Tactical Hybrid Stratospheric Airship

Abstract

A hybrid stratospheric airship (1;1') comprising an inflatable central body (10), first and second wings (20A, 20B) extending from the central body and projecting laterally from two opposite sides thereof, the first and second wings having proximal and distal end portions (21A, 21B) and leading edges (201A, 201B) and trailing edges (202A, 202B) of the central body, a main shell portion (11A-C) joining the main body, and a main shell portion (11A-C) joining the first and second wings and each of the first and second wings. The aircraft includes an outer shell (11) having first and second lateral shell portions (11D, 11E) joined together; and at least one main spar (12) extending transversely to the center body, providing structural support to the first and second wings and intersecting the center body, at least one straight spar (12) interposed between the leading and trailing edges of the first and second wings and connected to distal end portions of the first and second wings.

Description

Technical Field

[0001] The present invention relates to the technical field of stratospheric platforms, and more specifically, to hybrid stratospheric airships.

Background Art

[0002] Interest in HAPS (High Altitude Pseudo-Satellite) stratospheric platforms has been increasing in recent years. This interest is motivated by applications that can benefit from the advantages derived from the use of HAPS platforms, such as homeland security, precision agriculture, telecommunications, and environmental monitoring analysis. Different from satellites, HAPS stratospheric platforms offer the possibility of continuously observing the earth's surface on a local scale, that is, virtually without revisit time, and in close proximity, that is, from a much lower altitude than satellites, and thus provide a significantly higher image resolution than that provided by satellite remote sensing, which also introduces payloads with low performance and cost efficiency.

[0003] HAPS is a platform that can typically operate at an altitude of about 18 - 20 km above the earth's surface (lower stratosphere), and can usually operate continuously for several months by using solar power generation energy. The flight altitude (18 - 20 km) is extremely interesting. This is because it well exceeds the altitude range involved in commercial air traffic, so the impact of the HAPS platform on air routes is limited only to the stages of ascending to mission altitude and descending to a landing base. Furthermore, from the perspective of weather conditions, the statistical analysis of the existing wind conditions indicates that the intensity in this altitude range is minimal. The temperature profile of the stratosphere rises as the altitude increases (unlike the troposphere). This stabilizes this part of the atmosphere and prevents the formation of updrafts and turbulence.

[0004] In recent years, several suggestions have been made regarding HAPS platforms. These suggestions can be classified into three main platform types. The first type is represented by stratospheric balloons from a temporal perspective. The second type is represented by fixed-wing type platforms, and finally, the third type is airship type platforms.

[0005] Stratospheric balloon type and airship type platforms are based solely on using aerostatic forces to balance weight (lighter than air), while fixed-wing types use only aerodynamic forces (heavier than air) to balance weight. Balloon type platforms have a high ratio of payload weight to total weight. On the other hand, such balloon type platforms typically do not have a propulsion system nor other direction control systems, and thus do not offer the possibility of setting a predetermined orbit. The orbit is therefore determined by wind conditions at various altitudes.

[0006] Fixed-wing platforms, on the other hand, are based on a form with a very large wingspan to enhance aerodynamic efficiency and are characterized by a very lightweight structure. For the latter reason, the total weight of fixed-wing type platforms must be restricted, reducing the available payload weight to several kilograms (5 - 25 kg). Furthermore, the very lightweight structure of these platforms may pose an aeroelastic problem at low altitudes during the takeoff and landing phases.

[0007] The airship-type platform, on the other hand, is designed for a very high payload (>200 kg) and has a very large size and a very high maximum takeoff weight (MTOW (maximum takeoff weight) > 5000 kg) compared to the balloon-type platform and the fixed-wing-type platform. Such an MTOW is mainly due to the presence of the gas envelope. The gas envelope constitutes a second inner shell of a size almost equal to the outer shell. This second inner shell is necessary to compensate for the gas expansion associated with altitude changes (the volume at high altitudes can be up to 20 times the volume at sea level). The large size of the stratospheric airship makes ground operations difficult, especially in adverse weather conditions, and requires dedicated infrastructure for their deployment and evacuation, essentially making their tactical use impossible. Therefore, from the analysis of the above prior art stratospheric platforms, two main aspects can be noted. The first aspect relates to the operation of such platforms. It is suggested that the platforms are strongly affected by weather conditions and can only be deployed from a limited number of bases around the world. The second aspect relates to the weight available for the payload. While the weight is limited to exceed 25 kg in the case of the fixed-wing-type platform, the airship-type platform is truly advantageous only for payloads exceeding 250 kg. The inflatable hybrid stratospheric vehicle described in Patent Document 1 can be launched from a submarine or a ship and can utilize both aerostatic buoyancy and lift. Such a vehicle also requires a number of components (e.g., a regenerative fuel cell, an electrolyzer, tanks for water and oxygen, and a vapor recovery system). In addition to making the vehicle heavier, these components reduce its reliability. Furthermore, the vehicle described in Patent Document 1 needs to fly in different forms at different altitudes. This is because, energetically, solar cells have a high weight-to-power ratio, while regenerative fuel cells have a significantly low weight-to-power ratio.Specifically, during the day at an altitude of 21 km, the vehicle uses the solar cells on the central body and the solar cells on the deployed wings to power the motor, and thus the deployed wings also generate the required lift force, and has sufficient energy to generate hydrogen to be used at night as fuel from water by the fuel cell. On the other hand, at night, due to the lack of solar energy and the inability to store sufficient energy to fly at an altitude of 21 km, the vehicle is forced to descend to an altitude of 15 km, so as to utilize the higher air density for both lift and buoyancy, and it is necessary to retract the wings. This is because the vehicle does not have sufficient energy to use the wings. When descending to an altitude of 15 km, such a platform gets extremely close to the altitude affected by commercial air traffic and may cause interference. Furthermore, if the air traffic management authority requires the isolation of the area affected by the flight of such a platform, a larger volume of airspace will be prohibited for the flight of other aircraft. Therefore, in light of the above, it is clear that the vehicle design described in Patent Document 1 can be improved in terms of performance and operability by acting from both the perspective of the adopted energy system and the perspective of the aircraft structural form.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to enable the use of a hybrid stratospheric platform that can solve or at least partially avoid the above-mentioned drawbacks with reference to the prior art.

[0010] According to aspects of the present invention, a further objective is, instead of or in addition to the above objectives, to enable reduction of the weight, size, and cost of a stratospheric platform for the same payload, and thus to provide a hybrid stratospheric platform that can also be employed in tactical type operations.

[0011] According to aspects of the present invention, a further objective is, instead of or in addition to the above objectives, to provide a hybrid stratospheric platform that enables improved system reliability with respect to the above prior art systems.

[0012] According to aspects of the present invention, a further objective is, instead of or in addition to the above objectives, to provide a hybrid stratospheric platform that can load a payload in the range of 35 - 100 kg as required by many applications.

[0013] According to aspects of the present invention, a further objective is, instead of or in addition to the above objectives, to provide a hybrid stratospheric platform having an aircraft structure form that is more efficient than the platform forms of the prior art, specifically within a payload range of 35 - 100 kg.

[0014] According to aspects of the present invention, a further objective is, instead of or in addition to the above objectives, to provide a hybrid airship type stratospheric platform that is also compatible with payloads of less than 35 kg.

Means for Solving the Problems

[0015] These and other objectives are achieved by the hybrid stratospheric airship defined in the appended claim 1 in its most general form and in the dependent claims in some specific embodiments.

Effects of the Invention

[0016] The present invention will be better understood from the following detailed description of exemplary embodiments, which is related to the accompanying drawings and thus is in no way limiting.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figures 7A-7C

Figures 8A-8C

Modes for Carrying Out the Invention

[0018] Like or equivalent elements in the accompanying drawings are denoted by the same reference numerals.

[0019] It should be noted that, for the purposes of this specification, the terms "outer" and "inner" used to describe the hybrid stratospheric airship according to the present invention are intended to refer to the center of such an airship. Further, it should be noted that the terms "lower side", "upper side", "horizontal direction", and "vertical direction" adopted hereinafter in this specification to describe parts of the hybrid stratospheric airship according to the present invention are intended to refer to the normal operating state of such an airship at the assigned mission altitude. Furthermore, the terms "front side" and "rear side" adopted hereinafter in this specification to describe parts of the hybrid stratospheric airship according to the present invention are intended to refer to the forward direction X1 (Figure 2) of such an airship in its normal operating state at the assigned mission altitude.

[0020] Referring first to FIGS. 1-5, a hybrid stratospheric platform according to the first embodiment is generally indicated by reference numeral 1. According to one embodiment, the stratospheric platform 1 is embodied in a hybrid stratospheric airship 1. It should be noted that the "airship" used to describe the stratospheric platforms 1 and 1' (FIG. 6) should be understood in the sense that the geometry of these platforms is more similar to that of an airship-type stratospheric platform than to that of a fixed-wing stratospheric platform. In other words, they have a greater extent in the length direction than in the span direction of the wing length, and also have a higher percentage thickness of the profile used than the profiles typically used for fixed-wing configurations. In fact, the platforms 1, 1' cannot be defined as such as either an airship type or a fixed-wing stratospheric platform. It should also be noted that for the purposes of this specification, the term "hybrid" used to define the stratospheric platform indicates the fact that the stratospheric platform is formed to use aerostatic and aerodynamic forces jointly and in an optimized state. Specifically, the hybrid platform is formed to jointly utilize both aerostatic buoyancy and lift. In this regard, it should also be noted that the airship 1 is advantageously formed to use aerodynamic forces not only to control the airship but also to balance the weight of the airship during various flight phases and, if necessary, to increase the flight altitude. It should further be noted that in other parts of this specification, the structure of the stratospheric airship 1 is formed in relation to each design configuration or mission operation configuration. In this configuration, the airship 1 is inflated with a gas, preferably helium. According to one embodiment, the airship 1 is a HAPS (High Altitude Pseudo Satellite) stratospheric platform. According to one embodiment, the airship 1 is a tactical type of stratospheric platform. This means that the airship can be easily transported inside a standard container and deployed directly towards the operation scenario.This is made possible by the small size and MTOW (Maximum Takeoff Weight). According to one embodiment, the airship 1 has a length L1 of 10m - 40m, a width W1 of 8m - 35m, an MTOW of 25kg - 450kg, and a payload of 5kg - 100kg. Generally, the airship 1 can be used in various different application fields, such as border surveillance, environmental monitoring, precision agriculture, telecommunications, homeland security, and emergency support.

[0021] According to one embodiment, as will be better understood hereinafter in this specification, the airship 1 has a combination of inflatable structural elements 10, 20A, 20B, 12, 23A, 24A, 23B, 24B having various different internal pressures, connected to rigid structures 10A, 10B, 13A, 22A, 22B, 311A - 313A, 321A - 323A, 331A - 333A (made of, for example, composite materials, aluminum, etc.). According to one embodiment, all the inflatable elements of the airships 1 and 1' (Figure 6) described hereinafter in this specification include a laminated material composed of a gas-retaining layer, a structural layer, and a protective layer.

[0022] Referring again to FIGS. 1-5, the stratospheric airship 1 includes an inflatable central body 10 and inflatable first and second wings 20A and 20B. The wings extend from the central body 10 and project laterally from two opposite sides of the central body 10. The wings 20A, 20B can be inflated with a gas, specifically a gas lighter than air, preferably helium. According to one embodiment, under the operating conditions of the airship 1, the wings 20A, 20B are fixed wings, that is, wings that are not folded during the flight of the airship 1 once inflated. The central body 10 is a carrier body and can be inflated with a gas, specifically a gas lighter than air, preferably helium. According to one embodiment, the central body 10 has a central biconvex lens-shaped structure. Each of the wings 20A, 20B has a proximal end portion 21A, 21B proximal to the central body 10 and a distal end portion 22A, 22B distal to the central body 10. The distal portions 22A, 22B are essentially the tips 22A, 22B of the wings 20A, 20B. Each of the wings 20A, 20B includes a leading edge 201A, 201B and a trailing edge 202A, 202B. According to one embodiment, the tips 22A, 22B are preferably rigid lower structures made of a rigid composite material. The wings 20A, 20B, which are aerodynamic elements useful for generating lift, reduce induced drag by controlling the platform and increasing the aspect ratio (AR) of the system.

[0023] Referring to FIG. 4, according to one embodiment, the central body 10, the first wing 20A, and the second wing 20B respectively define a central body chamber 60, a first wing chamber 60A, and a second wing chamber 60B. These chambers are separate from each other and can be inflated independently.

[0024] The airship 1 includes an outer shell 11 or an outer skin 11 having central shell portions 11A-11C. Further, the outer shell 11 includes a first side shell portion 11D and a second side shell portion 11E. These side shell portions are respectively coupled to the first wing 20A and the second wing 20B. Specifically, the central body 10 includes the central shell portions 11A-11C, while the first wing 20A and the second wing 20B respectively include a first side portion 11D and a second side portion 11E. In other words, the central shell portions 11A-11C partition the central body 10 from the outside, while the first side shell portion 11D and the second side shell portion 11E respectively partition the first wing 20A and the second wing 20B from the outside.

[0025] Referring again to FIGS. 1-5, the airship 1 includes at least one main spar 12 extending laterally with respect to the main portion 10. The spar structurally supports the first wing 20A and the second wing 20B described above and intersects the central body 10. The main spar 12 is a straight spar, and the straight spar is interposed between the leading edges 201A, 201B and the trailing edges 201A, 201B of the first wing 20A and the second wing 20B, respectively. The spar 12 is connected to the distal end portions 22A, 22B of the wings 20A, 20B. The at least one spar 12 joins the tips 22A, 22B of the two wings 20A, 20B and passes through the interior of the central body 10, which is advantageous as it enables particularly effective absorption of bending loads.

[0026] According to one embodiment, the main spar 12 includes two opposing end portions 121A, 121B. These end portions respectively extend inside the first wing 20A and the second wing 20B. Each end portion 121A, 121B is tapered in a direction from the proximal end portions 21A, 21B to the distal end portions 22A, 22B of the wings 20A, 20B. According to one embodiment, the main spar 12 has a circular cross-section. According to one embodiment, the end portions 121A, 121B are respectively constrained to the distal end portions 22A, 22B.

[0027] According to an advantageous embodiment, the main spar 12 is preferably an inflatable spar having a tubular shape. Providing at least one main spar 12 is particularly advantageous for high payloads and large configurations. Alternatively, for low payloads and small configurations, at least one main spar 12 made of composite material may be provided.

[0028] According to one embodiment, the airship 1 includes a pair of main spars 12. These main spars are preferably arranged parallel to each other.

[0029] According to one embodiment, the first wing 20A and the second wing 20B each include at least one secondary spar 23A, 24A, 23B, 24B, the secondary spars being arranged inside the wing and having a cross-section of a smaller dimension than the cross-section of the main spar 12. More specifically, according to one embodiment, the average cross-sectional area of at least one secondary spar 23A, 24A, 23B, 24B is smaller than the average cross-sectional area of the main spar 12. According to one embodiment, at least one secondary spar 23A, 24A, 23B, 24B is tapered in a direction from the proximal end portions 21A, 21B to the distal end portions 22A, 22B of the wings 20A, 20B. According to one embodiment, at least one secondary spar 23A, 24A, 23B, 24B extends exclusively inside its respective wing 20A, 20B. According to one embodiment, at least one secondary spar 23A, 24A, 23B, 24B has a circular cross-section. According to one embodiment, at least one secondary spar 23A, 24A, 23B, 24B is arranged so as to approach at least one main spar 12 from the respective proximal end portions 21A, 21B to the distal end portions 22A, 22B of the wings 20A, 20B.

[0030] According to one embodiment, each of the wings 20A, 20B of the airship 1 includes a first secondary spar 23A, 23B and a second secondary spar 24A, 24B. According to one embodiment, the respective first secondary spars 23A, 24A and the second secondary spars 23B, 24B of the wings 20A, 20B are arranged so as to approach each other in a direction from the proximal end portions 21A, 21B to the distal end portions 22A, 22B of the wings 20A, 20B. Specifically, at least one main spar 12 is interposed between the first secondary spars 23A, 24A and the second secondary spars 23B, 24B of the respective wings 20A, 20B.

[0031] According to an advantageous embodiment, at least one of the secondary spars 23A, 24A, 23B, 24B is an inflatable spar, preferably having a tubular shape.

[0032] According to one embodiment, the first wing 20A and the second wing 20B each include at least one planar wing rib 31A - 33A, 31B - 33B made of fabric, and this wing rib is intersected by at least one main spar 12. According to one embodiment, each wing 20A, 20B includes a plurality of wing ribs 31A - 33A, 31B - 33B, preferably three wing ribs 31A - 33A and 31B - 33B, and these wing ribs are intersected by at least one main spar 12. According to one embodiment, the first lateral shell portion 11D and the second lateral shell portion 11E each include an upper surface 111D, 111E and an opposite lower surface 112D, 112E. At least one wing rib 31A - 33A, 31B - 33B joins the respective upper surfaces 111D, 111E and lower surfaces 112D, 112E of the lateral shell portions 11D, 11E, enabling a predetermined aerodynamic profile of the wings 20A, 20B to be achieved during pressurization.

[0033] According to one embodiment, the central body 10 includes at least one central body rib 13 intersected by at least one main spar 12. According to one embodiment, the central body 10 includes a plurality of central body ribs 13, preferably three ribs 13, intersected by at least one main spar 12. At least one rib 13 has a planar shape and is made of fabric. Specifically, the central shell portions 11A-11C include an upper surface 111 and an opposite lower surface 112. At least one central body rib 13 joins the upper surface 111 and the lower surface 112 of the central shell portions 11A-11C so as to enable a predetermined aerodynamic profile of the central body 10 to be obtained when pressurized.

[0034] Referring to FIGS. 4-5, according to one embodiment, at least one main spar 12 is connected at rib joints 13A, 311A, 321A, 331A to both at least one central body rib 13 of the central body and at least one wing rib 31A-33A, 31B-33B of the first wing 20A and the second wing 20B. According to one embodiment, the rib joints 13A, 311A, 321A, 331A include rigid or semi-rigid rings 13A, 311A, 321A, 331A, which are preferably made of composite materials. According to one embodiment, the airship includes a plurality of rib joints 13A, preferably three rib joints 13A, each of these rib joints intervening between at least one main spar 12 and one of the ribs 13. According to one embodiment, the wing 20A includes a plurality of rib joints 311A, 321A, 331, preferably three rib joints 311A, 321A, 331, each of these rib joints intervening between at least one main spar 12 and one of the ribs 31A, 32A, 33A. According to one embodiment, the secondary wing spars 23A, 24A of the wing 20A have respective rib joints 312A, 322A, 332A and 313A, 323A, 333A and are connected to at least one wing rib 31A-33A of the first wing 20A. According to one embodiment, the rib joints 312A, 322A, 332A and 313A, 323A, 333A include rigid or semi-rigid rings 13A, 311A, 321A, 331A. These rings are preferably made of composite materials. According to one embodiment, the wing 20B includes rib joints similar to the rib joints 311A, 321A, 331A and the rib joints 312A, 322A, 332A, 313A, 323A, 333A. Since the wing 20B has the same and symmetric structure as the wing 20A, for the sake of brevity, the rib joints of the 20B wing will not be described in further detail.

[0035] Referring again to FIGS. 4-5, according to one embodiment, at least one main spar 12 is connected to the central shell portions 11A-11C through the central body joint portions 10A, 10B. Specifically, according to one embodiment, the rib joint portions 13A, 311A, 321A, 331A allow the passage of gas. Further, the central body joint portions 10A, 10B are adapted to enable not only a structural connection between the central shell portions 11A-11C and at least one main spar 12, but also a pressure sealing connection. In fact, as described above, according to one embodiment, the central body 10 and the wings 20A, 20B define separate chambers 60, 60A, 60B from each other. Specifically, the chambers 60, 60A, 60B are designed to operate at various different pressures. More specifically, according to one embodiment under the operating conditions and mission altitude of the airship 1, the central body 10 as well as the first wing 20A and the second wing 20B are inflated to a pressure lower than the pressure at which at least one main spar 12 is inflated. For example, according to one embodiment, the main body 10 is inflated to a pressure of about 1000 Pa, while at least one main spar 12 is inflated to a pressure of about 10000 Pa. According to an embodiment under the operating conditions and mission altitude of the airship 1, at least one secondary spar 23A, 24A, 23B, 24B is inflated to a pressure of about 10000 Pa.

[0036] According to one embodiment, the central shell portions 11A-11C include two half-shells 11A, 11B having a semi-circular cross-section or a semi-elliptical cross-section, which are the starting points from which the first wing 20A and the second wing 20B extend, and at least one intermediate portion 11C that joins the two half-shells 11A, 11B. According to one embodiment, the at least one intermediate portion 11C, together with a pair of central body ribs 13, defines at least one section of a central body 10 having a cross-sectional shape that is substantially square-shaped, i.e., having straight sides that face each other in a pair defined by the pair of ribs 13, and convex sides that face each other in a pair defined by the central shell portions 11A-11C. According to one embodiment, the central shell portions 11A-11C include a pair of intermediate portions 11C configured to define a pair of central body sections 10 having a substantially square shape together with the plurality of ribs 13.

[0037] According to one embodiment, the airship 1 is configured to generate an aerostatic buoyancy equal to 30%-70% of the total weight of the airship 1 and simultaneously generate a lift force equal to 70%-30% of the total weight of the airship 1, so that the sum of the aerostatic buoyancy and the lift force is equal to the total weight of the airship 1, or greater than the weight of the airship 1 if a change in altitude is required.

[0038] According to one embodiment, the airship 1 includes at least one propulsion system 51, 52. According to one embodiment, the propulsion systems 51, 52 include a rear propeller 51 disposed on the rear side of the central body 10 and a pair of front propellers 52 disposed on the front side of the central body 10 from two opposing portions of the central body 10. Specifically, the rear propeller 51 is angle-adjustable about a vertical axis, and the front propellers 52 are angle-adjustable about their respective horizontal axes. According to one embodiment, the rear propeller 51 is centrally disposed with respect to the central body 10 and preferably includes a "stern thrust" motor. According to one embodiment, the propellers 52 are symmetrically disposed with respect to the central body 10 and preferably each include a "vector thrust" motor. Such an arrangement of the motors 51, 52 is designed to maximize the lever arm with respect to the center of gravity of the airship 1. According to one embodiment, the propellers 51, 52 are helical propellers. Advantageously, the arrangement of the front propellers 52, which are orientable about their respective horizontal axes, enables obtaining thrust in the vertical plane useful for controlling the altitude of the airship 1 on the vertical plane even at low speeds, while the rear motor 51, which is orientable in the horizontal plane, enables controlling the direction of the airship 1 and eliminates the need for a movable vertical rudder. According to one embodiment, the propulsion system is fully electric. According to one embodiment, the airship 1 includes a power generation system based on flexible solar panels 40 disposed on the outer shell 11 of the airship 1, preferably on the upper surface 111 of the central portions 11A - 11C of the shell. Specifically, the airship 1 is fully energy self-sufficient and is designed to be able to fly continuously for several weeks. The airship 1 further includes an energy storage system necessary to ensure night flights without the need to lower the flight altitude. According to one embodiment, the energy storage system includes high energy density batteries such as Li-Po, Li-ION, Li-S.

[0039] According to one embodiment, the airship 1 includes a bay 70 for the payload and a bay 80 for avionics and the battery described above. The bays 70, 80 are preferably arranged on the outer shell 11, and more preferably on the central portions 11A - 11C of the central shell 10. According to one embodiment, the airship 1 includes control surfaces 203A, 203B positioned on the wings 20A, 20B. By changing the sizes of the control surfaces 203A, 203B and the wings 20A, 20B, the percentage of how much each aerostatic thrust and aerodynamic thrust contribute to the total thrust required to balance the weight can be adjusted. Based on the payload, flight altitude, and assigned cruise speed, various different optimal solutions can be obtained.

[0040] According to one embodiment, the airship 1 does not have a gas bladder for compensating for gas expansion associated with altitude changes. This solution makes it possible to significantly reduce the weight and size of the airship 1 compared to classical well-known techniques based on the form of the airship type. Instead, according to one embodiment, there will be only a small gas bladder mainly to absorb pressure fluctuations caused by temperature deviation mainly due to day-night alternation.

[0041] Referring to FIGS. 7A-7C and FIGS. 8A-8C, according to one embodiment, the geometric shape of the airship 1 changes in a predetermined manner from an initial minimum volume takeoff shape (FIGS. 7A and 8A) to a hybrid aerodynamic shape (FIGS. 7C and 8C). The hybrid aerodynamic shape corresponds to the shape of the airship 1 shown in FIG. 1. As shown in the initial takeoff configuration in FIG. 7A, the airship 1 is vertically disposed on the ground B1, and only the front portion of the central body 10 of the airship 1 is inflated. In such a configuration, the wings 20A, 20B are fully folded. According to one embodiment, the airship 1 is also configured to assume the intermediate configurations shown in FIGS. 7B and 8B. In the intermediate configuration, the central body 10 and the wings 20A, 20B are partially inflated. According to one embodiment, the airship 1 assumes the intermediate configuration (FIGS. 7B and 8B) at an altitude of about 8000 m and assumes the hybrid aerodynamic configuration (FIGS. 7C and 8C) at an altitude of about 15000 m.

[0042] Referring now to FIG. 6, the hybrid stratospheric airship according to the second embodiment is generally indicated by reference numeral 1'. The airship 1' differs from the airship 1' shown in FIGS. 1-5 only in that its wings have a slightly different structure from the wings 20A, 20B of the airship 1'. All that has been described in connection with the airship 1 is applicable to the airship 1' as being compatible. Therefore, for the sake of brevity, the airship 1' will not be described in detail again. It should be particularly noted that FIG. 6 does not show some components of the airship 1'. For example, only the first wing 20A' of the airship 1' is shown in FIG. 6. Here, the corresponding part of the outer shell 11 has been removed to show the internal structure of the wing 20A'. However, it is clear that the airship 1' has two wings with a symmetrical structure with respect to the central body 10, similar to the case of the airship 1 described above. Therefore, the description to be described later in connection with the wing 20A' can be applied to the second wing (not shown) of the airship 1' with necessary modifications. Specifically, the first difference between the wing 20A' and the wing 20A of the airship 1 is that the wing 20A' has a first secondary spar 23A disposed at the leading edge of the wing 20A'. The second difference between the wing 20A' and the wing 20A is that the wing 20A' includes at least one strut 26A-29A interposed between the first secondary spar 23A and the main spar 12 of the airship 1'. Providing the secondary spar 23A at the leading edge of the wing 20A and providing at least one strut 26A-29A is advantageous because it makes it possible to maintain the profile shape of the wing 20A and prevent or significantly reduce the deformation of the leading edge as the internal pressure increases within the wing 20A. According to one embodiment, the wing 20A' includes a plurality of struts 26A-29A, preferably four struts 26A-29A. These struts are interposed between the first secondary spar 23A and the main spar 12 of the airship. According to one embodiment, the wing 20A' also includes a third secondary spar 25A in addition to the first and second secondary spars 23A, 24A. The third secondary spar 25A is interposed between the first secondary spar 23A and the main spar 12.In such cases, at least one of struts 26A - 29A extends partially between the first spar 23A and the third spar 25A, and also extends partially between the third spar 25A and the main spar 12. According to one embodiment, at least one of struts 26A - 29A is an inflatable strut. According to one embodiment, at least one of struts 26A - 29A is in fluid communication with the first secondary spar 23A and the main spar 12 of the airship 1'. According to one embodiment, at least one of struts 26A - 29A is in fluid communication with the third secondary spar 25A. However, it should be further noted that by slightly modifying the structure of the wings 20A, 20B of the airship 1 shown in FIGS. 1 - 5, one or more struts similar to struts 26A - 29A intervening between the first secondary spar 23A and at least one main spar 12 of the airship 1 may be provided within the wings 20A, 20B of the airship 1.

[0043] The structure of the hybrid stratospheric airships 1, 1' has been described, and here, as an example, the operating modes of such airships 1, 1' will be briefly described.

[0044] At takeoff, the airships 1, 1’ have an ellipsoidal shape and their weight is balanced solely by the aerostatic thrust. The aerostatic thrust also provides the free lift necessary for ascent. Thus, takeoff is carried out vertically without the need for aerodynamic thrust. Therefore, in the takeoff phase, which is not controlled by selection or is at most partially controlled, an initial phase occurs in which the gas expands until it completely fills the available volume within the central body and the wings. As the system ascends, the shape continuously changes from an ellipsoid to a hybrid load-bearing design shape (Figure 1). This phase ends at a predetermined altitude (e.g., 8000 - 12000 m based on the size of the airships 1, 1’). At this altitude, the airships 1, 1’ having acquired this shape can generate aerodynamic thrust. Once the aerodynamic shape is acquired, the second part of the ascent phase begins. At this point, this second part utilizes both the aerostatic thrust and the aerodynamic thrust generated by the forward movement of the airships 1, 1’ relative to the air at a predetermined speed. In this phase, the expansion of the gas is not structurally contained and the excess gas is released. The lift balances the part of the weight that is no longer supported aerostatically.

[0045] When the desired flight altitude (e.g., 17,000 - 21,000 meters) is reached, the airships 1, 1’ start their mission. Two flight modes are possible depending on the wind strength. The first mode is stationary with respect to the Earth for the area and is possible when the wind is 5 - 18 m / s. In this mode, the airships 1, 1’ use the relative wind to generate lift while remaining stationary with respect to the ground. For lower strength winds, the platform has to move on an orbit. These orbits are circular or linear and enable the generation of the lift necessary to complement the aerostatic thrust. Obviously, the aerodynamic thrust can also compensate for the aerostatic thrust losses related to gas leakage. Aerostatic thrust losses are inevitable specifically in a helium filling system intended to remain in flight for a long time. During the descent phase, the loss of internal pressure due to altitude is compensated by continuously introducing air into the shell in a controlled manner in order to maintain the required shape useful for supporting and controlling the platform during its descent to the landing surface. At this stage, the system is also assisted in control by an electric motor. The electric motor utilizes the energy storage stored in the battery.

[0046] Therefore, based on the above, it can be understood how the hybrid stratospheric airship according to this specification can achieve the above object.

[0047] Without prejudice to the principles of the invention, the embodiments and structural details may be widely varied with respect to the above description disclosed by non-limiting examples without departing from the scope of the invention as defined in the appended claims. According to aspect (1), a hybrid stratospheric airship (1; 1') configured for use in a state where aerostatic force and aerodynamic force are combined and optimized, comprising: - an inflatable central body (10); - a first inflatable wing and a second inflatable wing (20A, 20B) extending from the central body (10) and protruding laterally from two opposite sides of the central body (10), each wing (20A, 20B) having a proximal portion (21A, 21B) of the central body (10), a distal end portion (22A, 22B) of the central body (10), a leading edge (201A, 201B), and a trailing edge (202A, 202B); - an outer shell (11) having a central shell portion (11A-11C) coupled to the central body (10) and a first side shell portion and a second side shell portion (11D, 11E) coupled to the first wing and the second wing (20A, 20B); - at least one main spar (12) structurally supporting the first wing and the second wing (20A, 20B), intersecting the central body (10), and extending laterally with respect to the central body (10), the at least one main spar (12) being a linear spar interposed between the leading edge (201A, 201B) and the trailing edge (201A, 201B) of the first wing and the second wing and connected to the distal end portion (22A, 22B) of the first wing and the second wing; A hybrid stratospheric airship (1; 1') comprising the above. According to aspect (2), the at least one main spar (12) is an inflatable spar. According to aspect (3), the at least one main spar (12) is a spar made of a composite material. According to aspect (4), the first wing and the second wing (20A, 20B) comprise at least one secondary spar (23A, 24A, 23B, 24B) disposed within the wing and having a cross-section smaller than the cross-section of the main spar (12). According to aspect (5), the at least one secondary spar (23A, 24A, 23B, 24B) comprises a first secondary spar and a second secondary spar (23A, 24A, 23B, 24B), and the first secondary spar and the second secondary spar are arranged to approach each other in a direction from the proximal portion (21A, 21B) to the distal end portion (22A, 22B) of each said wing (20A, 20B), and the at least one lateral spar (12) is interposed between the first secondary spar (23A, 24A) and the second secondary spar (23B, 24B). According to aspect (6), the at least one secondary spar (23A, 24A, 23B, 24B) is an inflatable spar. According to aspect (7), the at least one secondary spar (23A) is arranged at the leading edge (201A, 201B) of the first wing and the second wing (20A). According to aspect (8), it comprises at least one strut (26A - 29A) interposed between the at least one secondary spar (23A) and the at least one main spar (12). According to aspect (9), the at least one strut (26A - 29A) is an inflatable strut. According to aspect (10), the central body (10), and the first wing and the second wing (20A, 20B) are separate from each other and define a central body chamber (60), a first wing chamber (60A), and a second wing chamber (60B) that can be inflated independently. According to aspect (11), under the operating conditions and mission altitude of the airship (1; 1'), the central body (10), and the first wing and the second wing (20A, 20B) are inflated at a pressure lower than the pressure at which the at least one main spar (12) inflates. According to aspect (12), the first wing and the second wing (20A, 20B) are each intersected by the at least one main spar (12) and comprise at least one planar wing rib (31A - 33A, 31B - 33B) made of fabric, and the first side shell part and the second side shell part (11D, 11E) each comprise an upper surface (111D, 111E) and an opposite lower surface (112D, 112E), and the at least one wing rib (31A - 33A, 31B - 33B) joins the upper surface (111D, 111E) and the lower surface (112D, 112E) of each said side shell part (11D, 11E) so as to enable a preset aerodynamic profile of the wings (20A, 20B) to be obtained when pressurized. According to aspect (13), the central body (10) comprises at least one central body rib (13) intersected by the at least one main spar (12), the rib (13) of the central body (13) is of a planar shape and made of fabric, the central shell part (11A - 11C) comprises an upper surface (111) and an opposite lower surface (112), and the at least one central body rib (13) joins the upper surface (111) and the lower surface (112) of the central shell part (11A - 11C) so as to enable a preset aerodynamic profile of the central body (10) to be obtained when pressurized. According to aspect (14), the at least one main spar (12) is connected to the at least one central body rib (13) and to the at least one wing rib (31A - 33A, 31B - 33B) of the first wing and the second wing (20A, 20B) via rib connection parts (13A, 311A, 321A, 331A), the at least one main spar (12) is further connected to the central shell part (11A - 11C) by central body connection parts (10A, 10B), the rib connection parts (13A, 311A, 321A, 331A) allow the passage of gas, and the central body connection parts (10A, 10B) enable not only a structural connection but also a pressurized sealing connection between the central shell part (11A - 11C) and the at least one main spar (12). 。 According to aspect (15), the central shell portion (11A - 11C) serves as the starting point from which the first wing and the second wing (20A, 20B) extend, and includes two half - shells (11A, 11B) having a semi - circular cross - section or a semi - elliptical cross - section, and at least one intermediate portion (11C) that joins the two half - shells (11A, 11B). According to aspect (16), a propulsion system (51, 52) is provided, which includes a rear - side propeller (51) disposed on the rear side of the central body (10) and a pair of front - side propellers (52) disposed on the front side of the central body (10) at two opposite side portions of the central body (10). The angle of the rear - side propeller (51) is adjustable about a vertical axis, and the angle of the front - side propeller (52) is adjustable about a horizontal axis. According to aspect (17), the geometric shape of the airship (1; 1') changes in a predetermined manner from an initial minimum - volume take - off shape to a hybrid and aerodynamic shape (1, 1').

Claims

1. A hybrid stratospheric airship (1; 1') configured for use in a state where aerostatic force and aerodynamic force are combined and optimized, - an inflatable central body (10), - first and second inflatable wings (20A, 20B) extending from the central body (10) and protruding laterally from two opposing sides of the central body (10), each wing (20A, 20B) having a proximal portion (21A, 21B) of the central body (10), a distal end portion (22A, 22B) of the central body (10), a leading edge (201A, 201B), and a trailing edge (202A, 202B), the first and second inflatable wings, - an outer shell (11) having a central shell portion (11A - 11C) coupled to the central body (10) and first and second lateral shell portions (11D, 11E) coupled to the first and second wings (20A, 20B), - at least one main spar (12) that structurally supports the first and second wings (20A, 20B), intersects the central body (10), and extends laterally with respect to the central body (10), the at least one main spar (12) being a linear spar intervening between the leading edges (201A, 201B) and trailing edges (202A, 202B) of the first and second wings and being connected to the distal end portions (22A, 22B) of the first and second wings, comprising, The first wing (20A) and the second wing (20B) are provided with first secondary spars (23A, 24A) and second secondary spars (23B, 24B) having a cross - section smaller than that of the cross - section of the main spar (12) and being arranged on both the leading edge (201A, 201B) side and the trailing edge (202A, 202B) side of the first wing (20A) and the second wing (20B), The first secondary spar (23A, 24A) extends between the distal end portion (22A) of the first wing (20A) and the outer surface of the central body (10), and is connected to the distal end portion (22A) of the first wing (20A) and the outer surface of the central body (10). The second secondary spar (23B, 24B) extends between the distal end portion (22B) of the second wing (20B) and the outer surface of the central body (10), and is connected to the distal end portion (22B) of the second wing (20B) and the outer surface of the central body (10). Hybrid stratospheric airship (1; 1').

2. The hybrid stratospheric airship (1; 1') according to claim 1, wherein the at least one main spar (12) is an inflatable spar.

3. The hybrid stratospheric airship (1; 1') according to claim 1, wherein the at least one main spar (12) is a spar made of a composite material.

4. The hybrid stratospheric airship (1; 1') according to claim 1, wherein the first secondary spar and the second secondary spar (23A, 24A, 23B, 24B) are arranged to approach each other in a direction from the proximal side portion (21A, 21B) to the distal end portion (22A, 22B) of each wing (20A, 20B).

5. The hybrid stratospheric airship (1; 1') according to claim 4, wherein the at least one secondary spar (23A, 24A, 23B, 24B) is an inflatable spar.

6. The hybrid stratospheric airship (1') according to claim 4 or claim 5, wherein the at least one secondary spar (23A) is arranged on the leading edges (201A, 201B) of the first wing and the second wing (20A).

7. The hybrid stratospheric airship (1') according to any one of claims 4 to 6, comprising at least one strut (26A - 29A) interposed between the at least one secondary spar (23A) and the at least one main spar (12).

8. The hybrid stratospheric airship (1') according to claim 7, wherein the at least one strut (26A - 29A) is an inflatable strut.

9. The hybrid stratospheric airship (1; 1') according to any one of claims 1 to 8, wherein the central body (10), and the first and second wings (20A, 20B) are separate from each other and can be inflated independently, defining a central body chamber (60), a first wing chamber (60A), and a second wing chamber (60B).

10. The hybrid stratospheric airship (1; 1') according to any one of claims 1 to 9, wherein under the operating conditions and mission altitude of the airship (1; 1'), the central body (10), and the first and second wings (20A, 20B) are inflated at a pressure lower than the pressure at which the at least one main spar (12) inflates.

11. The first and second wings (20A, 20B) are each intersected by the at least one main spar (12) and include at least one planar wing rib (31A - 33A, 31B - 33B) made of fabric, and the first and second lateral shell portions (11D, 11E) each have an upper surface (111D, 111E) and an opposite lower surface (112D, 112E). The at least one wing rib (31A - 33A, 31B - 33B) joins the upper surface (111D, 111E) and the lower surface (112D, 112E) of each of the lateral shell portions (11D, 11E) so as to enable a preset aerodynamic profile of the wings (20A, 20B) to be obtained when pressurized. The hybrid stratospheric airship (1; 1') according to any one of claims 1 to 10.

12. The central body (10) comprises at least one central body rib (13) intersected by the at least one main spar (12), the at least one central body rib (13) of the central body (10) being planar in shape and made of fabric, the central shell portion (11A-11C) comprising an upper surface (111) and an opposite lower surface (112), and the at least one central body rib (13) being configured to join the upper surface (111) and the lower surface (112) of the central shell portion (11A-11C) so as to enable a preset aerodynamic profile of the central body (10) to be obtained when pressurized. The hybrid stratospheric airship (1; 1') according to any one of claims 1 to 11.

13. The central body (10) comprises at least one central body rib (13) intersected by the at least one main spar (12), the at least one central body rib (13) of the central body (10) being planar in shape and made of fabric, the central shell portion (11A-11C) comprising an upper surface (111) and an opposite lower surface (112), and the at least one central body rib (13) being configured to join the upper surface (111) and the lower surface (112) of the central shell portion (11A-11C) so as to enable a preset aerodynamic profile of the central body (10) to be obtained when pressurized, The at least one main spar (12) is connected to the at least one central body rib (13) and to the at least one wing rib (31A - 33A, 31B - 33B) of the first and second wings (20A, 20B) via rib connection portions (13A, 311A, 321A, 331A), and the at least one main spar (12) is further connected to the central shell portion (11A - 11C) by central body connection portions (10A, 10B), the rib connection portions (13A, 311A, 321A, 331A) allowing passage of gas, and the central body connection portions (10A, 10B) enabling not only a structural connection but also a pressure - sealing connection between the central shell portion (11A - 11C) and the at least one main spar (12), the hybrid stratospheric airship (1; 1') according to claim 11.

14. The central shell portion (11A - 11C) serves as the origin from which the first and second wings (20A, 20B) extend and comprises two half - shells (11A, 11B) having a semi - circular or semi - elliptical cross - section and at least one intermediate portion (11C) joining the two half - shells (11A, 11B), the hybrid stratospheric airship (1; 1') according to any one of claims 1 to 13.

15. A propulsion system (51, 52) including a rear - side propeller (51) disposed on the rear side of the central body (10) and a pair of front - side propellers (52) disposed on the front side of the central body (10) at two opposite sides of the central body (10), the angle of the rear - side propeller (51) being adjustable about a vertical axis and the angle of the front - side propeller (52) being adjustable about a horizontal axis, the hybrid stratospheric airship (1; 1') according to any one of claims 1 to 14.

16. The geometric shape of the airship (1; 1') changes in a predetermined manner from an initial minimum - volume take - off shape to a hybrid and aerodynamic shape (1, 1'), the hybrid stratospheric airship (1; 1') according to any one of claims 1 to 15.

Images