Low-altitude aircraft with high flight stability
By designing axial flow ducted fan arrays and airflow guide ducts on low-altitude aircraft, the stability and control challenges of low-altitude aircraft in complex flow fields have been solved, achieving highly stable flight and expanding the scope of applications.
Patent Information
- Application Number
- CN202511455019.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-13
- Publication Date
- 2025-12-12
AI Technical Summary
Existing low-altitude aircraft have poor flight stability in complex flow field environments, unstable lift and high control difficulty, shortened component life, and limited application scenarios.
An axial flow ducted fan array is adopted, which includes multiple axial flow ducted fans with adjustable speed evenly arranged on a large diameter circumference and configured with a shrinkable air guide duct. The load placement tray is installed at the center of the circumference and connected by connectors to form a stable lift source and mass distribution. The large diameter circumference enhances the effect of rotational inertia and torque cancellation.
It achieves stable lift in complex flow fields, reduces rotational angular acceleration, avoids tipping and falling, extends component life, and expands application scenarios.
Smart Images
Figure CN121106799A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of low-altitude flight technology, specifically to a low-altitude aircraft with high flight stability. Background Technology
[0002] Although low-altitude aircraft technology is becoming increasingly mature and widely used, civilian low-altitude aircraft still have significant shortcomings in their flight adaptability in complex flow field environments, and they suffer from the following technical problems: Poor lift stability and uniformity: Rotary-wing low-altitude aircraft, whose core feature is hovering, operate in complex flow fields. While their flight speed is on the same order of magnitude as the flow field velocity, the magnitude and direction of the flow field velocity vector are disordered in time and space. This makes it difficult for the rotor to maintain a stable and uniform incoming flow field as designed, easily leading to high rotor leading angle of attack and flow separation on the rotor surface. Moreover, this flow separation varies significantly with time and space, resulting not only in a substantial decrease in the rotor's resultant lift and a complex lift distribution along the spanwise direction, but more importantly, the variable direction of the resultant lift makes it impossible for the vertical component to overcome the weight of the low-altitude aircraft and its payload, directly threatening altitude maintenance.
[0003] Flight control is difficult: The instability and unevenness of lift will put low-altitude aircraft in a state of inherent vibration and adverse stress, which will greatly increase the difficulty of flight control, seriously deteriorate the stable flight capability, and in extreme cases, cause low-altitude aircraft to lose control and cause overturning and crashing accidents.
[0004] Shortened component lifespan: Vibrations and adverse stresses caused by complex flow fields will accelerate the wear and tear of key components such as rotors, significantly reducing their service life.
[0005] Limited application scenarios: Complex flow fields frequently occur in practical applications, such as severe convective weather, highway tunnels, areas near high-rise buildings with wind flow, and wind fields formed by strong sunlight in mountainous areas. However, existing technologies lack effective countermeasures and can only passively avoid these scenarios, which greatly limits the service range and application capabilities of low-altitude aircraft. Summary of the Invention
[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a low-altitude aircraft with high flight stability, good lift stability, simple flight control, and expanded application scenarios.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A low-altitude aircraft with high flight stability includes an axial flow ducted fan array, a load storage tray, connectors, and segmented arc connecting rings; The axial flow ducted fan array includes multiple axial flow ducted fans with individually adjustable speeds. The multiple axial flow ducted fans are evenly arranged on the same circumference, and the diameter of the circumference is much larger than the diameter of the axial flow ducted fans. All axial flow duct fans are equipped with the same contraction-type air guide duct downstream, with the air outlet of the contraction-type air guide duct facing downwards, and adjacent axial flow duct fans are connected by segmented arc connecting rings located on the circumference. The load tray is installed at the center of the circumference of the axial flow ducted fan array, and the load tray is connected to the axial flow ducted fan by circumferentially distributed connectors.
[0008] Furthermore, the circumference diameter of the axial flow ducted fan array is at least five times the diameter of the axial flow ducted fan.
[0009] Furthermore, the circumference of the axial flow ducted fan array is divided into four quadrants, and multiple equal numbers of axial flow ducted fans are arranged on the circumference of each quadrant, and the total number of axial flow ducted fans is a multiple of four.
[0010] Furthermore, the axial ducted fans in each quadrant rotate in the same direction, while the axial ducted fans in adjacent quadrants rotate in opposite directions.
[0011] Furthermore, the connector bends and protrudes towards the circumferential center, and the position of the load-bearing tray is higher than the position of the segmented arc connecting ring.
[0012] Furthermore, the length of the connector is adjustable to accommodate load trays of different diameters.
[0013] Furthermore, load-bearing trays are commonly used equipment for placing low-altitude aircraft.
[0014] Furthermore, it also includes a power supply and a control system, the power supply being used to provide electrical energy to the axial flow ducted fan and the control system, and the control system being used to regulate the operating status of the axial flow ducted fan.
[0015] In summary, the present invention has the following advantages: To address the issue of poor lift stability, this invention addresses this problem by uniformly arranging axial flow ducted fans on a large-diameter circumference and configuring a contracting guide duct downstream of the axial flow ducted fans. On one hand, the contracting guide duct enhances the lift force of the axial flow ducted fans; on the other hand, it regulates the axial airflow field inside the axial flow ducted fans, ensuring that the axial airflow velocity can be maintained at a level above 30 meters per second (the velocity inside the contracting guide duct is slightly higher than the axial airflow velocity of the axial flow ducted fans), far exceeding the airflow velocity of the complex flow field outside the axial flow ducted fans. This results in… The airflow relative to the blades of the axial ducted fan helps to suppress the direct, unstable, uneven impact with a significant angle of attack on the leading edge of the fan blades caused by the complex airflow turbulence outside the axial ducted fan (similar to the effect of rectification), reducing the probability and range of flow separation on the surface of the fan blades; finally, multiple uniformly distributed axial ducted fans form an array of lift sources. Even if some fans experience significant lift fluctuations due to flow field turbulence, the remaining fans can still provide relatively stable lift supplementation, avoiding a significant decrease or drastic change in the overall lift resultant force, and ensuring that the lift component in the vertical direction is sufficient to overcome the weight of the fuselage and load; To address the challenge of flight control, this invention arranges axial-flow ducted fans evenly on a large-diameter circle, distributing the mass of the low-altitude aircraft as far as possible along the outer edge of the circle. The increased mass distribution radius significantly enhances the system's moment of inertia. Simultaneously, the large diameter of the circle places each axial-flow ducted fan in a different flow field region within the highly turbulent flow field. This difference in flow field scale reduces the correlation of the torques acting on each fan, enhancing the torque cancellation effect. The combined effect of increased moment of inertia and enhanced torque cancellation significantly reduces the angular acceleration of the low-altitude aircraft, preventing overturning and crashes caused by excessively large turns. The normal motion of this aircraft in the horizontal plane is accomplished by utilizing the speed difference thrust principle, which is well-known in aviation technology and applicable to multi-lift source aircraft.
[0016] The structural design of this invention enables low-altitude aircraft to maintain stable lift and attitude in highly turbulent flow fields such as severe convective weather, highway tunnels, near high-rise buildings, and strong sunlight and wind fields in mountains. This breaks through the limitation of existing low-altitude aircraft passively avoiding turbulent flow fields, allowing them to perform flight missions in more scenarios and expanding their application scope. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the structure of the low-altitude aircraft of the present invention.
[0018] In the picture: 1-Load-bearing tray, 2-Segmented arc connecting ring, 3-Axial flow duct fan, 4-Connector. Detailed Implementation
[0019] The present invention will now be described in further detail.
[0020] like Figure 1 As shown, a low-altitude aircraft with high flight stability includes an axial flow ducted fan array, a load storage tray 1, a connector 4, and a segmented arc connecting ring 2. The axial flow ducted fan array includes multiple individually adjustable axial flow ducted fans 3, which are evenly arranged on the same circumference, and the diameter of the circumference is much larger than the diameter of the axial flow ducted fans 3; preferably, the diameter of the circumference on which the axial flow ducted fan array is located is at least five times the diameter of the axial flow ducted fans 3.
[0021] All axial flow ducted fans 3 are equipped with the same downward-facing converging air duct, and adjacent axial flow ducted fans 3 are connected by segmented arc connecting rings 2 located on the circumference. The load tray 1 is installed at the center of the circumference of the axial flow ducted fan array, and the load tray 1 and the axial flow ducted fan 3 are connected by circumferentially distributed connectors 4.
[0022] Furthermore, the circumference of the axial flow ducted fan array is divided into four quadrants, and multiple equal numbers of axial flow ducted fans 3 are arranged on the circumference of each quadrant, and the total number of axial flow ducted fans 3 is a multiple of four.
[0023] Furthermore, the axial ducted fans 3 in each quadrant rotate in the same direction, while the axial ducted fans 3 in adjacent quadrants rotate in opposite directions.
[0024] Furthermore, the connector 4 bends and protrudes towards the circumferential center, making the height of the load tray 1 higher than the height of the segmented arc connecting ring 2. By bending and protruding the connector 4, the load tray 1 is positioned at a certain height above the segmented arc connecting ring 2, preventing the load from directly contacting turbulent airflow or being interfered with by fan airflow. This slows down the wear and tear of critical components, extends their service life, and concentrates the load in the central position, preserving the balance of the fuselage mass distribution around the circumference, ensuring the design effect of the moment of inertia, and further maintaining flight stability.
[0025] Furthermore, the length of the connector 4 is adjustable to accommodate load trays 1 of different diameters.
[0026] Furthermore, the load-bearing tray 1 is a common device for placing low-altitude aircraft.
[0027] Furthermore, it also includes a power supply and a control system. The power supply provides electrical energy to the axial flow ducted fan 3 and the control system, and the control system is used to regulate the operating status of the axial flow ducted fan 3.
[0028] Working principle: When a low-altitude aircraft carrying a certain load is in a complex flow field, as a rigid body system, its motion conforms to the requirements of the following equations:
[0029] The rotation angle of the rigid body in the above equation is The right side of the equation represents the distributed force. F e torque ; Moment of inertia of a rigid body system about the z-axis J z Defined by the following formula:
[0030] r For rotational mass m The distance to the axis of rotation.
[0031] For an object in a complex flow field, the forces acting on its various parts, regardless of magnitude or direction, exhibit a complex spatial distribution. This complex spatial distribution intensifies with increasing spatial distance, leading to stronger cancellation of torques on the object. Therefore, the larger the diameter of the axial-flow ducted fan array on the circumference of a low-altitude aircraft, the smaller the vector sum of the torques acting on the entire aircraft. Simultaneously, a larger diameter results in a larger rotational mass. m Distance to the pivot r It is also larger, and the magnitude and distance of the moment of inertia are also greater. r The acceleration is proportional to the square of the circumference. The combined effect of these two factors results in a significant decrease in the rotational angular acceleration of the low-altitude aircraft of this invention as the diameter of the circumference increases. This achieves high flight stability for the low-altitude aircraft of this invention and reduces the risk of it overturning and crashing.
[0032] When the low-altitude aircraft of this invention takes off, in the initial state, each axial-flow ducted fan 3 rotates at the same speed, which can adapt to the low-speed airflow field. At this time, the aircraft flies upward (the total lift force of the axial-flow ducted fans 3 is greater than the weight and load of the aircraft) / downward (the total lift force of the axial-flow ducted fans 3 is less than the weight and load of the aircraft) with an almost horizontal attitude. When entering a complex flow field, tilting and ascent / descending motion will occur. Since the aircraft of this invention has the ability to maintain a stable state, it can absorb a certain intensity of shear flow in the flow field. The most unfavorable situation for this invention is strong vertical shear flow. When such a continuous strong shear flow occurs in the flow field, the aircraft will tilt to one side. At this time, due to the deviation of the thrust direction of the axial-flow ducted fans 3 from the vertical direction of gravity, the aircraft will automatically tend to move away from the strong shear flow area. That is to say, the aircraft will be blown away from the strong wind area and enter the weak wind area, thereby restoring a stable flight attitude. The shear flow on the horizontal plane has a relatively weak impact on the aircraft because the axial velocity inside the axial ducted fan 3 is more than 30 meters per second, which is much higher than the velocity in the external airflow field in the horizontal direction. This helps to suppress the generation of separation flow inside the axial ducted fan 3, thereby enabling the axial ducted fan 3 to maintain high operating efficiency, that is, to generate sufficient lift force to ensure the flight status of the aircraft.
[0033] As a design based on a passive control concept, the low-altitude aircraft of this invention does not require additional control mechanisms and corresponding energy consumption. Therefore, the high-stability flight method it achieves has a clear principle, simple structure, and significant and reliable effects. Furthermore, it is eco-friendly, energy-saving and noise-reducing, widely applicable, simple and easy to implement, and thus economical and efficient.
[0034] Application Examples Application Example 1: In severe convective weather of a certain intensity. Because of its high stability flight capability, the aircraft of this invention can assist in tasks such as regional disaster relief, key point lighting, and line inspection, so that people's normal lives are not disrupted by severe weather conditions.
[0035] Application Example 2: Highway tunnels. The constant flow of high-speed traffic creates a strong shear flow field in the narrow space of the tunnel. At the same time, the distributed airflow of the ventilation system creates localized complex flow areas, posing a challenge to the high stability of the aircraft's flight capabilities. This is where the low-altitude aircraft of this invention comes in handy.
[0036] Application Example 3: Near tall buildings with a certain wind speed. Near tall buildings, when there is a certain wind speed, whether it is the top of the building, or the front, back and two sides, due to the change in the cross-section of the airflow channel, there will be accelerated flow in some places, decelerated flow in others, and vortex flow in still others. When an aircraft flies in such an area, it is constantly traversing various different flow field states. The aircraft of this invention can also perform well in this situation.
[0037] Application Example 4: Mountainous wind fields under strong sunlight. In mountainous areas, when sunlight is intense, the surface temperature rises sharply, causing a significant decrease in air density near the surface. This density difference drives an updraft, which in turn draws in high-density air from mid-air and washes it down, creating a complex spatial flow field with alternating updrafts and downdrafts. The aircraft of this invention can be perfectly suited to this situation.
[0038] The low-altitude aircraft of this invention has a significant high stability flight capability. Its emergence has expanded the adaptability of low-altitude aircraft to the complexity of the flow field in the flight area. Moreover, it utilizes mature axial flow ducted fan equipment. By selecting appropriate models and quantities, it achieves high stability flight capability with a simple structure. It is convenient and simple to implement and has a very wide range of applications.
[0039] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A low-altitude aircraft with high flight stability, characterized in that: Includes axial flow ducted fan array, load storage tray, connectors and segmented arc connecting rings; The axial flow ducted fan array includes multiple axial flow ducted fans with individually adjustable speeds. The multiple axial flow ducted fans are evenly arranged on the same circumference, and the diameter of the circumference is much larger than the diameter of the axial flow ducted fans. All axial flow duct fans are equipped with the same contraction-type air guide duct downstream, with the air outlet of the contraction-type air guide duct facing downwards, and adjacent axial flow duct fans are connected by segmented arc connecting rings located on the circumference. The load tray is installed at the center of the circumference of the axial flow ducted fan array, and the load tray is connected to the axial flow ducted fan by circumferentially distributed connectors.
2. The low-altitude aircraft according to claim 1, characterized in that: The circumference diameter of the axial flow ducted fan array is at least five times the diameter of the axial flow ducted fan.
3. The low-altitude aircraft according to claim 1, characterized in that: The circumference of the axial flow ducted fan array is divided into four quadrants. Each quadrant has a number of equal axial flow ducted fans arranged on its circumference, and the total number of axial flow ducted fans is a multiple of four.
4. The low-altitude aircraft according to claim 3, characterized in that: The axial flow ducted fans in each quadrant rotate in the same direction, while the axial flow ducted fans in adjacent quadrants rotate in opposite directions.
5. The low-altitude aircraft according to claim 1, characterized in that: The connector bends and protrudes towards the center of the circumference, and the position of the load-bearing tray is higher than the position of the segmented arc connecting ring.
6. The low-altitude aircraft according to claim 1, characterized in that: The length of the connector is adjustable to accommodate load trays of different diameters.
7. The low-altitude aircraft according to claim 1, characterized in that: Load trays are commonly used devices for placing low-altitude aircraft.
8. The low-altitude aircraft according to claim 1, characterized in that: It also includes a power supply and a control system. The power supply provides electrical energy to the axial flow ducted fan and the control system, and the control system is used to regulate the operating status of the axial flow ducted fan.