WO2006024842A2

WO2006024842A2 - Improvements in or relating to airships

Info

Publication number: WO2006024842A2
Application number: PCT/GB2005/003356
Authority: WO
Inventors: Christopher George Hey
Original assignee: Christopher George Hey
Priority date: 2004-08-28
Filing date: 2005-08-30
Publication date: 2006-03-09
Also published as: GB0419232D0; WO2006024842A3; GB2417472A; GB2417472B

Abstract

An airship (1) having a rigid plastics hull (2) generally of ovoid shape and filled with a lifting gas such as helium so that the airship of pressurized monocoque construction. The airship has four expandable ballast air bags/containers (3, 4, 5, 6) and air can be introduced into and released from the bags/containers through apertures (not shown) in undercarriage (8). Four angularly spaced tail fins (7) are provided for aerodynamic trim control in forward motion (but not at low airspeeds). If air is pumped out of bags, by pump means operated by control means in the undercarriage, a controlled ascent of airship can be achieved, control being maintained by controlling the amount of air ejected from the bags. When descent is desired, ballast (air) is pumped into the bags from the ambient air, thus increasing the load carried, again under control, without gas loss, and enabling the airship to achieve and maintain a desired height, without recourse to forward speed or aerodynamic forces.

Description

IMPROVEMENTS IN OR RELATING TO AIRSHIPS

This invention relates to improvements in or relating to airships and is more particularly concerned with airships having a hull of pressurized monocoque construction.

A monocoque (single shell) or unibody construction utilizes the external skinning of an object to form some, or most, of the structure. Such a structure is opposed to using an internal framework that is then covered with a non-structural skinning. '

Generally, there are currently two main types of airship hull, namely rigid or limp. Airship development curtailed in the 1930s, following on from the disasters with the Hindenberg (Germany),R101 (UK) and Shenandoah (USA). However, fresh consideration of the problems of airship construction since then resulted in a third kind of airship hull, namely a pressured monocoque utilising a stressed skin.

Traditionally, airships have incorporated a gas (e.g. helium) envelope or bag (or gas envelopes/ bags) retained within an outer cover (which cover is held in place by a frame in the case of a rigid airship). In such designs, it tends to be disadvantageous that a substantial portion of the space enclosed within the outer cover does not contain any of the lifting gas so that maximum utilisation of space has not been realised. In addition, it tends to be disadvantageous that structure and material are required to keep the gas envelope/s or bag/s and the fabric ( e.g. Dacron, polyester, mylar,Tedlar and Hytrel) of the outer cover apart from each other, as well as apart from the frame, in order to avoid or seemingly minimise wear of the envelope/s or bag/bags or outer cover and/or gas leakage arising.

A rigid, monocoque, hull (effectively a single, unitary, gas envelope/ bag) may overcome, or alleviate, the problems of wear, and seemingly make maximum use of the space available. However, such a rigid monocoque construction whilst having the aforementioned advantages tends to have other problems, in particular relating to trim and height/lift control in particular relating to ballast.

Until now, airships have generally used water as ballast. The purpose of the ballast is not only to prevent the airship from rolling, and keep it upright, but also to enable the trim to be adjusted during flight (as fuel is used up) and to assist in height/altitude control. It tends to be problematic that once ballast has been ejected it cannot be replaced until the airship has landed. It also means the airship is very 'light' when landing, unless lifting gas is ejected at the end of the flight.

A single, gas filled envelope or cell will generate a fixed amount of lift and the total lift available can be calculated as a simple subtraction of the total (empty) mass of the envelope/cell ( i.e. in this case pressurized monocoque airship) from the lifting force generated by the gas content. This tends to create problems in keeping the airship at, or near, ground level (for loading etc), or in controlling the rate of ascent of the airship until the altitude where lift generated equals total load is reached. There also tends to be problems in altitude control and controlling the rate of descent - if these are controlled by lifting gas loss this reduces the control options available, as well as being expensive, and is an inefficient use of lifting gas. Some altitude control can be achieved as a result of forward motion, using aerodynamic forces over the control surfaces, but at departure, upon arrival, and in bad weather, slow speed is desired, reducing the aerodynamic control forces available. Alternatively, dynamic control of the airship can be accomplished by suitably positioned engines although this would seem to be an inefficient use of power.

Traditionally, this problem has been dealt with by carrying ballast (such as water) which is released in a controlled manner for ascent. In such a scenario, it tends to be disadvantageous that gas is lost if available aerodynamic forces are not great enough to enable the craft to descend, or to remain at a particular altitude. Additionally, in the 1930s accurate altitude control was not a matter of crucial importance, especially in view of the fewer (and slower) aircraft in the air.

It is an object of the present invention to at least alleviate the aforementioned, or other, problem associated with airships.

According to the present invention there is provided an airship having a hull which, in use, is of pressurized monocoque construction comprising a rigid envelope, in use, containing gas and said envelope housing at least one ballast bag or container, the arrangement being such that air can be introduced into or released from said at least one ballast bag or container in order to control the airship in flight. Advantageously, the airship in accordance with the present invention uses air as ballast, and thus ballast can be ejected, and replaced, as desired, at any convenient time during flight. Advantageously, in most cases, lifting gas does not need to be ejected from the airship to control the airship, at any stage of flight, or whilst the airship is on the ground.

The air bags/containers will usually be expandable and made of any suitable material which will usually be non-permeable e.g. Dacron, polyester, mylar, Tedlar and Hytrel, or rubber.

Usually, the airship will be provided with pump means such as one or more electrical (preferably hydraulic) pumps arranged to pump ambient air into said at least one ballast bag or container via suitable valve means and/or out of said at least one ballast bag or container as and when required, preferably through said valve means.

Conveniently, control/s for the pump means may be located in a cockpit provided outside of the monocoque hull (usually the cockpit is located underneath the hull).

In one embodiment of the present invention, the hull is provided with a ( rigid) frame or keel (at the base of the hull), in use, supporting the cockpit, and said frame or keel preferably spans ( and advantageously supports) the air bag/s or container/s. Thus, air may pass through apertures in the frame or keel to and from the bag/s or container/s. Advantageously, the frame or keel may be designed to support or suspend cockpits of different sizes ( for example for a one man crew or alternatively for two man crew or greater) and may be provided with appropriate differently placed coupling fixtures providing a modular arrangement of cockpits for the same frame/keel.

In one embodiment of the present invention, at least two air ballast bags/containers are provided and an air communication line or network is provided between them, the arrangement being such that air can be transferred from one bag/container to the other or others, in order to achieve altitude control and/or trim control.

In one embodiment, only one air bag/container is provided, preferably, located along the longitudinal axis of the airship forward or aft of the centre of lift (centre of buoyancy).

In another embodiment, two bags/containers are provided one on each side of the centre of lift. Preferably, air can be transferred from one bag/container to the other to control altitude and trim of the airship. Preferably, two additional bags are located one on each side of the centre of lift to control lateral trim. Preferably, said two additional bags/containers are located on the lateral axis of the airship and an air communication line/network may be provided between them to allow air to be transferred selectively between them via pump means. Preferably, air communication lines are provided between all four bags or at least between opposite pairs of bags ( one pair being arranged laterally and the other pair being arranged longitudinally). In some embodiments a fifth air bag/container is provided ( preferably either centrally of the airship or in a position midway between the centre of lift and the most forward bag/container).

Advantageously, the airship may be a pressure vessel able to resist an internal pressure of at least two atmospheres ( and not more than 2.5 atmospheres) with an external pressure of one atmosphere (i.e. a pressure difference of 1 atmosphere) or an internal pressure of no less than half an atmosphere, with an external pressure of one atmosphere (i.e. a pressure difference of half an atmosphere.)

Preferably, facility is provided for ancillary equipment (engines, crew positions, etc) to be mounted and carried outside of the monocoque hull (the crew positions being located in a, or the, cockpit)l, and fairings or the like may be added to the hull in order to streamline control surfaces and the like, in a similar fashion to traditional airships.

The ballast bag/s or container/s is/ are, preferably, located low down within the craft (preferably as low as possible), and/or directly below the centre of lift or the airship. Where two or more airbags/containers are provided they may be arranged symmetrically or regularly around the centre of lift of the airship.

The hull may be of any suitable material such as rigid plastics or metal or carbon fibre.

An embodiment of an airship in accordance with the present invention will now be described, by way of example only, with reference to the much simplified accompanying drawings, in which;- FIGURE 1 is a perspective side view of the airship showing the general location of ballast air bags or containers within the airship;

FIGURE 2 shows a more diagrammatic side view of the airship similar to FIGURE 1 but showing various configurations of the air bags or containers in deflated and inflated states, and

FIGURE 3 shows a diagrammatic plan view of the airship shown in FIGURE 2 depicting the location of ballast air bags/containers within the airship.

Referring to the FIGURES of the drawings, an airship 1 has a rigid plastics hull 2 generally of ovoid shape and is filled with a lifting gas G such as helium ( see FIGURE 2) so that the airship of pressurized monocoque construction.

This embodiment of the airship 1 is provided with four expandable ballast air bags/containers 3,4,5,6 although it is possible in other embodiments for only one such airbag to be provided under the centre of lift.

The airship 1 has four angularly spaced tail fins 7 (only three shown in FIGURE 1) for aerodynamic trim control in forward motion ( but not at low airspeeds).

The airship 1 is provided with an underbelly cockpit structure 8 ( shown connected to keel 8a in FIGURE 1) for ancillary equipment and is generally of known form. The keel 8a spans and supports the air ballast bags/containers 3,4,5,6 ( see FIGURE 1) and air can be introduced into and released from the bags/containers through apertures ( not shown) in the undercarriage 8.

The airship 1 overcomes problems encountered in trim control and in using water as ballast by carrying the ballast air bags 3,4,5,6 (or bag) internally, within the monococque hull 2. In use of the airship 1, bags 3,4,5,6 can have outside air ( ambient air from outside the airship 11) pumped into them (or out of them) by pump means ( not shown) through valves ( not shown) on the bags/containers by control means( not shown) located in the cockpit 8, the air being the ballast, in a manner to be described. Additionally, as will be evident from the FIGURES airbags 3,4,5,6 are interconnected by airlines a,b,c,d so that air can be transmitted from one bag to another for reasons explained later on in this specification.

If air is pumped out of bags 3,4,5,6, by pump means operated by control means in the cockpit 8, a controlled ascent of airship 1 can be achieved, control being maintained by controlling the amount of air ejected from the bags.

When descent is desired, ballast (air) is pumped into the bags 3,4,5,6 from the ambient air, thus increasing the load carried, again under control, without gas loss, and enabling the airship 1 to achieve and maintain a desired height, without recourse to forward speed or aerodynamic forces. The air used as ballast is contained within the bags 3,4,5,6 to avoid 'free water effect' which would disrupt the trim of the airship. The bags 3,4,5,6 (or bag in other embodiments) are also positioned to assist in trim control as described later.

FIGURE 2 shows bags/containers 3,4,5,6 in a deflated state ( solid lines) , in a partly inflated state 3\4' ,5" ,6" ( first set of dashed lines) and in a second more inflated state 3' ' ,4" ,5' ' ,6' ' (second set of dashed lines).

Pumping air into the bags /containers 3,4,5,6 in the monocoque hull 2 will increase the pressure within. This will increase the pressure of the lifting gas G, thus decreasing the lift generated. Thus, if it is desired to secure the airship 1 on the ground, the internal pressure could be increased to the extent that the lifting gas G ceases to generate lift, and increases the total weight (as against mass) of the airship 1, ensuring the airship rests firmly on the ground (on the undercarriage) and minimising the risk of weather induced movement. Typically an internal pressure of 1.5 atmospheres should be more than adequate for this purpose.

For ascent to a maximum altitude the ballast air would be ejected from the bags 3,4,5,6, under control, ultimately leaving the airship 1 entirely filled with lifting gas G, and thus at maximum lift. In this situation, the internal / external air pressure difference is expected to be to be no more than 0.2, and probably less than the ambient pressure at that altitude.

These pressure differences should generate additional loads on the structure of the airship 1. Such loads should be adequately borne by the stressed skin monococque structure.

This system of control as aforedescribed should avoid the disadvantages of the total loss ballast system as aforementioned, so that that controlled gas loss is no longer required for height control of the airship 1. Advantageously, this avoids any dynamic control by engines being necessary.

In forward motion of the airship I, aerodynamic trim can be utilised by the conventional system of tail surfaces 7 to provide control in longitudinal and lateral senses. These forces are generated by forward motion, and such trim control is not available at low airspeed.

Static trim can be achieved, maintained, and controlled, at all stages of flight, by using the internal air ballast bags 3,4,5,6.

Trim along the longitudinal axis of the airship 1 could be attained with a single ballast airbag ( e.g. just airbag 3) by placing that bag along the longitudinal axis, but slightly forward (or aft) of the centre of lift or buoyancy X. Adjustment of the air volume in the bag 3 would affect the trim. This would also affect the height control, and, therefore, two or more air bags ( e.g. 4,5 or 4,5,6) should conveniently be used, one ahead of, and the other aft from, the centre of lift or buoyancy X. By this means, altitude can be maintained by retaining a constant pressure, but adjusting trim simply by shifting air from one bag to another. This would mean that the weight of a bag 3,4,5,6 with more air would generate a moment around the centre of lift X, and thus with control of the amount of air, the desired trim of the airship could be achieved, thus maintaining desired altitude whilst adjusting trim.

Similarly, for lateral trim, two or more airbags ( 3,4,5,6) could be placed either side of the centre of buoyancy X, along the lateral axis of the airship 1. The size of such airbags (e.g 5,6) would not need to be very great, as there is unlikely to be much need for adjustment of lateral trim.

In general, trim would be controlled by using a minimum of four airbags 3,4,5,6 as shown in FIGURE 3 arranged along the longitudinal and lateral axis of the airship 1, below the centre of lift X, by means of pumping the air ballast between the bags 3,4,5,6 via air communication lines a,b,c,d, suitable valves ( not shown) being provide in the communication lines. The centre of gravity of the airship 1 is depicted by reference numeral g in FIGURE 2. The total ballast would remain constant, thus enabling the desired height to be maintained. In the event of a need to change height, then air ballast would be added to, or dumped from, all the bags 3,4,5,6 in proportion, thus maintaining desired trim whilst adjusting altitude.

FIGURE 3 shows in dashed lines a possible location for a fifth air bag/container Y, if desired. The chain-dotted lines L in FIGURES 2 and 3 represent circular frames of the monocoque hull 2.

The traditional airship requires large numbers of personnel for ground handling. Advantageously, the airship 1 does not require such personnel, in view of the ability to increase mass.by taking on air, and thus reducing the lift, and 'lightness' of the craft.

The airship 1 may utilise a tricycle undercarriage, which would typically be attached to the keel 8a, for manouvering when on the ground, and can be moved under its own power, or by any of the usual kind of tow vehicles available for fixed wing aircraft. However, the size of the airship 1 may provide certain constraints. In contrast, the kind of heavily prepared mooring mast or like facility for airships would not usually be required.

The keel 8a may be provide with coupling means for affixing various sizes of cockpits and/or passenger modules, equipment modules, cargo modules or the like thereto in a modular fashion.

It is to be understood that the scope of the present invention is not to be unduly limited by the particular choice of terminology and that a specific term may be replaced or supplemented by an equivalent or generic term. For example, the term 'envelope' could be replaced by 'shell' or 'bag ' may be replaced by 'cell or expandable cell'. Further it is to be understood that individual features, method or functions relating to the airship or ballast arrangement might be individually patentably inventive. The singular may include the plural and vice versa. Additionally, any range mentioned herein for any parameter or variable shall be taken to include a disclosure of any derivable sub-range within that range or of any particular value of the variable or parameter arranged within, or at an end of, the range or sub-range.

Therefore, further according to the present invention there is provided a keel or frame for an airship, said keel/frame being adapted for suspending (interchangeable) cockpits or passenger, equipment or cargo modules or the like of varying size. The keel or frame will be adapted for suspending at least two different sizes (lengths) of cockpit/module.

Further according to the present invention there is provided an airship having a frame or keel in accordance with the immediately preceding paragraph.

In this manner, an airship can be built in a modular fashion with the cockpit/module being a selected one of a plurality of size options.

Further according to the present invention there is provided a kit of parts including a hull and a plurality of (interchangeable) cockpits/modules of varying size, the arrangement being such that the airship can be built by attaching a selected one of the cockpits/modules to the hull.

Claims

1. An airship having a hull which, in use, is of pressurized monocoque construction comprising a rigid envelope, in use, containing gas and said envelope housing at least one ballast bag or container, the arrangement being such that air can be introduced into or released from said at least one ballast bag or container in order to control the airship in flight and preferably in which the air bags/containers are expandable and preferably in which the air bags/containers are made of non- permeable material e.g. Dacron, polyester, mylar, Tedlar and Hytrel, or rubber.

2. An airship as claimed in claim 1 provided with pump means arranged to pump ambient air into said at least one ballast bag or container via valve means and/or out of said at least one ballast bag or container and preferably in which air can be pumped out of said at least one air bag or container via said valve means and preferably in which the pump means comprises one or more electrical pumps and preferably in which the pump means is hydraulic and preferably in which control/s for the pump means are located in a cockpit provided outside of the monocoque hull and preferably in which the cockpit is located underneath the hull and preferably in which the hull is provided with a frame or keel, in use, supporting the cockpit and preferably in which said frame or keel spans and supports the air bag/s or container/s.

3. An airship as claimed in Claim 2 in which, in use, air can pass through apertures in the frame or keel to and from the at least one air bag or container and preferably in which the frame is rigid and preferably in which the frame or keel is at the base of the hull and preferably in which the frame or keel can support or suspend cockpits of different sizes and preferably in which the frame or keel is provided with differently placed coupling fixtures providing a modular arrangement of cockpits for the same frame/keel.

4. An airship as claimed in any one of the preceding Claims having at least two air ballast bags/containers and an air communication line or network provided between said at least two air bags/containers, the arrangement being such that air can be transferred from one bag/container to the other or others, in order to achieve altitude control and/or trim control and preferably in which the at least two bags/containers are provided one on each side of the centre of lift and preferably in which two additional air bags/containers are located one on each side of the centre of lift to control lateral trim and preferably in which said two additional bags/containers are located on the lateral axis of the airship and preferably in which an air communication line/network is between said two additional air bags/containers to allow air to be transferred selectively between them via pump means and preferably in which air communication lines are provided between all four bags or at least between opposite pairs of bags ( one pair being arranged laterally and the other pair being arranged longitudinally).

5. An airship as claimed in claim 4 in which a fifth air bag/container is provided and preferably in which the fifth air bag/container is centrally of the airship or in a position midway between the centre of lift and the most forward bag/container or in which a single air bag/container is provided located along the longitudinal axis of the airship forward or aft of the centre of lift (centre of buoyancy).

6. An airship as claimed in any one of the preceding Claims which is a pressure vessel able to resist an internal pressure of at least two atmospheres ( and not more than 2.5 atmospheres) with an external pressure of one atmosphere (i.e. a pressure difference of 1 atmosphere) or an internal pressure of no less than half an atmosphere, with an external pressure of one atmosphere (i.e. a pressure difference of half an atmosphere.)

7. An airship as claimed in any one of the preceding Claims in which facility is provided for ancillary equipment (engines, crew positions, etc) to be mounted and carried outside of the monocoque hull (the crew positions being located in a, or the, cockpit) and preferably in which and fairings or the like can be added to the hull in order to streamline control surfaces and the like.

8. An airship as claimed in any one of the preceding claims in which the ballast bag/s or container/s is/ are located low down within the craft and/or directly below the centre of lift or the airship or having two or more airbags/containers arranged symmetrically or regularly around the centre of lift of the airship or in which the hull is of any suitable material such as rigid plastics or metal or carbon fibre.

9. A keel or frame for an airship, said keel/frame being adapted for suspending (interchangeable) cockpits or passenger, equipment or cargo modules or the like of varying size and preferably adapted for suspending at least two different sizes (lengths) of cockpit/module or an airship having such a frame of keel.

10. A kit of parts including a hull and a plurality of (interchangeable) cockpits/modules of varying size, the arrangement being such that the airship can be built by attaching a selected one of the cockpits/modules to the hull.