A method for calculating trim of a helicopter three-point suspension

Abstract

The application discloses a kind of helicopter three-point hanging trim calculation method, the three-point hanging coupling system of helicopter is modeled, the three-point hanging coupling model of helicopter is obtained, and the balance state quantity of the whole system is calculated based on the model;When modeling, introduce the hanging system model of three sling models and hanging object models, establish the coupling motion equation of helicopter and three hanging systems.The present application can assist in determining the weight distribution principle of multiple independent hanging.

Description

Technical Field

[0001] This invention pertains to helicopter flight dynamics technology and proposes a method for calculating the trim of a helicopter with three-point suspension. Background Technology

[0002] Because helicopters can take off and land vertically, hover precisely, fly at extremely low altitudes, and maneuver flexibly, they are not limited by terrain and have unique advantages in transport performance compared to ground transportation equipment. Sling transport can overcome the size limitations of helicopters, greatly maximizing their transport capabilities, and is an important helicopter flight mission. Three-point sling transport specifically refers to a helicopter having three sling points, each capable of independently slinging cargo. Helicopters with three-point sling transport capability can deploy external loads to three locations in a single mission, not only enriching the helicopter's application scenarios but also saving transportation resources. Modeling three-point sling transport requires considering the motion coupling of multiple sling systems (composed of sling and load models) with the helicopter, making it quite complex. However, current research on the overall flight dynamics modeling and computational analysis of helicopter three-point sling transport is limited. Summary of the Invention

[0003] The purpose of this invention is to design a method for calculating the balance of a helicopter's three-point sling load system. This method involves modeling the helicopter's three-point sling load coupling system and calculating the equilibrium state variables of the entire system. Furthermore, the calculation method described in this invention can assist in determining the weight distribution principles for multiple independent sling loads.

[0004] The technical solution of the present invention is a method for calculating the balance of a helicopter three-point suspension system. The method is characterized by modeling the helicopter three-point suspension coupling system to obtain a helicopter three-point suspension coupling model, and calculating the equilibrium state of the entire system based on the model. During modeling, a suspension system model composed of three sling models and a suspension object model is introduced to establish the coupling motion equations between the helicopter and the three suspension systems.

[0005] In the aforementioned helicopter three-point sling load trim calculation method, the coupled motion equations of the helicopter and the three sling load systems are as follows:

[0006]

[0007] In the formula, m F I F It refers to the mass and moment of inertia of the fuselage; V F , ω F , These are the fuselage velocity, acceleration, angular velocity, and angular acceleration; g (f) It is the gravitational acceleration under the fuselage axis; F (f), M (f) It refers to the resultant aerodynamic forces and moments exerted on the fuselage by all components except the suspension system, and the resultant torque experienced by the fuselage; q is the suspension system number; It is the collection of slings that connect each suspension system to the fuselage; It is the position of the i-th suspension point in the q-th suspension system under the fuselage axis; This is the coordinate transformation matrix for the suspension cables; Ns is the number of suspension cable nodes. It is the position state quantity of the sling node; These are the cable node mass, aerodynamic force, and tensile force; m L,q I L,q These are the mass and moment of inertia of the suspended body in the corresponding suspension system; V L ,q , ω L,q , These are the velocity, acceleration, angular velocity, and angular acceleration of the suspended body. It refers to the aerodynamic forces and torques acting on the suspended body under the body axis system; It is the coordinate transformation matrix of the suspended body; It is the collection of slings that connect the suspension body within each suspension system; It is the position of the i-th suspension point in the q-th suspension system under the body axis of the suspension body.

[0008] In the aforementioned helicopter three-point sling load trim calculation method, the helicopter three-point sling load coupling model also includes a rotor model, which consists of blade motion, airfoil aerodynamic data, and distortion augmented dynamic inflow model; used to calculate the aerodynamic forces and moments exerted by the rotor on the fuselage.

[0009] In the aforementioned helicopter three-point sling load trim calculation method, the helicopter three-point sling load coupling model also includes a fuselage aerodynamic model, which is obtained from wind tunnel tests or CFD aerodynamic data difference; used to calculate the aerodynamic forces and moments acting on the fuselage.

[0010] In the aforementioned helicopter three-point sling load trim calculation method, the helicopter three-point sling load coupling model also includes a tail aerodynamic model, which is obtained from wind tunnel tests or CFD aerodynamic data difference; it is used to calculate the aerodynamic forces and moments applied to the fuselage by the tail surface.

[0011] In the aforementioned helicopter three-point sling load trim calculation method, the helicopter three-point sling load coupling model also includes a tail rotor model, which is similar to the rotor model; it is used to calculate the aerodynamic forces and torques exerted by the tail rotor on the fuselage.

[0012] In the aforementioned helicopter three-point suspension trim calculation method, the helicopter three-point suspension coupling model also includes an aerodynamic interference model, which is established based on wind tunnel tests; it is used to determine the inflow conditions of the fuselage, tail surface, and tail rotor.

[0013] In the aforementioned helicopter three-point suspension trim calculation method, the helicopter three-point suspension coupling model also includes a sling model, which is a segmented lumped mass-spring-damping model; used to establish the tension balance of each sling node.

[0014] In the aforementioned helicopter three-point suspension trim calculation method, the helicopter three-point suspension coupling model also includes a suspended object model, which is a six-degree-of-freedom rigid body model; used to calculate the aerodynamic forces and moments applied to the slings by the suspended object.

[0015] In the aforementioned helicopter three-point sling load trim calculation method, the calculation method for the equilibrium state quantity is as follows:

[0016] During the balancing process, the global Galerkin method is used, and the Fourier coefficients are used to approximate the periodic motion, thereby obtaining the coupled motion equations of the helicopter and the three sling systems that can be used for balancing solutions. Finally, the equilibrium state variables of the helicopter's three-point sling system are obtained through iterative solutions.

[0017] The beneficial effects of this invention: The calculation method in this invention, by modeling the helicopter three-point sling coupling system, realizes the balance calculation of the helicopter's three-point sling, playing an important role in the design and capability demonstration of helicopter three-point sling capacity. Using the balance calculation method in this invention, it can assist in determining principles such as weight distribution for multi-point independent slings and sling swing limits. See details... Figure 2 .

[0018] Depend on Figure 2 As can be seen, the calculation method in this invention can realize the trim calculation for helicopter three-point sling flight. After obtaining the backswing angle of the three slings in the three-point sling flight using the calculation method in this invention, the backswing angle of the slings can be adjusted by adjusting the mass distribution of the three slings, avoiding interference between the three slings, and thus optimizing the weight distribution. After obtaining the balance using the calculation method in this invention, the maximum level flight speed under the sling swing limit can also be determined based on the balance state, providing guidance for determining the flight envelope of the helicopter three-point sling flight. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating three-point suspension.

[0020] Figure 2 The collective pitch, tail rotor pitch, and sling backswing angle results are obtained from the helicopter three-point sling trim calculation method described in this invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] A method for calculating the trim of a helicopter with three-point sling load, see [link / reference]. Figures 1-2 A three-point suspension coupling system for a helicopter is modeled to obtain a three-point suspension coupling model for the helicopter. Based on this model, the equilibrium state variables of the entire system are calculated. During the modeling process, a suspension system model consisting of three sling models and a suspended object model is introduced to establish the coupling motion equations between the helicopter and the three suspension systems.

[0023] The aforementioned equations of motion for the coupling of the helicopter and the three pylon systems are as follows:

[0024]

[0025] In the formula, m F I F It refers to the mass and moment of inertia of the fuselage; V F , ω F , These are the fuselage's velocity, acceleration, angular velocity, and angular acceleration. g (f) It is the gravitational acceleration under the fuselage axis; F (f) , M (f) It refers to the resultant aerodynamic forces and moments exerted on the fuselage by all components except the suspension system, and the resultant torque experienced by the fuselage; q is the suspension system number; It is the collection of slings that connect each suspension system to the fuselage; It is the position of the i-th suspension point in the q-th suspension system under the fuselage axis; This is the coordinate transformation matrix for the suspension cables; Ns is the number of suspension cable nodes. It is the position state quantity of the sling node; These are the cable node mass, aerodynamic force, and tensile force; m L,q I L,q These are the mass and moment of inertia of the suspended body in the corresponding suspension system; V L ,q , ω L,q , These are the velocity, acceleration, angular velocity, and angular acceleration of the suspended body. It refers to the aerodynamic forces and torques acting on the suspended body under the body axis system; It is the coordinate transformation matrix of the suspended body; It is the collection of slings that connect the suspension body within each suspension system; It is the position of the i-th suspension point in the q-th suspension system under the body axis of the suspension body.

[0026] The aforementioned helicopter three-point suspension coupling model also includes a rotor model, which consists of blade motion, airfoil aerodynamic data, and distortion augmented dynamic inflow model; used to calculate the aerodynamic forces and moments exerted by the rotor on the fuselage.

[0027] The aforementioned helicopter three-point suspension coupling model also includes a fuselage aerodynamic model, which is obtained from wind tunnel tests or CFD aerodynamic data difference; used to calculate the aerodynamic forces and moments acting on the fuselage.

[0028] The aforementioned helicopter three-point suspension coupling model also includes a tail aerodynamic model, which is obtained from wind tunnel tests or CFD aerodynamic data difference; used to calculate the aerodynamic forces and moments exerted by the tail on the fuselage.

[0029] The aforementioned helicopter three-point suspension coupling model also includes a tail rotor model, which is similar to the rotor model; it is used to calculate the aerodynamic forces and torques exerted by the tail rotor on the fuselage.

[0030] The aforementioned helicopter three-point suspension coupling model also includes an aerodynamic interference model, which is established based on wind tunnel tests; it is used to determine the inflow conditions of the fuselage, tail surface, and tail rotor.

[0031] The aforementioned helicopter three-point suspension coupling model also includes a sling model, which is a segmented lumped mass-spring-damping model; used to establish the tension balance of each sling node.

[0032] The aforementioned helicopter three-point suspension coupling model also includes a suspended object model, which is a six-degree-of-freedom rigid body model; used to calculate the aerodynamic forces and moments applied to the slings by the suspended object.

[0033] The aforementioned method for calculating equilibrium state quantities is as follows:

[0034] During the balancing process, the global Galerkin method is used, and the Fourier coefficients are used to approximate the periodic motion, thereby obtaining the coupled motion equations of the helicopter and the three sling systems that can be used for balancing solutions. Finally, the equilibrium state variables of the helicopter's three-point sling system are obtained through iterative solutions.

[0035] The above description is merely a specific embodiment of the present invention, providing a detailed description of the invention. Parts not covered herein are conventional techniques. However, the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for calculating the trim of a helicopter with three-point sling load, characterized in that, A three-point sling coupling system for a helicopter is modeled to obtain the helicopter three-point sling coupling model. Based on this model, the equilibrium state variables of the entire system are calculated. During modeling, a sling system model consisting of three sling models and a suspended object model is introduced, and the coupled motion equations between the helicopter and the three sling systems are established. The coupled motion equations between the helicopter and the three sling systems are: ； In the formula, m F , I F It refers to the mass and moment of inertia of the fuselage; These are the fuselage velocity, acceleration, angular velocity, and angular acceleration; g (f) It is the gravitational acceleration under the fuselage axis; F (f) , M (f) It refers to the resultant aerodynamic forces and moments exerted on the fuselage by all components except the suspension system, and the resultant torque experienced by the fuselage; q is the suspension system number; It is the collection of slings that connect each suspension system to the fuselage; It is the position of the i-th suspension point in the q-th suspension system under the fuselage axis; This is the coordinate transformation matrix for the suspension cables; Ns is the number of suspension cable nodes. It is the position state quantity of the sling node; These are the cable node mass, aerodynamic force, and tensile force; m L,q , I L,q These are the mass and moment of inertia of the suspended body in the corresponding suspension system; These are the velocity, acceleration, angular velocity, and angular acceleration of the suspended body. It refers to the aerodynamic forces and torques acting on the suspended body under the body axis system; It is the coordinate transformation matrix of the suspended body; It is the collection of slings that connect the suspension body within each suspension system; It is the position of the i-th suspension point in the q-th suspension system under the body axis of the suspension body.

2. The helicopter three-point sling load trim calculation method according to claim 1, characterized in that, The helicopter three-point suspension coupling model also includes a rotor model, which consists of blade motion, airfoil aerodynamic data, and distortion augmented dynamic inflow model; used to calculate the aerodynamic forces and torques exerted by the rotor on the fuselage.

3. The helicopter three-point sling load trim calculation method according to claim 1, characterized in that, The helicopter three-point suspension coupling model also includes a fuselage aerodynamic model, which is obtained by wind tunnel testing or CFD aerodynamic data difference; used to calculate the aerodynamic forces and moments acting on the fuselage.

4. The helicopter three-point sling load trim calculation method according to claim 1, characterized in that, The helicopter three-point suspension coupling model also includes a tail aerodynamic model, which is obtained by wind tunnel testing or CFD aerodynamic data difference; it is used to calculate the aerodynamic forces and moments exerted by the tail on the fuselage.

5. The helicopter three-point sling load trim calculation method according to claim 1, characterized in that, The helicopter three-point suspension coupling model also includes a tail rotor model, used to calculate the aerodynamic forces and torques exerted by the tail rotor on the fuselage.

6. The helicopter three-point sling load trim calculation method according to claim 1, characterized in that, The helicopter three-point suspension coupling model also includes an aerodynamic interference model, which is established based on wind tunnel tests; it is used to determine the inflow conditions of the fuselage, tail surface, and tail rotor.

7. The helicopter three-point sling load trim calculation method according to claim 1, characterized in that, The helicopter three-point suspension coupling model also includes a sling model, which is a segmented lumped mass-spring-damping model; used to establish the tension balance of each sling node.

8. The helicopter three-point sling load trim calculation method according to claim 1, characterized in that, The helicopter three-point suspension coupling model also includes a suspended object model, which is a six-degree-of-freedom rigid body model; used to calculate the aerodynamic forces and moments applied to the slings by the suspended object.

9. The helicopter three-point sling load trim calculation method according to claim 1, characterized in that, The method for calculating the equilibrium state quantities is as follows: during balancing, the global Galerkin method is used, and the Fourier coefficients are used to approximate the periodic motion, thereby obtaining the coupled motion equations of the helicopter and the three sling systems that can be used for balancing solutions; finally, the equilibrium state quantities of the helicopter's three-point sling system are obtained through iterative solutions.

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