Abstract: A dual two-beam differential interferometer that measures both the amplitude and orientation of propagating, broadband surface acoustic waves. Four beams are focused on a surface. The four reflected beams are separated into two pairs. The two pairs are detected to produce two signals that are used to compute amplitude and orientation.

Abstract: A method for determining the potential of zero charge of an unpowdered semiconductor material. The semiconductor material is used as the working electrode 12 of a standard three-electrode photoelectrochemical cell 11. The onset potential of the semiconductor material is measured at several different cell temperatures. The slope of the graph of onset potential versus temperature is used to compute the potential of zero charge.

Abstract: Phenoxy resins containing pendent ethynyl groups, the process for preparing the same, and the cured resin products obtained therefrom are disclosed. Upon the application of heat, the ethynyl groups react to provide branching and crosslinking with the cure temperature being lowered by using a catalyst if desired but not required. The cured phenoxy resins containing pendent ethynyl groups have improved solvent resistance and higher use temperature than linear uncrosslinked phenoxy resins and are applicable for use as coatings, films, adhesives, composited matrices and molding compounds.

Abstract: A strain transducer system 10 and process for making same is disclosed wherein a beryllium-copper ring 13 having four strain gages 12, 14, 26 and 28 disposed thereon and electrically connected in Wheatstone bridge fashion to output instrumentation 25. Tabs 16 and 20 are bonded to a balloon or like surface 11 with strain on the surface 11 causing bending of ring 13 and providing an electrical signal through gages 12, 14, 26 and 28 proportional to the surface strain. FIG. 2 illustrates a pattern of a one-half ring segment as placed on a sheet of beryllium-copper for chem-mill etch formation, prior to bending and welding of a pair of the segments to form a ring structure 13.

Abstract: A rubber-toughened addition-type polyimide composition having excellent high temperature bonding characteristics in the fully cured state and improved peel strength and adhesive fracture resistance physical property characteristics is disclosed. The process for making the improved adhesive involves preparing the rubber-containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride has been mixed, and utilizing solvent or mixture of solvents for the reaction.

Abstract: A device which corrects aerodynamic spin wherein a collapsible boom 42 extends an aircraft moment arm and an anti-spin parachute force 24 is exerted upon the end of the moment arm to correct intentional or inadvertent aerodynamic spin. This configuration effects spin recovery by means of a parachute 30 whose required diameter 32 decreases as an inverse function of the increasing length of the moment arm. The collapsible boom 42 enables the parachute 30 to avoid the aircraft wake 50 without mechanical assistance, retracts to permit steep takeoff, and permits a parachute 30 to correct spin while minimizing associated aerodynamic, structural and in-flight complications.

Abstract: The invention relates to a smoke generator capable of emitting a very thin, laminar stream of smoke for use in high detail flow visualization. The generator is also capable of emitting a larger but less stable "rope" of smoke. The invention consists of a pressure supply 29, and fluid supply 28, which supply smoke generating fluid 25 to feed tube 22. Feed tube 22 is directly heated by electrical resistance from current supplied by power supply 30 and regulated by constant temperature controller 32. Smoke exit hole 21 is drilled in the wall of feed tube 22. Because feed tube 22 is heated both before and past exit hole 21, no condensation of smoke generating fluid occurs at the smoke exit hole, enabling the production of a very stable smoke filament 16. The generator is small in size, thereby avoiding wind turbulence in front of the test model 11.

Abstract: A reusable metal clamp 10 for retaining a fused quartz ampoule 25 during temperature cycling in the range of 20.degree. C. to 1000.degree. C. A compressible graphite foil 27 having a high radial coefficient of thermal expansion is interposed between the fused quartz ampoule 25 and metal clamp 10 to maintain a snug fit between these components at all temperature levels in the cycle.

Abstract: A process for preparing a thermoplastic poly(imidesulfone) is disclosed. This resulting material has thermoplastic properties which are generally associated with polysulfones but not polyimides, and solvent resistant which is generally associated with polyimides but not polysulfones. This system is processable in the 250.degree.-350.degree. C. range for molding, adhesive and laminating applications. This unique thermoplastic poly(imidesulfone) is obtained by incorporating an aromatic sulfone moiety into the backbone of an aromatic linear polyimide by dissolving a quantity of a 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) in a solution of 3,3'-diaminodiphenylsulfone and bis(2-methoxyethyl)ether, precipitating the reactant product in water, filtering and drying the recovered poly(amide-acid sulfone) and converting it to the poly(imidesulfone) by heating.

Abstract: The invention relates to a hot melt adhesive attachment pad for releasably securing distinct elements together and particularly useful in the construction industry or a spatial vacuum environment. The attachment pad consists primarily of a cloth 11 selectively impregnated with a charge of hot melt adhesive 12, a thermo-foil heater 13 and a thermo-cooler 14. These components are securely mounting in a mounting assembly 17 and 18. In operation, the operator activates the heating cycle transforming the hot melt adhesive to a substantially liquid state, positions the pad against the attachment surface, and activates the cooling cycle solidifying the adhesive and forming a strong, releasable bond.

Abstract: The basic heat pipe principle is employed to provide a self-contained passively cooled probe that may be placed into a high temperature environment. The probe consists of an evaporator region 13 of a heat pipe 10 and a sensing instrument 17. Heat is absorbed as the working fluid 22 evaporates in the probe. The vapor is transported to the vapor space 14 of the condenser region 15. Heat is dissipated from the condenser region and fins 20 causing condensation of the working fluid, which returns to the probe by gravity and the capillary action of the wick 18. Working fluid, wick and condenser configurations and structure materials can be selected to maintain the probe within an acceptable temperature range.

Abstract: Traditional roll control systems such as ailerons, elevons or spoilers are least effective at high angles of attack due to boundary layer separation over the wing. This invention uses independently deployed leading edge flaps 16 and 18 on the upper surfaces of vortex stabilized wings 12 and 14, respectively, to shift the center of lift outboard. A rolling moment is created that is used to control roll in flight at high angles of attack. The effectiveness of the rolling moment increases linearly with angle of attack. No adverse yaw effects are induced. In an alternate mode of operation, both leading edge flaps 16 and 18 are deployed together at cruise speeds to create a very effective airbrake without appreciable modification in pitching moment. Little trim change is required.

Abstract: A sensor for measuring flow direction and airspeed that is suitable, because of its small size, for rapid instrumentation of research airplanes. A propeller driven sphere rotating at a speed proportional to airspeed presents a reflective target to an electro-optical system such that the duty cycle of the resulting electrical output is proportional to yaw angle and the frequency is proportional to airspeed.

Abstract: Method and apparatus for making in-situ measurements of flow resistivity on the Earth's ground surface. The novel feature of the invention is two concentric cylinders, 22 and 23, inserted into the ground surface 24 with a measured pressure 21 applied to the surface inside the inner cylinder 22. The outer cylinder 23 vents a plane B-B beneath the surface to the atmosphere through an air space 28. The flow to the inner cylinder is measured (16) thereby indicating the flow from the surface to the plane beneath the surface.

Abstract: This invention is a wind tunnel model mount system (10) for effectively and accurately determining the effects of angle of attack and airstream velocity on a model airfoil or aircraft. The model mount system includes a rigid model (30) attached to a splitter plate (11) which is supported away from the wind tunnel wall (20) by a plurality of flexible rods (12). Conventional instrumentation (21) is employed to effect model rotation through turntable (13) and to record model (30) flutter data as a function of the angle of attack versus dynamic pressure.

Abstract: A resin product useful as an adhesive, composite or casting resin and the process for preparing same to improve the flexural strength mechanical property characteristics thereof. This improved flexural strength is attained with little or no change in density, thermal stability or moisture resistance by chemically incorporating 1.2 to 10.6% by weight Co(III) ions in an epoxidized resin system.

Abstract: The invention is a structure for a strong, lightweight corrugated sheet. The sheet is planar or curved and includes a plurality of corrugation segments, each segment being comprised of a generally U-shaped corrugation 12 with a part-cylindrical crown 13 and cap strip 20, and straight side walls 14 and 15 with secondary corrugations 16 oriented at right angles to said side walls. The cap strip 20 is bonded to the crown 13 and the longitudinal edge 18 of said cap strip extends beyond edge 17 at the intersection between said crown and said side walls. The high strength relative to weight of the structure makes it desirable for use in aircraft or spacecraft.

Abstract: This invention is an airfoil which has particular application to the blade or blades of rotor aircraft and aircraft propellers. The airfoil thickness distribution, camber and leading edge radius is shaped to locate the airfoil crest at a more aft position along the chord, and to increase the freestream Mach number at which sonic flow is attained at the airfoil crest. The upper surface of the airfoil has a general reduction in the surface slope back to the maximum ordinate which is about 40 percent of the airfoil chord. The reduced slope causes a reduction in velocity at the airfoil crest at lift coefficients from zero to the maximum lift coefficient. The leading edge radius is adjusted or shaped so that the maximum local Mach number at 1.25 percent chord and at the designed maximum lift coefficient is limited to about 0.48 when the Mach number normal to the leading edge is approximately 0.20.

Abstract: This invention relates to a hand held hydraulic cutting tool particularly useful to deactivate ejection seats in military aircraft rescue operations. The tool consists primarily of a hydraulic system composed of a fluid reservoir 11, a pumping piston 16, and an actuator piston 26. Mechanical cutting jaws 28, 29 are attached to the actuator piston rod 26. The hydraulic system is controlled by a pump handle 18. As the pump handle 18 is operated the actuator piston rod 26 is forced outward and thus the cutting jaws are forced together. The frame of the device is a flexible metal tubing 30 which permits easy positioning of the tool cutting jaws in remote and normally inaccessible locations. Bifurcated cutting edges 28a and 28b ensure removal of a section of the tubing or cable (40, FIG. 3) to thereby reduce the possibility of accidental reactivation of the tubing or cable being severed.

Abstract: A reusable, externally applied thermal protection system is disclosed and functions by utilizing shell tile structure 10 which effectively separates its primary functions as an insulator and load absorber. Tile 10 consists of structurally strong upper and lower metallic shells 12,16 manufactured from materials meeting the thermal and structural requirements incident to tile 10 placement on the spacecraft. A lightweight, high temperature package of insulation 26 is utilized in upper shell 12, while a lightweight, low temperature insulation 28 is utilized in lower shell 16. Assembly of tile 10, which is facilitated by self-locking mechanism 20, may occur subsequent to installation of lower shell 16 on the spacecraft structural skin 30.