Abstract: A surfboard fin assembly for the flush incorporation into a surfboard body that allows for adjusting the depth the fin extends below the surfboard. It has a biasing means that maintains the fin in the down position yet allows upward movement upon the application of upward force such as when the fin is struck from below. The fin is perpendicularly affixed to a hinge body that is pivotally housed in an open ended fin box that is integrated into the volume of the surfboard body. A means for tensioning is releasably attached at a distal end to the hinge body and at a proximal end to the surfer's ankle. The height of the fin is adjustable through the means for tensioning and sets the performance of the surfboard to the surfer's desired level of directional control depending on their type of surfing. The fin or fin and hinge body are interchangeable with other design of fins.

Abstract: A surfboard fin assembly for the flush incorporation into a surfboard body that allows for adjusting the depth the fin extends below the surfboard. It has a biasing means that maintains the fin in the down position yet allows upward movement upon the application of upward force such as when the fin is struck from below. The fin is perpendicularly affixed to a hinge body that is pivotally housed in an open ended fin box that is integrated into the volume of the surfboard body. A means for tensioning is releasably attached at a distal end to the hinge body and at a proximal end to the surfer's ankle. The height of the fin is adjustable through the means for tensioning and sets the performance of the surfboard to the surfer's desired level of directional control depending on their type of surfing. The fin or fin and hinge body are interchangeable with other design of fins.

Abstract: A fishing lure device that, upon retrieval, will ascend in an upwardly direction toward the surface of the water. The device consists of a horizontal vane that can ascend with enough force as to penetrate the water's surface and become airborne, thereby simulating a foraging animal. The device may be augmented with some artificial or live bait that may increase the likelihood of attracting a fish.

Abstract: A circuit is provided for detecting an open condition in a thermocouple or thermocouple leads connected to a preamplifier even though the thermocouple is grounded or connected to ground through some resistance. A high frequency AC test signal is applied to both leads of the thermocouple and one of the leads is connected to a low pass filter. When the thermocouple circuit is closed, the AC signal on both leads will be substantially equal. If, however, either of the leads or the thermocouple itself is open, the AC signal will be different due to the low pass filter connected to one of the leads. That filter attenutes the signal on the associated lead as well as causing a phase shift of the two AC signals. A differential amplifier connected to the thermocouple leads detects the amplitude attenuation or the phase shift to provide an output whenever the thermocouple circuit is opened.

Abstract: A closed loop fuel control system is described for an internal combustion engine having two cylinder banks and an air/fuel mixture supply means for supplying a combustible mixture to each of the cylinder banks with the air/fuel ratio of the mixture supplied to each of the cylinder banks having relative values determined by the characteristics of the engine and the mixture supply means. Two exhaust gas sensors are provided, each being located at the exhaust discharge point of a respective one of the cylinder banks and sensing the oxidizing/reducing conditions of the exhaust gases from the respective cylinder bank. A controller adjusts the air/fuel mixture supply means to obtain a specified air/fuel ratio in response to combinations of exhaust gas oxidizing/reducing conditions as sensed by the exhaust gas sensors.

Abstract: An engine spark timing system includes pulse generating apparatus effective to generate conventional spark timing pulses, apparatus, including a first capacitor, effective to vary the voltage across the first capacitor in one direction at a first rate toward a reference voltage and generate a retarded spark timing pulse when the first voltage is reached, apparatus initiated at the time the retarded spark timing pulse is generated to vary the voltage across the capacitor in the opposite direction at a second rate until the next conventional spark timing pulse and apparatus responsive to engine start and one or more other engine operating conditions to substitute selected retarded spark timing pulses for the corresponding conventional spark timing pulses in the firing of the engine spark plugs.

Abstract: A vibration sensor mounted on an internal combustion engine characterized by knock-induced vibrations at a characteristic frequency and by other vibrations is tuned to resonate at substantially the characteristic frequency. A bandpass filter tuned to the characteristic frequency is connected to the vibration sensor output; and the output of the filter is provided to one input of a comparator and to average detector circuitry for generating a unidirectional noise reference signal representing noise at the characteristic frequency, which signal is provided to the other input of the comparator. The knock signal, obtained from the output of the comparator and comprising pulses corresponding to knock-induced peaks of amplitude greater than the unidirectional noise reference signal, is fed back through a low-pass filter to the average detector circuitry in sense to oppose increases in the unidirectional noise reference signal during said knock-induced peaks.

Abstract: In a spark timing system for a spark ignited internal combustion engine, means are provided for generating a series of alternating coil-on and coil-off signals in accordance with crankshaft rotation and one or more engine operating conditions, means are provided for normally passing each coil-on signal immediately to the spark coil to turn on current therethrough and means are provided for passing each coil-off signal to the spark coil to turn off current therethrough with a retard determined in accordance with an additional engine operating condition to generate a spark pulse retarded with respect to the normal spark timing. To ensure a minimum burn time for the spark plugs, means are provided to hold the spark coil in the off condition for a predetermined minimum burn time following each retarded coil-off signal, regardless of the possible appearance of a coil-on signal before the end of this minimum burn time.

Abstract: A gas coupled or free turbine type gas turbine engine of the type having two or more independently rotatable turbines has a set of hydraulic (oil cooled) clutches for coupling a gasifier turbine to a power turbine and wherein the turbine engine includes a combustor for supplying motive fluid to both of the turbines and having an operating characteristic that produces an abrupt fall in the motive fluid temperature at the turbine inlets upon synchronous operation of the independently rotatable turbines.

Abstract: An electronic circuit is used to control a gas turbine engine primarily as a function of turbine inlet temperature and compressor speed and in particular includes a speed governing loop to control compressor speed according to throttle position and modified by a temperature limiting compensation loop which accurately sets the turbine inlet temperature limit according to a schedule which avoids engine surge and destructive temperatures. The compensation loop is particularly designed to provide quick response to acceleration demands and a smooth transition to temperature limiting. A start fuel schedule circuit is also used to moderate the speed loop during engine starting.