KR102033125B1 - The method of prediction for trajectory of external store of a helicopter - Google Patents

Abstract

The present invention provides a first step of constructing a flight dynamics simulation model of a helicopter, and conducts a simulation of launching a projectile from a helicopter under conditions that excludes the influence of downwashing caused by the rotation of the rotor. A second step of storing a third step of interpreting the inflow by the rotor in the trajectory of the projectile and a third step of storing the projectile trajectory inflow data and a fourth step of re-launching the launch simulation of the projectile based on the projectile trajectory inflow data It relates to a projectile trajectory prediction method of a helicopter including.
The method for predicting the projectile trajectory of the helicopter according to the present invention can achieve efficiency by quickly deriving an analysis result while using less resources.

Description

Helicopter projectile trajectory prediction method {THE METHOD OF PREDICTION FOR TRAJECTORY OF EXTERNAL STORE OF A HELICOPTER}

The present invention relates to a method for predicting the projectile trajectory of a helicopter, and more particularly, to a projectile trajectory predicting method for analyzing the trajectory of the projectile in consideration of the effect of downwashing caused by the rotation of the rotor of the helicopter.

Helicopters are widely used with various types of weapons. Armed forces use projectiles, and can be divided into propellants, such as rockets or missiles, and propellants, such as warheads. In the case of a projectile that has only propulsion force, not guided like a rocket, the flight trajectory is affected by the change of external environment on the moving path. In particular, during the maneuvering of the helicopter, the attitude of the initial projectile is affected by the downwash generated from the rotor, and the actual arrival position is different from the target position.

Regarding the trajectory analysis of such a projectile, it is shown in US Pat. No. 6,186,441.

However, in the related art, in order to analyze the firing trajectory, the CFD analysis method is used to analyze all the areas around the rotor, which causes a lot of resources.

US 6,186,441 published February 13, 2001

It is an object of the present invention to provide a method for predicting a projectile trajectory of a helicopter that can solve a problem that requires a lot of resources using the CFD plane method when analyzing the trajectory of a projectile projected from a conventional helicopter.

As a means of solving the above problem, the first step of constructing a flight dynamics simulation model of the helicopter, performing a launch simulation in which the projectile is launched from the helicopter under the condition that the influence of the downwash caused by the rotation of the rotor is excluded; A second step of storing the trajectory data of the third step of analyzing the inflow by the rotor in the trajectory of the projectile, and a third step of storing the projectile trajectory inflow data, and performing a re-launch simulation of the projectile based on the projectile trajectory inflow data. A projectile trajectory prediction method of a helicopter including four steps may be provided.

Here, the method may further include a fifth step of determining whether or not the collision with the helicopter by analyzing the trajectory data of the projectile derived after the fourth step.

And, the analysis of the rotor inflow of the third stage can be performed using the 6DOF flight mechanics analysis technique.

On the other hand, the projectile may be a non-guided rocket.

In addition, the fifth step may determine whether or not collide with the rotor by nose-up pitch maneuver by the trajectory inflow during launch of the rocket.

On the other hand, the third step may analyze the inflow flow according to the helicopter hovering (hovering) and the helicopter ascending speed within a predetermined range.

In addition, the third step may analyze the inflow according to the side and rear maneuver of the helicopter.

The method for predicting the projectile trajectory of the helicopter according to the present invention can achieve efficiency by quickly deriving an analysis result while using less resources.

1 is a conceptual diagram showing the trajectory of a projectile launched from a helicopter.
2 is a view showing the projectile and the center of gravity.
3 is a view showing the trajectory of the projectile and its posture in consideration of downwash.
4 is a flowchart of a method for predicting a projectile trajectory of a helicopter according to a first embodiment of the present invention.
5 is a graph showing the trajectory of the rocket obtained by the rocket launch simulation.
6 is a diagram illustrating six degrees of freedom applied to a helicopter.
7 is a downflow graph obtained through flow analysis around a helicopter.
8 is a graph showing the trajectory of the rocket analyzed by reflecting downwash.
9 is a graph showing the trajectory of the rocket in consideration of the influence of the inflow which occurs during the ascending start of the helicopter.

Hereinafter, a method for predicting a projectile trajectory of a helicopter according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. And the names of each component in the description of the following embodiments may be called other names in the art. However, if their functional similarity and identity, even if the modified embodiment can be seen as an equivalent configuration. In addition, the symbols added to each component is described for convenience of description. However, the contents shown in the drawings in which these symbols are described do not limit each component to the ranges in the drawings. Similarly, even if an embodiment in which the configuration on the drawings is partially modified is employed, it can be regarded as an equivalent configuration if there is functional similarity and identity. In addition, in view of the general level of those skilled in the art, if it is recognized as a component to be included naturally, the description thereof will be omitted.

1 is a conceptual diagram showing the trajectory of the projectile projected from the helicopter (1). As shown in the figure, the trajectory emitted by the helicopter 1 is different from the path after the launch. The arrival position at which the rocket 2 arrives may vary according to the path, and the initial launch condition is adjusted to reflect the external influence so that the rocket 2 arrives at the correct target position. At this time, the collision with the helicopter 1 after the armed shot should be prevented, and in particular, the collision with the rotor should be prevented. To prevent collision with the rotor, it is possible to predict the trajectory of the rocket 2 reflecting the influence of inflow (downwash) generated from the rotor and to prevent the rocket 2 from firing in a flying environment where there is a risk of collision. have.

2 shows the projectile and the center of gravity 3. As shown, the projectile may be an unguided rocket 2. US guided rocket (2) is not provided with a separate guidance function means a rocket (2) that is launched by generating a propulsion force. The U-guided rocket 2 is configured to fire with propulsion in the initial firing direction. However, as shown, the center of gravity 3 of the rocket 2 is directed toward the front end of the rocket 2 so that the posture may be changed by an external force applied from the outside. 2) the posture change occurs, and in particular, the posture change occurs because the rotation is made based on the center of gravity (3) of the rocket (2).

3 is a view showing the trajectory and the posture of the projectile considering the downwash.

As shown, the rocket 2 is subjected to an external force by the inflow of the rotor immediately after launching, and an upward pitch movement occurs. This is due to the fact that the center of gravity (3) of the rocket (2) is located in the first half side as described in Figure 2 because more rotation moment occurs in the lower half relative to the center of gravity (3) by the wake. In this case, when excessive pitch movement occurs upward, the rocket 2 may collide with the blade of the rotor.

The collision of the rocket 2 and the helicopter 1 may be affected by the maneuver of the helicopter 1 as well as the launch angle of the rocket 2. Specifically, hovering (hovering), ascending start, descending start, etc. are also affected. In particular, during the starting up, a larger inflow occurs than during the hovering, so that the pitch movement of the rocket 2 becomes large.

4 is a flowchart of a method for predicting a projectile trajectory of the helicopter 1 according to the first embodiment of the present invention, FIG. 5 is a graph showing the trajectory of the rocket obtained by the rocket launch simulation, and FIG. 6 is applied to the helicopter 1. 7 is a graph showing six degrees of freedom, and FIG. 7 is a graph of an inflow (4) obtained through the flow analysis around the helicopter (1), and FIG. 8 is a trajectory of the rocket analyzed by reflecting the inflow (downwash) (4). Is a graph.

As shown, the method of predicting the projectile trajectory of the helicopter 1 according to the present invention comprises the first step (S100) of constructing a flight dynamics simulation model of the helicopter 1 and the influence of the inflow of the rotor 4 (downwash). The second step (S200) of analyzing and storing the trajectory of the projectile under the condition of displacing the third step (S200), the third step of analyzing the inflow (4) by the rotor in the trajectory of the projectile and storing the projectile trajectory inflow (4) data ( S300), a fourth step S400 of re-launching the launch vehicle based on the projectile trajectory inflow 4 data, and a fifth step S500 of determining whether or not the collision with the helicopter 1 is performed.

The first step (S100) of constructing a flight dynamics simulation model of the helicopter 1 is a step of constructing a flight dynamics simulation model of the helicopter 1 in an operational area (OFE: Operational Flight Envelop) of the helicopter 1. In this step, the model is constructed in consideration of the flow generated by the rotor and the flow caused by the interference effect of the fuselage, and a simulation model according to the maneuver is constructed. In detail, the simulation model according to the maneuver is constructed with a flight dynamics model based on hovering, side maneuvering and rear maneuvering. In addition, a model is constructed according to the rising and falling start, and a simulation model is constructed in the low speed region and the high speed region. For example, the helicopter (1) aerodynamic model may be a UH-60A model, and the ARTICULATED rotor shape including flap and lead-lag degrees of freedom may be modeled using feather element theory using FLIGHTLAB. The inflow 4 model can be a PETTER HE FINITE STATE model. The tail rocker can be modeled with a BAILEY rotor. The aerodynamic model for the aircraft can be used as a wind tunnel test database for the fuselage model and the SCALE MODEL with horizontal and vertical stabilizers mounted on the fuselage. Modeling of the rocket may use the M261 / MK66 Hydra70 rocket. The warhead weighs 13.5 lb, the gross weight is 19,93 lbs, and can be 66.1 inches long. Data such as aerodynamic coefficient for analysis can use the established database. Although not described, the flight dynamics simulation model of the helicopter 1 may include models in various flight zones.

The second step (S200) of analyzing and storing the trajectory of the projectile under conditions in which the influence of the downflow of the rotor has been removed is performed in the flight area in which the helicopter 1 is operated. Interpreting and storing data. The projectile may be a rocket as described above, and the results according to different specifications may be derived for each rocket. Here, the trajectory 5 of the projectile is simulated by assuming that there is no wake when the rocket is launched. The result is shown in FIG. 5, after the launch, the parabolic trajectory appears due to the action of rocket propulsion and gravity. Various trajectory data can be interpreted according to the specifications of each rocket and data of the flight area, and the analyzed data is stored.

The third step (S300) of analyzing the inflow (4) by the rotor in the trajectory of the projectile and storing the projectile trajectory inflow (4) data is an inflow into the region where the trajectory of the projectile is made, not the entire area of the helicopter (1). Corresponds to step (4) in the analysis. In this step, the rotor inflow (4) is analyzed along the trajectory of the rocket derived in the second step (S200) instead of the entire area around the helicopter (1). Unlike CFD (Computational Fluid Dynamics) analysis, which analyzes the flow of the entire area around the helicopter (1), only the area corresponding to the trajectory of a specific rocket is analyzed.

6, the concept of six degrees of freedom of the helicopter 1 is shown. In this step, the inflow (4) of the rotor for the area corresponding to the rocket trajectory is analyzed using the Six Degree of Freedom flight dynamics analysis technique. The six degree of freedom flight mechanics analysis technique is a technique to interpret the motion of an aircraft by expressing six movement factors. The six moving elements are the linear movement in the x-axis direction, the linear movement in the y-axis direction, the linear movement in the z-axis direction, the roll movement in the x-axis direction, and the y-axis center. The pitch and the yaw around the z axis.

Helicopter (1) 6 The degrees of freedom aerodynamic model uses the forces and moments acting on each element of the helicopter (1 main rotor, tail rotor, horizontal safety plate, vertical safety plate and fuselage) to solve the equations of the aircraft's motion equation. It calculates the six motion factors that act on the aircraft.

The inflow (4) of the helicopter (1) is the modeling factor that has the greatest influence on the aerodynamic analysis of the helicopter (1), and the dynamic inflow (4) model is the corresponding inflow (4) state variable. It can be expressed as a first-order relation for and is used for flight mechanics analysis such as simulation. The Vortex wake model can use the vortex element to predict the inflow (4) state occurring in the rotor disk. However, the vortex wake up model is an example, and various models may be applied to the inflow (4) model.

7 is a graph of the inflow 4 obtained through flow analysis around the helicopter 1. As shown, an analysis graph is shown according to the number of state variables (3, 6, 15) for inflow derivation of the dynamic inflow model, and as the number of state variables increases, Predictions are made. On the other hand, in the case of the vortex wake model, a roll-up vortex is formed at the blade tip.

Projection trajectory The fourth step (S400) of re-launching the launching of the projectile based on the inflow (4) data corresponds to the step of analyzing the trajectory of the projectile by applying it to the projectile based on the inflow (4) data. FIG. 8 is a graph showing the trajectory 6 of the rocket analyzed by reflecting the inflow 4 (downwash). As shown in FIG. 8, the effect of the rocket trajectory due to the pitch effect of the rocket after the rocket is launched is shown. Is shown. Differences in flight distance according to the model of the rocket show a slight difference, and the analysis results between the models do not have much error. However, considering the influence of the flow, the rocket launched at an altitude of 300m has a difference of 561m at the point of arrival.

In addition, as another example of analyzing the trajectory of the rocket with different flight conditions, a graph showing the trajectory of the rocket and the distance between the rotor considering the influence of the inflow flow 4 generated during the ascending start of the helicopter 1 is shown in FIG. 9. Is shown. As shown, the flight conditions are shown the result that the different pitches are generated due to the influence of the inflow (4) of the rotor during the ascending start to change the trajectory. The faster the ascending speed of the helicopter 1, the stronger rotor inflow 4 is generated, resulting in greater pitch movement. As shown in the drawing, when the ascending speed is 2800ft / min, the distance to the rocket is less than 50cm near 7.5m from the rotor head, resulting in the risk of collision.

The fifth step (S500) of determining whether or not the collision with the helicopter (1) is determined in consideration of the trajectory of the analyzed rocket and the maneuver of the helicopter (1) to determine whether the collision, and stores the data on the flight conditions of the risk of collision Done. The risk of collision may be determined to be a risk of collision if the rocket's trajectory is within a certain distance from the helicopter.

As described above, the projectile trajectory prediction method of the helicopter 1 according to the present invention analyzes the influence of the inflow of the rotor 4 on the trajectory region of the rocket by using a six degree of freedom flight dynamics analysis method. As a result, the analysis results can be quickly obtained while using less resources, thereby improving efficiency.

1: helicopter
2: rocket
3: center of gravity
4: inflow
5: Trajectory of rockets without the influence of inflows
6: Trajectory of the Rocket Reflects Influence
S100: First step to build a flight dynamics simulation model of the helicopter
S200: a second step of analyzing and storing the trajectory of the projectile under conditions in which the influence of the rotor downwash is removed
S300: a third step of analyzing the inflow by the rotor in the trajectory of the projectile and storing the projectile trajectory inflow data
S400: a fourth step of re-executing the launch simulation of the projectile based on the projectile trajectory inflow data
S500: fifth step of determining whether the collision with the helicopter

Claims (7)

A first step of building a flight dynamics simulation model of the helicopter;
A second step of performing a launch simulation in which a projectile is launched from the helicopter and storing trajectory data of the projectile under the condition that the effect of the downwash generated by the rotation of the rotor is excluded;
A third step of analyzing the inflow by the rotor in the trajectory of the projectile and storing the projectile trajectory inflow data;
Re-launching the firing simulation of the projectile based on the projectile trajectory inflow data; And
And a fifth step of determining whether or not the vehicle collides with the helicopter by analyzing trajectory data of the projectile derived after the fourth step. delete According to claim 1,
The rotor inflow analysis of the third step is a helicopter projectile trajectory prediction method, characterized in that it is carried out using a six degree of freedom flight dynamics analysis technique. The method of claim 3, wherein
The projectile is a helicopter launch vehicle trajectory prediction method, characterized in that the non-guided rocket. The method of claim 4, wherein
The fifth step of the helicopter launch vehicle trajectory prediction method, characterized in that for determining whether or not the collision with the rotor by nose-up pitch maneuver by the trajectory inflow flow. The method of claim 5,
The third step is a helicopter projectile trajectory prediction method, characterized in that for analyzing the inflow of the helicopter according to the hovering (hovering) and the ascending speed of the helicopter within a predetermined range. The method of claim 6,
The third step of the helicopter projectile trajectory prediction method, characterized in that for analyzing the inflow flow according to the side and rear maneuver of the helicopter.

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