CATIA secondary development-based seaplane water surface transverse stability calculation method

Abstract

The invention provides a CATIA secondary development-based seaplane water surface transverse stability calculation method, which comprises the following steps of: determining a water surface profile of an airplane in still water, and constructing a three-dimensional model of the airplane in CATIA; carrying out floating state analysis and calculation on the airplane on the water surface; obtaining the drainage volume and buoyancy center coordinates of the ship body and the buoy below the water surface line; establishing a waterline plane with a heeling angle; carrying out repeated iterative calculation by taking the drainage volume, the heeling angle and the trim angle of the ship body and the buoy as iterative factors for calculation, and constraining and optimizing conditions until floating state parameters meeting optimization design conditions are obtained; according to the floating state parameters, the gravity overturning moment and the buoy restoring moment of the airplane at different heeling angles are calculated, then according to stress analysis, other overturning / restoring moments of the airplane are superposed, the water surface transverse stability is calculated, and the water surface transverse stability of the airplane is evaluated. The method has remarkable advantages in the aspects of improving the calculation efficiency and the calculation accuracy, enhancing the design flexibility, performing visual analysis, optimizing floating state parameters, expanding the application range and the like.

Description

Technical Field

[0001] The invention relates to the technical field of seaplane design, and in particular to a method for calculating the surface lateral stability of a seaplane based on secondary development of CATIA. Background Art

[0002] When a seaplane is stationary or gliding at low or medium speed on the water, the balance state of the aircraft when it is floating upright is destroyed by external forces. The aircraft gradually deviates from the balance state and tilts laterally around the longitudinal axis, which may cause the aircraft to capsize. Surface lateral stability is an analytical method to evaluate whether an aircraft is safe.

[0003] The lateral stability of an aircraft on the water surface is mainly determined by analyzing and comparing the overturning moment and the restoring moment, and judging whether the lateral stability meets the requirements based on the numerical comparison of the two. The traditional approach is to calculate the displacement and center of buoyancy of the aircraft hull and pontoon respectively according to the different lateral floating states of the aircraft on the water surface, and use the vertical integral method along the draft direction for calculation. In actual engineering applications, two methods are usually used: computer calculation and manual calculation. The former can be realized through the stability formula, and the latter is mostly in the form of a table, processed and calculated according to the hull / pontoon line diagram. No matter which of the above methods is used for calculation, its parameter variables are many, it is easy to make mistakes, and it is inefficient. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the lateral stability of a seaplane on the water surface based on CATIA secondary development, which is simple in operation, fast and convenient, in view of the shortcomings of the above-mentioned calculation method, so as to improve the calculation accuracy and efficiency.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA, the method comprising the following steps:

[0007] Determine the water line of the aircraft in still water and build a 3D model of the aircraft in CATIA;

[0008] According to the different weights and centers of gravity of the aircraft, the product engineering optimization module of CATIA is used to analyze and calculate the floating state of the aircraft on the water surface with the aircraft gravity and buoyancy, center of gravity position and center of buoyancy position as constraints;

[0009] Establish a plane between the water surface line and the Y axis, segment the hull and pontoon models with this plane, and use CATIA's measurement tools to obtain the displacement volume and buoyancy center coordinates of the hull and pontoon below the water surface line;

[0010] The plane established by the waterline and the Y axis is used as a reference, and the plane is rotated with the waterline as the axis of rotation to establish a waterline plane with a heel angle;

[0011] The displacement volume, heel angle and trim angle of the hull and pontoon are used as iterative factors for calculation. The product engineering optimization module of CATIA is used to perform repeated iterative calculations, and through constraints and optimization conditions, the floating parameters that meet the optimization design conditions are obtained.

[0012] Based on the floating parameters obtained by iterative calculation, the aircraft gravity overturning moment and float restoring moment at different heel angles are calculated, and then other overturning / restoring moments of the aircraft are superimposed according to the force analysis to calculate the lateral stability on the water surface;

[0013] Based on the calculated lateral stability parameters, the aircraft's lateral stability on the water surface is evaluated.

[0014] According to a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA provided by the present invention, before determining the water surface line of the aircraft in still water, the following steps are further performed:

[0015] Determine and calculate the status of the aircraft's lateral stability on the water surface, including aircraft weight, center of gravity, and related shape numerical models.

[0016] According to a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA provided by the present invention, when establishing a waterline plane with a heel angle, the rotation angle starts from 0 degrees and gradually increases to the limited heel angle of the aircraft, and the rotation angle range is the heel angle range of the aircraft.

[0017] According to a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA provided by the present invention, the buoyancy parameters include the position of the center of buoyancy of the aircraft when the aircraft is in a floating and balanced state at different heel angles, the displacement volume of the hull and the displacement volume of the pontoon, the aircraft gravity overturning arm and the pontoon restoring arm.

[0018] According to a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA provided by the present invention, when calculating the floating parameters, the total weight, center of gravity coordinates, and heel angle of the aircraft are used as input parameters, and the CATIA product engineering optimization module is called and set in the optimization command;

[0019] Select Constraint Type Only as the Optimization Type;

[0020] Select bow draft, stern draft or select trim angle, bow or stern draft as free variables to control the waterline;

[0021] The constraint conditions are selected as follows: the difference between buoyancy and aircraft weight = 0kg, the longitudinal distance from the center of buoyancy to the center of gravity = 0mm, and the tolerance is set;

[0022] In CATIA, build the optimization command based on the above input parameters and optimization settings;

[0023] After the settings are completed, call the run optimization command to perform the calculation.

[0024] According to a method for calculating the surface lateral stability of a seaplane based on CATIA secondary development provided by the present invention, when calculating the surface lateral stability, according to design requirements and test requirements, a series of combinations of different weights, centers of gravity, and heel angles are set through a program, and each combination is used as an input parameter;

[0025] For each input parameter combination that meets the optimization conditions, output the aircraft gravity overturning arm and float restoring arm under each combination; wherein these arms are calculated by measuring the lateral distance between the center of buoyancy and the center of gravity and combining the weight and buoyancy of the aircraft;

[0026] Based on the force analysis, combine the other overturning / restoring moments of the aircraft and superimpose them on the gravity overturning moment and the float restoring moment;

[0027] The aircraft's lateral stability index on the water surface is calculated using the superimposed total overturning moment and total restoring moment.

[0028] According to a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA provided by the present invention, the calculation formula of the buoy restoring moment is as follows:

[0029] M re =δ ft ×L' ft

[0030] Among them, δ ft is the displacement of the buoy, in kg; L' ft is the buoy restoring arm, in m.

[0031] According to a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA provided by the present invention, the calculation formula of the aircraft gravity overturning moment is as follows:

[0032] M un =W TO ×L' un

[0033] Among them, W TO is the weight of the aircraft, excluding the displacement weight of the floats, in kg; L' un It is the overturning arm of the aircraft entering the water, excluding the part where the float enters the water, and the unit is m.

[0034] According to a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA provided by the present invention, the overturning moment of the aircraft is M H =F(θ)(kg·m);

[0035] Restoring moment of the aircraft MR =f(θ)(kg·m);

[0036] The static balance criterion of an aircraft is as follows:

[0037]

[0038] It can be seen that compared with traditional manual calculation or solutions based on other software, the present invention has the following beneficial effects:

[0039] 1. The present invention can quickly and effectively calculate and derive the buoyancy center position of the seaplane under different configurations and different heel angles, the displacement volume of the hull and pontoon, the total gravity overturning arm and the pontoon restoring arm, and provide data support for designers to calculate the overturning moment and the restoring moment, avoiding the tedious operations of designers and human errors, and can quickly improve the calculation efficiency and accuracy.

[0040] 2. The present invention makes full use of the 3D modeling and engineering optimization functions of CATIA to achieve full automation from model construction to floating state analysis and then to lateral stability calculation, which greatly improves calculation efficiency and accuracy and reduces the possibility of human error.

[0041] 3. The present invention uses CATIA's measurement tools to accurately obtain the displacement volume and buoyancy center coordinates of the hull and pontoon below the water surface line, and uses the product engineering optimization module to perform accurate floating state analysis and iterative calculations, thereby ensuring the accuracy of the calculation results.

[0042] 4. The present invention can perform flexible flotation analysis and calculation according to aircraft configurations of different weights and centers of gravity. By adjusting input parameters, the water surface lateral stability under different design or loading conditions can be quickly evaluated, providing strong support for design optimization.

[0043] 5. CATIA's 3D modeling function makes the entire calculation process highly visualized. You can intuitively see the changes in the aircraft's floating state on the water surface and the force conditions at different roll angles, which helps to better understand the problem and make more reasonable decisions.

[0044] 6. This method is not only suitable for the calculation of the water surface lateral stability of seaplanes, but can also be expanded as needed to be used for the buoyancy and stability analysis of other types of surface or water vehicles.

[0045] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The present invention is a flow chart of an embodiment of a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA.

[0047] Figure 2 It is a force diagram of a seaplane in an embodiment of a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0050] See also Figure 1 and Figure 2 The present invention provides a method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA, the method comprising the following steps:

[0051] Step S1, determine the water surface line of the aircraft in still water, and build a three-dimensional model of the aircraft in CATIA, including all key components such as the fuselage and floats.

[0052] Step S2, according to the different weights and centers of gravity of the aircraft, the product engineering optimization module of CATIA is used to analyze and calculate the floating state of the aircraft on the water surface with the aircraft gravity and buoyancy, center of gravity position and center of buoyancy position as constraints. The parameters in the model (such as weight distribution, float size, etc.) are adjusted to make the aircraft float and balance under given conditions.

[0053] Step S3, establish a plane between the water surface line and the Y axis, segment the hull and buoy model with the plane, and use the CATIA measurement tool to obtain the displacement volume and buoyancy center coordinates of the hull and buoy below the water surface line. The accuracy of the segmentation plane can be ensured so that the displacement volume and centroid can be accurately calculated.

[0054] Step S4, taking the plane established by the waterline and the Y-axis as a reference, rotating the plane with the waterline as the axis of rotation, and establishing a waterline plane with a heel angle.

[0055] Step S5, using the displacement volume of the hull and pontoon, the heel angle, and the pitch angle as the iterative factors of the calculation, using the product engineering optimization module of CATIA to perform repeated iterative calculations, through constraints and optimization conditions, until the floating parameters that meet the optimization design conditions are obtained. Among them, by setting reasonable iterative conditions and convergence standards, the accuracy and stability of the calculation results are ensured.

[0056] Step S6, according to the floating parameters obtained by iterative calculation, the aircraft gravity overturning moment and the buoy restoring moment at different heel angles are calculated, and then other overturning / restoring moments of the aircraft are superimposed according to the force analysis to calculate the lateral stability on the water surface.

[0057] Step S7, evaluating the lateral stability of the aircraft on the water surface according to the calculated lateral stability parameters.

[0058] Among them, the calculation method can be used for different weight / center of gravity conditions of the aircraft, including weight / center of gravity under conditions such as fuel imbalance on the left and right wings and load imbalance.

[0059] In this embodiment, the product engineering optimization module of CATIA is used to conveniently set constraints and optimization targets, and find the optimal floating parameters through iterative calculation. This optimization-based method is more efficient and accurate than the traditional trial and error method.

[0060] In this embodiment, CATIA, as a powerful CAD / CAE platform, provides a complete data management function. The data and models calculated by this method can be easily stored, retrieved and reused, providing strong support for subsequent design optimization and performance evaluation.

[0061] In this embodiment, before determining the water surface line of the aircraft in still water, the following steps are further performed:

[0062] Determine and calculate the status of the aircraft's lateral stability on the water surface, including aircraft weight, center of gravity, and related shape numerical models.

[0063] In this embodiment, when establishing the waterline plane with the heel angle, the rotation angle starts from 0 degrees and gradually increases to the limited heel angle of the aircraft. The rotation angle range is the heel angle range of the aircraft.

[0064] In this embodiment, the floating parameters include the position of the center of buoyancy of the aircraft when the aircraft is floating and in equilibrium at different heel angles, the displacement volume of the hull and the displacement volume of the pontoon, the aircraft gravity overturning arm and the pontoon restoring arm.

[0065] In this embodiment, when calculating the floating parameters, the total weight, center of gravity coordinates, and heel angle of the aircraft are used as input parameters, and the CATIA product engineering optimization module is called and set in the optimization command;

[0066] Select Constraint Type Only as the Optimization Type;

[0067] Select bow draft, stern draft or select trim angle, bow or stern draft as free variables to control the waterline;

[0068] The constraint conditions are selected as follows: the difference between buoyancy and aircraft weight = 0kg, the longitudinal distance from the center of buoyancy to the center of gravity = 0mm, and the tolerance is set;

[0069] In CATIA, build the optimization command based on the above input parameters and optimization settings;

[0070] After the settings are completed, call the run optimization command to perform the calculation.

[0071] In this embodiment, when calculating the lateral stability on the water surface, according to the design requirements and test requirements, a series of combinations of different weights, centers of gravity, and heel angles are set through the program, and each combination is used as an input parameter. These combinations can cover the typical operating conditions and extreme situations of the aircraft.

[0072] For each input parameter combination that meets the optimization conditions, output the aircraft gravity overturning arm and float restoring arm under each combination; wherein these arms are calculated by measuring the lateral distance between the center of buoyancy and the center of gravity and combining the weight and buoyancy of the aircraft;

[0073] Based on the force analysis, combine the other overturning / restoring moments of the aircraft and superimpose them on the gravity overturning moment and the float restoring moment;

[0074] The aircraft's lateral stability index on the water surface is calculated using the superimposed total overturning moment and total restoring moment.

[0075] Furthermore, the total weight of the aircraft includes the weight of the fuselage, engine, fuel, passengers and cargo; the center of gravity coordinates are the three-dimensional coordinates of the center of gravity of the aircraft, usually expressed as (Xc, Yc, Zc), where Xc, Yc, and Zc represent the lateral, longitudinal, and vertical positions of the center of gravity in the aircraft coordinate system, respectively; the roll angle is the angle of rotation of the aircraft around its longitudinal axis (i.e., the Y axis), indicating the tilt state of the aircraft on the water surface.

[0076] Furthermore, selecting the "constraint only" type means that the optimization process will only consider satisfying the given constraints without pursuing the minimization or maximization of a specific objective function.

[0077] Further, select the bow draft and stern draft: these two variables directly determine the position of the waterline, which in turn affects the displacement volume and the floating state. By adjusting the draft depth of the bow and stern, the floating state of the aircraft can be controlled to meet the balance between buoyancy and gravity. Or select the trim angle, bow or stern draft: it allows to consider the trim angle and draft depth at the same time, providing more degrees of freedom for optimization. The change of the trim angle will also affect the position of the center of buoyancy, and thus affect the stability of the floating state.

[0078] Further, the difference between buoyancy and aircraft weight = 0kg: ensure that the buoyancy of the aircraft in the water is equal to its total weight to achieve a floating state. Set the tolerance to take into account calculation errors and small fluctuations in actual conditions.

[0079] Further, the longitudinal distance from the center of buoyancy to the center of gravity = 0 mm: ensure that the center of buoyancy and the center of gravity coincide or are very close in the longitudinal direction (Y axis) to reduce the overturning moment caused by the center of gravity offset. Similarly, the tolerance is set to take into account the slight deviation of the actual situation.

[0080] Furthermore, the calculation process of this embodiment specifically includes:

[0081] Constructing optimization commands: In CATIA, construct optimization commands based on the above input parameters and optimization settings. This includes defining free variables, constraints, tolerances, etc.

[0082] Call the Run Optimization command: Execute the optimization command, and CATIA will automatically adjust the values ​​of the free variables to meet all constraints. During the iteration process, CATIA will continuously calculate the current floating parameters (such as the center of buoyancy, displacement volume, etc.) and check whether the constraints are met.

[0083] Result evaluation: After the optimization is completed, check whether the optimization results meet the design requirements. If they do, record the current floating parameters; if they do not, you may need to adjust the input parameters or optimization settings and rerun the optimization command.

[0084] Subsequent analysis: Based on the optimized buoyancy parameters, the lateral stability of the aircraft can be further analyzed. By calculating parameters such as the gravity overturning moment and buoy restoring moment at different heel angles, the lateral stability performance of the aircraft can be evaluated.

[0085] Furthermore, the setting of the optimization calculation program includes: writing or setting the optimization calculation program in CATIA or other software environments supporting engineering optimization. The program needs to be able to receive weight, center of gravity and heel angle as input parameters, and call CATIA's product engineering optimization module or other related tools to perform iteration and optimization operations.

[0086] Furthermore, for each input parameter combination: set the initial buoyancy parameters (such as bow draft, stern draft or trim angle, etc.), which can be estimated values ​​or default values; according to the current buoyancy parameters, use CATIA's model analysis and measurement functions to calculate the buoyancy, center of buoyancy position, etc., and compare them with the input gravity and center of gravity position. By adjusting the buoyancy parameters (free variables), the buoyancy and gravity are balanced, and the center of buoyancy and center of gravity coincide within the allowable range; set optimization conditions, such as the difference between buoyancy and gravity is close to zero, and the longitudinal distance between the center of buoyancy and the center of gravity is less than the tolerance; check whether the iteration results meet the optimization conditions. If not, continue the iteration; if satisfied, record the current buoyancy parameters and calculation results.

[0087] In this embodiment, the calculation formula of the buoy restoring moment is as follows:

[0088] M re =δ ft ×L' ft

[0089] Among them, δ ft is the displacement of the buoy, in kg; L' ft is the buoy restoring arm, in m.

[0090] In this embodiment, the calculation formula of the aircraft gravity overturning moment is as follows:

[0091] M un =W TO ×L' un

[0092] Among them, W TO is the weight of the aircraft, excluding the displacement weight of the floats, in kg; L' un It is the overturning arm of the aircraft entering the water, excluding the part where the float enters the water, and the unit is m.

[0093] In this embodiment, the overturning moment of the aircraft is M H =F(θ)(kg·m);

[0094] Restoring moment of the aircraft M R =f(θ)(kg·m);

[0095] The static balance criterion of an aircraft is as follows:

[0096]

[0097] Furthermore,

[0098] In practical applications, when evaluating the lateral stability of a seaplane on the water, the following steps are specifically included:

[0099] Determine and calculate the status of the aircraft's lateral stability on the water surface, including aircraft weight, center of gravity, and related shape numerical models.

[0100] Call the CAITA part editing module and open the aircraft-related shape digital model, import the center of gravity coordinates, establish the initial waterline, create a plane between the waterline and the Y-axis, rotate the plane with the waterline as the axis and the input heel angle as the angle, establish the waterline plane, and divide the hull / float volume under the waterline plane. The displacement and buoyancy center coordinates of the hull / float under the water surface can be quickly obtained through the CATIA built-in measurement module.

[0101] Call the CAITA product engineering optimization module, select "constraint only" for the optimization type, take the aircraft's longitudinal inclination angle (or bow draft, stern draft) as a free variable, select "the difference between the aircraft's buoyancy and the aircraft's weight = 0kg", "the longitudinal distance from the aircraft's center of buoyancy to the aircraft's center of gravity = 0mm" in the constraints, and set a certain tolerance.

[0102] After completing the settings, call the run command to start the calculation. Use the CATIA product engineering optimization module, through constraints and optimization, iterate repeatedly until the optimization design conditions are met, and get the waterline plane of the aircraft in a floating and balanced state at a given heel angle. Use CATIA's built-in measurement module to measure the displacement volume and center of buoyancy of the hull / float below the waterline plane, and calculate the aircraft gravity overturning lever arm and float restoring lever arm through the center of buoyancy position and displacement volume.

[0103] Then change the aircraft's roll angle, and repeatedly call the CAITA product engineering optimization module to perform the above calculations to obtain the aircraft's waterline plane when the aircraft is floating and balanced at different roll angles. Use CATIA's built-in measurement module to measure the displacement volume and center of buoyancy of the hull / float below the waterline plane, and calculate the aircraft's gravity overturning lever arm and float restoring lever arm through the center of buoyancy position and displacement volume.

[0104] The calculation results under different heel angles, the difference between the aircraft buoyancy and the aircraft weight under the corresponding state, and the longitudinal distance from the aircraft buoyancy center to the aircraft center of gravity are exported to check whether the constraint conditions meet the requirements, verify the validity of the results, and ensure the validity of the output data.

[0105] The aircraft gravity overturning moment and float restoring moment are calculated based on the exported data, and then other overturning / restoring moments of the aircraft (such as crosswind overturning moment, propeller reaction moment, asymmetric pull rolling moment, fuel imbalance moment, etc.) are superimposed according to the force analysis to calculate the water surface lateral stability.

[0106] In summary, the present invention can quickly and effectively calculate and derive the buoyancy center position of the seaplane under different configurations and different heel angles, the displacement volume of the hull and pontoon, the total gravity overturning lever arm and the pontoon restoring lever arm, and provide data support for designers to calculate the overturning moment and the restoring moment, avoiding the cumbersome operation of the designers and human error, and can quickly improve the calculation efficiency and accuracy. The present invention makes full use of the three-dimensional modeling and engineering optimization functions of CATIA, and realizes the full automation from model construction to floating state analysis and then to lateral stability calculation, which greatly improves the calculation efficiency and accuracy and reduces the possibility of human error. The present invention accurately obtains the displacement volume and buoyancy center coordinates of the hull and pontoon below the water line through the measurement tool of CATIA, and uses the product engineering optimization module to perform accurate floating state analysis and iterative calculation, thereby ensuring the accuracy of the calculation results. The present invention can perform flexible floating state analysis and calculation according to the configuration of aircraft with different weights and centers of gravity. By adjusting the input parameters, the water surface lateral stability under different design or loading conditions can be quickly evaluated, providing strong support for design optimization.

[0107] Furthermore, CATIA's 3D modeling function makes the entire calculation process highly visual, allowing you to intuitively see the changes in the aircraft's floating state on the water surface and the force conditions at different roll angles, which helps to better understand the problem and make more reasonable decisions.

[0108] Furthermore, this method is not only applicable to the calculation of the water surface lateral stability of seaplanes, but can also be expanded as needed to be used for the buoyancy and stability analysis of other types of surface or water vehicles.

[0109] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0110] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for calculating the lateral stability of a seaplane on the water surface based on secondary development of CATIA, characterized in that: The following steps are involved: Determine the water line of the aircraft in still water and build a 3D model of the aircraft in CATIA; According to the different weights and centers of gravity of the aircraft, the product engineering optimization module of CATIA is used to analyze and calculate the floating state of the aircraft on the water surface with the aircraft gravity and buoyancy, center of gravity position and center of buoyancy position as constraints; Establish a plane between the water surface line and the Y axis, segment the hull and pontoon models with this plane, and use CATIA's measurement tools to obtain the displacement volume and buoyancy center coordinates of the hull and pontoon below the water surface line; The plane established by the waterline and the Y axis is used as a reference, and the plane is rotated with the waterline as the axis of rotation to establish a waterline plane with a heel angle; The displacement volume, heel angle and trim angle of the hull and pontoon are used as iterative factors for calculation. The product engineering optimization module of CATIA is used to perform repeated iterative calculations, and through constraints and optimization conditions, the floating parameters that meet the optimization design conditions are obtained. According to the floating parameters obtained by iterative calculation, the aircraft gravity overturning moment and float restoring moment at different heel angles are calculated, and then the other overturning / restoring moments of the aircraft are superimposed according to the force analysis to calculate the lateral stability on the water surface; Based on the calculated lateral stability parameters, the aircraft's lateral stability on the water surface is evaluated.

2. The method according to claim 1, characterized in that: Before determining the aircraft's surface line in still water, also perform: Determine and calculate the status of the aircraft's lateral stability on the water surface, including aircraft weight, center of gravity, and related shape numerical models.

3. The method according to claim 1, characterized in that: When establishing a waterline plane with a roll angle, the rotation angle starts from 0 degrees and gradually increases to the aircraft's limited roll angle. The rotation angle range is the aircraft's roll angle range.

4. The method according to claim 1, characterized in that: The floating parameters include the position of the center of buoyancy of the aircraft when the aircraft is in a floating and balanced state at different heel angles, the displacement volume of the hull and the displacement volume of the pontoon, the aircraft gravity overturning arm and the pontoon restoring arm.

5. The method according to claim 4, characterized in that: When calculating the floating parameters, the total weight, center of gravity coordinates, and heel angle of the aircraft are used as input parameters, and the CATIA product engineering optimization module is called and set in the optimization command; Select Constraint Type Only as the Optimization Type; Select bow draft, stern draft or select trim angle, bow or stern draft as free variables to control the waterline; The constraint conditions are selected as follows: the difference between buoyancy and aircraft weight = 0kg, the longitudinal distance from the center of buoyancy to the center of gravity = 0mm, and the tolerance is set; In CATIA, build the optimization command based on the above input parameters and optimization settings; After the settings are completed, call the run optimization command to perform the calculation.

6. The method according to claim 1, characterized in that: When calculating the lateral stability on the water surface, a series of combinations of different weights, centers of gravity, and heel angles are set through the program according to the design requirements and test requirements, and each combination is used as an input parameter; For each input parameter combination that meets the optimization conditions, output the aircraft gravity overturning arm and float restoring arm under each combination; wherein these arms are calculated by measuring the lateral distance between the center of buoyancy and the center of gravity and combining the weight and buoyancy of the aircraft; Based on the force analysis, combine the other overturning / restoring moments of the aircraft and superimpose them on the gravity overturning moment and the float restoring moment; The aircraft's lateral stability index on the water surface is calculated using the superimposed total overturning moment and total restoring moment.

7. The method according to claim 1, characterized in that: The calculation formula of the buoy restoring moment is as follows: M re =d ft ×L' ft Among them, δ ft is the displacement of the buoy, in kg; L' ft is the buoy restoring arm, in m.

8. The method according to claim 1, characterized in that: The calculation formula of the aircraft gravity overturning moment is as follows: M un =W TO ×L' un Among them, W TO is the weight of the aircraft, excluding the displacement weight of the floats, in kg; L' un It is the overturning arm of the aircraft entering the water, excluding the part where the float enters the water, and the unit is m.

9. The method according to claim 1, characterized in that: The overturning moment of the aircraft is M H =F(θ)(kg·m); The restoring moment of the aircraft M R =f(θ)(kg·m); The static balance criterion of an aircraft is as follows:

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