Improved aircrew Anti-g garment

Abstract

An inflatable bladder (33, 41) is carried by an aircrew garment 5 (35, 43, 34, 42) worn on the body of the aircrew and to apply pressure to the body when inflated by a gas to counteract effects of high G-forces during flight. The garment and / or the bladder (33, 41, 49, 56) includes at least one sheet of flexible material that includes graphene.

Description

[0001] IMPROVED AIRCREW ANTI-G GARMENT

[0002] TECHNICAL FIELD

[0003]

[0001] The invention relates to aircrew ensembles worn by aircrew in flight which may include an inflatable bladder that is configured to be carried by an aircrew garment worn on the body of the aircrew and to apply pressure to the body when inflated by a gas to counteract effects of high G-forces during flight .

[0004] BACKGROUND TO THE INVENTION

[0005]

[0002] Aircrew such as pilots wear an ensemble including a protective suit when flying in aircraft . Traditionally the suit is either a single piece suit combining both jacket and trousers in a single garment or it is a two-piece suit with a separate j acket and trousers . Because of the potential of injury caused by fire in such aircraft then all the ensemble must pass flame tests using "Burn Manikins" or other testing .

[0006]

[0003] The ensemble may include also special equipment (aircrew life support equipment - ALSE) that protects the wearer against the effects of high G-acceleration or altitude and other potentially damaging factors . In this case, the ensemble provides an outer layer (the restrainer) that holds and positions and restrains the inflatable counter pressure bladders such that when they are inflated they apply pressure to the body. The combination of the inflatable bladders with the outer retainers can provide counter pressure to the legs when the wearer is being accelerated to reduce the effect of blood pooling in the lower limbs and / or can also provide counter pressure to the chest to counteract the effect of breathing pressurised gas when at altitude . Examples of this are shown in WO-A-2007 / 111981 and in US-A-6325754 .

[0007]

[0004] An inflatable chest counter pressure bladder is either incorporated into a vest or a j acket type garment which is worn by the pilot over the flight suit, or the bladder is incorporated into the jacket part of the flight suit . Inflatable lower Gbladders are either incorporated into a lower G garment, which is typically worn over the flight suit, or the bladders are incorporated into the trouser section of the flight suit .

[0008]

[0005] In some cases the bladders are made of a textile (nylon or polyester) which is coated with a gas / air-holding layer of an gas (e . g . air) impermeable material such as synthetic rubber (e . g . neoprene ) or thermo-plastic materials such as polyurethane (PU) and thermoplastic polyurethane (TPU) . Most bladders are now made of a TPU coated fabric type because TPU is a thermoplastic material which can be easily welded using high frequency or radio frequency or ultrasonic welding . The disadvantage of this type of bladder construction is that the bladders have poor characteristics in respect of weld strength, tear and tensile strength and are not Fire Resistant ( FR) and also may not Be Moisture Vapour Permeable (MVP) .

[0009]

[0006] The aircrew and their flight equipment is subj ected to extremes of potential for damage which include the following :

[0010] • Wear and tear as a result of the frequency of use and servicing and laundering . The flight garment may be worn and laundered several times in 24 hours which can cause excessive wear .

[0011] • Entering and exiting the aircraft places greater strain on the equipment and the potential for snagging . Each time a pilot gets into the ej ector seat and straps in and tightens straps and buckles it places loads on the equipment .

[0012] • If the pilot ej ects from the aircraft this can place great strain on the materials of the ALSE . The equipment must be able to withstand the "air blast" resulting from meeting up to 700 knots ( 1 , 300 kilometres per hour) air speed and unless the materials are strong enough they can be torn open. Also during "air blast" the blast can include fragments of materials that can penetrate the equipment and puncture it resulting in it failing in use .• On landing on the ground and if escape and evasion is required then damage can be caused by the environment tearing or puncturing the ALSE .

[0013]

[0007] There are broadly two types of lower G bladder assemblies . First, there is a full cover bladder assembly where the inflatable area of the bladder coverage is almost all of the lower limbs and abdomen. Such an inflatable bladder assembly can also be connected at ankle level to an inflatable lining of a flight boot or an inflatable sock lining the boot, or the boot can incorporate an inflatable lining . The counter pressure can be applied directly to the limbs by providing the assembly with a restraining cover with the bladder inflating underneath the restraining cover and the restraining cover allowing the expansion of the bladder only in a direction towards the limbs . Secondly, there is a partial cover bladder assembly (also called a "skeletal" or "five bladder" assembly) . In this case two or more bladders (up to 5 ) cover respective parts of the lower body and are positioned for example, over the leg bone (hence skeletal ) and also have a bladder area over the abdomen. In this case, each bladder applies tension to a restraining cover of the assembly as it inflates, which in turn then applies the counter pressure to the limbs through the tensioned cover material .

[0014]

[0008] Such bladder assemblies can be integrated into the trousers of a suit rather than being incorporated into a separate garment, as shown in WO-A-2007 / 111981 .

[0015]

[0009] Counter pressure assemblies whether jackets or vests or lower G bladder assemblies of the above types have a problem of placing an excessive thermal burden on the wearer . The full cover lower G assembly is the worst in terms of the thermal burden and also has a problem of being excessively bulky. Excessive thermal burden and the consequent hyperthermia on the aircrew increases their fatigue as well as sweat loss and dehydration and reduces aircrew concentration and missionendurance . Increased core temperature also reduces tolerance to the effects of high G acceleration .

[0016]

[0010] WO-A-2021 / 043640 discloses anti-G trousers are partially double-walled and partially single-walled and made from a tearresistant, refractory and stretch-resistant synthetic textile material of max . 130 gram / m2 . The single-walled areas are air-permeable . In the double-walled areas, airtight pockets are thereby formed which act as pneumatic muscles and contract when being inflated from an automatic pressure supply and thereby draw the adjacent single-layer textile pieces towards one another .

[0017] [ Oil ] WO-A-2012 / 041971 discloses an aircrew ensemble comprising a garment for covering at least a part of a body of a wearer and an inflatable counter-pressure bladder, carried by the garment . The inflatable counter-pressure bladder is formed from a moisture-vapour permeable material allowing the passage therethrough of perspiration from the wearer' s body. Such moisture-vapour permeable materials are not air-permeable or gas-permeable .

[0018] SUMMARY OF THE INVENTION

[0019]

[0012] Some embodiments of the invention provide an inflatable bladder system in which the materials are reinforced with graphene and configured to be carried by an aircrew garment worn on the body of the aircrew and to apply pressure to the body when inflated by a gas to counteract effects of high G-forces during flight .

[0020]

[0013] Some embodiments of the invention provide graphene reinforced aircrew ensembles worn by aircrew in flight . Reinforcing materials with graphene have been shown through testing to increase tensile and tear strength for a given thickness / weight of material, increase weld strength and increase Moisture Vapour Permeability (MVP) and give Flame Retardancy ( FR) characteristics .

[0014] As mentioned above, an ensemble may provide an outer layer (a restrainer) that holds and positions and restrains inflatable counter pressure bladders such that when they are inflated they apply pressure to the body. In some embodiments, the outer layer that restrains the bladder is made from a textile that incorporates graphene reinforced fibres . Previously the anti G garment outer retraining layer is made from a woven textile such as nylon or polyester . The disadvantage of these outer restraining layers is that the high repeated tensions that the bladders apply to the wearer will cause the restrainer material to "fatigue" and ultimately fail and tear . If this happens the G protection garment will fail and lead to the failure of the protection system which in turn could lead to the wearer losing consciousness (G LOG) and loss of the pilot and aircraft . Conventionally, the only way to overcome this is to use a heavier more substantial material and this in turn makes the garment heavier, bulkier and to have a greater thermal burden . Furthermore, the restrainer is preferably made of a material that is fire retardant and in some cases a "sacrificial layer" of a FR material, adding further to the weight and bulk of the system is used. The textile restrainer reinforced with graphene may be inherently FR and may require no outer FR covering . The combination of the graphene inflatable bladders with the outer graphene retainers can provide counter pressure to the legs when the wearer is being accelerated to reduce the effect of blood pooling in the lower limbs and / or can also provide counter pressure to the chest to counteract the effect of breathing pressurised gas when at altitude .

[0021]

[0015] As mentioned above, a disadvantage of conventional TPU bladder construction is that the bladders have poor characteristics in respect of weld strength, tear and tensile strength and are not FR and also may not be moisture vapour permeable (MVP) . In some embodiments of this invention a bladder system is provided whereby the TPU and the supporting textile ( if it the TPU coated onto a textile) include materials arereinforced with graphene . The graphene is incorporated into the TPU when it is being mixed and / or into the textile yarn material when it is being mixed before being extruded . Conventionally, to achieve the same level of strength in tear and tensile and weld strength, the weight / thickness of the TPU would have to be greater that the graphene reinforced TPU. The graphene bladders are therefore lighter and less bulky and may be inherently FR and may have greater MVP characteristics . In the case of such flight garments then the additional strength and resilience of the materials for a given weight is very important .

[0022]

[0016] According to one aspect of the invention, there is provided an aircrew ensemble comprising a garment for covering at least a part of a body of a wearer, and an inflatable counter-pressure bladder, carried by the garment, wherein the garment and / or the bladder includes at least one sheet of flexible material that includes graphene . The garment may be a G suit (also sometimes referred to as an anti-G suit ) that provides protection against high G forces .

[0023]

[0017] Graphene can be defined as a lattice of hexagonal carbon atoms having a single layer of atoms arranged in a honeycomb planar nanostructure . Graphene Nano Platelets (GNPs ) can be defined as platelet-shaped sheets of graphene stacked on top of one another . These graphitic stacks may have an average thickness of 1-2 nanometres . GNPs may possess many of the same properties as graphene . The graphene in the at least one sheet of flexible material, according to various embodiments of the invention, may be in the form of GNPs or other forms of graphene, including pure graphene .

[0024]

[0018] The sheet of material may also include polyurethane, PU, and / or thermoplastic polyurethane, TPU . Graphene may be dispersed into PU / TPU at the melt stage in the form of GNPs .

[0025]

[0019] The sheet of material may be formed from fibres , threads or yarn that contains graphene . The fibres, threads or yarn may be woven together to form the sheet of material . The fibres ,threads or yarn may also include polyurethane, PU, and / or thermoplastic polyurethane, TPU . Graphene may be dispersed into PU / TPU at the melt stage in the form of GNPs .

[0026]

[0020] Embodiments of the invention may provide aircrew ensembles using flexible polymer films (e . g . PU or TPU) incorporating graphene to create waterproof and / or gas (e . g . air) holding materials . Such incorporation of graphene into the PU / TPU film may increase its strength and contributes to the overall performance of the equipment .

[0027]

[0021] Embodiments of the invention may provide aircrew ensembles using one of more sheets of material, e . g . including PU or TPU, and incorporating graphene . Such incorporation of graphene into the sheet of material may increase its strength and flame retardance, and contributes to the overall performance of the equipment .

[0028]

[0022] The sheet of material may be f luid / gas / air impermeable . This allows the sheet of material to form a pressure holding inflatable item. Pressure holding inflatable items are normally referred to as "bladders" . Inflatable bladders can be inflated orally by mouth or from a compressed gas source such as a cylinder of compressed gas, e . g . CO2 .

[0029]

[0023] For example, aircrew ensembles may utilise a film of a flexible polymer typically for example PU or TPU in order to provide a barrier against a pressurised gas in the creation of inflatable structures to provide G protection .

[0030]

[0024] A flexible polymer, typically for example PU or TPU, film incorporating graphene may also be used to create a flexible material which is waterproof and can be used to manufacture aircrew ensembles .

[0031]

[0025] The sheet of material may have a thickness of between 100 and 150pm.

[0032]

[0026] The sheet of material may include between 1 and 10% graphene (by weight ) , preferably 1.5% graphene by weight .Samples of a number of different percentages of graphene by weight ranging from 1% to 5% were tested in four ways - being breaking force , puncture resistance , weld strength and tear strength . The most effective percentage of GNPs within the TPU was found to be 1 . 5% .

[0033]

[0027] The sheet of material may be moisture-vapour permeable . This may improve comfort of a garment and allow the passage of perspiration through the material .

[0034]

[0028] The sheet of material may be flame retardant ( e . g . it will be less damaged by fire than a non-graphene including sheet of material ) .

[0035]

[0029] The aircrew ensemble may include first and second sheets of material , one of which is said at least one sheet of flexible material that includes graphene .

[0036]

[0030] The first sheet of material may be arranged to support the second sheet of flexible material .

[0037]

[0031] The second sheet of flexible material may have a lower modulus of elasticity than the first sheet of material .

[0038]

[0032] The second sheet of flexible material may be bonded to the first sheet of material .

[0039]

[0033] The second sheet material may be separate from the first sheet of material .

[0040]

[0034] The second sheet of material flexible material may form at least part of the inflatable bladder .

[0041]

[0035] The first sheet of material may be configured to limit the expansion of the inflatable bladder .

[0042]

[0036] The sheet of flexible material that includes graphene may be connected to another sheet of material by an in shear and / or in peel connection .

[0037] The aircrew ensembles may have at least one further nongraphene sheet of material ( i . e . a sheet of material that does not contain graphene ) . The non-graphene sheet of material may support the sheet of flexible material that includes graphene . The sheet of flexible material that includes graphene may have a lower modulus of elasticity the non-graphene sheet of material . The non-graphene supporting sheet of material may limit the expansion or stretching of the sheet of flexible material that includes graphene (e . g . as a bladder incorporating the sheet of flexible material that includes graphene) . The non-graphene supporting sheet of material may protect the sheet of flexible material that includes graphene from abrasion or other damage . Alternatively, the supporting sheet of material may include graphene, and the sheet of material supported by the supporting sheet of material may or may not include graphene .

[0043]

[0038] In some embodiments, the at least one sheet of flexible material of the aircrew ensemble that includes graphene is a gas-permeable material allowing the passage of the gas therethrough to cool the body.

[0044]

[0039] In some embodiments, the aircrew ensemble is provided in combination with an inflation system for inflating the bladder when a threshold G-force is detected acting on the wearer' s body, the inflation system also being operable in the absence of said threshold G-force to cause gas to pass through the gas-permeable material of the bladder to increase the cooling of the wearer' s body.

[0045]

[0040] The bladder may include at least one of the sheets of material that includes graphene and is configured to control the maximum rate of passage of the gas therethrough such that the bladder remains sufficiently inflated to counteract effects of high G-forces during flight .

[0046]

[0041] The bladder may include a plurality of formations on an internal surface thereof to facilitate passage of the gas between the formations .

[0042] The bladder may include a plurality of regions , each having a different gas-permeability. For example, a one of the regions with a relatively low gas-permeability is located to be positioned in use at a region of the wearer' s body that requires greater protection from G forces .

[0047]

[0043] The garment may include at least one of the sheets of material that includes graphene and which is inextensible, inflation of the bladder causing the bladder to act against the inextensible sheet to apply counter-pressure to the wearer' s body .

[0048]

[0044] The garment may include two sheets, the inflatable bladder being located between said two sheets, and wherein at least one of the two sheets is one of the sheets of material that includes graphene .

[0049]

[0045] Advantageously, the same gas supply may be used to counteract effects of high G-forces and cool the body of the aircrew. Conveniently, the gas supply may be from a supply of air on an aircraft that is used to help the aircrew breathe .

[0050]

[0046] The bladder is preferably configured to control the maximum rate of passage of the gas therethrough such that the bladder remains sufficiently inflated to counteract effects of high G-forces during flight .

[0051]

[0047] The graphene bladder may include a plurality of formations in the internal surface thereof to facilitate passage of the gas there between.

[0052]

[0048] According to another embodiment, there is provided aircrew ensemble comprising a garment for covering at least a part of a body of a wearer and an inflatable counter-pressure bladder, carried by the garment, the inflatable counter-pressure bladder being formed from a graphene reinforced gas-permeable materialallowing the passage therethrough of gas to cool the wearer' s body .

[0053]

[0049] An ensemble may be provided in combination with an inflation system for inflating the bladder when a threshold G-force is detected acting on the wearer' s body, the inflation system also being operable in the absence of said threshold G-force to cause gas to pass through the gas-permeable material of the bladder to increase the cooling of the wearer' s body. This advantageously allows cooling of the wearer in non-high-G situations .

[0054] BRIEF DESCRIPTION OF THE DRAWINGS

[0055]

[0050] For a better understanding of the present invention embodiments will now be described by way of example, with reference to the accompanying drawings , in which :

[0056] Figure 1 is a general view of an aircrew ensemble including a chest counter-pressure assembly and full cover lower G assembly,

[0057] Figure 2 is a section on the line X-X of Figure 1 , Figure 3 is a cross-section on the line Z-Z of Figure 1, Figures 4A and 4B are alternative partial cross-sections on the line X-X or Z-Z of Figure 1 showing the passage of gas through the lower G assembly in respective first and second different embodiments,

[0058] Figure 5 is a similar view to Figure 1 but showing a partial cover lower G assembly,

[0059] Figure 6 is a cross-section on the line Y-Y of Figure 5 through a lower G bladder of the assembly of Figure 5 , Figures 7A and 7B are cross-sections on the line Z-Z of Figure 1 showing, deflated and inflated respectively, a second form of lower G bladder of the assembly,

[0060] Figures 8A and 8B are cross-sections on the line Z-Z of Figure 1 showing, deflated and inflated respectively, a third form of lower G bladder of the assembly,Figure 9 is a similar view to Figure 1 but showing an aircrew ensemble with an alternative form of chest counter pressure assembly and full cover lower G assembly,

[0061] Figure 10 is a schematic view of a grill bladder for the ensemble of Figure 9,

[0062] Figure 11 is a schematic view of a finger bladder for the ensemble of Figure 9,

[0063] Figure 12 is a cross-section on the line X-X of Figure 9 showing the inflation of a chest bladder of the chest counter pressure assembly of Figure 9,

[0064] Figures 13A and 13B are cross-sections on the line Y-Y of Figure 9 showing a bladder of the lower G assembly respectively deflated ( 13A) and inflated ( 13B) ,

[0065] Figures 14A, 14B, 14C and 14D are partial cross-sectional views of an alternative embodiment of bladder for the ensemble of Figure 9 in which the bladder is self-tightening, Figures 14A and 14C showing the bladder un-inflated and Figures 14B and 14D showing the bladder inflated,

[0066] Figure 14E is a similar view to Figures 14A, 14B, 14C and 14D but showing a known non-self-tightening bladder,

[0067] Figure 15 is a similar view to Figure 1 but showing an aircrew ensemble with detachable bladders ,

[0068] Figure 16A is a schematic view of a detachable chest bladder for the ensemble of Figure 15 ,

[0069] Figure 16B is a schematic view of a detachable leg bladder for the ensemble of Figure 15 ,

[0070] Figure 16C is a section on the line X-X of Figure 16A and showing the bladder of Figure 16A mounted on a jacket of the ensemble of Figure 15 ,

[0071] Figure 16D is a section on the line Y-Y of Figure 16B and showing the bladder of Figure 16B mounted on a lower G garment of the ensemble of Figure 15 ,

[0072] Figure 17 is a schematic side elevation of an aircrew in an ej ector seat of an aircraft an wearing an ensemble for countering G forces of any on the kinds shown in Figures 1 to 16D and showing the flow of body fluids under Gzforces ,Figure 18 is a section on the line X-X of Figure 17 showing schematically blood vessels of the aircrew of Figure 17 in an undistended position,

[0073] Figure 19 is a similar view to Figure 18 but showing the blood vessels in a distended position as a result of Gzforces , Figure 20 is a similar view to Figure 19 and showing the effect of a full cover lower G garment,

[0074] Figure 21 is a schematic section through part of a lower leg and ankle carrying an inflatable lower G assembly with inflation proceeding towards the ankle,

[0075] Figure 22 is a similar view to Figure 21 but showing inflation starting from the ankle,

[0076] Figure 23 is a similar view to Figure 22 but showing the progression of inflation from the ankle and the use of an inlet at the ankle,

[0077] Figure 24 is a similar view to Figure 23 and showing the further progression of inflation from the ankle,

[0078] Figure 25 is a similar view to Figures 21 and 22 but showing the application of a residual pressure to the leg,

[0079] Figure 26 is a schematic front elevation of an aircrew ensemble including a lower G bladder assembly providing the ankle inflation and residual pressure of Figures 22 , 23 and 24 and showing a first form of gas supply,

[0080] Figure 27A is a similar view to Figure 26 but showing a second form of gas supply,

[0081] Figure 27B is a section on the line X-X of Figure 27A, and Figure 28 shows an example arrangement of holes in a bladder to provide air-permeability,

[0082] Figure 29 is a cross-section of an inflatable bladder, Figures 30 to 35 are partial views at points around the circumference of the inflatable bladder of Figure 29 - e . g . at points A, B or C - showing different forms of pieces of material that may be used to form the inflatable bladder, and Figures 36, 37 and 38 are partial views at points around the circumference of the inflatable bladder showing how two pieces of material and may be sealed at their seams in various different ways .In the figures, like elements are generally designated the same reference signs .

[0083] DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0084]

[0051] An anti-G suit is often worn by pilots and crew of high speed aircraft that subject them to a G force when turning, the effect of which is to drive the blood supply of the body towards the lower abdomen and legs resulting in a reduced supply of oxygenated blood to the brain which can lead to loss of consciousness (G LOG) and potentially the loss of the crew and aircraft . To counteract this effect pilots and crew wear an anti-G suit which consists of a close-fitting suit which is adjusted to fit the wearer and has inflatable bladders within it that when inflated apply a counter pressure to the lower abdomen and legs . This counter pressure reduces the blood volume by effectively compressing the lower abdomen and legs .

[0085]

[0052] Referring first to Figure 1, the aircrew ensemble includes a flight suit that comprises an upper suit portion 20 and lower suit portion 21. The upper suit portion 20 and the lower suit portion 21 are typically made from a fire-retardant textile which is stitched together, and are preferably made from an inherently fireproof fabric such as NOMEX®. The upper suit portion 20 has a torso portion 22 , a waist 23 , a neck opening 24 and left and right arm portions 25a, 25b, respectively. The upper suit portion also has a front opening 26 closed by, for example, a zipper 27. The lower suit portion 21 has a waist 28 and left and right leg portions 29a, 29b . The suit is completed by gloves 30 and boots 31.

[0086]

[0053] The upper portion 20 and the lower portion 21 may be formed in one-piece with a front central longitudinal zip or may be formed as separate parts and connected at the waist .

[0087]

[0054] The upper portion 20 carries a chest counter pressure assembly in the form of a j acket 32 containing a chest counterpressure bladder 33 . Referring next to Figure 2 , the j acket 32 is formed of inner and outer layers 34 , 35 of gas ( e . g . air ) permeable material that hold the bladder 33 between them located on the chest of a wearer . The inner layer 34 and / or the outer layer 35 of the j acket 32 may be elastically deformable . The inner layer 34 and / or the outer layer 35 of the j acket 32 may be inelastic and / or inextensible . Preferably at least the outer layer 35 of the j acket 32 is inelastic and / or inextensible .

[0088]

[0055] As seen in Figure 2 , the outer layer 35 is formed by front and rear portions 35a, 35b that are interconnected by two rows of side lacing 38a , 38b located at respective opposite sides of the outer layer 35 to allow the circumferential length of the j acket 32 to be adj usted to the correct fit for a wearer, although such adj ustment can be performed in other ways . This adj ustment is important for reasons that will become apparent below . The bladder 33 may, optionally, be formed of an air-permeable material that allows gas ( e . g . air ) to pass through the material . The entire surface of the bladder 33 may be gas ( e . g . air ) permeable , or only part of the surface of the bladder 33 may be gas ( e . g . air ) permeable . The bladder 33 may be entirely gas ( e . g . air ) impermeable .

[0089]

[0056] The bladder 33 has an inlet 39 for connection to an inflation hose 100 that , in turn, is connected to an inflation system 101 for supplying gas ( e . g . air ) under pressure to the bladder 33 , in a manner to be described below . The inflation system 101 may be part of a breathing system 103 for the wearer . Both the inflation system 101 and the breathing system 103 may be part of the aircraft' s pressurisation system 105 .

[0090]

[0057] Referring once again to Figure 1 , and also to Figure 3 , the lower portion 21 carries a lower G assembly 40 assembly a lower G bladder 41 . The lower G assembly 40 is formed by inner and outer layers 42 , 43 of air-permeable material that hold the lower bladder 41 between them and located around the legs of a wearer ( one of which is shown in Figure 3 ) and over the abdomenof the wearer . The inner layer 42 and / or the outer layer 43 of lower G assembly 40 may be elastically deformable . The inner layer 42 and / or the outer layer 43 of lower G assembly 40 may be inelastic and / or inextensible . Preferably at least the outer layer 43 of lower G assembly 40 is inelastic and / or inextensible .

[0091]

[0058] As seen in Figure 3, the outer layer 43 is formed with a side opening whose edges are interconnected by a row of side lacing 44 located to allow the circumferential length of the lower G assembly 40 outer layer 43 to be adjusted to the correct fit for a wearer, although such adjustment can be performed in other ways . This adjustment is important for reasons that will become apparent below. The bladder 41 may, optionally, be formed of air-permeable material that allows gas (e . g . air) to pass through the material . The entire surface of the bladder 41 may be gas (e . g . air) permeable, or only part of the surface of the bladder 41 may be gas (e . g . air) permeable . The bladder 41 may be entirely gas (e . g . air) impermeable .

[0092]

[0059] The bladder 41 has an inlet 45 for connection to an inflation hose 90 that, in turn, is connected to an inflation system 91 for supplying gas (e . g . air) under pressure to the bladder 41, in a manner to be described below. The inflation system 91 may be part of the breathing system 103 for the wearer .

[0093]

[0060] The lower G bladder 41 has also an outlet 46 at each ankle connected to respective bladders not shown) in respective boots 31.

[0094]

[0061] In use, an aircrew member such as a pilot dons the suit with the j acket 32 and lower G garment 40. The lacings 38a, 38b and 44 are tightened to ensure that the jacket 32 and the garment 40 are a close fit around the torso and the lower body portion respectively of the wearer so that, when inflated, the bladders 33, 41 apply a required restriction (see below) .

[0062] The inlet 39 to the chest bladder 33 is connected via a G valve 107 to the inflation system 101 , as described above , which may also be part of the aircraft breathing circuit 103 . The inlet 45 to the lower G bladder 41 is connected via a G valve 109 to the inflation system 91 . Whilst in flight , the chest bladder 33 and the lower G bladder 41 are pressurised and depressurised through the aircraft' s pressurisation system 105 and the G valves 107 , 109 . This happens as the aircraft experiences high G and the valves 107 , 109 open and close at pre-determined values of G .

[0095]

[0063] The inlet 39 to the chest bladder 33 and the inlet 45 to the lower G bladder 41 may alternatively both be connected to a single G valve and a single inflation system .

[0096]

[0064] As mentioned above , the gas ( e . g . air ) holding bladders 33 , 41 that are incorporated into an aircrew protective ensemble , for applying counter pressure when gas filled under high G acceleration . Optionally, the gas ( e . g . air ) holding bladders 33 , 41 may be made to be gas ( e . g . air ) -permeable . The passage of gas ( e . g . air ) through the gas ( e . g . air ) -permeable bladders 33 , 41 advantageously assists in the cooling of the wearer as this will increase evaporative cooling from the surface of the wearer' s body .

[0097]

[0065] The bladders 33 , 41 may be made from a material that is porous to gas ( e . g . air ) when gas ( e . g . air ) is passed into them from a pressurised gas ( e . g . air ) supply source or may be a non-permeable material made porous ( or gas ( e . g . air ) -permeable ) by being punctured to form holes over its surface ( e . g . "needled" ) . The extent of the porosity ( or permeability) of the material is selected so that the gas ( e . g . air ) flow out of the bladders 33 , 41 cannot be so excessive as to substantially reduce the effectiveness of the ability to of the bladders 33 , 41 to apply pressure to the wearer' s body when under high G .

[0066] Gas / air-permeable regions of the bladders 31 , 41 may, for example , have 3mm diameter holes formed at 100mm intervals along parallel rows . Adj acent rows may be spaced apart at 50mm intervals . The holes along adj acent rows may be staggered so that a hole in a first row is equidistant from the two nearest holes of a second, adj acent row . The holes along alternate rows are aligned along axes perpendicular to the rows , the distance between adj acent holes along such an axis being 100mm. An example hole arrangement is shown in Figure 28 .

[0098]

[0067] A typical gas ( e . g . air ) flow rate of about 580 litres a minute may maintain a constant flow rate through the gas ( e . g . air ) permeable bladder to maintain a 0 . 5psi ( 3447Pa ) internal pressure for cooling purposes . A higher internal pressure may be required when G protection is needed for the wearer . For example , a maximum bladder pressure needed at the maximum 9G ( e . g . 9Gz , gravitational force that is applied to the vertical axis of the body) may be llpsi ( 75 . 84 kPa ) . A lower bladder pressure may be sufficient at lower G forces ; for example at 5G ( or 5Gz ) a bladder pressure of 4psi ( 27 . 57 kPa ) may be used .

[0099]

[0068] The bladders 33 , 41 may be made from material that is moisture vapour permeable ( as described in WO-A-2012 / 041971 ) . The bladders 33 , 41 may be made from material that is both moisture vapour permeable ( as described in WO-A-2012 / 041971 ) as well as air permeable . Such moisture vapour permeable materials are available from GORE-TEX .

[0100]

[0069] Respective regions of the bladders 33 , 41 may have different levels of air-permeability . For example , regions of the bladders 33 , 41 that cover larger muscles , such as thighs and calves , may have a greater air-permeability than other areas . Regions of the bladders 33 , 41 that cover parts of the wearer' s body that require maximum G protection, such as the abdomen, may have a lower air-permeability than other areas ( such as the larger muscles ) . Regions of the bladders 33 , 41 that cover parts of the wearer' s body that require maximum Gprotection may not be air-permeable at all . The different airpermeabilities may be provided by varying the size and / or positioning of holes in the bladder material - e . g . with no holes at the abdomen area and a higher density of holes at the larger muscle areas than other areas .

[0101]

[0070] The bladders 33 , 41 are preferably inelastic ( formed from inelastic material ) , although in some embodiments the bladders 33 , 41 may be elastic ( e . g . formed from elastically deformable material ) .

[0102]

[0071] When in an aircraft is experiencing high G, the bladders 33 , 41 are pressurised by the pressurisation system 105 which includes a pressurised supply of gas ( e . g . air ) on board the aircraft . This pressurised supply of gas ( e . g . air ) from the pressurisation system 105 is almost in practice unlimited in flow rate / volume . The pressurised supply of gas ( e . g . air ) can be therefore used to increase evaporative cooling in addition to the conventional purpose of providing high G protection .

[0103]

[0072] The flow and volume of gas ( e . g . air ) from the pressurisation system 105 is configured to be sufficient that it still allows the bladders 33 , 41 to be highly effective at protecting aircrew when under high G conditions , even though, optionally, a relatively small amount of gas ( e . g . air ) is "leaking" out of the bladders 33 , 41 due to their gas ( e . g . air ) permeability .

[0104]

[0073] The pressurisation system 105 may also be modified to create a back pressure and controlled flow of gas ( e . g . air ) into the bladders 33 , 41 when not under high G . As mentioned above , the supply of gas ( e . g . air ) into the bladders 33 , 41 is controlled by a G valves 107 , 109 such that , as high G is experienced the valves 107 , 109 open to fully inflate the bladder 33 , 41 to provide high G protection . The valves 107 , 109 may be modified to allow a gas ( e . g . air ) flow into the bladders 33 , 41 when not under high G to provide cooling of the wearer evenunder lower G conditions when the bladders 33 , 41 are partially ( not fully) inflated . This creation of an airflow into the bladders 33 , 41 when not under high G has a further benefit as the bladders 33 , 41 are always filled with gas ( e . g . air ) ( albeit to a low pressure ) such that , on experiencing high G, the time taken to fully inflate the bladders is reduced . This is advantageous as this results in the bladders filling quicker with gas ( e . g . air ) to quickly provide counter pressure earlier thus preventing "pooling" occurring in the lower limbs . Generally, the rate at which gas ( e . g . air ) passes through the air-permeable material of the bladders 33 , 41 will be lower when the gas ( e . g . air ) pressure in the bladders 33 , 41 is lower . Greater cooling is generally required at high G (when the bladders 33 , 41 are fully inflated at high pressure ) due for example to the stresses to which aircrew are subj ected at high G - and therefore a relatively lover cooling effect at lower bladder pressures may be considered appropriate and advantageous .

[0105]

[0074] Figure 4A shows a partial cross-sectional view through a portion of the upper 20 / lower 21 portion of the flight suit . As indicated by arrows "A" gas ( e . g . air ) within the bladder 33 , 41 passes through the outer and inner surfaces of the bladder due to the gas ( e . g . air ) permeability of the outer and inner surfaces of the bladder 33 , 41 . Arrow "B" shows movement of gas ( e . g . air ) within the bladder 33 , 41 between the outer and inner surfaces of the bladder 33 , 41 . Arrow "C" shows movement of gas ( e . g . air ) through the inner surface of the bladder 33 , 41 , the inner surface 34 of the j acket 32 / the inner surface 42 of the lower G assembly 40 . Arrow "D" shows movement of gas ( e . g . air ) through the outer surface of the bladder 33 , 41 , the outer surface 35 of the j acket 32 / the outer surface 43 of the lower G assembly 40 . Only one of the outer and inner surfaces of the bladder 33 , 41 may be gas ( e . g . air ) permeable .

[0106]

[0075] Figure 4B shows a partial cross-sectional view through a portion of the upper 20 / lower 21 portion of the flight suit thatincludes optional formations 47 on the outer and inner surfaces of the bladder 33 , 41 , inside the bladder volume , which provide channels 48 for gas ( e . g . air ) to pass along within the bladder 33 , 41 . When the bladder 33 , 41 are not fully inflated the outer and inner surfaces of the bladder may be compressed together by the tightening of the outer layers 35 , 43 of the G garment , and the formations 47 assist the passage of gas ( e . g . air ) in this situation . The formations 47 may be square or rectangular in cross-section . The formations 47 may have a length of 2 -3 mm and / or a width of 2-3 mm (measured parallel to the surface of the bladder 33 , 41 ) . The formations 47 may be formed of substantially incompressible ( e . g . closed cell ) foam. The formations 47 may be formed of rigid material , such as plastics . The use of formations 47 in the lower 21 portion of the flight suit may be particularly advantageous to improve the passage of gas ( e . g . air ) to prevent "pooling" occurring in the lower limbs . For example , a row of six formations 47 may be provided spaced apart along a line between the bladder 41 inlet 45 and outlet 46 .

[0107]

[0076] Optionally, a portable gas ( e . g . air ) pump 120 may be provided which may be carried by the aircrew member . The portable gas ( e . g . air ) pump 120 may be battery powered . The portable gas ( e . g . air ) pump 120 may be connected to the inlets 39 , 45 to provide an gas ( e . g . air ) flow into the bladders 33 , 41 when not under high G to provide cooling of the wearer even under lower G conditions when the bladders 33 , 41 are not fully inflated such that when out of the aircraft the aircrew member can have the benefit of evaporative cooling caused by gas ( e . g . air ) passing through the gas ( e . g . air ) -permeable bladder material . This is advantageous as it addresses the challenge of keeping pilots cool when "standing by" for example on the deck of an aircraft carrier in the Gulf or other hot climate .

[0108]

[0077] The upper 20 portion of the flight suit is sometimes not worn and in this case a bladder type garment / vest may be provided that is made from similar air-permeable materials to the lowerG garment 21 and used as an upper body cooling garment . This may be done by using the low-pressure cooling gas (e . g . air) supply that is used to provide cooling to the lower body G garment 21 , which is controlled by a valve which controls the pressure to ensure the pressure in the upper portion 20 is sufficient to provide cooling by the passage of gas (e . g . air) through the bladder but which pressure remains relatively low compared with the pressure applied provide G protection .

[0109]

[0078] Referring next to Figure 5 , an alternative form of the lower G bladder has the lower G bladder 49 in the form of a partial cover bladder . Parts common to Figures 1 to 4 and to Figure 5 are given the same reference numerals and will not be described in detail .

[0110]

[0079] The partial cover lower G bladder 49 is formed by a first bladder portion 49a that extends across the front abdomen of a wearer and then down the front of the thighs of the wearer to just above the knee . Second and third bladder portions 49b, 49c extend over respective left and right shins of the wearer . These bladder portions 49a, 49b and 49c are interconnected and connected to a source of pressurised gas (e . g . air) as described above in relation to Figures 1 to 4 . The bladder portions 49a, 49b and 49c are air-permeable to allow cooling of the wearer in the manner described above .

[0111]

[0080] Referring next to Figure 6, the shin bladders 49b, 49c extend only around the front of the leg 50 of the wearer . When the bladders 49b, 49c are inflated, the diameter of the outer layer 43 increases and so draws the non-elastic outer layer 43 against the rear of the leg 50 of the wearer . This , together with the pressure applied by the bladder 43b, 43c to the front of the leg, provides the constriction necessary to counter G forces .

[0112]

[0081] In the embodiments of Figures 1 to 4 , the bladder 41 is sized to extend exactly around the associated body part . Thisneed not be the case . If the material of the bladder 41 is inelastic, the bladder 41 may be sized so that when uninflated the bladder 41 is of greater diameter than the body part it encircles ( see Figure 7A) . Thus , when inflated, the bladder 41 is not subj ect to hoop stress ( see Figure 7B) and the tension is taken up by the seams of the outer layer 43 and not by the seams 41a of the bladder 41, which are weaker than the seams of the outer layer 43.

[0113]

[0082] Alternatively, if the bladder 41 is made from an elastic material, it can be sized so that, when uninflated, it is of lesser diameter than the limb 50 it encircles so as to reduce the bulk of the garment (see Figure 8A) . When inflated (see Figure 8B) , the circumferential length increases to surround the 1 imb 50 .

[0114]

[0083] The inflatable bladders in a G suit should preferably meet certain very demanding characteristics . The bladders are conventionally made from TPU. The bladders may be inflated and deflated thousands of times and this weakens the bladder . The pressures that the bladders experience are four or five times greater than other inflatables . The bladders are subj ected to frequent washing as they are part of a worn garment, and this weakens the bladder over time . Additionally, the bladders within the G suit may need to withstand fire and flame exposure for example if ej ecting through a "fireball" . The suit must preferably also be capable of being stored or effectively functioning in a range of extreme temperatures from -40°C to +60°C, which requires exceptional performance from the TPU bladders .

[0115]

[0084] According to an embodiment of the invention, any of the bladders described herein may include at least one sheet of flexible material that includes graphene, of the type / composition as discussed above . The sheet of flexible material may also include a flexible polymer such as PU and / or TPU, as discussed above .

[0085] Conventional bladders made from TPU without graphene reinforcement may fail earlier in their lifetime than those with a graphene-including sheet and will not be flame retardant .

[0116]

[0086] Bladders with a graphene-including sheet may be thinner, lighter and more flexible than conventional bladders while providing the same or better performance . As the bladders form part of the pilot' s worn suit, the lighter and more flexible the bladders with a graphene-including sheet will lead to a more comfortable and less obstructive garment which is helpful to achieve good pilot performance both in the air and on the ground . The thinner and lighter bladders with a graphene-including sheet will benefit this performance .

[0117]

[0087] The bladders with a graphene-including sheet material can be made to be Moisture Vapour Permeable (MVP) which will further benefit the pilot by reducing thermal burden .

[0118]

[0088] The bladders with a graphene-including sheet material can be made to be gas / air permeable in the manner described above .

[0119]

[0089] According to an embodiment of the invention, the inner layer 34 and / or the outer layer 35 of the jacket 32 may be at least one sheet of flexible woven material that includes graphene, of the type / composition as discussed above . The sheet of flexible woven material may also include a flexible polymer such as PU and / or TPU, as discussed above .

[0120]

[0090] Conventional j ackets made without graphene reinforcement may fail earlier in their lifetime than those with a grapheneincluding woven sheet and will not be as flame retardant .

[0121]

[0091] According to an embodiment of the invention, the inner layer 42 and / or the outer layer 43 of lower G assembly 40 may be at least one sheet of flexible woven material that includes graphene, of the type / composition as discussed above . The sheet of flexible woven material may also include a flexible polymer such as PU and / or TPU, as discussed above .

[0092] The principles described above with reference to Figures 7A, 7B and 8A, 8B are not limited to bladders such as the lower G bladders 33, 41 that, when inflated, extend all around a body part . The same principle could be applied to other bladders , such as the chest compression bladder 33, by containing the bladder in a pocket formed in the associated garment . Where the bladder is of inelastic material (such as in Figures 7A, 7B) , the pocket is smaller than the uninflated bladder so that, when inflated, the inflated bladder is confined by the pocket and tension is taken by the material of the garment . If the bladder is of elastic material ( Figures 8A, 8B) then the pocket is larger then the uninflated bladder, with the bladder, on inflation, expanding to fill the pocket .

[0122]

[0093] There are a number of ways of designing a bladder 33, 41 to reduce further the thermal burden. These can be used with or without the permeable materials previously described.

[0123]

[0094] Referring next to Figure 9, parts common to Figures 1 to 8 and to Figure 9 are given the same reference numerals and will not be described in detail . In this embodiment, the chest bladder 33 and the lower G bladder 41 , which may advantageously include graphene, are provided with elongate slots 51 to form "grill" bladders 33 , 41 - seen schematically in Figure 10. Alternatively, as seen schematically in Figure 11, the bladders 33, 41 can be formed as a series of inter-connected bladder tubes 52 ("fingers") connected by a manifold such that there are spaces formed by bladder slots 51 between the fingers 52 . The slots 51 allow air movement through the slots 51 when the bladder 33, 41 is deflated and therefore evaporative cooling of sweat is assisted when uninflated. This is shown in more detail in Figure 12 for the chest bladder 33 where it will be seen that, when the bladder 33 is uninflated, evaporative cooling can take place through the slots 51. The "grill" bladders 33 , 41 and bladder tubes 52 ("fingers") are formed of air-permeable material to provide cooling .

[0095] However, when inflated, the bladder 33 , 41 expands laterally and outwardly to provide the continuous counterpressure needed (seen in broken line in Figure 12 for the chest bladder 33 and in Figures 13A (uninflated) and 13B (inflated) for the lower G bladder 41 ) .

[0124]

[0096] In these embodiments, therefore, the bladder 33, 41 has an uninflated area and is formed, inwardly of the periphery of that area, with one or more open gaps that allow air movement through the gap or gaps to increase evaporative cooling . The or each gap closes or substantially closes on inflation of the bladder 33, 41.

[0125]

[0097] Referring next to Figure 14A to 14E, the grill or finger bladders 33 , 41 can be made with an outer layer 53 of non-stretch material and an inner layer 54 of elastic material . When such a bladder 33, 41 is inflated, the outer layer 53 will bulge (because it is non-stretch) and so reduce the circumferential length of the bladder 33, 41. The inner layer 54 will stretch (rather than bulge ) and so apply even pressure to the flesh (see Figures 14B and 14D) . This helps to reduce a problem of traditional G bladders made wholly of non-stretch materials that, when they are inflated, the cover of the bladder "balloons" both inwardly and outwardly. This "ballooning" causes restriction in the cockpit due to the bulk of the inflatable section increasing and can interfere dangerously with the pilot controls . This effect is greatly reduced in this dual material "finger" or "grill" bladder design . It is only by the inner layer 54 being elastic that the inner / internal space is filled and the pressure surface is then applied evenly to the body part . If this is not applied evenly then this leads to petechial haemorrhaging (see Figure 14E ) where the surface vessels burst under the skin in the areas where uneven pressure produces areas of insufficient pressure to counteract the increased internal pressure in the vessels .

[0098] In the embodiments described above with reference to Figures 1 to 14 , the bladders 33, 41, 49 are all carried between inner and outer layers 34 , 35 and 42, 43 of a jacket 32 or lower G garment 40. In the case of partial cover bladders 49a, 49b and 49c, the bladders 49a, 49b and 49c may be secured by, for example, stitching to the outer layer 43 , although this is not necessary.

[0126]

[0099] Referring next to Figures 15 and 16A, 16B, 16C and 16D, parts common to these Figures and to Figures 1 to 14 are given the same reference numerals and will not be described in detail . In this embodiment, the jacket 32 and the lower G garment 40 are formed from a single layer of air-permeable material, which may advantageously include graphene . The chest bladder is formed by a single front air-permeable bladder 56 that is attached to the jacket 32 by releasable fastenings 57 such as press studs or touch close fasteners or zippers or other mechanical means ( see Figure 16B) . Similarly, the lower G air-permeable bladder 41 is attached to the lower G air-permeable garment 40 by releasable fastenings 57 such as press studs or touch close fasteners or zippers or other mechanical means (see Figure 16B) .

[0127]

[0100] As seen in Figures 16C and 16D, the bladders 56, 41 may be covered with an inner lining 59 that forms a pocket with the associated garment that can be opened at one side 59a to allow insertion of the bladder 56, 41.

[0128]

[0101] If the bladders 33 , 41 of the suit described above with reference to Figures 1 to 14 are damaged or punctured, then the suit becomes non-functional and normally has to be replaced in its entirety or has to be stripped down into component parts and reassembled when the faulty part is replaced. The bladders 33 , 41 may need to be taken apart and then replaced as the suit is being rebuilt . The bladders 33, 41 are particularly vulnerable to damage caused by wear and tear as they are constantly being inflated and deflated and being worn in a suitin which mechanical action inside the cockpit can easily damage the bladders 33, 41.

[0129]

[0102] The arrangement of Figures 15 and 16A, 16B, 16C, 16D, in which the bladders 56, 41 are of modular design such that they can be easily replaced or exchanged by hand and without any special tools, reduces substantially the cost of servicing and maintenance of such bladder counter pressure systems . In addition, it allows the ensemble to be worn either with or without bladders 56, 41 so making the ensemble more widely functional .

[0130]

[0103] The feature of removable bladders of Figures 15 and 16 can also be used in conjunction with the bladders 33, 41 of the full cover suit of Figures 1 to 4 .

[0131]

[0104] Any of the bladders described above, including those described in relation to Figures 9 to 16, may include graphene .

[0132]

[0105] Referring next to Figures 17 , 18 , 19 and 20, when an aircrew in an aircraft that experiences high Gzacceleration is subjected to high G forces when in a curved flight, then the body fluids (in particular the blood, more particularly venous blood) are accelerated in the z direction (i . e . from head to toe) (see Figure 17 ) . As the mass of the fluid is increased by the acceleration, so the hydrostatic pressure of the fluid is increased progressively and linearly in the z direction (see also Figure 17 ) . As the walls of human blood vessels 65 are essentially "elastic", then the volume of the vessels 65 is increased in the z direction progressively and linearly i . e . in the lower limbs (see Figures 18 and 19 ) . As a consequence of this, the volume of blood overall is increased in the lower limbs (blood pooling) and decreased in the upper part of the abdomen as the volume of blood in the body is constant . Decreasing the volume of blood in the upper part of the abdomen also leads to a decrease of blood volume in the head. At the same time as the blood is being accelerated in the z direction,the heart, aorta and other large vessels of the abdomen are also displaced in a z direction which adds to a further reduction in the total blood volume in the upper part of the body and therefore in the head. (This is known as the caudal effect . ) As a consequence of reducing the available blood pressure and volume in the brain (and in particular the supply of blood to the eyes ) , a dangerous lowering of the blood oxygen concentration in the brain occurs . This leads first to a loss of colour in the vision and then a loss of peripheral vision (grey out and tunnel vision) . Ultimately G induced loss of consciousness (GLOC) occurs . This clearly has a detrimental effect on the aircraft pilot and ultimately the loss of the aircraft and the death of the aircrew may follow .

[0133]

[0106] To counteract this negative effect of blood pooling in the lower limbs , counter pressure garments to cover the lower limbs have been developed as described above and, for example, with reference to Figures 1 to 16 and in WO 2007 / 111981 and USA-6325754 . As seen in Figure 20 , the effect of such a garment 66 is to restrict the leg blood vessels 65 and so force blood back into the upper part of the body.

[0134]

[0107] As well as the use of counter pressure garments , aircrew are trained to carry out physiological manoeuvres (Anti-G Straining Manoeuvres - AGSM) and this is done by tensing the voluntary muscles and pressurising the chest / lungs, the action of both of these being to reduce the effect of G acceleration on the body. This is, however, very tiring and limits the G endurance that can be tolerated and it also limits voice communication and voice command whilst straining under AGSM. The goal of a G protection garment and its development is to limit the amount of pilot effort required by maximising the protection offered by the garment and therefore increasing overall G endurance . Additionally, pilots can also breathe pressurised gas (Positive Pressure Breathing for G, PPBG) such that the thoracic pressure / thoracic blood pressure is increased causing more dissolved oxygen to be carried to the brain .

[0108] One type of counter pressure (anti-G) garments is gas pressurised by inflating gas holding bladders from an aircraft compressor or compressed gas supply and which are restrained around the lower limbs and lower abdomen by covers which apply a counter pressure as described above with reference to Figures 1 to 16 and therefore limit the "blood pooling" in the lower limbs and limit the z displacement of the heart and maj or blood vessels (caudal effect ) (see Figure 20 ) . Referring next to Figure 21, in such a suit, an inflation pressure front 80 travels down the lower G bladder 41, 49, moving in a direction opposite to that of the venous blood to apply the pressure to the leg ( see also Figure 20 ) that limits blood pooling .

[0135]

[0109] Referring next to Figures 22 and 23, the suit described above with reference to any of Figures 1 to 20 may be modified so that the gas (e . g . air) supply applies the gas inf lation / pressurisation to the lower G bladder 41, 49 at the ankles first ("ankle inflation") rather than applying the pressure first at the abdominal level . This benefits the wearer by tending to increase the venous blood return up the lower limbs and thereby increasing the blood volume / pressure in the upper body and head. The pressure point 81 from the applied gas (e . g . air) thus starts at the ankle (see Figure 22 ) and continues up the leg ( see Figure 23 ) in the same direction as the venous blood until the bladder reaches an operating pressure .

[0136]

[0110] In addition, the gas (e . g . air) supply may be modified to apply continuously a residual "gas pressure" to the lower G bladders 41 , 49 and thus constriction to the lower limbs such that blood pooling is continuously reduced in the lower limbs . (This is termed "start-pressure" and is less than the operating pressure . ) This is shown in Figures 24. This benefits the wearer by continuously reducing blood pooling and overcomes the "lag" phase in the G garment inflation system. This may be supplied automatically or may be controlled by the wearer utilizing a squeezable bulb 73 (see Figure 25 ) .

[0111] Referring next to Figure 26, the gas (e . g . air) supply to the ankles may be through two external hoses 60a and 60b connected by a single hose 61 to the gas (e . g . air) supply. Each hose 60a, 60b runs along a respective leg of the lower G garment 41 to a respective inlet 62a, 62b at an associated ankle . Alternatively, as seen in Figures 27A and 27B, the hoses 60a, 60b may run through the interior of the lower G bladder 41 ( see Figure 27B) to the respective inlets 62a, 62b .

[0137]

[0112] Although the bladders above are described as air-permeable, it should be appreciated that the bladders may be gas-permeable - and not specifically permeable by air . The bladders may be permeable by any gas that is used to inflate the bladders - allowing a portion of the inflating gas to permeate through the bladder walls . Air is a convenient gas to use, as it is often stored onboard an aircraft to help aircrew breathe; however, other gases can be used to inflate the bladders .

[0138]

[0113] Conventional anti G ensembles made without graphene reinforcement may fail earlier in their lifetime than those with a graphene-including woven sheet and will not be as flame retardant .

[0139]

[0114] Garment layers with a woven graphene-including sheet may be thinner, lighter and more flexible than conventional garment layers while providing the same or better performance . As the garment layers form part of the pilot' s worn suit, the lighter and more flexible the garment layers with a grapheneincluding sheet will lead to a more comfortable and less obstructive garment which is helpful to achieve good pilot performance both in the air and on the ground.

[0140]

[0115] Although embodiments have been described in relation to an anti-G suit as shown in Figs . 1 to 27 , it should be appreciated that least one sheet of flexible material that includes graphene may be advantageously incorporated into many other forms of anti-G suit .

[0116] Discussed above is an aircrew ensemble that has at least one sheet of flexible material that includes graphene . The at least one sheet of flexible material that includes graphene may be included in one of more of an inflatable bladder, the inner layer of the garment in which the bladder is contained, and the outer layer of the garment in which the bladder is contained. The sheet of flexible material may also include a flexible polymer - such as polyurethane, PU, and / or thermoplastic polyurethane, TPU.

[0141]

[0117] The sheet of flexible material may be formed by dispersing graphene in the form of Graphene Nano Platelets (GNPs ) into PU / TPU at the melt stage . The sheet of material may have a thickness of between 100 and 150pm. The sheet of material may include between 1 and 10% graphene by weight, preferably 1.5% graphene by weight .

[0142]

[0118] The sheet of material may be formed from fibres , threads or yarn that contains graphene . The fibres, threads or yarn may be woven together to form the sheet of material . The fibres, threads or yarn may also include polyurethane, PU, and / or thermoplastic polyurethane, TPU . Graphene may be dispersed into PU / TPU at the melt stage in the form of GNPs to from the fibres , threads or yarn .

[0143]

[0119] Embodiments of the invention may provide an aircrew ensemble using flexible polymer films (e . g . PU or TPU) incorporating graphene to create waterproof and / or air-holding materials . Such incorporation of graphene into the PU / TPU film may increase its strength and flame retardancy, and may contribute to the overall performance of the aircrew ensemble .

[0144]

[0120] The graphene-including sheet of material may be fluid impermeable . The graphene-including sheet of material may be gas impermeable . This allows the sheet of material to form a pressure-holding inflatable item and / or to form a waterproof garment / item.

[0121] Pressure-holding inflatable items are often referred to as "bladders" . Inflatable bladders can be inflated orally by mouth or from a compressed gas source such as a cylinder of compressed CO2 .

[0145]

[0122] Embodiments of the invention may provide aircrew ensembles using one of more sheets of material . The sheet of material may be formed from fibres, threads or yarn that contains graphene . The fibres , threads or yarn may be woven together to form the sheet of material . The fibres, threads or yarn may include PU or TPU, and incorporate graphene . Such incorporation of graphene into the fibres, threads or yarn of the sheet of material may increase the strength of the sheet and flame retardancy, and contributes to the overall performance of the equipment .

[0146]

[0123] A graphene-including flexible sheet of material may be incorporated into a bladder for an anti G garment in a number of ways . By way of example, an inflatable bladder 100 is shown in Figure 29. The inflatable lifesaving bladder 100 comprises two pieces of flexible material 112A and 112B . The pieces of flexible material 112A and 112B are connected to each other along opposite sides by a first seam 114A and a second seam 114B . The pieces of flexible material 112A and 112B form an internal volume 116. The inflatable bladder 100 may be inflated, for example, by a gas inflation system 118 or by an oral inflation device 120. The inflatable bladder 100 may be circular in cross-section but may also have other cross-sectional shapes , such as elliptical .

[0147]

[0124] Figures 30 to 35 show different ways in which a graphene-including flexible sheet of material may be incorporated into the inflatable bladder 100. Figures 30 to 35 are partial views at any point around the circumference of the inflatable bladder 100 of Fig . 29 - e . g . at points A, B or C .

[0148]

[0125] In Figure 30 each of the two pieces of flexible material 112A and 112B may be formed by a graphene-includingflexible sheet of material 122 that is coated or laminated onto an inner face 124 of a supporting substrate 126 such as a woven textile (e . g . coated or laminated onto the entire inner face 124 of the supporting substrate 126) . The flexible sheet of material 122 creates a barrier to gas when the internal volume 116 is filled and pressurised with gas . The outer textile supporting substrate 126 provides strength, abrasion resistance and limits the elasticity of the bladder 100 to create a dimensionally stable structure .

[0149]

[0126] The supporting substrate 126 may be a non-graphene sheet of material ( i . e . a sheet of material that does not contain graphene ) .

[0150]

[0127] The supporting substrate 126 of Figure 30 may be a graphene-containing sheet of material . The supporting substrate 26 may be formed by weaving together fibres , threads or yarn that contain graphene . In an arrangement where the supporting substrate 26 of Figure 30 is a graphene-containing sheet of material, the flexible sheet of material 22 may be formed by a graphene-including flexible sheet or may be formed by a non-graphene sheet ( i . e . a sheet of material that does not contain graphene) .

[0151]

[0128] In Figure 31 each of the two pieces of flexible material 112A and 112B may be formed by a graphene-including flexible sheet of material 22 that is coated or laminated onto an outer face 128 of an inner supporting substrate 126A, such as a woven textile (e . g . coated or laminated onto the entire outer face 128 of the inner supporting substrate 126A) . The flexible sheet of material 122 creates a barrier to gas when the bladder 100 is filled and pressurised with gas . The inner supporting substrate 126A provides strength and limits the elasticity of the bladder 100 to create a dimensionally stable structure . The inner supporting substrate 126A may be a non-graphene sheet of material ( i . e . a sheet of material that does not contain graphene) . The flexible sheet of material 122 may protect the inner supporting substrate 126A from damage . Theflexible sheet of material 122 may provide an outer surface onto which other items formed of PU / TPU may be readily attached -e . g . by high-frequency welding .

[0152]

[0129] The inner supporting substrate 126A of Figure 31 may be a graphene-containing sheet of material . The inner supporting substrate 126A may be formed by weaving together fibres, threads or yarn that contain graphene . In an arrangement where the inner supporting substrate 126A of Figure 31 is a graphene-containing sheet of material, the flexible sheet of material 122 may be formed by a graphene-including flexible sheet or may be formed by a non-graphene sheet (i . e . a sheet of material that does not contain graphene) .

[0153]

[0130] In Figure 32 each of the two pieces of flexible material 112A and 112B may be formed by a graphene-including flexible sheet of material 122 that is coated or laminated onto an inner face 124 of an outer supporting substrate 126B (such as a woven textile) and coated or laminated onto an outer face 128 of an inner supporting substrate 126A (such as a woven textile ) . For example, the flexible sheet of material 122 is coated or laminated onto the entire inner face 124 of an outer supporting substrate 126B and coated or laminated onto the entire outer face 28 of an inner supporting substrate 126A. The flexible sheet of material 122 is sandwiched between an inner and outer supporting substrates 126A, 126B . The flexible sheet of material 122 creates a barrier to gas when the internal volume 116 is filled and pressurised with gas . The inner supporting substrate 26A provides strength and limits the elasticity of the internal volume 116 to create a dimensionally stable structure . The outer supporting substrate 26B provides strength, abrasion resistance and limits the elasticity of the bladder 16 to create a dimensionally stable structure . The inner supporting substrate 126A and / or the outer supporting substrate 126B may be a non-graphene sheet of material ( i . e . a sheet of material that does not contain graphene) .

[0131] The inner supporting substrate 126A of Figure 32 may be a graphene-containing sheet of material . The inner supporting substrate 126A may be formed by weaving together fibres, threads or yarn that contain graphene . Alternatively, or additionally, outer supporting substrate 126B of Figure 32 may be a graphenecontaining sheet of material . The outer supporting substrate 126B A may be formed by weaving together fibres , threads or yarn that contain graphene . In an arrangement where the inner supporting substrate 126A and / or the outer supporting substrate 126B of Figure 32 is a graphene-containing sheet of material, the flexible sheet of material 122 may be formed by a grapheneincluding flexible sheet or may be formed by a non-graphene sheet (i . e . a sheet of material that does not contain graphene) .

[0154]

[0132] In Figure 33 each of the two pieces of flexible material 112A and 112B may be formed by an inner grapheneincluding flexible sheet of material 122 and an outer sheet 130 such as a woven textile (similar to the supporting substrate 26 of Figure 30 ) . However, in this embodiment, the flexible sheet of material 122 is not attached to outer sheet 130 but is unsupported. The flexible sheet of material 122 may be within but completely separate from the outer sheet 130. The flexible sheet of material 122 may be connected to the outer sheet 130 at one or more points which form a minority of the surface area of the outer sheet 130. The outer sheet 130 forms a non-elastic outer "restrainer" which has smaller dimensions than the potential dimensions of the chamber formed by the flexible sheet of material 122 when expanded . The non-elastic outer "restrainer" retains its dimensional stability so that it does not expand when the chamber formed by the graphene-including flexible sheet of material 122 is inflated. Such an arrangement may be used, for example, as part of a lifejacket or small liferaft that need to be very compact when deflated and packed. The outer sheet 30 may be a non-graphene sheet of material (i . e . a sheet of material that does not contain graphene) .

[0133] The outer sheet 130 of Figure 33 may be a graphenecontaining sheet of material . The outer sheet 130 may be formed by weaving together fibres, threads or yarn that contain graphene . In an arrangement where the outer sheet 130 of Figure 33 is a graphene-containing sheet of material, the flexible sheet of material 122 may be formed by a graphene-including flexible sheet or may be formed by a non-graphene sheet (i . e . a sheet of material that does not contain graphene) .

[0155]

[0134] In Figure 33 the chamber formed by the flexible sheet of material 122 may be made to be oversize or made from a material that can stretch and so that any join in the chamber (e . g . welds or seams between multiple flexible sheets of graphene-containing material ) never comes under tension. Although the chamber may be of generally the same shape as the non-elastic outer "restrainer", the chamber may be of generally larger size . The chamber may be made of a sufficiently large size so that, when inflated within the non-elastic outer "restrainer", the chamber fills the internal volume of the non-elastic outer "restrainer" without any stretching of the chamber occurring, and the tension is taken up by the non-elastic outer "restrainer" . If the chamber is made oversized, the chamber may be made of an inextensible and / or inelastic material . It is advantageous for the tension to be taken up by the non-elastic outer "restrainer", as it may generally be stronger than the chamber .

[0156]

[0135] In Figure 34 each of the two pieces of flexible material 112A and 112B is formed by a graphene-including flexible sheet of material 122. In this embodiment grapheneincluding flexible sheet of material 122 is not supported in any way and forms a single layer pressurised bladder (no sheet such as a woven textile or the like is provided) . The grapheneincluding flexible sheet of material 122 may provide an outer surface onto which other items formed of PU / TPU may be readily attached - e . g . by high-frequency welding .

[0136] In Figure 35 each of the two pieces of flexible material 112A and 112B may be formed by two graphene-including flexible sheets of material 122A and 122B . Inner flexible sheet of material 122A is coated or laminated onto an inner face 124 (e . g . onto the entire inner face 124 ) of a supporting substrate 126 (such as a woven textile) . Outer flexible sheet of material 122B is coated or laminated onto an outer face 128 (e . g . onto the entire outer face 128 ) of the supporting substrate 126. The supporting substrate 126 is "sandwiched" between the inner and outer flexible sheets of material 122A and 122B . The flexible sheets of material 122A and 122B create barriers to gas when the internal volume 116 is filled and pressurised with gas . The supporting substrate 126 provides strength and limits the elasticity of the internal volume 116 to create a dimensionally stable structure . The flexible sheets of material 122A and 122B provide redundancy, so that the gas-tight nature of the bladder may be maintained when one of the flexible sheets of material 122A and 122B is damaged. The supporting substrate 126 may be a non-graphene sheet of material (i . e . a sheet of material that does not contain graphene) . The outer flexible sheet of material 122B may protect the supporting substrate 126 from damage . The outer flexible sheet of material 122B may provide an outer surface onto which other items formed of PU / TPU may be readily attached - e . g . by high-frequency welding .

[0157]

[0137] The supporting substrate 126 of Figure 35 may be a graphene-containing sheet of material . The supporting substrate 126 may be formed by weaving together fibres, threads or yarn that contain graphene . In an arrangement where the supporting substrate 126 of Figure 35 is a graphene-containing sheet of material, the flexible sheets of material 122A and 122B may be formed by a graphene-including flexible sheet or may be formed by a non-graphene sheet (i . e . a sheet of material that does not contain graphene) .

[0158]

[0138] Although in the arrangements described above, each of the two pieces of flexible material 112A and 112B may beformed by a graphene-including flexible sheet of material 122 , it should be understood that only one of the pieces of flexible material 112A and 112B may formed by a graphene-including flexible sheet of material 122 (the other piece of flexible material may be gas-impermeable but not include graphene) .

[0159]

[0139] The graphene-including flexible sheet of material 122 can be made MVP (Moisture Vapour Permeable ) , termed "breathable", if required . For example, the graphene-including flexible sheet of material 122 may have a molecular structure that allows moisture vapour to pass through but that does not allow water to pass through .

[0160]

[0140] Typically, such bladders are formed from a plurality of pieces of flexible material, such as the pieces of material 12A and 12B of the bladder 100 described above . The pieces of material may include (or consist of ) graphene-including flexible sheets of material, such as the graphene-including flexible sheet of material 122 and / or flexible sheet of woven material 126, 126A, 126B of the bladder described above . Edges of one or more pieces of material may be connected together to form a bladder .

[0161]

[0141] Pieces of material 112A and 112B may be sealed at their seams (such as the seams 114A and 114B described above) in various ways . Pieces of material may be sealed at their seams by being glued or welded (e . g . welded together by high frequency welding) . The seams can be "in shear", peel or peel and shear, as shown in Figures 36, 37 and 38 , respectively.

[0162]

[0142] By way of example, Figure 36 shows a partial view of the bladder 100 described above in the region of the seam 114B . The two generally semicircular (in cross-section) pieces of material 112A and 112B are brought together, with edges 1140A and 40B of the pieces of material 112A and 112B extending radially outwardly with respect to the generally circular (in cross-section) main body of the bladder 100 so that they lie adjacent to one another and in parallel . The seam 114B is formedby welding or gluing (or otherwise fixing together) the edges 140A and 140B of the pieces of material 112A and 112B . The weld (or adhesive ) between the edges 140A and 140B of the pieces of material 112A and 112B is designated 142. The seam 114A may be formed in the same way. Such seams as shown in Figure 36 can be referred to as "in peel" .

[0163]

[0143] By way of example, Figure 37 shows a partial view of the bladder 100 described above in the region of the seam 114B . The two generally semicircular (in cross-section) pieces of material 112A and 112B are brought together, with edges 140A and 140B of the pieces of material 112A and 112B overlapping . The upper piece of material 112A has an outer surface 143A and an inner surface 143B . The lower piece of material 112B has an outer surface 145A and an inner surface 145B . The pieces of material 112A and 112B are connected at an edge region 1140A and 140B of each of the pieces of material 112A and 112B so that the distal inner surface of one of the pieces overlaps the distal outer surface of the other one of the pieces . In the arrangement shown the distal outer surface 143A of the upper piece of material 112A is positioned to face the distal portion of the inner surface 145B of the lower piece of material 112B .

[0164]

[0144] The seam 114B is formed by welding or gluing (or otherwise fixing together) the edges 140A and 140B of the pieces of material 112A and 112B . The weld (or adhesive) between the edges 140A and 140B of the pieces of material 112A and 112B is designated 142. The seam 114A may be formed in the same way. Such seams as shown in Figure 37 can be referred to as "in shear" .

[0165]

[0145] By way of example, Figure 38 shows a partial view of the bladder 100 described above in the region of the seam 114B . The two generally semicircular (in cross-section) pieces of material 112A and 112B are brought together, with edges 140A and 1140B of the pieces of material 12A and 112B extending radially inwardly with respect to the generally circular ( in crosssection) main body of the bladder 100 so that they lie adjacentto one another and in parallel . The seam 114B is formed by welding or gluing (or otherwise fixing together) the edges 140A and 140B of the pieces of material 112A and 112B, and by welding or gluing (or otherwise fixing) a strip of material 147 over the outer surface of the bladder 100 in the region where the pieces of material 112A and 112B meet . The weld (or adhesive ) between the edges 140A and 140B of the pieces of material 112A and 112B, and between the strip of material 147 over the outer surface of the bladder 100 in the region where the pieces of material 112A and 112B meet, is designated 142. The seam 114A may be formed in the same way. Such seams as shown in Figure 38 can be referred to as "in peel" and "in shear" .

Claims

1. CLAIMS1. An aircrew ensemble comprising a garment (20, 21 ) for covering at least a part of a body of a wearer, and an inflatable counter-pressure bladder (33 , 41 , 49, 56) , carried by the garment (20, 21 ) , wherein the garment (20, 21 ) and / or the bladder (33, 41, 49, 56, 100 ) includes at least one sheet of flexible material that includes graphene .2 . The aircrew ensemble of claim 1, wherein the graphene included in the sheet of flexible material comprises graphene nano platelets .

3. The aircrew ensemble of claim 1 or 2 , wherein the sheet of material further includes a flexible polymer .4 . The aircrew ensemble of claim 1 , 2 or 3, wherein the sheet of material includes polyurethane, PU .5 . The aircrew ensemble of any one of claims 1 to 4 , wherein the sheet of material includes thermoplastic polyurethane, TPU .

6. The aircrew ensemble of any one of claims 1 to 5 , wherein the sheet of material includes between 1 and 10% graphene by weight, preferably 1.5% graphene by weight .7 . The aircrew ensemble of any one of claims 1 to 6, wherein the sheet of material has a thickness of between 100 and 150pm.8 . The aircrew ensemble of any one of claims 1 to 7 , wherein the sheet of material is fluid impermeable .

9. The aircrew ensemble of any one of claims 1 to 8 , wherein the sheet of material is moisture-vapour permeable .

10. The aircrew ensemble of any one of claims 1 to 9, wherein the sheet of material is formed from fibres, threads or yarn that contains graphene .

11. The aircrew ensemble of claim 10 , wherein the fibres , threads or yarn are woven together to form the sheet of material .12 . The aircrew ensemble of any one of claims 1 to 11 , including first and second sheets of material, one of which is said at least one sheet of flexible material that includes graphene .

13. The aircrew ensemble of claim 12 , wherein the first sheet of material is arranged to support the second sheet of flexible material .14 . The aircrew ensemble according to any one of claims 1 to 13 wherein the inflatable bladder (33 , 41, 49, 56, 100 ) is a chest compression bladder and the garment (20 ) covers the torso of a wearer .15 . The aircrew ensemble according to any one of claims 1 to 13 wherein the inflatable bladder (33 , 41, 49, 56, 100 ) is a lower G bladder and the garment ( 21 ) covers the abdomen and legs of a wearer .

16. The aircrew ensemble according to claim 15 wherein the lower G bladder extends across the abdomen and around the legs of the wearer .17 . The aircrew ensemble according to claim 15 wherein the lower G bladder includes a first portion ( 49a) for extending over the abdomen and thighs of a wearer and second portions ( 49b, 49c) extending over respective shins of a wearer .18 . The aircrew ensemble according to any one of claims 1 to 17 wherein the bladder ( 33 , 41 , 49, 56, 100 ) includes one of the sheets of material that includes graphene and which is elastic so that, when the bladder ( 33 , 41, 49, 56, 100 ) is deflated, the bladder extends only partially over anassociated body part of a wearer to allow evaporative cooling from the uncovered body part, inflation of the bladder ( 33 , 41 , 49, 56, 100 ) causing elastic lengthening of the bladder (33, 41, 49, 56, 100 ) to extend the bladder over the whole area of the associated body part .

19. The aircrew ensemble according to any one of claims 1 to 17 wherein the bladder ( 33 , 41, 49, 56, 100 ) includes one of the sheets of material that includes graphene and which is inelastic, the bladder ( 33 , 41, 49, 56, 100 ) having an area greater than area of the associated body part of the wearer and being confined by the garment (20, 21 ) so that, when inflated, the bladder (33, 41 , 49, 56, 100 ) has the area of the associated body part, so that the material of the bladder (33, 41, 49, 56, 100 ) is untensioned, the tension being taken by the garment ( 20, 21 ) .

20. The aircrew ensemble of any one of claims 1 to 19, wherein the at least one sheet of flexible material that includes graphene is a gas-permeable material allowing the passage of the gas therethrough to cool the body.

21. The aircrew ensemble of claim 20, wherein the bladder includes at least one of the sheets of material that includes graphene and is configured to control the maximum rate of passage of the gas therethrough such that the bladder remains sufficiently inflated to counteract effects of high G-forces during flight .22 . The aircrew ensemble of claim 21, wherein the bladder includes a plurality of formations on an internal surface thereof to facilitate passage of the gas between the formations .

23. The aircrew ensemble of claim 21 or 22 , wherein the bladder ( 33 , 41, 49, 56 ) includes a plurality of regions, each having a different gas-permeability.24 . The aircrew ensemble according to claim any one of claims 1 to 23 wherein the garment ( 20 , 21 ) includes at least one of the sheets of material that includes graphene and which is inextensible , inflation of the bladder ( 33 , 41 , 49 , 56 , 100 ) causing the bladder ( 33 , 41 , 49 , 56 , 100 ) to act against the layer to apply counter-pressure to the wearer' s body .25 . The aircrew ensemble according to claim 24 wherein the garment includes two sheets ( 42 , 43 ) , the inflatable bladder ( 33 , 41 , 49 , 56 ) being located between said two sheets ( 42 , 43 ) , and wherein at least one of the two sheets ( 42 , 43 ) is one of the sheets of material that includes graphene .

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