WO2018085902A1

WO2018085902A1 - An inflation system for use in a buoyancy system

Info

Publication number: WO2018085902A1
Application number: PCT/AU2017/051253
Authority: WO
Inventors: Tim Lyons
Original assignee: Archimedes Pty Ltd
Priority date: 2016-11-14
Filing date: 2017-11-14
Publication date: 2018-05-17

Abstract

The present invention provides an inflation system (12) for use in a buoyancy system (14). The buoyancy system is adapted to be fitted to an aircraft (15) for recovering and retaining the aircraft (15) at the surface of a body of water (16), upon landing, crashing or ditching into the water. The buoyancy system comprises a plurality of inflatable bodies (1 ) which, when inflated, increases the buoyancy of the aircraft. The inflation system inflates the inflatable body and comprises a first gas and a gas generation system (33) for generating a second gas, the second gas being at a higher temperature than the first gas. The gas generation system is housed in a hollow body (35). The buoyancy system also comprises an activation system (5) to activate the inflation system. Upon activation of the inflation system the first gas passes into the hollow body as the gas generation system produces the second gas. The first gas is caused to mix with the second gas to form a third gas, the third gas inflating the inflatable body to the desired level of inflation.

Description

An Inflation System for use in a Buoyancy System Field of the Invention

[0001 ] The present invention generally relates to a buoyancy system and an inflation system. In particular the present invention generally relates to an inflation system for use with a buoyancy system capable of rapid inflation.

Background Art

[0002] Buoyancy/ floatation systems typically incorporate one or more inflatable bodies, a gas supply and a means to activate the system. Upon activation of the system the inflatable bodies are inflated from the gas supply. The gas supply is typically in the form of a compressed gas connected directly or indirectly via a conduit/hose to the inflatable body. In order to retain buoyancy, the inflatable bodies are gas tight and sealed. These systems tend to be very heavy and require a relatively large volume, largely due to the required cylinder/reservoir of compressed gas. Furthermore, the speed of inflation is restricted by the hose and/or orifice providing gas to the inflatable body and the pressure inside the cylinder. In some applications these buoyancy/ floatation systems are unable to inflate quick enough to provide the requisite level of inflation.

[0003] Multi role aircraft are often employed by Defence Forces to perform operations over water. In most cases such aircraft are not fitted with a system that can provide sufficient buoyancy to keep the aircraft afloat, which is a problem should they ditch or crash into water. History continues to demonstrate that aircraft generally sink very quickly once they ditch or crash into water. This poses a significant risk to the aircraft and their crew when operating over water.

[0004] The buoyancy/ floatation systems which are currently fitted to aircraft/helicopters use heavy, robust cylinders of compressed gas to inflate buoyancy bags when the buoyancy bags are at the surface (i.e. when the pressure is at one atmosphere). These cylinders are generally designed to provide the minimum amount of buoyancy required to keep an aircraft/helicopter afloat after a controlled landing on water. In those cases where the aircraft/helicopter has begun to sink the increasing pressure exerted by water retards inflation. As aircraft/helicopters sink rapidly upon contact with water, the buoyancy/ floatation systems require large volumes of gas to overcome the increasing water pressure while inflating the bags to their full volume. Current buoyancy/ floatation systems have limited gas flow supply as well as gas supply rates. These are unable to counteract the effect of increasing water pressure as the aircraft/helicopter sinks and cannot return the sinking aircraft/helicopter to the surface.

[0005] Other inflatable bodies such as automotive airbags, which are generally not gas tight or sealed inflatable bodies, momentarily inflate to provide cushioning to the occupants in a motor vehicle accident. These inflatable bodies are inflated with energetic and explosive materials to ensure rapid deployment, but generally do not remain inflated as longevity of the inflatable body post cushioning is not an important consideration following the initial impact that caused the airbag to deploy. Automotive airbags also have a small volume, typically less than one cubic meter.

[0006] There are other buoyancy/ floatation systems which incorporate inflatable bodies that are inflated rapidly with a cold, high pressure gas. Due to the nature of the gas supply and the temperature of the gas these systems are prone to damage as the sealant medium used to render the fabric gas tight becomes brittle, or is displaced from the fabric. Often the pressure at which the gas is stored needs to be limited to reduce the effects of extreme cold gas on the gas tight fabric, which lowers the overall inflation volume which is problematic for a sinking airframe due to an increase in hydrostatic sea pressure as discussed above. Extremely cold gas can reduce the effectiveness of the inflatable body to contain the inflation gas when inside the inflatable body.

[0007] There are yet other buoyancy/ floatation systems which incorporate inflatable bodies that are inflated rapidly with a hot gas generated from a pyrotechnic device. Again, due to the nature of the gas generation and the temperature of the gas, the inflatable body is prone to damage. This damage could include damage to: [0008] the sealant medium used to make the fabric gas tight by causing the sealant medium to melt or become less effective in containing the gas.

[0009] the fabric providing strength and the structural integrity to the inflatable body by melting or damaging fabric fibres.

[0010] The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application.

SUMMARY OF INVENTION

[001 1 ] It is an objective of this invention to provide a buoyancy system which overcomes at least one of the problems of the prior art, or at least provides a useful alternative.

[0012] The inflation system used in the buoyancy system of the present invention provides a light weight means to supply gas rapidly, such as to inflate an inflatable body of a buoyancy system connected to an aircraft. The primary objective of the buoyancy system is to provide sufficient time for aircraft occupants to safely egress an aircraft after an event that has led to the aircraft landing, crashing or ditching into a body of water. A secondary objective of the buoyancy system is to assist in the recovery of the aircraft including the recovery of any cryptographic, weapons, sensitive or other valuable materials, and to assist subsequent aircraft investigation.

[0013] The present invention provides a buoyancy system adapted to be fitted to an aircraft for recovering and retaining the aircraft at the surface of a body of water, upon landing, crashing or ditching into the water, the buoyancy system comprises: a plurality of inflatable bodies which, when inflated, increases the buoyancy of the aircraft, each inflatable body having an inflation system to inflate the inflatable body, the inflation system provides a first gas and comprises: a gas generation system for generating a second gas, the second gas being at a higher temperature than the first gas, the gas generation system being housed in a hollow body; an activation system to activate the inflation system; whereupon activation of the inflation system the first gas passes into the hollow body, the gas generation system produces the second gas, wherein the first gas is caused to mix with the second gas to form a third gas, the third gas inflating the inflatable body to the desired level of inflation.

[0014] The present invention provides a buoyancy system adapted to be fitted to an aircraft for recovering and retaining the aircraft at the surface of a body of water, upon landing, crashing or ditching into the water, the buoyancy system comprises: an inflatable body which, when inflated, increases the buoyancy of the aircraft; an inflation system to inflate the inflatable body, the inflation system comprises; a reservoir comprising a first gas; a gas generation system for generating a second gas, the second gas being at a higher temperature than the first gas, the gas generation system being housed in a hollow body; an activation system to activate the inflation system; whereupon activation of the inflation system the first gas is released from the reservoir and passes into the hollow body, the gas generation system produces the second gas, wherein the first gas leaving the reservoir is caused to mix with the second gas to form a third gas, the third gas inflating the inflatable body to the desired level of inflation.

[0015] Preferably the inflation system is incorporated within the inflatable body. This allows the direct inflation of the inflatable body. As soon as gas is generated from the inflation system the inflatable body begins to inflate. As the gas is generated rapidly the rate of inflation of the inflatable body is significantly quicker than prior art systems.

[0016] The buoyancy system of the present invention does not rely on hoses or other equipment to deliver the gas to the inflatable body. Neither does it rely on having to first pass the gas through a heat exchanger in order to cool the gas before it enters the inflatable body. This not only eliminates slow points in the delivery of the gas, it also reduces the weight of the inflation system which is a critical consideration when considering attaching a buoyancy system to an aircraft

[0017] Each inflatable body may have one or more inflation systems incorporated therein.

[0018] The gas generation system may comprise a gas generating medium such as for example an explosive, propellant or other chemical compound whereby a charge activates the medium, creating the second gas.

[0019] Preferably the first gas is stored in a reservoir. The reservoir may be in the form of a light weight cylinder. The cylinders may be a carbon fibre composite material.

[0020] Preferably the activation system activates the inflation system upon the buoyancy system experiencing activation criteria, or upon manual activation. The activation criteria may be dependent on the aircraft experiencing a change in one or more of the following conditions: pressure, temperature, velocity or water immersion. The activation system may comprise a detection system incorporating one or more sensors to detect the activation criteria. Each sensor may be adapted to detect different parameters. Preferably the activation system comprises a combination of sensors and may include hydrostatic, water, altimeter or shock or impact sensors.

[0021 ] The activation system may automatically activate immediately after the aircraft enters a body of water. The activation system may be hydrostatically activated when the aircraft reaches a predetermined depth. Preferably a sensor detects when the aircraft reaches the predetermined depth, whereupon the activation system activates the inflation system. The sensor may comprise one or more hydrostatically operated devices or other automatic activation sensors fitted to the buoyancy system. The predetermined depth may be selected such that at the predetermined depth there is minimal chance that any moving parts of the aircraft that could damage the inflatable body are still moving. Preferably the predetermined depth is 1 .2m.

[0022] Preferably the inflatable body is inflated within five seconds of the inflation system being activated. Preferably the inflatable body is inflated within three seconds of the inflation system being activated.

[0023] Preferably the buoyancy system arrests the descent of the aircraft before the aircraft is at a depth which causes the windows of the aircraft to implode.

[0024] Preferably the buoyancy system arrests the descent of the aircraft before the aircraft is at a depth of 7m.

[0025] Preferably, the at least one inflatable body is adapted to be positioned on the aircraft such that once inflated the positioning of the at least one inflatable body ensures the aircraft is maintained at the surface of the water. Preferably the aircraft is maintained in a condition which will allow its occupants to readily escape. In the case of a helicopter the buoyancy system typically orientates the helicopter with its nose out of the water and the cabin in a vertically upright plane or so that an air pocket is created inside the helicopter's cabin to allow occupants to breath.

[0026] The at least one inflatable body may take any shape and depends upon the aircraft it is to fitted. The at least one inflatable body may comprise one or straps there around for securing the buoyancy system to the aircraft.

[0027] In a deflated condition, the buoyancy system may be stored at a position on the aircraft which does not inhibit operation of the aircraft systems, including weapon systems, entry into the cabin, nor, once inflated, exit from the cabin.

[0028] Preferably once the at least inflatable body is inflated, the aircraft will remain at the surface of the water for a predetermined period of time. Preferably the period of time is five minutes or more. [0029] Preferably the at least one inflatable body is made from a gas tight material. This will ensure the gas is held in the inflatable body for a long period of time ensuring there is ample time to rescue the crew, and preferably the aircraft. The at least one inflatable body may be made from a material having a tensile strength greater than 7000N/5cm. The at least one inflatable body may be made from a light weight material of 500gsm or lower.

[0030] The at least one inflatable body may be made from Kevlar or similar type material.

[0031 ] The at least one inflatable body may comprise one or more pressure relief valves to release excess gas from the inflatable body and prevent over pressurisation, particularly as the aircraft ascends and the external pressure exerted by the water on the at least one inflatable body reduces.

[0032] The buoyancy system may be powered by its own independent power source or from a power source within the aircraft, or a combination of both. Preferably the independent power source is able to power the buoyancy system after five years of the buoyancy system being in storage. Preferably the independent power source is able to power the buoyancy system for at least 500 flying hours within a five year period.

[0033] Preferably the buoyancy system comprises a control unit which provides the activation system and the detection system. The control unit also provides a disarm system so that the buoyancy system can be disarmed to ensure accidental activation does not occur whilst maintenance staff are working on the aircraft, or while the buoyancy system is in storage. The disarm system may comprise a sensor, such as a Hall effect sensor which varies its operational mode based on the presence of a magnetic field, and a pin. The pin may provide the magnetic field, whereby when the pin is in place the magnetic field causes the sensor to retain the buoyancy system in an off state, and upon removal of the pin the magnetic field is removed, allowing the sensor to return the buoyancy system to a ready, or on state.

[0034] Preferably the control unit compensates for changes in operational conditions, such as changes in temperature and atmospheric pressure. This allows the buoyancy system to be used at different heights as well as different locations without the need for adjustment to compensate for the associated changes.

[0035] Preferably the control unit is in a potting compound to protect its components.

[0036] The buoyancy system may have a release means so that it can be detached/ jettisoned from the aircraft. The release means may be operated if the buoyancy system is unintentionally activated.

[0037] The present invention further provides an aircraft having at least one buoyancy system as substantially herein described secured thereto.

[0038] The aircraft may be fitted with more than one buoyancy system. When there is more than one buoyancy system attached to an aircraft, the inflation system of each buoyancy system may be arranged to activate under the same conditions or under different conditions.

[0039] Preferably the buoyancy system may be easily attached and detached from the aircraft. As the buoyancy system is only required for aircraft flying over large bodies of water, it is desirable to be able to easily attach and detach the buoyancy system to the aircraft to suit the aircrafts mission. In contrast to the prior art, the buoyancy system of this invention is configured to allow a technician to easily attach or detach the buoyancy system, as opposed to being permanently fixed to the aircraft. The present invention is also configured so that it may be attached or detached on the base, or in the field. Preferably the buoyancy system may be attached to the aircraft by two technicians in less than 10 minutes.

[0040] The present invention provides an inflation system for a buoyancy/floatation system, the inflation system enables rapid inflation/deployment of an inflatable body, the inflation system comprises: a reservoir of a first gas; a gas generation system for generating a second gas, the second gas being at a higher temperature to that of the first gas, the gas generation system being housed in a hollow body; an activation means to activate the inflation system; whereupon activation of the inflation system the first gas is released from the reservoir and passes into the hollow body, the gas generation system produces the second gas, wherein the first gas leaving the reservoir is caused to mix with the second gas to provide a third gas which is at a temperature between the first gas and the second gas.

[0041 ] Preferably the gas generation system is housed in a shroud. The shroud may be located in the hollow body. The shroud may be cylindrical in shape and have a plurality of holes in an outer surface such that the second gas is ejected from the shroud in a radial direction.

[0042] The third gas may be ejected from the hollow body in a direction which assists deployment of the inflation system and therefore inflation of the buoyancy body.

[0043] The gas generation system may comprise a gas generating medium such as for example an explosive, propellant or other chemical compound contained within at least one vessel, whereby a charge activates the medium, creating the second gas within the at least one vessel at pressure. The medium may be activated by an initiator or a detonator which is operably connected to the activation system. The gas generation system may comprise more than one initiator or detonator in the event that one or more of the initiators or detonators does not function correctly. The second gas is at a high temperature and requires to be cooled prior to coming into direct contact with the inflatable body. This is achieved by mixing the second gas with the first gas to form the third gas. The third gas is a combination of the first gas and the second gas and is at a temperature between the temperature of the two gases prior to mixing.

[0044] The hollow body may be in the form of a sleeve having an inlet and an outlet. The sleeve may support the shroud such that the shroud is co-axially supported therein whereby an annular passage is formed between the shroud and the sleeve. The sleeve may incorporate one or more mixing means within the passage, such as baffle plates, to enhance the mixing of the first gas and the second gas.

[0045] An outlet of the reservoir may align with or be connected to the inlet of the sleeve such that the first gas passes into the sleeve when released from the reservoir. The reservoir may comprise a gas storage cylinder containing the first gas. Preferably the gas storage cylinder is elongated.

[0046] When the inflation system is in a closed condition the outlet of the reservoir is closed/in the form of a nib or disk, whereupon activation of the activation system a squib or an explosive device is ignited to rupture the nib or disk to allow the first gas to be discharged from the reservoir. The squib or explosive device may be located adjacent the nib or disk.

[0047] The first gas and the second gas may be different gases. In an alternative embodiment the first gas and the second gas are substantially the same gases

[0048] The inflation system may be located in an inflatable body removing the need for hoses and/or constricting orifices to direct the gas to the inflatable body. This not only reduces the weight and volume of the inflatable system but also removes components which retard the rate of inflation of the inflatable body.

[0049] The inflatable body may have a maximum volume exceeding one cubic metre. Preferably the inflatable body has a volume of 1 .5m³.

[0050] The activation system may be activated in a variety of ways, largely dictated by the particular application. The buoyancy system may incorporate a plurality of activation systems.

[0051 ] The activation system may be adapted to activate automatically when the object is at a predetermined depth or when immersed in water.

[0052] The activation system may be hydrostatically activated when the buoyancy/floatation system reaches a predetermined depth. The automatic activation system may comprise one or more hydrostatically operated devices/sensors.

[0053] The activation system may comprise an override mechanism so that the automatic operation of the activation system can be disabled should it be required.

[0054] The activation system may be acoustically operated. [0055] The activation system may be manually operated.

[0056] The inflation system may be powered from a generated power supply or from an internal power supply or battery pack.

[0057] The inflation system as hereinbefore describes allows for rapid inflation of the inflatable body. Research has shown that when a helicopter crashes or ditches into a body of water, the crew and personnel on-board are more at risk from drowning in the fast-sinking vehicle, than from direct injuries caused by the crash itself. The inflation system enhances the speed in which the inflatable body is able to inflate by having the inflation system located within the inflatable body. This removes the restrictions and delay which are caused by connecting hoses and/or other components used to connect the gas inflation system to the inflatable body.

[0058] The present invention further provides a helicopter or other aircraft wherein one or more inflation systems as herein described are fitted thereto to inflate one or more inflatable bodies secured to the aircraft. The one or more inflation systems may be strategically placed on the aircraft to ensure the aircraft is returned to and retained in a desired orientation.

[0059] The present invention provides a high volume rapid inflation system used as part of a buoyancy or floatation system for rapid inflation/deployment of an inflatable body generally over an inflated volume of one cubic meter, the system comprises: at least one compressed gas source, providing cold gas which, post release, mixes with a hot gas source; at least one energetic/pyrotechnic gas source, providing hot gas which, post release, mixes with a cold gas source; a means of activation incorporated into the inflatable body to activate the inflation system; where the inflation gas source or sources and a means of activation is contained inside the inflatable body.

[0060] The present invention generally relates to inflatable bodies with an inflated volume of one cubic metre or more.

[0061 ] Preferably the at least one compressed gas source will contain a gas suitable for cooling hot gasses.

[0062] Preferably the at least one compressed gas source will be release immediately prior to or concurrently with the at least one energetic/pyrotechnic gas source.

[0063] Preferably the at least one compressed gas source will be released by the activation of an energetic/pyrotechnic device.

[0064] Preferably the cold gas released by the at least one compressed gas source will flow over or be released in the vicinity of the at least one energetic/pyrotechnic gas source allowing the hot and cold gases to mix upon activation of the at least one energetic/pyrotechnic gas source. During the activation of the gas sources, the cold gas cools the hot gas and hot gas heats the cold gas to produce a resultant gas temperature that protects the inflatable body from damage and provides a rapid gas volume to achieve full inflation of the inflatable body.

[0065] Preferably the at least one energetic/pyrotechnic gas source will generate gas from a pyrotechnic, explosive or energetic chemical reaction immediately upon activation of the preferably the at least one energetic/pyrotechnic gas source. [0066] This invention provides the next generation in inflation technology for inflating gas tight inflatable bodies where large volumes are required generally over one cubic meter. This new generation of large volume rapid inflation technology will allow inflatable bodies to be inflated faster in emergency situations and weigh considerably less than current technology.

[0067] The present invention further provides a buoyancy system for keeping an aircraft afloat, and in an orientation so as to create an air pocket within the cabin, upon landing, crashing or ditching into a body of water, the system comprises: an inflatable body which, when inflated, increases the buoyancy of the aircraft; an inflation system located in the inflatable body to inflate the inflatable body from within the inflatable body; a sensor and activation system to activate the inflation system; where upon meeting activation criteria or upon manual activation, the sensor and activation system will activate the inflation system causing a gas to inflate the inflatable body, which once inflated to the required volume assists the aircraft to remain positively buoyant at the surface of a body of water.

[0068] The present invention further provides a buoyancy system wherein one or more of the buoyancy systems are adapted to be fitted to a helicopter for keeping the helicopter afloat upon landing, crashing or ditching into a body of water, the/each buoyancy system comprises: an inflatable body which, when inflated, increases the buoyancy of the helicopter, the inflatable body being positioned on the helicopter such that once inflated the helicopter is maintained in a vertically upright position or in an orientation so as to create an air pocket within the cabin; an inflation system located in the inflatable body to inflate the inflatable body; a sensor and activation system to activate the inflation system whereupon meeting activation criteria or upon manual activation, the sensor and activation system will activate the inflation system causing a gas to inflate the inflatable body, which once inflated to the required volume assists the helicopter to remain positively buoyant at the surface of a body of water; a deployment device, the deployment device restricting the inflation of the at least one inflatable body until the blades of the helicopter have detached from the helicopter or otherwise stopped rotating.

[0069] The deployment device may comprise a sensor which senses when the helicopter has reached a depth wherein potentially damaging moving parts have stopped moving. The depth may be 1 .2m.

[0070] The present invention further provides a buoyancy system wherein one or more of the buoyancy systems are adapted to be fitted to a helicopter for maintaining the helicopter afloat and in a favourable orientation for escape, upon crashing or ditching into a body of water, the buoyancy system having substantially no impact on the flight performance of the helicopter when fitted thereto, the buoyancy system comprises: an inflatable body which, when inflated, increases the buoyancy of the helicopter; an inflation system to inflate the inflatable body, the inflation system comprises a a first gas; a gas generation system for generating a second gas, the second gas being at a higher temperature than the first gas, the gas generation system being housed in a hollow body, wherein the gas generation system comprises a gas generating medium whereby a charge activates the medium to create the second gas; a control unit to activate the inflation system where upon meeting crash activation criteria, the control unit will activate the inflation system causing the first gas to pass into the hollow body, the gas generation system produces the second gas, wherein the first gas is caused to mix with the second gas to form a third gas, the third gas inflating the inflatable body to the desired level of inflation.

[0071 ] The present invention further provides an aircraft buoyancy system for maintaining the aircraft afloat after crashing or ditching into a body of water, the buoyancy system comprises: a plurality of inflatable bodies which, when inflated, increases the buoyancy of the aircraft, each inflatable body housing an inflation system to inflate the inflatable body; the inflation system comprises a reservoir of a cold gas and a gas generation system which generates a hot gas, wherein an activation system activates the inflation system upon the aircraft experiencing one or more predetermined crash activation criteria, upon activation the inflation system releases the cold gas into a hollow body in which the hot gas is generated whereupon mixing the resultant gas inflates the inflatable body.

[0072] The buoyancy system may comprise a deployment means wherein the deployment means is in the form of a delay device, the deployment means preventing the at least one inflatable body from inflating until after a prescribed period of time or prescribed depth is achieved following activation of the activation system, such that in operation the deployment means prevents the inflation of the at least one inflatable body until the at least one inflatable body can be inflated without being damaged by moving parts of the aircraft. Preferably the delay device delays inflation of the plurality of inflatable bodies until a depth of 1 .2m or greater is reached. [0073] The hot gas generated by the gas generation system may be in excess of 600° C (1 1 10°F).

[0074] The present invention further provides an aircraft having at least one buoyancy system as substantially herein described secured thereto.

[0075] The aircraft may be fitted with more than one buoyancy system. When there is more than one buoyancy system attached to an aircraft, the inflation system of each buoyancy systems may be arranged to activate under the same conditions or under different conditions.

[0076] Preferably the buoyancy system returns the aircraft to the water surface within 30 seconds of the buoyancy system being activated.

[0077] Preferably the buoyancy system prevents the aircraft from being completely submerged.

[0078] Preferably the buoyancy system returns the aircraft to the water surface within 30 seconds of the aircraft hitting the water.

[0079] Preferably the buoyancy system retains the aircraft at the water surface for at least five minutes and preferably until the aircraft has been recovered.

[0080] Preferably each buoyancy system weighs 33kgs or less.

[0081 ] Preferably each buoyancy system weighs 25kgs or less.

[0082] Preferably each buoyancy system weighs 20kgs or less

[0083] Preferably the buoyancy system is unaffected after operating at altitudes of altitudes of 4270m (14000ft) or less.

Brief Description of the Drawings

[0084] The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings in which: Figure 1 a, b, c are side, plan and front views of a helicopter (Tiger ARH) having a buoyancy system according to a first embodiment of the invention installed under each snub wing;

Figure 2 a, b, c are similar views to figure 1 a, b, c but with the buoyancy system deployed;

Figure 3 and 4 are perspective views of a casing containing a buoyancy system, the buoyancy/floatation system comprising an inflation system according to an embodiment of the present invention;

Figure 5 is a perspective view of a reservoir and a gas generation system of the inflation system secured to a portion of a housing;

Figure 6 is a perspective view of the inflation system;

Figure 7 is a side view of a shroud which houses the gas generation system;

Figure 8 is a side view of a squib device used to cause the reservoir to open;

Figure 9 is a perspective view of a pin of a disarm system in position.

Figure 10 is a perspective view of an inflated inflatable body showing the location of the inflation system;

Figure 1 1 is a view of the inflatable body once inflated relative to the housing; and

Figure 12 is a perspective view of a reservoir and a gas generation system of the inflation system secured to a portion of a housing according to an alternative embodiment and

Figure 13 is a perspective view of a pin arrangement for securing the buoyancy/floatation system to an aircraft.

Figure 14 a is a view of a helicopter (Tiger ARH) post ditching floating on the surface of a body of water with the buoyancy system activated; Figure 15a is a view of a helicopter (Tiger ARH) with a buoyancy system fitted;

Figure 15b is a view of the helicopter (Tiger ARH) in figure 15a in water in an upright orientation with the inflatable body deployed;

Figure 16a is a view of the helicopter (Tiger ARH) in figure 15a but with the inflatable bodies in a different position;

Figure 16b is a view of the helicopter (Tiger ARH) in figure 16a in water in an upright orientation with the inflatable body deployed;

Figure 17 a, b is a view of a helicopter (MRH 90) with multiple inbuilt and/or semi-permanent buoyancy systems fitted; and

Figure 17 c the helicopter (MRH 90) in figure 17a in water in an upright orientation with the inflatable bodies deployed;

Best Mode(s) for Carrying out the Invention

[0085] The present invention provides an inflation system 12 particularly suited to rapidly inflate volumes over one cubic meter. It is particularly suited to emergency situations where it is critical that the volume is inflated almost instantaneously. There are many applications for the inflation system described herein. These are considered to fall within the scope of the present application as would be understood by the person skilled in the art.

[0086] The below embodiments of the present invention discuss applications in which a helicopter ditches or crashes into a body of water. However, it is to be understood that the present invention may be fitted to other type of aircraft, those applications also being covered by the present invention.

[0087] A first embodiment of the present invention is in the form of a buoyancy system 14 incorporating the inflation system 12, wherein the buoyancy system 14 is fitted to a helicopter 15 where, after activation, the helicopter 15 is recovered and retained afloat at or near the surface of a body of water 16, typically with the nose sitting above the water surface. In this orientation the occupants of the helicopter are able to leave the helicopter or take advantage of an air pocket within the cabin.

[0088] In the present embodiment two buoyancy systems 14 are secured to the helicopter. The buoyancy systems 14 are designed to be quickly removed from, and easily attach to the helicopter 15. This ensures the weight of the helicopter can be optimised when flying over land where buoyancy systems are not required.

[0089] Figures 1 a, b, c show the helicopter 15 fitted with two buoyancy systems 14 under snub wings 20, whereby each buoyancy system 14 is in a stored condition, i.e. ready for activation.

[0090] Figure 2 a, b, c shows the buoyancy systems 14 after each buoyancy system has been activated and each inflatable body 1 has been deployed. The inflated shape of the inflatable body 1 can take any form depending on the aircraft and the desired orientation of the aircraft once it is at the water surface 16. A variation to the shape in figure 2 is shown in figure 10.

[0091 ] Each buoyancy system 14 comprises an inflatable body 1 which houses the inflation system 12. As the inflation system 1 2 is positioned inside the inflatable body to the inflatable body is able to rapidly inflate and arrest the sinking descent of the helicopter.

[0092] As shown in figures 3 and 4, each buoyancy system 14 is contained in a removable, sealed casing 18 that houses all the components thereof. The systems that comprise the buoyancy system 14 include the inflatable body 1 , the inflation system 12 to inflate the inflatable body 1 , an activation system 5, a housing 8 and attachment system to secure the buoyancy system 14 to the helicopter.

[0093] The inflation system 12 comprises a reservoir for storing a compressed first gas, and a gas generation system 33 for generating a second gas which is at a higher temperature than the first gas. The gas generation system 33 is housed in a hollow body 35. Located within the hollow body 35 is a shroud 37 which houses the gas generation system 33. The shroud 37 is cylindrical in shape and has a plurality of holes 39 in an outer surface such that the second gas is ejected from the shroud in a radial direction.

[0094] The hollow body 35 is in the form of a sleeve 41 having an inlet 43 and an outlet 45. The sleeve 41 supports the shroud 37 such that the shroud is co-axially supported therein whereby an annular passage is formed between the shroud and the sleeve in which the first gas and second gas mix.

[0095] The gas generation system 33 comprises a gas generating medium 3, whereby a charge activates the medium, creating the second gas. The medium is activated by an initiator which is operably connected to the activation system 5. Once generated the second gas is at a high temperature and requires to be cooled prior to coming into direct contact with the inflatable body. This is achieved by mixing the second gas with the first gas to form the third gas.

[0096] Upon activation of the inflation system 12 the first gas is released from the reservoir 31 and a portion passes into the hollow body 35 through the inlet 43 while a portion passes around the hollow body 35. Also the gas generation system 33 produces the second gas, wherein the first gas leaving the reservoir 31 is caused to mix with the second gas, cooling the second gas and form the mixed third gas. The third gas inflates the inflatable body 1 arresting the descent of the helicopter and returning the helicopter to the surface of the water.

[0097] When the inflation system 12 is in a closed condition an outlet 32 of the reservoir 31 is closed. Upon activation of the activation system a squib 57 ruptures the closed end to allow the first gas to be discharged from the reservoir.

[0098]

[0099] The activation system 5 comprises an automated trigger mechanism for post-crash emergencies upon detection of water and/or pressure through immersion and/or hydrostatic sensors which will automatically activate the inflation system. [00100] The housing 8 is specifically designed to interface directly to the particular aircraft's existing hard points or to suitably reinforced locations on the fuselage. The housing 8 is located so as not to interfere with normal aircraft operations and will allow the buoyancy system to operate appropriately.

[00101 ] Referring to figures 3, 4 and 7, the housing 8 comprises an upper housing and an outer cover 10. The cover 10 is fixed to the housing but is designed to be ejected upon activation as the inflatable body begins to inflate The cover 10 is made from a flexible material such that should a part of the cover 10 remain fixed to the housing during inflation the likelihood of puncturing the inflatable body 1 is reduced.

[00102] The upper housing 9 is made from a titanium and/or composite skeleton and includes the aircraft attachment fittings 1 1 .

[00103] The buoyancy system also comprises a control unit 47 which provides the activation system 5. The control unit also provides a disarm system 49 so that the buoyancy system can be disarmed to ensure accidental activation does not occur while maintenance staff are working on the aircraft, or while the buoyancy system is in storage. The disarm system 49 provides a system user interface and comprises a Hall effect sensor (not shown) which varies its operational mode based on the presence of a magnetic field which is provided by a pin 51 . When the pin is in place its magnetic field causes the sensor to retain the buoyancy system 14 in an off state, and upon removal of the pin 51 the magnetic field is removed, allowing the sensor to return the buoyancy system to a ready, or on state. As shown in figure 7 the upper housing 9, or in some applications the cover 10, supports the disarm system 49. The inflation system comprising the reservoir 31 storing the first gas, and the gas generation system 33 is secured inside the inflatable body 1 by a series straps 55 and material fixings welded or sewed to the inside of the buoyancy bag.

[00104] The buoyancy system 14 utilises hard points which are secured to the frame of the aircraft with a pin arrangement 53 (figure 1 1 ). The housing of the system provides hard points through which at least one strap 55 passes, as shown in figure 10. These straps pass around the inflatable body in which the inflation system is supported.

[00105] As identified in the above embodiment, this invention provides a light weight large volume rapid inflation solution for deploying and inflating inflatable bodies.

[00106] The inflation system of the present invention provides a light weight solution for inflating inflatable bodies with a large inflated volume generally over one cubic metre. The rapid inflation system is able to achieve full volume inside an inflatable body extremely fast, in less than a second when required, improving outcomes in emergency situation.

[00107] The present invention has many applications across numerous inflatable systems, especially in aviation and maritime environments. Certainly many more applications are also possible and these will come to light in the future, particularly owing to the human quest to make aircraft and marine transportation safer.

[00108] Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.

[00109] Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

The Claims Defining the Invention are as Follows:

1 . A buoyancy system adapted to be fitted to an aircraft for recovering and retaining the aircraft at the surface of a body of water, upon landing, crashing or ditching into the water, the buoyancy system comprises: a plurality of inflatable bodies which, when inflated, increases the buoyancy of the aircraft, each inflatable body having an inflation system to inflate the inflatable body, the infiation system provides a first gas and comprises: a gas generation system for generating a second gas, the second gas being at a higher temperature than the first gas, the gas generation system being housed in a hollow body; an activation system to activate the inflation system; whereupon activation of the inflation system the first gas passes into the hollow body, the gas generation system produces the second gas, wherein the first gas is caused to mix with the second gas to form a third gas, the third gas inflating the inflatable body to the desired level of inflation.

2. A buoyancy system adapted to be fitted to an aircraft for recovering and retaining the aircraft at the surface of a body of water, upon landing, crashing or ditching into the water, the buoyancy system comprises: an inflatable body which, when inflated, increases the buoyancy of the aircraft; an inflation system to inflate the inflatable body, the inflation system comprises; a reservoir comprising a first gas; a gas generation system for generating a second gas, the second gas being at a higher temperature than the first gas, the gas generation system being housed in a hollow body; an activation system to activate the inflation system; whereupon activation of the inflation system the first gas is released from the reservoir and passes into the hollow body, the gas generation system produces the second gas, wherein the first gas leaving the reservoir is caused to mix with the second gas to form a third gas, the third gas inflating the inflatable body to the desired level of inflation.

3. The buoyancy system according to any one of the preceding claims wherein the inflation system is incorporated within the inflatable body. This allows the direct inflation of the inflatable body. As soon as gas is generated from the inflation system the inflatable body begins to inflate. As the gas is generated rapidly the rate of inflation of the inflatable body is significantly quicker than prior art systems.

4. The buoyancy system of the present invention does not rely on hoses or other equipment to deliver the gas to the inflatable body. Neither does it rely on having to first pass the gas through a heat exchanger in order to cool the gas before it enters the inflatable body. This not only eliminates slow points in the delivery of the gas, it also reduces the weight of the inflation system which is a critical consideration when considering attaching a buoyancy system to an aircraft

5. The buoyancy system according to any one of the preceding claims wherein each inflatable body has one or more inflation systems incorporated therein.

8. The buoyancy system according to any one of the preceding claims wherein the gas generation system comprises a gas generating medium such as for example an explosive, propeiiant or other chemical compound whereby a charge activates the medium, creating the second gas.

7. The buoyancy system according to any one of the preceding claims wherein the first gas is stored in a reservoir. The reservoir is in the form of a light weight cylinder. The cylinders is a carbon fibre composite material.

8. The buoyancy system according to any one of the preceding claims wherein the activation system activates the inflation system upon the buoyancy system experiencing activation criteria, or upon manual activation. The activation criteria is dependent on the aircraft experiencing a change in one or more of the following conditions: pressure, temperature, velocity or water immersion. The activation system comprise a defection system incorporating one or more sensors to detect the activation criteria. Each sensor is adapted to detect different parameters. The buoyancy system according to any one of the preceding claims wherein the activation system comprises a combination of sensors and include hydrostatic, water, altimeter or shock or impact sensors.

9. The buoyancy system according to any one of the preceding claims wherein the activation system automatically activate immediately after the aircraft enters a body of water. The activation system is hydrosfaticaliy activated when the aircraft reaches a predetermined depth. The buoyancy system according to any one of the preceding claims wherein a sensor detects when the aircraft reaches the predetermined depth, whereupon the activation system activates the inflation system. The sensor comprise one or more hydrostatically operated devices or other automatic activation sensors fitted to the buoyancy system. The predetermined depth is selected such that at the predetermined depth there is minimal chance that any moving parts of the aircraft that could damage the inflatable body are still moving. The buoyancy system according to any one of the preceding claims wherein the predetermined depth is 1 .2m.

10. The buoyancy system according to any one of the preceding claims wherein the inflatable body is inflated within five seconds of the inflation system being activated. The buoyancy system according to any one of the preceding claims wherein the inflatable body is inflated within three seconds of the inflation system being activated.

1 1 . The buoyancy system according to any one of the preceding claims wherein the buoyancy system arrests the descent of the aircraft before the aircraft is at a depth which causes the windows of the aircraft to implode.

12. The buoyancy system according to any one of the preceding claims wherein the buoyancy system arrests the descent of the aircraft before the aircraft is at a depth of 7m.

13. The buoyancy system according to any one of the preceding claims wherein, the at least one inflatable body is adapted to be positioned on the aircraft such that once inflated the positioning of the at least one inflatable body ensures the aircraft is maintained at the surface of the water. The buoyancy system according to any one of the preceding claims wherein the aircraft is maintained in a condition which will allow its occupants to readily escape, !n the case of a helicopter the buoyancy system typically orientates the helicopter with its nose out of the water and the cabin in a vertically upright plane or so that an air pocket is created inside the helicopters cabin to allow occupants to breath.

14. The buoyancy system according to any one of the preceding claims wherein the at least one inflatable body takes any shape and depends upon the aircraft it is to fitted. The at least one inflatable body comprise one or straps there around for securing the buoyancy system to the aircraft.

15. The buoyancy system according to any one of the preceding claims wherein in a deflated condition, the buoyancy system is stored at a position on the aircraft which does not inhibit operation of the aircraft systems, including weapon systems, entry into the cabin, nor, once inflated, exit from the cabin.

16. The buoyancy system according to any one of the preceding claims wherein once the at least inflatable body is inflated, the aircraft will remain at the surface of the water for a predetermined period of time. The buoyancy system according to any one of the preceding claims wherein the period of time is five minutes or more.

17. The buoyancy system according to any one of the preceding claims wherein the at least one inflatable body is made from a gas tight material. This will ensure the gas is held in the inflatable body for a long period of time ensuring there is ample time to rescue the crew,

18. The buoyancy system according to any one of the preceding claims wherein the aircraft. The at least one inflatable body is made from a material having a tensile strength greater than 7000N/5cm. The at least one inflatable body is made from a light weight material of 500gsm or lower.

19. The buoyancy system according to any one of the preceding claims wherein the at least one inflatable body is made from Kevlar or similar type material.

20. The buoyancy system according to any one of the preceding claims wherein the at least one inflatable body comprise one or more pressure relief valves to release excess gas from the inflatable body and prevent over pressurisation, particularly as the aircraft ascends and the external pressure exerted by the water on the at least one inflatable body reduces.

21 . The buoyancy system according to any one of the preceding claims wherein the buoyancy system is powered by its own independent power source or from a power source within the aircraft, or a combination of both. The buoyancy system according to any one of the preceding claims wherein the independent power source is able to power the buoyancy system after five years of the buoyancy system being in storage. The buoyancy system according to any one of the preceding claims wherein the independent power source is able to power the buoyancy system for at least 500 flying hours within a five year period.

22. The buoyancy system according to any one of the preceding claims wherein the buoyancy system comprises a control unit which provides the activation system and the detection system. The control unit also provides a disarm system so that the buoyancy system can be disarmed to ensure accidental activation does not occur whilst maintenance staff are working on the aircraft, or while the buoyancy system is in storage. The disarm system comprise a sensor, such as a Hall effect sensor which varies its operational mode based on the presence of a magnetic field, and a pin. The pin provide the magnetic field, whereby when the pin is in place the magnetic field causes the sensor to retain the buoyancy system in an off state, and upon removal of the pin the magnetic field is removed, allowing the sensor to return the buoyancy system to a ready, or on state.

23. The buoyancy system according to any one of the preceding claims wherein the control unit compensates for changes in operational conditions, such as changes in temperature and atmospheric pressure. This allows the buoyancy system to be used at different heights as well as different locations without the need for adjustment to compensate for the associated changes.

24. The buoyancy system according to any one of the preceding claims wherein the control unit is in a potting compound to protect its components.

25. The buoyancy system has a release means so that it can be detached/ jettisoned from the aircraft. The release means is operated if the buoyancy system is unintentionally activated.

26. An aircraft having at least one buoyancy system according to any one of the preceding claims secured thereto.

27. The buoyancy system according to any one of the preceding claims wherein the buoyancy system is easily attached and detached from the aircraft. As the buoyancy system is only required for aircraft flying over large bodies of water, it is desirable to be able to easily attach and detach the buoyancy system to the aircraft to suit the aircrafts mission. In contrast to the prior art, the buoyancy system of this invention is configured to allow a technician to easily attach or detach the buoyancy system, as opposed to being permanently fixed to the aircraft. The present invention is also configured so that it is attached or detached on the base, or in the field. The buoyancy system according to any one of the preceding claims wherein the buoyancy system is attached to the aircraft by two technicians in less than 10 minutes.

28. An inflation system for a buoyancy/floatation system, the inflation system enables rapid inflation/deployment of an inflatable body, the inflation system comprises: a reservoir of a first gas; a gas generation system for generating a second gas, the second gas being at a higher temperature to that of the first gas, the gas generation system being housed in a hollow body; an activation means to activate the inflation system; whereupon activation of the inflation system the first gas is released from the reservoir and passes into the hollow body, the gas generation system produces the second gas, wherein the first gas leaving the reservoir is caused to mix with the second gas to provide a third gas which is at a temperature between the first gas and the second gas.

29. The buoyancy system according to any one of the preceding claims wherein the gas generation system is housed in a shroud. The shroud is located in the hollow body. The shroud is cylindrical in shape and have a plurality of holes in an outer surface such that the second gas is ejected from the shroud in a radial direction.

30. The buoyancy system according to any one of the preceding claims wherein the third gas is ejected from the hollow body in a direction which assists deployment of the inflation system and therefore inflation of the buoyancy body.

31 . The buoyancy system according to any one of the preceding claims wherein the gas generation system comprise a gas generating medium such as for example an explosive, propeliant or other chemical compound contained within at least one vessel, whereby a charge activates the medium, creating the second gas within the at least one vessel at pressure. The medium is activated by an initiator or a detonator which is operably connected to the activation system. The gas generation system comprise more than one initiator or detonator in the event that one or more of the initiators or detonators does not function correctly. The second gas is at a high temperature and requires to be cooled prior to coming into direct contact with the inflatable body. This is achieved by mixing the second gas with the first gas to form the third gas. The third gas is a combination of the first gas and the second gas and is at a temperature between the temperature of the two gases prior to mixing.

32. The buoyancy system according to any one of the preceding claims wherein the hollow body is in the form of a sleeve having an inlet and an outlet. The sleeve support the shroud such that the shroud is co-axialiy supported therein whereby an annular passage is formed between the shroud and the sleeve. The sleeve incorporate one or more mixing means within the passage, such as baffle plates, to enhance the mixing of the first gas and the second gas.

33. The buoyancy system according to any one of the preceding claims wherein an outlet of the reservoir align with or be connected to the inlet of the sleeve such that the first gas passes into the sleeve when released from the reservoir. The reservoir comprise a gas storage cylinder containing the first gas. The buoyancy system according to any one of the preceding claims wherein the gas storage cylinder is elongated.

34. The buoyancy system according to any one of the preceding claims wherein the When the inflation system is in a closed condition the outlet of the reservoir is closed/in the form of a nib or disk, whereupon activation of the activation system a squib or an explosive device is ignited to rupture the nib or disk to allow the first gas to be discharged from the reservoir. The squib or explosive device is located adjacent the nib or disk.

35. The buoyancy system according to any one of the preceding claims wherein the first gas and the second gas is different gases, !n an alternative embodiment the first gas and the second gas are substantially the same gases

38. The buoyancy system according to any one of the preceding claims wherein the inflation system is located in an inflatable body removing the need for hoses and/or constricting orifices to direct the gas to the inflatable body. This not only reduces the weight and volume of the inflatable system but also removes components which retard the rate of inflation of the inflatable body.

37. The buoyancy system according to any one of the preceding claims wherein the inflatable body has a maximum volume exceeding one cubic metre. The buoyancy system according to any one of the preceding claims wherein the inflatable body has a volume of 1 .5m³.

38. The buoyancy system according to any one of the preceding claims wherein the activation system is activated in a variety of ways, largely dictated by the particular application. The buoyancy system incorporate a plurality of activation systems.

39. The buoyancy system according to any one of the preceding claims wherein the e activation system is adapted to activate automatically when the object is at a predetermined depth or when immersed in water.

40. The buoyancy system according to any one of the preceding claims wherein the activation system is hydrostatically activated when the buoyancy/floatation system reaches a predetermined depth. The automatic activation system comprise one or more hydrostatically operated devices/sensors.

41 . The buoyancy system according to any one of the preceding claims wherein the activation system comprise an override mechanism so that the automatic operation of the activation system can be disabled should it be required.

42. The buoyancy system according to any one of the preceding claims wherein the activation system is acoustically operated.

43. The buoyancy system according to any one of the preceding claims wherein the activation system is manually operated.

44. The buoyancy system according to any one of the preceding claims wherein the inflation system is powered from a generated power supply or from an interna! power supply or battery pack.

45. A helicopter or other aircraft wherein one or more inflation systems as according to any one of the preceding claims are fitted thereto to inflate one or more inflatable bodies secured to the aircraft. The one or more inflation systems is strategically placed on the aircraft to ensure the aircraft is returned to and retained in a desired orientation.

48. A high volume rapid inflation system used as part of a buoyancy or floatation system for rapid inflation/deployment of an inflatable body generally over an inflated volume of one cubic meter, the system comprises: at least one compressed gas source, providing cold gas which, post release, mixes with a hot gas source; at least one energetic/pyrotechnic gas source, providing hot gas which, post release, mixes with a cold gas source; a means of activation incorporated into the inflatable body to activate the inflation system; where the inflation gas source or sources and a means of activation is contained inside the inflatable body.

47. The present invention generally relates to inflatable bodies with an inflated volume of one cubic metre or more.

48. The buoyancy system according to any one of the preceding claims wherein the at least one compressed gas source will contain a gas suitable for cooling hot gasses.

49. The buoyancy system according to any one of the preceding claims wherein the at least one compressed gas source will be release immediately prior to or concurrently with the at least one energetic/pyrotechnic gas source.

50. The buoyancy system according to any one of the preceding claims wherein the at least one compressed gas source will be released by the activation of an energetic/pyrotechnic device.

51 . The buoyancy system according to any one of the preceding claims wherein the cold gas released by the at least one compressed gas source will flow over or be released in the vicinity of the at least one energetic/pyrotechnic gas source allowing the hot and cold gases to mix upon activation of the at least one energetic/pyrotechnic gas source. During the activation of the gas sources, the cold gas cools the hot gas and hot gas heats the cold gas to produce a resultant gas temperature that protects the inflatable body from damage and provides a rapid gas volume to achieve full inflation of the inflatable body.

52. The buoyancy system according to any one of the preceding claims wherein the at least one energetic/pyrotechnic gas source will generate gas from a pyrotechnic, explosive or energetic chemical reaction immediately upon activation of the preferably the at least one energetic/pyrotechnic gas source.

53. This invention provides the next generation in inflation technology for inflating gas tight inflatable bodies where large volumes are required generally over one cubic meter. This new generation of large volume rapid inflation technology will allow inflatable bodies to be inflated faster in emergency situations and weigh considerably less than current technology.

54. A buoyancy system for keeping an aircraft afloat, and in an orientation so as to create an air pocket within the cabin, upon landing, crashing or ditching into a body of water, the system comprises: an inflatable body which, when inflated, increases the buoyancy of the aircraft; an inflation system located in the inflatable body to inflate the inflatable body from within the inflatable body; a sensor and activation system to activate the inflation system; where upon meeting activation criteria or upon manual activation, the sensor and activation system will activate the inflation system causing a gas to inflate the inflatable body, which once inflated to the required volume assists the aircraft to remain positively buoyant at the surface of a body of water, A buoyancy system wherein one or more of the buoyancy systems are adapted to be fitted to a helicopter for keeping the helicopter afloat upon landing, crashing or ditching into a body of water, the/each buoyancy system comprises: an inflatable body which, when inflated, increases the buoyancy of the helicopter, the inflatable body being positioned on the helicopter such that once inflated the helicopter is maintained in a vertically upright position or in an orientation so as to create an air pocket within the cabin; an inflation system located in the inflatable body to inflate the inflatable body; a sensor and activation system to activate the inflation system whereupon meeting activation criteria or upon manual activation, the sensor and activation system will activate the inflation system causing a gas to inflate the inflatable body, which once inflated to the required volume assists the helicopter to remain positively buoyant at the surface of a body of water; a deployment device, the deployment device restricting the inflation of the at least one inflatable body until the blades of the helicopter have detached from the helicopter or otherwise stopped rotating.

56. The deployment device comprise a sensor which senses when the helicopter has reached a depth wherein potentially damaging moving parts have stopped moving. The depth is 1 .2m.

57. A buoyancy system wherein one or more of the buoyancy systems are adapted to be fitted to a helicopter for maintaining the helicopter afloat and in a favourable orientation for escape, upon crashing or ditching into a body of water, the buoyancy system having substantially no impact on the flight performance of the helicopter when fitted thereto, the buoyancy system comprises: an inflatable body which, when inflated, increases the buoyancy of the helicopter; an inflation system to inflate the inflatable body, the inflation system comprises a a first gas; a gas generation system for generating a second gas, the second gas being at a higher temperature than the first gas, the gas generation system being housed in a hollow body, wherein the gas generation system comprises a gas generating medium whereby a charge activates the medium to create the second

QHS, a control unit to activate the inflation system where upon meeting crash activation criteria, the control unit will activate the inflation system causing the first gas to pass into the hollow body, the gas generation system produces the second gas, wherein the first gas is caused to mix with the second gas to form a third gas, the third gas inflating the inflatable body to the desired level of inflation.

58. An aircraft buoyancy system for maintaining the aircraft afloat after crashing or ditching into a body of water, the buoyancy system comprises: a plurality of inflatable bodies which, when inflated, increases the buoyancy of the aircraft, each infiatable body housing an inflation system to inflate the infiatable body; the inflation system comprises a reservoir of a cold gas and a gas generation system which generates a hot gas, wherein an activation system activates the inflation system upon the aircraft experiencing one or more predetermined crash activation criteria, upon activation the inflation system releases the cold gas into a hollow body in which the hot gas is generated whereupon mixing the resultant gas inflates the inflatable body.

59. The buoyancy system comprise a deployment means wherein the deployment means is in the form of a delay device, the deployment means preventing the at least one inflatable body from inflating until after a prescribed period of time or prescribed depth is achieved following activation of the activation system, such that in operation the deployment means prevents the inflation of the at least one inflatable body until the at least one infiatable body can be inflated without being damaged by moving parts of the aircraft. The buoyancy system according to any one of the preceding claims wherein the delay device delays inflation of the plurality of inflatable bodies until a depth of 1 ,2m or greater is reached.

60. The hot gas generated by the gas generation system is in excess of 600° C (1 1 10°F).

61 . An aircraft having at least one buoyancy system as substantially herein described secured thereto,

62. The aircraft is fitted with more than one buoyancy system. When there is more than one buoyancy system attached to an aircraft, the inflation system of each buoyancy systems is arranged to activate under the same conditions or under different conditions.

83. The buoyancy system according to any one of the preceding claims wherein the buoyancy system returns the aircraft to the water surface within 30 seconds of the buoyancy system being activated.

64. The buoyancy system according to any one of the preceding claims wherein the buoyancy system prevents the aircraft from being completely submerged.

85. The buoyancy system according to any one of the preceding claims wherein the buoyancy system returns the aircraft to the water surface within 30 seconds of the aircraft hitting the water.

68. The buoyancy system according to any one of the preceding claims wherein the buoyancy system retains the aircraft at the water surface for at least five minutes

87. The buoyancy system according to any one of the preceding claims wherein until the aircraft has been recovered.

68. The buoyancy system according to any one of the preceding claims wherein each buoyancy system weighs 33kgs or less.

89. The buoyancy system according to any one of the preceding claims wherein each buoyancy system weighs 25kgs or less.

70. The buoyancy system according to any one of the preceding claims wherein each buoyancy system weighs 20kgs or less

71 . The buoyancy system according to any one of the preceding claims wherein the buoyancy system is unaffected after operating at altitudes of altitudes of 4270m (14000ft) or less.