Abstract: Acetylene terminated aspartimides are prepared using two methods. In the first, an amino-substituted aromatic acetylene is reacted with an aromatic bismaleimide in a solvent of glacial acetic acid and/or m-cresol. In the second method, an aromatic diamine is reacted with an ethynyl containing maleimide, such as N-(3-ethynylphenyl)maleimide, in a solvent of glacial acetic acid and/or m-cresol. In addition, acetylene terminated aspartimides are blended with various acetylene terminated oligomers and polymers to yield composite materials exhibiting improved mechanical properties.

Abstract: A high temperature polyimide composition prepared by reacting 4,4'-isophthaloyldiphthalic anhydride with metaphenylenediamine is employed to prepare matrix resins, adhesives, films, coatings, moldings, and laminates.

Abstract: A zero-play pin clevis joint for deployable space structures includes a tapered pin and tapered bores extending through a shackle and through a tang such that the tapered pin is received in the tapered bores. Spring washers urge the tapered pin into the tapered bores of the shackle and also urge the tang onto the tapered pin. Deployable truss structures use a plurality of the aforementioned zero play pin clevis joints to connect a plurality of truss tubes. The angle of taper for the various components is preferably about 12.degree. included angle.

Abstract: An electro-optical spin measurement system for a spin model in a spin tunnel includes a radio controlled receiver/transmitter, targets located on the spin model, optical receivers mounted around the perimeter of the spin tunnel and the base of the spin tunnel for receiving data from the targets, and a control system for accumulating data from the radio controlled receiver and receivers. Six targets are employed. The spin model includes a fuselage, wings, nose and tail. Two targets are located under the fuselage of the spin model at the nose tip and tail, two targets are located on the side of the fuselage at the nose tip and tail, and a target is located under each wing tip. The targets under the fuselage at the nose tip and tail measure spin rate of the spin model, targets on the side of the fuselage at the nose tip and tail measure angle of attack of the spin model, and the targets under the wing tips measure roll angle of the spin model. Optical receivers are mounted at 90.degree.

Abstract: The invention is a boundary flow control system and method which comprises heating elements 24 to trigger boundary layer transition and audio speakers 83 to provide acoustic suppression 51 of boundary layer turbulence 52. The trigger and suppression control are activated by a feedback amplifier 82 which reads boundary layer flow conditions using an anemometer probe 81. The active control of the boundary layer permits delay of flow separation and a reduction in skin friction drag as compared to natural flow conditions.

Abstract: A metallic outer sleeve 10 is provided which is capable of enveloping a hollow metallic inner member 12 having continuous reinforcing fibers 14 attached to the distal end thereof. Inner member 12 is then introduced into outer sleeve 10 until inner member 12 is completely enveloped by outer sleeve 10. A liquid matrix member 20 is then injected into space 22 between inner member 12 and outer sleeve 10. A pressurized heat transfer medium 23 is flowed through the inside of inner member 12, thereby forming a fiber reinforced matrix composite material 26. The wall thicknesses of both inner member 12 and outer sleeve 10 are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure 28 to the desired value.

Abstract: This invention is a process for producing composite laminates containing interlaminar disbonds of controlled sizes, shapes, and positions within a composite structure. A composite layer is provided for later inclusion within a laminate. The surfaces of this composite layer are solvent cleaned and sandblasted, except in desired disbond areas, which are coated with a releasing surface. A template to mask the bond areas is employed to obtain disbond areas of controlled shapes and sizes. The resulting composite layer is then used in the subsequent manufacture of a laminate, whereby faulty adhesion in the laminate can be studied with prior knowledge of the size, shape, and location of the disbond areas.

Abstract: Actuated forebody strakes provide yaw control at high angles of attack. In one embodiment, the strakes are axially slidable in the forebody to be deployed out of slots provided for the strakes in the forebody. In another embodiment, the strakes are pivotally connected at the tip of the strakes to pivot radially outwardly out of the slots provided in the forebody. In another embodiment, the forebody is provided with either a single strake or two strakes and the forebody is rotatable to vary the radial location of the strake or strakes. All embodiments achieve significant yaw control capability over a wide angle of attack and sideslip ranges.

Abstract: The invention is a Clock for synchronizing operations within a high-speed, distributed data processing network. The clock is actually a distributed system comprising a Central Clock and multiple Site Clock Interface Units (SCIU's) which are connected by means of a fiber optic star network and which operate under control of separate clock software. The presently preferred embodiment is as a part of the flight simulation system now in current use at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC), Hampton, Va.

Abstract: A means for extracting rotational energy from the vortex created at aircraft wing tips which consists of a turbine with blades located in the crossflow of the vortex and attached downstream of the wingtip. The turbine 30 has blades 40, 41, 42 and 43 attached to a core 45. When the aircraft is in motion, rotation of core 45 transmits energy to a centrally attached shaft 50. The rotational energy thus generated may be put to use within the airfoil 20 or aircraft fuselage 10.

Abstract: A sensing device 50 comprising an O.sub.2 sensor 22, a pump 37, a compressor 19, and a heater 21 is provided to quickly sense the amount of O.sub.2 in a combustion product gas. A sample of the combustion product gas is compressed to a pressure slightly above one atmosphere by compressor 19. Next, heater 21 heats the sample between 800.degree. C. and 900.degree. C. Next, pump 37 causes the sample to be flushed against electrode 32 located in O.sub.2 sensor 22 6000 to 10,000 times per second. Reference air at approximately one atmosphere is provided to electrode 31 of O.sub.2 sensor 22. Accordingly, O.sub.2 sensor 22 produces a voltage which is proportional to the amount of oxygen in the combustion product gas. This voltage may be used to control the amount of O.sub.2 entering into the combustion chamber 10 which produces the combustion product gas.

Abstract: A catalyst for the combination of CO and O.sub.2 to form CO.sub.2 which includes a platinum group metal--e.g., platinum; a reducible metal oxide having multiple valence states--e.g., SnO.sub.2 ; and a compound which can bind water to its structure--e.g., silica gel. This catalyst is ideally suited for application to high-powered, pulsed, CO.sub.2 lasers operating in a sealed or closed-cycle condition.

Abstract: The invention relates to a process for crosslinking aromatic polymers containing radiation-sensitive methylene groups (--CH.sub.2 --) by exposing the polymers to ionizing radiation thereby causing crosslinking of the polymers through the methylene groups. Crosslinked polymers are resistant to most organic solvents such as acetone, alcohols, hydrocarbons, methylene, chloride, chloroform, and other halogenated hydrocarbon, to common fuels and to hydraulic fluids in contrast to readily soluble uncrosslinked polymers. In addition, the degree of crosslinking of the polymers depends upon the percentage of the connecting groups which are methylene which ranges from 5 to 50% and preferably from 25 to 50% of the connecting groups and is also controlled by the level of irradiation which ranges from 25 to 1000 Mrads and preferably from 25 to 250 Mrads. The temperature of the reaction conditions ranges from 25.degree. to 200.degree. C. and preferably at or slightly above the glass transition temperature of the polymer.

Abstract: The invention is an improvement in a lightweight carbon-carbon composite piston, the improvement comprehending the use of near-net shape knitted or warp-interlock pre-forms to improve the structural qualitites of the piston. In its preferred embodiment, a one piece, tubular, closed-ended, knitted pre-form (a sock) of carbon fibers (11) embedded within the matrix of the piston structure forms the crown (12), side wall (15), skirt (16) and inner surface (18) of the piston, and wrap-interlock pre-forms strengthen the piston crown and wrist pin bosses.

Abstract: Polyphenylquinoxalines are prepared by the nucleophilic displacement reaction of di(hydroxyphenyl)quinoxaline monomers with activated aromatic dihalides or dinitro compounds. The reactions are carried out in polar aprotic solvents using alkali metal bases at elevated temperatures under nitrogen. The di(hydroxyphenyl)quinoxaline monomers are prepared either by reacting stoichiometric quantities of aromatic bis(o-diamines) with a hydroxybenzil or by reacting o-phenylenediamine with a dihydroxybenzil or bis(hydroxyphenylglyoxylyl)benzene.

Abstract: A device 11 is provided for simultaneously dispensing masking paper 12 from a roll 13 and masking tape 14 from a roll 15 so that masking tape 14 is affixed to masking paper 12 in a position which is partially on and partially off a longitudinal edge 16 of masking paper 12. The device includes a main frame 17, which has a central arcuate section 18 that overlies and partially envelops masking paper roll 13, being substantially concentric therewith. The main frame 17 has a forward section 19, which is adapted to receive and secure tearing means 20 for severing a desired segment of the masking paper with affixed masking tape. Main frame 17 has a rearward section 21 forming a handle 22, which is located at substantially the same level and to the rear of arcuate section 18, between the masking paper roll 13 and the masking tape roll 15.

Abstract: A fluorinated poly(phenylene ether ketone) having one of the following structural formulas ##STR1## wherein X is selected from the group consisting of aryl, SO.sub.2, O, CO, --C(CH.sub.3).sub.2, and S, is prepared by reacting a bisphenol with 1,1,1,3,3,3-hexafluoro-2,2-bis[4-(4-halobenzoyl)phenyl]propane (wherein halo is fluoro or chloro), which is a novel monomer formed as the reaction product of halobenzene (wherein halo is fluoro or chloro) and 1,1,1,3,3,3-hexafluoro-2,2-bis(p-chloroformylphenyl)propane.

Abstract: A flight deflection measurement system including a hybrid microchip of a receiver/decoder. The hybrid microchip decoder is mounted piggyback on the miniaturized receiver and forms an integral unit therewith. The flight deflection measurement system employing the miniaturized receiver/decoder can be used in a wind tunnel. In particular, the miniaturized receiver/decoder can be employed in a spin measurement system due to its small size and can retain already established control surface actuation functions.

Abstract: Linear aromatic polyimides with low dielectric constants are produced by adding a diamic acid additive to the polyamic acid resin formed by the condensation of an aromatic dianhydride with an aromatic diamine. The resulting modified polyimide is a better electrical insulator than state-of-the-art commercially available polyimides.