Unmanned flying body

Abstract

To provide an unmanned flying body that can effectively obtain a turning force with a plurality of rotors.SOLUTION: An unmanned flying body includes: a plurality of rotors for generating thrust; and a shield part positioned between any two adjacent rotors in plan view and shielding a lower side air current of the two rotors during flight.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an unmanned aerial vehicle.

Background Art

[0002] In recent years, unmanned aerial vehicles such as drones have been utilized in various fields such as facility inspections. . The unmanned aerial vehicle is provided with a plurality of rotors and obtains thrust for lifting. For example, Patent Document 1 discloses a method for controlling the airframe to turn the airframe by providing a difference in the rotational speed of the rotors.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such an unmanned aerial vehicle provided with a plurality of rotors, a technique for more efficiently flying is desired.

[0005] Therefore, the present disclosure has been made in view of the above problems, and an object thereof is to provide an unmanned aerial vehicle capable of efficiently obtaining a turning force by a plurality of rotors.

Means for Solving the Problems

[0006] According to the present disclosure, there is provided an unmanned aerial vehicle including a plurality of rotors for generating thrust, and a shielding portion that is located between any two adjacent rotors in plan view and shields the airflow below the two rotors during flight.

Effects of the Invention

[0007] According to the present disclosure, it is possible to provide an unmanned aerial vehicle capable of efficiently obtaining turning force by a plurality of rotary wings. It can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the present specification and drawings, for components having substantially the same functional configuration , duplicate description is omitted by assigning the same reference numerals.

[0010] <Summary> FIG. 1 is a schematic plan view of an unmanned aerial vehicle (drone) according to an embodiment of the present disclosure. . The unmanned aerial vehicle 1 of this example (hereinafter, also simply referred to as "aerial vehicle") is a rotary wing aircraft that obtains lift and thrust by a plurality of rotary wings. Although the aerial vehicle 1 of this example is an unmanned aerial vehicle, it may be applied to a manned aerial vehicle on which a person can board.

[0011] As shown in the plan view of FIG. 1, the flying object 1 includes a main body portion 1 0 (airframe) located at the center of the flying object in plan view, and a plurality of rotary wings 20 (20A, 20B, 20C, 20D) supported by the main body portion 10 and configured to generate thrust for flight. As shown in the front view of FIG. 2, a shielding portion 30 is provided on the main body portion 10, and is located between two circumferentially adjacent rotary wings (in this example, between the left and right rotary wings) around the main body portion 10. It is configured to block the airflow between the two rotary wings below the rotary wing 20.

[0012] The main body portion 10 is provided with electronic components such as a control unit, a memory unit, a communication unit, a sensor unit, an imaging unit (camera), etc. to be described later, and has a frame for supporting them, a cover for covering the electronic components and the like. The center of gravity of the flying object 1 is preferably located at approximately the center of the main body portion 10 in plan view , but is not limited thereto.

[0013] In this example, the shielding portion 30 is detachably configured on the lower surface side of the main body portion 10. Further, the shielding portion 30 in this example constitutes a battery pack with a rechargeable battery built therein. When the battery runs out, a battery pack with a pre-charged battery can be exchanged together with the shielding portion 30 . The battery can supply power to the rotary wings. At the coupling portion between the shielding portion 30 and the main body portion 10, connectors (contacts) for power supply or signal communication are provided. Inside the shielding portion 30, there may be components constituting at least a part of a memory unit, a control unit, etc. to be described later.

[0014] As shown in FIG. 1, the rotary wings 20 (20A, 20B, 20C, 20D) in this example are in plan view They are arranged at four locations around the main body 10. The number of the rotary wings 20 is not limited to four, and may be three or more, even less than five. Note that the number of blades constituting the rotary wings 20 is not particularly limited, and any shape and any number of blades can be adopted. Also, each rotary wing may be provided with a plurality of blades in the axial direction.

[0015] The flying object 1 in this example includes a left front rotary wing 20A located on the left front side of the main body 10, a right front rotary wing 20B located on the right front side , a left rear rotary wing 20C located on the left rear side, and a right rear rotary wing 20D located on the right rear side. In this example, two rotary wings adjacent to each other in the circumferential direction of the main body 10 are configured to rotate in opposite directions during flight, but they may also rotate in the same direction.

[0016] In this example, the left front rotary wing 20A and the right rear rotary wing 20D are configured to rotate clockwise (CW (Clockwise) direction) in a plan view, and the right front rotary wing 20B and the left rear rotary wing 20C are configured to rotate counterclockwise (CCW (Counterclockwise) direction) in a plan view. Note that the configuration is not limited to this, and they may be configured to rotate in opposite directions respectively.

[0017] Here, a propeller guard extending from the main body 10 may be provided outside the rotary wing (outside in a plan view when viewed from the center of the aircraft). Also, each rotary wing may be provided with a cylindrical propeller duct surrounding the circumference of each rotary wing.

[0018] The rotary wing 20 in this example is supported by a rotary wing support portion (not shown) extending outward from the main body 10. It is held. Also, the rotor 20 is held below the rotor support part. In this example, A motor is located above the propeller that constitutes the rotor 20, and a rotor support part is located above the motor. Note that the rotor 20 may be supported from below by the main body part 10.

[0019] When the flying object 1 hovers in the air, basically the four rotors 20 are rotated at the same rotation speed. Note that the rotation speed of each rotor 20 is appropriately controlled according to the flight environment. For example, information on the flight environment such as the temperature, air pressure, wind speed, and wind direction of the flight space is acquired by various sensors or received from an external device, and based on this information, the flight controller determines the rotation speed of each rotor 20, and an appropriate flight state is maintained.

[0020] When the flying object 1 ascends, the rotation speed of the four rotors 20 is made uniformly larger (faster) than when hovering, and conversely, when descending, the rotation speed is made uniformly smaller ( slower) than when hovering. When the flying object 1 moves forward, the rotation speed of the rear rotors (left rear rotor 20C and right rear rotor 20D) is made larger than that of the front rotors (left front rotor 20A and right front rotor 20B), and when moving backward, conversely, it is made smaller. When the flying object 1 moves leftward, the rotation speed of the right rotors (right front rotor 20B and right rear rotor 20D) is made larger than that of the left rotors (left front rotor 20A and left rear rotor 20C), and when moving rightward, conversely, it is made smaller. Note that the flying object 1 moves while tilting in the moving direction from the reference posture during hovering. When the flying object 1 turns left (counterclockwise), it turns in the clockwise (CW) direction. When the flying object 1 turns left (counterclockwise), it turns in the clockwise (CW) direction. When the flying object 1 turns left (counterclockwise), it turns in the clockwise (CW) direction. When the flying object 1 turns left (counterclockwise), it turns in the clockwise (CW) direction.

[0021] When the flying object 1 turns left (counterclockwise), it turns in the clockwise (CW) direction. The rotational speed of the rotating blades (in this example, the left front rotating blade 20A and the right rear rotating blade 20D) that rotate is made greater than the rotational speed of the rotating blades (in this example, the right front rotating blade 20B and the left rear rotating blade 20C) that rotate counterclockwise (CCW (Counterclockwise) direction), and conversely made smaller when turning to the right so as to turn. This utilizes the fact that a turning torque in the direction opposite to the rotational direction of the rotating blades 20 is generated in the airframe.

[0022] Here, when there is a difference in the rotational speeds of two adjacent rotating blades in plan view, as shown in FIG. 3, an air current (wind) is generated from the rotating blade with a lower rotational speed (rotating blade 20A in FIG. 3) toward the rotating blade with a higher rotational speed (rotating blade 20B in FIG. 3), and a turning torque in the reverse direction of this air current is generated in the airframe.

[0023] FIG. 4 is a plan view showing an aircraft 100 having no shielding part for comparison. As shown in FIG. 4, when the aircraft 100 turns to the left (a counterclockwise turn), an air current is generated from the rotating blades with relatively lower rotational speeds (the right front rotating blade 20B and the left rear rotating blade 20C) toward the rotating blades with higher rotational speeds (the left front rotating blade 20A and the right rear rotating blade 20D), and a turning torque is generated in the reverse direction. In this case, the turning torque T1 due to the air current from the right front rotating blade 20B to the left front rotating blade 20A and the turning torque T2 due to the air current from the left rear rotating blade 20C to the left front rotating blade 20A act in directions that cancel each other out. Similarly, the turning torque T 3 and the turning torque T4 in FIG. 4 also cancel each other out.

[0024] Therefore, as in the example shown in FIG. 5, between two adjacent rotating blades (between the left front rotating blade 20A and the right front rotating blade 20B, and between the left rear rotating blade 20C and the right rear rotating blade 20D), there are shielding parts ​​​Provide 30 to make it difficult for an air current to be generated between the two rotary wings on the lower side of the rotary wings. This suppresses (or reduces) the generation of the turning torques T1 and T3 in FIG. 4, and prevents the turning torques in the opposite directions from canceling each other out. As a result, the turning torques T2 and T4 can be effectively utilized to efficiently turn the aircraft 1. Specifically, in the aircraft 1 shown in FIG. 4, a shielding portion 30 (the front portion thereof) is provided between the two front rotary wings (the left front rotary wing 20A and the right front rotary wing 20B) adjacent to each other in the left-right direction (width direction) of the fuselage, and a shielding portion 30 (the rear portion thereof) is provided between the two rear rotary wings (the left rear rotary wing 20C and the right rear rotary wing 20D) adjacent to each other in the left-right direction (width direction) of the fuselage, so as to reduce the turning torque between the left front rotary wing 20A and the right front rotary wing 20B and the turning torque between the left rear rotary wing 20C and the right rear rotary wing 20D. As a result, the turning torque T2 caused by the air current from the left rear rotary wing 20C to the left front rotary wing 20A and the turning torque T3 caused by the air current from the right front rotary wing 20B to the right rear rotary wing 20D both act as left turning torques, enabling efficient turning. When turning to the right, since the turning torque is generated in the direction opposite to the turning torques T2 and T4 in FIG. 5, efficient turning is also possible in this case. The shielding portion 30 may extend from the front end portion to the rear end portion of the fuselage (main body portion 10), or may be provided only in a part of the front-rear direction of the fuselage. When the aircraft 1 turns clockwise, as shown in FIG. 5, the rotational speed of the rotary wings (in this example, the left front rotary wing 20A and the right rear rotary wing 20D) rotating clockwise is made higher than the rotational speed of the rotary wings (in this example, the right front rotary wing 20B and the left rear rotary wing 20C) rotating counterclockwise. The shielding portion 30 may extend from the front end portion to the rear end portion of the fuselage (main body portion 10), or may be provided only in a part of the front-rear direction of the fuselage. It may also be provided only in a part of the front-rear direction of the fuselage.

[0025] When the aircraft 1 turns clockwise to the right, as shown in FIG. 5, the rotational speed of the rotary wings (in this example, the left front rotary wing 20A and the right rear rotary wing 20D) rotating clockwise is, compared to the rotational speed of the rotary wings Reduce it. As a result, the turning torque T4 due to the airflow from the right rear rotor 20D to the right front rotor 20B and the turning torque T3 due to the airflow from the left front rotor 20A to the left rear rotor 20C both act as right turning torques, enabling efficient turning.

[0026] As described above, in the unmanned aerial vehicle 1 of the present embodiment, a plurality of rotors 20 for generating thrust and a shielding portion 30 located between any two adjacent rotors in a plan view and shielding the airflow below the two rotors during flight are provided. With such a configuration, it becomes possible to efficiently obtain a turning force by the plurality of rotors. The position and size of the shielding portion 30 are preferably set as appropriate according to the rotation direction of the rotors 20, the distance between the rotors 20, and the like.

[0027] The shielding portion 30 is preferably configured to be able to change the shielding amount. According to this, the magnitude of the turning torque can be adjusted by changing the shielding amount. For example, the shielding portion 30 may be configured to be partially detachable. The shielding portion 30 is formed by a plurality of parts coupled via a detachable coupling portion and can be attached and detached. The configuration of the coupling portion is not particularly limited, and may be any one or a combination of a hook mechanism that hooks from one side to the other, claw fitting, coupling by magnetism, screws, surface fasteners, etc. Further, the shielding portion 30 may be configured to be able to change the shielding amount by a slide structure. Specifically, for example, a part of the members of the shielding portion 30 slides in the front-rear direction of the aircraft body and expands and contracts in the front-rear direction, or a part of the members of the shielding portion 30 slides in the vertical direction and expands and contracts in the vertical direction.

[0028] ​​​​​​​​​​​​​​FIG. 6 is a side view of the aircraft 1. The shielding portion 30 may be capable of changing the shielding amount in the vertical direction (the axial direction of the rotor). As shown in FIG. 6, the shielding amount (height H) of the shielding portion 30 in the vertical direction is preferably 1 / 3 or more of the diameter D downward from the lower surface of the rotor 20, but is not limited thereto.

[0029] Also, the shielding portion 30 may be capable of changing the length in the direction perpendicular to the straight line connecting the centers of the two rotors sandwiching the shielding portion 30 in plan view (the front-rear direction of the aircraft in the example of FIG. 1). The shielding amount (each length L in FIG. 6) of the shielding portion 30 in the horizontal direction (the direction perpendicular to the straight line connecting the centers of the two rotors) is preferably 1 / 2 or more of the region between the radially opposite ends of the rotor 20. In other words, it is preferably 1 / 2 or more of the diameter D, but is not limited thereto, and it is sufficient to partially shield the region below the rotors between the two rotors.

[0030] Here, FIG. 7 is a diagram (plan view) showing an example of the hardware configuration of the aircraft 1 according to the present embodiment. As shown in FIG. 7, the aircraft 1 according to the present embodiment has a rotor 20 for generating thrust, a motor 21, and an ESC (Electric Speed Controller) 22. Further, the aircraft 1 includes a flight controller 23 as a control unit in the main body 10. The flight controller 23 can have one or more processors 23b, such as a central processing unit (CPU) or a programmable processor such as an FPGA (Field-Programmable Gate Array). The flight controller 23 has a memory 23a, and an ​​​​​​​​​​​​​is accessible. The memory 23a stores logic, code, and / or program instructions executable by the flight controller 23 to perform one or more steps. The flight controller 23 is an example of a control unit. Further, the flying object 1 in this example includes a camera and / or sensor 24 as an information acquisition unit. Also, the flying object 1 includes a transceiver 25. Note that the configuration of the flying object 1 shown in FIG. 7 is an example, and a rotary-wing aircraft having a configuration different from the main body 10 shown in FIG. 7 may be included in the scope of the present invention. The main body 10 is formed by a frame or the like constituting the flying object 1. The material constituting the main body 10 is not particularly limited, and for example, it can be carbon fiber resin, glass fiber resin, magnesium, magnesium alloy, aluminum, aluminum alloy, steel, titanium, or other materials. The rotary wing 20 is attached to the motor 21. The rotary wing 20 generates lift (thrust) for the flying object 1 by rotating itself due to the rotation of the motor 21. In this embodiment, the rotary wings 20 are provided at four locations on the front, rear, left, and right, but the present invention is not limited to such an example. For example, the rotary wings 20 may be provided at six or eight locations around the airframe. Depending on the structure, shape, equipment, size, etc. of the flying object 1, the number of rotary wings 20 provided can be appropriately changed. The memory 23a may include a removable medium such as an SD card or a random access memory (RAM) or an external storage device. The data acquired from the camera / sensor 24 may be directly transmitted to and stored in the memory 23a. For example, still image / moving image data captured by the camera is recorded in the built-in memory or the external memory.

[0031] The main body 10 is formed by a frame or the like that constitutes the flying object 1. The material that constitutes the main body 10 is not particularly limited, and can be, for example, carbon fiber resin, glass fiber resin, magnesium, magnesium alloy, aluminum, aluminum alloy, steel, titanium, or other materials. The rotary wing 20 is attached to the motor 21. The rotary wing 20 generates lift (thrust) for the flying object 1 by rotating itself due to the rotation of the motor 21. In this embodiment, the rotary wings 20 are provided at four locations on the front, rear, left, and right, but the present invention is not limited to such an example. For example, the rotary wings 20 may be provided at six or eight locations around the airframe. Depending on the structure, shape, equipment, size, etc. of the flying object 1, the number of rotary wings 20 provided can be appropriately changed. The memory 23a may include a removable medium such as an SD card or a random access memory (RAM) or an external storage device. The data acquired from the camera / sensor 24 may be directly transmitted to and stored in the memory 23a. For example, still image / moving image data captured by the camera is recorded in the built-in memory or the external memory.

[0032] The memory 23a may include a removable medium such as an SD card or a random access memory (RAM) or an external storage device. The data acquired from the camera / sensor 24 may be directly transmitted to and stored in the memory 23a. For example, still image / moving image data captured by the camera is recorded in the built-in memory or the external memory. Also, the memory 2 The memory 23a may include a removable medium such as an SD card or a random access memory (RAM) or an external storage device. The data acquired from the camera / sensor 24 may be directly transmitted to and stored in the memory 23a. For example, still image / moving image data captured by the camera is recorded in the built-in memory or the external memory. 3a can appropriately store various types of information, such as information acquired from an external information processing device connected via the signal connector 13, or information transmitted from the control terminal 26.

[0033] The flight controller 23 includes a control module configured to control the state of the aircraft 1. For example, the control module adjusts the spatial arrangement, speed, and / or acceleration of the aircraft 1 having six degrees of freedom (translational motions x, y, and z, and rotational motions θx, θy, and θz) by controlling the motor 21, which is a propulsion mechanism of the aircraft 1, via the ESC11c. The lift of the aircraft 1 is generated by the rotation of the rotor 20 by the motor 21. The flight controller 23 can control the rotational speed of the motor 21 (the rotational speed also means the number of rotations per predetermined time) to adjust the thrust by the rotor 20.

[0034] The flight controller 23 is communicable with a transceiver 25 configured to transmit and / or receive data from one or more external devices (for example, the control terminal 26). The transceiver 25 can use any suitable communication means such as wired communication or wireless communication. The transceiver 25 can utilize one or more of, for example, a local area network (LAN), a wide area network (WAN), infrared, wireless, WiFi, a point-to-point (P2P) network, a telecommunications network, cloud communication, or any other communication method.

[0035] The transceiver 25 transmits data acquired by the sensor 24, processing results generated by the flight controller 23, predetermined control data, user commands from a terminal or a remote controller, etc. can transmit and / or receive one or more of them, and the received information can be stored in a storage unit such as the memory 23a The information obtained by the sensor 24 may be output to the control terminal 26 or an external device via the transceiver 25.

[0036] The control terminal 26 is a device for controlling the flight of the aircraft 1. Note that the flight of the aircraft 1 may be controlled by the operation of an operator on the ground or the like, or by an autonomous flight program based on flight path information and sensing (e.g., GCS (Ground Control ol Station)), or by automatic or manual control. The control terminal 26 may be, for example, a transceiver (prop), a smartphone, a tablet, or other terminal. The control terminal 26 can send flight control instruction information to the flight controller 23.

[0037] The sensor 24 according to the present embodiment may include, for example, an inertial sensor (an inertial measurement device such as an IMU (Inertial Measurement Sensor)), an acceleration sensor, a gyro sensor, a GPS sensor, a wind sensor, a temperature sensor, a humidity sensor, a pressure sensor, an altitude sensor, a proximity sensor such as LiDAR (Laser Imaging Detection and Rangin g), or a vision / image sensor other than a camera. Also the sensor 24 may be mounted on the flight controller 23 or provided outside the flight controller 23. Further, when a camera is provided such a camera may be any camera. For example, the camera may be, in addition to a general camera an infrared camera, a stereo camera, or the like. The camera may be, for example, a self-​ A camera for use in position estimation and a camera for imaging a subject to be imaged may be provided respectively. In the non-flight state, the flying object 1 of this example can remove the battery pack from the main body 10 and charge it. The battery pack may or may not be integrated with the shielding portion 30. Also, the flying object 1 may be provided with a plurality of batteries or may be provided with only one battery.

[0038] As described above, the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. However, the technical scope of the present disclosure is not limited to such examples. Those having ordinary knowledge in the technical field of the present disclosure can conceive of various modifications or correction examples within the scope of the technical idea described in the claims. Obviously, these are also naturally understood to belong to the technical scope of the present disclosure.

[0039] In the above embodiment, such autonomous flight control has been described as being executed by the flight controller 23 of the flying object 1. However, the present technology is not limited to such an example. That is, such an autonomous flight control method is not limited to an example processed at the edge in the flying object. The above-described correction processing may be remotely performed by another autonomous flight control device, and the processing result may be transmitted to the flying object. Based on such a result, the drive unit may be controlled. That is, the main body of the hardware that executes such an autonomous flight control method is not particularly limited, and the above-described functional units may be executed by a plurality of hardware.

[0040] Also, the effects described in this specification are merely illustrative or exemplary and are not limiting. It is not. That is, the technology according to the present disclosure can exhibit other effects that are obvious to those skilled in the art from the description of this specification, together with or instead of the above effects.

[0041] In addition, the following configurations also belong to the technical scope of the present disclosure. (Item 1) A plurality of rotors for generating thrust, A shielding portion located between any two adjacent rotors in plan view and shielding the airflow below the two rotors during flight, and a drone equipped with the same. (Item 2) The drone according to Item 1, wherein any two adjacent rotors rotate in opposite directions to each other. (Item 3) The drone according to Item 1 or 2, wherein the shielding portion is configured to be able to change the shielding amount by partial attachment and detachment. (Item 4) The drone according to any one of Items 1 to 3, wherein the shielding portion is configured to be able to change the shielding amount by a partial sliding structure. (Item 5) The drone according to any one of Items 1 to 4, wherein the shielding portion is configured to be able to change the shielding amount in the vertical direction of the airframe. (Item 6) The drone according to any one of Items 1 to 5, wherein the shielding portion is configured to be able to change the shielding amount in the front-rear direction of the airframe. (Item 7) The drone according to any one of Items 1 to 6, wherein the shielding portion is located between the rotors adjacent to each other in the left-right direction of the airframe. (Item 8) The drone according to any one of Items 1 to 7, wherein the rotors are provided at four locations on the right front side, left front side, right rear side, and left rear side of the airframe. (Item 9) The shielding part has a battery for supplying power to the rotary wing, the unmanned aerial vehicle according to any one of Items 1 to 8. (Item 10) The shielding part extends from the front end part to the rear end part of the airframe, the unmanned aerial vehicle according to any one of Items 1 to 9.

Explanation of Signs

[0042] 1 Aircraft 10 Main body part 20 Rotary wing 30 Shielding part​​

Claims

1. A plurality of rotors for generating thrust; A main body located at the center in the left - right direction of the unmanned aerial vehicle and supporting the plurality of rotors; A shielding portion provided below the main body and positioned between any two adjacent rotors in a plan view, and located below the two rotors during flight. By blocking the airflow between the two rotors, the shielding portion suppresses the turning torque generated on the airframe by the airflow. The shielding portion is provided at least in either the space between the left and right rotors located in front of the unmanned aerial vehicle or the space between the left and right rotors located behind the unmanned aerial vehicle. The unmanned aerial vehicle, wherein the shielding portion does not include a storage portion for cargo transportation.

2. The unmanned aerial vehicle according to Claim 1, wherein any two adjacent rotors rotate in opposite directions to each other.

3. The unmanned aerial vehicle according to Claim 1 or 2, wherein the shielding portion is configured to be able to change the shielding amount by partial detachment.

4. The unmanned aerial vehicle according to Claim 1 or 2, wherein the shielding portion is configured to be able to change the shielding amount in the vertical direction of the airframe.

5. The unmanned aerial vehicle according to Claim 1 or 2, wherein the shielding portion is configured to be able to change the shielding amount in the front - rear direction of the airframe.

6. The unmanned aerial vehicle according to Claim 1 or 2, wherein the shielding portion is detachable from the main body.

7. The rotors are provided at four locations: the right front side, the left front side, the right rear side, and the left rear side of the airframe. The left front - side rotor and the right rear - side rotor rotate in a clockwise direction in a plan view. The unmanned aerial vehicle according to Claim 1 or 2, wherein the right front - side rotor and the left rear - side rotor are configured to rotate in a counter - clockwise direction in a plan view.

8. The unmanned aerial vehicle according to Claim 1 or 2, wherein the shielding portion has a battery for supplying power to the rotors.

9. The unmanned aerial vehicle according to Claim 1 or 2, wherein the shielding portion extends from the front end portion to the rear end portion of the airframe.

Images