Payload deployment system

Abstract

A payload deployment system 100 for a vessel comprises an ejection tube 101 for holding a payload 102, a fluid‑power ejection apparatus 110 adapted to move from a primed configuration to a fired confi

Description

Field of the Invention The present invention relates to a payload deployment system and particularly, although not exclusively, to a fluid-power payload deployment system. Background Vessels carrying a payload typically require a dedicated payload deployment system for deploying the payload from the vessel. Conventional payload deployment systems often rely on an explosive charge for deploying the payload from the vessel. A drawback of conventional payload deployment systems that rely on explosive charges is that they present a hazard. The hazard may be acceptable when the vessel is deployed; however, when the vessel is located at a vehicle base, the hazard may no longer be acceptable. Often, conventional, explosive charge based, payload deployment systems have to be removed from the vessel when the vessel returns to the vehicle base and then reinstalled before the vessel can leave the base. Further, in an explosive charge based payload deployment system, once the payload has been deployed, it is often not possible to reset the payload deployment system for deploying a further payload. Instead, some or most of the payload deployment system often requires replacement before the payload deployment system can be used again. In some cases, the payload is retained in the payload deployment system by way of a frangible element. Once again, once the payload has been deployed, any frangible elements of the payload deployment system, i.e., elements that are required to break in order to deploy the payload, require replacement before the payload deployment system can be used again. There is therefore a desire to develop a payload deployment that has minimal parts requiring replacement after use and that can be reset in a simple and efficient manner. The present invention has been devised in light of the above considerations. Summary of the Invention According to a first aspect, there is provided a payload deployment system for a vessel, the payload deployment system comprising: an ejection tube for holding a payload; a fluid-power ejection apparatus adapted to move from a primed configuration to a fired configuration under a firing pressure to eject the payload from the ejection tube; and a release apparatus adapted to selectively retain the fluid-power ejection apparatus in the primed configuration against the firing pressure. Put another way, there is provided a system for deploying a payload comprising a release apparatus that selectively retains the payload in the ejection tube against the firing pressure that would otherwise deploy the payload from the ejection tube. In other words, the release apparatus selectively retains the payload in the ejection tube against the firing pressure of the fluid-power ejection apparatus until the release apparatus releases the payload to be ejected under the firing pressure. By providing a means of selectively retaining the payload in the ejection tube against the firing pressure, in the form of the release apparatus, the fluid-power ejection apparatus may be brought to, and maintained at, the firing pressure without the payload being ejected from the ejection tube. In this way, the only action required to eject the payload from the payload deployment system is to actuate the release apparatus to release the payload or the fluid-power ejection apparatus. There is therefore no requirement to prime the fluid-power ejection apparatus and then actuate the release apparatus in response to a trigger signal as the fluid-power ejection apparatus can be pre-emptively primed to the firing pressure without the payload being deployed. The response time for deployment of the payload from the payload deployment system may therefore be reduced and the efficiency of the payload deployment system may be improved. The vessel may be any suitable vessel for holding and deploying a payload. The vessel may be: a water vehicle; a land vehicle; or an air vehicle. For example, the vessel may be a ship or a submarine. The payload may be any suitable payload for deployment from a vessel. The payload may be a countermeasure. For example, the payload may be a munition, such as a torpedo or a missile, or an unmanned underwater vehicle, such as a remotely operated underwater vehicle (ROUV) or an autonomous underwater vehicle (AUV). The firing pressure may be a firing fluid pressure of a pressurized fluid within the fluid-power ejection apparatus. In some examples, the fluid-power ejection apparatus may be a pneumatic ejection apparatus and the firing pressure may be a firing air pressure. In some examples, the fluid-power ejection apparatus may be a hydraulic ejection apparatus and the firing pressure may be a firing liquid pressure. The firing pressure may be directly or indirectly applied to the payload in the payload ejection tube to eject the payload from the payload ejection tube. The firing pressure may be applied to the payload to accelerate the payload through the ejection tube such that the payload is ejected from the ejection tube at an ejection velocity. The ejection velocity may be 1 to 30 meters per second. The fluid-power ejection apparatus is adapted to move from a primed configuration to a fired configuration under the firing pressure to eject the payload from the ejection tube. The fluid-power ejection apparatus may be coupled to the payload in the ejection tube and / or the ejection tube itself. The movement of the fluid-power ejection apparatus may directly or indirectly move the payload within the ejection tube. For example, the movement of the fluid-power ejection apparatus from the primed configuration to the fired configuration may move the payload from a position entirely within the ejection tube to a position at least partially ejected from the ejection tube. The release apparatus is adapted to selectively retain the fluid-power ejection apparatus in the primed configuration against the firing pressure. The release apparatus may be actuated to release the fluid-power ejection apparatus from the primed configuration, such that the fluid-power ejection apparatus moves from the primed configuration to the fired configuration under the firing pressure. The release apparatus may be actuated in response to a trigger signal. The trigger signal may be a mechanical signal or an electronic signal. Various examples of the release apparatus are described in further detail below. In some examples, the release apparatus may comprises a lockable jaw assembly moveable between a retaining configuration, for retaining the fluid-power ejection apparatus in the primed configuration (against the firing pressure), and a release configuration, for releasing the fluid-power ejection apparatus from the primed configuration such that the fluid-power ejection apparatus moves to the fired configuration under the firing pressure. Actuating the release apparatus may comprise moving the lockable jaw assembly from the retaining configuration to the release configuration. In the retaining configuration, the lockable jaw assembly may prevent movement of the fluid-power ejection apparatus from the primed configuration to the fired configuration, thereby preventing relative movement of the payload with respect to the ejection tube. In the release configuration, the lockable jaw assembly may permit movement of the fluid-power ejection apparatus from the primed configuration to the fired configuration, thereby permitting relative movement of the payload with respect to the ejection tube. In some examples, the lockable jaw assembly may comprise a jaw element moveable between an engaged configuration and a disengaged configuration to move the lockable jaw assembly between the retaining configuration and the release configuration. The jaw element may releasably couple with the fluid-power ejection apparatus to selectively retain the fluid-power ejection apparatus in the primed configuration against the firing pressure. The jaw element may releasably grip at least part of the fluid-power ejection apparatus to selectively retain the fluid-power ejection apparatus in the primed configuration against the firing pressure. In some examples, the lockable jaw assembly may comprise a plurality of jaw elements, with the aforementioned jaw element being one of that plurality of jaw elements. Each jaw element of the plurality of jaw elements may be as described above. For example, the lockable jaw assembly may comprise a pair of jaw elements arranged to engage with opposite sides of the fluid-power ejection apparatus. The pair of jaw elements may be diametrically opposed from each other across the fluid-power ejection apparatus. The pair of jaw elements may releasably pinch or grip at least part of the fluid-power ejection apparatus to selectively retain the fluid-power ejection apparatus in the primed configuration against the firing pressure. In some examples, the fluid-power ejection apparatus may comprise a retention contact surface. The jaw element may comprise a first jaw contact surface adapted to contact the retention contact surface when the jaw element is in the engaged configuration. The first jaw contact surface and the retention contact surface may form cooperating surfaces. Put another way, the first jaw contact surface may be parallel to the retention contact surface when the jaw element is in the engaged configuration. In the example where the lockable jaw assembly comprises a plurality of jaw elements, each jaw element may comprise a respective first jaw contact surface. Each respective first jaw contact surface may contact a respective retention contact surface of the fluid-power ejection apparatus, or each respective first jaw contact surface may contact a common retention contact surface of the fluid-power ejection apparatus. The firing pressure of the fluid-power ejection apparatus may force the retention contact surface into contact with the first jaw contact surface, such that the first jaw contact surface applies a retaining force against the retention contact surface to retain the fluid-power ejection apparatus in the primed configuration. At least a component of the retaining force may directly oppose the movement of the fluid-power ejection apparatus from the primed configuration to the fired configuration. In some examples, moving the jaw elementto the disengaged configuration from the engaged configuration moves the first jaw contact surface out of contact with the retention contact surface to release the fluidpower ejection apparatus from the primed configuration. For example, when the first jaw contact surface is moved out of contact with the retention contact surface, the retaining force may no longer be applied to the fluid-power ejection apparatus and the fluid-power ejection apparatus may be released from the primed configuration to move towards the fired configuration under the firing pressure. In some examples, the lockable jaw assembly may further comprise a locking element movable between a locked configuration, for locking the lockable jaw assembly in the retaining configuration, and an unlocked configuration, for releasing the lockable jaw assembly from the retaining configuration. Actuating the release apparatus may comprise moving the locking element from the locked configuration to the unlocked configuration. In the locked configuration, the locking element may prevent movement of the lockable jaw assembly from the engaged configuration to the disengaged configuration, thereby preventing relative movement of the jaw element with respect to the fluid-power ejection apparatus. In the unlocked configuration, the locking element may permit movement of the lockable jaw assembly from the engaged configuration to the disengaged configuration, thereby permitting relative movement of the jaw element with respect to the fluid-power ejection apparatus. In some examples, the release apparatus may further comprise a release pin, wherein the release pin is moveable between an untriggered configuration, for retaining the locking element in the locked configuration, and a triggered configuration, for releasing the locking element from the locked configuration. Actuating the release apparatus may comprise moving the release pin from the untriggered configuration to the triggered configuration. In the untriggered configuration, the release pin may prevent movement of the locking element from the locked configuration to the unlocked configuration, thereby preventing relative movement of the locking element with respect to the or each jaw element. In the triggered configuration, the release pin may permit movement of the locking element from the locked configuration to the unlocked configuration, thereby permitting relative movement of the locking element with respect to the or each jaw element. In some examples, the locking element is moveable between the locked configuration and the unlocked configuration under the firing pressure of the fluid-power ejection apparatus. The release pin may be 5 adapted to retain the locking element in the locked configuration against the firing pressure when the release pin is in the untriggered configuration. The firing pressure of the fluid-power ejection apparatus may force the locking element into contact with the release pin, such that the release pin applies a lock retaining force against the locking element to retain the lockable jaw assembly in the retaining configuration to retain the fluid-power ejection apparatus in the primed configuration. At least a component of the lock retaining force may directly oppose the movement of the locking element from the locked configuration to the unlocked configuration. In some examples, moving the release pin to the triggered configuration from the untriggered configuration permits the locking element to move out of contact with the jaw element, such that the first jaw contact surface may move out of contact with the retention contact surface to release the fluid-power ejection apparatus from the primed configuration. For example, when the release pin is moved out of contact with the locking element, the lock retaining force may no longer be applied to the locking element and the locking element may be released from the locked configuration to move towards the unlocked configuration under the firing pressure. Once the locking element has moved to the unlocked configuration, the jaw element may be permitted to move from the engaged configuration to the disengaged configuration such that the first jaw contact surface moves out of contact with the retention contact surface to release the fluid-power ejection apparatus from the primed configuration. In some examples, the locking element comprises a locking plate and a locking shaft extending therefrom. The locking plate may be configured to engage with the jaw element(s) when the locking element is in the locked configuration. The locking shaft may be configured to engage with the release pin when the release pin is in the untriggered configuration. The release pin applies the lock retaining force to the locking shaft to retain the locking plate in contact with the jaw element(s) and the locking element in the locked configuration. In some examples, the locking element comprises a locking contact surface, and wherein the jaw element comprises a second jaw contact surface adapted to contact the locking contact surface when the locking element is in the locked configuration. The second jaw contact surface and the locking contact surface may form cooperating surfaces. Put another way, the second jaw contact surface may be parallel to the locking contact surface when the jaw element is in the engaged configuration. In the example where the lockable jaw assembly comprises a plurality of jaw elements, each jaw element may comprise a respective second jaw contact surface. Each respective second jaw contact surface may contact a respective locking contact surface of the locking element, or each respective second jaw contact surface may contact a common locking contact surface. The firing pressure of the fluid-power ejection apparatus may force, directly or indirectly, the second jaw contact surface into contact with the locking contact surface, such that the locking contact surface applies a locking force against the second jaw contact surface to retain the jaw element in the engaged configuration. At least a component of the locking force may directly oppose the movement of the jaw element from the engaged configuration to the disengaged configuration. In some examples, the jaw element is rotatable between the engaged configuration and the disengaged configuration. The jaw element may be rotatable relative to the fluid-power ejection apparatus. The jaw element may be rotatable relative to the locking element. In some examples, the release apparatus may comprise a pivot point about which the jaw element is rotatably mounted. The first jaw contact surface and the second jaw contact surface may be provided on opposing sides of the pivot point. For example, rotation of the jaw element about the pivot point in a first direction may bring the first jaw contact surface out of contact with the retention surface and the second jaw contact surface into contact with the locking contact surface. For example, rotation of the jaw element about the pivot point in a second direction, opposite the first direction, may bring the first jaw contact surface into contact with the retention surface and the second jaw contact surface out of contact with the locking contact surface. When the locking element is in the locked configuration and the fluid-power ejection apparatus is in the primed configuration, the jaw element in the engaged configuration may be prevented from rotating in either the first direction or the second direction. When the locking element moves to the unlocked configuration, the jaw element may then be permitted to rotate in the first direction to release the fluid-power ejection apparatus from the primed configuration. The movement of the fluid-power ejection apparatus from the primed configuration to the fired configuration may force the jaw element to rotate from the engaged configuration to the disengaged configuration once the locking element has moved to the unlocked configuration. In some examples, the retention contact surface may be angled with respect to a longitudinal axis of the ejection tube at a first angle. The first jaw contact surface may be angled with respect to the longitudinal axis of the ejection tube at the first angle when the jaw element is in the engaged configuration. In some examples, the locking contact surface may be angled with respect to the longitudinal axis of the ejection tube at a second angle, different to the first angle. The second jaw contact surface may be angled with respect to the longitudinal axis of the ejection tube at the second angle when the jaw element is in the engaged configuration. The first angle may be a minimum angle between the retention contact surface and the longitudinal axis of the ejection tube. The second angle may be a minimum angle between the locking contact surface and the longitudinal axis of the ejection tube. The first angle may be defined between the retention contact surface and a vector parallel to the longitudinal axis of the ejection tube and directed away from the movement of the fluid-power ejection apparatus from the primed configuration to the fired configuration. The second angle may be defined between the locking contact surface and a vector parallel to the longitudinal axis of the ejection tube and directed away from the movement of the fluid-power ejection apparatus from the primed configuration to the fired configuration. In some examples, the second angle may be smaller than the first angle. In other words, the angle between the locking contact surface and the longitudinal axis of the ejection tube may be smaller than the angle between the retention contact surface and the longitudinal axis of the ejection tube. For example, once the release pin has moved from the untriggered position to the triggered position, the only remaining movements of the payload deployment system may occur directly or indirectly as a result of the firing pressure. In particular, both the locking element and the fluid-power ejection apparatus are moveable under the firing pressure; however, in order for the fluid-power ejection apparatus to move from the primed configuration to the fired configuration, the jaw element has to move from the from the engaged configuration to the disengaged configuration, which is prevented by the locking element until the locking element has moved from the locked configuration to the unlocked configuration. In the case where the second angle, i.e., the angle between the locking contact surface and the longitudinal axis of the ejection tube, is smaller than the first angle, i.e., the angle between the retention contact surface and the longitudinal axis of the ejection tube, the locking element will be moved from the locked configuration to the unlocked configuration by the firing pressure before the fluid-power ejection apparatus will move from the primed configuration to the fired configuration. The second angle being smaller than the first results in a locking force (or release force or actuation force) that is smaller than the retaining force (or hold force), meaning that the locking element will move under the firing pressure more easily than the fluidpower ejection apparatus. This both ensures that the lockable jaw assembly can move automatically (under the firing pressure) from the retaining configuration to the release configuration once the release pin has moved to the triggered configuration as well as ensuring that the fluid-power ejection apparatus will not move from the primed configuration to fired configuration (under the firing pressure) until the locking element has moved to the unlocked configuration. In some examples, the first angle is around 2 or more times as large as the second angle. For example the first angle may be around 3 or more times as large as the second angle. For example the first angle may be around 4 or more times as large as the second angle. For example the first angle may be around 4.5 times as large as the second angle. In some examples, the fluid-power ejection apparatus may comprise an ejection element having a payload facing surface adapted to contact the payload in the ejection tube. The ejection element may be adapted to move through the ejection tube from the primed configuration to the fired configuration under the firing pressure to eject the payload from the ejection tube at an ejection velocity when the ejection element is released by the release apparatus. For example, the ejection element may be releasably coupled, directly or indirectly, to the release apparatus when the release apparatus is in engaged configuration and the fluid-power ejection apparatus is in the primed configuration. The ejection element may have the same cross-sectional shape as the ejection tube. The ejection element may substantially fill a transverse cross-section of the ejection tube. In some examples, the ejection element may comprise a deformable element provided on the payload facing surface of the ejection element. In this way, the ejection element may be provided in compliant contact with the payload in order to account for manufacturing tolerances as well as reduce vibrations transferred to the payload whilst the payload is in the ejection tube. In some examples, the ejection element may comprise a projection extending from a body of the ejection element towards the payload. The projection may be provided towards an outer edge of the body of the ejection element. The payload facing surface of the ejection element may be provided on an end face of the projection such that the payload facing surface contacts an outer edge of the payload. The projection and the body of the ejection element may define a recess for receiving a portion of the payload. The recess may receive the portion of the payload without directly contacting the payload, such that the only contact between the payload and the ejection element occurs at the payload facing surface. In some examples, the payload deployment system may comprise a pressure balancing port for balancing a pressure in the ejection tube as the ejection element moves through the ejection tube. The pressure balancing port may be formed in a sidewall of the ejection tube. The pressure balancing port may be fluidically connected to an environment external to the ejection tube. That is, the pressure balancing port may provide a fluid connection between the ejection tube (e.g. an inside thereof) and the environment external to the ejection tube. For example, where the vessel is a submarine and the payload is a torpedo, the pressure balancing port may fluidically connect the inside of the ejection tube to the underwater environment external to the ejection tube into which the torpedo is being deployed. The pressure balancing port may be provided rearwardly of the ejection element and at the opposite end of the ejection tube to an ejection port, through which the payload is ejected. In use, as the ejection element moves through the ejection tube to move the payload towards the ejection port, the environmental fluid, i.e., the seawater, may flood behind the ejection element through the pressure balancing port. In this way, the pressure experienced by the fluid-power ejection apparatus is balanced between the payload deployment system and the external environment. Accordingly, the fluid-power ejection apparatus does not have to overcome an external pressure, which may be high in a submarine context, in order to eject the payload from the ejection tube. In some examples, the fluid-power ejection apparatus may comprise: a cavity for receiving a pressurised fluid; and an ejection shaft extending from the ejection element into the cavity. The retention contact surface may be provided at a retaining end of the ejection shaft opposite a payload end of the ejection shaft, the payload end being proximate the ejection element. The retention contact surface may circumscribe the retaining end of the ejection shaft. The cavity may comprise a valve for introducing the pressurised fluid into the cavity, or removing the pressurised fluid from the cavity. The valve may be provided in a wall of the cavity. In some examples, the ejection shaft may comprise an ejection cavity at least partially enclosed by the ejection shaft. For example, the ejection shaft may be a hollow shaft. The ejection shaft may comprise a conduit fluidly connecting the ejection cavity to the cavity. The ejection shaft may comprise a drive surface within the ejection cavity and provided towards the payload end of the ejection shaft. In this way, the firing pressure applies a driving force to the drive surface to drive the ejection shaft out of the cavity, and so move the ejection element through the ejection tube, thereby moving the fluid-power ejection apparatus from the primed configuration to the fired configuration. By providing a substantially hollow ejection shaft, the weight of the fluid-power ejection apparatus may be reduced, thereby reducing the driving force required to accelerate the fluid-power ejection apparatus to eject the payload from the ejection tube. By providing a conduit connecting the ejection cavity to the cavity and the drive surface internal to the ejection cavity, the pressure within the ejection shaft is equalised with the pressure external to the ejection shaft and within the cavity, thereby preventing the ejection shaft from buckling. In some examples, the cavity is tapered. For example, the cavity may narrow towards an ejection tube end of the cavity. The tapering of the cavity may reduce vibrations in the ejection shaft as the ejection shaft moves through the cavity. According to a second aspect, there is provided a method for loading a payload deployment system as described above, the method comprising: moving the fluid-power ejection apparatus to the primed configuration; selectively retaining the fluid-power ejection apparatus in the primed configuration using the release apparatus; locating the payload in the ejection tube; and pressurizing the fluid-power ejection apparatus to the firing pressure, such that the fluid-power ejection apparatus is retained in the primed configuration by the release apparatus against the firing pressure. The fluid-power ejection apparatus may be pressurised by introducing a pressurised fluid into the cavity by way of the valve as described above. In some examples, there may be a delay between locating the payload in the ejection tube and pressurizing the fluid-power ejection apparatus to the firing pressure. For example, the method steps may be performed up until the step of locating the payload in the ejection tube as a vessel is refitted in a vehicle base. The step of pressurizing the fluid-power ejection apparatus may then only be performed prior to the vessel leaving the vehicle base. In contrast to a conventional explosive charge based payload deployment system, the step of pressurizing the fluid-power ejection apparatus is significantly less labour intensive than reinstalling an entire payload deployment system and can be completed in a significantly shorter period of time. In addition, the payload deployment system may remain unpressurized indefinitely, such that payload deployment system is not storing energy for an extended period of time. In the case where a vessel returns to a vehicle base without the payload having been ejected, the fluidpower ejection apparatus may be depressurized, for example by way of the valve as described above, in order to remove the firing pressure from the fluid-power ejection apparatus and de-energise the payload deployment system. Thus, the payload deployment system may be rendered safe to work around without requiring the entire system to be removed from the vessel. According to a third aspect, there is a provided a method for reloading a payload as described above, the method comprising: removing residual pressurized fluid from the fluid-power ejection apparatus; and performing the method for loading the payload deployment system according to the second aspect. The residual pressurized fluid may be removed from the fluid-power ejection apparatus by way of the valve as described above. The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided. Summary of the Figures Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which: Figures 1a and 1b show a schematic representation of a payload deployment system according to an aspect of the disclosure. Figure 2 shows a schematic representation of a lockable jaw assembly according to an aspect of the disclosure in the retaining configuration. Figures 3 to 8 show schematic representations of a payload deployment system according to an aspect of the disclosure with the lockable jaw assembly moving from the retaining configuration to the release configuration and the fluid-power ejection apparatus moving from the primed configuration to the fired configuration. Figure 9 shows a method of loading a payload deployment according to an aspect of the disclosure. Detailed Description of the Invention Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference. Figures 1a and 1b show a schematic representation of a payload deployment system 100 according to an aspect of the disclosure. Figure 1a shows the payload deployment system 100 with the fluid-pressure ejection apparatus 110 retained in the primed configuration by the release apparatus 150. Figure 1 b shows the payload deployment system 100 with the fluid-pressure ejection apparatus 110 in the fired configuration. The payload deployment system 100 shown in Figures 1a and 1b comprises an ejection tube 101 for holding a payload 102, which is received in a cavity 103 of the ejection tube 103. An ejection port end 104 of the ejection tube may be sealed by a frangible end cap 105. The payload deployment system 100 further comprises a fluid-power ejection apparatus 110. The fluidpower ejection apparatus 110 is adapted to move from a primed configuration, as shown in Figure 1a, to a fired configuration, as shown in Figure 1 b, under a firing pressure to eject the pay load 102 from the ejection tube 101. As the payload 102 is ejected from the ejection tube 101, the payload 102 may rupture the frangible end cap 105 in order to be fully ejected from the ejection tube 101. An example of a fluid-power ejection apparatus 110 is provided below with reference to Figures 2 to 7. The payload deployment system 100 further comprises a release apparatus 150. The release apparatus 120 is adapted to selectively retain the fluid-power ejection apparatus 110 in the primed configuration, as shown in Figure 1a, against the firing pressure. An example of a release apparatus 150 is provided below with reference to Figures 2 to 7. Figure 2 shows a schematic representation of a release apparatus 250 according to an aspect of the disclosure. The release apparatus 250 shown in Figure 2 is selectively retaining the fluid-power ejection apparatus 210 in the primed configuration against the firing pressure. The features of the fluid-power ejection apparatus are described in further detail below with respect to Figure 3. In the example shown in Figure 2, the release apparatus 250 comprises a lockable jaw assembly 251, which comprises a pair of jaw elements 252, each rotatably mounted about respective pivot points 253 on opposite sides of the fluid-power ejection apparatus 210, and a locking element 254. The lockable jaw assembly 251 is shown in the retaining configuration in Figure 2, with the jaw elements 252 in the engaged configuration and the locking element 254 in the locking configuration. The fluid-power ejection apparatus 210 comprises a retention contact surface 212 and the jaw elements each comprise a respective first jaw contact surface 255 adapted to contact the retention contact surface 212 when the jaw element 252 is in the engaged configuration as shown in Figure 2. The lockable jaw assembly 251 in the retaining configuration retains the fluid-power ejection apparatus 210 in the primed configuration against the firing pressure, which drives the fluid-power ejection apparatus 210 in a firing direction 211. The firing pressure drives the retention contact surface 212 towards the respective first jaw contact surfaces 255. The retention contact surface 212 applies a firing force 213 against the first jaw contact surface 256. The first jaw contact surface 256 applies an opposing retaining force 213 against the retention contact surface 212 to retain the fluid-power ejection apparatus 210 in the primed configuration. At least a component of the retaining force 256 directly opposes the movement of the fluid-power ejection apparatus in the firing direction 211. The locking element 254 comprises a locking contact surface 257 and the jaw elements each comprise a respective second jaw contact surface 258 adapted to contact the locking contact surface 257 when the locking element 254 is in the locked configuration as shown in Figure 2. As outlined above, the lockable jaw assembly 251 in the retaining configuration retains the fluid-power ejection apparatus 210 in the primed configuration against the firing pressure, which drives the fluid-power ejection apparatus 210 in a firing direction 211. The firing pressure drives the retention contact surface 212 towards the respective first jaw contact surfaces 255, which would cause the jaw elements 252 to rotate about the pivot points 253 in a first direction 259 to bring the first jaw contact surfaces 255 out of contact with the retention surface 212 and the second jaw contact surface 258 into contact with the locking contact surface 257. In the absence of the locking element 254, for example when the locking element 254 is in the unlocked configuration, the jaw elements 252 would continue to rotate in the first direction 259 towards the disengaged configuration, in order to bring the lockable jaw assembly 251 into the release configuration for releasing the fluid-power ejection apparatus 210 from the primed configuration. However, with the locking element 254 in the locked configuration, the second jaw contact surfaces 258 apply a transferred firing force 214 against the locking contact surface 257. The locking contact surface 257 applies an opposing locking force 260 against the second jaw contact surfaces 258 to retain the jaw elements 252 in the engaged configuration. The locking force 260 is transferred around the pivot point 253 in a second direction 261, opposite the first direction 259. At least a component of the locking force 260 directly opposes the rotation movement of the jaw elements 252 in the first direction 259. In the example shown in Figure 2, the retention contact surface 212 is angled with respect to a longitudinal axis 206 of the ejection tube (not shown in Figure 2) at a first angle 215 and the locking contact surface 258 is angled with respect to the longitudinal axis 206 of the ejection tube at a second angle 216, which is smaller than the first angle 215. By making the second angle 216 smaller than the first angle 215, the locking force 260 is made less than the retaining force 256 such that the retention of the fluid-power ejection apparatus 210 is stronger than the locking of the jaw elements 252 by the locking element 254. In this way, the locking element 254 can be moved from the locked configuration to the unlocked configuration by the firing pressure before the fluid-power ejection apparatus 210 is moved from the primed configuration to the fired configuration. For example, the first angle 215 may be twice the size of the second angle 216. Figures 3 to 8 show a series of schematic representations of a payload deployment system 300 with the lockable jaw assembly 251 moving from the retaining configuration to the release configuration and the fluid-power ejection apparatus 210 moving from the primed configuration to the fired configuration. Reference numerals for features shown in Figures 1 a, 1 b and 2 have been denoted with the same reference numerals in Figures 3 to 8. The fluid-power ejection apparatus 210 comprises a cavity 230 for receiving a pressurised fluid, which may be received in the cavity by way of a valve 231. The cavity is tapered towards a payload end 232 of the cavity 230. The pressurized fluid received in the cavity 230 generates the firing pressure that drives the fluid-power ejection apparatus 210 from the primed configuration, shown in Figure 3, to the fired configuration, shown in Figure 8. In the examples shown in Figure 3 to 8, the fluid-power ejection apparatus 210 comprises an ejection element 220 having a payload facing surface 221. A deformable element 222 is provided on the payload facing surface 221 of the ejection element 220 for contacting the pay load 102 in the ejection tube 101. The ejection element 220 moves through the ejection tube 101 from the primed configuration, shown in Figure 3, to the fired configuration, shown in Figure 8, under the firing pressure to eject the payload 102 from the ejection tube 101 at an ejection velocity when the ejection element 220 is released. The ejection element 220 comprises a projection 223 extending from a body 224 of the ejection element 220 towards the payload 102. The projection 223 is provided towards an outer edge of the body 224 of the ejection element 220. The payload facing surface 221 is provided on an end face of the projection such that the pay load facing surface 221 contacts an outer edge of the pay load 102. The projection 223 and the body 224 of the ejection element 220 define a recess 106 for receiving a portion 107 of the payload 102. In the examples shown in Figure 3 to 8, the fluid-power ejection apparatus 210 further comprises an ejection shaft 225 extending from the ejection element 220 into the cavity 230. The retention contact surface 212 is provided at a retaining end 226 of the ejection shaft 225 opposite the ejection element 220. The ejection shaft 225 comprises an ejection cavity 227 at least partially enclosed by the ejection shaft 225. The ejection cavity 227 is fluidly connected to the cavity 230 by a conduit 228. The ejection shaft 225 further comprises a drive surface 229 within the ejection cavity 227 and provided towards the payload end of the ejection shaft 225 proximate the ejection element 220. The payload deployment system 300 may further comprise a release pin 310, wherein the release pin 310 is moveable between an untriggered configuration, shown in Figure 3, for retaining the locking element 254 in the locked configuration, and a triggered configuration, shown in Figure 4, for releasing the locking element 254 from the locked configuration. In addition to the elements of the lockable jaw assembly 251 described above with reference to Figure 2, in the examples shown in Figures 3 to 8, the locking element 254 comprises a locking plate 254a and a locking shaft 254b extending therefrom. The locking plate 254a engages with the jaw elements 252 when the locking element 254 is in the locked configuration. The locking shaft 254b engages with the release pin 310 when the release pin 310 is in the untriggered configuration. The locking shaft 254b extends from the locking plate 254a to the release pin 310, through a wall of the cavity 230. The release pin 310 applies the lock retaining force to the locking shaft 254b to retain the locking element 254 in the locked configuration, shown in Figure 3. The firing pressure acts on the locking plate 254a in the same manner as the fluid-power ejection apparatus 210 in order to move the locking element from the locked configuration to the unlocked configuration. The payload deployment system 300 shown in Figures 3 to 8 further comprises a pressure balancing port 320 for balancing pressure in the ejection tube 101 with the external environment, which may be submerged underwater, as the ejection element 220 moves through the ejection tube 101, which will be explained in further detail below. The steps of deploying the payload 102 using the payload deployment system 300 is now outlined below with reference to Figures 3 to 4. Figure 3 shows the payload deployment system 300 in an initial state with a payload loaded 102 in the ejection tube, the fluid-power ejection apparatus 210 in the primed configuration and the lockable jaw assembly 251 in the retaining configuration. Further, the release pin 310 is in the untriggered configuration, retaining the locking element 254 in the locked configuration, which in turn retains the jaw elements 252 in the engaged configuration. In response to a trigger signal, the release pin 310 moves to the triggered configuration shown in Figure 4. When the release pin 310 has moved to the triggered configuration, the release pin 310 no longer contacts the locking shaft 254b and the lock retaining force is no longer applied to the locking element 254. In response to the release pin 310 moving to the trigger configuration, the locking element 254 is released from the locked configuration shown in Figure 4 to the unlocked configuration shown in Figure 5 under the firing pressure. When the locking element 254 has moved to the unlocked configuration, the lock contact surface 257 no longer contacts the second jaw contact surface 258 and the locking force is no longer applied to the jaw elements 252. In response to the locking element 254 moving to the unlocked configuration, the jaw elements 252 are released from the engaged configuration shown in Figure 5. The jaw elements 252 are therefore free to rotate about the pivot points 253 in response to the driving force 213 applied to first jaw contact surface 255 by the retaining contact surface 212. As the jaw elements 254 rotate in the first direction 259, the fluidpower ejection apparatus 210 begins to move from the primed configuration towards the fired configuration. The jaw elements 254 may move from the engaged configuration to the disengaged configuration, shown in Figure 6, substantially simultaneously with the fluid-power ejection apparatus 210 moving from the primed configuration to the fired configuration. In Figure 7, the lockable jaw assembly 251 is fully in the release configuration and the fluid-power ejection apparatus 210 is free to move under the firing pressure from the primed configuration to the fired configuration, which is shown across Figures 5 to 8. In Figure 8, the fluid-power ejection apparatus 210 has reached the fired configuration and the payload 102 finishes ejecting from the ejection tube 101 under the momentum imparted by the fluid-power ejection apparatus 210. In the final part of the movement of the fluid-power ejection apparatus 210 to the fired configuration, the tapering of the payload end 232 of the cavity 230 may guide the ejection saft 225 to keep the movement of the fluid-power ejection apparatus 210 straight. Figure 9 shows a method 400 for loading a payload deployment system 300 as described herein. The method begins in step 410 by moving the fluid-power ejection apparatus 210 to the primed configuration, for example as shown in Figure 3. Step 410 may be performed when the lockable jaw assembly 251 is in the disengaged configuration, for example as shown in Figure 7. In step 420, the fluid-power ejection apparatus 210 is selectively retained in the primed configuration using the release apparatus 250, for example by moving the jaw elements 252 to the engaged configuration as shown in Figure 4. In step 430, the payload 102 is located in the ejection tube 101, for example as shown in Figure 3. In step 440, the fluid-power ejection apparatus 210 is pressurized to the firing pressure, for example by filling the cavity 230 with a pressurized fluid via the valve 231, such that the fluid-power ejection apparatus 210 is retained in the primed configuration by the release apparatus 250 against the firing pressure. In some examples, there may be a delay between steps 430 and 440. For example, the method may be performed from steps 410 to 430 as a vessel is refitted in a vehicle base. Step 440 may then only be performed prior to the vessel leaving the vehicle base. In contrast to a conventional explosive charge based payload deployment system, step 440 is significantly less labour intensive than reinstalling an entire payload deployment system and can be completed in a significantly shorter period of time. After the payload 102 has been deployed, for example following the sequence outlined about with respect to Figures 3 to 8, the method 400 may include the optional step 450 of removing residual pressurized fluid from the fluid-power ejection apparatus 210, for example via the valve 231, after which the method steps 410 to 440 may be repeated in order to reload the payload deployment system 300. The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof. While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention. For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations. Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / -10%.

Claims

:

1. A payload deployment system for a vessel, the payload deployment system comprising: an ejection tube for holding a payload;5 a fluid-power ejection apparatus adapted to move from a primed configuration to a firedconfiguration under a firing pressure to eject the payload from the ejection tube; anda release apparatus adapted to selectively retain the fluid-power ejection apparatus in the primed configuration against the firing pressure.10 2. The payload deployment system claimed in claim 1, wherein the release apparatus comprises alockable jaw assembly moveable between a retaining configuration, for retaining the fluid-power ejection apparatus in the primed configuration, and a release configuration, for releasing the fluid-power ejection apparatus from the primed configuration such that the fluid-power ejection apparatus moves to the fired configuration under the firing pressure.

153. The payload deployment system claimed in claim 2, wherein the lockable jaw assembly comprises a jaw element moveable between an engaged configuration and a disengaged configuration to move the lockable jaw assembly between the retaining configuration and the release configuration.20 4. The payload deployment system claimed in claim 3, wherein the lockable jaw assemblycomprises a plurality of jaw elements.

5. The payload deployment system claimed in any of claims 3 to 4, wherein the fluid-power ejection apparatus comprises a retention contact surface, and wherein the jaw element comprises a first jaw25 contact surface adapted to contact the retention contact surface when the jaw element is in the engaged configuration.

6. The payload deployment system claimed in claim 5, wherein moving the jaw element to the disengaged configuration from the engaged configuration moves the first jaw contact surface out of30 contact with the retention contact surface to release the fluid-power ejection apparatus from the primed configuration.

7. The payload deployment system claimed in any of claims 2 to 6, wherein the lockable jaw assembly further comprises a locking element movable between a locked configuration, for locking the16 1025lockable jaw assembly in the retaining configuration, and an unlocked configuration, for releasing the lockable jaw assembly from the retaining configuration.

8. The payload deployment system claimed in claim 7, wherein the release apparatus further 5 comprises a release pin, wherein the release pin is moveable between an untriggered configuration, for retaining the locking element in the locked configuration, and a triggered configuration, for releasing the locking element from the locked configuration.

9. The payload deployment system of claim 8, wherein the locking element is moveable between 10 the locked configuration and the unlocked configuration under the firing pressure of the fluid-power ejection apparatus, and wherein the release pin is adapted to retain the locking element in the locked configuration against the firing pressure when the release pin is in the untriggered configuration.

10. The payload deployment system of any of claims 7 to 9, wherein the locking element comprises a 15 locking contact surface, and wherein the jaw element comprises a second jaw contact surface adapted to contact the locking contact surface when the locking element is in the locked configuration.

11. The payload deployment system in any of claims 9 to 10, when dependent directly or indirectly on claim 5, wherein the retention contact surface is angled with respect to a longitudinal axis of the ejection 20 tube at a first angle and the locking contact surface is angled with respect to the longitudinal axis of the ejection tube at a second angle, different to the first angle.

12. The payload deployment system of claim 11, wherein the second angle is smaller than the first angle.2513. The payload deployment system of claim 12, wherein the first angle is around 2 or more times as large as the second angle.

14. The payload deployment system claimed in any of claims 3 to 13, wherein the jaw element is 30 rotatable between the engaged configuration and the disengaged configuration.

15. The payload deployment system of claim 14, when dependent directly or indirectly on claim 10, wherein the release apparatus comprises a pivot point about which the jaw element is rotatably mounted, and wherein the first jaw contact surface and the second jaw contact surface are provided on opposing 35 sides of the pivot point.16 102516. The payload deployment system claimed in any preceding claim, wherein the fluid-power ejection apparatus comprises an ejection element having a payload facing surface adapted to contact a payload in the ejection tube, wherein the ejection element is adapted to move through the ejection tube from the primed configuration to the fired configuration under the firing pressure to eject the payload from the ejection tube at an ejection velocity when the ejection element is released by the release apparatus.

17. The payload deployment system claimed in claim 16, wherein the ejection element comprises a deformable element provided on the payload facing surface of the ejection element.

18. The payload deployment system claimed in any of claims 16 to 17, wherein the ejection element comprises a projection extending from a body of the ejection element towards the payload, the projection being provided towards an outer edge of the body of the ejection element and the payload facing surface being provided on an end face of the projection such that the payload facing surface contacts an outer edge of the payload.

19. The payload deployment system claimed in any of claims 16 to 18, wherein the payload deployment system further comprises a pressure balancing port for balancing a pressure in the ejection tube as the ejection element moves through the ejection tube.

20. The payload deployment system claimed in any of claims 16 to 19, when dependent directly or indirectly on claim 5, wherein the fluid-power ejection apparatus comprises:a cavity for receiving a pressurised fluid; andan ejection shaft extending from the ejection element into the cavity, wherein the retention contact surface is provided at a retaining end of the ejection shaft opposite a payload end of the ejection shaft, the payload end being proximate the ejection element.

21. The payload deployment system claimed in claim 20, wherein the ejection shaft comprises an ejection cavity at least partially enclosed by the ejection shaft, wherein the ejection shaft further comprises a conduit fluidly connecting the ejection cavity to the cavity.

22. The payload deployment system claimed in claim 21, wherein the ejection shaft comprises a drive surface within the ejection cavity and provided towards the payload end of the ejection shaft.

23. The payload deployment system as claimed in any of claims 20 to 22, wherein the cavity is tapered.

24. A method for loading a payload deployment system as claimed in any of claims 1 to 23, the5 method comprising:moving the fluid-power ejection apparatus to the primed configuration;selectively retaining the fluid-power ejection apparatus in the primed configuration using the release apparatus;locating the payload in the ejection tube; and10 pressurizing the fluid-power ejection apparatus to the firing pressure, such that the fluid-powerejection apparatus is retained in the primed configuration by the release apparatus against the firing pressure.

25. A method for reloading a payload as claimed in any of claims 1 to 23, the method comprising:15 removing residual pressurized fluid from the fluid-power ejection apparatus; andperforming the method for loading the payload deployment system claimed in claim 24.LOCXI

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