Abstract: An aircraft propeller speed control defines values for propeller speed governing control law parameters, such as gains and dynamic compensations, based on known values of propeller and engine dynamic characteristics over the complete propeller operating envelope. Adjusting control law gains and dynamic compensations as functions of propeller and engine dynamic characteristics over the entire flight envelope provides for control of propeller speed to obtain optimum stability and consistent propulsion performance over the entire flight envelope.

Abstract: An aircraft engine propeller synchrophasing system (4) has a gain stage (8) which varies the gain of the system (4) according to the magnitude of the difference between the preferred propeller relative phase and the measured propeller relative phase.

Abstract: A ground mode pitch position logic and control is shown and described in this invention. A method for scheduling and limiting the pitch actuator reference signal in accordance with the actuator commanded schedule, propeller overspeed and propeller underspeed.

Abstract: A method and apparatus for providing improved phase error measurement as shown and described. The measured phase error (.phi..sub.E) is used as an input to a SYNCHROPHASER.RTM. control which provides for phase control of a slave propeller with respect to a master. The phase error (.phi..sub.E) is the sum of the sensed phase error and 360.degree. divided by N.sub.p times .phi..sub.count minus .phi..sub.ref. .phi..sub.count is a counted number of phase discontinuities which occur in .phi..sub.S, the sensed phase. The values of .phi..sub.count and .phi..sub.E, measured phase output, may be limited in number and magnitude.

Abstract: Governor stability of a propeller pitch controlled speed governor is improved by dynamically compensating a turbine engine speed error signal employed in determining fuel flow. The fuel flow requirement is a function of the dynamically compensated turbine engine speed error signal, an indicated air speed signal, and a power lever angle signal.

Abstract: An aircraft engine propeller autofeather system (4) has a feather solenoid (8) which is actuated by either a signal provided by an engine power loss detector (10) or a signal provided by an engine overspeed detector (12). The overspeed detector (12) detects excessive propeller speed by comparing the speed to a first predetermined value (21) or by comparing the speed rate of change to a second predetermined value (23) combined with comparing the speed to a third predetermined value (25).

Abstract: A propeller speed governor having a derivative feedback of propeller speed and having a means such as a switch to open the derivative feed back loop when airspeed exceeds a predetermined amount is shown and described. This derivative inhibit is used to provide improved dynamic compensation at high and low speeds.

Abstract: A flight-mode propeller overspeed governor and underspeed governor is shown and described. The description includes a reset of the overspeed governor during engine acceleration and a reset of the underspeed governor during engine deceleration to eliminate sluggish transient response in the engine.

Abstract: A propeller overspeed governor logic and control is described in this invention. A method is shown for providing a variable propeller pitch rate from a discrete pitch command to improve governing dynamic characteristics.

Abstract: A method and apparatus for integral control of a dependent variable in a system having at least two independent variables which influence the dependent variable is disclosed. A difference signal indicative of the difference between the sensed dependent variable and a reference is integrated and provided to a hysteresis transfer function. The output of the transfer function is subtracted from the integrated difference signal and the resulting signal is used to control an independent variable which thereby influences the dependent variable only for small magnitude signal variations in the integrated signal. The integrated signal is used to control another independent variable for large magnitude signal variations in the integrated signal. The other independent variable is typically only capable of influencing the dependent variable for large magnitude signal variations.

Abstract: An improved slave propeller SYNCHROPHASER.RTM. device and mode logic for a multi-propeller aircraft is disclosed. A designated master propeller has at least one associated slave propeller which has its speed and phase controlled with respect to the master by initially controlling the speed of the slave propeller to within a selected constant number of RPM of the master so that the master and slave propellers are periodically in phase and then switching to phase control for controlling the speed of the slave propeller in the presence of a phase difference signal having an absolute magnitude less than a selected absolute magnitude. A selected phase difference relationship between the master and the slave may thus be effected with minimum transient effect on the speed of the slave propeller.

Abstract: An improved slave propeller synchrophaser (10) includes a first control (14) responsive to a phase difference signal (28) and a phase difference reference signal (26) for providing a phase error signal (112) and for providing a propeller speed reference bias signal (40) for a speed governor (46), and also includes, according to the present invention, a second control (12) responsive to the phase error signal (112) for providing an engine power reference bias signal (80) for an engine power control for providing a very limited amount of propeller fine speed control within the dead band of the propeller speed governor while at the same time substantially maintaining engine power at the commanded power level.

Abstract: A coordinated fan pitch, fuel flow and fan exhaust nozzle area control for a gas turbine powered aircraft propulsor of the bypass duct, variable pitch and exhaust nozzle configuration serves to effectuate reverse pitch change through feather, by minimizing forward thrust excursion and shaft torque to obtain rapid reverse thrust response.

Abstract: A control for a variable pitch fan propulsor driven by a turbine type of power plant which fan is mounted in an engine bypass duct having a variable exit nozzle. The control serves to coordinate the control of fuel flow to the engine, the area of the fan exit nozzle, and the pitch of the fan blades by biasing the power lever position signal with Flight Mach No. An additional feature is the inclusion of fan surge control derived from signals of flight Mach No. and corrected free turbine speed.