Source: http://www.docstoc.com/docs/42510791/Emissive-Decoys---Patent-4069762
Timestamp: 2015-08-02 17:43:17
Document Index: 475726128

Matched Legal Cases: ['art 34', 'art 38', 'art 34', 'art 38', 'art 34', 'art 38']

Emissive Decoys - Patent 4069762 by Patents-307
42510791
The present invention relates to protection means able to be used in anattempt to protect a vehicle, such as a surface ship from the threat constituted by a missile or similar self-propelled offensive device, provided with an infra-red guidance system.For the purpose of protecting a vehicle from an infra-red guided missile, the prior art already proposes placing at a certain point in space, one or more possible movable decoys, having infra-red radiation and able to be substituted for thevehicle in the guidance system of the missile.Protection means of this type remain effective in the case where the vehicle to be protected is an aircraft. In fact, the source of infra-red radiation of the aircraft is constituted essentially by the hot part of its propulsion means. The hightemperature prevailing in this part establishes for the target constituted by this aircraft, an infra-red source whose brightness spectrum comprises a dominant factor in the near infra-red (wave length of the order of 4.mu.). Furthermore, the dimensionsof the source remain relatively small. Due to this, it is easy to re-constitute an artificial target representing a brightness spectrum very close to that of the actual target constituted by the aircraft, by means of an appropriate pyrotechniccomposition. In addition, the considerable speed of the aircraft enables it to move away rapidly from the positioned decoy or decoys in order that the explosion of the missile in the vicinity of the latter no longer constitutes any danger.On the other hand, in the case where the vehicle to be protected is a surface ship, the above-described solution remains only slightly effective. In fact, the ship constitutes a target of considerable size, the temperature of which remainsrelatively low, approximately 15.degree. C greater than the temperature of the bottom of the sea. The result of this low temperature gradient is that the brightness spectrum of the ship has a dominant factor in the far infra-red (wave l
4,069,762
102/37.6&#226;&#168;102/37.6
3,762,327 10/1973 Murray et al
3,841,219 10/1974 Schillreff
712,385 6/1965 Canada
[54]	EMISSIVE DECOYS
[75]	Inventor: Louis Maury, Toulouse, France
[73]	Assignee: Societe E. Lacroix, Muret, France
[21]	Appl. No.: 652,348
Primary Examiner&#226;Verlin R. Pendegrass&#226;&#168;Attorney, Agent, or Firm&#226;Pollock, Vande Sande &amp;
Jan. 26, 1976&#226;&#168;Foreign Application Priority Data
Jan. 29, 1975 France
[51]	IntCU
75 02725
102/90; 102/37.8
102/6, 37.6, 37.8, 65,
102/66, 90
An elementary emissive decoy for protecting, say, a&#226;&#168;ship from an infra-red guided missile has a water-tight&#226;&#168;case provided with floats and in which there is a liquid&#226;&#168;aerosol, a high calorific pyrotechnic composition core&#226;&#168;and an ignition device for the core. A plurality of de&#194;&#172;&#226;&#168;coys are launched from the ship one after another to&#226;&#168;create an artificial moving target.
1,819,106 8/1931 McBrideetal
2,119,697 6/1938 Anderson
3,427,973 2/1969 Beers
. 102/66&#226;&#168;102/37.8&#226;&#168;. 102/65
*&#226;&#162; - -&#226;&#160;*
&#226;&#161; .
r&#226;&#168;%
U.S. Patent Jan. 24,1978
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water-tight case provided with floats, a liquid aerosol, a&#226;&#168;core of a pyrotechnic composition having a high calo&#194;&#172;&#226;&#168;rific effect and a device for controlling the ignition of&#226;&#168;the core.
The present invention relates to protection means&#226;&#168;able to be used in an attempt to protect a vehicle, such 5&#226;&#168;as a surface ship from the threat constituted by a missile&#226;&#168;or similar self-propelled offensive device, provided&#226;&#168;with an infra-red guidance system.
For the purpose of protecting a vehicle from an infra-
As known per se, the sudden dispersion into damp air&#226;&#168;of the liquid aerosol contained in the casing causes the&#226;&#168;production of a cloud of considerable dimensions of&#226;&#168;very fine droplets. By causing this dispersion by means&#226;&#168;of a core of a pyrotechnic composition able to give the&#226;&#168;red guided missile, the prior art already proposes plac- 10 iiquid aerosol considerable calorific energy before dis-&#226;&#168;ing at a certain point in space, one or more possible
movable decoys, having infra-red radiation and able to&#226;&#168;be substituted for the vehicle in the guidance system of&#226;&#168;the missile.
persion, the applicants have ascertained that the cloud
of droplets thus created had a brightness spectrum very
close to that of a surface ship, in the sense that it had a
dominant factor in the far infra-red (wave length of&#226;&#168;Protection means of this type remain effective in the 15 betWeen 8 and 14p). The &quot;dilution&quot; of the calorific&#226;&#168;case where the vehicle to be protected is an aircraft. In
fact, the source of infra-red radiation of the aircraft is
energy provided by the pyrotechnic core in a cloud of&#226;&#168;fine droplets of considerable volume makes it possible&#226;&#168;to produce an artificial target able to be substituted for&#226;&#168;the ship in the missile guidance system, both as regards&#226;&#168;its dimensions and its brightness spectrum.
The duration of the above-mentioned elementary&#226;&#168;decoy is brief (of the order of several seconds).
This is why the invention also relates to a method of&#226;&#168;using such decoys, making it possible to obtain an arti&#194;&#172;&#226;&#168;ficial target of substantially constant brightness, able to&#226;&#168;attract the guidance system of the missile for a relatively&#226;&#168;long period of time, in order to enable the ship to es-
constituted essentially by the hot part of its propulsion&#226;&#168;means. The high temperature prevailing in this part&#226;&#168;establishes for the target constituted by this aircraft, an 20&#226;&#168;infra-red source whose brightness spectrum comprises a&#226;&#168;dominant factor in the near infra-red (wave length of&#226;&#168;the order of 4ji). Furthermore, the dimensions of the&#226;&#168;source remain relatively small. Due to this, it is easy to&#226;&#168;re-constitute an artificial target representing a bright- 25&#226;&#168;ness spectrum very close to that of the actual target&#226;&#168;constituted by the aircraft, by means of an appropriate&#226;&#168;pyrotechnic composition. In addition, the considerable&#226;&#168;speed of the aircraft enables it to move away rapidly&#226;&#168;from the positioned decoy or decoys in order that the 30&#226;&#168;explosion of the missile in the vicinity of the latter no&#226;&#168;longer constitutes any danger.
On the other hand, in the case where the vehicle to be&#226;&#168;protected is a surface ship, the above-described solution	, .	.	.	.
remains only slightly effective. In fact, the ship consti- 35 em^ss&gt;v^ decoys according to claim 1, and of setting the&#226;&#168;tutes a target of considerable size, the temperature of decoys in operation one after the other in order to cre-&#226;&#168;which remains relatively low, approximately 15* C ate an artificial moving target of substantially constant&#226;&#168;greater than the temperature of the bottom of the sea. brightness for the missile.
The result of this low temperature gradient is that the Preferably, the elementary decoys are spread by
brightness spectrum of the ship has a dominant factor in 40 means of a launching device such as a rocket, about
the far infra-red (wave length of the order of 10/x) in a which they are initially arranged in successive stages, in
characteristic manner. It is therefore obvious that the order to be ejected radially therefrom. The launching
device is preferably designed to rotate about its own
axis in order that the elementary decoys may be ejected
45 one after the other in a substantially parallel direction.&#226;&#168;First, the decoys will be located virtually in a straight&#226;&#168;line on the surface of the water. It will also be an advan-
According to a second aspect of the present invention&#226;&#168;there is provided a method for attempting to protect a&#226;&#168;vehicle, such as a surface ship, from a threat constituted&#226;&#168;by an infra-red guided missile, which consists in spread&#194;&#172;&#226;&#168;ing in a chosen region of space a plurality of elementary
detection and guidance systems of the missiles must be&#226;&#168;calculated to react essentially to radiation having a&#226;&#168;spectrum similar to that of a ship.
The decoys already employed using infra-red radia&#194;&#172;&#226;&#168;tion are for the most part based on a predetermined&#226;&#168;pyrotechnic composition. The high combustion temper&#194;&#172;&#226;&#168;ature of these compositions and the relatively small&#226;&#168;dimensions of the source of radiation which they form 50 tbe launching device is not modified, except in its bear-
result in a radiation spectrum whose dominant factor is&#226;&#168;in the near infra-red. The proportion of far infra-red in&#226;&#168;this radiation is very slight, approximately one tenth&#226;&#168;that of the near infra-red. Since, in addition, the dimen&#194;&#172;&#226;&#168;sions of the infra-red source constituted by the decoy or 55 and which also seems to move in a certain direction,&#226;&#168;decoys remains limited, it will be understood that the&#226;&#168;chances of deceiving the missile guidance system with&#226;&#168;decoys of this type are slight.
The main object of the present invention is to provide&#226;&#168;an emissive decoy able to constitute an artificial target 60 sive increase in the distance between the ship and mov-&#226;&#168;of considerable dimensions, whose brightness spectrum&#226;&#168;is close to that of the ship to deceive the infra-red guid&#194;&#172;&#226;&#168;ance system of the missile.
According to a first aspect of the present invention&#226;&#168;there is provided an elementary emissive decoy in- 65 to block out the image of the ship to the benefit of the&#226;&#168;tended to be set in operation in an attempt to protect a&#226;&#168;vehicle such as a surface ship from the threat consti&#194;&#172;&#226;&#168;tuted by an infra-red guided missile, comprising in a
tage if the directions of ejection of the decoys are verti&#194;&#172;&#226;&#168;cal and directed downwards, such that the trajectory of
ing, by the ejection of the various decoys.
Putting the decoys into operation successively makes&#226;&#168;it possible to create for the missile the illusion of a mov&#194;&#172;&#226;&#168;ing target which has a substantially constant brightness
Such a &quot;movement&quot; of the artificial target makes it&#226;&#168;possible to divert the missile, the &quot;movement&quot; of the&#226;&#168;target naturally taking place in a general direction re&#194;&#172;&#226;&#168;mote from the trajectory of the ship. With the progres-
ing target, it is clear that, in combination with an appro&#194;&#172;&#226;&#168;priate manoeuver, the ship may escape the field of de&#194;&#172;&#226;&#168;tection of the missile. It may be advantageous to place a&#226;&#168;smoke screen between the ship and this missile, in order
artificial target.
The present invention will now be described, with&#226;&#168;reference to the accompanying drawings in which:
controlled in order to take place in substantially the&#226;&#168;same direction and more precisely in a vertical down&#194;&#172;&#226;&#168;wards direction. Thus, the rocket 18 is gradually light&#194;&#172;&#226;&#168;ened, but its trajectory remains unchanged. In order to
FIG. 1 is a diagrammatic view illustrating a method&#226;&#168;of using a plurality of emissive decoys according to the&#226;&#168;present invention;
FIG. 2 shows a launching device for the decoys,&#226;&#168;which can be used in the method of the invention; and 5 control these ejections in rapid succession, in a substan-
FIG. 3 is a sectional view, to an enlarged scale, on&#226;&#168;line III&#226;III of FIG. 2, showing an elementary emissive&#226;&#168;decoy according to the invention.
In FIG. 1, the reference numeral 10 designates a&#226;&#168;surface ship which is to be protected from an infra-red 10&#226;&#168;guided missile or similar self-propelled offensive device&#226;&#168;12, launched at the ship.
The principle used consists of substituting for the ship&#226;&#168;10, a succession of artificial targets such as 14, each able&#226;&#168;to attract the guidance system of the missile 12 by form- 15 elementary decoys will be distributed on the surface of&#226;&#168;ing for the latter an image similar to that of the ship. The&#226;&#168;succession of targets 14 is produced by setting off one&#226;&#168;after the other a plurality of floating elementary decoys&#226;&#168;16, after having spread these decoys in a given direction&#226;&#168;by means of an appropriate launching device of the 20 stability,&#226;&#168;rocket type 18. Preferably, the elementary decoys 16&#226;&#168;are launched from the rocket 18 in order to float on the
tially constant direction, it is possible to use pyrotechnic&#226;&#168;delays between the successive ejection charges, the&#226;&#168;durection of which delays corresponds to a complete&#226;&#168;revolution of the rocket 18 about itself.
In an equally advantageous variation, ejection of the&#226;&#168;decoys takes place simultaneously stage by stage such&#226;&#168;that the quantity of overall movement resulting from&#226;&#168;these ejections is zero and the trajectory of the rocket&#226;&#168;18 therefore remains unchanged. In this variation, the
the water substantially along a sinusoid.
In both of the above-described methods, it is desirable
that the decoys located in the rear part of the rocket 18&#226;&#168;be ejected first, in order for the rocket retain good
FIG. 3 is a sectional view of an elementary emissive&#226;&#168;projectile according to the invention, in the case where&#226;&#168;one uses a launching rocket 18 such as that illustrated in&#226;&#168;FIG. 2 and which is described in the aforesaid French,
surface of the water in a straight line of predetermined&#226;&#168;direction. In most cases, this direction is different from
the direction of travel of the ship, the latter thus having 25 patent,&#226;&#168;the possibility of manoeuvering in order to increase still&#226;&#168;further the space between the succession of targets 14&#226;&#168;and itself.
The decoy 30 illustrated in FIG. 3 is composed of a&#226;&#168;casing 32 of plastics material, and of general prismatic&#226;&#168;shape and having a cross-section in the form of a sector&#226;&#168;of an annulus. The narrower lower part 34 of the casing
The rocket 18 is designed to launch 150 elementary&#226;&#168;decoys 16. The launching of the first decoy can take 30 32 is intended to be received in the base 36 of the cell 28&#226;&#168;place with a delay, of between 0.3 seconds and 10 sec&#194;&#172;&#226;&#168;onds for example, from the departure of the rocket 18&#226;&#168;from the ship 10.
As will be seen hereafter, the effective duration of
formed between two successive radical fins by two&#226;&#168;adjacent transverse partitions 26 interconnecting these&#226;&#168;fins.
The wider upper part 38 of the casing 32 encloses two&#226;&#168;each artificial target is limited to several seconds. The 35 water-tight compartments 40 forming floats which en-&#226;&#168;delay introduced between the operation of successive&#226;&#168;decoys 16 is calculated so that the brightness of the&#226;&#168;overall artificial target, constituted by the target or&#226;&#168;targets 14 which are still effective, approximates to a&#226;&#168;given value corresponding to the brightness of the ship 40 water.
10 as seen from the missile 12. Therefore the overall
able the casing 32 to float in a satisfactory manner. The&#226;&#168;normal position of the casing on the water is that shown&#226;&#168;in FIG. 3: the lower part 34 is immersed and the upper&#226;&#168;part 38 is located at least partly above the surface of the
As described in the aforesaid patent, part 34 of the&#226;&#168;casing is provided with a pressure cap 42 appropriately&#226;&#168;fixed to the casing 32. This cap defines an inner cylindri&#194;&#172;&#226;&#168;cal recess 44 in which is fitted a radial tubular support
duration of the artificial target may be 10 minutes or&#226;&#168;even more. At the same time as firing the rocket 18, it&#226;&#168;may be advantageous to place a smoke screen 20 be&#194;&#172;&#226;&#168;tween the ship 10 and the missile 12 in order to tempo- 45 member 46 integral with the support structure for the
device 18. A pyrotechnic charge 48 is placed between&#226;&#168;the member 46 and the base 50 of the recess 44 with a
rarily blind the latter and divert it more easily towards&#226;&#168;the first target 14 created close to the ship.
FIG. 2 shows a possible construction of the launching&#226;&#168;rocket 18. This rocket is of the type described and&#226;&#168;claimed in French Patent Number 75.02541 filed on Jan. 50 18, by virtue of the guidance of the cap 42 on the mem-&#226;&#168;28, 1974 in the name of the Applicant for a &quot;Rocket for&#226;&#168;launching decoys .&quot; References may be made to this&#226;&#168;patent for the description and operation of this rocket
view to the ejection of the elementary decoy 30 in a&#226;&#168;radial direction perpendicular to the axis of the device
ber 46.
Ignition of the charge 48 is assured by a pyrotechnic&#226;&#168;band 52 located in the central passage 54 provided in&#226;&#168;the support member 46. However, it will be understood&#226;&#168;Very briefly, the rocket 18 comprises a plurality of 55 that the passage 54 could be reserved for an electrical
ignition connection or any similar means.
The casing 32 comprises mainly a first compartment&#226;&#168;56 closed in a water-tight manner by means of a cover&#226;&#168;58 of appropriate shape and a second compartment 60
radial fins 22 which wind slightly helically around a&#226;&#168;tubular support structure (not shown), and is equipped&#226;&#168;with a powder propellant 24. A plurality of transverse&#226;&#168;partitions 26 define, with the fins 22, a plurality of iden&#194;&#172;&#226;&#168;tical cells 28 of prismatic shape each having a cross-sec- 60 formed inside the first by a water-tight cover 62 appro-&#226;&#168;tion in the form of a circular sector and able to receive
priately fixed by welding for example to the cover 58.&#226;&#168;According to the invention, the compartment 56 is&#226;&#168;filled with a liquid aerosol such as titanium tetrachloride&#226;&#168;or tin tetrachloride and the compartment 60 is filled
an elementary emissive decoy 30.
The launching rocket 18 is also provided with a time&#226;&#168;control device able to trigger the ejection of the various&#226;&#168;elementary decoys 30 according to a predetermined 65 with a pyrotechnic composition 66 having a high calo&#194;&#172;&#226;&#168;rific effect. For example, this composition 66 can be&#226;&#168;constituted by a mixture of aluminum (or boron) and&#226;&#168;potassium perchlorate in appropriate proportions. Igni-
According to a preferred embodiment, described in&#226;&#168;the aforesaid patent, the ejection of successive decoys is
very close to that of a ship, in the sense that is has a&#226;&#168;dominant factor in the far infra-red (wave length of&#226;&#168;between 8 and 14p,). The duration of this source is very&#226;&#168;limited, of the order of several seconds.
It will be understood that the elementary decoy de&#194;&#172;&#226;&#168;scribed with reference to FIG. 3 constitutes the basic&#226;&#168;member which is used for carrying out the method&#226;&#168;described above with reference to FIG. 1.
tion of the composition 66 is assured through a perfo&#194;&#172;&#226;&#168;rated disc 68, by a pyrotechnic primer 70 also housed in&#226;&#168;the cover 62.
Ignition of the primer 70 may be achieved either by a&#226;&#168;pair of pyrotechnic bands having a delay, initiated by 5&#226;&#168;the ejection charge 48, or preferably by an electronic&#226;&#168;ignition circuit 72 having a delay, housed in a compart&#194;&#172;&#226;&#168;ment 74 formed in the upper part 38 of the case 32.
The compartment 56 advantageously comprises a&#226;&#168;certain number of partitions (not shown) intended to 10 the casing 32 is dictated by the shape of the cells 28&#226;&#168;oppose both deformation of the cover 58 and displace- provided on the launching rocket: the latter can be of&#226;&#168;ment in the latter of the liquid aerosol 64.	any appropriate known type. The use of the rocket
The convergent walls 76 of the casing have a corru- described in French Patent No. 75.02541 is given as a&#226;&#168;gated shape in order to have sufficient rigidity in the preferred example, to give the maximum occupation of&#226;&#168;direction of ejection of the casing 32. This corrugated 15 ^e useful volume achieved by the cellular structure of&#226;&#168;shape of the walls 76 also makes it possible to quickly	r0cket.
absorb the kinetic energy of the casing 32 when the&#226;&#168;latter comes into contact with the water.
It will also be understood that the general shape of
Numerous modifications may be applied to the ele&#194;&#172;&#226;&#168;mentary decoy described above: in particular, it is possi-
,	, .	ble to replace the electronic circuit 72 by any other
pyrotechnic composition 66 to the aerosol 64, the struc- 20 appropriate known delay means. The composition 66,&#226;&#168;ture and/or material of the cover 60 or more precisely
of the part of this cover which separates the compart&#194;&#172;&#226;&#168;ments 60 and 56 will be such that this part of the cover&#226;&#168;breaks instantaneously at the time of ignition of the&#226;&#168;composition 66. On the contrary, the structure of the 25&#226;&#168;outer cover 58 and/or the material constituting the&#226;&#168;latter will be such that this case may undergo a consid&#194;&#172;&#226;&#168;erable elongation before bursting at the time of ignition.
The elementary emissive decoy 30 is set in operation&#226;&#168;in the following manner:
At the time tl after the departure of the rocket 18&#226;&#168;from the ship 10, the charge 48 is ignited. As above-&#226;&#168;mentioned, this ignition may advantageously take place&#226;&#168;when the cell 28 containing the decoy is directed down&#194;&#172;&#226;&#168;wards in a substantially vertical direction. The hot gases 35&#226;&#168;resulting from the combustion of the charge 48 press&#226;&#168;against the member 46 in order to expel from the latter&#226;&#168;the cap 42 which forms the base of the casing 32. Simul&#194;&#172;&#226;&#168;taneously, the electronic circuit 72 is triggered, for&#226;&#168;example by disconnection of an electrical connection 40&#226;&#168;connecting this circuit by means of a removable con&#194;&#172;&#226;&#168;nection (not shown) to a continuous electrical supply&#226;&#168;provided on the device 18.
The ejected decoy falls into the water and is stabi&#194;&#172;&#226;&#168;lized by the floats 40 and undulations of the walls 76.
At a time tl fixed by the time constant (possibly ad&#194;&#172;&#226;&#168;justable) of the circuit 72, the primer 70 is ignited and&#226;&#168;ignites the composition 66. As it burns, the latter causes&#226;&#168;considerable heating of the aerosol 54, then its disper&#194;&#172;&#226;&#168;sion into space.
In contact with the damp air, the aerosol hydrolyses&#226;&#168;according to the reaction:
In order to facilitate the transfer of energy from the
the shape of the casing 32, the arrangement of the floats&#226;&#168;40, the method of ejection of the decoys 30, etc. can all&#226;&#168;be modified.
1.	An elementary emissive decoy intended to be set in&#226;&#168;operation in an attempt to protect a vehicle such as a&#226;&#168;surface ship from the threat constituted by an infra-red&#226;&#168;guided missile, comprising a water-tight casing pro&#194;&#172;&#226;&#168;vided with float means, including a first compartment&#226;&#168;and a second compartment a portion of which extends&#226;&#168;within the said first compartment, a liquid aerosol en&#194;&#172;&#226;&#168;closed within the said first compartment, a pyrotechnic&#226;&#168;composition having a high calorific effect enclosed&#226;&#168;within the said second compartment, and means for&#226;&#168;controlling the ignition of the pyrotechnic composition,&#226;&#168;whereby ignition of the pyrotechnic composition forms&#226;&#168;a cloud of droplets of the aerosol while giving it consid&#194;&#172;&#226;&#168;erable calorific energy before dispersion.
2.	An elementary emissive decoy according to claim&#226;&#168;1, wherein the said first and second compartments have&#226;&#168;substantially parallel covers adapted to be forced open&#226;&#168;to permit dispersion of the aerosol, the cover of the said&#226;&#168;second compartment being of less strength than the&#226;&#168;cover of the said first compartment.
3.	An elementary emissive decoy according to claim&#226;&#168;I in which the device for controlling the ignition com&#194;&#172;&#226;&#168;prises an electronic circuit having a delay.
4.	An elementary emissive decoy according to claim&#226;&#168;1, in which the casing has an outer surface which is able&#226;&#168;to retard the motion of the casing it comes into contact&#226;&#168;with the water.
5.	An elementary emissive decoy according to claim&#226;&#168;1, in which is compartmentalised and in which the com&#194;&#172;&#226;&#168;partment that receives the liquid aerosol is provided&#226;&#168;with partitions.
6.	An elementary emissive decoy according to claim
TiCl4 + 4H20 = 4HC1 + Ti(OH)4.
This reaction causes the production of a large cloud&#226;&#168;of fine droplets. The initial heating of the aerosol and&#226;&#168;the &quot;dilution&quot; of this heating in the cloud thus produced&#226;&#168;creates an infra-red source whose radiation spectrum is
1, in which the liquid aerosol is titanium tetrachloride.
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