Abstract: A flight planning system for obtaining flight plans and/or weather information is provided with a portable computer having a display unit, keyboard, memory, built in modem and a built in disk drive that can be connected via telephone lines to a ground based data center. The basic flight planning data and/or weather request data is input in response to menu driven prompts and reviewed on the display by the pilot. The portable computer is then connected to the data center which generates a series of optimized flight plans and provides desired weather information. After the desired flight plan and/or weather information has been selected by the pilot, it is loaded onto a floppy disk in the disk drive. The aircraft is provided with a data transfer unit which accepts the floppy disk and downloads the flight plan and requested weather information into the onboard computerized navigation system.

Abstract: A system for warning the pilot of an aircraft flying at low level, particularly over rising terrain, of an excessive closure condition that could result in controlled flight into terrain if left uncorrected. Specifically a warning system is disclosed that monitors the terrain closure rate of an aircraft under certain conditions. These conditions relate to the weapons not being armed, the aircraft flying between 100 and 1800 feet and the air speed exceeding 200 knots. When these conditions are met a warning is provided to the pilot that the terrain closure rate exceeds a predetermined safe limit for the radio altitude at which the aircraft is flying.

Abstract: Disclosed herein is a video projection system (18) suitable for mounting in the ceiling of the passenger compartment of an aircraft for displaying video images for passengers embarked on the aircraft. The video projection system includes a video projector (19) positioned to project video images through an opening in the ceiling, a light deflector (21) positioned to deflect the light from the video projector along a different path, and a projection screen (23) positioned to receive and display the deflected video images. Various embodiments are disclosed wherein the light deflector and/or projection screen are mounted for movement from stowed to deployed positions, the deflector and/or projection screen being movable in a controlled manner that does not pose a significant safety hazard.

Abstract: The invention provides independent guidance and monitoring to be integrated into an MLS landing system and also provides a scaled-down MLS landing guidance system useable at small airports. In both cases an added fixed beam precision guidance system is integrated into the MLS time sequence format. The fixed beam guidance system is based upon the concept of using paired fixed overlapping beams, sequentially radiated by different fixed antennas. One pair is oriented to left and right of the centerline of the runway, and the other pair is oriented above and below the desired glideslope. The first set of paired beams overlap at the centerline of the runway in such a manner that an aircraft approaching exactly on centerline will intercept equal signal intensities to indicate an on-course approach.

Abstract: Prior detection circuits for measuring capacitance differences have commonly included error source, such as P-N junctions, in the DC signal path. The present invention provides an improved detection circuit for measuring the capacitance difference between first (C.sub.1) and second (C.sub.2) capacitive elements. The detection circuit comprises a first capacitor (C.sub.3) serially connected to the first capacitive element at a first common node (36) to form a first series circuit, and a second capacitor (C.sub.4) serially connected to the second capacitive element at a second common node (38) to form a second series circuit. The detection circuit also includes switch a circuit (32) connected between the common nodes and a reference potential, a driver (30) for applying a drive signal across each series circuit, a line for activating the switch circuit (48) and a difference detector (34) for measuring the voltage difference between the common nodes.

Abstract: VLF communication signals encoded in MSK format contain phase ambiguities that must be resolved in order to use such signals in navigation systems. The ambiguities are resolved by the present frequency multiplying device that in one embodiment operates to double the frequency of an input signal and mix the doubled input signal with a mixing signal to produce an output signal having first and second states. The device includes a transition detector (42) for generating a trigger signal in response to each low-to-high or high-to-low transition of the input signal that occurs when the output signal is in its second state, and a bistable circuit (44) for generating the output signal in response to the trigger signal and to a mixing signal. The bistable circuit responds to the trigger signal to cause the output signal to be in its first state, and responds to a periodic characteristic of the mixing signal to cause the output signal to be in its second state.

Abstract: The elimination of activity dips in the output of vibrating beam accelerometers has often required an adjustment of parameters in conflict with other design criteria. This problem is overcome by the present accelerometer that comprises a pendulum (48) and a force transducer. The pendulum has first (49) and second (52) ends and a first axis (P) extending between the first and second ends. The pendulum is hingedly connected at its first end to a support (50) along a second axis (F) perpendicular to the first axis. The force transducer comprises an oscillator and a dual beam force sensing element (53) connected between the second end of the pendulum and the support. The point of connection of the force sensing element to the pendulum lies along the first axis. The force transducer is adapted for vibration over a predetermined operating range (44) of beam vibration frequencies.

Abstract: A digital accelerometer comprising a linear analog accelerometer and a digitizer. The analog accelerometer includes a housing and conductor means extending outside the housing, and is adapted to produce on the conductor means an analog signal representing linear acceleration along one axis. A casing is positioned against the housing so as to form a substantially enclosed space between the housing and the casing. The digitizer is located within such enclosed space and receives the analog signal and produces a corresponding digital signal. An interface circuit is positioned within the enclosed space for receiving the analog signal and producing a second analog signal that is input to the digitizer. The digital signal produced by the digitizer may be conveyed to a location outside the enclosed space and housing by a flexible strip of insulating material having a plurality of conductive strips embedded therein.

Abstract: In order to facilitate the installation of transducers such as accelerometers in a larger system, each transducer is provided with a memory circuit which is physically attached to the transducer and contains data reflecting the operating characteristics of that particular transducer. The data stored in the memory can be in the form of coefficients for polynomial equations that describe the operation of the transducer as the function of a variable such as temperature. Provision is made for transmitting this data along with the signal output from the transducer to the larger system.

Abstract: In order to provide timely aircraft performance data from an aircraft flight data recorder in a useful format, a flight data display system is provided: with a data storage unit; an interface circuit for reformatting flight data from the flight data recorder; a central processor for converting selected portions of the reformatted data into engineering units and storing the converted data into the storage unit; and a video display unit including a keyboard for selecting the desired portions of the reformatted flight data for display on the video display unit. The video display unit provides for the multicolor display of flight data in either graphical form or in a cockpit instrument form on a cathode ray tube.

Abstract: An aircraft flight data recorder housing comprising a titanium alloy having a nominal composition of 15 weight percent vanadium, 3 weight percent chromium, 3 weight percent tin, and 3 weight percent aluminum with the balance being titanium and, within limitations, certain trace elements. The alloy is simultaneously hot formed and solution heat treated at temperatures on the order of 1400.degree. F. to 1500.degree. F. to fabricate the recorder housing.

Abstract: Thermally induced stress between a quartz proof mass and the metal stators which constrain it are relieved by a suspension system employing pliant members. Contact points between the proof mass and the stators are formed by raised pads on the proof mass which contact beams formed in the stators. Each beam has an axis of pliancy, which axis extends through a fixed, stable contact point between the proof mass and the stators, the beam being otherwise rigid to applied forces along axes orthogonal to the axis of pliancy. The resulting suspension system exhibits compliance to thermally induced loads while providing rigidity in response to seismic loads.In alternative embodiments of the suspension system, the pliant beams are positioned to provide temperature compensation for compounds of the transducer.

Abstract: Inertial measurement of the angular rotation and translational motion of a structure can be provided by a pair of vibrating accelerometers aligned in a side-by-side arrangement with their force sensing axes in the same direction and vibrated to and away from each other along an axis normal to their force sensing axes.

Abstract: Apparatus for measuring inertial specific force and angular rate of moving body by means of a plurality of accelerometers mounted on mutually perpendicular axes, each accelerometer being mounted for vibratory movement along its respective axis. The apparatus further includes a drive for vibrating each accelerometer to produce output signals and a signal processor for deriving from the accelerometer output signals the specific force and angular rate for the respective axes. Enhanced performance is achieved by utilizing pairs of accelerometers vibrating along each axis combined with a preseparation circuit that separates the components of the accelerometer output signal having specific force information from components having angular rate information.

Abstract: A helicopter weight measuring system for detecting the loaded weight of a helicopter operating under partial or full hover conditions while the wheels of the helicopter are contacting the ground includes means for sensing loading on the landing gear of the helicopter and means for determining the lift produced by a rotating wing of the helicopter. The sensed loading on the landing gear is added to the calculated lift to produce an indication of total helicopter loading.

Abstract: In order to reduce nuisance warnings and to increase the effectiveness of real warnings produced by a ground proximity warning system, the criteria for generating a warning is varied for certain airport areas to take into account the terrain in those areas. Along with position data, certain flight parameters such as heading, altitude, glideslope and localizer deviation are checked by the system in order to ensure that the aircraft is located in the desired warning modification area. In addition, the ground proximity warning system includes a mechanism for ensuring that the corrected barometric altitude of the aircraft is within acceptable limits.

Abstract: A transducer assembly includes first and second stators which are axially aligned with, and bear upon opposite sides of a proof mass. The stators and proof mass are clamped together by means of a sleeve having a side portion with spaced apart upper and lower flanges extending therefrom. The flanges bear against receiving surfaces on the stators with the sleeve under elastic deformation such that a compression force tending to reduce the spacing between the flanges is transmitted to the stators and proof mass as a controlled compressive axial preload.

Abstract: A transducer assembly includes first and second stators which are axially aligned with, and bear upon opposite sides of a proof mass. The stators and proof mass are clamped together by means of a sleeve having a side portion with upper and lower flanges projecting therefrom. An inner sleeve element, formed from a material having a different coefficient of thermal expansion than the side portion, is disposed between the flanges. The temperature of the sleeve is controlled such that the inner sleeve element produces a tensile stress on said flanges, increasing the spacing therebetween. The flanges are then joined to the stators. Thereafter, the temperature of the sleeve is controlled such that the tensile stress produced by the inner sleeve element on the flanges is reduced producing a compression force tending to reduce the flange spacing. This compression force is transmitted to the stators and proof mass as a controlled compressive axial preload.

Abstract: A warning system for providing an aural warning to the pilot of a rotary wing aircraft monitors the altitude above ground and barometric descent rate of the aircraft and generates the warning if the descent rate of the aircraft is excessive for the altitude at which the aircraft is flying. The system provides two distinct warnings, one being an early warning advising the pilot of a hazardous condition, and the other being a warning alerting the pilot of imminent danger. The system also includes tactical and non-tactical modes of operation, wherein the warning criteria are adjusted to meet tactical and non-tactical flight conditions.

Abstract: A dynamic low tire pressure detection system for detecting the presence of a low tire mounted on a structural member of an aircraft, such as a bogie beam or nose axle, includes a pair of inclinometers mounted on the structural member and adapted to sense the bend therein. The signals from the inclinometers are combined to generate signals representing the weight carried by the structural member. When the aircraft is moving, the weight signal is analyzed to determine whether particular frequency components are present therein. The amplitude of these frequency components are modified by a gain factor dependent upon a reference amplitude and are added to develop a tire pressure signal. The tire pressure signal is compared against a trip setting to determine whether the tire pressure is within acceptable limits. If the tire pressure is outside of the range of acceptable tire pressures, a signal is generated to warn of a potentially dangerous condition to the aircraft operating personnel.