Innovative Solutions & Support, Inc.

Other

Donaldson Comapny, Inc.

Smiths Industries Plc

Innovative Solutions & Support, Incorporated a Corporation of

Innovative Soslutions and Support, Incorporated

Smiths Industries Aerospace & Defence Systems Inc.

Geoffrey S Hedrick

Steven L Tomlinson

An air data measurement system includes a device for sensing air pressure outside an aircraft, a pressure transducer in fluid communication with the air pressure sensing device and having a piezoresistive bridge attached on a flexible diaphragm. The piezoresistive bridge has an electrical resistance which varies in response to the sensed air pressure applied to the diaphragm and whose sensitivity varies with the magnitude of the excitation current passing therethrough. The system also includes a current supply operatively connected to the pressure transducer for supplying and varying the magnitude of the excitation current to the piezoresistive bridge. Further included is an output device connected to the pressure transducer for sensing a change in the electrical resistance of the piezoresistive bridge and outputting a signal from the piezoresistive bridge corresponding to the sensed air pressure. The current supply device varies the magnitude of the excitation current to the bridge in response to the output signal of the output device so as to change the sensitivity of the transducer relative to the airspeed of the aircraft.

Air data measurement system with circuit for linearizing pressure

A method for calibrating a pressure-sensing altitude sensor of an aircraft while the aircraft is in flight. The method includes the steps of obtaining a set of reference atmospheric pressures as a function of height above a base station by affixing a reference pressure sensor to a balloon. As the balloon is released into the atmosphere, the reference sensor continuously measures the atmospheric pressures and transmits the data back to the base station while a ground-based radar disposed adjacent the base station measures the height of the balloon. An aircraft flying in a vicinity of the base station can calibrate its pressure-sensing altitude sensors by measuring the atmospheric pressure outside the aircraft and its geometric height relative to the base station and then comparing the pressure measurements with corresponding reference pressure values at a geometric height that is substantially that same as the geometric height of the aircraft.

Method for calibrating aircraft altitude sensors

A time-varying control signal is developed by a current sensor connecting the imaging screen and a closely proximate screen grid of a cathode ray tube as an imaging electron beam is operatively swept across the screen to produce images thereon. The control signal is processed and then applied to at least one of the tube operating elements--such as the horizontal and vertical deflection coils, the focusing lens, the electron beam generator and, in a plural beam tube, the convergence assembly--which controls a characteristic affecting the quality of an image. Specific arrangements for using the time-varying control signal to compensate for geometric image distortions affecting horizontal linearity and to increase the imaging resolution of the tube are disclosed.

Methods and apparatus for improving cathode ray tube image quality

A fluid density measuring device or densitometer computes, electronically, the density of a fluid by measuring the resonant frequency of an excitation signal provided to a density transducer (11) immersed in the fluid. The frequency at which resonance occurs in the circuit (13, 15, 17, 21, 23, 25, 29, 31, 37, 41) will vary according to the density of the fluid, and this information is used by measuring electronics (31, 37, 41, 43), including a programmed microprocessor (43), to calculate the density of the fluid. The output of the microprocessor (43) may be a display of fluid density information or may be transmitted to a fuel gauge.

Densitometer with remotely disposed control electronics

An internal electrostatic field-generating, beam-controlling element in a cathode ray tube is formed by depositing an initially continous layer of resistive material on a substrate and applying a voltage differential across the coating to generate a field-generating current therethrough during operation of the tube. After completion of tube assembly and sealing of the tube envelope, the element is custom fine-tuned by projecting an externally-originating laser beam through the envelope wall to selectively remove portions or areas of the resistive material, thereby predeterminately distorting the electrostatic field and selectively changing the effect of the field on the imaging electron beam. This procedure readily enables both correction of perceived deficiencies in and intentional modifications to one or more characteristics of the electron beam.

Methods and apparatus for post-assembly custom fine-tuning of an

A system for providing an airtight/particle tight hermetically sealed clean room environment (20) from which air is passed through a filter (22) includes a panel supporting grid member (24, 24a) having a negative pressure return (32) integrally formed therein for preventing air leakage into the clean room environment (20) with the grid member (24) comprising a circumferential mounting frame having an aperture therein, and a filter panel (22) which is mounted in the frame (24, 24a) in hermetically sealing engagement therewith for closing the aperture. The mounted filter panel (22) and the integral grid member (24, 24a) comprises a negative pressure plenum cavity (32) with the grid member (24, 24a) per se comprising a plenum member which allows negative pressure to be carried around the mounted filter panel (22).

Integral grid structure for providing negative pressure plenum

A universal fuel quantity indicator apparatus (100,102) includes a digital fuel quantity indicator (100) having an internal microprocessor control unit (104) and a removably connectable digital calibration trim unit interface (102) which enables the fuel quantity indicator (100) to be reconfigured for different fuel tanks by varying selectable fuel tank parameters, such as constants associated with a fuel quantity determination based on calculations of capacitance of a tank capacitor array (110) and a compensator capacitor (112). The interface (102) includes up/down steering control buttons (140,142) which control selection and storage of the selected parameters, a mode selection jumper (154) which selects between a RUN mode and a CALIBRATE mode for the indicator (100), and an alternate static memory (108) which stores the configured parameters for loading to the indicator internal static memory (150) associated with the microprocessor (104) in the CALIBRATE mode to configure the indicator (100) for a specific fuel tank. The indicator display (130) is used in the CALIBRATE mode to display the parameters being selected to configure the indicator (100) for a specific fuel tank and in the RUN mode to display the measured fuel quantity information for the configured fuel tank. The control program for both the RUN and CALIBRATE modes is resident in the indicator internal static memory (150) and is accessed by the interface (102) in the CALIBRATE mode to accomplish the parameter selection needed to reconfigure the universal indicator (100) for a specific fuel tank, such as for an aircraft.

Universal fuel quantity indicator apparatus

A system for providing a hermetically sealed clean room environment (34) from which air enters through a filter (20, 20a) includes a magnetically permissive ceiling grid (22, 26, 54), a filter panel (20, 20a) removably mountable in the grid (22, 26, 54) and a magnetic sealing and mounting arrangement (38, 40, 42, 44, 52) associated with the filter panel (20, 20a) for effectuating an airtight/particle-tight hermetic seal. A permanent magnet (42, 52) extends circumferentially around the periphery of the filter panel (20, 20a) and is bonded thereto, with the magnet (42) being embedded in a gasket (38) in one instance and comprising a magnet blade (52) in another instance. In either instance, a magnetically flowable fluid is disposed between the magnet (42, 52) and the ceiling grid (22, 54) so that when the panel (20, 20a) is placed into the steel ceiling grid (22, 54), a high reluctance path is set up in the air space between the magnet (42, 52) and the steel grid (22, 54) and the magnetic lines of flux (50, 60)travel through the fluid (44) to the ceiling grid (22, 54) as a return path. The fluid (44) aligns itself with these magnetic lines of flux (50, 60) in an attempt to reduce the magnetic reluctance of the circuit and in so doing fills all the voids (45) between the filter panel and the grid mounting interface (38-22, 52-54). The resulting hermetic seal permits the plenum (24) above the dropped ceiling (26) to be positively pressurized by an air blower (28) to provide the clean room environment (34).

Clean room ceiling grid system

A pressure transducer cross-check system (10) in which a pair of low precision pressure transducers (12, 14) which detect parameters related to each other in content are alternately periodically calibrated during the operation of the system by cross-checking by a solenoid actuated valve (18) which alternately connects one of the pair of low precision pressure transducers (12, 14) to its associated pressure input (20, 22) while connecting a common high precision pressure transducer (16) to the other of the related pressure parameter inputs (20, 22) for selectively alternately providing one of the pair of parameter input signals as a high precision pressure responsive input signal to the system controller on alternate cycles of the low precision pressure transducer pair in accordance with the cycling of the valve (18). The high precision pressure transducer (16) output signal and the alternately selected low precision pressure transducer (12, 14) output signal are compared under identical sampling conditions, such as by conversion of the low precision pressure transducer voltage output into a frequency output via a voltage-to-frequency converter (32) where the high precision pressure transducer (16) output is a signal in which the frequency is proportional to pressure.

Pressure transducer cross-check system

A mach airspeed indicator capable of internally determining mach number and VMO from measured altitude and airspeed information directly. An internal microprocessor, capable of storing a plurality of selectable VMO curves and a table of mach number versus q.sub.c /P.sub.s, receives the measured altitude and airspeed information, determines VMO and mach number therefrom, and directly drives the VMO and mach number displays where q.sub.c represents the impact pressure and P.sub.s represents the static pressure. The measured altitude and airspeed signals are analog synchro signals. In order to drive the VMO display, the received analog altitude synchro signals are digitized in a synchro-to-digital converter comprising a single multiplying digital-to-analog converter for both sin .theta. and cos .theta. synchro functions, and fed to the microprocessor which verifies the appropriate VMO from the preselected VMO curve, and drives the VMO analog pointer via a stepper motor servo loop closed by the microprocessor. If the VMO is exceeded, the microprocessor provides an overspeed alarm control signal. In order to drive the mach number display, both the received measured analog altitude and airspeed synchro signals are received, digitized in the synchro-to-digital converter, and fed to the microprocessor. The microprocessor converts the digital airspeed signal into q.sub.c /P.sub.s signal which is used to determine mach number from the stored values. The microprocessor then drives the mach number counter display via a separate stepper motor servo loop closed by the common microprocessor.

Mach airspeed indicator

An improved fluid quantity indicator, such as for aviation fuel, of the type utilizing capacitive type sensing probes in which a capacitance change occurs proportional to the amount of fluid in a tank or container due to the dielectric constant of the fluid being different from that of air, in which the improvement comprises microprocessor control means for providing display and totalizing control in conjunction with automatic compensation for the zero fluid capacitance variation in a tank and automatic adjustment of the fluid full scale reading for variation in fluid tank capacitance. The microprocessor controls two independent digital servo loops, one of which is nulled when the microprocessor output is equivalent to the fluid quantity for providing a container configuration independent real time digital display of fluid quantity within a given container, and the other of which is nulled when an in-phase signal of equivalent magnitude and opposite sense to cancel out the real component leakage present across the sensing probes is provided. In addition, the microprocessor may be coupled to another microprocessor which functions to total the signals from a plurality of containers or tanks on board the aircraft to provide a total display of fluid on board.

Fluid quantity indicator

An improved fluid quantity indicator, such as for aviation fuel, of the type utilizing capacitive type sensing probes in which a capacitance change occurs proportional to the amount of fluid in a tank due to the dielectric constant of the fluid, such as aviation fuel, being different from that of air, in which the improvement comprises automatic compensation for the zero fluid capacitance variation in a tank and automatic adjustment of the fluid full scale reading for variation in fluid tank capacitance. Programmable digital to analog convertors are utilized to provide a universal apparatus full scale set compensation for containers for the fluid substantially independent of the container configuration for compensating for variation in full scale capacitance of a given container and to provide a universal apparatus zero set compensation for containers for the fluid substantially independent of the container configuration for compensating for variations in zero fluid capacitance of a given container. An up/down counting means together with a digital display is utilized for providing an indication of the fluid quantity, the reference probe signal and the sensing probe signal being preferably summed with the zero set biasing signal in a servo control loop with the counting means for providing the digital display of fluid quantity, the loop being nulled when the counting means output is equivalent to the fluid quantity to provide a container configuration independent real time digital display of fluid quantity within a given container or tank.

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Malvern, PA, United States of America

Geoffrey S Hedrick