Rotorcraft having a flight control system for improved rotorcraft control upon in-flight shutdown in asymmetric flight state modes

Abstract

The invention relates to a rotorcraft (100) having a main rotor (110) with at least one main rotor actuator (114), a series actuator arranged upstream of the main rotor actuator, an engine (180) for powering the main rotor, and a flight control system (160) for controlling flight operations in an AEO mode or in an AFR mode, the flight control system comprising a control logic (165) for pre-conditioning the series actuator upon entering the AFR mode to enable rotorcraft control in case of an IFSD, wherein the pre-conditioning of the series actuator comprises shifting a reduced nominal range of series actuator travel authorized for the series actuator in the AEO mode into a reduced shifted range of series actuator travel authorized for the series actuator in the AFR mode to enable an authorization of an increased range of travel in case of an IFSD to provide sufficient control authority for recovery maneuver.

Description

Technical Field

[0001] This invention relates to a rotorcraft comprising: at least one main rotor having at least one main rotor actuator for modifying main rotor control according to the current flight status of the rotorcraft; at least one first engine and at least one second engine for powering the at least one main rotor; and a flight control system for controlling the flight operation of the rotorcraft in at least all engine operating modes or in an asymmetric flight mode, wherein in all engine operating modes, at least one first engine and at least one second engine power the at least one main rotor, and in the asymmetric flight mode, only at least one first engine poweres the at least one main rotor. The invention also relates to a flight control system and a method for controlling the flight operation of such a rotorcraft. Background Technology

[0002] More generally, a multi-engine rotorcraft (e.g., a twin-engine helicopter) comprising at least one main rotor and at least two engines for powering the at least one main rotor can operate in All Engine Operation (AEO) mode, in which each of the at least two engines supplies non-zero mechanical power to the at least one main rotor, such that the at least two engines together (e.g., in a substantially symmetrical manner) supply the required mechanical power to the at least one main rotor. The at least two engines can be implemented as thermal engines and are typically over-engineered to allow at least one main rotor to be driven by a single engine in the event of a failure of the other engine. Furthermore, to reduce fuel consumption of the thermal engines, the multi-engine rotorcraft can operate in a so-called Super Idle Operation (SIO) mode, which is primarily designed to reduce fuel consumption and contribute to reduced emissions and decarbonization during cruise flight during a given flight mission, and / or increase the rotorcraft's flight endurance or range. Therefore, in SIO mode, one of the selected engines is set to passive operation by desynchronizing it (i.e., zero power), so that the other engine needs to handle the flight mission alone by increasing its power request. In SIO mode, the passive engine is running, but it may be idling or operating at a speed slower than idle (i.e., over-idle).

[0003] Alternatively, multi-engine rotorcraft can operate in Single-Engine Operation (SEO) mode, in which one of at least two engines can be shut down and rendered inactive, requiring the other engine to handle the flight mission independently by increasing its power request. In fact, even when operating at a relatively high load power condition with increased power request, the other engine typically consumes less fuel than if both engines were operating together at a relatively low load power condition with reduced power request. Therefore, SEO and SIO modes are economical operating modes, also known as Asymmetric Flight Conditions (AFR) modes for asymmetric operation involving thermal engines, since at least two engines do not operate in the same manner.

[0004] During AFR mode, a multi-engine rotorcraft may face an in-flight shutdown (IFSD) situation where the currently operating engine is powering at least one main rotor, which may end in an autorotation state. Regarding autorotation automation, US11,194,349B2 and US2007 / 164167A1 describe methods for autorotating the main rotor of the corresponding rotorcraft upon detection of an engine failure to allow for a safe landing and recovery of the rotorcraft following the engine failure.

[0005] However, due to the time sensitivity of autorotation, such engine failure scenarios would require immediate action on flight control, such as to avoid a rapid and catastrophic drop in main rotor speed (RPM). For example, document US2024 / 0083570A1 describes a rotorcraft comprising a first engine, a second engine, a main engine restart system for the first engine, a rapid-start engine restart system for the first engine, and a computer system. This computer system is configured to detect a failure in the second engine during a Reduced Engine Operation (REO) flight mode, where the first engine has been intentionally shut down in flight and the second engine will remain operational, and, in response to the detection of a second engine failure during REO flight mode, automatically restart the first engine using the rapid-start engine restart system.

[0006] Furthermore, document US11,299,286B2 describes a method for operating a rotorcraft comprising a plurality of engines configured to power the rotorcraft and at least one rotor coupled to the plurality of engines. The rotorcraft can operate in an asymmetric operating state (AOR), wherein at least one first engine of the plurality of engines is the currently operating engine in working mode to power the rotorcraft, while at least one second engine of the plurality of engines is not operating and therefore operates in standby mode to substantially not power the rotorcraft. If a failure of the currently operating engine is detected, one or more flight control inputs of at least one rotor are adjusted to compensate for the reduction in rotor speed caused by the failure of the currently operating engine. The flight control input(s) are adjusted to increase the rotor speed such that at least one rotor rotates at substantially the same rotor speed as before the failure of the currently operating engine. Furthermore, a command is given to increase the power output of the non-operating engine. Furthermore, the flight control input(s) are further adjusted. For example, the flight control input(s) can be restored to their values ​​before the corresponding engine failure.

[0007] However, if this failure condition of the currently operating engine occurs during AFR mode, and appropriate action is not taken quickly enough, reactivating the currently decelerated or shut-down engine in AFR mode during a flight mission may require more time than at least one main rotor of the given rotorcraft can provide before the end of a critical and unrecoverable low rotor speed state. The situation becomes even more severe if the given rotorcraft's autopilot is engaged and / or rotor inertia is low and the pilot is, for example, inattentive. For instance, if the given rotorcraft's autopilot is engaged, certification requires at least three seconds of non-interference before any pilot action, which can conceivably become an unrecoverable flight situation after the aforementioned failure condition of the currently operating engine is detected. Summary of the Invention

[0008] Therefore, an object of the present invention is to provide a novel rotorcraft comprising a flight control system for controlling at least the flight operations of the rotorcraft in the event of an IFSD (In-Flight Disruption) in AFR (Air-Free Flight) mode, wherein the flight control system is adapted to enable the rotorcraft to safely recover from an in-flight engine failure of the nominal engine before the engine, which has been inactive until now, is fully restored during AFR mode. Another object of the present invention is to provide a flight control system and a method for controlling the flight operations of such a rotorcraft.

[0009] The aforementioned objective is achieved by a rotorcraft comprising the features of claim 1. More specifically, according to the invention, the rotorcraft comprises: at least one main rotor having at least one main rotor actuator for modifying main rotor control according to the current flight status of the rotorcraft; at least one first engine and at least one second engine for powering the at least one main rotor; and a flight control system for controlling the flight operation of the rotorcraft, wherein the main rotor actuator stroke of the at least one main rotor actuator is adjusted via the serial actuator stroke of at least one serial actuator arranged upstream of the at least one main rotor actuator, wherein the at least one serial actuator is coupled to a control stick, the control stick being connected to at least one parallel actuator, and wherein the flight control system is configured to control the flight operation of the rotorcraft at least in All Engine Operation (AEO) mode or in Asymmetric Flight State (AFR) mode, wherein in All Engine Operation (AEO) mode, at least one first engine and at least one second engine power at least one main rotor, and in Asymmetric Flight State (AFR) mode, only at least one first engine power at least one main rotor. The flight control system includes control logic configured to pre-adjust at least one serial actuator upon entering AFR mode to enable rotorcraft control in the event of an in-flight stop (IFSD) of at least one first engine in AFR mode. The pre-adjustment of the at least one serial actuator includes shifting a reduced nominal travel range authorized for the serial actuator travel of at least one serial actuator in AEO mode to a reduced shift travel range authorized for the serial actuator travel of at least one serial actuator in AFR mode, thereby authorizing an increased travel range in the event of IFSD. This increased travel range is adapted to provide sufficient control authority required to restore maneuverability in response to the occurrence of IFSD.

[0010] Preferably, at least one main rotor actuator can be used for collective axis actuation and / or pitch / longitudinal axis actuation of at least one main rotor. In particular, the collective axis command for collective axis actuation can be generated by a given control level (e.g., the control level applied by the master stick) plus the sum of the actuations of the serial actuators, and the master stick can be commanded by parallel actuators or by the pilot of the rotorcraft.

[0011] Specifically, according to the present invention, each engine operating state of a rotorcraft can be associated with a series actuation stroke range having possible asymmetric limitations. For example, the flight control system (FCS) may potentially face the following engine states:

[0012] a) AEO status,

[0013] b) For example, AFR status generated by SEO or SIO.

[0014] c) An IFSD state in an AFR, for example, during SEO / SIO, where the power-providing engine that was operating so far (e.g., the first of at least two engines) unexpectedly shuts down due to engine failure, while the engine that was intentionally slowed down or shut down so far (e.g., the second of at least two engines) restarts but cannot immediately provide sufficient power to the main rotor.

[0015] d) One engine inoperable (OEI) state, for example, at least two engines, only the second engine powers at least one main rotor, while the first engine of at least two engines is inoperable due to engine failure.

[0016] e) Dual Engine Inoperability (TEI) state, such as after IFSD in AFR, the second of at least two engines fails to restart successfully and power the main rotor, or unexpectedly stops later during OEI flight operations, resulting in the rotorcraft facing a complete engine failure.

[0017] In this way, a specified serial actuation stroke range can be defined for each of the above engine states. If necessary, a specified serial actuation stroke range can also be defined for any transition between those states.

[0018] Furthermore, based on the engine status, appropriate FCS targets can be calculated and defined for flight control, and then suitable flight control strategies can be selected based on the corresponding FCS targets. For example, for engine status c) above, FCS targets can be managed based on initial flight conditions and optimal pitch and collective axis commands to maintain sufficient main rotor speed (i.e., RPM) and minimize altitude loss before the second engine restarts to restore full power after one working engine fails. Additionally, roll and yaw axes can be controlled to minimize the response caused by power loss and recovery maneuvers.

[0019] Advantageously, specific pre-adjustments to the actuator during AFR mode enable the actuator to operate with sufficient available control authority (e.g., maximum available travel range) to recover control from power loss of the rotorcraft.

[0020] Preferably, pre-tuning of at least one serial actuator is performed as an automated process. This way, once the AFR mode is activated, increased travel is available, and when a working engine failure is detected, an automatic response can be achieved using the increased travel of the serial actuator via parallel and / or serial FCS actuators. Thus, the rotorcraft's flight envelope can be optimized by automatically controlling the trajectory and responding to a working engine failure in AFR mode before achieving full recovery of the currently non-working engine. Furthermore, this automatic response, addressing the actual manner of maneuvering required by commands, can also be performed by conventional parallel and serial actuators, thereby reducing the overall cost and risk of this approach.

[0021] Furthermore, by using an increased stroke for the automatic control trajectory, altitude loss during flight operations can be minimized when the corresponding altitude margin is small, or collisions with aircraft flying in a lower flight corridor (i.e., 200m below the rotorcraft) can be avoided. More specifically, with the increased stroke of the corresponding automated FCS (AFCS) actuators, automatic in-flight optimization of the combination of flight and main rotor speed by adjusting the corresponding controls (i.e., total pitch, periodically varying pitch, pedals, and other aerodynamic surfaces) during a stable automatic rotation descent advantageously minimizes altitude loss during engine in-flight reactivation. For example, such control adjustments could include automatically reducing the rotorcraft's current flight speed to an optimal climb rate Vy, which could reduce the corresponding power requests during automatic rotation and during subsequent initial flight recovery after engine in-flight reactivation.

[0022] For example, in engine state c) above, a minimum main rotor RPM constraint can be applied, for instance, by preventing the main rotor RPM from dropping below 90%, 85%, or 80%. Furthermore, when power is regained from a restarted engine, these objectives in engine state c) can gradually transform into the objectives in engine state d). Engine state d) is the nominal, naturally soft end of engine state c).

[0023] Unlike conventional autopilot, where a higher main rotor RPM and therefore a higher descent rate are often preferred, the aforementioned autopilot implements a new initial deceleration strategy: reducing the main rotor speed, specifically to the optimal climb rate Vy, in order to reduce the descent rate. This strategy is particularly useful when the helicopter is flying at a rate sufficiently higher than the optimal climb rate Vy at the moment of engine failure.

[0024] According to some aspects, pre-tuning of at least one serial actuator when entering AFR mode may include increasing the reduced shift travel range of the serial actuator travel to the maximum available travel range to provide fully available control in the event of IFSD.

[0025] According to some aspects, pre-adjustment of at least one serial actuator upon entering AFR mode may include: shifting the neutral stroke position of at least one serial actuator to the maximum shifted neutral stroke position to provide fully available control in the event of IFSD; and adjusting at least one parallel actuator to compensate for the shift of the neutral stroke position of at least one serial actuator.

[0026] According to some aspects, the control logic can be configured to set the neutral stroke position of the serial actuator stroke of at least one serial actuator within the maximum available stroke range, wherein the neutral stroke position is the center stroke position in AEO mode, which divides the maximum available stroke range evenly into two maximum available stroke regions in two opposite stroke directions, and wherein the reduced nominal stroke range includes two reduced authorized stroke regions that are smaller than the two maximum available stroke regions.

[0027] If needed, the state of each engine can be associated with three serial actuation configuration parameters: minimum (min) stroke range, maximum (max) stroke range, and "neutral stroke". For example, in AEO mode, a set of AEO-specific serial actuation configuration parameters (i.e., minimum stroke range, maximum stroke range, and "neutral stroke") can be selected, which includes selecting opposite minimum and maximum stroke ranges and selecting a "neutral stroke" that falls between the minimum and maximum stroke ranges.

[0028] According to some aspects, pre-adjustment of at least one serial actuator upon entering AFR mode may include limiting the maximum available travel range in AFR mode to a reduced shift travel range in AFR mode until an IFSD of at least one first engine occurs, wherein the reduced shift travel range is less than the maximum available travel range and preferably equal to the reduced nominal travel range.

[0029] According to some aspects, pre-adjustment of at least one serial actuator upon entering AFR mode may include shifting the neutral stroke position of the serial actuator stroke of at least one serial actuator from the center stroke position in AEO mode to the shift stroke position in AFR mode, the shift stroke position being adapted to realize an increase in control authority for main rotor control in order to achieve the required recovery maneuver in response to the occurrence of IFSD.

[0030] According to some aspects, reducing the shift travel range can be achieved by uniformly dividing the shift neutral travel position of the serial actuator travel of at least one serial actuator into two shift travel regions.

[0031] According to some aspects, the control logic is configured to pre-adjust at least one parallel actuator when entering AFR mode, so as to achieve rotorcraft control by modifying the current parallel actuator position of at least one parallel actuator to compensate for the shift of the neutral stroke position of the serial actuator stroke of at least one serial actuator when an IFSD of at least one first engine occurs in AFR mode.

[0032] More specifically, since the axis command is generated by the sum of the joystick / pedal and the serial actuation, each serial actuation offset needs to be compensated for by the opposite travel of the joystick / pedal commanded by its respective parallel actuator to keep the sum unaffected by the serial actuation offset. Thus, the parallel actuator command must adapt to each change in the "neutral travel" position.

[0033] According to some aspects, modifying the current parallel actuator position of at least one parallel actuator to compensate for a shift may include: moving the neutral control position of a control lever from a nominal neutral control position in AEO mode to a shifted neutral control position in AFR mode, different from the nominal neutral control position, by means of at least one parallel actuator, the shifted neutral control position being adapted to allow serial actuator travel of at least one serial actuator with increased privileges.

[0034] Depending on some aspects, the control logic can be configured to modify the force feedback to the pilot of the rotorcraft via the associated force-sensing characteristics of the parallel actuators.

[0035] More specifically, typically two different parties (i.e., the pilot and the actuator) act on the same parallel actuation control. Thus, for a given control, the parallel actuator must act on that control via a force transmission scheme that remains compatible with any pilot action that may occur at any given time. Therefore, the pilot will inevitably feel some reaction force each time they perform a manual / pedal action.

[0036] Similarly, there are typically two key objects in parallel actuation: the "hands / feet off" command for the stick / pedal position and the tactile feedback to the pilot. When the stick / pedal is commanded to travel a large distance during IFSD, the pilot may interfere with these controls, most likely speeding up or slowing down the stick / pedal movement. Therefore, force-feedback or tactile feedback exists to help or guide the pilot understand what should be done to optimally recover from IFSD, but also to provide the pilot with some means to adjust the expected helicopter commands in response to such IFSD.

[0037] For example, two types of tactile feedback can be installed on parallel actuators: preloaded frictional feedback for overall and yaw commands, and preloaded spring effect feedback for pitch and roll commands.

[0038] In addition, two types of haptic feedback management can be provided. One is a parallel force transmission mechanism, a classic mechanism that acts as preloaded friction or spring effect feedback. In this case, the only way to affect the perceived haptic feedback is through a command at one of the inlets of this parallel force transmission mechanism. The other is to command the parallel actuator motor to generate the desired torque and thus produce haptic feedback. The latter can provide more degrees of freedom in haptic feedback management. Therefore, this type of haptic feedback management must provide a certain guiding force to the pilot when the control device is far from its proper position, and follow the pilot and provide a “trimmed” control position when the control device approaches an acceptable stationary position. Therefore, the parallel actuator is preferably configured with the ability to provide different maximum speeds depending on engine status, and the ability to command haptic force to guide the pilot but also follow the pilot during manual / pedal intervention, especially in critical flight situations such as IFSD and recovery from dormant engine hibernation.

[0039] According to some aspects, at least one serial actuator may include a first serial actuator and a second serial actuator, wherein pre-adjustment of the at least one serial actuator may include: maximizing a first authorized stroke range of the first serial actuator's first serial actuator stroke from a first reduced nominal stroke range authorized in AEO mode to a first maximum available stroke range authorized when IFSD occurs, and maximizing a second authorized stroke range of the second serial actuator's second serial actuator stroke from a second reduced nominal stroke range authorized in AEO mode to a second maximum available stroke range authorized when IFSD occurs.

[0040] If needed, the first and second serial actuators can be the same serial actuator. The serial actuation configuration parameters can then be evenly distributed between the first and second serial actuators or among all the same serial actuators.

[0041] Alternatively, the first and second serial actuators can be different serial actuators. Then, the serial actuation configuration parameters can be distributed unevenly among the first and second serial actuators or among all serial actuators, depending on the specific characteristics of each serial actuator.

[0042] According to some aspects, the reduced shift travel range of the serial actuator stroke of at least one serial actuator used to control the flight operation of a rotorcraft in AFR mode until IFSD occurs can be provided solely by the first maximum available travel range of the first serial actuator.

[0043] According to some aspects, the control logic can be configured to enable the serial actuator stroke of at least one serial actuator to be actuated within a first maximum available stroke range and a second maximum available stroke range, in order to control the flight operation of the rotorcraft in response to the occurrence of IFSD in AFR mode.

[0044] Another objective of the foregoing is achieved by an FCS for a rotorcraft comprising at least one main rotor having at least one main rotor actuator for modifying main rotor control according to the current flight status of the rotorcraft, wherein the main rotor actuator stroke of the at least one main rotor actuator is adjusted via the serial actuator stroke of at least one serial actuator arranged upstream of the at least one main rotor actuator, wherein the at least one serial actuator is coupled to a control stick connected to at least one parallel actuator, and wherein at least one first engine and at least one second engine are provided for powering the at least one main rotor. The FCS is configured to control the flight operation of the rotorcraft at least in AEO mode or AFR mode, wherein in AEO mode, at least one first engine and at least one second engine power at least one main rotor, and in AFR mode, only at least one first engine powering at least one main rotor, the FCS comprising the features of claim 14. More specifically, according to the invention, the FCS includes control logic configured to pre-adjust at least one serial actuator upon entering AFR mode to enable rotorcraft control in the event of an in-flight shutdown of at least one first engine in AFR mode, wherein the pre-adjustment of the at least one serial actuator includes shifting a reduced nominal travel range authorized for the serial actuator travel of at least one serial actuator in AEO mode to a reduced shift travel range authorized for the serial actuator travel of at least one serial actuator in AFR mode to authorize an increased travel range in the event of IFSD, the increased travel range being adapted to provide sufficient control authority required to restore maneuverability in response to the occurrence of IFSD.

[0045] Another of the aforementioned objectives is achieved by a method for controlling the flight operation of a rotorcraft, wherein the rotorcraft comprises: at least one main rotor having at least one main rotor actuator for modifying main rotor control according to the current flight status of the rotorcraft, wherein the main rotor actuator stroke of the at least one main rotor actuator is adjusted via the serial actuator stroke of at least one serial actuator arranged upstream of the at least one main rotor actuator, and wherein the at least one serial actuator is coupled to a control stick connected to at least one parallel actuator; at least one first engine and at least one second engine for powering the at least one main rotor; and an FCS for controlling the flight operation of the rotorcraft at least in AEO mode or AFR mode, wherein in AEO mode, at least one first engine and at least one second engine power the at least one main rotor, and in AFR mode, only at least one first engine powers the at least one main rotor, the method comprising the features of claim 15. More specifically, according to the invention, the method includes providing control logic configured to pre-adjust at least one serial actuator upon entering an AFR mode to enable rotorcraft control in the event of an in-flight shutdown of at least one first engine in the AFR mode, wherein the pre-adjustment of the at least one serial actuator includes shifting a reduced nominal travel range authorized for the serial actuator travel of at least one serial actuator in the AEO mode to a reduced shift travel range authorized for the serial actuator travel of at least one serial actuator in the AFR mode to enable authorization of an increased travel range in the event of an IFSD, the increased travel range being adapted to provide sufficient control authority required to restore maneuverability in response to the occurrence of the IFSD. Attached Figure Description

[0046] Preferred embodiments of the invention are summarized by way of example with reference to the accompanying drawings in the following description. In these drawings, parts and elements that are identical or have the same function are labeled with the same reference numerals and characters, and therefore will be described only once in the following description.

[0047] - Figure 1 A side view of an illustrative rotorcraft according to the present invention is shown.

[0048] - Figure 2A It shows Figure 1 Illustrative status of the serial actuators of a rotorcraft, wherein the rotorcraft is operating in AEO mode.

[0049] - Figure 2B It shows Figure 1 Illustrative status of the serial actuators of a rotorcraft, wherein the rotorcraft is operating in AFR mode.

[0050] - Figure 2C It shows the situation when IFSD occurs. Figure 2B Descriptive states of the serial actuators,

[0051] - Figure 3A It shows Figure 1 An illustrative FCS of a rotorcraft, wherein the rotorcraft is operating in AEO mode, and

[0052] - Figure 3B It shows Figure 3A The FCS, in which the rotorcraft is operating in AFR mode. Detailed Implementation

[0053] Figure 1 An aircraft 100 is illustrated, illustratively implemented as a rotorcraft and more specifically as a helicopter. Therefore, for simplicity and clarity, aircraft 100 is hereinafter referred to as "helicopter 100". However, the invention is not limited to helicopters and can be applied equally to any other rotorcraft.

[0054] Helicopter 100 includes at least one main rotor 110, such as a multi-bladed main rotor, for providing lift and forward or rearward thrust during operation. For example, at least one main rotor 110 includes a plurality of rotor blades connected at an associated rotor head 113 to a rotor shaft that rotates about an associated rotor axis during operation of helicopter 100. Two of the plurality of rotor blades are illustratively labeled with reference numerals 111 and 112, respectively.

[0055] At least one main rotor 110 also includes at least one associated main rotor actuator 114. However, suitable actuators that can be used to implement the associated main rotor actuator 114 are well known to those skilled in the art, and therefore their detailed description may be omitted for the sake of brevity and conciseness.

[0056] Illustratively, at least one main rotor actuator 114 is configured to modify the main rotor control of at least one main rotor 110 according to the current flight status of the helicopter 100. For example, the respective main rotor actuator stroke of at least one main rotor actuator 114 is via at least one serial actuator (e.g., arranged upstream of at least one main rotor actuator 114) Figure 2A The serial actuator stroke of the serial actuator 205 in the series (e.g., Figure 2A The stroke of the serial actuator (205c) is adjusted. At least one serial actuator is illustratively coupled to a control lever (e.g., Figure 3A The control lever 301 in the middle is connected to at least one parallel actuator (e.g., Figure 3A Parallel actuator 375 in the middle.

[0057] For example, helicopter 100 includes a fuselage 120 and landing gear 115, which is exemplary only of the skid type. The left side of fuselage 120 is shown, for example, thus illustrating the left wall of the fuselage 120 of helicopter 100. Illustratively, fuselage 120 forms an interior area of ​​the aircraft that accommodates a cockpit 122 and may further accommodate a cabin for passengers and / or cargo. Furthermore, fuselage 120 may be connected at the rear fuselage 124 to a tail boom 130 having a horizontal stabilizer 132. Tail boom 130 may be implemented as an elongated beam element comprising at least a tubular tail boom cone 134.

[0058] Illustratively, the helicopter 100 also includes at least one preferably shrouded anti-torque device 140, configured to provide anti-torque during operation, i.e., to counteract the torque generated by the rotation of at least one main rotor 110, in order to balance the helicopter 100 in terms of yaw. The at least one anti-torque device 140 is illustratively disposed in the rear section of the tail boom 130 and preferably includes a tail rotor 142. The rear section of the tail boom 130 may also include a tail fin 150.

[0059] Preferably, the tail rotor 142 also includes an associated tail rotor actuator 144. However, suitable actuators for implementing the associated tail rotor actuator 144 are well known to those skilled in the art, and therefore, for the sake of brevity and conciseness, their detailed description may be omitted.

[0060] Illustratively, the helicopter 100 includes at least two engines 180 for powering at least one main rotor 110, namely at least one first engine 192 and at least one second engine. It should be noted here that... Figure 1 Only the first engine 192 is individually labeled because it is located on the left side of the helicopter 100. However, as an example, the helicopter 100 is implemented with a twin-engine configuration having two engines forming the at least two engines 180. Therefore, in addition to engine 192, the at least two engines 180 also include another engine, which may, for example, be located on the right side of the helicopter 100, such that it... Figure 1 It is not visible in the middle.

[0061] Helicopter 100 also includes FCS160 for controlling the flight operations of helicopter 100 based on the status of different engines. For example, the status of such engines may include:

[0062] a) AEO state, wherein at least one first engine 192 and at least one second engine provide power to at least one main rotor 110;

[0063] b) AFR configuration, wherein only at least one first engine 192 powers at least one main rotor 110;

[0064] c) IFSD during AFR status, wherein at least one first engine 192 experiences in-flight shutdown under AFR;

[0065] d) OEI state, in which only at least one second engine powers at least one main rotor 110, while at least one first engine 192 is inactive due to a previous in-flight shutdown;

[0066] e) TEI state, in which at least one first engine 192 and at least one second engine do not power at least one main rotor 110, because at least one first engine 192 and at least one second engine are not functioning.

[0067] If necessary, appropriate FCS targets can be calculated and defined for control based on the engine status or transitions between them. Particularly during AFR and when IFSD occurs in a working engine, an appropriate flight control strategy must be selected based on the corresponding FCS targets. For example, different strategies may be required to maintain a safe flight state depending on the flight conditions at the time of IFSD. For instance, a sharp deceleration, even below the optimal climb rate Vy, might be advantageous to minimize altitude loss, or suitable trim conditions (e.g., small bank angles) for minimum power may be favorable.

[0068] According to the present invention, the FCS 160 for controlling the flight operations of helicopter 100, at least in AEO mode or AFR mode, includes control logic 165 configured to pre-adjust at least one serial actuator upon entering AFR mode to enable helicopter control in the event of an IFSD (In-Flight Delay) of at least one first engine 192 under AFR conditions. The FCS 160 can automatically command flight controls 170.

[0069] For example, control logic 165 is configured to pre-adjust (one or more) serial actuators in AFR mode (e.g., SIO / SEO) such that control of the serial actuators will achieve FCS objectives and constraints. If needed, pre-adjustment of (one or more) serial actuators can be used to modify flight control in any of the control axes (i.e., pitch, roll, total, and yaw axes).

[0070] Figures 2A to 2C It shows that it has undergone Figure 1 An illustrative mechanism illustrating the modification of the variable serial actuator stroke range of the serial actuator 205 of the helicopter 100. More specifically, Figure 2AThe serial actuator 205 is illustratively located on the main control axis of the helicopter 100 operating in AEO mode. (See also...) Figure 2A As shown, in AEO mode, the serial actuator stroke of at least one serial actuator 205 is authorized to reduce the nominal stroke range 212, for example, the current serial actuator stroke represented as the current serial actuator stroke position 205c.

[0071] More specifically, at least one serial actuator 205 may have a first end position 210c of the maximum possible travel range 210 of the serial actuator travel 205c in a first operating direction 201 and a second end position 210d of the maximum possible travel range 210 of the serial actuator travel 205c in a second operating direction 202. The maximum possible travel range 210 represents the full available mounted travel range of at least one serial actuator 205, which will be theoretically available regardless of the FCS settings. Reducing the nominal travel range 212 is an authorized travel range that uses only a portion of the maximum possible travel range 210. For example, during AEO mode, the available travel range of at least one serial actuator 205 may be 50% of the maximum possible travel range 210. This authorization can be performed by the FCS via, for example, application software stop.

[0072] like Figure 2A As shown, the neutral stroke position 215 can be set by the FCS for at least one serial actuator 205. More specifically, Figure 1 The control logic 165 is configured to set the neutral stroke position 215 of the serial actuator stroke 205c of at least one serial actuator 205 within the maximum available stroke range 210.

[0073] For example, the neutral travel position 215 can be the center travel position in AEO mode, which uniformly divides the maximum available travel range 210 into two maximum available travel regions 210a and 210b with travel in two opposite travel directions 201 and 202. Illustratively, the reduced nominal travel range 212 can include two reduced authorized travel regions 212a and 212b that are smaller than the two maximum available travel regions 210a and 210b. Illustratively, the reduced nominal travel range 212 is uniformly divided into reduced authorized travel regions 212a and 212b by the neutral travel position 215 of the serial actuator travel 205c of at least one serial actuator 205.

[0074] During AEO mode, the serial actuator stroke 205c can be illustratively performed in the first operating direction 201 from the neutral stroke position 215 to the first end position 212c of the reduced nominal stroke range 212 within the reduced authorized stroke region 212b. The stroke performed in the first operating direction 201 can represent an extension of at least one serial actuator 205, which can result in… Figure 1 The upward control of the total pitch of the main rotor 110. Illustratively, the serial actuator stroke 205c is positioned between the neutral stroke position 215 and the first end position 212c of the reduced nominal stroke range 212 within the reduced authorized stroke region 212b.

[0075] For example, the serial actuator stroke 205c can also be performed in the second operating direction 202 from the neutral stroke position 215 to the second end position 212d reaching the reduced nominal stroke range 212 within the reduced authorized stroke region 212a. The stroke performed in the second operating direction 202 can represent the retraction of at least one serial actuator 205, which can result in… Figure 1 Downward control of the total pitch of the main rotor 110.

[0076] Figure 2A The serial actuator travel 205c shown is illustratively performed in the second operating direction 202 from the neutral travel position 215 toward the second end position 212d. However, it should be noted that the serial actuator travel 205c can also be performed from a current serial actuator position different from the neutral travel position 215. For example, if the current serial actuator position is within the reduced authorized travel region 212b, the serial actuator travel 205c may allow for relatively more retraction and relatively less extension of at least one serial actuator 205. Alternatively, the serial actuator travel 205c can also be performed from the current serial actuator position, which would allow for relatively more extension and relatively less retraction of at least one serial actuator 205, such as... Figure 2B As shown.

[0077] Figure 2B This shows the process of entering AFR mode. Figure 2A The serial actuator 205. In Figure 2B In AFR mode, a reduced shift travel range 216 is authorized for the serial actuator stroke 205c of at least one serial actuator 205. For example, pre-adjustment of at least one serial actuator 205 upon entering AFR mode includes shifting the reduced nominal travel range 212 authorized for the serial actuator stroke 205c of at least one serial actuator 205 in AEO mode into the reduced shift travel range 216 authorized for the serial actuator stroke 205c of at least one serial actuator 205 in AFR mode.

[0078] More specifically, pre-adjustment of at least one serial actuator 205 upon entering AFR mode may include limiting the maximum available travel range 210 in AFR mode to a reduced shift travel range 216 prior to the occurrence of an IFSD of at least one first engine 192 in AFR mode. Illustratively, the reduced shift travel range 216 is smaller than the maximum available travel range 210.

[0079] like Figure 2B As shown, pre-adjustment of at least one serial actuator 205 upon entering AFR mode may further include shifting the neutral stroke position 215 of the serial actuator stroke 205c of at least one serial actuator 205 from the center stroke position in AEO mode to the shift stroke position 225 in AFR mode. Illustratively, the shift stroke position 225 is adapted to implement an increase in control authority for the main rotor control to achieve the required recovery maneuver in response to the occurrence of IFSD, as described below. Figure 2C Detailed description.

[0080] Now return to Figure 2B Upon entering AFR mode, the neutral stroke position 215 of the serial actuator stroke 205c of at least one serial actuator 205 is shifted to a shifted neutral stroke position 225. Illustratively, the reduced shift stroke range 216 is uniformly divided into two shift stroke regions 235m and 235n by the shifted neutral stroke position 225 of the serial actuator stroke of at least one serial actuator. In some embodiments, the reduced shift stroke range 216 of the serial actuator stroke 205c of at least one serial actuator 205 in AFR mode is equal to the reduced nominal stroke range 212.

[0081] In other words, pre-adjustment of at least one serial actuator 205 upon entering AFR mode will shift the authorized travel range, but will not immediately increase the authorized travel range to a travel range greater than the travel range authorized in AEO mode. For example, Figure 2B The reduced displacement range 216 still allows only 50% of the maximum possible range 210 to be used. However, the authorized portion of the maximum possible range 210 is illustratively shifted toward the first end position 210c of the maximum possible range 210.

[0082] like Figure 2B As shown, the authorized operating stroke range 235a of the serial actuator stroke prior to IFSD during AFR mode is equal to the reduced nominal stroke range 212 during AEO mode. Thus, prior to IFSD in AEO mode, the serial actuator stroke 205c can be illustratively executed in the first operating direction 201 from the shift neutral stroke position 225 to the first end position 235c of the reduced shift stroke range 216 within the shift stroke region 235n. For example, prior to IFSD in AEO mode, the serial actuator stroke 205c can also be executed in the second operating direction 202 from the shift neutral stroke position 225 to the second end position 235d of the reduced shift stroke range 216 within the shift stroke region 235m.

[0083] Similar to the serial actuator stroke 205c during AEO mode, the serial actuator stroke 205c prior to IFSD during AFR mode can also be executed from a current serial actuator position different from the shift neutral stroke position 225. For example... Figure 2B The illustrated serial actuator travel 205c has an initial point and an final point within a shift travel region 235m. The initial and final points of the serial actuator travel 205c prior to IFSD during AFR mode can be located anywhere within the reduced shift travel range 216. However, the region outside the reduced shift travel range 216 is the unauthorized region 235b, which is unavailable prior to IFSD.

[0084] Figure 2C This demonstrates the response to the occurrence of IFSD in AFR mode. Figure 2B The serial actuator 205. (Reference) Figures 2A to 2C The pre-adjustment of at least one serial actuator 205 includes shifting a reduced nominal travel range 212 authorized for the serial actuator travel 205c of at least one serial actuator 205 in AEO mode to a reduced shift travel range 216 authorized for the serial actuator travel 205c of at least one serial actuator 205 in AFR mode, to authorize an increased travel range 214 in the event of an IFSD, which is adapted to provide sufficient control authority required to restore actuation in response to the occurrence of IFSD. Illustratively, the increased travel range 214 corresponds to... Figure 2A The maximum possible travel range 210, that is, the travel range between the first end position 210c and the second end position 210d.

[0085] also, Figures 2A to 2C The mechanism of the variable serial actuator stroke range of at least one serial actuator 205 shown illustrates the method of operating the helicopter 1 according to the invention.

[0086] More specifically, such as Figures 2A to 2C As shown, the method includes providing Figure 1 Control logic 165, configured to pre-adjust at least one serial actuator 205 upon entering AFR mode to achieve helicopter control in the event of an IFSD (Instantaneous Frequent Discharge) of at least one first engine 192 in AFR mode, wherein the pre-adjustment of the at least one serial actuator 205 includes, as follows: Figure 2A The reduced nominal travel range 212 authorized for at least one serial actuator 205's serial actuator travel 205c in AEO mode, as shown, is shifted to, for example, Figure 2BAs shown, in AFR mode, within the reduced shift stroke range 216 authorized for the serial actuator stroke 205c of at least one serial actuator 205, as... Figure 2C The diagram illustrates the authorization to increase the travel range 214 in the event of an IFSD. Illustratively, the increased travel range 214 is adapted to provide sufficient control authority to restore operation in response to the occurrence of an IFSD.

[0087] Illustratively, pre-adjustment of at least one serial actuator 205 upon entering AFR mode may include shifting the neutral stroke position 215 of the serial actuator stroke 205c of at least one serial actuator 205 to the maximum shift neutral stroke position 227 to provide fully available control in the event of IFSD. For example, when Figure 2A The nominal travel range 212 is reduced and shifted in the first direction 201 to reach the desired position. Figure 2B When the authorized operating stroke range 235a is reached, the maximum shift authorized operating stroke range 235a will share a constraint on the first direction 201 with the maximum possible stroke range 210. Thus, the first end position 235c of the shift authorized operating stroke range 235a will be the first end position 210c of the maximum possible stroke range 210. Therefore, in this maximum shift case, Figure 2B The shift neutral stroke position 225 will be Figure 2C The maximum displacement neutral travel position shown is 227.

[0088] More specifically, such as Figure 2B and Figure 2C As shown, pre-adjustment of at least one serial actuator 205 upon entering AFR mode includes increasing the reduced shift travel range 216 of the serial actuator travel 205c to the maximum available travel range 210 to provide fully available control authority in the event of IFSD. That is, pre-adjustment of at least one serial actuator 205 may include increasing the reduced nominal travel range 212 at the actuator level to achieve the maximum available travel range 210 for controlling the helicopter 100 during IFSD in AFR mode. Then, after IFSD, the FCS 160 will be able to use the maximum available travel range 210 of the serial actuator travel 205c.

[0089] like Figure 2CAs shown, the increased stroke range 214 during an IFSD event allows at least one serial actuator 205 to be actuated to a first end position 210c and a second end position 210d of the maximum possible stroke range 210. The stroke region between the maximum shift neutral stroke position 227 and the second end position 210d can be fully utilized to perform the serial actuator stroke 205c in the second operating direction 202 to achieve a sufficient reduction in total pitch within 0.5 seconds, for example, according to the objectives and constraints of FCS160 during an IFSD event.

[0090] Illustratively, however, when IFSD occurs, the actual travel position 217 may not be at the maximum shift neutral travel position 227. In this case, the entire travel range between the actual travel position 217 and the second end position 210d can be the authorized operating travel range 235a to reduce... Figure 1 The total pitch of the main rotor is 110, or, if applicable, quickly modified. Figure 1 The blade angles of the main rotor 110 and the tail rotor 142.

[0091] It should be noted that the increased authorized operating travel range 235a can be used not only to reduce the overall pitch of the main rotor, but also for other main rotor controls to achieve safe flight conditions. Thus, the illustrative second operating direction 202 can represent any direction required to achieve such main rotor and / or tail rotor control, including, for example, increasing the periodic pitch of the main rotor.

[0092] Illustratively, when entering AFR mode, a shift in the authorized operating stroke range 235a of the serial actuator stroke 205c of at least one serial actuator 205 can be compensated for by moving the control lever in the opposite direction. This compensation can be achieved by... Figure 3A At least one parallel actuator connected to the control lever is provided, as shown.

[0093] Figure 3A At least one serial actuator is shown, illustratively implemented as a first serial actuator 315 and a second serial actuator 325, which are illustratively arranged in AEO mode. Figure 1 Upstream of at least one main rotor actuator 114. A first serial actuator 315 and a second serial actuator 325 are illustratively coupled to a control lever 301, which is connected to at least one parallel actuator 375.

[0094] like Figure 3A As shown, at least one serial actuator includes a first serial actuator 315 and a second serial actuator 325. Each of the first serial actuator 315 and the second serial actuator 325 may have a separate neutral stroke position. Illustratively, the first serial actuator 315 may be the same as the second serial actuator 325. Figure 2A The neutral stroke position 215 in the diagram shows the neutral stroke position of the first serial actuator 315 and the second serial actuator 325.

[0095] For example, the first serial actuator 315 and the second serial actuator 325 may each have two serial actuator bodies 315a, 325a and two serial actuator rods 315b, 325b. Illustratively, the first serial actuator rod 315b may, for example, be fully retracted into or fully extended from the first serial actuator body 315a. Thus, the entire length of the serial actuator body 315a can represent a first maximum usable stroke range (…). Figure 3B (315e in the text). However, similar to Figure 2A At least one serial actuator 205 in the AEO mode, the first serial actuator 315 can be authorized only with a first authorized stroke range, which is illustratively implemented as a first reduced nominal stroke range 315d of the first serial actuator stroke 315c. Similarly, the second serial actuator 325 in the AEO mode can be authorized only with a second authorized stroke range, which is illustratively implemented as a second reduced nominal stroke range 325d of the second serial actuator stroke 325c. If desired, the first reduced nominal stroke range 315d can be equal to the second reduced nominal stroke range 325d. Thus, the sum of the first reduced nominal stroke range 315d and the second reduced nominal stroke range 325d of the first serial actuator 315 and the second serial actuator 325 can provide... Figure 2A The entire reduced nominal stroke range 212 of at least one serial actuator 205 in the process.

[0096] Illustratively, at least one parallel actuator 375 may have a parallel actuator body 375a and a parallel actuator lever 375b. A parallel actuator stroke 375c can be performed within a parallel actuator stroke range 375d, allowing the current parallel actuator position 375m to be changed accordingly. Therefore, the control lever 301 can be moved to different control positions.

[0097] like Figure 3A As shown, the control lever 301 illustratively has a neutral control position 310. For example, this neutral control position 310 in AEO mode corresponds to the nominal neutral control position 311 that the control lever 301 can be held in AEO mode. Illustratively, the nominal neutral control position 311 can correspond to the trim position 390, and therefore corresponds to the "trimmed" state.

[0098] Illustratively, when entering such Figure 2B When the AFR mode shown is used to pre-adjust at least one serial actuator 205, the following may occur: Figure 3AThe displacement 301a of the control lever 301. For example, if the reduced nominal travel range of the main series actuator is shifted to a reduced shift travel range corresponding to the "generally up" portion of the maximum available travel range, the main lever (e.g., control lever 301) will be displaced 301a. Since the trim position 390 should remain substantially in the same position, the main lever needs to be lowered.

[0099] For example, pre-adjustment of at least one serial actuator 205 upon entering AFR mode may further include adjusting at least one parallel actuator 375 to compensate for a shift in the neutral stroke position 215 of the serial actuator stroke 205c of at least one serial actuator 205. More specifically, Figure 1 The control logic 165 is preferably configured to pre-adjust at least one parallel actuator 205 upon entering AFR mode, so that in AFR mode... Figure 1 When at least one first engine 192 experiences IFSD, helicopter control is achieved by modifying the current parallel actuator position 375m of at least one parallel actuator 375 to compensate for the shift of the neutral stroke position 215 of the serial actuator stroke 205c of at least one serial actuator 205. For example, Figure 3A The current parallel actuator position of 375m shown can be adapted to Figure 3B The parallel actuator position shown is 375n.

[0100] Figure 3B The arrangement in AFR mode is shown. Figure 1 The first serial actuator 315 and the second serial actuator 325 upstream of at least one main rotor actuator 114 have a shift neutral stroke position compensated by at least one parallel actuator 375.

[0101] More specifically, the pre-adjustment of the first serial actuator 315 and the second serial actuator 325 when entering AFR mode preferably includes maximizing the first authorized stroke range of the first serial actuator stroke 315c of the first serial actuator 315 from the first reduced nominal stroke range 315d authorized in AEO mode to the first maximum available stroke range 315e authorized when IFSD occurs.

[0102] like Figure 3BAs shown, the pre-adjustment of the first serial actuator 315 and the second serial actuator 325 upon entering AFR mode may further include maximizing the second authorized stroke range of the second serial actuator stroke 325c of the second serial actuator 325 from the second reduced nominal stroke range 325d authorized in AEO mode to the second maximum available stroke range 325e authorized when IFSD occurs. However, such pre-adjustment will result in different or asymmetrical configurations of the first serial actuator 315 and the second serial actuator 325, which may only be necessary when implementing the first serial actuator 315 and the second serial actuator 325 using different actuator types. Therefore, the following description is by way of example only and is not intended to limit the invention.

[0103] For example, Figure 2B The reduced shift stroke range 216 of the serial actuator stroke 205c of at least one serial actuator 205 used to control the flight operation of helicopter 100 in AFR mode before the occurrence of IFSD can be provided solely by the first maximum available stroke range 315e of the first serial actuator 315. More specifically, refer to Figure 2B Used to control IFSD before it occurs in AFR mode. Figure 1 The authorized operating stroke range 235a of the serial actuator stroke 205c of at least one serial actuator 205 for flight operation of helicopter 100 can be provided solely by the first maximum available stroke range 315e of the first serial actuator 315. Therefore, the second maximum available stroke range 325e of the second serial actuator 325 can be an unauthorized region 235b of at least one serial actuator 205 that is unavailable in AFR mode before an IFSD occurs.

[0104] Illustratively, the second serial actuator lever 325b can be fully withdrawn from the second serial actuator body 325a, causing the overall neutral stroke position of the first serial actuator 315 and the second serial actuator 325 to shift to the maximum shifted neutral stroke position, providing fully usable control authority in the event of an IFSD. However, it should be noted that this shifted overall neutral stroke position can also be provided by withdrawing only the first serial actuator lever 315b from the first serial actuator body 315a or by withdrawing both serial actuator levers from both serial actuator bodies. If desired, at least one serial actuator may include more than two serial actuators, and the shifted overall neutral stroke position can be provided by adjusting the relevant positions of one or more serial actuator levers and their corresponding serial actuator bodies.

[0105] Illustratively, Figure 1The control logic 165 can be configured to enable the serial actuator strokes (e.g., the first serial actuator stroke 315c and the second serial actuator stroke 325c of the first serial actuator 315 and the second serial actuator 325) to be actuated within a first maximum available stroke range 315e and a second maximum available stroke range 325e in response to the occurrence of IFSD in AFR mode to control the flight operation of the helicopter 100.

[0106] For example, in response to the occurrence of IFSD in AFR mode, Figure 2B The authorized operating range 235a (e.g., the first maximum available range 315e) can be extended into the previously unauthorized area 235b (e.g., the second maximum available range 325e), such that... Figure 2C The increased travel range 214 shown can provide sufficient control to resume operation in response to the occurrence of IFSD.

[0107] like Figure 3B As shown, the overall neutral stroke position of the shift of the first serial actuator stroke 315c and the second serial actuator stroke 325c of the first serial actuator 315 and the second serial actuator 325 must be compensated by at least one parallel actuator 375 by modifying the current parallel actuator position 375n of at least one parallel actuator 375.

[0108] More specifically, see reference Figure 3A and Figure 3B Trimming, i.e., modifying the current parallel actuator position 375n of at least one parallel actuator 375 to compensate for the shift, involves using at least one parallel actuator 375 to move the neutral control position 310 of the control lever 301 from the nominal neutral control position 311 in AEO mode to a shifted neutral control position 312 in AFR mode, which is different from the nominal neutral control position 311. In this way, the trim position 390 can remain substantially in the same position, while the neutral control position 310 of the control lever 301 is substantially moved to the shifted neutral control position 312.

[0109] Illustratively, the shift neutral control position 312 can be adapted to allow for increased serial actuator travel, such as the first serial actuator travel 315c and the second serial actuator travel 325c of the first serial actuator 315 and the second serial actuator travel 325c. For example, the control lever 301 in the shift neutral control position 312 can have more upward movement margin and can actuate the first serial actuator travel 315c and the second serial actuator travel 325c of the first serial actuator 315 and the second serial actuator travel 325c using the first maximum available travel range 315e and the second maximum available travel range 325e.

[0110] As an example, Figure 1 The control logic 165 can be configured to modify the force-feed feedback to the helicopter pilot via the associated force-feed characteristics of the parallel actuator 375. If needed, the control logic 165 can modify the force-feed characteristics during IFSD in AFR mode. In the case of IFSD in AFR mode, this force-feed characteristic can be mechanized by increasing the burst force and normal control force in the opposite direction to FCS control. FCS control may include controlling at least one serial actuator and / or at least one parallel actuator to achieve any suitable FCS objectives and constraints based on the current engine state, thereby maintaining safe flight.

[0111] It should be noted that the above embodiments are described merely to illustrate possible implementations and are not intended to limit the invention thereto. On the contrary, various modifications and variations of the above embodiments are possible and should therefore also be considered part of the invention.

[0112] For example, according to Figures 2A to 2C The displacement range 216 is reduced by shifting in the first operating direction 201 and reaching the end position 210c of the maximum possible range 210. However, if desired, the displacement range 216 may be reduced only in the first operating direction 201 toward the end position 210c to approach the end position 210c. Alternatively, the displacement range 216 may be reduced in the second operating direction 202 to reach or approach the end position 210d of the maximum possible range 210.

[0113] In addition, according to Figures 3A to 3B The authorized stroke ranges of the first serial actuator stroke 315c and the second serial actuator stroke 325c of the first serial actuator 315 and the second serial actuator 325 are maximized from the first reduced nominal stroke range 315d and the second reduced nominal stroke range 325d authorized in AEO mode to the first maximum available stroke range 315e and the second maximum available stroke range 325e authorized when IFSD occurs, to provide sufficient control authority for downward control of the total pitch. However, if desired, sufficient control authority can alternatively be provided in another direction required to achieve main rotor control and / or tail rotor control, such as upward control of the total pitch, increasing the periodic pitch variation of the main rotor, and applying adjustments on the roll axis and / or yaw axis.

[0114] List of reference numerals

[0115] 100 Rotorcraft

[0116] 110-bladed main rotor

[0117] 111 and 112 rotor blades

[0118] 113 Rotor Head

[0119] 114 Main rotor actuator

[0120] 115 landing gear

[0121] 120 fuselage

[0122] 122 Cockpit

[0123] 124 Rear Fuselage

[0124] 130 tail boom

[0125] 132 Horizontal stabilizer

[0126] 134 Tail beam cone

[0127] 140 Anti-torque device

[0128] 142 tail rotor

[0129] 144 Tail rotor actuator

[0130] 150 tail wing

[0131] 160 Flight Control System

[0132] 165 Control Logic

[0133] 170 Flight Control

[0134] 180 Rotorcraft Engine

[0135] 192. Engines that power the main rotor in AFR mode

[0136] 201 First operating direction of the serial actuator stroke

[0137] 202 Second operating direction of the serial actuator stroke

[0138] 205 Serial Actuator

[0139] 205c serial actuator stroke

[0140] 210 Maximum possible stroke range of the serial actuator

[0141] The maximum available travel area is divided into 210a and 210b on average.

[0142] End positions of the maximum possible travel range of the 210c and 210d serial actuators

[0143] 212 Serial Actuator Stroke Reduction Nominal Stroke Range

[0144] The reduced authorized travel area is divided into average sections 212a and 212b.

[0145] The end position of the reduced nominal stroke range of the 212c and 212d serial actuators

[0146] 214 Increased stroke range of serial actuator

[0147] 215 Neutral stroke position of the serial actuator stroke

[0148] 216. Reduced shift stroke range of the serial actuator.

[0149] 217 Actual travel position of the serial actuator stroke

[0150] 225 Serial actuator stroke shift neutral stroke position

[0151] 227. Maximum shift neutral stroke position of the serial actuator stroke.

[0152] Authorized operating stroke range of the 235a serial actuator

[0153] 235b Unauthorized Area

[0154] End positions of the authorized operating stroke range of the 235c and 235d serial actuators

[0155] The uniformly divided shift stroke region of the 235m and 235n serial actuators.

[0156] 301 control lever

[0157] Displacement of the 301a control lever

[0158] 310 Neutral control position of the control lever

[0159] 311 Nominal Neutral Control Position

[0160] 312 shift neutral control position

[0161] 315 and 325 serial actuators

[0162] 315a and 325a serial actuator main body

[0163] 315b, 325b serial actuator rod

[0164] 315c and 325c serial actuator stroke

[0165] 315d first reduction in nominal travel range

[0166] 315e First Maximum Available Travel Range

[0167] 325d Second Reduced Nominal Travel Range

[0168] 325e Second Maximum Available Travel Range

[0169] 375 parallel actuator

[0170] 375a Parallel Actuator Body

[0171] 375b parallel actuator rod

[0172] 375c parallel actuator stroke

[0173] 375d parallel actuator stroke range

[0174] Current parallel actuator positions 375m, 375n

[0175] 390 is the balancing position for overall control.

Claims

1. A rotorcraft (100) comprising: At least one main rotor (110) having at least one main rotor actuator (114) for modifying main rotor control according to the current flight status of the rotorcraft (100), wherein the main rotor actuator stroke of the at least one main rotor actuator (114) is adjusted via the serial actuator stroke (205c, 315c, 325c) of at least one serial actuator (205, 315, 325) arranged upstream of the at least one main rotor actuator (114), and wherein the at least one serial actuator (205, 315, 325) is coupled to a control lever (301), the control lever (301) being connected to at least one parallel actuator (375); At least one first engine (192) and at least one second engine for powering the at least one main rotor (110); A flight control system (160) configured to control the flight operations of the rotorcraft (100) at least in All Engine Operation (AEO) mode or in Asymmetric Flight State (AFR) mode, wherein in the All Engine Operation (AEO) mode, at least one first engine (192) and at least one second engine power at least one main rotor (110), and in the Asymmetric Flight State (AFR) mode, only the at least one first engine (192) powers at least one main rotor (110), the flight control system (160) comprising: Control logic (165) is configured to pre-adjust the at least one serial actuator (205, 315, 325) upon entering the AFR mode to enable rotorcraft control in the event of an in-flight stop (IFSD) of the at least one first engine (192) in the AFR mode, wherein the pre-adjustment of the at least one serial actuator (205, 315, 325) includes shifting a reduced nominal travel range (212) authorized for the serial actuator travel (205c) of the at least one serial actuator (205) in the AEO mode to a reduced shift travel range (216) authorized for the serial actuator travel (205c) of the at least one serial actuator (205) in the AFR mode to enable authorization of an increased travel range (214) in the event of an IFSD, the increased travel range (214) being adapted to provide sufficient control authority required to restore maneuverability in response to the occurrence of an IFSD.

2. The rotorcraft (100) according to claim 1, wherein pre-adjustment of the at least one serial actuator (205) upon entering the AFR mode comprises: The reduced shift travel range (216) of the serial actuator travel (205c) is increased to the maximum available travel range (210) to provide fully available control in the event of an IFSD.

3. The rotorcraft (100) according to claim 1, wherein pre-adjustment of the at least one serial actuator (205) upon entering the AFR mode comprises: The neutral stroke position (215) of the at least one serial actuator (205) is shifted to the maximum shifted neutral stroke position (227) to provide fully available control in the event of an IFSD; and the at least one parallel actuator (375) is adjusted to compensate for the shift of the neutral stroke position (215) of the at least one serial actuator (205).

4. The rotorcraft (100) according to claim 1, wherein the control logic is configured to set a neutral stroke position (215) of the serial actuator stroke (205c) of the at least one serial actuator (205) within the maximum available stroke range (210), wherein the neutral stroke position (215) is a center stroke position in the AEO mode, the center stroke position uniformly dividing the maximum available stroke range (210) into two maximum available stroke regions (210a, 210b) in two opposite stroke directions (201, 202), and wherein the reduced nominal stroke range (212) includes two reduced authorized stroke regions (212a, 212b) smaller than the two maximum available stroke regions (210a, 210b).

5. The rotorcraft (100) according to claim 1, wherein pre-adjustment of the at least one serial actuator (205) upon entering the AFR mode comprises: In the AFR mode, the maximum available travel range (210) is limited to the reduced shift travel range (216) prior to the occurrence of the IFSD of the at least one first engine (192) in the AFR mode, wherein the reduced shift travel range (216) is less than the maximum available travel range (210) and preferably equal to the reduced nominal travel range (212).

6. The rotorcraft (100) according to claim 4, wherein pre-adjustment of the at least one serial actuator (205) upon entering the AFR mode comprises: The neutral stroke position (215) of the serial actuator stroke (205c) of the at least one serial actuator (205) is shifted from the center stroke position in the AEO mode to the shift stroke position (225) in the AFR mode, the shift stroke position (225) being adapted to enable an increase in control authority for the main rotor control in order to achieve the required recovery maneuver in response to the occurrence of IFSD.

7. The rotorcraft (100) according to claim 5, wherein the reduced displacement stroke range (216) is uniformly divided into two displacement stroke regions (235m, 235n) by the displacement neutral stroke position (225) of the serial actuator stroke (205c) of the at least one serial actuator (205).

8. The rotorcraft (100) according to claim 6, wherein the control logic (165) is configured to: pre-adjust the at least one parallel actuator (375) upon entering the AFR mode to achieve rotorcraft control by modifying the current parallel actuator position (375m, 375n) of the at least one parallel actuator (375) to compensate for the shift of the neutral stroke position (215) of the serial actuator stroke (205c) of the at least one serial actuator (205) when an IFSD of the at least one first engine (192) occurs in the AFR mode.

9. The rotorcraft (100) according to claim 8, wherein modifying the current parallel actuator position (375m, 375n) of the at least one parallel actuator (375) to compensate for the displacement comprises: The neutral control position (310) of the control lever (301) is moved from the nominal neutral control position (311) in the AEO mode to a shift neutral control position (312) in the AFR mode, which is different from the nominal neutral control position (311), by means of the at least one parallel actuator (375). The shift neutral control position (312) is adapted to allow the serial actuator stroke (315c, 325c) of the at least one serial actuator (315, 325) with increased privileges.

10. The rotorcraft (100) of claim 1, wherein the control logic (165) is configured to provide force feedback to the pilot of the rotorcraft (100) via an associated force-sensing characteristic modification of the parallel actuator (375).

11. The rotorcraft (100) according to claim 1, wherein the at least one serial actuator (315, 325) comprises a first serial actuator (315) and a second serial actuator (315), and wherein pre-adjustment of the at least one serial actuator (315, 325) comprises: The first authorized stroke range of the first serial actuator stroke (315c) of the first serial actuator (315) is maximized from the first reduced nominal stroke range (315d) authorized in the AEO mode to the first maximum available stroke range (315e) authorized when IFSD occurs. The second authorized stroke range of the second serial actuator stroke (325c) of the second serial actuator (325) is maximized from the second reduced nominal stroke range (325d) authorized in the AEO mode to the second maximum available stroke range (325e) authorized when IFSD occurs.

12. The rotorcraft (100) according to claims 5 and 11, wherein the reduced shift travel range (216) of the serial actuator travel (205c, 315c, 325c) of the at least one serial actuator (205, 315, 325) for controlling the flight operation of the rotorcraft before the occurrence of IFSD in the AFR mode is provided only by the first maximum available travel range (315e) of the first serial actuator (315).

13. The rotorcraft (100) of claim 12, wherein the control logic is configured to enable the serial actuator strokes (205c, 315c, 325c) of the at least one serial actuator (205, 315, 325) to be actuated within a first maximum available stroke range (315e) and a second maximum available stroke range (325e) to control the flight operation of the rotorcraft (100) in response to the occurrence of IFSD in the AFR mode.

14. A flight control system (160) for a rotorcraft (100), the rotorcraft (100) comprising at least one main rotor (110), the at least one main rotor (110) having at least one main rotor actuator (114) for modifying main rotor control according to the current flight status of the rotorcraft (100), wherein the main rotor actuator stroke of the at least one main rotor actuator (114) is adjusted via the serial actuator stroke (205c, 315c, 325c) of at least one serial actuator (205, 315, 325) arranged upstream of the at least one main rotor actuator (114), wherein the at least one serial actuator (205, 315, 325) is coupled to a control lever (301), the control lever (301) being connected to at least one and The rotorcraft (100) includes an actuator (375), wherein at least one first engine (192) and at least one second engine are provided for powering the at least one main rotor (110); the flight control system (160) is configured to control the flight operations of the rotorcraft (100) at least in All Engine Operation (AEO) mode or in Asymmetric Flight State (AFR) mode, wherein in the All Engine Operation (AEO) mode, the at least one first engine (192) and the at least one second engine power the at least one main rotor (110), and in the Asymmetric Flight State (AFR) mode, only the at least one first engine (192) powers the at least one main rotor (110), and the flight control system (160) includes: Control logic (165) is configured to pre-adjust the at least one serial actuator (205, 315, 325) upon entering the AFR mode to enable rotorcraft control in the event of an in-flight stop (IFSD) of the at least one first engine (192) in the AFR mode, wherein the pre-adjustment of the at least one serial actuator (205, 315, 325) includes shifting a reduced nominal travel range (212) authorized for the serial actuator travel (205c) of the at least one serial actuator (205) in the AEO mode to a reduced shift travel range (216) authorized for the serial actuator travel (205c) of the at least one serial actuator (205) in the AFR mode to enable authorization of an increased travel range (214) in the event of an IFSD, the increased travel range (214) being adapted to provide sufficient control authority required to restore maneuverability in response to the occurrence of an IFSD.

15. A method for controlling the flight operation of a rotorcraft (100), wherein the rotorcraft (100) comprises: At least one main rotor (110) having at least one main rotor actuator (114) for modifying main rotor control according to the current flight status of the rotorcraft (100), wherein the main rotor actuator stroke of the at least one main rotor actuator (114) is adjusted via the serial actuator stroke (205c, 315c, 325c) of at least one serial actuator (205, 315, 325) arranged upstream of the at least one main rotor actuator (114), and wherein the at least one serial actuator (205, 315, 325) is coupled to a control lever (301), the control lever (301) being connected to at least one parallel actuator (375); for modifying the main rotor control according to the current flight status of the rotorcraft (100), wherein the main rotor actuator stroke of the at least one main rotor actuator (114) is adjusted via the serial actuator stroke (205c, 315c, 325c) of at least one serial actuator (205, 315, 325), and wherein the at least one serial actuator (205, 315, 325) is coupled to a control lever (301), the control lever (301) being connected to at least one parallel actuator (375); for modifying the main rotor control according to the current flight status of the rotorcraft (100), wherein the main rotor actuator (110) has at least one main rotor actuator (114) for modifying main rotor control according to the current flight status of the rotorcraft (100), wherein the main rotor actuator (114 ... At least one first engine (192) and at least one second engine powering a main rotor (110); and a flight control system (160) configured to control the flight operations of the rotorcraft (100) at least in All Engine Operation (AEO) mode or in Asymmetric Flight State (AFR) mode, wherein in the All Engine Operation (AEO) mode, the at least one first engine (192) and the at least one second engine power the at least one main rotor (110), and in the Asymmetric Flight State (AFR) mode, only the at least one first engine (192) powers the at least one main rotor (100), the method comprising: A control logic (165) is provided, configured to pre-adjust the at least one serial actuator (205, 315, 325) upon entering the AFR mode to enable rotorcraft control in the event of an in-flight stop (IFSD) of the at least one first engine (192) in the AFR mode, wherein the pre-adjustment of the at least one serial actuator (205, 315, 325) includes shifting a reduced nominal travel range (212) authorized for the serial actuator travel (205c) of the at least one serial actuator (205) in the AEO mode to a reduced shift travel range (216) authorized for the serial actuator travel (205c) of the at least one serial actuator (205) in the AFR mode to enable authorization of an increased travel range (214) in the event of an IFSD, the increased travel range (214) being adapted to provide sufficient control authority required to restore maneuverability in response to the occurrence of an IFSD.

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