Abstract: A transducer having compensation for a deflection due to an applied stress. The transducer a support ring (32) having a proof mass (34) cantilevered on a pair of flexures (38) between the magnets (26, 28) of a stator in which the transducer is mounted. Deflection of the support ring due to an imbalanced applied force is compensated by either moving the pads (30) used to mount the support ring, moving the centroid of capacitance (128) of the proof mass, or by modifying the support ring to provide a pair of moment arms (156), each approach insuring that an axis of deflection (102, 130) of the support ring is coaligned with the centroid of capacitance, thereby minimizing a bias error in the transducer output.

Abstract: A portable siting system particularly useful for siting a portable localizer for a collocated approach guidance system for aircraft utilizes a laser range finder in conjunction with a shaft encoder to determine the distance between the localizer and two arbitrary points along a runway center line as well as the azimuth offset between the two points. A microprocessor is used to compute the number of degrees the antenna of the localizer must be rotated so that its beam intersects the extended runway center line at a predetermined point based on trigonometric computations performed on the two measured distances and the measured angle.

Abstract: An integrated landing system interleaves signals encoded in a first format such as the microwave landing system that (MLS) format with signals encoded in a second format such as the precision tactical approach guidance (PTAG) format to permit approach guidance information to be transmitted to aircraft having either MLS receivers or PTAG receivers.

Abstract: A push-pull accelerometer in which both force transducers lie in a common plane. Thus, when implemented in silicon micromachined device, both transducers can be fabricated from a single crystal layer, thereby producing transducers with closely matched common mode responses.

Abstract: A system for warning the pilot of a tactical aircraft in a tactical maneuver such as a dive of the point at which recovery must be immediately initiated to prevent the aircraft from descending below a minimum desired altitude monitors the altitude, descent rate and pitch angle of the aircraft, and issues a voice warning when recovery must be initiated. The system also provides warnings of dangerous flight conditions during non-tactical or common route segments of a flight such as the take-off, landing and cruise segments of a flight. Circuitry responsive to the arming of the weapons of the aircraft enables the tactical warning portion of the system and disables certain functions of the non-tactical portion of the system that may cause false warnings to be generated during tactical maneuvers.

Abstract: A guidance system for landing an aircraft is described which uses a source of signals identifiable with the aircraft and a ground station which is linked to the aircraft. Specifically, the ground station includes a receiver which is connected to one or more pairs of antennas having a fixed, overlapping, directional sensitive pattern symmetically located relative to the center of the landing path, a receiver and a processor for measuring the relative sensitivity of the signals received at the antennas and for using the relative signal intensity to determine the location of the aircraft relative to the center of the landing path.

Abstract: A proximity to terrain warning system for aircraft utilizes a first set of warning criteria to generate a warning in the event of insufficient terrain clearance after take off. A different set of criteria are employed to generate warnings when the aircraft in in a cruise or approach phase of flight or on a tactical mission. Mode switching is provided to select the appropriate criteria and to select an excessive descent after take-off set of warning criteria in addition to the first set of criteria when appropriate.

Abstract: A warning system for rotary wing aircraft that monitors the altitude above ground of the aircraft and issues a warning when there is insufficient terrain clearance. The warning criteria are optimized for rotary wing aircraft and are altered as a function of landing gear position and airspeed. Two distinct warnings are given. One indicates insufficient terrain clearance and the other warns the pilot if he attempts to land with the landing gear up. Logic circuitry is provided to modify the criteria necessary to generate a warning, and to inhibit certain warnings, as required by the mode of operation of the aircraft.

Abstract: A snap action thermal actuator utilizes a pair of mechanically coupled bimetallic members having different temperature characteristics to provide a fast and positive snap action thermal actuator even when a low temperature differential is required. The actuator is particularly useful for controlling the operation of electrical contacts in a thermal switch.

Abstract: A compact torque motor providing bi-directional, limited angle reactionless torque to opposed structures. A motor (10, 150) includes an X-shaped core (12), and first and second pole pieces (14 and 16), which are disposed at opposite sides of the core. Two opposed legs on the X-shaped core (12) comprise a first core section (18), which is transverse to a similar second core section (20). A first electromagnetic coil (22) is formed on the first core section and a second electromagnetic coil (24) on the second core section. When the first and second electromagnetic coils are alternately energized, tabs (38, 40, 44, and 46) disposed approximate the ends of the first and second pole pieces are attracted to the resulting magnetic poles (26 and 28, 30 and 32), causing the pole pieces to counter-rotate back and forth about a central axis (48). Magnetic flux developed by the first and second electromagnetic coils is conveyed through the tabs and the first and second pole pieces between the opposite magnetic poles.

Abstract: A wind shear warning system monitors the flight path of an aircraft and wind shear in the vicinity of the aircraft and generates an advisory or cautionary message for the pilot based both on the magnitude of the wind shear and the flight path of the aircraft. When the aircraft is flying a normal flight path, a wind shear warning is generated only when relatively high negative wind shears are present. If the flight path of the aircraft is not normal, for example, if the aircraft is below the glide slope or descending too rapidly, a cautionary alert is given at lower values of wind shear. The alert or warning is selected to provide the pilot with information defining the nature of the hazard or potential hazard being encountered.

Abstract: A crash survivable enclosure for flight data recorders used in aircraft and other vehicles operating over land and water includes a strong, light-weight metal shell for enclosing and protecting an information storage device having power, signal, and address lines connected thereto. The memory device is supported inside the shell in a wax filler of the type having a high melting temperature and a high heat of fusion to act as a heat sink for absorbing a large quantity of heat to minimize possible damage to the memory device because of excessive heat, flames and/or high temperature. A strong lightweight metal shell is provided to enclose and protect the inner shell and contents against substantial, external mechanical forces commonly occurring in a crash and flames, heat and fire resulting therefrom.

Abstract: An improved accelerometer of the type that includes a proof mass suspended from a support by one or more flexures, such that the proof mass can pivot with respect to the support about a hinge axis. The proof mass includes a paddle attached to the flexures, the paddle having first and second paddle surfaces. The coil is mounted on the first paddle surface, and the accelerometer includes a stator for mounting the support and for forming a magnetic circuit with the coil. The improvement comprises positioning the flexures such that a plane containing the hinge axis and the center of mass of the proof mass is parallel to one of the paddle surfaces, and closer to one paddle surface than to the other paddle surface. In a preferred arrangement, the plane containing the hinge axis and the center of mass is approximately coplanar with one of the paddle surfaces and with the flexures.

Abstract: A system that warns the pilot of an aircraft performing low level maneuvers of a dangerous flight profile monitors the altitude of the aircraft above ground, and provides a first specific warning to the pilot if the altitude of the aircraft drops below a predetermined minimum altitude above ground. The system further monitors the roll angle and descent rate of the aircraft to provide a second specific warning if the descent rate of the aircraft exceeds a predetermined rate determined by the roll angle of the aircraft if the aircraft is below a second predetermined altitude above ground.

Abstract: Apparatus and method for establishing a level plane and with respect to the level plane, vertically aligning an acceleration sensitive axis of a gravity measurement device (10). The gravity measurement device includes an accelerometer (68), which is rotatably mounted on a gimbal shaft (62) within a gimbal frame (54). The gimbal frame is also rotatable about a longitudinal axis that is preferably oriented at a right angle to the longitudinal axis of the gimbal shaft. A stepping motor (20) is connected through an antibacklash gear (30), an idler gear (32) and an antibacklash gear (48) to a drive shaft (50). Rotation of this drive shaft causes the accelerometer to rotate about the gimbal shaft. In a similar fashion, a stepping motor (22) is drivingly connected to a drive shaft (56), used to rotate the gimbal frame.

Abstract: A transducer having compensation for a deflection due to an applied stress. The transducer includes a support ring (32) having a proof mass (34) cantilevered on a pair of flexures (38) between the magnets (26, 28) of a stator in which the transducer is mounted. Deflection of the support ring due to an imbalanced applied force is compensated by either moving the pads (30) used to mount the support ring, moving the centroid of capacitance (42) of the proof mass, or by modifying the support ring to provide a pair of moment arms (152), each approach insuring that an axis of deflection (102, 130) of the support ring is coaligned with the centroid of capacitance, thereby minimizing a bias error in the transducer output.

Abstract: A method and apparatus for detecting amplitude compression in a guidance system utilizes a transmitting system that transmits two pulses having a predetermined amplitude differential therebetween on each of a plurality of directional beams. The amplitudes of the pulses received from an individual one of the beams are compared, and if the amplitude differential between the received pulses is different than the predetermined amplitude differential of the transmitted pulses, a signal indicative of receiver compression is generated.

Abstract: A technique is described for tailoring the configuration of electrodes on a piezoelectric beam such that the tendency of the beam to vibrate in a predetermined flexure mode is enhanced. The mode has a predetermined longitudinal strain versus longitudinal position profile. At least two electrodes are mounted on the beam, and the configuration of at least one electrode varies as a function of longitudinal position, such that when a voltage difference is applied between the electrodes, the longitudinal force produced by the electrodes, as a function of longitudinal position, approximates the longitudinal strain versus longitudinal position profile. The configuration may be varied by varying the width of the electrode or the position of the electrode on the underlying beam surface.

Abstract: Flexures, and a method for creating flexures, for use in micromechanical sensors such as accelerometers in which a first member is pivotally connected to a second member. In one aspect, the invention provides first and second flexures connecting the first and second members, the flexures permitting rotation about a common hinge axis. The flexures have a crossed configuration that provides increased stability. Each flexure is made by etching grooves in the opposite wafer surface, the positions and depths of the grooves being selected so as to form a flexure therebetween.

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.