Method and system for determining upper limit of pitch angle change value of traction airdrop aircraft

Abstract

The invention belongs to the technical field of aircraft control stability, and particularly relates to a traction airdrop aircraft pitch angle change value upper limit determination method and system, and the method comprises the steps: 1, determining the attack angle limit alpha max1 of the pitch angle change value upper limit; step 2, determining an interference angle limit alpha max2 of a traction parachute cord at the upper limit of a pitch angle change value and a cargo hold exit; step 3, determining an upper limit value thetamax1 of the change of the pitch angle; and 4, determining the upper limit theta max of the pitch angle change by integrating the attack angle limit alpha max1 of the upper limit of the pitch angle change value, the angle limit alpha max2 of the traction parachute cord of the upper limit of the pitch angle change value and the interference angle of the cargo hold exit, and the upper limit theta max1 of the pitch angle change.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft control stability, and specifically relates to a method and system for determining an upper limit of a pitch angle variation value of a towing airdrop aircraft. Background Art

[0002] Tow airdrop is a typical method for transport aircraft to quickly drop heavy equipment and other cargo. According to the number of cargo pieces, it can be divided into tow single drop and tow continuous drop. The aircraft's tow airdrop mission can be summarized into the following stages:

[0003] Phase 1: The cargo hatch is fully opened before the tow airdrop, and the crew achieves stable level flight through control input;

[0004] The second stage: When the appropriate conditions are met, the crew releases the towing parachute, and the cargo moves along the track toward the exit under the action of the towing parachute until it leaves the aircraft;

[0005] Phase 3: After the cargo leaves the aircraft, the crew stabilizes the flight status and flies according to the plan, and the towing airdrop mission is completed.

[0006] Usually, the weight of cargo such as heavy equipment dropped by towing can reach more than 10% of the total weight of the aircraft. The second stage of towing airdrop is the stage with the highest process risk, the most dramatic changes in aircraft status, and the heaviest crew control burden. During this stage, the towing parachute, cargo and aircraft are in relative motion. When the cargo moves toward the exit, it will generate an additional pitch moment to make the aircraft rise rapidly. The additional moment of the cargo will suddenly disappear at the moment of leaving the aircraft, causing the aircraft to quickly lower its head. In addition, during the continuous drop process, the aircraft will repeatedly raise its head and lower its head, causing the aircraft's angle of attack, pitch angle and other key flight parameters to change rapidly in a short period of time. The aircraft is at risk of exceeding the angle of attack, excessive pitch angle, and interference between the towing parachute and the cargo hold exit, endangering flight safety.

[0007] Based on the above situation, towed airdrop is a risky flight subject. It is necessary to control the range of changes in key parameters, thereby limiting the state changes of the aircraft and ensuring the flight safety of the carrier aircraft during the towed airdrop process. However, at present, there is no clear and universal method for determining the upper limits of the angle of attack and pitch angle for towed airdrop missions. Pilots mainly operate within a limited range based on trial and experience. It is not universal and difficult to transplant to other aircraft. It is not conducive to flexible mission execution and expansion of aircraft capabilities, and has great potential risks.

[0008] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0009] The purpose of the present application is to provide a method and system for determining an upper limit of a pitch angle change value of a towing airdrop aircraft, so as to overcome or alleviate at least one of the known technical defects.

[0010] The technical solution of this application is:

[0011] On the one hand, a method for determining an upper limit of a pitch angle variation value of a towing airdrop aircraft is provided, comprising:

[0012] Step 1: Determine the angle of attack limit α of the upper limit of the pitch angle change max1 ;

[0013] Step 2: Determine the angle limit α of the interference between the traction parachute rope and the cargo hold exit, which is the upper limit of the pitch angle change value max2 ;

[0014] Step 3: Determine the upper limit value θ of the pitch angle change itself max1 ;

[0015] Step 4: Angle of attack limit α of the upper limit of the comprehensive pitch angle change value max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 , determine the upper limit of the pitch angle change θ max .

[0016] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in step 1, based on the configuration F and speed V, considering the airflow separation, buffeting, and stall danger, the upper limit of the angle of attack is determined by using the aircraft characteristics, and the angle of attack limit α of the upper limit of the pitch angle change value is used. max1 .

[0017] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, step 1 includes:

[0018] α max1 =f(F,V);

[0019] in,

[0020] f(F,V) is the upper limit of the angle of attack under the combination of configuration F and speed V, taking into account the dangers of airflow separation, buffeting and stall, and is a function of configuration F and speed V.

[0021] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in step 2, the towing parachute line angle τ is used as the angle limit α of the towing parachute line interference with the cargo hold outlet of the upper limit of the pitch angle change value. max2 .

[0022] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, step 2 includes:

[0023] α max2 =τ.

[0024] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in step 2:

[0025]

[0026] in,

[0027] △X, △Z are the coordinate differences along the X and Z directions in the fuselage coordinate system between the lowest point M on the cargo hold exit and the connection point k of the towing parachute rope on the cargo.

[0028] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in step 2:

[0029]

[0030] in,

[0031] (x M ,z M ) is the coordinate of the lowest point M on the upper part of the cargo hold exit in the aircraft coordinate system;

[0032] (x k ,z k ) is the coordinate of the connection point k of the towing parachute rope on the cargo in the body coordinate system.

[0033] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in step 2:

[0034]

[0035] in,

[0036] (x N0 ,z N0 ) is the coordinate of the traction parachute rope connection point k in the body coordinate system at the start of the traction airdrop;

[0037] (x N ,z N ) is the coordinate of the point where the traction parachute rope connection point k leaves the aircraft in the aircraft coordinate system at the end of the traction airdrop;

[0038] K represents the location status of the cargo, 0 represents the cargo location point at the start of the towing airdrop, and 1 represents the cargo departure point at the end of the towing airdrop.

[0039] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in step 3, based on flight safety and usage scenario requirements, the upper limit value θ of the pitch angle change itself is determined. max1 .

[0040] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in step 4, the angle of attack limit α of the upper limit of the pitch angle change value is used. max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 The smaller value is used as the upper limit of the pitch angle change θ max .

[0041] According to at least one embodiment of the present application, in the above-mentioned method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, step 4 includes:

[0042] θ max =min(α max1 ,α max2 ,θ max1 ).

[0043] On the other hand, a system for determining an upper limit of a pitch angle variation value of a towing airdrop aircraft is provided, comprising:

[0044] The first module is used to determine the angle of attack limit α of the upper limit of the pitch angle change value max1 ;

[0045] The second module is used to determine the angle limit α of the towing parachute rope and the cargo compartment exit to determine the upper limit of the pitch angle change value max2 ;

[0046] The third module is used to determine the upper limit value θ of the pitch angle itself max1 ;

[0047] The fourth module is used to integrate the angle of attack limit α of the upper limit of the pitch angle change value max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 , determine the upper limit of the pitch angle change θ max .

[0048] According to at least one embodiment of the present application, in the above-mentioned system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in the first module, based on the configuration F and the speed V, considering the airflow separation, buffeting, and stall danger, the upper limit of the angle of attack is determined by using the aircraft characteristics, and the angle of attack limit α of the upper limit of the pitch angle change value is used. max1 ,have:

[0049] α max1 =f(F,V);

[0050] in,

[0051] f(F,V) is the upper limit of the angle of attack under the combination of configuration F and speed V, taking into account the dangers of airflow separation, buffeting and stall, and is a function of configuration F and speed V.

[0052] According to at least one embodiment of the present application, in the above-mentioned system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in the second module, the towing parachute line angle τ is used as the angle limit α of the towing parachute line interference with the cargo hold outlet of the pitch angle change value upper limit max2 ,have:

[0053] α max2 = τ;

[0054]

[0055] in,

[0056] △X, △Z are the coordinate differences between the lowest point M on the cargo hold exit and the connection point k of the towing parachute rope on the cargo, along the X and Z directions in the aircraft coordinate system;

[0057]

[0058] in,

[0059] (x M ,z M ) is the coordinate of the lowest point M on the upper part of the cargo hold exit in the aircraft coordinate system;

[0060] (x k ,z k ) is the coordinate of the connection point k of the towing parachute rope on the cargo in the body coordinate system;

[0061]

[0062] in,

[0063] (x N0 ,z N0 ) is the coordinate of the traction parachute rope connection point k in the body coordinate system at the start of the traction airdrop;

[0064] (x N ,z N ) is the coordinate of the point where the traction parachute rope connection point k leaves the aircraft in the aircraft coordinate system at the end of the traction airdrop;

[0065] K represents the location status of the cargo, 0 represents the cargo location point at the start of the towing airdrop, and 1 represents the cargo departure point at the end of the towing airdrop.

[0066] According to at least one embodiment of the present application, in the above-mentioned system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in the third module, based on flight safety and usage scenario requirements, the upper limit value θ of the pitch angle change itself is determined. max1 .

[0067] According to at least one embodiment of the present application, in the above-mentioned system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in the fourth module, the angle of attack limit α of the upper limit of the pitch angle change value is used. max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 The smaller value is used as the upper limit of the pitch angle change θ max ,have:

[0068] θ max =min(α max1 ,α max2 ,θ max1 ).

[0069] This application has at least the following beneficial technical effects:

[0070] In the method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft disclosed in the above-mentioned embodiment and the system thereof, in view of the situation where the aircraft state changes drastically during the towing airdrop process, the changing characteristics of the aircraft angle of attack, pitch angle, and towing parachute during the towing airdrop process are analyzed to obtain the upper limit of the pitch angle change value during the towing airdrop process. The obtained result is reasonable and can ensure that the angle of attack during the towing airdrop process does not exceed the limit and the parachute rope of the towing parachute does not interfere with the cargo hold exit, which is convenient for mission execution and ensures flight safety during the towing airdrop process. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 It is a schematic diagram of the variation trend of the pitch angle and the angle of attack during the continuous towing airdrop of cargo provided in the embodiment of the present application;

[0072] Figure 2 It is a schematic diagram of changes in the angle of the parachute rope, the angle of attack and the pitch angle of the towing parachute when a single piece of cargo gradually moves toward the cargo hold exit provided by an embodiment of the present application;

[0073] Figure 3 It is a schematic diagram of the coordinates of the connection points of each towing parachute rope on the cargo in the body coordinate system provided by an embodiment of the present application;

[0074] Figure 4 It is a schematic diagram of the angle limit change of the pitch angle change upper limit of the towing parachute rope and the cargo hold exit during the towing airdrop process provided by an embodiment of the present application;

[0075] Figure 5It is a schematic diagram of determining the upper limit of the pitch angle change by combining the angle of attack limit of the upper limit of the pitch angle change value, the angle limit of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change value, and the upper limit of the pitch angle change itself, provided in an embodiment of the present application.

[0076] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be construed as limitations on the present application. DETAILED DESCRIPTION

[0077] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0078] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall have the usual meanings understood by those of ordinary skill in the art to which this application belongs. The words used in the description of this application to indicate orientation are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application indicates that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0079] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0080] When an aircraft tows an airdrop, the main parameter changes have the following typical characteristics:

[0081] (1) The additional pitch moment generated by the movement of the cargo will directly change the pitch angle. Although the pitch angle is a longitudinal long-period quantity, due to the fast movement speed of the cargo, the pitch angle shows a rapid oscillation trend during the towing airdrop process and converges slowly.

[0082] (2) The angle of attack is longitudinal. After being disturbed, the towing airdrop process also shows a rapid oscillation trend. However, since the short-period quantity has a rapid convergence trend during the change process, the maximum value of the angle of attack oscillation peak is smaller than the corresponding value of the pitch angle. The change trends of the pitch angle and angle of attack during the continuous towing airdrop of cargo are as follows: Figure 1 shown.

[0083] (3) During the towing airdrop process, the movement of cargo is relatively short, and the aircraft's flight altitude and speed change slightly. The direct impact on the aircraft's flight altitude and speed is not significant, and will not pose a significant impact on flight safety.

[0084] (4) During towed airdrop, the tow parachute rope is stretched in the direction of the aircraft's airspeed, and the angle between the rope and the X-axis of the aircraft's coordinate system is the aircraft's angle of attack.

[0085] During the aircraft towing airdrop process, the pitch angle change amplitude is greater than the angle of attack change amplitude. When considering the angle of attack limitation, the angle of attack can be controlled by limiting the pitch angle change range. The aircraft angle of attack reflects the relationship between the towing parachute rope and the cargo hold floor. The angular relationship between the towing parachute rope and the aircraft can be represented by the aircraft pitch angle. Limiting the pitch angle change range can clarify the angle between the towing parachute rope and the cargo hold floor, thereby avoiding interference between the towing parachute rope and the cargo hold exit.

[0086] Therefore, during the aircraft towing airdrop process, the upper limit of the pitch angle can be controlled to limit the angle of attack, as well as the angle between the towing parachute rope and the cargo hold floor, so as to avoid interference between the towing parachute rope and the cargo hold exit, thereby facilitating the execution of the mission and improving the safety of the aircraft towing airdrop. Based on this, an embodiment of the present application provides a method for determining the upper limit of the pitch angle change value of a towing airdrop aircraft.

[0087] Step 1: Determine the angle of attack limit α of the upper limit of the pitch angle change max1 .

[0088] When the aircraft is flying, due to factors such as airflow separation, buffeting, and stall, there must be an upper limit on the angle of attack under the combination of configuration F and speed V. Based on configuration F and speed V, taking into account dangerous situations such as airflow separation, buffeting, and stall, the upper limit of the angle of attack is determined using the characteristics of the aircraft, which is the angle of attack limit α of the upper limit of the pitch angle change value. max1 , expressed as a function of configuration F and speed V, as follows:

[0089] α max1 =f(F,V)…………(1)

[0090] Step 2: Determine the angle limit α of the interference between the traction parachute rope and the cargo hold exit, which is the upper limit of the pitch angle change value max2 .

[0091] Regardless of whether it is a single or continuous towing, when a single piece of cargo gradually moves toward the cargo hold exit, the pitch angle θ increases significantly. Considering the assumption that the towing parachute rope interferes with the lowest point M at the top of the cargo hold exit, the changes in the towing parachute rope angle τ, the angle of attack α, and the pitch angle θ are as follows: Figure 2 shown.

[0092] The angle τ of the traction parachute rope changes in real time during the traction airdrop process, which is the angle of attack corresponding to the interference critical state at the corresponding moment.

[0093] For traction single cast:

[0094] α max2 =τ…………(2)

[0095] For towed continuous drop, the upper limit of the pitch angle change value is the angle limit α of the tow parachute rope interfering with the cargo hold exit max2 , take the larger value of the angle τ of each traction parachute rope.

[0096] The towing parachute line angle τ is the angle between the towing parachute line and the X-axis of the fuselage coordinate system, that is, the angle with the cargo hold floor, which is consistent with the value of the angle of attack α and can be calculated as follows:

[0097]

[0098] in,

[0099] △X, △Z are the coordinate differences along the X and Z directions in the fuselage coordinate system between the lowest point M on the cargo hold exit and the connection point k of the towing parachute rope on the cargo.

[0100]

[0101] in,

[0102] (x M ,z M ) is the coordinate of the lowest point M on the upper part of the cargo hold exit in the aircraft coordinate system;

[0103] (x k ,z k ) is the coordinate of the connection point k of the towing parachute rope on the cargo in the body coordinate system, and the value of this coordinate changes in real time during the towing airdrop process.

[0104]

[0105] in,

[0106] (x N0 ,z N0 ) is the coordinate of the traction parachute rope connection point k in the body coordinate system at the start of the traction airdrop;

[0107] (x N,z N ) is the coordinate of the point where the traction parachute rope connection point k leaves the aircraft in the aircraft coordinate system at the end of the traction airdrop, where z N0 With z N The difference reflects the angle change between the cargo hold floor and the x-axis of the aircraft coordinate system. N0 With x N The difference reflects the displacement of the cargo, x k Values ​​between x N0 and x N Between k Values ​​between z N0 and z N between;

[0108] K represents the location status of the cargo, 0 represents the cargo location point at the start of the towing airdrop, and 1 represents the cargo departure point at the end of the towing airdrop.

[0109] When the aircraft's angle of attack is too large, the parachute rope will interfere with the lowest point M above the cargo hold exit. max1 , the angle limit of the interference between the traction parachute rope and the cargo hold exit α max2 The calculation of the pitch angle change value can be comprehensively obtained by comprehensively obtaining the comprehensive angle of attack limit α max :

[0110] α max =min(α max1 ,α max2 )…………(5)

[0111] Since the pitch angle change amplitude is greater than the angle of attack change amplitude during the towing airdrop process, the comprehensive angle of attack limit α of the upper limit of the pitch angle change value is set. max As the pitch angle, if the crew controls the pitch angle change through manipulation and does not exceed the comprehensive angle of attack limit α of the upper limit of the pitch angle change value max , the angle of attack will definitely not exceed the limit value.

[0112] Step 3: Determine the upper limit value θ of the pitch angle change itself max1 .

[0113] Based on flight safety, usage scenarios and other requirements, the aircraft itself will have an upper limit value of the pitch angle change θ max1 .

[0114] Step 4: Angle of attack limit α of the upper limit of the comprehensive pitch angle change value max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 , determine the upper limit of the pitch angle change θ max .

[0115] Limit the angle of attack to the upper limit of the pitch angle change value α max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 The smaller value is used as the upper limit of the pitch angle change θ max , as follows:

[0116] θ max =min(α max1 ,α max2 ,θ max1 )…………(6)

[0117] In the method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft disclosed in the above embodiment, in view of the situation where the aircraft state changes dramatically during the towing airdrop process, the changing characteristics of the aircraft angle of attack, pitch angle, and towing parachute during the towing airdrop process are analyzed to obtain the upper limit of the pitch angle change value during the towing airdrop process. The obtained result is reasonable and can ensure that the angle of attack during the towing airdrop process does not exceed the limit and the parachute rope of the towing parachute does not interfere with the cargo hold exit, which is convenient for mission execution and ensures flight safety during the towing airdrop process.

[0118] The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft disclosed in the above embodiment is applicable to engineering practice, has technical theoretical support, has a simple calculation method, is highly feasible, and is easy to use.

[0119] In a specific embodiment, the transport aircraft drops cargo, the towing airdrop speed is 275 km / h, the cruise configuration is 250 km / h with a limited angle of attack of 14°, and the 300 km / h with a limited angle of attack of 13°. The coordinate k of the connection point of the towing parachute rope on the cargo at the start of the first towing airdrop (x N0 ,z N0 ) is (-4,0.2) m, and the coordinates of the connection point k of the traction parachute rope on the cargo at the beginning of the second cargo traction airdrop are (x N0 ,z N0 ) is (2, -0.2) m, and the coordinates of the connection point k of the traction parachute rope on the cargo when the cargo leaves the aircraft (x N ,z N ) is (-10,0.6)m, and the coordinates of the lowest point M on the upper part of the cargo hold exit (x M ,z M ) is (-13, -1.7) m, the upper limit of the aircraft pitch angle is 18°, and the calculation is carried out using the method for determining the upper limit of the pitch angle change value of the towing airdrop aircraft disclosed in the above embodiment.

[0120] Step 1: Based on the towing airdrop speed and cruise configuration limit angle of attack data, the limit angle of attack of 13.5° corresponding to the towing airdrop speed of 275km / h is used as the angle of attack limit α of the upper limit of the pitch angle change value. max1 ;

[0121] Step 2: Calculate the coordinates of the connection point k of the traction parachute rope on the cargo in the body coordinate system during the traction airdrop process, and the coordinates of the connection point k of each traction parachute rope on the cargo in the body coordinate system (x k ,z k ) changes as Figure 3 shown.

[0122] Calculate the angle limit α of the interference between the towing parachute rope and the cargo hold exit for the upper limit of the pitch angle change max2 ,like Figure 4 As shown, the horizontal axis is the traction airdrop process, t1 is the time when the traction parachute of the first cargo begins to open, t2 is the time when the first cargo starts to move, t3 is the time when the first cargo leaves the aircraft, and at the same time, the traction parachute of the second cargo begins to open, t4 is the time when the second cargo starts to move, and t5 is the time when the second cargo leaves the aircraft.

[0123] Step 3: Determine the upper limit value θ of the pitch angle change itself max1 It is 18°.

[0124] Step 4: Set the angle of attack limit α of the upper limit of the comprehensive pitch angle change value max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 Plotted on a graph, such as Figure 5 The smaller value is used as the upper limit of the pitch angle change θ max The limiting factors of the pitch angle are different in different time periods. The minimum value of the pitch angle under multiple conditions is the pitch angle limit value.

[0125] A system for determining an upper limit of a pitch angle variation value of a towing airdrop aircraft, comprising:

[0126] The first module is used to determine the angle of attack limit α of the upper limit of the pitch angle change value max1 ;

[0127] The second module is used to determine the angle limit α of the towing parachute rope and the cargo compartment exit to determine the upper limit of the pitch angle change value max2 ;

[0128] The third module is used to determine the upper limit value θ of the pitch angle itself max1 ;

[0129] The fourth module is used to integrate the angle of attack limit α of the upper limit of the pitch angle change value max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1, determine the upper limit of the pitch angle change θ max .

[0130] Optionally, in the above-mentioned system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in the first module, based on the configuration F and the speed V, the upper limit of the angle of attack is determined by using the aircraft characteristics, and the angle of attack limit α of the upper limit of the pitch angle change value is used. max1 ,have:

[0131] α max1 =f(F,V);

[0132] in,

[0133] f(F,V) is the upper limit of the angle of attack under the combination of configuration F and speed V, taking into account the dangers of airflow separation, buffeting and stall, and is a function of configuration F and speed V.

[0134] Optionally, in the above-mentioned system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in the second module, the towing parachute rope included angle τ is used as the angle limit α of the towing parachute rope interference with the cargo hold outlet of the upper limit of the pitch angle change value. max2 ,have:

[0135] α max2 = τ;

[0136]

[0137] in,

[0138] △X, △Z are the coordinate differences between the lowest point M on the cargo hold exit and the connection point k of the towing parachute rope on the cargo, along the X and Z directions in the aircraft coordinate system;

[0139]

[0140] in,

[0141] (x M ,z M ) is the coordinate of the lowest point M on the upper part of the cargo hold exit in the aircraft coordinate system;

[0142] (x k ,z k ) is the coordinate of the connection point k of the towing parachute rope on the cargo in the body coordinate system;

[0143]

[0144] in,

[0145] (x N0 ,z N0) is the coordinate of the traction parachute rope connection point k in the body coordinate system at the start of the traction airdrop;

[0146] (x N ,z N ) is the coordinate of the point where the traction parachute rope connection point k leaves the aircraft in the aircraft coordinate system at the end of the traction airdrop;

[0147] K represents the location status of the cargo, 0 represents the cargo location point at the start of the towing airdrop, and 1 represents the cargo departure point at the end of the towing airdrop.

[0148] Optionally, in the above-mentioned system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in the third module, based on flight safety and usage scenario requirements, the upper limit value θ of the pitch angle change itself is determined. max1 .

[0149] Optionally, in the above-mentioned system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft, in the fourth module, the angle of attack limit α of the upper limit of the pitch angle change value is used. max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 The smaller value is used as the upper limit of the pitch angle change θ max ,have:

[0150] θ max =min(α max1 ,α max2 ,θ max1 ).

[0151] Regarding the system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft disclosed in the above embodiment, since it corresponds to the method disclosed in the above embodiment, the description is relatively simple. For specific related matters, please refer to the relevant instructions in the method part, and its technical effects can also refer to the technical effects of the relevant part of the method, which will not be repeated here.

[0152] In addition, technicians in the field should also be able to realize that the various modules of the system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft disclosed in the embodiment of the present application can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, this application generally describes them according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Technicians in the field can choose to adopt different methods to implement the described functions for each specific application and its actual constraints, but such implementation should not be considered to be beyond the scope of this application.

[0153] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. In the absence of conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0154] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A method for determining the upper limit of the pitch angle change value of a towing airdrop aircraft, characterized in that: include: Step 1: Determine the angle of attack limit α of the upper limit of the pitch angle change max1 ; Step 2: Determine the angle limit α of the interference between the traction parachute rope and the cargo hold exit, which is the upper limit of the pitch angle change value max2 ; Step 3: Determine the upper limit value θ of the pitch angle change itself max1 ; Step 4: Angle of attack limit α of the upper limit of the comprehensive pitch angle change value max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 , determine the upper limit of the pitch angle change θ max .

2. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 1, characterized in that: In step 1, based on configuration F and speed V, considering the airflow separation, buffeting, and stall danger, the upper limit of the angle of attack is determined using the aircraft characteristics, which is used as the upper limit of the pitch angle change value. max1 .

3. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 2, characterized in that: In step one, there are: α max1 =f(F,V); in, f(F,V) is the upper limit of the angle of attack under the combination of configuration F and speed V, taking into account the dangers of airflow separation, buffeting and stall, and is a function of configuration F and speed V.

4. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 3 is characterized in that: In step 2, the angle τ of the towing parachute rope is used as the upper limit of the pitch angle change value and the angle limit α of the towing parachute rope interference with the cargo hold exit max2 .

5. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 4 is characterized in that: In step 2, there are: a max2 =t.

6. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 5, characterized in that: In step 2: in, ΔX, ΔZ are the coordinate differences along the X and Z directions in the fuselage coordinate system between the lowest point M on the cargo hold exit and the connection point k of the towing parachute rope on the cargo.

7. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 6, characterized in that: In step 2: ΔX=x M -x k ΔZ=z M -with k ; in, (x M ,z M ) is the coordinate of the lowest point M on the upper part of the cargo hold exit in the aircraft coordinate system; (x k ,z k ) is the coordinate of the connection point k of the towing parachute rope on the cargo in the body coordinate system.

8. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 7, characterized in that: In step 2: in, (x N0 ,z N0 ) is the coordinate of the traction parachute rope connection point k in the body coordinate system at the start of the traction airdrop; (x N ,z N ) is the coordinate of the point where the traction parachute rope connection point k leaves the aircraft in the aircraft coordinate system at the end of the traction airdrop; K represents the location status of the cargo, 0 represents the cargo location point at the start of the towing airdrop, and 1 represents the cargo departure point at the end of the towing airdrop.

9. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 8, characterized in that: In step 3, based on flight safety and usage scenario requirements, determine the upper limit value θ of the pitch angle change itself max1 .

10. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 9, characterized in that: In step 4, the angle of attack is limited to the upper limit of the pitch angle change value α max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 The smaller value is used as the upper limit of the pitch angle change θ max .

11. The method for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 10, characterized in that: In step 4, there are: i max =min(a max1 ,a max2 ,i max1 )。 12. A system for determining the upper limit of the pitch angle change value of a towing airdrop aircraft, characterized in that: include: The first module is used to determine the angle of attack limit α of the upper limit of the pitch angle change value max1 ; The second module is used to determine the angle limit α of the towing parachute rope and the cargo compartment exit to determine the upper limit of the pitch angle change value max2 ; The third module is used to determine the upper limit value θ of the pitch angle itself max1 ; The fourth module is used to integrate the angle of attack limit α of the upper limit of the pitch angle change value max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 , determine the upper limit of the pitch angle change θ max .

13. The system for determining the upper limit of the pitch angle change value of the towing airdrop aircraft according to claim 12, characterized in that: In the first module, based on the configuration F and speed V, the airflow separation, buffeting, and stall dangers are considered, and the upper limit of the angle of attack is determined by using the characteristics of the aircraft, which is used as the upper limit of the pitch angle change value. max1 ,have: α max1 =f(F,V); in, f(F,V) is the upper limit of the angle of attack under the combination of configuration F and speed V, taking into account the dangers of airflow separation, buffeting and stall, and is a function of configuration F and speed V.

14. The system for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 13, characterized in that: In the second module, the angle α of the towing parachute rope interference with the cargo hold exit is taken as the upper limit of the pitch angle change value. max2 ,have: a max2 =t; in, ΔX, ΔZ are the coordinate differences between the lowest point M on the cargo hold exit and the connection point k of the towing parachute rope on the cargo in the X and Z directions in the aircraft coordinate system; ΔX=x M -x k ΔZ=z M -with k ; in, (x M ,z M ) is the coordinate of the lowest point M on the upper part of the cargo hold exit in the aircraft coordinate system; (x k ,z k ) is the coordinate of the connection point k of the towing parachute rope on the cargo in the body coordinate system; in, (x N0 ,z N0 ) is the coordinate of the traction parachute rope connection point k in the body coordinate system at the start of the traction airdrop; (x N ,z N ) is the coordinate of the point where the traction parachute rope connection point k leaves the aircraft in the aircraft coordinate system at the end of the traction airdrop; K represents the location status of the cargo, 0 represents the cargo location point at the start of the towing airdrop, and 1 represents the cargo departure point at the end of the towing airdrop.

15. The system for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 14, characterized in that: In the third module, based on flight safety and usage scenario requirements, the upper limit value θ of the pitch angle change itself is determined. max1 .

16. The system for determining the upper limit of the pitch angle variation value of the towing airdrop aircraft according to claim 15, characterized in that: In the fourth module, the angle of attack is limited to the upper limit of the pitch angle change value α max1 , the angle limit α of the interference between the towing parachute rope and the cargo hold exit of the upper limit of the pitch angle change max2 , the upper limit of the pitch angle change itself θ max1 The smaller value is used as the upper limit of the pitch angle change θ max ,have: i max =min(a max1 ,a max2 ,i max1 )。

Images