Patent Publication Number: US-2023145112-A1

Title: Aircraft

Description:
FIELD 
     The present disclosure relates to an aircraft with a detachable payload module. 
     BACKGROUND 
     High altitude long endurance (HALE) unmanned aircraft have been devised. These typically have long wingspans and low drag to improve their ability to operate efficiently for weeks or months at altitudes in excess of 15 km. 
     There are relatively strict weight requirements for the HALE aircraft in order for them to operate for long periods of time at high altitude. As such, many traditional aspects of an aircraft are not included in a HALE aircraft in flight. One such aspect is landing gear, which is designed to separate from the HALE aircraft during take-off to reduce weight. 
     The return of a HALE Vehicle back to the ground with its payload module intact is hindered by the lack of landing gear. 
     Therefore, there is a need for an apparatus in which the HALE vehicle and/or payload can be returned to ground in an intact state. 
     SUMMARY 
     According to a first aspect of the present disclosure, there is provided an aircraft comprising: a fuselage; and a payload module coupled to the fuselage, the payload module comprising one or more data storage devices, wherein the payload module is configured to be decoupled from the fuselage during flight upon receipt of a de-coupling input. 
     Decoupling the payload module from the fuselage during flight enables the payload module, which includes one or more data storage devices, to be landed independently of the rest of the aircraft. 
     In one example, the aircraft includes a de-coupling element configured to decouple the payload module from the fuselage. 
     The de-coupling element may comprise one or more electromagnets that are configured to couple the payload module to the fuselage when energised, wherein the one or more electromagnets are configured to be de-energised to decouple the payload module from the fuselage upon receipt of a de-coupling input. Electromagnets provide a relatively low weight solution for coupling the payload module to the fuselage and a mechanism for de-coupling the payload module from the fuselage. 
     In one example, the one or more electromagnets may be configured to provide a holding force of at least 150N when energised to couple the payload module to the fuselage. 
     In one example, the one or more electromagnets comprises a strip electromagnet that is configured to distribute the load of the payload module across the fuselage. Providing an electromagnet in the form of a strip means that the load may be spread across a relatively larger width and therefore reduces high stress points on the fuselage. 
     In one example, the de-coupling element comprises an electro-mechanical release mechanism to decouple the payload module from the fuselage upon receipt of a de-coupling input. 
     The electro-mechanical release mechanism may comprise a pin puller. 
     The electro-mechanical release mechanism may comprise a separate nut release mechanism. 
     In one example, the de-coupling element comprises a pyrotechnic hold down and release mechanism, wherein a pyrotechnic impulse is used to decouple the payload module from the fuselage. Pyrotechnic impulses are reliable mechanisms for de-coupling elements during flight. 
     In one example, the aircraft comprises an aerofoil that is covered by the payload module when the payload module is coupled to the fuselage and exposed to oncoming air when the payload module is decoupled from the fuselage. The aerofoil aids in landing the remainder of the aircraft after the payload module  102  has been de-coupled. 
     In one example, the aircraft comprises a HALE vehicle. 
     In one example, the payload module comprises control avionics for the aircraft. 
     It will be appreciated that features described in relation to one aspect of the present disclosure can be incorporated into other aspects of the present disclosure. For example, an apparatus of the disclosure can incorporate any of the features described in this disclosure with reference to a method, and vice versa. Moreover, additional embodiments and aspects will be apparent from the following description, drawings, and claims. As can be appreciated from the foregoing and following description, each and every feature described herein, and each and every combination of two or more of such features, and each and every combination of one or more values defining a range, are included within the present disclosure provided that the features included in such a combination are not mutually inconsistent. In addition, any feature or combination of features or any value(s) defining a range may be specifically excluded from any embodiment of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure will now be described by way of example only and with reference to the accompanying drawings. 
         FIG.  1    is a perspective view of a HALE vehicle; 
         FIG.  2    is a plan view of a HALE vehicle; 
         FIG.  3    is a plan view of a HALE vehicle in which the payload module is decoupled from the fuselage; 
         FIGS.  4 A to  4 C  shows an example of a decoupling element; and 
         FIG.  5    is a plan view of a HALE vehicle in which the payload module is decoupled from the fuselage. 
     
    
    
     For convenience and economy, the same reference numerals are used in different figures to label identical or similar elements. 
     DETAILED DESCRIPTION 
     High altitude aircraft may include a payload module that includes a data storage device, and a fuselage. In some scenarios, the high altitude aircraft jettison the take-off gear during take-off and so it becomes very difficult to land the aircraft in an intact state. The invention enables the payload module  102  to be decoupled from the fuselage  104  during flight, such that the payload module  102  including the data storage device can be safely landed and possibly re-used in future. 
     Generally, embodiments herein relate to an aircraft and a decoupling element for detaching a payload module from the fuselage of the aircraft. 
       FIG.  1    shows an illustrative example of a vehicle  100 , specifically a HALE unmanned aeroplane. The present invention is particularly applicable to vehicles that operate with low weight restrictions. 
     The vehicle  100  includes a wing member  106 . In one example, the wingspan of the wing member  106  is approximately 35 metres and has a relatively narrow chord (i.e. of the order 1 metre). The wing member  106  is coupled to a fuselage  104 . To aerodynamically balance the vehicle  100 , a horizontal tail plane  108  and a vertical tail fin (or vertical stabilizer)  110  are coupled to the rear of the fuselage  104 . A payload module  102  is coupled to the front of the fuselage  104 , i.e. the nose of the vehicle  100 . An engine having a propeller may be mounted to the wing member  106  on both sides of the fuselage  104 . The engines may be powered by a combination of solar panels mounted to the upper surfaces of the wing member  106  and batteries disposed inside the fuselage  104  and/or wing member  106 . 
     The vehicle  100  is of lightweight construction. For example, the fuselage  104 , wing member  106 , payload module  102 , tail plane  108  and tail fin  110  may be made of a monocoque carbon fibre laminate skin structure. In other words, the skin forms the aircraft&#39;s body. In other embodiments, the body is substantially made of a light weight metal, such as titanium, titanium alloy, aluminium, aluminium alloy. In one example, the body is made substantially of fiberglass. 
       FIG.  2    shows an example of a vehicle  100 , such as a HALE aircraft. In  FIG.  2   , the payload module  102  includes one or more data storage devices  113 . The one or more data storage devices are configured to store data obtained during the flight of the HALE aircraft, for example, data relating to video, images, flight details or other recorded information. The data may be sensitive data, such as intelligence on an adversary. In one example, the payload module  102  includes the control avionics  112  for the aircraft. In one example, the control avionics  112  receives flight control data from an external source and the control avionics  112  uses the received data to control the flight of the aircraft  100 . In other examples, the control avionics  112  generates the flight control data in situ. 
     The vehicle  100  may include a decoupling element  114 . The decoupling element  114  may be located between the payload module  102  and the fuselage  104  to enable the payload module  102  to be coupled to the fuselage  104  in a first, flight condition. The decoupling element  114  is also configured to decouple the payload module  102  from the fuselage  104  in the event of a decoupling signal being initiated. 
     Decoupling the payload module  102  from the fuselage  104  enables the payload module  102 , which may contain sensitive equipment such as the one or more data storage devices  113 , to be landed separately to the rest of the vehicle  100 . For example, the payload module  102  may include one or more parachutes that may be activated following separation from the fuselage  104  such that the payload module  102  can be landed in a safe manner. In other words, the payload module  102  may be decoupled from the fuselage  104  mid-flight and land separately from the rest of the aircraft  100 . This is particularly important as there is an increased chance that the one or more data storage devices  113  and/or the control avionics  112 , which are part of the payload module  102 , may be recovered and reused. In other words, the decoupling aims to avoid damaging sensitive equipment within the payload module  102 . 
     It is desirable to also return the rest of the vehicle  100  to the ground after the payload module  102  has been decoupled. If the vehicle  100 , including the payload module  102 , were to be brought back to the ground as a single piece, then there is a higher risk that the payload module  102 , including sensitive equipment such as the one or more data storage devices  113  and/or control avionics  112 , would be damaged during landing as HALE aircraft do not have landing gear. 
       FIG.  3    shows an example in which the payload module  102  has been decoupled from the fuselage  104  mid-flight. In this example, the decoupling element  114  has been activated to decouple the payload module  102  from the fuselage  104 . Examples of the decoupling element  114  are discussed in more detail below. 
     During flight, the control avionics  112  may receive a decoupling input to decouple the payload module  102  from the fuselage. The control avionics  112  may be configured to control the decoupling element  114  to decouple the payload module  102  from the fuselage  104 . 
       FIG.  4    shows an example of the decoupling element  114 . In one example, the decoupling element  114  comprises a base plate  116  to which one or more electromagnets  118  are attached. The base plate  116  may be coupled to the payload module  102  or to the fuselage  104 . 
     In this example, the one or more electromagnets  118  may be magnetically coupled with one or more corresponding magnets that are attached to the other one of the payload module  102  and the fuselage  104 . In  FIG.  3   , the decoupling element  114  is attached to the payload module  102 . In this example, the one or more electromagnets  118  would be coupled with the payload module  102  and magnetically coupled with one or more magnets (not shown) that are attached to the fuselage  104 . 
     In other examples, the baseplate  116  is not required and the electromagnets  118  are directly coupled to the payload module  104  (or the fuselage  102 ). 
     To decouple the payload module  102  from the fuselage  104 , current is supplied to the electromagnets  118  to stop the neutralizing the magnetic force, thereby dropping the payload module  102  away from the fuselage  104  of the aircraft  100 . In other words, the electromagnet  118  may be de-energised to decouple the payload module  102  from the fuselage upon receipt of a de-coupling input. 
     In operation, the one or more electromagnets  118  may be configured to have a holding force of 150N or above to couple the payload module  102  to the fuselage  104  during flight. More preferably, the one or more electromagnets  118  may be configured to provide a holding force of 250N to account for any aerodynamic forces exerted on the payload module  102  during flight. In one example, the one or more electromagnets  118  may be configured to provide a holding force of 375N. 
     In one example, the one or more electromagnets  118  have a weight of approximately 0.15 Kg. In one example, the one or more electromagnets  118  have a substantially circular cross-section and have a diameter of approximately 32 mm. 
     A decoupling element  114  comprising electromagnets  118  provides a relatively low weight solution to allow aircraft  100 , such as HALE vehicle to meet its strict weight requirements. 
       FIG.  4 A  shows a circular baseplate  116 , but other shaped baseplates  116  are envisaged. For example, the baseplate  116  may be substantially rectangular or elliptical.  FIG.  4    shows four electromagnets  118 , but, in practice only one electromagnet  118  may be used. 
       FIG.  4 B  shows an alternative arrangement of electromagnets  118 . In this example, the electromagnets  118  are in the form of strips. As mentioned above, the payload module  102  and the fuselage  104  may be constructed from a relatively lightweight material, such as carbon fibre, which does not respond well to point loads. 
     Providing an electromagnet  118  in the form of a strip results in a relatively large magnetic coupling area. Increasing the number of attachment points between electromagnets  118  and corresponding magnets will decrease the stress on the payload module  102  as the force is split across more contact points. In one example, the electromagnet  118  comprises a relatively long strip electromagnet that is attached to a relatively large area of the payload module  102 . For example, the electromagnet  118  may extend substantially across three quarters of the width of the payload module  102  to spread the loading across the width of the payload module  102 . As such, during connection and release, the connection/release forces are distributed over a relatively larger area and so will be less likely to cause damage. 
       FIG.  4 C  shows an alternative example of the decoupling element  114 . In this example, the payload module  102  is secured to the fuselage  104  via one or more electro-mechanical release mechanisms  120 . In one example, the electro-mechanical release mechanism  120  comprises a pin puller or a separation nut release mechanism. In these examples, a spool of wire may be released when an electric current is passed through it. Utilising an electro-mechanical release mechanism  120  to couple the payload module  102  to the fuselage  104  provides a one-time release of the payload module  102  from the fuselage  104 . Electro-mechanical release mechanism  120  have an operating temperature of between around −150 and 150 degrees Celsius and so are particularly suited for use with a HALE aircraft  100 . This removes the need for thermal management of the electro-mechanical release mechanism  120 , which is difficult to provide on HALE aircraft due to the thin atmosphere and intense energy coming from the sun. Electro-mechanical release mechanisms  120  are also low shock, as no sudden movements or release of energy occurs. This is important to protect the sensitive electronics that are housed within the payload module  102  and also allows the use of off the shelf components to be used rather than bespoke components. This helps reduce costs of production. 
     In one example, the decoupling element  114  comprises a pyrotechnic hold down and release mechanism. A pyrotechnic hold down and release mechanism would allow the separation of the payload module  102  by initiating a small pyrotechnic impulse or pressure releasing mated ends of the decoupling element  114 . This method of release is extremely reliable. 
     In each of these examples, the decoupling element  114  is configured to operate in high-altitude environments. For example, in substantially low temperature and at relatively low pressures. In these examples, the payload module  102  may be relatively light (due to 15 kg restriction), but also recoverable. This differs from other similar uses (like satellites) where the parts that are separated are not usually recovered on the ground, and do not experience constant aerodynamic forces like drag. These requirements mean a long-term durable solution is needed that does not damage the payload module  102  in anyway. 
       FIG.  5    shows an example of an aircraft  100  in which the payload module  102  has been decoupled from the fuselage  104 . In this example, the fuselage  104  comprise an aerofoil  122  that is covered by the payload module  102  when the payload module  102  is coupled to the fuselage  102  and exposed to oncoming air when the payload module  102  is decoupled from the fuselage  104 . 
     The aerofoil  122  is configured to alter the airflow over the aircraft  100  (with payload module  102  removed), such that the fuselage  104  may be diverted downwards to the ground. In examples, the presence of the aerofoil  122  aids with the landing of the aircraft  100  without the payload module  102 . As the payload module  102  is removed from the rest of the aircraft, the centre of gravity of the aircraft  100  shifts rearwards, which would cause an upwards pitch of the aircraft. The aerofoil  122  would counter this rear shift and pitch the aircraft  100  down into a declining flight path assisting the landing of the HALE aircraft with the payload module  102  detached. 
     In this example, both the payload module  102  and the fuselage  104  may both be safely returned to ground in an intact state. In one example, a de-coupling signal may be sent to the control avionics  112  from a ground source to initiate the decoupling element  114  to decouple the payload module  102  from the fuselage  104 . 
     In other examples, the de-coupling signal may be generated by control avionics  112  to initiate the decoupling element  114  to decouple the payload module  102  from the fuselage  104 . 
     The de-coupling signal may be initiated during flight or alternatively be initiated as during the landing process of the aircraft  100 . Intentionally de-coupling the payload module  102  from the fuselage  104  during flight increases the chances that the payload module  102 , which may include expensive equipment, can be safely returned to ground, for example by parachute. In some example, the de-coupling signal may be initiated in the event of an emergency such that the payload module  102  may be more likely to be salvaged. 
     The recovered payload module  102  may be used with another fuselage  104  in a “plug and play” style arrangement. 
     Where, in the foregoing description, integers or elements are mentioned that have known, obvious, or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present disclosure, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the disclosure that are described as optional do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, while of possible benefit in some embodiments of the disclosure, may not be desirable, and can therefore be absent, in other embodiments.