stage where the polymer is mixed and de-gassed, and a high compression second stage where the polymer is consolidated and extruded. The cross sectional profile of the polymer bead may be altered using a variable extruder gate.

Abstract: A thermoplastic composite structure is produced by extruding a bead of composite material to a desired cross sectional shape. An extruder extrudes the polymer bead containing reinforcing fibers, using a low compression first extruder stage where the polymer is mixed and de-gassed, and a high compression second stage where the polymer is consolidated and extruded. The cross sectional profile of the polymer bead may be altered using a variable extruder gate.

Abstract: A system and method for preparing a fluid flow surface may include the steps of: (1) producing a laser beam, (2) moving the laser beam across a surface of a work piece, and (3) machining a riblet in the surface by removing material from the surface, wherein the riblet includes a pair of ridges, wherein the pair of ridges is approximately parallel to each other, and each one of the ridges includes opposed sides, and a groove formed between facing ones of the sides and separating the ridges.

Abstract: A method and apparatus for sealing a fastener that extends through a surface. The apparatus comprises a housing having a base and cap, wherein the cap is configured to cover a portion of a fastener extending through a surface, and wherein the housing is configured to apply suction to the surface.

Abstract: Methods and apparatus for forming microscopic features on a film layer are disclosed. An example method includes using a surface of a tool to contact a thermoplastic film coupled to an outer surface of a structure. The surface of the tool defines a first microscopic pattern. The example method also includes heating the thermoplastic film by moving the surface of the tool on the thermoplastic film to create friction between the tool and the thermoplastic film and urging the heated thermoplastic film into the first microscopic pattern of the surface of the tool to form a second microscopic pattern in the thermoplastic film.

Abstract: Thermal actuation of riblets is described herein. One disclosed example apparatus includes a riblet defining an aerodynamic surface of a vehicle. The disclosed example apparatus also includes a thermal expansion element within or operatively coupled to the riblet, wherein the thermal expansion element changes shape in response to a surrounding temperature, to displace a movable portion of the riblet relative to the aerodynamic surface to alter an aerodynamic characteristic of the vehicle.

Abstract: A method for sealing a fastener employs a mold which provided with an inlet port for molding material. The mold is then positioned over a fastener and the mold is sealed against a structure. A moisture cured polyurethane reactive adhesive (MCRPA) as a molding material is then heated and injected into the mold. Upon solidification of the MCRPA, the mold is then removed to expose the MCRPA to atmospheric moisture and cured to leave an in-situ molded cap formed over the fastener and sealed to the structure.

Abstract: A composite radius filler material is provided. The composite radius filler includes a resin, a first group of fibers dispersed within the resin, and a second group of fibers dispersed within the resin. The first group of fibers has a first length configured to facilitate orientation in a longitudinal direction. The second group of fibers has a second length that is shorter than the first length, with the second group of fibers configured to facilitate random orientation in a transverse direction.

Abstract: A system for depositing a composite filler material into a channel of a composite structure includes an end-effector configured to extrude a bead of the filler material into the channel. The filler material can comprise a first group of relatively long fibers, a second group of relatively short fibers and a resin. A drive system is configured to move the end-effector relative to the channel, and a position sensor is configured to detect the position of the bead relative to the channel. A controller is configured to operate the drive system in response to the detected position and to operate the end-effector to heat and compress the filler material so as to orient the longer fibers in a substantially longitudinal direction relative to the channel and the shorter fibers in substantially random directions relative to the channel when the bead is extruded into the channel.

Abstract: Actuatable microstructures and methods of making the same are disclosed. An example a sheet includes a first side including an elastomeric material and a second side opposite the first side. The sheet defines sealed channels. In response to a pressure differential across the elastomeric material, the elastomeric material is to be in a deformed position relative to the sealed channels to define microstructures.

Abstract: A method for sealing a fastener employs a mold which provided with an inlet port for molding material. The mold is then positioned over a fastener and the mold is sealed against a structure. A molding material is then injected into the mold. The mold is then removed to leave an in-situ molded cap formed over the fastener and sealed to the structure.

Abstract: This disclosure teaches an apparatus for cultivating plants that reduces the amount of lost water and increases the amount of water in the soil.

Abstract: An electrostatic colloid thruster for implementing a method of ionizing a liquid is disclosed herein. The electrostatic colloid thruster includes an electrically conductive extractor having a plurality of holes defined therethrough; an ultrasonic atomizer having an electrically conductive atomization surface at least partially facing the extractor and being arranged relative thereto so as to define a gap; a reservoir system in fluid communication with the atomization surface; and an electrical power source in electrical communication with both the extractor and the atomization surface. The apparatus and method are generally utile in various applications including, for example, spacecraft propulsion, paint spray techniques, semiconductor fabrication, biomedical processes, and the like.

Abstract: A method of ionizing a liquid is disclosed herein. The method includes the steps of dispensing an electrically conductive liquid onto an electrically conductive membrane so as to form a liquid film on the surface of the membrane, applying an electrical charge to the liquid film on the membrane, generating ultrasonic waves to vibrate the membrane so as to induce capillary waves in the liquid film, and electrostatically attracting the electrically charged crests in the capillary waves so that electrically charged droplets are extracted from the capillary waves and accelerated therefrom for emission. The method is generally utile in various applications including, for example, spacecraft propulsion, paint spray techniques, semiconductor fabrication, biomedical processes, and the like. In addition to the above-described method, an electrostatic colloid thruster for implementing the method is disclosed herein as well.

Abstract: An electrostatic colloid thruster for implementing a method of ionizing a liquid is disclosed herein. The electrostatic colloid thruster includes an electrically conductive extractor having a plurality of holes defined therethrough; an ultrasonic atomizer having an electrically conductive atomization surface at least partially facing the extractor and being arranged relative thereto so as to define a gap; a reservoir system in fluid communication with the atomization surface; and an electrical power source in electrical communication with both the extractor and the atomization surface. The apparatus and method are generally utile in various applications including, for example, spacecraft propulsion, paint spray techniques, semiconductor fabrication, biomedical processes, and the like.

Abstract: A method of ionizing a liquid is disclosed herein. The method includes the steps of dispensing an electrically conductive liquid onto an electrically conductive membrane so as to form a liquid film on the surface of the membrane, applying an electrical charge to the liquid film on the membrane, generating ultrasonic waves to vibrate the membrane so as to induce capillary waves in the liquid film, and electrostatically attracting the electrically charged crests in the capillary waves so that electrically charged droplets are extracted from the capillary waves and accelerated therefrom for emission. The method is generally utile in various applications including, for example, spacecraft propulsion, paint spray techniques, semiconductor fabrication, biomedical processes, and the like. In addition to the above-described method, an electrostatic colloid thruster for implementing the method is disclosed herein as well.

Abstract: A method of ionizing a liquid propellant is disclosed herein. The method includes the steps of applying an electrical charge to a showerhead, delivering a liquid propellant under pressure into a chamber defined within the showerhead, and emitting the liquid propellant under pressure through a plurality of micro-nozzles interspaced within the face of the showerhead to create a plurality of jets that collectively produce an electrospray having charged particles. An electric thruster that implements such a method is also disclosed herein. The thruster includes a showerhead having an inlet and a plurality of micro-nozzles, a reservoir for supplying propellant to the showerhead via the inlet, means for accelerating charged particles, and a power source connected to the showerhead and the accelerating means. The propellant is emitted under pressure from the micro-nozzles to produce an electrospray having charged particles. The charged particles are accelerated by the accelerating means to produce thrust.

Abstract: A method of ionizing a liquid propellant is disclosed herein. The method includes the steps of applying an electrical charge to a showerhead, delivering a liquid propellant under pressure into a chamber defined within the showerhead, and emitting the liquid propellant under pressure through a plurality of micro-nozzles interspaced within the face of the showerhead to create a plurality of jets that collectively produce an electrospray having charged particles. An electric thruster that implements such a method is also disclosed herein. The thruster includes a showerhead having an inlet and a plurality of micro-nozzles, a reservoir for supplying propellant to the showerhead via the inlet, means for accelerating charged particles, and a power source connected to the showerhead and the accelerating means. The propellant is emitted under pressure from the micro-nozzles to produce an electrospray having charged particles. The charged particles are accelerated by the accelerating means to produce thrust.