DE102021104092A1 - Method of operating an aircraft depending on an operating mode - Google Patents

Abstract

Disclosed is a method for operating an aircraft, the aircraft having at least one engine for propelling the aircraft, with several energy suppliers that differ from one another being provided to supply the engine, the method comprising: determining an operating mode, the operating mode having at least one predefined one rule for the supply of the drive by the energy suppliers includes; Operating the aircraft depending on the specific operating mode in which the supply of the drive by the energy supplier is subject to the predefined rule.

Description

The invention relates to a method for operating an aircraft, a control device for carrying out such a method, and an aircraft that can be operated using the method.

Conventional aircraft, in particular commercial cargo and passenger aircraft, mostly have an engine that is supplied with kerosene. For example, gas turbines, in particular turbine jet engines, have become established in almost all aircraft categories. Turboprop engines are also used for shorter operating distances or for special purposes, such as in the military sector. Irrespective of the differences between the engine types, however, kerosene is the main source of energy for aircraft propulsion.

For ecological reasons and the foreseeable limited availability of fossil fuels, there is a desire to create efficient aircraft engines for alternative energy suppliers, in particular based on electrical energy and/or hydrogen. A general goal is to be able to supply electric motors with high power consumption reliably and over a longer period of time, for example in order to safely drive one or more propellers to generate the propulsion force required for flight. Alternatively or additionally, essentially conventional gas turbine drives can be used, which, however, are supplied with hydrogen.

In principle, therefore, suitable propulsion technologies are available to use alternative energy suppliers for aircraft propulsion systems. One problem, however, is that alternative energy suppliers often have special requirements for storage on an aircraft compared to kerosene. For example, large amounts of electrical energy can regularly only be stored in accumulators, which have a high mass compared to kerosene tanks.

Similar problems exist when using hydrogen as an energy supplier because the storage of hydrogen requires special tank structures, in particular high-pressure tanks or cryogenic tanks for cryogenic storage. In contrast to this is kerosene, which has several properties that are advantageous for use in aircraft, for example a low specific mass. In addition, it can easily be accommodated in aircraft structures that are already present, typically in the aircraft wing. In this way, kerosene tanks only increase the aircraft weight insignificantly. On the other hand, alternative energy suppliers for the supply of aircraft engines increase the aircraft weight significantly, so that the operational efficiency of the aircraft is reduced accordingly. In particular, the possible maximum range of the aircraft compared to pure kerosene operation is reduced. It is possible to transport additional mass from an alternative energy supplier proportionately instead of payload. However, this reduces the efficiency of the aircraft in relation to the payload.

Irrespective of the problems described above, the inventors have recognized particular potential for using alternative energy suppliers over relatively short flight distances, for example over a distance of a few hundred kilometers. On such short distances, the use of alternative energy suppliers can also make sense from an economic point of view. However, the market for commercial aircraft with a very short range can be considered small, so that such aircraft are currently not being mass-produced and offered. It is also to be expected that the respective distance over which the use of alternative energy suppliers is efficient will be subject to continuous change in the future. It is therefore hardly economical for an aircraft manufacturer to develop an aircraft for a specific very short range. In particular, the high safety requirements in aviation, which are associated with cost-intensive approval procedures for newly developed aircraft, are a hindrance.

The circumstances described are unsatisfactory because airworthy propulsion technologies based on alternative energy suppliers are generally known. The increasing desire for a reduction in the pollutant emissions of conventional aircraft engines could thus already be taken into account.

The aim is to develop aircraft that provide multiple energy suppliers for the supply of one or more aircraft drives. In this way, the disadvantages of individual energy suppliers are to be compensated. However, the limited usability of such hybrid aircraft compared to classic kerosene drives has so far been regarded as disadvantageous, so that there is not sufficient competitiveness compared to purely kerosene-powered aircraft.

It is an object of the invention to provide a safe aircraft with a number of energy suppliers provided for supplying the drive, with the aircraft being able to be used flexibly and efficiently.

The object is achieved by a method having the features of claim 1.

A method for operating an aircraft is specified, the aircraft having at least one drive for propelling the aircraft. A plurality of energy suppliers that differ from one another are provided to supply the drive, the method comprising: determining an operating mode, the operating mode comprising at least one predefined rule for the supply of the drive by the energy suppliers; and operating the aircraft depending on the specific operating mode in which the supply of the drive by the energy suppliers is subject to the predefined rule.

The method is generally based on one or more operating modes in order to ensure flexible and at the same time secure use of the multiple energy suppliers. For this purpose, a corresponding operating mode includes a predefined rule that specifies how the aircraft's drive is to be supplied by the multiple energy suppliers. For example, one of the energy suppliers can only be used for a specific flight phase, for example the start of the aircraft, whereas another energy supplier can be available for supplying the drive throughout the flight. Such a rule is suitable for meeting the high safety requirements of modern aircraft, in particular because incorrect use of the energy suppliers, for example premature exhaustion of an energy supplier, is avoided. In other words, it is ensured that the aircraft is not operated in any way with regard to the available energy suppliers, but only in a range that is z. B. is tailored to a specific operating scenario and meets the relevant security requirements. Accordingly, the operating mode can be determined, for example, as a function of a specific operating scenario of the aircraft, such as a short-haul flight, and the operation of the aircraft can be used as a basis.
The use of operating modes of the type described above also ensures efficiency-optimized operation of the aircraft, in that ineffective use of the energy suppliers can be ruled out by suitably designing the predefined rule. For example, the use of an energy supplier which, in connection with a drive, only develops maximum efficiency at a specific flight altitude can only be permitted at this specific flight altitude. In this way, the aircraft can be used efficiently over different flight distances.

Embodiments of the invention are disclosed in the dependent claims, the description and the figures.

According to one embodiment, determining the mode of operation includes: selecting one of multiple modes of operation, each of the modes of operation including at least one of multiple predefined rules for powering the drive through the multiple energy suppliers, wherein the predefined rules differ between some of the modes of operation. The use of multiple operating modes increases the flexibility of the aircraft for different operating scenarios, for example for different operating distances or payloads. In addition or as an alternative to a plurality of operating modes, a modification of a respective operating mode can also be made possible. However, it is preferred that an operating mode, in particular the associated rule, cannot be modified or can only be modified within narrow limits. Instead, to increase flexibility, several operating modes can be provided, each of which contains a clear usage rule for the energy suppliers. This reduces the risk of error for wrong modifications of an operating mode.

According to a further embodiment, the supply of the drive by at least one of the energy suppliers is released, blocked and/or modified in the specific operating mode depending on at least one operating parameter of the aircraft. In this way, the supply of the drive can be adapted to the operation of the aircraft - within the framework of the predefined rule. For example, one of the energy suppliers can be provided as a reserve, so that the use of this energy supplier for supplying the drive is blocked until the capacity of another energy supplier is exhausted. The power supply for the drive from the energy suppliers can additionally or alternatively be provided by an operating scheme of the aircraft. For example, the supply can take place depending on firmly defined flight sections, such as takeoff, climb, operation at cruising altitude, approach, or landing.

According to a further embodiment it is provided that in the specific operating mode the contribution of at least one of the energy suppliers to the supply of the drive is adjusted as a function of at least one operating parameter of the aircraft. For example, when the drive is at full load, a specific contribution ratio can be provided, for example 50% each from two energy suppliers. With a reduced load during a flight at cruising altitude, on the other hand, one of the energy suppliers can make a smaller contribution than the other, eg 80% and 20%. It is also possible that one of the energy suppliers makes 0%, ie no contribution. It is also possible to use predefined contribution ranges for the respective energy lie ferants to allow the pilot to use the energy suppliers variably within the contribution areas. The contribution ranges are preferably defined in such a way that a relevant mission of the aircraft can also be carried out safely with the specific operating mode when the contribution ranges are fully utilized.

In a further embodiment, the at least one predefined operating parameter represents at least one of the following information: operating distance, operating status, availability of at least one of the energy suppliers during operation, time information, flight segment, weight of the aircraft. This list is not to be understood as exhaustive, i.e. other operating parameters are also possible. Taking one or more operating parameters into account ensures even more flexible usage options, with safety aspects also being taken into account. For example, it may turn out during a flight that the consumption of one of the energy suppliers used is higher than normal, i.e. the availability of the energy supplier concerned is lower than expected. The activated operating mode can then be adjusted in such a way that the consumption of the relevant energy supplier is reduced, for example by operating the drive in a different load range. As an alternative or in addition, other energy suppliers can be increasingly used to supply the drive.

In general, it is preferred that the operation of the aircraft is based on the specific operating mode for the entire duration of a flight. However, it is also conceivable that the operating mode is modified or changed during flight operations, e.g. in the event of an unforeseen operating situation. For example, you can switch between two predefined operating modes.

In a further embodiment, the operating mode is determined as a function of at least one determination parameter, with the determination parameter preferably representing one of the following: operating distance, weight of the aircraft, maximum landing weight, maximum take-off weight, payload of the aircraft, number of passengers, availability of at least one of the Energy suppliers at an airport, operating time. This list is not final, i.e. other determination parameters are also possible. In particular, it is also possible for a determination parameter to be formed by an operating parameter of the aircraft, in particular one of the operating parameters mentioned above. The determination as a function of a determination parameter simplifies the operation of the aircraft overall, particularly when using a determination rule to automate the determination. In an example, the flight distance and the payload can be taken into account in the determination, with a first operating mode being determined. On the other hand, if the availability of the energy suppliers at the airport is also taken into account, a second operating mode can be determined. For example, a quantity of methanol for the first mode of operation may not be available in sufficient quantity at a relevant airport, so that the second mode of operation is determined according to which, for example, no methanol is required.

In the specific operating mode, at least one of the energy suppliers can be provided as a primary energy supplier and at least one other energy supplier can be provided as a secondary energy supplier, with the secondary energy supplier preferably forming a reserve energy supplier for the primary energy supplier. Alternatively or additionally, the secondary energy supplier can form a support supplier for the primary energy supplier. A primary energy supplier can be the energy supplier that is mainly used for the operation of the aircraft, for example for most of the flight time at a cruising altitude of the aircraft. The primary energy supplier can alternatively or additionally be an energy supplier which is used primarily over another energy supplier.

A reserve energy supplier can generally be an energy supplier that is used when another energy supplier, in particular a primary energy supplier, is exhausted. The use of the reserve energy supplier can be provided in particular for an unforeseen operating situation, for example in the event of an unplanned extension of the operating time or an unexpected increase in consumption by the other energy supplier.

A support energy supplier can generally be an energy supplier that is used when another energy supplier, in particular a primary energy supplier, is to be supplemented, e.g. to maximize an amount of energy available for the drive per unit of time or to relieve the other energy supplier.

In one example, the first energy supplier includes at least one electrical energy store, in particular a rechargeable battery, with a second energy supplier including kerosene. In this configuration, the drive is primarily powered by electrical energy. Kerosene is preferably only used as a reserve and is only used, for example, when unforeseen circumstances arise that require an extension of the planned flight time or flight distance.

In another example, one of the energy suppliers includes hydrogen and another of the energy suppliers includes methanol. The energy supplier methanol can, if it cannot be used directly by the drive, be converted into hydrogen, e.g. with the help of a hydrogen reformer, so that a gas turbine or the like can only be supplied with hydrogen, which is particularly advantageous from an ecological point of view. The methanol can only be used as a reserve or can be used on an equal footing with directly stored hydrogen. So it is conceivable to use the methanol for the regular supply of the drive as soon as the hydrogen supply is exhausted. In this case, the methanol can be regarded as a subordinate, i.e. secondary energy supplier, but not merely as a reserve for an unforeseen extension of flight time. The aircraft can have a respective tank for hydrogen and methanol, which can be optionally mounted on the aircraft.

In the example described, the aim can be to supply the drive with hydrogen and methanol within a flight route. However, it is also conceivable that only one of the two energy carriers should be used within a flight route. In this way, an operating mode can be available in which one of the two energy suppliers, e.g. hydrogen or methanol, is not used to supply the drive. A tank for the unused energy supplier can advantageously be removed from the aircraft in order to reduce the weight of the aircraft. A tank for the required energy supplier, on the other hand, is mounted on the aircraft.

According to a further embodiment, determining the operating mode includes selecting one of a plurality of operating modes. The operating modes include a first and at least one second operating mode, with the energy suppliers including a first and at least one second energy supplier. In the first operating mode, the first energy supplier is provided as the primary energy supplier and the second energy supplier is provided as the secondary energy supplier. In the second operating mode, on the other hand, the second energy supplier is provided as the primary energy supplier and the first energy supplier is provided as the secondary energy supplier. The prioritization of the energy suppliers is thus reversed between the operating modes. This increases the flexible use of the aircraft in a special way, while the number of energy suppliers involved can remain unchanged.

In one example, the first energy supplier is electrical energy from a rechargeable battery that can be mounted on the aircraft, with the second energy supplier being formed by kerosene, which can be kept available, for example, in a wing tank of the aircraft. In the first operating mode, electrical energy represents the primary energy source. Kerosene is only of secondary importance for supplying the drive. In this way, all-electric operation of the aircraft can be provided, with the kerosene only being used as a reserve, for example. Due to the primarily electrical supply, the first operating mode is generally only suitable for short ranges, for example up to 650 kilometers. In order to nevertheless enable flexible use of the aircraft for longer ranges, kerosene is the primary energy supplier in the second operating mode. The first energy supplier (electrical energy from a rechargeable battery that can be mounted on the aircraft) can also be used as a reserve, ongoing support for a drive (e.g. jet engine) supplied with the kerosene and/or to support a take-off or go-around process. The first energy supplier can also only be used for a specific operating phase, e.g. for operation on an airport runway and/or for the landing approach. Alternatively, the first energy supplier can also be dispensed with entirely, with a battery of the first energy supplier preferably being removed from the aircraft.

For example, a conventional turbofan engine without the use of bleed air (“bleedless engine”), in which all aircraft systems are electrically powered by an engine generator, can be supplemented with a battery. This can, for example, supply the electrical aircraft systems when the aircraft is taking off and also drive the electrical generators of the engines in order to support the propulsion. With an assumed power output of 35 MW per electric generator of an engine at airport level and a power consumption of 0.5 MW (1.5 percent of the power output) for the electrical systems of the aircraft, using an additional installed battery can increase the power of the engine by a total of approx. 3 percent can be achieved for the starting process. This opens up the possibility of reducing the required take-off distance of the aircraft compared to pure kerosene operation. However, a shortened take-off distance does not necessarily make sense if a very long take-off distance is available. In this case, the additional battery can be dispensed with, ie the battery can be dismantled, so as not to unnecessarily increase the weight of the aircraft.

In the event that kerosene forms the primary energy supplier, it is possible to provide the following operating modes. In a first operating mode, the drive is primarily supplied with kerosene, i.e. the driving force is generated by burning kerosene. In this operating mode, no additional rechargeable batteries are preferably mounted on the aircraft in order to generate drive energy using electrical energy. Any batteries can therefore be removed for this operating mode. In a second operating mode, a battery with a first storage capacity is mounted on the aircraft. In this operating mode, too, the driving force is primarily generated by burning kerosene, although additional electrical energy from the installed battery is used to support the drive when starting or going around ("boost" function). In a third operating mode, a battery with a second storage capacity that is greater than the first storage capacity is mounted on the aircraft. In this operating mode, the electrical systems of the aircraft are powered by the battery, with the battery also being used to support the propulsion, for example by operating generators from one or more jet engines as an electric motor and thus driving the turbine. The third operating mode can be provided for shorter operating distances, e.g. up to 500 kilometers, in which case the battery can be in the form of a lithium-ion battery, for example. However, other battery types can also be considered. Due to the higher storage capacity, the battery can provide 1 MW of electrical power, for example. This can be in the range of 2.5 percent of the total output per engine.

In another example, multiple modes of operation based on multiple energy suppliers are provided. One of the energy suppliers is formed by electrical energy from a rechargeable battery that can be mounted on the aircraft. In at least one of the operating modes, a predefined minimum proportion of the energy provided for the drive is preferably stored in the rechargeable battery. For example, the minimum proportion can advantageously be in the range between 1 and 50 percent, so that proportions of 5 or 20 percent are also possible. Other values are also conceivable.

In a further embodiment, the energy suppliers include a first, second and third energy supplier, with the first energy supplier being provided as the primary energy supplier and the second and third energy suppliers being provided as the secondary energy suppliers in the specific operating mode. The secondary energy suppliers can form reserve energy suppliers and/or backup suppliers for the primary energy supplier. The reliable and safe use of several energy suppliers is thus possible even with more than two different energy suppliers. For example, kerosene can serve as the primary energy supplier and two different batteries, which can have different storage capacities, act as the second and third energy suppliers. The second energy supplier can be provided, for example, to support the primary energy supplier, for example in that the second energy supplier supports the drive in parallel with the first energy supplier. The third energy supplier can serve as a reserve for emergencies.

In another example, hydrogen is used as the primary energy supplier and methanol from two different methanol tanks as the secondary energy supplier. The ranking of the energy suppliers as primary or secondary energy suppliers can also be reversed. A respective operating mode can be provided for both cases. In this way, the aircraft can be operated flexibly and yet safely with changing availability of hydrogen and methanol at a particular airport and for different ranges and payloads.

If methanol is to be used as an energy supplier, the aircraft and/or a methanol tank that can be mounted on the aircraft is/are preferably equipped with a reformer in order to extract hydrogen from the methanol. In one example, two methanol tanks are provided for one operating mode, with one of the methanol tanks being permanently integrated into the aircraft and the other methanol tank being flexibly mountable on the aircraft. A reformer can also be permanently integrated in the aircraft. In addition, a hydrogen tank, for example a cryotank, can be mounted on the aircraft. In a first operating mode, hydrogen stored in the hydrogen tank is the primary energy supplier, with methanol forming second and third energy suppliers in the two methanol tanks, which serve as secondary energy suppliers, in particular for reserve purposes. In a second operating mode, the methanol in the two methanol tanks serves as the first and second primary energy supplier, with hydrogen optionally being provided as a secondary energy supplier. In this way, in particular, an operating mode based exclusively on methanol can be created, in which a hydrogen tank of the aircraft can remain empty. In a third operating mode, hydrogen is the primary energy supplier, with the aircraft's methanol tanks being able to remain empty.

In general, it is preferred that one or more tanks dedicated to the particular operational mode are not required to be dismantled from the aircraft before the aircraft is operated in the particular operational mode. In particular, the hydrogen tanks and/or methanol tanks mentioned can be removed from the aircraft if they are not permanently integrated into the aircraft. The efficiency of the aircraft can be increased in this way.

In a further refinement, the drive comprises at least one electric motor, with at least several of the energy suppliers being provided for supplying the electric motor in the specific operating mode. For example, hydrogen and methanol can be provided as energy suppliers. Both energy carriers can be fed to a fuel cell of the drive and in this way converted into electrical energy that is used to supply the electric motor. If the drive has an electric motor, this is preferably used to drive a propeller, so that the electric motor and the propeller together form a propeller drive for the aircraft. However, it is also possible for the electric motor to be used to continuously support a gas turbine, in particular during flight operations.

According to a further embodiment, the drive comprises a plurality of drives that differ from one another. These include a first drive and a second drive, with one of the energy suppliers being provided for supplying the first drive and another of the energy suppliers being provided for supplying the second drive in the specific operating mode. The energy suppliers can thus serve to selectively supply assigned drives. In this way, different drive technologies can be combined with each other, with the supply of the individual drives being guaranteed by the individual energy suppliers. For example, the first drive includes an electric motor or is formed by an electric motor. In this case, the first energy supplier can be formed by the electrical energy of a rechargeable battery that can be mounted on the aircraft. The second drive, on the other hand, can have a gas turbine, in particular a gas turbine that is supplied with kerosene or hydrogen. Thus, a classic kerosene drive can be combined with a forward-looking electric drive in order to advantageously enable flexible use of the aircraft that is still efficient. For example, on a short flight route of e.g. 350 kilometers, a large battery can be mounted on the aircraft as the first energy supplier in order to enable a substantially all-electric flight. For longer distances, on the other hand, a smaller battery can be carried, which is only used as an aid, i.e. to support the kerosene drive.

In the case of several drives, these can advantageously be coupled to a gear. For example, the aircraft can have an electric propeller drive, which has at least one electric motor coupled to a propeller. In addition, the aircraft can have a gas turbine, which is connected to the propeller via a gearbox and can drive the propeller to rotate in addition to or as an alternative to the electric motor.

According to a further embodiment, in the specific operating mode, one of the drives is provided as the primary drive and another of the drives is provided as the secondary drive. In other words, the first drive can be the primary drive and the second drive can be the secondary drive. Alternatively, the first drive can be the secondary drive and the second drive can be the primary drive. In this way, with the help of the specific operating mode, it can be determined which of the drives should primarily be used for the flight. For example, for a flight to be carried out predominantly or entirely with an electric motor, the electric motor can be set accordingly as the primary drive and a corresponding operating mode can be determined. A conventional kerosene drive can serve as a secondary drive, which for example only serves as a backup if the electric motor can no longer be operated with sufficient power. Conversely, for longer ranges, the kerosene drive can be specified as the primary drive and a corresponding operating mode can be determined for this. It is also conceivable that the operating mode is not only selected as a function of the range. Additional or different operating parameters can also be used, as explained above. For example, the need for maintenance of the respective drives can be taken into account.

According to a further embodiment, the determination of the operating mode includes that one of a plurality of operating modes is selected, the operating modes comprising a first and at least one second operating mode, wherein in the first operating mode the first drive is provided as the primary drive and the second drive is provided as the secondary drive, wherein the secondary drive preferably forms a reserve drive for the primary drive. In the second operating mode, the first drive is provided as a secondary drive and the second drive is provided as a primary drive, with the secondary drive preferably forming a support drive for the primary drive. The flexible use of the aircraft can thus also be realized at the level of the drives, ie the Drives can be used in different ways as required. For example, an electric motor of the aircraft can function as a primary drive or as a secondary drive in different operating modes. In the case of primary propulsion, the electric motor can drive a propeller to provide primarily or all-electric power to the aircraft. If the electric motor is provided as a secondary drive, it can, for example, drive the blade wheel of a gas turbine in a supporting manner.

In a further embodiment, one of the energy suppliers comprises at least one electrical energy store which can be flexibly mounted on the aircraft in order to supply the drive with electrical energy. A flexible installation of the energy store makes it possible to replace the energy store without a great deal of time or installation effort. For example, the energy storage device can be easily replaced between two flight missions, so that time-consuming charging of the energy storage device on the aircraft is no longer necessary. It is also possible to remove the energy store after fully electric flight operations in order to carry out a flight with a different primary energy supplier, such as kerosene, without delay. The energy store can be installed in a separate holding device inside the aircraft and easily accessible from the outside through a flap. Alternatively, the energy store can be mounted on an outside of the aircraft, for example on an aircraft wing. The energy store can be formed by a rechargeable battery.

In a further embodiment, one of the energy suppliers optionally comprises one of a plurality of electrical energy storage devices, with the energy storage devices being able to be mounted flexibly on the aircraft in order to supply the drive with electrical energy, and with the storage capacity of the plurality of energy storage devices differing at least in part from one another and/or or wherein the storage capacity of at least some of the plurality of energy stores is the same. The energy stores can form a system for the electrical supply of aircraft drives with variable storage capacity with the aircraft or multiple aircraft. For example, multiple operating modes can be provided, each of which is designed for a different range of the aircraft and each prescribes a range-adapted number of energy stores to be mounted on the aircraft in question if the aircraft is to be operated in the associated operating mode. In this way, the aircraft can be operated particularly flexibly and yet efficiently and safely.

According to a further embodiment, one of the energy suppliers comprises a first energy carrier which can be accommodated in a first energy carrier store of the aircraft, the first energy carrier store being permanently connected to the aircraft or flexibly mountable on the aircraft in order to supply the drive with the first energy carrier. The first energy carrier can be formed by a conventional energy carrier, in particular kerosene. However, an alternative energy carrier is also possible, e.g. hydrogen or methanol. The flexible installation of energy carrier storage opens up further possibilities for using the aircraft flexibly. For example, the energy carrier store can be dismantled if a flight with a very short range is to be carried out and a corresponding operating mode is determined for this purpose, in which only one electrical energy store is used to supply an electrical drive. In the case of a longer range, on the other hand, the energy storage device can be mounted flexibly. The first energy source can be formed by kerosene, hydrogen or methanol.

According to an advantageous embodiment, another of the energy suppliers includes a second energy carrier that can be accommodated in a second energy carrier store of the aircraft, the second energy carrier store being permanently connected to the aircraft or flexibly mountable on the aircraft in order to supply the drive with the second energy carrier. The flexible use of the aircraft can be further increased in this way. For example, the second energy carrier can be formed by methanol, which can be used, for example, by means of a reformer or in some other way to generate hydrogen. Methanol has fewer storage requirements than hydrogen and is therefore attractive as an energy carrier in the aviation sector. The combination of one or more hydrogen tanks with one or more flexibly mountable methanol tanks also enables the aircraft to be used efficiently for different ranges. In principle, however, both types of energy storage devices can be mounted flexibly on the aircraft. One or more hydrogen tanks are preferably permanently integrated into the aircraft. On the other hand, one or more methanol tanks can preferably be mounted flexibly on the aircraft.

The drive preferably forms a flight drive of the aircraft. In other words, the drive, which as explained can also include several different drives, is used to generate the necessary flight drive force. The drive can in particular have an electric motor for driving a propeller of the aircraft. Alternatively or additionally, the drive can have at least one gas turbine an energy carrier is supplied. Both drive types can also be implemented on an aircraft, in particular in multiple designs, for example on the left and right wing. In addition, the drive can have a fuel cell, which generates electrical energy on the basis of hydrogen and/or methanol, which can be used to supply the electric motor and/or to support a gas turbine. If the gas turbine is assisted, a generator arranged in the gas turbine can be operated as an electric motor.

According to a further embodiment, the energy suppliers are provided depending on the specific operating mode, so that the energy suppliers are available during operation of the aircraft to supply the drive depending on the predefined rule of the specific operating mode.

The provision of the energy suppliers can include at least one of the following method steps: dismantling at least one first electrical energy store on the aircraft; mounting at least one second electrical energy storage device on the aircraft; dismantling at least a first energy storage device from the aircraft; mounting at least one second energy storage device on the aircraft; Filling of the installed energy carrier store and/or a fixed energy carrier store of the aircraft with at least one energy carrier. In particular, the energy store can be mounted in such a way that the energy store is inserted or pushed into a receiving device formed on the aircraft, so that the electrical contacts of the receiving device and the energy store make contact with one another. The contacts of the receiving device are electrically connected to the drive, which in particular comprises an electric motor, so that in this way the drive can be supplied by the energy store. Dismantling can be done in reverse to assembling.

According to one embodiment, the provision of the energy suppliers differs between a number of operating modes depending on the specific operating mode. For example, specific storage devices can be mounted on the aircraft for a first operating mode. However, the storage devices are disassembled for a second mode of operation, with other storage devices being mounted on the aircraft.

In general, the provision of the energy suppliers can include a modification of one or more storage devices mounted on the aircraft, with storage devices being able to be, for example, the aforementioned energy storage devices and/or energy carrier storage devices. In particular, storage devices can be at least partially dismantled and/or replaced by dismantling a first storage device and mounting a second storage device on the aircraft. In this way, for example, a dead battery can be replaced with a charged battery, or a battery with a first weight can be replaced with a battery with a second weight that is greater than the first weight. It is also possible to simply dismantle one or more storage devices if these storage devices are not provided as energy suppliers according to the specific operating mode.

The invention also relates to a control device for operating an aircraft. The aircraft has at least one drive for propelling the aircraft, with several different energy suppliers being provided to supply the drive, with the control device being designed to carry out the method according to at least one of the embodiments described above.

According to a further aspect of the invention, a computer program is provided which comprises instructions which, when the computer program is executed by a computer, cause the computer to carry out the steps of the method according to at least one of the embodiments described above.

The invention also relates to an aircraft with at least one drive for propelling the aircraft. Several different energy suppliers are provided to supply the drive. The aircraft is further adapted to be operated with the method according to at least one of the embodiments described above.

The aircraft can have a control device which is designed to carry out the method according to at least one of the embodiments described above. However, it is also possible that individual steps of the method are not carried out by the control device but in another way. For example, the operating mode can be determined on a central computer. This process can be initiated and monitored in particular by an operator of the aircraft. It is also possible here that the determination of the operating mode made on the central computer is stored in a file and then communicated wirelessly a control device of the aircraft that is to be operated as a function of the specific operating mode is transmitted. In addition to using a central computer, it is also conceivable for the determination to be carried out entirely or partially by a human. For example, an operational planner of the aircraft can decide in which operating mode the aircraft is to be operated on the basis of the range and payload envisaged in a specific operational scenario. However, for security reasons, an automated determination of the operating mode may be preferred.

According to one embodiment, the at least one drive comprises a first drive and a second drive, the first drive comprising at least one electric motor and the second drive comprising at least one gas turbine. The electric motor can be designed separately from the gas turbine and can be used in particular to drive a propeller. The electric motor and the gas turbine can be coupled to one another via a transmission or can be optionally coupled.

According to a further embodiment, the aircraft has a first energy carrier store for accommodating a first of the plurality of energy suppliers. Furthermore, the aircraft has a second energy carrier store for accommodating a second of the plurality of energy suppliers. The at least one drive is adapted to be supplied by both energy suppliers during flight operations. For example, a fuel cell can be supplied with hydrogen that is stored in the first energy carrier store. In addition, methanol can be stored in the second energy carrier store and used to supply the fuel cell. The energy suppliers can generally be formed by energy carriers.

It is understood that features described in connection with one of the embodiments described above, e.g. with reference to the method, can also be implemented in other embodiments, e.g. with reference to the aircraft described. This also applies vice versa.

The invention is described further below by way of example with reference to the drawings, in which functionally identical parts are provided with the same reference numbers.

• 1: ein Verfahren zum Betreiben eines Flugzeugs;
• 2: ein schematisches Flugzeug, das mit dem Verfahren gemäß 1 betrieben wird;
• 3: ein Diagramm, das relative Massenanteile über eine Flugzeugreichweite für zwei Betriebsmodi illustriert.

The drawings only show examples:

• 1 : a method of operating an aircraft;
• 2 : a schematic aircraft, according to the method 1 is operated;
• 3 : a graph illustrating relative mass fractions over an aircraft range for two modes of operation.

A method for operating an aircraft is based on 1 explained. The aircraft comprises at least one drive for propelling the aircraft, with several energy suppliers that differ from one another being provided to supply the drive. The method begins with step 10, in which one of several operating modes for operating an aircraft is determined. A determination rule can be provided for this purpose, which selects one of the multiple operating modes on the basis of one or more determination parameters, such as the payload of the aircraft, range and/or the availability of the energy suppliers. In this way, flexible use of the aircraft is made possible, which takes into account high safety requirements by adapting the use of the energy suppliers to the operational requirements.

Each operating mode includes at least one predefined rule for supplying the drive with energy suppliers. Exemplary operating modes are described below using 3 explained. In step 12 the aircraft is operated depending on the specific operating mode in which the supply of the drive by the energy suppliers is subject to the predefined rule. The predefined rule can thus provide that the energy suppliers supply the drive according to the predefined rule. The energy suppliers are therefore not used arbitrarily, but in a specific way, for example within specific limits and/or as a function of one or more operating parameters.

A further step can be provided between steps 10 and 12 (not shown), according to which one or more of the energy suppliers are provided on the aircraft depending on the specific operating mode. For example, one or more batteries can be mounted on the aircraft so that each battery can supply the drive. Alternatively or additionally, one or more energy carriers, e.g. kerosene or hydrogen, can be filled into one or more energy carrier storage units of the aircraft and be available to supply the drive.

Regarding 2 an aircraft 14 is described purely schematically, which according to the basis of 1 described method can be operated. The aircraft 14 includes a wing 16 on which a first drive 18 and a two Ter drive 20 are provided. Both drives 18 and 20 can also be provided on another wing of the aircraft 14 (not shown). The engines 18 and 20 are generally capable of independently or jointly producing sufficient thrust to accelerate the aircraft 14 to the speed required for flight. The first drive 18 is connected to a first energy supplier 22 . Furthermore, the second drive 20 is connected to a second energy supplier 24 . A control device 26 is also arranged on the aircraft 14 and is coupled to the drives 18 and 20 in order to control them.

In one example, the first drive 18 is formed by an electric motor that drives a propeller of the aircraft 14 that is not shown in detail. The energy supplier 22 includes a rechargeable battery (not shown) in which electrical energy for supplying the drive 18 is stored. Various rechargeable batteries with different capacities are provided, which can each be mounted flexibly on the aircraft 14 . This further improves the possible uses of the aircraft 14, as described in more detail below with reference to FIG 3 is explained.

The second drive 20 is formed by a gas turbine (not shown), which is operated with kerosene. Accordingly, the second energy supplier includes a kerosene tank, which is filled with kerosene (not shown) if the second drive 20 is to be used during the flight. In a particular embodiment, the gas turbine can be adapted to drive a generator in order to generate electrical energy to supply the electric motor of the first drive 18 .

Regarding 3 two operating modes B1 and B2 are described, which are used for flexible use of the aircraft 14. The operating modes B1 and B2 are described using several curves NB1, NB2, L, E1B1, E2B2, E12B1, E12B2, which are plotted in a coordinate system in which the X-axis 28 represents a range of the aircraft 14 and the Y-axis 30 represents a relative proportion of the maximum take-off weight of the aircraft 14 (MTOM: Maximum Take Off Mass). The X-axis 28 shows purely exemplary values in kilometers. Other values may apply to other aircraft with other engines. The values of the Y-axis 30 are normalized to the maximum take-off weight of the aircraft, ie the value 1.0 represents the maximum take-off weight that must not be exceeded. In 3 For example, curve L represents the empty weight of the aircraft 14, which is approximately 57 percent of maximum takeoff weight (0.57). The empty weight is constant regardless of the range of the aircraft 14.

In the operating mode B1, the first drive 18 is generally provided as the primary drive and the first energy supplier is provided as the primary energy supplier. The second drive 20 and the second energy supplier 24 are generally provided as a secondary drive or secondary energy supplier. If the aircraft 14 is operated in the first operating mode B1, the aircraft 14 can be operated completely electrically up to a maximum possible range, i.e. by means of the first drive 18, which is supplied by the first energy supplier 22. If the maximum possible electrical range is exceeded, the aircraft is operated using the second drive 20 or the second energy supplier 24 . This is described in more detail below with reference to curves NB1, E1B1 and E12B1.

The curve NB1 represents the available payload NB1 for the aircraft 14 when the aircraft is operated in the first operating mode B1. It can be seen that the curve NB1 is constant at a value of 0.2 between a range of 0 to approx. 350 km, ie a payload of 20% of the maximum take-off weight can be transported over the first 350 km. Within this range, the aircraft 14 is operated as far as possible and in particular completely electrically, with only a reserve of kerosene being fueled. However, a first battery with a relatively high storage capacity must be carried in order to enable fully electric flight. The mass of the first battery is about 21 percent of the maximum take-off weight. The total mass of the aircraft 14, including the empty mass of the aircraft 14 and the mass of the first battery, is therefore approximately 78 percent. This is illustrated by the curve E1B1, which is constantly 78 percent of the maximum take-off weight because the mass of the first battery is independent of the amount of energy stored in the first battery. A quantity of kerosene is provided as a reserve, which amounts to approx. 2-3 percent of the maximum take-off weight. The total mass, including the empty mass of the aircraft 14, the mass of the first battery and the mass of the reserve kerosene, is therefore approximately 80 percent of the maximum take-off weight. This is illustrated by curve E12B1, which is essentially constant at 80 percent in the first section up to 350 km. In this area, the aircraft is primarily operated electrically, with the kerosene drive 20 being activated when the first battery begins to be exhausted. In this way, the maximum payload of 20% for the first operating mode B1 can be transported safely and efficiently up to a range of approximately 350 km. Beyond this range, more kerosene is tanked at the expense of the maximum available payload in order to increase the range accordingly. It can be seen that the Curve E12B1, ie the total mass including kerosene increases as the payload NB1 decreases. This ensures that the maximum take-off weight is not exceeded. The aircraft 14 can thus be used for ranges of up to 2200 km, provided that a reduction in the payload, for example with a smaller number of passengers, can be accepted.

In the second operating mode B2, the ranking of the drives and energy suppliers is exactly reversed, i.e. the first drive 18 is generally provided as a secondary drive and the first energy supplier as a secondary energy supplier. By contrast, the second drive 20 and the second energy supplier 24 are generally provided as the primary drive or primary energy supplier. When the aircraft 14 is operated in the second operating mode B2, the aircraft 14 can be operated up to a maximum possible range of approximately 900 km with a maximum payload of 30 percent. Within this range, the aircraft 14 is mainly operated by means of the second drive 20, i.e. by kerosene, with the first drive 18 only being used as needed to support the second drive 20, e.g. when the aircraft 14 takes off. This is explained in more detail below using curves NB2 , E1B2 and E12B2 explained. The curve E1B2 represents the total mass of the aircraft, including the empty mass and the weight of a second battery, which has a lower storage capacity than the first battery of the first operating mode and accordingly also has a lower mass. Therefore, the curve E1 B2 with a constant value of 63% (0.63) is below the corresponding curve E1B1 of the first operating mode B1. The curve NB2 represents the payload available for the aircraft 14 when the aircraft is operated in the second operating mode B2. It can be seen that the curve NB2 is constant at a value of 0.3 between a range of 0 to about 900 km, i.e. a payload of 30% of the maximum take-off weight can be transported over the first 900 km, as explained. Within this range, more kerosene must be refueled as the range increases. This relationship is illustrated by curve E12B. The curve E12B2 indicates the total mass of the aircraft 14, including the empty mass of the aircraft 14, the mass of the second battery and the mass of the kerosene tanked. It can be seen that beyond a range of up to 900 km, within which a maximum payload of 30 percent can be transported, the available payload decreases depending on the amount of additional kerosene tanked, see curves NB2 and E12B2. In other words, the maximum take-off weight is reached at a range of 900 km, so that as the range continues to increase, the available payload has to be reduced in favor of the additional kerosene in order not to exceed the maximum take-off weight. The aircraft 14 can thus be used for ranges of up to 3500 km, provided that a corresponding reduction in the payload, e.g. with a smaller number of passengers, can be accepted.

In 3 it can also be seen that the curves E12B1 and E12B2 each have a constant area near the maximum possible range. The maximum capacity of the kerosene tanks of the aircraft 14 is reached in each of these areas, ie the amount of kerosene cannot be increased any further. For this reason, when the maximum range is fully utilized, disproportionately less payload can be transported, so that the curves NB1 and NB2 fall particularly sharply in the area of the maximum capacity of the kerosene tanks. It can also be seen that the maximum capacity of the kerosene tanks in operating mode B1 is slightly lower than in operating mode B2. This circumstance is due to the increased space requirement for the first battery, which has a greater mass than the second battery, which is provided for the second operating mode.

It is understood that the in 3 The values and relationships shown are only examples and other values and relationships may apply to other aircraft with different configurations, in particular with regard to the drives and energy suppliers.

Reference List

10

determining a mode of operation

12

Operating an aircraft depending on the particular mode of operation

14

airplane

16

wing

18

first drive

20

second drive

22

first energy supplier

24

second energy supplier

26

control device

28

Range

30

Mass relative to maximum take-off weight

NB1

Payload in the first mode of operation

NB2

Payload in the second mode of operation

L

empty mass

E1 B1

Mass comprising empty mass and mass of the first energy supplier in the first operating mode

E12B1

Mass comprising empty mass and masses of the first and second energy suppliers in the first operating mode

E1 B2

Mass comprising empty mass and mass of the first energy supplier in the second operating mode

E12B2

Mass comprising empty mass and masses of the first and second energy suppliers in the second operating mode

Claims (27)

Method for operating an aircraft (14), the aircraft (14) having at least one engine (18, 20) for propelling the aircraft (14), wherein to supply the engine (18, 20) a plurality of energy suppliers (22 , 24) are provided, the method comprising: - Determining an operating mode (B1, B2), wherein the operating mode (B1, B2) comprises at least one predefined rule for the supply of the drive (18, 20) by the energy suppliers (22, 24); - Operating the aircraft (14) depending on the specific operating mode (B1, B2), in which the supply of the drive (18, 20) by the energy suppliers (22, 24) is subject to the predefined rule. procedure after claim 1 , wherein determining the operating mode (B1, B2) further comprises: - selecting one of a plurality of operating modes (B1, B2), each of the operating modes (B1, B2) having at least one of a plurality of predefined rules for supplying the drive (18, 20 ) by the multiple energy suppliers (22, 24), wherein the predefined rules differ between some of the operating modes (B1, B2). procedure after claim 1 or 2 , wherein in the specific operating mode (B1, B2) the supply of the drive (18, 20) by at least one of the energy suppliers (22, 24) depending on at least one operating parameter of the aircraft (14), preferably an operating scheme of the aircraft (14) , released, blocked and/or modified. Method according to one of the preceding claims, wherein in the specific operating mode (B1, B2) the contribution of at least one of the energy suppliers (22, 24) to the supply of the drive (18, 20) depending on at least one operating parameter of the aircraft (14) , preferably an operating scheme of the aircraft (14). procedure after claim 3 or 4 , wherein the at least one predefined operating parameter represents at least one of the following: operating distance (28), operating status, availability of at least one of the energy suppliers during operation, time information, flight segment, weight of the aircraft (30). Method according to at least one of the preceding claims, in which the operating mode (B1, B2) is determined as a function of at least one determination parameter, the determination parameter preferably representing one of the following: operating distance (28), weight of the aircraft, maximum landing weight, maximum take-off weight ( 30), aircraft payload (NB1, NB2), number of passengers, availability of at least one of the energy suppliers at an airport, operating time. Method according to one of the preceding claims, wherein in the specific operating mode (B1, B2) at least one of the energy suppliers (22, 24) is provided as the primary energy supplier and at least one other of the energy suppliers (22, 24) is provided as the secondary energy supplier, the secondary energy supplier preferably being a reserve energy supplier for the primary energy supplier. Method according to one of the preceding claims, wherein determining the operating mode (B1, B2) comprises that one of a plurality of operating modes (B1, B2) is selected, the operating modes (B1, B2) comprising a first and at least a second operating mode, wherein the energy suppliers (22, 24) comprise a first and at least one second energy supplier, wherein - In the first operating mode (B1), the first energy supplier (22) is provided as the primary energy supplier and the second energy supplier (24) is provided as the secondary energy supplier, and - In the second operating mode (B2), the second energy supplier (24) is provided as a primary energy supplier and the first energy supplier (22) is provided as a secondary energy supplier. Method according to one of the preceding claims, wherein the energy suppliers comprise a first, second and third energy supplier (22, 24), wherein in the specific operating mode (B1, B2) the first energy supplier is provided as a primary energy supplier and the second and third energy suppliers are provided as secondary energy suppliers, with the secondary energy suppliers preferably forming reserve energy suppliers for the primary energy supplier. Method according to one of the preceding claims, wherein the drive (18) comprises at least one electric motor, wherein in the specific operating mode (B1, B2) at least some of the energy suppliers (22, 24) are provided for supplying the electric motor, wherein the some energy suppliers (22, 24) preferably include hydrogen and methanol. Method according to one of the preceding claims, wherein the drive comprises a plurality of drives (18, 20) that differ from one another, the drives (18, 20) comprising a first drive (18) and a second drive (20), wherein in the specific operating mode (B1, B2) at least one of the energy suppliers (22, 24) is provided to supply the first drive (18) and another of the energy suppliers (22, 24) to supply the second drive (20), wherein the first drive (18) preferably comprises an electric motor and wherein the second drive (20) preferably comprises a gas turbine. procedure after claim 11 , wherein in the specific operating mode (B1, B2) - the first drive (18) is provided as a primary drive and the second drive (20) as a secondary drive or - the first drive (18) is provided as a secondary drive and the second drive (20) is provided as a secondary drive . procedure after claim 11 , wherein determining the operating mode (B1, B2) comprises selecting one of a plurality of operating modes (B1, B2), the operating modes (B1, B2) comprising a first and at least one second operating mode, wherein in the first operating mode (B1 ) the first drive (18) is provided as the primary drive and the second drive (20) as the secondary drive, with the secondary drive preferably forming a reserve drive for the primary drive, and with the first drive (18) as a secondary drive and the second drive (20) is provided as a primary drive, with the secondary drive preferably forming a support drive for the primary drive. Method according to at least one of the preceding claims, wherein one of the energy suppliers (22, 24) comprises at least one electrical energy store which can be flexibly mounted on the aircraft (14) in order to supply the drive (18, 20) with electrical energy. Method according to at least one of Claims 1 until 13 , wherein one of the energy suppliers optionally comprises one of a plurality of electrical energy storage devices, wherein the energy storage devices can each be mounted flexibly on the aircraft (14) in order to supply the drive (18, 20) with electrical energy, the storage capacity of the plurality of energy storage devices differing at least partially differ from each other and / or wherein the storage capacity of at least some of the plurality of energy storage is at least substantially the same. Method according to at least one of the preceding claims, wherein one of the energy suppliers (22, 24) comprises a first energy carrier which can be accommodated in a first energy carrier store of the aircraft (14), the first energy carrier store being permanently connected to the aircraft (14) or flexibly connected to it the aircraft (14) can be mounted in order to supply the drive (18, 20) with the first energy carrier. procedure after Claim 16 , wherein another of the energy suppliers (22, 24) comprises a second energy carrier which can be accommodated in a second energy carrier store of the aircraft, the second energy carrier store being permanently connected to the aircraft or being flexibly mountable on the aircraft in order to activate the drive (18, 20 ) to supply with the second energy source. Method according to at least one of the preceding claims, wherein the drive (18, 20) forms a flight drive of the aircraft (14). Method according to at least one of the preceding claims, the method further comprising: Providing the energy suppliers (22, 24) depending on the specific operating mode (B1, B2), so that the energy suppliers (22, 24) during operation of the aircraft (14) to supply the drive (18, 20) depending on the predefined Rule of the specific operating mode (B1, B2) are available. procedure after claim 19 , wherein the provision of the energy suppliers (22, 24) comprises at least one of the following method steps: - dismantling at least one first electrical energy store from the aircraft (14); - Mounting at least one second electrical energy store on the aircraft (14); - Dismantle at least one first energy carrier aircraft memory (14); - Mounting at least one second energy carrier storage on the aircraft (14); - Filling of the mounted second energy carrier store and/or a fixed energy carrier store of the aircraft (14) with at least one energy carrier. procedure after claim 19 or 20 , wherein the provision of the energy supplier differs between several operating modes depending on the specific operating mode. Control device (26) for operating an aircraft (14), the aircraft (14) having at least one drive (18, 20) for propelling the aircraft (14), with the drive (18, 20) being supplied with a plurality of different Energy suppliers (22, 24) are provided, wherein the control device (26) is designed to carry out the method according to one of the preceding claims. Computer program comprising instructions which, when the computer program is executed by a computer, cause it to carry out the steps of the method according to at least one of Claims 1 until 20 to carry out at least partially. Aircraft (14) with at least one engine (18, 20) for propelling the aircraft (14), with several energy suppliers (22, 24) differing from one another being provided for supplying the engine (18, 20), with the aircraft (14 ) is adapted to, with the method according to at least one of Claims 1 until 20 to be operated. Airplane (14) to Claim 24 , wherein the aircraft (14) has a control device (26). Claim 21 having. Airplane (14) to Claim 24 or 25 , wherein the at least one drive comprises a first drive (18) and a second drive (20), wherein the first drive (18) comprises at least one electric motor and wherein the second drive (20) comprises at least one gas turbine. Aircraft (14) according to at least one of claims 24 until 26 , wherein the aircraft (14) has a first energy carrier store for accommodating a first of the energy suppliers and wherein the aircraft (14) has a second energy carrier store for accommodating a second of the energy suppliers, the drive (18, 20) being adapted for this purpose during flight operations to be supplied by the first and second energy supplier.

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