Apparatus

Abstract

The present invention relates to a fuel management system 100 for an electrically powered aircraft. The system comprises a cryogenic fuel source 100; a refuel arrangement 120 and a conduit 111, 112, 1

Description

Technical Field The present invention is concerned with electrical propulsion systems and the configuration and arrangement of fuel provision for electrical propulsion systems within aircrafts. There are several alternative power sources options (that are much more environmentally friendly than typical combustion of fossil fuels) but these are not widespread. Moreover, such systems are not at present used in commercial-sized aircraft (e.g. 48 or 96 passenger aircraft and / or CS-25 related aircraft). The system used herein is directed toward use of green energy options within commercial-sized aircraft. Electrical propulsion systems have many benefits over combustion propulsion systems, particularly in relation to chemical emissions and the like. It is widely seen that electrical propulsion systems may render transport as more viable in a long term perspective. Electrical propulsion systems in aircraft in particular may use cryogenic substances as a source of chemical power for latter conversion into propulsion. Substances may be used for thermal exchange matters prior to being used in the production of thrust. Cryogenic substances may be contained in tanks in the aircraft and be refilled at airports after flights as per standard combustion fuels. Summary of the Invention Aspects of the invention are set out in the accompanying claims. In accordance with some embodiments described herein, there is provided a fuel management system for an electrically powered aircraft, the system comprising: a cryogenic fuel source; a refuel arrangement; a conduit providing fluid communication between the cryogenic fuel source and the refuel arrangement; a controller arrangement arranged to detect a stage of flight, wherein the stage of flight is at least one of: cruise; descent; landing; taxi; and, stationary, wherein the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel into the conduit upon detection of a stage of flight having changed to a predetermined stage of flight. The present management system provides an improved system for rapid turnaround at a terminus, such as an airport, for an aircraft that may be used with non-conventional fuels for improved environmental impact. The present system accounts for and mitigates against a danger of thermal shock by proactively cooling portions of the system that may be involved in a refuelling process. Use of the controller arrangement to detect a change in a stage of flight and then controls distribution of cryogen through the fuel management system allows for a highly proactive system that improves safety by reducing thermal shock and increases flight turnaround at airports. This arrangement therefore reduces delays experienced by some aircraft during refuelling and in turn improves the user experience of travelling on such vehicles. In use, when the aircraft is in final stages of flight, cryogen from a storage tank can be provided from the tank through various conduits to a refuelling arrangement. The cryogen cools the elements between the tank and element in which liquid cryogen can be provided to the tank from a supply. As such, once the aircraft has landed and is stationary and undergoing refuelling, the elements due to interact with the new cryogen being provided by the resupplying process are already pre-cooled. In this way, the likelihood of boil off of the new cryogen and thermal shock is reduced largely. This makes the refuelling more efficient and quicker enabling the aircraft to return to the air sooner. Furthermore, thermal shock can reduce the lifetime of components. As such, the present system further increases the lifetime of the system and reduces the cost of maintenance of the system. In examples, the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel into the conduit upon detection of a stage of flight having changed to descent, landing or taxi. While the system may provide cryogen during any stage of flight, it may be preferable to do so somewhat shortly prior to refuelling. In this example, this is any of descent, landing or taxi stages of flight. In the examples used herein, the complete stages of flight include stationary, taxi, take off, climb, cruise, descent, landing, taxi and lastly stationary again (upon final landing and arrival at for example, the terminal). In examples, the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel arrangement upon detection of a stage of flight having changed to a predetermined stage of flight. The process described herein may be a single process or may be a piecemeal process. Cryogen may be provided in stages through the elements of the system, this may be to further reduce the likelihood of thermal shock and to reduce the amount of cryogenic fuel gas that is produced during the cooling process of the cryogen cooling the conduit and refuel arrangement etc. In examples, the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel arrangement upon detection of a stage of flight having changed to landing or taxi. The full precooling process involves sending cryogen from the fuel source through the conduit and to the refuel arrangement. It may be advantageous to perform this somewhat close to refuelling. By performing the precooling process close to refuelling, the ambient heating for the conduit and refuel arrangement does not have time to increase the temperature of these elements significantly. It is also advantageous for this precool process to be gradual. If the precool process is conducted overly quickly, there may be increased chance for thermal shock and a rapid production of H2 gas which needs to be released in a careful and controlled manner. As such, there is a balance to strike as to the timings (in terms of flight stage) as to when to perform the precool process. In examples, the system further comprises a pump arranged to pump cryogenic fuel from the cryogenic fuel source in response to signals from the controller arrangement. It is advantageous to provide the system with improved control over the delivery of the cryogen (e.g. the cryogenic fuel) from the cryogenic fuel source to the conduit and the refuel arrangement. This can be improved with a controllable pump for controlled delivery of the fuel from the source. This can provide controlled flow such that, if desired, greater flow can be provided during certain periods of the precool process and less flow can be provided during other periods of the precool process. The pump allows provision of a pressure differential which may be required at the end of a flight where a large portion of the cryogenic fuel has been used in the production of thrust for the aircraft. In examples, the system further comprises at least one valve for controlling the direction of flow of cryogenic fuel from the cryogenic fuel source to the refuel arrangement. Control over the movement of cryogenic fuel and gaseous cryogen is advantageous in the present system. In controlling movement of the cryogenic fuel, the user can be provided with control over the elements that are to be cooled at e.g. particular stages of flight. Similarly, the valve may be used to control the movement and release of gaseous cryogen (e.g. as might be formed after the cooling of the conduit and refuel arrangement). In examples, the refuel arrangement further comprises an opening for receiving fuel into the fuel management system from an external environment. During refuelling, fuel may be provided through the opening (from e.g. a refuel supply truck or the like) to the fuel management system for storage in the cryogenic fuel source. In examples, the refuel arrangement further comprises: a refuel tank for temporarily holding cryogenic fuel; and, a gas vent. The gas vent is advantageous in releasing gaseous cryogen (e.g. gaseous hydrogen) from the system. Gaseous cryogen may be formed during the precool process where liquid cryogen performs a thermal exchange with the conduit and refuel arrangement. Controlled release of the gaseous cryogenic fuel is advantageous for improved safety. The gaseous cryogenic fuel may be hydrogen gas but may be any other suitable gas. In examples, the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel tank upon detection of a stage of flight having changed to a predetermined stage of flight. The refuel tank requires cooling as this tank receives the liquid cryogen during refuelling. The precooling of the refuel tank prior to receiving the refuelling liquid cryogen means that the refuelling cryogen will not boil off and therefore refuelling is much quicker. In examples, the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel tank upon detection of a stage of flight having changed to taxi or stationary. The refuel tank is one of the last elements to cool in the precool process, it being one of the furthest elements in the system from the cryogenic fuel source. As such, it is advantageous for this to occur shortly before refuelling begins. This may be, e.g., in the taxi or stationary stages of flight. In examples, wherein the conduit comprises a first portion and a second portion, the first portion arranged to provide fluid communication between the cryogenic fuel source and the opening, the second portion arranged to provide fluid communication between the cryogenic fuel source and the gas vent, the refuel arrangement further comprising a closeably openable connection arranged to connect the first portion and the second portion. The conduit may provide a loop from the opening of the refuel arrangement (where new cryogenic fuel is introduced to the system) to the cryogenic fuel source (where cryogenic fuel is stored and delivered for use in propulsion during movement and flight of the aircraft). The conduit may provide two routes to and / or from the refuel arrangement to the cryogenic fuel source. In use, this may be one for liquid movement (e.g. in during refuelling) and one for gaseous movement (e.g. out during precool and refuelling). As such, one conduit portion provides fluid communication between the cryogenic fuel source and the gas vent. The closeably openable connection may be a valve or the like that can join the two portions such that the conduit is a closed path from the cryogenic fuel source towards the refuel arrangement and then returning back to the cryogenic fuel source. In examples, the controller arrangement is arranged to provide an actuation signal to the closeably openable connection upon detection of a stage of flight having changed to a predetermined stage of flight, wherein the predetermined stage of flight is landing, taxi or stationary. Providing cryogen along the conduit when the closeably openable connection is closed allows the full flow path to be cooled prior to refuelling. This may be advantageously performed prior to refuelling and therefore associated with predetermined stages of flight. In examples, the system further comprises a condensing arrangement arranged to condense gaseous cryogen fuel into liquid cryogen fuel. It may be advantageous to reclaim some cryogen into the liquid state from the gaseous state in place of venting from the system. As such, the condensing arrangement may improve the overall efficiency of the system. In accordance with some embodiments described herein, there is provided an at least partially electrically powered aircraft comprising a fuel management system as per any of the above embodiments and examples. Such an aircraft may take advantageous of a highly efficient and environmentally friendly propulsion arrangement alongside having reduced turnaround time at airports. In accordance with some embodiments described herein, there is provided a method of controlling a fuel management system in an aircraft, the method comprising: i) detecting, by a controller arrangement, that a stage of flight has changed to a predetermined stage of flight, wherein the stage of flight is at least one of: cruise; descent; landing; taxi; and, stationary; ii) sending, by the controller arrangement, a signal to a cryogenic fuel source to provide a cryogenic fuel into a conduit, the conduit arranged to provide fluid communication between the cryogenic fuel source and a refuel arrangement; and, iii) providing, from the cryogenic fuel source, a cryogenic fuel into a conduit in response to the signal from the controller arrangement. This method provides a proactive approach for precooling such that turnaround times at airports are reduced. This method allows use of highly environmentally friendly propulsion and provides solutions to problems that are not presently used in modern systems. In examples, the method further comprises iv) detecting, by a controller arrangement, that a stage of flight has changed to a further predetermined stage of flight, wherein the stage of flight is at least one of: landing or taxi; v) sending, by the controller arrangement, a signal to a cryogenic fuel source to provide a cryogenic fuel cryogenic fuel through the conduit to the refuel arrangement; and, vi) providing, from the cryogenic fuel source, a cryogenic tuei tnrougn the conduit to the refuel arrangement in response to the signal from the controller arrangement. In examples, the method further comprises detecting, by the controller arrangement, that a 5 temperature of the conduit or refuel arrangement is above a predetermined temperature; and, sending, by the controller arrangement, a further signal to a cryogenic fuel source to provide further cryogenic fuel to at least one of the conduit and the refuel arrangement. In examples, the method further comprises detecting, by the controller arrangement, that the 10 concentration of a gaseous cryogen is over a predetermined level; sending, by the controller arrangement, a signal to the refuel arrangement to actuate a gas vent to vent gas from the fuel management system; actuating, by the refuel arrangement, a gas vent to vent gas from the fuel management system. Brief Description of the Drawings One or more embodiments of the invention will now be described, by way of example only, and with reference to the following figures in which: Figure 1 shows a schematic view of a fuel management system according to an example of the present disclosure; Figure 2 shows a schematic view of a fuel management system according to an example of the present disclosure; and, Figure 3 shows a flow diagram of a method according to an example of the present disclosure. Any reference to prior art documents in this specification is not to be considered an admission that such prior art is widely known or forms part of the common general knowledge in the field. As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”. The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples. It will also be recognised that the invention covers not only individual embodiments but also combination of the embodiments described herein. The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the spirit and scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc, other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future. Detailed Description An invention described herein relates to fuel management within an electrical powered aircraft. A particular system for this invention may be an aircraft with an electrically drivable motor or a drivable motor that is at least partially electrically driven. The aircraft may be propelled by a form of combustion of gaseous cryogen or the like (such as combustion of gaseous hydrogen or the like). For example, a propulsion source in the arrangements discussed may be fully or partially electrically powered. Partially powered aircraft may use thrust provided in part by electrical means and in part by combustion means. Figure 1 shows a simple schematic view of a fuel management system 100. The fuel management system 100 may be for an electrically powered aircraft. The system 100 comprises a cryogenic fuel source 110. The cryogenic fuel source 110 may be a tank that store liquid cryogen. The liquid cryogen may be liquid hydrogen (LH2) or the like. Alternatively, it may be liquefied natural gas (LNG), liquid methane, or any other suitable liquid cryogenic fuel. The system 100 comprises a refuel arrangement 120. The refuel arrangement 120 is arranged to be an interface between the cryogenic fuel source 110 and an external refilling system (such as might be included in a refuelling vehicle at an airport or the like). The refuel arrangement 120 therefore may include elements such as an opening to provide fluid communication between the inside of the system 100 (such as the cryogenic fuel source 110) and an external environment. The refuel arrangement 120 may be sized or configured to receive a refuelling pipe or the like that may be anticipated to provide liquid cryogen into the system 100. The refuel arrangement 120 may have a valve or may include a controllably closeable opening or the like to provide control over when the cryogenic fuel source 110 is in fluid communication with the external environment. It may be preferable for the refuel arrangement 120 to be in an open state shortly prior to refuelling and otherwise closed. The system 100 comprises a conduit 130 for providing fluid communication between the cryogenic fuel source 110 and the refuel arrangement 120. The conduit 130 may be a pipe or the like through which a fluid may pass from either of the cryogenic fuel source 110 and the refuel arrangement 120 to the other. The conduit 130 may include a series of portions, each offering a path from e.g. the cryogenic fuel source 110 to the refuel arrangement 120 (and / or vice versa). The system 100 comprises a controller arrangement 140. The controller arrangement 14U is arranged to detect a stage of flight. The controller arrangement 140 may detect such a stage of flight based on signals from sensors, detectors and operational characteristics such as altitude sensors, thrust demands, breaking demands, landing gear status, present velocity etc. The stage of flight in the present arrangement may be at least one of: cruise; descent; landing; taxi; and, stationary. In examples of the present system, a liquid cryogen is provided through the system 100 from the cryogenic source 110 to cool the conduit 130 and refuel arrangement 120. This is performed ahead of refuelling so that the incoming liquid cryogen is more efficiently received by the system 100. In this way, refuelling is quicker and the aircraft can return to providing flights sooner. Refuelling is more efficiently received as the incoming cryogenic fuel is not partly boiled off to cool the refuel arrangement 120 and conduit 130. As this system may be used prior to refuelling it may be referred to herein as “precooling”. This is the precooling of elements within the system 100 prior to refuelling. This precooling occurs prior to refuelling. As such, this may be preferentially prior to a stationary phase of flight, such as during descent, during landing or during taxi to the terminal. This may also occur during earlier phases of flight, however it is preferable to occur shortly before refuelling occurs so that there is less time in which parasitic thermal energy may increase the temperature of both the refuel arrangement 120 and the conduit 130. The controller arrangement 140 may be arranged to provide a signal to the cryogenic fuel source 110 to provide a cryogenic fuel into the conduit 130 upon detection of a stage of flight having changed to descent, landing or taxi. The aim of this arrangement is to provide more efficient refuelling as none (or very little) of the fuel used in refuelling is used to cool the refuelling arrangement 120 and the conduit 130. Instead, the system proactively provides “leftover” cryogenic fuel from the source 110 to precool these elements. This cryogenic fuel may be “leftover” as this is at or towards the end of a flight journey where there will be no further need for that fuel and it can be effectively used in thermal exchange functions. This may take place during any or all of descent, landing or taxi. In practice, it may be that this system operates to precool elements on each landing. It may be that this system operates to precool elements on landings where refuelling is anticipated. As such, where an aircraft can provide multiple flights prior to refuel, it may be advantageous to only perform the precool method disclosed herein where refuelling is anticipated. I ms may be anticipated by detecting that the total fuel in the aircraft has dropped below a predetermined level. The phase of flight selected for delivery of cryogenic fuel through the elements of the system 100 may be related to the time required for the cryogenic fuel to suitably cool the elements and the amount of time prior to refuelling. These timings can be controlled by the controller arrangement 140 as the controller arrangement 140 is aware of the stage of flight and therefore the likely amount of time between any one moment and the subsequent refuel stage. The controller arrangement 140 can control provision of cryogenic fuel to the conduit 130 during an earlier stage than the subsequent provision of cryogenic fuel to the refuel arrangement 120. Cryogenic fuel may be provided in stages through the elements of the system 100. This may be to reduce the likelihood of thermal shock to the elements. If the cryogenic fuel is provided quickly to all elements the likelihood of thermal shock is increased. Therefore, a more controlled gradual approach may be more reliable for reduction of likely occurrence of thermal shock. A controlled gradual delivery of cryogenic fuel may also reduce the volume of cryogenic fuel gas that is produced per unit time during the cooling process of the cryogen cooling the conduit and refuel arrangement etc. Large gas generation over a short time is harder to deal with than the same generation over a longer time. Therefore a slower controlled delivery of cryogenic fuel over different flight stages may be advantageous. The system 100 may comprise a pump to provide a pressure differential to assist in the delivery of the cryogenic fuel from the source 110. The fuel may be consumed during flight and therefore at landing, there may not be a large remaining amount of cryogenic fuel. As such, to get a flow of cryogenic fuel from the source 110 a pump may be advantageous. The pump may provide an advantageous pressure differential. The pump may be controlled by the controller arrangement 140 which may be aware of the remaining level of cryogenic fuel in the source 100 and therefore the level of pumping required to reach the conduit 130 and the refuel arrangement 120. The system 100 may use a valve to guide and control movement of the cryogenic fuel around the system 100. Valves are advantageous for controller movement of fluids and so may be advantageous in the present system 100. The refuel arrangement 120 may comprise an opening for receiving fuel in the fuel management system 100 from an external environment, such as a refuel vehicle at an airport. The opening may include a cover that can block the opening (for example wnen tne vemcie is not being refuelled). The cover may be controlled by the controller arrangement 140 such that the system 100 is closed to the external environment other than during refuelling (or perhaps maintenance or the like). The opening may be sized or configured to receive refuelling equipment. The opening may have a latch or the like for securing a refuelling pipe for ease of refuelling. Referring now to Figure 2, there is shown an example of a simple schematic view of a fuel management system 100. The fuel management system 100 of Figure 2 has a number of elements in common with the system 100 of Figure 1, these will not be discussed again in detail for expediency. The fuel management system 100 of Figure 2 has a number of elements shown in more detail, these will be discussed below. The system 100 of Figure 2 has a cryogenic source 110 and a refuel arrangement 120. The system also has a conduit (shown connecting the source 110 to the arrangement 120). The conduit includes a few pathways including paths indicated 111, 112, 112a, 113, 113a, 132. The refuel arrangement 120 include opening 121 for allowing liquid fuel to enter the system 100. The arrangement 120 includes a gas vent 122 for allowing cold gas to exit the system 100. In use, the gaseous cryogen may be generated in the tank 110 of cryogen and exit the system 100 via pathways of the conduit to the exit 122. During refilling, liquid fuel is provided via the opening 121 and is transferred through the conduit pathways to the tank 110. The refuel arrangement 120 shown further comprises a refuel tank 125. This may temporarily hold cryogenic fuel prior to passing the fuel to the tank 110. The system shown has a series of valves 123,133 and a pump 131. These assist in controlling the flow of the liquid fuel. There may be a controllable connection 123 between the pathways of the conduit. Prior to refuelling, the controller arrangement (not shown in Figure 2) may connect the connection 123 so that the pathways do not connect to the opening 121 and the gas vent 122. The cryogenic fuel from the tank 110 (cryogenic source) may be provided through the conduit entirely, to the refuel arrangement 120 and back to the tank 110. In this way, the full length of conduit and elements of the refuel arrangement 120 are precooled ahead of cryogenic fuel being provided to the system 100. The gaseous cryogenic fuel produced during this process may be latterly removed via opening the gas vent and venting the gaseous cryogenic fuel. While the aircraft may have some storage on-board for gaseous cryogenic fuel, during the latter stages of flight it may be organisationally more straightforward to vent the gas after the precool has been completed. The processes discussed herein may be related to stages of flight as noted above. This may allow a controller to control the cooling of the system as best befits the present stage of flight and therefore the proximity to refuelling. While the present methods and use processes may be employed during flight such as climb or cruise, it is anticipated that the most benefits from this arrangement may occur during use closely prior to refuelling. As such, the more relevant phases of flight appear to be descent, landing, taxi and park (stationary). In examples, the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel tank upon detection of a stage of flight having changed to taxi or stationary. In this, the full precooling (up to and including the refuel arrangement) occurs somewhat closely prior to refuelling. This stage may be during taxi (post landing) or stationary prior to the arrival of the refuelling vehicle. In this way, large amounts of time can be saved during refuelling and therefore the aircraft may have a shorter turnaround time. In this way, passengers are impacted less and have an improved experience of flight travel. The elements herein may be located in or use vacuums for improved thermal properties. The conduit in Figure 2 has at least two portions. The first portion is arranged to provide fluid communication between the cryogenic fuel source 110 and the opening 121. The second portion is arranged to provide fluid communication between the cryogenic fuel source 110 and the gas vent 122. The refuel arrangement 120 in the example of Figure 2 has a closeably openable connection 123 arranged to connect the first portion and the second portion as noted above. When the closeably openable connection 123 is closed, the system 100 can provide liquid cryogen along both the liquid route (from tank 110 to opening 121, or vice versa) and what is normally the gas route (from tank 110 to vent 122, or vice versa). This provides full precooling of the system 100 and is therefore a particularly advantageous version of the present disclosure. This may be seen as operating the device somewhat “in reverse" nowever tne advantages from a thermal standpoint can be seen. The system 100 may include a condensing arrangement arranged to condense gaseous cryogen fuel into liquid cryogen fuel for additional fuel efficiencies. The present system 100 may be used in an aircraft or any other vehicle. For other vehicles, the predetermined stages of flight may be considered more accurately as predetermined stages of travel. For example, automobiles may consider parking at a refuel station as equivalent to the landing procedure of an aircraft. For ships, this may be the docking process. In the specific example of Figure 3, there is shown a distribution system 130 (optional). This as a liquid pump 131, bleed line 132 and one way valve 133. The distribution system 130 may be part of the refuel arrangement 120. Referring now to Figure 3, a method 300 according to an example of the present disclosure is shown as a flow diagram. The method 300 has three steps 305, 310, 315. In a first step 305, a controller detects that a stage of flight has changed to a predetermined stage of flight. The stage of flight is at least one of: cruise; descent; landing; taxi; and, stationary. Each of these stages of flight are somewhat close to when a refuel event may occur and therefore there may be an advantage from precooling the system shown and described above. In a second step 310, the controller sends a signal to a cryogenic fuel source to provide a cryogenic fuel into a conduit. The conduit is arranged to provide fluid communication between the cryogenic fuel source and a refuel arrangement. In a third step 315, a cryogenic fuel is provided from the cryogenic fuel source into a conduit in response to the signal from the controller arrangement. In this way, the cryogenic fuel source provides a cryogen into the conduit to cool the conduit. This is part of the precooling system and method disclosed herein. By performing this step prior to refuelling, the system provides a swifter and more efficient refuel process. The stages of flight that are prior to refuelling include those listed above: cruise; descent; landing; taxi; and, stationary. While the refuelling occurs while the aircraft is stationary, this is more accurately after the flight has concluded. In such an instance, the aircraft may be in a standby mode or an off mode rather than still in a stage of a flight. This method may be further expanded by further detections (or determinations or the like) of stages of flight by the controller arrangement and subsequent instructions to the cryogenic source to provide further amounts of cryogenic fuel through the system. In use, the method leads to a fully cooled system prior to refuelling. As mentioned above, it is desirable for the precool stage to conclude shortly before the beginning of the refuelling stage. This leaves less time in which parasitic and environmental thermal energy to warm up the conduit and refuel arrangement. As such, the controller arrangement is designed to know the estimated time for cooling these elements and the time until refuelling. With this, the controller arrangement may schedule the precool in a suitable period of time. As also noted above, the controller arrangement may account for reducing thermal shock and producing gaseous cryogenic fuel by ensuring a controlled delivery of cryogenic fuel to the conduit and refuel arrangement and then venting the gaseous cryogenic fuel if required. The system herein reduces wait times for refuelling. The system herein is highly efficient and uses environmentally friendly propulsion in vehicles that typically do not use such green fuels. These systems are more beneficial for the environment over present systems that utilise gas turbine and combustion of fuels.

Claims

1. A fuel management system for an electrically powered aircraft, the system comprising: a cryogenic fuel source;a refuel arrangement;a conduit providing fluid communication between the cryogenic fuel source and the refuel arrangement;a controller arrangement arranged to detect a stage of flight, wherein the stage of flight is at least one of: cruise; descent; landing; taxi; and, stationary,wherein the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel into the conduit upon detection of a stage of flight having changed to a predetermined stage of flight.

2. A fuel management system according to claim 1, wherein the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel into the conduit upon detection of a stage of flight having changed to descent, landing or taxi.

3. A fuel management system according to claim 1 or 2, wherein the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel arrangement upon detection of a stage of flight having changed to a predetermined stage of flight4. A fuel management system according to claim 3, wherein the controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel arrangement upon detection of a stage of flight having changed to landing or taxi.

5. A fuel management system according to any preceding claim, further comprising a pump arranged to pump cryogenic fuel from the cryogenic fuel source in response to signals from the controller arrangement.

6. A fuel management system according to any preceding claim, further comprising at least one valve for controlling the direction of flow of cryogenic fuel from the cryogenic fuel source to the refuel arrangement.

7. A fuel management system according to claim 6, wherein the icIUCI ai I QI I^CI I Id IL comprises an opening for receiving fuel into the fuel management system from an external environment.

8. A fuel management system according to claim 7, wherein the refuel arrangement further comprises:a refuel tank for temporarily holding cryogenic fuel; and, a gas vent.

9. A fuel management system according to claim 8, whereinthe controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel tank upon detection of a stage of flight having changed to a predetermined stage of flight.

10. A fuel management system according to claim 9, whereinthe controller arrangement is arranged to provide a signal to the cryogenic fuel source to provide a cryogenic fuel through the conduit to the refuel tank upon detection of a stage of flight having changed to taxi or stationary.

11. A fuel management system according to any of claims 8-10, wherein the conduit comprises a first portion and a second portion,the first portion arranged to provide fluid communication between the cryogenic fuel source and the opening,the second portion arranged to provide fluid communication between the cryogenic fuel source and the gas vent,the refuel arrangement further comprising a closeably openable connection arranged to connect the first portion and the second portion.

12. A fuel management system according to claim 11, wherein the controller arrangement is arranged to provide an actuation signal to the closeably openable connection upon detection of a stage of flight having changed to a predetermined stage of flight,wherein the predetermined stage of flight is landing, taxi or stationary.

13. A fuel management system according to any preceding claim, further comprising a condensing arrangement arranged to condense gaseous cryogen fuel into liquid cryogen fuel.

14. An at least partially electrically powered aircraft comprising a fuei 11 icai ica^ci i ici it oyoici 11 according to any of claims 1-13.

15. A method of controlling a fuel management system in an aircraft, the method comprising:i) detecting, by a controller arrangement, that a stage of flight has changed to a predetermined stage of flight, wherein the stage of flight is at least one of: cruise; descent; landing; taxi; and, stationary;ii) sending, by the controller arrangement, a signal to a cryogenic fuel source to provide a cryogenic fuel into a conduit, the conduit arranged to provide fluid communication between the cryogenic fuel source and a refuel arrangement; and,iii) providing, from the cryogenic fuel source, a cryogenic fuel into a conduit in response to the signal from the controller arrangement.

16. A method according to claim 15, further comprising:iv) detecting, by a controller arrangement, that a stage of flight has changed to a further predetermined stage of flight, wherein the stage of flight is at least one of: landing or taxi;v) sending, by the controller arrangement, a signal to a cryogenic fuel source to provide a cryogenic fuel cryogenic fuel through the conduit to the refuel arrangement; and,vi) providing, from the cryogenic fuel source, a cryogenic fuel through the conduit to the refuel arrangement in response to the signal from the controller arrangement.

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