FR2701103A1 - Method for launching and controlling, from a mobile vehicle, a projectile not guided vertically and with a braked trajectory. - Google Patents

Abstract

Proposed launch on a target (4), from a mobile vehicle (1), a projectile (2) not guided vertically, with a mixed trajectory (25), free, of adjustable duration, then braked, in which , before launch, and for various positions of the vehicle (1), - the target (4) is identified, - the distance from the target (4) to an anticipated virtual trajectory of maximum range (6) of the projectile (2) is calculated and - the projectile (2) will be launched after said distance has crossed a minimum, and then, in the calculation, the maximum range trajectory (6) is replaced by a mixed trajectory (25) whose travel time is slaved ( TB1) of the free trajectory (26) so that the distance from the target (4) to the trajectory of the projectile (25) remains equal to this minimum and the projectile (2) is sent a trajectory duration signal free (26).

Description

Launch and control method, from a mobile vehicle,

  a projectile unguided vertically and with a braked trajectory.

  The present invention relates, first of all, to a method for launching and controlling a target, from a mobile vehicle, of at least one vertically ungated projectile, with a mixed trajectory, with a free portion, of adjustable duration. and then with a braked portion, in which, in a first approach phase before launching, and for each of various successive positions of the vehicle, 1 the position of the target is determined in a three-dimensional coordinate system linked to the vehicle, 2 the said duration is fixed adjustable to a maximum value, it calculates, taking into account the speed of the vehicle and in said mark, the anticipated virtual trajectory of the projectile, maximum range, 3 is calculated the distance from the target to said virtual trajectory and launching the projectile after said distance has passed a minimum. To launch, from a mobile vehicle, for example an aircraft, a projectile not guided vertically, such as a bomb or a rocket, the pilot gives the aircraft an appropriate drop angle so that the target is on the ground. trajectory of the projectile In the case of the airplane, this angle is determined by the trajectory of the latter, whereas, in the case of another vehicle, on land or sea, it may, in the case of for example

  rockets, be adjusted by pivoting the launch device.

  The free trajectory portion is followed by a braked portion of the trajectory, a parachute then braking the bomb to improve the angle of impact on the ground, so that it explodes and, if possible, reaches the target under a impact angle sufficient for

ensure the desired effectiveness.

  There was the problem of precisely

  the bomb and in particular the angle, or slope, and the moment

  launch, otherwise the bomb fell "short" or exceeded the target.

  Moreover, if the aircraft must, in a single attack pass, send on the target several bombs, it can not launch them simultaneously because there would be a risk of collision between these bombs. To avoid this risk, the drops are made successively, leaving between them a safety time interval Each bomb then had a clean trajectory, so, in general, incorrect The problem of adjusting the trajectory to obtain a group shot also arose when the bombs

  had different masses or ballistic characteristics.

  Therefore, it was necessary to "water" an entire area with a larger number of bombs and the aircraft eventually carried out

  several passes, with the risks that entailed.

  On the other hand, when the target extends over a large area, such as an airstrip, more bombs are needed to cause sufficient damage. The problem then was to perform a concentration shot with a homogeneous distribution. the points of impact, so as not to waste projectiles. Both of the above problems, cluster firing or concentration firing, are related to the fundamental problem of setting the range of bombs in the vertical plane of their trajectory. The present invention aims to solve the problem of adjustment

of scope.

  For this purpose, it relates to a method of the type mentioned above, characterized in that: in a second approach phase, the position of the target is determined, said adjustable duration is fixed, an expected virtual trajectory of the target is calculated, projectile as in the first approach phase, but replacing, in the calculation, after crossing the said minimum, the maximum range trajectory by a mixed trajectory whose ensuing travel time of the free trajectory portion by the minimum of said distance from the target so that, for each of the various positions of the vehicle during this second approach phase, the distance from the target to the trajectory of the projectile is equal to this minimum and, before the expiry of said travel time projectile, transmits to the projectile a free trajectory portion of travel path signal. Thus, whatever the launch conditions of the projectile, it is braked at the right time so that its

trajectory reaches the target.

  It will be noted that the relative position of the target, when it is mobile, can be predictive and one can take account of its expected displacement during the free flight time of the projectile. Advantageously, the ground impact angle of the trajectory of the projectile during the first phase as well as during the second approach phase is calculated and the launch is prohibited until a projectile trajectory presents, with the horizontal,

  an angle of impact greater than a determined value.

  In this case, the braking trajectory portion did not always have the necessary duration for the bomb to have the best efficiency, with an effect in a sector completely surrounding its

point of impact.

  The problem of the effectiveness of the projectile is thus solved since the projectile, not only reaches the target, but hits it, if it presents a horizontal surface, at an angle

  sufficient impact to ensure the effectiveness of its action.

  In addition, it is possible to make a group shot of projectiles launched successively to the same point of a quasi-point target, or projectiles masses or characteristics

  different aerodynamics, possibly launched simultaneously.

  We proceed then for all the other projectiles as for the

first launched.

  When several projectiles are to be launched in a firing said concentration, respectively on several points of a target, is assigned to the projectiles respectively several points of impact on the target and is transmitted to each projectile a portion of free trajectory portion of the position of the point

the corresponding impact.

  This provides the desired distribution of impact points.

  The invention also relates to a method of guidance after launch according to the launch method of the invention, wherein, the projectile comprising a data receiver arranged to cooperate, after launching, with a transmitter of the vehicle, is continued, after launching , calculating a virtual trajectory of the projectile coinciding with its real trajectory and transmitting to the projectile the corresponding signals of travel time of the

portion of free trajectory.

  The invention will be better understood from the description

  following of the preferred embodiment of the method of the invention, with reference to the accompanying drawing, in which: Figure 1 shows a plane and the planned trajectories of bombs and Figure 2 is a block diagram illustrating the method of the invention; 'invention. An airplane 1 carries, in this example, two bombs 2 and 3, here

  similar, which must reach a target 4, here on a ground 5.

  On board the aircraft 1, a viewfinder 11 provides a signal 19 to acquire the relative position of the target 4 relative to the aircraft 1 In this example, the viewfinder 11 has a sighting optics steerable associated with a computer (not shown) The angle of view of the optics relative to a ground stabilized mark and indications of position of the aircraft 1 in this frame, from a set 12 central aircraft inertial-calculator 1, are provided to the viewfinder 11 to generate the signal 19 It will be understood that a precise navigation device could as well provide the position of

  target 4 without having to see it.

  There is also on board the aircraft 1, a computer 13 receiving, from the assembly 12, in which it is here included, the position indications of the aircraft 1 and the signal 19 of

position of the target 4.

  The computer 13, having in memory the characteristics of the bombs 2 and 3 necessary for the calculation of their trajectories after release, such as mass, coefficient Cx of aerodynamics, proceeds cyclically a trajectory calculation algorithm providing the maximum range of the bombs 2 and 3 , given their velocity vector and its angle on the horizontal as well as attitude and

  airplane altitude 1 relative to the horizontal plane of the target 4.

  The bombs 2 and 3 comprise a braking device, here a parachute, the activation of which is delayed with respect to the moment of release. The delay TB 1, TB 2 of activation of the parachute is adjustable, so that the bombs 2 and 3 have a mixed trajectory formed of a portion of free trajectory, or smooth phase, not voluntarily braked, of duration, therefore length, controlled, followed,

  if the order is given, a braked portion of the trajectory.

  The computer 13 is individually connected to each bomb 2, 3 by a data link 14, 15 In this example, it is expected that the link is maintained after the drop, so that to achieve these links 14, 15, the calculator 13 is associated with two radio transmitters respectively transmitting to two radio receivers placed in the bombs 2, 3 It will be understood that unwinding cable connections could be provided, the influence of the braking due to the cables then being taken into account for the calculation of the path

bombs 2, 3.

  The computer 13 can also calculate the horizontal range of a bomb 2, 3 under the position and speed conditions of the aircraft 1 indicated, depending on the duration of travel of the

portion of free trajectory.

  The dropping of the bombs 2, 3 is carried out by implementing the

process below.

  In a first approach phase before launch, and for each of various successive positions of the aircraft 1, the target 4 being located by means of the viewfinder 11, the computer 13 cyclically calculates a free trajectory portion 6 of the bombs 2, 3 corresponding to the maximum horizontal reach P which can be

  obtained, taking into account the conditions of release.

  When the horizontal distance from the target 4 to the aircraft 1 becomes equal to the maximum delivery range P, the computer 13 provides the pilot of the aircraft 1 a first firing solution signal. In a second approach phase, in order to maintain the target 4 on the trajectory of the bomb 2 as the aircraft 1 moves, the position of the target 4 is determined as before and the computer 13 sets the adjustable duration TB 1 by calculating an anticipated virtual trajectory of the bomb 2 as in the first approach phase, but replacing, in the calculation, after crossing the minimum above, the maximum range trajectory 6 by a mixed trajectory 20 of which it enslaved the travel time TB 1 of the free trajectory portion 21 by the minimum distance of the target 4 so that for each of the various positions of the aircraft 1 during this second approach phase, the distance of the target 4 to the trajectory 20 of the bomb 2 is equal to this minimum and, before the expiry of said travel time TB 1, it transmits to the bomb 2 a travel time signal TB 1 free trajectory portion 21 will understand that, if he was not planned to maintain data links, such as 14, 15, between the computer 13 and the bombs 2, 3, the signal

  duration TB 1 should be transmitted before the release.

  In this example, the first firing solution signal does not allow the launch, because there is an additional condition, which is that the trajectory of the bomb 2, 3 makes, on impact, an angle A, on the horizontal, which reaches a threshold value AO, here 82 degrees This trajectory can, in practice, be a free trajectory portion, such as 6, if the corresponding apogee is sufficiently high for the trajectory of the bomb 2, 3 sufficiently close to the vertical, or it can be a mixed trajectory, which requires a lower height of apogee since the trajectory presents a

  transition bringing it back faster to the vertical.

  To satisfy this condition on the angle of impact A of the trajectories of the bombs 2, 3 at their intersection with the horizontal plane of the target 4, the computer 13 provides, as explained below, a second firing solution signal, allowing the release, when the angle of impact A reaches the value AO As the aircraft 1 approaches the target 4, here without losing altitude, the length of the free trajectory portion decreases and that of the

  slowed trajectory portion, starting from higher, increases

  This results in an increase in the angle of impact A. It will be noted that, if the target 4 is masked by a relief, of known horizontal position and height, it is possible to introduce the additional condition that it is guaranteed. that the mixed trajectory is airborne to target 4, i.e.

  height of apogee sufficient to ensure an overflight of this relief.

  This can also be the case when the trajectory of the bombs 2, 3 must remain above a volume of air space in which

  Countermeasures may be applied to the bomb 2, 3.

  The calculator 13 then compares the mixed trajectory 20 with the coordinates, in horizontal position and altitude, of the relief concerned and authorizes a bomb launch 2, 3 only when the mixed trajectory 20 is located above the relief. The latter is also considered as a target which, in this case, must always be avoided and exceeded by the mixed trajectory 20, that is to say that the launch takes place only after crossing the mixed trajectory by the top of the relief, after that the distance between the mixed trajectory 20 and the top of the relief has passed through a

minimum.

  The pilot then drops the bomb 2 at a time T1, at a point 7 of the trajectory 8 of the aircraft 1, represented by a dashed line Here, instead of storing in the bomb 2, before its release, the delay, relative to the moment Tl of release, of activation of the parachute calculated at the moment of the release, the computer 13 continues the calculation of this delay The bomb 2 follows, for a duration of course equal to the delay TB 1 above, a trajectory 20 formed of a free trajectory portion 21 which will be followed, at a time Tl + TB 1, of a braked trajectory portion 22 When the corresponding duration has elapsed, the computer 13 sends to the bomb 2 a signal brake control signal This braking command signal, transmitted after launch, which, as indicated, could have been replaced by another brake control signal stored in the bomb 2 before launch, makes it possible to take into account a movement of the target 4 that would have been unforeseen During the launch, it is indeed possible with the computer 13 to extrapolate the movements of the target 4, but this is only statistical and therefore can not take into account an avoidance maneuver performed by the target 4 as a function of the threat detected The order to open the parachute of the bomb 2 is memorized and commands the opening of the parachute

  when the time TB 1 has elapsed since the drop.

  The bomb 3 is then released at a point 9 of the trajectory 8, at a time T 2, and, as the aircraft 1 has approached the target 4 since the previous release, the computer 13 controls, with a delay TB 2 less than for the bomb 2 (TB 1), the opening of the bomb parachute 3 The bomb 3 follows a trajectory 25 formed of a portion of free trajectory 26 followed by a braked trajectory portion 27 A trajectory of the bomb 3, for which the duration of travel of the free trajectory portion would be equal to that (21) of the bomb 2, is represented by a dashed line which exceeds the target 4 by a horizontal distance D. The difference ΔTb the travel times of the free paths of the bombs 2 and 3 are proportional to the duration i Tl = T 2 Tl separating the two drops However, the conditions of release could have varied from one bomb 2, 3 to the other and the bombs 2, 3 being slightly slowed by the air on their portion of trajectory

  free, the following corrective terms are introduced.

  The distance D between ground impacts 5, assumed to be horizontal, of the bombs 2 and 3 in the absence of correction of the parachute opening delay is equal to the difference c Tl between the delivery instants multiplied by the horizontal velocity Vi J the intersection point of the trajectory of one of the bombs 2, 3 with the ground 5, calculated in a known manner by the computer 13 The range correction on the bomb 3, that is to say the value of the distance Between impacts, is equal to the horizontal velocity l Vbj of the bomb 3 at the end of the free trajectory portion 26, shorter in this example than the free trajectory portion 21, multiplied by the duration of the anticipation of the control signal corresponding braking

the bomb 3.

  This anticipation is equal to the delay TB 1 of the brake control signal of the bomb 2, with respect to its moment of release Tl, minus the delay TB 2, here reduced, of the brake control signal of the bomb 3 with respect to its moment of release T 2 So we have:

ûTb = O Tl | Vi | / I Vbl.

  We will notice that the horizontal velocity | Vi | the ground impact point 5 is a phase velocity, that is to say corresponds to the displacement of a virtual trajectory which is the end of the braked trajectory portion It can therefore take values independent of the speed horizontal plane 1, especially larger if the aircraft 1 performs a resource brutally increasing the range of bombs 2, 3, so that

  the precise determination of IL is therefore of great importance.

  An observation, by observation, of the free trajectory portion of the bomb 2, 3 and a brake control signal transmitted after the release, taking into account the observed trajectory of the bomb 2, 3,

  allow to further improve the accuracy of the bombing.

  Conversely, the aircraft 1 can maneuver so that the speed

  horizontal phase | Vi | low between the drops, that is

  that is to say that the quasi parabolas of the two free paths pass substantially through the target 4, which, in this particular case, makes the accuracy of bombardment little dependent on the difference

  between the delays of the brake control signals.

  It will also be noted that, contrary to this example, the braking delay of the bomb 3 could be greater than that of the bomb 2 if the aircraft 1, although approaching the target 4, performed a maneuver decreasing the range P In the case where, contrary to the firing grouped above, it would be necessary to distribute homogeneously, in firing concentration, the points of impact on an extended surface of target 4, it will be understood that the above process is applicable in providing, unlike braking delay between bombs, an offset correction, positive or negative, calculated according to the same principle

  and shifting the points of impact to the ground 5.

  The bombs are then assigned several points of impact on the target 4 and each bomb is transmitted a portion of free trajectory portion TB 1, TB 2 depending on the position of the

corresponding impact point.

  In this example, the computer 13 provides a launch prohibition signal when the travel time of the free trajectory portion is reduced to a determined threshold value preventing any range correction. This value, in case it is different from zero, allows the aircraft to avoid parachutes It may depend on the flight conditions of the aircraft 1, that is to say the speed at which it will deviate, after

  launch, the trajectory of the bombs 2, 3.

  It will be understood that a free path portion length as well as the corresponding travel time can be set. he

Claims (5)

  1 Method for launching and controlling a target (4), from a mobile vehicle (1), of at least one projectile (2, 3) unguided vertically, with a trajectory (25) mixed, with a free portion , of adjustable duration, then with a braked portion, in which, in a first approach phase before launch, and for each of various successive positions of the vehicle (1), 1 the position of the target (4) is determined in a reference three-dimensional linked to the vehicle (1), 2 said adjustable duration is fixed at a maximum value, it is calculated, taking into account the speed of the vehicle (1) and in said reference, the anticipated virtual trajectory (6) of the projectile (2, 3), of maximum range, 3 the distance of the target (4) from the virtual trajectory (6) is calculated and the projectile (2, 3) is launched after the said distance has passed a minimum, characterized in that in a second approach phase, we determine the position of the target (4), we set the ladit e adjustable duration (TB 1, TB 2), it calculates an anticipated virtual trajectory of the projectile (2, 3) as in the first approach phase, but replacing, in the calculation, after crossing said minimum, the trajectory of maximum range (6) by a mixed trajectory (25) whose travel time (TB 1, TB 2) of the free trajectory portion (26) is enslaved by the minimum of said distance from the target (4) so that, for each of the various positions of the vehicle (1) during this second approach phase, the distance from the target (4) to the trajectory of the projectile (25) is equal to this minimum and, before the expiry of said duration of course (TB 1, TB 2), the projectile (2, 3) is transmitted with a duration signal of portion of free path (26).   2 Method according to claim 1, wherein the angle of impact (A) is calculated on the ground of the trajectory of the projectile (2, 3) during the first phase (6) as well as during the second approach phase (25) and prohibiting the launching until a projectile trajectory (25) has, with the horizontal, an angle of impact (A) greater than a determined value (AO).   The method according to one of claims 1 and 2, wherein   several projectiles (2, 3) are launched by assigning them respectively several impact points (4) on the target and transmitting to each projectile (2, 3) a free trajectory portion portion (TB 1, TB 2) function the position of the point corresponding impact (4).   The method according to one of claims 1 to 3, wherein   said travel time (TB 1, TB 2) is compared with a threshold value and a projectile launch prohibition signal (2, 3) is generated when it is lower than said threshold value. Guiding method after launch according to the method of one   claims 1 to 4, wherein to prevent the passage of the   projectile (2, 3) in a space to be avoided, the position of the space is determined, the distance between a vertex of one space and the mixed trajectory (25) is calculated and the projectile is not launched (2, 3) only after said distance passed through a minimum.   6 Guiding method after launch according to the method of one   Claims 1 to 5, wherein the projectile (2, 3)   comprising a data receiver arranged to cooperate, after launching, with a transmitter of the vehicle (1), the calculation of a virtual trajectory (6; 25) of the projectile (2, 3) coinciding with its execution is continued after launching; trajectory and the projectile (2, 3) is transmitted with the corresponding duration signals   of course of the free trajectory portion (26).