Method for calculating the sink velocity of the nose landing gear in the free-flight hooking situation of a carrier-based aircraft

Abstract

The application provides a method for calculating the sinking speed of a front landing gear under a free flight hooking condition of a carrier-based aircraft, and belongs to the technical field of landing gear load calculation of carrier-based aircrafts. The method comprises the following steps: regarding the whole landing gear as a rigid body, and obtaining the sinking speed of the aircraft in the vertical plane according to relevant standards; obtaining the sinking speed caused by the pitch rate of the aircraft by using the dynamic equation of the center of mass of the aircraft to obtain an initial calculation formula of the pitch rate, simplifying the preliminary calculation formula of the pitch rate to obtain a calculation formula of the pitch rate, and obtaining the rotation speed of the aircraft in the vertical plane during the landing process; and synthesizing the sinking speed of the aircraft in the vertical plane and the rotation speed in the vertical plane to obtain the sinking speed of the front landing gear under the free flight hooking condition. The method of the application makes up for the deficiency of the specification requirements, and introduces the horizontal and vertical overload coefficients in the calculation of the pitch rate, thereby increasing the universality and flexibility of the sinking speed calculation.

Description

Technical Field

[0001] This application belongs to the field of carrier-based aircraft landing gear load calculation technology, and specifically relates to a method for calculating the sinking speed of the nose landing gear under the condition of free flight hooking of a carrier-based aircraft. Background Technology

[0002] Formula for calculating the pitch rate of an aircraft under free-flight hook-up conditions:

[0003] (1)

[0004] In the formula: V TD The grounding limit is given by L; the aircraft lift is given by m; the aircraft mass is given by g; and the acceleration due to gravity is given by g.

[0005] The nose landing gear's descent speed can generally be calculated using the pitch rate from Equation 1. However, this pitch rate formula only provides the requirement for calculating the initial engagement moment in free-flight hook-up scenarios, which is of significant guiding importance for establishing simulation models. However, it lacks guidance for calculating the descent speed at the instant the nose landing gear contacts the deck after the arresting hook engages; furthermore, at this moment, it assumes the aircraft is a rigid body, and its motion is a superposition of rotation and translation within the vertical plane of symmetry. Therefore, this formula has certain limitations in calculating the nose landing gear descent speed under free-flight hook-up conditions. Summary of the Invention

[0006] The purpose of this application is to provide a method for calculating the nose landing gear sinking speed of a carrier-based aircraft under free flight hook-up conditions, in order to solve or mitigate at least one of the problems in the background art.

[0007] The technical solution of this application is: a method for calculating the nose landing gear sinking speed of a carrier-based aircraft under free flight hook-up conditions, including:

[0008] Treating the entire landing gear as a rigid body, the vertical translational descent velocity of the aircraft is obtained according to relevant standards.

[0009] The pitch rate is calculated by using the dynamic equation of the aircraft's center of mass to obtain the descent velocity caused by the aircraft's pitch rate. The initial calculation formula for the pitch rate is then simplified to obtain the final calculation formula for the pitch rate, which in turn gives the aircraft's rotational speed in the vertical plane during the landing process.

[0010] The vertical translational descent speed and the rotational speed in the vertical plane of the composite aircraft are used to obtain the nose landing gear descent speed under free flight hook conditions.

[0011] Preferably, the vertical translational descent velocity of the aircraft is:

[0012]

[0013] In the formula: This represents the average aircraft engagement speed.

[0014] This is the vertical translational descent velocity of the aircraft.

[0015] Preferably, the dynamic equation of the aircraft's center of mass is:

[0016]

[0017] Where: m is the aircraft's landing mass, in kg;

[0018] V E The engagement speed is in m / s;

[0019] The pitch rate;

[0020] L represents lift, N;

[0021] F is the reaction force exerted by the aircraft on the landing gear, in N;

[0022] P is the engine thrust, in N;

[0023] T represents the resistance force, N;

[0024] θ is the pitch angle;

[0025] γ is the glide slope angle;

[0026] β is the angle between the arresting hook and the horizontal plane;

[0027] After simplification, the initial formula for calculating the pitch rate is obtained as follows:

[0028] .

[0029] Preferred, assuming The pitch rate calculation formula is simplified from the initial pitch rate calculation formula to obtain the pitch rate calculation formula:

[0030] (5)

[0031] Where: n z The vertical load factor of the main landing gear impact on the ship is the average sinking speed.

[0032] n x The heading load coefficient is the resultant of engine thrust and arresting force.

[0033] α is the angle of attack.

[0034] Preferably, the aircraft's rotational speed in the vertical plane during landing is:

[0035] In the formula: a is the horizontal distance from the aircraft's center of gravity to the front.

[0036] Preferably, the nose landing gear descent speed under the free-flight hook-on condition is: .

[0037] Based on the rigid body dynamics equations of an aircraft, this application establishes a formula for calculating the nose landing gear sinking speed under free flight hook-up conditions, which makes up for the deficiencies in the standard requirements. Furthermore, it introduces the air and vertical overload coefficients into the pitch rate calculation, increasing the universality and flexibility of the sinking speed calculation. Attached Figure Description

[0038] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0039] Figure 1 This is a schematic diagram of the method flow of this application.

[0040] Figure 2 This is a diagram illustrating the forces acting on the aircraft's center of mass at the moment of landing.

[0041] Figure 3 This is a diagram illustrating a hook-on situation during free flight. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0043] This application provides a method for calculating the nose landing gear sinking speed under free-flight hook-up conditions of carrier-based aircraft. It considers the influence of directional overload and vertical overload on the sinking speed and finally gives the calculation formula for the nose landing gear sinking speed. Based on this, the buffer performance is analyzed by combining the equivalent mass of the nose landing gear, so that the vertical load of the nose landing gear under free-flight hook-up (FFE) conditions can be obtained quickly, providing support for the evaluation of the vertical load of the nose landing gear under free-flight hook-up conditions.

[0044] like Figure 1 As shown, the method for calculating the nose landing gear sinking speed of a carrier-based aircraft under free flight hook-up conditions provided in this application includes the following steps:

[0045] Step 1: The vertical translational descent speed of the aircraft

[0046] Treating the entire landing gear as a rigid body, the vertical translational descent velocity of the aircraft is the average descent velocity during aircraft landing. This calculation formula can be obtained from GJB67.4-2008:

[0047] (2)

[0048] In the formula: The average aircraft engagement speed is expressed in km / h. This represents the descent speed of the aircraft during vertical translation.

[0049] Step 2: Aircraft pitch rate considering vertical and yaw load factors

[0050] like Figure 2 As shown in the force diagram of the aircraft, the descent velocity caused by the aircraft's pitch rate is calculated using the dynamic equations of the aircraft's center of mass:

[0051] (3)

[0052] Where: m is the aircraft's landing mass, in kg;

[0053] V E The engagement speed is in m / s;

[0054] The pitch rate;

[0055] L represents lift, N;

[0056] F is the reaction force exerted by the aircraft on the landing gear, in N;

[0057] P is the engine thrust, in N;

[0058] T represents the resistance force, N;

[0059] θ is the pitch angle;

[0060] γ is the glide slope angle;

[0061] β is the angle between the arresting hook and the horizontal plane.

[0062] The pitch rate is obtained by simplifying Equation 3 as follows:

[0063] (4)

[0064] Assumption For equation 4, we have:

[0065] (5)

[0066] Where: n z n is the vertical load factor for the main landing gear impact on the ship, corresponding to the average sinking velocity. x α is the heading load coefficient resulting from the combined engine thrust and arresting force; α is the angle of attack.

[0067] The aircraft's rotational speed in the vertical plane during landing is:

[0068] (6)

[0069] In the formula: a is the horizontal distance from the aircraft's center of gravity to the front of the plane, in meters.

[0070] Step 3: Synthesize the nose landing gear descent speed

[0071] like Figure 3 The diagram showing the free-flight hook-up situation, combined with the sinking velocity formula and pitch rate formula from steps one and two, yields the nose landing gear sinking velocity:

[0072] (7)

[0073] Assume the average engagement speed of a certain aircraft =350km / h, combined speed is =379km / h, aircraft lift is 33.8t, aircraft weight is 26t, vertical overload coefficient =4, heading load factor =3, the angle of attack of the aircraft is =8°, the distance from the nose landing gear to the center of gravity is a=6m, substituting into the calculation formula, the nose landing gear sinking speed can be obtained. =3.645m / s.

[0074] Based on the rigid body dynamics equations of an aircraft, this application establishes a formula for calculating the nose landing gear sinking speed under free flight hook-up conditions, which makes up for the deficiencies in the standard requirements. Furthermore, it introduces the air and vertical overload coefficients into the pitch rate calculation, increasing the universality and flexibility of the sinking speed calculation.

[0075] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for calculating the sinking speed of the nose landing gear when a carrier-based aircraft is hooked during free flight, characterized in that... include: Treating the entire landing gear as a rigid body, the vertical translational descent velocity of the aircraft is obtained according to relevant standards. The vertical translational descent velocity of the aircraft is: In the formula: This represents the average aircraft engagement speed. This represents the vertical translational descent velocity of the aircraft. The pitch rate is calculated by using the dynamic equation of the aircraft's center of mass to obtain the descent velocity caused by the aircraft's pitch rate. This initial pitch rate calculation formula is then simplified to obtain the final pitch rate calculation formula, which gives the aircraft's rotational velocity in the vertical plane during landing. The dynamic equation of the aircraft's center of mass is: In the formula: m is the aircraft's landing mass; V E For the engagement speed; Let L be the pitch rate; F be the lift; F be the reaction force exerted by the aircraft on the landing gear; P be the engine thrust; T be the arresting force; θ be the pitch angle; γ be the glide slope angle; and β be the angle between the arresting hook and the horizontal plane. After simplification, the initial formula for calculating the pitch rate is: ； Assumption The pitch rate calculation formula is simplified from the initial pitch rate calculation formula to obtain the pitch rate calculation formula: In the formula: n z n is the vertical load factor for the main landing gear impact on the ship, corresponding to the average sinking velocity. x The yaw load coefficient is the sum of engine thrust and arresting force; α is the angle of attack; the aircraft's rotational speed in the vertical plane during landing is: In the formula: a is the horizontal distance from the aircraft's center of gravity to the front of the plane; The nose landing gear descent speed under free-flight hook-up conditions is obtained by combining the vertical translational descent speed and the rotational speed in the vertical plane of the composite aircraft. The nose landing gear descent speed under free-flight hook-up conditions is: 。

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