Method and a device for assisting the piloting of a hybrid rotorcraft having a lift rotor and at least one propulsion rotor generating thrust

Abstract

A method of facilitating the piloting of a hybrid rotorcraft that comprises a lift rotor and at least one propulsion rotor together with at least one engine operating in compliance with at least one rating. For at least one rating, onboard calculator determines a first power margin of the power plant that is available for the lift rotor and at least one second power margin that is available for said at least one propulsion rotor. A single indicator displays a line together with a first index pointing to said line to illustrate a current operating point of the lift rotor, and a second index pointing to said line to illustrate a current operating point of said at least one propulsion rotor. For each monitored rating, a first symbol is spaced apart from the first index by a first distance illustrating the first power margin. A second symbol is spaced apart from the second index by a second distance illustrating the second power margin.

Claims

1. A method of facilitating the piloting of a hybrid rotorcraft, the hybrid rotorcraft having a lift rotor with a plurality of first blades having a first pitch that is variable at least for contributing to providing the hybrid rotorcraft with lift, the hybrid rotorcraft having a propulsion system having at least one propulsion rotor provided with a plurality of second blades having a second pitch that is variable for contributing at least to causing the hybrid rotorcraft to advance, the hybrid rotorcraft having a power plant provided with at least one engine operating at at least one rating for rotating the lift rotor and each propulsion rotor of the at least one propulsion rotor, the at least one rating being associated with at least one limit for at least one monitoring parameter of the power plant, wherein the method comprises the steps of: for at least one monitored rating of at least one rating, using onboard calculator to determine a first power margin of the power plant that is available for the lift rotor, and at least one second power margin of the power plant that is available for the at least one propulsion rotor; displaying a line on a single indicator to separate a first side and a second side of the indicator; displaying, on the single indicator, a first index pointing to the line to illustrate a current operating point for the lift rotor, and displaying, on the single indicator, a second index pointing to the line to illustrate a second current operating point for the at least one propulsion rotor; and for each monitored rating, displaying, under the control of the onboard calculator, a first symbol spaced apart from the first index by a first distance illustrating the first power margin for the monitored rating, and displaying, under the control of the onboard calculator, a second symbol comprising at least one pointer spaced apart from the second index by a second distance illustrating at least one second power margin for the monitored rating.

2. The method according to claim 1, wherein the first index and the first symbol associated with each monitored rating are positioned on the first side, the second index and the second symbol associated with each monitored rating being positioned on the second side.

3. The method according to claim 1, wherein the step of determining a first power margin comprises the following steps: determining an engine torque margin for each engine of the at least one engine; determining an intermediate torque margin between a rotor torque limit of a rotor shaft rotating the lift rotor and a current torque exerted on the rotor shaft; determining a minimum rotor torque margin corresponding to the minimum from among the engine torque margin and the intermediate torque margin; and determining the first power margin equal to the minimum rotor torque margin multiplied by the speed of rotation of an engine outlet shaft driven in rotation by the engine that presents the smallest torque margin.

4. The method according to claim 3, wherein the step of determining an engine torque margin for each engine comprises the following steps: determining a monitoring margin for each monitoring parameter of the engine between a current value of the monitoring parameter and a predetermined limit for the monitoring parameter in the monitored rating; and for each monitoring parameter that is not the engine torque, transforming the monitoring margin into a margin expressed in engine torque units, the engine torque margin being the smallest of the margins expressed in engine torque units.

5. The method according to claim 3, wherein the step of determining at least one second power margin comprises the following steps: determining an engine torque margin for the or each engine; determining, for each propulsion rotor, a calculation torque margin between a propulsion rotor torque limit of a propulsion rotor shaft rotating the propulsion rotor and a current torque exerted on the propulsion rotor shaft; determining a minimum propulsion rotor torque margin corresponding to the minimum from among the engine torque margin and each calculation torque margin; and determining a single second power margin equal to the minimum propulsion rotor torque margin multiplied by the speed of rotation of an engine outlet shaft driven in rotation by the engine presenting the smallest torque margin.

6. The method according to claim 3, wherein the step of determining at least one second power margin comprises the following steps: determining an engine torque margin for each engine of the at least one engine; determining, for each propulsion rotor, a calculation torque margin between a propulsion rotor torque limit of a propulsion rotor shaft rotating the propulsion rotor and a current torque exerted on the propulsion rotor shaft; determining, for each propulsion rotor, a minimum propulsion rotor torque margin corresponding to the minimum from among the engine torque margin and the calculation torque margin associated with the propulsion rotor; and determining a second power margin for each propulsion rotor equal to the minimum propulsion rotor torque margin of the propulsion rotor multiplied by the speed of rotation of an engine outlet shaft rotated by the engine presenting the smallest torque margin.

7. The method according to claim 1, wherein the first index and the second index are stationary relative to the line, the first symbol and the second symbol being movable relative to the line.

8. The method according to claim 7, wherein the first index and the second index are in alignment, the first index and the second index being arranged symmetrically about the line.

9. The method according to claim 1, wherein the first index and the second index are movable relative to the line, the first symbol and the second symbol being stationary relative to the line.

10. The method according to claim 9, wherein for a given monitored rating, the first symbol and the second symbol are in alignment, the first symbol and the second symbol being arranged symmetrically about the line.

11. The method according to claim 1, wherein the at least one propulsion rotor comprises a plurality of propulsion rotors, and the second power margin(s) includes one propulsion rotor margin for each propulsion rotor, the second index comprises one pointer for each propulsion rotor, which pointer is spaced apart from the second symbol by a second distance illustrating the corresponding second power margin.

12. The method according to claim 1, wherein the first symbol and the second symbol are identical in shape.

13. The method according to claim 1, wherein the first symbol and the second symbol are at least temporarily asymmetrically arranged relative to the line.

14. A hybrid rotorcraft, the hybrid rotorcraft having a lift rotor with a plurality of first blades having a first pitch that is variable at least for contributing to providing the hybrid rotorcraft with lift, the hybrid rotorcraft having a propulsion system having at least one propulsion roto provided with a plurality of second blades having a second pitch that is variable for contributing at least to causing the hybrid rotorcraft to advance, the hybrid rotorcraft having a power plant provided with at least one engine operating at at least one rating for rotating the lift rotor and the or each propulsion rotor, the rating(s) being associated with at least one limit for at least one monitoring parameter of the power plant, wherein the hybrid rotorcraft includes onboard calculator and an indicator that are configured to apply the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its advantages appear in greater detail from the following description of examples given by way of illustration and with reference to the accompanying figures, in which:

(2) FIG. 1 is an isometric view of a hybrid rotorcraft;

(3) FIG. 2 is a diagram showing a device for assisting the piloting of such a hybrid rotorcraft; and

(4) FIGS. 3 to 5 show the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) Elements present in more than one of the figures are given the same references in each of them.

(6) FIG. 1 shows a hybrid rotorcraft 1 of the invention provided with a main rotor (MR) constituting a lift rotor 5 having a plurality of first blades 6 presenting a first collective pitch that is variable. The hybrid rotorcraft 1 is also provided with a propulsion system 7. The propulsion system 7 includes at least one propulsion rotor 8, e.g. of the propeller type, comprising a plurality of second blades 9 having a second collective pitch that is variable.

(7) By way of example, the hybrid rotorcraft 1 has a fuselage 2 carrying at least one rotary wing, the rotary wing including the lift rotor carrying the first blades 6. Furthermore, the hybrid rotorcraft includes a first propulsion rotor and a second propulsion rotor. By way of example, the two propulsion rotors 8 are lateral rotors, possibly arranged at each of the outer ends of a wing 3.

(8) In order to drive rotation of the lift rotor and of each propulsion rotor 8, the aircraft includes a power plant having at least one engine 10, e.g. of the turboshaft type. Furthermore, the power plant may include an, interconnection system 11 comprising at least one main power transmission gearbox (MGB), at least one transmission shaft, . . . .

(9) The speeds of rotation of the outlet shafts of the engines 10, of the propulsion rotors 8, of the lift rotor 5, and of the mechanical interconnection system 11 may optionally be proportional to one another, with the proportionality ratio being variable or constant regardless of the flight configuration of the hybrid helicopter under normal operating conditions of the integrated drive train.

(10) In addition, each engine 10 operates in compliance with an operating envelope that includes one or more ratings, e.g. comprising a takeoff rating defining a maximum takeoff power TOP, a maximum continuous rating defining a maximum continuous power MCP, a transient rating defining a maximum transient power MTP, a first contingency rating defining a supercontingency power 30 sec OEI, a second contingency rating defining a second contingency power 2 min OEI, and/or a third contingency rating defining a continuous contingency power cont-OEI.

(11) In order to control the hybrid rotorcraft, the pilot may have a thrust control serving to modify the mean pitch of the second blades of the propulsion rotors 8.

(12) More precisely, the thrust control acts identically on the pitch of the second blades 9 in order to obtain collective variation of the pitch of the second blades. For example, the pilot may request an increase of 5 degrees in the mean pitch of all of the blades of the propulsion rotors in order to increase the resultant thrust generated in particular by the first propulsion rotor and by the second propulsion rotor, the mean pitch of the blades of the first and second propulsion rotors possibly being equal to half the sum of the pitches of the first and second propulsion rotors 8.

(13) The thrust control may comprise a thrust control lever (TCL) that acts on a drive train connected to the second blades of the propulsion rotors.

(14) As an alternative, or in addition, the thrust control may optionally be provided with a button suitable for controlling at least one actuator arranged on said drive train. This button advantageously has three positions, namely a first position for increasing the mean pitch of the blades of the propulsion rotors, and thus collectively varying the pitch of the second blades 9 by the same amount, a second position for decreasing the collective pitch of the second blades 9, and finally a third position for leaving the pitch of the second blades 9 unmodified.

(15) In order to control the yaw attitude of the hybrid rotorcraft, the pilot may have a yaw control device provided with Yaw control means, conventionally pedals, for giving rise to variation in the pitch of the second blades 9 that is not collective but instead different or even differential.

(16) Finally, the hybrid rotorcraft 1 has conventional control means for controlling the pitch of the first blades 6 of the lift rotor 5 both collectively and cyclically.

(17) In order to avoid risking maneuvers that might endanger the aircraft, the aircraft is provided with a piloting assistance device.

(18) FIG. 2 shows such a piloting assistance device 15 in accordance with the invention.

(19) The piloting assistance device 15 comprises onboard calculator 20.

(20) The onboard calculator 20 may comprise one or more computers communicating with one another.

(21) Furthermore, the piloting assistance device 15 includes an indicator 60 controlled by the onboard calculator and a plurality of sensors 30 connected to the onboard calculator.

(22) In the example shown, the onboard calculator 20 comprises a central computer 22 and a conventional engine computer 21 for each engine.

(23) By way of example, such an engine computer is of the type known under the acronym FADEC (for full-authority digital engine control). Each engine computer is then connected to at least one engine sensor. By way of example, such an engine computer may regulate an electric motor or it may regulate a fuel-burning engine by controlling its fuel metering unit. For each operating rating, such an engine computer can, also deliver the power margin available from the engine (or motor) relative to the maximum power of that rating, and it can deliver a current value for the power being consumed by the engine (or motor).

(24) In another example, single calculator may be used.

(25) By way of example, each calculator may comprise at least one processor 23 and at least one memory 24, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not being limiting on the scope to be given to the term “calculator” or “calculator means”.

(26) Under such circumstances, the onboard calculator 20 is connected by wired or wireless connections to sensors 31 for measuring monitoring parameters of each engine 10. For example, each engine computer 21 is connected a set of engine sensors. The monitoring parameters of an engine may include at least one parameter selected from a list comprising: the speed of rotation Ng of a gas generator of each engine; the torque TQ of each engine; and a gas temperature, e.g. the temperature of the gas at the inlet to a low pressure free turbine of each engine, written T45.

(27) Under such circumstances, for each engine, the piloting assistance device 15 possesses a sensor 32 for measuring the speed of rotation Ng of the engine, a torque meter 34 for measuring the torque TQ developed by the engine on an engine outlet shaft 100 driven by the engine, and a sensor 33 for measuring the engine gas temperature T45. An engine speed of rotation sensor 40 may serve to measure the speed of rotation of the engine outlet shaft.

(28) Furthermore, the piloting assistance device 15 may include a sensor 35 for sensing outside pressure P0 and a sensor 36 for sensing outside temperature T0, which sensors are connected to the onboard calculator 20, and for example to the central computer 22.

(29) Furthermore, the onboard calculator 20, for example the central computer, may be connected to a propulsion rotor torque meter 37 for each propulsion rotor. Each propulsion rotor torque meter 37 serves to measure torque on a propulsion rotor shaft 90 driving the propulsion rotor in rotation about its axis of rotation AXH. A sensor for sensing the speed of rotation of the propulsion rotor 41 may serve to measure the speed of the rotation of the propulsion rotor shaft.

(30) The onboard calculator 20, and for example the central computer, may be connected to a rotor torque meter 38. The rotor torque meter may measure torque on a rotor shaft 500 driving rotation of the lift rotor 5 about its axis of rotation AXR. A rotor speed of rotation sensor 42 can measure the speed of rotation of the rotor shaft 500.

(31) The onboard calculator 20, and for example the central computer, may be connected to a mean pitch sensor measuring the current mean pitch of the blades of the propulsion rotor blades and/or to an air speed sensor suitable for measuring the true air speed of the hybrid helicopter and/or to a rotary speed sensor for measuring the speed of rotation of the propulsion rotors and/or to a rotary speed sensor for measuring the speed of rotation of the life rotor and/or to a pitch sensor for measuring the collective pitch of the blades of the lift rotor.

(32) In the method of the invention performed by the device 10, for at least one operating rating of the engine referred to for convenience as the “monitored” rating, the onboard calculator 20 determines a first power margin MRGPROT relating to the maximum power MAXP that can be developed in this rating.

(33) For example, the onboard calculator determines, for each engine, an engine torque margin that corresponds to equal to the power margin of the engine converted into units of torque.

(34) Optionally, each rating specifies a stored limit that is not to be exceeded for each monitoring parameter. Under such circumstances, the engine computer of an engine determines the “monitoring” margin between a current value of each monitoring parameter and its limit. Where appropriate, the monitoring margin is converted by the engine computer into a comparison margin expressed in engine torque units by applying stored relationships or the equivalent.

(35) For example, the engine computer determines a T45 temperature margin that is converted into a margin expressed in torque units, an Ng speed of rotation margin that is converted into another margin expressed in torque units, and an engine torque margin which is naturally expressed in torque units. The smallest of the margins expressed in torque units represents the torque margin of the engine in question.

(36) In addition, the onboard calculator 20 may calculate an intermediate torque margin between a stored limit for the rotor torque of the rotor shaft 500 and the current torque exerted on said rotor shaft 500.

(37) The onboard calculator 20 can then determine a minimum rotor torque margin, which is equal to the minimum from among each of the engine torque margins and the intermediate torque margin.

(38) Independently of this aspect, the onboard calculator 20 determines one or more second power margins for the power plant.

(39) The onboard calculator then determines, for each propulsion rotor, a “calculation” torque margin between a stored propulsion rotor torque limit for a propulsion rotor shaft 90 driving rotation of the propulsion rotor and a current torque exerted on that propulsion rotor shaft 90 as measured by a propulsion rotor torque meter 37.

(40) In, a first alternative, a single second power margin is calculated.

(41) Under such circumstances, the onboard calculator determines a minimum propulsion rotor torque margin corresponding to equal to the minimum among each of the engine torque margins and each of the calculation torque margins. The onboard calculator then determines a single second power margin that is equal to the minimum propulsion rotor torque margin multiplied by the speed of rotation of an engine outlet shaft 100 driven in rotation by the engine that presents the smallest torque margin.

(42) In a second alternative, a second power margin is calculated for each propulsion rotor.

(43) Under such circumstances, the onboard calculator determines, for each propulsion rotor, a minimum propulsion rotor torque margin corresponding to equal to the minimum from each of the engine torque margins and the calculation torque margin of this propulsion rotor. The onboard calculator then determines a second power margin for each propulsion rotor equal to the minimum propulsion rotor torque margin of that propulsion rotor multiplied by the speed of rotation of an engine outlet shaft driven in rotation, by the engine presenting the smallest torque margin.

(44) Whatever the alternative, the onboard calculator, and for example the central computer, calculates for each monitored rating a first power margin. MRGPROT that represents a power reserve of the power plant that can be used by the lift rotor. In addition, the onboard calculator, and for example the central computer, calculates for each monitored rating at least one second power margin MRGPHEL that represents a power margin of the power plant that can be used by at least one propulsion rotor.

(45) Under such circumstances, the onboard calculator, and for example the central computer, transmits at least one signal to an indicator 60 to generate and display various symbols on a screen 61 of the indicator.

(46) Optionally, the onboard calculator may cause two parallel vertical bars 62 to be displayed so as to define horizontally a display zone 63.

(47) Furthermore, the onboard calculator may cause a line 65 to be generated and displayed, in the display zone 63, if any, to separate a first side 64 of the indicator 60 from a second side 66. By way of example, the information concerning the lift or main rotor (MR) may be displayed on the first side 64 while the information concerning the propulsion rotors and the thrust control lever (TCL) may be displayed on the second side 66.

(48) The onboard calculator may cause a first index 70 to be generated and displayed in the display zone 63, if any, on the first side 64. This first index 70 points to a line 65 in order to illustrate the current operating point of the lift rotor, and for example the power being consumed by the lift rotor.

(49) Optionally, the onboard calculator calculates the power being consumed by the lift rotor by multiplying the rotor torque exerted on the rotor shaft 500 by the speed of rotation of the rotor shaft, as measured respectively the rotor torque meter 38 and by the rotor rotary speed sensor. Alternatively, the onboard calculator calculates the power being consumed by the lift rotor by using stored polar plots and parameters of the lift rotor, such as the radius of the first blades, the tip speed of the blades of the lift rotor, the air speed of the aircraft, the pitch of the first blades, . . . .

(50) The onboard calculator may cause a second index 75 to be generated and displayed, in the display zone 63, if any, on the second side 66. This second index 75 points to the line 65 in order to illustrate a current operating point of the propulsion rotor(s), and for example the power being consumed by the propulsion rotor(s).

(51) Optionally, the onboard calculator may calculate the power consumed by each propulsion rotor by multiplying the propulsion, rotor torque exerted on the propulsion rotor shaft 90 by the speed of rotation of the propulsion rotor shaft 90, as measured respectively by the propulsion rotor torque meter 37 and by the propulsion rotor rotary speed sensor 41. Alternatively, the onboard calculator calculates the power consumed by each propulsion rotor by using stored polar plots and propulsion rotor parameters such as the radius of the second blades, the tip speed of the blades of the propulsion rotor, the air speed of the aircraft, the pitch of the second blades, . . . .

(52) For each monitored rating, the onboard calculator may cause a first symbol 80 to be generated and displayed in the first side 64 and spaced apart from the first index 70 by a first distance D1 illustrating the first power margin at this monitored rating. In the example shown, the onboard calculator may generate a first symbol 81 for illustrating the first power margin for the transient rating MTP and a first symbol 82 for illustrating the first power margin for the extended power rating and a first symbol for illustrating the first power margin for the maximum continuous rating.

(53) For each monitored rating, the onboard calculator may cause a second symbol 85 to be generated and displayed in the second side 66 and spaced apart from the second index 75 by a second distance D2 illustrating at least one second power margin for this monitored rating. In the example shown, the onboard calculator may generate a second symbol 86 for illustrating the smallest second power margin for the transient rating MTP and a second symbol 87 for illustrating the smallest second power margin for the extended power rating and a second symbol 88 for illustrating the smallest second power margin for the maximum continuous rating.

(54) In the embodiment shown in FIG. 2, the onboard calculator may position the first index 70 and then for each monitored rating it may shift the first symbol 80 relative to the first index 70 as a function of how the first power margin varies. Likewise, the onboard calculator may position the second index 75, and then for each monitored rating it may shift the second symbol relative to the second index 75 as a function of how the smallest second power margin varies.

(55) The first index 70 and the second index 75 are stationary relative to the line 65. However, the first symbols 80 and the second symbols 85 are movable relative to the line 65.

(56) Optionally, the first index 70 and the second index 75 are in alignment and/or arranged symmetrically about the line 65.

(57) By way of example, and with reference to FIG. 3, when the Pilot changes the Pitch of the second blades of the propulsion rotors, the various margins become smaller. The first symbols and the second symbols move in the same direction.

(58) FIG. 4 shows a situation in which the pilot no longer has any power margin for the propulsion rotors, but still has some power margin, for the lift rotor.

(59) In the embodiment of FIG. 5, the first index 70 and the second index 75 are movable relative to the line 65. However the first symbols 80 and the second symbols 85 are stationary relative to the line 65.

(60) Optionally, for each monitored rating, the first symbol 80 and the second symbol 85 are in alignment and/or are arranged symmetrically about the line 65.

(61) In the variant of FIG. 6, the onboard calculator distinguish between the propulsion rotors.

(62) Under such circumstances, the onboard calculator calculates a propulsion rotor margin for each propulsion rotor.

(63) Furthermore, the second index 75 presents a respective pointer 76, 77 for each propulsion rotor, each pointer 76, 77 being spaced apart from the second symbol by a distance that illustrates the margin, for the corresponding propulsion rotor.

(64) Naturally, the present invention may be subjected to numerous variations as to its implementation. Although several implementations are described, it will readily be understood that it is not conceivable to identify exhaustively all possible implementations. It is naturally possible to envisage replacing any of the means described by equivalent means without going beyond the ambit of the present invention.