An aircraft and method of takeoff using distributed propeller slipstream ejection

Abstract

The present application relates to a kind of aircraft for launching take-off by distributed propeller slipstream, comprising fuselage, wing arranged on fuselage, it further includes fixed stake, arresting cable, one end of arresting cable is connected in fixed stake, the other end is connected in aircraft tail, the wing leading edge is provided with multiple propellers for providing power, distributed propeller rotation generates slipstream flowing through the upper and lower surfaces of wing, lift is generated by slipstream, for aircraft carrier or land launching take-off.The present application can be conventionally taken off and landed in the area with airport, can short take-off in the case of insufficient runway condition, does not have the large energy consumption stage of vertical take-off and landing, does not have the flight conversion from vertical to transition, safer, compared with fuel power, each motor can be independently controlled, effectively reduce noise pollution and vibration, propeller distributed along wingspan, can improve lateral control ability, reduce rudder load, realize weight reduction and drag reduction.

Description

Technical Field

[0001] This invention belongs to the field of aircraft design and relates to an aircraft and a takeoff method that utilizes a distributed propeller skid-stream catapult for takeoff. Background Technology

[0002] Distributed Electric Propulsion (DEP) aircraft significantly improve aerodynamic performance through aerodynamic-propulsion coupling effects. Compared to conventionally laid-out aircraft, they not only offer higher propulsion efficiency but, more importantly, fully utilize the distributed propeller slipstream effect to enhance lift at low speeds, enabling short takeoffs and landings. This, in turn, allows for a reduction in wing area, thereby lowering structural weight and cruise drag to meet the demands of long-endurance flights. Compared to conventional aircraft, DEP aircraft offer higher aerodynamic efficiency, economy, and environmental friendliness, making them a new research hotspot in the domestic and international aviation fields.

[0003] For computational research on propeller slipflow, the momentum theory, blade element theory, eddy current theory, and lift line theory are relatively mature approaches. These theoretical methods are computationally efficient, but calculating the slipflow of a single propeller becomes very complex when considering coupling with other propellers or wings. Computational fluid dynamics (CFD) has developed several reliable simulation methods, including the excitation disk method, the multiple reference frame method, and the slip mesh method.

[0004] This invention considers using an electrically driven row of propellers distributed at the leading edge as the power output. The propellers generate slipflow over the upper and lower surfaces of the wing. The rotation of the propellers causes axial and in-plane airflow. Through comprehensive design of parameters such as propeller diameter, number of blades, blade twist angle, blade shape, nacelle, wing area, number of propellers, position, and rotational speed, the slipflow effectively covers and enhances the entire wing surface. Axial acceleration performance is enhanced through propeller design, and the flow velocity on the wing surface is adjusted by changing the propeller speed and pitch. The lift-to-drag ratio is improved by designing a small wing area. Before the aircraft is ejected, arresting cables are used to keep the horizontal velocity relative to the ground at zero. When the lift reaches a critical state equal to gravity, the arresting cables disconnect, and the aircraft instantly generates a maximum horizontal acceleration, instantly increasing its forward velocity and lift, thus achieving ejection. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide an aircraft and takeoff method utilizing distributed propeller skid-stream catapult launch. This aircraft can take off and land conventionally in areas with airports; it can take off short distances when runway conditions are insufficient; it eliminates the high-energy-consuming phase of vertical takeoff and landing; and it eliminates the transition from vertical to horizontal flight, making it safer. Compared to fuel-powered aircraft, each motor can be independently controlled, effectively reducing noise pollution and vibration. The propellers distributed along the wingspan improve lateral control capability, reduce control surface load, and achieve weight and drag reduction.

[0006] The present invention is achieved through the following technical solution.

[0007] An aircraft that utilizes distributed propeller slipstream catapult launch includes a fuselage, wings mounted on the fuselage, a fixed stake, and an arresting cable. One end of the arresting cable is connected to the fixed stake, and the other end is connected to the tail of the aircraft. Multiple propellers for providing power are mounted on the leading edge of the wings. The distributed propellers rotate to generate slipstreams that flow across the upper and lower surfaces of the wings, generating lift through the slipstreams for catapult launch of the aircraft from ships or land.

[0008] The aircraft can be used for normal takeoff when the arresting cable is not connected.

[0009] When the aircraft is connected to the arresting cable, the rotating propeller generates a slipstream that flows over the upper and lower surfaces of the wing. Due to the action of the arresting cable and the fixed stake, the aircraft's horizontal velocity is zero. Lift is generated through the slipstream. When the aircraft reaches a certain lift, the arresting cable is disconnected for the aircraft to take off from ships or land via catapult launch.

[0010] Furthermore, the wing is a fixed wing.

[0011] Furthermore, through the comprehensive design of the propeller diameter, number of blades, blade twist angle, blade shape, nacelle, wing area, number of power units, position, and rotational speed, the entire wing surface slipflow is effectively covered, achieving a good lift generation effect.

[0012] Furthermore, propeller rotation causes axial and in-plane airflow; axial acceleration performance is enhanced through propeller design; and the flow velocity on the wing surface is adjusted by changing the propeller speed and pitch.

[0013] Furthermore, when the aircraft is connected to the arresting cable, the rotating propeller generates slipstream that flows over the upper and lower surfaces of the wing. Lift is generated through the slipstream. When the lift reaches a critical state equal to the weight of the aircraft, the arresting cable disconnects, and the aircraft instantly generates a huge horizontal acceleration, its forward speed increases instantaneously, and the lift increases abruptly, allowing the aircraft to be ejected.

[0014] Furthermore, the propeller is electrically driven.

[0015] A takeoff method for an aircraft using distributed propeller slipstream catapult launch, the aircraft including a fuselage, wings mounted on the fuselage, a fixed stake, and an arresting cable, one end of the arresting cable being connected to the fixed stake and the other end being connected to the tail of the aircraft, the leading edge of the wings being provided with multiple propellers for providing power, the distributed propellers rotating to generate slipstream flowing over the upper and lower surfaces of the wings, and the slipstream generating lift;

[0016] There are two methods for aircraft to take off:

[0017] (i) The runway conditions meet the requirements for conventional takeoff, and the aircraft taxis on the runway for conventional takeoff.

[0018] (II) When runway conditions are insufficient to meet the requirements for conventional takeoff, the aircraft will take off by catapult. Catapult takeoff includes the following steps:

[0019] (1) The aircraft is parked on the runway, and the tail of the aircraft is connected to a fixed pile by an arresting cable to prevent it from moving forward. The arresting cable is in a slack state.

[0020] (2) The propellers on the wings on both sides of the fuselage start, the fuselage generates a forward motion tendency, and the arresting cable changes from a slack state to a taut state.

[0021] (3) The propellers on both sides of the fuselage rotate, generating slip flow on the upper and lower surfaces of the wings, changing the aerodynamic pressure on the upper and lower surfaces of the wings, increasing the lift of the wings. Due to the restraint of the arresting cables and fixed piles, the horizontal speed of the aircraft is zero, and the fuselage reaches the critical lift state and is about to take off.

[0022] (4) When the lift generated by the wing reaches a critical state greater than the weight of the aircraft, the arresting cable is disconnected, the aircraft instantly generates a huge horizontal acceleration, the forward speed increases instantly, the lift increases instantaneously, and the aircraft achieves catapult take-off.

[0023] A thrust propeller is positioned at the leading edge of the wing, with the wing within the propeller wake. The direct effect of the wing on the propeller is a choking effect. This choking effect reduces the propeller's axial velocity, resulting in a decrease in the propeller's advance ratio and an increase in thrust. Another effect of the wing on the propeller comes from the circulation of the wing and the influence of vortices on the propeller, thus affecting the induced velocity of the propeller. The propeller located at the leading edge of the wing will be affected by the upwash airflow of the wing boundary vortices. A thrust propeller is positioned at the leading edge of the wing, with part of the wing within the propeller slipstream, as shown in the attached diagram. Figure 1As shown, the propeller has two effects on the part of the wing located in the propeller slipstream: First, the increased axial velocity of the airflow in the propeller slipstream increases the dynamic pressure on the wing surface. The propeller's operation generates slipstreams flowing across the upper and lower surfaces of the wing, causing axial and in-plane airflow. Because the downdraft reduces the air pressure on the upper surface of the wing, the high-speed spiral slipstream trailed by the propeller alters the original flow pattern of the wing. The propeller injects energy into the airflow, increasing both the dynamic and static pressures on the wing in the slipstream region. Second, the change in the wing's angle of attack caused by the tangential velocity of the airflow in the propeller slipstream leads to changes in the lift distribution. Due to the rotation of the airflow, the local angle of attack on the wing changes, increasing the dynamic pressure in the slipstream region and leading to an increase in local circulation, thus generating incremental lift and induced drag. Furthermore, the area of ​​influence is not limited to the region where the propeller disk is located but extends outwards. High-speed slipstreams delay boundary layer separation and improve flap efficiency, optimizing the slipstream's impact on wings and control surfaces, resulting in better maneuverability and control responsiveness at different flight phases. Before catapult launch, the aircraft is restrained by arresting cables to achieve zero horizontal velocity relative to the ground. When lift reaches a critical point equal to gravity, the arresting cables disconnect, granting the aircraft instantaneous, maximum horizontal acceleration. This leads to a sudden increase in forward velocity and a rapid increase in lift, enabling catapult launch.

[0024] Compared with existing technologies, the advantages of this invention are: it allows for conventional takeoff and landing in areas with runways; it enables short-distance takeoff in areas with insufficient runway conditions; it can utilize existing, widely available helicopter airports and small airports for takeoff; it eliminates the high-energy-consuming phase of vertical takeoff and landing, significantly increasing range and passenger capacity compared to eVTOL; it eliminates the transition phase between vertical takeoff and landing, making it relatively safer; compared to fuel power, each motor can be independently controlled, effectively reducing noise pollution and vibration; the propellers distributed along the wingspan improve lateral controllability, reduce control surface load, and achieve better maneuverability, thus reducing weight and drag; the forward propeller accelerates airflow and increases circulation, which, combined with the relatively small wing area, fully utilizes the distributed propeller slipstream acceleration effect to improve wing lift characteristics; and it meets the requirements of the "Outline for the Development of Green Aviation Manufacturing (2023-2035)". Attached Figure Description

[0025] Figure 1 This is a diagram illustrating the increased lift from the distributed propeller slipstream of the present invention.

[0026] Figure 2 This is a schematic diagram of a new concept aircraft for catapult takeoff using distributed propeller slipstream, according to the present invention.

[0027] Figure 3 This invention presents a schematic diagram of the takeoff preparation (motor start-up) phase of a novel concept aircraft that utilizes distributed propeller slipstream for catapult takeoff.

[0028] Figure 4 This invention presents a schematic diagram of a novel concept aircraft that utilizes distributed propeller slipstream to achieve catapult takeoff and reaches the critical lift state.

[0029] Figure 5 This invention provides a schematic diagram of a novel concept aircraft that utilizes distributed propeller slipstream to achieve catapult takeoff, illustrating the catapult phase achieved by disconnecting the arresting cable.

[0030] In the picture: 1. Airframe, 2. Arresting cable, 3. Fixed stake, 4. Wing, 5. Propeller. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0032] like Figures 1 to 5 As shown, an aircraft that utilizes distributed propeller slipstream catapult launch includes a fuselage 1, wings 4 mounted on the fuselage 1, a fixed stake 3, and an arresting cable 2. One end of the arresting cable 2 is connected to the fixed stake 3, and the other end is connected to the tail of the aircraft. Multiple propellers 5 are mounted on the leading edge of the wings 4 to provide power. The distributed propellers 5 rotate to generate slipstreams that flow over the upper and lower surfaces of the wings 4, generating lift through the slipstreams for catapult launch of the aircraft from ships or land.

[0033] The aircraft can be used for normal takeoff when arresting cable 2 is not connected;

[0034] When the aircraft is connected to arresting cable 2, the propeller 5 rotates to generate slip flow over the upper and lower surfaces of the wing 4. Due to the action of arresting cable 2 and fixed pile 3, the aircraft's horizontal speed is zero. Lift is generated through the slip flow. When the aircraft reaches a certain lift, arresting cable 2 is disconnected for the aircraft to take off from ships or land by catapult.

[0035] Furthermore, the wing 4 is a fixed wing.

[0036] Furthermore, through the comprehensive design of the propeller diameter, number of blades, blade twist angle, blade shape, nacelle, wing area, number of power units, position, and rotational speed, the entire wing surface slipflow is effectively covered, achieving a good lift generation effect.

[0037] Furthermore, the rotation of propeller 5 causes axial and in-plane airflow; axial acceleration performance is enhanced through propeller design; and the flow velocity on the wing surface is adjusted by adjusting the propeller speed and pitch.

[0038] Furthermore, when the aircraft is connected to the arresting cable 2, the rotating propeller 5 generates a slipstream that flows over the upper and lower surfaces of the wing 4. The slipstream generates lift. When the lift reaches a critical state equal to the weight of the aircraft, the arresting cable disconnects, and the aircraft instantly generates a huge horizontal acceleration, its forward speed increases instantly, and the lift increases abruptly, allowing the aircraft to be ejected.

[0039] Furthermore, the propeller 5 is electrically driven.

[0040] A takeoff method for an aircraft that utilizes distributed propeller slipstream catapult launch, the aircraft including a fuselage 1, wings 4 mounted on the fuselage 1, a fixed stake 3, and an arresting cable 2, one end of the arresting cable 2 being connected to the fixed stake 3 and the other end being connected to the tail of the aircraft, the leading edge of the wings 4 being provided with multiple propellers 5 for providing power, the distributed propellers 5 rotating to generate slipstream flowing over the upper and lower surfaces of the wings 4, and the slipstream generating lift;

[0041] There are two methods for aircraft to take off:

[0042] (i) The runway conditions meet the requirements for conventional takeoff, and the aircraft taxis on the runway for conventional takeoff.

[0043] (II) When runway conditions are insufficient to meet the requirements for conventional takeoff, the aircraft will take off by catapult. Catapult takeoff includes the following steps:

[0044] (1) The aircraft is parked on the runway, and the tail of the aircraft is connected to the fixed pile 3 by the arresting cable 2 to prevent it from moving forward. The arresting cable 2 is in a slack state.

[0045] (2) The propellers 5 on the wings 4 on both sides of the fuselage 1 start, the fuselage 1 generates a forward motion tendency, and the arresting cable 2 changes from a slack state to a taut state.

[0046] (3) The propellers 5 on the wings 4 on both sides of the fuselage 1 rotate, generating slip flow on the upper and lower surfaces of the wings 4, changing the aerodynamic pressure on the upper and lower surfaces of the wings 4, and increasing the lift of the wings 4. Due to the restraining effect of the arresting cable 2 and the fixed pile 3, the horizontal speed of the aircraft is zero, and the fuselage 1 reaches the critical lift state and is about to leave the ground.

[0047] (4) When the lift generated by the wing 4 reaches a critical state greater than the weight of the fuselage 1, the arresting cable 2 is disconnected, the fuselage 1 instantly generates a huge horizontal acceleration, the forward speed increases instantly, the lift increases instantaneously, and the aircraft achieves catapult take-off.

[0048] A thrust propeller is positioned at the leading edge of the wing, with the wing within the propeller wake. The direct effect of the wing on the propeller is a choking effect. This choking effect reduces the propeller's axial velocity, resulting in a decrease in the propeller's advance ratio and an increase in thrust. Another effect of the wing on the propeller comes from the circulation of the wing and the influence of vortices on the propeller, thus affecting the induced velocity of the propeller. The propeller located at the leading edge of the wing will be affected by the upwash airflow of the wing boundary vortices. A thrust propeller is positioned at the leading edge of the wing, with part of the wing within the propeller slipstream, as shown in the attached diagram. Figure 1 As shown, the propeller has two effects on the part of the wing located in the propeller slipstream: First, the increased axial velocity of the airflow in the propeller slipstream increases the dynamic pressure on the wing surface. The propeller's operation generates slipstreams flowing across the upper and lower surfaces of the wing, causing axial and in-plane airflow. Because the downdraft reduces the air pressure on the upper surface of the wing, the high-speed spiral slipstream trailed by the propeller alters the original flow pattern of the wing. The propeller injects energy into the airflow, increasing both the dynamic and static pressures on the wing in the slipstream region. Second, the change in the wing's angle of attack caused by the tangential velocity of the airflow in the propeller slipstream leads to changes in the lift distribution. Due to the rotation of the airflow, the local angle of attack on the wing changes, increasing the dynamic pressure in the slipstream region and leading to an increase in local circulation, thus generating incremental lift and induced drag. Furthermore, the area of ​​influence is not limited to the region where the propeller disk is located but extends outwards. High-speed slipstreams delay boundary layer separation and improve flap efficiency, optimizing the slipstream's impact on wings and control surfaces, resulting in better maneuverability and control responsiveness at different flight phases. Before catapult launch, the aircraft is restrained by arresting cables to achieve zero horizontal velocity relative to the ground. When lift reaches a critical point equal to gravity, the arresting cables disconnect, granting the aircraft instantaneous, maximum horizontal acceleration. This leads to a sudden increase in forward velocity and a rapid increase in lift, enabling catapult launch.

[0049] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. An aircraft system utilizing distributed propeller skid-stream catapult launch, comprising a fuselage (1) and wings (4) mounted on the fuselage (1), characterized in that, It also includes a fixed pile (3) and an arresting cable (2). One end of the arresting cable (2) is connected to the fixed pile (3), and the other end is connected to the tail of the aircraft. Multiple propellers (5) for providing power are provided on the leading edge of the wing (4). The distributed propellers (5) rotate to generate slip flow that flows over the upper and lower surfaces of the wing (4), and the slip flow generates lift for the aircraft to take off from the ship or land. When the aircraft is not connected to the arresting cable (2), it can be used for normal takeoff; When the aircraft is connected to the arresting cable (2), the propeller (5) rotates and generates a slip flow that flows over the upper and lower surfaces of the wing (4). Due to the action of the arresting cable (2) and the fixed pile (3), the aircraft's horizontal speed is zero. Lift is generated through the slip flow. When the aircraft reaches a certain lift, the arresting cable (2) is disconnected for the aircraft to take off from the ship or land. By comprehensively designing the propeller diameter, number of blades, blade twist angle, blade shape, wing area, number of propellers, propeller position, and propeller speed, the entire wing surface slipflow is effectively covered, achieving a good lift generation effect. The rotation of the propeller (5) causes axial and in-plane airflow; the axial acceleration performance is enhanced by the propeller design; the flow velocity on the wing surface is adjusted by adjusting the propeller speed and pitch. When the aircraft is connected to the arresting cable (2), the propeller (5) rotates and generates a slipstream that flows over the upper and lower surfaces of the wing (4). The slipstream generates lift. When the lift reaches the critical state equal to the weight of the aircraft, the arresting cable breaks, and the aircraft instantly generates a huge horizontal acceleration, the forward speed increases instantly, the lift increases abruptly, and the aircraft is ejected.

2. The aircraft system for takeoff using a distributed propeller skid-stream catapult as described in claim 1, characterized in that, The wing (4) is a fixed wing.

3. The aircraft system for takeoff using distributed propeller skid-stream catapult as described in claim 1, characterized in that, The propeller (5) is electrically driven.

4. A method for launching an aircraft using a distributed propeller skid-stream catapult launch system as described in any one of claims 1-3, characterized in that, The aircraft system includes a fuselage (1), a wing (4) mounted on the fuselage (1), a fixed stake (3), and an arresting cable (2). One end of the arresting cable (2) is connected to the fixed stake (3), and the other end is connected to the tail of the aircraft. Multiple propellers (5) for providing power are provided on the leading edge of the wing (4). The distributed propellers (5) generate slip flow through the upper and lower surfaces of the wing (4) by rotating, and generate lift through the slip flow. Aircraft take-off method Including the following two types: (i) The runway conditions meet the requirements for conventional takeoff, and the aircraft taxis on the runway for conventional takeoff; (ii) When runway conditions are insufficient to meet the requirements for conventional takeoff, the aircraft shall take off by catapult. Catapult takeoff includes the following steps: (1) The aircraft is parked on the runway, and the tail of the aircraft is connected to the fixed pile (3) by the arresting cable (2) to prevent it from moving forward. The arresting cable (2) is in a slack state. (2) The propellers (5) on the wings (4) on both sides of the fuselage (1) start, the fuselage (1) generates a forward motion tendency, and the arresting cable (2) changes from a relaxed state to a taut state; (3) The propellers (5) on the wings (4) on both sides of the fuselage (1) rotate, generating slip flow on the upper and lower surfaces of the wings (4), changing the aerodynamic pressure on the upper and lower surfaces of the wings (4), increasing the lift of the wings (4). Due to the restraining effect of the arresting cable (2) and the fixed pile (3), the horizontal speed of the aircraft is zero, and the fuselage (1) reaches the critical lift state and is about to leave the ground. (4) When the lift generated by the wing (4) reaches the critical state equal to the weight of the aircraft, the arresting cable (2) is disconnected, the body (1) instantly generates a huge horizontal acceleration, the forward speed increases instantly, the lift increases instantaneously, and the aircraft achieves catapult take-off.

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