Abstract:
There is provided an electrically powered augmenter device that has a silicon window. The silicon window emits the infrared radiation from the augmenter in a specific waveband, to attract heat seeking missles. Moreover, the augmenter may be mounted on the fuselage of an unpowered aerial towed target or other airborne vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     (Not Applicable) 
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     (Not Applicable) 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to aerial targets, and more particularly to an improved aerial target decoy which simulates an exhaust of a jet engine through use of an infrared augmenter device having a silicon window. 
     The use of aerial targets to enhance military weapons training is well known. As shown in FIG. 1, aircraft typically tow these aerial targets so that they duplicate battle targets (e.g., enemy aircraft). By providing a scenario which closely resembles a real-life battle situation, target-striking weapons such as anti-aircraft missiles can be launched thereagainst so as to optimize their use and operation. 
     Certain types of aerial targets utilized in the military weapons training are adapted for more sophisticated weaponry such as heat-seeking missiles. These types are not only designed to provide visual indications of the targets&#39; locations, but further emit infrared thermal; signatures. In this respect, military weaponry such as heat-seeking missiles can trace and follow the thermal signatures to strike and destroy those targets that emit them. By incorporating these types of aerial targets into the military weapons training, the operation and use of heat-seeking weaponry can be significantly improved in preparation for real-life situations. 
     Traditionally, gas or liquid fuel powered aerial targets have been used to achieve this purpose. These fuel-burning targets typically operate to heat a mesh or to create an external flame which radiates sufficient thermal signature. However, because such targets require fuel tanks, plumbing, valves and an ignition source, they are complicated and expensive. They also are limited in altitude and airspeed of operation. A further disadvantage is that their infrared emission is primarily directed aft. Thus, they are poorly suited in training pilots to attack an enemy heading toward them. 
     One known solution to this problem is the use of aerial targets manufactured by Global Target Systems Limited of Challock, Great Britain. Generally, a typical aerial target from Global comprises an enclosed housing which places a heater unit therein to selectively emit thermal signatures through its window. Although its targets are believed to be proven effective for their intended purpose, they are extremely expensive to manufacture. Simply put, these targets are too impractical as to cost to serve as one-time target designations. 
     Perhaps the greatest cost factor in manufacturing Global&#39;s aerial targets is the use of zinc-sulphide windows in their targets. In particular, Global&#39;s use of zinc-sulphide windows is due to the fact that they allow frequencies of infrared to radiate therethrough which can be readily detected by heat-seeking weaponry. However, these windows are extremely costly, not to mention that they are often difficult to obtain and/or fabricate. This becomes a tremendous factor when considering that aerial targets, by their inherent nature, are manufactured to be used for one-time target practice. 
     In view of the above-described shortcomings of conventional aerial targets, there exists a need in the art for an aerial target which can be economically manufactured. More specifically, there exists a need for an aerial target adapted for heat-seeking weaponry which generates and emits the required infrared thermal signature therefor, while being mass-producible with mitigated costs. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention specifically addresses and alleviates the above-referenced deficiencies associated with the use of aerial targets of the prior art. More particularly, the present invention is an improved aerial target which simulates an exhaust of a jet engine through use of an infrared augmenter device having a silicon window. This specific augmenter of the present invention is designed to continuously output the required infrared thermal signature in the forward direction as it is advantageously insensitive to mounting orientation. In addition, it is advantageously insensitive to airspeed and altitude. More importantly, however, the present invention&#39;s aerial target decoy uses a silicon window to radiate detectable infrared frequencies therethrough, which is significantly cheaper and more easily obtainable than the conventional windows performing the same. 
     In accordance with a preferred embodiment of the present invention, there is provided an unpowered aerial target for emitting an infrared thermal signature in a specific waveband range (about 3 to 5 microns) when being towed by an aircraft. The present invention features an infrared augmenter device which is engaged to the forward end of a fuselage. However, because the present augmenter device is adapted to consistently emit thermal signature through its window, it would be recognized that the augmenter can be placed any desired location defined on the fuselage. 
     In the preferred embodiment of the present invention, the silicon window may be incorporated into the infrared augmenter device in any sensible fashion, whether it be via conventional or creative means. Preferably, however, the silicon window is mounted in the front end of the augmenter device by an O-ring that acts like a snap-ring. This manner of attachment is further preferred as it helps prevent outside dust and moisture from entering within the device. 
     In operation, an aircraft may tow the present invention&#39;s aerial target by connecting elongated tow line to the target. By doing so, the target becomes airborne but should be far enough from the aircraft (about 2 miles) so that any incoming missiles do not inadvertently harm the aircraft. When airborne, the infrared augmenter device is operative to electrically generate high-intensity heat (about 1,400°F.) therewithin whereat its silicon window allows continuous emission of required infrared signatures of approximately 40 watts per steradian in the 3-5 micron waveband. In this respect, military weaponry such as heat-seeking missiles can be launched to trace these signatures for the purpose of striking and destroying the aerial target that emits them. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These as well as other features of the present invention will become more apparent upon reference to the drawings wherein: 
     FIG. 1 is a side view of an aircraft towing a prior art aerial target (not drawn to scale) when conducting a military weapons training; 
     FIG. 2 is a perspective view of an aerial target utilized for emitting infrared thermal signatures constructed in accordance with a preferred embodiment of the present invention; 
     FIG. 3 is a perspective view of an infrared augmenter device featured in the aerial target of FIG.  2  and comprising a silicon window which is mounted therein; 
     FIG. 4 is a cross-sectional view of the infrared augmenter device of FIG.  3  and illustrating its internally disposed heating elements; and 
     FIG. 5 is a cross-sectional view of the infrared augmenter device of FIG.  3  and illustrating layers of insulation which are strategically arranged therein. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only, and not for purposes of limiting the same, FIG. 2 perspectively illustrates an infrared augmenter device  10  constructed in accordance with a preferred embodiment of the present invention. As indicated above, the infrared augmenter device  10  is adapted to emit an infrared thermal signature  12  in the forward direction  14 . Those of ordinary skill in the art will recognize that the augmenter device  10  may be formed to have a variety of shapes, configurations, geometries and sizes other than for that shown in the provided figures. 
     As shown in FIG. 3, the infrared augmenter device  10  is enclosed in a housing  16 . Although the housing  16  is shaped in a cylindrical configuration, such depiction is exemplary in nature and should not be limited thereto. The housing  16  may be fabricated from any material, but is preferably fabricated from a metallic material, and even more preferably aluminum. 
     Referring more particularly to FIGS.  4  and  5 ,there is provided a plurality of heating elements  24  that are disposed within the internal compartment  22  of the housing  16 . It would be known to a person of ordinary skill in the art that the number of heating elements  24  may vary. For example, there could be only one heating element  24 , or more than three. Rather, it is the concept of generating heat  26  within the internal compartment  22  that should be appreciated. In the preferred embodiment, however, three heating elements  24  should be used for optimization. 
     The three heating elements  24  are concentrically disposed within the internal compartment  22  of the housing  16  (best shown in FIG.  5 ). Although each of the heating elements  24  may be characterized by various shapes and configurations, the ones of the present invention each generally has an a circular configuration. These heating elements  24  further include electrical input terminals  28  which extend and protrude through the back end  20  of the housing  16  (as shown in FIG.  4 ). In this regard, the back end  20  is preferably a metallic backplate, and more particularly an aluminum backplate, which provides sufficient clearance holes  30  for the input terminals  28  to extend therethrough. 
     Referring now to FIGS. 2 and 4, the electrical input terminals  28  are in communication with an electrical power source  31  for supplying power thereto. More specifically, the heating elements  24  can be connected in parallel to the power source  31 . These elements  24  can be sized for 28 VDC, or can be designed in a manner as to be adapted for any type of power. The power source may be located within the fuselage  34 . In the alternative, the requisite electricity may be drawn from an outside power source such as from an aircraft  50  for example through an electrical cable which is elongated within the connecting tow line  52 . Moreover, there is further provided an insulating plate  36  disposed between the back end  20  and the forward end  32  to which the electrical input terminals  28  are mounted. 
     Referring more particularly to FIGS. 3 and 4, the infrared augmenter device  10  comprises a window  38  which is preferably fabricated from silicon. It is expressly stated herein that the use of a silicon window to radiate detectable infrared signature  12  is both advantageous and imperative to the present invention as it is significantly cheaper, sufficiently rugged and more easily obtainable than the conventional windows (e.g., zinc-sulphide windows) performing the same. 
     Preferably, the silicon window  38  is mounted within an opening  42  of the housing&#39;s front end  18  by an O-ring that acts like a snap-ring and further simultaneously mitigating outside dust and moisture from entering within the device  10 . However, it will be recognized by those of ordinary skill in the art that there are other methods of mounting the silicon window  38  within the housing  16 . 
     The silicon window  38  is preferably an anti-reflective window. In this respect, the silicon window is coated with an anti-reflective material. Moreover, as shown in FIGS. 4 and 5, there may further comprise insulation layers  48  which are selectively positioned within the internal compartment  22  of the housing  16  in a manner as to expo se the silicon window  38  to the generated heat  26 . Of course, these insulation layers  48  protect the housing  16  from heat  26  and further reduce heat losses in operation. 
     In operation, an aircraft  50  is utilized to tow the present invention&#39;s aerial target  40  by connecting an elongated tow line  52  thereto. However, it should be recognized by those of ordinary skill in the art that the present target  40  may be adapted for use with a variety of other vehicular structures (e.g., tanks, jeeps, gunboats, manned and unmanned fixed-wing aircraft and helicopters, etc.) 
     In particular, one end of the tow line  52  is connected to the aircraft  50  while the other end is connected to the fuselage  34 . By doing so, the decoy  40  becomes airborne but it should be emphasized that the decoy  40  should be sufficiently distanced from the aircraft  50  (about 2 miles)i so that any incoming missiles do not inadvertently harm the aircraft  50 . 
     When the present decoy  40  is airborne, the heating elements  24  are operative to electrically generate high-intensity heat  26  (about 1,4000° F.) within the internal compartment  22 . These heating elements  24  produce radiant heat  26  which is radiated through the silicon window  38  whereat the silicon window  38  allows continuous emission of required infrared signatures  12 . These signatures  12  are approximately 40 watts per steradian in the 3-5 micron waveband which are selected frequencies associated with infrared engines. In this respect, military weaponry such as heat-seeking missiles can be launched to trace these signatures  12  for the purpose of striking and destroying the aerial target  40 . 
     Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art. Thus, the particular combination of parts described and illustrated herein is intended to represent only certain embodiments of the present invention, and is not intended to serve as limitations of alternative devices within the spirit and scope of the invention.