Abstract: A system and method for slowing the rotation of a rotor using, for example, rotor brake system for a rotorcraft comprises: one or more generators connected to a main rotor gearbox; an electric distributed anti-torque system mounted on a tail boom of the rotorcraft comprising two or more electric motors connected to the one or more generators, wherein the two or more electric motors are connected to one or more blades; and wherein a rotation of the rotor is slowed by placing a drive load on the main rotor gearbox with the one or more generators to bleed the mechanical power from rotor into electrical power via the two or more electric motors, wherein the electric distributed anti-torque system generates thrust in opposing directions.

Abstract: Methods and related apparatus for improving synchronization of two or more engines on an aircraft are disclosed. Such method may be used where each engine comprises a first spool and a second spool, and, where a rotational speed of a first spool of a first engine has been substantially synchronized with a rotational speed of a first spool of a second engine. An exemplary method comprises receiving a value of a sensed parameter useful in controlling the first engine; adding a bias to the value; and using the biased value for controlling the first engine to cause a change in rotational speed of the second spool of the first engine in relation to the rotational speed of the first spool of the first engine.

Abstract: Semiconductor device structures with a gate structure having different profiles at different portions of the gate structure may include a fin structure on a substrate, a source/drain structure on the fin structure, and a gate structure over the fin structure and along a sidewall of the fin. The source/drain structure is proximate the gate structure. The gate structure has a top portion having a first sidewall profile and a bottom portion having a second sidewall profile different from the first sidewall profile.

Abstract: Herein provided are methods and systems for controlling operation a first propeller of an aircraft, the first propeller associated with a first engine, the aircraft further comprising a second propeller associated with a second engine. A first requested engine power for the first engine is obtained. A second requested engine power for the second engine is obtained. The first propeller is synchronized with the second propeller by setting a first propeller command for the first propeller based on the first and second requested engine power, and the first propeller command is sent for the first propeller.

Abstract: A system is described that includes a turbine engine including an engine fan including one or more variable-pitch blades driven by a shaft, which rotates at a rotational speed which depends on a pitch of the one or more variable-pitch blades of the engine fan. The system further includes a generator configured to produce alternating-current (AC) electricity at a particular frequency relative to the rotational speed of the shaft. The system also includes a propulsor, which includes a propulsor motor and a propulsor fan. The propulsor motor is configured to drive, based on the AC electricity produced by the generator, the propulsor fan. The system includes a controller configured to control the particular frequency of the AC electricity by at least controlling the pitch of the one or more variable-pitch blades of the engine fan and thereby the rotational speed of the generator.

Abstract: A method of controlling a Counter-Rotating Open-Rotor (CROR) includes mechanically linking a pitch change system of a first rotor with a pitch change system of a second rotor and commanding a Blade Angle (Beta1 commanded) of the first rotor such that a Blade Angle (Beta2 Actual) of the second rotor is a function of the commanded Blade Angle (Beta1 commanded) to provide a linear relationship between an actual Blade angle (Beta1 Actual) and Beta1 commanded of the first rotor and a non-linear relationship between Beta2 Actual and Beta1 commanded.

Abstract: The present invention refers to a method for controlling an aircraft propeller system during thrust reversal, wherein it is checked whether each power plant is ready for the transition to negative pitch, and where the propellers transition to negative pitch is controlled from a flight control system, such as only when both power plants are ready for the transition to negative pitch, the flight control system instructs the aircraft propeller system to reverse thrust. If a power plant failure is detected before a reversal order is received, then the flight control system is informed of that failure condition, and then the flight control system will disable the thrust reversal operation as long as the failure condition remains. The method of the invention improves the aircraft controllability during landing operations, reduces pilot workload, and improves passenger comfort during landing and taxing.

Abstract: A midframe portion (313) of a gas turbine engine (310) is presented and includes a compressor section with a last stage blade to orient an air flow (311) at a first angle (372). The midframe portion (313) further includes a turbine section with a first stage blade to receive the air flow (311) oriented at a second angle (374). The midframe portion (313) further includes a manifold (314) to directly couple the air flow (311) from the compressor section to a combustor head (318) upstream of the turbine section. The combustor head (318) introduces an offset angle in the air flow (311) from the first angle (372) to the second angle (374) to discharge the air flow (311) from the combustor head (318) at the second angle (374). While introducing the offset angle, the combustor head (318) at least maintains or augments the first angle (372).

Abstract: A mechanism for adjusting pitch of blades of a propeller of a system of contra-rotating propellers for a turbomachine, wherein each blade moves around a radial axis. The mechanism includes a linear actuator, a structure to transform movement imparted by the linear actuator into rotation of each of the blades in a synchronized manner around their radial axis, the structure including a bracket of longitudinal axis formed of a central ring, an outer ring, and multiple radial arms rigidly connected to the central ring and to the outer ring. The central ring can be subject to actuation of the linear actuator, and the central ring and the outer ring are positioned in two separate planes, orthogonal to the longitudinal axis, such that the bracket is shaped as a truncated cone.

Abstract: A damping device includes a calculator calculating a pseudo vibration to cancel a source vibration transmitted from a vibration source to a position to be damped, using an adaptive control algorithm. The canceling vibration is generated according to the pseudo vibration. A vibration detector detects an error vibration remaining at the position. The adaptive control algorithm is adapted by learning to reduce the error vibration. A frequency recognizer recognizes a frequency of the source vibration from a signal related to the vibration source. The frequency of the vibration is used to determine a frequency of the pseudo vibration. A phase difference identifier identifies a phase difference between the error vibration and the canceling vibration according to the pseudo vibration, and a frequency corrector corrects, according to the phase difference, the frequency of the vibration to eliminate the phase difference.

Abstract: A method and apparatus for controlling a propeller of a contra-rotation open fan (CROF) engine of an aircraft is provided. A diameter of the propeller is set to be at a first diameter during at least a portion of a first flight condition of the aircraft. The diameter of the propeller is set to be at a second diameter, different from the first diameter, during at least a portion of a second flight condition of the aircraft.

Abstract: A simple, robust and systematic control solution for open rotor control with a differential gearbox is disclosed. When the two counter rotating rotors of a CROR engine are conditioned by the differential gearbox, the two rotors speeds are coupled for given input torque. The solution provided by the current disclosure mathematically decouples these two rotors by transforming the original individual actuator input and speed output into differential & average input and output. Because the newly formed control system representation of the plant has decoupled input/output mapping, it follows that the simple SISO control can be applied. Furthermore, the current control solutions allow a simple and well-coordinated speed phase synchronizing among the four rotors on a two-engine vehicle.

Abstract: A drive device (D) for driving first and second lift rotors (2, 3) of a twin-rotor rotorcraft, includes link elements provided with first and second transmission shafts (5, 6) for synchronizing the first and second transmission members (74, 84) of first and second main gearboxes (7, 8), the first main gearbox (7) being provided with first power combiner element (73) firstly meshing with the first transmission member (74) and secondly mechanically linked with the first transmission shaft (5) and with the second transmission shaft (6), and the second main gearbox (8) being provided with second power combiner element (83) firstly meshing with the second transmission member (84), and secondly mechanically linked with the first transmission shaft (5) and with the second transmission shaft (6).

Abstract: A device for controlling pitch of fan blades of a turboprop including at least one set of variable-pitch fan blades constrained to rotate with a rotary ring centered on a longitudinal axis and mechanically connected to a turbine rotor, each blade coupled for pitch adjustment to a synchronization ring. A turntable is mounted via a rotary connection to a rod of an actuator that is secured to a stationary structural element of the turboprop, the turntable being mechanically connected to the synchronization ring by a plurality of connection arms hinge-mounted on the turntable and connected to the synchronization ring such that a longitudinal movement of the turntable under drive from the actuator causes the synchronization ring to turn about the longitudinal axis.

Abstract: A system and method for pitching a rotor blade in a wind turbine are disclosed. The method includes collecting in an individual pitch controller for the rotor blade a pitch offset angle relative to a collective pitch angle. The method further includes determining a synchronized pitch offset angle. The method further includes, after an emergency condition occurs, pitching the rotor blade towards the synchronized pitch offset angle.

Abstract: The object is to reduce aerodynamic load when a wind turbine is halted. When a wind turbine halt command is input, pitch angles of wind turbine blades 5-1, 5-2, and 5-3 are matched, and then the pitch angles of the wind turbine blades 5-1, 5-2, and 5-3 are moved to a feathering position.

Abstract: A motor control apparatus includes a first FG pattern for generating a first induced voltage attendant upon rotation of the rotor of a motor; a second FG pattern for generating a second induced voltage due to noise; a differential amplifier for differentially amplifying the first and second induced voltages, which are input thereto; and a motor speed control unit for controlling rotation of the motor so as to achieve synchronization between the output of the differential amplifier and a prescribed frequency signal.

Abstract: The exchange, removal or addition, as applicable, of media and/or power between the individual shafts of an engine, between individual engines and between the engines and the aircraft provides for additional degrees of freedom, enabling engine parameters to be addressed in terms of a reduction or avoidance of negative resonances or beats. It also provides an ability to alter thrust from engines of a multi-engined aircraft to reduce rudder trim.

Abstract: The exchange, removal or addition, as applicable, of media and/or power is provided between the individual shafts of an engine, between individual engines and between the engines and the aircraft. Thus, additional degrees of freedom are provided, enabling engine parameters to be addressed in terms of a reduction or avoidance of negative resonances or beats. It also provides an ability to alter thrust from engines of a multi-engined aircraft to reduce rudder trim.

Abstract: A method for reducing the total operating noise and/or the total vibration of at least two generally-identical rotating machines. In one embodiment, the noise (or vibration) contribution of each machine at a predetermined reference relative phase angle is estimated. Optimum phase angles are calculated by minimizing a cost function which includes such estimated noise (or vibration) contributions and each rotating machine's relative phase angle. In another embodiment, the gradient of a weighted sum of a measure of the magnitude of the acoustic pressure amplitude of the total operating noise (or the amplitude of the total vibration) is measured. Each machine phase angle is adjusted by a predetermined increment opposite in sign to its associated gradient. The measuring and adjusting are repeated until the gradient is within a limit.

Abstract: A synchrophaser for a multi-engine, propeller-driven aircraft including a filter that automatically compensates for misalignment of blade position sensor tabs through derivation and application of a correlation coefficient. The correlation coefficient is calculated in a self-adjustment derivation, utilizing a dynamic tolerance band, providing increased accuracy in propeller speed determination. The correlation coefficient brings about an apparent uniform distribution of blade position sensors, as seen by the synchrophaser, thus eliminating a primary source of cyclic propeller speed disturbances. The correlative filer accomplishes its task without the phase shifting normally encountered in other digital filtering technique.

Abstract: An "adaptive synchrophaser" is disclosed for modifying the phase angle relationship between aircraft propellers to reduce cabin noise and/or vibration. Rather than use a constant pre-selected angle for a specific passenger cabin configuration during a particular flight mode (e.g., during liftoff or cruise), the synchrophaser periodically monitors actual operating conditions and modifies the phase angle accordingly. In the preferred embodiment, a plurality of transducers (microphones) are installed at several cabin locations to sample noise periodically. The signals are then transmitted via a signal conditioner, a multiplexer and an analog-to-digital converter to a signal processor. The processor calculates the maximum acoustic noise at each microphone location for all possible phase angles. It then identifies the optimum phase angle that resulted in the lowest maximum noise anywhere in the cabin, and signals a synchrophaser to set that angle.

Abstract: A propeller control system (1) includes a propeller controller (6) the gain of which is set by a look up table (2) in response to airspeed data supplied by an airspeed detector (4). By varying the gain of the propeller controller (6) an overall system gain can be maintained as the gain of a propeller (7) varies with airspeed.

Abstract: A system is provided for determining tracking error in a propeller or rotor driven aircraft by determining differences in the aerodynamic loading on the propeller or rotor blades of the aircraft. The system includes a microphone disposed relative to the blades during the rotation thereof so as to receive separate pressure pulses produced by each of the blades during the passage thereof by the microphone. A low pass filter filters the output signal produced by the microphone, the low pass filter having an upper cut-off frequency set below the frequency at which the blades pass by the microphone. A sensor produces an output signal after each complete revolution of the blades, and a recording display device displays the outputs of the low pass filter and sensor so as to enable evaluation of the relative magnitudes of the pressure pulses produced by passage of the blades by the microphone during each complete revolution of the blades.

Abstract: A propeller control system comprises a phase controller (11) having a phase control gain to control a propeller phase relationship, free air turbulence detection means (7, 9) and a gain controller (8) for varying the phase control gain in response to detected free air turbulence such that in the presence of turbulence a low gain is selected and in the absence of turbulence a high gain is selected. By varying the gain in this way the sensitivity of the phase controller (11) is reduced during turbulent conditions preventing excessive phase changes by the controller (11) striving to follow a turbulent master propeller. Similarly a speed controller (14) has its gain set by a gain controller (17) according to the degree of turbulence detected.

Abstract: To prevent propeller overshoot, a propeller governor control generates a signal which modifies a speed command issued to a propeller governor. The signal causes the propeller governor to change blade pitch before the propeller reaches its commanded speed. The propeller governor control also compensates for small calibration errors in the propeller governor.

Abstract: A control circuit for synchronizing the speed of a plurality of engines of an aircraft. The control circuit includes first and second counters for counting pulses in a reference pulse train and an engine speed pulse train over a predetermined time interval and third and fourth counters for determining the time between the last pulse of the reference pulse train counted during the predetermined time interval and the end of that time interval and the time between the last pulse of the engine speed pulse train counted during the predetermined time interval. The frequencies of the reference pulse train and speed pulse train in conjunction with inputs from the first, second, third and fourth counters are used to compute an average phase difference between the reference and speed pulse trains over the predetermined time interval.

Abstract: A marine propeller includes a hub rotatable about a longitudinal axis and having a plurality of blades extending radially outwardly therefrom and pivotable about respective radial pivot axes between a low pitch position and a high pitch position. A disc has a plurality of guide slots each receiving and retaining a respective lever arm extending rearwardly within the hub from a respective blade. A biasing spring coaxial with the longitudinal axis of rotation of the hub biases the disc to in turn bias the lever arms and blades to the low pitch position. The disc is a generally flat planar plate-like member extending radially outwardly from the longitudinal axis at the rear of the hub and includes a preload mechanism accessible at the rear of the hub for adjusting the bias. The disc restricts movement of the lever arms along the guide slots such that the lever arms can move only in unison, which prevents blade flutter.

Abstract: A system for reducing noise created by multiple rotating machines by synchronizing the machines so as to establish a phase relationship between the machines which minimizes the noise. One or more feedback sensors, such as microphones, are placed so as to sense the noise to be reduced. The noise signals from the microphones are sent to a controller. Tachometer signals of the rotational speed of each machine are also sent to the controller. The controller generates an output signal in response to the inputs from the microphones and the tachometers that is fed to one or more of the rotating machines in order to establish the desired phase relationships.

Abstract: The rotation of N-bladed propellers of a multi-engine aircraft is controlled by phase angle synchronizer 30 such that a predetermined phase angle offset .phi.3 is maintained between the blades of a first propeller 10 and the blades of a second propeller 20, at which offset cabin noise is reduced to a minimum and cabin vibration to a near minimum. The controller 40 determines the optimum phase angle offset .phi.3 to be that phase angle of the set of N periodic phase angles: .phi.1+K(360/N), where K ranges in integer steps from 0 to N-1, each characteristic of minimum cabin noise generation, beginning with the minimum first phase angle, .phi.1, lying between 0 and 360/N degrees, which is closest to the second phase angle, .phi.2, characteristic of minimum cabin vibration.

Abstract: A self-actuating variable pitch marine propeller which incorporates two or more blades having cylindrical shafts which are rotatably connected to a central hub via cylindrical joints; the blades rotate about and translate radially, relative to the hub center, along the blade shaft, or shank, axis. In operation, the blades move radially outwardly from the hub center as they rotate from lower to higher pitch. The blades are biased towards the lower pitch. As the propeller rotational speed increases, centrifugal forces act on the blade mass creating a radially directed outward force. This radially outward force, upon reaching a sufficient magnitude, causes the blades to move radially outward. A blade positioning mechanism connected between each blade and the hub directs the blades to rotate to a higher pitch angle as the blades move radially outward.

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: An apparatus for controlling the phase of a slave propeller relative to that of a master propeller is shown and described. A logic means having a trajectory function, F(.phi..sub.E), which defines the region for phase holding, i.e. where the error correction signal, .phi..sub.EC, equals phase error .phi..sub.E. In the region of phase holding, normal control is achieved and there is no slipping of control from a first propeller blade to a second propeller blade.

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: Propeller phase control apparatus for use on multi-engine aircraft having, for each engine, an electronic engine control (EEC) for providing an EEC command speed and phase (S/P) signal to control propeller phase and shaft speed, and a speed and phase control (SPC) for regulating the propeller's blade pitch angle to adjust the shaft speed thereof in dependence on the EEC command S/P signal value, includes: a SYNCHROPHASER Reference Unit (SRU) having a signal processor with signal memory, the memory including stored signals definitive of a speed and phase algorithm, the signal processor calculating a common SRU command S/P signal value for all SPCs in accordance with the algorithm and in dependence on the sensed values of selected flight data indicative of engine performance, and further includes an electronic switch for each SPC, for selecting either the SRU command S/P signal of the engine's EEC command S/P signal for presentation to the SPC.

Abstract: In the invention, the speeds of both propellers in a counterrotating aircraft propeller pair are measured. Each speed is compared, using a feedback loop, with a demanded speed and, if actual speed does not equal demanded speed for either propeller, pitch of the proper propeller is changed in order to attain the demanded speed. A proportional/integral controller is used in the feedback loop. Further, phase of the propellers is measured and, if the phase does not equal a demanded phase, the speed of one propeller is changed, by changing pitch, until the proper phase is attained.

Abstract: Control system for synchrophasing the propellers of an aircraft, each propeller provided with a blade pitch controller for controlling the blade angle of the propeller, the systen containing for each propeller a control loop, comprising: a revolution rate controller, means for determining the blade passing frequency, an adjustable propeller revolution rate reference source supplying a revolution rate setpoint control signal, comparator means for comparing the blade passing frequency with said setpoint to generate an error signal for the revolution rate controller.

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 phase and speed control system for synchronizing the speed and controlling the phase relationship between a pair of aircraft engines, each engine having associated therewith a centrifugal governor, includes a phase comparator circuit which provides a pulse width modulated signal only to the governor coil of the engine having the slower initial rotational velocity. A variable delay on one input of the phase comparator may be adjusted to determine the relative rotational phase relationship between the engines.

Abstract: A plurality of variable diameter rotors with mechanism for varying the diameter of the rotors synchronously, and including mechanism to limit the diameter of the rotors.