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Description  |
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The invention relates to guided missile fire control simulators for use in
the training of personnel in the operation of guided missile launching and
the control of the launched missile to strike a selected target in a
simulated combat environment.
The use of simulators for the training of observers in the control of
artillery fire has been known for some time. One known system is described
in the United Kingdom Patent Specification No. 1,279,873, which describes
the use of projectors for displaying a battlescene, selected targets
superimposed thereon, and the further superimposition of an explosion
image at a point computed to be the impact point at the end of the
trajectory selected by the trainee observer.
Another known system is described in the United Kingdom Patent Application
No. 2,030,685 A, which is generally similar, although more sophisticated
computer arrangements are described and the preferred embodiment uses
television projectors.
One object of the present invention is to provide a simulator that can
reliably produce a simulation of the launch and flight of a guided missile
under the control of a trainee operator towards a selected target, and to
display the effect of the missile warhead exploding, whether as the result
of a successful strike, or the result of an abortive attempt, assuming
that the explosion is within the field of view of the operator.
The invention consists in a guided missile fire control simulator in which
a plurality of image projectors are combined in a projection system under
the control of a digital computer to display on a common screen:
a view of a selected combat area produced by a terrain image projector;
a view of a target superimposed on said terrain and produced by a target
image projector;
a representation of the appearance of a guided missile in flight, as seen
by the operator, which representation is superimposed upon the terrain
view from a missile image projector, and which is occulted whenever the
theoretical flight path takes the missile out of the view of the operator,
and which is terminated by a visual representation of the effects of the
missile warhead exploding only if the explosion or the effects thereof
would be visible to the operator;
said target image projector and said missile image projector each being
caused to project their image to respective positions on the screen by an
associated projection directing system that is controlled by said
computer;
an instructor's control station providing means for supervising an exercise
by the production of relevant control signals;
and at least one missile control station providing means for a trainee to
produce missile launch and guidance control signals;
said computer being supplied with exercise control data comprising:
stored information constituting an elevation database defining the
displayed terrain;
stored information defining the visibility of any position in the displayed
terrain to the operator and thus constituting a visibility database;
stored information concerning the missile flight characteristics and
capabilities to constitute a weapon system database; and
said computer uses said information to translate said control signals
received from an operation control unit at and after launching of a
missile into a resultant theoretical flight path for said missile and
producing signals to control said projection direction system of said
missile image projector to cause the projected image to follow the
calculated path across the displayed terrain and to terminate the missile
flight by an image projection representing the effect of explosion of the
missile warhead if within the operator's field of view, but inhibiting
such projection if theoretically outside the operator's field of view.
Advantageously, means may be provided to indicate the reason for any
failure, such as may result from the missile being guided into the ground,
or driven on a path exceeding its range capability, or being subjected to
any flight maneuver that is beyond the particular missiles capabilities.
The invention, and further advantageous features thereof will now be
described with reference to the drawings in which:
FIG. 1 is a block schematic diagram of one exemplary embodiment of the
invention;
FIG. 2 schematically illustrates details of a target image projector for
use in the embodiment shown in FIG. 1;
FIG. 3 schematically illustrates details of a missile image projector for
use in the embodiment shown in FIG. 1; and
FIG. 4 schematically illustrates details of an output-beam directing system
for use in the embodiment shown in FIG. 1.
In the embodiment illustrated in FIG. 1, a screen 1 is positioned to
display a terrain image that is projected on to the screen by a terrain
image projector 2. A projector control unit 3 provides means for selecting
any one slide from a magazine store or such slides (not shown), means for
introducing a shutter into the light path, and means for controlling the
brilliance of the projected image, all these control functions being
operated by signals from a computer 4.
The simulator also comprises a plurality of target image projectors 5, of
which only one is shown. Each of these projectors has a control unit 6
providing control means for selecting any one slide from a magazine store
of such slides (not shown), means for controlling the setting of a zoom
lens to vary the size of the image projected onto the screen 1, a shutter
control, a brilliance control and a color filter control. Automatic
focussing control means may be provided to correct the focus when the
position of the target image is changed on the screen, as this change will
result in a change in the length of the projection path. All these control
means are operated by the computer 4.
To facilitate the steering of the projected image to the desired position
on the screen at any instant, the target projectors 5 are positioned to
project their output beams in a direction away from the screen, with an
angle of tilt, and a respective plane front-surfaced mirror is positioned
in each beam path, to reflect the projected image onto the screen 1. Each
mirror forms part of an output-beam directing system 7, which will be
described in more detail with reference to FIG. 4, and each mirror
position is controlled by a respective control unit 8 that is operated by
the computer 4.
The simulator also comprises at least one missile image projector 9, and
only one is shown. This projector will be described in detail with
reference to FIG. 3. It is controlled by a control unit 10 operated by the
computer 4 to provide control of the size and brilliance of the image and
the projection of a flash-gun that is fired to simulate an explosion of a
missile warhead, when required. The projectors 9 are mounted in a similar
manner to the target image projectors 5, each having an associated
output-beam directing system 7 with a control unit 8 identical to the
means provided for steering the projected target images, as described
above.
For use by the students who are to be trained on the simulator, a number of
operators positions 11 are provided, each having a weapons system control
unit of a type appropriate for the guided missile for which operational
training is to be provided. The missile will be assumed for the sake of
example to be of the wire guided type, and the control will provide launch
and guidance facilities, and possible missile selection, as in some cases
it may be assumed that the operator has control of a number of missiles
capable of being remotely launched from a firing position separate from
the observation point. Each operator's position is provided with auxiliary
communication facilities to enable messages to be passed to or from an
instructor's post 12, and furthermore loudspeakers 13 and effects lighting
units 14 are provided to give each operator fully simulated combat stress
conditions, including enemy fire for example.
In order to provide the computer 4 with the necessary information on which
to base an exercise, a data store 15, which in this embodiment is a floppy
disc store, contains stored data giving details of the elevation of the
terrain selected for projection, point by point, considered from the
launch point, (an elevation database), together with a coded
representation of the visibility of each point in the terrain, considered
from the operators view point (a visibility database), and data defining
the performance capabilities of the weapon system concerned.
In this embodiment, there is also provision for the data store to hold
details of pre-planned maneuvers by enemy targets, which enables the
instructor to have more time for assessing the trainee operator's
performance, and possibly introducing transient commands, such as wind
gusts that may affect a missile's flight path, for example.
Furthermore, there may be provided one or more additional image projectors
similar in construction to the target image projector 5 described above,
each having an associated output-beam directing system, to project a
simulation of smoke generated as a defensive screen which drifts down-wind
and finally decays. The or each projector has its magazine containing an
assortment of smoke silhouettes, and a masking "paddle" is mounted to move
under the control of a computer program to progressively unmask the
particular smoke symbol that has been selected, the projected image being
steered by the control means from the computer, in like manner to that
described for the target projectors, but with supervision from the
instructor to vary wind-speed, the rate of decay of each smoke cloud, and
the timing of smoke generation or of the firing of smoke rounds.
Pre-planned programs can be used to simplify the instructor's task.
The store 15 may also be to record details of the exercise, including the
response of the or each operator to the problems presented. This record
can then be used to replay the exercise and enable operators to study
their own performances, and appreciate the nature and importance of any
mistakes they committed during the exercise.
In order to provide the computer 4 with access to the data stored in the
memory device 15, a central processor 16 is used in known manner. The
computer 4 then accepts commands and data from the operator's position 11,
the instructor's position 12, and the control units 8, performs the
required calculations and issues commands to the projectors 2, 5 and 9 via
their control units 3, 6 and 10, respectively, steers the projected target
and missile images by commands to the control units 8, and generates sound
effects and lighting effects to control the loudspeakers 13 and lamps 14
via a sound effect generator 17 and an enemy fire simulator 18.
The training of personnel to use such guided weapons effectively presents
numerous problems. Firstly, training using actual equipment (real rounds
with live or dummy warheads) is prohibitively expensive if sufficient
operators are to be trained and their skills maintained by practice
firing. Secondly, training is not simply a matter of learning how to
control the missile in its flight, since it may be of equal or greater
importance to teach the ability to decide which of several targets is the
correct one to engage, to distinguish between friend and foe, as in a real
battle situation both may be simultaneously visible to the missile
operator or his commander. Problems may arise in identifying the leader of
an enemy armored formation, and in estimating whether a selected target
will be able to reach cover before it can be reached by a missile launched
against it.
To provide effective simulation, an optical projector provides a view of
the terrain, in which the potential targets will appear, as seen from the
point of view of the missile operator. The view may be changed under the
control of the training instructor to present any one of a number of
different, representative terrain views; and the instructor can control
the intensity of the viewed scene at any level from full brilliance to
very dim, and change to new levels within this range, as he wishes. The
missile image projectors are of a special type whose purpose is to project
upon the screen a representation of the appearance of a guided missile in
flight as seen by the missile operator. This is typically the exhaust
flame of the missile motor, which is represented by a colored image of
roughly circular aspect whose size diminishes as the distance of the
missile from the operator increases, and it must also be capable of
projecting a representation of the effect of the missile warhead
exploding, as seen by the missile operator. Full details of various
constructions of missile image projectors will be given with reference to
FIG. 3.
A missile control station is provided for each missile image projector,
from which one or more missile operators under training can observe the
projection screen and exercise a degree of control over the picture
displayed thereon, notably with respect to the missile representation
associated with the control station concerned. For this, each missile
control station is provided with an actual missile control sight, or a
mockup thereof, on which sufficient active controls are provided for the
operator to exercise the necessary degree of control for the purpose of
the training intended.
The number of target image projectors 5 is equal to or greater than the
number of independently visible, moving targets seen on the projection
screen. For example, if six such targets may be visible at one time, then
six projectors will be actively engaged. Each projector is provided with
the means of producing the following effects upon its associated target
image:
(a) Selection from a number of image sources, typically slide
transparencies, representing different types of targets likely to be
encountered, each at one or more scaled sizes; and different aspects or
angles from which the target is viewed;
(b) Selection of the intensity at which the image is seen, from full
brilliance to zero, with a number of intermediate levels giving an
effectively continuous gradiation between the extremes;
(c) Means for occulting or displaying the projected image by the operation
of a shutter in the optical path;
(d) Selection of one color in which the projected target image is seen, to
enable representation of an active enemy target, or an alternative color
representing a target which is deemed to have been hit by a missile and
thereby "stopped";
(e) For a given image source size variation in the size of the image
observed on the projection screen by variation in the effective focal
length of the optical system of the projector ("zooming");
(f) Optional compensation for the effects upon the focus of the projected
image at the projection screen caused by changes in the effective
projection length ("throw") as the image is steered to different points on
the projection screen by the output-beam directing system concerned may be
provided in some cases;
(g) In a further optional arrangement beam modulation means may be provided
to impose a "target identity" marking capable of being automatically
recognized by detection means in given circumstances, as will be described
later.
Further identical projectors may be provided, to minimize visual
disturbance to observers of the projected images being caused by
interruption of projection when it is desired to project a different
slide, for example, when a moving target changes direction and a new
aspect is required. By this means, one of the inactive projectors can be
commanded to select the desired slide ready for projection, and the images
cross-faded.
The output-beam directing systems steer the projected beam from its
associated projector to any part of the projection screen, as commanded.
For reasons of accuracy and stability, motors of the stepping type,
controlled from a digital interface, are used. Because of their special
characteristics, it is also necessary within the optical beam deflecting
device to provide limit sensing devices to define the deflection limits
permitted to the deflection devices, datum defining devices to align the
system when first switched on or otherwise disturbed, and safety limit
switches to guard against over-run of the mechanism in the event of
failure of the limit sensing devices, as will be described with reference
to FIG. 4.
The sound effects system enables the realism of the training environment to
be enhanced by generating sounds associated with the launch of a missile,
its passage away from the missile operator and the detonation of its
warhead; the sounds typical of the movement of enemy targets; and the
sound of enemy gunfire directed at the missile operator for the purpose of
distraction and harassment. The system may also carry public address by
the instructor. Because of the difficulties involved in the precise cueing
of recordings on disc or tape, it has been found advantageous to generate
effects via the computer, using a quasi-random number generator and a
clock pulse source whose period can be varied, in order to vary the pitch
and introduce variations in amplitude and bandwidth. Such effects have
proved to be most realistic.
The simulator instructor's control station 12 will include a computer
terminal having a visual display unit and a keyboard, from which the
progress of the exercise can be controlled, and one or more target control
units, from each of which a target can be controlled in all aspects, and
which also controls enemy gunfire.
A master station may be provided, from which overall control of the
training mission may be exercised.
The training equipment is adaptable to train operators in the method of use
of a variety of guided weapons systems, the characteristics of the
invention trainer being able to be varied to represent each weapon system
as required. Thus the "mission profile" will be to some extent
missile-system dependent, but would include most or all of the following
steps:
(I) Prior to the use of the invention trainer for instructional purposes,
the training staff would cause a selected terrain view to appear upon the
projection screen, and also one or more enemy target images. By means of
the target control unit these images would be caused to move; and behave
in a manner which will present to the student the situation which the
instructor intends.
During this phase, the training equipment would be set to record all the
data being displayed upon the projection screen and all the changes as and
when they occur--that is, the terrain view selected and the intensity of
its projection, the continuously updated position of all targets, their
size, aspect, intensity, color and whether occulted or not, and the
incidence of associated sounds; also any enemy fire. The reason for this
is that, while a target or targets may readily be moved "on-line" from the
target control unit(s) during the training session proper, the training
staff may be better employed in monitoring the student; also the behavior
of the targets can be optimized to present the training situation desired
for any level of student ability. Such recorded exercise data is retained
in the computer storage medium (typically a "floppy disk" or disk pack)
and pre-recorded scenarios may be produced as desired.
(II) The student, positioned at the missile control station 11, would then
be exposed to the projected situation produced as in (I) above, and would
evaluate the simulated threat, and apply tactical criteria in deciding
which (if any) of the targets he would engage; and would inform the
instructor accordingly.
(III) The student, having decided to engage a target, would initiate the
launch of a missile using the controls available to him, appropriate to
the type of missile system being simulated. The appropriate representation
of the missile launch sound would be heard, and the missile image would
appear on the projection screen at a position and after a time delay
representative of the missile type being simulated. These factors depend
upon the characteristics of the particular missile system; in some, the
missile launcher unit and sight form a combined unit, while in others the
sight may be separated from the launcher unit by up to several tens of
meters for reasons of tactical concealment. Both types of system can be
represented in the trainer, as can those systems in which the sight is an
integral part of a vehicle. The missile operator then steers the missile
using the controls available to him as appropriate to the missile system,
in a manner to hit the target. During the run of the missile, various
hazards may cause failure to make a hit.
A computer model of the elevation of all parts of the terrain view is held
in the computer "elevation database" and the computer calculates on a
continuous basis, the position in space of the missile. If the student
steers the missile in such a way that it would hit the ground before
reaching the target, the missile image is removed from the screen and a
message is written on the visual display unit at the operator's position
stating that the missile has crashed. Another stored computer model based
on the elevation data noted above, takes into account the position and
elevation of the missile operator, and which areas of the ground are
consequently invisible to him, to form a "visibility database". If the
missile is steered into such an area, the missile image is removed from
the projection screen. If his subsequent control movements would cause the
missile to fly into view again, the image will reappear. However, the
elevation criterion also applies, as above, and the missile may be stated
to have crashed, if the simulated conditions indicate this to have
occurred while out of sight. The instructor may introduce wind effects of
varying severity and these may additionally be steady or gusting. The
missile flight path will be disturbed accordingly. The wind effects input
may be manually introduced from the computer terminal during the run of
the missile, or may be generated automatically by reference to the
elevation database (so that a cross-wind gust occurs as the missile
traverses a valley, for example).
The student may attempt to engage a target which is beyond the range of the
simulated missile system. In this event the missile will crash when it is
computed to have travelled to its maximum range, and a message will appear
on the computer terminal showing the nature of the failure.
The student's control movements may fly the missile into regions of its
flight envelope from which the real device could not recover--for example,
extremes of upward pitch. If such regions are entered (depending upon the
missile system concerned and the availability of possibly classified
information concerning the missile behavior in such circumstances) the
missile will crash and an appropriate message will be displayed at the
computer terminal. The effects of enemy gunfire aimed at the missile
operator's location, or the location of the launcher, may be introduced.
In the real world, this is a counter-measure employed by the enemy not
only to destroy the point from which missiles are controlled or launched,
but is also effective even if the enemy does not know the exact location,
as the effects of locally exploding ordnance is often sufficient to
destroy the concentration of the missile operator long enough for him to
lose control of the missile, which will therefore crash or at least miss
the intended target. Thus, the instructor may introduce at will, or
include in the scenario recorded prior to the training session, a
representation of the sound of a high-explosive shell detonating nearby,
which may also be accompanied by a representation of the flash which
accompanies the explosion.
The computer continuously calculates the position in space of the missile,
and of all targets in the exercise, whether they are being played back
from previously recorded tracks or under manual control by the
instructional staff, and visible or occulted (having passed into dead
ground for example). If the calculated missile position coordinates are
identical to those of a target, the missile has hit the target, and the
computer can use the result to initiate projection of the effects of an
explosion, assuming the calculated position is within sight of the
operator, as determined by the visibility data base.
As an optional measure to assist the computer calculations and provide
enhanced response times, the or each target projector 5 may be provided
with means to modulate its projected light beam by variation of the output
amplitude at a unique frequency above the flicker rate and any power
supply induced component. The or each missile projector 9 can then be
provided with a sensing element to supply an output signal to the computer
4 when such a frequency modulation is detected, as the two projector beams
are then coincident and it only remains to determine if the ranges
correspond. By providing a multi-segment detector the respective outputs
can be compared, and whereas equal values indicates true coincidence, any
discrepancy can be evaluated to determine the degree and direction of a
miss.
Yet another alternative arrangement can employ a single detector which is
nutated, or fed via a nutating mirror. In the absence of true coincidence
the output will then have an amplitude modulation component at the
frequency of nutation whose amplitude and phase can serve to indicate the
magnitude of a miss. In any event, true coincidence causes a red flash of
the missile warhead explosion to be seen on the projection screen 1 at the
point of coincidence of the missile and target symbols, followed by the
simulated sound of the explosion, after a time delay proportional to the
distance of the target from the missile operator. The loudness of the
sound is also reduced as the distance increases.
When the target is hit its color changes automatically to red to indicate
it has been "stopped", and target motion then normally ceases. It is an
important feature in training a person to become a proficient missile
operator that the pattern of missile behavior engendered by the control
movements made by the trainee shall be known, and undesirable trends
corrected. It is not sufficient for the trainee to try simply to achieve
the maximum number of hits on the selected target, since a `hit` may
simply be the lucky end-result of a wildly gyrating trajectory. Therefore,
provision is made in the invention trainer to record, for the latter part
of the missile's run, the percentage of the time that the missile is laid
accurately on the target. The length of the recorded run may be varied by
the instructor, but would be typically between 50 and 1000 meters,
depending on the range of the target being engaged. The computer, knowing
the coordinates of the missile and all the targets, is also programmed to
calculate the distance and direction of closest approach of a missile to
the target, so that in the event of the student failing to hit the target,
the extent and direction of the error in aim is written onto the computer
terminal screen for the information of the instructor.
The computer retains all data employed from the firing of the missile to
the end of its run (from whatever cause), and therefore the mission can be
replayed and the events viewed on the projection screen by the student and
observers for the purposes of debriefing. This replay can be at real speed
or at a slower speed, with the ability to "hold" (stop) the replay at any
point as often as required, for maximum teaching benefit. The simulator
can be made to represent any required weapon system, whether wire-guided,
radio controlled, or even if using laser or other more sophisticated
guidance systems.
The design of the target image projector 5 presents some difficulties, as
the projected image is relatively small, and a correspondingly small
transparent zone is provided on the projector slide, then there will be
excessive limitation of the light output. For this reason the arrangement
schematically shown in FIG. 2 has been adopted.
A magazine 21 loaded with a plurality, preferably eighty, different slides
is provided in each projector. The set of slides is preferably identical
in each projector, as the computer can then call up any available
projector 5, select the appropriate slide, adjust the projector controls
and steering, and cross-fade to initiate an apparent change of heading of
a target projected on the screen.
The selected slide 22 is positioned in the light beam and an image
projected by an objective lens 23 to form a focussed reduced image in a
first image plane 24, which is then projected via a multiplying converter
lens 25 and a main zoom-type lens 26. The computer effects control by
means of 6-bit commands, which are translated into appropriate control
functions by circuitry and/or transducer means.
The brilliance compound is used to trigger a semiconductor device 27a in a
current control circuit 27, the switch-on being delayed after each
zero-transit of an a.c. supply waveform by a length of time determined by
the command word, which is fed to a shift register 27b to introduce at the
most, a delay equal to the period required to enable the filament of the
lamp to be heated to stand-by temperature in the residual time of that
half-cycle. The register is fed by pulses from a clock pulse generator
whose period is phase lock looped to that of the a.c. waveform. A shutter
control 28 is of a simple two-position electro-mechanical design, and a
two-color filter slide is controlled by a color-controller 29. A slide
selector 21a must be designed to accommodate the requirements of the
particular make of the projector and the magazine 21. Image focus control
may be effected by rotation of the focus control element of the zoom lens
26, using a shaft and linkage drive 26a, and a drive 26b of greater sweep
is used for setting the zoom position. If a modulated signal is to be
imposed upon the target beam, then preferably the supply circuit is
designed accordingly, and set to impose the required frequency of
modulation although a rotating shutter could be employed.
FIG. 3 schematically shows details of the missile image projector 9. A
projector lamp unit 31 provided with a suitably colored output aperture 32
emits light via a diaphragm 33 that can be adjusted in size by a control
drive 33b to vary the apparent range of the missile image. A brilliance
control arrangement 27 similar to that described with reference to FIG. 2
may be provided. The projected light passes through a semi-silvered mirror
34 to be focussed and projected by a lens arrangement similar to the
arrangement 25, 26 of FIG. 2. In order to display the effect of a warhead
explosion an electronic flash gun 35 can be triggered from the computer by
a control circuit 35a.
The flash gun has its normal aperture covered by a mask in which there is
an appropriately shaped aperture covered by a frosted colored filter. The
different output is reflected by the mirror 34 to be projected via the
lens system onto the screen 1. If the target projectors are provided with
means for modulating their output beam, as described above, then each
missile projector is provided with a photo-sensitive detector in a
focussed image plane. Thus, a single or multi-segment detector could be
provided at the output face of the flash gun 35, to recieve light entering
from the screen and reflected by the mirror 34. Alternatively, a further
semi-silvered mirror could be provided between the projector 31 and mirror
34 to deflect light entering via the lens 26 to the detector. The detector
itself may be mounted to nutate, or the relevant mirror driven
appropriately. Sensitive filter circuits are provided to monitor for the
presence of a modulated projector-beam.
Each target image projector 5 and missile image projector 9 must have its
output beam steered to the appropriate position on the projected terrain
at any instant. To effect this control, each projector directs its beam to
an associated output-beam directing system 7 of the type schematically
illustrated in FIG. 4.
A plane, front-surfaced mirror 41 has a gimbal mount 42 which is provided
with separate geared drive means 43 for each of its axes of rotation. Each
geared drive means 43 has a rotatable drive shaft 44 driven by a
respective stepping motor 45 that is controlled by commands from the
computer via a decoding circuit 46. In this way, precise, reliable and
repeatable steering control can be insured. To avoid setting up problems,
each drive shaft 44 has an associated member 44a influencing a
photo-electric sensor 47 designed to locate a reference starting position
and optical limit stops 48. As the stepping motors apply very high torque,
electro mechanical limit switches 49 are provided as a fail-safe measure.
The essential flexibility of the invention simulation system, with regard
to its reaction time and the effectiveness of its display arises from the
division of information relating to the combat scene displayed into two
separate stores, the terrain database which holds the actual ground
heights, point by point, and the visibility database, which stores the
necessary data to allow for the effect imposed upon sight-lines by the
presence of, and effective height of such natural phenomena as shrubs and
trees, and also manmade features such as walls and buildings of all types.
The particular embodiment described employs optical projectors for terrain,
target image and missile image projection. It will be readily apparent
that television projection equipment could be used, and in this case it
might be advantageous to use electronic circuitry to cause target image
and missile image projection to be effected within the video circuits of a
common television projector. Thus, the optical output beam directing
systems of the described embodiment would be replaced by circuits gating
the appropriate signals into the television video signal.
Some missile guidance systems require the operator to aim a sight towards
the target at all times, particularly in systems having a sight combined
with a launch tube. For such systems the missile projectors may be
provided with beam modulation means such as are described above for the
target projector, but using characteristic modulating frequencies. By the
provision of a sensor in the sight of the angular position of the missile
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