Foldable propeller and cross-medium aircraft with same

Abstract

The utility model relates to a foldable propeller and a cross-medium aircraft with the same, the foldable propeller comprises a propeller hub controlled to rotate, a limiting structure arranged at the end part of the propeller hub and a plurality of blades uniformly arranged around the axis of the propeller hub, and each blade is hinged with the propeller hub; the hinged axis between the paddle and the propeller hub is perpendicular to the rotating axis of the propeller hub, and the limiting structure is located at the front end of the propeller hub in the direction of the pulling force generated when the paddle rotates along with the propeller hub; when the propeller hub rotates, the blades hinged to the propeller hub rotate and unfold under the action of centrifugal force to abut against the limiting structure. When the propeller hub stops rotating, the blades hinged to the propeller hub are folded to be close to the rotating axis of the propeller hub due to self weight or fluid resistance in the underwater flight process. The propellers are configured to be of a foldable structural form, so that the propellers are not prone to being impacted by water flow and damaged, meanwhile, turbulent flow generated when the water flow passes through the propellers is reduced, and the speed and stability of the cross-medium aircraft in the underwater flight process are improved.

Description

Technical Field

[0001] The utility model relates to the field of water-air cross-medium aircraft, in particular to a foldable propeller and a cross-medium aircraft with the propeller. Background Art

[0002] In order to expand the operating environment and application scope of existing aircraft and make full use of the advantages of high concealment of underwater flight and high maneuverability of air flight, aviation technology personnel in various countries are currently developing aircraft with water-air cross-medium flight capabilities. Water-air cross-medium aircraft have the ability to fly in the air and dive underwater at the same time, and have important application value in the fields of reconnaissance, detection, search and rescue, and communication.

[0003] However, no mature water-to-air cross-medium aircraft has been successfully developed so far. Therefore, the development of water-to-air amphibious cross-medium unmanned aerial vehicles has huge potential application value and important strategic significance. The aerial power mechanism that drives the unmanned aerial vehicle to fly in the air can be a turbojet engine or a propeller; the underwater power mechanism that drives the unmanned aerial vehicle to fly underwater can be a propeller propeller or a water jet propulsion system.

[0004] While conventional airborne propulsion systems may cease to function after being submerged in water, propellers can continue to operate even after immersion. Therefore, propellers are often used for the propulsion of trans-medium aircraft. However, propellers also present several challenges. They are easily damaged by the impact of water flow during underwater flight. Furthermore, water flowing over propellers creates turbulence, affecting the speed and stability of trans-medium aircraft during underwater flight. Utility Model Content

[0005] The present invention aims to solve the problems that when propellers are currently used as the aerial propulsion mechanism of a trans-medium aircraft, the propellers are easily damaged by the impact of water flow and the propellers cause turbulence. The utility model provides a foldable propeller and a trans-medium aircraft with the propeller to solve these technical problems. The propeller is configured in a foldable structure, so that the propeller is not easily damaged by the impact of water flow, and at the same time the turbulence generated when the water flows through the propeller is reduced, thereby improving the speed and stability of the trans-medium aircraft when flying underwater.

[0006] In order to solve the above technical problems, the technical solutions of the present utility model are as follows:

[0007] A foldable propeller comprises a hub for controlled rotation, a limiting structure provided at the end of the hub, and a plurality of blades evenly arranged around the axis of the hub, wherein each blade is hinged to the hub, and the hinge axis between the blade and the hub is perpendicular to the rotation axis of the hub. The limiting structure is located at the front end of the hub along the direction of the pulling force generated when the blade rotates with the hub;

[0008] When the hub rotates, the blades hinged to the hub rotate and expand under the action of centrifugal force until they are against the limit structure; when the hub stops rotating, the blades hinged to the hub are retracted close to the rotation axis of the hub due to their own weight or fluid resistance during underwater flight.

[0009] A cross-medium aircraft includes a teardrop-shaped centrally symmetrical body having a nose and a fuselage, wherein the nose of the body is located at the front side of the fuselage, and the body is provided with an underwater power mechanism for providing underwater flight power and an aerial power mechanism for providing aerial flight power, wherein the aerial power mechanism is the above-mentioned foldable propeller.

[0010] Preferably, the cross-medium aircraft further includes a water entry and exit attitude adjustment mechanism, the water entry and exit attitude adjustment mechanism comprising a watertight compartment provided inside the nose, a flexible water storage bag located within the watertight compartment, and a two-way water pump connected to the water storage bag, one flow channel of the two-way water pump being connected to the water storage bag, and the other flow channel being connected to the rear end of the fuselage;

[0011] The bidirectional water pump adjusts the overall density of the aircraft and the position of the center of mass of the aircraft along the long axis of the fuselage by changing the water storage volume in the water storage bag. When the water in the water storage bag switches between an empty state and a full state, the numerical variation range of the overall density of the aircraft includes the density value of water; when the water in the water storage bag is emptied and the trans-medium aircraft floats on the water surface, the center of mass of the aircraft is located behind the metacenter.

[0012] Preferably, an empty compartment is further provided at the rear end of the fuselage, and a water hole communicating with the empty compartment is opened at the rear end of the fuselage;

[0013] When the empty compartment is filled with water and the water in the water storage bag is emptied, the overall density of the trans-medium aircraft is less than the density of water.

[0014] Preferably, the side of the fuselage is connected to four or six fixed wings, and the trailing edges of the fixed wings are provided with controlled rotating slipstream fins, and the rotation axis of the slipstream fins is parallel to the wing surfaces of the fixed wings and perpendicular to the long axis of the fuselage;

[0015] When the fuselage is connected to four fixed wings, two of the fixed wings are used as wings symmetrically distributed on both sides of the fuselage, and the remaining two fixed wings are symmetrically arranged on both sides of the plane where the wings are located, forming two mutually symmetrical vertical tails;

[0016] When the fuselage is connected to six fixed wings, two of the fixed wings are used as wings symmetrically distributed on both sides of the fuselage, and the remaining four fixed wings are arranged in pairs on both sides of the plane where the wings are located. The two fixed wings in the same pair are located on the same side of the plane where the wings are located, and form a V-shaped vertical tail.

[0017] Preferably, the fixed wing is a delta wing.

[0018] Preferably, with the wing surface of the fixed wing as a reference plane, when the slipstream fin rotates relative to the fixed wing, the angle range of rotation of the slipstream fin relative to the wing surface is ±30°.

[0019] Preferably, for the slipstream fin and the propeller connected to the same fixed wing, the slipstream fin is arranged in the slipstream area of ​​the propeller.

[0020] Preferably, the cross-medium aircraft also includes a rotating motor for driving each propeller to rotate and a power battery for supplying power to all the rotating motors. The power supply line between the power battery and the rotating motor is also provided with an electronic speed regulator to control the rotation speed of each propeller separately.

[0021] Preferably, the underwater power mechanism includes an underwater propeller connected to the rear end of the fuselage, the underwater propeller is also powered by a power battery, and the electronic speed regulator is also connected to the power supply circuit between the power battery and the underwater propeller.

[0022] Preferably, the underwater power mechanism is an underwater propeller connected to the rear end of the fuselage.

[0023] Preferably, the fixed wing of the cross-medium aircraft is further connected to a support structure, and the rear end of the support structure is located at the rear side of the underwater propeller.

[0024] Preferably, the underwater power mechanism includes an underwater propeller connected to the rear end of the fuselage, the water inlet and the water outlet of the underwater propeller are respectively located at the front end and the rear end of the underwater propeller, and a plurality of diversion gaps are opened on the edge of the rear end of the fuselage, and the diversion gaps are evenly arranged around the circumference of the fuselage.

[0025] Preferably, the cross-media aircraft also includes a flight control device for controlling the flight attitude, the flight control device includes sensors and an onboard computer, the sensors include an attitude sensor and a positioning module, and the onboard computer controls the operation of the air power mechanism, the underwater power mechanism, and the water entry and exit attitude adjustment mechanism according to the information data measured by the sensors.

[0026] Beneficial technical effects of the technical solution of this utility model:

[0027] (1) The foldable propeller includes a rotating hub, a limiting structure provided at the front end of the hub, and a plurality of blades arranged around the axis of the hub, and each blade is hinged to the hub. The limiting structure is located at the front end of the hub along the direction of the pulling force generated when the blade rotates with the hub. When the hub of the propeller is controlled to drive the blades to rotate, the free end of the blade is moved away from the axis of rotation of the hub under the action of centrifugal force, so that the blades of the propeller can be fully unfolded until the blade surface and the limiting structure at the front end of the hub are offset. The expansion range of the blades is locked by utilizing the centrifugal force exerted on the blades and the obstruction of the limiting structure, so that the unfolded blades generate a continuous and stable airflow when rotating, driving the cross-medium aircraft to fly.

[0028] During underwater flight, the propeller stops working and the blades are retracted close to the hub axis under the action of water resistance. The retracted blades are not easily affected by water impact, which can extend the service life of the blades and reduce the turbulence generated by the blades, thereby reducing the resistance encountered by the trans-medium aircraft underwater and improving the speed and stability of the trans-medium aircraft during underwater flight.

[0029] (2) The aircraft body in this solution is provided with an aerial power mechanism and an underwater power mechanism, and is suitable for flying in the air and underwater. The aircraft body includes a nose and a fuselage, and is also provided with a water entry and exit attitude adjustment mechanism for controlling the aircraft to switch between a state suitable for aerial flight and a state suitable for underwater flight. The water entry and exit attitude adjustment mechanism includes a watertight compartment provided in the nose, a flexible water storage bag located in the watertight compartment, and a two-way water pump connected to the water storage bag. When the two-way water pump is used to fill the water storage bag with water and to pump the water out of the water storage bag, the mass distribution of the trans-medium aircraft can be changed, thereby changing the overall density of the trans-medium aircraft and the position of the center of mass, and controlling the trans-medium aircraft to enter and exit the water.

[0030] For example, when the aircraft is floating on the water surface, water can be added to the water bladder to increase the mass of the nose, causing the aircraft to fall over and plunge into the water. This also increases the overall density of the aircraft, immersing it entirely in water and allowing it to switch to underwater flight. While the aircraft is flying underwater, the water in the bladder can be gradually pumped out to reduce its overall density, allowing it to gradually rise to the surface. When the water in the bladder is emptied, the aircraft's center of mass is located behind the metacenter, and the aircraft, floating on the water surface, can automatically adjust to a nose-up attitude, making it convenient for flight and suitable for aerial flight.

[0031] (3) An empty compartment is also provided inside the fuselage, and a water-permeable hole is provided at the rear end of the fuselage that is connected to the empty compartment. When the trans-medium aircraft is flying in the air, the empty compartment is in an empty state, and the overall mass of the aircraft is relatively small, making it suitable for flying in the air. When the trans-medium aircraft lands on the water surface, the rear end of the fuselage is immersed in water, and some water will enter the lower part of the empty compartment through the water-permeable hole, increasing the overall density of the trans-medium aircraft and causing the center of mass of the aircraft to gradually move toward the rear end of the aircraft, thereby promoting the aircraft to float stably on the water surface. When the aircraft is completely underwater, the space in the empty compartment can be completely filled with water, further increasing the overall mass and overall density of the trans-medium aircraft, making the trans-medium aircraft suitable for underwater flight.

[0032] (4) Four or six fixed wings are connected to the sides of the fuselage. Four fixed wings can form two wings and two vertical tails, while six fixed wings can form two wings and two V-shaped vertical tails. The trailing edge of each fixed wing is also rotatably connected to a slipstream fin. When the trans-aircraft is flying in the air or underwater, air or water flow continuously passes over the fixed wings and the slipstream fins. By controlling the deflection of different slipstream fins, the air or water flow passing through the slipstream fins can be used to generate a torque that propels the trans-aircraft to deflect, thereby conveniently controlling the trans-aircraft to produce pitch, roll, and yaw movements. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It shows a schematic structural diagram of a cross-medium aircraft in an embodiment of the present utility model;

[0034] Figure 2 Shows a schematic structural diagram of the machine body in an embodiment of the present utility model;

[0035] Figure 3 A schematic diagram of the structure of the fixed wing, propeller and slipstream rudder in an embodiment of the present invention is shown;

[0036] Figure 4 A schematic diagram of the propeller blade movement in an embodiment of the present utility model is shown.

[0037] In the accompanying drawings:

[0038] 1- fuselage; 1a- nose; 1b- fuselage; 11- diversion gap; 111- water permeable hole; 12- empty compartment; 13- supporting structure; 14- electronic speed regulator; 15- power battery; 2- fixed wing; 21- propeller; 211- hub; 212- blade; 213- limit structure; 214- rotating motor; 22- slipstream rudder; 221- servo; 222- articulated rod; 3- underwater thruster; 4- water entry and exit attitude adjustment mechanism; 41- watertight compartment; 42- water storage bladder; 43- two-way water pump; 44- pipeline. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the following further describes the foldable propeller and the trans-medium aircraft equipped with the propeller proposed in the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in a very simplified form and are not in exact proportions. They are only used to conveniently and clearly illustrate the objectives of the embodiments of the present invention. To make the objectives, features, and advantages of the present invention more clearly understood, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in this specification for those familiar with the technology to understand and read. They are not intended to limit the implementation conditions of the present invention and therefore have no substantive technical significance. Any structural modifications, changes in proportional relationships, or adjustments in size, without affecting the efficacy and objectives that can be achieved by the present invention, should still fall within the scope of the technical content disclosed in the present invention.

[0040] The following will be combined with the Figures 1 to 4 The technical solutions of the foldable propeller of the utility model and the cross-medium aircraft with the propeller are described in detail with specific embodiments.

[0041] Example

[0042] like Figures 1 to 4 As shown, a foldable propeller of this embodiment includes a hub 211 for controlled rotation, blades 212 hinged to the hub 211, and a rotary motor 214 that drives the hub 211 to rotate. Each hub 211 is connected to two blades 212, and the two blades 212 are evenly arranged around the axis of the hub 211. One end of the blade 212 is hinged to the hub 211, and the other end is a free end. The hinge axis between the blade 212 and the hub 211 is perpendicular to the rotation axis of the hub 211. Along the direction of the pulling force generated when the blade 212 rotates with the hub 211, a limiting structure 213 is fixedly connected to the front end of the hub 211. The limiting structure 213 is used to limit the angle of rotation of the blade 212 toward the limiting structure 213. When the trans-medium aircraft needs to fly using propeller 21, it drives hub 211 to rotate, thereby driving blades 212 to rotate. During the rotation of blades 212, blades 212 also rotate around the hinge axis between themselves and hub 211. The free ends of blades 212 are moved away from the rotation axis of hub 211 under the action of centrifugal force, allowing blades 212 of propeller 21 to fully deploy until the blade surfaces of blades 212 abut against limiting structure 213 at the front end of hub 211. The deployment range of blades 212 is locked by the centrifugal force exerted on blades 212 and the obstruction of limiting structure 213. After deployment, blades 212 can generate continuous and stable airflow during rotation, driving the trans-medium aircraft to fly.

[0043] This embodiment also discloses a trans-medium aircraft, comprising a teardrop-shaped body 1 having a nose 1a and a fuselage 1b. The body 1 is centrally symmetrical, with the nose 1a located in front of the fuselage 1b. The body 1 is equipped with an aerial propulsion system, an underwater propulsion system, and a water entry and exit attitude adjustment mechanism 4. The aerial propulsion system is used to drive the trans-medium aircraft in flight, the underwater propulsion system is used to drive the trans-medium aircraft underwater, and the water entry and exit attitude adjustment mechanism 4 is used to drive the trans-medium aircraft into and out of water. In this embodiment, the water entry and exit attitude adjustment mechanism 4 includes a watertight compartment 41 disposed within the nose 1a, a flexible water storage bladder 42 disposed within the watertight compartment 41, and a two-way water pump 43 connected to the water storage bladder 42. One flow channel of the two-way water pump 43 is connected to the water storage bladder 42, and the other flow channel is connected to a pipe 44. The pipe 44 extends to the rear end of the fuselage 1b. When the rear end of the fuselage 1b is immersed in water, the two-way water pump 43 can conveniently pump water into the water storage bladder 42. The watertight compartment 41 is enclosed and sealed from the water bladder 42. When water is added to the water bladder 42, positive pressure is generated therein, compressing the air between the compartment 41 and the water bladder 42. When water is removed from the water bladder 42, negative pressure is generated therein, expanding the air between the compartment 41 and the water bladder 42. It should be noted that the various fore-aft positions described in this embodiment refer to fore-aft positions along the longitudinal axis of the body 1.

[0044] The installation location of the bidirectional water pump 43 in this embodiment is not restricted; it only needs to ensure that it can pump water out of the water bladder 42 and pump water back into the bladder 42 when the tail end of the aircraft is submerged in water. By adjusting the water volume within the bladder 42 using the bidirectional water pump 43, the overall density of the aircraft and the position of the aircraft's center of mass along the long axis of the aircraft body 1 can be adjusted. The range of values ​​for the overall density of the aircraft includes the density of water. When the bladder 42 is empty, the overall density of the aircraft is at its minimum value, less than the density of water. When the bladder 42 is filled with water, the overall density of the aircraft reaches its maximum value, greater than the density of water.

[0045] When the trans-medium aircraft is in flight, the water bladder 42 is empty, and the overall mass of the aircraft is low, making it suitable for aerial flight. To transition from aerial flight to underwater flight, the trans-medium aircraft is first landed on the water surface. At this point, the aircraft's overall density is less than that of water, allowing it to float stably. Furthermore, the aircraft's center of mass is located behind the metacenter, allowing the aircraft to maintain an upward-pointing nose 1a while floating on the water surface. This facilitates both upward takeoff and the bidirectional water pump 43 to pump water from the rear end of the fuselage 1b into the water bladder 42.

[0046] The aircraft body 1 in this embodiment is equipped with both aerial and underwater propulsion mechanisms, enabling both aerial and underwater flight. The water entry and exit attitude control mechanism 4, when filling and draining the water reservoir 42, can alter the mass distribution of the trans-medium aircraft, changing the overall density and center of mass of the trans-medium aircraft, thereby controlling its entry and exit movements.

[0047] For example, when the aircraft is floating on the water surface, water is added to the water bladder 42 to increase the mass of the nose 1a, causing the aircraft to fall over and plunge into the water. Water is then continuously added to the water bladder 42 until the overall density of the aircraft is greater than that of water, causing the aircraft to sink into the water and transition to underwater flight. While the aircraft is flying underwater, the water in the water bladder 42 is gradually pumped out to reduce the overall density of the aircraft. When the overall density of the aircraft is less than that of water, the aircraft automatically rises to the surface. Furthermore, after the water in the water bladder 42 is emptied, the center of mass of the aircraft is located behind the metacenter. The aircraft, floating on the water surface, automatically adjusts to a nose-up position, facilitating its flight into the air. Furthermore, after the water in the water bladder 42 is emptied, the overall density of the aircraft is also reduced, making it suitable for flight.

[0048] In addition, in this embodiment, the rear end of the fuselage 1b is provided with an empty compartment 12. This compartment also has a water hole 111 connected to the empty compartment 12. When the rear end of the fuselage 1b is immersed in water, water can flow into the empty compartment 12 through the water hole 111, thereby allowing the rear end of the fuselage 1b to be immersed in water and improving the stability of the aircraft while maintaining its nose 1a facing upward. Furthermore, the accumulation of water in the empty compartment 12 increases the overall density of the aircraft, making it suitable for underwater flight. When the trans-medium aircraft is airborne, the flight attitude of the fuselage 1b is adjusted to allow the water in the empty compartment 12 to be completely drained through the water hole 111, reducing the overall density of the aircraft and making it suitable for aerial flight. When the empty compartment 12 is filled with water and the water in the water storage bladder 42 is emptied, the overall density of the trans-medium aircraft is less than that of water, thereby ensuring that the trans-medium aircraft can successfully float to the surface.

[0049] Specifically, the teardrop-shaped body 1 of this embodiment can reduce the drag of the aircraft in water, improving its speed and maneuverability. Furthermore, the centrally symmetrical structure of the body 1 makes it less likely to generate turbulent airflow when flying in the air and less likely to generate turbulent water flow when flying underwater, thereby improving the stability of the aircraft in both air and underwater flight.

[0050] In addition, four fixed wings 2 are installed on the side of the fuselage 1b. The four fixed wings 2 are evenly arranged around the axis of the fuselage 1. Two of the fixed wings 2 are symmetrically installed on both sides of the fuselage 1b, forming the wings of the fuselage 1; the remaining two fixed wings 2 are symmetrically distributed on both sides of the plane where the wings are located, forming the two vertical tails of the fuselage 1.

[0051] In this embodiment, each fixed wing 2 is a delta wing. This delta wing configuration generally features low drag during supersonic flight, high structural strength, and minimal rearward movement of the wing's center of gravity at transonic speeds. The trailing edge of each fixed wing 2 is also equipped with a controlled, rotating slipstream fin 22. The rotation axis of the slipstream fin 22 is parallel to the wing surface of the fixed wing 2 and perpendicular to the long axis of the fuselage 1. When the trans-aircraft is airborne or underwater, the slipstream fin 22 is controlled to deflect at a certain angle. Air or water flowing past the slipstream fin 22 generates a torque that propels the trans-aircraft, causing it to perform pitch, roll, and yaw maneuvers. In this embodiment, the angular range of the slipstream fin 22's control surface relative to the wing surface of the fixed wing 2 is ±30°.

[0052] In another embodiment, six fixed wings 2 can be installed on the side of the fuselage 1b, wherein two fixed wings 2 are symmetrically installed on both sides of the fuselage 1b, forming the wings of the fuselage 1; the remaining four fixed wings 2 are arranged in pairs on both sides of the plane where the wings are located, and the two fixed wings 2 in the same pair are located on the same side of the plane where the wings are located. The two fixed wings 2 in the same pair constitute a V-shaped vertical tail, and the two V-shaped vertical tails corresponding to the two pairs of fixed wings 2 are respectively located on both sides of the plane where the wings are located.

[0053] The aerial power mechanism in this embodiment is the foldable propeller 21 mentioned above. Each fixed wing 2 is equipped with a propeller 21. The propeller 21 is installed at the end of the fixed wing 2 away from the fuselage 1b, and the rotation axis of the propeller 21 is parallel to the long axis of the fuselage 1b. When the propeller 21 rotates, it generates power to drive the cross-medium aircraft to fly. The underwater power mechanism in this embodiment uses an underwater propeller 3. The underwater propeller 3 is installed at the rear end of the fuselage 1b and is coaxial with the fuselage 1b. When the underwater propeller 3 sprays water backward, it can propel the cross-medium aircraft to fly underwater. Please refer to Figures 2 to 4 , specifically introduce the aerial power mechanism and underwater power mechanism in this embodiment:

[0054] The propeller 21 of the air power mechanism includes a controlled rotation hub 211, blades 212 hingedly connected to the hub 211, and a rotary motor 214 that drives the hub 211. Each hub 211 is connected to two blades 212, which are evenly arranged around the axis of the hub 211. A limiting structure 213 is also fixedly connected to the front end of the hub 211. The limiting structure 213 limits the rotation angle of the blades 212 when rotating toward the front side of the fuselage 1b. When the trans-medium aircraft needs to fly using propeller 21, it drives hub 211 to rotate, thereby driving blades 212 to rotate. During the rotation of blades 212, blades 212 also rotate around the hinge axis between themselves and hub 211. The free ends of blades 212 are moved away from the rotation axis of hub 211 under the action of centrifugal force, allowing blades 212 of propeller 21 to fully deploy until the blade surfaces of blades 212 abut against limiting structure 213 at the front end of hub 211. The deployment range of blades 212 is locked by the centrifugal force exerted on blades 212 and the obstruction of limiting structure 213. After deployment, blades 212 can generate continuous and stable airflow during rotation, driving the trans-medium aircraft to fly.

[0055] When the trans-medium aircraft lands with its nose 1a pointing upward, the propeller 21 stops rotating, and the blades 212 droop due to their own weight, automatically retracting toward the rotation axis of the hub 211. This reduces the space occupied and makes the retracted blades 212 less susceptible to damage from collisions. When the trans-medium aircraft flies underwater, the blades 212 experience resistance toward the rear of the trans-medium aircraft, which causes the blades 212 to retract backward toward the rotation axis of the hub 211, reducing the resistance encountered by the trans-medium aircraft during underwater flight and increasing its maximum speed. While the trans-medium aircraft is flying underwater, the retracted blades 212 are also less susceptible to water impact, extending the life of the blades 212. They also reduce the turbulence generated by the blades 212 and the resistance encountered by the blades 212, enabling the trans-medium aircraft to fly smoothly underwater.

[0056] In this trans-medium aircraft, a slipstream rudder 22 and a propeller 21 connected to the same fixed wing 2 are located within the propeller 21's slipstream zone, enabling efficient mid-air adjustment of the trans-medium aircraft's attitude. A servo 221 is also installed within the fixed wing 2 to drive the slipstream rudder 22's deflection. In this embodiment, a three-section articulated rod 222 is connected between the servo 221 and the slipstream rudder 22, with adjacent sections of the articulated rod 222 being hingedly connected. The first section of the articulated rod 222 is connected to the servo 221, which drives the first section of the articulated rod 222 to rotate. The last section of the articulated rod 222 is fixedly connected to the control surface of the slipstream rudder 22. When the servo 221 drives the first section of the articulated rod 222 to rotate, the articulated rod 222 can drive the slipstream rudder 22 to deflect.

[0057] It should be understood that, in another embodiment, the servo 221 can directly drive the slipstream fin 22 to deflect via a gear set or a sprocket set.

[0058] The trans-medium aircraft in this embodiment can fly with its nose 1a pointing vertically upward or nearly vertically upward. When the trans-medium aircraft needs to deflect horizontally, the rotational speed of each propeller 21 can be adjusted to tilt the fuselage 1b of the trans-medium aircraft. This tilts the direction of the total lift generated by all propellers 21, thereby driving the trans-medium aircraft horizontally. Furthermore, the trans-medium aircraft can also switch to a level flight attitude while in flight, maintaining the long axis of the fuselage 1b horizontally or nearly horizontally. The propellers 21 and slipstream fins 22 can then be used to rapidly move the trans-medium aircraft horizontally while maintaining a level flight attitude.

[0059] Specifically, the underwater propeller 3 of the underwater propulsion mechanism is mounted at the rear end of the fuselage 1b. The water inlet of the underwater propeller 3 is positioned toward the fuselage 1b and spaced a distance from the rear end of the fuselage 1b. The water outlet of the underwater propeller 3 is positioned away from the fuselage 1b. The rear end of the fuselage 1b is connected to the underwater propeller 3 via four rod structures. The four rod structures are evenly arranged around the axis of the fuselage 1b and extend along the long axis of the fuselage 1b. The rod structures are fixedly connected to the fuselage 1b and the underwater propeller 3, or are detachably connected. The underwater propeller 3 in this embodiment is a ducted water propeller, but it can also be replaced with a propeller-type vector propeller or a pump-jet propeller.

[0060] When the cross-medium aircraft is flying underwater, the underwater propeller 3 needs to continuously inhale water and then discharge the water. However, the underwater propeller 3 is installed at the rear end of the fuselage 1b, which causes the fuselage 1b to block the water inlet of the underwater propeller 3, which is not conducive to the underwater propeller 3 absorbing water. Therefore, in order to ensure that the underwater propeller 3 works efficiently, the rear end edge of the cross-medium aircraft is also provided with a plurality of diversion gaps 11, and the plurality of diversion gaps 11 are evenly arranged around the circumference of the fuselage 1b. The wall surface of the diversion gap 11 is a smooth concave arc surface, and the diversion gap 11 is smoothly connected to the surface of the fuselage 1b, which reduces the obstruction of the underwater propeller 3 and enables the underwater propeller 3 to work efficiently. In addition, the water-permeable hole 111 in this embodiment is provided on the wall surface of the diversion gap 11.

[0061] In addition, since the rear end of the fuselage 1b is connected to the underwater propeller 3, when the cross-medium aircraft lands with the nose 1a facing upward, in order to avoid collision damage to the underwater propeller 3, each fixed wing 2 of the cross-medium aircraft is also connected to a long strip of support structure 13, and the rear end of the support structure 13 extends backward along the long axis direction of the fuselage 1 to the rear side of the underwater propeller 3. When the cross-medium aircraft lands with the nose 1a facing upward, it can contact the landing area through the rear end of the support structure 13 to avoid colliding with the underwater propeller 3.

[0062] Specifically, a power battery 15 is provided inside the fuselage 1b to supply power to the underwater propeller 3 and each rotating motor 214. The power supply line between the power battery 15 and the underwater propeller 3 and the rotating motor 214 is also equipped with an electronic speed regulator 14 to control the rotation speed of each propeller 21 and the propulsion power of the underwater propeller 3 respectively.

[0063] Furthermore, the cross-media aircraft is equipped with a built-in flight control device, which includes sensors and an onboard computer. The sensors include but are not limited to attitude sensors and positioning modules. The onboard computer controls the operation of the propeller 21, the slipstream rudder 22 and the bidirectional water pump 43 according to the information data measured by the sensors.

[0064] A cross-media flight system includes a ground measurement and control station and the above-mentioned cross-media aircraft. The ground measurement and control station includes a control terminal with built-in display and control software. The control terminal is connected to the onboard computer of the cross-media aircraft through uplinks and downlinks.

[0065] A cross-medium attitude adjustment method is applicable to the above-mentioned cross-medium aircraft when the cross-medium aircraft needs to dive from the water surface:

[0066] S1 - Start the two-way water pump 43 to fill the water storage bag 42 with water, so that the head 1a of the body 1 is immersed in water;

[0067] S2-Continue to inject water into the water storage bag 42 until the entire trans-medium aircraft is immersed in water;

[0068] S3-control the bidirectional water pump 43 to keep running to prevent the water in the water storage bag 42 from flowing out.

[0069] When a cross-medium aircraft needs to fly out from underwater:

[0070] A1-Start the two-way water pump 43 to pump out the water in the water storage bag 42, so that the body 1 floats up and the nose 1a of the body 1 points upward;

[0071] A2-After the body 1 floats to the water surface, the propeller 21 is started to drive the cross-medium aircraft upward;

[0072] A3-After the trans-medium aircraft is completely airborne, the bidirectional water pump 43 is turned off.

[0073] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A foldable propeller, characterized in that: The propeller comprises a hub with controlled rotation, a limiting structure provided at the end of the hub, and a plurality of blades evenly arranged around the axis of the hub, each of the blades being hinged to the hub, the hinge axis between the blade and the hub being perpendicular to the rotation axis of the hub, and the limiting structure being located at the front end of the hub along the direction of the pulling force generated when the blade rotates with the hub; When the hub rotates, the blades hinged to the hub rotate and expand under the action of centrifugal force until they are against the limit structure; when the hub stops rotating, the blades hinged to the hub are retracted close to the rotation axis of the hub due to their own weight or fluid resistance during underwater flight.

2. A cross-medium aircraft, characterized in that: The invention comprises a teardrop-shaped centrally symmetrical body having a nose and a fuselage, wherein the nose of the body is located at the front side of the fuselage, and the body is provided with an underwater power mechanism for providing underwater flight power and an aerial power mechanism for providing aerial flight power, wherein the aerial power mechanism is the foldable propeller according to claim 1.

3. The cross-medium aircraft according to claim 2, characterized in that: The cross-medium aircraft further includes a water entry and exit attitude adjustment mechanism, the water entry and exit attitude adjustment mechanism including a watertight compartment provided inside the nose, a flexible water storage bag located within the watertight compartment, and a two-way water pump connected to the water storage bag, one flow channel of the two-way water pump being connected to the water storage bag, and the other flow channel being connected to the rear end of the fuselage; The bidirectional water pump adjusts the overall density of the aircraft and the position of the center of mass of the aircraft along the long axis of the fuselage by changing the water storage volume in the water storage bag. When the water in the water storage bag switches between an empty state and a full state, the numerical variation range of the overall density of the aircraft includes the density value of water; when the water in the water storage bag is emptied and the trans-medium aircraft floats on the water surface, the center of mass of the aircraft is located behind the metacenter.

4. The cross-medium aircraft according to claim 3, characterized in that: An empty compartment is also provided at the rear end of the fuselage, and a water hole communicating with the empty compartment is opened at the rear end of the fuselage; When the empty compartment is filled with water and the water in the water storage bag is emptied, the overall density of the trans-medium aircraft is less than the density of water.

5. The cross-medium aircraft according to claim 2, characterized in that: The sides of the fuselage are connected to four or six fixed wings, and the trailing edges of the fixed wings are provided with controlled rotating slipstream fins, wherein the rotation axis of the slipstream fins is parallel to the wing surfaces of the fixed wings and perpendicular to the long axis of the fuselage; When the fuselage is connected to four fixed wings, two of the fixed wings are used as wings symmetrically distributed on both sides of the fuselage, and the remaining two fixed wings are symmetrically arranged on both sides of the plane where the wings are located, forming two mutually symmetrical vertical tails; When the fuselage is connected to six fixed wings, two of the fixed wings are used as wings symmetrically distributed on both sides of the fuselage, and the remaining four fixed wings are arranged in pairs on both sides of the plane where the wings are located. The two fixed wings in the same pair are located on the same side of the plane where the wings are located, and form a V-shaped vertical tail.

6. The cross-medium aircraft according to claim 5, characterized in that: The fixed wing is a delta wing.

7. The cross-medium aircraft according to claim 5, characterized in that: Taking the wing surface of the fixed wing as a reference plane, when the slipstream fin rotates relative to the fixed wing, the angular range of the slipstream fin relative to the wing surface is ±30°.

8. The cross-medium aircraft according to claim 5, characterized in that: For the slipstream fin and the propeller connected to the same fixed wing, the slipstream fin is arranged in the slipstream area of ​​the propeller.

9. The cross-medium aircraft according to claim 5, characterized in that: The cross-medium aircraft also includes a rotating motor for driving each propeller to rotate and a power battery for supplying power to all the rotating motors. The power supply line between the power battery and the rotating motor is also provided with an electronic speed regulator to control the rotation speed of each propeller separately.

10. The cross-medium aircraft according to claim 9, characterized in that: The underwater power mechanism includes an underwater propeller connected to the rear end of the fuselage, the underwater propeller is also powered by a power battery, and the electronic speed regulator is also connected to the power supply circuit between the power battery and the underwater propeller.

11. The cross-medium aircraft according to any one of claims 5 to 9, characterized in that: The underwater power mechanism is an underwater propeller connected to the rear end of the fuselage.

12. The cross-medium aircraft according to claim 11, characterized in that: The fixed wing of the trans-medium aircraft is further connected to a supporting structure, and the rear end of the supporting structure is located at the rear side of the underwater propeller.

13. The cross-medium aircraft according to claim 11, characterized in that: The underwater power mechanism includes an underwater propeller connected to the rear end of the fuselage, the water inlet and the water outlet of the underwater propeller are respectively located at the front end and the rear end of the underwater propeller, and a plurality of diversion gaps are opened on the edge of the rear end of the fuselage, and the diversion gaps are evenly arranged around the circumference of the fuselage.

14. The cross-medium aircraft according to any one of claims 2 to 10, characterized in that: The cross-medium aircraft also includes a flight control device for controlling the flight attitude. The flight control device includes sensors and an onboard computer. The sensors include an attitude sensor and a positioning module. The onboard computer controls the operation of the air power mechanism, the underwater power mechanism, and the water entry and exit attitude adjustment mechanism based on the information data measured by the sensors.

Images