Amphibious transporter based on ground effect

Abstract

The amphibious transport plane based on the ground effect comprises a plane body, a main wing and a vertical empennage, the main wing is located behind the gravity center of the plane body, a pair of forward-swept front wings are further arranged in front of the gravity center of the plane body, and the vertical empennage is arranged on the main wing; a first propeller is arranged on each of the left and right sides of the head of the fuselage; a pair of second propellers is arranged at the front end of the main wing; a fault step is arranged in the middle of the fuselage. The aircraft has the beneficial effects that the aircraft obtains a great lift-drag ratio in a ground effect area by utilizing the ground effect, the aircraft is lifted up through an airflow air cushion, and the airflow angle of the engine is accurately controlled by utilizing a popular engine tilting technology, so that the aircraft is prevented from falling off. Therefore, low-oil-consumption, large-load, short-distance take-off and low-speed landing are achieved, and the take-off and landing performance of the seaplane is greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of aircraft, and in particular relates to an amphibious transport aircraft based on ground effect. Background Art

[0002] Seaplanes are aircraft that can take off, land and park on the water. They are mainly used for maritime patrols, anti-submarine warfare, rescue, sports, tourism, commuting, aerial photography, etc. The weaknesses of seaplanes are significant. Since water takeoff and landing require good water tightness, the structural weight and flight resistance of seaplanes are relatively large, and the load, range, speed, etc. are not as good as ordinary land-based aircraft of the same level. What is even more unacceptable in terms of combat is that the belly of the seaplane's ship-shaped fuselage is used for water skiing and cannot be equipped with doors, so the fuselage bomb bay cannot be used; and missiles and other weapons are mounted on the wings. If they take off and land on the water, the external weapons will also be subject to the strong impact of the waves and are easily damaged. In addition, seaplanes are in direct contact with seawater, and they also take more effort in corrosion resistance and maintenance than land-based aircraft.

[0003] Apart from the hull, the wing and tail layout of advanced seaplanes are similar to those of most transport aircraft. Therefore, research on large seaplanes at home and abroad is mainly about how to overcome the shortcomings of seaplanes, especially how to ensure that seaplanes can take off and land safely. The speed of seaplanes during takeoff and landing cannot be too high. If the landing speed is too high, fatigue fracture will inevitably occur in the internal structure of the fuselage due to multiple takeoffs and landings, thus affecting the overall life of the seaplane.

[0004] Therefore, a new layout of watercraft is needed to improve the aircraft's load-bearing performance, take-off and landing performance, and low-speed flight performance. Summary of the invention

[0005] In view of this, the present invention aims to propose an amphibious transport aircraft based on ground effect, and proposes a new layout method to improve the aircraft's load-bearing performance, take-off and landing performance, and low-speed flight performance.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] An amphibious transport aircraft based on ground effect, comprising a fuselage, a main wing and a vertical tail, wherein the main wing is located behind the center of gravity of the fuselage, a pair of forward-swept front wings are arranged in front of the center of gravity of the fuselage, and the vertical tail is arranged on the main wing;

[0008] A first propeller is disposed on each of the left and right sides of the fuselage head; a pair of second propellers is disposed at the front end of the main wing;

[0009] A step is arranged in the middle of the fuselage.

[0010] Preferably, the installation angle of the front wing is greater than that of the main wing, and the vertical installation position of the front wing is lower than that of the main wing.

[0011] Preferably, the front wing is a mid-monoplane wing, the main wing is a high-monoplane wing, and the main wing is provided with a cutting winglet;

[0012] The aspect ratio of the front wing is small, and the aspect ratio of the main wing is large.

[0013] Preferably, an elevator is provided on the rear side of the canard, a rudder is provided at the end of the vertical tail, and flaps and ailerons are provided on the rear side of the main wing; and a buoy is also included, which is installed below the wingtip of the canard through a wingtip end plate.

[0014] Preferably, the airfoil of the front wing is MH114, with a wingspan of 900 mm; the leading edge sweep angle of the wing is 8°-10°, the installation angle is 6°, the average geometric chord length is 175 mm, the average aerodynamic chord length is 176.19 mm, and the wing area is 0.21 m 2 , wing root chord length 200mm, wing tip chord length 150mm; aspect ratio 6.86, root tip ratio 1.33;

[0015] The main wing has a rearward-shifted and curved airfoil of MH115, with a wingspan of 1500 mm. The main wing installation angle gradually changes from 4° at the wing root to 2° at the wing tip. The average geometric chord length is 176.8 mm, the average aerodynamic chord length is 190.4 mm, and the wing area is 0.29 m 2 , wing root chord length 200mm, wing tip chord length 10mm, aspect ratio 8.48;

[0016] The center of gravity of the transport aircraft is 400 mm from the leading edge of the middle of the front wing;

[0017] The maximum thickness position of the main wing is 31.7% of the average aerodynamic chord length from the leading edge, and the maximum camber is 7.3%;

[0018] The main wing is a rectangular wing.

[0019] Preferably, connecting rods are provided on both sides of the fuselage head, and the first propeller is installed on the connecting rods through a tilt motor. The tilt motor is composed of a servo and a motor. The servo can control the motor angle by rotating, and finally control the axial angle of the first propeller.

[0020] Preferably, the step-rectifying shape is an inclined step.

[0021] Preferably, when the maximum take-off weight of the aircraft is 10 kg, the step length is 15 mm and the step height is 10 mm.

[0022] Preferably, the transport aircraft model can also be applied to other aircraft that use ground effect to achieve short-distance takeoff.

[0023] Preferably, during the control process, the aircraft flies in the ground effect area when there is no wind or the wind speed is less than the wind and wave bearing capacity limit of the aircraft. After the wind speed reaches the wind and wave bearing capacity limit of the aircraft, the flight control sends a command to autonomously control the aircraft to take off and cruise at high altitude.

[0024] The advantages and positive effects of the present invention are:

[0025] The present invention studies and analyzes the step and proposes a new type of unconventional water transport aircraft layout, which uses the ground effect to enable the aircraft to have excellent take-off and landing performance and low-speed flight performance.

[0026] The ground effect is used to make the aircraft obtain a great lift-to-drag ratio in the ground effect zone, and the aircraft is "lifted" by the "air flow cushion". The more popular engine tilt technology is used to accurately control the engine airflow angle, thereby achieving "low fuel consumption, high load, short-distance takeoff, and low-speed landing", greatly improving the take-off and landing performance of seaplanes.

[0027] The innovation of the present invention lies in the aircraft layout, hull step optimization, flight mode, etc. Among them, the innovations of the aircraft layout and flight mode are both to cleverly utilize the ground effect to greatly increase the cruise lift-to-drag ratio, improve the cruising distance, cruise speed and effectively shorten the sea take-off and landing distance of the sea transport aircraft, so that it can take off and land in a short distance and effectively unload the heavy load of the seaplane landing on the water. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 is a top view of the present invention;

[0030] Figure 2 It is a right side view of the present invention;

[0031] Figure 3 It is a schematic diagram of the fuselage plane step;

[0032] Figure 4 It is a schematic diagram of the oblique steps of the fuselage;

[0033] Figure 5 It is a schematic diagram of the fuselage curved surface steps;

[0034] Figure 6 It is the resistance-time curve of the plane fault when the fault height is 10mm and the length is 15mm;

[0035] Figure 7 It is the resistance-time curve of the inclined plane step when the step height is 10mm and the length is 15mm;

[0036] Figure 8 It is the resistance-time curve of the surface step when the step height is 10mm and the length is 15mm;

[0037] Fig. 9 It is the resistance-time curve of the inclined plane step when the step height is 10mm and the length is 25mm;

[0038] Fig.10 It is the resistance-time curve of the inclined fault when the fault height is 10mm and the length is 35mm;

[0039] Fig.11 It is a schematic diagram of the flight envelope of the present invention.

[0040] Fig.12 It is the lift-time curve of the aircraft flying in the ground effect area;

[0041] Fig.13 It is the drag-time curve of the aircraft flying in the ground effect area;

[0042] Fig.14 It is the lift-time curve of the aircraft flying in the non-ground effect area;

[0043] Fig.15 It is the drag-time curve of an aircraft flying in the non-ground effect area.

[0044] In the figure:

[0045] 1. Main wing 2. Front wing 3. Vertical tail 4. First propeller

[0046] 5. Second propeller 6. Elevator 7. Flaps 8. Aileron

[0047] 9. Step 10. Rudder 11. Float 12. Wing tip end plate DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0050] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the structure of the device components will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and height should be included.

[0051] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0052] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0053] An amphibious transport aircraft based on ground effect, such as Figure 1-2 As shown, it includes a fuselage and a main wing 1, the main wing 1 is located behind the center of gravity of the fuselage, and a pair of forward-swept canards 2 are also arranged in front of the center of gravity of the fuselage. There are two vertical tails 3, which are arranged on the main wing; the canards 2 are placed in the front to generate positive lift, and the overall layout is similar to that of a tandem wing, except that the canards 2 can also play a role similar to that of a horizontal tail, providing a nose-up moment to balance the nose-down moment of the main wing 1.

[0054] In this layout, the entire aircraft can greatly increase the total lift and reduce the induced drag, achieving fuel efficiency of the transport aircraft, maximizing the transport efficiency while meeting the take-off and landing performance.

[0055] A first propeller 4 is arranged on each of the left and right sides of the fuselage head; carbon tubes are arranged on both sides of the fuselage head as connecting rods, and the first propeller is installed on the connecting rods through a tilt motor, and the tilt motor is composed of a servo and a motor. The servo can control the motor angle by rotating, and finally control the axial angle of the first propeller; a pair of second propellers 5 are arranged at the front end of the main wing; the second propeller 5 is fixed to the main wing through a motor and a connector.

[0056] A step 9 is arranged in the middle of the fuselage.

[0057] The step 9 can divide the fuselage into two parts, the front body and the rear body. The front part of the front body and the rear body are tilted upward, and the rear part of the front body is the main sliding surface. At low speed, the front body and the rear body are in contact with water. At this time, the aircraft is mainly supported by the static buoyancy of the water. When the speed gradually increases, the hydrodynamic lift increases, the hull is lifted, and the hull waterline gradually moves backward. At this time, the step has two functions. The first function is to generate a huge negative pressure to resist the deadweight of the aircraft and the suction of water on the fuselage; the second function is that the high-speed water flow of the front hull flows through the step and the retracted curved surface of the rear hull throws the high-speed water flow out so that it no longer flows along the hull, greatly reducing the wetted area of ​​the rear hull and reducing the suction of seawater to help the aircraft take off quickly. At the same time, the existence of the step can also effectively reduce the occurrence of dolphin jumps, which is conducive to improving the motion stability of the seaplane and greatly improving the sliding efficiency. However, the existence of the step will inevitably interrupt the streamline shape of the bottom of the fuselage when the aircraft is in the cruising state, which will generate a large aerodynamic resistance. In this regard, we conducted corresponding research on the steps to obtain the optimal solution for the steps of amphibious aircraft during take-off and cruising phases. Figure 3-5 They are plane fault steps, oblique fault steps and curved fault steps.

[0058] First, determine the step width according to the hull weight, then determine the step height, and finally determine the step length. Different aircraft may determine different values ​​for the step width and height.

[0059] Step width calculation Where W is the maximum take-off weight of the aircraft, where W = 10 kg, ρw is the density of seawater, where ρw = 1025 kg / ㎡, and C is the static load coefficient, which is 0.6. Substituting each parameter into the equation, it can be obtained that the step width is approximately equal to 120 mm.

[0060] The step height hst / Bst is generally around 0.05, and here it is taken as 0.08, which gives hst=10mm. The step length here is taken as 15mm as the basic value.

[0061] We studied the effect of the step-rectification shape on drag reduction and takeoff negative pressure area. When the step height is 10mm and the step length is 15mm, we studied the effect of different step-rectification shapes on drag reduction and takeoff negative pressure area. We studied the original step and the step after rectification, and conducted a simulation of sea takeoff in Fluent.

[0062] Rectification analysis results: the resistance from plane step to inclined plane rectification and curved surface rectification is continuously reduced, and the absolute value of the minimum negative pressure in the negative pressure area increases first and then decreases. Figure 6 , Figure 7 , Figure 8 . Through the resistance results in the report definition, it can be found that the resistance from plane step to inclined step is greatly improved, while the resistance from inclined step to curved step is not much improved. When the minimum pressure of the inclined step is -35000pa, there is still a large area of ​​blue (blue is the minimum pressure), and when the minimum pressure of the curved step is -20000pa, most of the step area has turned green (cannot reach the minimum pressure), and the original plane step has no blue negative pressure area when the minimum pressure is -20000pa. The above characteristics show that the minimum negative pressure of the inclined step is much smaller than the minimum negative pressure of the curved step and the plane step. The existence of the negative pressure area can form an air cushion at the rear of the aircraft when flying at high speed to cut off the high-speed water flow, reduce the hull wetting area, and greatly reduce the suction of water on the aircraft during takeoff. This result shows that the negative pressure area of ​​the inclined step is more advantageous during the takeoff stage.

[0063]

[0064] Table 1 Resistance size at different stages of each fault step

[0065] When the height of the slope step is 10 mm, we study the effect of the step length on drag reduction and negative pressure area:

[0066] The length of the slope step is extended to 15 mm, and the fluid analysis is performed on the step lengths of 25 mm and 35 mm respectively. The analysis results of resistance-time are shown in Fig. 9 , Fig.10 ,Compared with the length of 15mm, the resistance of 25mm and 35mm gradually decreases. It can be concluded that the longer the length of the slope step is, the smaller the resistance is. When the height of the slope step is 10mm and the length is 25mm, the minimum pressure is around -15000pa, and when the height is 10mm and the length is 35mm, the minimum pressure is around -12000pa, indicating that the longer the length of the step is, the smaller the absolute value of the minimum negative pressure in the negative pressure area is.

[0067]

[0068] Table 2 Resistance size of different step lengths

[0069]

[0070] Table 3 Drag reduction benefits of different step lengths

[0071] It was finally determined that the stepped rectification shape is a sloped stepped shape. When the maximum take-off weight of the aircraft is 10kg, the step length is 15mm, the step height is 10mm, the cruise drag reduction rate is 8.8%, the absolute value of the minimum negative pressure is about 35000Pa, and the minimum negative pressure is reduced by more than 15000Pa.

[0072] The rear side of the cantilever is provided with an elevator 6, the end of the vertical tail is provided with a rudder 10, and the rear side of the main wing is provided with a flap 7 and an aileron 8. The elevator 6 on the cantilever can not only provide a lifting moment, but also play a flap-like role. When taking off, the rudder surface deflects downward to achieve a short-distance takeoff effect with the help of the strong airflow of the ground effect. It also includes a buoy 11, which is installed below the wing tip of the cantilever 2 through the wing tip end plate 12.

[0073] The canard 2 is a mid-wing, the main wing 1 is an upper wing, and the main wing 1 is provided with a cutting winglet. Because the canard 2 is to utilize the ground effect, a mid-wing or a lower wing must be used. In order to ensure that the control surface (elevator) on the canard can reduce the impact of waves, a mid-wing is selected, which will inevitably reduce the ground effect. However, by controlling the direction of the slipstream through the tilt motor and the wingtip end plate, a strong air cushion can be formed under the canard. At this time, the elevator can act as a flap-like role, and by bending the wing to compress the strong air cushion downward to generate a large upward reaction force to achieve short-distance takeoff and landing. The main wing 1 adopts an upper wing, which avoids the central wing box from occupying too much fuselage volume, thereby reducing the load, and at the same time facilitates opening the tail compartment to load and unload cargo.

[0074] The installation angle of the canard 2 is greater than the main wing 1, and the vertical installation position of the canard 2 is lower than the main wing 1. The canard 2 and the main wing 1 are arranged in layers in the vertical direction, which avoids the situation that the main wing 1 is affected by the downwash airflow of the canard 2. The present invention is a transport aircraft. In order to ensure the stability of the aircraft, the canard needs to stall before the main wing. When the angle of attack is too large, the canard will stall in advance and the lift it provides will drop sharply, and the aircraft will be automatically balanced by the nose-down moment. In order to achieve the above effect, under the same conditions, the installation angle of the canard is greater than the main wing, which will cause the airflow to flow through the canard to produce a large downwash. If the main wing is located within the influence range of the canard downwash airflow, it will cause the effective angle of attack of the main wing to decrease, thereby reducing the lift generated. In order to increase the lift coefficient of the whole aircraft, the horizontal canard and the rear main wing are arranged in layers in the vertical direction, and the installation position of the canard is lower than the main wing, which avoids the situation that the main wing is affected by the downwash airflow of the ground effect wing.

[0075] The aspect ratio of the front wing is small, that is, the wingspan is short and the chord is long, which can increase the structural rigidity. The high structural strength is mainly used for takeoff in the ground effect area. The ground effect area is 0-1 average aerodynamic chord length. The longer the chord length, the stronger the ground effect at the same flight altitude.

[0076] The main wing has a large aspect ratio. The main lift is generated during level flight for high-altitude cruising. The main wing has a larger aspect ratio than the front wing. The lift of the front wing is smaller than that of the main wing during high-altitude cruising. The lift generated by the tilt motor at a certain deflection angle offsets the nose-down moment. The center of gravity of the aircraft must be ahead of the neutral point of the entire aircraft for the aircraft to be stable longitudinally. If the neutral point of the entire aircraft is farther away from the center of gravity, the more unstable it is and the more it needs to rely on the flight control system. The main wing generates the main lift during cruising, which is similar to the wing of a general transport aircraft. The front wing is used as a ground effect wing and is mainly used for short-distance takeoff using ground effect. In order to ensure that the lift gain generated by the ground effect wing in the weak ground effect area makes the neutral point of the entire aircraft move forward no more than the center of gravity or not much more, the area of ​​the ground effect wing cannot be very large. At the same time, the structural strength and flight altitude in the ground effect area also require the aspect ratio of the ground effect wing to be small.

[0077] We also conducted various analyses on the wing (wing airfoil) selection, as shown in Table 4:

[0078] Table 4 Airfoil optimization and selection

[0079] The airfoil of the front wing is MH114, with a wingspan of 900 mm; the leading edge sweep angle of the wing is 8°-10°, the installation angle is 6°, the average geometric chord length is 175 mm, the average aerodynamic chord length is 176.19 mm, and the wing area is 0.21 m 2 , wing root chord length 200mm, wing tip chord length 150mm; aspect ratio 6.86, root tip ratio 1.33;

[0080] The main wing has a rearward-shifted and curved airfoil of MH115, with a wingspan of 1500 mm; the main wing installation angle gradually changes from 4° at the wing root to 2° at the wing tip, with an average geometric chord length of 176.8 mm, an average aerodynamic chord length of 190.4 mm, and a wing area of ​​0.29 m 2 The wing root chord length is 200mm, the wing tip chord length is 10mm, and the aspect ratio is 8.48; the maximum thickness position of the main wing is 31.7% of the average aerodynamic chord length from the leading edge, and the maximum curvature is 7.3%; the main wing is a rectangular wing.

[0081] After determining the parameters of the wing, the wing modeling was performed in XFlr5 and all the mass points of the fuselage were added. The aircraft aerodynamics were analyzed using the nonlinear lift line theory, vortex lattice method and surface source method. The center of gravity of the aircraft was found to be 400 mm from the leading edge of the forward swept wing on the horizontal axis. The stability of the aircraft was analyzed using 3D Panels and VLM (vortex lattice method). The longitudinal, heading and roll modes of the aircraft were all converged, that is, the aircraft could automatically return to its original flight state after being disturbed. The pitch moment was small during 0° level flight.

[0082] Connecting rods are arranged on both sides of the fuselage head, and the first propeller is installed on the connecting rods through a tilt motor. The tilt motor is composed of a steering gear and a motor. The steering gear can control the motor angle by rotating, and finally control the axial angle of the first propeller.

[0083] Ground effect refers to the phenomenon that when an aircraft flies close to the ground or water, the air cushion formed between the wing and the ground or water surface increases the pressure on the lower surface of the wing and the lift. At the same time, the presence of the ground or water surface weakens the downwash of the wing, increasing the lift-to-drag ratio and reducing the induced drag.

[0084] The conventional upper wing and T-shaped tail layout is not the optimal solution for transport aircraft that require the wings to provide strong lift. The tail needs to provide a huge negative lift in order to balance the entire aircraft. Lw (lift generated by the wing) = W (weight of the entire aircraft) + Lt (negative lift generated by the horizontal tail). At this time, the main wing will generate a huge induced drag.

[0085] From the perspective of aerodynamic shape layout design, the present invention innovatively proposes an "unconventional layout" to achieve low-speed flight performance, superior take-off and landing performance and innovative load-bearing capacity. The present invention innovatively proposes an unconventional layout in which the "horizontal tail" is placed in front and swept forward, the main wing is placed in the rear, and the double vertical tails are at the rear.

[0086] The canard 2 is also called the ground effect wing, which is located before the center of gravity, and the main wing is located after the center of gravity. Both wing surfaces generate positive lift, realizing Lw=W-Lt, which can greatly reduce the induced drag for transport aircraft. At the same time, the canard (ground effect wing) is swept forward to make the spanwise flow of the wing surface flow from the wing tip to the wing root, so that the boundary layer accumulates at the wing root. At this time, the propeller slipstream located in front of the wing root blows the wing root to increase the kinetic energy of the airflow accumulated at the wing root, thereby increasing the lower limit of the aircraft stall and improving the low-speed flight performance of the aircraft. The main wing is increased with a slanted winglet to weaken the wingtip vortex and reduce the induced drag. In addition, the slipstream blown by the propeller installed before the canard can form an air cushion between the horizontal canard and the sea surface (ground), which can quickly help the transport aircraft take off on water. The movable rudder on the canard is the "elevator". When the aircraft takes off, the rudder needs to be deflected downward. At this time, the elevator can act as a flap to obtain high lift.

[0087] The present invention cruises in the ground effect area when there is no wind and the wind speed is slow. At this time, the lift-to-drag ratio of the whole aircraft is large, and the economic benefit of cruising is high. When the wind speed is higher, the waves on the water surface are larger, and the waves will hinder the water-skimming cruising of the aircraft. When the wind speed reaches 13m / s (21 knots) (the wind and wave bearing capacity limit of this embodiment), the flight control sends a flight mode switching instruction, and the aircraft cancels the fixed altitude cruise and leaves the ground effect area to cruise at high altitude. Wind speed V w The airspeed V can be measured by the pitot tube A and ground speed V L Get the tailwind V w =V L -V A ; V when against the wind w =V L +V A , see the specific flight envelope Fig.11 .

[0088] We perform fluent aerodynamic analysis on the aircraft flying in and out of the ground effect area to obtain the aerodynamic benefits of the aircraft when flying in the ground effect area, ground effect and non-ground effect lift and drag-time see Figure 12-15 .

[0089]

[0090] Table 5 Pneumatic characteristics of the whole machine

[0091] During the control process, the aircraft flies in the ground effect area (the height of the ground effect area is 0-1 mean aerodynamic chord length) when there is no wind or the wind speed is less than the limit of the aircraft's wind and wave bearing capacity. When the wind speed reaches the limit of the aircraft's wind and wave bearing capacity, the flight control will issue a command to autonomously control the aircraft to take off and cruise at high altitude.

[0092] The protection of this patent is not limited to the field of transport aircraft, but also covers any modified aircraft in any field that uses ground effect to achieve short-distance takeoff.

[0093] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. An amphibious transport aircraft based on ground effect, comprising a fuselage, a main wing and a vertical tail, characterized in that: The main wing is located behind the center of gravity of the fuselage, a pair of forward-swept front wings are also arranged in front of the center of gravity of the fuselage, and the vertical tail is arranged on the main wing; A first propeller is disposed on each of the left and right sides of the fuselage head; a pair of second propellers is disposed at the front end of the main wing; A step is arranged in the middle of the fuselage.

2. The amphibious transport aircraft based on ground effect according to claim 1, characterized in that: The installation angle of the front wing is greater than that of the main wing, and the vertical installation position of the front wing is lower than that of the main wing.

3. The amphibious transport aircraft based on ground effect according to claim 1, characterized in that: The front wing is a mid-monoplane wing, the main wing is a high-monoplane wing, and the main wing is provided with a cutting winglet; The aspect ratio of the front wing is small, and the aspect ratio of the main wing is large.

4. The amphibious transport aircraft based on ground effect according to claim 1, characterized in that: The rear side of the front wing is provided with an elevator, the end of the vertical tail is provided with a rudder, the rear side of the main wing is provided with a flap and an aileron; and a buoy is also included, and the buoy is installed below the wing tip of the front wing through a wing tip end plate.

5. The amphibious transport aircraft based on ground effect according to claim 1, characterized in that: The airfoil of the front wing is MH114, with a wingspan of 900 mm; the leading edge sweep angle of the wing is 8°-10°, the installation angle is 6°, the average geometric chord length is 175 mm, the average aerodynamic chord length is 176.19 mm, and the wing area is 0.21 m 2 , wing root chord length 200mm, wing tip chord length 150mm; aspect ratio 6.86, root tip ratio 1.33; The main wing has a rearward-shifted and curved airfoil of MH115, with a wingspan of 1500 mm. The main wing installation angle gradually changes from 4° at the wing root to 2° at the wing tip. The average geometric chord length is 176.8 mm, the average aerodynamic chord length is 190.4 mm, and the wing area is 0.29 m 2 , wing root chord length 200mm, wing tip chord length 10mm, aspect ratio 8.48; The center of gravity of the transport aircraft is 400 mm from the leading edge of the middle of the front wing; The maximum thickness position of the main wing is 31.7% of the average aerodynamic chord length from the leading edge, and the maximum camber is 7.3%; The main wing is a rectangular wing.

6. The amphibious transport aircraft based on ground effect according to claim 1, characterized in that: Connecting rods are arranged on both sides of the fuselage head, and the first propeller is installed on the connecting rods through a tilt motor. The tilt motor is composed of a steering gear and a motor. The steering gear can control the motor angle by rotating, and finally control the axial angle of the first propeller.

7. The amphibious transport aircraft based on ground effect according to claim 1, characterized in that: The step-breaking rectification shape is an inclined step-breaking.

8. The amphibious transport aircraft based on ground effect according to claim 7, characterized in that: When the maximum take-off weight of the aircraft is 10kg, the step length is 15mm and the step height is 10mm.

9. The amphibious transport aircraft based on ground effect according to claim 1, characterized in that: The transport aircraft model can also be applied to other aircraft that use ground effect to achieve short-distance takeoff.

10. The amphibious transport aircraft based on ground effect according to claim 1, characterized in that: During the control process, the aircraft flies in the ground effect area when there is no wind or the wind speed is less than the aircraft's wind and wave bearing capacity limit. When the wind speed reaches the aircraft's wind and wave bearing capacity limit, the flight control system issues a command to autonomously control the aircraft to take off and cruise at high altitude.

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