Routing method and device for a twin-engine aircraft with an economical operating mode

Abstract

The present invention relates to a routing method for an aircraft (1) comprising two internal combustion engines (11) and an AEO operating mode, in which said internal combustion engines (11) jointly provide mechanical power to a rotor (2, 3) of said aircraft (1), as well as an economy operating mode in which a single internal combustion engine (11) provides mechanical power to said rotor (2, 3). Several possible routes (37, 38) for a flight between departure (31) and arrival (35) points are calculated independently, with associated operational costs, based on performance and health data of said aircraft (1), as well as meteorological and environmental data. The possible routes (37, 38) include at least one AEO route (37) using only said AEO operating mode, and at least one economy route (38) using at least part of said AEO operating mode and said economy operating mode.An optimized route is then selected from among the aforementioned possible routes (37,38) based on a comparison of operational costs. Abbreviated figure: Figure 1.

Description

Title of the invention: Routing method and device for a twin-engine aircraft with an economical operating mode

[0001] The present invention is in the field of aircraft navigation assistance systems.

[0002] The present invention relates to a routing method and device for a twin-engine aircraft having an economical operating mode.

[0003] The present invention is intended for rotary-wing aircraft equipped with at least two thermal engines and at least one rotor, the thermal engines driving the respective rotor(s) of these aircraft in rotation.

[0004] A rotary-wing aircraft has at least one rotor that can be driven in rotation by at least two internal combustion engines. The internal combustion engines are also oversized to allow the rotor to be driven by a single engine in the event of a failure of another engine. Such an aircraft has a so-called "total" or "AEO" (Ail Engines Operative) operating mode in which each internal combustion engine provides non-zero mechanical power to at least one rotor, the internal combustion engines jointly and substantially symmetrically providing the required mechanical power to at least one rotor.

[0005] In order to reduce the fuel consumption of the aircraft's internal combustion engines, an "economy" operating mode can be used, primarily during cruise flight. In this economy mode, a single internal combustion engine provides the power necessary to drive the aircraft's rotor. The other internal combustion engine(s) do not provide significant mechanical power, or even any power at all. This economy mode is therefore an asymmetrical operation of the internal combustion engines, as the engines do not operate identically.

[0006] Such an economical operating mode is advantageous but must be used judiciously. Indeed, the economical operating mode can lead to fuel savings, directly reducing flight costs and environmental impact, or improving aircraft performance by increasing range or payload. However, the economical operating mode may be limited to a specific flight envelope, firstly to ensure flight safety and secondly to ensure the propulsion system provides sufficient power for the current flight phase.

[0007] For example, the economic operating mode must be engaged with a minimum safety height relative to the ground being flown over in order to allow, in the event of failure of the motor driving the rotor, the reactivation of another motor.

[0008] According to another example, during high-speed forward flight phases, the aircraft requires significant motive power that cannot be provided by the economical operating mode without risk of specific damage to the internal combustion engine and / or the mechanical transmission chain, such damage being likely to generate additional maintenance costs.

[0009] Thus, the economical operating mode results in a reduction of the aircraft's speed, consequently increasing the flight time and, as a result, the operational cost of this flight.

[0010] In these cases, the costs induced by the increased flight time and / or by the additional maintenance costs may prove to be greater than the gain obtained by the reduction in fuel consumption or the improvement in aircraft performance.

[0011] As another example, depending on the aircraft's operating conditions, such as wind, outside temperature, or altitude, the performance of a combustion engine fluctuates. These conditions can influence the power output of the combustion engine and / or its fuel consumption. Consequently, using the economy operating mode may prove less economical under these conditions than a traditional operating mode for combustion engines in flight, or even impossible.

[0012] Finally, the introduction of new energies such as biofuels, which allow a reduction in polluting emissions but whose costs are significantly higher than fossil fuels, as well as the introduction of new carbon emission taxation schemes, brings additional variability which must be integrated into the thinking of an aircraft operator on the best use which can be made of these biofuels within the framework of this economic operating mode.

[0013] Therefore, choosing whether or not to use the economic operating mode proves to be a complex technical problem, both with regard to safety issues and economic issues for the operator.

[0014] Furthermore, establishing a route involves creating a flight plan between the departure and arrival points, a route between the departure and arrival points comprising successive waypoints, each associated with an altitude and possibly a speed. Estimated departure and arrival times, or even the estimated flight duration, may also be associated with the route. A flight plan may also include intermediate legs.

[0015] The data and parameters typically involved in establishing a route include, in particular, current and forecast weather conditions Specific distances between the departure and arrival points, as well as terrain data including the relief and any known obstacles, may be considered when establishing the flight plan. Aircraft performance information may also be taken into account.

[0016] Ecology and environmental preservation are also increasingly taken into account today in order to establish the routing of an aircraft, for example to limit its polluting emissions and / or the generation of noise, particularly near inhabited areas.

[0017] US Patent 10262545 describes a system for determining the operational parameters of a rotary-wing aircraft, including its flight plan, while optimizing its operating costs. Specifically, the system receives input data and provides, notably in flight and in real time, operational parameters of the aircraft by applying a cost model. The input data considered includes mission strategies, data from aircraft sensors such as airspeed, altitude, attitude, and angular velocity and acceleration, as well as damage data for aircraft equipment, such as engines, and maintenance costs. The operational parameters include, for example, a flight plan and a plurality of optimized parameters associated with the flight plan.These optimized parameters include, for example, the operating mode of the aircraft's engines, such as balancing the power supplied by several engines or using an operating mode in which one engine is shut down in flight to reduce fuel consumption.

[0018] Document EP 2763083 relates to a route processing method that generates several routes based on points of interest and environmental characteristics, in particular air and noise pollution generated by the aircraft, and / or economic characteristics, in particular its fuel consumption or flight time. Performance values ​​can be associated with each new route.

[0019] The present invention then relates to a method and a routing system for an aircraft comprising at least two thermal engines allowing optimal consideration of an economical operating mode of the aircraft in order to optimize the fuel consumption of the aircraft, and consequently the operational cost of the flight.

[0020] First, the present invention relates to a routing method for an aircraft equipped with at least one rotor and at least two internal combustion engines driving said at least one rotor, the aircraft having a governor configured to regulate the internal combustion engines at least according to an AEO operating mode in which each internal combustion engine provides non-zero mechanical power to said at least one rotor, the internal combustion engines jointly and substantially symmetrically providing the mechanical power required by said at least one rotor, and an economy operating mode in which at least one of the two engines Thermal power does not provide mechanical power to at least one rotor. The process comprises the following steps: - Setting parameters for a flight plan including: • a starting point for the flight plan, and • a destination point for the flight plan, - determination, using a computer, of several possible routes between the departure point and the arrival point, based on the flight plan parameters and several data points including at least aircraft performance data, aircraft health data, meteorological data, and environmental data, the determination including: • identification of at least one AEO route using only the AEO operating mode, • determination of at least one economical route using the economic operating mode and the AEO operating mode, - estimation, using the calculator, of an operational cost for each possible route, based on cost models associated with the different operating modes of the aircraft, the estimate including: • estimation of at least one AEO cost associated with said at least one AEO route, • estimation of at least one economic cost associated with said at least one economic route, - Comparison of AEO and economic costs, - selection using the calculator of a route from among the AEO and economic routes based on the comparison of AEO and economic costs.

[0021] The method according to the invention thus makes it possible to automatically select the route which minimizes the operational cost of the flight, or to optimize this operational cost in combination with one or more other criteria, and taking into account during the flight the AEO and economic operating modes as well as the conditions of use of the economic operating mode.

[0022] The method according to the invention thus advantageously assists an aircraft operator in flight preparation by allowing optimization of the operational cost of the flight, thanks to an optimized use of the aircraft's operating modes and in particular the economical operating mode.

[0023] Indeed, inappropriate use of this economical operating mode can generate more disadvantages than benefits, causing, for example, an increase in flight time not economically compensated by a decrease in fuel consumption.

[0024] To this end, several possible routes are calculated in parallel and independently The flight plan is determined based on the parameters of a flight plan, namely the departure and arrival points, as well as possibly one or more waypoints and / or one or more transit corridors. Other constraints may also apply to the flight plan, such as a maximum flight duration, an arrival time, and / or a payload to be transported, for example.

[0025] Flight corridors define areas within which the aircraft must operate, for example, with a minimum and maximum altitude for cruise flight phases. Flight corridors also allow for the definition of areas where flight is prohibited. Preferably, several AEO routes and several economic routes are calculated.

[0026] The possible routes are also calculated based on several data relating on the one hand to the aircraft and on the other hand to the flight environment.

[0027] Thus, aircraft performance data can be taken into account. This performance data makes it possible to define the aircraft's performance, such as the limitations of the authorized flight envelope, the maximum speed of the aircraft, the power available at each internal combustion engine as well as their consumption and include, for example, first performance data corresponding to the AEO operating mode of the aircraft, and second performance data corresponding to the economical operating mode of the aircraft.

[0028] This performance data includes, for example, charts or formulas for determining the aircraft's maximum speed, the power available for each internal combustion engine, and its fuel consumption, depending on operational conditions such as altitude, total aircraft mass, ambient temperature and atmospheric pressure, and the calorific value of the fuel used. This performance data may also include engine margins related to the use or damage of the internal combustion engines, as well as the aircraft's specific configuration, including the type of air intake and nozzle, to calibrate the theoretical performance to the actual performance of each internal combustion engine.

[0029] Aircraft health data may also be taken into account and includes data relating in particular to the use and damage of the internal combustion engines and a mechanical transmission chain mechanically linking said at least two internal combustion engines and said at least one rotor. Such a mechanical transmission chain may include in particular a main gearbox responsible for transmitting the mechanical power delivered by the internal combustion engines to the rotor. This health data includes, for example, one or more so-called "engine" counters associated with each internal combustion engine, each engine counter characterizing usage data related to the use or to damage to a heat engine. An engine counter can, for example, record the operating hours of the heat engine, the damage it has suffered from overheating, as well as the number of cycles of a gas generator and a free turbine of a turboshaft engine.

[0030] This health data may include at least two so-called counters "Transmission" counters, associated for example with input shafts of the main transmission, the input shafts being mechanically connected to internal combustion engines, each transmission counter characterizing usage data related to the use or damage of an input shaft. A transmission counter can, for example, count the number of input-output cycles in the economy operating mode of a freewheel in the main transmission, or the number of operating hours of an input shaft, or its duration of use in economy mode.

[0031] Meteorological data may also be taken into account and include wind and temperature data between the inclusive departure and arrival points, as well as possibly at the passage points and / or in the passage corridors. This meteorological data may also include the presence of icing or inclement weather areas between the departure and arrival points that may be incompatible with the use of the economy operating mode. This meteorological data may include measured data as well as forecasts.

[0032] Finally, environmental data can also be taken into account and includes a terrain database allowing for the consideration of topography and, where applicable, artificial obstacles to establish possible routes. The terrain database can also include inhabited areas, possibly with the associated population density, in order to take into account, if necessary, environmental nuisances, whether related to noise or air pollution, in relation to these inhabited areas.

[0033] These different data can be stored in a memory of the computer or a memory linked to the computer.

[0034] Possible routes can be established in parallel and independently by the computer, for example by applying a known route calculation algorithm. A possible route can be defined as a succession of navigation points connected by flight segments. These flight segments can be formed, for example, by straight lines, curved lines, or arcs of circles.

[0035] Next, an operational cost estimate for each possible route can be performed, based on cost models associated with the different aircraft operating modes. These cost models include an AEC cost model. associated with the AEO operating mode and an economic cost model associated with the economic operating mode. The AEO and economic cost models include, in particular, the costs related to fuel used, the hourly flight costs of the aircraft, the aircraft maintenance costs, and the cost related to the aircraft crew.

[0036] AEO and economic cost models allow for the estimation of the AEO and economic operational costs of possible routes based on the characteristics of these possible routes. For example, the operational cost of a route is estimated based on factors such as the altitude of waypoints, flight duration, and the operating mode used on each segment of these possible routes.

[0037] Comparing AEO and economic costs can thus allow the different AEO and economic routes to be ranked according to their respective AEO and economic cost values. This comparison of AEO and economic costs can also make it possible to determine the lowest AEO cost among the AEO costs and the lowest economic cost among the economic costs and / or the lowest operating cost among the AEO and economic costs.

[0038] Finally, the method according to the invention makes it possible, from the plurality of possible calculated routes, to select a route from among all the AEO and economic routes established based on the operational costs of these possible routes. The route thus selected allows for optimized integration of the economic operating mode into the flight plan, making it possible, for example, to minimize the operational cost of the flight, or to optimize this operational cost in combination with one or more other criteria. This selection step is performed automatically, via the computer, for example by applying a Monte Carlo simulation, possibly carried out in a directed and non-random manner by a Tree-structured Parsen Estimator (TPE).Depending on the situation, the selected route may or may not include at least one segment requiring the implementation of the economic operating mode.

[0039] The aircraft routing method according to the invention may further include one or more of the following features, taken alone or in combination.

[0040] According to one possibility, the comparison of AEO and economic costs can be carried out on the sole criterion of operational cost, the selected route being the possible route having the lowest operational cost among the AEO and economic costs.

[0041] Alternatively, the comparison of AEO and economic costs can be carried out on the criterion of operational cost combined with a complementary criterion.

[0042] This additional criterion can be chosen, for example, from flight duration, environmental nuisances, namely noise or air pollution, conditions meteorological factors, to avoid a storm for example, the availability of emergency landing areas.

[0043] According to another possibility compatible with the preceding ones, the economical operating mode may include a first operating mode, in which only one heat engine among said at least two heat engines operates and alone ensures the rotation of said at least one rotor, said at least one other heat engine being stopped and not supplied with fuel, and a second operating mode, in which only one heat engine among said at least two heat engines provides mechanical power to said at least one rotor, to drive it in rotation, said at least one other heat engine being started and supplied with fuel, not providing any mechanical power to said at least one rotor.

[0044] According to another possibility compatible with the preceding ones, each economical route may comprise several successive flight segments between the departure and arrival points, and the computer may determine for each segment an aircraft operating mode, either the economical operating mode or the AEO operating mode, based on the segment's characteristics, for example, its altitude, position, orientation, length, and the aforementioned data. In particular, the economical operating mode is associated with a segment whose characteristics correspond to the permitted range of that operating mode. Similarly, all flight segments of an AEO route are associated with the AEO operating mode.

[0045] In addition, the computer can determine, for each segment to which the economic operating mode is associated, information indicating the heat engine among the heat engines which must provide mechanical power to said at least one rotor.

[0046] This information can thus allow the operation of several engines to be alternated during several successive flights, or even on the same flight, in order to balance the use and / or damage to the engines and the associated input shafts of a main gearbox to which each internal combustion engine is connected. This information can be determined based on the aircraft's health data, and in particular the engine and transmission counters. Consequently, the maintenance of the internal combustion engines and the main gearbox can be optimized.

[0047] According to another possibility compatible with the preceding ones, the method may include a step of moving the aircraft between the departure and arrival points along the selected route. In this way, this flight is carried out with a minimum operational cost or optimized according to an additional criterion.

[0048] To this end, the method may also include a step of transmitting the selected route to an aircraft flight management device for the purpose of implementing this aircraft movement step.

[0049] According to another example compatible with the previous ones, the method may include a step of displaying the selected route on a viewing device, such as a screen for example, in order to allow the operator to view the selected route.

[0050] According to another example consistent with the preceding ones, the performance data may be specific to the internal combustion engines of the aircraft concerned, taking into account, in particular, the actual performance, notably in terms of power, fuel consumption, and damage, specific to each of these internal combustion engines, and even the aging of the transmission chain between each internal combustion engine and the rotor. An update of this performance data may, for example, be carried out following a maintenance operation, a monitoring operation, or a health diagnosis performed on the aircraft or, more specifically, on the internal combustion engine.

[0051] According to another example consistent with the preceding ones, the method may include a step of identifying one or more emergency landing areas on the economical route(s), in the event that the economical operating mode cannot be achieved on at least part of the selected route.

[0052] Indeed, if at least part of the selected route cannot be flown using the intended economy mode, the aircraft's fuel consumption will increase, and the aircraft may not be able to reach its destination. For example, a change in weather conditions, such as increased wind speed or a change in temperature, or a system failure on the aircraft may prevent the use of the intended economy mode.

[0053] The identification of one or more emergency landing areas then makes it possible to determine one or more emergency landing areas located near an economical route to which the aircraft can be diverted if the economical operating mode cannot be achieved on at least part of the selected route.

[0054] The present invention also relates to a computer program comprising instructions which, when the program is executed, lead to the implementation of the method according to the invention described above. The program is, for example, executed by a computer or a calculator, comprising at least one processor, at least one integrated circuit, at least one programmable system, at least one logic circuit, and a memory, these examples not limiting the scope given to the expression "computer" or "calculator".

[0055] Memory allows the computer program to be stored as well as various other information. data used by the computer program, namely aircraft performance and health data, aircraft-related cost models, meteorological data and environmental data.

[0056] The present invention also relates to a routing system for an aircraft equipped with at least one rotor and at least two internal combustion engines driving said at least one rotor, the aircraft having an economical operating mode in which at least one of said at least two internal combustion engines does not provide mechanical power to said at least one rotor. This routing system comprises at least one computer and at least one memory storing at least one database, for example, aircraft performance and health data, cost models associated with the aircraft, meteorological data, and environmental data.

[0057] This routing system is configured for the implementation of the process described above.

[0058] The routing system may be equipment not belonging to the aircraft and therefore independent of the aircraft. The routing system may then include at least one information transmitter, and the aircraft may include at least one receiving device and at least one flight management device connected to the receiving device.

[0059] The routing system can alternatively be integrated into the aircraft and thus constitute aircraft equipment. The routing system can then be connected to an aircraft flight management device. Furthermore, the selected route can be displayed on a screen of the flight management device or on a screen of the aircraft.

[0060] The routing system may include a display device, such as a screen, to display the selected route to an aircraft operator.

[0061] The present invention further relates to a routing system comprising an aircraft and such a routing system not belonging to the aircraft. The aircraft comprises at least one receiving device and at least one flight management device connected to the receiving device. The routing system comprises at least one information transmitter configured to cooperate with the aircraft's receiving device in order to transmit the flight plan characteristics and the selected route to the receiving device, which then forwards them to the aircraft's flight management device.

[0062] The present invention finally relates to an aircraft comprising a routing system.

[0063] The invention and its advantages will become apparent in more detail in the following description, with illustrative examples given by reference to the accompanying figures, which represent: - the [Fig. 1], an aircraft routing system, - [Fig. 2], a synoptic diagram of an aircraft routing process, - [Fig. 3], a diagram showing the corridors of a flight plan, and - [Fig.4], a graph representing the operational costs of possible routes according to two criteria.

[0064] Elements present in several separate figures are assigned one and the same reference.

[0065] An aircraft routing system 50 is shown in [Fig. 1]. The routing system 50 includes a computer 55 and a memory 56. Such a routing system 50 may also include a display device 59, such as a screen, as well as an information receiver 52 and an information transmitter 51. The information transmitter 51 and the information receiver 52 are, for example, respectively a receiver and a transmitter of radio waves of a wireless communication device of the routing system 50.

[0066] An aircraft 1 for which the routing system 50 is intended is a rotary-wing aircraft, as shown in [Fig. 1], comprising a fuselage 4, a landing gear 6, a propulsion system 10, and at least one rotor 2, 3 driven in rotation by the propulsion system 10. The propulsion system 10 comprises at least two internal combustion engines 11, a governor 14 regulating the operation of the internal combustion engines 11, and a main gearbox 12 arranged between the internal combustion engines 11 and the rotor(s) 2, 3. The main gearbox 12 comprises input shafts 13, each mechanically and distinctly connected to one of the internal combustion engines 11, for example, by means of a freewheel of the main gearbox 12.

[0067] By way of example, the aircraft 1 shown in [Fig.1] has two thermal engines 11 and two rotors 2,3, namely a main rotor 2 arranged above the fuselage 4 and a tail rotor 3 arranged on a tail boom of the aircraft 1.

[0068] The regulator 14 can, for example, include as many motor controllers as the drive system 10 has internal combustion engines 11. Each motor controller can control the operation of an internal combustion engine 11 and record usage data relating to that internal combustion engine 11. Such a motor controller is, for example, a controller of a system known by the acronym FADEC for the English designation "Full Authority Digital Engine Control".

[0069] In addition, the aircraft 1 may also include a display device 17, a receiving device 18 and a flight management device 15 connected to the receiving device 18.

[0070] Finally, the aircraft 1 has a memory 19 responsible for recording the usage data of the main transmission box 12.

[0071] The drive unit 10 can implement several operating modes to drive the rotors 2, 3. For example, in a so-called "total" or "AEO" operating mode, the controller 14 regulates the operation of the internal combustion engines 11 so that all the engines 11 are used and each provides power non-zero mechanical power to jointly provide the mechanical power necessary for the proper functioning of rotors 2,3 and aircraft 1.

[0072] Alternatively, the regulator 14 can regulate the operation of the internal combustion engines 11 so that a single engine 11 provides the mechanical power necessary for the proper operation of the rotors 2, 3 and the aircraft 1 in an "economy" operating mode. The other internal combustion engine(s) 11 of the propulsion system 10 then do not provide significant mechanical power to the rotors 2, 3. This economy operating mode is intended to reduce the fuel consumption of the propulsion system 10. The economy operating mode is particularly intended for cruise flight.

[0073] The economical operating mode may include a first economical operating mode, in which the heat engine(s) 11 do not supply mechanical power to the rotors 2, 3, and are stopped and not supplied with fuel. In the case where the heat engines 11 are free-turbine turboshaft engines, the rotating parts of the gas generator of this stopped turboshaft engine may nevertheless be kept rotating by means of an electric machine to facilitate and accelerate the restart of this turboshaft engine.

[0074] The economical operating mode may also include a second economical operating mode, in which the thermal engine(s) 11 not supplying mechanical power to the rotors 2,3 are started and operate at idle, thereby supplying no mechanical power to the rotors 2,3.

[0075] The economical operating mode can, when used appropriately, make it possible to obtain financial savings by reducing fuel consumption, possibly in order to increase the range of aircraft 1 or the payload for a given quantity of fuel.

[0076] However, under unsuitable conditions, the economy operating mode can be counterproductive. For example, in economy mode, the forward speed of aircraft 1 is reduced, which lengthens the flight time and can contribute to increasing the total cost of the flight. Furthermore, in economy mode, the propulsion system 10 operates asymmetrically, which can affect maintenance operations and their associated costs.

[0077] The routing system 50 according to the invention addresses this problem by assisting an aircraft operator 1 in establishing a flight plan, taking into account the AED and economic operating modes. The routing system 50 is configured to implement an aircraft routing method, a schematic diagram of which is shown in [Fig. 2].

[0078] To this end, memory 56 can store instructions and / or a computer program enabling, in particular, the execution of this routing process. The computer 55 of the routing system 50 enables the execution of this aircraft routing process.

[0079] Furthermore, the routing system 50 can be independent of aircraft 1 and can cooperate with aircraft 1 as shown in [Fig. 1].

[0080] The receiving device 18 of aircraft 1 can cooperate with the information transmitter 51 of the routing system 50 in order to receive characteristics of a flight plan, and in particular the characteristics of a route selected by the routing system 50, and then transfer them to the flight management device 15 of aircraft 1 in order to carry out a flight of aircraft 1 following this selected route.

[0081] Furthermore, the routing system 50 and the aircraft 1 can form a routing set 20.

[0082] Alternatively, the routing system 50 can be integrated into aircraft 1 and constitute equipment of that aircraft 1.

[0083] The routing process comprises the following steps.

[0084] First, during a parameter setting step 110 of the flight plan, the flight parameters of the envisaged mission are defined. This parameter setting step 110 allows a starting point 31 and an arrival point 35 to be defined. This parameter setting step 110 thus allows the flight plan to be initialized.

[0085] The departure point 31 and arrival point 35 are shown in [Fig. 1], on the display device 59, and in [Fig. 3]. In addition, corridors 32-34 are also shown in [Fig. 3] and define areas within which the aircraft 1 must operate. For example, the flight plan may include a takeoff corridor 32 starting at the departure point 31, a cruise corridor 33, and an arrival corridor 34 ending at the arrival point 35. The cruise corridor 33, for example, allows for the definition of a minimum altitude ALTMin and a maximum altitude ALTMax above the ground overflown for the cruise flight phases.

[0086] Minimum height limitations ALTMinEco and maximum height limitations ALTMaxEco relative to the ground overflown relating to the authorized flight domain in the economy operating mode are also shown in [Fig.3].

[0087] The minimum altitude ALTMin and the minimum altitude limitation ALTMinEco are determined by safety parameters to ensure sufficient altitude margin for regaining control of aircraft 1 in the event of an engine failure. These altitudes therefore vary depending on the operating mode and the number of engines in operation. Furthermore, the minimum altitude limitation ALTMinEco may include different and specific limitations for the first and second economy operating modes.

[0088] Other flight plan parameters can be defined during parameterization step 110. For example, a maximum flight duration, one or more waypoints A specific time for the passage, and / or a fixed time or time interval for departure and / or arrival, can be configured. Mission-specific parameters, such as payload or flight type (e.g., visual flight rules or instrument flight rules), can also be defined.

[0089] These flight parameters are generally set by an operator of the aircraft 1. For example, the departure point 31 and arrival point 35 can, for example, be entered directly on a map displayed on the display device 59 or by entering their coordinates via a suitable input device.

[0090] Next, the method includes a determination step 120 to determine, using the computer 55 and a known route calculation algorithm, several possible routes 37, 38 connecting the starting point 31 to the arrival point 35 based on several data points and taking into account the flight plan parameters. This calculation step 120 is performed prior to the takeoff of the aircraft 1.

[0091] The calculation step 120 includes a first calculation substep 121 for calculating, with the computer 55, one or more AEO routes 37, during which the aircraft 1 would use only the AEO operating mode.

[0092] Calculation step 120 includes a second calculation substep 122 for calculating, with the computer 55, one or more economy routes 38, during which the aircraft 1 would use at least partially both economy and AEO operating modes. In this case, as soon as the conditions for using economy operating mode, and in particular the authorized flight envelope, are met on a portion of the route, economy operating mode is selected. Otherwise, AEO operating mode is chosen.

[0093] Only one AEO route 37 and one economic route 38 are shown in [Fig. 1]. However, the determination step 120 allows for the determination of several AEO routes 37 and several economic routes 38, or even a multitude of AEO routes 37 and economic routes 38 covering the corridors 32-34.

[0094] The data enabling the determination of these possible routes 37,38 include at least data relating to the aircraft 1 and data relating to the environment. This data is, for example, stored in memory 56.

[0095] The data relating to aircraft 1 includes aircraft 1 performance data comprising first performance data corresponding to the AEO operating mode, and second performance data corresponding to the economy operating mode. Some performance data may be common to both operating modes, such as the power required in flight to reach a given speed or the calorific values ​​of the fuel used, and other data may be different and specific to each operating mode. For example, limitations of the authorized flight envelope, such as the Height and forward speed, as well as available power and fuel consumption, are specific to each operating mode. These performance data may also include engine margins specific to each internal combustion engine 11, allowing for the definition of the actual performance of each internal combustion engine 11.

[0096] These performance data can be taken into account in the form of charts determining for example the available power and fuel consumption of each thermal engine 11 as a function of the mass of the aircraft 1, its altitude, its speed and / or external atmospheric conditions.

[0097] The data relating to aircraft 1 also includes aircraft 1 health data, in particular at least two engine counters characterizing usage data for the internal combustion engines 11, and at least two transmission counters characterizing usage data for the input shafts 13, and including in particular the number of input-output cycles of the economy operating mode of the freewheel of the main transmission 12, or the number of hours of operation in economy mode of the input shafts 13 of the main transmission 12. Other health data may also be taken into account for the calculation 120 of possible routes 37,38, such as the use of electrical machines charged with supporting one or more internal combustion engines 11 in economy operating mode for example.

[0098] Environmental data includes meteorological data, including wind and temperature data, and possibly atmospheric pressure and the presence of inclement weather between the departure point 31 and arrival point 35, as well as in the passage corridors 32-34. This meteorological data can be taken into account by the performance data of the aircraft 1, for example the charts mentioned above.

[0099] The environmental data also includes environmental data such as a field database. This field database lists permanent natural or artificial obstacles, and even temporary artificial obstacles. For example, the field database includes a mountain 70 as shown in [Fig. 1].

[0100] The AEO route 37 and the economic route 38 shown in [Fig.1] are thus calculated based on these different data and flight parameters.

[0101] However, the determination step 120 may conclude that only one type of route is feasible among the AEO 37 and economic 38 routes, depending on the data and flight parameters. For example, given the distance between the departure point 31 and the arrival point 35, possibly combined with a large payload, it may be impossible to carry out the flight in AEO operating mode.

[0102] For similar reasons, calculation step 120 may conclude that no possible route exists, either for an AEO operating mode or for an economic operating mode.

[0103] The possible routes 37, 38 may comprise several successive flight segments 41 between the starting point 31 and the arrival point 35, as shown in [Fig. 1]. Each flight segment 41 corresponds to a part of the possible route 37, 38, and flight characteristics of aircraft 1 are associated with each of these flight segments 41. These flight characteristics of aircraft 1 associated with each of these flight segments 41 are elements of the flight plan, such as altitude, speed, position, heading, for example, and are defined during the determination step 120.

[0104] For AEO routes 37, the computer 55 associates the AEO operating mode with each flight segment 41. For economy routes 38, the computer 55 associates an operating mode from among the economy operating mode and the AEO operating mode with each flight segment 41, as well as optionally information indicating which of the internal combustion engines 11 should provide mechanical power to the rotors 2,3.

[0105] According to the examples of possible routes 37,38 shown in [Fig.1], the environmental data made it possible to identify the mountain 70 located between the starting point 31 and the arrival point 35. The summit 72 of the mountain 70 has an altitude greater than the maximum height ALTMax defined by the corridor 33. The altitude of the flank 71 of this mountain 70 is, however, less than this minimum height ALTMin, and greater than the maximum height limitation ALTMaxEco.

[0106] Accordingly, the AEO route 37 shown in [Fig. 1] was defined according to four flight segments 41 during calculation step 121, these four flight segments 41 being flown with aircraft 1 in AEO operating mode. A takeoff segment 42 starts at the departure point 31 and follows the departure corridor 32. Then, two cruise segments 45, 46 fly over the flank 71 and around the summit 72 while following the departure corridor 32. Finally, a landing segment 44 ends at the arrival point, following the arrival corridor 34.

[0107] The economy route 38 shown in [Fig. 1] was defined according to three flight segments 41 during calculation step 122. The takeoff segment 42 and the arrival segment 44 are identical to those of the AEO route 37 and are flown with aircraft 1 in AEO operating mode. Then, a cruise segment 48, located between the takeoff segment 42 and the arrival segment 44, bypasses the mountain 70 while respecting the cruise corridor 33 as well as the minimum altitude ALTMinEco and maximum altitude ALTMaxEco limitations. Therefore, the cruise segment 48 can be flown with aircraft 1 in economy operating mode.

[0108] In addition, the determination step 120 may include a further identification substep 125 to identify one or more emergency landing areas 36 near each economy route 38 calculated in the determination step 122. Such an emergency landing area 36 may be necessary for flight safety. A diversion point 39 located on the economy route 38 may also be defined, with the aircraft 1 to proceed to the emergency landing area 36 from this diversion point 39. For example, according to the example shown in [Fig. 1], if the aircraft 1 cannot be operated in economy mode over the entire flight segment 41, for example due to changing weather conditions, it might not have sufficient fuel to reach the destination point 35.Therefore, the flight plan includes an emergency landing area 36 and a diversion point 39 calculated during the determination sub-step 125 allowing aircraft 1 to divert from the economical route 38 from the diversion point 39 to head towards the emergency landing area 36 in order to land there before running out of fuel.

[0109] Next, the method according to the invention includes an estimation step 130 carried out using a computer 55 to estimate an operational cost of each possible route 37,38 previously determined, based on cost models associated with the different operating modes of the aircraft 1.

[0110] The cost models include an AEO cost model associated with the AED operating mode and an economic cost model associated with the economic operating mode. These cost models make it possible to determine the cost of a flight or part of a flight for each possible route 37,38 as a function of the operating mode of aircraft 1 used on each segment of that possible route 37,38. Economic data may be common to both the AEO and economic cost models, such as, for example, the cost of fuel, the cost per flight hour of aircraft 1, and / or the cost per flight hour of a pilot.

[0111] During this estimation step 130, the calculator 55 can, for example, apply the following formula to estimate the operational cost of an AEO 37 or economic 38 route:

[0112] Mission cost = fuel consumption x fuel cost + flight time x (pilot hourly cost + aircraft hourly flight cost) + engine maintenance cost + aircraft maintenance cost

[0113] Operational costs reflect the effect of each of the parameters influencing the execution of the flight. However, these operational costs can be associated with the characteristics of the flight, in particular the duration of the flight, the environmental conditions and the payload carried, in order to judge and select the best compromise on these operational costs.

[0114] This estimation step 130 includes an estimation substep 131 using the AEO cost model to estimate an AEO cost for each AEO route 37. An AEO route 37 is entirely implemented in AEO operating mode. Therefore, only the AEO cost model is needed to estimate the operating cost of an AEO route 37.

[0115] This estimation step 130 also includes an estimation substep 132 using the AEO cost model and the economic cost model to determine the economic cost for each economic route 38. An economic route 38 is operated partially in AEO mode and partially in economic mode. Therefore, both the AEO and economic cost models are required to estimate the operating cost of an economic route 38.

[0116] The method according to the invention then comprises a comparison step 140 carried out using the calculator 55 to compare the previously estimated AEO and economic costs

[0117] This comparison step 140 allows the different AEO and economic routes to be ranked according to their respective AEO and economic costs based on one or more criteria. For example, a comparison of AEO and economic costs can be carried out solely on the criterion of the value of each of the AEO and economic costs of the determined AEO and economic routes. Alternatively, a comparison of AEO and economic costs can also take into account at least one additional criterion, chosen, for example, from flight time, environmental nuisances, weather conditions, and the availability of emergency landing areas.

[0118] Finally, a selection step 150 is carried out with the calculator 55 to select a route from among the possible routes 37,38 previously determined following the comparison step 140 of AEO and economic costs.

[0119] The selected route may, for example, be chosen from among the AEO 37 and economic 38 routes based solely on the criterion of operational cost. In this case, the selected route is the possible route 37,38 with the lowest operational cost.

[0120] Alternatively, the selected route may be chosen from the AEO route(s) 37 and the economic route(s) 38 by combining the operational cost criterion with at least one additional criterion.

[0121] In all cases, the selection step 150 may include, for example, a Monte Carlo simulation to choose a finite number of routes in a first iteration. This choice is made in a directed and non-random manner by a TPE sampler, advantageously allowing the selection of possible routes 37, 38 so as to converge towards the required objective. Then, during the following iteration(s), using the results of the previous simulations, the computer 55 can then directly obtain the route with the lowest operational cost among the or the AEO 37 routes and the economic route(s) 38. The calculator 55 may optionally identify alternatively the AEO 37 route with the lowest operating cost among several AEO 37 routes and the economic route 38 with the lowest operating cost among several economic routes 38.

[0122] Alternatively, the selected route may be chosen from the AEO route(s) 37 and the economic route(s) 38 by combining the operational cost criterion with at least one of the complementary criteria.

[0123] For example, [Fig. 4] represents the operational costs of a multitude of possible routes, including AEO routes 37 and economic routes 38, on a graph where, for example, the operational cost of the possible routes 37 and 38 is on the x-axis and a supplementary criterion is on the y-axis. In the example shown, the operational costs Xi and x2 represent the best compromises between the operational cost and this supplementary criterion. In this example, a TPE sampler dedicated to multi-objective sampling can be used to identify these two operational costs xi and x2, which belong to the Pareto front of the Monte Carlo simulation results. The selection between the operational costs xi and x2 can then be made according to the criterion to be prioritized between the operational cost and this supplementary criterion, this selection preferably being carried out automatically by the computer 55 to obtain the selected route.

[0124] The method may include an optional display step 155 for displaying the selected route on the display device 59 in order to inform, for example, the operator of aircraft 1. The optional display step 155 may optionally include a display of the AEO route 37 having the lowest operating cost among several AEO routes 37 and the economical route 38 having the lowest operating cost among several economical routes 38. The operator can thus realize the differences between these two possible routes 37,38 having the optimum operating costs.

[0125] Each route 37,38 can be displayed in two dimensions, according to a top view on the display device 59.

[0126] The method may then include a step of moving the aircraft 1 170 to perform a flight between the starting point 31 and the arrival point 35 according to the selected route.

[0127] To this end, the method may also include a step 160 of transmitting the flight plan, and in particular the selected route, to a flight management device 15 of the aircraft 1 for the purpose of carrying out the movement step 170. The transmission of the flight plan characteristics is carried out using the information transmitter 51 which cooperates with the receiving device 18 of the aircraft 1. The receiving device 18 thus receives the flight plan characteristics, and in particular the characteristics of the selected route, and then transfers them to the device flight management 15 of aircraft 1 with a view to carrying out a flight of aircraft 1 following this selected route.

[0128] Naturally, the present invention is subject to numerous variations in its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible embodiments. It is, of course, conceivable to replace a described means with an equivalent means without departing from the scope of the present invention and the claims.

Claims

1. Demands Routing method for an aircraft (1) equipped with at least one rotor (2,3) and at least two internal combustion engines (11) rotating said at least one rotor (2,3), said aircraft (1) having a regulator configured to regulate said internal combustion engines (11) at least according to an operating mode called "AEO", corresponding to the English designation "all engines running", in which said internal combustion engines (11) each provide non-zero mechanical power to said at least one rotor (2,3) and jointly a required mechanical power to said at least one rotor (2,3), and an economical operating mode in which at least one of said internal combustion engines (11) does not provide mechanical power to said at least one rotor (2,3), characterized in that said method comprises the following steps: - setting (110) parameters of a flight plan including: • a starting point (31) of said flight plan, and • an arrival point (35) of said flight plan, and - determination (120) using a computer (55) of several possible routes (37,38) between said starting point (31) and said arrival point (35), based on said parameters of said flight plan and several data including at least performance data of said aircraft (1), health data of said aircraft (1), meteorological data, and environmental data, said determination (120) including: • determination (121) of at least one AEO route (37) using only said AEO operating mode, • determination (122) of at least one economic route (38) using said economic operating mode and said AEO operating mode, - estimation (130) using a calculator (55) of an operational cost of each possible route (37,38) based on cost models associated with the different operating modes of said aircraft (1), said estimation (130) comprising: • estimation (131) of at least one AEO cost associated respectively with said at least one AEO route, • estimation (132) of at least one economic cost associated respectively with said at least one economic route, - comparison (140) of said AEO and economic costs, - selection (150) using said calculator (55) of a route from said AEO (37) and economic (38) routes according to said comparison of said AEO and economic costs, - transmission (160) of said selected route to a flight management device (15) of said aircraft (1).

2. A method according to claim 1, wherein said method comprises a displacement (170) of said aircraft (1) between said starting point (31) and arrival point (33) along said selected route.

3. A method according to any one of claims 1 to 2, wherein said performance data of said aircraft (1) comprise: • first performance data corresponding to said AEO operating mode of said aircraft (1), and • second performance data corresponding to said economic operating mode of said aircraft (1), said health data of said aircraft (1) comprise: • an engine counter associated with each internal combustion engine (11), said engine counter recording at least one usage data point of said internal combustion engine (11), and • at least two transmission counters associated respectively with input shafts (13) of a main transmission (12) arranged between said internal combustion engines (11) and said at least one rotor (2, 3), said input shafts (13) being mechanically connected respectively to said internal combustion engines (11), each transmission counter recording at least one usage data from one of said input trees (13), said meteorological data include wind and temperature data between said starting point (31) and arrival point (35), and said environmental data include a field database.

4. A method according to any one of claims 1 to 3, wherein said at least one economic route comprises several successive flight segments between said starting point (51) and arrival point (55), and said computer (55) determines for each segment an operating mode of said aircraft (1) from said economic operating mode and said associated AEO operating mode as a function of characteristics of said segment and said data.

5. Method according to claim 4, wherein said computer (55) determines for each segment for which said economic operating mode is associated information indicating said heat engine (11) among said heat engines (11) supplying said mechanical power to said at least one rotor (2,3).

6. A method according to any one of claims 1 to 5, wherein said economical operating mode comprises a first operating mode in which only one heat engine (11) among said heat engines (11) operates and alone drives said at least one rotor (2,3) into rotation, said at least one other heat engine (11) being stopped and not supplied with fuel and a second operating mode in which only one heat engine (11) among said heat engines (11) supplies mechanical power to said at least one rotor (2,3) to drive it into rotation, said at least one other heat engine (11) being started and supplied with fuel, not supplying any mechanical power to said at least one rotor (2,3).

7. A method according to any one of claims 1 to 5, wherein said selection (150) of a route from among said AEO (37) and economic (38) routes is carried out solely on the criterion of said operational cost, the selected route being the possible route (37,38) having said lowest AEO or economic cost.

8. A method according to any one of claims 1 to 5, wherein said selection (150) of a route from said AEO (37) and economic (38) routes is carried out on the criterion of operating cost combined with at least one additional criterion.

9. Method according to claim 8, wherein said at least one additional criterion is chosen from flight duration, environmental nuisances, weather conditions, availability of emergency landing areas.

10. A method according to any one of claims 1 to 9, wherein said method comprises a step of identifying one or more emergency landing areas (36) on said at least one economical route (38), in the event that said economical operating mode cannot be achieved on at least a part of said selected route.

11. A method according to any one of claims 1 to 10, wherein said method includes a display step (155) for displaying said selected route on a display device (59).

12. A computer program comprising instructions which, when said program is executed, lead to the implementation of the method according to any one of claims 1 to 11.

13. Aircraft (1) routing system (50) equipped with at least one rotor (2,3) and at least two internal combustion engines (11) rotating said at least one rotor (2,3), said aircraft (1) having an economical operating mode in which at least one of said internal combustion engines (11) does not provide mechanical power to said at least one rotor (2,3), said system (50) comprising: - at least one computer (55), and - at least one memory (56) storing at least one database, characterized in that said routing system (50) is configured to implement the aircraft routing method according to any one of claims 1 to 10.

14. Routing assembly (20) comprising an aircraft (1) and a routing system (50) according to claim 13, characterized in that said aircraft (1) comprises at least one device receiving device (18) and at least one flight management device (15) linked to said receiving device (18), said routing system (50) includes at least one information transmitter (51) configured to cooperate with said receiving device (18) of said aircraft (1) in order to transmit characteristics of said flight plan and said selected route to said receiving device (18) which transfers them to said flight management device (15).

15. Aircraft (1), characterized in that said aircraft (1) comprises a routing system (50) according to claim 13.

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