AU2006100241A4 - An aircraft buoyancy augmentation device - Google Patents

Description

IP Australia 2 9 MAR 2006 1 P&S AN AIRCRAFT BUOYANCY AUGMENTATION DEVICE BACKGROUND ART This invention relates to the aviation industry in particular but not exclusive to a buoyancy augmentation device for conventional aircraft.

The aviation industry, commercial or military consumes a vast amount of fuel in order to transport personnel and cargo. Fuel costs are a large proportion of the cost of operating aircraft. Savings in fuel consumption by aeronautical engineering improvements not only lower the direct operating costs of an aircraft but can result in increases to payload capacity i.e. passengers, cargo, fuel that aircraft can lift, or give the aircraft greater range of travel or more time in the air.

Airliners, military, transport and cargo aircraft are operated daily with large volumes of non or under utilized space within their airframes, for example, within internal structures, behind panels, under fairings, between floors, within cargo and passenger compartments and equipment bays, including empty cargo hold transport space. In both pressurised and non-pressured areas air usually occupies these spaces.

Within a pressurised fuselage, air is circulated through the hull under positive pressure in order to keep the air fresh and breathable and at a reasonable temperature. Air on demand is normally fed from the engine compressors. By reducing the volume of air to be refreshed within the pressure hull, a lower volume of air is required to be tapped from the engine compressors contributing to a lower energy requirement, and therefore lower fuel burn.

Aircraft manufacturing is focused on aerodynamic design, construction, material weight and construction method i.e. engineering design in order to save weight, reduce airframe drag, reduce operating electrical loads, improve engine designs and efficiency, and to re-circulate up to at least seventy-five percent of cabin 2 air. The entire volume of air within the pressure hull is refreshed approximately every four minutes. Currently, conventional aircraft operators and manufacturers have not identified the unoccupied airspaces within their airframes as "useful space" other than for additional components or fuel storage.

The spaces within current airframes are under utilized and are filled or occupied with air. They are therefore a disadvantage to fuel consumption. The industry has failed to recognize such space as useful and has failed to take advantage of these spaces.

Aircraft, by their nature and engineering constraints, must be shaped accordingly in order to be aerodynamically efficient or to house componentry for example the pressure hull must be of a substantially circular cross section for design weight efficiency. These constraints lead to the creation of unutilized, air occupied voids.

WO99/2435 (Lockhead Martin Corp) describes an ultra large, partially buoyant airship having an airfoil configuration with propulsion apparatus supported on various locations. This however, is a refinement of an airship or lighter than air dirigible and is not comparable to conventional cargo and passenger aircraft operating at high speed.

Airships in general, are cumbersome, slow and prone to inoperability in poor weather conditions and are difficult to handle or load and carry relatively small loads for their size.

Furthermore, ducting, pipes, hoses and electrical cables are supported by relatively heavy rods, clamps, clips etc. which adds weight and reduces payload. In addition, electrical cables/wires currently transit air filled spaces in conventional airframes and as air supports combustion can potentially present an electrical fire hazard.

OBJECT OF INVENTION It is therefore an object of the present invention to seek to ameliorate or eliminate some of the disadvantages and limitations of the prior art or to at least present the public with useful choice.

STATEMENT OF INVENTION Essentially the invention is a gas impervious bladder or compartment filled with lighter than air gas, preferably helium installed within the otherwise unoccupied areas of an airframe, which will apply buoyancy lifting force to the airframe thereby increasing the lifting capability of the airframe in air by offsetting a portion of the weight of the airframe. The compartment(s) can be designed into new airframes or retrofitted to existing airframes. There are no limits to the size or configuration of the aircraft for which they can be designed and installed. The compartments must be a lighter nett weight than the buoyant force they are to exert to be effective.

In one aspect the invention resides in an aircraft buoyancy augmentation device for installation in conventional aircraft including in combination, one or more inflatable bladders or compartments, adapted to reside in spaces or cavities between internal structural members of the aircraft fuselage, wings or tail section, the inflatable bladders or compartments adapted to be inflated under pressure with a lighter than air fluid thereby providing non-aerodynamic lift.

As the buoyancy compartment is pressurized, it has a structural strength and may be used to support aircraft equipment such as but not limited to, ventilation ducting, other tubing or electrical conduits, thereby eliminating that hardware currently used to support them. Surfaces of the compartments may also provide a replacement for such hardware items, and are not limited to, sidewall panels, cabin ceiling panels, overhead locker enclosing paneling, cargo side or ceiling panels etc eliminating the need for and therefore the weight of these items.

In another aspect therefore the invention resides in an inflatable internal componentry support member of an aircraft adapted to support by compressive force, aircraft componentry located between the inflated member and the aircraft internal structure, the support member adapted to be filled under pressure with a lighter than air fluid thereby also providing non-aerodynamic lift.

Preferably the componentry support member when inflated provides structural support to the cabling, hoses, connections and internal components in contact with the support member.

Preferably the bladders or compartrilents when located in the cargo or passenger area are fabricated of a compliant and strong sheet material and substantially occupy empty space surrounding cargo or unoccupied seats.

The compartments may be rigid, semi rigid or flexible in nature or a combination of these characteristics. They may also be structurally reinforced with ribs, internal/external straps or formers to maintain shape as or where required.

Preferably the componentry support member is formed from durable flexible plastic, rubber or other flexible composite material.

More preferably, the compartments may be made from, but not limited to, plastics, fibres, metals, fabrics or rubbers including butyl, nitride, silicone, natural or combinations of such materials taking into account the environment in which they are installed.

Factors for environmental consideration include the temperature expected, the maximum pressure differential possible, the capacity and structural capability of the designated space in which the compartment is to reside, the presence of reagent fluids and the compartments proximity to sensitive equipment. The materials should be lightweight and meet industry approved specifications.

If made from thermally insular materials, the devices may replace aircraft thermal insulation blankets.

Preferably the bladders or compartments when located in the internal space or cavity of the aircraft are configured in shape and size to fit the space or cavity in which they reside.

Preferably, the compartments should be shaped to take advantage of the largest volume possible.

Preferably the lighter than air fluid is helium, or an equivalent non-combustible inert gas.

Preferably, the compartments, can be used singularly, or in combination with other such compartments.

For ease of maintenance access, the compartments should be readily deflateable and removable, mainly from a direct access panel or an adjacent panel already existing.

Visible compartments may be finished decoratively for aesthetics if required.

Preferably, a simple, lightweight inflation/deflation valve is installed in an easily accessible location on the compartment.

The compartments should have strength enough to withstand the maximum pressure differential anticipated for flight conditions plus an appropriate safety margin.

An overpressure protection valve may be installed individually or incorporated into the filling valve of each compartment.

Preferably, compartment pressure is monitored locally with a simple indicator or electronically with a pressure switch individually or in series or parallel with others.

Preferably, the monitor is a go/no go mechanical or electro-mechanical device to indicate when pressure is correct especially for cargo and cabin removable compartments. For permanently installed, not so easily accessed compartments, electric monitoring is favourable. Otherwise, periodic inspection is required of the monitoring system.

Monitoring is necessary because it is important to know a compartment's status for aircraft weight and balance calculation.

Weight and balance calculations can be done manually using aircraft manufacturers supplied tables or through the aircrafts C.O.G (centre of gravity) computer if installed. Modification of the C.O.G computer would be necessary (through software and/or hardware intervention) Moment change would need to be calculated for each buoyancy compartment according to its lift value and its location in the aircraft.

Weight and balance responsibility rests with the aircraft manufacturer and operator.

The compartments can be singular or multi-cellular and are an adjunct to the airframe of a conventional aircraft and may be designated to replace any decorative structures or fill any space within the airframe.

For most locations within an aircraft the buoyancy device will be installed prior to fitting of access panels then inflated to design pressure and will need no specific tethering, being contained within the structural cavity.

Preferably, a simple strap or hook system is all that is required to tether the compartments to the aircraft. Other means of tethering include velcro and/or press studs. Tethers should be as lightweight as possible and be of industry approved materials.

The compartments should be durable, not easily punctured, not easily burnt or be toxic or in any way cause damage to the airplane or its equipment in and should not interfere with radio reception or transmission.

Servicing can be accomplished from handled or mobile vehicular mounted apparatus, typically consisting of a storage tank, gas pump and pressure regulator being attached to a valve on the buoyancy compartment via a hose and fittings which enables inflation and deflation of the compartment as required and enables the reuse of evacuated gas. Almost all this equipment is commercially available.

DETAILED DESCRIPTION OF DRAWINGS Referring now to Figure 1 there is shown a side view of an aircraft 10 showing the positions of the inflatable bladders or compartments 11, 12, 14, 16,18 in the fuselage section of the aircraft and the tail portion 20, 22, 23, 25, 27 of the aircraft.

The bladders and compartments are ideally filled with a lighter than air gas typically helium.

Shown are compartments 24, 26 in the nose section of the aircraft and at the base of the wing 12, 14 and rear cargo portions 16, 18 of the aircraft.

Figure 2(a) shows the nose section 50 of the aircraft 51 wherein the nose cone structural support compartment 50a is located behind the nose cone bulkhead and is adapted to be filled under pressure with an inert lighter than air gas, typically helium.

The nose cone 50a is shown configured having two trailing sections 50b, extending rearward of the nose cone to maximize the volumetric capacity of the support member. Where there is electronic equipment behind the nose cone such as weather radar, the support member may be configured to occupy any free space and to provide support to cabling, conduits and other equipment.

Figure 2(b) shows position of lighter than air bladders 52 filling an unoccupied top passenger area. A bladder or compartment 54 can also fill the freight area when there is little freight as well as part of the nose cone 56.

Figure 3(a) and 3(b) show passenger 60 and freight aircraft 70 respectively having bladders or compartments 62, 72, 74, 76, 78 in the fuselage and tail sections 64, 66, 68.

In the case of the passenger aircraft Figure there are compartments 61 located in the bulkhead of the first class section as well as the floors 63 and bulkhead section 62. The tail section can also be filled with compartments having lighter than air bladders 63, 65, 67, 69.

Where there is no luggage the complete luggage areas 70, 71 can be further occupied by a bladder or compartment filled with helium as well as the unoccupied luggage space 65 in the nose of the aircraft In the case of the freight aircraft shown in Figure the freight 80, 82, 84, 86 may be positioned strategically in the aircraft to balance the loading of the aircraft. The freight can then be held in place by the bladders or compartments 72, 74, 76, 77, 78, 79 positioned between the items of freight in the tail section, base of the wing and upper freight sections.

Figure 4(a) shows a cross section through the fuselage of an aircraft 90 of Figure 4(b) showing the position of bladders and compartments in the bulkhead 100 and in the floor 102 of the passenger compartment and in the freight area 92, 94, 96, 98 of the aircraft. Also shown in Figure 4(b) is a central fuel tank bladder 101 which is normally empty in aircraft on flights of short duration.

As shown the bladders or compartments are compartmentalized and may be of separate configurations that is half circular 98 and rectangular 92 cross section or configurations.

Figure 5 shows a view through the passenger section of the aircraft 110 wherein an inflatable compartment 112 is shown in the bulkhead of the aircraft having a concealed valve 114 for manually filling the bulkhead compartment 112. Each bulkhead 113, 115 compartment has its own filling valve 111, 117. Also shown are floor section compartments 116, 118, 120 connected with a concealable manually filling station 122. Both bulkhead and floor compartments are connected by pressure monitors and lines 124, 125 attached to each compartment for electronically monitoring the volume and pressure of each compartment.

Figure 6(a) shows a longitudinal cross section 130 in a passenger area which is unoccupied. The inflatable bladder 132 is configured to fit in between the seats 134, 136, 138, 140 to maximize the volume of the bladder. On deflation the bladder can preferably be rolled up and stored at an airport or other storage station. Also shown are floor compartments 142, 144 which are located between the ribs 146, 148 of the floor as shown in Figure 6(b).

Figure 7(a) shows a perspective view of the bladder or compartment 150 in the lower freight area of an aircraft. The compartment may be moved in any position along the fuselage of the aircraft to distribute the load in the aircraft. The freight compartment is used when there is no or little freight so that the balance of the aircraft can be optimised. Figure 7(b) shows a typical lower freight fuselage configuration of bladders or compartments 152, 154, 156, 158, 160 of different shapes or sizes each adapted to be filled manually. The compartments are tied down to the floor by means of heavy duty straps 162, 164 and each compartment typically has raised dimples 152a, 154a, 156a, 158a, 160a to prevent the top of the compartments when fully inflated from completely touching the panels of the aircraft flooring or roof structure.

Figure 8 shows a structural view through a lower portion of the fuselage 170 wherein the compartments 172, 174, 176, 178 can be configured to occupy space between structural members 180, 182 such as the ribs of the fuselage as well as between the floor beams 184, 186. Each compartment has a manual filling valve 172a, 176a, 178a shown and can be independently inflated to balance the aircraft.

Figure 9 shows an aircraft 190 on tarmac service ramp 192 as well as having its compartments inflated by means of a mobile pump truck 194 which receives the lighter than air gas, preferably helium from a storage tank 196 at an airport or flight centre facility. In the alternative, where there is no storage tank, the lighter than air gas may be provided by a mobile tanker carrying the same.

Figure 10 shows the invention adapted from military operation wherein a cargo aircraft 200 is shown with its fuselage almost completely filled with bladders or compartments 210, 212, 214 containing lighter than air gas. It is also shown in broken lines a lighter than air compartment 218 in the nose cone. In military operations where there are a smaller number of passengers the augmented buoyancy of the lighter air compartments filling the fuselage would allow the military aircraft to fly at high altitudes for a greater distance without refueling.

COMMERCIAL ADVANTAGE As weight equals cost, the reduction in airframe net weight equals an increased payload resulting in increased operator profit or competitive advantage.

Manufacturers can market increased payload or range based on same airframe model i.e make their aircraft more attractive to buy.

The use of the invention in aircraft manufacture could also reduce the number of parts or components within any given aircraft model by eliminating fixtures and hardware namely equipment to fix cabling, connections, and conduits and the time taken.

The basic engineering is relatively simple and simple to install, other advantages include the absence of any major regulatory hitches and wasted space is used positively. Increased airframe lifting efficiency without penalties, and the use of helium, provides a natural presence of fire retardant gas especially for cargo holds. In a ditching event, i.e aircraft having to land on water, the aircraft will be more buoyant, thereby giving more time to evacuate the crew and passengers.

VARIATIONS

It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth.

Throughout the description and claims this specification the word "comprise" and variations of that word such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps.

Claims (4)

1. An aircraft buoyancy augmentation device for installation in conventional aircraft including in combination, one or more inflatable bladders or compartments, adapted to reside in spaces or cavities between internal structural members of the aircraft fuselage, wings or tail section, the inflatable bladders or compartments adapted to be inflated under pressure with a lighter than air fluid thereby providing non-aerodynamic lift.

2. An inflatable internal componentry support member of an aircraft adapted to support by compressive force, aircraft componentry located between the inflated member and the aircraft internal structure, the support member adapted to be filled under pressure with a lighter than air fluid thereby also providing non-aerodynamic lift.

3. An inflatable componentry support member as claimed in claim 2 wherein when inflated provides structural support to the cabling, hoses, connections and internal components in contact with the support member.

4. The invention as claimed in any of the above claims when located in the internal space or cavity of the aircraft is configured in shape and size to fit the space or cavity. The invention as claimed in any of the above claims wherein the lighter than air fluid is helium.