DE112020004905T5 - STRATOSPHERE AIRSHIP WITH LARGE RIGID-AND-FLEXIBLE INTEGRATED STRUCTURE - Google Patents

Abstract

The present invention discloses a stratospheric airship having a large rigid-flexible integrated structure that includes an outer pod and a keel. The outer capsule covers the keel. The keel consists of a central axle truss, stiffening rings and a string secondary keel. The central axle truss extends along the longitudinal direction of the stratospheric airship. The plurality of stiffening rings are arranged in parallel and coaxially along the longitudinal direction. The centers of the stiffening rings are connected to the central axle framework. The string secondary keel is connected to outer rings of adjacent stiffening rings in a head section of the stratospheric airship. The outer shape of the outer capsule in the present invention is substantially unaffected by environmental changes, pressure and buoyancy can be subjected to decoupling control, and the center of mass is stable. In addition, an environmental control system, a propulsion system, a power system and a return buffer system are optimized. The stratospheric airship of the present invention has stable attitude, low power consumption, flexible and controllable take-off and return flight, strong long-term flight capacity, and wide industrial application potential.

Description

field of invention

The present invention relates to the technical field of aerostats, in particular to a stratospheric airship with a large rigid-flexible integrated structure.

Description of the prior art

The stratosphere is also called the isothermal layer. The stratosphere is the second layer of the Earth's atmosphere from bottom to top, above the troposphere and below the mesosphere. The stratosphere is about 10-50 kilometers above sea level and has an average atmospheric density of about 88.9 g/m ³ . It is characterized by being warm on top and cold on the bottom. The atmosphere in the stratosphere flows horizontally and rarely rolls up and down, and the airflow is relatively stable, so most airplanes fly in the stratosphere.

Stratospheric airships are low dynamic aircraft. Stratospheric airships have a wide range of military and civilian applications because they take advantage of static lift combined with propulsion and integrated environmental, flight control, power and other subsystems, and can remain in an adjacent space of the stratosphere for long periods of time. At present, the stratospheric airship is a national strategic space resource development platform and an important field of research and development. However, in the world, stratospheric airship control technology is still at the stage of key technology research, bottleneck technology breakthrough and integration technology verification, and there is still no mature, industrial-grade application product.

The air in the stratosphere is thin, air density is only about 1/14 that of sea level, and buoyancy is extremely low. In order to reduce weight, light-weight materials are generally used in the manufacture of soft airships at home and abroad. However, the alternation of day and night in the stratosphere changes the airship's temperature, causing changes in lift, pressure, and center of mass, making the airship's state of hover unstable. In addition, due to the thin gas, it is difficult to compress the air, so a special low-flow blower and high-pressure head is required. However, the special blower has high energy consumption, low efficiency. but high cost. At the same time, thin air requires a large diameter, low speed and heavy weight of an altitude propeller, which makes the thrust efficiency low. Also, more energy is consumed to maintain the health of an airship system, which also increases the overall weight of the airship system. Therefore, the overall weight of the stratospheric airship system is not exactly light. In addition, the airship system has high requirements for long-term stay in the air, maintaining altitude and maintaining buoyancy. However, current technology does not yet provide an effective solution. The scientific and technical professionals in this field at home and abroad is still conducting various explorations.

The Chinese patent applications CN108706091A "BIONIC STRATOSPHERE AIRSHIP" and CN108725734A "METHODS FOR THE COORDINATED CONTROL OF LIFT AND PRESSURE OF A STRATOSPHERE AIRSHIP" propose a new airship configuration and layout based on the form and principle of a Portuguese galley, in which a heat-adapted airbag is filled with a gas-liquid reversibly controllable working medium, the working medium by a thermodynamic cycle device is converted between liquid and gaseous states and long-term control of pressure and buoyancy is realized by a method of coordinated control of pressure and buoyancy. However, the change in the state of the working medium and the change in the total volume of the airship make it difficult to stabilize the center of mass.

In the Chinese patent CN106394855A “HYDROGEN ADJUSTER STRATOSPHERE AIRSHIP” is supplemented by the offloading of hydrogen storage ballast, the loss of helium to maintain lift and pressure, and realize the cycle by combining the hydrogen-oxygen hydroelectric reaction of a fuel cell. However, there are many technical difficulties and the use of hydrogen in airships is currently prohibited.

In Chinese patent ZL201110012621.8 “AIRSHIP WITH AMMONIA ASSISTANT AIR CUSHION AND LIFT CONTROL METHOD THEREOF”, the ternary air cushion of the ammonia auxiliary air cushion is used, and the control of pressure and buoyancy are done by the phase change between gas and liquid. Also the influence of the ammonia working medium on the airship's center of buoyancy and center of mass, as well as the problem of its control were not effectively solved.

The Chinese patent CN201521080600.X "LARGE AIRSHIP RIGID STRUCTURE SYSTEM" proposes an airship with a rigid structural system comprising a prestressed structural system and a flexible outer capsule structure, the prestressed structural system consisting of a central axis, prestressed stiffening rings and longitudinal tie rods. However, the prestressed stiffening rings of this structure have low rigidity and low stability. The long central axis runs through the capsule of the airship from head to tail, crossing the central tubes of a plurality of prestressed stiffening rings, resulting in the axis being subjected to a larger bending force, easily losing stability, having a low load capacity, is cumbersome to install and difficult to provide an overall feasible preload; and it is difficult for the flexible outer capsule structure and the prestressed structure system to bear force synergistically, so the overall efficiency of the structure is low.

The Chinese patent application CN108725741A "RIGID STRATOSPHERIC AIRSHIP WITH NEW STRUCTURE" provides a rigid stratospheric airship in which a plurality of outer capsule frames consisting of stiffening rings and rods are arranged outside the outer capsule, inner capsules are divided into cabin inner capsules along the axial Direction of the airship are sequentially arranged to store helium, and air is stored in capsules between the outer capsule and the inner capsules. This system is called a rigid airship and can withstand negative pressure. However, this system is still essentially an integrated soft structure airship concept, and it is only a partially reinforced structural system, i.e. the entire airship structural system still requires the outer capsule to be inflated with positive pressure to maintain the shape and rigidity of the obtain airship.

In the Chinese patent application CN201910275705.7 "LARGE AIRSHIP WITH SEMI-RIGID STRUCTURES" is used a structure for integrated and synergistic force absorption by an integral keel of a tension-compression self-balancing system and a prestressed capsule, and the prestressed capsule has the characteristics of an overall compliance at a zero pressure and an overall stiffness and a high load capacity at a low pressure. Although the capsule is generally under non-negative pressure, which can be close to zero, some capsules (with a low drag spherical or aerofoil head) cannot maintain their shape and rigidity under low or zero pressure. At the same time, the present invention only aims at the structural system of the airship and does not concern the improvement of the general properties of the airship.

That is, the survivability of the prior art stratospheric airship during long-term airborne presence is not yet well solved. This has become an obstacle to the industrial application of stratospheric airships.

Therefore, the existing technologies still need to be further improved and expanded.

Summary of the Invention

In view of the above shortcomings of the prior art, the technical task of the present invention is to improve the survivability of a stratospheric airship during long-term airborne presence with flexible control and high feasibility.

In order to achieve the above purpose, the present invention provides a large rigid-flexible integrated structure stratospheric airship comprising an outer capsule and a keel, the outer capsule covering the keel; the keel comprises a central axle truss, stiffening rings and a string secondary keel; the central axle truss extends along the longitudinal direction of the stratospheric airship; the plurality of stiffening rings are arranged coaxially and the stiffening rings are arranged coaxially with the axle framework; the centers of the stiffening rings are connected to the central axle framework; and the string secondary keel is connected to outer rings of adjacent ones of the stiffening rings in a head region of the stratospheric airship.

Furthermore, the outer capsule consists of a flexible film material with low air permeability.

In addition, the outer capsule is filled with air.

Further, the string secondary keel comprises an outer string tie rod and an inner string tie rod, the outer string tie rod and the inner string tie rod having a hollow belly forming space and the outer string tension rod is in contact with the inner surface of the outer capsule.

Furthermore, the string secondary keel comprises support rods, the support rods being arranged at a belly part of the string secondary keel and the support rods connecting the outer string tie rod and the inner string tie rod.

Furthermore, the outer and inner string pull rods are arranged symmetrically.

Furthermore, a plurality of support rods are arranged parallel to each other.

Furthermore, there are no less than three support rods.

Further, the keel comprises longitudinal tie rods, and the longitudinal tie rods are connected to the outer rings of the adjacent stiffening rings, the longitudinal tie rods being located in the head area of the stratospheric airship and the two ends of the longitudinal tie rods being connected in a respective associated manner to the head end and the tail end of the string secondary keel are.

Furthermore, the outer ring comprises two sub-rings and a first truss; the first truss is distributed along the inner circumference of the outer ring; the two subrings are connected and widened by the first truss; the first truss comprises an inner chord node or strut node (in short: inner chord node) and an outer chord node or strut node (in short: outer chord node); the inner chord node is connected to the central axle truss by a radial tie rod; the outer chord-knot connects the first truss and the two sub-rings; and the string secondary keel and the outer ring are connected by the outer chord knot.

Further, the shape of a unit of the first truss is a triangle, and the triangle includes two outer chord nodes and one inner chord node.

Further, the longitudinal tie rods connect the outer tendon nodes at the same location on two adjacent strut rings.

Furthermore, the inner tendon node is connected to the two ends of the hub shaft of the stiffening ring via two radial tie rods.

Further, the central axle truss includes a plurality of sets of boat-shaped second trusses, and the second trusses connect the adjacent stiffening rings; and the shape of an inner unit of the second truss includes a triangle.

Furthermore, the stratospheric airship comprises inner capsules, the inner capsules being arranged inside the outer capsule and the inner capsules being filled with a first gas, the first gas having a lower density than air.

Furthermore, the inner capsules surround the central axle framework in a ring shape.

Furthermore, a large number of inner capsules are provided.

Furthermore, the inner capsules are made of ultra-light films with low strength.

Furthermore, the first gas contains helium.

The inner capsule is also equipped with a helium valve on the top of the outer capsule.

The stratospheric airship further includes an environmental control system, wherein the environmental control system is configured to control air pressure within the outer pod.

Further, the environmental control system is configured to maintain the air pressure within the outer shell between a set under pressure limit and a set over pressure limit.

Further, the negative pressure limit is set not to exceed a negative pressure value corresponding to the compression limit of the keel, and the positive pressure limit is set not to exceed a positive pressure value corresponding to the outer shell tensile limit.

A differential pressure gauge is also provided, and the differential pressure gauge is configured to determine the difference between the internal and external pressures of a contact area between the outer shell and the keel.

The environmental control system further includes an air valve; the air valve is located at the bottom of the outer shell; and the air valve is configured to allow the outer shell to be vented to the outside in a positive pressure condition.

Further, the environmental control system includes a fan; the blower is installed on the outer capsule; and the blower is configured to inflate the outer shell in a negative pressure state.

Further, the fan includes a high-altitude fan and/or a low-altitude fan.

Further, the environmental control system selects the high-altitude fan and/or the low-altitude fan according to the hovering altitude of the stratospheric airship.

Furthermore, an air outlet of the blower is provided with a non-return valve.

The stratospheric airship further includes an air bag, the air bag being configured to be supported on the base of the stratospheric airship.

Further, the number of airbags is set to four, and the lines connecting the positions of the four airbags form a rectangle, and the rectangle is located at the lower belly part of the stratospheric airship.

Further, the airbags are configured to be stored and folded during the cruising phase of the stratospheric airship and inflated to a design pressure upon return and landing at a specified altitude above the ground.

Further, the specified height is 1 km.

Further, the stratospheric airship comprises a battery, wherein the battery is housed in a nacelle and the nacelle is located under the stratospheric airship; and the battery is electrically connected to a solar energy collection panel.

Furthermore, the stratospheric airship comprises a propulsion system, wherein the propulsion system comprises a rear engine and/or side engines; the tail engine is attached to the outer surface of the outer pod in a tail portion of the stratospheric airship; the side engines are fixed at a head and/or middle position of the stratospheric airship, and the side engines are symmetrically distributed on the left and right sides with respect to the axial direction of the central axle truss; and the side engines and/or the tail engine comprise/comprises high-altitude propellers driven by an high-altitude motor.

Furthermore, the stratospheric airship comprises two pairs of tail units, the two pairs of tail units being arranged in a rear area of the stratospheric airship and having an X-shaped arrangement.

Furthermore, the tail units are inflatable tail units.

1. 1. Der String-Sekundärkiel kann die Verformung der Außenkapsel in einem Bereich mit einer relativ großen Krümmung begrenzen, die Hemmung des starren Kiels auf die Verformung der flexiblen Außenkapsel verstärken und die Volumenänderung der Außenkapsel klein machen, wodurch die Auftriebskontrolle und die Druckkontrolle des Luftschiffs entkoppelt, der Kontrollprozess vereinfacht und der Massenschwerpunkt des Luftschiffs stabilisiert wird.
2. 2. Das ersten Fachwerke der Versteifungsringe bilden ein radiales Zug-Druck-Selbstausgleichssystem, und die Versteifungsringe und die zweiten Fachwerke bilden ein axiales Selbstausgleichssystem. Das Selbstausgleichssystem ist vorteilhaft, um den Gesamtnutzungsumfang des Kiels zu reduzieren und die Leistungsanforderungen an die Materialien zu senken, wodurch das Gewicht des Kiels und das Gesamtgewicht des Luftschiffs reduziert werden.
3. 3. Die umlaufende Innenkapselstruktur ist vorteilhaft, um das Links-Rechts-Gleichgewicht des Luftschiffs zu erhalten, wodurch die Stabilität des Massenschwerpunkts gewahrt bleibt und ein Auf- und Abschwanken des Luftschiffs und damit ein Umkippen verhindert wird.
4. 4. Das Umgebungskontrollsystem, das Antriebssystem, das Energiesystem und das Puffersystem für den Rückflug sind optimiert und zeichnen sich durch eine einfache Steuerung, eine stabile Fluglage, einen geringen Energieverbrauch und eine ausgezeichnete Kontrollierbarkeit des Starts und der Rückkehr aus, wodurch die Grundlage für die industrielle Anwendung von Luftschiffen in der Stratosphäre geschaffen wird.

Compared to the prior art, the present application has at least the following advantageous technical effects:

1. 1. The string secondary keel can limit the deformation of the outer capsule in an area with a relatively large curvature, strengthen the inhibition of the rigid keel on the deformation of the flexible outer capsule, and make the volume change of the outer capsule small, thereby decoupling the airship's buoyancy control and pressure control , simplifying the control process and stabilizing the airship's center of mass.
2. 2. The first truss of the stiffening rings form a radial tension-compression self-balancing system, and the stiffening rings and the second trusses form an axial self-balancing system. The self-balancing system is advantageous in reducing the overall usage scope of the keel and lowering the performance requirements of the materials, thereby reducing the weight of the keel and the overall weight of the airship.
3. 3. The all-round inner capsule structure is advantageous to maintain the left-right balance of the airship, which maintains the stability of the center of mass and prevents the airship from pitching up and down and thus overturning.
4. 4. The environmental control system, propulsion system, power system and return flight buffer system are optimized, featuring simple control, stable flight attitude, low power consumption and excellent controllability of take-off and return, laying the foundation for the industrial Application of airships in the stratosphere is created.

The concept, specific structures and resulting technical effects of the present invention are explained in detail below in conjunction with the accompanying drawings so that the purpose, features and effects of the present invention can be fully understood.

character list

• 1 12 is a cross-sectional view of a structure system in the up-down direction according to a preferred embodiment a stratospheric airship of the present invention;
• 2 Figure 12 is an isometric view of a keel structure in accordance with a preferred embodiment of a stratospheric airship of the present invention;
• 3 Figure 12 is a schematic view of a shroud in accordance with a preferred embodiment of a stratospheric airship of the present invention;
• 4 Figure 12 is a cross-sectional view of a string secondary keel in accordance with a preferred embodiment of a stratospheric airship of the present invention;
• 5 Figure 12 is a layout diagram of an environmental control system in accordance with a preferred embodiment of a stratospheric airship of the present invention; and
• 6 12 is a layout diagram of a propulsion system according to a preferred embodiment of a stratospheric airship of the present invention.

Reference List

101

keel;

102

string secondary keel;

103

outer capsule;

104

inner capsule;

105

empennage;

106

Gondola;

107

air cushions;

10101

stiffening ring;

10102

central axle framework;

10103

longitudinal pull rod;

1010101

first truss;

1010102

hub shaft;

1010103

radial pull rod;

1010104

outer ring;

10201

- outer string pull rod;

10202

inner string pull rod;

10203

support rod;

201

large-altitude blower;

202

low-altitude fan;

203

air valve;

204

helium valve;

205

differential pressure gauge;

206

environmental controller;

301

side engine;

302

rear engine; and

401

Solar Energy Collection Plate.

Detailed Description of Preferred Embodiments

A plurality of preferred embodiments of the present invention are described below with reference to the accompanying drawings so that the technical content thereof may be more clearly and easily understood. The present invention can be embodied in many different embodiments, and the scope of the present invention is not limited to the embodiments mentioned herein.

In the drawings, like reference numbers indicate components having the same structure, and like reference numbers indicate assemblies having similar structures or functions. The size and thickness of each assembly shown in the drawings are shown arbitrarily, and the size and thickness of each assembly are not limited in the present application. In order to clarify the representation, the thickness of the component is correspondingly exaggerated in some places in the drawings.

Embodiment I

As the shape of an airship changes greatly, not only lift but also pressure changes drastically, which can cause the airship's center of mass to become unstable, reducing hover control accuracy and making the control system complicated. An airship whose shape remains unchanged has essentially unchanged buoyancy, so that buoyancy and pressure control can be decoupled. On this basis, by changing the gravity of the airship and the rate of change of gravity, the ascent and descent and the speed of ascent and descent of the airship can be controlled.

In order to control the deformation of the airship, a stratospheric airship with a large rigid-flexible integrated structure is disclosed in this embodiment.

As in 1 As shown, the stratospheric airship includes an outer pod 103 and a keel 101. The outer pod 103 covers the keel 101, and the keel 101 includes a central axle truss 10102, stiffening rings 10101, and a string secondary keel 102. The central axle truss 10102 extends along the longitudinal direction of the stratospheric airship; a plurality of stiffening rings 10101 are coaxial, the stiffening rings 10101 are arranged coaxially with the central axle framework, and the centers of the stiffening rings 10101 are connected to the central axle framework 10102. The string secondary keel 102 is arranged in a head region of the stratospheric airship, and the string secondary keel 102 is connected to the outer rings 1010104 of adjacent stiffening rings 10101 .

In practice, the volume of the stratospheric airship is relatively large; accordingly, the surface of the outer capsule 103 is relatively large. According to physical principles, the weight of an object is positively related to its thickness and density if the surface area is constant. In order to control the weight of the stratospheric airship, the outer capsule 103 is preferably made of a flexible sheet material with low air permeability, taking into account the requirements of low overall weight, prevention of air leakage and high material strength. Preferably, the outer capsule 103 is made of a thin sheet material that lets through only 0.5 liters per square meter in 24 hours, has a high specific strength, is lightweight, and has high strength. It should be noted that the contained gas of the outer capsule 103 is normally air.

In practice, airships in the stratosphere usually become teardrop-shaped for aerodynamic reasons, or, as in 1 shown projectile-like in construction, i.e. spherical at the head, cylindrical in the middle and cone-shaped at the stern.

Under the same conditions of tension and compression, the local stress on an outer surface of greater curvature (such as a low drag spherical or streamlined head) increases significantly. That is, under the same tension and compression conditions, the local deformation of the head portion of the outer capsule 103 is larger. Although adding a sufficient number of stiffening rings 10101 in the head area can solve the above problem, it results in a significant increase in the weight of the airship.

In order to account for the weight problem of the airship and to optimize the local deformation, the tension structure of the head area of the stratospheric airship is optimized by the arrangement of a string secondary keel 102 in this embodiment. The stiffening rings 10101 are exoskeletons in the longitudinal direction of the stratospheric airship; and between adjacent stiffening rings 10101 in the head area, the placement of the string secondary keel 102 further meshes the area of greater curvature and increases the force support points, thereby improving the problem of local deformation.

Preferably, as in 4 shown, the string secondary keel 102 comprises an outer string tension rod 10201 and an inner string tension rod 10202, the outer string tension rod 10201 and the inner string tension rod 10202 forming a cavity and the outer string tension rod 10201 in contact with the inner surface of the outer capsule 103. The string secondary keel 102 is made of a rigid material and therefore has a certain strength. Under external tension or compression, the string secondary keel 102 can only be stretched or shortened to a limited extent along the longitudinal direction, thereby limiting the deformation of the outer shell 103 in this area.

In order to improve the tension and compression resistance of a large range of curvature, the string secondary keel 102 preferably also comprises support rods 10203; and the support rods are arranged at a belly part of the string secondary keel 102 to connect the outer string tie rod 10201 and the inner string tie rod 10202 . Preferably, the support rods 10203 are perpendicular to the axis of the cavity of the string secondary keel 102 . By increasing the number of support rods 10203, the tensile and compressive load-bearing capacity of the string secondary keel 102 can be further increased. In order to ensure the same force characteristics of the plurality of support rods 10203, the plurality of support rods 10203 should be parallel to each other.

In addition, the outer string pull rod 10201 and the inner string pull rod 10202 are preferably distributed symmetrically along the axis of the cavity cavity of the string secondary keel 102 to ensure that the outer string pull rod 10201 and the inner string pull rod 10202 are the same Force obtained so that the outer string pull rod 10201 and the inner pull rod 10202 have the same amount of deformation.

Normally, considering the segment length of the string secondary keel 102, the number of supporting rods 10203 should be at least 3 parallel to each other to ensure that the inner string tie rod 10202 and the outer string tie rod 10201 maintain the arched shape even under high tension or compression be able.

It should be noted that the string secondary keel 102 may consist of an outer string tie rod 10201 and an inner string tie rod 10202 to form a fish belly shaped structure with a certain radius; it may also consist of a plurality of outer string tie rods 10201 and a plurality of inner string tie rods 10202 to form a hollow-bellied structure in sections, as in FIG 4 shown.

It should also be noted that 4 shows a unitary structure of the string secondary keel 102. In practical applications, as in 2 As shown, there are a plurality of string secondary keels 102 approximately perpendicular to a plane of the connected stiffening rings 10101 and distributed circumferentially. In different areas separated by adjacent stiffening rings 10101 in the longitudinal direction of the stratospheric airship, the distribution density of the string secondary keels 102 can be different, and the radii of the hollow abdominal spaces of the string secondary keels 102 can also be different. In particular, in a region with a larger curvature, the string secondary keels 102 can be more densely distributed between adjacent stiffening rings 10101, and the radian of the abdominal cavity will be larger.

In order to further limit the overall deflection of the cylindrical midsection stratospheric airship, the keel 101 may preferably, as shown in FIG 2 shown may also be provided with a longitudinal pull rod 10103; and longitudinal tie rod 10103 connects outer rings 1010104 of adjacent stiffening rings. Similar to the string secondary keels 102, there are preferably a plurality of longitudinal tie rods 10103 perpendicular to the associated stiffening rings 10101 and distributed circumferentially.

For the head section of the stratospheric airship, there are both longitudinal tie rods 10103 and string secondary keels 102. In this case, to ensure that the force on the head is mainly borne by the string secondary keel 102, two ends of the longitudinal tie rod 10103 are preferably connected to the front and aft end of the string secondary keel 102 connected. That is, the longitudinal tie rod 10103 is sandwiched between the outer string tie rod 10201 and the inner string tie rod 10202, thereby ensuring the structural strength of the stratospheric airship. More preferably, the longitudinal pull rod 10103 in the head area of the stratospheric airship can be processed into a whole with the strand secondary keel 102 . Preferably, the longitudinal tie rods 10103 form true shafts of the hollow bulbous structure of the string secondary keel 102 and are also perpendicular to the support rods 10203 to form a structure.

Longitudinal tie rods 10103 and string secondary keels 102 optimize the outer support structure of keel 101 to more accurately form an outer skeleton of the stratospheric airship carrying outer capsule 103.

3 Figure 10 shows a preferred embodiment structure of the stiffening ring 10101 comprising an outer ring 1010104, radial tie rods 1010103 and a hub shank 1010102; the outer ring 1010104 is located on the outer periphery of the stiffening ring 10101, and the outer ring 1010104 is configured to support the outer shell 103 directly; the hub shaft 1010102 is located in the center of the stiffening ring 10101 and is connected to the central axle framework 10102; and the outer ring 1010104 is connected to the hub shaft 1010102 by radial tie rods 1010103.

In order to optimize the mechanical properties of the keel 101, the stiffening ring 10101 is preferably designed as a radial tension-compression self-balancing system. Specifically, the outer ring 1010104 includes a first truss 1010101 and two sub-rings; the first truss 1010101 is evenly distributed along the inner circumference of the outer ring 1010104 to connect and support the two sub-rings; and the two sub-rings support the outer shell 103 outward and span the outer shell 103. The first framework 1010101 comprises an inner and an outer tendon node or strut node (short: outer tendon node); the inner chord node is connected to the hub 1010102 of the central axle framework 10102 via a radial tie rod 1010103; and the connection points between the first truss 1010101 and the two sub-rings form two outer chord nodes. In this case, the string secondary keel 102 and the outer rings 1010104 are connected by a pair of outer chord nodes; preferably, the pair of outer chordal nodes connected by the string secondary keel 102 correspond to the same positions of the stiffening rings 10101 to which they belong.

Preferably, the shape of a unit of the first truss 1010101 is triangular; more preferably, two radial pull rods 1010103 have one end connected together to the inner tendon node, and the other two ends separately connected to two ends of the hub shaft 1010102. That is, of the three vertices of the triangular unit of the first truss 1010101, the two outer chord kno ten connected to the two sub-rings and carry the force, mainly the pressure, emanating from the outer capsule 103; and the inner chord nodes are connected to both ends of the hub shaft 1010102 in a triangular shape by the corresponding two radial tie rods 1010103. The stiffening ring 10101, based on the first truss 1010101, represents a stable radial stress balancing system that ensures that under the pressure or stress of the outer capsule 103, the stratospheric airship is balanced in radial tension and remains stable, without instability and damage to cause. In addition, the radial self-balancing stiffening ring 10101 can also counteract the radial force component of the string secondary keel 102 connected to it, which further limits the deformation of the stratospheric airship. The counteracting effect of the radial self-balancing stiffening ring 10101 on the string keel 102 can reduce the load material requirement in the corresponding direction of the string keel 102, which helps to reduce the quantity and weight of the string keel 102.

It should be noted that the number of sub-rings of the outer ring 1010104 is not limited to two, and more sub-rings can be selected depending on the actual situation.

The at least two sub-rings of the outer ring 1010104 of the stiffening ring 10101 connected and expanded by the first truss 1010101 and the radial tension rods 1010103 connected to the inner chordal node and the two ends of the hub shank 1010102 share the radial tension of the outer capsule 103 layer by layer. As a result, the stress carried by each structural unit of the stiffening ring 10101 is reduced, making it possible to reduce the amount of material used or to choose lighter materials with somewhat lower stress properties, resulting in a lower overall weight of the airship.

For the same reason, the stiffening ring 10101 bears the radial load almost entirely through the outer capsule 103, so that the radial load on the central axle framework 10102 is very low. That is, the central axle truss 10102 only needs to withstand axial stresses such as e.g. B. axial tensile stresses or rotational stresses. As a result, the structure of the central axle truss 10102 that resists radial deformation can be neglected, thus reducing the amount of material used, or a lighter material with a slightly lower radial stress is chosen, which is also beneficial to the overall weight of the airship.

The stratospheric airship has a relatively large volume. Due to the influence of factors such as lighting, the temperature of the outer capsule 103 is not balanced, so the vertical force components in the longitudinal direction of the stratospheric airship are also different, causing axial stress. When the central axle truss 10102 is subjected to a large bending force, the stratospheric airship may become unstable or it may be difficult to establish an overall feasible preload. Preferably, the central axle truss 10102 comprises a plurality of sections of boat-shaped second trusses. The plurality of sections of boat-shaped second trusses and the various stiffening rings 10101 are connected in series to form a stable, axially self-balancing system. When enduring axial tension or compression, the multiple sections of central axle framework structures 10102 are connected in series to form a stable central axle framework with superior mechanical strength; and the operating principle of the boat-shaped structure of the central axle truss 10102 is similar to that of the string secondary keel 102 with the hollow bulbous structure.

Furthermore, the internal unit of the second trusses can have various shapes, preferably triangular to form a more stable anti-deformation structure.

A central skeleton formed by the various stiffening rings 10101 and the central axle framework 10102 forms the inner skeleton of the stratospheric airship. The outer capsule 103 is placed on the various stiffening rings 10101, string secondary keels 102 and/or longitudinal tie rods 10103 and is stretched out to form an airship. The force exerted on the outer capsule 103 or the outer ring 1010104 is distributed layer by layer by the self-balancing system and transmitted to all parts of the inner skeleton, contributing to the overall form stability of the stratospheric airship at zero pressure, as well as the overall rigidity and load capacity a low pressure, so that the mechanical strength of the stratospheric airship is greatly improved.

The keel 101 mentioned above has a certain structural strength and forms the skeleton of the stratospheric airship, so that it also reflects the basic shape of the stratospheric airship. With the string secondary keels 102, the longitudinal pull tangen 10103 and the self-balancing central skeleton, the volume of the outer capsule 103 is fundamentally prevented from changing excessively due to changes in external atmospheric pressure, changes in atmospheric temperature or heating from solar radiation, so that a change in volume results in a change in buoyancy, and the stratospheric airship consequently ascends and descends excessively while hovering.

Embodiment II

As in 1 As shown, in another preferred embodiment of the present invention, a plurality of inner capsules 104 are arranged inside the outer capsule 103, and the inner capsules 104 are filled with a first gas, the first gas having a density lower than that of air. Similar to the choice of material for the outer capsule 103, the inner capsules 104 are preferably made from ultra-lightweight, low-strength films; and preferably the first gas comprises helium to ensure sufficient buoyancy of the stratospheric airship.

When the stratospheric airship is hovering in the air, it may sway up and down on one side due to directional adjustment or the influence of external forces. Preferably, the inner pods 104 are arranged to annularly surround the central axle truss 10102 to stabilize the center of mass and maintain the left-right balance of the stratospheric airship. Since the inner capsules 104 are distributed annularly around the central axle framework 10102, the first gas is evenly distributed annularly. In addition, the first gas can be viewed with its center of mass concentrated at the center of the ring, and the stable center of mass represents a drag moment that can to some extent prevent the stratospheric airship from oscillating up and down.

Preferably, the inner capsule 104 is also provided with a helium valve 204 and the helium valve 204 is opened at the top of the outer capsule 103 . With this arrangement, in the event of a small or small leakage of an inner capsule 104, since the density of the first gas is less than that of the air in the outer capsule 103, the first gas will be collected over the interior of the outer capsule 103 without the overall weight and buoyancy of the affect stratospheric airship.

Embodiment III

When the airship is "super cold" in the stratosphere, the pressure from the outer capsule 103 may exceed the stress limit of the keel 101, causing the keel 101 to suffer irreversible damage; and when the airship is “super hot” in the stratosphere, the stress from the keel 101 may exceed the tensile strength of the outer pod 103 material, causing the outer pod 103 to suffer irreversible damage. In particular, when the temperature in the stratosphere decreases or when there is no direct sunlight (e.g. at night), the air temperature in the outer capsule 103 and the air pressure in the outer capsule 103 also decrease. However, since the shape of the stratospheric airship by the keel 101 is limited, the shape of the airship does not change significantly, so the lift does not change significantly. However, this causes the air pressure inside the stratospheric airship to decrease more, which is lower than the outside atmospheric pressure, resulting in negative pressure. The negative pressure forces the outer capsule 103 to press on the keel 101. If the negative pressure is too great, it can cause instability or even damage to the stratospheric airship. When the temperature in the stratosphere rises, or when the sun shines directly on the stratospheric airship during the day, the air temperature in the outer capsule 103 rises, resulting in an increase in internal air pressure that is higher than the external atmospheric pressure, creating overpressure arises. However, due to the limited shape of the outer shell 103, the tensile force that the outer shell 103 supports increases. When the tensile force borne by the outer can exceeds the tensile limit of the outer can 103, the outer can 103 is ruptured and causes a hazard.

Unlike the optimization of the structure or the material of the keel 101 and/or the outer capsule 103, in this embodiment an environmental control system as in 5 shown, designed so that it actively controls the pressure change in the work process. The environmental control system is configured to adjust the air pressure within the outer shell 103 between a negative pressure set limit and a positive pressure set limit. Optionally, the set vacuum limit does not exceed a vacuum value corresponding to the keel 101 compression limit and the overpressure limit does not exceed an overpressure value corresponding to the outer pod 103 tensile limit. The limit for the negative pressure and the limit for the positive pressure can also be determined according to other criteria, e.g. B. after a dynamic control based on the return of the airship and the hover angle in the stratosphere.

The principle of the active pressure regulation of the environmental control system is explained below with reference to the in 5 illustrated layout diagram of the environmental control system explained in more detail. In this embodiment, the environmental control system includes an environmental controller 206, a fan and/or an air valve 203; the fan is installed on the outer shell 103; and the air valve 203 is installed at the bottom of the outer shell 103.

Depending on the pressure difference inside and outside the outer shell 103, the environmental controller 206 controls the opening and closing of the fan and/or the air valve 203 to adjust the air pressure balance inside and outside the outer shell 103. In particular, when the overpressure in the outer shell 103 is higher than the overpressure limit, the environmental controller 206 controls the opening of the air valve 203; and the outer shell 103 is driven by the positive pressure to expel air to the outside, and the inner air pressure is reduced. When the negative pressure inside the outer shell 103 is below the negative pressure limit, the environment controller 206 controls the blower to inflate the inside of the outer shell 103 to reduce the negative pressure inside the outer shell 103 . The environmental controller 206 controls the balance between the air pressure inside the outer capsule 103 and the outside atmospheric pressure to ensure the flight safety of the stratospheric airship.

Preferably, the fan comprises a high-altitude fan 201 and/or a low-altitude fan 202; the environmental controller 206 selects the high-altitude fan 201 and/or the low-altitude fan 202 to operate according to the flying altitude of the stratospheric airship to inject air into the outer capsule 103 so that the air pressure inside and outside of the outer capsule 103 is kept within a certain range.

Preferably, the air outlet of the high-altitude fan 201 and/or the low-altitude fan 202 is provided with a normally-closed check valve, the check valve being configured to open when the outer shell 103 is under negative pressure and the blower is in operation to prevent air from escaping the outer capsule 103 under overpressure or zero pressure.

The environmental control system can also be equipped with a differential pressure gauge 205 to detect a pressure differential value of a contact surface between the outer shell 103 and the keel 101 . The differential pressure measuring device 205 is preferably arranged on the underside of the outer capsule 103 .

By controlling the inflation and deflation of the outer capsule 103, the environmental control system changes the gravity of the stratospheric airship, which hardly deforms, thus enabling the control of ascent and descent.

• Schritt 1. In einem ersten Höhenbereich der Stratosphäre, wenn der Luftdruck in der Außenkapsel 103 niedriger als ein erster Unterdruck-Grenzwert ist, steuert der Umgebungskontroller 206 das Gebläse zum Aufblasen von Luft in die Außenkapsel 103, um das Gewicht des Stratosphären-Luftschiffs zu erhöhen; unter dem Umstand, dass die Volumenänderung des Stratosphären-Luftschiffs sehr klein ist, nimmt das Gewicht zu, die Schwerkraft ist größer als der Auftrieb, und das Stratosphären-Luftschiff wird langsam sinken; mit abnehmender Höhe nimmt die Außentemperatur der Atmosphäre ab, und der Luftdruck im Inneren der Außenkapsel 103 nimmt ebenfalls ab, so dass das Aufblasen auch dazu beiträgt, den Luftdruck im Inneren der Außenkapsel 103 aufrechtzuerhalten, so dass die Luftdruckdifferenz innerhalb und außerhalb der Außenkapsel 103 in einem ersten vorgegebenen Bereich gehalten wird.
• Schritt 2. Wenn das Stratosphären-Luftschiff in einen zweiten Höhenbereich absteigt, nimmt die Temperatur der Außenatmosphäre mit abnehmender Höhe zu, so dass der Luftdruck im Inneren der Außenkapsel 103 allmählich in einen Überdruck umschlägt, d.h. der Luftdruck im Inneren der Außenkapsel 103 wird höher als der äußere atmosphärische Druck sein. Zu diesem Zeitpunkt, wenn der Überdruck höher als der erste Überdruck-Grenzwert ist, steuert der Umgebungskontroller 206 das Luftventil 203 zum Öffnen, um eine bestimmte Luftmenge abzulassen. Die Luftdruckdifferenz innerhalb und außerhalb der Außenkapsel 103 wird in einem zweiten vorgegebenen Bereich gehalten, wodurch das Gewicht des Stratosphären-Luftschiffs verringert wird.

The working process of the environmental control system that controls the stratospheric airship in a return and landing phase can be as follows:

• Step 1. In a first stratospheric altitude range, when the air pressure in the outer capsule 103 is lower than a first negative pressure limit, the environmental controller 206 controls the fan to inflate air into the outer capsule 103 to increase the weight of the stratospheric airship ; under the circumstance that the volume change of the stratospheric airship is very small, the weight increases, the gravity is greater than the buoyancy, and the stratospheric airship will sink slowly; as the altitude decreases, the outside temperature of the atmosphere decreases, and the air pressure inside the outer capsule 103 also decreases, so inflation also helps maintain the air pressure inside the outer capsule 103, so the air pressure difference inside and outside the outer capsule 103 in is held within a first predetermined range.
• Step 2. When the stratospheric airship descends to a second altitude range, the temperature of the outside atmosphere increases with decreasing altitude, so that the air pressure inside the outer capsule 103 gradually changes to overpressure, i.e. the air pressure inside the outer capsule 103 becomes higher than be the external atmospheric pressure. At this time, if the overpressure is higher than the first overpressure limit, the environmental controller 206 controls the air valve 203 to open to release a certain amount of air. The air pressure difference inside and outside the outer capsule 103 is maintained within a second predetermined range, thereby reducing the weight of the stratospheric airship.

Considering that the stratosphere is generally 10 to 50 km above sea level, the second altitude range is preferably not higher than 10 km.

The process described above controls the return and landing of the stratospheric airship. He controls the in reverse order Launch and take-off of the stratospheric airship.

Preferably, to control the rate of climb and descent of the stratospheric airship, the inflation rate and/or inflation time of the fan for inflating the outer capsule 103 can be controlled, or the deflation rate and/or deflation time of the air valve 203 can be varied.

For example, in a descending step of Step 2, a second overpressure limit may be set, and the second overpressure limit is less than the first overpressure limit; and when the air pressure inside the outer shell 103 is between the second overpressure limit and the first overpressure limit, the environmental controller 206 controls the blower to inflate the outer shell 103. At this time, this is equivalent to reducing the exhaust efficiency of the outer shell 103 and further reducing the degree of change the lowering speed. The combined pressure control method of the fan and the air valve 203 can achieve various speed adjustment effects, and is particularly suitable for the speed adjustment of the environmental control system, which only has the air valve 203 with two states of opening and closing and the fan with a single rotation speed.

The adjustment criteria for the first overpressure limit and the first underpressure limit can be based on the yield strengths of the materials of the outer capsule 103 and the keel 101 or on a dynamic function controlled based on the rate of ascent and descent.

In addition, the values of the first and second predetermined ranges are ideally set such that the outer shell 103 remains in a state of air pressure equilibrium. In order to avoid frequent inflation and deflation, the first predetermined range and/or the second predetermined range can preferably be set to zero pressure, slightly positive pressure and slightly negative pressure. The air pressure deviation of the slight overpressure and the slight underpressure from the zero pressure can be adjusted to ±1%-5%.

When the environmental control system controls the hovering of the stratospheric airship, the principle is similar, and the air blower and/or the air valve 203 are controlled by the environmental control system to equalize the air pressure inside and outside the outer capsule 103.

Embodiment IV

In another preferred embodiment of the present invention, air bags 107 are provided at the bottom of the stratospheric airship to prevent the stratospheric airship from returning to the ground with a large landing. The airbags 107 are designed to be inflatable and retractable. The air cushions 107 are preferably arranged on the outer capsule 103 directly below the stiffening rings 10101. Considering the large volume of the stratospheric airship, there are preferably at least four airbags 107 evenly arranged at the lower belly portion of the outer capsule 103.

In order to ensure the aerodynamic performance of the stratospheric airship, the airbags 107 are deployed and collapsed during the cruising phase of the airship; on return and landing, the airship will not be inflated to design pressure until it is 1 km above the ground.

Embodiment V

In another preferred embodiment of the present invention, the stratospheric airship is also provided with a propulsion system.

As in 6 As shown, the propulsion system includes a rear engine 302; and a propulsion controller of the propulsion system is configured to control the rear engine 302 . The tail engine 302 is arranged in a tail portion of the stratospheric airship and installed on the outer surface of the outer capsule 103 . Preferably, the tail engine 302 is installed longitudinally at the end of the stratospheric airship to obtain the longest power arm. The longer the power arm, the greater the torque. Therefore, even if the tail engine 302 has a relatively small power, it can easily change the pitch flight state of the stratospheric airship or help the stratospheric airship to change direction.

In order to improve the steering ability of the stratospheric airship, side thrusters 301 can preferably also be provided, which support the direction adjustment of the horizontal direction of the stratospheric airship, e.g. B. a U-turn or an axial rotation. The side engines 301 are also controlled by the drive control. Preferably, a plurality of pairs of side thrusters 301 are located at the head or center position of the outer pod 103 and are symmetrical with respect to each other distributed on a vertical axial plane of the central axle truss 10102. In addition, an imaginary plane formed by the connecting lines of a plurality of side engines 301 is perpendicular to the planes in which the stiffening rings 10101 are arranged.

Preferably, the thrusters 301 use vector control techniques to further aid in pitch and steering control. Considering the working environment of the airship in the stratosphere, the stern engine 302 and/or the side engines 301 preferably use a technical solution for driving the high-altitude propellers by an high-altitude motor.

In addition, fins 105 may be provided in the rear of the stratospheric airship, which are configured to help stabilize the attitude of the stratospheric airship. As in 2 As shown, two pairs of empennages 105 without control surfaces are arranged on the outer surface of the outer pod 103 in an X-shaped arrangement; preferably, the tailplanes 105 are inflatable tailplanes.

Embodiment VI

In a further preferred embodiment of the present invention, the stratospheric airship is equipped with an energy system for extending the flight time, for example a system for renewable energy, in particular a solar battery system.

As in 6 As shown, a solar energy collection plate 401 covers the outer shell 103, at least the top so that it faces the sun. The electric power generated by the solar power collection panel 401 is transmitted through wires to the battery for storage, and the battery provides power for the environmental control system and the propulsion system. When there is light, the solar energy collection panel 401 converts light energy into electric energy, and the battery stores the electric energy while using the electric energy for power supply; when there is no light, the battery uses the stored electrical energy for power supply. The technical solution of the solar battery system can reduce the energy source that the stratospheric airship needs to carry, which is equivalent to increasing the energy reserve and reducing the overall weight, thereby increasing the time that the stratospheric airship stays in the air continuously , considerably lengthened.

A gondola 106 can also be installed below the stratospheric airship, as in 2 shown, to be provided; and the battery can be housed in the nacelle 106. Preferably, the nacelle 106 is connected to the outer shell 103 directly under a given stiffening ring 10101 .

The preferred specific embodiments of the present invention have been described in detail above. It goes without saying that one skilled in the art would be able to make various modifications and variations in accordance with the concept of the present invention without the use of the inventive effort. Therefore, any technical solution that can be achieved by a person skilled in the art through logical analysis, reasoning or limited experimentation based on the state of the art and according to the concept of the present invention should fall within the scope of protection defined by the claims.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• CN 108706091A [0005]
• CN108725734A [0005]
• CN 106394855A [0006]
• CN201521080600X[0008]
• CN 108725741A [0009]
• CN201910275705 [0010]

Claims (20)

Stratospheric airship with a large rigid-flexible integrated structure, characterized in that it comprises an outer capsule and a keel, the outer capsule covering the keel; the keel comprises a central axle framework, stiffening rings and a string secondary keel; the central axle truss extends along the longitudinal direction of the stratospheric airship; the plurality of stiffening rings are arranged coaxially and the stiffening rings are arranged coaxially with the central axle framework; the centers of the stiffening rings are connected to the central axle framework; and the string secondary keel is connected to outer rings of adjacent ones of the stiffening rings in a head region of the stratospheric airship. Stratospheric airship with a large rigid-flexible integrated structure claim 1 characterized in that the string secondary keel comprises an outer string tension rod and an inner string tension rod, the outer string tension rod and the inner string tension rod forming a hollow abdomen; and the outer string tension rod is in contact with the inner surface of the outer shell. Stratospheric airship with a large rigid-flexible integrated structure claim 2 , characterized in that the string secondary keel further comprises support rods, the support rods being arranged at a belly part of the string secondary keel, the support rods connecting the outer string tension rod and the inner string tension rod to each other. Stratospheric airship with a large rigid-flexible integrated structure claim 3 , characterized in that the plurality of support rods are arranged parallel to each other. Stratospheric airship with a large rigid-flexible integrated structure claim 2 , characterized in that the keel further comprises longitudinal tie rods and the longitudinal tie rods are connected to outer rings of adjacent ones of the stiffening rings, the longitudinal tie rods being arranged in the head region of the stratospheric airship and the two ends of the longitudinal tie rod being respectively associated with the head end and the tail end of the string -Secondary keel connected. Stratospheric airship with a large rigid-flexible integrated structure claim 1 , characterized in that the outer ring comprises two sub-rings and first trusses; the first trusses are distributed along the inner circumference of the outer ring; the two subrings are connected and widened by the first trusses; the first trusses comprise an inner chord node and an outer chord node; the inner chord node is connected to the central axle truss by a radial tie rod; the outer chord-knot connecting the first truss and the two sub-rings; and the string secondary keel and the outer ring are connected by the outer chord knot. Stratospheric airship with a large rigid-flexible integrated structure claim 1 characterized in that the central axle truss comprises a plurality of sets of boat-shaped second trusses and the second trusses connect adjacent ones of the stiffening rings; and the shape of an inner unit of the second truss comprises a triangle. Stratospheric airship with a large rigid-flexible integrated structure claim 1 , characterized in that it further comprises an inner capsule, the inner capsule being arranged inside the outer capsule; and the inner capsule is filled with a first gas, the first gas having a density lower than that of air. Stratospheric airship with a large rigid-flexible integrated structure claim 8 , characterized in that the inner capsule surrounds the central axis framework ring-shaped. Stratospheric airship with a large rigid-flexible integrated structure claim 1 , characterized in that it further comprises an environmental control system, the environmental control system being configured to control the air pressure in the outer capsule. Stratospheric airship with a large rigid-flexible integrated structure claim 10 , characterized in that the environmental control system is configured to maintain the air pressure in the outer capsule between a set under pressure limit and a set over pressure limit. Stratospheric airship with a large rigid-flexible integrated structure claim 11 , characterized in that the vacuum limit is set not to exceed a vacuum value corresponding to the pressure limit of the keel, and the over pressure limit is set so that it does not exceed an overpressure value that corresponds to the tensile limit of the outer capsule. Stratospheric airship with a large rigid-flexible integrated structure claim 10 , characterized in that the environmental control system comprises an air valve; the air valve is located at the bottom of the outer shell; and the air valve is configured to allow the outer shell to be vented to the outside in a positive pressure condition. Stratospheric airship with a large rigid-flexible integrated structure claim 10 , characterized in that the environmental control system further comprises a fan; the blower is installed on the outer capsule; and the blower is configured to inflate the outer shell in a negative pressure condition. Stratospheric airship with a large-scale rigid-flexible integrated structure Claim 14 , characterized in that the fan comprises a high-altitude fan and/or a low-altitude fan. Stratospheric airship with a large-scale rigid-flexible integrated structure claim 15 , characterized in that an air outlet of the fan is provided with a non-return valve. Stratospheric airship with a large-scale rigid-flexible integrated structure claim 1 , characterized in that it further comprises an air bag, the air bag being configured to be supported on the bottom of the stratospheric airship. Stratospheric airship with a large rigid-flexible integrated structure claim 1 characterized in that it further comprises a battery, the battery being housed in a nacelle, the nacelle being under the stratospheric airship; and the battery is electrically connected to a solar energy collection panel. Stratospheric airship with a large rigid-flexible integrated structure claim 1 , characterized in that it further comprises a propulsion system, wherein the propulsion system comprises a rear engine and/or side engines; the tail engine is attached to the outer surface of the outer pod in a tail portion of the stratospheric airship; the side engines are fixed at a head and/or middle position of the stratospheric airship and the side engines are distributed symmetrically on the left and right sides with respect to an axial direction of the central axle truss; and the side engines and/or the tail engine comprise/includes high-altitude propellers driven by an high-altitude motor. Stratospheric airship with a large rigid-flexible integrated structure claim 1 , characterized in that it further comprises two pairs of tailplanes, the two pairs of tailplanes being arranged in a rear area of the stratospheric airship and having an X-shaped arrangement.

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