Method and system for determining elevator trim additional deflection angle after aircraft cargo throwing

Abstract

The invention belongs to the technical field of aircraft control stability design, and particularly relates to a method and system for determining an elevator trim additional deflection angle after aircraft cargo putting, and the method comprises the steps: 1, calculating the weight change of an aircraft after cargo putting, and calculating the weight change of the aircraft after cargo putting; a generated elevator balancing additional deflection angle delta e1; step 2, calculating an elevator trim additional deflection angle delta e2 generated by the change of the center of gravity of the aircraft after the cargo is thrown; 3, the elevator balancing additional deflection angle delta e1 generated by aircraft weight change after the goods are thrown and the elevator balancing additional deflection angle delta e2 generated by aircraft gravity center change after the goods are thrown are synthesized, and the elevator balancing additional deflection angle delta e is obtained.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft control stability design, and specifically relates to a method and system for determining an additional deflection angle of an elevator trim after cargo is dropped from an aircraft. Background Art

[0002] When an aircraft performs a cargo delivery mission, part of the cargo will fall off the aircraft, causing changes in the aircraft's mass characteristic data, including weight, center of gravity, and moment of inertia.

[0003] Due to the change of aircraft mass characteristic data before and after cargo delivery, the additional deflection angle of aircraft elevator trim will change significantly. Obtaining the additional deflection angle of aircraft elevator trim is critical for setting the elevator preset angle, mastering the operation input, estimating the aircraft controllability, and ensuring the safe execution of the mission.

[0004] At present, the main method is to build a nonlinear equation group by modeling the three-degree-of-freedom flight dynamics of the aircraft and cargo, and solve the balance points of the equation group corresponding to the flight state before and after cargo delivery, and then calculate the elevator difference and obtain the additional deflection angle. This technical solution has accurate calculation results, but for different delivery scenarios and different cargoes, it is necessary to use a computer to change parameters using a specific calculation program and repeatedly solve the nonlinear equation group for calculation, which is inefficient and difficult to implement when there is a lack of computers and their specific calculation programs.

[0005] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0006] The purpose of the present application is to provide a method and system for determining the additional deflection angle of the elevator trim after cargo is dropped from an aircraft, so as to obtain the additional deflection angle of the elevator required to maintain the aircraft's trim state relative to that before cargo is dropped, so as to overcome or alleviate at least one of the known technical defects.

[0007] The technical solution of this application is:

[0008] On the one hand, a method for determining an additional deflection angle of an elevator trim after cargo is dropped from an aircraft is provided, comprising:

[0009] Step 1: Calculate the additional elevator trim angle △δ generated by the change in aircraft weight after cargo delivery e1 ;

[0010] Step 2: Calculate the additional elevator trim angle △δ generated by the change in the aircraft's center of gravity after cargo is dropped e2 ;

[0011] Step 3: After the cargo is dropped, the weight change of the aircraft is calculated, and the additional deflection angle △δ of the elevator trim is generated e1, and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e .

[0012] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped, step 1 is specifically as follows:

[0013] C mα ·△α+C m,δe ·△δ e1 =0;

[0014] in,

[0015] C mα is the aircraft longitudinal static stability derivative;

[0016] △α is the amount of angle of attack reduction to achieve rebalancing after cargo delivery;

[0017] C m,δe is the elevator efficiency.

[0018] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is released, in step 1,

[0019] in,

[0020] △m is the mass of the cargo dropped from the aircraft, and △m is the reduction in the mass of the aircraft;

[0021] g is the acceleration due to gravity;

[0022] ρ is the atmospheric density;

[0023] V is the flight speed;

[0024] S is the wing area;

[0025] C Lα is the slope of the lift line.

[0026] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after cargo is dropped from an aircraft, step 2 is specifically as follows:

[0027]

[0028] in,

[0029] △M is the moment of force exerted by the cargo on the aircraft;

[0030] c is the mean aerodynamic chord length.

[0031] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is released, in step 2, △M=-m0g·△X;

[0032] in,

[0033] m0 is the total mass of the aircraft and cargo before cargo is released;

[0034] △X is the offset of the aircraft's center of gravity after the cargo is dropped.

[0035] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is released, in step 2, △X=X1-X0;

[0036] in,

[0037] X1 is the location of the aircraft’s center of gravity after cargo is dropped;

[0038] X0 is the location of the total center of gravity of the aircraft and cargo before the cargo is dropped.

[0039] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is released, step three is specifically:

[0040] △δ e =△δ e1 +△δ e2 .

[0041] According to at least one embodiment of the present application, the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is released further includes:

[0042] Step 4: Calculate the angle of attack correction caused by the elevator change, and the resulting additional elevator trim angle △δ ex ;

[0043] Step 5: Use the elevator change to generate the angle of attack correction, and the resulting elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 .

[0044] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is released, step 4 is specifically as follows:

[0045] C mα △α x +C m,δe ·△δ ex =0;

[0046] in,

[0047] △α x is the elevator change △δ e The additional lift generated is △C L , the resulting angle of attack correction.

[0048] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is released, in step 4, C L,δe △δ e +C Lα △α x =0;

[0049] in,

[0050] C Lδe is the derivative of the elevator lift coefficient with respect to the control surface.

[0051] According to at least one embodiment of the present application, in the above-mentioned method for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped, step five is specifically as follows:

[0052] △δ e0 =△δ e +△δ ex .

[0053] On the other hand, a system for determining an additional deflection angle of an elevator trim after cargo delivery from an aircraft is provided, comprising:

[0054] The module for calculating the additional deflection angle of the elevator trim generated by the change in aircraft weight is used to calculate the additional deflection angle △δ of the elevator trim generated by the change in aircraft weight after cargo delivery. e1 ;

[0055] The module for calculating the additional deflection angle of the elevator trim generated by the change of the aircraft's center of gravity is used to calculate the additional deflection angle △δ of the elevator trim generated by the change of the aircraft's center of gravity after the cargo is dropped. e2 ;

[0056] The elevator trim additional deflection angle calculation module is used to calculate the elevator trim additional deflection angle △δ generated by the aircraft weight change after cargo delivery e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e .

[0057] According to at least one embodiment of the present application, in the above-mentioned system for determining the additional deflection angle of the elevator trim after cargo delivery to the aircraft, the module for calculating the additional deflection angle of the elevator trim generated by the aircraft weight change calculates the additional deflection angle △δ of the elevator trim generated by the aircraft weight change after cargo delivery. e1 , specifically:

[0058] C mα ·△α+C m,δe ·△δ e1 =0;

[0059] in,

[0060] C mα is the aircraft longitudinal static stability derivative;

[0061] △α is the amount of angle of attack reduction to achieve rebalancing after cargo delivery;

[0062] C m,δe is the elevator efficiency;

[0063]

[0064] in,

[0065] △m is the mass of the cargo dropped from the aircraft, and △m is the reduction in the mass of the aircraft;

[0066] g is the acceleration due to gravity;

[0067] ρ is the atmospheric density;

[0068] V is the flight speed;

[0069] S is the wing area;

[0070] C Lα is the lift line slope;

[0071] In the calculation module of the additional deflection angle of the elevator trim generated by the change of the aircraft's center of gravity, the additional deflection angle △δ of the elevator trim generated by the change of the aircraft's center of gravity after the cargo is dropped is calculated. e2 , specifically:

[0072]

[0073] in,

[0074] △M is the moment of force exerted by the cargo on the aircraft;

[0075] c is the average aerodynamic chord length;

[0076] △M=-m0g·△X;

[0077] in,

[0078] m0 is the total mass of the aircraft and cargo before cargo is released;

[0079] △X is the offset of the aircraft’s center of gravity after cargo is dropped;

[0080] △X=X1-X0;

[0081] in,

[0082] X1 is the location of the aircraft’s center of gravity after cargo is dropped;

[0083] X0 is the total center of gravity of the aircraft and cargo before cargo is dropped

[0084] In the elevator trim additional deflection angle calculation module, the additional elevator trim deflection angle △δ is generated by integrating the aircraft weight change e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e , specifically:

[0085] △δ e =△δ e1 +△δ e2 .

[0086] According to at least one embodiment of the present application, the above-mentioned system for determining the additional deflection angle of the elevator trim after the aircraft cargo is released further includes:

[0087] The module for calculating the additional deflection angle of the elevator trim generated by the angle correction amount generated by the elevator change is used to calculate the additional deflection angle △δ generated by the angle correction amount generated by the elevator change. ex ;

[0088] The elevator trim additional deflection angle correction calculation module is used to generate the angle of attack correction amount based on the elevator change, and the generated elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 .

[0089] According to at least one embodiment of the present application, in the above-mentioned system for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped, the additional deflection angle calculation module for the elevator trim generated by the angle of attack correction amount generated by the elevator change calculates the additional deflection angle △δ generated by the elevator trim. ex , specifically:

[0090] C mα △α x +C m,δe ·△δ ex =0;

[0091] in,

[0092] △α x is the elevator change △δ e The additional lift generated is △C L , the resulting angle of attack correction;

[0093] C L,δe △δ e +C Lα △α x =0;

[0094] in,

[0095] C Lδe is the derivative of the elevator lift coefficient with respect to the control surface;

[0096] In the elevator trim additional deflection angle correction calculation module, the elevator change generates an angle of attack correction, and the resulting elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 , specifically:

[0097] △δ e0 =△δ e +△δ ex .

[0098] This application has at least the following beneficial technical effects:

[0099] Provided are a method and system for determining an additional deflection angle of an elevator trim after cargo is dropped from an aircraft. The method utilizes the characteristics of changes in the center of gravity and weight before and after cargo is dropped to deduce an additional deflection angle of the elevator after dropping relative to a state before dropping. The method has a clear calculation principle, a simple calculation formula, and uses less data. The method is mainly based on commonly used parameters that are easy to obtain, such as cargo mass, center of gravity change, aircraft geometry, and aerodynamic characteristics of the carrier aircraft. The method does not require solving a nonlinear equation group, is not limited by computers and nonlinear equation group solving programs, is convenient for rapid calculation, and has high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] Figure 1 It is a schematic diagram of the change of the center of gravity of the aircraft when the center of gravity of the cargo provided in the embodiment of the present application is dropped before the center of gravity of the aircraft;

[0101] Figure 2 It is a schematic diagram of the change of the center of gravity of the aircraft when the center of gravity of the cargo provided in the embodiment of the present application is dropped behind the center of gravity of the aircraft;

[0102] Figure 3 is a schematic diagram of a method for determining an additional deflection angle of an elevator trim after cargo is dropped from an aircraft provided in an embodiment of the present application;

[0103] Figure 4 It is a schematic diagram of a system for determining an additional deflection angle of an elevator trim after cargo is dropped from an aircraft provided in an embodiment of the present application.

[0104] 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

[0105] 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.

[0106] 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.

[0107] 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.

[0108] Before and after the cargo is dropped, the weight, center of gravity and moment of inertia of the aircraft will change significantly. According to the characteristics of the aircraft trim state nonlinear equations, the changes in weight and center of gravity will affect the elevator trim amount, while the changes in moment of inertia have no effect on the elevator trim amount.

[0109] (I) Impact caused by the change in aircraft weight after cargo is dropped.

[0110] After the cargo is dropped, the mass of the aircraft is reduced. In order to achieve rebalancing after the cargo is dropped, the aircraft trim angle of attack must be reduced. The reduction in angle of attack △α is calculated as follows:

[0111]

[0112] in,

[0113] △m is the mass of the cargo dropped from the aircraft, and △m is the reduction in the mass of the aircraft;

[0114] g is the acceleration due to gravity, which can be 9.8m / s2;

[0115] ρ is the atmospheric density;

[0116] V is the flight speed;

[0117] S is the wing area;

[0118] C Lα is the slope of the lift line.

[0119] The reduction in the angle of attack △α can generate a pitch moment, which requires the elevator to deflect a certain angle to balance. That is, after the cargo is dropped, the weight of the aircraft changes, resulting in an additional deflection angle △δ for the elevator to balance. e1 , calculated as follows:

[0120] C mα ·△α+C m,δe ·△δ e1 =0…………(2)

[0121] in,

[0122] C mα is the aircraft longitudinal static stability derivative;

[0123] C m,δe is the elevator efficiency.

[0124] Substituting equation 1 into equation 2 yields:

[0125]

[0126] In general, the aircraft longitudinal static stability derivative C mα 、Elevator efficiency C m,δe All are less than 0, additional deflection angle △δ e1 Greater than 0.

[0127] (ii) The impact caused by the change in the aircraft's center of gravity after the cargo is dropped.

[0128] The cargo center of gravity is dropped before or after the aircraft center of gravity. The aircraft center of gravity changes as follows: Figure 1 , Figure 2 shown.

[0129] The change in the center of gravity of the aircraft before and after the cargo is dropped is △X=X1-X0, where X0 is the position of the total center of gravity of the aircraft and the cargo before the cargo is dropped, and X1 is the position of the center of gravity of the aircraft after the cargo is dropped.

[0130] Considering the cargo as an object that exerts force and torque on the aircraft, it can be assumed that after the cargo is dropped, the torque △M exerted by the cargo on the aircraft disappears, and the calculation is as follows:

[0131] △M=-△mg·(X1-X2)…………(4)

[0132] in,

[0133] X2 is the location of the center of gravity of the cargo before delivery.

[0134] The total mass of the aircraft and cargo before cargo delivery is m0, the mass of the aircraft after cargo delivery is m1, the position of the total center of gravity of the aircraft and cargo before cargo delivery is X0, the position of the center of gravity of the aircraft after cargo delivery is X1, and the following equations 5 and 6 are satisfied.

[0135] m0=m1+△m…………(5)

[0136] m0X0=m1X1+△mX2…………(6)

[0137] According to formula 5 and formula 6, we have:

[0138]

[0139] Substituting equation 7 into equation 4 and eliminating X2, we have:

[0140] △M=-m0g·(X1-X0)=-m0g·△X…………(8)

[0141] in,

[0142] △X is the offset of the aircraft's center of gravity after the cargo is dropped.

[0143] After the cargo is dropped, the torque △M of the cargo on the aircraft disappears, and the elevator needs to be deflected at a certain angle for balance. That is, after the cargo is dropped, the center of gravity of the aircraft changes, and the additional deflection angle △δ of the elevator trim is generated. e2 , calculated as follows:

[0144]

[0145]

[0146] in,

[0147] c is the mean aerodynamic chord length.

[0148] After the cargo is dropped, the center of gravity of the aircraft changes, resulting in an additional deflection angle △δ for the elevator trim e2 The positive and negative signs are related to the offset △X of the center of gravity of the aircraft after the cargo is dropped. When the cargo is dropped before the center of gravity of the aircraft, △X>0, and when the cargo is dropped after the center of gravity of the carrier aircraft, △X<0.

[0149] (iii) The total impact of changes in aircraft weight and center of gravity after the cargo is dropped.

[0150] Comprehensively consider the changes in aircraft weight and center of gravity after cargo delivery, and the additional deflection angle △δ of the elevator trim e , calculated as follows:

[0151]

[0152] Theoretically, the elevator changes △δ e The additional lift generated is △C L , which will affect the estimation of the angle of attack reduction △α after delivery, and the resulting angle of attack correction △α x There is an additional pitch moment, which in turn forms the elevator correction. Elevator change △δ e The additional lift generated is △C L , the resulting angle of attack correction △α x , calculated as follows:

[0153] C L,δe △δ e +C Lα △α x =0…………(12)

[0154] C Lδe is the derivative of the elevator lift coefficient with respect to the control surface.

[0155] Elevator change △δ e The additional lift generated is △C L , generating the angle of attack correction △α x The pitch moment requires the elevator to be deflected at a certain angle to balance, that is, the change of the elevator produces an angle of attack correction, and the resulting elevator trim additional deflection angle △δ ex , calculated as follows:

[0156] C mα △α x +C m,δe ·△δ ex =0…………(13)

[0157] Considering the angle of attack correction caused by the change of the elevator, the additional deflection angle △δ generated by the change of the elevator is ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 , calculated as follows:

[0158]

[0159] Equation 14 corrects the effect of the angle of attack correction produced by the elevator deflection. The angle of attack correction produced by the elevator change is the additional deflection angle △δ produced by the elevator trim. ex, which will generate an angle of attack correction again, and then generate a corresponding additional deflection angle for elevator trim. Considering n corrections, considering the angle of attack correction caused by the elevator change, the additional deflection angle △δ for elevator trim e0 , calculated as follows:

[0160]

[0161] Usually, the accuracy of the result is sufficient when not considering or only considering one correction, and the calculation of formula 11 can meet the requirements.

[0162] The mass of the cargo dropped by the above aircraft, △m, is in kg, the total mass of the aircraft and cargo before the cargo is dropped, m0, is in kg, and the longitudinal static stability derivative of the aircraft, C mα The unit is 1 / °, the slope of the lift line C Lα The unit is 1 / °, the derivative of the elevator lift coefficient with respect to the control surface C Lδe The unit is 1 / °, elevator efficiency C mδe The unit is 1 / °, and the unit of atmospheric density ρ is kg / m 3 , flight speed V is in m / s, wing area S is in m 2 , the unit of average aerodynamic chord length c is m, and the unit of offset △X of the center of gravity of the aircraft after cargo delivery is m.

[0163] Based on the above embodiments of the present application, a method for determining an additional deflection angle of the elevator trim after cargo is dropped from an aircraft is provided, such as Figure 3 shown.

[0164] Step 1: Calculate the additional elevator trim angle △δ generated by the change in aircraft weight after cargo delivery e1 .

[0165] C mα ·△α+C m,δe ·△δ e1 =0;

[0166] in,

[0167] C mα is the aircraft longitudinal static stability derivative;

[0168] △α is the amount of angle of attack reduction to achieve rebalancing after cargo delivery;

[0169] C m,δe is the elevator efficiency.

[0170]

[0171] in,

[0172] △m is the mass of the cargo dropped from the aircraft, and △m is the reduction in the mass of the aircraft;

[0173] g is the acceleration due to gravity;

[0174] ρ is the atmospheric density;

[0175] V is the flight speed;

[0176] S is the wing area;

[0177] C Lα is the slope of the lift line.

[0178] Finally, we have:

[0179]

[0180] Step 2: Calculate the additional elevator trim angle △δ generated by the change in the aircraft's center of gravity after cargo is dropped e2 .

[0181]

[0182] in,

[0183] △M is the moment of force exerted by the cargo on the aircraft;

[0184] c is the mean aerodynamic chord length.

[0185] △M=-m0g·△X;

[0186] in,

[0187] m0 is the total mass of the aircraft and cargo before cargo is released;

[0188] △X is the offset of the aircraft's center of gravity after the cargo is dropped.

[0189] △X=X1-X0;

[0190] in,

[0191] X1 is the location of the aircraft’s center of gravity after cargo is dropped;

[0192] X0 is the location of the total center of gravity of the aircraft and cargo before the cargo is dropped.

[0193] Finally, we have:

[0194]

[0195] Step 3: After the cargo is dropped, the weight change of the aircraft is calculated, and the additional deflection angle △δ of the elevator trim is generated e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e .

[0196] △δe =△δ e1 +△δ e2 .

[0197] Finally, we have:

[0198]

[0199] Step 4: Calculate the angle of attack correction caused by the elevator change, and the resulting additional elevator trim angle △δ ex .

[0200] C mα △α x +C m,δe ·△δ ex =0;

[0201] in,

[0202] △α x is the elevator change △δ e The additional lift generated is △C L , the resulting angle of attack correction.

[0203] C L,δe △δ e +C Lα △α x =0;

[0204] in,

[0205] C Lδe is the derivative of the elevator lift coefficient with respect to the control surface.

[0206] Step 5: Use the elevator change to generate the angle of attack correction, and the resulting elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 .

[0207] △δ e0 =△δ e +△δ ex .

[0208] Finally, we have:

[0209]

[0210] It can also add an additional deflection angle △δ to the elevator trim e Several corrections were made, including:

[0211]

[0212] In a specific embodiment, the mass of the cargo dropped by the aircraft △m=20000kg, and the longitudinal static stability derivative of the aircraft C mα =-0.03, lift line slope C Lα =0.1, elevator efficiency C mδe =-0.02, the atmospheric density corresponding to the flight altitude of 1000m is ρ=1.11kg / m3, the flight speed is V=120m / s, the wing area is S=250m2, the average aerodynamic chord length is c=7m, the offset of the center of gravity of the aircraft after the cargo is dropped is △X=1m, and the total mass of the aircraft and cargo before the cargo is dropped is m0=135000kg.

[0213] The additional deflection angle Δδ of the elevator trim is determined by the method for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped according to the above embodiment. e , the specific implementation is as follows:

[0214] Calculate the additional elevator trim angle △δ caused by the change in aircraft weight after cargo delivery e1 =1.5°;

[0215] Calculate the additional elevator trim angle △δ caused by the change in the aircraft's center of gravity after cargo is dropped e2 =4.7°;

[0216] The additional deflection angle of the elevator trim is △δ, which is generated by the combined weight change of the aircraft. e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e =△δ e1 +△δ e2 =6.2°, which is close to the additional deflection angle of 6.6° obtained by performing three / six-degree-of-freedom flight dynamics modeling on the aircraft and cargo, establishing a nonlinear equation group, solving the equilibrium points of the equation group corresponding to the flight states before and after cargo delivery, and then calculating the elevator difference, and having a high accuracy.

[0217] The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft disclosed in the above-mentioned embodiment utilizes the characteristics of the change in the center of gravity and weight before and after cargo delivery to deduce the additional deflection angle of the elevator after delivery relative to the state before delivery. The calculation principle is clear, the calculation formula is simple, and less data is used. It is mainly based on the cargo mass, the change in the center of gravity, the geometric shape of the aircraft, the aerodynamic characteristics of the carrier aircraft, and other commonly used parameters that are easy to obtain. There is no need to solve a group of nonlinear equations, and it is not limited by computers and nonlinear equation solution programs. It is convenient for rapid calculation and has high efficiency.

[0218] On the other hand, a system for determining the additional deflection angle of the elevator trim after the aircraft cargo is released is provided. Figure 4 As shown, including:

[0219] The module for calculating the additional deflection angle of the elevator trim generated by the change in aircraft weight is used to calculate the additional deflection angle △δ of the elevator trim generated by the change in aircraft weight after cargo delivery. e1 ;

[0220] The module for calculating the additional deflection angle of the elevator trim generated by the change of the aircraft's center of gravity is used to calculate the additional deflection angle △δ of the elevator trim generated by the change of the aircraft's center of gravity after the cargo is dropped. e2 ;

[0221] The elevator trim additional deflection angle calculation module is used to integrate the aircraft weight change to generate the elevator trim additional deflection angle △δ e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e .

[0222] Optionally, in the above-mentioned system for determining the additional deflection angle of the elevator trim after cargo delivery, a module for calculating the additional deflection angle of the elevator trim generated by the aircraft weight change calculates the additional deflection angle △δ of the elevator trim generated by the aircraft weight change after cargo delivery. e1 , specifically:

[0223] C mα ·△α+C m,δe ·△δ e1 =0;

[0224] in,

[0225] C mα is the aircraft longitudinal static stability derivative;

[0226] △α is the amount of angle of attack reduction to achieve rebalancing after cargo delivery;

[0227] C m,δe is the elevator efficiency;

[0228]

[0229] in,

[0230] △m is the mass of the cargo dropped from the aircraft, and △m is the reduction in the mass of the aircraft;

[0231] g is the acceleration due to gravity;

[0232] ρ is the atmospheric density;

[0233] V is the flight speed;

[0234] S is the wing area;

[0235] C Lα is the slope of the lift line;

[0236] In the calculation module of the additional deflection angle of the elevator trim generated by the change of the aircraft's center of gravity, the additional deflection angle △δ of the elevator trim generated by the change of the aircraft's center of gravity after the cargo is dropped is calculated. e2 , specifically:

[0237]

[0238] in,

[0239] △M is the torque of the cargo on the aircraft;

[0240] c is the average aerodynamic chord length;

[0241] △M=-m0g·△X;

[0242] in,

[0243] m0 is the total mass of the aircraft and cargo before cargo is released;

[0244] △X is the offset of the aircraft’s center of gravity after cargo is dropped;

[0245] △X=X1-X0;

[0246] in,

[0247] X1 is the location of the aircraft’s center of gravity after cargo is dropped;

[0248] X0 is the total center of gravity of the aircraft and cargo before cargo is dropped

[0249] In the elevator trim additional deflection angle calculation module, the additional elevator trim deflection angle △δ is generated by integrating the aircraft weight change e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e , specifically:

[0250] △δ e =△δ e1 +△δ e2 .

[0251] Optionally, the above-mentioned system for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped also includes:

[0252] The module for calculating the additional deflection angle of the elevator trim generated by the angle correction amount generated by the elevator change is used to calculate the additional deflection angle △δ generated by the angle correction amount generated by the elevator change. ex ;

[0253] The elevator trim additional deflection angle correction calculation module is used to generate the angle of attack correction amount based on the elevator change, and the generated elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 .

[0254] Optionally, in the above-mentioned system for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped, in the module for calculating the additional deflection angle of the elevator trim generated by the angle of attack correction amount generated by the elevator change, the additional deflection angle of the elevator trim generated by the elevator change is calculated. ex , specifically:

[0255] C mα △α x +C m,δe ·△δ ex =0;

[0256] in,

[0257] △α x is the elevator change △δ e The additional lift generated is △C L , the resulting angle of attack correction;

[0258] C L,δe △δ e +C Lα △α x =0;

[0259] in,

[0260] C Lδe is the derivative of the elevator lift coefficient with respect to the control surface;

[0261] In the elevator trim additional deflection angle correction calculation module, the elevator change generates an angle of attack correction, and the resulting elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 , specifically:

[0262] △δ e0 =△δ e +△δ ex .

[0263] With regard to the system for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped, as it corresponds to the method for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped, the description is relatively simple. For specific related matters, please refer to the relevant description of the system for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped, and its technical effects may also refer to the technical effects of the method for determining the additional deflection angle of the elevator trim after the aircraft cargo is dropped, which will not be repeated here.

[0264] In addition, technicians in the field should also be able to realize that the various modules and units of the system for determining the additional deflection angle of the elevator trim after the aircraft cargo is released disclosed in the embodiments 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.

[0265] 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 additional deflection angle of the elevator trim after cargo is dropped from an aircraft, characterized in that: include: Step 1: Calculate the additional elevator trim angle △δ generated by the change in aircraft weight after cargo delivery e1 ; Step 2: Calculate the additional elevator trim angle △δ generated by the change in the aircraft's center of gravity after cargo is dropped e2 ; Step 3: After the cargo is dropped, the weight change of the aircraft is calculated, and the additional deflection angle △δ of the elevator trim is generated e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e .

2. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 1, characterized in that: Step 1 is as follows: C mα ·△α+C m,δe ·△δ e1 =0; in, C mα is the aircraft longitudinal static stability derivative; △α is the amount of angle of attack reduction to achieve rebalancing after cargo delivery; C m,δe is the elevator efficiency.

3. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 2, characterized in that: In step one, in, △m is the mass of the cargo dropped from the aircraft, and △m is the reduction in the mass of the aircraft; g is the acceleration due to gravity; ρ is the atmospheric density; V is the flight speed; S is the wing area; C Lα is the slope of the lift line.

4. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 3, characterized in that: Step 2 is as follows: in, △M is the torque of the cargo on the aircraft; c is the mean aerodynamic chord length.

5. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 4, characterized in that: In step 2, △M=-m0g·△X; in, m0 is the total mass of the aircraft and cargo before cargo is released; △X is the offset of the aircraft's center of gravity after the cargo is dropped.

6. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 5, characterized in that: In step 2, △X = X1-X0; in, X1 is the location of the aircraft’s center of gravity after cargo is dropped; X0 is the location of the total center of gravity of the aircraft and cargo before the cargo is dropped.

7. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 6, characterized in that: Step three is as follows: △δ e =△δ e1 +△δ e2 。 8. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 7, characterized in that: Also includes: Step 4: Calculate the angle of attack correction caused by the elevator change, and the resulting additional elevator trim angle △δ ex ; Step 5: Use the elevator change to generate the angle of attack correction, and the resulting elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 .

9. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 8, characterized in that: Step 4 is as follows: C mα ·△α x +C m,δe ·△δ ex =0; in, △α x is the elevator change △δ e The additional lift generated is △C L , the resulting angle of attack correction.

10. The method for determining the additional deflection angle of the elevator trim after cargo delivery from an aircraft according to claim 9, characterized in that: In step 4, C L,δe △δ e +C Lα △α x =0; in, C Lδe is the derivative of the elevator lift coefficient with respect to the control surface.

11. The method for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 10, characterized in that: Step 5 is as follows: △δ e0 =△δ e +△δ ex 。 12. A system for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft, characterized in that: include: The module for calculating the additional deflection angle of the elevator trim generated by the change in aircraft weight is used to calculate the additional deflection angle △δ of the elevator trim generated by the change in aircraft weight after cargo delivery. e1 ; The module for calculating the additional deflection angle of the elevator trim generated by the change of the aircraft's center of gravity is used to calculate the additional deflection angle △δ of the elevator trim generated by the change of the aircraft's center of gravity after the cargo is dropped. e2 ; The elevator trim additional deflection angle calculation module is used to calculate the elevator trim additional deflection angle △δ generated by the aircraft weight change after cargo delivery e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e .

13. The system for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 12, characterized in that: The calculation module of the additional deflection angle of the elevator trim generated by the change of aircraft weight calculates the additional deflection angle △δ of the elevator trim generated by the change of aircraft weight after cargo delivery. e1 , specifically: C mα ·△α+C m,δe ·△δ e1 =0; in, C mα is the aircraft longitudinal static stability derivative; △α is the amount of angle of attack reduction to achieve rebalancing after cargo delivery; C m,δe is the elevator efficiency; in, △m is the mass of the cargo dropped from the aircraft, and △m is the reduction in the mass of the aircraft; g is the acceleration due to gravity; ρ is the atmospheric density; V is the flight speed; S is the wing area; C Lα is the lift line slope; In the calculation module of the additional deflection angle of the elevator trim generated by the change of the aircraft's center of gravity, the additional deflection angle △δ of the elevator trim generated by the change of the aircraft's center of gravity after the cargo is dropped is calculated. e2 , specifically: in, △M is the moment of force exerted by the cargo on the aircraft; c is the average aerodynamic chord length; △M=-m0g·△X; in, m0 is the total mass of the aircraft and cargo before cargo is released; △X is the offset of the aircraft’s center of gravity after cargo is dropped; △X=X1-X0; in, X1 is the location of the aircraft’s center of gravity after cargo is dropped; X0 is the total center of gravity of the aircraft and cargo before cargo is dropped In the elevator trim additional deflection angle calculation module, the additional elevator trim deflection angle △δ is generated by integrating the aircraft weight change e1 , and after the cargo is dropped, the aircraft's center of gravity changes, resulting in an additional elevator trim angle △δ e2 , get the additional deflection angle △δ for elevator trim e , specifically: △δ e =△δ e1 +△δ e2 。 14. The system for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 13, characterized in that: Also includes: The module for calculating the additional deflection angle of the elevator trim generated by the angle correction amount generated by the elevator change is used to calculate the additional deflection angle △δ generated by the angle correction amount generated by the elevator change. ex ; The elevator trim additional deflection angle correction calculation module is used to generate the angle of attack correction amount based on the elevator change, and the generated elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 .

15. The system for determining the additional deflection angle of the elevator trim after cargo delivery to an aircraft according to claim 14, characterized in that: In the calculation module of the additional deflection angle of the elevator trim generated by the angle correction amount generated by the elevator change, the angle correction amount generated by the elevator change is calculated, and the additional deflection angle of the elevator trim generated is △δ ex , specifically: C mα ·△α x +C m,δe ·△δ ex =0; in, △α x is the elevator change △δ e The additional lift generated is △C L , the resulting angle of attack correction; C L,δe △δ e +C Lα △α x =0; in, C Lδe is the derivative of the elevator lift coefficient with respect to the control surface; In the elevator trim additional deflection angle correction calculation module, the elevator change generates an angle of attack correction, and the resulting elevator trim additional deflection angle △δ ex , add an additional deflection angle △δ to the elevator trim e Make corrections and obtain the corrected elevator trim additional deflection angle △δ e0 , specifically: △δ e0 =△δ e +△δ ex 。

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