Abstract: The output of the vertical accelerometer of a ships inertial navigation sem (SINS), in pulse form, is first counted and scaled to provide an output related directly to the total acceleration. The SINS computer provides the latitude, and north and east velocities of the ship, which are then converted into the theoretical gravity and the Coriolis error. These two factors are subtracted from the total scaled acceleration, and the resultant output is passed through a filter that corresponds to a particular weighting function (heavily weighted for the middle time) to remove the factor of ships heave acceleration. The final output is the free-air gravity anomaly in terms of real time.

Abstract: Apparatus and method for indicating and adjusting the angle between the horizontal tangent to the luff of a sail and the direction of the apparent wind.

Abstract: A display device particularly suited for providing the pilot of an aircraft with combined inflight attitude, heading, altitude, and horizontal situation information previously available only by using two or three devices providing separate displays. The preferred embodiment of this invention combines a commonly used and commercially available flight director-type device for providing a display in combination with a miniature aircraft supported for angular displacement from a vertical orientation to indicate heading error, or heading offset, and an extended course deviation indicator bar which projects into juxtaposition with the miniature aircraft for providing a true picture of the aircraft's horizontal situation relative to a selected VOR, ILS, or MLS course.

Abstract: An annular momentum control device (AMCD) 11 is operated in a strapped down position on a spacecraft. The signals from the position sensors 18 and 19 at the several AMCD magnetic bearing stations a, b, and c are applied to computers (FIGS. 4 and 5) which compute the angular rate about first and second axes in the plane of the AMCD rim 12 and compute the linear accelerations along the first and second axes and along a third axis perpendicular to the first and second axes.

Abstract: Six sensors are oriented to position their input axes on the surface of a cone. The cone angle is optimized to permit the use of sensors with identical range capacity despite the fact that the maximum input along each of the orthogonal axes differs.The optimization of cone angle minimizes the average total error amplification due to skewing and change of sensor maximum rate capability to provide data closely approximating that derived from a non skewed, orthogonal, sensor array. The sensors may be gyroscope or accelerometer which are packaged in assemblies of two identical sensors each.

Abstract: An improved system for determining the vertical direction relative to a moving base includes gyroscopic rate sensors for determining angular velocities of a device such as a weapon mounted on the base, relative to two orthogonal axes; a gyroscopic rate sensor for determining the roll angle velocity of the system and a calculating circuit for determining the roll and pitch angles needed to ascertain the vertical direction.

Abstract: An inertial navigation system utilizing a servo-controlled two-degree of freedom pendulum to obtain specific force components in the locally level coordinate system. The pendulum includes a leveling gyroscope and an azimuth gyroscope supported on a two-gimbal system. The specific force components in the locally level coordinate system are converted to components in the geographical coordinate system by means of a single Euler transformation. The standard navigation equations are solved to determine longitudinal and lateral velocities. Finally, vehicle position is determined by a further integration.

Abstract: A skin friction measuring device for measuring the resistance of an aerodynamic surface to an airstream, adapted to be mounted on an aircraft, within an opening defined therein, and characterized by a friction plate adapted to be disposed in a flush relationship with the external surface of the aircraft and be displaced in response to skin-friction drag, as an airstream is caused to flow over the surface thereof, and a potentiometer connected to the plate for providing an electrical output indicative of the magnitude of the drag.

Abstract: An indicator for indicating the optimum angular position of a sail which is adapted to be rotated in various positions relative to a wind, and wherein the position of the sail may be represented by a polar curve comprising a laminar zone, a drop-off zone, a transition zone and a checking zone. The indicator comprises display means for displaying the optimum angular position of the sail relative to the wind as well as evaluation means for determining the position of the sail which corresponds to value between the end of the laminar zone and the beginning of the checking zone as a function of the direction of the wind. Means for indicating the direction of the wind to the evaluation means and driving means for driving the display means to display the optimum sail position are also included.

Abstract: In an aircraft excessive rate of descent warning system that utilizes barometric descent rate compared with aircraft altitude above ground to generate a warning, nuisance warnings at airports having terrain that slopes generally downwardly towards the runway can be substantially reduced by modifying either the descent rate signal or the altitude above ground signal as a function of radio altitude rate thereby having the effect of increasing the descent rate required to trigger a warning when the aircraft is descending essentially parallel to the ground.

Abstract: A system for processing signals representative of airspeed error and inertial longitudinal acceleration in first and second channels, respectively, and providing cancellation of the turbulence-induced components of the respective signals. Shear detection and compensation circuits are provided in the system for reducing speed wandering in moderate and heavy turbulence. A circuit processing the signal .DELTA.V from the shear detector circuit is utilized to provide a gust bias signal input in the system.

Abstract: A set of two two-degrees-of-freedom rate gyroscopes and three linear accelerometers are assembled in a single module adapted to be mounted within a single aircraft electronics control unit, the unit comprising a strapped-down attitude and heading reference system. The module base provides a common keyed support for the two pre-calibrated gyros and three accelerometers in intimate mechanical and thermal association. The two gyros are oriented in the base and the base oriented in the aircraft so that the spin axis of one gyro is oriented parallel to the aircraft Z axis and that of the other gyro parallel to the aircraft Y axis while the gyro pickoffs and torquers (input and output axes, respectively) are rotated or skewed forty-five degrees about the spin axes to positions such that the input and output axes lie along the slant heights of a forty-five degree half angle right circular cone, the axis of which lies along the aircraft X axis.

Abstract: A multiple sensing device has sensors, mounted on a common rotatable shaft, for sensing magnetic field, electric field, gas flow, angular acceleration and linear acceleration. The latter three of the sensing devices employ piezo electric crystals as the sensors, while the magnetic field sensor employs a pair of rotating coils and the electric sensing device employs a pair of rotating electrodes.

Abstract: Improvements are disclosed in the pattern cone of the magnetic compass as described and claimed in copending application 769409, Harold T. Lyman, Jr., now U.S. Pat. No. 4,132,113. Simpler apparatus for trimming the sensor outputs of the sine and cosine of the angle between the craft's actual heading and the desired heading, are described and claimed.

Abstract: A system for processing signals representative of airspeed error and inertial longitudinal acceleration in first and second channels, respectively, and providing cancellation of the turbulence-induced components of the respective signals. Shear detection and compensation circuits are provided in the system for reducing speed wandering in moderate and heavy turbulence. A circuit processing the signal .DELTA.V from the shear detector circuit is utilized to provide a gust bias signal input in the system.

Abstract: A system for mounting a gimbal assembly to expand the range of angular mon of the gimbals and to permit direct connections to the gimbals. Two counter rotating members between the mounting base and the gimbal assembly change the spatial orientation of the plane on which the gimbal assembly is mounted without rotating the plane.

Abstract: An aircraft navigation display which allows a pilot to easily envision his position, heading, wind drift and direction of travel relative to one or more radio stations. The presentation allows the pilot to quickly and easily understand and interpret the various indicia because the display is similar to a map and shows the aircraft's plan position and allows the pilot to fly holding patterns as well as cross country patterns since the position of the aircraft is continuously observable.

Abstract: A redundant inertial reference system is provided with four gyroscope units, with the spin axes of the gyroscopes in the units being oriented, respectively, perpendicular to the four faces of an equilateral tetrahedron. Incidentally, a tetrahedron is a four sided body, and an equilateral tetrahedron is a four sided body having equilateral triangles for the four sides. With the four gyroscopes mounted perpendicular to the four sides of an equilateral tetrahedron, each of the gyroscopes is located symmetrically with respect to the others, with an angle of approximately 109.4 degrees between the spin axes of the gyroscopes. The system is particularly applicable to strapdown type inertial guidance systems and can provide three dimensional orientation information even if two of the gyros fail. The system uses four gyro units, a minimum number which can accomplish a foregoing function, with the four gyro units arranged substantially symmetrically with respect to one another.

Abstract: A head-up display system for an aircraft has a display unit which projects a display of symbology representing the aircraft flight parameters onto a separately mounted partially-transparent reflector positioned in front of the aircraft pilot, so that the pilot sees an image of the display against the external scene. The display unit has a sensor which receives an image of the display via the reflector. The sensor responds to displacement of this image from a reference established with respect to the display unit, caused by movement of the reflector relative to the display unit, and the display is correspondingly modified to compensate for such movement. The display unit may include a cathode-ray tube for providing the display which can be modified by adjustment of the deflection of the cathode-ray beam. In this case the reference established with respect to the display unit may be an instantaneous point image of the cathode-ray beam.

Abstract: A cabin display unit accepts information from a plurality of sources such as the petot static tube, a static air pressure source, a temperature source, cabin pressure source and the like and converts the data to corresponding electrical valves. The valves are multiplexed and converted to a digital value and applied to a micro-processor which calculates, from the data, the aircraft's true air speed, outside temperature, altitude, etc., and displays the calculated information on a cabin display unit.

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: Gyrocompass heading step-by-step repeater amplifier channels are provided with protection from damage by accidental short-circuits occurring in one or more compass step-by-step data repeaters or in the cables extending to such repeaters. Total shut-down of the affected channel or channels is effected by fast-acting thyristor pulse control circuits and the channels are automatically reset when the fault is removed. A cooperative latching short-circuit alarm is provided.

Abstract: A method and a device for facilitating the determination of wind direction and the position of a sailing vessel on a racing course. One and the same geographical bearing determined by the wind direction can be read on both tacks. The same graduation number may be watched on both tacks and this number refers to the wind direction.

Abstract: A portable navigational aid or device for use in a user-sailboat or similar vessel, where the user-sailboat and another approaching boat are traveling along courses which intersect, to indicate readily whether the user-sailboat should have the right-of-way considering the direction of the wind, the angles of approach of the two boats and the local governing rules regarding the right-of-way. The device includes a disc-shaped member which is held on board the user's boat so that an arrow on the disc-shaped member points in the direction of the wind. A marked pivoted indicator dial having a user-boat symbol is pivoted with the disc-shaped member and is oriented such that the user-boat symbol coincides with the direction of travel of the user's boat.

Abstract: A navigational device consisting of a magnetic compass containing a pattern having a specified relation of black-to-white density with respect to angle, rotating with the compass card, a light source for illumination of the pattern, pairs of sensors mounted in the compass and responsive to the light intensity reflected from or transmitted through the pattern, the output from one pair of sensors being proportional to the sine of the angle made by the sensor pair zero reference line with respect to Magnetic North, and the output of the other pair of sensors being proportional to the cosine of said angle, both outputs being suitable for operation of a remote indicating compass, and various modifications thereof for making the outputs of the sensor pairs proportional to the sine and cosine of the angle between a manually settable desired heading or angle and the angle of the said sensor pair zero reference line with respect to Magnetic North.

Abstract: This invention is a display system to assist a human operator in manually ntrolling a ship. This system may be operated in a conventional autopilot mode, where the system controls the ship completely; in a conventional hand electric mode, where the helsman manually controls the ship unaided by the system; and in a third mode, where the autopilot provides the helmsman all the information needed to steer the ship properly while the helmsman maintains direct manual control over the ship. In addition to the usual displays such as a rudder angle indicator and a compass repeater, the system provides a display which shows both the actual angle of the helm wheel and optimum angle for the helm wheel calculated by the autopilot.

Abstract: A rate of change of energy computer utilizing signal processing of the inner vectorial product of inertial acceleration and inertial velocity wherein such parameters are derived utilizing outputs from the aircraft INS (inertial navigation system) and from body mounted accelerometers.

Abstract: A system providing economical redundant strap-down inertial measurement capability in a space navigation system. By appropriate orientation of two-degree-of-freedom dry tuned rotor gyros, the system is able to achieve complete redundancy utilizing only three gyro units. With this orientation, both orthogonal and skewed rate data are available. Not only are the necessary computations materially simplified, but this system also provides the necessary conditions for failure detection and isolation.

Abstract: A guiding device for guiding the helmsman of a sailing vessel in steering a preset course relative to the apparent wind. The device employs a course selector a single setting of which presets the desired course to wind for both the port and starboard tacks. The device comprises a wind vane disposed at the top of the mast of the vessel and a guiding instrument at deck level. The guiding instrument signals the on-course condition by a state of balance and deviations from on-course by deviations from balance.

Abstract: The invention relates to an apparatus for compensating the output of a pendulous induction compass transmitter to eliminate heading errors during turns due to the vertical component of the Earth's magnetic field as well as those due to the horizontal component of the Earth's magnetic field perpendicular to the axis of tilt. By compensating for the effects of the Earth's vertical field component, instabilities and anomalies such as "Northerly Turning Error" are eliminated or minimized. Compensation for vertical field error is provided by generating a signal proportional to the product of the Earth's magnetic field M, the sine of the magnetic dip angle D at the given latitude and the sine of the aircraft tilt or bank angle .phi.. A compensating signal proportional to cos .phi. is generated and used to compensate for two cycle error.

Abstract: The invention relates to an apparatus for compensating a "strapdown" induction compass transmitter to eliminate heading errors during turns and during climbing and diving maneuvers which are due to the vertical component of the Earth's magnetic field and those due to the horizontal component of the Earth's field perpendicular to the axis of tilt. Instabilities and anomalies such as "Northerly Turning Error" which are due to the vertical component of the Earth's magnetic field are thus eliminated or minimized as is two cycle error which is due to the Earth's horizontal field during these same maneuvers. The vertical field roll compensating signal, to compensate for turn induced errors, is made proportional to the product of the Earth's magnetic field M, the sine of the dip angle D, and the sine of the bank or roll angle .phi.. The vertical field pitch compensating signal, to compensate for errors induced by climbing or diving maneuvers, is made proportional to the product of the sine of the angle .phi.

Abstract: The vehicle is operated over land which is described by a grid coordinate system having a north direction offset from geographic north. The vehicle has a pick-up to determine its heading speed along its longitudinal center line. The spin axis of a free gyro establishes a reference axis. A meridian gyro determines the angle, if any, between said reference axis and geographic north at the start of a mission. At the start of the mission a computer is supplied with information as to the starting point in said grid coordinate system, the angle between geographic north and grid north, and an estimated corrective factor (based on the type of terrain to be traversed) to be applied to the measured heading speed. The computer continuously determines, for display, the position of the vehicle in said grid system.

Abstract: The invention relates to an apparatus for compensating a "strapdown" induction compass transmitter to eliminate heading errors during turns, and during climbing and diving maneuvers which are due to the vertical component of the Earth's magnetic field as well as those due to the horizontal component of the Earth's magnetic field perpendicular to the axis of tilt. Instabilities and anomalies such as "Northerly Turning Error" which are due to the vertical field are thus eliminated or minimized as is two cycle error which is due to the Earth's horizontal field during these same maneuvers. The vertical field compensating signal during turns is proportional to the product of the Earth's magnetic field, M the sine of the dip angle D and the sine of the bank or roll angle .phi.. The vertical field pitch compensating signal while climbing or diving is proportional to the product of the sine of the pitch angle .theta., the Earth's magnetic field M and the sine of the magnetic dip angle D.

Abstract: The invention relates to an apparatus for compensating the output signals from a pendulous induction compass transmitter to eliminate heading errors during turns due to the vertical component of the Earth's magnetic field as well as those due to the horizontal component of the Earth's magnetic field perpendicular to the axis of tilt, i.e., two cycle error. By compensating for the effect of Earth's vertical field component, instabilities and anomalies such as "Northerly Turning Error" are eliminated or minimized. Compensation for vertical field error is achieved by generating a signal proportional to the product of the Earth's magnetic field M, the sine of the magnetic dip angle D at the given latitude and longitude and the sine of the aircraft bank or roll angle .phi.. This signal is combined (by summation) with the demodulated signal from the sin .psi. channel (i.e., the signal from the windings of the compass transmitter which senses the field along the athwartships axis) to cancel vertical error.

Abstract: A flight control system utilizing a limited authority stability augmentation system having a long term attitude and/or path control input to enhance the automatic flight capability of the stability augmentation system. A position sensor coupled with the limited authority stability augmentation actuator provides an indication to the human pilot via a suitable indicator when the actuator is near or at the limit of its authority thereby permitting the human pilot to effect manual trim, thus recentering the actuator.

Abstract: A navigation aid for sailing vessels which provides a continuous indication of the actual progress towards a selected position or goal, such as a course mark in a sailboat or yacht race, is described. The actual progress is indicated in terms of speed made good and/or distance made good so as to enable immediate evaluation of the effect of course changes and variations in vessel performance. The speed of the sailing vessel through the water is detected and an output signal proportional thereto is obtained. A sensor which is responsive to deviations from the direct course to the goal and which may be positioned in azimuth in accordance with that course is also provided. This sensor may be a Hall effect generator which is responsive to the earth's magnetic field as well as to the output signal from the speed detector and provides an output which is proportional to the product of the speed and the cosine of the angle between the course being sailed and the course to the goal.

Abstract: This invention provides an improved method and apparatus for celestial navigation. A reference spherical triangle is established from the coordinates of the ground position of an observed selected celestial body and an assumed position for the observer. A second right spherical triangle is then derived from a functional relationship between the first triangle and the observed height of the celestial body. The location of the end of the hypotenuse of the second triangle opposite the ground position defines a point of position on a line of position for the observer. The compass bearing for the line of position is functionally derived from conventional relationships and the line of position may be plotted through the point of position. Plotting means are provided to maintain the spaced relationship between lines of longitude and lines of latitude as a function of latitude for a mercator map projection and to directly plot the point of position on the plotting means.

Abstract: An automatic piloting system for the automatic steering of a marine or other vessel along an intended course in which a digital signal representing an intended course is processed to provide rudder commands for steering the desired course.

Abstract: An underwater navigation device wherein a flux gate compass provides head difference signals, a doppler navigation sonar provides drift angle signals, which signals are combined by a summer to provide steering correction signals that are displayed by a steering null meter.

Abstract: In a gyro horizon type of equipment, roll corrections are fed to the aircraft symbol which is a normally fixed display element and pitch correction is introduced on a movable display element or drum with modification of the position of the display elements of the instrument gyro as a function of an interconnection of the instrument gyro with a gyromaster reference through comparators connected to each of the roll and pitch systems.

Abstract: In order to provide a more accurate representation of aircraft pitch attitude for use in aircraft head up display devices, a circuit for generating a computed pitch signal responds to a longitudinal accelerometer and a vertical gyroscope within the aircraft wherein the computed pitch signal is generated by adding to the gyro pitch signal a correction factor computed by subtracting the value of the computed pitch signal from an inertial pitch signal derived from the longitudinal accelerometer. In order to compensate for the effects of aircraft acceleration on the longitudinal accelerometer signal, a computed acceleration signal derived from the difference between the longitudinal accelerometer signal and the gyro pitch signal is subtracted from the longitudinal accelerometer to generate the inertial pitch signal.

Abstract: An aircraft instrument comprising equipment for providing a first signal which is a function of airspeed and suitable for use in controlling an aircraft by variation of the airspeed to a predetermined value, an apparatus for providing a second signal which is a function of lift and suitable for use in controlling the aircraft by variation of the airspeed to adjust the lift to a predetermined value, and a selecting apparatus arranged to apply the second signal to a signal utilization mechanism for controlling the aircraft in accordance with said second signal except when said second signal falls below a predetermined datum level, which represents a safe margin above stall, whereupon the first signal is applied to the signal utilization mechanism, the selecting apparatus being arranged to provide a transition between control by the first signal and control by the second signal which is shorter than a transition between control by the second signal and control by the first signal.

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: An assembly of single-component motion sensors consists of four equinumerous groups of sensors. All the sensors in any one group have their measurement axes parallel and the directions of the measurement axes of the four groups are parallel to the diagonals of a rectangular parallelepiped. The edges of the imaginary parallelepiped are parallel to the coordinate axes relative to which it is desired to measure the components of motion. With two sensors per group the assembly can still give results after any two sensors have failed. It is shown how two non-simultaneous failures, and, in some cases, two simultaneous failures, can be located.

Abstract: A navigational system for automatically positioning a platform relative to the earth's geopotential surface. A system is provided which includes an accurate self-contained attitude reference to the true vertical. The system includes an inertial platform which is rotatable relative to a level platform, each of the platforms being connected to a two axis gimbal. One of the platforms is also connected to a three axis gimbal which may be connected to the vehicle which it is desired to stabilize. Means are provided for sensing rotation of one platform relative to the other. An inertial platform position control computer is provided for generating first corrected signals to the three axis gimbal for automatically referencing the inertial platform to a datum reference spheroid. Additional computer means are provided for generating second corrected signals to the two axis gimbal to align the level platform with the true vertical to the geopotential surface of the earth.

Abstract: The invention provides a peripheral vision horizon device for use in projecting a light bar on the interior of an aircraft cockpit or the like to indicate pitch and roll, the light bar being located with reference to a datum in the cockpit. The device includes a housing having a first part attachable to the cockpit and a second part rotatably coupled to the first part for movement about a first axis which on assembly in the aircraft extends transversely of the cockpit. A lens carrier is rotatably coupled to the second part for rotation about a second axis which is at right angles to the first axis. A light source is contained in the housing and an optical system is coupled to the housing for directing light from the light source towards the lens carrier along the second axis. A lens of two-fold symmetry is mounted in the lens carrier transversely of the second axis for receiving said light and projecting a beam of light which strikes the interior of the cockpit to create the light bar.

Abstract: The output of a transducer providing a signal representing the instantaneous airspeed of an aircraft is differentiated and fed to a summing device. Also fed to the summing device are a signal representing the horizontal acceleration of the aircraft which is subtracted from the instantaneous airspeed signal, and a signal in accordance with the downdraft drift angle of the aircraft which is added to the instantaneous airspeed signal. The output of the summing device represents the magnitude of the wind shear condition (rate of change of wind velocity) as modified by a downdraft drift angle signal. This output signal is fed to appropriate indicator apparatus which may comprise an appropriate display, a peak magnitude storage device, a warning device including a dangerous wind condition and/or a telemetering device providing a reading to a ground station for use in advising other aircraft.

Abstract: This invention relates to low range fluid speed sensors for the measurement of fluid currents in any direction, down to near zero velocity for dense fluids. Two signals with a 90.degree. space phase relationship are used which permits the instantaneous resolution of the fluid speed vector into its two orthogonal components.

Abstract: Control of an active three-axis multiple-wheel attitude control system is provided with a bias momentum to achieve stiffness about the pitch axis. With this stiffness, the system overcomes the inherent inability of a zero momentum system employing the sun as its yaw reference to be provided with this yaw reference during the periods encompassing satellite high noon and midnight (i.e., approximate coalignment of the sun line and the local vertical). The satellite attitude is normally maintained by angular momentum exchange developed by three or more reaction wheels positioned on the satellite. The control mechanism is arranged to provide net angular momentum in the pitch axis wheels to achieve the momentum bias or stiffness along the pitch axis, whereas the time average of the angular momentum about the roll and yaw axes is substantially zero.

Abstract: A sensing vane is placed near the leading edge of the keel of a sailboat where the water flow splits. The vane is deflected away from a "center" position (i.e., a position aligned with the keel) by the water stream as a function of the water flow angle (the angle between the heading of the boat and its path through the water). The rotational movement of the vane is sensed by a synchro transmitter which drives a synchro follower positioned at a location near the helm of the boat where it drives an indicator dial. The indicator dial is appropriately calibrated for each boat to provide a direct reading of flow angle, the ratio between the side force of the water on the keel (S.sub.k) and the water drag force (D.sub.k) being a function of this angle. The dial is marked to provide an indication when optimum flow angle (i.e., that for maximum S.sub.k /D.sub.k) is being achieved. In addition, an alerting signal may be provided when such optimum condition exists.