METHOD AND DEVICE FOR ROUTING A TWIN-ENGINE AIRCRAFT WITH ECONOMIC OPERATING MODE

Description

[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 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 " for the English designation "All Engines Operative" in which each heat engine provides non-zero mechanical power to at least one rotor, the heat engines jointly and substantially symmetrically providing the mechanical power required to at least one rotor.

[0005] To reduce fuel consumption by the aircraft's internal combustion engines, an "economy" operating mode can be used, primarily during cruise flight. In this economy mode, only one internal combustion engine provides the power needed to rotate 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 therefore results in asymmetrical operation of the internal combustion engines, as they do not operate identically.

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

[0007] For example, the economy 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 that flight.

[0010] In these cases, the costs incurred by increased flight time and / or additional maintenance costs may prove to be greater than the gain obtained from reduced fuel consumption or improved aircraft performance.

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

[0012] Finally, the introduction of new energy sources such as biofuels, which reduce polluting emissions but are significantly more expensive than fossil fuels, and the introduction of new carbon emission taxation schemes bring additional variability that must be integrated into an aircraft operator's thinking about the best use that can be made of these biofuels within 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 security 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 with an associated altitude and sometimes even a speed. Estimated departure and arrival times, or the estimated flight duration, may also be associated with the route. A flight plan may also include intermediate stops.

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

[0016] Ecology and environmental preservation are also increasingly taken into account today when establishing the routing of an aircraft, for example to limit its polluting emissions and / or noise generation, 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 operational parameters for the aircraft, including in-flight and real-time data, 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 data on aircraft equipment damage, such as engine damage, 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, for example by balancing the power supplied by several engines or by using an operating mode in which one engine is shut down in flight in order to reduce fuel consumption.

[0018] Document EP 2763083 concerns a route processing method that generates multiple routes based on points of interest and environmental characteristics, particularly air and noise pollution generated by the aircraft, and / or economic factors, particularly fuel consumption or flight duration. Performance values ​​can be associated with each new route.

[0019] The documents US 2020 / 0362753, US 2022 / 0122468 and US 9193442 are also known.

[0020] 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.

[0021] 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 in rotation, the aircraft having a regulator configured to regulate the internal combustion engines at least according to a first operating mode called " AEO "in which each heat engine supplies non-zero mechanical power to at least one rotor, the heat engines jointly and substantially symmetrically supplying the required mechanical power to at least one rotor, and a second operating mode, called "economical", in which at least one of the two heat engines does not supply mechanical power to at least one rotor. The process comprises the following steps: setting parameters of a flight plan including: ∘ a departure point of the flight plan, and ∘ an arrival point of 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 including at least aircraft performance data, aircraft health data, meteorological data, and environmental data, the determination including: ∘ determination of at least a first route called " AEO using only the first operating mode AEO, • Determination of at least one second so-called "economic" route using the second economic operating mode and the first AEO operating mode; estimation, using the calculator, of an operational cost for each possible route, based on cost models associated with the different aircraft operating modes; the estimation including: • Estimation of at least one first so-called " AEO associated respectively with said at least one first route, ∘ estimation of at least one second cost called "economic" associated respectively with said at least one second route, comparison of the first and second costs, selection using the calculator of a route from among the first and second routes according to the comparison of the first and second costs.

[0022] 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 first and second modes of operation as well as the conditions of use of the second economical operating mode.

[0023] 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 second economical operating mode.

[0024] Indeed, inappropriate use of this second economic 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.

[0025] To this end, several possible routes are calculated in parallel and independently 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.

[0026] Flight paths define areas within which the aircraft must operate, for example, with a minimum and maximum altitude for cruise phases. Flight paths also allow for the definition of no-fly zones. Preferably, several first and second routes are calculated.

[0027] 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.

[0028] Thus, aircraft performance data can be taken into account. This performance data allows the definition of aircraft performance, such as the limitations of the authorized flight envelope, the maximum speed of the aircraft, the power available at the level of each internal combustion engine as well as their consumption and includes, for example, first performance data corresponding to the first AEO operating mode of the aircraft, and second performance data corresponding to the second economic operating mode of the aircraft.

[0029] This performance data includes, for example, charts or formulas that determine the aircraft's maximum speed, the power available for each internal combustion engine, and its fuel consumption, based 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 against the actual performance of each internal combustion engine.

[0030] Aircraft health data may also be considered and includes data relating in particular to the use and damage of the internal combustion engines and a mechanical transmission chain mechanically linking said engines to at least two internal combustion engines and said engine to 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 damage of an internal combustion engine. An engine counter may, for example, record the operating hours of the internal combustion engine, the creep damage it has sustained, as well as the number of cycles of a gas generator and a free turbine of a turboshaft engine.

[0031] This health data may include at least two so-called "transmission" counters, associated, for example, with input shafts of the main transmission. These input shafts are mechanically connected to internal combustion engines. Each transmission counter records usage data related to the use or damage of an input shaft. A transmission counter might, for example, count the number of input-output cycles of the second 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 this second economy operating mode.

[0032] Meteorological data may also be taken into account and includes wind and temperature data between the departure and arrival points, as well as potentially at waypoints and / or within transit corridors. This meteorological data may also include the presence of icing or inclement weather areas between the departure and arrival points that could be incompatible with the use of the second, more economical operating mode. This meteorological data may include both measured data and forecasts.

[0033] Finally, environmental data can also be taken into account, including a terrain database that allows for the consideration of topography and potentially artificial obstacles when establishing possible routes. This terrain database can also include inhabited areas, possibly with their associated population density, in order to take into account, if necessary, environmental nuisances such as noise or air pollution affecting these inhabited areas.

[0034] These different data can be stored in a memory of the computer or a memory linked to the computer.

[0035] Possible routes can be established simultaneously and independently by the computer, for example by applying a known route calculation algorithm. A possible route can be defined as a series of navigation points connected by flight segments. These flight segments can be formed, for example, by straight lines, curved lines, or circular arcs.

[0036] 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 a first AEO cost model associated with the first AEO operating mode and a second economic cost model associated with the second economic operating mode. Both cost models incorporate, in particular, the costs related to fuel used, the aircraft's hourly flight costs, aircraft maintenance costs, and the cost related to the aircraft crew.

[0037] The first and second cost models allow us to estimate the first and second operational costs of the first and second possible routes, respectively, based on the characteristics of those 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 those possible routes.

[0038] Comparing the first and second costs allows us to rank the different first and second routes according to their respective first and second cost values. This comparison can also help determine the lowest first cost among the first costs and the lowest second cost among the second costs, and / or the lowest operating cost among both the first and second costs.

[0039] Finally, the method according to the invention allows, from the plurality of possible routes calculated, the selection of a route from among all the first and second routes established based on the operational costs of these possible routes. The route thus selected allows for optimized integration of the second economical 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 so-called sampler. TPE for the English expression "Tree-structured Parsen Estimator". Depending on the situation, the selected route may or may not include at least one segment requiring the implementation of the second economic operating mode.

[0040] The aircraft routing method according to the invention may further include one or more of the following features, taken alone or in combination.

[0041] According to one possibility, the comparison of first and second 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 first and second costs.

[0042] Alternatively, the comparison of first and second costs can be carried out on the criterion of operating cost combined with a complementary criterion.

[0043] This additional criterion can be, for example, chosen from flight duration, environmental nuisances, namely noise or air pollution, weather conditions, to avoid a storm for example, the availability of emergency landing areas.

[0044] According to another possibility compatible with the previous ones, the second economical operating mode may include a first mode of use, for 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 mode of use, for 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.

[0045] According to another possibility compatible with the previous ones, each second route can comprise several successive flight segments between the departure and arrival points, and the computer can determine for each segment an aircraft operating mode, either the second economic operating mode or the first AEO operating mode, based on the segment's characteristics, such as its altitude, position, orientation, length, and the previously mentioned data. Specifically, the second economic operating mode is associated with a segment whose characteristics fall within the permissible range of this operating mode. Similarly, all flight segments of a first route are associated with the first AEO operating mode.

[0046] In addition, the computer can determine, for each segment to which the second economic operating mode is associated, information indicating which internal combustion engine among the internal combustion engines must provide mechanical power to said at least one rotor.

[0047] This information allows for alternating the operation of multiple engines during several successive flights, or even on the same flight, in order to balance the use and / or wear of the engines and their associated input shafts in the main transmission to which each internal combustion engine is connected. This information can be determined based on aircraft health data, and in particular, engine and transmission counters. Consequently, the maintenance of the internal combustion engines and the main transmission can be optimized.

[0048] According to another possibility compatible with the previous ones, the process may include a step of moving the aircraft between the starting and arrival points according to the selected route.

[0049] In this way, this flight is carried out with a minimum operational cost or optimized according to an additional criterion.

[0050] To this end, the process may also include a prior step of transmitting the selected route to an aircraft flight management device in order to implement this aircraft movement step.

[0051] According to another example consistent with the previous ones, the process may include a step of displaying the selected route on a display device, such as a screen for example, in order to allow the operator to view the selected route.

[0052] In another example consistent with the previous ones, performance data can be specific to the internal combustion engines of the aircraft in question, taking into account, in particular, the actual performance, notably in terms of power, fuel consumption, and damage, specific to each of these engines, and even the aging of the transmission chain between each engine and the rotor. An update of this performance data can, for example, be carried out following maintenance, monitoring, or a health check performed on the aircraft or, more specifically, on the internal combustion engine.

[0053] According to another example consistent with the previous ones, the process may include a step of identifying one or more emergency landing areas on the second route(s), in the event that the second economical operating mode cannot be achieved on at least part of the selected route.

[0054] Indeed, if at least part of the selected route cannot be flown using the second, 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 temperature, or a system failure on the aircraft may prevent the use of the second, intended economy mode.

[0055] Identifying one or more emergency landing areas then makes it possible to determine one or more emergency landing areas located near a second route to which the aircraft can be diverted if the second economical operating mode cannot be achieved on at least part of the selected route.

[0056] 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 do not limit the scope given to the expression "computer" or "calculator".

[0057] The memory allows the computer program to be stored as well as various information used by the computer program, namely performance data and aircraft health data, cost models associated with the aircraft, meteorological data and environmental data.

[0058] 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 a second, 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.

[0059] This routing system is configured for the implementation of the process described above.

[0060] 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.

[0061] The routing system can alternatively be integrated into the aircraft and thus constitute aircraft equipment. The routing system can then be connected to the aircraft's flight management system. Furthermore, the selected route can be displayed on a screen of the flight management system or on a screen of the aircraft.

[0062] The routing system may include a display device, such as a screen, to display the selected route to an aircraft operator.

[0063] The present invention further relates to a routing system comprising an aircraft and such a routing system not belonging to the aircraft. The aircraft includes at least one receiving device and at least one flight management device connected to the receiving device. The routing system includes 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.

[0064] The present invention finally relates to an aircraft comprising a routing system.

[0065] The invention and its advantages will become apparent in more detail in the following description, with illustrative examples given by reference to the attached figures which represent: there figure 1 , an aircraft routing suite, the figure 2 , a synoptic diagram of an aircraft routing process, the figure 3 , a diagram showing flight path corridors, and the figure 4 , a graph representing the operational costs of possible routes based on two criteria.

[0066] Elements present in several separate figures are assigned a single reference.

[0067] An aircraft routing system 50 is shown on the figure 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.

[0068] An aircraft 1 for which the routing system 50 is intended is a rotary-wing aircraft, as represented on the figure 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.

[0069] As an example, aircraft 1 shown on the figure 1 comprises two thermal engines 11 and two rotors 2,3, namely a main rotor 2 arranged above the fuselage 4 and a rear rotor 3 arranged on a tail boom of the aircraft 1.

[0070] 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 language designation "Full Authority Digital Engine Control".

[0071] In addition, 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. The flight management device 15 may, for example, be an autopilot system of aircraft 1 or an FMS device for the English designation "Flight Management System" which provides information to the pilot of aircraft 1 during the flight on a route to follow, and for example key waypoints.

[0072] Finally, aircraft 1 has a memory 19 responsible for recording usage data from the main transmission box 12.

[0073] The drive unit 10 can implement several operating modes to drive the rotors 2, 3. For example, in a first operating mode called "total" or « AEO », The regulator 14 regulates the operation of the thermal engines 11 so that all the engines 11 are used and each provides a non-zero mechanical power to jointly provide the mechanical power necessary for the proper operation of the rotors 2,3 and the aircraft 1.

[0074] Alternatively, the regulator 14 can control 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 a second operating mode known as "economy 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 second economy operating mode aims to reduce the fuel consumption of the propulsion system 10. The second economy operating mode is particularly intended for cruise flight.

[0075] The second economical operating mode may include a first mode of use in which the internal combustion engine(s) 11, not supplying mechanical power to the rotors 2, 3, are stopped and are not supplied with fuel. In the case where the internal combustion engines 11 are free-turbine turboshaft engines, the rotating components 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.

[0076] The second economical operating mode may also include a second mode of use, in which the internal combustion 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.

[0077] The second economical operating mode can, when used wisely, achieve financial savings by reducing fuel consumption, possibly in order to increase the aircraft's range or payload for a given amount of fuel.

[0078] However, under unsuitable conditions, the second economical operating mode can be counterproductive. For example, in this second economical operating 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 this second economical operating mode, the propulsion system 10 operates asymmetrically, which can affect maintenance operations and their associated costs.

[0079] 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 first and second modes of operation. The routing system 50 is configured to implement an aircraft routing method, a synoptic diagram of which is shown in the diagram. figure 2 .

[0080] For this purpose, 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.

[0081] Furthermore, the routing system 50 can be independent of aircraft 1 and can cooperate with aircraft 1 as shown on the figure 1 .

[0082] 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.

[0083] Furthermore, the routing system 50 and aircraft 1 can form a routing set 20.

[0084] Alternatively, the routing system 50 can be integrated into aircraft 1 and constitute equipment of that aircraft 1.

[0085] The routing process involves the following steps.

[0086] First, during a parameter setting step 110 of the flight plan, the flight parameters of the planned mission are defined. This parameter setting step 110 allows for the definition of a starting point 31 and an ending point 35. This parameter setting step 110 thus initializes the flight plan.

[0087] The starting point 31 and the arrival point 35 are shown on the figure 1 , on the display device 59 as well as on the figure 3 In addition, corridors 32-34 are also shown on the figure 3 and define zones in which 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 allows, for example, the definition of a minimum height ALTMin and a maximum height ALTMax relative to the ground overflown for the cruise flight phases.

[0088] Minimum altitude (ALTMinEco) and maximum altitude (ALTMaxEco) limitations relative to the ground overflown, relating to the authorized flight envelope in the second economy operating mode, are also shown on the figure 3 .

[0089] The minimum altitude ALTMin and the minimum altitude limitation ALTMinEco are determined by safety parameters to ensure sufficient altitude for aircraft recovery 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 operating modes, which are related to the second economy operating mode.

[0090] Other flight plan parameters can be defined during parameter setting step 110. For example, a maximum flight duration, one or more waypoints, and / or a fixed time or time interval for departure and / or arrival can be set. Mission-specific parameters, such as the payload or flight type (e.g., visual flight rules or instrument flight rules), can also be defined.

[0091] These flight parameters are generally set by an aircraft operator 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.

[0092] Next, the process 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 various data and taking into account the flight plan parameters. This calculation step 120 is performed prior to the takeoff of aircraft 1.

[0093] Calculation step 120 includes a first calculation substep 121 to calculate, with computer 55, one or more first routes 37, during which aircraft 1 would use only the first AEO operating mode.

[0094] Calculation step 120 includes a second calculation substep 122 for calculating, with the computer 55, one or more second routes 38, during which the aircraft 1 would use at least partially the second economy operating mode and the first AEO operating mode. In this case, as soon as the conditions for using the second economy operating mode, and in particular the authorized flight envelope, are met on a part of the route, the second economy operating mode is selected. Otherwise, the first AEO operating mode is chosen.

[0095] Only one first route 37 and one second route 38 are represented on the figure 1 However, the determination step 120 allows for the determination of several first routes 37 and several second routes 38, or even a multitude of first and second routes 37,38 covering the corridors 32-34.

[0096] The data enabling the determination of these first and second possible routes 37,38 include at least data relating to aircraft 1 and data relating to the environment. This data is, for example, stored in memory 56.

[0097] The data relating to aircraft 1 includes performance data for aircraft 1, which includes initial performance data corresponding to the first operating mode. AEO, and second set of performance data corresponding to the second economical 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, while other data may be different and specific to each operating mode. For example, limitations of the permitted flight envelope, such as altitude and forward speed, as well as available power and fuel consumption, are specific to each operating mode. This performance data may also include engine margins specific to each internal combustion engine 11, allowing the actual performance of each internal combustion engine 11 to be defined.

[0098] This performance data can be taken into account in the form of charts determining, for example, the available power and fuel consumption of each internal combustion engine 11 as a function of the mass of the aircraft 1, its altitude, its speed and / or external atmospheric conditions.

[0099] 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 second economic operating mode of the freewheel of the main transmission 12, or the number of hours of operation in the second economic operating 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 electric machines charged with supporting one or more internal combustion engines 11 in the second economic operating mode for example.

[0100] Environmental data includes meteorological data, notably 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 aircraft performance data 1, for example the previously mentioned charts.

[0101] Environmental data also includes environmental data such as a terrain database. This terrain database lists permanent natural or artificial obstacles, and even temporary artificial obstacles. For example, the terrain database includes a mountain 70 as represented on the figure 1 .

[0102] The first route 37 and the second route 38 represented on the figure 1 are thus calculated based on these different data and flight parameters.

[0103] However, the determination step 120 may conclude that only one type of possible route is feasible among the first and second routes 37,38, 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 the first AEO operating mode.

[0104] For similar reasons, calculation step 120 may conclude that no possible route exists, for both the first AEO operating mode and the second economic operating mode.

[0105] The first and second possible routes 37,38 may include several successive flight segments 41 between the starting point 31 and the arrival point 35, as shown on the figure 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.

[0106] For the first routes 37, the computer 55 associates the first AEO operating mode with each flight segment 41. For the second routes 38, the computer 55 associates an operating mode from among the second economic operating mode and the first AEO operating mode with each flight segment 41, as well as possibly information indicating which of the internal combustion engines 11 should provide mechanical power to the rotors 2,3.

[0107] According to the examples of first and second possible routes 37,38 displayed on the figure 1 , environmental data made it possible to identify mountain 70 located between the starting point 31 and the arrival point 35. The summit 72 of 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.

[0108] Consequently, the first route 37 displayed on the figure 1 was defined according to four flight segments 41 during calculation step 121, these four flight segments 41 being traversed with aircraft 1 in the first 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.

[0109] The second route 38 displayed on the figure 1 This route 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 first route 37 and are flown with aircraft 1 in the first operating mode, AEO. 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 the second operating mode, economical.

[0110] Furthermore, the determination step 120 may include an additional identification substep 125 to identify one or more emergency landing areas 36 near each second route 38 calculated in the determination step 122. Such an emergency landing area 36 may be required for flight safety. A diversion point 39 located on the second 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 on the figure 1 If aircraft 1 cannot be used with the second economical operating mode over the entire flight segment 41, for example in the event of changing weather conditions, it may not have enough fuel to reach the arrival point 35. Therefore, the flight plan includes an emergency landing area 36 and a diversion point 39 calculated during the determination substep 125 allowing aircraft 1 to divert from the second 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.

[0111] 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 first or second possible route 37,38 previously determined, based on cost models associated with the different operating modes of the aircraft 1.

[0112] The cost models include a first cost model associated with the first operating mode (AEO) and a second cost model associated with the second operating mode (economic). These first and second cost models allow the cost of a flight or part of a flight to be determined for each possible first or second route 37,38, depending on the operating mode of aircraft 1 used on each segment of that possible first or second route 37,38. Economic data may be common to both the first and second cost models, such as the cost of fuel, the cost per flight hour of aircraft 1, and / or the cost per flight hour of a pilot.

[0113] During this estimation step 130, the calculator 55 can, for example, apply the following formula to estimate the operational cost of a first or second route 37,38:

[0114] Operational costs reflect the effect of each parameter influencing flight execution. However, these operational costs can be considered in relation to flight characteristics, particularly flight duration, environmental conditions, and payload, to assess and select the best compromise on these operational costs.

[0115] This estimation step 130 includes a sub-estimation step 131 using the first cost model for each first route 37. A first route 37 is entirely carried out in the first AEO operating mode. Therefore, only the first cost model is needed to estimate the operational cost of a first route 37.

[0116] This estimation step 130 also includes a substep 132 estimating a second cost for each second route 38 using the first cost model and the second cost model. A second route 38 is partially implemented in the first operating mode (AEO) and in the second operating mode (economic). Therefore, both the first and second cost models are required to estimate the operational cost of a second route 38.

[0117] The process according to the invention then comprises a comparison step 140 carried out using the calculator 55 to compare the first and second costs previously estimated

[0118] This comparison step 140 allows the different first and second routes to be ranked according to their respective first and second costs based on one or more criteria. For example, a comparison of first and second costs can be carried out solely on the criterion of the value of each of the first and second costs for the determined first and second routes. Alternatively, a comparison of first and second costs can also take into account at least one additional criterion, chosen, for example, from flight duration, environmental impact, weather conditions, or the availability of emergency landing sites.

[0119] Finally, a selection step 150 is carried out with the calculator 55 to select a route from among the first and second possible routes 37,38 previously determined following the comparison step 140 of the first and second costs.

[0120] The selected route can, for example, be chosen from among the first and second routes 37,38 based solely on the criterion of operational cost. In this case, the selected route is the first or second possible route 37,38 with the lowest operational cost.

[0121] Alternatively, the selected route may be chosen from the first route(s) 37 and the second route(s) 38 by combining the operational cost criterion with at least one additional criterion.

[0122] In all cases, the selection step 150 may include, for example, a Monte Carlo simulation to choose a finite number of roads in a first iteration. This choice is made in a directed, not random, manner by a sampler. TPE advantageously allowing the selection of possible first and second 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 directly obtain the route with the lowest operational cost among the first route(s) 37 and the second route(s) 38. The computer 55 can optionally identify, alternatively, the first route 37 with the lowest operational cost among several second routes 37 and the second route 38 with the lowest operational cost among several second routes 38.

[0123] Alternatively, the selected route may be chosen from the first route(s) 37 and the second route(s) 38 by combining the operational cost criterion with at least one of the complementary criteria.

[0124] For example, the figure 4 represents the operational costs of a multitude of possible routes, including first routes 37 and second routes 38, on a graph where, for example, the operational cost of the first and second possible routes 37,38 is on the x-axis and a complementary criterion is on the y-axis. In the example shown, the operational costs x 1 and x Two are those representing the best compromises between operational cost and this additional criterion. In this example, a sampler TPEThe multi-objective approach can be used to identify these two operational costs, x1 and x2, which belong to the Pareto front of the Monte Carlo simulation results. The selection between the operational costs x1 and x2 can then be made based on the preferred criterion: the operational cost or this additional criterion. This selection is preferably performed automatically by the calculator 55 to obtain the selected route.

[0125] The method may include an optional display step 155 to display 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 first display of the first route 37 having the lowest operating cost among several first routes 37 and a second display of the second route 38 having the lowest operating cost among several second routes 38. The operator can thus become aware of the differences between these first and second possible routes 37,38 having the optimum operating costs.

[0126] Each first or second route 37,38 can be displayed in two dimensions, according to a top view on the display device 59.

[0127] The process may then include a step of moving aircraft 170 to perform a flight between the starting point 31 and the arrival point 35 according to the selected route.

[0128] To this end, the method may also include a step 160 of the flight plan, and in particular the selected route, to a flight management device 15 of the aircraft 1 in order to carry out the movement step 170. The transmission of the characteristics relating to the flight plan is carried out beforehand using the information transmitter 51 which cooperates with the receiving device 18 of the aircraft 1. The receiving device 18 thus receives the characteristics of the flight plan, and in particular the characteristics of the selected route, then transfers them to the flight management device 15 of the aircraft 1 in order to carry out a flight of the aircraft 1 following this selected route.

[0129] 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.

Claims

1. Routing method for an aircraft (1) provided with at least one rotor (2,3) and at least two combustion engines (11) rotating said at least one rotor (2,3), said aircraft (1) having a regulator configured to regulate said combustion engines (11) at least according to a first operating mode, wherein said combustion engines (11) each provide a non-zero mechanical power to said at least one rotor (2,3) and together, a mechanical power required at said at least one rotor (2,3), and a second operating mode, wherein at least one of said combustion engines (11) does not provide mechanical power to said at least one rotor (2,3), characterised in that said method comprises the following steps: - configuring (110) of parameters of a flight plan comprising: ∘ a starting point (31) of said flight plan, and ∘ an arrival point (35) of said flight plan, and - determining (120), using a calculator (55) of several possible routes (37,38) between said starting point (31) and said arrival point (35), as a function of said parameters of said flight plan and of several pieces of data comprising at least performance data of said aircraft (1), health data of said aircraft (1), meteorological data, and environmental data, said determination (120) comprising: ∘ determining (121) of at least one first route (37) only using said first operating mode, ∘ determining (122) of at least one second route (38) using said second operating mode and said first operating mode, - estimating (130) using said calculator (55) of an operational cost of each first and second possible route (37,38) as a function of cost models associated with the different operating modes of said aircraft (1), said estimation (130) comprising: ∘ estimation (131) of at least one first cost, respectively associated with said at least one first route, ∘ estimation (132) of at least one second cost, respectively associated with said at least one second route, - comparing (140) of said first and second costs, - selecting (150) using said calculator (55) of a route from among said first and second routes (37,38) according to said comparison of said first and second costs, - transmitting (160) of the selected route to a flight management device (15) of said aircraft (1).

2. Method according to claim 1, for which said method comprises a movement (170) of said aircraft (1) between said starting (31) and arrival (33) points according to said selected route.

3. Method according to any one of claims 1 to 2, for which said performance data of said aircraft (1) comprise: ∘ first performance data corresponding to said first operating mode of said aircraft (1), and ∘ second performance data corresponding to said second operating mode of said aircraft (1), said health data of said aircraft (1) comprise: ∘ an engine counter associated with each combustion engine (11), said engine counter accounting for at least one piece of usage data of said combustion engine (11), and ∘ at least two transmission counters associated respectively with input shafts (13) of a main transmission box (12) arranged between said combustion engines (11) and said at least one rotor (2,3), said input shafts (13) being mechanically connected, respectively to said combustion engines (11), each transmission counter accounting for at least one piece of usage data of one of said input shafts (13), said meteorological data comprise data relating to the wind and to the temperature between said starting (31) and arrival (35) points, and said environmental data comprise a land database.

4. Method according to any one of claims 1 to 3, for which said at least one second route comprises several successive flight segments between said starting (51) and arrival (55) points, and said calculator (55) determines, for each segment, an operating mode of said aircraft (1) among said first and second associated operating modes as a function of features of said segment and of said data.

5. Method according to claim 4, for which said calculator (55) determines, for each segment, for which said second operating mode is associated, a piece of information indicating said combustion engine (11) among said combustion engines (11) providing said mechanical power to said at least one rotor (2,3).

6. Method according to any one of claims 1 to 5, for which said second operating mode comprises a first mode of use for which one single combustion engine (11) among said combustion engines (11) operates and ensures only the rotation of said at least one rotor (2,3), said at least one other combustion engine (11) being stopped and not provided with fuel and a second mode of use for which one single combustion engine (11) among said combustion engines (11) provides a mechanical power to said at least one rotor (2,3) to rotate it, said at least one other combustion engine (11) being started and provided with fuel, not providing any mechanical power to said at least one rotor (2,3).

7. Method according to any one of claims 1 to 5, for which said selection (150) of a route among said first and second routes (37,38) is done on the only criterion of said operational cost, the selected route being the possible route (37,38) having said first or second lowest cost.

8. Method according to any one of claims 1 to 5, for which said selection (150) of a route among said first and second routes (37,38) is done on the criterion of the combined operational cost with at least one complementary criterion.

9. Method according to claim 8, for which said at least one complementary criterion is chosen from among a flight duration, environmental damage, meteorological conditions, an availability of emergency landing areas.

10. Method according to any one of claims 1 to 9, for which said method comprises a step (125) of identifying one or more emergency landing areas (36) on said at least one second route (38), in the case where said second operating mode cannot be performed on at least one part of said selected route.

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

12. Method according to claim 11, for which said display step (155) comprises a first display of said first route (37) having the lowest operational cost among several first route (37) and a second display of said second route (38) having the lowest operational cost among several second routes (38).

13. Computer program comprising instructions which, when said program is executed, lead to implementing the method according to any one of claims 1 to 12.

14. Routing system (50) for aircraft (1) provided with at least one rotor (2,3) and at least two combustion engines (11) rotating said at least one rotor (2,3), said aircraft (1) having a second operating mode, wherein at least one of said combustion engines (11) does not provide mechanical power to said at least one rotor (2,3), said system (50) comprising: - at least one calculator (55), and - at least one memory (56) storing at least one database, characterised in that said routing system (50) is configured to implement the routing method for an aircraft, according to any one of claims 1 to 12.

15. Routing assembly (20) comprising an aircraft (1) and a routing system (50) according to claim 14, characterised in that said aircraft (1) comprises at least one receiving device (18) and at least one flight management device (15) connected to said receiving device (18), said routing system (50) comprises at least one information emitter (51) configured to engage with said receiving device (18) of said aircraft (1), in order to transmit features of said flight plan and said selected route to said receiving device (18) which transfers them to said flight management device (15).

16. Aircraft (1), characterised in that said aircraft (1) comprises a routing system (50) according to claim 14.