A method for longitudinal control of a water take-off and landing of an amphibious aircraft

Abstract

The present application belongs to the water surface take-off and landing control technology field of water surface aircraft, and particularly relates to a kind of amphibious aircraft water surface take-off and landing longitudinal control method.The present application determines the corresponding elevator deflection angle of the aircraft when sliding at the median pitch angle at different speeds through flight test, and when taking off, the corresponding relationship of the flight test speed, median pitch angle and elevator deflection angle is used to draw the elevator control rate curve of the aircraft during the take-off process respectively, so as to obtain the elevator control rate of the aircraft during the take-off process on the static water surface and wave water surface;when landing, the pilot gradually brings the rod after the aircraft touches the water, so that the elevator deflection angle is in the minimum state of the maximum available deflection angle combination until the aircraft completes the deceleration on the water surface.The present application effectively solves the unstable influence caused by the interference of the wave water surface on the take-off and landing of the amphibious aircraft, and improves the take-off and landing safety.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water surface take-off and landing control of water surface aircraft, and particularly relates to a longitudinal control method for water surface take-off and landing of an amphibious aircraft. BACKGROUND

[0002] When the amphibious aircraft takes off and lands on the water surface, the aircraft can only be stably sliding when the pitch attitude angle is within a certain range, that is, the amphibious aircraft has a stable boundary for the longitudinal attitude angle. When the pitch attitude angle of the aircraft exceeds the stable boundary, unstable motion phenomena such as dolphin motion and jumping motion occur, which endangers the safety of take-off. Since the water surface is a soft support, the longitudinal inclination angle of the aircraft before leaving the water changes with the speed, elevator deflection angle, and water surface conditions all the time, especially when taking off on a wave water surface, the longitudinal inclination angle of the aircraft presents a certain amplitude and period of fluctuation characteristics, and the longitudinal motion stability of the aircraft becomes more complex.

[0003] When the aircraft takes off and slides on the static water surface, as long as the pitch attitude angle of the aircraft is within the stable boundary range, the aircraft can maintain stable sliding until take-off. When the water surface sliding longitudinal inclination angle of the aircraft is within the stable boundary range, after the aircraft is disturbed, the aircraft has a self-stabilizing characteristic, that is, after the disturbance disappears, the pitch attitude angle of the aircraft converges to the state before the disturbance within a few oscillation periods. Research shows that even if the disturbance attitude is very large, causing the longitudinal inclination angle of the aircraft to temporarily exceed the stable boundary, the longitudinal inclination angle of the aircraft can converge to the state before the disturbance within a few oscillation periods. However, when the water surface sliding longitudinal inclination angle of the aircraft is on or outside the stable boundary, the aircraft either produces spontaneous unstable motion or produces unstable motion after being disturbed.

[0004] When the aircraft lands on the water surface, the sliding stability characteristics of the aircraft are similar to the take-off stability characteristics. However, after the aircraft lands, the aircraft speed should be reduced as quickly as possible, while avoiding the disturbance of wind and waves on the aircraft. Research shows that the safety of the aircraft sliding at a smaller attitude is poorer than that of the aircraft sliding at a larger attitude, because when the pitch attitude angle of the aircraft is smaller, the area of the front part of the aircraft body participating in water sliding increases, that is, the action center of the wetted area of the body moves forward, and when it exceeds a certain limit, the action center moves to the front of the center of gravity. When the aircraft is disturbed, the water force forms a yawing moment, and even causes rolling, thereby affecting the motion safety of the aircraft. However, when the aircraft moves at a larger pitch attitude angle, the action center of the wetted area of the body moves backward, which is beneficial to enhancing the motion stability of the aircraft. Therefore, from the perspective of motion safety, it is a safer water landing control method for the aircraft to slow down at a larger pitch attitude angle after landing on the water.

[0005] When an amphibious aircraft moves on wave-like water, its pitch angle oscillates with a certain amplitude and period due to wave disturbances. The amplitude and period are affected by wave height, wavelength, and speed. When the amplitude of the pitch angle oscillation exceeds the stable range, the pitch angle may exceed the stability boundary. However, whether unstable motion occurs depends on the aircraft's taxiing attitude angle on calm water in that configuration (i.e., the pitch angle when the aircraft taxis at that speed and elevator deflection angle, called the initial pitch attitude angle).

[0006] Currently, although existing technologies have established control methods for maintaining the attitude of amphibious aircraft during takeoff and landing, they do not specify how to control the attitude angle and control surfaces at different stages of takeoff and landing. Therefore, they are not sufficiently instructive for aircraft takeoff and landing operations and are prone to water-based takeoff and landing hazards. Summary of the Invention

[0007] The purpose of this invention is to provide a control method that can effectively reduce interference, improve the water surface take-off and landing performance of amphibious aircraft, and enhance flight safety.

[0008] The technical solution of this invention is as follows: A longitudinal control method for amphibious aircraft takeoff and landing on water. Through test flights, the elevator deflection angle corresponding to the aircraft's taxiing at a mid-pivot angle at different speeds is determined. During takeoff control, the elevator control rate curves of the aircraft during takeoff are plotted using the test flight speed, mid-pivot angle, and their corresponding elevator deflection relationships, respectively, to obtain the aircraft's elevator control rate during takeoff on calm water and wavy water. During water landing control, after the aircraft touches the water, the pilot gradually pulls the stick to bring the elevator deflection angle to the minimum value among the maximum available deflection angle combinations until the aircraft has decelerated on the water surface.

[0009] Determine the maximum pitch angle α at which the aircraft can taxi stably at different speeds through test flights with a mid-pivot angle. max Minimum pitch angle α min It was obtained after calculation.

[0010] αaveN=(αmax+αmin) / 2.

[0011] Through constant-speed gliding test flights on still water, at the speed V corresponding to the peak drag of the aircraft... hump And the aircraft's speed of leaving the water, V GW Between these points, several speed points are selected at approximately equal intervals, causing the aircraft to move at a constant speed in sequence. By adjusting the aircraft's elevator and changing its planing angle, the maximum pitch angle α at which the aircraft can taxi stably at these speeds is determined. max Minimum pitch angle α min .

[0012] The maximum speed at which the aircraft does not jump is the maximum pitch angle at the speed at which the aircraft can be stably glided max The minimum pitch angle at which the aircraft can be stably glided is the pitch angle at the speed at which the aircraft does not jump min .

[0013] During the take-off process, the speed of the aircraft does not reach V hump Before that, the pilot keeps the elevator inconveniently and focuses on keeping the throttle lever to accelerate the aircraft until the speed reaches V hump .

[0014] After reaching V hump , the pilot gradually controls the elevator deflection angle during the take-off process, and keeps the elevator deflection angle at δ1, δ2, δ3, δ4, …, δN at speeds 1, 2, 3, 4, …, N respectively until the speed of the aircraft reaches V GW off the water.

[0015] After the aircraft touches the water, the pilot gradually brings the lever, so that the elevator deflection angle is in the δmin state, and the aircraft is controlled with a fixed elevator deflection angle until the aircraft is decelerated on the water surface.

[0016] δmin is the minimum value of δmax1, δmax2, δmax3, …, δmaxN by using the maximum safe gliding pitch angle of the aircraft at different speeds and the corresponding elevator deflection angle.

[0017] The technical effect of the present application is that the present application describes a method for determining the wing deflection angle and attitude angle holding range or exact value during different stages of take-off and landing of an aircraft, which can guide the pilot in the take-off and landing operation of an amphibious aircraft on a still water surface and a wave water surface, guide the designer to develop the take-off and landing operation program of the amphibious aircraft on the still water surface and the wave water surface, effectively solve the instability caused by the interference of the wave water surface on the take-off and landing of the amphibious aircraft, improve the safety of take-off and landing, and have good guiding significance for the designer to compile the aircraft manual and the pilot to operate the aircraft. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic diagram of a method for determining a median pitch angle;

[0019] Figure 2 is a schematic diagram of an elevator control law during take-off on a still water surface and a wave water surface;

[0020] Figure 3 is a schematic diagram of an elevator control law during water landing on a still water surface and a wave water surface. DETAILED DESCRIPTION

[0021] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0022] The water surface take-off and landing longitudinal control method of the amphibious aircraft in the present application determines the corresponding elevator deflection angle of the aircraft when sliding at the median pitch angle at different speeds through flight test. When taking off, the flight test speed, the median pitch angle and the corresponding elevator deflection angle are used to draw the elevator control rate curve of the aircraft in the take-off process, so as to obtain the elevator control rate of the aircraft in the take-off process on the static water surface and the wave water surface. When landing, the pilot gradually brings the lever after the aircraft touches water, so that the elevator deflection angle is in the minimum state of the maximum available deflection angle combination until the aircraft completes deceleration on the water surface. Thus, the attitude angle and the control surface are effectively and accurately controlled in different stages of the take-off and landing process, the take-off and landing control of the amphibious aircraft is effectively guided, and the safety of water surface take-off and landing is improved.

[0023] The specific implementation process of the water surface take-off and landing longitudinal control method of the amphibious aircraft in the present application is as follows:

[0024] (1) First, the real machine static water surface constant speed sliding flight test is carried out. Between the speed V hump and the aircraft water leaving speed V GW , N (N>5) speed points are selected at approximately equal intervals, so that the aircraft moves at a constant speed in turn, the elevator of the aircraft is adjusted, the water sliding angle of the aircraft is changed, the maximum pitch angle α max and the minimum pitch angle α min of the aircraft that can stably slide at these speeds are determined (see Table 1), and the deflection angle of the elevator when the aircraft slides at the maximum pitch angle is determined, as shown in Table 2. The basis for determining the maximum pitch angle α max that can stably slide is that the aircraft will not jump when sliding at this pitch angle, but the aircraft will jump when the attitude is greater than α max . The basis for determining the minimum pitch angle α min that can safely slide is that the aircraft will not appear dolphin motion when sliding at this pitch angle, but the aircraft will appear dolphin motion when the attitude angle is less than α min .

[0025] Table 1 Flight test table of maximum and minimum pitch angles for stable sliding

[0026] Speed V hump ]]> Speed 1 Speed 2 Speed 3 Speed 4 … Speed N V GW ]]> Maximum pitch angle — αmax1 αmax2 αmax3 αmax4 … αmaxN — Minimum pitch angle — αmin1 αmin2 αmin3 αmin4 … αminN —

[0027] Table 2 Maximum steady taxiing pitch angle corresponding to elevator deflection test flight table

[0028] Speed V hump ]]> Speed 1 Speed 2 Speed 3 Speed 4 … Speed N V GW ]]> Maximum pitch angle — αmax1 αmax2 αmax3 αmax4 … αmaxN — Corresponding elevator deflection — δmax1 δmax2 δmax3 δmax4 … δmaxN —

[0029] (2) Calculate the average value of the maximum longitudinal pitch angle a max and the minimum longitudinal pitch angle a min of the aircraft that can safely taxi, which is called the median pitch angle, see Figure 1 , which is the determination method of a max , a min , the median pitch angle, the calculation method of the median pitch angle is:

[0030] a aveN = (a max + a min) / 2

[0031] The median pitch angle is the middle position of the stable taxiing range of the aircraft, and the range from the median pitch angle to the upper and lower stable boundaries is equivalent. When the aircraft taxis at the median pitch angle, whether the attitude angle increases after the aircraft is disturbed by the lifting moment or the attitude angle decreases after the aircraft is disturbed by the lowering moment, the stable margin to the stable boundary is the same. Since the disturbance of the lowering moment or the lifting moment is random when the aircraft taxis on the water surface, the aircraft taxis at the median pitch angle to ensure the optimal anti-interference ability of the aircraft.

[0032] Through test flight, the aircraft moves at a constant speed, the elevator deflection angle of the aircraft and the corresponding pitch angle of the aircraft are recorded, and the corresponding elevator deflection angle δ of the aircraft at different speeds when the aircraft taxis at the median pitch angle is obtained, see Table 3.

[0033] Table 3 Median pitch angle corresponding to elevator deflection test flight table

[0034]

[0035] (3) Determination of longitudinal control method during takeoff

[0036] Using the test flight speed, the median pitch angle and the corresponding elevator deflection, the elevator control rate curve of the aircraft during takeoff is drawn respectively, and the elevator control rate of the aircraft during takeoff on the static water surface and the wave water surface is obtained, that is: during takeoff, when the speed of the aircraft reaches V hump , since the pitch angle of the aircraft is mainly affected by the water force, the influence of the elevator surface on the pitch angle is weak, at this time the pilot can not control the elevator, and focus on keeping the throttle lever to accelerate the aircraft. After reaching V hump , the pilot gradually controls the elevator deflection angle, and keeps the elevator deflection angle at δ1, δ2, δ3, δ4, …, δN respectively at speed 1, speed 2, speed 3, speed 4, …, speed N, until the aircraft reaches V GW off the water, please refer to Figure 2 .

[0037] The advantage of the method is that when the speed is less than Vhump, the pilot can focus on accelerating the aircraft, and when the speed reaches Vhump, the pilot controls the elevator according to the rules shown in Table 3 to make the aircraft slide at a neutral pitch angle, improving the adaptability of the aircraft to the environment during take-off and the anti-interference ability of the aircraft.

[0038] (4) Water landing control

[0039] Referring to Table 2, the minimum value of δmax1, δmax2, δmax3, …, δmaxN is taken as δmin using the maximum safe sliding pitch angle of the aircraft at different speeds and the corresponding elevator deflection angle, and the elevator control rate of the aircraft during water landing on a calm water surface or a wave water surface is obtained, that is, after the aircraft touches the water, the pilot gradually pulls the lever to make the elevator deflection angle at δmin state until the aircraft slows down on the water surface (speed less than 3 knots), as shown in Figure 3 During water landing, the pilot does not need to maintain different elevator deflection angles at different speeds as in the take-off process, and the pilot controls the aircraft at a fixed elevator deflection angle to make the aircraft slide stably at a larger pitch angle. The technical advantages of this are: first, to reduce the pilot's control burden, and second, when the aircraft slides at a larger attitude angle, the water dynamic force point position is located at the rear, and the heading anti-interference ability at this time is stronger than that when the aircraft slides at a smaller pitch angle.

[0040] Through the invention, the pilot can be guided to control the amphibious aircraft during take-off and landing on a calm water surface or a wave water surface, or the designer can be guided to develop the take-off and landing control procedure of the amphibious aircraft on a calm water surface or a wave water surface.

[0041] The above is only a specific embodiment of the present application, which is described in detail, and the part not described is a conventional technology. However, the protection scope of the present application is not limited to this, any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application. The protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for longitudinal control of amphibious aircraft taking off and landing on water, characterized in that, Through test flights, the elevator deflection angles corresponding to the aircraft's taxiing at the mid-pivot angle at different speeds were determined. During takeoff control, the elevator control rate curves of the aircraft during takeoff were plotted using the relationship between the test flight speed, the mid-pivot angle, and the corresponding elevator deflection angles. This yielded the elevator control rate of the aircraft during takeoff on calm and wavy water surfaces. During water landing control, after the aircraft touches the water, the pilot gradually pulls the stick to bring the elevator deflection angle to the minimum value among the maximum available deflection angle combinations until the aircraft has decelerated on the water surface. Determine the maximum pitch angle α at which the aircraft can taxi stably at different speeds through test flights with a mid-pivot angle. max Minimum pitch angle α min It was obtained after calculation. αaveN=(α max +a min ) / 2; Through constant-speed gliding test flights on still water, at the speed V corresponding to the peak drag of the aircraft... hump And the aircraft's speed of leaving the water, V GW Between these points, several speed points are selected at approximately equal intervals, causing the aircraft to move at a constant speed in sequence. By adjusting the aircraft's elevator and changing its planing angle, the maximum pitch angle α at which the aircraft can taxi stably at these speeds is determined. max Minimum pitch angle α min ; The maximum speed at which the aircraft will not exhibit jumping motion is the maximum pitch angle α at which it can taxi stably. max When the pitch angle decreases to the point where the aircraft exhibits dolphin-like motion, this pitch angle is the minimum pitch angle α required for stable gliding at that speed. min .

2. The longitudinal control method for water surface takeoff and landing of an amphibious aircraft according to claim 1, characterized in that, During takeoff, the aircraft speed did not reach V. hump Beforehand, the pilot held the elevator steady, focusing on maintaining the throttle to accelerate the aircraft until it reached speed V. hump .

3. The longitudinal control method for water surface takeoff and landing of an amphibious aircraft according to claim 2, characterized in that, During takeoff, reaching V hump Then, the pilot gradually manipulates the elevator deflection angle, maintaining the elevator deflection angle at δ1, δ2, δ3, δ4, ..., δN at speeds 1, 2, 3, 4, ..., N, respectively, until the aircraft speed reaches V. GW Take off from the water.

4. The longitudinal control method for water surface takeoff and landing of an amphibious aircraft according to claim 1, characterized in that, After the aircraft touches the water, the pilot gradually pulls the stick to bring the elevator deflection angle to δmin, and then controls the aircraft with a fixed elevator deflection angle until the aircraft has decelerated on the water surface.

5. The longitudinal control method for water surface takeoff and landing of an amphibious aircraft according to claim 4, characterized in that, in, δmin is the minimum value among δmax1, δmax2, δmax3, ..., δmaxN, which is obtained by taking the maximum safe taxiing pitch angle and the corresponding lift angle of the aircraft at different speeds.

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