Abstract: A system is disclosed for detecting the laminar to turbulent boundary layer transition on a surface while simultaneously taking pressure measurements. The system uses an accelerometer for producing electrical signals proportional to the noise levels along the surface and a transducer for producing electrical signals proportional to pressure along the surface. The signals generated by the accelerometer and transducer are sent to a data reduction system for interpretation and storage.

Abstract: Apparatus for indicating the instantaneous angular deflection of an object about a selected axis without mechanical contact with the object. Light from a light source is transmitted through a first flat refractor to a converging lens which focuses the light through a second flat refractor onto a differential photocell. The first flat refractor is attached to the object such that when the object is deflected about the selected axis the refractor is also deflected about that axis. The two flat refractors are identical and they are placed an equal distance from the converging lens as are the light source and the photocell. The output of the photocell which is a function of image displacement is fed to a high gain amplifier that drives a galvanometer which rotates the second flat refractor. The second refractor is rotated so that the image displacement is very nearly zero making the galvanometer current a measure of the deflection of the object about the selected axis.

Abstract: Apparatus for remotely measuring and accessing water status relative to snow and glacial melt, surface runoff, rainfall, evaporation, flow rate, and soil moisture. A radar target located at a selected location on the surface of the earth is designed to collect water and render its cross-sectional area variable as a function of the height of the water level within the target. The target is remotely monitored by an orbiting or airborne synthetic aperature radar. The target appears as a bright spot embedded within the radar image. The target brightness is indicative of the height of the water level within the ground located target.

Abstract: An angular position transducer utilizing photocells and a light source is disclosed. The device uses a fully rotatable baffle which is connected via an actuator shaft to the body whose rotational displacement is to be measured. The baffle blocks the light path between the light source and the photocells so that a constant semicircular beam of light reaches the photocells.When the assembly is in the null position the illuminated area of each of the photocells is equal. As the actuator shaft rotates, the baffle also rotates which causes an increase in the area of illumination of one of the photocells together with an equal decrease in the area of illumination of the other photocell.The current produced by the photocells is fed through a resistor, a differential amplifier measures the voltage drop across the resistor which indicates the angular position of the actuator shaft and hence of the object.

Abstract: A method and apparatus for pressure testing the static pressure orifices and associated connections used in wind tunnels. A cylindrical module, having in one end an open hemispherical calibration pressure chamber separated from and surrounded by an annular vacuum chamber, is placed over the orifice of the system to be tested. O-rings ensure seating and a vacuum seal between the chambered end of the module and the surface around the orifice: one O-ring separates the two chambers and another separates the outer chamber from the outside environment. Ports lead from each of the chambers out the other end of the module to tubes connected to a control box consisting of calibration pressure and vacuum supply lines, bleeder valves, and guages. The calibration pressure supply may be above or below atmospheric pressure.

Abstract: Novel aromatic crystalline polimides are disclosed that are synthesized from polyamide-acid and when heated to 200.degree. to 300.degree. C. become cyclized to afford an opaque polymer which by X-ray diffraction of the unoriented film exhibited 47 percent crystallinity. Differential Scanning Calorimetry (DSC) indicates a melt at 425.degree. C. with no glass transition in these crystalline polyimides.

Abstract: A method and apparatus for inducing a Doppler frequency shift in a reference beam laser velocimeter light beam to simulate target velocity wherein the light beam is passed through a rotating refractive transparent block positioned between two reference points along the beam resulting in a continuous change in the light beam optical path length between the reference points according to a known function. The velocity indicated by the laser velocimeter is compared to the known simulated velocity function for velocimeter testing and calibration.

Abstract: A transducer that combines a noncontacting displacement probe with a self-contained target. The target is held in position against a vibrating surface by a housing which also supports the noncontacting probe. The target vibrates with the surface and the probe senses the vibrations of the target.

Abstract: A novel addition polyimide based on the use of liquid monomers wherein the essentially solventless prepreg produced therefrom retains good drape, tack and other mechanical properties.

Abstract: A seat cushion for providing realistic acceleration cues to an aircraft simulator pilot. A plurality of contiguous seat cushion compartments with each including an air cell with a non-compressible surface underneath the air cell are provided with apparatus for separately controlling the pressure in the air cells. Apparatus are provided for initially controlling the air pressure in the air cells to allow the two main support areas, the tuberosities, of the simulator pilot to touch the non-compressible surface and thus begin to compress the flesh near these areas. Thereafter during a simulated flight apparatus are provided for controlling the air pressure in the cells to simulate the events that occur in a seat cushion during actual flight.

Abstract: Apparatus for providing accurate pointing of instruments on a carrier vehicle and for providing isolation of the instruments from the vehicle's motion disturbances. The apparatus includes two assemblies, with connecting interfaces, each assembly having a separate function. The first assembly is attached to the carrier vehicle and consists of an azimuth gimbal and an elevation gimbal which provide coarse pointing of the instruments by allowing two rotations of the instruments relative to the carrier vehicle. The second or vernier pointing assembly is made up of magnetic suspension and fine pointing actuators, roll motor segments, and an instrument mounting plate around which a continuous annular rim is attached which provides appropriate magnetic circuits for the actuators and the roll motor segments.

Abstract: Apparatus for measuring pressure fluctuations in air or other gases in an area of elevated temperature. A condenser microphone is located in the area of elevated temperature and electronics for processing changes in the microphone capacitance is located outside the area and connected to the microphone by means of a high-temperature cable assembly. The microphone includes apparatus for decreasing the undesirable change in microphone sensitivity at high temperatures. The high-temperature cable assembly operates as a half-wavelength transmission line in an AM carrier system and maintains a large temperature gradient between the two ends of the cable assembly. The processing electronics utilizes a voltage controlled oscillator for automatic tuning thereby increasing the sensitivity of the measuring apparatus.

Abstract: An electrochemical detection device for detecting micro-organisms. A standard pH reference electrode and a platinum cathodic electrode are positioned in a container with suitable nutrient medium for microbial growth plus the sample to be tested. The two electrodes are connected to electronic circuitry including an up/down counter which counts up for the first 80 minutes after a test has been initiated. Then the potential between the two electrodes is tracked by the electronic circuitry and after there is a change of 10 mv a signal is sent to the up/down counter to cause it to reverse its count. Thereafter when there is a additional 20 mv change in the potential between the two electrodes another signal is sent to the up/down counter signalling it to stop. The resulting count on the counter is equal to the length of time for the inoculum to begin the production of measurable amounts of H.sub.2 after inoculation. This length of time is indicative of a endpoint.

Abstract: This invention is an improvement in aircraft control systems that utilize feedback motion sensors to generate a control signal to control the aircraft. The improvement consists essentially of a complementary filter comprising a simplified model of the aircraft, a high-pass filter, a low-pass filter and a summing amplifier. The control signal is applied to the simplified model of the aircraft which ateempts to compute the vehicle response to the signal. This computed response is then fed into the high-pass filter to eliminate long-term errors in the calculated response, with the result that a good estimate of the high frequency content of the aircraft motion is obtained. In order to obtain a good estimate of the low frequency content of the motion a rate gyro signal is fed through the low-pass filter that eliminates all of the offending noise. The outputs from the high-pass and low-pass filters are summed by the summing amplifier to produce an estimated rate which is then used as a motion feedback signal.

Abstract: An indicator for recording the load at which a fatigue specimen breaks during the last cycle of a fatigue test. A load cell is attached to the specimen which is alternately subjected to tension and compression loads. The output of the load cell which is proportional to the load on the specimen is applied to the input of a peak detector. Each time that the specimen is subjected to a compression load, means are provided for appyling a positive voltage to the reset of the peak detector to reset it. Hence, during the last cycle of the tension load the peak detector measures the maximum load on the specimen. Means are also provided for disconnecting the load cell from the peak detector when there is a failure in the specimen.

Abstract: Apparatus for measuring an aircraft's horizontal speed and height above ground without the need for airborne cooperative devices. Two ground level TV cameras separated by a measured distance and pointed at zenith are placed in line with the projection of the expected path of the aircraft. Speed is determined by measuring the time that it takes the aircraft to travel between the fields of view of the two TV cameras using zenith crossings as the reference points. Height is determined by correlating the speed with the time required to cross the field of view of either of the two cameras.

Abstract: A wing, for aircraft of cropped, arrow-type planform with thin leading and side edges, having a pivotable tip to alter the crop angle of the wing during flight. Increasing the crop angle causes the wing side edge to become a trailing edge which reduces the strength of the side edge vortex flow. Decreasing the crop angle causes opposite results, in particular the side edge is now a leading edge and can generate a leading edge vortex flow. The wing constitutes a roll control device for aircraft of the stated design particularly effective at higher angles of attack.

Abstract: A device for generating burst signals that can be used to determine whether or not a laser doppler velocimeter is operating properly. A high frequency signal which corresponds to the information frequency of the laser doppler velocimeter is modulated by a low frequency signal to provide an envelope for the high frequency signal. The high frequency signal is modulated by the low frequency signal by any modulator means such as, for example, an analog multiplier. The low frequency signal is added to the modulated signal to provide pedestals for the resulting series of burst pulses. Then means are provided for selecting different combinations of these burst signals. Also means are provided for making the burst signals asymmetrical as desired. In addition, means are provided for varying the frequencies and amplitudes of the information, envelope and pedestal frequency signals in the burst signals.

Abstract: A fluid velocity measuring device which when placed in a freestream fluid flow causes vortices to be formed at a frequency proportional to the flow rate of the fluid. Sensors on the device generate electric signals with frequency proportional to the rate of vortex creation and with relative mean amplitudes indicative of fluid flow direction. Electric circuitry translates the electric signals into indications of fluid speed and direction.

Abstract: Automatic liquid volume compensation apparatus is disclosed having particular application to septic systems. The apparatus limits septic tank air volume to optimize bacterial decomposition of wastes and controls the flow rate from the inlet piping through the tank to the drain field to limit passage of unprocessed fluid and prevent backups in the inlet piping.In the first of two embodiments, a bladder within a settling tank inflates or deflates to accommodate changes in liquid volume while maintaining tank level within desired limits. In the second embodiment, an auxiliary tank stores excess liquid which is returned to the primary settling tank when settling tank liquid level has declined to a desired height.