Ejection seat parachute opening control method

Abstract

The present application belongs to the field of aviation, and is a method for controlling the opening of an ejection seat. A departure coordinate system is established for the motion trajectory of the ejection seat after leaving the aircraft. After the ejection seat leaves the aircraft, a motion trajectory of the ejection seat after leaving the aircraft is established according to the departure coordinate system. Then the ejection seat obtains the terrain contour information of the current area, and the opening contour of the current area is determined in combination with the opening height of the survival parachute. The calculation method is simple, and the opening height can be adjusted in time according to the different altitudes of the landing altitude in the current area. When the landing altitude is high, the opening time of the parachute is earlier, and when the landing altitude is low, the opening time of the parachute is later, thereby effectively preventing the parachute from opening too early and causing a long time in the air.

Description

Technical Field

[0001] The present application belongs to the field of aviation, and in particular relates to an ejection seat parachute opening control method. Background Art

[0002] When a pilot ejects for life, the parachute opens at different altitudes depending on the flight area. The parachute opening altitude is determined based on the highest altitude point in the current ejection area. This results in the parachute opening time being based on the highest altitude when the local altitude changes dramatically and the height difference is large. However, the actual landing area of ​​the pilot is at a low altitude, especially in the Himalayas, Hengduan Mountains, Kunlun Mountains, etc. If a pilot ejects while flying in a plateau area, opening the parachute too early will cause the pilot to stay in the air for too long, causing the risk of hypoxia at high altitude.

[0003] Therefore, it is necessary to design a method that can accurately determine the parachute opening time when the parachute opening altitude is the same as or different from the landing altitude. Summary of the invention

[0004] The purpose of this application is to provide an ejection seat parachute opening control method to solve the risk of high-altitude hypoxia caused by the large difference between the parachute opening altitude and the landing altitude in the prior art.

[0005] The technical solution of the present application is: an ejection seat parachute opening control method, comprising: establishing a departure coordinate system according to the motion trajectory of the ejection seat after leaving the aircraft, establishing a data model according to the motion parameters of the ejection seat during ejection, and calculating the motion trajectory of the ejection seat after leaving the aircraft; obtaining the terrain contour information in the current area, and determining the parachute opening contour of the current area according to the parachute opening height of the survival parachute carried by the ejection seat; calculating the intersection of the parachute opening contour and the motion trajectory, and obtaining the parachute opening time after the ejection seat is ejected.

[0006] Preferably, the method for establishing the off-aircraft coordinate system is: setting the coordinate origin to the sea level height corresponding to the current position, the three coordinate axes of the off-aircraft coordinate system are the current aircraft heading x, the ground direction y, the right-hand rule determines the yaw direction z, the aircraft position is (0, y1, 0), and y1 is the aircraft altitude.

[0007] Preferably, the movement trajectory of the ejection seat after leaving the aircraft is:

[0008] The heading motion trajectory of the ejection seat is:

[0009]

[0010] In the formula, C dx is the ejection seat drag coefficient, s x is the frontal area of ​​the ejection seat, m is the mass of the ejection seat, P is the atmospheric pressure, ρ cc is the air density;

[0011] The ground motion trajectory is: y =v y t, where v y =80m / s, t is time.

[0012] Preferably, the aircraft collects current longitude and latitude information while flying, interacts with the ground control center through the longitude and latitude information, obtains terrain contour information of the current area, and then transmits the terrain contour information to the ejection seat.

[0013] Preferably, the parachute opening contour is a step function, specifically:

[0014]

[0015] Among them, h1-h3 are the altitudes of different locations in the region, and x1-x5 are different heading distances.

[0016] The present application discloses an ejection seat parachute opening control method, which establishes a departure coordinate system for the motion trajectory of the ejection seat after leaving the aircraft, and then establishes the motion trajectory of the ejection seat after leaving the aircraft according to the departure coordinate system, and then the ejection seat obtains the terrain contour information of the current area, and determines the parachute opening contour of the current area in combination with the parachute opening height of the survival parachute. The calculation method is simple, and the parachute opening height can be adjusted in time according to the different altitudes of the landing altitude in the current area. When the landing altitude is high, the parachute opening time is earlier, and when the landing altitude is low, the parachute opening time is later, thereby effectively preventing the parachute from opening too early and causing the air to stay too long. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0018] Figure 1 This is a schematic diagram of the overall process of this application;

[0019] Figure 2 This is a schematic diagram of the intersection of the ejection seat trajectory and the parachute opening contour line for this application. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0021] An ejection seat parachute opening control method, such as Figure 1 As shown, the following steps are included:

[0022] Step S100, establishing a departure coordinate system according to the motion trajectory of the ejection seat after leaving the aircraft, establishing a data model according to the motion parameters of the ejection seat during ejection, and calculating the motion trajectory of the ejection seat after leaving the aircraft;

[0023] like Figure 2 As shown, the three coordinate axes of the off-plane coordinate system are the current aircraft heading x, the ground direction y, and the yaw direction z is determined by the right-hand rule, where the origin of the coordinates is the sea level corresponding to the current position, the aircraft position is (0, y1, 0), and y1 is the aircraft altitude. When the ejection seat is not ejected, it coincides with the position of the aircraft, which is time t = 0. The off-plane coordinate system moves with the aircraft. When the ejection seat is ejected, the off-plane coordinate system is solidified and time t starts to count.

[0024] The motion trajectory after leaving the aircraft has three direction vectors, namely heading motion x', yaw motion z' and ground motion y'. When the ejection seat does not diverge during ejection and there is no roll angle, the yaw motion can be ignored. At this time, only the heading motion trajectory and ground motion trajectory need to be calculated.

[0025] As a specific implementation, the upward movement of the ejection seat on a certain type of aircraft can be simplified as v y = 80m / s linear motion (this data is related to the seat characteristics, is test data, and is only applicable to this model of seat), the ground motion trajectory is l y =v y t.

[0026] The trajectory of the ejection seat is:

[0027]

[0028] In the formula, C dx is the ejection seat drag coefficient, s x is the frontal area of ​​the ejection seat, m is the mass of the ejection seat, P is the atmospheric pressure, ρ ∞ is the air density, v ∞ is the incoming flow velocity.

[0029] The trajectory of the earthward motion is: y =v y t, where v y =80m / s, t is time.

[0030] Therefore, the ejection seat motion trajectory F l (x, y) is a function of time t.

[0031] Step S200, obtaining the terrain contour information in the current area, and determining the parachute opening contour of the current area according to the parachute opening height of the survival parachute carried by the user;

[0032] The parachute opening contour is determined by the terrain contour and the parachute opening height. The aircraft can collect the current longitude and latitude information when flying, and interact with the ground control center through the longitude and latitude information to obtain the terrain contour information of the current area. The terrain contour information is then transmitted to the ejection seat in real time, and the parachute opening contour of the current area is determined based on the opening height of the survival parachute it carries. When the ejection seat is ejected, it stops receiving the terrain contour information of the aircraft.

[0033] After the ejection seat is ejected, its own movement speed v can be measured by the sensor x , v y , v z According to the aerodynamic formula, the current air density ρ can be calculated with the atmospheric pressure P ∞ and the altitude H.

[0034] Assume H* is the height of the local terrain contour line, r is the contour scale, h' is the life-saving parachute opening height, k is the safety factor, and h* is the parachute opening contour line, then h*=H*+r+kh'. Among them, the life-saving parachute opening height is related to the performance of the life-saving parachute itself. Different types of life-saving parachutes have different opening heights, that is, the minimum height required from the parachute shooting to the life-saving parachute being fully opened.

[0035] In the off-plane coordinate system, the time t corresponding to point Q where the ejection seat motion trajectory coincides with the parachute opening contour line is the parachute opening time.

[0036] The parachute opening contour is a step function, and the expression is as follows:

[0037]

[0038] Among them, h1-h3 are the altitudes of different locations in the region, and x1-x5 are the heading distances.

[0039] Step S300, calculating the intersection of the parachute opening contour line and the motion trajectory, and obtaining the parachute opening time after the ejection seat is ejected.

[0040] Another F h (x, y) = F l (x, y), solving the equation gives the time t0, which is the intersection of the parachute opening contour and the motion trajectory of the ejection seat. t0 is the time when the ejection seat opens the parachute after ejection. Therefore, when the ejection seat is ejected from the cabin at t=0, the parachute is opened at t=t0.

[0041] The present application establishes a departure coordinate system for the motion trajectory of the ejection seat after leaving the aircraft. After the ejection seat leaves the aircraft, the motion trajectory of the ejection seat after leaving the aircraft is established according to the departure coordinate system. The ejection seat then obtains the terrain contour information of the current area, and determines the opening contour of the current area in combination with the opening height of the survival parachute. The calculation method is simple, and the opening height can be adjusted in time according to the different altitudes of the landing altitude in the current area. When the landing altitude is high, the opening time of the parachute is earlier, and when the landing altitude is low, the opening time of the parachute is later, thereby effectively preventing the parachute from opening too early and causing a long time in the air.

[0042] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An ejection seat parachute opening control method, characterized in that: include: Establish a departure coordinate system according to the motion trajectory of the ejection seat after it leaves the aircraft, establish a data model according to the motion parameters of the ejection seat during ejection, and calculate the motion trajectory of the ejection seat after it leaves the aircraft; Obtain the terrain contour information in the current area, and determine the parachute opening contour of the current area according to the parachute opening height of the survival parachute carried by the user; Calculate the intersection of the parachute opening contour and the motion trajectory to obtain the parachute opening time after the ejection seat is ejected.

2. The ejection seat parachute opening control method according to claim 1, characterized in that: The method for establishing the off-aircraft coordinate system is as follows: the coordinate origin is set to the sea level height corresponding to the current position, the three coordinate axes of the off-aircraft coordinate system are respectively the current aircraft heading x, the ground direction y, the right-hand rule determines the yaw direction z, the aircraft position is (0, y1, 0), and y1 is the aircraft altitude.

3. The ejection seat parachute opening control method according to claim 2, characterized in that: The motion trajectory of the ejection seat after leaving the aircraft is: The heading motion trajectory of the ejection seat is: In the formula, C dx is the ejection seat drag coefficient, s x is the frontal area of ​​the ejection seat, m is the mass of the ejection seat, P is the atmospheric pressure, ρ ∞ is the air density, v ∞ is the incoming flow velocity; The ground motion trajectory of the ejection seat is: y =v y t, where v y =80m / s, t is time.

4. The ejection seat parachute opening control method according to claim 1, characterized in that: When the aircraft is flying, it collects the current longitude and latitude information, interacts with the ground control center through the longitude and latitude information, obtains the terrain contour information of the current area, and then transmits the terrain contour information to the ejection seat.

5. The ejection seat parachute opening control method according to claim 1, characterized in that: The parachute opening contour is a step function, specifically: Among them, h1-h3 are the altitudes of different locations in the current area, and x1-x5 are the heading distances.

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