Abstract:
An ammunition propellant temperature measuring assembly comprising a firstemperature measuring device for determining at least two surface temperatures of a round of ammunition and for transmitting a first signal indicative of the surface temperature, a second temperature measuring device for determining ambient temperature in a storage area for the ammunition and for transmitting a second signal indicative of the ambient temperature, and computer apparatus for receiving the first and second signals and a temperature profile for the ammunition, and adapted to compute therefrom a propellant temperature of the round.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured, used and licensed by or for the Government for Governmental purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to the measurement of temperature of ammunition, and is directed more particularly to the measurement of ammunition propellant temperature on a round to round basis. 
     2. Description of the Prior Art 
     In the gun fire systems of tanks and other armored vehicles, it has been known that the temperature of a round of ammunition plays a role in gun firing accuracy. 
     It is common in such vehicles to provide a temperature gage in the ammunition storage compartment of the vehicle to measure the air temperature in the compartment. Once measured, the air temperature is manually entered into a ballistic computer. Such a system requires that the rounds be stabilized to the ambient temperature in the storage compartment which, in turn, sometimes requires that old rounds be fired before newly stored rounds. 
     It has recently become known that the propellant temperature of a round has a significant bearing on gun firing accuracy. Under the prior art system, there is no means by which to measure propellant temperature of a single round at any given time, particularly while the round is being loaded into a gun. 
     Accordingly, there is a need, in a gun fire control system, for an ammunition propellant temperature measuring means which has the capability of determining the propellant temperature of individual rounds as they are loaded into the breach of an associated gun. 
     SUMMARY OF THE INVENTION 
     It therefore is an object of the invention to provide an assembly for measuring the propellant temperature of ammunition. 
     A further object of the invention is to provide such an assembly for effecting such measurements on a round by round basis. 
     A still further object of the invention is to provide such an assembly as is capable of effecting such measurements on a given round during the loading of that round into the breech of an associated gun. 
     With the above and other objects in view, as will hereinafter appear, a feature of the invention is the provision of an ammunition propellant temperature measuring assembly comprising a first temperature measuring device for determining at least two surface temperatures of a round of ammunition and for transmitting a first signal indicative of the surface temperatures, a second temperature measuring device for determining ambient temperature in a storage area for the ammunition and for transmitting a second signal indicative of the ambient temperature, and computer means for receiving the first and second signals and a temperature profile for the ammunition, and adapted to compute therefrom the propellant temperature of the round. 
     The above and other features of the invention, including various novel details of construction and combinations of parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular assembly embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference is made to the accompanying drawings in which is shown an illustrative embodiment of the invention, from which its novel features and advantages will be apparent. 
     In the drawings: 
     FIG. 1 is diagrammatic illustration of one form of measuring assembly illustrative of an embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, it will be seen that the illustrative assembly is associated with a breech B of a gun G and is adapted to act upon a round R of ammunition having surfaces S 1  and S 2 , and in which there is disposed a propellant P. Prior to firing, the round R is loaded into the breech B. 
     The inventive assembly includes a first temperature measuring device 10 which projects an infrared sensing beam 12 for measurement of the surface temperature of the round R just prior to the entry of the round R into the breech B. The first temperature measuring device 10 preferably is an infrared transducer, known in the art. One such transducer found acceptable is known as the Series 3000 transducer, produced by Everest Interscience, Inc. The operation of the first temperature measuring device 10 is based upon the fact that the round surfaces S 1  and S 2  emit infrared energy, as do all surfaces. The wavelengths of the emitted energy relate to the temperatures T S1  and T S2  of the surfaces S 1  and S 2  respectively. The surfaces S 1  and S 2  of the round R also reflect infrared radiation emitted by surrounding surfaces. The infrared temperature measuring device, that is, the first temperature measuring device 10, is able to receive a portion of the infrared radiation emitted and reflected by the surface S 1  and S 2  of the round R and, from it, generate at least two corresponding surface temperatures T S1  and T S2 . With respect to the specific examples illustrated by equations 1 through 4, the first surface temperature T S1  refers to a cartridge case temperature Tc; and the second temperature T S2  refers to a stub case temperature Ts. With respect to the specific examples illustrated by equations 5 through 8, the first surface temperature T S1  refers to a cartridge case temperature Tc; and the second temperature T S2  refers to an average warhead (projectile) surface temperature Tw. 
     The assembly herein further includes a second temperature measuring device 14 disposed in an ammunition storage compartment 16 from whence are taken the rounds for the gun G. 
     A computer means 18, which may include a microcomputer 20 and a ballistic computer 22, is provided. If the computer means 18 includes the microcomputer 20 and the ballistic computer 22, the microcomputer 20 is adapted to receive signals from the first and second temperature measurement devices 10, 14. 
     The first temperature measuring device 10 is adapted to transmit a first signal 24 indicative of the measured surface temperatures of the round to the microcomputer 20. Similarly, the second temperature measuring device 14 is adapted to transmit a second signal 26 indicative of the ambient temperature T A  in the ammunition storage compartment 16, to the microcomputer 20. 
     As noted above, the microcomputer 20 is adapted to receive the signals 24, 26 from the first and second temperature measuring devices. The microcomputer 20 is further adapted to receive and retain a temperature profile 28, which may be entered into the microcomputer 20 manually or by automatic means. The microcomputer 20 is adapted to compute from the first and second temperature signals 24, 26 and from the temperature profile 28, the temperature of the propellant P in the particular round R entering the breech B, and to transmit a signal 30 to the ballistic computer 22, the signal being indicative of the computed temperature of the propellant. The ballistic computer is then able to refine the expected trajectory of the round, and thereby enhance accuracy of the round upon firing. 
     Mounted proximate the first temperature sensing device 10 is a position sensor 32 which projects a beam 34 of energy, such as a light beam, onto a reflector 36 which reflects the beam 34 back to the sensor 32. The energy beam 34 may, alternatively, be an infrared beam. If so, the beam comprises infrared wavelengths significantly different from those associated with the first temperature sensor 10, so as not to interfere with the first temperature sensor. Upon interruption of the beam 34 by movement of the round R toward the breech B, the sensor, after a slight delay, usually of about one-half second, sends a wake-up call 38 to the first temperature measuring device 10 to activate the device 10. The wake-up call 38 is delayed so as not to activate the first temperature measuring device 10 upon momentary interruption of the energy beam 34, as by movement of an operator&#39;s hand therethrough. 
     When the above-described assembly is used in a tank, or similar vehicle, the position sensor 22, first temperature sensor 10, and computer means 18 may be supported by brackets 40 fixed to a gun turret top portion 42, or other relatively stable structural element. 
     It is to be understood that the present invention is by no means limited to the particular assembly herein disclosed and/or shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims. For example, the computer means 18 may comprise a single ballistic computer with capability of performing the tasks above assigned to the microcomputer. When two computers are used, as described above, the microcomputer may, rather than sending the signal 30 to the ballistic computer, simply display the propellant temperature which may then be entered manually into the ballistic computer. The propellant temperature may be displayed on a display 33. The second temperature measuring device 14 may be electrical or mechanical. If electrical, it is contemplated that the device 14 will send the signal 26 directly to the microcomputer 20, as described above and as illustrated in. FIG. 1. However, if the second temperature measuring device is mechanical, the storage compartment ambient temperature may be displayed and manually input into the microcomputer. 
     Further, though mention is made above of the utility of the assembly in tank and armored vehicle environments, it will be apparent that the assembly described herein is applicable to any gun operated by a computerized fire control system, such as fixed emplacements, naval gun turrets, and the like. 
     There is thus provided an ammunition propellant temperature measuring assembly which effects measurement of the propellant temperature of an individual round of ammunition at the last moment before the round enters the breech of the gun. 
     Attached are formulas or equations for the Algorithm to convert surface temperatures to propellant temperatures for various rounds of ammunition. These formulas or equations correspond to the temperature profile of the ammunition and are indicative of a relationship between the first temperature signal 24 (representative of the measured two surface temperatures of the round R), the second temperature 26 (representative of the ambient temperature in the ammunition storage compartment 16), and the temperature of the propellant P. ##EQU1##