Abstract:
A small arms firing effects simulator utilizes a modular construction to  egrate with the magazine of a weapon such as a rifle. The modular design resembles the ammunition clip and houses an expendable plastic coated plurality of pyrotechnic charges. An electrical control circuit is also housed within the module and serves to interface the pyrotechnic charges with the firing of the weapon, including semi-automatic and automatic firing as well as disabling the weapon when all rounds have been fired.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to military weapons and particularly to apparatus for simulating the sound and flash thereof. More particularly, the present invention may be described as an electronically controlled pyrotechnic sound and flash simulator for use with small arms training. 
     2. Description of the Prior Art 
     In recent years, the armed forces have placed an increasing emphasis on the realism of battlefield training conditions. In U.S. Pat. No. 3,836,919 entitled &#34;Small Weapons Noise Simulator,&#34; which issued June 3, 1958 to Edwin R. DuBois, there is shown an electro-mechanical small weapons noise simulator which can be attached to a weapon. 
     Currently with regard to the standard M16 automatic weapon, the armed forces use blanks and a blank fire adapter. The sound levels produced by this method are far below that of live round fire. Inasmuch as each M16 blank is estimated to cost at least 8.5 cents, training with such is quite expensive. 
     SUMMARY OF THE INVENTION 
     The present invention represents a cost effective means for simulating small arms fire without modifying the weapon and without the use of mechanical actuation, other than in electrical switches. The present invention utilizes a low cost plastic expendable housing a metal/oxidizer pyrotechnic in conjunction with an electrical ignition system. The expendable would contain a plurality of rounds and would be installed in a firing unit which can be inserted into the weapon via the magazine breech. The invention produces sound and flash by the electrical ignition of the pyrotechnic in a confined space and venting the combustion produced in a manner which utilizes the weapon&#39;s ejection port. The electrical control circuit provides for automatic and semiautomatic fire, and interfaces with the weapon trigger and bolt. 
     It is an object of this invention to provide a realistic simulation of small arms fire noise and flash. 
     Another object of the invention is to provide an inexpensive means to provide realistic training using an actual weapon. 
     Yet another object of the invention is to provide a reliable, low maintenance, reusable small arms training device. 
     Another object of the present invention is to provide a pyrotechnic simulation of small arms fire without dangerous pressuration of the ignition chamber. 
     The foregoing and other objects, features and advantages of the invention, and a better understanding of its construction and operation, will become apparent from the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of the electrical control circuit; 
     FIG. 2 is a schematic diagram of the electrical control circuit; 
     FIGS. 3a and 3b are an illustration of the expendable; and 
     FIG. 4 is an illustration of the expendable within the firing unit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The circuitry of the Small Arms Firing Effect Simulator (SAFES) consists of ten functional blocks as shown in FIG. 1, plus battery and expendable as shown in FIG. 3. Referring to FIG. 1, the embodiment shown in the block diagram utilizes a bolt interface 10, a trigger interface 20, an oscillator control 30, a 500 Hertz oscillator 40, a 10 Hertz oscillator 50, a firing counter 60, firing decoder 70, firing control 80, firing sensors 90, and a Multiple Integrated Laser Engagement System (MILES) interface 19. 
     The implementation of the functional block diagram is shown in FIG. 2 utilizing seven CMOS IC&#39;s, thirty-one SCR&#39;s, five diodes, six capacitors, seventy-four resistors, and three switches. 
     The bolt interface 10 is constructed to provide a realistic simulation of operator actions as would occur during the firing of live rounds. This is accomplished through a microswitch 101 that engages the weapon&#39;s bolt as it travels. As shown in FIG. 2, switch 101 is connected to relay 102 and resistor 103. When the weapon bolt is open, or the SAFES unit is out of the weapon, switch 101 is closed, allowing relay 102 contacts to open. With relay 102 open, pyrotechnic charges 11 cannot be fired, a safety precaution which duplicates the action of the weapon. 
     When the ganged selector switches 208 and 209 are turned to the &#34;Semi&#34; or &#34;Auto&#34; position, the R-C combination of resistor 104 and capacitor 105 resets a bolt flip-flop 106. Flip-flop 106 provides signals to the oscillator control circuit 30 and the firing counter 60, inhibiting their action. Flip-flop 106 is set by the action of microswitch 101, which is debounced through the use of resistor 102 and a capacitor 107 in conjunction with a Schmitt trigger 108. 
     Trigger interface 20 utilizes a resistor 201, a resistor 202, a capacitor 203, a Schmitt trigger 204, and a dome switch 205, which is normally open. The action of switch 205 is debounced by the R-C time constant of resistor 202 and capacitor 203. The fall in voltage is detected by Schmitt trigger 204 and when triggered, the output of Schmitt trigger 204 goes high. Schmitt trigger 204 has its output connected to the semi position of selector switch 208 and to an input to a NAND gate 501 in 10 Hertz oscillator 50. 
     Oscillator control 30 uses a D flip-flop 301, a NAND gate 302, and an inverter 33. Flip-flop 301 is clocked by the signal from trigger interface 20 when selector switch 208 is in the semi position, and by the output of 10 Hertz oscillator 50 in the auto position. The level of the input to flip-flop 301 from bolt interface 10 determines the state of the output to 500 Hertz oscillator 40 when flip-flop 301 is clocked. If bolt actuation has taken place, 500 Hertz oscillator 40 is enabled. Flip-flop 301 is reset, inhibiting 500 Hertz oscillator 40, only by a signal from firing sensor 80. 
     NAND gate 302 serves to control the output of 500 Hertz oscillator 40 and provides CLK signals used as timing pulses by firing counter 60 and firing decoder 70. Inverter 303 is used to invert part of the CLK signal to CLK signal, which is also used by firing counter 60 and firing decoder 70. 
     500 Hertz oscillator 40 is comprised of a NAND gate 401, an inverter 402, resistors 403 and 404, and a capacitor 405. The input to NAND gate 401 comes from flip-flop 301, with the other input to gate 401 tied to ground via resistor 404 and capacitor 405. When the input from flip-flop 301 is high, 500 Hertz oscillator 40 runs; when the input is low, oscillator 40 is inhibited. The running frequency of oscillator 40 is determined by the values of resistor 403 and capacitor 406. Resistor 404 provides feedback to allow NAND gate 401 to change states. The output of gate 401 is inverted by inverter 402 and input to NAND gate 302. 
     10 Hertz oscillator 50 utilizes NAND gates 501 and 502, resistors 503 and 504, and capacitor 505. NAND gate 501 is controlled by the signal input from inverter 204 of trigger interface 20. When said signal is high, that is, when the trigger is squeezed, 10 Hertz oscillator 50 operates. The values of resistor 504 and capacitor 505 determine the running frequency. Resistor 503 provides the feedback required to allow NAND gate 501 to changes states. The output of gate 501 serves as the input to gate 502, which has its output connected to the auto position of switch 208, thus reclocking flip-flop 301 at a 10 Hertz rate in the auto mode. 
     Firing counter 60 consists entirely of a dual binary counter, such as a MC14520. Counters 601 and 602 are held in a reset mode until the actuation of bolt interface 10. A low signal from flip-flop 106 enables counters 601 and 602 to accumulate the CLK and CLK signal, respectively. The outputs of each counter is then fed into one-half of firing decoder 70. 
     Firing decoder 70 of FIG. 1 consists of firing decoders 701 and 702. Firing decoders 701 and 702, as shown in FIG. 2, are two 4-bit latch/4 to 16 line decoders, such as MC14514&#39;s. Decoder 701 receives the count from the CLK counter 601 and decodes it to provide a single pulse on the appropriate line of the sixteen outputs. Decoder 702 performs the same function, but receives its input from CLK counter 602. The outputs of decoders 701 and 702 are connected to the gate resistors 901 through 963 of firing control 90. 
     The outputs of decoders 701 and 702 are inhibited by a signal derived from oscillator control circuit 30, thus providing a means of stopping the drive to firing control 90 while maintaining the decoded count. 
     Firing control 90 utilizes thirty-one SCR&#39;s of the MCR-106 type, and sixty-two gate resistors. Resistors 901 through 963 are placed in pairs between ground and firing decoder 70 at the gate of each SCR 965 through 995. This is to limit the gate current required from decoders 701 and 702 and to provide temperature stability against false triggering. 
     The anodes of the odd numbered SCR&#39;s 965 through 995 are connected to the contact of relay 102. The cathodes of odd numbered SCR&#39;s 965 to 995 are connected to the appropriate side of each pyrotechnic charge 11. The even numbered SCR&#39;s 966 to 994 have their cathodes tied to ground and their anodes tied to one side of their appropriate charge 11. 
     When relay 102&#39;s contacts are closed, SCR&#39;s 965 to 995 can be triggered by firing decoders 70. The trigger timing is controlled such that only two SCR&#39;s are enabled at any time, thus current can only flow through one charge at a time. Each SCR 965 to 995 is triggered until an unexpended charge is found, then the triggering stops until the next fire command is given. 
     Firing sensor 80 consists of diodes 801, 802, and 803, a voltage comparator 804, capacitor 806, resistors 807, 808, 809, and 811, and inverter 805. These components are connected to provide a signal to oscillator control 30 and a MILES interface at the moment a charge 11 fires. This was accomplished by placing diodes 801 and 802 in the current path which supplies SCR&#39;s 965 to 995. The voltage across diodes 801 and 802 is monitored by voltage comparator 804. When current flows through the diodes, firing control 90 has sequenced to an unexpended charge. The resultant voltage drop across the diodes is sensed and forces the output of comparator 804 high. This output is inverted by inverter 805 and used to reset oscillator control flip-flop 301, turning off 500 Hertz oscillator 40. 
     MILES interface 19 is simply a diode 19, whose cathode is connected to the output of firing sensor 80, connected to the trigger of the MILES unit associated with the weapon. 
     The particular firing control circuitry shown in FIG. 1 and described hereinabove is for a 30-round magazine insert for use in training combat troops with an M16 rifle with a MILES unit attached thereto. To further enhance the realism, the small arms firing effect simulator is packaged to resemble the magazine clip of the M16. Referring to FIG. 3, the small arms firing effect simulator is packaged within a reusable housing 21 having an upper end 211 and a lower end 212. Upper end 211 is designed for insertion into an M16 in the manner of a magazine clip, said upper end 211 having an exhaust port 213 designed for cooperation with the ejection port of said M16 rifle. Exhaust port 213 communicates with lower end 212 via an upper exhaust chamber 214 with upper end 211. Within upper exhaust chamber 213 is port spring 215 designed to maintain reusable housing 21 in cooperative relation within said M16 rifle. 
     Within upper end 211, switch 101 of bolt interface 10 is positioned for cooperation with the bolt of said M16. Also within upper end 211 is a battey compartment 216 for housing power supply 207. 
     Lower end 212 houses the electric control circuitry and the plastic expendable 12 which contains pyrotechnic charges 11. A lower exhaust chamber 217 communicates with upper exhaust chamber 214 to provide a path for the discharge of gases generated by the explosion of pyrotechnic charges 11. 
     Selector switch 208 is mounted on lower end 212, as is trigger overlay 218 for connecting trigger interface 20 to the weapon. 
     Plastic expendable 12 is mounted within a hinged chamber block 219 which forms lower exhaust chamber 217 and holds expendable 12 in place in a receiver block 220. Receiver block 220 has contact pins 221 which serve to connect firing control 90 with pyrotechnic charges 11. 
     Plastic expendable 12 is designed to be fabricated in an automatic process, thereby reducing cost. The configuration of expendable 12 is as shown in FIG. 4. Expendable 12 is a series of thirty cups 121, with bridge wire 111 at the bottom of each cup 121. Bridge wire 111 makes contact to a silk-screened conductive area 122 between each cup 121. Conductor area 122 makes contact with contact pins 221, thus connecting to firing control 90. 
     Referring to FIG. 3, each cup 121 has within it a pyrotechnic charge 11 which is a shaped pyrotechnic pellet composed of 75% potassium perchlorate, 15% black powdered aluminum, and 10% dextrose. Each pellet is sealed within a cup 121 by a plastic sealant 124 such as RTV silicone. The entire expendable structure is encased in a plastic casing 126. 
     The concept behind the small arms firing effect simulator is that of an electrical ignition of pyrotechnic charge 11 by heating bridge wire 111 to incandescence. Charge 11 burns in a combination mode to produce a quantity of combustion by-products, which, being contained in a fixed volume, produces a rapid increase in pressure. At some point, the pressure will be great enough to rupture plastic sealant 124 covering the exit orifice. The shock of the rupture and the ensuing venting of pressure from chambers 214 and 217 via exit port 211 produces overpressure levels and duration which simulate small arms fire. 
     While the invention has been described with reference to a preferred embodiment, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions or other changes not specified may be made which will fall within the purview of the appended claims.