CN112173080A - Variable-pitch rotor wing structure and control method thereof - Google Patents
Variable-pitch rotor wing structure and control method thereof Download PDFInfo
- Publication number
- CN112173080A CN112173080A CN202011020945.1A CN202011020945A CN112173080A CN 112173080 A CN112173080 A CN 112173080A CN 202011020945 A CN202011020945 A CN 202011020945A CN 112173080 A CN112173080 A CN 112173080A
- Authority
- CN
- China
- Prior art keywords
- pitch
- variable
- rotor
- motor
- hub
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000001133 acceleration Effects 0.000 claims description 9
- 230000003247 decreasing effect Effects 0.000 claims 2
- 238000010586 diagram Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000006073 displacement reaction Methods 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C11/00—Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
- B64C11/30—Blade pitch-changing mechanisms
- B64C11/44—Blade pitch-changing mechanisms electric
Landscapes
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention belongs to the technical field of helicopter rotors, and discloses a variable-pitch rotor structure and a control method thereof, wherein the rotor structure comprises: the pitch control device comprises a motor, a central propeller hub, a propeller clamp, a variable pitch shaft and a propeller blade; the paddle clamp is connected with the central hub through a variable-pitch shaft, and the central hub is arranged on the motor; there is the contained angle of predetermineeing in pitch-variable axle and rotor plane, predetermine the contained angle and be less than 90 degrees, and the oar presss from both sides can wind pitch-variable axle free rotation and predetermine the angle, has effectively simplified large-scale many rotor crafts and has controlled, provides a simple effectual method for electronic many rotor maximization.
Description
Technical Field
The invention belongs to the technical field of helicopter rotors, and particularly relates to a variable-pitch rotor structure and a control method thereof.
Background
In the process of aircraft development, along with the progress of electronic control technology and the development of battery technology, the electric multi-rotor aircraft becomes the mainstream of small aircraft. The electric multi-rotor aircraft has the advantages of simple structure, small number of parts, low operation requirement, low maintenance cost and wide application in aerial survey, agriculture and forestry plant protection, leisure and entertainment and the like.
As is well known, electric multi-rotor aircrafts rely on high frequency to change the rotating speed of each rotor to realize lift force change, thereby realizing attitude control. Rotor size greatly influences rotor pulling force and efficiency, and to realize carrying the big and efficient many rotor crafts, need adopt bigger size's rotor, however, along with rotor size increases, rotor inertia increases fast, means to realize that the quick change of rotor rotational speed is also more difficult.
In order to solve the problem of difficult variable speed of the rotor, people design a variable-pitch electric multi-rotor, namely, a pitch is increased when the pulling force needs to be increased through a servo actuator, and the pitch is reduced when the pulling force needs to be reduced. By the method, the pulling force of different rotors can be changed rapidly, so that the control response speed of the multi-rotor aircraft is greatly improved. However, the blade pitch-changing mechanism, the servo actuator and other components of the electric pitch-changing multi-rotor make the structure of the electric multi-rotor complicated and increase the cost of use and maintenance. .
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the problem that the large electric multi-rotor wing is difficult to change the rotating speed and simultaneously avoid the problems of complexity and high cost of a variable-pitch electric multi-rotor wing mechanism, the invention provides a variable-pitch rotor wing structure and a control method thereof, which effectively simplify the control of a large multi-rotor wing aircraft and provide a simple and effective method for the large scale of the electric multi-rotor wing.
In order to achieve the purpose, the invention is realized by adopting the following technical scheme.
The first technical scheme is as follows:
a variable-pitch rotor structure, comprising: the pitch control device comprises a motor, a central propeller hub, a propeller clamp, a variable pitch shaft and a propeller blade;
the paddle clamp is connected with the central hub through a variable-pitch shaft, and the central hub is arranged on the motor;
there is the contained angle of predetermineeing in pitch-variable axle and rotor plane, predetermine the contained angle and be less than 90 degrees, and the oar presss from both sides and can wind pitch-variable axle free rotation and predetermine the angle.
The first technical scheme of the invention has the characteristics and further improvements that:
(1) one end of the paddle clamp is provided with a first groove which is downward in an inclined mode, and the central paddle hub is provided with a second groove which is upward in an inclined mode;
the variable-pitch shaft is characterized in that first threaded holes with the same size are formed in two sides of the first groove respectively, second threaded holes with the same size are formed in two sides of the second groove respectively, the variable-pitch shaft penetrates through the first threaded holes and the second threaded holes, and two ends of the variable-pitch shaft are fixed through nuts.
(2) The other end of the paddle clamp is provided with a horizontal groove, and one end of the paddle is fixedly connected in the horizontal groove through a bolt.
(3) The variable pitch rotor structure comprises 2 blades and odd-numbered or even-numbered blades more than 2 blades.
(4) The blade clamp may be a separate component or part of the blade for rotating the blade relative to the hub about the pitch axis.
The second technical scheme is as follows:
a control method for a variable-pitch rotor structure, which is applied to the structure of the first technical scheme, and comprises the following steps:
the acceleration of the motor and the acceleration duration or deceleration duration are controlled, and the blades move relative to the central hub due to inertia, so that the pitch is changed.
The second technical scheme of the invention has the characteristics and further improvements that:
(1) when the motor rotates at a constant speed, the blades are stressed in balance, the blades are kept static relative to the central hub, the blades stably run at a fixed pitch, and at the moment, the lift force generated by the rotor wing is unchanged.
(2) When the motor tends to rotate in an accelerating mode, the central hub accelerates along with the motor, the acceleration of the blades lags behind the hub due to the inertia effect, at the moment, the blades rotate backwards around the pitch changing shaft relative to the central hub, the pitch is increased, and the lift force generated by the rotor wing is increased.
(3) When the motor has the tendency of decelerating and rotating, the central hub decelerates along with the motor, and the deceleration of the blades lags behind the hub due to the inertia effect, at the moment, the blades rotate forwards around the pitch axis relative to the central hub, the pitch is reduced, and the lift force generated by the rotor wing is reduced.
The variable-pitch rotor wing provided by the invention has the advantages of simple and reliable structure, quickness in installation and low cost, effectively simplifies the operation of a large-scale multi-rotor wing aircraft, and provides a simple and effective method for the large-scale electric multi-rotor wing. Can be simple convenient realization displacement control through this variable pitch rotor structure, effectively improve aircraft control and control response speed. Through this displacement rotor structure can effectively reduce control and control in-process, the energy loss that the great change of motor rotational speed leads to has improved flight efficiency.
Drawings
Fig. 1 is a schematic structural diagram of a variable pitch rotor structure according to an embodiment of the present invention;
fig. 2 is a schematic view showing a first preset included angle β between a variable pitch axis and a rotor plane according to an embodiment of the present invention;
fig. 3 is a schematic view illustrating a second preset included angle β between the variable pitch axis and the rotor plane according to the embodiment of the present invention;
fig. 4 is a first schematic structural diagram illustrating a motor rotating at a constant speed in a structure of a variable-pitch rotor structure according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a motor rotating at a constant speed in a structure of a variable-pitch rotor structure according to an embodiment of the present invention;
fig. 6 is a first schematic structural diagram illustrating a motor rotating at an accelerated speed in a structure of a variable-pitch rotor structure according to an embodiment of the present invention;
fig. 7 is a second schematic structural diagram illustrating a motor rotating at an accelerated speed in a structure of a variable-pitch rotor structure according to an embodiment of the present invention;
fig. 8 is a first schematic structural diagram illustrating a motor decelerating rotation in a structure of a variable-pitch rotor structure according to an embodiment of the present invention;
fig. 9 is a second schematic structural diagram illustrating a motor decelerating rotation in the structure of the variable-pitch rotor structure according to the embodiment of the invention;
wherein, 1-motor, 2-central propeller hub, 3-propeller clamp, 4-variable-pitch shaft and 5-blade.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention relates to a variable-pitch rotor structure and a control method thereof. The variable pitch rotor structure comprises a motor 1, a central hub 2, a blade clamp 3, a variable pitch shaft 4 and blades 5.
The paddle is installed on the paddle clamp, and the paddle clamp is connected with central propeller hub through the pitch axis, and central propeller hub installs on the motor. The variable pitch axis and the plane of the rotor wing form a certain included angle. The paddle clamp can rotate around the variable pitch shaft freely for a certain angle.
When the motor rotates at a constant speed, the blades are stressed in balance, the blades are kept static relative to the central hub, the blades stably run at a fixed pitch, and at the moment, the lift force generated by the rotor wing is unchanged.
When the motor tends to rotate in an accelerating mode, the central hub accelerates along with the motor, the acceleration of the blades lags behind the hub due to the inertia effect, at the moment, the blades rotate backwards around the pitch changing shaft relative to the central hub, the pitch is increased, and the lift force generated by the rotor wing is increased.
When the motor has the tendency of decelerating and rotating, the central hub decelerates along with the motor, and the deceleration of the blades lags behind the hub and the motor due to the inertia effect, at the moment, the blades rotate forwards around the variable pitch shaft relative to the central hub, the pitch is reduced, and the lift force generated by the rotor wing is reduced.
Through the control mode, when the tension of the rotor wing needs to be changed, only the rotating speed of the rotor wing needs to be changed in a small range, and meanwhile, the time needed for reaching the target tension is effectively shortened.
Further, the variable-pitch rotor structure can be provided with more than 2 blades with odd or even number, and can be a clockwise rotating blade or a counterclockwise rotating blade.
Further, the blade clamp may be a separate component or may be part of the blade, which functions to allow the blade to rotate about a pitch axis relative to the hub.
Furthermore, the pitch axis is characterized by a specific angle with the rotor plane, which is essential in that the blade rotates around it under the action of inertia, which changes the pitch of the blade. The same effect can be achieved no matter what the included angle is.
Further, the motor of the present variable pitch rotor structure may also be replaced with a fuel engine.
Furthermore, the lift unit formed by the variable-pitch rotor wing structure can be combined or superposed for use.
To visually illustrate the implementation of the present disclosure, an example is given as follows:
as shown in fig. 1, the main components of the present structure include: 1 motor, 2 central hub, 3 paddle clamp, 4 variable pitch shaft, 5 blades.
As shown in fig. 2 and 3, the blades 5 are fixedly connected with the blade clamp 3, the central hub 2 is fixedly connected with the motor 1, the blade clamp 3 is connected with the central hub 2 through the variable pitch shaft 4, the variable pitch shaft 4 and the plane of the rotor wing have a specific included angle β, and the blade clamp 3 can rotate freely by a certain angle by taking the variable pitch shaft 4 as an axis.
As shown in fig. 4 and 5, when the motor 1 keeps rotating at a constant speed, the blades 5 will keep a certain pitch, and at this time, the lift force generated by the blades 5 is not changed.
As shown in fig. 6 and 7, when the motor 1 tends to rotate at an accelerated speed, the blade 5 and the blade clamp 3 rotate backward relative to the central hub 2 around the pitch axis 4 due to the inertia of the blade 5, and the pitch becomes large, so that the lift force generated by the blade 5 increases. Controlling the acceleration and the duration of the acceleration of the motor 1 allows the pitch of the blades 5 to be increased to a specific desired angle.
As shown in fig. 8 and 9, when the motor 1 tends to rotate at a reduced speed, the blade 5 and the blade clamp 3 rotate forward relative to the central hub 2 around the pitch axis 4 due to the inertia of the blade 5, and the pitch becomes smaller, so that the lift force generated by the blade 5 is reduced. The acceleration and deceleration duration of the motor 1 are controlled so that the pitch of the blades 5 can be reduced to a specific required angle.
The variable-pitch rotor wing is simple and reliable in structure, quick to install and low in manufacturing cost, effectively simplifies the operation of a large-scale multi-rotor wing aircraft, and provides a simple and effective method for large-scale electric multi-rotor wing.
Can be simple convenient realization displacement control through this variable pitch rotor structure, effectively improve aircraft control and control response speed.
Through the variable-pitch rotor wing structure, the energy loss caused by the large change of the rotating speed of the motor in the control and manipulation process can be effectively reduced, and the flying efficiency is improved.
The foregoing is merely a detailed description of the embodiments of the present invention, and some of the conventional techniques are not detailed. The scope of the present invention is not limited thereto, and any changes or substitutions that can be easily made by those skilled in the art within the technical scope of the present invention will be covered by the scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. A variable-pitch rotor structure, comprising: the variable-pitch propeller comprises a motor (1), a central propeller hub (2), a propeller clamp (3), a variable-pitch shaft (4) and blades (5);
the paddle clamp is connected with the central hub through a variable-pitch shaft, and the central hub is arranged on the motor;
there is the contained angle of predetermineeing in pitch-variable axle and rotor plane, predetermine the contained angle and be less than 90 degrees, and the oar presss from both sides and can wind pitch-variable axle free rotation and predetermine the angle.
2. A variable pitch rotor structure according to claim 1,
one end of the paddle clamp is provided with a first groove which is downward in an inclined mode, and the central paddle hub is provided with a second groove which is upward in an inclined mode;
the variable-pitch shaft is characterized in that first threaded holes with the same size are formed in two sides of the first groove respectively, second threaded holes with the same size are formed in two sides of the second groove respectively, the variable-pitch shaft penetrates through the first threaded holes and the second threaded holes, and two ends of the variable-pitch shaft are fixed through nuts.
3. A variable pitch rotor structure according to claim 1,
the other end of the paddle clamp is provided with a horizontal groove, and one end of the paddle is fixedly connected in the horizontal groove through a bolt.
4. A variable pitch rotor structure according to claim 1, wherein said variable pitch rotor structure comprises 2 blades and an odd number or an even number of blades greater than 2 blades.
5. A variable pitch rotor structure according to claim 1,
the blade clamp may be a separate component or part of the blade for rotating the blade relative to the hub about the pitch axis.
6. A method for controlling a variable-pitch rotor structure, characterized in that it is applied to a structure according to any one of claims 1 to 5, said method being:
the acceleration of the motor and the acceleration duration or deceleration duration are controlled, and the blades move relative to the central hub due to inertia, so that the pitch is changed.
7. A method of controlling a rotor with variable pitch as claimed in claim 6, wherein the blades are balanced during uniform rotation of the motor, remain stationary with respect to the central hub, and operate at a constant pitch with constant lift generated by the rotor.
8. A method of controlling a variable-pitch rotor structure according to claim 6, wherein when the motor tends to accelerate, the central hub follows the motor and the blade is accelerated by inertia to a position behind the hub, and wherein the blade is rotated backwards about the pitch axis relative to the central hub and the pitch is increased and the lift generated by the rotor is increased.
9. A method of controlling a variable-pitch rotor structure according to claim 6, wherein when the motor tends to decelerate, the central hub follows the motor and the blade decelerates due to inertia to a point where the hub lags behind the deceleration, and wherein the blade rotates forward relative to the central hub about the pitch axis with decreasing pitch and decreasing lift generated by the rotor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011020945.1A CN112173080A (en) | 2020-09-25 | 2020-09-25 | Variable-pitch rotor wing structure and control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011020945.1A CN112173080A (en) | 2020-09-25 | 2020-09-25 | Variable-pitch rotor wing structure and control method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112173080A true CN112173080A (en) | 2021-01-05 |
Family
ID=73943945
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011020945.1A Pending CN112173080A (en) | 2020-09-25 | 2020-09-25 | Variable-pitch rotor wing structure and control method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112173080A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113928540A (en) * | 2021-11-19 | 2022-01-14 | 中国直升机设计研究所 | Helicopter inertia variable-pitch rotor wing |
| CN114435585A (en) * | 2022-01-28 | 2022-05-06 | 清华大学 | Variable pitch fan and pitch control method thereof |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB467488A (en) * | 1935-09-17 | 1937-06-17 | Cyril Dell | Improvements in variable pitch airscrews and the like |
| GB492911A (en) * | 1937-04-06 | 1938-09-29 | Cierva Autogiro Co Ltd | Improvements in and relating to sustaining rotors for aircraft |
| CN201566836U (en) * | 2009-08-10 | 2010-09-01 | 亨利(中国)有限公司 | Bottom-wing type flying body |
| CN105059536A (en) * | 2015-08-07 | 2015-11-18 | 胡家祺 | Rotor wing device with variable pitch and multi-rotor-wing aircraft |
| CN108045572A (en) * | 2017-12-03 | 2018-05-18 | 中国直升机设计研究所 | A kind of compound thrust high-speed helicopter of cross-arranging type |
| US20180362146A1 (en) * | 2017-06-14 | 2018-12-20 | Sanmina Corporation | Tilt-rotor multicopters with variable pitch propellers |
| CN210310858U (en) * | 2019-07-03 | 2020-04-14 | 南京航空航天大学 | Variable-speed driving rotor wing |
| CN210391542U (en) * | 2019-09-12 | 2020-04-24 | 南京木蚁智能科技有限公司 | Periodic pitch changing device without tilting disk |
| CN111252238A (en) * | 2020-03-17 | 2020-06-09 | 南京韬讯航空科技有限公司 | Variable-pitch rotor system module controlled by electric regulation and helicopter |
| CN111268096A (en) * | 2020-03-25 | 2020-06-12 | 湖南韬讯航空科技有限公司 | Steering engine-free variable-pitch rotor system module and helicopter |
| CN111559497A (en) * | 2020-06-19 | 2020-08-21 | 深圳远行智能航空科技有限公司 | Aircraft rotor power device |
| CN211442758U (en) * | 2019-12-11 | 2020-09-08 | 北京中航智科技有限公司 | Folding rotor wing of coaxial unmanned helicopter |
-
2020
- 2020-09-25 CN CN202011020945.1A patent/CN112173080A/en active Pending
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB467488A (en) * | 1935-09-17 | 1937-06-17 | Cyril Dell | Improvements in variable pitch airscrews and the like |
| GB492911A (en) * | 1937-04-06 | 1938-09-29 | Cierva Autogiro Co Ltd | Improvements in and relating to sustaining rotors for aircraft |
| CN201566836U (en) * | 2009-08-10 | 2010-09-01 | 亨利(中国)有限公司 | Bottom-wing type flying body |
| CN105059536A (en) * | 2015-08-07 | 2015-11-18 | 胡家祺 | Rotor wing device with variable pitch and multi-rotor-wing aircraft |
| US20180362146A1 (en) * | 2017-06-14 | 2018-12-20 | Sanmina Corporation | Tilt-rotor multicopters with variable pitch propellers |
| CN108045572A (en) * | 2017-12-03 | 2018-05-18 | 中国直升机设计研究所 | A kind of compound thrust high-speed helicopter of cross-arranging type |
| CN210310858U (en) * | 2019-07-03 | 2020-04-14 | 南京航空航天大学 | Variable-speed driving rotor wing |
| CN210391542U (en) * | 2019-09-12 | 2020-04-24 | 南京木蚁智能科技有限公司 | Periodic pitch changing device without tilting disk |
| CN211442758U (en) * | 2019-12-11 | 2020-09-08 | 北京中航智科技有限公司 | Folding rotor wing of coaxial unmanned helicopter |
| CN111252238A (en) * | 2020-03-17 | 2020-06-09 | 南京韬讯航空科技有限公司 | Variable-pitch rotor system module controlled by electric regulation and helicopter |
| CN111268096A (en) * | 2020-03-25 | 2020-06-12 | 湖南韬讯航空科技有限公司 | Steering engine-free variable-pitch rotor system module and helicopter |
| CN111559497A (en) * | 2020-06-19 | 2020-08-21 | 深圳远行智能航空科技有限公司 | Aircraft rotor power device |
Non-Patent Citations (1)
| Title |
|---|
| 陆洋等: "电控旋翼稳态操纵响应研究", 《航空学报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113928540A (en) * | 2021-11-19 | 2022-01-14 | 中国直升机设计研究所 | Helicopter inertia variable-pitch rotor wing |
| CN113928540B (en) * | 2021-11-19 | 2023-10-27 | 中国直升机设计研究所 | Helicopter inertia displacement rotor wing |
| CN114435585A (en) * | 2022-01-28 | 2022-05-06 | 清华大学 | Variable pitch fan and pitch control method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3251952B1 (en) | Variable directional thrust for helicopter tail anti-torque system | |
| US9758245B2 (en) | Rotor drive system | |
| KR101958246B1 (en) | Convertiplane | |
| US10407163B2 (en) | Aircraft control system and method | |
| EP2511177B1 (en) | Helicopter with cycloidal rotor system | |
| EP3501983A1 (en) | Anti-torque system for a helicopter and method for controlling an anti-torque system for a helicopter | |
| WO2020079649A1 (en) | A quiet redundant rotorcraft | |
| US20100014977A1 (en) | Variable pitch aft propeller vane system | |
| JP2004526630A (en) | Ducted fan vehicle particularly useful as a VTOL machine | |
| US8851415B1 (en) | Magnetic aerodynamic generation lift integrated flight technology with joint electric thrust | |
| CN112173080A (en) | Variable-pitch rotor wing structure and control method thereof | |
| EP3798129A1 (en) | Electric motor for a propeller engine | |
| US8845290B1 (en) | System and method for magnetically and aerodynamically optimized control of rotorhead | |
| US20150037149A1 (en) | Rotorcraft control system for rotorcraft with two or more rotor systems | |
| US3273827A (en) | Propeller-rotor high lift system for aircraft | |
| CN209581870U (en) | Duct plume rotor craft based on cycloid propeller technology | |
| JP7201289B2 (en) | Rotorcraft with propulsion on rotating poles | |
| US10864987B2 (en) | Counter rotating torque drive for rotary wing vehicle propulsion | |
| EP0018114A1 (en) | Thrust devices | |
| EP4144637A1 (en) | Aircraft provided with supporting wings for the cruise flight | |
| CN111942581A (en) | Distributed lift force duck-type layout vertical take-off and landing unmanned aerial vehicle and control method | |
| CN114162338B (en) | Coaxial contra-rotating propeller transmission system capable of independently changing pitch | |
| CN111268117A (en) | Multi-duct aircraft with constant lift force and working method thereof | |
| EP0944522B1 (en) | Hovering aircraft | |
| CN111776208B (en) | Aircraft and rotor head assembly thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210105 |
|
| RJ01 | Rejection of invention patent application after publication |